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c!J~p~!! - '- QA Halliburton Company - FIELD INVESTIGATION TEAM ACTIVITIES AT UNCONTROLLED HAZARDOUS SUBSTANCES FACILITIES - ZONE I NUS CORPORATION SUPERFUND DIVISION *64412* 64412 SUBMITTED BY: FINAL DRAFT PRELIMINARY ASSESSMENT RAMSEY MOTORS ST. THOMAS, U.S. VIRGIN ISLANDS PREPARED UNDER TECHNICAL DIRECTIVE DOCUMENT NO. 02-8902-42 CONTRACT NO. 68-01-7346 FOR THE ENVIRONMENTAL SERVICES DIVISION U.S. ENVIRONMENTAL PROTECTION AGENCY MARCH 24, 1989 NUS CORPORATION SUPERFUND DIVISION ~ t~c&.. DIANE TRUBE G 02-8902-42-PA REV. NO. PROJECT MANAGER REVIEWED/APPROVED BY: JOSE~%P:r SITE ANAGER R NALD M. NAMAN FIT OFFICE MANAGER - - 02-8902-42-PA Rev. No. 0 POTENTIAL HAZARDOUS WASTE SITE PRELIMINARY ASSESSMENT PART I: SITE INFORMATION 1. Site Name/Alias Ramsey Motors Street Route 384 City Tutu District, St. Thomas State U.S. Virgin Islands Zip 08002 2. County __ N'--/A.......,_ __________ _ County Code NIA Cong. Dist. N/A 3 EPA ID No. New Site .........._,.........,..............c ________ _ 4. Latitude 18° 20' 4 1 " Longitude _64_ 0_5_3_' 2_0'--"------- USGS Quad. Eastern St. Thomas, U.S. Virgin Islands 5. Owner Rita Ramsey Street Route 384, Tutu District City St. Thomas 6. Operator Same as above Street N/A City N/A 7. Type of Ownership [El Private D Federal □County D Municipal 8. Owner/Operator Notification on File 0RCRA3001 Date (E] None D Unknown 9. Permit Information Permit Permit No. None 10. Site Status [El Active □Inactive 11. Years of Operation Unknown Tel. No. (809) 775-4900 State U.S. Virgin Islands Tel. No. N/A State N/A □State D Unknown D Other 0 CERCLA 103c Date Date Issued Expiration Date D Unknown to Present Zip 08002 Zip N/A Comments - 02-8902-42-PA Rev. No. 0 12. Identify the types of waste units (e.g., landfill, surface impoundment, piles, stained soil, above- or below-ground tanks or containers, land treatment, etc.) on site. Initiate as many waste unit numbers as needed to identify all waste sources on site. (a) Waste Management Areas Waste Unit No. 1 Waste Unit Type Facility Name for Unit Waste Oil Drums Drums (b) Other Areas of Concern Identify any miscellaneous spills, dumping, etc. on site; describe the materials and identify their locations on site. Waste oil was discharging onto the Ramsey Motors property from the adjacent Gassett Motors property. 13. Information available from Contact Amy Brochu Preparer Joseph Mayo Agency U.S. EPA Tel. No. (201) 906-6802 Agency NUS Corp. Region 2 FIT Date -"--03=/-=2~4/c..;:8=9 ___ _ ,:·•4{){.) - 02-8902-42-PA Rev. No. 0 PART II: WASTE SOURCE INFORMATION For each of the waste units identified in Part I, complete the following six items. Waste Unit 1 Drums Waste Oil Drums 1. Identify the RCRA status and permit history, if applicable, and the age of the waste unit. There are no known current or previous RCRA permits for the Ramsey Motors Site. The age of the waste unit is unknown. The Water and Power Authority (WAPA) stopped accepting waste oil, which it used for fuel, in 1986 when it was found to contain PCBs. Since that time nearly all waste oil on St. Thomas has been stored, as there is no acceptable method of disposal. 2. Describe the location of the waste unit and identify clearly on the site map. The waste unit is located inside an overhang garage in the northeast corner of the Ramsey Motors property. 3. Identify the size or quantity of the waste unit (e.g., area or volume of a landfill or surface impoundment, number and capacity of drums or tanks). Specify the quantity of hazardous substances in the waste unit. 4. Twenty-five 55-gallon drums of waste oil are stored along the inside perimeter of an automotive repair garage. Identify the physical state(s) of the waste type(s) as disposed of in the waste unit. The physical state(s) should be categorized as follows: solid, powder or fines. sludge. slurry. liquid, or gas. The drums on site contain automotive waste oil, which is a liquid. 5. Identify specific hazardous substance(s) known or suspected to be present in the waste unit. The waste units contain automotive waste oil. Readings ranging from 10 to 90 ppm and 60 to 300 ppm were detected on the HNu photoionization detector and OVA flame ionization detector, respectively, in open drums in the garage. Substances such as gasoline, kerosene, and degreasing solvents may also be present in the drums. 6. Describe the containment of the waste unit as it relates to contaminant migration via groundwater, surface water, and air. The waste oil drums are located inside a garage on a cement floor. Some of the drums were open, and there were spills on the floor of the garage. Small quantities of oil apppeared to be leaking out of the garage onto the soil. Ref. Nos. 1 20 21 - 02-8902-42-PA Rev. No. 0 PART Ill: HAZARD ASSESSMENT GROUNDWATER ROUTE 1. Describe the likelihood of a release of contaminant(s) to the groundwater as follows: observed, alleged, potential, or none. Identify the contaminant(s) detected or suspected, and provide a rationale for attributing the contaminant(s) to the facility. 2. The likelihood of a release of contaminants to the groundwater from the waste unit on site is small. Although some of the drums were not properly closed, all the drums were stored inside on a cement floor. There are no berms or curbs to contain the waste in the event of a spill. The drums contain automotive waste oil. Air monitoring instrument readings inside the drums ranged from 10 to 300 ppm. This suggested that the drums may contain volatile components, possibly gasoline, kerosene, or degreasing solvents. These substances are typically associated with automotive facilities. Ref. No. 1 Describe the aquifer of concern; include information such as depth, thickness, geologic composition, permeability, overlying strata, confining layers, interconnections, discontinuities, depth to water table, groundwater flow direction. The rock units of St. Thomas and St. John are divided into three major groups. The Water Island Formation, which is late lower Cretaceous in age, consists of keratophyre and spillates. The Virgin Island Group, which is probably early Cretaceous or Albian in age, consists of andesitic-pyroclastic rocks and sedimentary formations. The Virgin Island Group is divided into four formations: The Louisenhoj Formation, which consists of augite-andesite breccia, tuff, and conglomerate; the Outer Brass Limestone which consists of partially silicified- tuffaceous-radiolarian-limestone; the Tutu Formation, which consists of tuffaceous wacke, including megabreccia near the base and limestone near the top; the Hans Lollik Formation which may be Eocene in age consists of augite-andesite breccia and tuff. The final group is made up of one or more dioritic plutons. These unamed dikes and plugs of quartz - andesine hornblende - porphory are Upper Cretaceous and Lower Tertiary in age. Alluvian deposits are quarternary in age. The Water Island Formation which consists of 95 percent volcanic flow breccias was probably extruded on a relatively level ocean floor. The absence of terrigenous sediments from this formation indicates that there were no emergent islands present in the area at the time of extrusion. Emergent islands would have served as a source of weather sediments or detritus, which is not present in this formation. There is evidence that sea floor subsidence occurred during the greater part of the accumulation of this formation. However, the subsidence was not rapid enough to maintain a constant water level thereby causing explosive erruptions near the top of the formation. Regional uplift occurred near the end of the Water Island. The Louisenhoj Formation of the Virgin Island Group unconformably overlies the Water Island Formation and crops out on about half of the land area on St. Thomas. Pillsbury sound between St. Thomas and St. John was the origin of this formation. Evidence of this center is based upon the coarseness of volcanic ejecta in the formation in nearby eastern St. Thomas and western St. John. Material is less coarse and tuffs are more predominant as you move further east and west away from the center or origin. This Augite-andesite formation ranges in thickness from 4,000 to 13,000 feet. In certain areas of St. Thomas and St. John conglomerates are interbedded with andesitic rocks at the base of this formation. The depositional environment of this conglomerate varies from location to location throughout· formation. ; :. _; ; (; () L :.:;~if.():.:~· - 02-8902-42-PA Rev. No. 0 The Outer Brass Formation of the Virgin Island Group is mostly siliceous limestone which overlie the Louisenhoj, Formation. This limestone formation is an offshore deposit formed by radiolarian and foraminiferal remains including a minor amount of tuff. Thicknesses are known to be up to at least 600 feet. Overlying the Outer Brass Formation is the Tutu Formation. Tutu Formation is fine to coarse- grained volcanic wackes, which is termed flysch. This formation is derived from eroding sediments from the Louisenhoj andesites. Exposed thicknesses are known to be as much as 6000 feet. Within this formation, a megabreccia lithofacies with an average thickness of 30 feet and a limestone member with thickness up to 300 feet is worth mentioning. The Hans Lollik Formation which consists of at least 10,000 feet of augite-andesite pyroclastic rocks, crops out on Little Hans Lollik Island. Dioritic plutons are located in Pillsbury Sound between St. Thomas and St. John; the narrows, between St. John and the British Virgin Islands; and south of St. Thomas. The exact delination of these plutons are uncertain. Throughout the islands isolated dikes of quartz-andesine porphyries, andesine - hornblendes porphyries, lamprophyres, breccias and pegmatites appear. Folding occured after the deposition of the Virgin Island Group. Rocks were tilted to form a northward-dipping homocline, which is cut by sets of faults trending N 45"W, N 55°E and north. Well defined joint sets parallel each of the major fault trends. Dips range from 15° to 90° with the average being 40°. Strike-slip faults have horizontal offsets of less than 1 mile. Two major strike-slip graben structures or fault systems exist. The first passes through Redhook, St. Thomas and the eastern of Lovango Cay. The second crosses St. John, from Contact Point on the southwest to Brown's Bay on the northeast. Most recently Pleistocene to Holocene alluvial deposits occurred primarily in coastal embayments. However, a narrow bank of alluvium extends up to turpentine run on the east end of the island. Most of these deposits are composed of silt, clay, and thin, discontinuous beds of sand and gravel. Maximum thickness of these is 50 feet. Groundwater movement is limited to openings and joints along fault zones. Regional geologic information is insufficient to determine whether these fractures and fault zones are present in all of the above-described formations; however, for this report it is assumed that the fractures and fault zones are present in all of these formations. The valleys on the island are the result of weak zones caused by faulting and jointing and are primary recharge areas for groundwater. Alluvial deposits have a high porosity but low permeability, making this aquifer unfavorable for groundwater production. In coastal embankments throughout the island, saltwater intrusion is widespread in alluvial deposits. In most areas, alluvial deposits are interconnected with bedrock and act to recharge precipitation to the underlying bedrock. The direction of groundwater flow in the Turpentine Run Basin Aquifer is south-southeast which is generally along the direction of flow of turpentine Run. Depth to groundwater in the aquifer ranges from 5 to 60 feet, and the altitude of the water levels ranges from 1 to 209 feet above mean sea level. Ref. Nos. 11, 16 3. Is a designated sole source aquifer within 3 miles of the site? No sole source aquifer, as designated in the Federal Register, is located within 3 miles of the site. Ref. No. 8 i L .. 1 I 02-8902-42-PA Rev. No. 0 4. What is the depth from the lowest point of waste disposal/storage to the highest seasonal level of the saturated zone of the aquifer of concern? Drums in the waste unit were stored on a cement floor at ground level. Depth to groundwater in Virgin Island Housing Authority (VIHA) well Nos. 1 and 2 was reported to be 56 and 60 feet, respectively. The VIHA wells are located about 900 feet southeast of Ramsey Motors. There is a well on the Ramsey Motors property that is used for washing cars. The well is approximately 100 feet deep, but the depth to water in the well is unknown. Ref. Nos. 1, 2, 9 5. What is the permeability value of the least permeable continuous intervening stratum between the ground surface and the aquifer of concern? There are no continuous intervening strata between the ground surface and the bedrock aquifer. Soils are generally thin in the area around the site. The water-bearing formations in the Turpentine Run Basin Aquifer are composed primarily of fractured and jointed volcanic rocks. The range of hydraulic conductivities associated with these formations is 1 Q-3 to 1 o-s cm/sec. Ref. Nos. 10, 11, 16 6. What is the net precipitation for the area? Net precipitation is usually calculated by subtracting mean annual lake evaporation (a surrogate measure for evapotranspiration) from normal annual total precipitation. Mean annual lake evaporation information was not available for St. Thomas; however, evapotranspiration data were available. These data indicate that 95.8 percent of the incident precipitation on St. Thomas is lost through evapotranspiration. The normal annual total precipitation for St. Thomas is 43. 74 inches, but because of orographic effects on the Island, normal annual total precipitation can range from 35 inches to 50 inches over short distances. In the Turpentine Run Basin, normal annual precipitation is 40 inches. Calculations for net precipitation are provided below: 40 inches precipitation x 95.8 percent lost to evapotranspiration = 38.32 inches lost to evapotranspiration 40 inches precipitation - 38.32 inches lost to evapotranspiration = 1 .68 inches net precipitation. Ref. Nos. 3, 5, 12, 13 7. Identify uses of groundwater within 3 miles of the site (i.e., private drinking source, municipal source, commercial, industrial, irrigation, unusable). Groundwater within 3 miles of the site is used as a source of private and municipal drinking water, and for commerical purposes. There are at least 41 wells within 2 miles of the site. Thirty-four of these wells are within 1 mile fo the site. Sixteen of these wells have been closed because they are contaminated with volatile organic compounds. Ref. Nos. 6, 9 8. What is the distance to and depth of the nearest well that is currently used for drinking or irrigation purposes? Distance _ _.:._7..:::c8.;:;..0...;.fe.;:;..e-=-t::.-____ _ Depth __ 1;...;:5"""0-'f-=-e.;:;..et~----- Nearest well is the VIHA well No. 2, which is located approximately 780 feet southeast of Ramsey Motors. This well is believed to be used for drinking. A nearby well, VIHA No. 1, was ordered closed because of contamination with volatile organic compounds. VIHA well No. 2 is not listed as being closed for contamination, and its designated use is for domestic purposes. Ref. Nos. 6, 9 • ·''·) 'I_ 02-8902-42-PA Rev. No. 0 9. Identify the population served by the aquifer of concern within a 3-mile radius of the site. 10. It is difficult to estimate the population served by groundwater on St. Thomas as there are few records available on groundwater withdrawal, sale, and transport. The locations of some wells in St. Thomas are unknown, and there are reports of illegal drilling on the island. It is estimated that there are 500 to 600 private wells on St. Thomas. Most of these are used for nondrinking domestic purposes such as washing and flushing, although some may be used for drinking. There are a number of wells that are used for commercial purposes. Water from these wells is trucked to private houses and pumped into cisterns to augment the rainwater collected from roofs. Groundwater is also bottled and sold in supermarkets. There are at least 41 wells in the Turpentine Run Basin. Recently 16 of these wells have been ordered closed because they were found to be contaminated with volatile organic compounds. One of these wells was a major supplier of water to the eastern end of the island. Estimates of the population using groundwater as a source of drinking water range from none to approximately 11,000--the population of the Turpentine Run Basin which is not served by water from the desalinization plant. The actual population served by groundwater is probably less than 11,000 as desalinated water and water from wells outside the three mile radius is trucked into the area. Ref. Nos.9, 13, 15, 18, 19 SURFACE WATER ROUTE Describe the likelihood of a release of contaminant(s) to surface water as follows: observed, alleged, potential, or none. Identify the contaminant(s) detected or suspected, and provide a rationale for attributing the contaminants to the facility. A very small potential exists for contaminants to be transported to surface water. The waste oil drums are stored inside a garage on a cement floor. There were some minor spills in the area and there were no containment structures around the drums to prevent migration of spills. The drums contain waste oil generated from automotive repair and maintenance activities. Air monitoring instruments indicated the presence of organic vapors in the open drums. Substances such as gasoline, kerosene, and degreasing solvents may also be present in the drums. Waste oil was draining from a ditch on the adjacent Gassett Motors site onto the Ramsey Motors site. Ref. Nos. 1, 2 11. Identify and locate the nearest downslope surface water. If possible, include a description of possible surface drainage patterns from the site. The nearest downslope surface water is the Mangrove Lagoon, which is hydraulically connected to the Caribbean Sea. The distance from the site to the nearest surface water along the course of Turpentine Run is 2.5 miles. There are a number of storm sewers on the site and it is possible that these sewers may intercept much of the runoff from the site. It is unknown where the storm sewers discharge but it is suspected that they discharge to Turpentine Run as it is the only drainage pathway from the basin. Ref. Nos. 2, 4, 5 12. What is the facility slope in percent? (Facility slope is measured from the highest point of deposited hazardous waste to the most downhill point of the waste area or to where contamination is detected.) The facility is relatively flat with a slight slope toward the south-southeast. Facility slope is estimated to be Oto 3 percent •_;(_., .L /i.j.i)' .. :, Ref Nos 1, 2 02-8902-42-PA Rev. No. 0 13. What is the slope of the intervening terrain in percent? (Intervening terrain slope is measured from the most downhill point of the waste area to the probable point of entry to surface water.) The slope of the intervening terrain is as follows: • Elevation of waste area 240 ft • Elevation at point of entry Oft • Path length 13,200 ft 240 ft- 0 ft x 100 = 1.8% slope 13,200 ft Ref. Nos. 1, 2 14. What is the 1-year 24-hour rainfall? 1-year 24-hour rainfall data was not available for the U.S. Virgin Islands. However, it is known that rains exceeding 1 inch in 24 hours occur six or seven times a year on St. Thomas. Two-year 48-hour rainfalls range from 4 to 15 inches. It has also been reported that it is not uncommon for 24-hour rainfalls to be 2 to 3 inches. Ref. Nos. 4, 6 15. What is the distance to the nearest downslope surf ace water? Measure the distance along a course that runoff can be expected to follow. The nearest downslope surface water is the Mangrove Lagoon which is hydraulically connected to the Caribbean Sea. The distance from the site to the lagoon is 2.5 miles. It appears that most runoff fromthe site enters storm drains near the site. Since the point of discharge and the route of these storm drains is unknown, the distance to the nearest downslope surface water along the pathway is unknown.· Ref. No. 2 16. Identify uses of surface waters within 3 miles downstream of the site (i.e., drinking, irrigation, recreation, commercial, industrial, not used). Surface water within 3 miles downstream of the site is used for recreation including swimming, fishing, and boating. The DPNR has designated the area of the Mangrove Lagoon for preservation and conservation recreation. Ref. Nos. 2, 14 17. Describe any wetlands, greater than 5 acres in area, within 2 miles downstream of the site. Include whether it is a freshwater or coastal wetland. There are no wetlands greater than 5 acres within 2 miles downstream of the site. However, there is a coastal Mangrove wetland approximately 2.5 miles downstream. The Mangrove Swamp is designated as a preservation area in the Coastal Zone Management Program of the DPNR. Ref. Nos. 2, 14 18. Describe any critical habitats of federally listed endangered species within 2 miles of the site along the migration path. There are no known critical habitats of federally endangered species within 2 miles of the site. The Virgin Islands Tree Boa (Epicrates monensis granti) is an endangered species in the U.S. Virgin Islands; however, no critical habitat has been identified for this species. Ref. No. 7 19. What is the distance to the nearest sens1t1ve environment along or contiguous to the migration path (if any exist within 2 miles)? There are no sensitive environments within two miles of the site that lie ale to the migration pathway Ref Nos 2, 7, 14 ;Ui 02-8902-42-PA Rev. No. 0 20. Identify the population served or acres of food crops irrigated by surface water intakes within 3 miles downstream of the site and the distance to the intake(s). There is no population served or food crops irrigated by surface water intakes within 3 miles downstream of the site. The nearest surface water is saline. There is a desalinization plant which uses sea water to supply drinking water, but the intake is greater than 3 miles from the site. Ref. Nos. 2, 13 21. What is the state water quality classification of the water body of concern? No water quality classification is known to exist for the Mangrove Lagoon or the Caribbean Sea, although the mangrove swamp surrounding the lagoon is designated as a preservation area by the DPNR. Ref. No. 14 22. Describe any apparent biota contamination that is attributable to the site. No apparent biota contamiantion was observed during the on-site reconnaissance conducted by NUS Corp. Region 2 FIT on February 15, 1989. Ref. No. 1 AIR ROUTE 23. Describe the likelihood of a release of contaminant(s) to the air as follows: observed, alleged, potential, none. Identify the contaminant(s) detected or suspected, and provide a rationale for attributing the contaminant(s) to the facility. The potential for release of contaminants to the air is very small. Above-background concentrations of organic vapors were detected in drums using an OVA and HNu; however, no readings above background were detected in the ambient air in the drum storage areas. The drums on site contain waste oil from automotive repair and servicing operations. The drums may also contain small quantities of gasoline, kerosene, or degreasing solvents. Ref. Nos. 1, 2 24. What is the population within a 4-mile radius of the site? Based on the 1980 census, the population within 4 miles of the site is approximately 36,000. Ref. No. 17 FIRE AND EXPLOSION 25. Describe the potential for a fire or explosion to occur with respect to the hazardous substance(s) known or suspected to be present on site. Identify the hazardous substance(s) and the method of storage or containment associated with each. No significant fire or explosion conditions are known or suspected to be present on the site. Ref. No. 1 26. What is the population within a 2-mile radius of the hazardous substance(s) at the facility? Based on the 1980 census, the population within 2 miles of the site is approximately 19,000. Ref. No. 17 ! : __ ;i 'J ..i DIRECT CONTACT/ON-SITE EXPOSURE 02-8902-42-PA Rev. No. 0 27. Describe the potential for direct contact with hazardous substance{s) stored in any of the waste units on site or deposited in on-site soils. Identify the hazardous substance{s) and the accessibility of the waste unit. There is little potential for direct contact with substances stored in the waste unit. Although the bungs are open on some of the drums and there are some spills, the drums are not located in an area that is frequented by customers. Access to the site is controlled by a fence. There is potential for workers to come in contact with waste oil in the course of performing their jobs. Ref. No. 1 28. How many residents live on a property whose boundaries encompass any part of an area contaminated by the site? There is no evidence that any residential areas have been contaminated by the site. Ref. No. 1 29. What is the population within a 1-mile radius of the site? Based on the 1980 census data, the population within 1 mile of the site is approximately 11,000. Ref. No. 17 - PART IV: SITE SUMMARY AND RECOMMENDATIONS 02-8902-42-PA Rev. No. 0 The Ramsey Motors Site is located in the Tutu area of St. Thomas, U.S. Virgin Islands. Ramsey Motors is engaged in the sale, maintenance and repair of automobiles. The area within approximately 1 mile of the site is densely populated and contains some commercial properties. There are large housing developments northeast, southeast, and west of the site. The nearest residence is approximately 400 feet southwest of the site. The densely populated and highly commercial town of Charlotte Amalie, which is the capital of St Thomas, is located 2.3 miles east of the site. There are twenty-five 55-gallon drums of waste oil stored on a concrete floor along the inside perimeter of the Ramsey Motors automotive garage. Some of the drums were open and there were spills on the garage floor during the on-site reconnaissance conducted by NUS Corp. on February 15, 1989. Readings ranging from 10 to 90 ppm and 60 to 300 ppm were detected on the HNu photoionization detector and the OVA flame ionization detector, respectively, during the reconnaissance. Waste oil was noted discharging from a pool on the adjacent Gassett Motors Property into a drainage ditch on the Ramsey Motors Site. Until June 1986, the Virgin Islands Water and Power Authority (WAPA) accepted waste oil generated by marinas, airports, and auto maintenance facilities. The waste oil was blended with fuel and burned as a source of power. WAPA stopped accepting waste oil when a batch was found to contain PCBs. The source of the PCBs is unknown. Since 1986, there has been no permitted method of waste oil disposal on St. Thomas. Generators must store their waste oil, but the facilities are not inspected or issued storage permits. These conditions combined with drum shortages and poor housekeeping has resulted in generally poor waste containment at many of the facilities. As mentioned previously, the waste oil drums on the Ramsey Motors Property are not properly stored or contained. Many of the drums are open and there is oil pooled on the floor. The garage where the drums are stored has a concrete floor and an overhang roof, but the walls are not continuous and small quantities of oil appeared to be leaking into the soil in a few areas. There are no berms to contain the oil in the event of a spill. Although there is a potential for the waste oil to be released to the environment, the waste oil drums on the site do not currently pose a significant threat to groundwater or surface water resources in the vicinity of the site. As a result, a recommendation of NO FURTHER REMEDIAL ACTION PLANNED is provided. Any potential for release of the oil to the environment could be significantly reduced if the drums are properly stored and contained, and the spilled oil is cleaned up. It is recommended that the responsible local or federal department ensure that the waste is properly stored and contained. i LJ I 02-8902-42-PA Rev. No. 0 No enforcement actions have been taken against Ramsey Motors in the past. The owners of the Ramsey Motors property have been identified as one of nine potentially responsible parties in the contamination of groundwater in the Tutu area. In July and August of 1987, EPA confirmed by sampling that volatile organic compounds were present in a number of wells in the Tutu area. DPNR has issued orders to close 16 wells in the area. EPA removal action activities in the Tutu area included: sampling of wells and cisterns, removal of contaminated water from cisterns, and supplying clean water on a regular basis to affected residents. \I../\ ATTACHMENT A MAPS AND PHOTOS RAMSEY MOTORS ST. THOMAS, U.S. VIRGIN ISLANDS CONTENTS Figure 1: Site Location Map Figure 2: Site Map Exhibit A: Photograph Log 02-8902-42-PA Rev. No. 0 :J .. J. ... ·---- 1enlund .._J'.' ---·-. SITE LOCATION MAP RAMSEY MOTORS ST. THOMAS, U.S. VIRGIN ISLANDS SCALE: 1·• 2000' 77 02-8902-42-PA Rev.Jo. 7~ ' J FIGURE 1 II ■~ ',?,~1?: ~ I 0 t WATER TOWER SMALL 20 GALLON DRUMS, PAILS OIL STAIN WELL oO 0 0 •••• ••• 0 0 OVERHANG GARAGE • • • • CONCRETE LOT GRASS/ DIRT -------~-------~----~ LEGEND O OPEN DRUM e CLOSED DRUM ROUTE 384 SITE MAP RAMSEY MOTORS • • • • • • • 1-z w :::e w 0 ST. THOMAS, U.S. VIRGIN ISLANDS NOT TO SCALE I X 02-8902-42-PA Rev. No. 0 OIL STAINS, x POOLS GRASS GRASS " GR:___J GASSETT PROPERTY FIGURE 2 I □ J&.11 I~ i i ii i U' , 1 _.:,; L1 1..::1 ----, l .. . . ,_ t t I Photo Number R3-Pl3 R3-Pl4 R3-Pi5 R3-Pl6 RAMSEY MOTORS ST. THOMAS, U.S. VIRGIN ISLANDS FEBRUARY 15, 1989 PHOTOGRAPH INDEX ALL PHOTOGRPAHS TAKEN BY DIANE TRUBE Description Ramsey Motors waste oil drums inside garage. Small 20 gallon drums in garage. Ramsey Motors. Pooled oil from drainage ditch at Gassett Motors. Groundwater supply well and water storage tank. 02-8902-42-PA Rev. No. 0 Time 1426 1431 1436 1447 i ;_ , i ,_,,) J .::· .,:;. .I ·, R3-P13 02-8902-42-PA Rev. No. 0 RAMSEY MOTORS ST. THOMAS, U.S. VIRGIN ISLANDS February 15, 1989 1426 Ramsey Motors waste oil drums inside garage. 1 t; I R3-P14 RAMSEY MOTORS 02-8902-42-PA Rev. No. 0 ST. THOMAS, U.S. VIRGIN ISLANDS February 15 , 1989 1431 Sma 11 20 ga 11 on, drums in garage. : U i f;;,):, · '1.:1. ,i R3-P15 RAMSEY MOTORS 02-8902-42-PA Rev. No. O ST. THOMAS, U.S. VIRGIN ISLANDS i=ebruary 15, 1989 1436 Ramsey Motors. Pooled oil from drainage ditch at Gassett Motors. R3-Pl6 02-8902-42-PA Rev. No. 0 RAMSEY MOTORS ST. THOMC\S, U.S. VIRGIN ISLANDS February 15, 1989 1447 Groundwater supply well and water storage tank. ,1 /.i i ,._), J ::. ,::'-(). J --_; ATTACHMENT B REFERENCES ; i REFERENCES 02-8902-42-PA Rev. No. 0 1. Field Notebook No. 0398, U.S. Virgin Islands Drum Reconnaissance, TDD No. 02-8902-29, NUS Corp. Region 2 FIT, Edison, New Jersey, February 14 to 17, 1989. 2. U.S. Department of the Interior, Geological Survey Topographic Maps, 7.5 minute series, "Central St. Thomas, Virgin Islands and Eastern St. Thomas, Virgin Islands Quadrangles" 1955, revised 1982. 3. Gomez - Gomez, F. and J.E. Heisel. Summary Appraisals of the Nation's Groundwater Resources-Caribbean Region. Geological Survey Professional Paper 813-4, 1980. 4. Stone, R.G. Scientific Survey of Porto Rico and the Virgin Islands, Volume XIX - Part 1, Meteorology of the Virgin Islands. 1942. 5. Climate of Puerto Rico and Virgin Islands, Climatography of the United States No. 60, June 1982. 6. Tutu Well Site Potable Water Alternatives Report, Anna's Retreat, St. Thomas, U.S. Virgin Islands. Prepared for U.S. EPA Region 2 By Region 2 Technical Assistance Team, Weston/SPER Division, December, 1989. 7. Fish and Wildlife Service List of Endangered and theatened Wildlife and Plants. 50 CFR 17.11 and 17.12. February, 1985. 8. Telecon Note, Telephone conversation between Nancy Schlater, EPA and Diane Trube, NUS Re: Sole source aquifer in VI, March 3, 1989. 9. Graves, R.P. and R. Gonzalez. Potentiometric surface of the Trupentine Run Basin Aquifer in the Tutu Area, Eastern St. Thomas, U.S. Virgin Islands, September 11, 1987. U.S. Geological Survey Water Resource Investigations Report 88-4131, 1998. 10. Uncontrolled hazardous waste site ranking system, A user's manual, 40 CRF, Part 300, Appendix A, 1986. 11. Donnelly, T.W., Geology of St. Thomas and St. John, U.S. Virgin Islands, In Caribbean Geological Investigations, Geological Society of America, Memoir 98. ed. H. H. Hess, 1966. 12. Climatological Data Annual Summary, Puerto Rico and Virgin Islands. National Oceanic and Atmospheric Administration, 1987. 13. Torres - Sierra, H. and R. Dacasta, Estimated Water Use in St. Thomas, U.S. Virgin Islands, July 1983 to June 1984. Caribbean Research Institute, Technical Report No. 21. 14. U.S. Virgin Islands Department of Planning and Natural Resources, Coastal Zone Management Program, zoning districts and coastal land and water use plan map. 15. Memo to Stephen D. Luftig,EPA, from Carlos O'Neill, EPA. Authorization of CERCLA Removal Action Monies for the Tutu Well Site. January 6, 1988. 16. Jordan, D.G. and O.J. Cosner, A Survey of the Water Resources of St. Thomas, Virgin Islands, U.S. Geological Survey Open File Report, 1973. 17. Water management Plan for the Public Water System, Prepared for the Government of the Virgin Islands by CH2M HILL July, 1983 REFERENCES (CONT'D) 02-8902-42-PA Rev.No.a 18. Telecon Note: Conversation between Fernando Gomez, USGS and Rich Feinberg, NUS Corp., on 3/11/89 at 1045 hours. RE: Hydrology and groundwater use in St. Thomas. 19. Telecon Note: Conversation between D. Goetz of Polycaribe and D. Trube, NUS Corp., on 3/14/89 at 1430 hours. RE: Wells and water use on St. Thomas. 20. Telecon Note: Conversation between L. Reed, DPNR, and D. Trube, NUS Corp., on 3/3/89 at 1640 hours. RE: Permits for site on St. Thomas. 21. Record of Communication, Telephone conversation between L. Reid, DPNR, and A. Brochu, U.S. EPA Region 2, on 1/30/89 at 1400 hours. REFERENCE NO. 1 .-:: /.i- . :, , ~ - I ' , <.. ,'..; ,- I - I I I NUS CORPORATION I II __, - 0398 I I I I I I I -- I ' l""tro -~~.nc.: _ v-)/uVI\.:,~ I Ca..:~r _ GC7£°-:re _ ____ _ Pn-nco __ Hof-tJ_ri _ C(.Mlm(.J.._r;,+.1 ho+o:-s VJ:.. c;~l,)t_HliJ~r ---►~/ c'o\\ f- _, ' -'- - l-µ- -~·Cl..j-(;- -- -...:.:.; s- f 7 ·-r,; . ., , LL - __ _e....a..c_c__:_1.;__e__~_ro,.o..£._ --=1:.:,!, _ •i _ u~~~.,-------- ---- ?' _ _tf ac .. br_ Ha_u~---M~r~----~ _ ___ __ _ _________ 9 _ -- _J3~~df~ho0.1e.r-•~~r-W'~ ------- -rg- - 2 lnd2ep.eacia.~ --aao..tL,-a.rd 10 Amu ,c..P--v) '-{ ru: b+: ~.\.o c't:c , , c _ ___ _ _ ___ _ CQQ ~Ck;l<?~co {_ c4 :Y-nht:0 l2._~------ . ~- c.A- 7\A..'DI,i., __ lDa~-t-s___=-~m~C,"':s--'-'~~--'Z..- --,......_ _ n:-.,, l 0 , · 0.1 _ t- - / <:J --;--_, "\ I? -- . L.)C~-.c--..C;. __ \..,'_\. \._ ;;,.J,:,£v. , ~ _, t~~ -t-- -~U~-\------J....;) _ --r:_~k..~l-cO..CC___ -- ---- ---- - . ·- __ I'{ G~~ ___ t:\o.+o_._s ~a.m ~ --r- _ fv\cA-c , s __ """T ---~-- ~ssc_ L Q . . O~°'- O.~~-- A,r~or -r _ ,--~., C"I_ ~v• _,.~ ~Q.v.X~-- _ -r ~ ,c.. I\,·, ') :re i,..._ ~ 1·, ~ - . 7)e_'~ru:C.:r--,> '-v I .\) r t,J R_ --- c::::,-_ -- I lo ,7 I~ 1ct ,q zo z.o 2'2. Fii:ar··,· OlPj() Mei w/ ~- .--C..:,,kr-_. T \ic, 7'-' ~' c")'--' p~ J- O '?CO Arr ;ve'(Y ('\_ -r ·v 1 0rl~-t ~\Q.('\~Y), - \Jo.~ Kt>.S. ('::) N ~) cSzs- ~ C:,,.r\c~ C'lJ,t_J. 0.--,~..,, ·--;J a."'o....~ (-cc1·.~ ·-rrn-'i. a..vd ~no.J..c "°-.ci::.,..v-.a-r_ • -4- LecnC1-r<'.:f~e..ecC. ("i,~9-.),,111 ._ve;._.:. h(.o< -4-o Sam.pt.(. ~rn~'1 Ho-h .-c_:,. G c,c, s.<.·l+s ~.,ct.J'S ,I ...... ~ ["':J~o , +1 v-ru..'-Te,..c:u.o, A.Jo --,c. h;, ~ ..... t'"\.d. C~los sa.._d) • ½o.c.-l-.,"t l-tn.._,e,I\ ''·fo.r .. ~c ... :!:, ,:-,..{ ~,-h~ .. 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Gel+W <!s~ l...ro Y". Cl< c) c....,-, ({ -+-r <, s ~ -~vii,... f.. ~ c. '1 C \ ~ ce c~(. s--~--' I... • oq o o bi~~ R\ "1 -~ r a,", vc:> .s \(0...........\..0. fo:~'f8cl Ca.mm a., ro.... -L~ (E ?A EO:.:So-,... ~ ~c ";e) -," e.\c:a.a z?,-e ( tt,\t\ ..s Cc."'-\a.ci- -~ ., -~~cjcu_ ~'1) \ecf-, §:J9'1Jap d-/~fo ),J,,,,.,., 1A" /1/ 2/1( lrf U yo I 'I ;·r I ,, __ l I (.J() .L s·qc.1-2q (, )_ '?''l I ! C ",- !407 16 d \' ro~-~1 -\ 'vJoc~;'IQ•::..~.>; ~\.\. 6 .. ( (..A.h,s. o..rc 1..JO ~.c... od --; ():.4u.mS i"- (:.0.SW"- '-..o;:i<Y, .. U 9o ~ 1 -% ~~J'Y'.. OuA 1 \\I\ • C -30 ('I')"" t-p\;'-"- \ \ .. '., C,\~ 1_0...'Qe.l - . [, :n,--. '~ - 1---\c_:- 'b ::0. s+Cl..~.s; -~- ~n-\S <ao -~o f~rn (c,vft) '~"~:sc..Gl c.,~.,.__ 6',lv..A""..s o..'-c:....-c 2o -Go ? ~ ,..,,,. C1-f ,u\..._ \ 11 fl~~~<::._ ;..__ \)__~~ L0h.(. __ / '9-•'l.LMS' o.lo"~ _ \,«c.l< of 9"-r~- _ _ _ _ --~ _ ___ ._.. ~ <l.bet<;, - . E?- xo•"- _ (ro -~c - 3:c.... -.... -- - . ~ Cc O&ai( Ccrdn L 7 St 0 --tl..e. r5 \.I.."' \:-..... 1w_ \ \a c} 3ou ~~m ,_' ,:._,_) P..-"') . - dl<v-,M ~ Jr~(" 't-.'\. 9.aro..~ (of!"' bvl'\ ~s ) _ t o- q o ? ? )'V\ c !+ AJ"'" 1 . " _\t,. ~VV\ ~""c-1 6e.,rl-(; JO~ o'd weJ.I (~rCi'~o,,, ') not- ui.."C ~, cL-- •v\.\Cti,r tlR~(C,)'- ,c,c· ~ U.: ~ l l ?<~ ,")'\.V{ ela.,--,tz:ct) A-- LS . ! q, s.,.. f~rrrv.:r~ W 1) L C)O~ 78' l1..:;e.\ I ~\.v..,-e, u.Se& ,G, & ,-.i1~ ..... ...:~. bw-\:i..s ~ L ...._ ~ & o:;f ~ /d,,. - u.xi 1 • r~~ ¾ ·~~;(.~ +n..y"\k. - ~ rrt..lX..-h -~.dJ --rL; cuJ.--,f~ P+-c~, ~ "T.; c :Cl..Y),'\..ffL_,.__~· f\.A ,...._ C-:-..J ·-y, ' l:SU◊ ~ c:~ s'-- - ~ ·' /l .·' _. . .:. .. .. T . .: ... · - .... ' ....... ._. .. ' 1, I >----- . (<':' (y' \ I ,t ' I I ; I ~ ~ ~ ~ \.G ;,)(_"! ]_ ~-•1.1·,:'d j_ i - +- --+-- i ~ I I -r- i ~ I ' - G, vc,~, _-; c - ,_,, I i_, '..;,-:.L(",. .. , - -, 1 """': ~c Cr\. 18 ~:CL! I ___ j_; ..,.I. ·'k::l_ .• C&3c - -, c,C\., [e cClL.;, 2 ...,,.,.,-u.:Q,t_. " ( 4-o.. "'- ~ ~ ._'V\CL....., ~-d ~i~<...-':, ~'"7 CS,1n~ d,._,.~.--~ - ~ "'t w<,)J L,-CCJ.£ ~-'-<~rc~c.CC ---tr:- (D-e_ cCcs.ecP h7 r o__(i --- ---- _l.-':_5.-C,.., r-Ls 5~l[ ~----~ __ ,_LJS.d'...d __ fu_r_ <::or ~(~~- ____ __-__ &__, ..... / .. !cl ____ -ty'~ _ -f-a __ ?0)-.)_~ _G_ W.~ L,L..r(..JL ~e,_l~"1 ,+~r<;e, ..J- _ ------- --=pa_p_c --L~~- - - -- - -- ----- - --- --·- - - - --- - - · -- Wells_ .@- _ I.J-'·•c.-° ~ __ G_r_~10.c£e.__jd-i__V, ______________________________________ -· ____ e·_v:::.::- __ LA.':'1,•--~•~:tt-------------------- ------- - - - _-_ __ J_S_..;\'\es~ ~~4 )..j~-5_-~e.~--"" _c~-'-t_cf PAJ~~~-- -~c UO.no.-c& ca--..-.. S<...c... _ ~- ___ ~:i-i-~cf ~~ ~ .~ c.Y" REFERENCE NO. 2 .... :' ,:j.. ''· ·. -·-- :enlund !! \ - .. ---··. ·. ·. - ... .. .. .. ,,;-;.~: . ·. ·. ·. ~-~1.,.q~::.--:-·. ~·· VIRGIN !SU.NOS ~ SITE LOCATION MAP RAMSEY MOTORS ST. THOMAS, U.S. VIRGIN ISLANDS SCALE: 1·• 2000' FIGURE 1 Er '-11 r "7,::-), -~j I _ \_1\_ I .. _ i' •- ~ ...-~1"-A"-' REFERENCE NO. 3 ;-1 : .i- Summary Appraisals of the Nation's Ground-Water Resources- Caribbean Region , , By FERNANDO GOMEZ-GOMEZ and JAMES E. HEISEL GEOLOGICAL SURVEY PROFESSIONAL PAPER 813-U . , UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON:1980 U20 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES TABLE 4. - Water budget, in cubic ltectcnMters per year (lim1lyr) and percent. for Puerta Rico (by Weat COUL to Rio Grande ,le Are<ibo hm 1fyr Percent l'r.-<1p1Latwn __________________ l.tiljjl Streamrlow ___________________ ti~ 01vt'r.uuns ___________________ _ E,,·apulrasp1ralKJn _ _____________ I AIU SL~am outfluw ~ 1; ruund-watt.-r loss lo Wt'L!ands ur ~• ______________ 15 t;mund-water w1lhdrawals 1: Tol&l _______________________ 1U Industry ____________________ ~ lrnteallun __________________ _ Pubhc supply ________________ I 7:l.0 :!i u 61.3 37.6 Rio Grande de Arecibo to Rio d• La Plala hm1/yr Percent 1 . .!tkl I.U:lO J.i :!.6 Ri<J de La PlaLa to Rio Espiritu Santo hm1lyr Perc-ent Input hi"O .'>:1.2 .i~ ~6.d Ouq,ut :100 ;!J,M ~20 73.0 ;!I) 16 lU 1.6 15 Puerto Rico South Province Patillu Tallaboa to to Pon« Guanaca hmJ/yr Pe~nt hm1fyr Perttnt HU ;)0.6 60 :15.5 .!20 :1~.5 175 i4.5 dO ~-~ ~JO '.,J. I 60 :15.5 I\IO :!3.5 LOO "2.6 lO l.5 LS 6.4 170 :!1.0 60 25.5 I~ 21 143 37 d 2 La)U Valley hm111yr Perttnt IOU 72.d u :i ~ 33 :.!40 llO 1!7.3 II X.U 6.3 ~-" WntCout p,.,.,,_ :16() 29.0 - il.O .!70 ll.d ~20 74.2 40 3.2 IU d 10 1 All Kruund wat.t.-r withdrawn wu •~umt!'d LU ~ (or cunsumplkin :i.tnl't' 1t 1s nol ava1laL,W for utht-r u~. 1000,---~--,---,---~--.,....--...---.----, Public Supply (Puerto Rico Aqueduct ond Sewer Authority) 100 0 1910 IMS 1910 1979 1110 111!5 1990 YEARS A 1995 2000 2!5,-----:--""""T"--r-----r---.-----r---.-----r--- zo ~ 15 .., ► 10 IC ~ !5 ... IC 0'-----'----L--...... --...... --....... --....... --....... ---J .., ... .., ~ !50,----,---,----r----r---,---,---"T""---, ... :;: 45 z u 40 • B" z -- 30 "' ~ 25 • : zo 0 ~ 15 i 10 !5 ?HO 1915 TOTAL WITMDtl-ALS (held" 1■lf-MP,ilff i■llntry ... ........ ,., . . .. .,) &IIOUNOWATU 1175 ltlO IH5 1990 lffl 2000 YUIii B F1c1 1n: 17.-Watt.-r-use estimates. A, Fur Puerto ltico: µublic-supply data provided hy the Puerto Ri(·o A,1~uct and Sewer Authority (mo<litie1I from Morris, 1!!71;). B. for the U.S. Virgin lsla111ls. iUi 24::~:4 CARIBBEAN REGIOl'i U21 province) and its off1lwre i,'4nd, (Vvqius, CtiUbra, and M= Isl.and,) and JOT the U.S. ViTy\n Istanda, 1975 P1.Wrtu H.K·u -Conllnut"'I l'.S. \. lrj,CIII b.~1111 ... Pu,•rlu k.K·u·s uffshon- island:- lcutC.-t lntttnor l'Ut"r\A.1 k.lC'o Vwqut':- &•ndt111..tl Cuk-hra ,\l,,n,1, SI. Cn,u, St Thum;L"' ' ~t ,lut111 µruv11l(y ~•Vln<'l' hmJJ,,-r J't"rt"t-nl hm-'f\.'r Pt'rt"t"nt hm11~r Pt'n-t"nl hm-'/_\r Pt-rn·nl hmJ1~r Pt'n·t'nl hm 1•\r Pt•fTt·lll hm'·,r Pt'n·1·nt hmJ1_\1 t-'t"l'l"t'lll hmJ•~r P"'rn·111 lnput-Continixd Jlll) U.J IO,M'io IOU l:'.J.M:tO IOU llU IOU 'l.[J IOU -1.-, )tMI :au IOU !:tfi )OIi ., .. (OU :';10 56.7 Output-Continued 27ij 310 6.512 5S S 10.151i 64.l 110 ~I., ~4.0 580 64.4 4.JU as.s 5.046 :ll.S ;,.o :llJ :l.J 260 I.ti J.:l :ti .J ll l.:l 16 t :158 2.J +; .tM IU JIM t 188 12 t;+; PROBLEMS AFFECTING USE OF WATER RESOURCES MANAGEMENT-PUERTO JllCO By adoption of Law No. 23 of January 1973, the Puer- to Rico Department of Natural Resources (DNR) was charged with the responsibility for implementation of the operational phase of the public environmental policy of Puerto Rico. Law No. 23 also provides for centraliza- tion of operational functions and implementation of regulations that had previously been dispersed throughout many governmental agencies. In addition, the new Water Law, No. 136 of June 3, 1976, assigned to the Secretary of DNR the responsibility to plan and regulate the use of and to improve, conserve, and develop the waters of Puerto Rico. In acknowledgment of the need for a centralized information center, the new water law also stipulates that the Secretary be assisted by a staff that has representatives from the Planning Board, the Puerto Rico Industrial Development Com- pany (PRIDCO), tbe Environmental Quality Board (EQB), the Puerto Rico Aqueduct and Sewer Authority (PRASA), the Puerto Rico Water Resources Authority (PRWRA), the Department of Agriculture (DOA), the Department of Health (DOH), the Department of Trans- portation and Public Works, and the University of Puer- to Rico. Although numerous government agencies (State and Federal) and institutions are involved in the use, plan-I ning, management, and investigation of the water 1 resources, the DNR, EQB, U.S. Environmental Protec-: tion Agency (EPA), PRWRA, PRASA, Puerto Rico ! Sugar Corporation, and heavy water-use industries j S5.H ::i~.~l ~7" :tu.-1 'JJ.:! ~I !:ti(~ t.H II u " J.t) :l.ti ; u ~ .-) l:l.:! ;,;, l.it 1.:! 1;; I I " II ,.-, II established by PRIDCO exert the greatest influence over the future of this resource. The responsibilities these agencies and public corporations have with respect to water resources are listed as follows: DNR. The functions of this Puerto Rican agency were establish_ed by Laws No. 23 and No. 136, previously stated. EQB. This is the Puerto Rico policy-making and regulatory agency responsible for the enhancement and protection of water quality; it is invested with quasijudicial powers to enforce its regulations. For purposes of the Federal Water Pollution Control program (Public Law 92-500) the Board is designated the State water-pollution control agen- cy. EPA. This is the Federal agency charged with ad- ministration of Public Law 92-500 aimed at restor- ing and maintaining the chemical, physical. and biological integrity of the Nation's waters. Among the programs the agency administers are establish- ment of effluent limitations, administration of the National Pollutant Discharge Elimination System, and management and planning for public water- supply treatment-works construction. PRWRA. The authority produces and distributes elec- trical energy and administers and operates the irri- gation systems supported by releases from reser- voirs and the hydroelectric power-generation nt:'t· work un the south coast and in northwestern Puerto Rieu. PRASA. The authority is charged with development. construction, operation, and maintenance of water and sewer systems and providing adequate water ·1 \ ,·1 I' .. .' I r;.q1o fr~~ U22 SUMMARY APPRAISALS OF THE NATION'S GROL'ND-WATER RESOL:RCES and sewer services and any other related services and facilities. Puerto Rico Sugar Corporation. A public corporation created by legislative action in 1973 to consolidate the operations of the sugar industry (cultivation and refining). The corporation manages all the 11 mills on the island, 7 of which are government owned. The corporation also manages cane cultivation on 29,600 ha of both government-owned and leased land. PRIDCO. This is the principal Puerto Rico governmen- tal agency charged with the responsibility for the economic development of Puerto Rico. With its associated public corporation, the Government Development Bank, it devises rr.ethods to accelerate economic development, especially through industrial promotion and tourism. This agency must submit to DNR and EQB an environmental-impact statement for each industrial project it proposes to develop. The agency also cooperates closely with the Plan- ning Board in preparing its plans and programs. The new centralized form of management stipulated in Law No. 136 of June 3, 1976, is intended to improve in- stitutional structures to aid optimum water-resources development. MANAGEMENT-U.S. VD.GIN ISLANDS In the U.S. Virgin Islands, the Department of Conser- vation and Cultural Affairs is charged with the ad- ministration and enforcement of all laws relating to water resources and water pol1ution, under Title 3, Chapter 22, of the Virgin Islands Code as of June 4, 1968. Other agencies involved with the management of the water resources are the Public Works Department, the Water and Power Authority, and the Virgin Islands Planning Office. The functions of each of these are outlined as follows: Public Works Department. Under Title 30, Section 51, of the Virgin Islands Code, the Commissioner of Public Works is designated to supervise and control the construction, repair, maintenance, operation, and administration of the potable-water systems. The potable-water system was defined as "all fresh water stored or collected by the government, whether in catchments, dams, wells, or reservoirs, for public distribution." Virgin Islands Water and Power Authority (WAPA). This authority was established in 1964 under Virgin Islands Code, Section 103, Title 30, for production and distribution of electrical energy and provision of potable water from its water-distillation systems. In the enabling legislation is a provision, 104e, for the transfer of the water-supply functions of the Public Works Department to W AP A at a date to be deter- mined by law. The transfer of functions has not been acted upon by the legislature, and W AP A sells the distilled water to the Public Works Department. U.S. Virgin Islands Planning Office. This office is designated as the government agency in charge of water-management planning; the agency is also en- titled to appropriate funds received under the title 3 program. The Public Works Department is by far the major ground-water user. Agriculture is almost nonexistent in the islands, and industries that depend heavily on water obtain their water from self-owned desalination plants. For these reasons, a lack of coordination among water users is not a major problem affecting ground-water resources in the Virgin Islands. WATER RIGHTS Water rights and laws regulating water use have been established by society to assure the minimum re- quirements of individuals and communities, to promote the beneficial development of water resources, and to respect legal access to water sources. These laws, which have been implemented to reduce friction between users, ironically become constraints if they are not adapted f:9 the needs of a modern technological society. On June 3, 1976, the Commonwealth Legislature approved the Law of Waters (Law No. 136) for Puerto Rico, which declared all waters within Puerto Rico the patrimony and wealth of the People of Puerto Rico; en- dowed the Secretary of Natural Resources with the power to plan and regulate the use, conservation, and development of the water resources and to implement the public policy and regulations related to the waters of Puerto Rico; and annulled two provisions of the Civil Code and the Law of Waters of March 12, 1903. The 1903 water law was essentially that which had been in effect in Spain since 1879 and had been extended over Puerto Rico by order of the King in 1886. Article 16 of Law No. 136 recognized acquired rights that make beneficial and reasonable use of water and were in ex- istence prior to June 3, 1976, including those conces- sions from the Spanish Crown. Acquired rights under the old Spanish law were ob- tained according to the prior-appropriation doctrine. For example, "any landowner may utilize the pluvial and other waters flowing intermittently in public channels or along roads" (Art. 6, 176, 177); "after use for one year and a day, he establishes a temporary right that is superior to that of any subsequent user," on the principle that first in time is first in right (Art. 7); "after water has been used without interruption for 20 years, the appro- priator acquires the right to continue the use indefinite- ! l_J 1 l) (.) .i. . .::'. .. :.\. -.~. b CARIBBEA~ Rl::GJO~ ly" (Art. 8). Similarly, as to "artesian wells, tunnels, or I galleries," (major ground-water developments as oppos- ed to "ordinary wells," which are defined (Art. 20) as j those for which no other motive power than man is employed for raising the waters), the right of the person ' discovering and bringing the water to the surface is recognized "in perpetuity," as long as such development does not interfere with preexisting rights to public or private waters (Art. 23). These rights (surface- or ground-water appropriation) were also recognized for all individuals who had enjoyed the use of public waters for a period of 20 years (prior tu 1886) even though no proper authorization had been obtained. The order of preference in utilization stipulated by the previous law (Art. 160 of the Spanish Water Law) ex- pressed the needs of the past century. First priority was given to water supply of towns, followed by water sup- , ply of railroads, irrigation, navigational canals, mills and I other factories, ferry boats and floating bridges, and fishponds. The economic importance of water-using in- I dustries was not foreseen, and a low preference as to water concessions was stipulated. Duration of the con- ' cessions was limited to 99 years of town supplies (Art. 170) and all other uses but was Min perpetuity" for irriga- tion (Art. 188) and fishponds and also for industry, as long as effluents were not harmful to health or vegeta- tion (Art. 220). As of 1909 there were approximately 250 concessions in Puerto Rico that were originally granted by the Spanish Crown (Report of the Governor of Puerto Rico, 1909). The majority of these grants were given to lan- downers in the South Coast province for the irrigation of approximately 21,000 ha. The surface-water conces- sions included rights to flood-waters, spring and winter waters, or a definite daily flow. An updated inventory of vested owners, diversion amounts, and land under irrigation is necessary to determine the degree to which these rights could affect a water-use and distribution plan. In the Virgin Islands, all waters are in public owner- ship and are subject to appropriation for beneficial use as stipulated in Chapw 5, Title 12, of the Virgin Islands Code. Under this policy, vested rights are recognized prior to other appropriation. Vested rights may be nullified by the government of the Virgin Islands (Com- missioner of Conservation and Cultural Affairs) when it is determined that the exercise of such rights would im- peril health or welfare by endangering, impairing, or destroying available sources of water. Nevertheless, the occurrence of such circumstances is very remote, as most private installations are for domestic use and withdraw less than 2 m3/d. An exception could be those individuals and companies that sell water obtained from I wells. Under Section 153 of Title 12, appropriation per- mits are not required if pumpage is less than 2 m31d for benefit1al use. Cndt•r Chapter 3, Title 12, of the Virgin Islands Code. trees and other vegetation adjacent to watercourses are protectt•c! by law. This regulation protects the esthetic values Pt stream channels but results in a significant loss of ground water to evapotranspiration by the deep- rooted ,·egetation. A modification of this law would be necessary in order to exclude from such provision those watereourses that are used for public supplies or are in hydraulic connection with aquifers tapped for supply. PRACTICES DETRIMENTAL TO GROUND-WATER QUALITY LAND USE Land use may affect recharge to an aquifer and the quality of its water. Although there has been no exten- sive evaluation of the effects of various land uses on aquifers in the Caribbean Region, data from scattered sources indicate that this could be a major problem in the near future. Urbanization has taken over large portions of the recharge areas of aquifers in metropolitan San Juan, Ponce, and Mayaguez in Puerto Rico and throughout the Virgin Islands of St. Croix and St. Thomas. Unless ar- tificial recharge is provided or withdrawals are reduced to compensate for the loss of recharge, the seawater- freshwater interface will move inland in most of these areas. Aquifers in the Caribbean Region are threatened by pollution from domestic, municipal, and industrial sources. The most widespread source of pollution is pro- bably sewage from cesspools, leaking sewage lines, and overloaded or improperly operating sewage plants. In Puerto Rico about 37 percent of the population is served by sewers. and in the U.S. Virgin Islands approximately 77 percent is served. In en I the only areas served by sewers are those within wns. ~ wastes have been discharged to aquifers through sinkholes and disposal wells or have entered aquifers from accidental spillage (D.G. Jordan, written commun., 1969; R.C. Vorhis, written commun., 1972). Of the 15 disposal wells known to exist in 1972, only 2 could be designated as deep injection wells, and the others could better be designated waste-disposal holes. All the known disposal holes were between 24 and 213 m deep. Wastes disposed in sinkholes and disposal holes in- clude sewage, oil. neutralized acid, organic compounds, dyes, pickling liquors, pineapple-cannery wastes. and brewery wastes. Jordan (written commun., 1969) estimated there were at least 40 such disposal holes in Puerto Rico in 1969. It has also been observed that unproductive wells are either abandoned without plugging or are not thor- 0 a U24 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES oughly sealed. As a result many are used as receptacles for wastes. The effects on water quality and the extent of damage this has caused in the Caribbean Region have not been assessed. In the Lajas Valley, Vazquez and Ortiz-Velez (1967) observed that a downward hydraulic gradient existed at various abandoned irrigation wells. These wells probably are serving as hydraulic connec- tors between perched water tables and the underlying regional water table. The effect of these "hydraulic con- nectors" on water quality is unknown. Disposal of refuse in landfills poses another threat to aquifers in Puerto Rico. Most landfills were estalished after 1972 (fig. 18), and although migration of leachates may be slow at some sites, with time these will inevi- tably affect to some degree the local ground-water sources. In the U.S. Virgin Islands, landfills have been established near the coast on St. Croix and St. Thomas, and contamination of freshwater sources is not a threat. The landfill on St John, however, is located in the in- ,rir 18'00' 111"15' EXPI.ANA TION t:. Municipal IOlid wat9 dmpoeal ... ShadN--~1111 Ul-•1111 • .....,_ CULEBRA ~~ '-~~ VIEQUES terior Guinea Gut Basin, where potential for ground- water development exists. IRJlJGATION PRACTICES Irrigation of crops occurs primarily in southern Puer- to Rico. The basic means of distributing water within cultivated lands is by furrows, although overhead sprinklers are used at some farms in the early months of sugarcane cultivation. Giusti (1971) estimated that ap- proximately 30 percent of the applied water in the South Coast province (Coamo area) was recharged to the aquifer. Bennett (1976) indicated that the ground-water reservoir in the South Coast province is "vertically oriented," in that local recharge and discharge tend to be high in any given locality relative to lateral ground- water flow. In areas where irrigation water is derived from wells, recycling of the irrigation water will result in an increase in the dissolved-solids concentration of the ground water. PUERTO RICO 115"11)' 64"'5' 17°45' FlGUU 18.- Solid-wute dilpoal llitee in the Caribbean &ep,n. CARIBBEAN REGION U25 During the mid-1960's, drought nearly eliminated surface-water supplies that were used in the South Coast province area for irrigation, and ground-water production was increased to make up the deficit. By 1968, after 3 years of increased pumpage, the ground water in storage was drastically depleted. An estimated 1,000 hm3 of the 1,500 hm3 in available storage had been withdrawn. The depletion in storage was accompanied by a decline in ground-water levels to below s~ level over large areas (pl. lA). The chloride concentration in the ground water increased slightly in the more severely depleted areas, but major seawater intrusion did not occur, apparently because of a slight ground-water mound in the coastal areas and the lower hydraulic con• ductivity of the coastal part of the aquifer. Heavy rains later in 1968 recharged the aquifer, but it has never recovered to early 1960 levels. A few areas where ground-water levels were below sea level still persisted in 1976 (pl. lB), but there has been no significant in- crease in chloride concentration indicative of seawater intrusion. OPTIMIZATION or USE or WATER. llESOUR.CES In general, until recent years the Hfort devoted to optimizing the use of water resources of the Caribbean Region has been minimal. Within Puerto Rico this lack of effort may have been due to the relative abundance of freshwater in relation to demand in most areas. In the U.S. Virgin Islands the poor quality of the ground water and the knowledge that the limited freshwater resources could not meet the demand led to reliance on seawater- desalination plants. Two major approaches are available for optimizing the use of water resources. These are conjunctive use of surface- and ground-water sources and water conserva- tion. The potential for application of such measures in the Caribbean Region is discussed separately. OONJUNCTIVE USE OF SURFACE- AND GROUND-WATER SOURCES The greatest potential for conjunctive use of surface- and ground-water IOW'CeS in the Caribbean Region may be on the island of Puerto Rico, where both sources are relatively plentiful. This use may be achieved by res- ervoir management, augmenting natural recharge, ground-water salvage, ground-water mining, and use of seawater. RESERVOIR MANAGEMENT Agriculture is the largest single water user in the South Coast province. The estimated ground-water withdrawal for irrigation (180 hm3/yr) constitutes almost 80 percent of the total pumpage. Therefore, the most productive efforts to solve the "water shortage" may involve an improvement of irrigation practices. To some degree, the irrigation efficiency likely could be im- proved by coordinating the activities of PRWRA with those of the Puerto Rico Sugar Corporation and by changing the priority of the functions of reservoirs serv- ing the south coast. Under present operating conditions, reservoirs are maintained at the highest stage possible for hydroelec- tric generation, thus reducing the runoff-capture poten- tial. With the available reservoirs and the implementa- tion of a more efficient water-management system, more water could be made available for irrigation. The hydroelectric-energy loss could possibly be compensated for by thermoelectric generation through burning of bagasse, the plant residue left after the juice has been extracted from sugar cane. During the 1973 fiscal year, PRWRA bought from the sugar mills (which operate from about December to April) 826 million kilowatt- hours of energy generated through burning of bagasse (Puerto Rico Planning Board, 1976). Hydroelectric generation was only about 97 .5 million kilowatt-hours during the 1973 fiscal year, partly by north-coast hydroelectric plants. AUGMENTING NATURAL RECHARGE Although aquifers receive recharge by natural means, it may be practical in some areas to increase this amount artificially. Within urbanized centers the loss of rainfall infiltration capacity may be compensated for by con- struction of infiltration ponds, which may also serve for recreation. Flow into the ponds could be supplied from urban runoff or by pumpage from nearby streams. These infiltration ponds could be situated in the upland coastal areas, where coarse sediments (sand and gravel) predominate and thickness of unsaturated material and therefore storage volume is greatest. Areas of Puerto Rico that could benefit most from such modifications are those zones where urban development has decreased the infiltration capacity of aquifers (essentially the San Juan metropolitan area and Ponce). In the San Juan metropolitan area, possible sites would be the San Sebastian outcrop and areas between the haystack hills (mogotes). At Ponce the most favorable area may be near the foothills, where depth to the water table is bet- ween 15 and 20 m. Infiltration induced by this method may make it feasible to establish and continuously operate public-supply wells within city limits, thus reducing dependence on interbasin water transfer. These well fields would also be invaluable in the event of hurricane damage to centralized water-purification and distribution systems. If the recharged water is destined for domestic use, measures would have to be taken to avoid contamination with toxic substances, which may r i 1 1 u, , 1 :c:: .q .::; c,- U30 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES even though ground-water development may be minimal in some areas. Within aquifers for which preliminary areal models have been constructed, monitoring net- works should be maintained to determine whether or not conditions follow those predicted. If significant deviation is detected, the cause can be evaluated and remedial measures can be taken as appropriate. Among the most important needs for improving the knowledge about aquifers in the Caribbean Region are listed as follows: 1. Better definition of conditions within the two major aquifers: knowledge needed about the following: a. Hydrologic relationship between bedrock and alluvium in the South Coast province of Puerto Rico and stream-aquifer interrela- tionships b. Extent of the artesian S)(Stem in the North Coast province of Puerto Rico c. Ground-water flow within the North Coast province west of Arecibo 2. Areal studies made concerning the following: a. Ground-water flow system in Lajas Valley b. Water-balance for unstudied aquifers in the East Coast, West Coast, and Interior pro- vinces c. Water-table monitoring throughout Puerto Rico, the offshore islands, and U .S Virgin Islands d. Qualit.ative and quantitive assessment of saline- water reserves of St. Croix and in the coastal aquifers of Puerto Rico e. Chemical-quality data to assess the extent of contamination and seawater intrusion Besides these basic needs, research is also lacking on evapotranspiration and its relationship to soils and vegetation under the climatic conditions in the Carib- bean Region. At present it is unknown if under long- term conditions thick vegetation and plant debris aid ground-water recharge by reducing runoff, enhancing infiltration, and reducing direct evaporation of rainfall or whether they uae more water from the soil through transpiration. ArchMolop:al sites, surface features, and historical notes indieate that water was much more plentiful at now parched areas in Puerto Rico's offshore islands and in the U.S. Virgin lsland.3. SUMMAllY The Caribbean Region consists of the Commonwealth of Puerto Rico (8,990 km2) and the U.S. Vi!X,in Islands (36illcm2). It i11 amoRg the n,osr-derisely populated areas in lhe woi'td, with an oveta:11 population of approxnnate- ly 3,200,000 people. Within the past 25 years the islands nave undergone a rapid transformation from an agriculturally based economy to one dependent on in- dustrial development, tourism. and related services. Water is among the most abundant and valuable natural resources in the Caribbean Region, but its availability varies significantly in both space and time. Rainfall contributes an annual average of 1,800 mm in Puerto Rico and 1,060 mm in the U.S. Virgin Islands. Of this amount, 1,130 mm (or 64 percent) in Puerto Rico and 990 mm (or 93 percent) in the U.S. Virgin Islands is lost to evapotranspiration. The water available for use in liquid form amounts to about 5,400 hm3/yr in Puerto Rico a.nd 24 hm3/yr in the U.S. Virgin Islands These amounts would theoretically satisfy the total water needs of both areas, which are about 919 hm3/yr and 20 hm3/yr, respectively (1975). In reality, most of this flow is contributed by intensive rainstorms and is lost to the ocean as runoff. Potential for retaining a large part of this flow exists on the island of Puerto Rico, but present- ly the total usable reservoir storage capacity is only about 230 hm3 • In the U.S. Virgin Islands, small dams and ponds have a storage capacity of about 2 hm•. Aquifers constitute a valuable water resource in the Caribbean Region. In Puerto Rico, ground-water withdrawals provide about 38 percent of the total water requirements, whereas in the U.S. Virgin Islands, they _p_rovide 10 percent. Excluding desalinated-water sup- plies in the U.S. Virgin Islands, ground water rovides a t 72 rcent of the freshwater . Of the 350 hm3/yr groun -water with wal in Puerto Rico, irriga- tion uses 53 percent; industry, 29 percent; and public water supply, 18 percent. In the U.S. Virgin Islands, ground water is withdrawn about equally from private wells and public water-supply wells. Based on past trends and future economic outlook in the region, estimates are that by 1985 ground-water pumpage in Puerto Rico will be about 426 hm3/yr and in the U.S. Virgin Islands, about 4.5 hm3/yr. This withdrawal is the estimated maximum sustained yield of all aquifers in the U.S. Virgin Islands under natural-recharge conditions. Most large-scale ground-water developments in Puer- to Rico are in the North Coast and South Coast pro- vinces. The North Coast province contains the island'f. most productive aquifer, which has been undergoing rapid development for industrial water supply since 1968, when a major artesian system was tapped. The ex- tent of this artesian system is unknown, but it has been tapped within the lower part of the Cibao Formation (Montebello Limestone Member) and in the upper part of the Lares Limestone. The South Coast province aquifer consists of deep alluvial deposits. It has been ex- tensively developed for irrigation of sugarcane and for industrial water supply. Unlike the north-coast aquifer system, which has large untapped resources, this aquifer I Ui :_;(_i 1. CARIBBEAN REGION U31 will support only minor future development if effective management practices are not introduced. In the U.S. Vir ·n Islands, the most extensive 1~ igneous roe . t contri utes 1ttle water to wells, but weighed against the costs of desalinated water, its exploitation is feasible for sup- plementing domestic water needs. The most productive aquifer consists of marl and alluvium deposits in central St. Croix. Although this aquifer contributes less than 6.3 Lis to individual wells, it yields about 0.86 hm3/yr to public water-supply wells and about 0.54 hm3/yr to private wells. Future development of this aquifer could probably produce an additional 1.0 hm3/yr. Ground-water resources will continue to play an im- portant role in the future development of both Puerto Rico and the U.S. Virgin Islands. In order to meet future needs, it is necessary that hydrologic principles be effectively applied in managing the total water resource. Optimization of the water resources can be ac- complished through conjunctive use of surface and ground waters and through conservation practices. Op- timal use may involve artificial recharge, ground-water salvage, saline- or fresh-ground-water mining, use of seawater, waste-water reuse, and use of underground space for temporary storage of wastes, which could otherwise contaminate valuable water supplies. Efficient development of the water resources within a basin also requires a thorough knowledge of the rela- tionship that exists between surface and subsurface water. Among the most urgent needs in the Caribbean Region is a computerized data bank containing informa- tion on ground-water withdrawal, consumptive use, sur- face diversions, and such other flows necessary for water-budget estimates. These data can be used with the available knowledge of the aquifers to construct digital or analog models. Such an approach would serve to point out areas where new information is needed, aid in assigning investigation priorities, and contribute to ef- fective management of the total water resource. SELECTED llFEllENCES Acevedo, G., Lugo-Lopes, IL A., and Ortiz-Velez, J., 1959, Occurrence of soil tumors nonhlat of tbe Guanica Lqoon, Lajas Valley, Puerto Rico: Univenity of Puerto Rico Agricultural Station Jour- nal, V, 43, 00. 2, p. 103-115. Adolphson, D. G., Seijo, M. A., and Robinson, T. M .. 1977, Water n!90W'CeS ofMaunabo Valley, Puerto Rico: U.S. Geological Survey Water-Resources Investigations 76-115, « p. Anders, R. B., 1968, Reconnaissance of the water resources of the Central Guanajibo Valley, Caho Rojo, Puerto Rico: U.S. Geological Survey open-file report, 18 p. Anderson, 1976, Ground water in the San Juan metropolitan area, Puerto Rico: U.S. Geological Survey Water-Resources Investiga- tion 41-75, 34 p. --197i, Ground water in the Lajas Valh,y. Puerto tt,~o: L -~- Geological Survey Water-~ources Investigation 68-i6, 45 p. Arnow. T .. and Crooks, J. W., 1960, Public Water supply in Put'rto Rico: Commonw1ealth of Puerto Rico Water-Rtesources Bulletin 2. 34 p. Bennett. G. D., 1972. Ground water along Rio Hucana at Ponce, Puerto Rico, and effects uf a proposed noodway on ground-wati,r quality: Commonwi,alth of Puerto Rico Water-Resources Bulli,tin 11. 28 p. --19i6. Electrical analog simulation of thi, aquifers along the south coast of Puerto Rico: lJ.S. Geological Survey Open-File Report 76-4, 101 p. Bennett, G. D., and Giusti, E. V .. 1972, Ground watt'r in the T11r- tuguero area, Puerto Rico, as related to proposed harbor construc- tion: Commonwealth of Puerto Rico Watt'r-Resources Bulletin 10, 25 p. Black, Crow and Eidsness, 1976, A water management plan for St. W, Croix, U.S. Virgin Islands: Black, Cn,w and Eidsness, Inc., Cun- T suiting Engineers, Gainsville, Fl. Black and V1eatch, 1976. Water supply study for entire island of Puerto Rico, first phase: Black and Veatch Consulting Engineers, Kansas City, Miss. Black and Veatch, Domenech, R. A .. and Associates, 1970, Water resources of Puerto Rico, phase ll. Ground Water appraisal: Black and Veatch Consulting Engineers. Kansas City, Miss., and R. A. Domenech and Associates, Hato Rey, Puerto Rico. Bogart, D. 8., Arnow, T., and Crooks, J. W., 1964, Water n!SOl.lrces of Puerto Rico, a progress report: Commonwealth of Put.-rto Rico Water-Resources Bulletin 4, 102 p. Bonnett, J. A., and Brenes, E. J., 1958, Detailed salinity survey of Lajas Valley: University of Puerto Rico Agricultural Experimen• tal Station Bulletin 111, 114 p. Briggs, R. P., anq Akers, J. P., 1965, Hydrogeologic map of Puerto Rico and adjacent islands: U.S. Geological Survey Hydrologic In- vestigations Atlas HA-197, scale 1:240,000. Briggs, R. P., and Seiders, V. M .. 1972, Geologic map of the Isla de Mona Quadrangle, Puerto Rico: U.S. Geological Survey Miscellaneous Geologic Investigations Map 1-718, scale 1:20,000. Buros, 0. K., 1976, Wastewater reclamation project, St. Croix, U.S. Virgin Islands: U.S. Environmental Protection Agt,ncy, En- vironmental Protection Technology Series EPA-600/2-76-134. 244 p. Calvesbert. R. J., 1970. Climate of Puerto Rico and U.S. Virgin ~ Islands: U.S. Department of Commerce EnvironmePtal Science Services Administrative Publication 60-52, Silver Spring, Md., 29 p. Cederstrom, D. J., 1950, Geology and ground-water resources of St. Croix, Virgin Islands: U.S. Geological Survey Water-Supply Paper 1067, 117 p. Cosner, 0. J .• 1972, Water in St. John, U.S. Virgin Island~: U.S. ~ Geological Survey open-file report, 46 p. Crooks. J. W .. Grossman, I. G., and Buicart. D. 8., 1968. Water resourres of the Guayanilla-Yaut·o area. Puerto Rico: Com- monwealth of Puerto Rico Water-Resources Bulletin 5, 55 p. Diaz, J. R .. 1968-1974. Gruund water levels in the south coast of Puer- to Rico (Guanica to Patillas): U.S. Geolo~al Survey Oata Release PR-I. San Juan, P.R. --1973, Chemical quality of water in Caflo Tiburones. Puerto Rico, A reconnaissance study carried out in 1967: C.S. Geological Survey open-file report (map), 2 p. --1974, Coastal salinity reconnaissance and monitoring system -south coast of Puerto Rico: U.S. Geological Survey Open- File Report 74-1, 28 p. ·\ i).) REFERENCE NO. 4 .'..-: .-. .;. ,:'. - . ,• .,. ·.i,, ~:: "\. .. ,r ... ~ t r ,.·,· .~ ·. ,.·\.· ,,i ... _ a rt - ~ 7-; : = ..:- , . == jl :">70.\"E . .\IETEOROLOCr or TEI£ f"IRCI.\" ISL..J.SDS 19 The nature oi the shorter-period pressure Yariations in relation to the weather and the general circulation are discussed below under The Cpper . .\ir and General Circulation, etc. PRECIPITATION Rain i, the climatic element oi most practical concern in the islands be- cause it is o iten 111,ufficient to mature sugar cane 111 one or two seasons: a drought o i six or nine consecuti \·e months occurs e\'ery decade or so. caus- ing much hardship to the townspeople and small nati\'e iarmers as well as to sugar and cotton estates and cattle ranches. Since early in the nineteenth century rainiall in the Virgin Islands has been measured in a unique unit of depth, called the "'line". The reason ior the adoption oi this measure is not known. It is an old English measure. in which I inch = 8 lines ( = 25.-tO millimeters). In Denmark they once used the Paris measure oi 12 Li11ie11 = I T 0111rne ( Paris inch) = 27.07 milli- meters= 1.0658 inches. I Paris line= 2.256 mm= .0888 inch= ~{ 44 foot. whereas the Danish f!'cst flldian (or English) line= 3.175 mm= L8 inch. It is conceivable that as many of the residents were British this "line" was adopted locally irom using English rain-measuring glasses or sticks graduated in eighths oi an inch. Since the . .\merican occupation inches ha\'e been used. Accuracy of the Measurements The accuracy oi rainfall measurements is a difficult problem in gen- eral. and is especially serious in tropical conntries. * \Ve have already re- f erred to the lack oi standards in the instruments and obsen·ation pro- cedures at \'irgin Islands stations. and here we mnst add that where the rainfalls are frequently light and the monthly and annual totals are small the errors oi measurement are greatest on a percentual basis. The common practice of measuring the catch only once each 2-t hours allows some water to evaporate irom the gage beiore it is read. particularly in a warm windy climate. The use oi a funnel is common and tends to cut down the evapo- ration. \\"here most of the rain falls at night. it is better to read the gage in the mornirn~. and where it ialls mor<: in the day an e\·ening ohsern.tion hour is pre ierable: two readings a <lay would be still better. and best oi all the use oi recording gages or the habit of reading the gage after each shower. It has been shown that a considerable difference in a giYen • For a cumprehen,;;1\·e discusswn see Jlrool-:s. C. F .. ;\ee<l ior universal !-itandar<is for measurin'I" :1rec1n1tat1on. :-;nowfall. and snowcover. Trans. '.\leet. Int. Comm. Snow and Glacien, Int .. \ssoc. llydrol. !lull. 23: pp. 1-52. Riga. 1938. !.)(_)_l :.~,.f.q4 7 20 SCIENTIFIC SURVEY OF PORTO RICO month's total may result at the same spot between a gage read each morn- ing and a gage read each evening. But it is difficult to estimate the magni- tude of this effect in the Virgin Islands except to say that the results from gages read only in the morning are probably somewhat lower than they would be if read only in the evening. The hours oi observation at the vari- ous stations are not stated or known in many cases and at some stations they were changed from time to time. Rain gages of different diameter and different l1eight oi orifice above the ground do not give comparable catches, but it is believed nearly all the gages used in the Virgin Islands since 1870 have been of the standard 8-inch diameter with rim about 3 feet high (cf. appendix A). The wind eddying around the gage may keep away some of the rain that should go in the gage. In windy places the catch may average 20 per cent too low from this cause, but we judge from tests made elsewhere with shielded gages that this error in the Virgin Islands probably does not average over 10 per cent (i.e., readings are 10 per cent too low on average from the wind effect alone). If we may assume that this error applies roughly equally to all the gages in the Caribbean region, it may be overlooked in practical comparisons. However, the error due to wind effect increases as the wind velocity increases and therefore the catch during severe storms, hurri- canes, is apt to be more than 10 per cent too low. High wind sometimes blows the gage over resulting in loss of a large catch of rain. Occasionally during heavy rains the gage may overflow before it is read. Considering all these sources of error, it is evident that on the average the recorded rain- falls are systematically lower than the true rainfalls. In addition there may be mistakes and falsifications on the part of ob- servers, which are unsystematic in their effect on the results and largely hidden in the averages. An inspection of the daily entries and the reputa- tion of the observer are the only bases for accepting observations as genu- ine, where the stations are not under regular inspection of an efficient na- tional weather service. We have not found any record of inspections by the Danish government, and the U. S. Weather Bureau inspections have been too infrequent to be effective. General Distribution From APPENDIX TABLES 2 and 3 we note that the mean annual rainfall differs considerably at the various stations, ranging between about 35 and 70 inches. The absolute range between driest and rainiest years at these stations is not much larger, however, the extreme annual totals ranging 'from about 25 inches to nearly 95 inches (APPENDIX TABLE 1 ). If we had \ 10: i STONE: C:Jv-Dl §» [Z) •• I records from eai tremes would be inches. A rainfall The seastntal c in May or June much more prone on record indicat month ; even Oct, tions ( see TEXT sections of St. C rain fall from 001 west, but from : middle was agai shift in the relat south of east, wh· peratures and ht graphic effects. E. Taylor in 1888: 42) sugg• RICO 1 gage read each morn- to estimate the magni- that the results from .vhat lower than they ,bservation at the vari- and at some stations :;ht of oririce al.Jove the · •~lieved nearly all the ,een of the standard i,endix A). The wind he rain that should go 20 per cent too low where with shielded does not average over er~~-- from the wind s •.__..;hly equally to ,·_erlooked in practical increases as the wind vere storms, hurri- .. gh wind sometimes of rain. Occasionally ead. Considering all _ ! the recorded rain- ; on the part O f ob- ~esults and largely tries and the reputa- h . servat1ons as genu- 1 of an efficient na- rd of inspections by ~au inspections have ·an ann11al rain fall -.veen about 35 and niest years at these ual totals ranging BLE 1 ). If we had I ~ STONE: METEOROLOGY OF THE VIRGIN ISLANDS 21 cm • ., . .,0 filll >o-·., [Z] •O· t, mlll H • 60 1111 OwC • 60 F1ouu 2. Rainfall map of St. Croix, 1921-30. (From Sbaw, 1932.) records from eastern St. Croix and from the mountain tops, these ex- tremes would be greater, probably reaching from 15 to more than 100 inches. A rainfall map of most of St. Croix is shown in FIGURE 2. The seasonal distribution generally shows two maxima, a smaller one in May or June and a larger one in October. The winter minimum is much more pronounced than the summer one. The lowest monthly amounts on record indicate that severe drought conditions can occur in almost any month ; even October has sometimes had less than 2 or 3 inches at most sta- tions ( see TEXT TABLE 4). Rose points out that the middle and western sections of St. Croix have somewhat opposite tendencies in departures of , . rainfall from normal - from 1903 to 1908 the middle was drier than the ... ,.,. west, but from 19()() to 1915 the middle was wetter, and after 1915 the middle was again the drier. This may possibly be due to a quasi-cyclic shift in the relative frequency of winds from slightly north and slightly south of east, which would be accompanied by changes in the average tem- peratures and humidities of the trade winds as well as contrasted oro- graphic effects. Forests and Rainfall E. Taylor in his "Leaflets from the Danish West Indies" (London, 1888: 42) suggests that St. Croix formerly had a greater rainfall be- i·t..1·1 j ()() .1 .,,,,,,,._. \ 22 SC/E;VTJPIC Sl'RVEY OF PORTO RICO cause an early book on the islands by Oldendorp ( l i7i) reported a greater amount of forest growth than is now found. Although a change of climate is possible, the present condition is better explained by the known destruc- tion of the forest by the inhabitants. TEXT TABLE 5 shows no prr1na11c11t change in the rainfall of St. Croix since 1852. St. John and Tortola have the most forests at present because they are too mountainous for economi- TEXT TABLE 4 FREQt:ENCY OF .\{ONTIII.Y RAINFALL TOTALS GREATF.R THAN SrECIFIED AMOUNTS, ST. C1w1x Average of 3 stations for 63 years, 1852-1914 (From Ravn) lfonth Number of years with rainfall Over 20 lines Over 40 lines Over 60 lines (2.50in.) (5.00 in.) (7.50 in.) Janury 25 l Fellruary 13 I lfan:b IJ 1 A ·1 JJ 5 1 ~ J7 24 II Juae JB 19 9 July 44 u J A.IIIUlt 50 2Z 8 September 57 Jl 10 October 60 JI 18 November 54 JO lJ December 39 11 4 cal sugar-cane culture, though at one time both were under considerable cultivation. There is no reason to believe that either St. John or Tortola receive much more rain than St. Thomas or St. Croix merely hecause they are now more forested. Indeed, the rainfall observations ( cf. APPENDIX TABLES 2--6) lend no support to that notion. Orographic Effects The rainfall increases with elevation on all the islands. as residents and traveler! can readily observe and as one would expect. Dut rain-gage sta- tions are.lacking at high elevations, except Pearl, Mafolie. Liliendal, \Vint- berg, and Dorothea. Shaw's rainfall map (FIGl'RE 2) based on rainfall records (see APPENDIX TABLE 7) of sugar estates on St. Croix leaves no doubt that even moderate elevations are better watered. Yet the rate of in- crease of rainfall with elevation does not here seem to be as large as in the parts of Porto Rico where the mountains rise steeply to 30()() feet or more directly in the path of the prevailing winds. Rose suggests that the rain- fall of the islands is not as great as one would expect from the topography because the winds blow mostly parallel to the mountain trends. The reason I I I I'' I \ ! .. i I ();_).1. :,'.4/\ / N <,, TEXT TABLE 5 AVEIIAGt; RAINt'AI.L t'OK EACH 10-Yt:AII PERIOD, 1852-1911 (IN INCIU;s)• "St. Croix, Virgin Islands"= (01ristiamtc<l's Fort+ Kings Ifill• + Fn-,kri,·k,1,-,1·, (From L. Smith) Period Jan. Feb. Mar. Apr. lllay June July Aug. S,pt. Ocl. -----·- - - - - 18S2-61 1.90 1.60 1.68 J.12 S.SJ J.76 J.SI 4.92 7.26 8.16 1862-71 2.11 1.6S 2.J6 2.06 3.35 J.86 3.10. 4.18 S.26 7.S0 1872-8l t 2 .85 Ul 1.57 1.43 4.16 4.48 3.J7 4.25 5.28 5.11 l/;82 91 t U8 210 I.IS 3.17 l.22 J.97 4.06 4.62 4.92 7.S0 1892 1901 2.16 1.4S l.l2 2.1S 6.JJ 4.60 S.42 4.58 6.81 5.47 1902 II 2.52 2.31 1.12 2.52 4.26 J.40 2.47 S.40 6.92 4.68 Total 14.JJ I t.45 10.21 15.57 26.90 24.08 21.9S 28.11 36.45 39.38 Average for 60 years (18S2-1911) 2 .38 1.91 1.70 2.60 4.47 4.01 J.65 4.70 6.07 6.S6 'I I, h,rl )/.I ----·- Nov. 4.43 4.07 6.61 S.92 S.46 4.96 ,r /;I ·i ii r: ,, ,, Dec. Year 2.68 3.40 2.33 3.67 4.08 s.os -- -------- - 31.4S 21.23 28l.3S S.23 3.53 46.89 • Tht>se- are from tht same obs,nvations used in Ti'.XT TA8L£S 19 to 22, hert converted to inches from the "lints" in which rainfall was measured (8 lines= J inch). l'rom "Re1>0rh ol 1he Vir1in hland• l,;xp,,rimenl Slalion, 1911". t Kin15 Hill wa• omilled from the avtralH for Oct. 1878 to Oct. 1888, inclusive. l~ I I ij 11 I I 24 SCIENTIFIC SURVEY OF PORTO RICO for this may also be contained in some observations of the writer: on sev- eral occasions during his stay at St. Thomas in June, 1939 when the sum- mit of the island ( 1800 ieet) was visited, he noticed that any large cumulo- nimbus cloud that had been initiated by forced ascent of the wind over the island would lean to the leeward so that most of the rain falling from it would fall on the ocean surface somewhat to the lee of the island. In other words the orographic influence on the rainfall was not fully enjoyed by the island itself owing to its small size and narrow form. This observation is confirmed ( oral communication) by Sergeant Davidovic. the Aerographer stationed at the U.S. Marine Corps Fleet Air Base on St. Thomas in 1939. In general the annual rain fall does not seem to increase more than about 10 inches between sea level and 1000 feet elevation, but some of the lower stations have as much rain as places high up on the leeward slopes or in high protected valleys ( compare Adrian and Cinnamon Bay, or Barracks and Liliendal, in the same years) (APPENDIX TABLE 2). In generally rainy years or months the rainfall differences between stations of different ele- vation are much greater than in generally dry seasons. At the U. S. Marine Corps station on Lindbergh Bay three rain gages have been set a few hundred yarcis apart in a line from the water to the foot of the mountain. These gages show a decided increase in rainfall (AP- PENDIX TABLE 12) as the mountain is approached, although they arc all about at the same elevation. This demonstrates how sensitive the rain- producing process is to the topography. For this reason, within the hilly town of Charlotte Amalie, or of Christianste4r_iliuveragc aoonal rainfall probably varies considerably ( up to 5 inches?) from block to block; hence records taken at difi'ere-nt spots in such a town cannot justifiably be com- bined as if from one station. Likewise different parcels of an estate often have very different rainfall ( e.g., Eden, Emmaus, Caroline; Adrian, Su- sannaberg) . We have not attempted to construct rainfall charts of St. Thomas and St. John owing to the non-homogeneity of the records. Shaw's map of St. Croix (FICUU 2) is based on a homogeneous though short ( 10 years) series of 26 records from the flatter parts of the island, which should give a reliable and consistent pattern. Year to Year Variation The variability of the mean annual rainfall is of prime economic conse- quence because in over half the years the actual rainfall is well below the 11ormal rainfall,• which is just about sufficient for an annual yield of sugar • It ia characteristic of the frequency distribution of either daily, monthly or annual rainfallo, that the most frequent value(....,.,.,) i1 ,enerally much less than the aver~. and in some caae9 the zero value is mmt frequent. i L .f I UUJ STO.V E.: .\IE:, cane, long the chief en discusses this problem low). Du Tertre and C the poor crops of 1841 1923 to 1924 were <lw trary to the impressio evidence that the rain to century ( see Fores has not been scientiti( show long quasi-peric rainfall. These undou enough to reveal any I near the critical limit f tuations are important understanding of the for the farmers merel) attempts to forecast ti derived from analysis for long-range foreca solutions offered do nc plicability, however pt The most successful r places, none of which I The diurnal distribt greater amount of rai1 foe's observations at 1 Tidende", 1888. He gi NIGHT AND Moath (1888) July Au,ust September • In lines; 8 lin The frequency of r: is probably not so prot heavier. :,,:'44(/ TO RICO 1s of the writer: on sev- une, 1939 when the sum- ::i that any large cumulo- ~nt of the wind over the the rain falling from it Pe of the island. In other ,ot fully enjoyed by the ,rm. This observation is _-idovic. the Aerographer on St. Thomas in 1939. crease more than about n, but some of the lower · 1e leeward slopes or in mon Bay, or Barracks .E 2). In generally rainy -tati(" of different eie- 1s. __ ,,1 Bay three rain gages ~ from the water to the crease in rainfall (AP- although they are all 10w sensitive the rain- ason, within the hilly 1erage annual rainfall n block to block ; hence not justifiably be com- els of an estate often ...:aroline ; Adrian, Su- s of St. Thomas and s. Shaw's map of St. ugh short ( l O years) ·-d, which should give :me economic conse- all is well below the annual yield of sugar >nthly or annual rainfalla, ace, and in 10me cuet the STO.\'E: J!ETEOROLOGY OF THE VIRGIN ISLANDS 25 cane, long the chief crop, and the cane yield suffers accordingly ( Dr. Shaw discusses this problem with respect to St. Croix, in paragraphs quoted be- low). Du Tertre and Ol<lendorp mention great droughts in 1661 and 1753; the poor crops of 1841, 1864, 1869, 1872 to 1877, 1891, 1892, 1899, 1904, 1923 to 1924 were due to low rainfall (see TEXT TABLES 20 to 23). Con- trary to the impression of many residents and travelers, there is no real evidence that the rainfall is slowly and steadily decreasing from century to century (see Forests and Rainfall). The question of cyclic variations has not been scientifically studied here, but results elsewhere generally show long quasi-periodic fluctuations of considerable amplitude in the rainfall. These undoubtedly exist here too but the records are not long enough to reveal any but the shortest "cycles". The average rainfall is so near the critical limit for sugar cane that even the small short-period fluc- tuations are important. It does not contribute much either to fundamental understanding of the variations nor to practical precautionary measures for the farmers merely to describe the rainfall curve as quasi-periodic. All attempts to forecast the fluctuations by means of extrapolating "cycles" derived from analysis of past records have been failures. Scientific bases for long-range forecasting are being sought in many directions but the solutions offered do not yet give results of practical value and general ap- plicability, however promising the method or enthusiastic the advocates. The most successful results so far are for certain special conditions and places, none of which have been in the West Indies. Diurnal Variation The diurnal distribution of the rainfall, as at San Juan, shows a much greater amount of rain by day than by night, judging from Mr. A. Wal- loe's observations at Charlotte Amalie, published in the "Set. Thomae Tidende", 1888. He gives the following figures. TEXT TABLE6 NIGHT AND DAY RAINFALL, CeAALOrTE AxALig, 1888• Moatll (ISSS) July Aupst Sepumber Total 38.4 77.2 69.0 • In lines; 8 lines = I inch. By day 26.S SS.9 44.6 Bynlpt 11.6 21.J 24.4 The frequency of rain is no doubt also greater by day but the contrast is probably not so pronounced because the intensity of the day showers is heavier. I U i . l (),:i l .,,,,,,.. ' • - . .Jt'' : ,. -.. ....... . ·. · itettf • -P 21:.,._. · ·. -...,.r,•_. ___ .;P' ..l.;.l~• 26 SCIENTIFIC SURVEY OF PORTO RICO At sea the rainfall frequency is a maximum at 6 A.~I. with a secondary maximum at about 10 P.:\L The amplitude of this daily variation is pre- sumably smaller than the one observed O\'er the islands, where the maxi- mum comes in the afternoon. It is very likely that the sea maximum at 6 A.:\I. affects the islands, or at least their shoreward margins, causing a secondary maximum at that hour. Xo hourly observations are available from the islands but the sunrise shower seems to be recognized by the residents as a more or less regular phenomenon. The daily double period in the rainfall is of course reflected in the cloudiness ( TEXT TABLE 17) and in the frequency of thunderstorms. Intensity and Frequency The rainfall in this low latitude and oceanic situation is entirely of the shower type, and therefore it is of great practical importance to know how frequently showers occur, how long they last, how much rain falls per shower, and what are the average and maximum rates of fall over short periods of time. Unfortunately systematic observations using recording rain gages were begun in the islands only very recently, so we are forced to infer much from the usual rainfall observations which give only monthlv totals and numbers of rainy days. The average rainfall per rain day (A~PENDIX TABLES 10 and 12; FIGURE 10) indicates some important characteristics. The "showers" of the winter and spring seasons are characteristically brief and light, often mere sprinkles, from cumulus clouds of small or moderate size and spaced by large intervals of blue sky (cf. TEXT TABLE 9). Sometimes "norther" effects cause a low overcast cloud deck with driz- zling rain punctuated by occasional heavier showers, which condition may persist a day or two. However, xerv heaxx raios ng tg 2 or 3 iocbcs io a da have fallen eveni"n the driest months. In the "rainy season", from • lay to ov vier and more enduring showers t under and at times, are to be e. least one s o o some sort then falls almost every day. Heavy rains lasting as much u 6 or 8 hours, even with hrief intermissions, are normally very rare, but passage of a hurricane within _s9_ or_lQQ.m.iles can cause enor. mous rainfall totals (o\·erJO ingieiliiu~ar twolrom i.:ictuall¥ con- ◄ !i_nuous downooun1 The high wind during hurricane weather adds greatly to the destructive effect of the rain. Some significant deductions can be made from the results of the re- cording rain gages, in spite of the short period they have been in use. At the Marine Barracks of Bourne Field on St. Thomas a recording rain STONE: JIETEOROL gage has been operated since i TABLE 12 and FIGURE 10) indi and also per rain hour for eacl fall during any 2-i hours of ti· teresting relation because in ti places we can assume that th• tabulated by the U. S. \Veath( basis for estimating the a,:cra~, Since February 1940. t!1e S( rainfall rates monthly from re1 estates on St. Croix. An abstr and 8. Although the period of averages or extremes likely to study of the tables re~eals a _ch rainfall and the maximum mt the average intensities. This i, showers probably have more numerous lighter showers. Tl average intensity to be great• months. It will be noted, howt months appears to be as higl· whereas the total rainfall is l1 the spring. This is a curious . the greater frequency of hail the late summer and-autumn. t tensity of rainfall will actu~ll: because of hurricanes. The irr. excluded, winter and spring ~ tensity as the autumn rains. bt- riods as shown in TEXT TABL great~r in the "rainy season" t to infer to what extent this islands, as the topography m well as the totals, but the Bour to show similar features to t~c Any practical interpretat1c Virgin Islands, especially on that a large proportion of the J ( see TEXT TABLES 9 and 10) · ? rain gages and they augment significance for crop growth ·.·; . .I} !' PORTO RICO nun_1 at. 6 A. :-.r. with a secondary -~ or this daily \'ariation is pre- er the islands, where the maxi- kely that the sea maximum at shoreward margins, causing a ,urly observations are available eems to be recognized by the eno_n. The daily double period toudmess (TEXT TABLE 17) and ·quency nic situation is entirely of the tical importance to know how last, how much rain falls per ,·,m• rates of fall over short Jb9b.-1·ations using recording cry recently, so we are forced ,bservations which give only rhe average rainfall per rain 0) indicates some important easons are characteristicallv cumulus clouds of small 0·r of blue sky (cf. TEXT TABLE nvercast cloud deck with driz- ~wers. which condition may 'c1ms up to 2 or 3 inches in a r 11 the ''rainy season", from ig showers. with squalls or . ected much more often; at 11ost every day. Heavy rains · intermissions. are normallv >r 100 miles can cause eno;- _1· ~r two from virtually con- rr1cane weather adds greatly ,rom the results of the re- l they have been in use. t. Thomas a recording rain STO.VE: .lfETEOROLOGY OP THE T"IRGIN ISLANDS 27 gage has been operated since 1935. An analysis of the results (APPE:-;01x TABLE 12 and FIGURE 10) indicates that the average rainfall per rain day and also per rain hour for each month is proportional to the greatest rain- fall during any 2--1- hours of the corresponding months. This is a very in- teresting relation because in the absence of recording rain gages at other places we can assume that the "greatest rainfall in 2--1- hours", which is tabulated by the U. S. \Veather Bureau for all its stations. gives a rough basis for estimating the a1Jeragc intensity of rainfall per day and per hour. Since February 194-0, the Soil Conservation Service has been tabulating rainfall rates monthly from recording gages at Anna's Hope and Jolly Hill estates on St. Croix. An abstract of the results appears in TEXT TABLES 7 and 8. Although the period of observation is too short to give any definite averages or extremes likely to occur, the figures are already significant. A study of the tables reveals a closer correlation by months between the total rain fall and the maximum intensities than between the total rain fall and the average intensities. This is not _surprising because one or two intense showers probably have more effect on the monthly totals than the more numerous lighter showers. There is nevertheless some tendency for the average intensity to be greater in the rainier months than in the drier months. It will be noted, however, that the average intensity in the spring months appears to be as high as or higher than in the autumn months, whereas the total rainfall is usually much greater in the autumn than in the spring. This is a curious fact which we have already suspected from the greater frequency of hail in the late spring and early summer than in the late summer and-autumn. Over a period of many years the average in- tensity of rainfall will actually be greatest in the autumn or late summer because of hurricanes. The important conclusion is that, if hurricanes are excluded, winter and spring showers probably have as great average iti- tensity as the autumn rains, but the 1na.rimum rates of rainfall in short pe- riods, as shown in TEXT TABLES 7 and 8, are generally two or three times greater in the "rainy season" than in the winter and spring. It is impossible to infer to what extent this conclusion is justified for all parts of the islands, as the topography may greatly affect the rainfall intensities as well as the totals, but the Bourne Field results (APPENDIX TABLE 12) seem to show similar features to those of Anna's Hope and Jolly Hill estates. Any practical interpretation of the average rainfalls reported in the Virgin Islands, especially on St. Croix, should take into account the fact that a large proportion of the rain falls in light showers and brief sprinkles (see TEXT TABLES 9and 10). Many of these light rains are measured in the rain gages and they augment the total rainfall out of proportion to their significance for crop growth and for vegetation because they barely wet iUI uul 28 SCIENTIFIC SURVEY OF PORTO RICO TEXT TABLE 7 RAINFALL INTENSITIES MEASURED AT STATION SCS No. 18 F. S. A., JoLLY H1u. ESTATE, ST. CR01x, V. I. (From U. S. Soil Conservation Service) -- Total Toul Average Maximum Intensity for Different Intervals Rainfall, Duration, Intensity, ~lonth inches hours• in.;hr. 5-mln. 10-min. 20-min. 60-min. 120-mln. ----- -- - - - -- -- - -- - ---• - - 1940 February 0.90 15.02 0.06 1.00 0.75 0.35 0.13 ~larch O.S2 1.92 0.27 April 1.97 6.42 O.Jl 2.00 I.SO 0.80 a.so 0.28 ll&y 7.10 30.00 0.24 J.SO 2.00 1.40 1.10 0.70 June J.OS 8.10 0.38 2.00 I.SO 0.90 O.H 0.30 July 2.14 5.07 0.42 5.00 3.SO 2.SO 1.30 0.6S Aucust l.OS 12.37 o.zs J.00 1.75 0.95 a.JO O.IS September 4.19 12.65 O.lJ 7.00 5.00 J.40 1.40 0.7S October 7.47 22.45 O.JJ 4.SO 2.7S 2.80 1.70 I.OS November 7.15 H.37 0.28 5.00 J.SO 2.40 1.45 0.90 December l.47 20.25 0.17 l.50 2.25 1.60 0.85 0.45 1941 January 1.97 S.02 0.39 2.00 1.75 0.90 0.40 0.20 February 0.21 0.80 0.26 Marcb 1.Jl l.ll 1.17 I.SO 1.00 0.50 a.ta April 2.28 9.45 0.24 l.75 z.so 1.40 0.56 0.30 • Intensitla of •- than 0.10 in./hr. are not lnduded. TaXTTABU8 RAINFALL INTENSITIES MEASUUD AT STAnoN SCS No. 15 F. S. A., ANNA'S Hon EsTAn, ST. Caorx, V. I. (From U.S. Soil Conservation Service) Total Total Averaae MuimllJII Intensity for Dillerent Intervala Rainfall, Duration, Intensity, 10-min. 20-min. 60-min. UO-mla. Month ioches boun• in./hr. 5-mia. 1940 i~ O.JS 2.11 0.13 1-09 17.18 0.12 1.80 I.ZS 0.75 O.JO 0.18 Maida 0.99 4.92 0.20 1.00 0.75 0.35 0.13 A,:1 1.SS 4.20 0.37 J.SO 1.75 1.20 0.80 0.43 ,. y ua IS.OS 0.19 2.00 l.SO 0.80 Q.40 0.2S June 1.56 4.60 O.J4 J.00 2.25 1.lO 0.40 0.20 July 1.17 4.23 0.2a 1.00 0.75 O.JS 0.13 A,.._ 1.15 7.48 Q.23 3.00 2.00 0.80 0.30 0.15 Sepcedier 5.24 6.67 0.82 7.00 5.00 4.20 2.30 1.18 October 8.43 22.05 o.JS 4.00 J.00 2.00 0.80 a.so NOYember 6.05 14.67 0.41 7.00 5.50 J.JO 1.10 0.60 December 2.36 14.10 0.17 I.SO 1.00 0.45 0.18 1941 O.JI January J.67 12.15 0.30 4.00 2.50 1.60 0.60 February 0.19 2.50 o.oa 0.15 March I.OS 2.83 0.37 1.50 1.00 0.50 0.20 April 2.48 7.25 0.34 4.00 3.00 2.60 0.92 0.41 • Intensities of less than 0.10 in./hr. are not Included. 1 i \Ul STONE: METE the vegetation and the t quickly evaporated by th PERCENT AGES Of l CaR (Fr• --- -----~-- MOGth January Felmw'Y March = Jwae July Aupll September October NOYember December Yaz AVERAGE AND ExTJu:; Month Yaz • Theoe &cures att not sums r year in the period covend by the ;.\.'.::;. I 1: \; ,I ! l' I 1,l 30 SCIESTir-IC SCR1'EY OT- PORTO RICO Evaporation The actual water loss irom the ground by evaporation and by transpira- tion of plants is probably high, judging from the general weather condi- tions and from the measures oi c,:aporating po·wcr of the air made at the Experiment Station ( see APPEXDIX TABLE 8). Consequently, the roughly 45 inches of measured average annual rainfall in the Virgin Islands is hy no means the equivalent for plant growth of 45 inches of measured pre- cipitation in rainier parts oi the \\'est Indies or in the southern United States. Thunderstorms, Squalls, and Hail Tl11mderstorms occur, as in Porto Rico, chiefly from July to October, according to the records at Christiansted and Bourne Field (TEXT TABLE land APPENDIX TABLE 12). Schomburgk in 1837 reported that 5 to 10 per cent of the days in a year had thunderstorms, mostly in September and October, which roughly agrees with the Christiansted data, although at Bourne Field more of the storms occur in July and August. Most storms probably occur in the afternoon, as at San Juan. They are apt to be squally and inflict wind damage at times, but lightning damage is usually slight. Squalls are sometimes associated with heavy showers and probably with most thunderstorms. The familiar downrush of cold air under a thunder- storm or tall cumulonimbus cloud can be so violent as to capsize small boats and damage dwellings, trees, and crops. When the observer is located on the sunny side of the cloud. it may appear white until after the squalls reach him, giving rise to the term "white squall" of the West Indian na- tives ; but when the observer is under or on the shaded side of the cloud. it appears very dark and ominous. so the accompanying gusts are called "black squalls". White squalls are also reported without heavy clouds nearby, but these are merely gusts when the trades are blowing strongly. The We.t Indian sailor well knows that the squalls are apt to be especially violent anddangcrous to boats along a coast which rises to high mountains immediately back of the shore. Hail is rarely reported and most residents spend a lifetime in the islands without seeing any. There are enough authenticated reports to leave no doubt that it falls at least every iew years. even several times in some years in which conditions are farnrable for it. :\Iuch hail. with cold and rainy weather, occurred in Virgin Gorda in January 1833, according to Schom- hurgk, who also wrote of hail on the north side of Tortola in November 1829. Knox mentions that hail as big as hen eggs fell in St. Croix on April 13, 1844; and that a Mr. !\"issen told him of a hailstorm at St. ~· . • STONE: METl Thomas on May 13, 18. St. Thomas in 1938. Alt early summer, the cases ter and spring; perhapf thus more likely to be re: Chemical analyses of Station from 1911 to l~ tained an average of 9 nitrogen in the form of These figures varied g1 The amounts do not see appear to depend on th, that they are related to These chemical constit, .soil and the nourishmer "' Owing to the small at ration, and the few pe1 obtain domestic water : and stored in cisterns, a crete to catch rain for strict economy in use o: Shallow dug wells an pumped for flushing 1 stocked with "mosquit spread chiefly by mosc of La Grange plantatio St. Croix was started but not on a scale suffic not yet been tried. Stor on which it was used £o ()! . .) 1. Temperatures in th Porto Rican stations , small land area availal RICO r. Cao1x, V. I. ·· for Diffettnt Intervals nin. 60-min. 120-min. j 3S 0.IJ 0 o.so 0.28 0 1.10 0.70 J o.ss 0.30 80 1-JO 0.6S 05 O.JO 0.1S ) l.40 0.7S J l.70 I.OS 1.4S 0.90 -~ 0.85 0.45 ) 0.20 "-o-:18 0.56 0.JO ·ao1x, V. I. lill'erent lntervall 60-min. 120-min. 0.JO 0.18 0.IJ 0.80 0.4J 0.40 0.25 0.40 0.20 ' c 0.13 O.JO 0.1S 2-JO 1.18 0.80 o.so 1.10 0.60 0.18 0.60 0.J8 0.20 0.15 0.92 0.48 l STONE: METEOROLOGY OF THE VIRGIN ISLANDS 29 the vegetation and the top of the soil and do not sink into it, and so are quickly evaporated by the sun and wind. TEXT TABLE9 PERCENTAGES OF DAYS WITH SPECIFIED AMOUNTS OF RAINFALL. ~- - ---- - - CaRISTIANSTED, ST. Caoix, 1852-1907 (From Willaume-Jantzcn and Ravn) ----'-----'----- ;;;: 20 mm 0-Smm (0.79" Month (0-0.20") or more) January 67 5 February 64 J March 66 4 ~ ss 16 • y S6 10 June 46 14 J1dy ss 10 AIIIUll 54 11 - September 45 15 October 44 IS November 48 12 December 52 a Year 54 11 TUT TABL& 10 ~somm (1.97" or more) 0 0 0 2 4 J z 4 4 7 J 2 3 AVDAGE AND EXTREME NUMBERS OF DAYS WITH RAIN, CsusnANSTED, ST. CROIX, 1852-1907 (From Willaume-Jantzen) Hilbest Lowat Month Mean in any one year inuyODeyear !~ 11 20 2 9 2J 1 Mardi 6 14 0 ~ 7 lJ 2 11 26 J Jue 10 20 4 July 11 17 4 Auaut 11 17 4 Sepiember IJ 19 6 October 12 19 6 November 14 20 4 December 1J 19 6 ----- ---- Year 128 111• a◄• • Tb- fisures are not sums of the columns above, bllt are the a:treme totala OD record for any ODe year in the period covered by tbe table. :..:. REFERENCE NO. 5 : i; ! I . - CLIMATOGRAPHY OF THE UNITED STATES NO. 60 Climate of Puerto Rico and Virgin Islands ············································ ·········· ........ . ············································ ·········· ........ . :::::::::::::::::::::::::::::::::::::::::::: :::::::::: ::::::::: !i!ii!!ii!!ii!!iii!!i!!iii!!iii!i!!~ii!!!ii! :=!\[!\\!\ ii!!\\!!! ············································ ....... ········· ············································ ........................................... .......................................... ......................................... ........................................ ....................................... ···························· . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................ ···························· ···························· ···················································· ..................................................... ···················································· ···················································· .................................................... .................................................... ..................................................... ............................. ......................................... . ..................................................... . ······································································· ···································· ................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .................................................. . • • .. • • .. • .. • • • • • • • • • • • • • • • • .. • • • • • • .. • • • • • .. • • • • • • • .. .. • • • .. • .. • • • • • • .. • .. 11 .. .. .. .. • • .. • • ....................................................... . ······································································· .................................................... . ......................................................................... ···················································· ......................................................................... ···················································· ······································································· ···················································· ......................................................................... . .................................................. . ······································································· ···················································· ......................................................................... ....................................................................... ······································································· ······································································· ······································································· ······································································· ······································································· ······································································· ............................................................................ ............................................................................. ··············· .. ········ .. ··· ................................................... . .................................................................................. : : : : : : : : : : : : : : : ::~:::::::::::::::::::::::::::::::::::::::::::::::::::: :::::::::::::::::::iii::::::::::::::::::::::::::::::::::::::::::::::::: ............................................................................. : : : : : : : : : : : : : : : : :+:::: :: :: : : : : : : : : : : : ; : : : : : : : ; : : : : : : : : ~ .................................................. ,.. : : : : : : : : :::::::::::.ii::::::::::::::::::::::?~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~i~~~~TI~~~~~ ~ii~~~~~~~ i ~ ~y~ .............. ........ ,. ........ / ..... .,- ···;,, 7 noaa NATIONAL OCEANIC ANO / ENVIRONMENTAL/ NATIONAL CLIMATIC. CENTER ATMOSPHERIC ADMINISTRATION DATA SERVICE ASHEVILLE. N.C. REPRINTED JUNE 1982 ·r; i ! uo J ," .q. ···, i • Due to the small size of the islands·and the location of all stations within a few miles of the water, the mean daily range is quite small. It varies from 9.1° at Charlotte Amalie to 15.1°F at Wintberg. For these same reasons extremes of temperature are not as great as they are in Puerto Rico, and relatively few days have temperatures of 90° For above. Since the extent of land areas is small, the air passage over land is quite short and there is not sufficient time for extreme heating to take place. On St. Croix, Annas Hope has had a temperature as high as 99° F. During the warmest months, maximum temperatures average about 87° to 89° F, with nighttime temperatures falling to about 74° to 78° F, and a little lower at the higher elevations. In the winter, daily maximum temperatures are generally in the low 80's and nighttime minima in the high 60's or low 70's. The highest mean maximum temperatures are found in August, while the lowest mean maxima fall either in January or February. The lowest mean minimum temperatures are observed in January and February, and the highest mean minimum temperatures are generally in July or August. DROUGHT - Drought in the Virgin Islands occurs about as often and is just as damaging as it is in Puerto Rico. None of the three islands has any significant running rivers or streams and only St. Croix has an u~derground water source in a few sections. Water for irrigation is not available in quantity at any time. Large storage reservoirs do not exist so the Virgin Islands are, to some extent, more at the mercy of "Mother Nature" than is Puerto Rico where there are adequate facilities for water storage. HAIL - In the U.S. Virgin Islands, hail is even less frequent than in Puerto Rico. In January of 1969 a severe local hailstorm with hailstones up to 1 1/2 inches in diameter occurred. This was the first hailstorm on record in the U.S. Virgin Islands. 20 I U i uu .1 .,;:4 :·,d ~hie lifting of the_moisture laden air over the hilly terrain of these islands is the most frequent cause of ra_~nf~U. -- However, due to the smallerel-evat:!ons and smaller size of the islands, there is a less marked variation in annual amounts. The larger mean annual totals are between 50 and-60 inches at the higher elevations, and the variation between the greatest and least average value is not as marked as it is in Puerto Rico. Clouds formed by forced ascent of the wind over small and narrow islands, as is the case for St. Thomas and St. Croix, lean to the leeward, so that most of the rain from them falls in the ocean to the lee of the island. Easterly wave passages are important contribu- tors to the rainfall of the Virgin Islands during the months from May through November. Like Puerto Rico, the U. S. Virgin Islands lie in the path of the tropical storms and hurricanes which form over the ocean to the east of the Lesser Antilles. As in Puerto Rico, they are relatively infrequent. While cold frontal passages affect the rainfall regime of the Virgin Islands, the frequency of fronts is less and their intensity is more likely to be diminished and less effective than in Puerto Rico. Annual rainfall values indicate differences in rainfall from location to location with higher elevations generally receiving greater amotmts. On St. Thomas and St. John, on the basis of the limited data available, a.nnual._~vera 40 and 60 inches a a e. On St. Croix there is a more noticeable var at on from place This Island has the greatest annual rainfall, in excess of in the northwestern corner. There are some indications that stations in a small area along the central portion of the southern coast of St. Croix receive about 40 to 45 inches. A narrow. finger of between 25 and 35 inches extends northeast to southwest over the flatlands south of the hills in the western portion of the Island. Annual rainfall averages less than 30 inches in the eastern end of St. Croix, possibly as low as 20 inches. As in Puerto Rico, there is no sharply defined wet-dry season relation- ship. Records available for the three islands indicate a relatively wet-relatively dry season distribution similar to that found in the southern portion of Puerto Rico. The relatively dry period extends from about December through June. Occasionally, quite heavy rainfall occurs during the so-called drier months. The driest month of St. Thomas and St. John usually is February or March and the wettest month September or October, as in the southern sections of Puerto Rico. On St. Croix, the month with the heaviest rainfall, on the average, ranges from September through November. The number of days with measurable rainfall over the Virgin Islands, based on a few known-to-be reliable stations, ranges from a little less than ZOO days annually at the higher rainfall stations to less than 100 days annually at the stations with lowest rainfall. As in Puerto Rico, one of the most striking fea~ures of the temperature regime in the U.S. Virgin Islands is the relatively small variation from the coolest to the warmest months, ranging from about 5° to 7°F. 19 ·\ t. i l i_)i.):L comfort or discomfort, between economic success or failure, or between safe and compatible building design can be a delicate one. Through effective planning and intelligent application of climatic considerations to life in the Caribbean, man can truly say he has found his tropical paradise. U. S. VIRGIN ISLANDS Location: The U. S. Virgin Islands are composed of three major islands, together with a number of smaller islands and cays totaling about 50. The three of primary importance are: St. Thomas, where the capital is located; St. Croix, the largest; and St. John, the smallest. These islands follow Vieques Island and Culebra Island in the path of the Lesser Antilles toward South America. St. Thomas lies some 38 miles east of Puerto Rico and about 1,500 miles southeast of New York. St. John lies a few miles east of St. Thomas and St. Croix is located about 40 miles south of St. Thomas and St. John. With an area of about 28 square miles, St. Thomas is the second largest of the U.S. Virgin Islands. This island lies between latitudes 18°23'N and 18°18'N and longitudes 65°03'W and 64°SO'W. It is about 5 miles from its northernmost to its southernmost points and a little more than 12 miles from its eastern to western extremities. The smallest of the three principal islands is St. John, with an area af only about 20 square miles. It is also the least populated. St. John lies between latitudes 18°23'N and l8°18'N, and longitudes 64°48'W and 64°40'W. This island extends about 5 miles from its northern to southern- tips and about 8 miles from its easternmost to westernmost points. Somewhat apart from the others, the largest of the three islands is St. Croix which has an area of 84 square miles. It lies between lati- tudes 17°47'N and 17°4l'N, and longitudes 64°54'W and 64°34'W. The Island extends some 19 miles from east to west and 6 miles from north to south. Topography: St. Thomas has .an extr!_mely irregula~~-C>_~~ tJine and is very hilly with practically no flatland. The highest hills are generally -roundnear--the--~enter of the Island, with Crown Mountain at 1,550 feet the highest point. The Island is relatively small and many of the peaks rise above 1,000 feet. Thia results in rather steep slopes over all the island, so that rainfall runoff is quite raid and there are no er- manen • Like.St~ Thomas, St. John has an extremely irregular shoreline and a very hilly topogra?hy. It has a number of peaks over 1,000 feet, topped by Bor4uux Mountain at 1,297 feet in the eastern portion of the island. Slopes are quite steep over all of the island, and there are very few areas of flatland. There are no permanent rivers or creeks. 17 1 ·1_J 'j () !_J J ~ :,,:,:. ,~ ... ;() I St. Croix is the largest of the three U. S. Virgin Islands. The topog- raphy is somewhat different from the other two with a broad expanse of low, relatively flatland running along the southern two-thirds of the Island. A range of hills, ranging in elevation from about 500 feet to more than 1,000 feet, .topped by Mount Eagle at 1,165 feet, runs along the northern coast. In the eastern end of St. Croix is found another group of slightly lower hills with a maximum elevation of about 860 feet. The relatively small area covered by hills on St. Croix results in rather steep slopes down to the Caribbean in the north and to the level areas to the south. Agriculture is not as important in the U. s. Virgin Islands as it is in Puerto Rico. St. Croix is the only one of the U. S. Virgin Islands with any sizable expanse of flatland suitable for farming. Here sugar cane, which was the principal crop, has been abandoned. Subsistence crops are now a minor effort. Some cattle are raised for milk and meat. In St. Croix, industrial growth has become a significant factor in the island's economy. With the downgrading of agriculture, industrial complexes have been expanded to include the petrochemical industry and refinement of aluminum. Light industrial plants and the manufacture of rum are the other industrial activities in St. Croix and St. Thomas. St. John has no industrial development and remains primarily a National Park. Tourism is the biggest factor in the Virgin Islands economy. It has, over the past years, undergone a vast increase in the numbers of cruise ships, especially at St. Thomas and St. Croix. Hotel facilities have been increased on both islands. One of the principal causes of concern in the U.-S. Virgin Islands is the short supply of water. Rainfall, while above 40 inches annually over most of the area, is insufficient. This is due partially to a high evaporation rate and the rapid runoff from the steep slopes on St. Thomas and St. John and, to a certain extent, on St. Croix. In an effort to utilize available water efficiently, most homes and business establishments catch rainwater on the roofs and pipe it to cisterns. The runway at the airport at St. Thomas is also used as a catchment area. On St. Thomas and St. John it is common to see the entire side of a hill cemented to act as a catchment area. Generally, during the drier portion of the year, it is necessary to carry water by barge from Puerto Rico. Installation of a sea-water distillation unit on St. Th011&a and St. Croix has helped alleviate the water shortage but water still raains a significant factor in the development of the island's ecQIIOIIJ. Rainfall in the U. S. Virgin Islands is of the same nature as that in Puerto Rico, falling most frequently in the form of brief showers. The rainfall-producing mechanisms are essentially the same as in Puerto Rico except in the matter of degree. 18 I U 1 · ,: ) , i l ,,: ,:l b .i REFERENCE NO. 6 TAT-02-P-04642 TO'l'O WELL SITE POTABLE WATER ALTERNATIVES REPORT AMNA'S RETREAT, ST. THOMAS, U.S. VIRGilf ISLA.NOS Prepared Por: carloa •• O'Neill, P.B. osc Luis J:. Santos, OSC Air and Bazardoua SUb■tance Staff caribbean Field Office O.S. EPA, Reqion II Santurce, Puerto Rico and Bruce Sprague, Chief Incident Response and Prevention Section O.S. EPA, Region II Edison, •ev Jersey 01137 Prepared By: Rodolfo Ratner, TAT II J .... Nanfreda, TAT II Region II Tecbnical Aaaiatanca Teua Weaton/SPER Division Edison, Mew Jersey 01137 December 1988 .. 1 appear to be sutticient land available to increase the cistern volW1es laterally. The only way the volWle could be increased is by ••king deeper cisterns. This operation would require the shoring of the existing hoaes and apartaents, therefore, the possibilty of structural daaage to th••• residences. 2. o SITE DESCJUPTIQN NfD CQRDITIQNS 2.1 sit• Background and conditions The TUtu Well site ia located at the eastern end of the Island at the Anna's Retreat Section of St. Thomas (see Figure 2-1 page 5). Moat of the wells are used for public drinking water supply. Tbe wells appear to be drilled into the TUrpentine Run aquifer. on, or about July 7, 1917, Nr. Irie Tillett, contacted the O.S. Virgin Islands (O.S.V.I.) Deparbaent of Planning and Matural Resources (DPlfR) regarding an odor eaanating fr011 the raw vell vater on his property located at Anna's Retreat, st. Tho■as, o.s.V.I. on July 16, 1987, the OSEPA received a request troa the DPIIR in St. Tboaas, tor AJll)ling and analy-• of several vell• in Tlltu. on July 21, the OSIPA and ita Technical Assistance T- (TAT) contractor, Roy P. lfuton, Inc., aobilized to st. Thoaas, to perfora saapling on th• drinkincJ vater well• ■u■pected of being contaainated. Th••• wells were also reported to have a strong, unpleasant odor and were found to be contaainated vith hazardoua substances. The EPA and ita Technical Assistance Te- (TAT) in coordination vith DPIIR, initiated saapling of vell• in the affected area in July 1987. Tbe tut resulta showed the presence of high concentrations of gasoline and chlorinated organic ccapounda. Pour vells: Elgin, Four Winds, Bartl:lllan, and Virgin Islands Housing Authority (VIBA) vere closed dovn by order ot DPNR due to high voe concentrations. Several of the vells in this area are major c011■ercial well services used for public drinking water supply, therefore, the incident vaa classified as ■ajor, and the DPNR co-issioner requested the EPA to assume the role of Lead Agency. The vell locations can be s .. n in Figure 2-2 page 6. A Texaco station, located opposite the Tillet Well, is suspected as a po■aible source of contaaination. A Petrotight test conducted on the underground storage tanks at this tacility indicated leaks in two of the three tanks. Th••• failures aay have contributed I !.Jr uu .l :,.:·.c1,:c,4 GREAT.,) N_ORTH~ SIDE " - - -----·- ..... ,.. I \ NO. WE!..L N.~\!E NO. J UY.l."fS 1" I -· -'wtm>SJ 2 IODIIC:UES 12 2 " 'llNDS 2 I 3.1 a.ufflDLUf IAIDY J3.l 'IIIU 1 I I 3.2 a.umDUN BAKERY l:U VDU 2 f ~ a.urnDUN 8.llDY 13.3 VDLl 3 I 4.1 CENE £CUlf 1 13., vtlU" u C:ENE £CUN Z u -'LPSA LIDNAID "-3 CD£ ECI.Df 3 !5 DElffl'BI 5 IURYr."'S !4 DDC!I , j 5 !T'EE!.t'S :~.l D£VC:>N 1 l 1 M.>.T'BU!'S 1--., DEVCON 2 ·- I swmrs 1-:'.3 D£VC>ff 3 I FRUfQIS 11 DIDI I 10 'TUJ..ffS 11 LQaJWtT u &IMS.Er'S _RED BOOK F?.!NC!DLANS 3AY • to the groundwater pollution problem, resulting in the contamination ot nearby wells. Another suspected source of contamination is the TUtu Esso gas station. This facility storu waste oil in an underground storage tank. The facility bas had proble■s in the past with leakage fro• their underground gasoline storage tank and 1• auapected ot using solvents in the aec::hanic shop. At the tiae ot inapec:tion, the nature of the probl- had not been detenained. Both th• Texaco and Esso gas stations are upgradient troa the affected vell• vbicb are being supplied with water. EPA continued its efforts towarda the identification ot; affected wells in the area, cuato .. rs which bad received vater froa contaainated wells, and possible alternate water supplies and reaedial action alternativu. A testing progra■ of wells located outside ot the known area of contamination was conducted to evaluate tho•• areas as possible alternate water supply sources. Sampling of cisterns served by the contaminated wells was also pertor■ed. EPA directed the bergency Response Cleanup Services contractor (ERCS) to; clean and disinfect the five (5) cisterns which had tested positive for PCB, aodify the exi•ting hoae pluabing, di■coMect the contaainated-vella, and dispose of the contaainated water. At EPA'• direction, DCS also contracted a local water bauler to deliver uncontaainated drinking water to the ci•t•rna by tank truck. A well smapl1ng progr- va• establ1ahed by the EPA to 110nitor the wells at the TUtu ait• for a one year period. Nin• potential responsible parti•• bave been identified. Th ... facilities included three 9aa0lin• service stations, two vehicle aaintenance repair shops, tvo territorial govenment aqenciu, one dry cleaner and one abandoned gasoline service station. EPA has identified Texaco as a viable potentially responsible party, based on the results of a soil/gas survey conducted on the Texaco Property under order fro■ DPNR and under the supervision of EPA. The survey found total hydrocarbon concentrations up to 690 ppm of benzene. EPA is continuing its efforts to identify potential responsible parties. 2.2 Topography and Gegloqylll •st. Tboaas is the aoat northweat island of the o.s. Virgin Islands and the second largest. Tile island 1• approxiutely 14 ail•• long and 2 to 3 ail•• wide and has an area of 32 square ail••· 7 .. The land surface is alao■t entirely sloping and extenc ••award fro• a central ridge, 800 to 1,200 feet high, running the length of the island. The slopes, which comaonly exceed 35 degrees, are dissected by nwaeroua streaa courses of steep gradient. The general appearance is a panorama of steep interstreaa spurs an rounded peaks. Flat inland is confined to the Olarlotta Amalie area and a fav -11 alluvial-filled eabayaenta. Tb• only variation in the general topography is in the upper valley of TUrpentine Run in eastern St. Thoaaa. Tb• valley baa relatively gentle topcqrapby conaiating of rolling bills in a basin surrounded by ateep slopes and abarp ridges. Tb• Tutu Formation, the youngest rock exposed on st. Th011&s is coapoaed al110•t entirely of angular debris derived fro. the Louisenhoj Ponaatton (an older volcanic foraation) and ainor limestone debris fro■ thin 11-estone deposited conteaporaneously vith the TUtu Formation. Tb• rocks were sw,sequently tilted to fora a nortbvard- dipping homocline. Dip• range from 15 to 90 degrees and average about 50 deqr .. a. Locally th• foraationa are overturned. Tb• pez1N&bl• zon .. that t.be•• rocu once aay have bad after depoaition have been-destroyed by -taaorpbi- or by depoaition of ■ineral• in pore spac ... Groundwater IIOV-nt is nov limited to openincJa along joints and fault zones. Tb• bOIIOClinal atructure is c::ut by -ts of faults trendinq If 45•w, If 55•z and north. Tbr .. well-defined joint sets parallel each of the aajor fault directions. The valley• of the island have aiailar trenda and are apparently the result of -lective erosion of rock weakened by faulting and jointing. Prt.e zones of grounclvater availability, therefore, follow the valleys. S..11 alluvial deposits ranging fro■ Pleistocene to Holocene in age, lie in the valley of TUrpentine Run in east-central St. Thoaas and the larger coastal eabayaants. Tb• alluviwa of TUrpentin• Run li•• in a narrow band ••ldo• ■ore than 200 feet in width along the streaa. llaxiaml thicJcn .. • of the alluviua is al>out 40 fHt. Noat of the alluviU11, vhicb i• co■poaad of silt, fine sand, and clay and contains discontinuous beds of sand and gravel 2 to 3 feet thick: lies in the Mt. Zion-Tutu area of the upper basin and in the narrow valley fro■ Mariendal to Mangrove Lagoon in the lover basin. Tb• alluvi\111 extends out under the lagoon near the ■outh of Turpentine Run. Although coapoaed predominately of fine-grained material, the alluviua readily infiltrat .. 8 strea.m!low when the groundwater level is below the base of the stream. As such, the alluvium forms a readily rechargeable aquifer, although it is of small extent and yield. so .. coastal embayaents beaded by interaittant atr .... contain maall deposits of alluvim1 siailar to that of Turpentine Run. Maxilnm tbiclm-• of th- deposit• is estiaated to be 50 f-t, and their areal extent ■eld011 is greater than a few acres (an exception being the Long Bay and Airport areas near Charlotte AIUllie). Near the sea, tbe alluvium interfingers with calcareous sand and at t1-es contains lenses of JlllnCJTOVe SVUlp deposits. Therefore, tb• depositsc!fe ot •inor significance as sources of water•. 2.J Rainta111ll wRain is the only natural source of fresh water to replenish the water resources of tbe island. RainfaJ is seasonal, with a rainy season in late sUENr and early fall and a secondary vet season usually in May. Nearly half the rain falls during August-November. ~ns exceeding 1 inch in 2! :::r: c= •!: r: 1:::n t.,i••• a~ear. F.opr to 15 LMi1-- - f --" __ 1 _____ A hour pe~~ N>PYt once every 2 y• in large atqrwa, m... ra can occur In any aon , bat are aore lllca during the hurricane --■on (Auqust-•oveaber). About ~ ln:ent of the tiae UU1yal rainfall 1• between 40 50 -· Lis• than 10 percent of the tiae annual rainfall is under 35 inch-, vbich usually wna a aajor deficiency during tbe noriaal vet season and drought. The cumulative departure froa average and the 10-year running average of rainfall shova that at this tiae of writing (1967) the island .. y be entering a period of deficient rainfall. With the exception of a few years in the late 1940's and early 1950's, rainfall in the past 30 years has been below average. There has been a long-tena decline of about 10 inches in annual rainfall since the peak of the surplus rainfall period in th• early 1930's. The moat severe droughts on record occcurred in 1964 and 1967, when only 27 and 24 inches of rain fell, respectively. Areal distribution of long-ter11 rainfall, is controlled by topography and the prevailing easterly to northeasterly vinda. However, individual storas .. y or may not show the affects of orographic control or prevailing winds and the arealcffstribution of the storms can be very irregular•. Sae Figure 2-3, page 10, tor average yearly rainfall. 9 1; i: 2.4 sampling Results Th• TUtu well site has been suapled repeatedly over· the last ten aonths and found to contain definite contuaination. Th• initial assesS11ent was conducted in July through S•ptaaber of 1987. Subsequent sampling and analysis bas proceeded on• aonthly baai•. Tb• initial assesaaent conaid•red 26 wells and •pproximltely 50 ci•tema. Of th•- v.lls and cisterns; 24 wells and 5 cist•rna were found to be conta.inated. Tb• 5 ci•t•rna were cl•aned and disinfected by the DCS contractor. Subsequent 110nitoring has be•n conaid•red for the 24 wells that shoved so•• type of contaaination. Table 2-1 pg. 12, lists th• wells included in th• current auipling progrua. Teles 2-2 and 2-3, pages 13-16, show the volatil• organic analysis r•sults of the contaminated wells and giv• the highest concentration of organic conta.ination found during the last six •onths. The suapling, and •ost of the preli•inary Photovac portable GC scr••ning, was conducted by the U.S. EPA Region II TAT. Drinking water lahoratoriu have perfonaed formal an•lysu to verity th• pbotovac scr•ening reaulta and to cover tb• entire spectrua of poa•il,1• baaardoaa contaainanta. AlthOUCJb, tb• concentration of th ... contaainanta fluctuat•s 110ntbly, it i• noteworthy that the -jor conta■inants bav• been 1,2-trana-dicbloroethyl•n• (DCE), trichloroethyl•n• (TCE), tetrachloroethyl•n• (PCE), toluen• (TOL), benzene (BEIi), tart.butyl ••thyl ether (TBME) and varioua -tal•. Their bigb concentration in tour wells: Tillet, B•rvey, S.itb and St••l• h•• been •vident from th• initial •••••...at. Th••• wells abov concentrations of vol•til• organica (VO) in exc .. • of 1,000 ppb. '1'be -jor and ao•t consistent conta.inant •ppears to be PCS. Tb• Tillet well has also shovn very high DCB and B!!M conta■ination. Pour other w•lls; Francois, Mathia•, Pour Winds, and Elgin; were confinaed to have >50 ppb voe •. Tb• last confirmation analysis conducted during OCtober 1917, included th• entir• Raz•rdous Sub•tance List (HSL), (consisting of approxi.aately 150 ch-icals). At that ti••• •ignificant lav•l• of TBIIE up to 470 ppb, and methylen• chlorid• up to 120,000 ppb vere d•tected. so■• sa■pl•• have also •bovn trac•• of vinyl chloride, chloroform, 1,1,1-trichloroethan•, broaodichloroeth•n•, xylen•, and ethylbenzen•. Finally, the BSL analysis al•o shoved th• presence of 11 1·t' '. I • ... ~ ! TABLE 2-1 CURRENT WELL MONITORING PROGRAM AND CLASSIFICATION AT TUTU WELL SITE WELL NAME CLASSIFICATION QPEN/CI.QSEP 1. Dede Public Opan 2. Steele Private Cloaed 3. Elgin fl ccmaercial Clo•ed Elgin f2 co ... rcial Closed Elgin fl co ... rcial Closed 4. Pour Winds ccmaercial Closed 5. S.ith Private Clo••d 6. Bryan co-•rcial Open 7. Harvey Private Closed 8. Tillet Cmmercial Closed 9. Barthllan Estate Private Closed 10. Devcon fl Collllercial Open Devcon fl co ... rcial Open 11. VDIA fl In•titutional Closed VIBA f3 Institutional Closed 12. Dench C0111Nrcial Pimp/No Power 13. Rmlsey Private Open 14. Barthllan Crusher co ... rcial Clo•ed 15. Alpha Leonard Private Open 16. Francois Private Open 17. o..itri• Coaaercial Open 11. llodriguez Auto Private Open 19. llartbaan Baltery CO-rcial Clo•ed 20. Mathias Private Open ' Definition of Classifications Private: Wells which serve on• or tvo houa ... co-•rcial: Well• that are uaed to yield water for sale. Institutional: Wells owned and operated by a non-profit institution or govenmental agency. Public: Well• that are for public use. 12 ~:'lj. _/· J REFERENCE NO. 7 5-7211 101: ,sn, FISH A~D WILDLIFE SERVICE LIST OF E!'IDANGERED AND THREATEN ED WILDLIFE AND PLANTS (50 CFR 17.11, 17.12; As sbowa ia Code of federal Replations. Volume 50. Revised u of October 1, 1983; 48 FR 46057, October l l, 1983; 48 FR 46331, 46336. 46337, 46341, October 12. 1983; 48 FR .. 92". October 15, 1983; 48 FR 527 .. l. 51746. No,ember ll. 1983; .. 9 FR 1058, January 9, 1984; 49 FR 1994, January 17, 1984: 49 FR 1783, 1786. January 23, 1984; 49 FR 6101. February 17, 1984; 49 FR 7334, February 18, 1984; 49 FR 7394, 7397, February 29, 1984; 49 FR 1052!, March 20. 1984: 49 FR U3S6. April 11, 1984; 49 FR 21058, May 18, 1984; 49 FR 12329, 22334. May 29. 1984; 49 FR 17514, July 5, 1984; 49 FR 18565, July 13, 1984; 49 fR 29234, 29137, July 19, 1984; 49 FR 30201, July 17, 1984; 49 FR 31410, Auaust 7, 1984; 49 FR 33885, 33891. Aupst 27, 198.t; 49 FR 3449,1. 34500, 3450.t, 34510, Aupst 31, 1984: 49 FR 35954, September 13, 1984; 49 FR 40038, October I l. 198.t; 49 FR 43069, October 26. 1984; 49 FR 43968, November 1, 1984; 49 FR 44756. No,ember 9, 1984; 49 FR 45163, No,ember 15, 1984; 49 FR 47400, December 4, 1984: 50 FR 1056, January 9, 1985) Title 50-WildUfe and Fisherie9 CHAll'TER 1-UNIT£D STATES FISH AND WILDLIFE SlltYICE, DEPARTMENT OF THE tNTHIOlt SU ■C:HAPT£R 9-TAKIN'l, POSSESSION, TRANS. l'OIITATtON, SAU. l"UltCHASl. 8AltT&lt, 0, l'OIITATION, AND IMl'OIITAflON 0, WILD Llf£ PART 17-ENDANGEltED AND i'HREATENED WILDUf£ AND P\.ANTS Aiildleri.,. Pub. L. 93-205, 87 Stat. 884; Pub. L. 94-.359, 90 Stat. 91 l; Pub. L. 95- 6.32, 92 Stat . .3751; Pub. L. 96-159, 9.3 Stat. 1225; Pub. L. 97-304, 96 Stat. 1411 {16 U.S.C. 1531 ~, s~q.) {Amended by 49 FR 21058, May 18. 1984: 49 FR 22329. 2233-4, May 29. 198-4; 49 FR 27514, July 5, 1984: 49 FR 28565. July 13. 1984; 49 FR 29234. 29237, July 19. 1984: 49 FR 30201. July 27, 1984: 49 FR 31420, Au1111t 7, 1984; 49 FR 33815. 33892. Au1ust 27, I 984; 49 FR 34-494. 34500. 34504. 34510, Au1111t 31. 1984; 49 FR 35954. September 13. 1984; 49 FR 43968. NoYember t. 1984; 49 FR 44756. November 9, 1984; 49 FR 4Sl63, Now-cm- ber 15. I 984; 49 Fil 47400. Dcccmber 4, 1984; SO FR 1056, J..-,y 9, 198S] .... ■-&ala f 11.JJ Fwe 11NI ... ......._. ...... (a) The list in this section contains the names of all soecies of wildlifl! which have been determined by the Services to be Endan1ercd or Threatened. It also con- tains the names of species of wildlife treat• ed as Endan1cred or Threatened because they are sufficiently similar in appearance 10 Endan1cred or Threatened species (sec i11.so,, s,q.). (b) The columns entitled "Common Name," "Scientific Name." and "Venc• brate Poi:,ula1ion Where Endanaercd or Threatened" dl!fine the species of wildlife within the meanina of the Act. Thus. dif- ferently classified aeoaraphic populations of the same vcnebrate subspecies or spe- cies shall be identified by their diff'erin& acoaraphic boundaries, even thouah the other two columns arc identical. The term "Entire" means that all populations throuabout the present ran1e of a vene- brate spcc:ics arc listed. Altbou1h common nama arc included. they cannot be relied upon for identification of any specimen, since tbcy may vary 1reatly in local usa1e. The Scrvic:cs shall use the most rcc:cntly accepted scientific name. In cases in which confusion mipt arise. a synonym(s) will be pro¥ided in parentheses. The Scr- vm shall rely to the extent prac:ticable on the /1111r,1a1ional Cod, of Zoolo11ca1 Nom,nclatllr~. (c) In the '-Status" column the follow• ina symbols arc used: "E" for Endan- gered. "T' for Threatened. and "E (orT) (S/ A)" for similarity of appearance species. (d) The other data in the list are non• regulatory in nature and arc provided for tbc information of the reader. In the annu- al revision and compilation of this Title. the followin& information may be amend- ed without public notice: the spellin& of species' names. historical ran1e, footnotes. references 10 certain other aprlicable por- tions of this Title. synonyms. and more current names. In any of these revised entries. neither the species. as defined in paragraph (b) of this section, nor its status may be cban1ed without followin& the procedures of Pan 424 of this Title. (c) The "Historic Range" indicates the known 1eneral distribution of the species or subspecies as reported in the current scientific literature. The present distribu- tion may be 1rculy reduced from this historic ranae. This column don not imply any limitation on the application of the prohibitions in the Act or implemenung rules. Such prohibitions apply to all indi• viduals of the species. wherever found. (f)( 1) A footnote to the feder■I Resis- t,r publication(S) listing or reclassifying a species is indicated under the column .. When Listed.·· Footnote numbers to §117.11 and 17.12 arc in the same nu- merical sequence. since plants and animals may be li5tcd in the same Fe4trat R .. ister document. That document. at least since 1973, includes a statement indicaaing the basis for the lisung. as well as the effccuve datets) of said listin1. ( 2) The .. Special Rules" and "Critical Habitat" columns provide a cross refer- ence to other sections in Paru 17. 222. 226, or 227. The "Special Rules" column will also be used to cite the special rules that describe experimental populauons and determine if they are essential or noncsaential. Separate listina will be made for eir.penmental populations . and the status column will include the followina symbols: "XE" for an essential experimental population and "XN" for a nonessential experimental population. The term "NA" (not applica• ble) appcarina in ei1her of these l"O col- umns indicates tll,at there arc no spcc1ai rules and/or Crintal Habitat for 1ha1 par- ticular species. However. all other appro- priate rules in Pans 17. 217-:?=7. and 402 still apply to that species. In addition. there may be other rules in this Title 1ha1 relate 10 such wildlife. e.g .. port--of-cnm.- requircments. h is not intended that tne references in 1he "Special Rules"" column (Sec. 17.11(f)(2)) 2-1-tS PuOliMecS by THE IUREAU OF NATIONAL AFFAIRS. INC. Wallllng10n. 0 C. 20037 29 Ii.ii u (_; .1 ~::: ij / .::. I / ENDANGERED WILDLIFE S-713 101:1511 I --- 1· '='fu~ s- , = = s:- ----.. -O'IY--.---1-----------,1-----------+-__::==:__...:.... __ _ Alli111or. Amer1can ....... •--·--· Allip1or missiu1pp1,:•.s" II s- u.U 1 ~~ u.,,_,.. i ! :..:to,91 do . ·······•········•·· ... 00 .......... . .. I -···OD .. · 1 u ~L-= I I I olGA. SCI do .. • .............. I .• • do . , .. OD. U S.A II.A. TX} . do dO .. , ,_ i,, 41 Fa .. JM. 0...-. 11. lffll do ..... I I ·1ne--"f 1--'°'"' Mil=•• aw... ; ~~i.11 •- ... .i C,W.a ... ~ ~• ,a,c;-.; ,j,~ , --• .......... : U.S.A ~ 111,.;o ~---•t--1 ..- £,::.., •.... 111 ··• ...... . ---•·· ·•·-- .1~-... -········-·:-. .. ::: ~ ~~ .... 1 == =- ...... -·: ·j us::i ,:-,- ~,,.:i, .. . .. a.: .. ,JO ........ - (•,o _,c.-u---. -0.:0...,Melr.l,,t - 1 I I ..._ ~ ,.,.:!l-1·'° -. . e,~.,---- ............. ·-·· ... , - Ck•r. 1.1.1,,;. ... _ .. I c:_-~~~~iii"iti'il■=--IO=;;•;;;h;--:::-~;:::;~;'(:.,;.=-=ii-.. .:...;••;..·.;IOl;:l:;..;:;..:,,.~.-"";.w~?.~ . :. :::: .. : ~-:. '"'-.".••w"' •- I r.; ···I .. :c C-. ~. , __ ...,.,.,., .... ;--· ··•···· c-~ ......,.,,_. ..... .,Dret.~~u•.~..a• C:-. •-·· I. ~ .::-.. ~-"'· .•. : &~-. A.,;.,._ ,.__ litaz,, C"-"-$et-t•·· '·0$lllo:I. S...--..-.r ',lc,ut0 ........................ . .... "'2 - ==·.: ·-·- =~~·-- i~~;·==::! .. --.~~eft., : c-c.,...~,. croc=---~- c-,aa.oe.c..-. I •• ~ ::.._ ... , ' CID,.-,;._~ ..... --- , ... ~ .............. I .<10 jO---··· ... C~"-~··. . .. OIi c....:---· . ·•·· .. . . ... ·•·, c.ea .. ·••···--· ct, ~--·· ~.""'91-,~ . ~., ... - ••· .. . ... ······ .. 1-- hen.~.. . .. i, ·_·· .. ·~ ... . - .j c._,,♦..-...-.-.... .. . ····•· - .,__, ~.,. ..,..,._-" .. ·- c,.--.... ~·°""""°· .:.--/.Ill'........, ... c._. .... _, __ "" (',o.:~·•S..- Ge .. ~,-w'\11,"..a; UIL .. ,:, C .J .. . •><• ~~--······ l>odl:- ...... ~ a.····-·· ~ s--. ,-.:i -•·••···•-·--······ " ...... - pte-lf'II ...... ······-···-·· ,o--,A:-..,·ac.., ....... "'---•~ ............... .-c-N···-· ►~ ._.,,."" ........ -·· ·-·••-··-· ~ ... '-.. ~·······-·· ..... .,..;.,i,.,,.,o.,r,0 ~]la' .. c..,,,,a - ··---··--· i;,.ra. ~ ...... ____ _ : <~ --··- ·• ... -······· .. -· ···I 1--.:& .. ... •· .. .. . .... ... . . . .... o~ I ~~-- - •••• ·• • • ·• ·• • ~ ._---.; ,:,,,,_,;...., 114,,... ·-·-··/ .. do ~ c,Xllllft,I,. ~~ """,.,....... .. : ~ ... ..,..,. ... ..,.~ --·- '. .:» . : C•,~-. _ ... ... . .. , ~- A."L , • ..:,..._ ,_.,_ Ef'l••· - i i ,:...,..._ p~~ .ar.:a i ~ ..... ·1~=--······ ISc:11"•• .. i-tq;-,-,.-~- 1EM-• ·- .,_._.pa --11 . P....,,.., ..-_ .._....._,._ -• ~ _-,. .-,.' • 4 ........... , ...a.; ' I lllrMft ()coar,· .. ~... ....... . Sp,-•-o-u -•- ....... ·-- , u SA,,,_. AlaDI ... _ .. _.. ....... oo :fEg-~~ . ~ .. ~J~-E;S ··•·•·· J ~ .... ~~ ·····-········ ······-·••i- - .,_ ...... -· ,_: - •···· !eo.-,...... ·--········ .. -.1,:::: .•. - ..... ... I °" I c,..... . .-,.,•••- . ·--~ - - ~ -· ·-········ .. 1 £.:.:.;~,-~ / Cy.•- - 111,1t..,. . I C.... ....... ··--·•-·••· P'W• ••--. '1 i ,= .. I : P~:ol'loaol 1Ci,cua•l-.... . .... -- .. -· .;~ ........ . J I \ I . 1 I ! I I I ....,,. r:, c:---···-· ---- ,_.,,__ - . ··-·-, "-llr.. .... T.,.._ --- ..... \ ,io !11,_,_....._····· ··•-••· 11.-c ~.... . I ••• <lo .. ...• I 1!;.....,, Gr.-C..-..---·· ...... ---.--.-·-·--- ~-..... ----- ............ ...,.. _·-··--•· ..-,--c..•-··-- ..... w-. - .,_,. ···-·· ........ vwi. c., ..-..·-·•·-····- ..--·---- ····•·······-·· ....... c.-- .. _......,... .__ .. -...... -···---···--· L.-.. ..... ·-··-··-· . 10-12-8' l 5E;~: ~~:::·:::::~~::::~=~:: = =~~=:::::·::::.:~~:! ~: :: :c.-........ ···-······ 1 ul.A.~"'9: .... - ............ j .... dll ,~---······· ............ --T...,._C--.._ .. oo lg:::..·::::::~~:~.::··::·:·:- ::_j ~~-~.::-·· ····' .... : .....-,-~,- ........ /1.1.1.A ,~... ..... ··•·· ~ -- .... . .. ~ ·•········ ... ... - /c.----.--,... i .... ~ 1--- • I~ l.\c.itkJ b) 49 FR 7397. Fcbruar) .:?9. J'J)!f4j (Add(d b~ 49 FR 7397. fcbruar) 29. 19!!4) E , ,, s, : .... ' 6' 111 I ! T ' 20,, ' Nil' ~ ,., T(S/Al . ., ., "" 51 · ~ T(S/Al ., ,· NA ., 1" E. ~~ I 17•.",t. E' J I .. .. 1 ,: 33 ! , • ;:-i-•i e, ., •!At E1 . , "--" I I \ I El •1 ... Ej 2 .. : .,,. , e; 1~ I NA. E 1S I , •• I E 15 I ..... E .! i .. ,. . E -.A [ E ,s I ~ .. ' f ~ ,., ( ,c ,. 1• 1;.:c; I I I IE 15. , ..... E ,, : t,,.l 1 E\ ;! : h4 I :I 1 I ..... ,! I .... , 3, .... El 3, ,.,; E' 15 • ... ! el e, I ,.~. I I f ,5 . .,,. f : ] ~~ I -.11, l ' .... ' E: •~i ' "·~-,. E• 3• ... T: ,~- .... ' T, ,n ..,. ' !, 1 :!t ,.,. , T I '1~. '" I I; I 3. ,.,. I ' ! .. , I E1 1: T I ,_.' ...... Ti ,29: .... I I T I •.:t ' ,.,. ' e' ., NA I E· Ill •.'- I E •21' ~, E 121 I T ,,.1 NA I T 33 I 11 Ht~I I T '211 NA: fl 1,11 NA I Tl ~2t I NA E' . ' ... Ti 1~1 ,,~ .. , E 1"2 ""' - T 142 : NA (IN. 17.11(11)) PutlllllleCI t,y THE IUREAU OF NATIONAL AFF~RS. INC .. WU,,ingtan, O C ::--•- i U 1 out .,::'·<+ ·/ .\. .... ",21a1 17 ,2111 17 '21•1 ,,. .. .. .... .... '"' ..... ...... .. , ,.~ ..... .. .. .. . ... .... "' ,.~ t,A ,.,. "'-' Nil ... ..... .... "'' .. ,. : ... ,_ll .... "'" .... ... .... "'" NA ... NII. "'ll , ... NA NA .. ll MA NII ""' N .. N.A N& hA NA - NA .... REFERENCE NO. 8 __ 1_N_u_s_c_o_R_P_o_R_A_ri_i_o_N ___________________ r_£_L£_c_o_N_N_o_rE__,] CONTIIOL NO: OATI: TIME: 3 /3/<gq I I Lf 1 OISTfUIUTION: \.) l <;Z I C"l <;?Cle, I. 2 1 IE'TWelN: OF: "40ftill: -I. Wo.,..,--~ Sch\ rit t"' r E()/4 -GwH7~. (212 )Z.G,4-tr'l?Lf AND: -O~a_,~ \ :-L'-~- INUSI DIICUS&ION: LlQ ~1,,;•-~:k. c~ - \J ,·r 9 ~ x:1 l~\ ~o~ ba, l:£ k.:~ Ill ~~~~Q~a:tcQ Q..5 Sc~~ e.eu.rs ii, °'f !.J ~:Q(' ~ I ~c~ bg, ~-~ jb..u,v\ t2~~0'11t£.'2.' CLnd2 l:l Q ~~QSg l~ rLr~ e~~c3ll.& - ACTION 11U18: ·- . ,._._·,,i: __ ; .·.,.. ..-:' .t.t ,· <:J ii ... : l REFERENCE NO. 9 Prrmnrcyd In c,>or.wratioo with HK! .. : .. ::.::..:::::.::·.:, ___ --·-·----------·------ ·---T--,----··----------· U.S. Er<l'~rif.».~ NlAL PH(H'EC1i(h\l AGENCY ------,------- ----------...-,,~ . ~ ,, ,. ' .,,. :: c I ,_., ="'·-~•="~'"'"'"" "'"'""" • ~"'-'' = "'" .., .. ,..,,~,"'-= "'"'"""""'"...,,""'="="'-"=-~=:>r>-.c~='-""''~"'"'""~'="'~-"''"''''"''=-"~'"' j ~,,,,,,,, .. _,,...,_,~ .. ..,cr-,.d\!<'-'"'""'-'""'"~'=•''''''"'"''°"'.,......,,., I .. , .... ,.,,. ". ,,,." ,., ·" ~ ... ' .,· "''···•· ,, .. ,,,.: .:.1 Pr~rrnrnrl !n couuara!lor 1t1i'ih llrn l U II r:"11111·,n,p1p,r,,JT ~ I nn1rn:"·,1!J",I ~ ~•c11r~v a~J. tl1i,N.1\Ul'~ll!L r~ J1!., fh1J1Lbi fii 11.!J1 ... 11ch1 i' !'lfl 'J i:V (HJdL! l t/ IJ'I" .,., ·r I (' j r l n ·1:1 r 1'.i 1 C ,J _, ... 1 /"\ ,1 ;;i , v nr: jl 'l '" ..,, o 8 , , '"' Iii: t111 o •1/-1,.ll P<)'J'EN'I'JO.M.J<;T.RJC SURFACE 01? THE TURPENTINE .RUN BASIN AQUIFJf[{ IN THE TUTU ARJi:A, EASTERN ST. THOlvIAS, U.S. VIRGIN LSLANDS, SEPTEJ:IBE:R ll~ 1987 }Jy Robert .P~ Graves fl_nd Ralph Gon.zti.lez G1·oLmcl - water l evels in the Ttirpentine Run basin aquifer , in en.ster n St . Tfl .-.ini;.L,'~, v.'ci.·e rneasut.-ed in 32 we l l .s o'E .Sep t G.mb0:r 11 , 1987 and a po t(~n:.irnner:::.- ic ~;urface ,nap 1:-,1,:1..s )repar2.C. . The a~.t ;_tude uf alJ. wel:~s 'dilS re .fc.-r-1:~nce.'...'. tu known :1.ancl S'-!:::'.'£ac.E:.> ~t-'._t ·:tude bencti..:'.1ar.ks by u se o: a :·evel .c:1.:rvc;y inst:~·1_1.men.t . 'T he r;ot.Dntic.,:'.te'.:~: i c surfc,cc e :na~ wc,,s pr:epare.d Cy -c~1e :.._1. _•~. ,-::;,;Dlug:_c-:c • .L Si...,r,7;;. i;, coo;,H-,.".":ction wid:. r::.':1C> '_:.S. :'."£rn/i.1:"o~u1lental "?-c o-::.octio:1 :\gcrncy. Hra.c !~unsd volcanic rock s un.dcr .l..i. e Turpentine Run basin and ~,re. locally overlain by alJ.uvial deposits (Donnelly , 1959) . The alluv i a l dc!oo.<;:i_t'.:-_: c:;a.n range to 40 f ee t: in th·l.ckness. G.r::·ound wa 1.:.er in the Tu-~:.w n L:i. nc-; Rlln b2sj_n occurs i n the f r actured voleanic ·:..·ock and ctlluvial d1,:,pco.i.i..:.-; 'Jr;cf,~ w;i,ter - cab\e condit-Lorrs (Jordan , :973). T1:e alluvia] cle posi:.: .s exe cc)nsidered i_:_o br:,_ 'r.:;6r2.1_,:dca:l..ly corucc.Led with the f·cc-,.c.t: 1.ci-ec'. vo.'.- cc1r1:~r_' rock. ',,'ell dep'.:hs ~r. the basi.,·1 ,:: ,:,n .c:1n;:;e. t:rcr:1 )5 to 31..5 feP.~·--: ' ., ' ' oe_<,-,., _ _1_n);~: ~:e.v e:ral i..;ells · ',1ere. oeing _pumped, or pump ing h c:td j ust term:i.nalecl , when l1u-o ',; at.rc:-r leve ls ,,,ere :nea.surecl ( tablG l) . Thnsc. w2ter l evels reflect a pumping or recovery comht i on ; therefore, .stat ic water-level condi tions throughout. t [w Turpentinr:.! Run basin at the t i me of mei:i.surcment cannot. be 2• .. '3 :=; 1._1rne.d . i\c>Lt_:_,:in.-:1. ~ i n :"o-::-r.1~c'.:~_on a'.Jcut zr our:d -·,;ater levels i.n the area o:~ ·:: ~.udy L.:o ~:v,:;i :i.J..a b1 e fr cn: th:. U.~'.. c;H;-lcgic.011 Sur vr_oy, Wate r .Resou:?:."ce:;: C(:1·l~b~an D~.stric~ oif~ce in San : ua1!, lue1:1:o Rico, Tel. (809) SELECTED REFERENCES Donnc• lJ_y , T . W,, 1959, Geolog y of .St , Thomas and St . John , Virgin rs1a:1ds: Unpublis ~c d Ph.D. ~isse=tatio n , Princ~to~ University, L '.,' 9 'J , ~Hragh~y & Mil ~er, Inc ., 198], Repo=: on c~rrent g~ound water condl ~lc11s i:1 t~ic 'j. '.). 'i::..:-gin I.s~~ands: .?·:::-ep8.red for ~he . .zo,;c::-;n:nent of "':h0. lJ • . S. Vir2"i --l !..:;lands DspJ.:ct:ncnt o.\: Cor.sEirvation and Cul;.:ural Affairs, 30 l'· Jorcla.n., D.G. and Cosner, O.J ., 1973, A .survey of t he water resour ces of .St. Thoma::: , Virgin Isla.r,<l,;::: IJ , S . Gc~olog i ca J_ Survey open-f i le n,1;0 •:t , SS p. St eve,i:3, ~:. F., ::Xi1:1ez -- G6nE-~z, F., a:1d Alicea , J., 198:, \--t'a '.:.er we ll~: in tt.e 1_;.~. 'Iirgin Is :~ands, :1 1_:_, :, .St. Tl:ornas : U .. ':;. Cec-L_1g :'...ca l Survey C'V'-'::1-?'.!,p_ 1\r-'e:-io;.t 82. -82 . \Vell numb::1· Table 1. Descrlpi:ion of weJ/s and September 1 \, 1987 water-le vel m easurem ents in T11rpenfinP Pun hes in, St. Thom;;;; 1 U.S 'lit gin lsl~w cfs D)at um la mean sea leval, Ahb r&vl1:1.fions: hyrihen.,:,,, dHta not <1.¥a il.t1.bl0; (FIL), su!lpoc te d roc ovoring fgvol; (PL), susporJto-d pwmping toveQ Well i<lentif-ic & tio n 1111.m.ber \Vell D.D.m. -e Yetu drilled Depth of wen De_ptr,. o.f Corwtruction ~?later Jevel below !and 0urfv.c1J (foet) 1Nater level altitude (feet) Land surface v.1titude (foet) ----ir--------J. _________ I ·r-:-::, (' -,, ' -+---·-,--------~------+- ----L---- - - 01 DJ O'.:i 06 0' 08 09 J_ C, I. I 1 ') ' L 16 17 rn 19 ~c 26 27 '.! 8 29 JO 3 1 ::,6 ·1-, c , 38 39 lf Q ' I 1. 82 CJ 2l[)IJLi_'lJS800 I : 8 '.~O 2 6 D 0L}~ 3 ',", 8 OC .L 82. 0 2 SO (,Lf 5 J:18 00 J. 8 :!. '.) 13 1_; (;-'r J J j9 00 l S 201. 7 C 0/i._'.i '.'.-59 OD 182 0 l 606Lf535900 1820 1 G06lt51;Q000 1810 .l 506L~SL;Qf)00 1G2Cl+2.06i+S:11,\00 131iJ37 OU i:.:_iJ 1 __ 1_ 00 .',_ 8'.-'.03 8001;5 ~ 1200 18/.Ql.,/}(16/: 5 '.) ~ :'r f:0 J. S?.OL, 90Slr SJ [)900 18202906t','.j3 J :500 1 i3202 '7 OGI/) 3 l a 00 l8202.7064'.:",31900 l 8 2 02C 00:if, S 3'?_C GO l8 lOl9 00!;'JJl9C:) 18 ).Cl J. 61JG •1 SJ ·r:U O .J 182017 0611 5'.3 2Ll'D J H'20:!.l06115J2500 182018064532800 18'.W l 700l1-533t)OG 1320 l 80CLr 'i 33 J_ 00 182018 O6L1 5 332 00 132:J~9C5,~533JDO 182015064532700 18 20 J. 15 061;53 2. ~)0 0 182015064533000 182011,061.532900 182012061,"i31L,00 182009061,5:i 1. :lOll 182008 061}'.)3 l I: OJ 181911J06lr5253 D'..l 181940061+5 252 0 0 1s1938 □6 1-:.s2s:oo 18_.l.9..3 80_ 6!f52.SOOO . .1. 2 l qJ.7,Diih..S.21,g_QQ_ 181 )3.°JO6L,52!1L1OO 1819210 6!,511, 1 U D Mario Bry~m '.i<:.,.11 i!J. Ma::io .Br\To.n 'iel1 i/2 Vio.r .i.o :B:ryc1.E i,;E,J.1 i,' -1 Lockhart Well lll ~ockh..::!_·t: 1i/e11 //2 i - '-_) I () Loc.kharl; W,;-,J. 1. f/3 Lockhart Well if!{ Lockhart WeJ. J. ffS Dern.i. t.r y :;~·~J. . .1. VI~:Ll:t. \✓r:J.J /11 VIHA WG:11 H3 VIHA We~~l ji,~ Till"3tS i;-;e.11 Four Wi nds :Plaza wel l If l Four Winds Plaza well {.!2. Gc'7.ne. Eg]jn We:!.~- iil Gene Eg1in \✓e:l ',_ /.i:,: Ge.r..e 'r':;7 ·i:n -.~re,-_!_'._ '/-J E . S t ee l we.21 Osborn Harvey Crusher Well Bakery Wel l Creger Motors Wel l lfl C!.""e\;er l'~oto:c s 'viel:~ l/2 Creger Noto-rs WriJ :'.. ,l_/ 3 Creger Votors v:ell iJ L; · E's a A Corp Wsll lll E 1 s & A Corp Yell fl2 E's & A Corp Wel.1 U3 E I s & A 1~o "'.'."p \'/ell ffL1 Franco4s La PJ_ace L. Smi th ~latth:.as Far r.ingtorc wel::. Poly Ca,ib/Devcon ill Poly Carib/ Dcvcc.sn ll2 . . Po_ly _C.fl.s:i_b/Dt,1..Tm1 HJ · -·_ Pcl ,,. _ c~rri.bll)wsmL f½ ~ .. Publ ic '•'~!Lt/Didi wel l (Gov . of the Virgin Islands) Dept. of Ag:ricu ~- ture ilni!i:~: l She.itec 1.977 1977 1 ()7 ("; ~978 l ~SJ_ 1950 1 ~:; i 978 1078 1973 1960 1 s 1960 1 s !_:: _'j :sc ', 40 l DU 300 285 2/.S LL) !GD 210 325 55 '" , ' -,, -_.-_ 37 73 6S J. s 36 36 ..- .. _,._, Opr.'.n ho2-e Opc-:.n }1:) Le. :.Jpe.r he lE_, ()p 2n hoJ_1~. Open hole Open 'rwle Open ho.le Open hole i i- i 1 : J. O 09 08 05 06 08 8~ 56 (,O 17 39 21 13 09 ' ') .l • . 37 66 76 30 32 22 27 26 ", r. _C 20 18 19 16 28 1 r1 cc 10 ',, u 7.:J9 183 l. 8!~ l83 183 _1_5.L(RL) 175 1 ,,· .u L2L 239 153 156 7 "1'1 dL U2(.0~L) 86(RL) 99(RL) 108 108 103 108 109 116 l28 Hl8 '..07 l 09 83 80 80 30 ,~_...-, '? ~ (T:>.T_,: . 01 05 115 22C 2 lg 188 18'9 2 3J 231 23.J 239 ?.78 186 166 165 ~hL 1~9 ' J2 175 .. 138 l,'.+() llO L',5 1 ·~5 l J7 ]_1.r8 1/3 l:~6 1 ··, ( .c o us 1 ~ 1 l;Q c:o L,3 ' ' ]7 9 ··--· --·----·----L----------'----------·-------"-------'----'·----- 0 :i 4 8 MU.ES ~--·T_,1 __ 1,--.,~·rL.--J O 2 .-,~ fJ KILOMETERS 113"17'•---------------~--------- -----~----------------.L. _____ _, ?-flap of Si". Thomas sho)'ting tho study are(!. EXPLAN A TION POTENTIOMETnlC CONTOUR - Shows nt!Hvd~ of wi:i.tor ta b!-? In foet Dashod wh·are e.pproxlnrntely locaied . Queried (?) ·11il ern !ocvJion le uncertain. C,:intour inte rva l va.ri~ll!a. D1:1.ium is moo.n sN,. !e'ltil. WATER- LEVEL DATA CONTROL POfNT - Open number is tho woJI n•Jmber shown on tabt;;i 1. Numbor In pa rl:)nth':!U<JS is 1ho altiti,rje of wtder la v.&I in feet. 0ntum i1J moan sea !evol. •~~ ., • ,._,....,_ BASIN BOIJNOArlY ------------ ·--·--·---~·-·----~-------------------------------------·-------·--.. ----- ---- -·------------------------------------------------------------ --~ ·:· -__·-:_OG!Ct,L '3UHVEY . ,-. -,:!f'.~iOG'RGES Of'/!SION .·.·::.· .' ,, REFERENCE NO. 10 - Uncontrolled Hazardous Waste Site Ranking System A Users Manual (HW-10) Originally Published in the July 16, 1982, Federal Register United States Environmental Protection Agency 1984 TU f ,_i ( , L :/ t:) ::3 U TAIi.i 2 l'lllaMlLlff or caotoGlC NA.TDULI• Type of Kate rial Clay, c-,act Ull, ebale; ullfracturN Nt-rpbic ad lpeoua roca Silt, loeaa, •llty claya, •1lty loaaa, clay loaaa; leH pemuble 11-atoM, dolait••• aad uadato•; ■odentely pemuble till Pl• uad aad dltJ u•; aa•J loaaa; loaa, ...... _..ntelJ pemea~ 11-atoae, dolait••• •• aa•ato• <• 11:ant); _..ntalJ fnct■l'N 1...-. •• •t-rpld.c roca, ■- coane till Cnwl, ...... lllf.aUJ fncturN iaaeoua aad •t-rplaic rocka; pemaa~ bualt •• lawa; ant 11-ato• aad doloaite •Dart_. fna: Approataau la•• of !7dnulic Co•ucU'lity 0 l 2 l Dawia, S. I.• forodtLi.' hmuld!1!i:of .. tual Natartala la flw-'l'llrouall foroua IINla, I.J.N. at ed.• Ac c Preu, lew Torti, 1H9 freeN, I.~ •• J.~ Cllarr)', Croa .... ter, PNaclce-lall, lac.• .._ Tork, 1979 ·1 i,'. ! (" .. ·' J.. REFERENCE NO. 11 j ... I ,, ,) ,, ,, '! 1j t The Geological Society of America ... \ ... Memoir 98 CARIBBEAN GEOLOGICAL INVESTIGATIONS By H. H. !!._ca, &Ji"1r D,P4. Gnlot,, Pri..,_ u,,;.,nl!o Pri---. N• J,,-, Carl 0. Bowin Woods Hou O«GtllfTcplw lrutuutia, Woou Ho/.,, M~ Thomu W. Donnelly Dt/J4. C.°"'f,, Riu Utriwrni,, HOIUtott, Tuu John T. Whetten Dtpl. C.oloo ad OeMllllfTap/rJ, Utriwrsity of WuhillflM. Stllllu, WasluflOII E.R.Oxburgh DtfJI. Gtolo0 ad Mi111ralof1, Oxf,wd Utriwrsity, Oxf,wd, E.,,,14111i 1966 ' ., .. ,, ., .. ,. ~; '·' ·•. \ t, , .... .;. I ( ,-- - - 1--. 91 CAllllUN C[OlOCICAL INV£.SJICATIONS 1he final bue map, ha\·e good shore-line delillil. Abpping on S1. John Wills Jone on I : 20,000 cnfargcmcnu of the I : 40,000 U .5. Coas1 and Geodetic Sun·ey millp. Aerial photographs ol approxim:ucly I: 50,000 Kale were me- (ul for some uruc1ural imcrprc1a1ion1. Exposures along 1hc shore lines Hnged in quality lrom cxccllcnl 10 very poor. Those inland, ucept in recent roilld cull, were almos1 invariably my poo,. Th, bm °""W S1. Thom,o ,nd SI. John '" ""P clilfs, which arc in plues · . · traverse. More shehcrcd ahorc lines uc easily w.ill:.cd, but rod. . ·· · . ., ... :llllcre arc much poorer. l.abor:11ory inves1iga1ioa1 lllidu4eill 11ucly o( acvcral hundred thin 1ec1ions, X ray dillranion cxamin.tlion of rock umplea and miner.al acpara1cs, abo111 300 pu1i~I chemical anilllysc:1, and n11mcrou1 mineral de1crmina1ions b,- op1inl examina1ion of cru,hed aamplea. About a dozen feldspan were dc:1c:rmincd by measurcmcn1 of index of rcfru1ion of grains orien1e,I on 1hc universJI mge, according 10 1he mc1hod of Smi1h (1960). App1oxima1ely 100 addi1io11al pl.igioclue 1amplc1 were dc1ermined by mea111remen1s of indicts of refraction o( 11norien1ed grains. An cx1cnsive op&ical s111dy of the frldspars, completed ahcr 1his ma1111scrip1 ,11as first 111bmiucd, has been publil.hed ehe,vhcrc (Donnelly. 1965). Pyroxenes were determined by mcas- uremenl of"• illnd 2V, illCCording 10 die method of Hess (1919). SUMMARY OF STRATIGRAPHY OF ST. THOMAS AND ST.JOHN The rocl uniu of S1. Thomas and S1. John (fie. 2) can be divided into 1hree major groups: 1hc Waler Island Formation, which consis&s of kcr.a- 1ophyrcs an,l 1pili1es; the Virgin Island Croup, which consists of anJcsi1ic 1,yrodaslic rocls and scdimenu; and one or more diorhic plu1ons. Tiae Water bland Formilltion possibly is la1c Lower Cretaceous. The Virgin Island Group is probably Albiilln (although ,he Hans Lollik Formation could be Eocene), and the dioritcs arc early Tcr&iary. The olileH rocks in 1he Virgin hlands arc &he kcra1ophyrcs and spili1ca o( 1he Water bliiind formation. These volcanic rocks are prcdominanlly Ro,111 and Ro,v brcccia,, bill kcra1ophyric pyroclaslic rocb are widcsprc:ad. A (cw o( the fine-pained 1uflaceou1 bed• contain wcll-prcscned R.adiolaria o( undetermined age. No1cwor1hy in 1he Waler bland Fonnadon is the ab- acnce of lerrigcnous 1Cdimcn11. This ch:arac1crisdc, togc1hcr wilh their •p· parcn&ly igneous mineralogy, has led the wri1cr to the conclusion that 1hcy arc probably volcanic rocks which were ex&rudcd on a rclill1ivcly level ocean Roor, prior 10 1hc existence of a ircnch or island pla1form. In con1us1 10 1hc pos1ula1ed abyssal environment for 1he Wa1cr bland volcanic rocks, m011 of 1he overlying pyrocla11ic rocks of 1he Virgin Island Group ,~ere cxirudcd suhacrially. 801h 1hc volc,mic and scdimelllary aocks exhibi1 slump s1rue1ures. and some mcgab1cccias con1ain lime11one bloch up 10 100 feel long. The bulk of 1hc scdimcn1uy 10cks in 1he Vi1gin hlanJ I---..-_ ( . I I I l i I I I ....... - - - I - --, -r -, T. W. llONNt:lLV-ST. TIIOMAS ANII H. JOUN, 11. s. \ 1M1;1N hi M,11~ 9.-, G101_1p ar~ co.use 1Vackcs con~i~1i11i; almuu cn1i1dy of slii;h1lr ,n·;,thnl·d debris 1lcr11·ed from 1he .in~em1c p)·1ocl.1uic rmls. The .tcpo,iiion of 11 11 , group may ha\'c accompanied 1hc for111a1ion of 1he iui1i.il hl.lml plJllo, 111 ;md ln:nch. Q. ::> 0 er Cl CONGO (Ar C 0 0 z .Q 4 (()Ill ,01Hf ..J <f Ill I'-· z C!) en er ::::> > 0 w u <f t-w UNIPOl'1 0:: u t·1,uu :?. HANS LOLLIK FORMATION (•0.000 lerl • I •uatl(•ANO(Stl[ Bll[CCIA ••• •uff Upper ••• •••~r conlach 1101 utn I TUTU FORMATION (6000 l~rl •I Tl.lffAC[~US liWICtc.[ lncl-.,d11 neor 1t,e bau tht Cokl Poml Megabreccio ltlholac,l!s ,.,., tho ••P 11 1ho Congo Cay Limestone Member (200-300 feel): COARS[LY CR,su1,11<[ LIM(SJO,.[. Top •• fotmal•~n not "'-'°'•d 1n u S ,al..»n~, OUTER BRASS LIMES TONE I 200 - 600 lul I PAllflALLY $ILIC1f1[Q JUffACEous RAOIOL .,.,.,. Llll[SJON(. • ' LOUISENHOJ FORMATION (14,000 feel IW SI. Thomas! 4000 feel IE Sr Thomosl 7000 feel IW St Johnl I •uli1JC · •NoES1TE 111ccc1• en, YUH l6tl/C 6fACH ti CLCVEI Ntor ••• aou II '"" Cobes Poml Conglomerale lilhofacies ;;~ .. :~~Mu end Ct'"" ti WAl(II ISLAND fQIIMAJtON UNCONFORMITY WATER ISLAND FORMATION (15.000 leett) ll[IIAfOPHYII[ nows. FLOW lll[CC1•s ..... TUHS •1111 Sl'ILIT[ ,LOWS ond "''""' RAOIOL&lltJU • lfttr-,ded llp dillet •"d plu91 ol •Ek&lOPHYR(. FolJ!ng ah~,- Jep~,i1io11 of 1lac Viri;in hl.111d L1u11p ,e,ullnl 1.11 gd) !rom d11fe1en11al ,·en1cal 1U0\·e111c111 .11111 1'•oil11cnl ;l\'l"l.ll'c ,1;1,s ul IIJ' . '"" f 1s· oo· 1·1 ° , '·"'l: D rom 10_ • 1c a,sodatl"tl s11ill"-,lip faulu la,I\C laoriwu1.,l ull,u, of less than I 1111le'. A!1!1011gh co111;1cr 111e1Jmoiphic dkns ic,ultin!: from •he c~1placcmc111 of d1ur111c pl111om arc cx1cnsi\'c, 1hc ,vesiein I\\O ihuds of St 1 homas and 1he sou1hcrn 1hirJ of S1. John arc e,scnaially unmclJniurphoscd. I I -, ( t' .. •. !Jo CARIIIEAN Ct:OLOCICAL IN\'LSllCATIOl'IS WATER ISLAND FORMATION ClNU.AL ITATUl[NT The Water hb.nd form:ation o( pouiblc late Lower Cretaceous age tumills almou entirely of kcra1ophy1·c, 1pili1e, and r.adiolarian 11111. The CK· po~eJ 1hicl11cu o( this fonulioo is 15,000 feet. based on projection o{ the hii;heu and loheu ho,i~·· · . ;,',rc»e>nable conection for lenticularil)' 111ii;h1 lower the uue thicl , tlie cxpascd section 10 8000 or 10,000 feet. \\'J1cr hbuJ, in the harbol ef Charloa1e Amalie, S1. Thomas, h,u becu ~c:kucd ,u ,he t)IIC loc;ality because of the great variety o{ rock types there arul the grner;1l ocellcncc of exposures, although cxccllen, exposures crop 0111 u1emhd1· ;,lung 1hc sau1h ilaorcs of St. Thom,:u and S1. John. ··Kera1oph1rc", as useJ here, is an extrusive or hypabyssal inuusivc ,·ol- CJnic roe!.. comiuing prodiminantly of albite and quanz, with chlorite, micaceous 111ine1als, and iron oxides. Nearly all of the Virgin Islands kcrato- ph)rcl co111ai11 cumillcr.ablc hec quanz, commonly as conspicuous pheno- upu. Those hi1h 1111.a11z phenocrlus could be called ·•quaru lero110- 1,h1rc" bu1 m.rny aphanilic rocks here co1lled "l.enuophyrc" arc chcmicall)' iJcmical 10 1lu: ,o ulleJ ··quuu lcr.a1ophyrcs" and the simpleSl 1er111· is ptc· fc:rreJ for all 1hcsc rocks. A uriking feature o{ kcr:itophyres is 1he absence o( phcnocrym (or pscuJon1orphs) o( pyroxene, amphibolc, ;anti min. Kcrato- ph) ric Oows anJ crp1al 1ulls inc soclic, with a ,·cry low po1assi11111 co111c111. but wine apparemly viuic 1ulfs arc iligluly more po1auic. Kc1·atoph)1e in• Uu)h·e roch hnc a higher potassium conlcnt an I commonly co111ain ,ct• onJary monoclinic K (elc.lspar. "Spilite" is a grceni~h seemingly altered cxtrwivc or hypabyss.al imrnsi,·c 10~1.. comi)1i11i; o{ chloritc and albitc, with varialilc ,11no11n11 of cpidolc, prdmiie, anJ cal~i,c, Frc:1h phcnocrym of clinopyro~cnc a1e generally l'IC)Cnt; amphibolc anJ olivine were not seen in the Virgin Islands spilitcs. At11)'gdulc.-s arc al.11111Ja11t and commonly contain moll o( lhc calcium con- 1en1 o{ ,be rods u epidu1c, calcite, or prchnitc, wi1h quaru and chlo1i1c. The~ ,pili1e, con1ain about the ume amount o{ Na10 as 1hc a11gi1c ;uuJcsilcs o( the Loui,cnjoj Forma1ion, and abo111 O.!i per cclll 1110,·c 1han Virgin Islands diaba5C dikes. JncludeJ wilh 1he •1'ili1es hc:re is ~ pa11ially albi1izcd augi1e andcsitc which occurs near the top of the fornution. The name spilitc has been applied in 1hc pau 10 many diverse rock types. ,ome of 11,•hid1 may be low-grade regionally mc1amorpho"d a11Jcsi1c1 oi- basahs. 01hcr spili1cs appcu 10 ha,·e been unusually hydrous maf,.c i111r11• si\·c rocks, and many a1c dcu1crically altered bauhs or andesi1cs. lfowC\·cr, 1hc1e ii an imprenive body of evidence that many so-called spilitcs, notably crrtain 01Jovician, Devonian, and Cretaceous gcosynclinal spili1cs. have charac1eristia which can be beu explained by auuming an euemially mag- ma1ic origin fur 1hcsc rocks. h is 10 this laucr group o{ rocks 1hat the Water bland Foranation spilitcs belong . I ·--··-, -·- -, ·----, ( ---, Such spili1cs may be tho11i;h1 o( as 1U1ls 1d1id1 li.11·r fo1111nl I,) .. 111,1111., lion o( andcsi1es. Howe1•cr, this proccu is bclicvc:d to occur d111 ing a late stage in the soli1lilica1io11 of a hydrous mafic magma and is not call>t'il Lr la1cr met.a morphism. Givc:n a certain combination of ph) sic JI anil chc111iLil condition,, spili1iza1ion o{ m.11ic cx1rusivc rocks is i11evi1aLle. t lcme ,ti~ lerm, applied in an admiucJly rcmiclin: genetic (hence s11hjcc1i1 c:) scn,c:, i, a ll)dnl one .1111.I )ho11l1l lie rttaincJ. The author a,lmiu 111.11 low g1.1,li- mctamo1 phirn1 m.iy oblitcra1c 1he mi11r1 aloi;ic.al crircria 11c:rcs):11 y f,1r thc: rccoi;ni1ion o{ spili1i1.1tion. Che111ic1I analpis ol a l.11~c a111l c;11 dully sclcuc,I sui1e o( ,pccimcns might rcvc,al \,·l1c1l1cr or 1101 lhc llll'L111wrpl1i, ro,l.s in q11c)1iu11 haJ liccn urigi11o1lly spihti1nl. b111 ~11d1 ;111,11},i) might·""' fail to do so, ;i111I die lcrm should he applil'll 1,•i1h 1o11t 111 ,11d1101 1. )11i1n 1,.1 kA IOl'II\ l<lS l11/1t11lut1my Hlll1·111c11/. t.l'l.11011l1)1c 10111p1i,n .11111111 f,1111 hlilo, 111 1111 \\lain hl,11111 h11111,11io11. Mu~, li.c1.1111pl1y1c OUIII) a, llu\\'s o111,l llo1>· Inn, i.,,. with minor 1111h, bu1l1 np1.1lli11e ;11111 \'il1i~ (rhc ).111c1 .1h,·.1)> dni11 ihnl) .111,l. rarely, n1l1.111ic: ht nci;1). Kc1.11opl1p ii: inrru,h c I u, I., .,1 c 11111 1111111111111011. 1hcy 01l11r ;u ho1h lliln a111I ph1i;,. 101111110111)' wi1h l'c1y 1,·, II dntlop"I columnar joinrini;. Kc:ia1111'hy1il llm,·, ;1u; i;nll·1.,lly tell> u( kct i11 1hi,l11n, Io:\\ 1loi,l lluh, arc compktdy ci..1,osc:d hom top 10 b.1sc; those h·hid1 arc h·rll 1·,f'oSl·.I ail' srrikini; only 1111 1hcir 1<.:i..111r.1l uui(ormity. llal.ini; and d11ll111~ l'h,·110111..:11.1 a,e :1Lsc11t. no,v ba111lini;. 11,11.1lly )01111:ll'h;,1 co111011tol, i, seen l,11 .illy (l'I :1. f1i;. ·I). C:0111J1 IS bclh'tc:ll llow 1111i1> a1c co111111011l)· difliculr ro idc111ily ;i, such, ;11111 a11i111(ks o( 1hc llmv) a1e 1101 ,1hvo1ys c.1)ily .1>1c11.ii11nl. One 1hicl l1'f.1111pl1pc nulV nc:.11 rhc L;1sc o( 1he sn1io11, 011 IL1111 I k.,d. SI. Jol111, ,ho1,s i;ov<I fu:hl ;11111 pcarugraphic cvidcruc o( n·11ical dil(uc1111.1- 1io11. The flow is .iho11t J(i5 kc! thi,l, ancl ncJr 1hc ll'lllcr i, rl'oldi,h g1J), graclini; lo g1ct11i~h g1 ay ,lo1rn\Va11I a111I 11p11·;11il. l',:1111g1 .1pl1i, dilfuu1n·s IVill l,c lfocussccl I.lier. Tl1c I ulur cl1a11gc ol.,cn·c:J in 1hc hdd 1rn11ld appc.11 10 lie 1cl;11cil Ill ;1 1lilk1c:111i.1I ,lq;,n: o( olli,l;11ion or i111n \\lll1i11 lhc: """· h'l1id1 is prohJbly 1cb1c:cl In 1d.,1in: 11111ccntr.11iu11 of \ol.,riln i11 1hc: 11.,.,. cc:111cr lluring coolini;. Kera1oph)·re Oow b1c:u i.1S, 01 rnri i11g :1> 1lisuc1e hub, ;11 c p1ub.il,I)· 111u1t· t:ommon than Oows in 1he lcro11opl1)'IC ~CljllCnce L111 are 1lilfic11h IO Ji,- ti_n~uish_ f1om flows. The 111;111ix of rhc llow brc:cli,i, 1;111 lic:1ii1c11al) t,,. 1hs1~ng111shc:d fiom 1l11: lr;1g111tnb only L1· c;11d11I sc1111i11) of 1111: 011111up; 11,l. 11:111nJ o{ 1vca1hc1ing ,~hid, lO\'Crs 111m1 keratoph)tC> dkl'li\·d)' olis1111n the line dc1;1il~ 11e1cs,a1y 10 1c:cognizc: 1hcsc rocl.s. 1-'r.ag111c:1111 in lluh' L1cHi.1s a,c ,ubangnl.11 10 ~11b1011mlcd. The m;11rix is aht1o)l iilen1icJ! 10 rhc: (1;.ig. mcn11 in polishcJ seuion; however, 1hc matrix ,~c.11hcu 111111c ,a,,i,11)· .. 11111 in on1crop a Oo\V brcccia 1>·ill ;1pptar ro11gl1cr in i;1ms 1t·\1111c 1h;111 ;1 llrn,·. A (cw Ro\V breccia~ cun~i~l o( bu1h '-cnophpc ;iml spili1c lragmc111s. One ( •. . ~ '. . ' .,,.. __ ·- ·-- ,,.....,_, •- . I CAllllllEAN G£OLOCICAL INIIUTICATIONS 1uch occuncucc (sample GS J-2, near the wen end o( Greal St. James hland) h a IOO-loo1-1hick bed or kcratophyrc and apili1c rubble with a re"' lime- Hone (ugmcnu set in an apparcnaly igneous matrix. The minor rccry11alliza- tion of the liines1onc suggeus a low 1cmpera1urc of extrusion. No conglomer- a1es "'ere idcnailieJ within the Water bland Formation, ahhough m:iny ftow brecciu ha\·c rounded N -.1111 anaular fragmcms anJ, when \vcathcrr.11. rrsemble conglomeutcs. Qlfr~ (umplc ST-274, Lisenlund, S1. Thomas) \~ouM undoub&~ ... , a conglomerate I.Jy moll licltl K&:t>I· ogim, b111 umvc.11hcred apJ'di I.I 'laund a short dist:incc c:amv:anl along 1hc m ilc sho"' 1hc ig11co111 matrix very clearly. Tul(s an,1 rnlcanic breccias form minor but 1fo1inc1 units in the forma- t ion. Tuffs u.•uin ai,e leu &han 52 mm) arc much more common than breccias an.i occur :as LeJs only I or 2 feet in thickneu. None or ,he: 11111 1111iu cou•J Le dc:mom1rated lo have a hori1on1al extent greater than aho111 half a mi•e. Grading is visible in the tull beds, ahhough this grading is commpnly i111enup1eJ by 1li.u1em, representing the ae1ion of 1vo11er currents on the sea Louom. Slump structures. gcncrally in 1hc form of conior1c1I bedding. :uc uncommon. ~faoy 1111T I.Jcds arc silicificd, although &he original 11)·rocl.a11ic gioundmau is recognizable in 1hin scclioo. App:ncntly 1hc origin- ally vitric grounJmau of many 1ulfs has ahered 10 fine-gr.iined 111ic;1 minerals; mu5coxi1c h the mru1 widcsprcad, and ccladonite and stilpnomelanc ha,•e been recognized. One: ol cha: beu oposurcs of a Lcratophyre brccci:i h on the cau sho1c o( L1111eshur Bay, St. John (iample SJ-7). Herc a bed 1Cvcral 1cm of feet thick consim of angular (ragments of kcratophyrc a few mm lo S cm in a reddish, hematitic maUilC. (Pl. 4, fig. 4). The hema,hic matrix con1ram ,,·ith 1hc morc ncutral co•ou of most 01hcr keratophyrc Dows and 1ul1s in which hrmalitc is generally subordiHIC 10 magnc,itc. Dikcs .ind d1allo\V plutons or lcra1ophpc occur chroughom the lm111;1- 1ion, bm arc mou conspicuous in cl1c hills ,ou1hwc:u of Charlotte Amalie, St. Thomas (lbypiece Hill. Gramliolola Hill, Sara Hill, Cabri1abcrg), in 1hc vicinit)' o( Naiarctb Bay, St. Thomas, and in the vicinity of Hoffman and Mc. Zion, St. Tho1n:11. (Mt Zion itself, however, is un,lcrlain by ;11101hc-r l)pc or inumh·c 1ocl.) These bodies commonly cxhibi1 col11m11;11 joi111i11~ 1~111cndicu•ar 10 the cooling surface, and examination of che joinu pro• ,·ides a means of rcconuruc&ing the shape of &he iotrush·c L01I)·· Thc hilb around chc Submarine: Hase on s,. Thom:11 (Dbri1al.Jc1g, G1a111- Lokola, Ha)piecc, and Sara hills) arc underlain by one or 1'110 intrusi\'e boJics known collcc1ivcly as the Submarine Base Pluton. The accompanying map and sectiom (Fig. S) show th.it the form of the imrusivc body is irregular. The pauern of join11 around llaypiccc Hill urongly suggcsu the pn."SCncc of an inuw;i,c funnel bene,uh this hill. The joint p:111crn 1.Jcnc;11h cutc:111 Sara llill, on the: other hand, would appear 10 suggest that 1he Door or the in1rusi,e body is s111.Jhorizo11,al. inegular, and shallo,~ly dipping here.'. The incrush·c-cxrrusivc contact near a prob:iblc vco1 al the southern cnd of I - --, ~~am••olola llill is 1110Ja:1J1<:•y 5lt'cp. On CJl11i1,1111·1i; lldl 11 11: .......... 1.11 Jo11111 ;ire 11l·.11ly h111i10111JI or 5h.1llo1d1· J1ppi11i; 10h·,11d 11,c: ,011 111.-. 11 nul o( the in&rusi\'C ho,ly. hut a1c nc;11 I)' ve11ilal ..ipp1 oi.i111.11d) :;oo kc:, 11 .. 11 h o( the so11tl11:ro contact. An ou1crnp o( extru,i\C rm L, c, i,k11il) ou 11 11 111~ H r Oau.,. .. ,.,m (Zlo, .. , Hett L11•AI ,., u,11.-, ••~ u .................. , ...... ., ..,..,, ••• ,,,u.•1• IA, ,,., .............. ,..,.,, ··•·" IOOO IHI I" I ;,~"'- ,...,.-/'C:":\i•---... II ~---/ ;,~ - _L__; __ · __ -_-_-_~_-,_,~) .... L _ _J ~----------------------····- J1,u•1: ,. Al.ar illlll U0H 1c,1io11t ol'1lu.: Sut,m,u111c U.ut.· plu1011, ~, I lin11l.1\ kl I, I ... 1•1~1c I lor locuiun. juu unJ1:rnca1h &he i11Hllii1c budy, cJ11 bc )&:en a•1111g Ilic )111111.: j .. ,, su,uh of the Caribl.Jc~n lr?11I. lluc 1hc in&ru5ivc body wJs probJLly lul llirough a steep conJuu at 1u southern enil, and 1prc;11• no11hwar,• .,1 a 1oui;hl) conformable ahec:l. le i, 1101 known whc1hcr or 1101 1his i111r .. ,i, c lmd) connccu wilh the 01he1 0111: .it )hallo,v Jcp1h .. The occurrence of i111rmh-c kc1a1ophpe in mo,lc1Jtc:ly IJ1gc l1111lin 10 wud the top o( the section may 1clln1 a suL1lc upwaul change iu li1holog). , I! ,, ,·--- ,- 11-1 CAIUIIIIEAN CCOLOCl<.:Al INVLSTICATIONS 1urc optiu). and rare biotitic mic.i and a mafic miner.a~ whid, has al~crcd completely to a fine grained, very red 1ubua~cc. 11111 could. be. cuhcr iddingsiu:, l,o1,·lingi1e, or ,ome other cl.iy mmcral or combinauon ol mincrah. The glau lragments have 1lillusc oullines and conlil l,c ,hi_nb. In no case, ho,~c\cr, has the degree ol prci.crvation reve;ilec.J 1hc o~thncs ul 1he origin.al glau hag~-ll-:!""K< ol ''"" b,J, ;,. dn~• m- 1ion is \Cly simibr to the.,: · _ .... r11icd 1ullatcous bc:1'5 lo111~1l III u• plo,ive rh)olitic ,ui1e1,, bl~"-..··. ' ·~ ivc origin is 1101 est;il,lhhctl hy peuographic evidence. · IIIAl ICIAl'IIIC VAIIIA IIONS The Waln hl.u1tl 1-·01111,uion i1 1c111,uhLly 11nilo1111, co11,i11i11g tl11011gh- out ol abou1 one lihh ~pili1c and 1hc remainc.Jcr lcratophyrc. ·1 he lo,~cr 1•~•- tion of 1hc lo1111a1io11, ,cen lieu at lt..111 Head, St. John, aml on Gtcat SI. James hland, cousisu c.Jo111inantly ol •!•id, kcratophf_re llow, with i11te1·- calatcd spilitn. Drcccia1 and pyaocbmc rocb ate mmor a!1c.J lorm only \Cry thin unils "·i1h a limi1cd lateral extent. The 111~1icr poruon of 1he lo1• malion, ,ccn best in the vicinity ol Charlone Amahc, St. Thomas, and 0~1 \Va1er hland ilsell dillen principally in the grc:11cr pcri:cnaage ol pyr~l;isuc uniu. ,\ao1111d 1he inti ush·c bodies ol 11.aypiece llill. Gumoolola Hrll. aml C,1b1 i1;il,c1g, 1hc 101 m,uion i1 1fo111inan1ly pyroclastic, with only :a lcw thin lcaaioph)lic Oo1>s. On Flag llill, suatig1aphic~lly sl!gl~tly_ lower than 1_hcse p)rocbs1ic 1ocls. a strikingly thick pyroclamc urut 1s m1ercala1ed m a dominallll) Oo1v ~c11ur11cc. No mineralogical distinctions l,e1wccn the lower aiul upper pur liuus ul 1hc formation can be seen uccpl 1hat nc.ir. the l~I' of the formation time is one occurrence of oligoclase and :albnc wnh high-temperature optics, and tl1C1e arc three occurrences of alhite \t~•h optics ,~hich dc,·iate significantly horn the l01Hcmpc1ature state :and ,~htch have been called 11uasi low-1empe1 a111rc optics (Donnelly, 1963). CNVIRONM[NT The mo,t 1triling lcatu1e of the Water hi.ind formiti?n is the, co~plcte al»cnce ol 1erricenous sediment: the entire exposed 1h1clneu co1H_1us ol volnnic rocls only slightly reworked locally by waler. The second 1mro•·· tant (c:aaure of this unit is that mou of the volcanic roch, except for the uppcrmou S per cent of the formation, arc Oow1. The py1oclas1ic 1ocLs 1hcmseh-cs consiu entirely o( relatively equ:anl, angular fragments, amt shards or pumiceous fragmcn11 are not seen. The <Jliicsccnt eruption of appaienily h)<lra1ed magmas must indicate 1hat these 111.1cm:as we•~ erup1td under a confining pressure ol superincumbrnl sea water :tpprma- ma1dy C:•(l•hak111 10 1hat ol the dcep-sc:a bouom. which is mfficient to pie- vent the e"-plosh·c expamion ol a magmatic gas phase. llydra1c1I 11ug111;1s crup1td in this endronment will experience scpar,11ion ol volatiles if tl_1e I I I I I T. W. l>ONNlllY-ST. TIIOMAS AND sr. JOIIN, II. S \"111.r.lN l~I ANDS 115 partial pressure of these volatiles exceeds that ol the sea wain (about 500 aim al IS,000 feet). The expansion ol these vola1ilrs, howl'\lc:r. will Le in ihc order of a few times, not many thouun<I times, as woulcl lie 1hc enc ii lhl· magmas were erup1td subacrially or in shallow \\'alc:r. Abps:,I p)1ocbs1i1 rocks will 1101 be formed by explosion but by reb1h·cly 1p1il'I l')q1.111si1111 ol volatiles and sn<lilcn d1illi11g by sea w:1ter. Dispcis.,I ol pywd.,st i, 11 ·•!-:IIU:llh will probably he eRccteil by ,low-moving l,0110111 c1m cnts. 01 con, e< 1 i, t.: currents initi:ated by the rcle:,se ol heat into the sea w:1lt'r. The :11,scncc ol lc:rrigcnous sc1limcn1ary rocks i111li1ates that 1hnc were no c1m·1i:1·111 i,l:nuh 1vhid1 coultl h,n·c ,crvnl as tl,c souuc ol h'1·.11hnc,l <lt"t1i111s. Slump 1t111c1Urcs or 01hn evhknces of 1lcposi1io11 011 ~lopes arc p1n1·111 hu1 an· nol ali1111da111; in co1111au, near the top o( the lor111a1io11 1hc1c arc scn-1.il 11aiki11g occ111iencl'S of el'Cnly la,-ere<I ppocbs1ic lcraroph)ll' 1>·i1h no Lnl ding 1li)llllhanccs. Ed1lenil)' 1hi. formation an1111111b1nl 11111 uni)· in ;1L)\ sat depths b111 also on 1a1hrr flat sca l,0110111. The app,·:1ra11«: ol sligh1I) more uplosh·c ct 11p1ives mil)· al the ,·cry top of 1he 1-'01 ma lion shows 1ha1 1hc sea bottom mo1y ha,c been u1lai1li11g tl11rini; the g1tater I'·" 1 of 1hc ,1c~ c11m11l.a1io11 h111 1ha1 subsi1knce was 1101 rapid enoui;h to 111;,i111.,i11 a con- J . st.Int ,uaer lc1·cl at the erupth·c 1t11lcr ol the acc1111111la1cil 11,l1.111ic tlq,osi1 _. Ahern:atin:lr, regional uplift near 1he ciul of Wa1c1 lsl:11111 time co11l1I h,1H hccn rcspomihle for 1hc :ippatl'llt )hallo1d11g ol 1,·:11u VIRGIN ISLAND GROUP I OlllSI NIIO J I 111! •I.\ 11111' frilroi/111 IUI r J/11/1·111r111. lJ111011101111:il,I)· m 1·111 i11~ 1 hr \ I .,1n hl.11111 formation and cropping 0111 on about hall the IJ111l :111·;1 of Sr. ·1 ho111:1s and S1. John is the i.olli51'11hoj (l.oo c' lilll l1oi) fo11na1io11, 11.11111·<1 101 cx,clle111 uposu1cs in ro:111 cuts in 1he ,·ii i11i1y of l.011isc11hoj. j11,1 1101 rli of ( :t,.11 lolll' Amalie, Sa. Thom.as. ll"!ii~ •!~c~~jl•c;111c is prcilo111i11a111I,- ;111,:i1c :1111lnill' ;iml varic~ ~n ~011~ __ 0!_ ~~~~1i~~1 hum l')'°cli•~•ic 111 cpi, l.1,1i1. The 111:1,..i- 11111111 :11'pa1c111 thiclm·)s ll,l\·ei.1·,I is ah11111 13,000 kct, lm1 :1 1c:1mruhlc correction lor lc111i111l:1ri1y 111i;;h1 1nl111t· this co111p111l·tl 1l1icl11n\ Ii) ;1 1hi1d or· more. C.k1c (IHil) ullc1I 1his 111cl l)"pc "lll11e llt.:.1ch" :1111111,i, 11:11111: h.,, pcuiue,I: ;111 of the: 11;11h·n 111 tin· \'i11:i11 hb~~-;:~. i.,11,ili.11 11 itlo "111111 Hitch" or "IU11e lli1." The form:11ion is 1hicle)I ;11111 al111os1 e111iacly I')"" l.1,1i1. (101-1111 1l'11111lcd tufl bc1ls :arc comitlc1ed essentially pyrod:nlic) in ,~rsre, 11 St Thomas. 111 e;111crn Sc. ·1 homa, ahc 1111111.,1 i1111 i, 11111, h ahi1111n ( 1111111 ln-1) .11111 i, , 11111 posed almosi cn1i1dy of 10.11,e ,l11111pl'II anti 1t·w111lnl 1')1111 l.1\1i, .ld11i,. probal,ly oai1:i11a1i11;.; hom a ,111.111 )IIL.u·iial c1111c. 111 h',·,11·111 '>1 fnl111 1hc form.ition is 1hickcr (71100 fn-1 111i11i11111111) a111I 11111,i,h p1,,J,.,11i11.,11ily 111 ro,1ue <:11111: 1ld11i,. l'ig1111· Ii ,hows ;,11 i111c11'1cra1io11 ul ah,· llllldi1i111h 1d1i, I, irmhccl in 1his 1lis11ib111io11 of 1ml 1ypcs :11111 1hi1 t11"~~1·, E, id,·111c f.,, """ t ( 116 ,-· t I ,-- - CAlllPU[AN GEOI.OCICAL IN\l[SllGATIONS Q.w ~z ::> 0 ..J 0 (/) ~ wo (/) a: 0: lL ct Oen u a: I ~~ i 21 : ji - a. 0 0 (/) ~ ~ .... ~ .. ~ I I 0. w 0 u i= en l :3 i u • O t 0: ,. p )-- C 5 Q. 0 .!E j t ; .. • Q o E • ? .. l! t~ i I .:: .. I w z -1/) ~t: ~ 1/) mf =>w (/) 0 lL 0. 0~ w=> z..J 0 l/) )_ z 0 .... <I ::!: 0: 0 lL 0 z <I ..J (/) ).. ~ ).. ~ ~ (:) L.-...L...--'----~--~ .., 5 .. ::, -0 C: i -. Ji E !! i 1 " - - - - - - ---. -, T. W. DONNELI.Y-ST. TIIOMAS ANO Sf. JOIIN, ll. S. \'Ill.GIN ISi Al'WS 117 pos1ula1eJ Pillsbury Sound erup1ivc center is based 011 1hc warscnrh ol volcanic ejecta in nearby western St. John anti e:utc111 St. Tho111:is, on 1111: presence in Pillsbury S01111tl of a diori1ic plu1011, and on 1hr 1mc,si1) ol finding the 11c:1tcst 1caso11able so111cc Cor the lithic ha111en1s in the Lo11i\cn· hoj Fo1111;11io11 of western St. Thomas. In wcs1c111 S1. Thonus (15 miles 110111 1hc prc111ninl ct upli\'e c.c111c1) occ.asional angula1 hlorls 6 iudu:s i11 di.1111- CICI" ;uc found in lhc ;uh be1h, ,,hid1 1ht·1nsd\'n IJllf;C holll f111t· 1111! 111 hagmcnts alJOul I inch long. The coanc cone Jdnis is 111mt s11ili11g in ,,t·s1c111 S1 John .111,I l',,.1u11 S1. Thomas. In ,.-n1t·111 S1. John ·lfoo1 blocks ol ,~ha1 11111,1 11,i\ c Ln·11 rnbac1ially dq,ositell ash fwm the ,lopes of 1he conc.:s a1c fo1111d mi,.cJ in coauc conglo111c.:ra1ic bctk Nea1 l\l;m1.bl in ca,1c111 St. Tho111;1s l.11gc hJg· menu o( what may ha\·e Leen a rnl,acri;il amlni1e llow ;uc )cc11 i11 brnd.1) o( dchris ern,lctl hum 1ht cone. ,\1 0111: lot ali1y h Jg111cn1~ ol lluw up 10 2 (eel long rest in a 11u11 ix of lilll'I 111.11c1 ial. 1\1:iny of I hne Ii .1g111t·11u L1 ol.e 1 ap:1rt just 111io1 to c1.·ss;i1iu11 u( trampo11, anti 1ht:ir IJ1olt·11 0111li11cs CJII Le ma1chrtl in 0111uop. This is the nnl) p1oli.1Llc.: lluw 111.11e1i.il idn11ific1I in 1hi1.fo1ma1io11. At the type locality 1hc lo1111;11io11 consists Jo111i11.1111I) of bc,h o( lll,t\\e antlrsi1ic 1111T ,.-hid,. m.c 1110)1 of 1hc 1111( sr-e11. "·;rs ·'l'l'·'":1111) w.11e1 bit! The ~tis arc t)Pically G-12 feel 1hid. aml h;l\e l.1i1 g1.uli11i; 1,·i1h du: w.11,n1 111a1crial (rarely coarser than aho11t ~ i111 hrs; ;1 kw hl111 '-s 10 I fool) 11t·.11 11,c b,uc. Thrsc beds commonly show l.1111i11;1r sl11111pi11i; (Fig~. 7, H) ·1 he 11111,1 'I riling (e;11111c o( this slumping is the ;1li11111l.1111 c.: ul "pull ·'I'·" 1,· ;111,I the hcqucnt i111e1111p1io11s ;11111 1i:1t·1uls of 1111: g1;1di11!; ·11,i, l.1111111.11 dumping i, a nay tharacleriuic lc;11111t· o( 1hc l.011i,.-11hoj Frn111.11io11 ;111,I apparently lo1111cJ as follo1vs: an ;i,h IJII 1~;1s dqmsi11·1I 11111k11,Jl1·1 (l·ig 7,\) on a slope an,1 tlc,·clopeJ fair grading, i111r1111plt'd 01 c:1\io11:1ll1 h) a l.11 ge angular Llock ,vhich J1·111cssetl the linliliug Lclo1v it. ·1 he linl· ;"h 011 1op became col1csi1·c more r.ipiJly 1lu11 di,J 1l1c coa, sn a)li bduh·. ·1 he le,, cohesive, coa1scr material below slumped (Fig. 711), carrying on i1 and ell• ,·eloping within it lragmenu o( 1hc more , ohcshc, f111e1 gr ai11t·1I ina1r1 i.11 abo\·c. The flow was rarely rapitl enough 10 become 1uil,uk111; 1hc p11lle.l- apart bet.ls ha\'c ne;uly all 1c1;1i11ctl :111 01icn1:itio11 p;ualld to the Lc1ltli11g. During this proct"ss ol slump 1hc g1a1ling lost i1s origi11:il ;11ra11gemc111, ;11111 the coarsest ma1c1ial is co111111011ly loullll sonu:what a!Jmc 1hc b;1\e o( 1hc unit. Addi1ional c1·hlcncc lo, <le1io\ilion 011 a slope is th<' 11,·;11 I) 11l,i,1'1i1nm slump slruc1ure) sccu in li11c-i;1.ii11c,I 1111fs in 1hc fo1111:11io11. Purdy pyroclastic he1b a1c not ah~a)S easily 1listi11gui,hnl !tom 111lf hnh h·hich J1ave slumped anti hom be1ls "·hich have Ileen more or leH 11·1,·oill'fl by w;uer currcnrs. Coa1scr py,ocbstic rods mu:illy nhihi1 1he lt.1i;me111 angularity, the 1111iformi1)· o( li1hologin, aml 1hc .ipp;11r111l1· ig11rn11s matrix which one associa1cs 1vi1h a~h 1lcposiu, whereas li11rr ash 1,nls re• 1tmblc volcanic ,vacle. The ovrr-all a\pcct ol this lormalion mggcsls ac, iJI 11,uuport and subaqueous tlrposi1io11 of I'> roclas1ic ,kb, is. Tr Jll\f'OII J· -- 'I r- - 120 CARlllll£AN C[OI.OCICAL INVESTICATIONS Cabr1 l'oi111 Co11glomnale l11l1ofacin Ntar the base of the formation in the ,ici11i1y of C111z Bay, St. John, anJ C1brs Point, Pearson Gardens, a11J Bunker llill, S1. Thomas, conglomcraics arc i111crbcJJcd with anJesi- 1ic p)roclauic anJ epidat1ic 1ocks. Thtsc conglomcratcs consist almost rnti1dy of wrll 1011111Jrtl kcra1ophyrc cohblts anti pc:bblcs dcrivcJ from 1hr 1111Jtd)i11g \\'a1cr hlanJ formation. At Cnu Hay, ho,vC\·cr, these conglom- tra1es arc more or lcu mixQI, •illt lffldesi1ic deb, is, suggrsting that sub- aciial erosion of the cone ~ -a lhal of the umlerlying ktr:uoph)·•e beds "·ere simultaneous. Al bia l'obu the conglomerate is composed of "di-rounded anJ fai,ly well-sorted lcratophyic and spilitc f'Obbles :111cl pd,blcs. Thnc conglonm:uc beds appc.ar to have been deposited in shallow ,~a1t·r, and ,,·ere nol pro,lucu of 111bidi1y-c11rrmt Jeposition. They a,c well soucJ, ate 1101 gradcJ, and have rela1ivcly liulc matrix. Their presence i11Jica1cs subacrial erosion, transpo, t, am) deposition of older rot ls Ju, ing tarly Louiirnhoj time. W<1lrr /Jla11d-l ouiscnhoj co11lacl. There arc few places "·here 1he tont~ll br1 h'ct·n the \\'atcr hl;mJ and I .011i~c11hoj Formations is well exposed. In S1. John there is one excellent cxpornrc of the contact along the west shore o( l\lontc n.,y. anJ thctc ate poor exposures at Klein Hay. The upornic 011 Mo111c lfay shows a conglomerate of the Louiscnhoj o,·crl)ing a spiliic bed. The spiliic is quite fresh at 1hc con1ac1, and 1he 01·cr- l) ing congh,mcralc cont.aim a wide anor1111tn1 ol Water bland lithologiu induding, howc, er, , cry few rocks idcn1ilialilc wilh Ilic underlying spili1t. Al Cahary DJy, St. John, 1hcte is an cxpos111c or a wnglomrratc or 1he Louisrnhoj form,11ion 01·ctlyi11i; kcratophyrc. On St. Thomas the ron1ae1 itself is pootly exposed, but an cx1cnsh·c ex- posure: of Louiscnhoj beds above the contact at 1hc headlands bctwtcn Brewer's Bay and the airpor1 is of gi-cat interest because of the extent of appa_renlly contemporaneous wca1hering displayed here. The Louisenhoj beds here consist dominantly of subacrially, varicolored andcsitic ash inter• bedded wi1h conglomeratic Water Island detritus. Some of she ash uniu arc brick red and consiu solely of albi1c, hcma1i1c, and a )iule illi1c (X-ray dillrac1ion). The albititcd plagiocbse phcnOCT)SIS evidently withstood the 1vca1hering ;ilmost pcrrec1ly, b111 1hc entire malic parl o( the roe~ has bren com·crtcd to oxide. O1htr uniu consist of 1'3ricolorccl fragments ranging hon1 tlccp red 10 grt·cn, c,·itlcntly rcHcc1ing ,liflcrcntial susceptibility to weather• ing. Still 01hcr uni1s comiu of greenish or gi-a)"ish hag111c111s in a uniformly pu1 plish matrix. The bJsal subJcrially wcalhtrcd unit is less th:m 100 feet thick and was found al only this one locality. The color o( the beds somewhat rcscmlilcs that of the wea1hcrcd hydrothermally altered rocks (1liscusscd in a folto,dng section), b111 the la11er gratlc into whi1ish unwcathcrctl· roclt within a fo,v rrct o( the su1 face and arc miner a logically quite distinct. The cx1c:111 of ,his h·ca1hcting is complc1cly unlike any rcc1·111 wea1hering o( any rocl.. t)llCS in 1hcsc u!Jmh amt 11111lo11l11rdly rcnn1s wr;11hcring con1cmpo1a- ncous "·i1h original Jrposiiion. I T, W. DONNELLY-ST. lllOMAS ANIJ SL JOIIN, IJ. S. 1 IRI.IN 1\l ,\'\ll\ l'.!I Anolher ocn11rc11cc of con1C111po1 .11ico11, \\"CJlh<'t ini:; i1 I"'"' Ii t·,111»nl .11 Wintbcrg Hill, St. Thomas. ·1 he poor na1111al npo,111 n. 11 Iii, h .11 c of ligluly mcta11101phosc<I rod, \\·c:1e 01igi11ally 1ho11i;l11 111 1,c ol ll)il101hn mally aht1e,I rod,. llowcvcr, 1c1r111 (1963) ,,_c.,,;11i1111, 1111 111.,d rn11,11111 ,i,,11 rcvc;1lcJ 1hc originally wca1herc1I 11.1111rt of 1hcH· '"' l, Mineralogy o/ 111afrc /rng111e11IJ. ·1 he p1incipal 111i11l'l.il, 1111111d i11 111.,111 fragments arc plagiocl;ise, clinop) 1 ou·nc. c 11101 i1c, ;11111 fH1111pdl) i11·. ;11111 .d,11 matrix and opaque minerals. HANS LOLLIK F,., 0 0 0 OUTER BRASS LS. 0 0 • 0 0 0 • I Manr 0 LOUISENHOJ FM Q Samples ,., 'eo Spililized Augite Andesile --0 I Many WATER Samples ISL ANO FM. An O An20 An 40 An60 Q LT and OLT !Donnelly, 19G31 optics e HT optics 0 Q_Q_ t·1cua1 10. Co111po,ition1 of pl;agioclJk.·1 a11:1ngtd ~c,ouli111; to sr1.11i~1.1phi, p0Ji1i1111 PLACtocusi:: Most phenocryst~ or 1hc Louiscnhoj andesi1cs arc lab1 adoa i1c:. about An,e (Fig. 10). Near the base of the form:11ion 111;111)' ppod.111ic 1odr.s contain :a dis1inctly more calcic pbgioclase (Ann 10 abo111 ,\n.J Sm11r of these pyrocl:a11ic rocks con1ain both by10,vni1ic anJ labradoritic fragmrnis, but a few contain only by1owni1ic (or anouhitic) fragmcn1s. ·1 he fd,hpars ate sharply euhedral and slightly zoned. They sho,v ab1111ilant simple 11d1111ing and some albitc 1winni11g. Grourulmau plagioclascs and pl.1i:;iodasi:s in 1hc 01:itrix of coarse pyrocbuic rods a1c ,·cry linegrainc,I a11d cloudy. JI.I.my :arc diuinctly more soilic 1h.111 1hc phrnonysts amt range in , ;11, i11111 ronll'III down lo An20 • In many la pi Iii 111lfs, 1he only fehlspar fo1111d is all,i1c (An1); ···U r-- ,-- ( 170 C..ARIIIUlAN CLOI.OCICAL INVl.fllCATICINS compmiiiuu of 1hc more silicco1u Jilk1e11tiatcs. The experiments of Yoder .ind Tilky (l!lti:!) show clcJily tl1Jt at water prcmncs greater than abo_11t 1000 LJrs, 111.11erial of basahic composition should h~ converted 10 a 1111x· 1urc of hu111Llcmlc ;111J pl,,giocl:ue at s11Lli«j11hlus 1c:~1pcra1111es. ~s the: tcmpcra1ure rises the material ,,,ill begin 10 melt, w11h _the plag~oclase liting com11111cJ fotK The firu liqui,h produccJ will he l11ghly fc:111c_ :uul silicco11s. ·1 he rnmpodliQl\al IJ!ftd of li11uiJs produce~ at ,ucccmvcly higher 1cmpn,11111cs has .- btqi capcrimcnially dc:1ern1111ccl. hut ~ com• p.1,ison ,,iih ,he .analogoul ~re in .anhydrous caKs ~cn_crallon of h.iuh) suggnu 1h.11 horn~c will t:aLc the pl;1cc of ,hopuJc :is the do111inJn1 mJlic pha~c hcing coruumcd during 1hc grc:11er yart o_f th~ mch· ing. ·1 lac h)thous liquid might, therefore, be more enriched m S1 thJn "ouhl co111p.11 JLlc li11'1i1h roexh1ing with diopsidc in the anhplro'.•~ c.uc. ·1 he cx1c111 10 1d1id1 residual lto111blc:ndc might conuol the compouuon of 11,c: Ji,1uids hill nut he easily cval11.11cd until these hornblem_lcs can he , olkued anJ analy,cJ. but this co11sidc:ra1ion migh1 prove 10 be p1vo1al. Tire quanliry of l.eu1ophyric magmas generate~ is pcrh_aps •~e o,~ly u:ally scriom 0Ljcc1io11 10 the: hypothesis of gcncr:111on of tlus cnure suite from the uppcr m:m1lc. The q11.1111ity of siliceous rocLt is ~nlr.now~, b~t geologic.al inference (cxpo~cil a1ca of Waler _Island For~auo~, wluch_ IS aLout 80 per cent lrra1ophyrc) comhincd wuh geophysical mfor~allo~ (seismic rd1ae1ion Jnd grJ\'ity) suggcsr that 1hc \\'arc~ hland Formall~n IS a p• ism aLu111 5 lm thick. cxt1:n1ling perhaps iO Lm in _an cau-wcst dncc• 1i1111, h111 1111i1c possiLly thinning 10 the call, an,I ex1cnd111g perhaps 20 lm in a no11h s11111h Jirrllion. Thii. \"olumc-1000 cu Lm, or 5200 cu lm o( l.uJ1oph)1e -i\ p1uh.1hly a m.1xi11111m, because pos)iLlc thinning to the •·JH an,1 10 11,e so111h was ignored in the calculation. H fusion o( 10 per cc111 ul tloc uppc:r 111J111lc migh1 yidd a Lera1oph)·ric liquid, 1hcn ~2.000 u, ~111 ul 111,pcr manllc "·uc fused during 1his igneous cpis0tle. If 1hr deprh ol lu~ion \\JS 10 l111 and 1hc cast wc>I hu1i10n1.,I extent or fusion 40 lm, ,la. 11 1he )1Qri,11n1JI dimension of the rusc1I zone in a no11h south direction mmt ha\e IKcn 80 lm. These lig111es may be oil by an onlcr of rn:igni11ulc or 11101 e. b111 1hey t·mpha~i,c one prohlcrn: 1hc generation here of siliceous 111agm.a faom 1he upper m:mllc may require the partial lus!on o~ more ma• 1crial th.an can tliree1ly underlie the ,·cnl, unless 1hr fosion cx1cmlc1I to greal dcprh. The explanation for this see.ming para1lox is :is lollo\\·s: ~ming ,he orogrnic process compression and thickening of h)dratcJ Carihbcan auu anti upper marulc c.arried this ma1criJI into rhc o~ogen _hom .:i co~- i.itlcrJLle diuantc pcrpcn,licular 10 the axis or clcprcsston. 1 he orogcmc IIIJgmatic process ahrn can he comparcJ 10 a mill 10 which is fed frcsh, hy· t1,a1c,I uppa 111.1n1lc, J11tl from 1vhich nvo pro1l11ns, m~gma ;111,I m;1fic IC· ,iduum, :iu: 1t1110H:1I, 1hr first th1011,;h ;1scc11r arul eruption anti the second 1t,1oui:h g1;11l11JI dii.pl.1ce111c:111 ,lo•~nwanl ;1111I ~1·1:n111:1lly la11:rally: The ., 1111111111 11f Lt-, Jlophi1 e c1 up1c,I 111ii;h1 h,1\ e 1t·111111t·1I brer;1I shot 1c11111g of .,I,0111 110 l.111 in this ;,re;i. The 1p1;111tity of siliceous igneou~ rodr. seen h1:1c i, f,.r in eueu of any 1ha1 hJs hccn recorded in similar orogcnic ,ones, and I I ' . -. ·-, T. w. ()ONNll u·-st. lllOJ\.IAS AND SI. JOIIN, II. s. VlkCIN hi.ANUS 171 lhc Virgi11 hlanch may be an cx11e111e example ol a p10,css ,d,ich h:,s 0l curred 10 a lc~scr cx1cn1 in m.my places al many rimes. Cleaily our knowl• edge of tl,c co111posi1io11 ol uppn manllc is 100 li111i1nl :11 tl,is 1i111c 10 assns this prohlcm further. The wrirer (Donnelly, 1964) also pointed 0111 1h.11 1hr gene1a1io11 of a second, sueng1hkss phase (aqueous, or h)d1a1cd silirare mdt) tl11rini; orogenic thickening would h.i,c profound srrucwral implicJliom 1 he ,·olumc in IVhich this phase 1v;1s grncrarcd would hc:comc cs~c111i:1II) 11rc11g1hlcu, and ahc su11c111ral process woulcl be cxpc11c1I 10 cl1Jnge f11J111 a rda1ivcly mihl 1hid,.cning to a 111orc viok111 111ovcme11r ;tloni; an t·x1,·11- sivc shear. The comc:1p1enccs of 1ltis 111ovcnu:n1 wo11l<I Le 1hJr 1hr isbnd platform ,,·0111,1 be raised IO an cmcri;nu Ind. and pmsiLI)' an adjuinini; oce;inic l1cncla ,,·011111 be loamed. The clf<"CI on the i;cnc1alion of is11eo11s melts would be 1ha1 1hr raae of dcprcHion of m;1111lc ma1crial (;1ml 11,c rate of heating) shonld be incrcJsnl g1caaly. After 1ltis profound s1ruc1ural episode, the gcneracion of magma will he rclacivcly rapid. and rite propo1- 1ion of malic to fclsic magm.a high. The rcsuic1ion o( abundant siliceous magmas 10 tl,c early u.igc·s of orogl·nic evolution is tomis1e111 witl, 1l,i, idea. In conclusion, the following poinu stem well es1ahfoltcd: (I) T,,·o r,-pcs of chemically 11nifo1 m m;,grnas wnc gcnerale,I 1laro11gho11r 11,e sp.111 ol geologic hh101 y of thrse islands. (2) Thc1e has hcen i111cra11 ion ol n11p1nl magmas 1virh the environment in the c,se ol alkali excha11gc in cxumi\t kcr:11ophyrcs. Ocher possihlc cxch;ongcs havc 1101 brcn cs1-,hli,hul, n1 q,1 th.at a few samples o( highly metamorphosed kcraloph)rcs h:l\c bten i111· povcrhhcd in alb lies. (3) The sili(co11s 111.,g111:1s I q11 nctll 11.:111 Jt) 1 (! ·\ I, ( >,) mclu clcrh-c1I by partial fusion in a dominJntly 50<lic t·11vi11111111r111, and 1110,1 probahly, in an cnl'ironmenl with co11si,lcrablc cJlci11111. ·1 lac l.11c1 bd,.1, ior o( this presumed calcium remains one of 1he i111por1:1111 a110111;1lits Thi, parent material, for dil"crsc reasons i11d11di11g geopl,) sir .1I a11d cl1e111ic:il t·, i dcnce, is conshlcrcd 10 he upper mantle. (·I) The 111Jfic 111;1gm:1s arc chn11i cally similar lo so cJtlc,I high·alumina hasahs typir.11 of orogrnic 1t·giom gencully. The laigh magnesium of 1hr spilircs results from its grnera1ion ' lrom a material largely deple1ed in iron hy ah11racrion of Lera1oph)rC (S) The increase in .aluminum wirh 1imc anJ 1hr higher 1w1111.,1i\C Ah/Q ratio of ~he later 1111a1 u-andesine porphyrics of the scco111I group m.,y imlicalc generation at increasing depth wirh time. (6) Crystal sc11li11g .and assimila- tion or wall rock were probahly of li11lc importance i11 11,t· grnc1.11iu11 01 dilfcrtn1ia1ion of this 111i1e. SUMMARY OF GEOLOGIC AND TECTONIC IIISTOR\' OF TIIE NORTHERN VIRGIN ISi.ANDS The 1ccio11ic C\'11l111i1111 of 1hc 1111,·110 Hi111-Vi1g111 hl.111.I, .11c, 11,1> .ii 1c.1dy hccn discussed hy 1hr wri1c1 (Donnelly, l!161). -, he fol101vi11g acro11111 s11111111ari,i11g the geologit: hh101 y of 1hc 11011he111 Virgin hbnd, el11rid.11cs ( ,--~' ,_, C.\Rlbb[AN ClOI OCICI\L INVtSI IGA I IONS tl1nc iJc.h li111 i1111mlucc:s 110 nc1,r ,oncepu. The 111;1jo1 eau-wcst fault illJu,eJ IJ11;d) hum sr;avi1y e,i,lcmc w;1) 1101 1noi;11i,c1I al 1hc 1ime 1lu1 plpc:r was pu:p~rc,I; ho1,rc1·er. i1s cxi\1c:ncc 11:<1'1i1c\ 110 m0llific11io11 ol the itll·.1s 111c:i.r111c1I. The: LcrJIOph)'H'S ;rnJ spili1cs ol 1hr \Va1c1 ht1111I l-"or111a1ion wc1c t:\1111JcJ 011 a rclJ1in-ly fl,11 sc:;a Lo1111111, as i11dica1cll by bd, o( 1c11 ii;l·nous 1k11 iul scilimc111 and p.1UC!J,,.9 ~1t111p s1111e111rrs in 111051 1111fai:c:011s unih. A 111;1jor c.1i,l•\\CSI hii;h-~ in(c:ncd hom g1a1•i1y d;11a wa5 prnb· alily 1he lorns o( n 11p1~,..( ~ 111ag111as 35 well as mosl of 1hc l;uer 111.1i;mas. ~lo.>1 c111e111i, alnng this bult 1i11111h;111co11s wi1h eruption ll'II to acc11mul.11ion o( 1hc \\'attt hla111I fOlh in a b;1si11 1vi1h ;i sharpl)· dclinccl no11hc:-111 cJ1;c:. Thc1 c is 501111! c:l'idc:nce o( shallo,ving o( the 1va1cr lc,·cl loh·a1d 1hc end o( \\';ucr bl,md time in the: grea1c:r p1oponio11 of 111(fa,co11i, Lcra1oph)1cs al 1l1e 1c:ry cop of the accaion. The encl of Waaer lsl.an,I aimc was m;ulcJ L)· aLrup1 c:mcrgemc:. po"ibly in part along ahc: major cas,.,.,l"lll fauh no1c,I p1c1 iumly. This mo1·e111c:111, as wdl .is 111bscqucn1 1110\l'lllcnh :ilung' 1hii. lauh, "·as of an oppo)ile seni,e 10 the original 111on:111e111: the no11hc:rn i.iJc: wc111 down. O,·c:rl)'ing basal Louiscnhoj beds wc:1e clc:posi1c:1I rnLacri.1lly .11111 wc:;11hc:rcJ 10 (us III a brick-red soil completely unlike an,· 1h:11 arc: ru, ming at 1hc: p1c:sc:111 1ime. ln1ercala1c:d conglomc:ra1cs o( p1c- duminJn1ly Lcra1opl1pic cbus which are cspc:ciJlly abundant nc:ai the base o( thc'l.011isc:11hoj show 1ha1 1hc:re was a rather persistent cmcrge111 i,ourcc a1<·a of ohlc:r rocks c:xposcJ at 1his 1ime. Slow subsidence a her c,11 h l.011ii,c:11hoj time is rc:nected in 1hc: gr.ulual diminution in abundant:c: ol w11slomc1alic uni1s, 1he finer gr.iin silc o( the: p)roclauic deposit) ;11111 thl'i1 rc:\\·01 k.c:J c1p1i, .ilr1m, ;11u.J 1hc: increasingly exccllc:nl gratling of 1he 11111 Lcds 101,·.ud the top of the fo1111a1io11. The 01·crlyini; O111c:r llta)S Li111c- uo11c: rc:pte)cnlS almou complclc ,·olcanic c111icsccncc and s11b)iclcllle Ldm,· 1hc: lc,cl o( dlccthe wa,·e erosion of the older rock uniu. The hc:i;i1111i11g ol Tutu 1imc: was the brginning of rcnewe,I clilfcu:nlial n:r1ical moHmtnl, with nl·1vly cic,11c1I 01 1cj11ven.i1cd )ICC!• slopes )hc1ltli11i; ,,;id.cs i111u water of 1111k.no1.-n 1lcp1h. l::111c1gemc of 11.111 o( the ~01111c: area is seen in 1he aLnndance ol p;1rtially wca1he1cd Louhcnhuj hai;111c111S .imong 1hc: dc11i1al componc:ni o( 1hc 1'11111 Fonn.11io11 a111I it! the i111c1- lala1cd Llurk.s of louili(c:1ous li111c)I011e o( 1hc Coli l'oin1 l\kg.1h1c:nia li1ho(acic:s A brief period ol 11ca1-c111c:1i;c11cc is seen in the C:oni;o C.1y 1.imc:slonc l\lcmbc:r. The 1ccr,·s1alli1a1io11 u( 1his 1111i1 is 100 l'Xlcmh·e 10 h:11c: prc:sl'ncd an,· o( the diagnostic pc:1rog1.1phic u i1c1 ia whi, h 111igh1 ha, c: ren·a kJ some1 hing o( its l'II\ ironmc:111 o( cll'1t0silion, bur iu 111auh·e• IIC)l> and lll',111) p111c: c.111 ilil l111111111\iti1111 ,l11m·, rlul ii 11111,1 h.nc l1t·1·11 ;1 L.111k Jc:poi,i1 u( 11c;11 ly pu11: slclc1;1I clt:b1 i). Rc:nc:wc1I , ulc ani,111 ahl·1 T11111 1 imc: i) \n:11 in 1hc thi, L a11i;i1c ;1111lc\itc p) 1oclauii: rocls o( the 11am l.ullil 1-"111111.,liun. l\fi11c1al~.;irally this ;11ulci.i1e .1ppr;1n 10 t.c i1lc111 it,11 111 1h.11 o( the 1.uui,l'lllmj For 111;11im1. l'ou•llans l.ollil Fo1 ma1i1111 l1i\l01 y h 11l1\1111c in the Amcrit.111 hl.11111, - - - - 1·, \V. ltUNNUI.\-SI. 'IIIOM.\S ANII SI. JllllN, II. S \•kl.IN l\l.~N11-; 17:1 and has L1:c11 trl· 11c,I in I Vi1gin hi I I . mo1c:, elJ1I Ly llc:hley (l!Jh0 thn1\) in the lhi1i,h . J II > A ,l.11c: ol ~I ulcllc I u,cnc 11,·ar 1111· lo f I - 11011 (1vhich i11cl11clcs rhc IIJII) I oll1l F .. I' o I It: I o11ol.1 1·01111.1 111··1111 · I - orm.uiun c illl'd It) 11 I I • tr.-, 111 I ic llrilish hl,1111b) l·,• ·•Lli,h.-s I , , l. ' q .1 Vi1i;i11 hlJ11,b Gu111p The I 11 .,. ,· I r I •e ·•l;l' ol 1111: uppn p;11 I ol sh,· the To11 I 1· . . i; •.11 10 •th in rl1c 111 i1i,h i,l.1111h i111111,I.., o., ·u1111.11w11 a11d i, a1•1•11c111I fos-iliktous Nct'·c·r L· • • y <11111l'1111 .. 11.1111•1111s "uh the """ " .-01111a11011. lloriw111·1I for . r · . • ltS O any llrll'lll.1ll011 Ill SClll,' . I 1•t.,·ecl .in i111p1111;1111 I ok at ·111 . , , . t <.1111101 tt· ~huh II lo 11.11 ,. Neatly all lhc s1111e1111JI rd·•,. y 'tl;t ,l,l11111i; tl1l' n·11l11111111 ol tl,i) .11,·.1. . . . ·• •011, "I'' o iw1 n·d ·,s ,.- ·II - I I . SIIJlli;1.11'l11cd1a1;111uo(1ht·1 l . . . c .is l1c l''>••t.il b . 111 1111115 <Ju Le 111 , ·i 1 . ai.1s of ilillc1cn1ial \'l'rli I , o1t t·.1,1 )' n,p ,lllll'd n11 lhl· 1 .J 1110,-c111l·111s. ,\I.illy f 1 11 I· . . . such 11101·c111c:11u <H 11111 , 1 1 . . · 11 I• ,111es .111 Oh wlu, h <c 111•1Y 1,1\·c co11111111c·,I I L I I · placcmc:1115 110111 C1et;1cc1111s lo c;.111, T· . _o e Ill' uc1 of IJ11h di) ent.• ) tlls.uy 111111', ;ind C\'l'II 111 1l1c pin. The l'•oLkm o( 1l1l' gc11ua1io11 ol the 1111 •111;.i • . . Iha, or •he s1111u111al nohuiu r I · I: s IS ll11:i.11u .• l,ly l111lnl h'itl1 11 o I 1c a1c The ., . • f 111;1gm.1s is consiclcnd 10 I. 1 · .,uic:iauon o all ol 1hc . save OlClltrc:, as a re I f 1 Ital fusion o( h)·dr;11ctl upper mantle 11111c:1i· i"'- I o .• ,c mo1c or Ins p.11. fo11111I lic:11ca1h lhc C ·•-1 5 . .1 • 1Jc1111c;1I to 1h.,1 p1esu11l1 ,a, 1u 1ca11 ca al driulu L .1 ,. I lic:low 1hc sc:-1 lloor Tl . I· 1 c ween :> ,1111 I:; 111 211 L 111 I • · •c argc ,·u 11111c: of siliceous l I CHl'I cx1c111, the: ,·olumc of I· I Ii l c·ratop I) I,·. ;11111 lo ;, a er 111;1 IC I0l s 1c<111irn ti I . f mane le: o1·cr a ho1 izo111al c:x1c:111 . I bl , ic us11111 o uppn . • co11rnc1a y g1c11n ti 11 me11i,1ons of chc: ouinopping ro, l uniu I( ' . •a 11 '.c J'll'H•111 iii hyd1a1c:d IO 10 15 L r . lhc fusion \\';is l111111nl lo 11,,· lion for the ,·olumc :,• ,on·, :•,1,1•per m.1111lle, ll1cn che ouly adc1p1a1l' npl.111., • C a crup1c1 ts 1ha1 I · I ported .1djacc:111 unlusc,1 mJnllc . I w1110111.1 mo,"C111,·111, 11 ;111, I • • 11110 t 1c oro .. cn wh . · 1 ic.11ccl, parii.slly fu~cd an I ti . r " , uc II ,,·as ' q11 c·,\cil. ·• • • 1 1c:11 lls re r a, 101 )' 1 c i I I I 1 · uowm.-a1d and faterall)·· , , 1111111 s ""' )' , "I''·" ,·,I ~he c:1·oh11io11 of ihis po11ion of ahc \\'es1 lnili. ·. . . uf Jt1x1apoi,cd, f•hysic,1lly l0•11taui11 • •hies tS h lo.1s1Lilly tht· • espothl' iln ilJtplicd l1oriwr11al lose. 1_. -1 b 1 1' o( c~n,i ·rnd 111'1'l't 111;1111k 10 c. a1 111 c a 0111• 1hc Join I 1 rcsuhcd in 1hiclcn•·••g . 1 1 . _ 0 1uwc·u1 I inc 1•l.11n am < o1,·111,· II f'IIIC •I - . . I lime), follo\\'cJ Ly (Ollll>rci,sil'e (· '.1 1 1 11 ,•e lllll~a ~•-•i;l'_i. (\\',11rr hl.11111 r I ,II IIIC, I IC orm 111011 1 f · au t S)'Slc:m, and ra11icl u11lih '·I . I f d , i .1 111;1 J• •• • t\TI l>l' (L . • , Ill I u1 me au rmc, ••1·111 . I I I I ou1scnhoj lime) ancl 111051 nob· LI , _ . o h ;111, I' .11 111111 .ipplicacion o( ro111111c~sh·c: f~rccs.1. y, ·al11lail11,1111111g_<><c:.11.1ic 11<·11, 11 F1111hn c., .. su 1111 1c.:r 1hu ll'nm, ,11111 · c:111c1gl·nce o( ihe ii.land pl.ulorm Thl'sc . , i; . 11111111111nl Islands that submergence of an . - I) no c:111lt11ce .,, lhl· \'i11;i11 Island time •t·1gn1a •··· dy L111Jgn11udc C:l'Cr occurs t:d ;titer \\',11n · " • ..-as gcnc:ra1r y 11 · I I · mantle; lhe propot1i011 r ·1· IC p:iri1;1 lll>HJII o( hpl1J•t:d IIJ'('t·• o u 1ceo11s a11d m;ific 111. G . . the rate of dcfo . · . ;i m.,s "1 au>· 11111r 1dln,. Tl rniauon .md 1he 1.11c of 1c:111pl'1 a1111e I isc:. ac c::mern C.rca1n A111illcs is a u11i1111c ··111·1,,·1 ,.r I •A 1 11· s.il1n11 k ........ , 's,~ 1,N,11101~ l!, l'~cc uu. _, - - ., I__J - - IH C.\llDlllAN ClOLOCICAL INYUTl!;ATIONS of the c.11th'1 ii.lJnJ aru. This aru has nevtr been blankcu:J with the thi,k 1cnigcnuu1 sc:Jimcnu "·hich ha,e moJificJ .anJ l:11cr ~uiJc:J 1he ~11 uc1urJI c,olutiou of mou otogenic regiom: ii rrpicsen1s ansic:111 the di,ect intuaction of oce.auic canst anJ orogenic forces. The failure ol these rods 10 hne licen metamorphosed .and their 111hm1m:nl c1duu11atio11 i~ a nculy pri~rine co11Ji1~11··E· bly the result of .a lud.y i;eologu;al Jcci~eu1-tl1c Jnclopi~ · ¼ 1sh·e strike-slip f.auh S)·Uc:111 su'.llh. o~ tlie islauJ pla1lor111 Jloa,j~ - resolved 1he hulk of d_,e pm1-t:ou1~, Jdormathc forces. \\'idiia cht' al;i11d pbtfo1111. the 110111111:1111 ll'llUllll' tunes ha,·c Leen Jillcrcn11;il ,·ertit:;il n1ovc111c11h c:ime,1 l,y 1hid,c:11i11i; ;&1 dq,tl,. Although none of the s1r11c1ural or pc:lrologk cond11sio11~ 1le1in:1I from 1his study un neceuarily be applied lo .any other specific o1rc:;1. ncverihdcss certain 0L$crv.11ions c.annoc fail 10 uise serious questions con- n·rniug loni; uanJiui; geologic:il hypotheses which h:ive not been seriously 11ucsrioncJ in 1ccc111 years. REFERENCES CITED llocciu,, 0. B. 1907, 010 Da111 .. -V,11inJic111 Ccolo1i: Cco1rali1k Tklul.rifl, II.on. 1Ja111 .. 1, Cto(Uj•h. SchL~b. w . • 9. p. 6-11 (Tum•aicJ by Mu. EJi1h Thcilc, Torlob, 11.V .• l., anJ cumineJ by 11,c wrilcr) Do~n: f .. •9:ili, Zoniliuci0n micro(aunbaiu Jc las u•iu1 crc1Jcicu dd c11c de t.luico: Dul Awe. r<uol Mc•. w. 8, p. 58'.)...t87 llu,.lN, N. 1... anJ Tun 11. 0. f .• 1950, The 1111e111 N•I\ISi,O,·kl\lSi,O,·11,O: Jour. Ccul· on,• ~d. p iH'.>-511 Ill ,.111~,,o~ .. ,. t .. l'l:o!I, C.uni1c cn1pl•c<mrn1 wi1h 1pcci•I rck1<11cc lo Nur&h Amcriu: 1\11 c,.._.1 rnic"': Ctul. S0<. Aincriu Dull .• w. 70, p. 671-741 cu,1, Pn 1101.<>u, •871. On 1hc 1col"IJ o( the nor1hcaa1cr11 Well India hlanJ1: S1ud,· l,ul,11, Kongl. S><n•la \'c1e111t.-Abd. lbnJ• .• no. •2. p. l~I. -- 1881, Ou11i11c ul ahc cculol)' ol 1hc 11011hcUl<rn Wc11 l11Jia hl•11J1: N. Y. AuJ. Sd. Annals. w. 21. p. IU-192 Cua...auu1, II P. •!HI, lur Frase du Abu11bcJi111:u11Jc11 Jcr Radiolui1c: Ccul. RunJ .. OJ. SI. p ~1~!!2• uu~~uu. T. W. 19;9, The g<olon o( St. Thomas anJ S1. John. Vhclu hla11J1: 2d C•ulolo<an Ccul Conl Tun,. (llhp1uer, Pucr10 Rico). p u,-.5!'1 -- 1%2. \\'•iuli1c in \\'<11 l11Jia11 1pili1ic rocl.a: Arn. r.ll11cra•ogi11. w. 47. P· 791-80:! -- 19Ci,. Cwnil ul alloi1c In early oroccnic wolunic roch: l\m. Jour. Sci .• w.,261. p. 9~7- 972 -- 19Gt E•olu1iu11 ol uucrn Antilk•n i1la11J arc: Arn. A11oc. rcuokum Ccu•usi111 llull. v. ii. p. ~!16 -- l!IGS, Su-bu11om morplrolory 1uccn1iwc of f'O'l·Plci11ounc 1cc1oaric ac1iwi1y ol Ilic c.aaicrn Cru1cr A111illt1: cw•. Soc. America Bull .. "· 7e. p. 1291-1291 •1Ji;c.1iAUA1~,. P .. and r.11c.11non1, G .• •Bell, 11&1. r.1cmoirc 1ur In Coralliarir1 dn An1illcs: r.lcro. Aud. Turin. 2J scr .• v. ••· p. 279-565; w. 29. p. •99 [Alu, K \\'., lni. The ceolusy o( 1hc Rrili1h Virgin hbn,h: Ceo •. r.la&·• v. 61, p. 5'9- S51 t, I[, w. S. Ti;•,u. F. J . anJ VUIIOOC[N, J.. 1951, llkl•morphic 1uc1ion, anJ IIICla· mu1phic bcics: Ceol Soc. l\111r1ica Memoir 7'. 260 p. • l'iol cu,uineJ by lhc w1ilcr. -l -- . ----._.; , .. -... ~ T. W. DONNELLY-ST. TIIOMAS AND ST. JOIIN. U. S. VIRCIN ISi.ANDS 175 lluuuoN, W .. •9Gt. Orii;io1 o( hii;h alumln1 louall. 111Jcsi1c, 111J 1bci1c 111ai;mu: Scic11<c, w. lt6, I' 6'Hi,7 llunn, J. J. •9s9, S.nnc 01lnc1alugi1JI equilibria in 1he 1111cm K,O·Al,O,-S,O, 11,0 Am. Juur. Sci .. w. 257. p 2H-270 lln11n, J J .. llhna, C., an,I l!.1O1111, D. II, 19lil, Some •llc1J1io11 rr•<1io111 i11 11>< 1ym·111 Na.O Al,O, SiO,·11,O: U. S G,ol Su,.ry l'wl ••••••:r 4:!111. I' 3111 llO 111 U, II. II. l!JtCJ, C:hcmic,;al c111111m1ic1nn a11J O(llhJI 1,ropt·111e:s ol commun ch11t•f•)lo\C·111 \, ·••11 I: .\rn. Minci•lui;iu. w. ,~. p li:!1-liC,6 lloc.10~1. A. C. 1905. Zur •••·troguphi,· tier lki11111 An11llrn 111'••1.. 111111 1;,-,.1 1 .. ,, Uuiv. w 6 (l!/02-•!JO,), p. 21i-2S:! •llo•N•1.1.11. II. n .. 11110. Not;lc Ut·11ur1l11i11a::n O\c.:l Sc 'I h11111.o' (;lor1111lil ~LuullllJ\ 1\l..c· N11u1lu11lcres. :/,k1 Mw<. p. S61-,G8 •-- 1816. llcbcr Jic rnincralir,chcn Vorko1111111,inc anl ,In loud S1. ·11111111,,. K,d. :!Ith \'cu. clcr Naiur (. unJ l\cruc. p. :!6:?· ~(if Ku,r. J. f .. 1926, Ccu•o11 ol rhc Vi111i11 h••nds, Cukhu, anJ Vi,·,•ucs: l111r0tluc1io11 • .,J rc,·icw ol 1hc •i1cu1urc; N. Y. Au,I Sci. Scic111ilic Suncy ol l'ullo kico a11J 1lo,· Viai;in hla11J1, w. 4. ••• I.••· 1-6!1 klNNUW, G. C .• l!J~O. P1cuu1c tulumr 1cmpc1.11urc 1cb11ions iu t.',Ut·r .11 tlc,.i1cJ IC"tu· pcratu1<s a11J prc11uru: Aro. Jour. Sci, Y. 2ill. p. 5f0-51>f •II.Nol, Rn. J. P .• •&52. A hi110,iu• ICC0lllll o( s,. Thom:u. \V.I; New York, Charles Scribner and S0111, p. 207-21! lu1•ru1N, C. C .• a11J Kuvnow, P. W .• •956, (The rdaiio,uloip ol the 1hcrg1oJynamiul pararoc1cr1 J'. T-f (or tl,O anJ ,o';'. aqueous Nae• sulurions): Min. Soc. USSR Tuna. w. 85, p. 529-SSf l10, .. 11. E. G., •965. re1,ology o( 1nJcsi1ic, 1pili1ic. anJ kc,a1opl1), ic flow 10< L. no 111, ccn1u• Puerto Rico: Ceo•. Soc. America Dull.•· 76, p. 57-88 •M•cLun, \V., 1817, Obscrv~1i1111s 011 1hr i;rnlo,:y o( •••• Wn1 •11,liJ i,l•111h ""'" IIJol,,.1,,, 10 Santa Cr111, indu1iwc: l'hibJclpl11~. Jou, AraJ. S<i. •· I, p 1,i .11~ llHUIIOH, II. A., 1!126, Cco.01,,y o( 1hc \'i1gi11 hl•111h. Culrl,r•. anJ \'1<1p1n: t•lopiug· raphy: N. Y. Acad. Sd .. Scicniilic Sun<y ol 1'0110 Riru ~11,I 1he \'111:111 hl•111h. • 4. pl.·• p. 71-lfl; pl. 2. p. •-219 N1c11olu, C. I)., 1959, Aulomc1a,om~1i1m in the •uwcr 1pil11cs ul aloe llu1hh ,ol,~111< aeries: Quart. Jour. Ccol. Soc. (.ondun, •· II t p. IS7-•62 Noc110U11, S. R .• anJ ALUN, R .• 195S. ·1 he gcuchcmi111y of 1u111c ii;nt·ous ro,l 1<rics. Ccochim. c1 Co1mochim. Acta."·•• p. 105-•t2 Ou1cu. C. D, E1,1Nc;, J. I., HlNNION, J. f .. 11 .. O1ou, D. C. anJ Muua. I>. E .• 1959, Ccul'h.,iu• in•c11ig41ions in lhc cJllcrn C~riblocan; summary ul •%s anJ •956 uuiac1. p. 17-•09 ir1 l. II. Ahrens, f. 1'1cu. K R~ukam•. an,1 S. K. Runcorn, E.l,to'I, l'hy,iu auJ Chcnoi1ny o( rhc Euah, Volume 3. London, l'•·•i;•mon l'rc.s, ~1.1 p. OawrLU, P. Ill .. l!JtiJ, Allah ion nch•"~• l,c1w1<·11 ••p••• a11,I lelJ•1••• phH<: Am J11111 Sci .. w. 26•. p. 201-2S7 Os1naN, [. f .. •959. llolc ol 0•1~•11 prn,urc iu 1hc cq1ulli1•111111 an,I tliflcrrnlu1i .. 11 »I baullic mai:ma: A111. Jour. Sci .. •· ::s1. p. (i()!}.617 R611 n, II. J .• l!IGO. Zur Pcuoi;nphic. Cco<l,cmic und Gcnesc drr lll•i;11••111c nn,I l.ai;,·, 1U11cn dc1 Obc:1Jcwon1 unJ Un1crluL0111 in O,11h1iri11i;rn. trnl,ng, r I u1>d1u11~ CI:, p. 1-275 Sc11oaN, k., •962, Sc1nl-qua111ila1i.c an•lpis o( chlori1u by X ray 11iff1a<11<,11 \111 M,11 cralocl11, Y. 47. p. IS8i-lS'l2 •Sc110M1uac;11, R. II .. 107. •>ic Junglnu-ln,cln, in grulni;hcher 111111 Llo11111 "l,n ll111,id11 Bcrclaau1· Almanach hir E11llunJc, p 367~55 S11u1ao, L., anJ OaANNOCII, \V. \V., •%2, Rapid analy,i1 ol 11li,,1c. CJ1L»11•1c. •nJ I''"'' pha1c rocla: U. S. Ccol. Su,cy llull. • 14 I A, 56 p. S11uaan, G. L~ Woaiu.. J. l., anJ [wrNc;, Ill., •956, Crni1y mcnu1cmcnu in aloe Virgin blanch: Ceo•. Soc. Arocrica Dull .• •· 67. p. 1529--15'6 ( (~ .. + C> ~ ........ . ~ ./.." + ,,. .. Q,. " . ,. . ---.\ ~,• .,l' <5 I '., ',\ ;, ,:_._!_.:·.~, ... ·~ ...... w , -----~ 0 _:,,.: ~\-=·•~",','.'. ~ ( Quaternary U. Cretaceous L Tertiary C C .Q <t en ::::, 0 ., u C -., ... u ~-- Q. ::::, 0 ... C> 'O C C .;; C Ct '- > □ B ~ ii 0 C. ·•· LEGEND :~ .. ;;-:"· "I' Alluvium Dikes and Plugs: qa • quartz-andeslne porphyry; oh• ondesine-hornblende porphyry Oioritic Rocks Hans Lollik Fm.: Augite andesite volcanic breccia and tuft Tutu Fm, Volconlc wacke. X-cp outcrop of Coki Point Megabrecclo Ktcc - Convo Coy Lt. Member Outer Bross Ls.:Thin-bedded, siliceous Is. LouisenhoJ Fm.: Augite andesite volcanic breccia and tuff, with minor conglomerate C-· UNCONFORMITY ,n ::::, 0 CD u C - Cl) ... u ... ., 3 0 ...J -4-·.:.. Quartz keratophyre dikes and plugs Water Island Fm.: Quartz keratophyre flows, flow breccias,ond tufts; rodiolorites, spilite flows 1/·i ·•• HUI / / Contact Fault, showing displacement Attitude of bedding Attitude of fault Attitude of intrusive contact IUPP[O 1¥ THOMAS W DOIIN(LLT 11,56- 1157 l SOuTHW[IT TO•TOLA 1¥ CI[ Ml[LSLIY (tlSII - - ------.,--------------------------------------.... REFERENCE NO. 12 .•;\'·;' •• • , " ,. ' ISSN 0500-4780 CLIMATOLOGICAL DATA ANNUAL SUMMARY PUERTO RICO AND VIRGIN ISLANDS 1987 VOLUME 33 NUMBER 13 "I CERTIFY THAT THIS IS AN OFFICIAL PUBLICATION OF THE NATIONAL OCEANIC ANO ATMOSPHERIC ADMINISTRATION ANO IS CO"PILED FROM INFORMATION RECEIVED AT THE ~4,JIOMAL CLl"ATIC DATA CENTER, ASHEVILLE NORTH CAROLINA" a 5(~ .1) ':],I..,,. _ 188 0, noaa DIRECTOR NATIONAL CLIMATIC DATA CENTER NATIONAL OCEANIC ANO AT"OSPHERIC AO"INISTRATION NATIONAL ENVIROIIIENTAL SATELLITE, DATA ANO INFO!fflATION SERVICE NATIONAL CLl"ATIC DATA CENTER ASHEVILLE NORTH CAROLINA ! , ! i , __ ; U I_ './ "-1 '-j' (j /-.; . .. f:: ( TOTAL PRECIPITATION ANO DEPARTURES FROM NORMAL I INCHES l STATION JUL Ptl(C IP D(PARIUR( VIRGIN ISLANDS '..;. ':,.14, ST THOIUS o, "'· ,,w,· DOROTHEA A[ s '.,A,'!'1. 12 ESTATE FOAT H Yl NE A ,l.04 ESTATE HOPE I , II RED HOOK BAY I . 22 TAUHAN FLO FAA AP ..... NINTBERG ... l --DIVISIONAL DATA-------> I .40 - I 85 ST CROIX 02 ALEX HAHILTON FLO FAA I . 2 2 - 2. 1 4 ANNALY 2.28 ANNAS HOPE I. 80 - I .22 BETH UPPER NEW NOAKS I . '12 CHRISTI ANSTED FOAT 2.28 COTTON VALLEY 2 2.50 H EAST HILL I . 41, ESTATE THE SIGHT 2.20 FOUNTAIN 3,00 FAEOEAIKSTEO 1 SE 2. 3 1 GRANARO 1 . '5 7 HAH BLUFF L-H STN 1. 'I'S HONTPELLl[R 2.55 --DIVISIONAL DATA-------> 2 .OB - 1 . 1 7 ST JOHN OJ CANE EL BAY PLANTATION 1 . 7 4 CATHERINEBURG 2.02 CORAL BAY 1 . 7 4 H CRUZ BAY I. 'S't • 2. 11 EAST ENO 2. I 0 LAH[SHUR BAY I . 1,'5 --DIVISIONAL DATA·------> I . BI . 1 . 44 AUG SEP oc T NOV ----- PR[( IP D(PARIUR( PR(C IP DCPARIUR[ PA(( IP D[PARIUA( 2. 7 2 2.57 4 .5) 2. 7 I, .40 4 .32 2.'tl, 2. ,o 4 .57 I. lo't I_ 1,1, J . , 7 2. 4 1 I . 4 2 4. JS I . '5 3 1 . 4 3 3 53 2.22 - 2. l 8 1 . 5 0 - 4 . 1,0 4 . 1 4 - 1 . 2 7 1 . I, 3 - 2 . 84 2 . 7 'I - 2 .84 2 b5 - 2 .bO 1 .80 2 . O'l 2 80 I .25 - l 1 2 1 .50 - 4 .SJ 4 . I 0 . 'l 7 I .32 2 02 " 2 5 5 .Bl, 1 4 3 3 7 8 '1 3 . 81, 1 1 3 1 .45 5 1 3 1 B 1 1 .:n 4 .Bb 1 . '!1 1 '50 3 .00 2 . O'I 2 .'12 2 52 1 . 45 1 I B 3 . 1 7 1 . &2 1 .42 '1 2 . 3 3 1 .38 2. 1 0 4 . I, 3 1 52 - 3. 0 B 1 .BO - 4 . 30 3 b8 - I . 7 3 2. 1 5 2. 2 J 5 .07 2 .20 1 . 2 2 5 . 2 7 J. I, 5 3 .51, 2 .27 - 2 .02 2.42 - 3 .55 3, 75 - 1 . 3 7 1 ,88 2.08 ' 3.08 1 ... o '1 '1 3. 0 8 2 . OB • 2 . 5 2 2 32 • 3 . 78 4 . I 5 • I . 21, S[[ R[F[R[NC[ NOl[S FOLLOWING STATION IND[X 7 PA[( IP O(PARIUR( 1 8. 4 7 1 7 . J 7 1 2 . '11 11 .4'1 10 JI, 1 0 4 3 1 J b2 8 5 1 1 J 25 8 2) 15 .Ol 11 .45 5 8bH 1 '5 . 2 7 15 .48 1 0. I 7 1 3 . 80 1 4 . 5 1 1 5 . 23 15. 7 I, H 11 11, . '15 1 J. 7 B I 4 .22 'I 11 1 2 8b 1 3 .OB 11 11 5 2 e .54 4 03H 1 0 3 'I I 0 b4 11 1 7 I, 01, DEC PR(( IP O(PAR I URI --- 4 4 J 5 . 1,5 4 2 7 2. 32 2 . 'l'I 4 1 J 3 '10 1 2 4 '14 '! bH J 52 4 b2 11 J 7 3 2. 3 'l 3 . 1 'l 2 'lb 5 50 3 74 2 'll, 11 4 42 3 82 04 3 '10 4 .42 11 4 Sb J .b7 4 04 4 .04 21, ( PUERTO RICO ANO VIRGIN ISLANDS I q A 7 ANNUAL PA£C IP O(PARIUR( 7 0. I 7 1,7,1,1, 4 1 . J 7 42.84 '50. 08 5 3 'I 7 1 0 2 3 '-¾ 50 1 0 58 1 b 48 8'l 55 '51 5 4 .8'! 58. 10 I, 1 . b 7 5b. 75 5'1. 02 5 8 78 55 2 1 11 4 7 48 .22 4 'I . 4 7 40. 1,2 4 4 . '! b 1 . 2 2 !--· ·-C !)J ( STATION OUTLYIIIG ISLAIIOS 01 NOIIA ISLANO 2 Y IEQUES ISLAIID t2 --DIYISIOIIAL DATA· - - - - - - , Y IAGIII ISLANDS ST THONAS 01 DOROTHEA AES RED HOOK IAT TAUNAII FLO FU AP --DIYISIOIIAL DATA··-----, ST CROIX 02 ALEX HANIL1011 FLO FAA AIIIIAL T BETH UPPER IIEW WORKS CHAISTIAIISTED FOAT --DIYISIOIIAL DA TA - - - - - - - , 51 JOHii 03 CATHEAIIIEBURG CRUZ BAY --DIVISIOIIAL DA TA· - - - - - - , ( AVERAGE TEMPERATURES AND DEPARTURES FROM NORMAL !°F) JAN FEB MAR U.i 1 ~ ~ = .. - i .i i ' .. .·. 'II: :!: ·• .. 1.-· a ~f~- ~1,. 1 JIJ.1 11, 3 71.4 11J.6 11, 5 7'5 7 7'5. , .. 3 ~ 7'5.1. 75 I, ~ ~ H 78 8 1'1 I 11 'I 11 3 I 7 77 8 I 2 77 5 ~78 l 77 8 77 'I ~ ~ ~ ~ ~ ~71 I ~77 a 71, e ~ 78. 1 I 5 77 J 1 74 5 -2 ~74 l ~15 'I ~15 I ~77 7 11 2 77 1 71, 0 b 71, b 0 71, 4 APR MAY JUN JUL - ,. -- ~ ~ 1'1 8 78 1 ,, 8 78 I, ~ 81 1 3 10 2 111 l ~ ~ ~ 1 81 J ~78 J MBI 0 e 7'1 7 = - ~ - ~ - ? ~ ,. - ,. "' ,. - - i - ,. ~ - - - - ~ ~ ~ .. - ... ... - ; .. ; "' .. :!: ~ 0 80 4 ~ 83 2 ~1'1 5 1'1 I 80 0 80 4 83 2 78 1 ~7'1 'I HSI 4 ~ ~ ~ 81 4 82 4 83 e I 8 10 I 3 81 2 2 82 I, 8 80 I, 82 I, Bl 'I • ~ ~ ~ ~ H ~ ~ ~ 2 'I 80 I, e 82 I, I 2 83 'I 2 I ~77 1 ~78 4 H1e 'I ~81 J M82 7 HBl 2 I 3 1'1 5 3 eo i. e e, I 1 ' S[[ l!f(l(NC[ IOl[S rouo1111, SIAIION INO(I • -·--- -- AUG SEP oc T NOV = ? "' - ,. - ; "' - " - "' "' - ! "' :, ~ - - "' .. - ... - ... ... - ~ ... :;: "' ... ; ~ C, "' ... ~ C, --- - --- 84 4 BJ 4 H • 81 1 Bl 'I eo e 1'1 0 84 4 83 4 82 '5 82 2 81 4 18 'I H H ~ ~ 85 I 85 I 83 'I 82 J 83 8 I 83 1 2 3 82 7 8 80 b I ~84 7 84 I 83 4 82 2 ~ 82 I H • ~ H H ~ ~ ~84 J 82 e 180 I, 84 1 2 e Bl '5 2 I Bl I 2 81 4 2 ~eo I, HSI 'I M7'1 b H 11 ) ~·· '5 83 e M8l 2 81 e 82 b 1 82 'I I '5 81 4 ., 1'1 I, ] I ) PUERTO RICO ANO VIRGIN ISLAIIDS 1'187 DEC ANNUAL - ! ,. i = - - ? i i -! -- .. i: * H7'1 1 • 78 I ~78 'I 1'1 1 71, ., • ti ~ 81 0 82 0 78 e I 3 80 b I 81 0 M81 5 M M H78 5 • 7'1 4 • 7'1 I, 2 I 80 'I I 171, 2 H 11 'I H M 7b 2 I J 1'1 4 2 5 0 i 1i ;!, ;-ii I "f..') ·pi·:1,,L :Jt:-'~t,J;;y ~©P'CHr;.d lrr COOi:' Dr=D.tim1 with t)Hi ·r·· . , .. ~ ---~-.. ,~-• --q<q""'" ~---· '""~.,~~ ... ~~«- ,u, '-'-~=- "'' ~ ~,---,....,~--==•·· '"-'""'••'<r• =-=_,...,=, ~''''"""""~'""·l~" ,.-,. •_"'~~~=.,,•=~•~-~~-~=~~-~~-""""'~.~----•l"'"~""""'·--~--~A =-~~™--•~--~,,--~=--• ... -==.,--=-··, ~-==~~ =~•-- --=- ,....,,,. lJJJ •. ~f'~ffltt''t>:1,t".t:',\rG~L f, ::t)T£:.Cf;ON AOz£NrW , . .--~-~•~•-~••~•m· ,---~-•=,=• ••=•-•-•" ~ ,_,.,,•=~e."-=~~•••""'-"=·•---~-,.,,~,._...-,.... . - •=-~-=•~=--•-~'"'' - ~~,~~, ~~-" ~~~~,•-==~--~-=~- I I i ' ' •'i:i 11J' :t: :.' ,: , ./ ·! / ' ' '~ '-",_,,,,. . !J;, •' '. a '"~ '' 'f 11 d• .! '¼ :. '>, '}? ,3 ~-.i t ~'. 1\\i ':;: 'G 't z,;; :{:: 9 '-~) Li, CJ1t)JX ' ,I 1 i I .. •· 1'· .. ' I . ' E ! I I i I . '' /,, 1' .· ,. I . , .. •, I - , . I i ·, I l ! SURFACB OF THE TURPENTINE TU'I'U :ey ?,oIJ·Jrt P Grav?:::\ 1J,1.1.z1_ Relph Gonz{i.lez C-ruur'.d-,.,;;:i.-'-:er lcc.·rels in ':'w:: Turpe".1t:i.nc Ren bc.L-;in aquifer~ in QD..Stern ;):_., >xi:c.i.s 1 ,,:c,1:·c :--1ea~;l1.reU i':1 '',2 11ell.s on :.:;er.,1:J"''.1;1bcr 11 1 .193"? anc.i 2 · ' · - ~ r, 1•os p··~,~,-,.,.,.,0 Q' The n_1_1:itud(➔ o_f ~,11 1;le.'..ls ·w2.s ?')::(-'E'=l0Jll8..:,~--~ r~1.,•,r:,.i-lC2. t'.clr ''""· L'-;--''·• - • u='.fr_: ... e.1,ced Lu ~c1own }_anrl surface c1:'...L_'..:uc1.c. ber:clr:(t.,..ks lJy use o~ a. level ,.1_•r,1c::.'/ ~,.str·-·~~1c'.l''~, "::.c. poter.tiorrec·cic s1_:rfa.c2. uap "\lil'.:i prepfl ::-cd 'Jy the :_:,.-J. c;,_,0 '.u:;iccd S0r,,ey ri. cooDet,::i.ticn w:i.-:.::.h '::ht~ U.:~. 2.nvj_;~or:menta:!.. ?r~~ertion 1~~0nc.y . ..-,,-acL1.nwl vo'._c2.,:iic -::ocks c,,nc1.t-:".'J.ic 'Tucp::<n'.:in.:: E1-.n br.s.i.n and 2re l.(.''.'cl __ }y c, 0.m1:.·la:·.r:. ·,,,y ,'.;._;.),_lvi:'3.l cfopusit.s (lk1··\.r,o:: . .-:y, ~95S). '.!'h•.:. a~.J.,1vinl c1.-::p')'_;i:.=: 1:.c~,1 rnr,zF• t') lrO f•-oet '..n d1ic:c:H~r-is, 'Jc,y_rn_,_1 '.'12.tE'.r in the T;1J·~;e,-,.~.Lne Pun Dt.s.:..n 0Cc.l1.:t.:.'..: ~.n i:"hc ·~-cac.t"'...n:ec_\ volc.,c=i_n_~c i·ock a1"c.cl allu·,ial c7c=>po:;l·:,:: drYpo.o:L _,:, 1:oJ.cac.::__'..., ·Jrc;~,, ,,,.<1.r2r·-caC:~r_: c.nH:.i.ticrns (.Jorc'..m1, :~97::,). Tl~e c'.H! c•r1c.rc:i'="ce.::_.::_,d to i:ie :1yc'.rat!..Llca:lly co·1.n0ct0.cl wi'.::h nic!c '1;0~·-1 dsp::'.::1s -·.n '::~1e t,us_:_E c:c_;.o TP.·~ge ~rum .:::;~, i-_ie_l_r)\,' "::i!1d s 1_'rfaC"'-· .~tJ :._,_:.v-i.al Un"C ::'ractLtre.d ,':'.l:vr--:Ta.~ wc1ls we-i:e :1eS_Y1g )U1T_pe.d 1 or p1...unp:Lng hal\ just '.:er~irwc8d, ,,..;':\0n :~}1e ,,,-;J.tP.'" '..ff✓sJ..;; were cEc,:;'Jrr!cl (Lc~:Jl!-:> 1). T}iP.se. Via'-.er levels "1 · e - -cr~·r~o,,· ,_-.,·ne1.·-.".·o·_,-, .~~~c· •.·.c w2.,~er-level r-c·:_.2c::t :c:. P'JI'.l])lI"{ or -:-c~cc·/ r~v .. , .:...._c._., - r, "° -L~- " ,::oc:.-i 1:-:_ons t_-nro·~i~f1 ou.1:. th2 Itcr;J(·:f\l~irn' !h:n '..);-.,:.s Ln ;it ::he Lin:c-~ of mea~~l,_-,,.01.r::ent c~~n:iot -~)E'- 2-s~,-:1.;11! 02d. ,\.dd::.-c Lo:vd. inf:Jtr1~:cL-ion about grr.>·--1nd-w,,1.:,~r _;_e_ve_l_s in t}1e are::1. of c;tu,:::y ~-'-i 2 ·1a:_-l,o_b1c lro:'l 1~h;~ ~-T,S. G1.2::::,J 1)g\c;c1.l Su:rv~'Y, W.s.1.c.r Re.SO'J.rces ':a.:.:.ibbc,J.n nisi-.r~:~t o.=1-·icP- in San ~i"J:m, ')·.v:,.r-to R:.co, 'l'c-!.:... (809) '.) __ v~_:::: -i_nr: 1:c~n~l~y. t.W. :959, Gco~ogy cf St. 1'hoDas and St. John, Virg!n J_~;l2.nds: TJr:pu:Jl.i~;n,::-,_-J Ph.D. disser1_;;,t-'on, !"1rl~1ccl:.c.n, t.:11iversity, l?r;i p. (;r>r;, /7ty c [,fj :ler, =.nc:.; 1981, Re.p:=irt on crn::·-.".'ent g r.ou,Ld wo."!::er con.C.itions -.,1 t.l:e l;.S. Virgin :~ir;r1ds: Prepared _br d;~, gov2rrn:im1t of th2 U.S, \/ \ rg in I:,; lar,~l s ]eD2.rtment of Con-sec'.1a'.-ion 2.nd C,J 1 ::.ura1 Aff;::: i. t·s, f.Q fL Jorcl'cl.D, D.C. anc\ Cosnr:r, O.J. 1 1973J t, .Sl:-rvey of tJ--:e water resources o.'..: St rn·rws, Lr?;in Islands: U, S. Gtl:} Logical S1_1.rvey ope.n-f L''-e '::""'°!IJO:·"'.:., 5.:) p. ~>ccve:1.s, K.'S., C;):ne:?'.-G6r:wz, F., and .t,:icco. 1 J,, i98~, Water well . .,, in tbe ~.S. Virgin Isla~d~, Pt. 1, St. Tl!unas: lJ.S. GAo~ogica: Su~vey Open-?i:e Rcpo 0 t 22-82. o •-•~~,, -•• = _ =~,T~ n. ~• ' - •~ a.Ca - > "'v _ ="==•«,,cc.c,,'"'°,=,""•'"""'"""-'"'=-""e,""'°'>"='>'<-"~'''-''~• ."(•' < <~1':.:,.,-.. '.:L;:\\/<:'.Y QI) (' -, l! I cw l l 12 Li 'r - , l (-, J.7 1.8 19 './0 2: ·i "' .. /, "/'1 .,0 YJ 31 J2 ·.1J J/1 ]6 :.:. ,' '18 1,1 Y:1.i'Jf,g. 1. Descr,"prion r;f ~•HJ/ls i:ltltf SGpi0n1h·er 11, 1.987 ".r,-:...1tet-•!1?JYel m,1asurn1r1t.1nt.~ in Turpr.mf:!t1f1 Run l'Jasin1 St. TJuJmt..-1s 1 U.D VitfJ!n J.;;l,:rnri'.g \'Jell id.e i.l ti/:i.r.r1. t-i.o:o rn.nc.ber ~ 22 r;7 1-;.QC,l~S 35 2-0 C :_ s:1 D2 rJ :)(JI.., 535 8UC :_ :-\~! U2 ~- '.J 6L:. '5]5 ~{(J() .', !.3::.0 i B n01;._'_;3::; 90 c: 1 S'.~O.l 7'.)G4SJ5900 -~ ':'2.0J.(;\)(,!.:5?,5900 .'. '.-Q () l G'J G!: Sir ()C 00 ~1:~/0L::?_Cl(J/j 5331.00 18'.?.C,3/'..)01:531100 :S'J.0:~SQ6L: 5311100 :L () ':'. C<r 9'J GL~)JO')OC 11L:'.'.".:·290FiL,SJ~.'.iOC L3?.:)2706:;..'..J3:i 800 l. 82'.)20061:532000 18202 JD6!1S3 ~. 900 182019U:)4_)3:'.900 132016064:JJ?.OOO 182.0J 706!1532200 l c\:;C/l '..l6/i:)3L500 l ti'.!.(.' l HO(ll1SJ/.SO\) i. t.L•'.C L / (J(,Lf 5 3JQOQ ·, ~'-~'. C \ ~: 1:01,533 l 00 1 t.1201806453J200 _LH:2Gl 91JG4533300 1820] 506/-}.532700 1820160645]2900 1820.l.5061,533000 18 201L,004532900 -1 SL C 1 '.W 6/153 :.LrO rJ : g2 00906/1.)]1.30 0 : 8200806,'rSJJL:OO ::_ g 19~: 3QG!i:S25 JO 0 1819/: 006/l-5252 0 0 .,.o !_l3}SO(,i.":;', _:., '._QC 1f\l93 r:L;6L15 '2.5()'...: t; 1 g 19J 7 OGL, r, 21, q DO J. 819J5 0 6t't~ 24 1,00 ~8~92JQ64.S24lUO Hc:,r io Bryan W<c:,.J 1 iH Ifa.:cic B1_·y~t11 ',fo:_l lr2 lock1,r.rt. Well Ji: i:.,ock:1a. ct 1,\ r:: 11 H'2. LocHtar~ Wi~2-l -1,:s DPmit:r.·y 1,ir::.1~ VII-IA \ic.l:. fi _;_ Ti.:.le~s T,:e~J. Ii'our v:_Ln(;.'::' Pl20a v:e.:':_l iil Four ¼'inds Plaza ,,,c:_l fi2 Gene E;;lin WclJ. if 1 Gene Jg2.in Well /f2 Gc:nc Eg_L_Ln \11elJ. 1/J E . .Stee: ,;.,elJ. 0.sbo.rn Harvey Cru.~;1-•er \1:ell Bcc:.b3ry Wu:'..l Creger _l'fo 1.:.o~s We l.~. Cn~ger ~1otors Well flJ Creger Notor.s Well 1/4 E 1 s & A Corp Well lll E I s & A Co-c-p WeJl ff2 E 1 s a A C:orp Well f,i'J E's & A Corp Well {/4 F~ancois La P:2~e L. Smi_t'1 r~atth:'..as Po~y Poly c, '- C,;i.,~. 'J/Dn-.., con Gn~·-i:~-/D~v c;o~1 ?u~lic \:ell/D~di well (Gov. o;" the \firg·\n :!:::;L:.nc~s) DepL. of Agricu:!..1::,_::n, \11in:nl Shrol·_'2r Y'3tU' <l:r·LU·:id 19:'7 1978 l'j73 !. 981 1_050 1 s _I_ 978 J. 978 1978 ~960 1 s l 950 TS Depth oi' W'::' l.] (f',,et) ... ~, of r····•-··-···---·----··---------,--- i \Vt.ter h;?e1 ! bD1c,w h::.:w:I 1Nti.ter t,~veJ aJi:'.tud,e (feet) ·----•--'·~----------+--------.-------r----- \1, c ·1 ' : 75 l5U j_L:'l 10(] 30C 285 ZZ5 1 as 105 '_60 2_:_o ~ ') .. --'~-:> 55 37 7] 69 '.5 ]6 36 Open hole, O•wr, hole 'J1)erc ho.I,.., Open f'colc'. 0:;)Pn hol2 Open ho:1.e Qr,,::sn ho ~1,2 Oren ;w ~c::. I ,. ll _'._J 09 08 05 ()6 03 80 S6 D 09 :2 - ' _) / 66 76 JO 32 :22 27 26 71 20 18 19 l h 28 1 0 .'..O ., •• a 1 T () _l_l} ?6 209 708 18~ 181, 183 .'..83 15VRL) 175 175 2.22 2]9 :65 153 156 131 ll2(RL) 86('./L) 99(RL) 1C8 1 0 il 1.08 1 'J8 189 116 128 108 107 ,09 83 BO 80 30 -B3(P~) 01 05 ..., ' 1- ~• •• :J 2.:: 0 2:;.s 192 19~ 128 2:;] :Z..'1 2?:3 2:J~) 272 106 165 1, .. 4 :.1· CJ L:) 2 1 "/ ~. lJB 1_,10 lJO l ~: 5 1:;5 1 ·17 _l l,8 L'.3 l:~6 !:'S l . J. ,3 JS \l ----- ____ ._ -----'---~--- i i3°i7'----------------- EXP~AN,I\T!ON P(JTt:::NTlOi,':ETn'JC CONTOUn - Show,:; Hlt!hicJ0 o? w!i!tor '1r-.h}o in iew:. t)ag/u,d wfr;irn ~'.ppro:dmntuly locLWd. -:1•1@rlo{! {?) whtH0 hc(<'i:'n lB ur1c1:trtain. ContOur interv8l 'liHis.bl·H. IJ~ttum )fJ rH,i~n JJi:1\'! t1~v::iL l'!f1TGl·-LEVEL D/',T;.\ CONT!lOL POINT·- Opuri mJ1r1 1Jm i!l th0 well n w:bur sho,1.1n <"Jn 1~1blo ·1. Nurribor !r1 pt•.renths~€•'.1 is ?ha n:~itudo of w:.t,·:,r !ovo/ in 1-::.1e~. Daium i'i: mean l.81:. lev~:iL 00,0J..~:'~t ,. -----•--·-· ------- WA~SOI.ACES tNVESntu.~ f.J~~1: :· ,_ REFERENCE NO. 13 I '--- ! l I I I j I i ' I l ESTIMATED WATER USE ]N STa THOMAS, U.S. VIRGIN 1SlANDS, JULY 1983 - JUNE 1984 By Heriberto Torres-Sierra and Rafael Dacosta . "k. ,- ~-~~'•~ "C'"~-~ Prepared in cooperation with the CARIBBEAN RESEARCH INSTITUTE COLLEGE OF THE VIRGIN ISLANDS ST. THOMAS, U.S. VIRGIN ISLANDS DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY WATER RESOURCES DIVISION OPEN-FILE DATA REPORT 84-721 ESi/MA TED WATER USE iN ST. THOMAS, U.S. VIRGIN ISLANDS, JULY ~ 983 - JUNE ~ 984 By Heriberto Torres-Sierra and Rafael Dacosta INTRODUCTION :,ate r use :fa ta l wi thd rawa.i ,1nd return amounts) has c.iwavs jeen the ~osc jifficult element r:o uetir.e .:.n the rydrologic cvcle. :he ~eed to 2eterm1ne the amount of water used to meet ?Ublic, -::or:unerciai ar.d Jomescic ~eeds among other ~ses is 2ssential where the available supply is inadequate. In St. Thorr.as, L".S. '."irgin =slands, where streamflow cccurs mostly during periods of intense rainstorms and ground-water resources are limited (Jordan and Cosner, 1973), water-use information is critical. In 1983, the L'. S. Geolog- ical Survey, Water Resources Division, in cooperation with the Water Resources Research Institute of the College of the Virgin Islands, began a general- ized inventory of water use in St. Thomas. St. Thomas is located about 20 miles ease of Puerto Rico (fig. 1). The island's popula- tion increased from 16,000 in 1960 to more than ~7,500 .:.n 1984, paralleled with an in- crease 1D water production to meet te-' public water-supply demand f~. 2). .,_~ -~. TJil:-~- ;,,ater dei::ands have increased also in response to tourism development. Although the production of water increas- ed with the installation of a ~ar~e-scale ~eawater ~esalina- tion plane by the Government cf the U.S. Virgin Islands, che demand has not been satisfied. U.S. GEOLOGICAL SURVEY WATER RESOURCES DIVISION ·. r. l ·, , :, our -:) ;: er cent , ·. r t he ~acer ~roducea ~3 accounted for, ~ostly ~ue ~o :osses from :eak3ge in che cistribution system installed in ;949 (Priede- Sedgwick, :nc., i 979). •)ther losses /,re ..:ue co unauthorized connections, :aultv meters, and uncontrolled public faucets (fig. J). WATER SOURCES AND USES :he principal sources and uses of water in St. Thomas are shoYn in 1:1.g. ➔• Seawater, rainfall collected from residen- tial roof-top catchments, and ground water are the main water sources in the island. Thermo- electric-power generation, pub- lic-water supply, and domestic and commercial self-supply are the principal uses. Seawater is used indirectly as the source of condenser-cool- ing water by the Virgin Islands Water and Power Authority (WAPA). The waste heat from the Island thermoelectric facility (fig. Sa) is used by the seawater-de- salination ;:ilant (fig. Sb). Desalinated water from storage tanks (fig. Sc) is distributed to the urban areas in Charlotte Amalie ( fig. Sd), by the Virgin Islands Public Works Department (VIPWD). Areas outside the ?Ublic-water supply distribution ~ystem, such as the Donoe housing project at t\ew, (fig. Se) can be classified as self- supplied ~sers. These obtain their water supply from rainfall catchments, wells, or from com- mercial water haulers (fig. Sf). ··,··., · . .'.,· .. -~ t.:ff: .... ~ :".1i.v'· ~ ·~·' . ·"--- The main urban area of Charlotte Amalie is also served bv a seawater svstem. This system supplies wa.cer for fire fighting and flushing of toilets and open drains. Areas outside the seawater system depend on "gray water" (wastewater from other household uses) as their source of water for flushing toilets or irrigation. Where aquifers yield significant water to wells (JO gal/irin or more) these are also capped as a source of water. even if saline, as feed tor reverse osmosis units or for flushing. Bottled water produced locally or imported is an important drinking water source. Bottled water costs approximate- ly $1.25 per gallon. In 1979 importation of bottled water was estimated at 1,600 gal/d (Peebles, 1979). There are no reliable figures for current imports. Publlc•W•ter Supply Production of desalinated water during the study period averaged 2.4 million gallons per day (Hgal/d). Only about 0.9 Hgal/d (38 percent) was accounted (revenues from sales) by the VIPVD. About 1.5 Hgal/d was unaccounted for as previously indicated. A recent investiga- tion shoved that leakage in the distribution system represents 30 to 40 percent of the total los ■es (CH2M -Hill Southeaat, 1983). The prod~ction of desalina- ted water for public supply increased to a peak of about 2.4 Hgal/d in 1975, declining thereafter to less than 0.6 Hgal/d in 1980. Since 1981, WAPA baa installed three n- desalination units with a total rated capacity of 3.1 Haal/d. At present only two units are being operated. Full production capacity will be required vben the East End Transmission Syst- becoaes operational (fi&• 6). This distribution syst- was constructed in 1977 but baa not been utilized. Water puaped to the seawater diatribution-ayst- averages 1.0 Mgal/d. Only about 0.35 Hgal/d of this amount ia accounted for at the public sewage treataent plant serviq Charlotte Amalie. The remainder uy be lost through leaks in the seawater-distribution syst-. Ho-ver, •:arious storm drains 1n Charlotte Amalie are continuouslv flushed to the ocean bv t~ps from the seawacer- distribution system. Discharge from two oi these taps were measured and had an average flow of 0.08 Mgal/d each. Five of these caps would account for ~ of the unaccounted flow •. The cost of potable water to WAPA rrom the desalination units is about S9.00 per thousand gallons (S9.00/kgal). This does not include amortiza- tion costs of the desalination units (Ajayi and G6111ez, 1983). The actual costs charged ,y VIPWD to consumers connected to the distribution system is $14/kgal (VIPWD personal communi- cation, l 984). Tltermoelectrlc•Power Gener•tJon Thermoelectric-Power Gene- ration is the largest single water use category in St. Thoaas. Total use was about 67 Mgal/d. This was essentially seawater, except about one percent freshwater obtained directly from the desalination plant for boiler feed. Doate•tlc Self•Supplled • R•lnfall About two-thirds of the population in St. Thomas is not served by the potable public water supply distribution syste■, and thus classified as d-stic self-supplied. Rain- water collected fro■ rooftop catchment systeaa and stored in ciatema, and withdrawals fro■ around water are the sources for d,_stic self-supply. £stimated -t•r use for this category was about 0.75 Mgal/d. Of this .-nt, 0.60 Mgal/d (80 percent) -- supplied from rainfall. This indicates that rooftop catchments are a major source of -t•r for moat private h~s especially in the more h1111id areas of the island (fig. 7). Virgin Islands law requires all dwellings, apart-nta and hotels to have a ■iniam cistern storq• of 10 gallons for each squara foot of roof area for one story buildings, aad 15 gallons for each square foot of roof aru for two or ac,re story buildings. All other buildings 3· ATLANTIC OCEAN ► C Q ........ 1ST. THOMAS! oe::t ••nv," 1 ISLANDS a: 2. Ill Cl. CD z 0 .. .. C (!) :z 1 . 2 ..., ~ are required to have ciaterns with a ■iniaum uaeable capacity of 4~ gallons per square foot of roof area except churches and warehouses, which are not required to confor■ to this standard (Jordan and Cosner, 1973). A co11parison of yields b, ,n rooftop-rainfall catch- m, at a high rainfall (Doro- th~) and at a low rainfall area (Red Hook), was -de using data from July 1983 to June 1984. The comparison was -de for a family of four using 25 gallons per capita per day (25 gpcd¾ with a roof area of 1,000 ft and an initially full cistern (10,000 gal). The faaily would have required the services of a water hauler only once if they lived in the Dorothea area, and twice if they lived in the Red Hook area. Rainfall could have supplied about 50 percent of the total water needs in the Dorothea area, but only 31 percent at Red Hook. The cost of water produced by household roof-top cistern syste■a is estiaated at $17 to SI 9 /ltgal ( CH2M Hill Southeast, 1983) • The -j or coat is associated with construction of a cistern. Oom••tlc S.lt-Supplled • Ground W•ter Ground water withdrawn for domestic self-supplied use was about 0.15 Mgal/d. Ground-water w:"•hdrawals by the Virgin I 1s Housing Authority (VIHA) w._,utimated at 0.10 Mgal/d. An additional 0.05 Maal/d was used by other do- ■tic self- supplied users. Ground water for do■estic use is available in nearly all parts of the island. There are only a few areas where yields to wells are large enough to warrant the development of public supplies. In their study, Jordan and Cosner divided the island into five ground-water areas according to their poten- tial yield and water quality (fig. 8). The potential yield ana waLer qua~icy or cneae areas are limited by excessive depth to water, seawater intrusion, waste-water contamination, and contS111ination from seawater mains. Commercial Self-Supplied Condominiums and hotels used about 2.0 Hgal/d of saline water. This is used principally for cooling, flushing toilets, and swimming pools. s-11 desalination plants produce about 0.1 Hgal/d freshwater. About 0.2 Hgal/d of the commercial water-use is ground water. This is used aoatly for flushing toilets. In SOiie areas, where the ground water is of good quality, the waste water is used for irrigation of lawns (Mahogany Run). However, moat of the commercial facilities are located near the coast and puap saline-ground water. Water haulers supplied an estimated 0.07 Hgal/d of desalin- ated water from the VIPWD sta'ndpipes to c011111ercial uaera. The average price of water delivered by water haulers is S55/kgal (Ajayi and G6aez-Gliaez, 1983). An estimated aaount of 0.05 Mgal/d was obtained fr- rooftop rainfall catclments. Public Waste·W•t•r Tr••tment There are seven public waste-water treatment facilities in St. Thomas (fig. 9). The airport plant, serving Charlotte Amalie, discharges about O. 5 Mgal/d to the ocean. Instantan- eous flow rates ■easured in June 1984 ranged from 0.16 to 1.4 Hgal/d (fig. 10), Specific conductance measurements indica- ted that about 70 percent of the effluent was seawater. The other six waste-water treatment plants serve aostly public-housing projects. These discharge about 0.20 Hgal/d to streams and the ocean. ......... .....,.. _ _..a.u. .. -.._., ............ ,,.1 .. -• __ .....,__.., ..... .......- nrpe l..._.. MU. .... .,..__, .._ .. ,rW I ... n_ a-.~ ..... . flf'l .. l..,,_,., __ ,_ .. .....,._.,._ __ I, II- ·•-'--•••• •uwu l•laill..,..... ......,, .. , •· -- t. -Ju, -.............. H•~.----1-n ", .. 11 • ..._~-~ .. ---···-·-.. FIGURE 3. Co•p•rl•OII of Ill• qu•nrll)f of •• ,., dlstrlbut•d .... ,4 ----··-••.., •••• ,,.., ,11,nln •~••11tf• Public Wort• Deoartntent. SOURCE, DISTRI, FIGURE ••• S••••t•r l•t•lr• •t U•• T11•r .. •••••trlc Po••• Pla•t •t «, ... ••r (S•b ••••J. · I F•GURE 5d. D• .. ••tlc ••d co .. ••rct•• •••r• ~• Ctar•att• A••II• ars•. EXPLANATION £l ArN urwacl ■ Plpellne lnetallad but not -■ti-1 •• ot July 11NM. □ Ar••• not ...,,ad 0 2 3 4 MILES FIGURE 8. Ar••• ••r••d bJ tb• fr•all-w•t•r dl&trlb•tlon •1•t•m. I !T FIGURE 7. A••••1.•·•••••I ral•t•II, I• lncb••· (Pr•pa••d l>J R • • C••ff-t, (#WIS) IIOAA.J -•-----.1\..-~ l I 0 B01 (C FIG - REFERENCE NO. 14 .·:. _!l, _:.'.' ·,. ( ( - - ,,. .... -... __ ...,_,o -~~ .... , .. -- -- -- ATLANT/(.' 0 C E A N _ _,,_ " .. .. --- --- ., --- --~~~e:=~~ ~~_:- :::; :.. ..... ... - --~ U o Virgin Islands ,;.._ CARIBBEAN S E A C ;5, t. of Planning and Natural Resources . ' ' :~= . :~~ i . ..., I t_astal Zone Management Program ............ of INe-, - tlnanced In pert IIIICNf Ille eo.t.l 1- ...,.._,,. Acl of 1ffl, aelrnl....._ !Ir Iha Offlce of CONtal Zone 11a1.....-11, N■llonll 0cunlc: and ~ Adffllnlll1911on. ll:'°'- r .. -·- --·· '·,.--=,a ~ \ •--~ •-~ ,ii• I.::-· -' \ COASTAL LAND AND WATER USE PLAN ■ Preservation [I Conservation Recreation. Tr.iditional Use5 0 Protection, Re5idential Low Densitv ■ Re5ider,tial. Medium Density ■ Residenr,al, High Density 0 Water Dependent & Related Commercial Marine Facilities ■ Water De~ndent & Related lndu~lrial Marine Faciliti~ II Commercial !) Industrial ~ hcluded Federal land TU -- __ .., ZONING DISTlllCTS LEGEND R-1 R-2 R-3 Low ~n,uy, lt~e-,m,11 Low ~nm ... R~1d1Pn11,1I 'v\f'd,um Den,11v Rft1den11,• R-4 '-Wd•um CH-m11v. RP\t~nh•I R-S H111:h [)en1,11v. RH1de-n11•I -'• 1 ~11:ncul1ur• 4ti-l "11r1cul1urr rrud,. f,1rm 8-1 (pn1r•I lu\tne-n 1-2 SKondM" Bul1ne-n 8-J ',ut1f'1't'd eu,•""' 8-4 8u\1n«!'\,-Rn1CH'n11,1I C 1-1 & 1-l REFERENCE NO. 15 - DATE: ~,£CT: FROM: TO: THRU: - UNITED STATE::, ENVIRONMENTAL PROTECTION Auc:NCY JAN OS 93B REGION n Preliminary Assessment and Confirmation of ~uthorization of CERCLA Removal Action Monies for the TUTU Well Site, Anna's ~etreat, Saint Thomas, u.s. Virgin Islands - ~CTION MEMORANDUM Carlos E. O'Neill ~ ~·-- [i-_ on-scene Coordinator ·-r ·-~l'"v--.) I. Stephen D. Luftig, Director Emergency and Remedial Response Division George H. zachos, Acting Chief Response and Prevention Branch I. EXECUTIVE SUMMARY On July 15, 1987, Mr. Allan Smith, Commissioner of the Department of Planning and Natural Resources (DPNR), u.s. Virgin Islands, verbally requested that the u.s. Environmental Protection Agency (EPA) provide analytical support in the sampling of one well which was reported to exhibit a strong unpleasant odor. This well is a major source of commercially provided potable water supply for the ea ■tern portion of St. Thomas. The well is located on the eastern part of the island in the Tutu Section of Anna's Retreat./ This verbal request was followed by an additional request for EPA to a ■sume the role of Lead Agency after sampling results indicated that several commercial wells were found to b~ contaminated with hazardous substances. This verbal reque ■t wa• followed by a formal request in writing by DPNR on Augu ■t 10, 1987. - In July and August of 1987, EPA confirmed by sampling and analysis, the contamination of groundwater with volatile organic compounds. A major contaminant in the groundwater is tetrachloroethy~ene (TCE). The EPA 10-Day Health Advisory Level of 175 ppb wa ■ exceeded in three (3) of twenty four (24) wells sampled, with two of the three contaminated wells being private residential wells • ./ The concentration• found ranged from 240 to 7,600 ppb with seven (7) additional well ■ being below the EPA 10-oay Health Advisory, but above the o.s. Virgin Island's interi ■ maximum permis ■ible concentration levels set on Septeab•r 1, 1987, by DPNR for volatile organic ■ in drinking water in U.• Turpentine Run Aquifer (50 ppb for a single com- pound or 1,0_ ppb for total volatile organic compounds). Three of the prntoa■ly mentioned seven well ■ were re ■idential wells. Rl!DION II FORM 1320-1 (9181) -2- This Action ~emorandum will document funding authorized for Phase I of the Tutu Well Site CERCLA Removal Action. P~ase I addresses only residences having contaminated drinking water wells with volatile orqanic compounds above levels established by the u.s.v.I.'s interim maximum permissible concentration levels for potable water. This action did not include wells where water is used prim~rily for commercial, business, industrial and/or trade purposes. It also did not include wells contaminated solely by gasoline or gasoline by-products which are not hazardous substances within the definition of section 101(14) of CERCLA. This action includes the decontam- ination and cleaning of residential cisterns contaminated by hazardous substances, the modification of plumbing, the delivery of water by tank trucks as a temporary alternate water supply, and a well water monitoring program. The total project ceilinq authorized for a 52-week period is Sl00,000 of which $40,000 is estimated for mitigation contracting, $45,000 for TAT's extramural costs1 and $15,000 for EPA's intramural costs. This memorandum will confirm your prior verbal authorization of Trust Fund monies, issued to the Chief, Incident Response and Prevention Section on September 1, 1987, to initiate the removal action at the subject site, and subaequently revised to the current project ceiling of $100,000. II. BACKGROUND A. Historical Information A request for EPA analytical support for one well in the Tutu section of st. Thomas waa made verbally on July 15, 1987 from DPNR. on July 31, 1987, a verbal request for EPA to assume the role of Lead Agency wa• made, and thi• wa• followed bv a written confirmation of the request, dated August 10, 1987 (received by the Eaergency and Remedial Reaponae Division on August 19, 1987). The initial request waa baaed on a report that one well waa reported to have a strong odor, characteris- tic of a petroleum product. This well is a major source of comaerciallyJprovided potable water for.the eaatern portion of the island. •••a•• preliainarv investiqation coa ■enced on July 21, 1987, vi•-·• field reconnaissance and sampling of this one well and six ~44itional wells identified in the immediate area. several oft~ well• are alao major water suppliers of public drinking watei'te the •••tern part of the island. TUT 002 0009 -3- Laboratory results from this survey indicated that the initial well was highly contaminated with gasoline and chlorinated organics, and the additional six wells contained elevated levels of chlorinated volatile organic compounds. ~ased on these results, DPNR declared that an imminent health threat existed, which could affect approximately 20,000 people living in St. Thomas. In addition, an indefinite number of tourists who vacation in St. Thomas were at risk since these commercial wells supply water to major hotels and restaurants. DPNR issued orders to close these seven commercial wells to protect public health. -/subsequent to this action, ~PA expanded their sampling plan due to the threat of greater contamination to drinking water wells in the area. EPA along with DPNR, identified other wells within the Tutu Water/Turpentine Run Aquifer which may be impacted by the hazardous substances identified to be pres- ent in the groundwater. A second round of groundwater well sampling took place on August 10 and 11, 1987, which included a total of twenty-four (24) wells identified in the Tutu Section of Anna's Retreat. All twenty-four wells were sampled and analyzed for volatile organic compounds. Following these results, DPNR closed the five private wells whic~ service two three-family homes and one apartment building housing twelve studio uni ts. B. Site Setting/Description The contaminated wells are located in the TUtu Section of Anna's Retreat, st. Thomas, u.s. Virgin Islands. The five (5) private wells recently ordered closed are located in the Tutu residential area. At the present time, the affected area is not serviced by any public water supply. EPA sampled a total of twenty-tour (24) wells in the Tutu area and found five private wells and eight (8) commercial wells seriously contaminated with up to 7,600 ppb of PCE. (See map attached). c. Quantity and Type of substance Present EPA sampled &.1}41 a_nalyzed for suspected volatile organic com- pounds on J~i22 and August 10, 1987. Listed below are the maximum concellbationa of the hazardous substances identified in the drinkin9 water wells: TUT UC'.? OOJ.O contaminant Tetrachloroethylene Trichloroethylene Benzene -4- Maximum Concentration Found (ppb) 7,600 61 1,400 Statutory Source of Hazardous Substances under CERCLA Clean Water Act Section 307(a) Clean Water Act Section 307(a) Clean Water Act Section 307(a) The results of the sampling are contained in Tables I and II. PCE contamination ranged from non-detectable to seven thousand- six hundred parts per billion (7,600 ppb). Sampling results adequately document 3 wells with contamination above EPA's 175 ppb PCE 10-oay Health Advisory Level and eight (8) wells above the DPNR's interim standards for maximum contaminant levels of volatile organic compounds in drinking water. III. THREAT A. Threat of Public Exposure Direct contact with PCE may cause eye and-nose irritation along with dry scaly and fissured dermatitis. Acute exposure through absorption, inhalation or ingestion, may cause central nervous system depression, hepatic injury and anesthetic death. PCE has been found to be carcinogenic. This is a case of actual contamination in exceas of the EPA 175 ppb PCE 10-Day Health Advisory Level for a three-family house and one apartment building houaing twelve studio units. In the other three faaily apartment dwellings, the well con- tamination exceeded the interim DPNR drinking water standard of SO ppb for any single volatile organic constituent. In addition to the exposure via consumption of the water, or eating food prepared ~ith this water, showering with water contaminated- with volatile organics can conta ■inate the air to significant1~ unhealthy levels. 1Ul 002 0011 -s- The location, direction and dimensions of the plume are af- fected by variations in water table depth, rate of puMping of the wells, duration and intensity of rainfall, and inter- mittent releas•s of chemicals from one or more sources, all of which are unknown at this time. Given the above variables which affect contaminant strengths in any well within the plume may vary randomly. On September 2, 1987, DPNR issued three (3) orders to close wells and issued two (2) advisory letters to homeowners not to use well water for drinking, bathing and washing. B. Evidence of Extent of Release Investigation, sampling and analyses by EPA have identified contaminated groundwater, as described above, and containing contaminates, as described in Tables I and II. c. Previous Actions to Abate Threat No mitigative action was taken by any Potentially Responsible Party prior to EPA's recent activities. o. Current Actions to Abate Threat JEPA has commenced an investigation of the TUtu water/Turpentine Run Aquifer by establishing a cooperative agreement with the u.s. Geologic Survey to define the characteristic• of this aquifer and to determine the extent of contamination. EPA and DPNR have also completed Aquifer and a monthly well aonitoring program is being developed • .J DPNR has issued a total of ten (10) orders/advisories to well owners to close sixteen (16) wells. A local dry-cleaner ha ■ been identified as using and storing PCE. Handling, storage and disposal practices fro ■ this facility are unknown at this tiae. DPHR ha ■ propoaed to issue an advisory to local dry cleaning establishments instructing the ■ to properly store and hold all waste for proper di ■po ■al by an indu ■trial va•t• hauler. IDPHR with the a ■■istance of EPA is conducting•• •••••••ent of at least nine (9) facilities identified to N· potential sources of hazardous waste and/or substance r•l••••• in the Tutu area. --· -6- has cleaned the homeowner's cisterns that have been conta~- inated by hazardous substances from the groundwater, modified the existing home plumbing to terminate well connections, and intends to continue to deliver clean wat~r via tank trucks on a regular basis, and establish a surveillance program for all wells in the area by a monthly groundwater monitoring program. This Phase I, short-term removal action will mitigate the threat to public health by providing a te~porary alternate source of water for affected consumers. IV. ENFORCEMENT The contaminant plume is generally believed by both OPNR and EPA, to ·have its source from past and present improper handling and disposal practices of organic solvents, po ■■ibly from dry cleaners and auto repair shops operating in the area. This site has been referred to the Site Compliance Branch for enforcement action. An attorney and enforcement project officer have been assigned to this case. EPA issued Request for Information letters to all Potentially Responsible Parties. v. PROPOSED PROJECT Ao Objective of the Phase I Removal Action The primary objective of the Phase I of ehe reaoval action is the mitigation of the threat to public health by providing a safe potable water supply to the affected residences. Two three-family homes and one apartment co ■plex housing twelve studio units were identified as being dependent on groundwater from their own private wells. Their respective wells were ordered closed-down by DPHR for exceeding interim drinking water standards. To reach the objective of providing a safe interim drinking water supply and protect the health of the public at risk, the following reaoval action was initiated. Water storage cisterns, which receiYed contaainated groundwater fro■ affected wells, were cleaned and sanitized. Cisterns were filled with clean, safe, driJIJl&a9 water. Water tank trucks froa local water haul- ers will b•_/providing water for the affected cisterns on a reg- ular basis. Pluabing modification was made to disconnect water linea from the contaminated wells which provide groundwater to the cisterns. ')l; -7- An attempt to connect well water directly to toilets for flush- ing will be made, if physically and economically feasible. A well surveillance program will be implemented involving all the wells in the Turpentine Run Aquifer, thru monthly sampling and monitoring. The longer term, Phase II objectiv~ will require the provision of a permanent alternate water supply in lieu of the temporary trucking of water to the threatened consumers within the plume area. Upon completion of an analysis of the alternatives for permanent water supply to these residences, a recommendation will be made for Phase II. B. Project Estimated Costs Water consumption per person per day on the average is thirty (30) gallons. It is estimated that the one apartment building ,~ has twelve studio units with the average of two people per unit. The two other private homes are three-family dwellings with the average of ten people in each. The cisterns in the three family houses are small and, therefore, a supply of water must be deliv- ered every two or three weeks, respectively. The delivery period is currently estimated to be one year or when a permanent alter- nate water supply can be provided, whichever occurs first. PROJECT COST (PHASE I) Cisterns Clean-Up: Provide labor, material and equipment including one vacuu ■ truck, pressure water spray guns, water tank truck, etc., to drain and dispose contaminated water and to clean and sanitize identified cisterns ••••••• $13,000 Modification of plumbing including Labor and Materials••••••••••••••••••••••••••••• $ 5,035 Refill ci ■tern ■ with clean and safe drinking water••••••••••••••••••••••••••••••••••••••••••• $ 2,665 Provide •~•tern ■ with clean and safe drinking water on re9ular basis according to a pre- approved ■chedule••••••••••••••••••••••••••••••• $15,000 contingency (101) ••••••••••••••••••••••••••••••• $ 4,300 Total Mitigation Cost••••••••••••••••• $40,000 TUT 002 0014 -8- Extramural TAT Cost TAT Monitoring and sampling program (Including travel and per niem) ••••••••••••••••• $35,000 TAT Technical and administrative sup po r t ( i n c 1 u di n g tr ave 1 and per di em ) • • • • • • • • • S 1 0 , 0 0 0 Total TAT Cost Intramural EPA Cost $45,000 (Including travel and per diem>••••••••••••••••••SlS,000 ESTIMATED TOTAL PROJECT COST••••••••••$100,000 This figure represents the estimated total for Phase I. It could be reduced significantly, if a reliable and permanent alternate water supply is found sooner than the proposed 52-weeks delivery period; might be increased, depending upon the identification of new drinking water wells found to be contaminated with hazardous substances within the affected area. c. Project Schedule Project initiation of cistern clean-up and safe water de- livery has already been implemented based on verbal funding authorization. Safe water delivery period is currently estimated not to exceed one year or when a permanent alternate water supply can be provided, whichever occurs first. V. RECOMMENDATIONS Condition• at the Tutu Well Site meet the require ■ents of section 300.65 of the National contingency Plan (NCP) for a CERCLA/SARA re ■oval action. EPA has determined that there is a threat to public health at the site (Section 300.65(b)(1). This deteraination va ■ based on: 1) Ru-• exposure to unacceptably high levels of acutely toaic ■ub ■tancss (Section 300.6S(b) (2)(i), and 2) co ■ta ■ination of drinking water supply (Section 300.65 (b)(2)(ii). TUT (:),J::: OU 1 ~~; -9- The resident population at risk currently relies on orivate well water as their source of potable water. This removal action complies with Section 104(b)(2) of CERCLA, as amended by SARA, in that it is consistent with the efficient performance of long-term remedial measures, by providing an interim supplv of potable watP.r to the public until a permanent water supply can be secured. This is a written confirmation of the initial and revised verbal approval of up to $100,000 for the total project ceiling estab- lished on September l, 1987, by the Director of the Emerqency and Remedial Response Division to the osc for the CERCLA removal action at the Tutu Well Site. The mitiqation contracting ceil- ing is estimated at $40,000, with an additional $45,000 for TAT costs, and S15,000 for EPA costs. Your authority to authorize these funds is pursuant to Deputy Administrator Alvin Alm's memorandum of oeleqation Number 14-lA dated April 15, 1984, and Richard Dewling's Redelegation Order R-11-1200.6 of August 29; 1984. r- . ., ' / .J APPROVAL: ~!::(_ !) · {_e,,rtJ~ ----~----------i--,-- DATE: I ,. DISAPPROVAL: DATE: cc: (after approval is obtained) c. Daggett, 2RA J. Marshall, 20EP R. Salkie, 2ERR-DD P. Gelabert, 2CPO s. Luftig, 2ERR R. Gherardi, 20PM-PIR G. zacho•, 2ERR-RP T. Sullivan, Pl(-214P ( EXPRESS a. Sprague, 2ERR-RP T. Fields, WR-5488 J. Czapor, 2ERRD-SC P. McJtechnie, 2IG G. Pavlou, 2ERRD-HYCRA -~f .. TUT OU MAIL) • ,, r 1 PHOTCVAC llMPLIMG RESULTS TUTU IILL IITI IT, THOMAS, U.S. VIICII lit.AIDS IANPLI IANPLI DATE OATI LOCATJOI IVIID IANPt.10 IIIL!IID IOVICE Ill Tel PCI !01, Da GCIIS ........ -·•1t■-ii --··· •••••••• •••••• ••• .. . ••• ... • •••••• WtHJIAI C'IDIH 17•473 07/22117 07/30/17 II 0 ' 102 I 0 • ,. HAltKNlM llkllf 17-474 07/22/17 07/30/1711 0 0 t I 0 .,. 4 IIIDS IIW 1 17-475 07/22117 07/30/17 Cl ' 11 14 I 0 • ,. 4 111101 IEWl ., .. ,. 07/21/17 07/30/17 Cl ·7 11 11 ' 0 • ,. tlW! 17-47'1 0?/22/11 t7/I0/17 Cl ,,, II 100 41 31 ,T, YJJIA 17-471 07/12/17 07/30/17 II 11 ' ,, • 0 .,. IGUI 17-471 07/11/17 07/10/17 Cl I 11 II I 0 .,. tlWt 17-410 07/22/17 07/30/17 Cl 1110 7111040 411 327 .,. PIILD IL&ll 17-411 07/11/17 07/30/17 ll 0 0 0 I 0 .,. • • • • , .. ·•·· ;·. ' TABLI I -- TUT (1: ,_ 00.1./ ,,. IELL SAMPLING l!SULTS TUTU l!LL IITI IT. THOUS, U.I. VIIGII IIUIIDI IUPLI DITI DITI ... !. 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DltCGI fl 01'1 11/10/17 11/13/17 Cl 0 • • • 0 ., • DDI 1141 11/10/17 11/13/17 II 0 • • • 0 ., • Dlllftl 1111 11/10/17 11/13/17 Cl • • I • 0 ., • • YIN& IILL IS 0111 11/11/17 01/IJ/ff JI 0 • • • ' ., . fJHl IILL 11 0111 11/11/17 11/11/17 II • I 11 I 11 .,. uun .. , 11/10/17 01/12/17 II • I ' I l •'• ,IIIL 1111 01/11/17 01/11/11 II • ■ 171 • 11 ., • -.nn .,., 11/10/17 11/13/17 N • II 7111 I H .t. amu IIU 11/10/17 11/11117 II • ' •• 1 I•'• PIAIICOII 1141 11/10/17 11/11/11 N ;. II Ill • 141 .,. DUCH ... 11/10/17 01/13/ff ti • • • • . ., . flu.IT 11u· 01/10/17 01/11/11 Cl. 1111 • 141 II 170 .,. !lLl.nDQf 1171 11/10/17 11/13/fl Cl , ... ·II UI Ii ,n .,. rim 1LU1 •••• 11/11117 11/13/ff II • • • • I .t . • J • TABLI II ~ . Nap: , . Bryans l2-) 7. Mathias t,.) 1 J. L Rodr 1guez (,) 8. S■i th \1) 14. J. Harth ■anU) 9. Francoisl•) 15. I. Eglin (.3) 10. TU let L•) 16. L Harvey l•) 11. Ramsey \.! '\ 17. Ii, ~t••l• (.1) 12, 4 Winds 11\.~)18. VIHA ~2-) 19. Lockhart, ... .,..--.: Leonard ") _,...,-,:ta.~J .. Demi tr 1 ~) =,t•\:~.~'i Dench ~) ':~~-lfl · Devcon ~ ) ~N .. 11:I> Oed■ \l) P-.~ ••• . '' ,, ' ' '' ' ' .._.. () IIUM~tA. cf Nt\\s••.::•: I I 11 I I I 11, \\\\I,-.._, \ \ \'- '....___.,. ,' ,,,.,, ,-. \ ____ ,, REFERENCE NO. 16 r - l i I I - ' U. s. Geological Survey Water Resources Division Caribbean District Open - File Report A SURVEY OF THE WATER RESOURCES OF ST. THOMAS, VIRGIN ISLANDS _,, ,- UNITED STATES DEPARTMENT OF THE INTERIO~ r1..t 1 ,:;)':: uu:.·.t IN COOPERATION WITH THE GOVERNMENT OF THE VIRGIN ISLANDS OF THE UNITED STATES - - ABSTRACT St. Thomas, with an area of 32 square miles, 1s the second large st of the Virgin Islands of the United States. The island is mountainous, and slopes commonly exceed 35 degrees along a central ridge 800 to l, 200 feet high running the length of the island. The general appearance is a panorama of numerous steep interstream spurs and rounded peaks. The island is made up of rocks of Cretaceous age, mostly volcanic flows and breccias. A thin limestone and tuffaceous wacke complete the sequence of major rock types. All the rocks have been tilted and dip about 50 degrees north. Water in Charlotte Amalie, the capital, is supplied by sea-water desalting and water barged from Puerto Rico and is augmented by hillside rain catchments and individual roof catch- ments. Rainwater augmented by water hauling and a few wells is the source of water for the rural areas. Streamflow is meager--2 to 8 percent of the annual rainfall-- and is .>redominantly stonn runoff. Runoff after rainstorms seldom exceeds 5 percent of the rainfall. Runoff is rapid, however, and flash floods occasionally occur. Test drilling has shown that water can be obtained from fractured volcanic rocks in nearly all parts of the island. Wells will yield, generally, less than 1,000 gpd ( gallons per day). In the upper Turpentine Run Valley and the Lovenlund Valley, short- term yields of individual wells are as great as 100 gallons per minute. Estimates of potential yield from these areas are 300,000 and 100,000 gpd, respectively. 'I'wo smaller areas--Long Bay and Lindberg S.y on the outskirts of Charlotte Amalie have estimated ground~···.·. yields of 70,000 and 30,000 gpd, respective!~. Fully develo .· e surface- and ground-water resources of the island could "'· · · ·,. 3 million ga lions of water per day. -,a;~ • .,.·_ .' - Ground water is slightly saline, commonly containing more than 1,000 milligrams per liter dissolved solids. The principal source of the minerals is bulk fallout of sea- and land:..cierived dust from the atmosphere. Solution of minerals from the rocks of the aquifers is the second largest contributor. Nitrate and some of the bicarbonate content of the water is probably derived from vegetation and animal and human wastes. Surface water is similar in minentl content to ground water during base flow • ·,;., - - UNITED STATES DEPARTMENT OF THE INTERIOR Geological Survey Caribbean District Open-File Report A SURVEY OF THE WATER RESOURCES OF ~> -~\. ~' ST. THOMAS, VIRGIN ISLANDS by D. G. Jordan and O. J. Cosner Prepared in cooperation with the Government of the Virgin Islands of the United States 1973 T\. __ 1··r ;102 - A SURVEY OF THE WATER RESOURCES OF ST. THOMAS, VIRGIN ISLANDS by D. G. Jordan and O. J. Cosner LOCATION AND GENERAL SE'ITING Location The Virgin Islands, forming part of the Antilles Island Arch separating the Canbbean Sea from the Atlantic Ocean, are about 1,400 miles southeast of New York and almost 1,000 miles east southeast of Miami. St. Thomas, the northwesternmost island, lies about SO mlles east of Puerto Rico A TL ANTIC (fig. 1). St. Thomas is the second largest of the more than SO islands and cays constituting the Virgin Islands of the United States. The island is approximately 14 miles long and 2 to 3 miles wide and has an area of 32 square miles. Lying within a few miles of the coast are nearly 40 smaller islands, ranging 1n area from slightly less than a square mile to a few hundred square feet. OCEAN .~ l, .. ,o- , .. _ "•·· I .... ~o ~ P::I ,.,. ♦'-. 1 re•Tel.• ,.,. ... 1 PUERTO RIC 0 , ..... ~ o•••~• ~ - ~~ ~oe&· I ,,,,..tj " - 7 CAR188£AN SE A I 10 N •• .. • .._. .... .. .. _ -11•10· ... ., •••oo· ···- ·-· ·••10 ! Figure 1.--Location of the Virgin Islands of the United States. l T\_i .. \ 002 - Population St. Thomas has about 17,000 pennanent resi- dents and a transient population of tounst and im- ported laborers of about 8,000. T:ie majority of the population is urban--about 20,000 people live 1n Charlotte Amalle, the only city and also the seat of government of the Virgin Islands. The permanent populauon is increasing rapidly and is expected to double by 1980 ( unpublished data, 'I.I. Planning Board, 1964). Topography The land surface is almost enurely sloping and extends seaward from a central ridge. 800 to 1,200 feet high, running the length of the island. The slopes, which commonly exceed 35 degrees, are dissected by numerous stream courses of steep ~radient. The general appearance is a panorama of steep interstream spurs and rounded peaks. Flat land is confined to the Charlotte Amalie area and a few small alluvial-filled embayments. The only variation in the general topography is in the upper valley of Turpentine Run in eastern St. Thomas. The valley has relauvely gentle topography consisting of rolling hills in a basin surrounded by steep slopes and sharp ridges. Land Cover and Use At one time almost all the land, including that characterized by steep slopes, was under cultiva- tion, prunanly for grazing or growing sugarcane or cotton. Agriculture, however, has declined almost to extinction. A few square miles of land are still devoted to grazing in the eastern part of the island, and about 10 acres are used for truck gardening in the north central part. The remainder has been all01Ned to revert to brush and secondary forest. Now, land us. ta.ollenging rapidly, much of it brought on by the ...... and its rapid mass trans- portauon. Incree-_population, in part caused by development of-'·t1Jand as a retirement haven and by tourism. reidlta ift more land being used for urban and suburban development. The increase in population not only makes new demands upon the water supply, but also the changes in lacv:i use could very well affect the available quantity and quality of the water resources. 2 Climate The average annual rainfall is about 45 inches and the average temperature is only 80 ° F, but the prevailing 1mpress1on of the climate is one of dryness, especially in the winter. nus is espe- cially true of the ea st end of the island, where, because of orographic effects. rainfall is only about 80 percent of that elsewhere. Rain is seasonal, nearly half falling between August and November. February and March are the dnest months and September and October the wettest. Most of the rain occurs as short, intense showers lasting but a few minutes. Rains exceeding 1 inch, with accompanying overcast, cloudy skies, come but six or seven times a year. Thus. there are few days when the sun does not shine. Although major rains are rare, their volume is noteworthy. The greatest rainfall of record was 18,0 inches September 13-14, 1928, during a hurricane. The last great rain in recent years was 10. 6 inches May 8. 1960, the result of a stationary tropical depression. 'nle island lies in the path of hurricanes and occasionally receives heavy rains and high winds from pa Hing storms. The incidence of direct hits is low--damaging stonns having a frequency of about one every 33 years. The last humcane to cause extensive damage was in September 1928. The direct rays of the sun are very hot, but air temperature is modified by the almost constant trade wind. Air temperature ( table 1) ranges from a mean law of 72. o• F in February to a mean high of 87 .8°F l.n August. The highest daily temper- ature of record was 95° F and the low, 63° F. The prevailing wind direction is from the east. Northeast and southeast winds are relatively common, but west winds are rare. Monthly average wind velocity during 1953-58 at Harry S. Truman Airport 1s given in table 1. A wind rose for the same period is shown in figure 2. Relative humidity is high owing to the proxunity of the sea. At Harry S. Truman Airport during 1953-58 relative humidity was highest, averaging 81 percent1in the early morning hours, and lowest, averaging 66 percent, in the early afternoon. Average daily humidity is given in table 1 • I !.IT ,_;t 1.,'';_:\ ' ., ,, I ._ ( ,.f -~ ,j' , ' .: . ( .Al TL.ANTIC ~ AIRPORT OCEAN ( Gromllc rock1 CARIBBEAN SEA 0 2 J Milo •••u· Geoloor oenerolued ofter T w Donnelly, 1960 ( '·. ( EXPLANATION ALLUVIUM - Silt, clal, and thin, discontinuous beds of sand and gravel. Includes beach sand. Estimated maximum thickness 50 ft. TUTU FORMATION - Tuffaceous conglomeratic mix lure derived from older rocks. Contains some limestone, especially near the top. Maximum thickness greater than 6,000 ft. OUTER BRASS LIMESTONE- Thin-bedded siliceous limestone and a few thin beds of tuff. Estimated maximum thickness 600 ft. LOUISENHOJ FORMATION-Water-laid luff, brecc1a 1 and a few thin beds of limestone Maximum thickness known 13,000 ft WATER ISL AND FORMATION-Lava flows, flow brecc1a 1 and water -laid tuft intruded by dikes and plugs. Maximum thickness greater than 15,000 ft. Contact Inferred fault, dotted where concealed Figure 3.--Geology of St. Thomas. ( - -- Geology The general geology of St. Thomas ( fig. 3 l has been studied for many years, but only recently :1ave the geologic fonnations been named and descnbed 1n detail (Donnelly, 1960, 196 6 l. 7he :'lames of geologic formations used m this report are after Donnelly. The names have not been adopted by the U.S. Geological Survey. The volcanic and sedimentary rocks of St. Thomas are of Cretaceous rand older?) age. The oldest rocks, those of the Water rs land Formation of Donnelly ( 1960) are predominantly lava flows and flow breccias deposited at great depth on the sea floor. Uplift and subareal erosion followed deposition. The Louuenhoj Fonnation overlying the Water Island formation was extruded from a volcanic center probably sited in what is now Pillsbury Sound between St. Thomas and St. John. Near the presumed location of the volcaruc onfice the rocks are mostly very coarse reworked cone debns. Farther from the orifice, coarse material lessens and tuffs predominate. Near the base of the Louisenhoj Formation is a conglomerate composed chiefly of rock from the Water Island Fonnation. The Outer Brass Limestone was deposited on the flanks of the Louisenhoj volcanic cone during a period of volcanic quiescence. It consists of 200 to 600 feet of thin-bedded graph1tic sil1c1fied radiolanan limestone and a small amount of included tuffaceous matenal. The Tutu Formation, the youngest rock exposed on St. Thomas proper, 1s composed almost entirely of angular debris denved from the Louisenhoj Formation and minor limestone debris from thin limestone deposited contemporaneously with the Tutu formation. The rocks were subsequently tilted to fonn a northward-dipping h011ocllne. Dips range from 15 to 90 degrees and •~~ about 50 degrees. Locally the forma~_•nt overturned • ...: ·, . ., ,.,. •4i The penneabl• •• that theae rocks once may have had after depoaitlon have been destroyed by metamorphism or by deposition of minerals in pore spaces. Ground-water movement is now limited to openings along joints and fault zones. The homoclinal structure 1s cut by sets of faults trend- ing N 45°W, N 55° E and north. Three well- defined Joint sets parallel each of the major fault 6 directions. The valleys of the island have s1m1lar trends and are apparently the result of selective erosion of rock weakened by faulting and Jointing. Prune zones of ground-water availability, therefore, follow the valleys. Small alluvial deposits ranging from Pleistocene (?) to Holocene 1n age lie m the valley of Turpentine Run 1n east-central St. Thomas and the larger coastal embayments. The alluvium of Turpentine Run hes in a narrow band seldom more than 200 feet in width along the stream. Maximum thickness of the alluvium is about 40 feet. Most of this alluvium, which is composed of silt, fine sand, and clay and contains discontinuous beds of sand and gravel 2 to 3 feet thick, lies in the Mt. Zion-Tutu area of the upper basin and in the narrow valley from Manendal to Mangrove Lagoon in the lower basin. The alluvium extends out under the lagoon near the mouth of Turpentine Run. Although composed pre- dominately of fine-grained material. the alluvium readily infiltratee streamflow when the grou.i,d- water level is below the base of the stream. As such, the alluvium fonns a readily rechargeable aquifer, although it is of small extent and yield. Some coastal embayments headed by mterma- tant streams contain small deposits of alluvium similar to that of Turpentine Run. Maximum thickness of theae deposits IS estunated to be 50 feet, and their areal extent seldom is greater than a few acres ( an exception being the Long Bay and Airport areas near Charlotte Amalie). Near the sea, the alluvium 1nterfingers with calcareous sand and at times contains lenses of mangrove- swamp deposits. Therefore, the deposits are of minor s1gruf1cance as sources of water. OCCURRENCE AND MOVEMENT OF WATER Water mover. through a cyclic pattern--the hydrologic cycle--in wtuch there are three storage areas: the sea, the land, and the atmosphere. On the land, surface water and ground water depend on: ( 1) the amount, intensity, and areal extent of the rainstonns; ( 2 l the slope of the land; ( 3) the moisture content of the soil and vegetal cover: ( 4) the infiltration ca pac I ty of the soil and underlying rocks; and ( 5) the size. T LJT - - number, and interconnecuon of openings Ln the aquifer. Ramiall '<a1n 1s the only natural source of fresn water :o replenish the water resources oi the island. ?ainfall is seasonal. ·::1th the rainy season Ln !ate summer and early iall and a secondary wet season usually in May. ::early nalf the rain falls junng August-November ( fig. -I l • Ra ins exceed- :ng l tnch 1n 24 hours come six or seven times a year. Four to 15 inches of rain falls in a -18-hour period about once every 2 ·1ears 1n large storms. T!-iese rains can occur 1n any month but are more likely during the nurricane season ! August- >:ovemberl. About half the time annual rainfall LS between 40 and 5 0 inches ( i1c;. 5) . Less than 10 percent of the time annual rainfall 1s less than 35 :nches. ·Nh1ch usually means a major deficiency during the normal wet season and drought. The cumulauve departure from average and the IO-year running average of rainfall shown m figure 6 shows that at this time of wnting ( 1967) the island may be entenng a period of deficient rain- fall. With the excepuon of a few years m the late 1940's and early 1950's, rainfall in the past 30 years has been below average. There has been a long-term decline of about 10 inches 1n annual rainfall since the peak of the surplus rainfall period in the early 1930 's. The most severe droug nts of record occurred 1n 1964 and l 967 . when but 27 and 24 inches of ram fell, respec- tively. :.real distnbution of long-term rainfall, shown in figure 7 ( see letter "a"). 1s controlled by topo- graphy and the prevailing easterly to northeasterly winds. However, 1ndiv1dual storms may or may not show the effects 0f orographic control or pre- •✓a1ling winds and the areal d1str1bution of the storms can be very i1TI1gular ( fig. 7--Letters "b" to "f ") • 'I Ci--1sture -J.'~' The soil zone over most of St. Thomas 1s not more than 1 foot thick. Where of sufficient thick- ness 1t has, however, the unique property cf absorbing large volumes of water--as much as 12 inches 1n 24 hours (R. Scott, SCS, oral commun .. 8 1963 l. E..xam1nat1on ot the soil zone wnen or; shows it to be coarsely ~ranuiar. cw inc; :o c l-..mp- 1ng of clay and slit particles. Frolcnc;eo satura- tion 1s necessary oeiore the s.,:ranules oreak down. As a result. ~:-:e sot! r:a s a r:1-,h per:;.ea:::itl1ty :.rnt1l well saturated. but, once saturated, : t :::iecomes poorly permeable and retains ·.vater 1n tr:e pore spaces between particles and reiects an·,, excess. < :::iservat1cr.s cur1r.~ rainstorms 1r:d1cate t::.at the typical sol! z.one wlll aosoro aoout 2 incnes of water before some water is rejected er ;r,.oves to tne underlying oedrock. f"-..1lly s.:ituratea, t:-:e soil will prooably retain 3 :nches ot ·N.:itcr per tcot oi depth. T?-:e capacity of the soil to hold l.:irge volu:nes of water, together with infrequent r:-:.:iior rainstorms and a high evapocransp1rauon rate, seriously reduces ,irouna-water recharge and storm runoii. Evapotrans p1rat1on ~ost of the water crapped 1n the soil zone returns to the atmosphere by evaporation or tran- sp1rat1on by plants ( evapotransp1rat1on). On St. Thomas this process is active throughout the year, and 90 to 95 percent of the rainfall is returned to the atmosphere. The tendecy of the soil to gra nu- late 1s also conducive to evaporation. .~s water 1s evaporated from the surface cf a saturated tight soil, the sod again becomes granular and exposes the soil at depth to the circulation of a 1r. Con- sequently, further rapid evaporation of sod moisture results. Transpiration is a major means of water loss from the sod zone and also from the upper part of the aquifer, 1f the water table 1s near the land surface. Grasses and shallow-rooted plants can transpire water only from the upper few feet of the soil zone, but many kinds of trees, such as deep- rooted false tamarind, transpire water from depths of more than 20 feet. The effects of evapotransp1rat1on may be seen 1n the channel of Bonne Resolution Gut below the gaging station. The gut flows 1n a predominantly bedrock channel a few feet wide for about l, 500 feet before reaching the alluv1ated embayment ,H Dorothea Bay. Base flow of the stream. 'Nhen less than 10,000 gpd (gallons per day), disappears 1n this reach. The loss is attributed principally to transpiration by the dense growth of brush and IU i ()() :,/ ( (al avera e annual (bl Morch 25-26 1963 -! k) April 7-8 1963 ,_.·.; ( (dl Mo 9-13 1963 (t) Au ust 28-29 1963 0 I 2 J 4 SMILES ICAU ,oa ALL MA,s (f) December 10-13 1965 Figure 7 .--laohyetala in inchea of the long-term distr1buUon of rainfall (a) and of individual rainatonn s ( b-f) on St. Thomas. ( - - trees bordering the stream. from tne a ppeara nee :::f the vegetation in a dry penod, only the vegeta- tion in a stnp about 100 feet wide with a total area Jf about 3 acres benefits from the stream. ;.., :n1nimum water loss of 10,000 gpd, 3. 6 million ;allons annuallv, would indicate ;in evaootranspi- ration rate of 1.: :;illhon ;;allons cer acre ;Jer year, Jr -l-l incnes. Bowden ( 1968 \ computed monthly potential evaporauon and s01l-mo1sture deficiency at six stations on St. Croix using the method devised by ::; . ·.v. Thornthwa 1te. Potential evaporation ranged from 58 to 69 inches and averaged 62 inches per ·1ear. Actual eva potransp1rat1on ( den ved from potential evapotranspirat1on and change 10 soil moisture) ranged from 41 to 46 inches and averaged 43 inches per year. Bowden•s data shows a sod- :no1sture deficiency 9 to 11 months of the year at the different stations. Surplus sod moisture ,:iccurred only 1n the months oi Septemoer to :-lovember. The authors believe that conditions are similar in St. Thomas. Streamflow The S to 10 percent of rainfall not returned to the atmosphere by evapotranspirauon from the soil zone either recharges the ground-water reservoir or runs off to the sea. Annual runoff in a time of average rainfall ranges from about 2 to 8 percent of the rainfall. Most stream channels on St. Thomas are dry iind carry only stonn runoff. Only two streams on !he island have perennial reaches. In these reaches, about one-half to three-fourths of the flO'N 1s stonn runoff, and the remainder is base flow I ground- water outflO'N to the streams l. From O. S to 2 inches of water annually reaches the sea as stonn runoff. The dmount of storm run- off vanes from basin to ba•1n, depending upon topography, soil m----, exposure, and vegeta- tion. Base flow --m• with perennial reaches. wlii le vf~' l in volume to storm run- off, seldom reac~..... The flO'N usually 1nflltrates into all~posits i.n the lower reaches of the stream■: Ground Water From O. 5 1ncn to as much as 5 inches of the 10 rainfall annually infiltrates tr.e s0:l ~nd rocKs to reach the ground-water reservoir. ·::ater 1n the grouno-water reservoir or aquiier moves ov gravity toward the sea. ',\'here the water taole is intercepted by the land si...riace, ·.vater :s dLs- charged as a spring or as ::ase rlow t-:: 3 stream. '.\'here it :s r,ear the lane surface. si...cn as along stream cnannels and 10 coastal ~moayrr:ents. large volumes of water are transoired :iy plants whose roots tap the ground-water reservoir. The transp1rat1on by plants d1rectlv :ror:: ::-:e water ,a:ile 1s so great that only :::mute qu.:int1t1es of 1round water ever reach tne sea, -.'ttner .35 stream- flow or as seepage dtrectl',' ,:-.rout;n t:ie sod .:ind rocks. i'resh- Salt-Water :r:terfoce rresh water :n the aquli~rs ;,lor.u ,:-i.e -:oust ,s ,n contact ·.v1th salt water 1n a c:·✓nar.'.:s 0"1stem. So long as water levels gracie seawara, fresh water w Ill discharge to the sea at t".e shore. Dunng times of ground-water recharge, the fresh- water lens th1ckens, displacing the underlying, heavier, salt water d01Nnward and seaward. Dur- ing times of no recharge, the fresh-water lens thins, as ground water discharges to sea. Salt' water, which moves into the normally fresh zone :f water during times of no recharge, 1s not entirely flushed out by fresh water when rechilfge occurs. Some remains behind, where Lt mixes with 1nfluxing fresh water. The interface zone of brackish water 1s thick where fluctuations 10 the size of the fresh-water lens are large. In some coastal areas, where the fresh-water lens 1s thin because of lack of rainfall or unfavor- able topographic or geologic factors, the under- lying 10terface zone may extend inland several hundred feet at depths of but a few feet below the water table. The balance between salt water and fresn ·nater in coastal aquifers 1s dellcute and cun easll·1 be disrupted by man's quest for water. Salt-water encroachment can readily result by remov 1ng more water from the fresh-water lens than 1s being replaced by recharge or by pumping a well at Jn excessive rate, 1n which case the fresh-water head 1s lowered, and movement of salt water upward or honzontally into the fresh-water zone 1s induced. ru1· () (_) :.i~'. Ot) S l - - ·.v ATER SC l'RC ES F"resn water has always been 1n cr:tical supply :n St. Thomas. Rain collected on roofs and stored 1n cisterns 1s still the source of ·nater fer :nost rural and ..:r::ian domestic supplies. ~efore 1960 :ulls1de rain catchments and a iew dug wells ·.vere the ma1or source of ·:,ater for ou::illc s..:cpi1es. Since then, c!esalteci water nas oecorr,e tr.e l:lajor source of 'Nater for pui.Jl1c supplies, Jnd water :::arged from Puerto Rico :s a close seconc. Char-lottt: ~:nahe Charlotte Amalle nas a dual public ·.vater system. Fresh water 1s used for drinking and general house- hold needs, and salt water 1s used for sarntar.1 and :ire-control purposes. The fresh-water sucply, octained from salt-water distillation plants, rall- s1de ram catchments, and a well, is supplemented by water barged from Puerto Rico. Potable water use and the sources of the water 1n figure 8 not only show the increasing demand for water but also the shift in sources of the water. In the late 1950's, with the exception of 1957, a drought year, catchments were the major source of water. Barged water became the major source of supplv 1n the early 1960's, but by the late 1960's, desalted water became the pnncipa l source of supply. :--I early all buildinas, both pnvate and public, 1n Ch.3rlotte Amalle have roof catchments and cisterns. In 1926, before the establishment of a public water system, about 200 pnvate and 17 public dug wells were in use 1n the urban area. Since then most of the wells have been abandoned because of sewage and salt-water contamrn.::iuor.. Some of the salty water was drawn mto the wells from the sea as a result of overpumping, and some of 1t entered the wells from leaky salt-water pipes. -~ few of the wells are still pumped occas1onally for nondnnking domestic supplies and for construe - tion p1.rposes ·1 I years, wells have ceen dug in eastern C ' Amalie for a supplemental ·.•,ater supply for · __ -:,Jiublic-housing pro1ects. Several other wel · ._ been dug in the same ;eneral area for w .. , nondnnking domestic . ~ . ':- use. Since 1926, 18 public h1lls1de ram catchments have been constructed. Of these, 14 are con- :1ected to the urban water-distribution system. 11 ·.\'ater :s hauled from the remairung four catch- ::1ents b·1 1nd1v1dual users or by water haulers. The total area oi the public catchments is esti- :-:-:ated to t)e 2-! acres, and the storage 1s estimated to t)e l~ :n1tllon .Jallons. Rel1i'!ble figures are not available or. the amount of water used from any of the catcr.~ents. :.iut total yield 1s estimated to be 50,000 gpd, :r-. add1t1on to the pubhc catchments, four pnvatelv owned catchments are 1n the urban area. ..:. gallery well at the airport was an important source oi 'Nater ir. the 1950's. ;t reportedl·t "/telded 13,000 gpd • .:n attempt to increase pro- duction resulted in salt-water encroachment, ruining the well as a source of potable water. ia 1962 the first desalting plant, with a capa- =1ty of 250,000 gpd, was put into production. tn 1966 a plant of 1 million gpd was put into produc- tion, and, by 1967, the start was made on a 2.5 :nllhon gpd desalting plant. The demand for water has increased six-fold since 1960 and shows little ind1cat1on of levehng off. In 1962 and again in 1966, when desalting plants were put on line, water demand increased almost overrught to absorb the increase in produc- tion. water barging, considered a stopgap measure, has had to be continued to meet the demand. The desalting plants reportedly will produce water at an average cost of about S 1. 00 per 1,000 gallons when operating at maximum efficiency. The cost of barged water from Puerto Rico depends upon equipment used, but in 1967 averaged about S3,50 per 1,000 gallons. Water is sold to the .:onsumer at a cost of SO cents per ton, about S2.00 per l, 000 0,111,...,ns. The difference betwe6n pro- :iuction cost and delivery cost 1s absorbed by the '.'Lrg1n Islands Government. Rural St. Thomas r<ooftop catchments and cisterns are still the ~.ajor source of water for rural St. Thomas. Dur- .:.g prolonged dry penods, rain water is supple- ·- ~nted by water hauled from public-supply points .., Charlotte Amalie. Small ponds have oeen con- structed, tapping storm runoff for 1mgat1on water :or tn.:ck g,rn:iening and drinking water for stock. .:3ince 1962 several private wells have been drilled TUT l_JI. _ _; .,::. - - -- ::-:iservat.1ons indicate that wind velocity ana roof ccnfigura tion are maier factors m the recovery =f rainfall from res1dent.1al structures. P.igh wind ·.vdl blow ram off a pitched roof onented parallel :a the wind, wnereas a rain shadow in proportion to the degree of roof pitch will occur on the lee side of a roof onented perpendicular to tne wind. ;. '/-snaped roof will be affected 1n the same :-.anner, ::lthoug,. probably to a lesser degree. :-~e .-est er£icient 1s probably a flat roof wit!"! a low lie ~,::;u:-:c ::-:e edge. ',Vater cannot blow o:i t~e r.::;of. :wr ; s a rain snadow created, and the lip converts tne roof ,nto a temporary storage container dunng :-:1c;h-ir.tens:t·1 ,a ins. Rainfall recovery on flat r·cofs ,s probably greater than that measured fror.i the ntlls1d-.:: catchments, whereas recovery on each :-cofs 1s probably 10 to 20 percent less, deoendmg =n cr:entation and steepness of pacn. Figure 25 shows an estimate of the annual costs Jf collecting rainwater and of cistern storage '.Or a small home. Cistern cost, amortized over a 20- year penod at 5 percent per year ( interest costs s:ot 1ncluaed), is estlmated to range fro::-. S5 .00 per c1...oic foot for 10 percent storage to S2. 50 per cubic foot for l 00 percent storage of the total annual recovered rainfall. Rainfall recovery was ➔stir..atec to ee 70 oercent ct 3n anr.uai ,3.r.:all Ji ~O :r.cnes over l, 000 scuare feet .:,f reef. ~e- c:::very unaer these cona1tions 'NOUid y1e10 ~8 ~pd. :twas assumed that water loss due to ::1suiftcient storage would ::ie maae up oy water ,:1...rcnasea :rom ·.vater haulers at costs of 10, 20, or 30 dollars per 1,000 gallons. The figure shows that, .using these cntena, the optimum c 1stern storage would ::ie about 20 percent of expected annual recovery, or about 3. 5 gallons per square foot of catchment • . .:,verage yield from rainfall alone would be about ~O gpd. c,nnual water cost would range from 5130 to Sl 96 annually, er 57. -tS per l, 000 gallons to Sll.20 per 1,000 gallons .. :..nnual cost of 100 percent cistern storage would be 5294 or Sl6.80 per 1,000 gallons. Ground Water Ground water 1s available 1n nearly all parts of the island in sufficient quantity to be of 1mpcr- tance to the water supply. '.n general, ·11elds of wells are sufficient only for 1ndiv1dual domestic supp hes. There are, however, a few areas where yields to wells are large enough to warrant soo-....--------.------,-----,------r--,-----r--,---r--r---, V, a:: <[ ...I ...I 0 Q ~ t- en 0 u ...J <[ ~ z z <[ 400 300 200 100 -------·---·---. ------+-----I I . Supplement water 1 ✓Storage 15 gallon, per 9quare1 fool! 130 per 1000 gallons I' (28 pj!rcent) , : I ------ ·----------+-------- -r-·-·------.;._~----- Suppl1ment water ! 1. t 20 i>er IO00 gallons ,, I , Supplement water IIOper 1000 allons 0 L...~IO ______ .....J20.,,...... __ ........,,3~0----:4l::-O---::l:50::--:6=-'::0:--~70~8:';:0~90~10~0:--' CISTERN STORAGE. IN PERCENT OF TOTAL CATCH Figure 2 5. --Annual cost of water from a roof catchment of 1,000 square feet with a ma;a.'!lum yield of 48 gallons per day. 31 TUT - i<a1nfau :- 3 o1e ~. --Scale :: ·:Hues :or aeterm1nrng .;r::iuno-water potential from pnys1cal critcr:<.l cina PXamo1es for selected wells 7opoqrapny C.xposure :ira1nage area Potential ) ·:alue \ I Long term Inches ·:a lue I 'ialue --:res I '/alue Sum of values yield . .Jpci I Crest of I North or south < -to I I) < 100 1 4 or less < 500 IJ ndge ,) .;lope i ; i General ! South slope 1 I ' -tlJ-45 ' I l 101-200 2 i 5-6 500-1,000 ! slope I i North slope ' 2 I Central I Sheltered I ' valley on 45-50 ' 2 2 I 1ntenor 2 201-300 4 7-8 1,000-5,000 ' general I I I slope valley ' Large I > 50 valley or I 3 3 301-400 6 9-10 5,000-10,000 I alluv1al flat i I > 400 8 11 or 9reater 10,000 + Examples Well 3 2 2 2 l 7 1. 000-5, 000 Well 10 1 1 1 1 4 500 Well 22 1 2 2 2 7 l, 000-5, 000 Well 20 1 3 2 6 12 10,000 Well 16 1 4 2 6 13 10,000 32 - t?:e development of publlc supplies for local use. The water, as a ·.vhole, LS ::ii poor :,ualit·/, !Jeing slightly :-:unerallzed, but c.:in still be considerea ;::otaole. :: :;ir. :Je blended ·:/lth CLStern ·Nater, '/Leiding a :"'.1xea ·.·,ater of r!lore ac~eptable pota- :;d1t·;. H Jusenolders ·.vno :,J•:e ·.vells ;enerall1 preier a cual s·;ster., ..1srng t:-.e ·::ell ·sater for ·.vashing, lawn w.:nerin;, ·,,.,:: s.:initarr purposes and ~ain ·:,ater :0r rir::fr.:,-., ;,.c :,0-::n..;. -,.,.. ·r·1,!'1ri-•N'lter poter.tl.Jl ,f Jr, ,r'"J c;in Ln large part be determined by ,rie a•:c-.,- ~ · "nuai r31ni.Jll, t::ipogr,1:::ny, and e:<posur•~ t-::i S.)l.:Jr ra-::i.1- tion. ln general, .:ireas receL•nng 1•.·ss ,'1Jn .;u .nches oi rcJiniall h.:ive 3 l-::,w -;r0und-·.•1,1cer :::.ten- nal. The southern slopes ::if t!°'.e 1sl.:ina, ·.-.-nere, !Jecause of sol.:ir r.:ia:ation, •2'-'ilPOtr.:inspirutiun .s nigh and recnarge is l:J·,v, Jenerally nave less ~round-water potentt.:il and "(Leid rnore nighly min- eralized water than the north slopes. T::ipography is important Ln th-1t - th " fL1tter slopes -JfOund- water recharge is iavored. A crude scale based on rainfall, topography, exposure, and drainage-basin area was developed for estimattnq <,1round-water potential of the rocks ()f the island I table -i l. The different features are assigned v;: lues ranging from 0 to 1:3. The !5Um of these valuf:s 1s a number irom which an estimate of the lon<;:-term vielJ of a ·.veil can be obtained. ;,. deep well will .,;enerally ·,·1eld more water than a shallow well in the same location. for the purpose of the scale, a well c!eoth of about 200 feet 1s assumed with the water level in the well at 50 feet below land surface. Little water 1s yielded from depths 0f more than 2 00 feet below the water table. It 1s empnasized that even though conditions appear favorable for obtaining a ,iround-water supply, there 1s always u p0ssibd1ty no water ·.vill be obtained as <l w:,11 may n.::>t penetr.:ite water- beanng stratu. \-Vater in ,:onsol1ciJted Rocks The permeable zunes or rne consohr! ·t,:,rl rncks consist of ooen joints and frJctures. :-:ear t:-.e 33 land surface the joints are open--the result of ·Neathenng and release of pressure. Joint open- ings, however, narrow rapidly with depth, anc ,;enerally at depths of a few hundred feet they are too narrow to transmit significant quantities of ·.vater. ,\ll the bedrock for::-iations are :::iroken ::i·✓ f:iults-- :ractures :1lcnq ·.-:nicn ~-:)•:e~.er.t ":Js :J~en ::lace. ! :1 some faults, earth ~<.J'/ement :-ia s cn.:sr.ed ~r.e rock to -aravel-size oreccLa, wnereas ,r. ct":ers t:-.e rock :-ias been reduced to a ilourlike su:.istance called fault gouge. :!.recc1ated fault zones not sealed by mineral deposits or :ault c;ou.,e car. oe ,,ery permeable and often extend to ceptns oi :-iundred s o i feet. The .x1entat1on of :-:,any of the valleys ma bays ·:•11dentl1 1s controlled by a fault and Jo1r.t s·;stem along which erosion has occurred. ·:alleys, :nerefore, are often indicators oi zones ,Jf Jn extensive jointing or fractunng system that may contain ground water. The yield to ::ells dnl.led 1n the oedrodc 1s small--~eneraily less than 1,000 gpd. :\!any wells v11ll yield 5 to 10 gpm ( gallons per minute, for about 10 hours. After that they yield at a much reduced rate as a result of removal 0f water from storage in the 1mmed1ate viciruty of the well. Once water in local storage is removed, the yield to the well is reduced to the general yield of the aqu1fer. For example, well 17 near Wintberg re- portedly yielded 12 gpm ( 17, 000 gpd) for a 2 4- hour pumping period when first drilled. However. almost dally use over the past 5 years has shown that the long-tenn yield of the well is about 2 50 ;allons per day. The consolidated rocks are penneable as a result of interconnected open fractures along joints a rd faults, which tend to be hneM. How- ever, permeab1lity may vary sigmhcantly alon~ a lineauon. One example of possible linear permeabdity ts the north-south fault 10 eastern Charlotte ,:,ma lie. Penneab1lity, as detennined from pumping tests of wells, ranged from about 1 to 9 gpd per it2 ( gallons per day per square foot) east and west of the fault. lmrned1ately along the fault zone in the vicinity of the race track, however, permeablllty ranged from about 70 to 150 gpd per ft2. South- ·.vard along the fault permeability was 1 ~pd per ft2 . ·1' ! ·, ) , __ .. i .)():/ The effective poroslty, or storage capacity, of - the consolidated rock also is related to open inter- coMected fractures and joints. Effective porosity in the upper Turpentine Run basin is estimated to be 4 percent based upon changes in the ground- water level in response to rainfall. Effective porosity of the rocks in most of the island is estl- mated to be 1 percent or less. Water in Unconsolidated Rock Water-bearing unconsolidated deposits are present only in Turpentine Run Valley and in coastal embeyments. These deposits consist of two dif- ferent lithologic types, which have a variety of water-bearing characteristics. They can be divided into ( 1) a bouldery silt and clay alluvium, which contains lenses and beds of sand and gravel, and ( 2) beach deposits, predominantly coral sand and occasional interbedded zones of coral, beach rock, and organic silt and clay. In the coastal embay- ments, alluvial and beach deposits may lnterfinger. The alluvial deposits are predominantly fine grained, and, although they have a high porosity, they have a low permeability and will yield water only slowly to wells. Water in these deposits is with faw exceptions under water-table conditions. Send and gravel beds and lenses in the alluvium are rare. Where present, however, they will yield water readily and act as a large collector syltem into which water from the leH permeable alluvium will percolate. Occasionally the water in the sand and gravel beds ls under artesian pressure because they are confined by the less permeable overlying alluvium. The beach deposits, principally medium to coarse coral sand, have a moderate to h19b per- meability and porosity and will yield water readily to wells . The moderate to high permeability of the beach deposits is often detrimental in that salt- water encroachment can Naily occur. W • .,;,.r , ,..,, -. --~ ~ . . t---- ~~ Ground water in · • is assumed to be under wawr-tablo co. ' -tbot 1■, the watar surface is unconfined, open to the atmosphere, and free to rise and fall. Sufficient data are not avail- able to show contours of the surface of the water table throughout the island. In gen.-al, the water table roughly parallels the topography. The depth 34 to the water table is a few feet below land surface in the coastal embayments but may be as much as 120 feet below land surface near the crest of the central ndge. The water table responds to changes in the quantity cf water stored in the ground~ater reser- voirs. The water table nses when recharge from rainfall or streamflow exceeds the discharge: 1t declines when discharge to spnngs, streams, or the sea, evapotranspirauon from the water table, and withdrawal of water from wells exceed recharge. Water-table fluctuations The hydrograph of well 1 in figure 2 6 is typical of the water-level fiuctuaUons in the rock aquifer of the south coast. Recharge follows the infre- quent heavy rainstorm or smaller storms in a wet period. The overall low storage capacity of the rock causes a rapid rtse in water levels, but the steep hydraulic gradients result in rapid loss•• and almost as rapid declines. Figure 27 ls the hydrograph of well 24 tapping the alluvium and weathered bedrock ln the lower Turpentine Run Valley, and figure 28 is the hydro- graph of well 21 in the alluvium of the upper basin. Recharge is rece1Y9d every time stonn water nins off in the stream and water level• rise. Between times of storm ninoff, ground-water level• are partly maintained by the infiltration of ba•e flow from the stream when now is present. The hydrograph of well 19 ln figure 29 shows the pattern of water-level fluctuations of the rock aquifer in ups,« Turpentine Run basin. The pattern is similar to that of the rock aquifer of the north coaat and largw valleys on the south coast. Here, greeter permeebUity enc$ ston9e capacity and generally thicker soil and alluvium result in a slow• but more prolon;ed respon•e to recharge and a slower discharge. The "troughs" in the hydrograph durtn; early 1965 were caused by pump- age (averaging 18,000 gpdl from a nearby well. Recharge The bedrock aquifer is principally recharged by 1nf:Utrat1on of rain on the land surface. Stream- flow and storm ninoff locally recharge the alluvium, which may, in tum, contribute water to the bedrock aquifer tn the major valleys and allu- viated coastal embayments. - - Rainfall, vegetation, evaporation, surflcial deposits, and exposure to solar radiation are the main factors affecting recharge to the aquifers. Leaky-salt water and sewage mains 1n Charlotte Amalle and effluent from sewage plants 1n the Turpentine Run basin also contribute water to the aquifers as does effluent from septic tanks through- out the island. Recharge irom these sources 1s detrimental as it 1s a potential source of pollution. The bedrock aquifer 1s recharged infrequently and only after a heavy ram or series of lesser rains. The amount depends on the antecedent rainfall and the degree to which s01l moisture has been depleted by evapotransp1ration since the last rain. Extensive brush cover and the granular nature of the soil cause rapid evapotranspiration. Conversely, the granular nature of the soil will allow water to pass through the soil zone without the soil being completely saturated--saturat1on being required only along the conduits between the soil granules. This reduces the water needed to satisfy soil-moisture requirements before recharge can take place. Even then, under dry conditions, a major rainstorm of 2 inches or more, or the equi- valent in lesser rains, is necessary to initiate re- charge to the bedrock aquifer. The amount of rainfall necessary for recharge vanes from one part of the island to another. On the north slope 1 inch of rain may cause recharge, whereas on the south slope, under dry conditions, 3 inches or more may be necessary for recharge. The fluctuation of ground-water levels indicates that recharge to the aquifers on the south-facing slopes is less frequent than on the north-facing slopes. Less frequent recharge on the south slopes 1s attributed to the greater solar radiation received by these slopes, which results in increased evapo- transpirat1on and a greater soil-moisture deficiency. Consequently, a greater volume of water is neces- sary to overcome the soil-moisture deficiency before recharge take ■ place. ,...,,.,_,: .. Where the s3i-,ositl ( saprolite or alluvium) are th . ". ftllftlJ from 2 to 15 feet, as on the north slope in · nity of Dorothea, in upper Turpentine Run be •.ad in the alluvial embay- ments, such as at Lan9 Bay and the Harry S. Truman Airport, water is retained in the surficial deposits and takes a much longer time to reach the bedrock aquifer. Peak recharge to the bedrock aquifer may lag as much as a month behind the rainfall. In some places little recharge reaches 37 the bedrock aquifer--as most 1s discharged to spnngs or streams directly from the saprohte or alluvium, as has been observed in the v1ciruty of Dorothea on the north slope. Runoff from maior rainstorms 1s the principal recharge to the aquifers of the coastal embayments and 1s an important source of recharge to the alluvium of Turpentine Run. Base flow of Turpen- tine Run and Bonne Resolution Gut at Dorothea Say, when present, also contributes recharge to the unconsolidated aquifers 1n their respective basins. For convenience of discussion, the island has been divided into five ground-water areas as shown 1n figure 30. Estimates of yield in these areas are given in table 5. 7dble i. --C:sumated yield of ground-water ~reas. · See flq. lU I _j:-ound-water I ..:.rea. Estimated yield ~r.nual r'!Cnarqe, Jfed 3Q ml ·l!X1 mq;yr :nches I 13. 6 450,000 16-1 .J.7 I I Lonq DdY I .] y 70,000 11 25 •• 9 I I Lindberg Say I . 2 1 J0,0001/ 11 4. J 2 J. 4 350.000 128 2.2 2 Upper basin 2.) )00,000 y 110 2.8 2 J 4 s Lower oasin_ I. I so ,000 ~/ 18 \.! 4.6 250,000 91 t.c .4y 100,000 16 i.J 10.0 100,000 )6 . 2 Total J2 1,250.uOO 455 1/ .,_pprox1mate area of alluvium only. Y DoH not include dn1na9e be11ns at Areas 1 and ; 'Nh1ch conlnbute recharge to Area 4 from surface- . ..,,.ter runoff. l/ Y:eld 1ncluded 1n ArN I total. Y Yield included 1n Area 2 total. Ground-Water Areas Area 1 Area 1 encompasses about half the land area. It is underlain principally by fractured volcanic tuff and breccia of the LouisenhoJ f'onnauon, on which l or 2 feet of soil have developed. On the south side of the island, from the vicinity of Charlotte Amalie westward to Brewers Bay, the volcaruc rock has been extensively fractured. The fractures, however, have been filled with U( ()() C : ..... · ;"·.J !_:) ( .Al TL.AlNTl!C OCE.AlN 6 ~ EXPLANATION 6 •' 0 l:::-.:-=-:-::] ....... : . ....... 2 FOIi SYMaOLS Surface-water gaging station Drilled well, number refered to in tut. Dug well Gallery Spring, number ref ered to in text. Rain gage Pollution from salt-water mains Encroachment by sea water Boundary of area Alluvial deposits Areas, see explanation below C.ARl!BBE.AlN 0 2 3 m,lu ( § E .Al -. ,- ,~: . ·•···. ( ( A'f.i~;I· EXPLANATION Areu 1 Wells in rock SO to 300 feet 1n depth wdl yield up to 1,000 gpd. In some larger basins and alluviated embayments yields up to l O, 000 gpd may be possible. Water contains 1,000 to 1,500 my/I chloride. Wells drilled near the sea and below sea level may yield brackish water when drilled or if pumped at excessive rates. Area 2 Wells in rock SU to 250 feet in depth will yield up to 30,000 gpd. Generally, deeper wells have a higher yield. Short-term yields of selected wells may be as great as 150,000 gpd. Wells tapping alluvium of lower Turpentine Run will yield up to 10,000 gpd. Water contains about 1,000 mg/1 dissolved solids and about 200 mg/1 chloride. Little danger of sa It-water encroachment except in lower Turpentine Run. ( Area 3 Wells 111 rock SU to 21lll fed rn deµtli will y1elJ uµ to 5,000 gµd. In some l,.H•Jer drt1int1uc' busins, yields up to lU,llll0 yµd muy be puss1ble. Water contains about 1,0110 my/I d1ssulvcd solids and about 200 mu/1 chlonde. Wdls drilled near the sea ,:ind bel1>w sea level 111<1y yield IJr<1ck1sh w<1tcr when drilled or if pumped <ll cXl'l:ss1vt• rdk·s. Area 4 Wells 1n limestone 511 to 1 Sil fE.:d in deµth will yield up to 50, tlUll yµd. Short-term yields of selected wells may be <JS yreot os 1511, llllll ypd. Water contains about l, 5110 my/I diss1ilvul solids and 200 to 30ll my/I chloride. Wells dri lied neur the sea or below sea level may yield brackish water when drilled or if µumped at excessive rates. Area 5 Wells in rock 50 to 300 feet 1n depth will yield up to 1,000 gpd. In general yields are small. Water contains 1,000 to 1,500 mg/I dissolved sulids and 300 to 500 mg/I chloride. Wells dnllcd on penin- sulas and in coastal areas yenerally will encounter brackish water. Ground water polluted by leaky salt-water mains in Charlotte Amalie med. figure 30.--Ground-water areas of St. Thomas show1ny Jocatwn of wells, spr11llJS, stream gages, and rain gayes • - secondary minerals. Alluvium and beach deposits fill the coastal embayments and are especially prominent in the Charlotte Amalie area. Ground-water levels range from a few feet below land surface in the embayments near the sea to as much as 120 feet below land surface on the central ndge. Depth to the water table is greatest beneath ridges and least in the valleys and lowlands. Wells range in depth from 50 feet in the low coastal areas to 250 feet or more near the central ridge. In general, the higher the altitude of the well site the greater the depth of the well. There 1s really no particular depth at which an aquifer can be successfully tapped, as yield depends entirely on the depth and density of open water-bearing frac- tures. A well in the Long Bay area ( well 12) at an altitude of 40 feet was drtlled to a depth of 120 feet before water-bearing fractures were penetrated. Well l O, on the other hand, at an altitude of 320 feet on the slope of the central ridge, penetrated water-bearing fractures at 60 feet. These, of course, are extremes. Long-term yields of wells generally range from 2 SO to l, 000 gpd, although initial or short-term yields may be 10 times greater. 1\tto valley areas, Long Bay and Lindberg Bay on the east and west edge of Charlotte Amalie, re- spectively, have greater ground-water potential than the remainder of Area l . Long Bay. --The Long Bay area lies in a basin about l square mile in extent, of which about O. 3 square mile is alluviated coastal embayment, and the remainder is steep-sloped volcanic ridges with little soil cover. Alluvium as thick as 60 feet overlies the bedrock. Near the coast the alluvium underlies and interfingers with a thin beach-sand deposit. A relatively impervious clay overlies the bedrock from a l1na about 1, 500 feet inland sea- ward to the shoreli't~ Bay, and probably extends out under · • Water is present in the alluvial depostw,. · · -th• main aquifer is the underlying volcanic~ IA9a .. 1, the bedrock underlying the allu,,..kla more water than that underlying the ridges. The zone of greatest yield 40 co wells 1s bound by the two faults ;:,ass,:-.<e ::-ir-~·-.;;-. the area. .::.. factcr c..;~:r:::i,.:~::-.; ·.::i tr.e :;rcauc•:·:tc·,- -f ·:'.•c :)edrc-c-: 1s '.ne .;•.~nr,:n alluv1u:n !hat Jc,:; ~:; J st,.:r3-~e r'?22~:c1r. "!"'.·.e =ilu':! 1_;:, (:.;r.tj~:-:s .. J:-:;-2 1uar.t;.~t's Ji ·.·11~:!r. -~c.3us~ cf :ts ~ _-.v :..4:=r~ta- bdity 1t generally ;·leids l,ttle 'N•Jter ·0 ·sells. but 1t yields wat-2r s1c·.·:ly to tne .. :-.c:er!·::;-. .; ::e".!- roclc aquifer. fhe cn:ictpal c1rea .A :-ec~ •r;e :: the bedrocK ,3quifer 1r0m rhe a I Ii.;·;.:.:~. : :::-1 f,:,ot of the volcanic nciqes inl,ir1c :t .:-. : •:: ~e ·: the impervious clay wedge cappin.; :1;,., .:,2r::-.:.: •. and mostly upgradient irom the area .t '",:J."/ water mains. The long-term y1eid cf the allu·11un•-:,Adrcc'.:. <1quifer 1s estimated tc be from 60,0C., ·, ·~, 1 :)CO ;i::d. The yield of wells ranges tr')m a:: :'-lt ..' · 0 to 7 0, 000 gpd. The high yield of scme -~f :h: wells, however, has little todow:tn ~/"~ k;;;- :crm yield of the aqu1fer. Sustai:1ec ;:,·:mpage ::-. excess of the long-term yield of the a~u1fer wul deplete the fresh ground water 1n storage acd r:-0b- ably result in salt-water encroachment. Salt water has encroached in a narrow strip c,f the alluvial aquifer bordering Long Bay because of pumping dug well1 13, 14, and 15, which supply Pearson Gardena public hou ■ing. Nearly half the alluvial aquifer, however, is contaminated to some degree by leaky salt-water mains. The approximate limits of salt-water contamination are shown in figure 30. The bedrock aquifer under- lying most of the contaminated alluvium contains fresh water because the pnncipal recharge area 1s upgradient of the relatively impermeable clay cap overlying the bedrock throughout most of the contaminated areas. Salt water has entered the bedrock in at least one place. Well 11 became salty after being pumped heavily for about 3 months. Sa It water from the alluvium has apparently entered the bed- rock aquifer through several improperly construc- ted wells. In each the aMular space between the wall of the well and the casing was left open, 3nd salt water moved down the aMular space, contam- inating the bedrock aquifer in the v1cini ty of the well. TL.Jl .. uu2 u 040 f i - ~-....:...:..::.~_2 -- ::1': ad'J',·:.,:) '<~ .: ··.- .3 :-er! ~1::-111.:: ·.c .:- ,: --.:: .::-:;:>ervi•.:,,;.:; - '·:! ~ ja sin ari: - : .:nicn 15 :·::~.-- , __ -. :: ~ i:f"'.1,.:i. • cl • , : - : -~. = . ~ ,: r. -.: : ~ .. · -.... _.-_: .s :r · :.., '. _-.-, oer:·.·,~LJLLt·:. :-:-=:: ·r ·si~•, .::! ~~~ : ..... 'J~ ;·:- .i.3 :..:r-~Cl:-:-.v ·- . ""'-. - - . i.. .' .,:Gti!"l;1:-::; :~=rccK l.; ·<..:Jr.:..: -~r-.:CClil E\. --1r::; :: :.-. Jl.t~rr:<J :J~.,- --=J: ::-::: 1.·:trus1ons. " .. -~•~ ·.·:-~11s, ~. c. -~r:c: , ·s :-:een IJr:ll-=u .;-: · ~~ :r, ~~ :=·: ,;o:..:; -,- 0 ·.::-:::-c,~ -:•..; ;~ ~: :!"le aduvi:il .' ei I ,~ ·: 1 '":'"'.-r::-1 ct 2'JO f":'~t. .'.'-l.'..~ -, :"1.J O -.~'ie -:: . .-.:-;- :t:=:~i ·>~id. e~crna~'="'~ ~(' ~·~ :.~, 11) 0pd. ~e"."!r.:t:.~ ··-=- 1 '; r_~:,hab1·✓ ·•,di ·,:~ld i .1 , ~·-•; qi:;d 1n the "."1::,.:::, -~~t !~~ t::r:=a,mcn~ !.Or:1~ ,::t the a1r1=ort. T:~-a :1! ... -.. 1_:_: ·c re!dt1va!·., :~ic·, :~er'! •:!nd, tn•.::;, ." :•~.:;11~-~ ~:.Jntr!.s,t..:~e ::0::.-;1.~~~?.!:le ~uJnt!tles :::: ·.vJte~ • :i -,.~ ~--:Jcrl·v·,:ig O':!dr:Y.:i< ,;_:,.;:for. - • r1-::.:er-.t:::1l yield Qf ~~e ;;\~,:irock aqu1!-=r . _ · ,·:'.: -.-_,,,-\ ~;; ae JC ,0110 ;pd, J.;si;:-:un,; j.:ita ·:::ai1-:!d -r~~- , ·s Lc.:i~ aay ,,r~a car ce applied. Salt-w<'lter mains in the 9oume field housing .;rea arP. known to leak, c1r.d 1t must be assumed :.;Jt :.--:~ ,Jlluv1um in that v1cin1ty LS contammat~. :-::e same care to prevent salt-water contamination -:,y 1r:.::;roper well construct1on must be taken n~re 1 s in che L::>ng 3ay area. ,:c or,e t1:r.e a gallery paralleling the runway H :he J1roort wae Wied for water supply. This :.;JU,.ry, ·,vhic:5'· ·· · · runoff from the n.mway ~r.d :;tQred W'l ' ·: · •lluvium and landfill :. x .:t..t~rP. ,J:;e, :-;,1d ' . · ••timated to be 11,000 ,;pa. U:1for.un,ne.iy, tltil~was overpumped :!nd salt-water encroachment followed. Salt w~ter 1s sull present in the alluvium near the well and ~s .r. a position to intrude the bedrock aquifer. ·.v a ter from the gallery occasionally is used for 41 -.:-::::1ble purposes. T~e use of water from ··• ··:.:J·.- drainage for drinking purposes, of course, , ..;a !"::;erou s because of the presence of toxic _.: --:::'."'i;nds such as nydrocarbons and tetraethyl :~Jm spilled aircraft fuels. · rea 2 1s the drainage basin of Turpentine Run. :r.-:enience 1t is separated into an upper and .··.-:-er ::asin; the upper basin above the stream- :1-.~ -:tation near Mt. Zion, and the lower basin The principal rocks are volcanic flows, ·. :·:. 3r.1 breccia. Alluvium as thick as 40 feet . . .:s .:: ::1e main stream channel of the lower basin. :r~hwest-onented fractured and jointed zone ·.•_:c:r•:t.1ermally altered rock bisects the upper ~: .J:~d wells range from 40 to 250 feet m ;::cth. :''ie shallower wells tap the alluvium and :-2.,:hcr...:.! bedrock of lower Turpentine Run. :-he ·!epth :::f ~he rock wells is not necessarily a cn- :0r,::::-: :Jf ·;reater yield, but 1s usually an 1nd1ca- ·. Jn cc "Nhere a zone of water-bearing fractures ·.-,;:; c.enctrated. Short-tenn yields from indi- '::Juul rock wells in the upper basin are as qreat -, 5 1: J, JOO gpd. Sustained yields, however, -,:-iqe trom about 3,000 to 30,000 gpd, lncil- ·:: ,L:J! Nells in lower Turpentine Run yield as -:-. , ::::1 , s 30,000 gpd, but sustained ground-water ·.•:,:!":drilw<1is of more than 10,000 gpd will i::robably r~ :>'..llt , n sea-water encroachment. .:r,:,ur.c!-water levels. --Contours of the ground- ·:,ater surface during August 1965 and January 1 'Jti6, ure .;;hown 10 figures 31 and 32. The arrows nn these maps indicate the general direction of ;round-water movement. In the upper basin, ·,,hen water levels are high, ground-water flow 1s split--part moving along the course of Turpentine Rur. .ind part moving through the fractured and 3ltered zone at Mt. Zion and emerging as a series 0f spnngs discharging to Turpentine Run in the lower basin. When ground-water levels are low ,!1 tne 1Joper basin, nearly all ground water 1s ,rooably dLscharged through the fractured zone at '.H. Zion, and a temporary ground-water divide ts ~stablished at the poS1t1on shO'Nn in figure 31. Grour.d-water levels in the basin fluctuate in relation to discharge from and recharge to the aquifers. figures 29 and 27 are the hydrographs of wells 19 and 24 anlled in bedrock in the upper basin and in the alluvium and weathered rock of TUT Ci().· REFERENCE NO. 17 . ....._, No data base is available for a detailed assessment of population within a particular radius of the site. The best available information follows this note, and consists of a 1980 census by water district. Populations were estimated by adding together the populations of ffCh district within the radius of interest. In cases where only a portion of a district is within the radius, population was prorated by area. ' j t ;- ' t r r r l I t I l I l I ~ - ~ ~ ~ Kris Buros WATER MANAGEMENT PLAN FOR THE _____ -.----_- ___ - PUBLIC WATER SYSTEM , .... ,]' ,,· Prepared for _ ._ THE DEPARTMENT -oF _____ - -------- --· ---- ---- ---- -- --- -- - CONSERVATION AND CULTURAL AFFAIRS GOVERNMENT Of THE VIRGIN ISLANDS Prepared by CH2M _ CH2M Hill SOUTHEAST, INC. IIHILL Project No. GN14325.AO --~ 'July,1983t • , • ,__ L-- .__ '"- ,._ '- ... ... .. \ I ( ( Table 3-3 DEMOGRAPHIC DATA FOR THE U.S. VIRGIN ISLANDS •et: lttO •~i;!t.•• D11• JOUO 1'1 ~ c~ t eol Dal a Ji.;iilatl• liiiili twee w.1. ..,.,_ .... la&IN lliiil hrN I ■ iot■I ■ L ■t•r•t fiipila&ioa Uork Fur.ca · liool ■ ilotela ... ,., .. 111 ... .!HIICI ~ P!fir> ~ ~ (UIII ■■) «-.,-> '"iF) ••w tr;> (lalllu} «;..-> «;_,-L umw ,,_., ~ ,_ P! w ll,J■IIII l l,DU ,..,. ~" " .. 1,20 SID Ut 14 UNI 1,u, ss, u, .... lH I "' J .. l,112 Mt ,. 10 ,,no ,o ua )0 ) HI o, i''• H ,., ,.,. »I u >• 00 JII 2) "" II : ,· :} .•. - ,,, u I) HJ JO I) .. " ... ~';-'"· -· s r.tl ,1 "' ftJ 1Ul'AI• .. \. ,:;:• .. , - B f;tD r.m m m (fl ,:ns r,olti HI m m It.no-a I ,n llo2 11,1 I ,,. II y >H u ,.. .... 12 " , ns • .,, • JH • ~o u .. ,,sn .., He ,.. 1,11112 Mt 260 JO ,0 1,161 SI 260 )U , . , 2,,16 • u ,. 1,111 JJ 12 ,. ,. 16" u H ., • ,.s .. ··•it , ... , ... • , ..• ,.u• ,,n, ,n us S,OIO l,SU >,Sit, 1,)) 1n ' ,.,,.. ,,.. ... H , ... , ., ,,,. SIO .., 2,JSI H ))Ill ))) u I 1,622 SI ; .. J,HJ ... J9' ,.,2, u, 1,2 .... ,. t 1,111 ..,.. 2,611 H t,IH UJ 2 .... 2S t,212 410 2,608 H II J,.. •• ••• HI ... ••u: Ht ISi ,u us 1,11, 5SO ISi '11 IH ll 561, l • t62 ) II 2,IU 11, ... ,,. ,. i:m w 1,:t 2)1, JO J,Jn Ulo ··'" ~ .. , . n J,JSJ HI I~-, .. , , .. ... n• ,,11" ISO 1,1161 115 HO •• 6tJ 22 ,.,. JtJ . 21 ,.,. .,, 2111 )II, a, J,IM * ,, HJ ,., .. u >2 JU ,. '·"' ,.., )2 2'1 2U •• ,,,,. 6,615 lo,ZH ,.,. n• ,,,n l 105 "1» ,.,. us ,.,n l,Sll ,,us Ulo ... " "·"'' ···" '·"' au .,, ..... , ,:as, ,:m ,,. ... '··" ,,ns J,5iS 2tlo 115 II u n • lS ... 100 n .. I,.. .-;ti dH ,.JI tr.& lU IIO no UJ H lff 'Dll'AUI «-;111 IT;fil ffi ... ,111 ,,Ji} m ~ R:lti IT,lil r.na r:m I&. Gl'ela I :ns IH n .. JO UJ J .. u 160 H SH 1,41 12) H&I ss z >,NJ HI 2,ots H 51 ,.s.2 "" 2,095 H 59, s,,. I ,OloO 2,0H IU H J 11,111 nt 2,IU lit .. .,,us '" 2.111 Ill II 11,Ul HJ J,112 llO IO lo UJ IH .. 111 '" II n, 22, II s sn H ,. 1t ls:1 )2 ' ,..,. JI t ti H Mt .. , ti H ... 101 t lSI. SU ' ...... .... , l,t>t '·'"' ... , ,.n, 7,tJS ,,,u J,UO • a.JM '·"' , .... JS H ..... , ... , , .... ,. a s.ua l,tlS ,,,n s, M ' ..... ••• u , .•. •• ..... ..• , , ... II 1• ... , ,,ul ,,,., 10 •• , . .., - .,.. u H 1.,n ,.. ,.,.. 12 1S ,,a.a , .. ,1oo u H II , ... , .. " ... H J.1"1 .. , " .. .. , J,162 6tl ,s 200 so ll ,.,. .. , .. ,.,.. ., •• , ... ..... ,.,., ., ,. . . .,, 10.1" , ,,., ., Ito lJ a.sn OJ , ..• ,. - , .. . .... ,n ... 100 " ,.,. SH .. .. , 11 H ... Hl '" IQ H SH ., "' 162 H ,,. )1J ,.. 1,2 n •• '" ... .. .. H .. IH ,.. ... 2S IU IU ... JIJ H n ., ... "' ti ,.., ,,,. "" IS .... ,.,, 1s1, IS II .. .. S) u ., u ,, ,n ,., .. IIIH II -, I ..LW. ..l.Jll .l.Jll -lit I! ...1.all1 .Lll1 ..lAll! _!!! ...l! ...!..M 2,020 , .... -1!! .J! ID II C .... ··'" ~1.m •• ,u HS .,_.,., u.,11 M.en .... , ... 7",JloD u,, .. n,u, 2,lll ---l ... ~ !L!!! Yam »JD Yll ldJl Will! ~ J!J!! s,su !.a!!! 1>111,00 il 1'22 ,J,M !&~ 2,000 1::· . - ....... , '' ..... ul~l•l1 _, • ••k fwca1 Kil • act.Nii 'Ila • •-••' .. ,., ... caaa1. ,. : ; ~ ;,..11 oufpu1 DA11A F lJfrt{ AR ( DISfRICf • Ol DIHRICI • 02 DISIIIICY • OJ DISIIIICf • o• DISIAl<.1 • OS DIIIAICf • 06 OISIAICI • 01 UISfAICY • o• DISIAICI • 09 UISIAICI • ao OISIRICf .• II DIIIAICI • u DISflllCf • IJ DISfRICf • ,. DISIRICI • ,, DIIIAICf • 16 DIHRICf • Ir DIIIAICI • •• OllfAICI • •• DISfAICf • 20 fOfAL ISLAND --1 ,vd _,I ,__, ~ ...i - - ... ... - .... ... - - .. •-____________ ( ( •---- INft:ANAL DeNANO ---PO •NIEANAL •Afl!A SUPPLY -------------• •--- EXfEANAL OIENAND ---• ·---- POfA8l.t: WAfEA ----• •-- NON-POYA&.E lfAfEA--o POfABLE NON-POI YOfAL CISYEAN Olttl:A fOIAL SALY OYHEA IOIAL POfABLE NON-POI TOTAL KGALl'D KGALl'D KGALl'D KGALl'D KGAL.l'O KGALl'D KGALl'D KGAL.l'D KGAL.ID IKGAL.10 111.GAL.ID KC.AL.ID ·---------------------------------------------------------------------------------------------------------- • ., .. o.o ., .. , .. o.o , .. o.o o.o o.o •o.5 o.o •o. s 211 ., J6o2 ... ,., •s- 1 o.o •s- 1 o.o o.o o.o 22600 .J6 • 2 262.2 670 •• o.o ., ... 110.a ••• ,as.a o.o o.o o.o 555.0 o.o 555.0 ,., ... ••• IJSoS ••• 100.0 • •••• o.o o.o o.o 26. I o.o 260 l z••• ••• • ••• 609 o.o 609 o.o o.o o.o 22.2 o.o 22.2 n.t ,: .... J1.1 6ol o.o .. ., o.o o.o o.o Ja.• o.o ll•• a•>•., :; ., •·· 29>•• ••• 2 o.o • •• 2 o.o o.o o.o 229ob o.o 229.6 , ... ••••• 20602 .J9o8 II .o •o-• o.o o.o o.o 2J6.5 o.o 2J6.5 .2486., ....... •••••• o ll0o9 412.JoS •2.J•·· 21uoo.o o.o 21000.0 415.3 o.o 415.J lllel ••• lllol 290 I o.o 29el o.o o.o o.o 102.0 o.o 102.0 2Jle0 ••• 2.JloO :S7o9 o.o J7o9 o.o o.o o.o 195. I o.o I 95 • I 6070 I 21.6 6J•.s S6o2 o.o . ·•-2 o.o o.o o.o 550.9 27.6 578.5 . , .. , ••• ,., .. , .,, .s o.o Jlo!I .o.o o.o o.o 10lo2 o.c, 10.J.2 21.2 ••• as.a 600 o.o 600 o.o 0 .I) o.o l9o2 0. I.I . 19.2 I l8oS so.o 168ol .... 10.0 , ... o.o so.o so.o 58.6 o.o •••• ... , o.o ... , ••• s.o II• I o.o so.o 50.0 90.5 o.o 90.s • J.J 1.1 •• • o s.• , ,o.o a1s.• o.o 10.0 ao.o 2•.2 o.o 2•-2 2.6 o.o , .. o.• o.o o.• o.o o.o o.o 2.2 o.o 2.2 • ••• o.o •••• J.4 ,o.o ., .. o.o o_.o o.o 15o5 o.o as.s .,, •• s JPo2 .JSSo6 so.a o.o so.a o.o o.o o.o 201.1 .J 1 • 2 .J04.9 5988 • .I ,~ase., .,., ••• s 6.t8 •• ••••• s 508206 21000.1) 110.0 21110.0 .1211.1 • 0 ® ·•- 10,- fffl I .SIIO l,IIOO Me1en Setwice D1t111c11 •• Numbe,ed IOI .C. .J.J12., FIGURE 3-4. ji.ltl Proj~ted demand of the service districts on St. Croix for the year 1980. _, _, ..., -- - - - - - - - - .. ... ,. fttUMAS ----------------------, l!oLANO Ur OUIPUI U f'OA YEAR 1980 OISfAICf • 01 DISIIIICI • o, UISfAICf • OJ OISfAICf • o• OISfAICf • 05 u1~••1cr • 1)6 OISfMIC f • 01 DISfNICf • 08 OISIAICI • IJ9 ouuucr • 1(1 OISfMICI • II OISfAICf • 12 OISfAICf • IJ OISfAICf • ... UISfAICf • 15 l>ISfAICf • 16 DISfRICf • I J OISIAICI • ,. OUfAICf • I ',J JOJAL l~l.AMU I I ..b •---- INfEANAL lleMANO ----• POJAHLE .. OH-POf KGAL. .ID KC.AL.ID •-------------- INfEANAl. WAfEA SUPPLY-------------• •---- POfABLE WAfEA -~1•-0 o-- .. ON-POJA8l.E WAJEA--0 CI S JEAN Of HE A f O AL SAL f OftEA ror AL KGAL.10 KGAL.10 KGAL.10 KGAL.10 KGAL.10 KGAL.10 •--- EXftHNAL OtNANO ---• POIAOLE NON-f>Uf KC.AL.ID KC.AL.ID ro, AL KGAL.10 --------------------------------------------------~-------------------------------------------------------- ••• o.o 6 •• 1.• o.o .. , o.o o.o o.o 5 ... o.o s ... , .,. , o.o .... , ••I o.o ... , o.o o.o o.o 15.6 0." 15 •• 27.9 o.o 21.9 5.0 o.o s.q o.o o.o o.o 22.9 o.o 22.v es.e o.o es.e 22. I o.o ;::! o.o o.o o.o 6.J • 1 c,." 6J.7 137.. I •• t J8o9 34 • 7 o.o o.o ... o ... o 102 • .J o.o 1oz. l H•"~t==• •••• 5 eJ.e JOoO Ille o.o o.o o.o •rs., :,a.a 501.5 ,o.,," . . . • 210.1 20.J 65.o es. o.c, 56o0 S6.0 1 J ... so.o I 2 .J • • ea.• :,,1: .• , ;-••• e2.s I I • 2 e.c, ··-~ o.o o.o o.o bl ■.J o.o (tJ.J , .. o .• ••• a•o.e 102.e 16.0 I I•• o.o o.o o.o •22 • .t o.o •2.1 • .1 .,.o I I• I 1oe.1 IJ.I o.o IJ.~ o.o ,s.o 15.0 eJ.9 0. C, dJ.9 50.J o.o 50oJ .J ... o.o ., .. o.o o.o o.o .... 9 o.o .. •• 9 , , .... 10•5 ,as.• 28.6 I OoO .Je.e: o. C, ,s.o 1s.u ll9 ■7 0.11 I .l9 • 1 2,,., o~. I l•.Z.e •o.o t 70o0 210.0 .o.o 62.0 ,, 1.0 195.tt ... it 200.0 •o., Ci• 0 .. 0.1 •• 1 o.o 9 • ., o.o o.o o.c, .JI • 0 o.o .JI • 0 2u-.• .t6.J ...' • & • 1 .1:, •• o.o .JJ •• o.o ".o o.o . ... ,, 21>.J 207.9 112.0 s, .• 16¥.6 I I lo 1 .. , ,,0.1 o.o c,.o o.o 591.J 51.b ••e.9 561 • .r 20., s1ar.9 .. J.5 2s.o ,,e.5 o.o u.o o.o ...... 1 20.1 "'""·" o.6 o.o o.6 0.' o.o 0 • I o.o o.o o.o o.~ o.o o.s 25.1 o.o 2s., J.6 o.o J.6 o.o o.o l. J 22 • I o.o 22.1 lil 1 • I' J:,2.0 o.o 152.0 152.0 29d6•0 ~ 011UICII ... Numl,e,1~d ·•. ·., \ I l'iO ■b Jl7C..C. REFERENCE NO. 18 I NUS CORPORATION TELECON NOTE I CONTROL NO: DATE: TIME: DISTRIBUTION: BETWEEN: OF: PHONE: u ~ G-~ r~vi:.~ ( ~°I h•('t- -'4~ ••-u. AND: (NUS) DISCUHION: ~ x·Qe..,:&,-,. a, ~ \ t e! N c\• ff : t--b.:.-. 3 d ~ <n::k:y?& ::#::1: J tr:= t'e-(uo~ :±o • & Aer/ ,Af 2-: ~ doM:: ~ ~ fx o/a,,.i~ «:::: °"'# Nfti,J. REFERENCE NO. 19 - I NUS CORPORATION TELE CON NO TE] CONTIIOLNO: DATI: 3/,,, It 'f TIME: DISTIUIUTION: IETWIIN: OP: '"ONE: Uc v, hoe f2 - t,..,<,/ / C,. r ~lier T>ol ca.,·,~ ( gc~) 77-S- ltt,,o AND: 0 •n......~ INUSI OIICUISION: ro r 6cc tz. 5]) o -40 0 9< ,9a.t; '<'rd ils Qo $i 'Thom or I 3 0 r ~ •v s-1& 4/ls Q ': S.S.. Toh ..... 5:zm& J:fcoccf.s AN' ¼op± a,+ ~. bl.-, works: {OOa. Lou?:t Grt~5r) fY\, Goe:iz :::tR;,.,awa \J, HA; wells o.cs '?m \»bli f ro'," ed) ~j-(,,, m ,o ►+A~C - :sta, r< a,.c-t :§ c :,>f rnJ ; A:X:11 ~ 1,s,dl ..C C - 1 c ,·, A{0:10"', j,c,,c;..lwiA.,...;.~ \ ,, r, Ui f4 m, oT: Sbrrc ::ThR •1 ½a,v<- --- .... I NUS CORl'ORATION TELE CON NO TE l CONTIIOLNO: OATI; nMt: ,, 3/3/'1'1 L/'ID OIITIUIUTION: 02.· ~0,-1, IITWIIN: OP: "40NI: Lecf"lar&. i-?ec.d. 7)PNR (v::c) (rc9 ) 7 7 <; J 3-z." AND: 7) ,'a.~ Ir~ INUSI OISCUIIION: ~~ ;:;; ~ ~k,:~ -~II~•~~~~~ l ff 9 .I »or 7:> ~ Iv ~ . i~~ = ia::1,1 .-\.,,d2 ~ 5 s;;; ; ... _, ; ~ ; ~ £1 ~,£.H Lewa~ dci:ta f ~- s~:tz. ewners ~ ·a. . -i=>, r M.d- (.Ru(!_ ~0:1.& OQ~ cf~ ~::ti~ """-,-<__ Qc1, ec,l:o:20~ y><".~~ ,•s:s.&~+ ka.a.~a~ ~a,~+ ~U4'~ l:::Sa.,; ~~ ~g 'f ha.ue. '2::. u.)cita.r ~~~a.r~ ~S:~ - ha . ~ .. ,~, Sr~s::lr. J 4 . W, t I loCA--iJ0.,,s , v.;c,f I '"5$, depil -to 9 ro u o&½aJi• ~~~I. ~~v-e~ ~Jih1 ~~,( ~ s::. lcce-iiP-s at= cte:SA,,\ • 5<\n,o,--+ ,~k,- t: Su ,, n hf k{.. ~ .. '\~(" V \w-k {, . lrr~T.io·- I ReeAl s.c,__l ~ ~ \"'\ii""\ n""' l~ ACTIONrT'IM8: ... ,. .. ~s: .. ' ~' S: ➔ :--rt Q a/c.. s. or~L...:::ii. w~d - kl 1~:e~~~-51._.. '2:01 \ •&S.~t ci). \ f~°--~~ - I d&<d2 ~.e ... ~£•9<.e: 1.s a - TUT -· (.·., (.·.: ~) ·2 (.)()·.,:.~ REFERENCE NO. 20 ·- . ' ; '. .. .' i RECORD OF COMMUNICATION SUIIIIIIAIIY 01" COIIIIIIUNICATION ~ REC'D 6v 4- )v-/~-r { f-r. CRo;,,r ~ J--r. 7,), oni l'\X ~ ~. fe/d A-;,;,_ ~~. 9 ~ ~ ~--:c . ...r~~ ~ A "7..r tt-ff')c~ IA./;/! acc77 r.z:r ~ ~ .f7"r~..r . - /JC-8,.J' /o..r.r;//4 , - t,/o~ /;,te ~ h ✓7k _,; lv<-Z" ~d 7f:. Jud" ,,,a4V..r "' ,:::v,,«--- /,.,...,r-e-ttY,.;;,,v~ 7-A.... /"'10lA/ • IPA ,_ ·~ (J-11) ·••ucaa ....... ~-........ _IC ..... ., •• U8CD UNTIL 8UHLY • ...... uaTaD. -~- --·- -- . --- ··--- .... REFERENCE NO. 21 '), \1-.•··1 f ! _: l. HRS s Grounawattr Roule Score IS~ w J Surlac:e Water Roule Score tS1wl Air Rou1e Score <Sa) s2 ... s2 ... s2 gw sw a ✓ s2 • sl • s2 gw sw a V s 2 • s2 • s2 / 1.13 • sM • gw sw a WORKSHEET FOR COMPUTING SM PRO s Grounawater Rout• Score IS,:wl Surface Water Rout■ Score ISsw) C· CJ Air Route Scon (Sa) s2 • s2 • s2 gw sw a ✓ s2 • sl • sl gw sw a Vs 2 .s2 +s2 /1.13 -sM- gw sw a WORKSHEET FOR COMPUTING SM 52 1 '\ • I / "\ ,~,.. /Uo. ~, TUT c,.)? ()O'.:·,b m rn m Gl [!] m ,~rc1Jno Water ~out• Wor11. Sneet ~ss1gne<2 v11ue C.rcrt Onel 0 rt ooserveo re,ease 1s <;1Yen a score ot •5. proc:eeo 10 ,,ne I!]. II OOStNed release IS QIY9n I score Of 0, croceed to line m Rout• CNractttlSIICS Oec:un to AQu,ter of 0 1 ii] l Concern Net Prec1011atJon 0 w2 l Permea01111y ot u,e 0 , ~ 3 Unsaturated Zone !@] Phys,~ St£le 0 1 2 ' I Toe.I Rout• cnaracten1ucs Score Containment 0 tWl wa11e CwactenstlCs T OlUClty' Pers,stenc• ®l 5 9 12 15 ii] MazatCOUI Waste @Lil 2 l • 5 5 7 a Quanaty I Total Wute CNrac1en1tiC1 Score Targets Ground Wat•r UH 0 l 7- ' 2J 3 Olstance 10 Nearea& }~ ' s s 10 weu I Pooueataon 12 15 ,. 20 ·-· S•IVtCI 24 JO J2 35 ~ I Total T uge11 Score u 11ne OJ is •5. mu111ply I] JI m Jim 1111ne OJ is 0, mu11101y m m G rn I I JI Oiv•dt hne I]] 0y ,1.lJQ Ind IT'IUltrc:,ly oy 100 }.- J 'f O) - ll ·J -f /) (L .. v- · r...,.·... C PRO I~ I ./ I : 2 --1 a L...! ! i 1 I 3 ' I , - 3 - i - --' , _/ 3 ' \ I 15 ' I . - 1 ..) l " ?'-,.. 1 t 11 i g , C a I - 25 ' q· I - 3 I 9 '£> , ,:-- '° - -~, - 6 '9 ~-/ ~ ' ,,.,. , ~ .. u\ ~ 57.lJQ / • •·I~ I ,.. I -_: -... ;q : Sgw• ! - -- , I Surtac:e Water Route worit Sneet I I i:launo F ac:10, I Assigned Value I Mu111-j HRS I '"4u. j PRO ! c1,c:1e One1 011er I Score 1 I m Oa,erved Re1eue a ,5 t I c-1 ,5 I 0 ! If 0osenred reteue 1s given a value of •5. proceed 10 11ne 0- If 0bserted reteaae Is given • value of 0, proceed 10 llne [iJ. rn Route Cl'\aractenstlcs I Facallty Slooe and lnterventn; ID, 2 3 1 I - 3 (~ Terrain __, 1-yr. 24-flr. Rainfall oj~3 1 3 ' -.... Olsta,,ce 10 Nearest Sutface ~ 1 2 3 2 9 Water - :_~ -·- Pt,ysaca, State 0 , 2 , ~ 3 I T otaa Route Charactertsuca Score - 15 - ~ [iJ Contaanment 0 , '@ID 1 ~ 3 ~ -......___.._. m Wute C1\atlcter1stlCI T oaicaty / Persastence @3 e 9 12 15-ffi] , 0 ,a 18 HazarGOUI Wute @..ij] 2 3 4 5 e 1 I , 0 I ( Quanur, I Total wuae Olaractettauca s,ore ( - 29 ;q [D Targets Surface Water UM 0 , ila 3 3 ~ g ~ Distance 10 a Senaitne .@ 1 2 3 2 c= 9 (-,.__ Etmronfflenl ~ Poouaaaon SefWCl/01stance ' s I 10 1 ( ,o (___ lOWatetlntua } 12 ,. 11 20 0owMtrNffl 2, 30 32 35 '° I Toa. Targets Score -,- !5 ~ - [!] If line m is ,5, multic,Jy OJ x@ I Gl " 57D II line {!] is o. multioJy ll) 1 rn X G) I I]] _, 5'.350 m Oiv1de tine ~ tly &&.lSO and mulUr:,ty tly 100 Ssw • r ' -~, 89 _,,, - -- C ' -1 •. _, ' TLJT {)(·,