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Halliburton Company FIELD INVESTIGATION TEAM ACTIVITIES AT UNCONTROLLED HAZARDOUS SUBSTANCES FACILITIES - ZONE I NUS CORPORATION SUPERFUND DIVISION *64415* 64415 02-8902-40-PA REV. NO. 1 FINAL DRAFT PRELIMINARY ASSESSMENT TUTU TEXACO ST. THOMAS, U.S. VIRGIN ISLANDS PREPARED UNDER TECHNICAL DIRECTIVE DOCUMENT NO. 02-8902-40 CONTRACT NO. 68-01-7346 FOR THE ENVIRONMENTAL SERVICES DIVISION U.S. ENVIRONMENTAL PROTECTION AGENCY MARCH 31,1989 REVISED MAY 26,1989 NUS CORPORATION SUPERFUND DIVISION SUBMITTED BY: DIANtTRUBE PROJECT MANAGER REVIEWED/APPROVED BY: (kw^v^ / SEPHf/IAYO 0 TE MANAGER RONALD M. NAMAN FIT OFFICE MANAGER 02-8902-40-PA Rev. No. 1 POTENTIAL HAZARDOUS WASTE SITE PRELIMINARY ASSESSMENT PART I: SITE INFORMATION 1. 2. 3 4. 8. 9. Site Name/Alias Tutu Texaco Street Route 38 and Route 384 City St. Thomas (Tutu District) County N/A State U.S. Virgin Islands Zip 08002 County Code N/A Cong. Dist. N/A ERA ID No. New Site Latitude 18° 20'34" N. Longitude 64° 53' 18"W. USGS Quad. Eastern St. Thomas. U.S. Virgin Islands Owner Texaco Caribbean___________ Street P.O. Box 3740______________ City Charlotte Amalie_____________ Operator Unknown______________ Street______________________ City________________________ Tel. No. 809-774-1931 State U.S. Virgin Island Zip 00801 Tel. No._________________ State Type of Ownership [x] Private n Federal Q County n Municipal D State n Unknown Other. Owner/Operator Notification on File D RCRA 3001 Date ______ [x] None G Unknown Permit Information Permit Permit No. Date Issued None ________ _______ QCERCLA103C Date Expiration Date Comments 10. Site Status [x] Active D Inactive 11. Years of Operation Unknown Q Unknown to Present 02-8902-40-PA Rev. No. 1 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. Waste Unit Type Facility Name for Unit 1 _______Drums________ Waste Oil Drums___________ 2 Underground Storage Tanks Waste Oil Underground Storage Tanks (b) Other Areas of Concern Identify any miscellaneous spills, dumping, etc. on site; describe the materials and identify their locations on site. No other spills, incidents of dumping, etc, were observed on the site during the NUS Corp. Region 2 FIT on-site reconnaissance on 2/15/89. _________________ 13. Information available from Contact Amv Brochu_______ Agency U.S. ERA_______ Tel. No. (201)906-6802 Preparer Joseph Mayo_____ Agency NUS Corp. Region 2 FIT Date 03/31/89_____ 02-8902-40-PA Rev. No. 1 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 RCRA permits for this waste unit. The age of this waste unit is unknown. Until June 1986, the Water and Power Authority (WAPA) accepted waste oil and used it for fuel. A batch of waste oil was found to contain polychlorinated biphenyls (PCBs), and WAPA stopped accepting waste oil. Currently, there is no acceptable method for disposal of waste oil on St. Thomas. Waste oil generators must store all their oil. 2. Describe the location of the waste unit and identify clearly on the site map. The waste unit is located in the northern corner of the Tutu Texaco 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. There are twenty-seven 55-gallon drums in the waste unit. Twenty-five of these drums contain waste oil generated from automotive repair and servicing operations. The remaining two drums reportedly contain dirt. There are also three 20-gallon drums and a few 5-gallon pails containing waste oil on site. The total quantity of waste in this unit is approximately 1420 gallons. 4. 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. Twenty-five of the drums contain liquid waste oil. Two of the drums reportedly contain dirt which is a solid. 5. Identify specific hazardous substance(s) known or suspected to be present in the waste unit. Twenty-five of the drums on site contain liquid waste oil from automotive repair and servicing operations. This oil may contain small quantities of gasoline, kerosene, or degreasing solvents. Sample analyses of waste oil from the Tutu Texaco station reportedly detected the presence 01" trichloroethane (TCA). However, the analysis results were invalidated because the sample holding times were exceeded. 6. Describe the containment of the waste unit as it relates to contaminant migration via ground water, surface water, and air. The waste in the unit is contained in drums that are stored on a concrete surface. There are no berms or curbs to contain the oil in the event of a spill. There is evidence of spills in the storage area, and the bung on one of the drums was open. An OVA flame ionization detector noted a reading of 20 ppm from the open drum. There were no readings above background in the ambient air in the drum storage area. The lack of containment of the waste unit provides the potential for release to surface water by runoff from spills and for release to groundwater by runoff and subsequent percolation through soil. Ref. Nos 1.21.22.24 02-8902-40-PA Rev. No. 1 PART II: WASTE SOURCE INFORMATION For each of the waste units identified in Part I, complete the following six items. Waste Unit 2 - Underground Storage Tanks . Waste Oil Underground Storage Tanks 1. Identify the RCRA status and permit history, if applicable, and the age of the waste unit. There are no known RCRA permits for this waste unit. The age of this waste unit is unknown. Until June 1986, the Water and Power Authority (WAPA) accepted waste oil and used it for fuel. A batch of waste oil was found to contain PCBs, and WAPA stopped accepting waste oil. Currently, there is no acceptable method for disposal of waste oil on St. Thomas. Waste oil generators must store all their oil. 2. Describe the location of the waste unit and identify clearly on the site map. The exact location of the waste unit is unknown as the tanks were not observed during the on- site reconnaissance conducted by NUS Corp. Region 2 FIT on 2/15/89. A preliminary investigation conducted by the Department of Planning and Natural Resources (DPNR) on 8/5/87 indicated the presence of two underground storage tanks. One tank had a concrete top and a concrete partition, and the second tank was covered with a square steel plate. The volume and composition of the tanks were not determined. The material in the tanks is reported to be waste oil. 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. The capacity of the tanks and the quantity of waste in the unit are unknown. 4. 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 physical state of the waste is liquid. 5. Identify specific hazardous substance(s) known or suspected to be present in the waste unit. The waste unit contains automotive waste oil. Substances such as gasoline, kerosene, and degreasing solvents may be present in the oil. Samples of Tutu Texaco waste oil were reported to contain TCA. However, the sample analysis results were invalidated because the sample holding times were exceeded. 6. Describe the containment of the waste unit as it relates to contaminant migration via groundwater, surface water, and air. The containment of the waste unit is unknown. The tanks are covered, but no other information concerning the tanks' waste containment properties is available. Ref. Nos. 1.21.22.24______________ 02-8902-40-PA Rev. No. 1 PART III: 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 contaminants) detected or suspected, and provide a rationale for attributing the contaminant(s) to the facility. The potential exists for wastes on the Tutu Texaco Site to be released to groundwater. There is evidence (photo No. R3-P10) that spilled oil is staining soil and may be transported to groundwater. There are no berms or curbs to contain the waste from the drums in the event of a spill. One of the drums was open. The drums on site contain automotive waste oil. Air monitoring instrument readings indicate that organic vapors are present in one of the drums. It is reported that samples of waste oil collected from the site contained TCA. However, the sample analysis results were invalidated because the sample holding times were exceeded. There is insufficient information available to evaluate a release from the underground storage tank for waste oil as the construction and integrity of this tank are unknown. There are no reports of spills or leaks from this tank; however, waste oil in the tank is being stored in violation of U.S. Virgin Islands laws. Ref. No. 1,22,24 2. 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, the Virgin Island Group, and an unnamed group made up of one or more dioritic plutons. The Water Island Formation, which is late lower Cretaceous in age, consists of keratophyre and spiHates. 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; and the Hans Lollik Formation, which may be Eocene in age, and 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. Alluvium deposits are quaternary 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 Water Island time. 02-8902-40-PA Rev. No. 1 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 further east and west away from the pluton. 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 the formation. The Outer Brass Formation of the Virgin Island Group is mostly siliceous limestone, which overlies 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. The Tutu Formation is fine- to coarse-grained volcanic wackes, which are 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 are 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 delineation of these plutons is uncertain. Throughout the islands isolated dikes of quartz-andesme porphyries, andesine-hornblende porphyries, lamprophyres, breccias, and pegmatites appear. Folding occurred 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 tip 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. Ground water 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. TUT" 02-8902-40-PA Rev. No. 1 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 level ranges from 1 to 209 feet above mean sea level. Ref. Nos. 9,11,16 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 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 are stored on a cement floor at ground level. The lowest point of the waste oil underground storage tank is unknown but is assumed to be at least 6 feet. Depth to groundwater in Virgin Island Housing Authority (VIHA) well Nos. 1 and 2, which are located approximately 500 feet northeast of the site, is reported to be 56 and 60 feet, respectively. Therefore, the depth from the lowest point of storage to the highest seasonal level of the saturated zone of the aquifer of concern is approximately 50 feet. 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 10-3 to 10'5 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 02-8902-40-PA Rev. No. 1 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 commercial purposes. There are at least 41 wells within 2 miles of the site. Thirty-four of these wells are within 1 mile of 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 500 feet_________ Depth 150 feet___________ The nearest well is the VIHA well No. 2, which is located approximately 500 feet northeast of Texaco. 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 9. Identify the population served by the aquifer of concern within a 3-mile radius of the site. 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 3-mile radius is trucked into the area. Ref. Nos. 9, 13, 15, 18, 19 SURFACE WATER ROUTE 10. 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 potential exists for contaminants to be transported to surface water. There were some spills in the drum storage area, and there were no containment structures around the drums to prevent migration of the spills. TU' 02-8902-40-PA Rev. No. 1 The drums contain waste oil generated from automotive repair and maintenance activities. Air monitoring instruments indicated the presence of organic vapors in an open drum on site. Samples of waste oil from the Tutu Texaco Site were reported to contain TCA. However, the sample analysis results were invalidated because the sample holding times were exceeded. The waste oil may also contain small quantities of substances such as gasoline, kerosene, and degreasing solvents. Ref. Nos. 1,22,24 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, an intermittent stream that drains the Turpentine Run Basin, is 2.5 miles. There are a number of storm sewers near 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 slope is relatively flat with a slight slope toward the south-southwest. Facility slope is estimated to be 0 to 3 percent. Ref. Nos. 1,2 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 cannot be calculated, as runoff may discharge to storm sewers and the path of these sewers is unknown. If runoff follows an overland route, the slope of the intervening terrain could be as follows: • Elevation of waste area - 200 ft • Elevation at point of entry - Oft • Path length -13000 ft 200 ft - 0 ft x 100 = 1.5 percent 13,000 Ref. Nos. 1,2 02-8902-40-PA Rev. No. 1 14. What is the 1-year 24-hour rainfall? One-year 24-hour rainfall data were 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. 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 surface 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 from the site enters storm drains near the site. Since the point of discharge and the route of these storm drains are 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 qranti) 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 sensitive environment along or contiguous to the migration path (if any exist within 2 miles)? There are no sensitive environments within 2 miles of the site that lie along or contiguous to the migration pathway. Ref Nos 2, 7, 14 02-8902-40-PA Rev. No. 1 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 contamination 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 contaminants) detected or suspected, and provide a rationale for attributing the contaminants) to the facility. The potential for release of contaminants to the air is very small. Above-background concentrations of organic vapors were detected in a drum; however, no readings above background were detected in the ambient air in the drum storage area. The drums on site contain waste oil from automotive repair and servicing operations. The oil may contain small quantities of gasoline, kerosene, or degreasing solvents. Samples of waste oil from the facility were reported to contain TCA. However, sample analysis results were invalidated because the sample holding times were exceeded. Ref. Nos. 1,22,24 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 02-8902-40-PA Rev. No. 1 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 DIRECT CONTACT/ON-SITE EXPOSURE 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 not 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 02-8902-40-PA Rev. No. 1 PART IV: SITE SUMMARY AND RECOMMENDATIONS Tutu Texaco is an automotive service station located in the Tutu area of St. Thomas, U.S. Virgin Islands. The primary activities at the site are gasoline sales and automotive repair and maintenance. The area within approximately 1 mile of the site is densely populated and contains some commercial properties. There are large housing developments northwest, north, and east of the site. Beyond 1 mile, there are scattered smaller villages and towns. The densely populated and highly commercial town of Charlotte Amalie is located approximately 2.5 miles west of the site. On February 15, 1989, NUS Corp. Region 2 FIT conducted an on-site reconnaissance of the Tutu Texaco Site. A total of thirty-one 55-gallon drums were observed on the site. Twenty-five of the drums contain waste oil, two contain dirt, and four contain water pumped from a tank excavation. There are three 20-gallon drums and a few 5-gallon pails containing waste oil on site. In addition to the drums, there are a number of underground storage tanks below the site. An unknown number of these tank contain gasoline, and two of the tanks contain waste oil. There is evidence that the gasoline tanks are "not tight" (i.e., may be leaking - Ref. No. 23). The integrity of the waste oil storage tanks is unknown. The underground gasoline tanks and the drums containing tank excavation water are not evaluated as they are not considered to be hazardous waste under the petroleum exclusion of the Comprehensive Environmental Response, Compensation, and Liability Act(CERCLA). Samples of waste oil from the site were reported to contain TCA. However, the sample analysis results were invalidated because the sample holding times were exceeded. The waste oil may also contain small quantities of gasoline, kerosene, and degreasing solvents. 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. Currently, there is no permitted method of waste oil disposal on St. Thomas. Generators must store their waste oil, but the facilities are not inspected or issued permits. These conditions, combined with drum shortages and poor housekeeping, have resulted in generally poor waste containment at many of the facilities. The waste oil drums on the Tutu Texaco Site are not properly stored or contained. There are oil spills visible on the ground, and oil-stained soil was observed on the Gassett Property adjacent to the drums. There are no berms to contain the oil in the event of a spill. Underground tanks for waste oil storage were described in a preliminary investigation completed by the DPNR in August of 1987. Waste oil was being stored in these tanks in violation of Virgin Islands ' — - " —J " "u~ -1---- 02-8902-40-PA Rev. No. 1 considerations, a recommendation of MEDIUM PRIORITY for further action is provided. Because of the spills, stained soil, and improper waste containment, the potential exists for transport of the wastes to surface water and groundwater. The owner of the Tutu Texaco Site, Texaco Caribbean Inc., has been identified as one of nine potentially responsible parties in the contamination of groundwater in the Tutu area. In July and August 1987, ERA 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. Locations for the collection of environmental samples at the Tutu Texaco Site are limited. The only available soil near the drum storage area is on the adjacent Gassett Motors property. A number of the wells in the vicinity of the site are known to be contaminated with volatile organic compounds. As a consequence, there may be few wells available that are useful in determining whether hazardous substances have been released from the facility. Sampling of waste sources on the site is recommended to determine whether the waste oil contains hazardous substances. Efforts should also be directed toward further definition of the population using groundwater for drinking and toward determining the volume, construction, and integrity of the underground oil storage tanks. Sampling is not recommended if ongoing or planned removal actions or enforcement actions result in the collection of samples from the site by EPA or DPNR, or by Texaco Caribbean for the aforementioned agencies. ATTACHMENT A MAPS AND PHOTOS 02-8902-40-PA Rev. No. 1 TUTU TEXACO ST. THOMAS, U.S. VIRGIN ISLANDS CONTENTS Figure 1: Site Location Map Figure 2: Site Map Exhibit A: Photograph Log 02 8902-40-PA Rev. No. 1 UTU TEXACO SERVICE STATION VIRGIN ISLANDS } , ._-,..(,___ ..77- (QUAD) EASTERN ST. THOMAS, V SITE LOCATION MAP TUTU TEXACO SERVICE STATION ST. THOMAS, U.S. VIRGIN ISLANDS SCALE: r- 2000' FIGURE 1 IMLJS ;.>o:. 02-8902 40-PA Rev. No. 1 DIRT FILLED DRUMS 20 GLN. DRUM AREA SITE MAP TUTU TEXACO. ST. THOMAS. U.S. VIRGIN ISLANDS L FIGURE 2 IMUS CORPORATION ( NOT TO SCALE ) 02-8902-40-PA Rev. No. 1 TUTU TEXACO ST. THOMAS, U.S. VIRGIN ISLANDS FEBRUARY 15, 1989 PHOTOGRAPH INDEX ALL PHOTOGRAPHS TAKEN BY DIANE TRUBE Photo Number Description Time R3-P1 West side-Dirt pile 1300 R3-P2 Drums under overhang 1302 R3-P3 Tutu Texaco drum storage area. 1304 R3-P4 Tutu Texaco excavated dirt pile and pvc-pipe collection 1308 system. R3-P10 Tutu Texaco drums as seen from Gassett Motors. Note stained 1353 soil. IMUS CORPORATION :ev. ,o. 1 ~UTU TEXACO .HOMAS, U.S. VIRGIN ISLANDS R3-P1 February 15, 1989 West side-Dirt pile. 1300 IMUS : e v . o. 1 TUTU TEXACO JOMAS, j.s. , :RGI;; :;LANDS R3-P2 February 15, 1989 Drums under overhang. 1302 IMUS CZO^PORATTON ~UTU TEXACO "HOMAS, J.s. . :RGIN R3-P3 February 15, 1989 Tutu Texaco arum storage area. 1304 IMUS CXDRPORATTON ~UTU TEXACO ;T. THOMAS, J.S. V I R G I N R3-P4 February 15, 1989 1308 Tutu Texaco excavatea dirt p i l e and pvc-pipe collection system. IMUS TUTU TEXACO HOMAS, U.S. VIRGIN ISLANDS R3-P10 February 15, 1989 1353 Tutu Texaco drums as seen from Gassett Motors. Note stained soil ATTACHMENT B REFERENCES 02-8902-40-PA Rev. No. 1 REFERENCES 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 Turpentine 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, 1988. 10. Uncontrolled hazardous waste site ranking system, A user's manual, 40 CFR, Part 300, Appendix A, 1986. 11. Donnelly, T.W., Geology of St. Thomas and St. John, U.S. Virgin Islands, 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. Dacosta, 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, US Geological Survey Open File Report, 1973 TUT 002 02-8902-40-PA Rev. No. 1 REFERENCES (CONT'D) 17. Water Management Plan for the Public Water System, Prepared for the Government of the Virgin Islands by CH2M Hill. July, 1983. 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. Reed, DPNR, and A. Brochu, U.S. EPA Region 2, on 1/30/89 at 1400 hours. 22. Memo from L. Reed, DPNR, to Texaco file, RE: Texaco Violations, August 5, 1987. 23. Records of Petro Site tests performed on Tutu Texaco Service Station underground tanks Nos. 1 and 3, by J.F. Martinexand Cia., Inc. on July 18 and July 11, 1987, respectively. 24. Memo from Arnold Martinez, TAT II, to Carlos O'Neill, U.S. EPA Caribbean Office. January 27, 1988. Subject: Tutu Area sampling results. REFERENCE NO. 1 '-/ NU8 CORPORATION II 0398 02, - 9-901 Met" O?00 OOLX Tee JLXL«r. u. ram uuxi'-T^ f—r«.n. s 53" ^w"7 -- ^* * »«^ • +^m / xt* ^ **^ I " ' / " / v ^ 14 U«S DC4*\. W« U-_LX, c.u.r o . .^ _ J> UC O - ! - 3 • At .. 5/S 5 J^ TUT 002 <?f &-/<??&? _ "~ ^^ ^*"7—— JBMNM 01 -WO i -Z*J. V i "" ' *>" 15 2-S \\ t 2- • \-flD w~ r V) C Q S >-4 S- -f s i^y) ~Tc>vw »vxy(ar5 -. We. r r s 1 8 OG/? U.S. c -l-a ot-fi.j.g - TP^ "~p>Q p. - - @ VIRGIN (QUAD) EASTERN ST. THOMAS, V.I. SITE LOCATION MAP TUTU TEXACO SERVICE STATION ST. THOMAS, U.S. VIRGIN ISLANDS FIGURE 1 002 0426 TOSJ SCALE: r- 2000' REFERENCE NO. 2 REFERENCE NO. 3 Summary Appraisals of the Nation's Ground-Water Resources — Caribbean Region By FERNANDO GOMEZ GOMEZ and JAMES E. HEISEL G E O L O G I C A L S U R V E Y P R O F E S S I O N A L P A P E R 8 1 3 - U U N I T E D S T A T E S G O V E R N M E N T P R I N T I N G O F F I C E . W ASH 1 N G T O N : 1 980 U20 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES TABLE 4. - Water budget, in cubic hectometers per year (lim'/yr) and percent, for Puerto Rico (by West coast to Rio Grmnde ile Arecibo hmVvr Percent North Coast Province Rio Grande de Arecibo to Rio ie U Plata hmVyr Percent Puerto Rico South Province Rio de La Plata to Kio tlspintu Santo hnWvr Percent Patillas to Pnnct hm'/vr Percent Tallabo* to Guanicm hm'/yr Percent Lajas West Coast Valley province hnV'yr Percent hmVyr Percent Input Precipitation Streamflow Diversions »20 J7 0 I.2SO ~>.V4 1.030 14. H ii70 "vi2 ."i'JO 46.8 410 'it 6 :UO :W.5 so y* 60 175 25.5 745 100 72.8 :I60 2S.O 44 :I2 880 710 33 240 __ __ Output Kvapulraspiration Stream nulflow 'iround water loss to wetlands or sea liround-waurr withdrawals' T..UI Industry Irrigation 1.410 lil 3 >«>5 1176 15 7 10 4 a 104 34.8 1 3W) ~>8.S t>0 2.6 26 8 :!00 23.8 \»20 730 20 l.U 20 1.6 5 15 __ ISO 23.5 20 2.5 170 210 143 ~_"~ 8 60 100 15 SO 21 37 2 25.5 42.6 6.4 25.5 —— 120 S7 3 270 21.8 11 xo ^»20 74.2 63 46 40 32 1 1 10 8 __ __ 10 All ground water withdrawn was aitsumeil tu be Tor consumption since it is nut available for other uses. 1000 800 Public Supply (Puerto Rico Aqueduct ond Sewer Authority) 200 - Induitrioi S«tf S«»pli«d TOTAL WIT ™- *^ eirauw I9«S 1970 r»T3 I9M IMS YEARS 1990 1999 ZOOO 29 20 5 " ui >- 10 LISHT INOUSTMY ,--' ' OOMESTIC AND COMMERCIAL TOTAL WrfHOMWALS (EictodM Mlf-MMtM 1989 1970 1979 I9W 19*9 TEAMS B 1990 1995 2000 FII.I UK 17.-Water-use estimates. A, For Puerto Ric.i; public-supply data provide! hy thf Puerto Rico Aqueduct and Sewer Authority (modified fn.m Morris, 197H). B. For the U.S. Virgin Islands. TUT CARIBBEAN REGION province) and its offshore islands (Vieques. CuUbra, and Mona Islands) and for the U.S. Virgin Islands, 1975 U21 pnivince hm*'\ r Prrrenl Pueru. KK-n-O InU-rmr Puerto Kin* ppivimv UUnii tuial hm-Vvr Perrt-nt hmj'v r Percent ..niimwl IS Virifin l>un.i. Pu*-rin KK-HS ut't'shtiiv islan-l>- Vieques Culehra M<XIM St. I'nux Si Th<.m,i> 4 Si .l«hi. hmj/yr Peri-ent hmj'>r Perreni fim''\t Pi-rct'iil hm • \ i Pert-nil hmj \r perM-nl hm* vi Hrtu ril Input-—Continued Output—Continued 31.11 6.512 644 4.342 S9» lU.liti 64.2 3SS 5.U46 31. 24.0 S5.H 12 lu 16 4 UU 188 PROBLEMS AFFECTING USE OF WATER RESOURCES MANAGEMENT—PUERTO RICO 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), the 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- ning, management, and investigation of the water resources, the DNR, EQB, U.S. Environmental Protec- tion Agency (EPA), PRWRA, PRASA, Puerto Rico Sugar Corporation, and heavy water-use industries 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 established 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 net- work on the south coast and in northwestern Puerto Rico. PRASA. The authority is charged with development, construction, operation, and maintenance of water and sewer systems and providing adequate water U22 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES 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 methods to accelerate economic development, especially through industrial promotion and tourism. This agency must submit to ONR 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. VIRGIN 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 pollution, 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 WAPA at a date to be deter- mined by law. The transfer of functions has not been acted upon by the legislature, and WAPA 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 to 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- CARIBBEAN KEGIO.N ly" (Art. 8). Similarly, as to "artesian wells, tunnels, or galleries," (major ground-water developments as oppos- ed to "ordinary wells," which are defined (Art. 20) as 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 to 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 other factories, ferry boats and floating bridges, and fishponds. The economic importance of water-using in- 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 "in 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 Chapter 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 wells. Under Section 153 of Title 12, appropriation per- mits arv not required if pumpage is less than 2 m3/d for beneficial use. Under Chapter 3, Title 12, of the Virgin Islands Code, trees and other vegetation adjacent to watercourses are protected by law. This regulation protects the esthetic values of stream channels but results in a significant loss of ground water to evapotranspiration by the deep- rooted vegetation. A modification of this law would be necessary in order to exclude from such provision those watercourses 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 Mayagiiez 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. IjyggnejaL^the only areas served by sewers are those within the urlftan limits'nf towns. 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- 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- 67*X' 30' terior Guinea Gut Basin, where potential for ground- water development exists. IRRIGATION 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. WOO' 18*00' EXPLANATION Municipal (did wwta ita> •pond to 85*15' 86*00' 6T45' CULEBRA 1815' h- 18*15'30T ST. THOMAS '^^^^ <^C5^ ST. JOHN VIEQUES 6T4S' ST. CROIX FIGUIC 18.- Sobd-WMte dnpoMl ntM in the Caribbean Region. 0434 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 sea level over large areas (pi. L4). 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 (pi. IB), but there has been no significant in- crease in chloride concentration indicative of seawater intrusion. OPTIMIZATION OF USE OF WATER RESOURCES In general, until recent years the effort 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. CONJUNCTIVE USE OF SURFACE- AND GROUND-WATER SOURCES The greatest potential for conjunctive use of surface- and ground-water sources 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 inter-basin 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 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 system 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. Qualitative 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 use more water from the soil through transpiration. Archaeological sites, surface features, and historical notes *njtatf* that water was much more plentiful at now parched areas in Puerto Rico's offshore islands and in the U.S. Virgin Islands. SUMMARY The Caribbean Region consists of the Commonwealth of Puerto Kico (8,990 km*) and their S. Virgin (35QJcm2). It is among the mostrdensely populated areas in the wWld, will] an uvurull population ot approxirfiate- ly 3,200,000 people. Within the past 25 years the islands liaveundergone 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 and 24 hms/yr in the U.S. Virtrin Islands. These amounts would theoretically satisfy the total water needs of both areas, which are about 919 hm3/yr and 20 hmVyr, 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 hms. 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_ jprovide 10 percent. Excluding desalinated-water sup- plies in the U.S. Virgin Islands, ground water provides about 72 percent of the freshwater used. Of the 350 hmVyr ground-water withdrawal 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 hmVyr. 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's 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 TUT CARIBBEAN REGION L'31 will support only minor future development if effective management practices are not introduced. In the U.S. Virgin Islands, the most extensive aquifer is_the fragmented igneous rock, it contributes little 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 L/s 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 hms/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 REFERENCES Acevedo, G., Lugo-Lopes, M. A., and Ortiz-Velez, J., 1959, Occurrence of soil tumors northMMt of the Guanica Lagoon, Lajas Valley, Puerto Rico: University of Puerto Rico Agricultural Station Jour- nal, v. 43, no. 2, p. 103-115. Adolphson, D. G., Seijo, M. A., and Robinson, T. M., 1977, Water resources of Maunabo Valley, Puerto Rico: U.S. Geological Survey Water-Resources Investigations 76-115, 44 p. Anders, R. B., 1968, Reconnaissance of the water resources of the Central Guanajibo Valley, Cabo 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. ———1977, Ground water in the Lajas Valley. Puerto Rico: I S. Geological Survey Water-Resources Investigation 68-76, 45 p. Arnow. T.. and Crooks. J. W., 1960. Public Water supply in Puerto Rico: Commonwealth of Puerto Rico Water-Resources Bulletin 2. 34 p. Bennett, G. D.. 1972. Ground water along Rio Bucanaat Ponce. Puerto Rico, and effects of a proposed floodway on ground-water quality: Commonwealth of Puerto Rico Water-Resources Bulletin 11, 28 p. ———1976. Electrical analog simulation of the aquifers along the south coast of Puerto Rico: U.S. Geological Survey Open-File Report 76-4, 101 p. Bennett. G. D.. and Giusti. E. V., 1972, Ground water in the Tor- tuguero area, Puerto Rico, as related to proposed harbor construc- tion: Commonwealth of Puerto Rico Water-Resources Bulletin 10. 25 p. Black. Crow and Eidsness, 1976, A water management plan for St. Croix, U.S. Virgin Islands: Black, Crow and Eidsness, Inc., Con- sulting Engineers, Gainsville, Fl. Black and Veatch, 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 II, Ground Water appraisal: Black and Veatch Consulting Engineers. Kansas City, Miss., and R. A. Domenech and Associates, Halo Key. Puerto Rico. Bogart, D. B., Arnow, T., and Crooks, J. W., 1964, Water resources of Puerto Rico, a progress report: Commonwealth of Puerto 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., and-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 Agency, 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 Environmental 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, O. J., 1972, Water in St. John. U.S. Virgin Islands: U.S. Geological Survey open-file report. 46 p. Crooks. J. W., Grossman, I. G., and Bogart, D. B.. 1968. Water resources of the Guayanilla-Yauco area. Puerto Rico: Com- monwealth of Puerto Rico Water-Resources Bulletin 5, 55 p. Diaz. J. R., 1968-1974, Ground water levels in the south coast of Puer- to Rico (Guanica to Patillas): U.S. Geological Survey Data Release PR-I.San Juan, P.R. ———1973. Chemical quality of water in Cano Tiburones, Puerto Rico. A reconnaissance study carried out in 1967: U.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. REFERENCE NO. 4 ACAlSi SCIENCES • . *-. 7r »iH^ PO NYAS-3 vol.19 pt,l il^SteS^'* WteSB** TUT 002 0439 METEOROLOGY Ol: THE I'!RGl\' !SLA.\'DS 19 :- — " 5 "3 :» The nature of the shorter-period pressure variations in relation to the weather and the general circulation are discussed below under The Lpper Air and General Circulation, etc. PRECIPITATION Rain is the climatic element of most practical concern in the islands be- cause it is oiten insufficient to mature susrar cane in one or two seasons : a drought of six or nine consecutive months occurs every decade or so. caus- ing much hardship to the townspeople and small native farmers as well as to sugar and cotton estates and cattle ranches. Since early in the nineteenth century rainfall in the Virgin Islands has been measured in a unique unit of depth, called the "line". The reason for the adoption of this measure is not known. It is an old English measure, in which 1 inch = 8 lines (= 25.40 millimeters ). In Denmark they once used the Paris measure of 12 Linicn =: 1 Tomine (Paris inch) = 27.07 milli- meters = 1.0658 inches. 1 Paris line = 2.256 mm = .0888 inch = 1i44 foot, whereas the Danish ll'est Indian (or English) line = 3.175 mm = L3 inch. It is conceivable that as many of the residents were British this "line" was adopted locally from using English rain-measuring glasses or sticks graduated in eighths of an inch. Since the American occupation inches have been used. Accuracy of the Measurements The accuracy of rainfall measurements is a difficult problem in gen- eral, and is especially serious in tropical countries.* We have already re- ferred to the lack of standards in the instruments and observation pro- cedures at Virgin Islands stations, and here we must add that where the rainfalls are frequently light and the monthly and annual totals are small the errors of measurement are greatest on a percentual basis. The common practice of measuring the catch only once each 24 hours allows some water to evaporate from the gage before it is read, particularly in a warm windy climate. The use of a funnel is common and tends to cut down the evapo- ration. Where most of the rain falls at night, it is better to read the gage in the morning, and where it falls more in the day an evening observation hour is preferable : two readings a day would be still better, and best of all the use of recording gages or the habit of reading the gage after each shower. It has been shown that a considerable difference in a given * For a comprehensive discussion see Rrooks. C F . Need fur -.imversal standards for measuring precipitation, -nowfall. and snowcover. Traps. Meet. Int. Comm. Snow and Glaciers, Int. Assoc. Uydrol. B u l l . 23: pp. 1-52. Riga. 1938. 20 SCIENTIFIC SURVEY OF PORTO RICO STONE: 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 of 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 height of 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 indies. 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 records from ea; tremes would be inches. A rainfall The seasonal < in May or June much more prone on record indicat month; even Oct tions (see TEXT sections of St. C rainfall from no west, but from middle was agai shift in the relai south of east, wr peratures and h graphic effects. E. Taylor in 1888: 42) sugg 044 RICO . gage read each morn- to estimate the magni- that the results from ../hat lower than they observation at the vari- and at some stations , rht of orifice above the "lieved nearly all the een of the standard pendix A). The wind ie rain that should go 20 per cent too low vhere with shielded does not average over :ra' from the wind s t .^jhly equally to erlooked in practical '"creases as the wind vere storms, hurri- ugh wind sometimes of rain. Occasionally ad. Considering all _, ; the recorded rain- on the part of ob- results and largely tries and the reputa- '•".ervations as genu- of an efficient na- •d of inspections by •au inspections have annual rainfall about 35 and •liest years at these ial totals ranging 3LE1). If we had STONE: METEOROLOGY OF THE VIRGIN ISLANDS 21 miju-DC" js nnra SC - L t O ' M ' L t b Ficuu 2. Rainfall map of St. Croix, 1921-30. (From Shaw, 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 1909 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- "UT 0442 22 SCIENTIFIC SURVEY OF PORTO RICO cause an early book on the islands by Oldendorp (1777) 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 permanent 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 FREQUENCY OF MO.VTHI.Y RAINFALL TOTALS GREATF.R THAN SPECIFIED AMOUNTS, ST. CROIX Average of 3 stations for 63 years, 1852-1914 (From Ravn) Month January February March a? June July Aufut September October November December Number of yean with rainfall Over 20 linn (2.50 in.) 25 13 13 33 37 38 44 50 57 60 54 39 Over 40 line* (5.00 in.) 21 1 5 24 19 12 22 32 38 30 11 Over 60 lines (7. 50 in.) _ _ — 1 11 9 3 8 10 18 13 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 because they are now more forested. Indeed, the rainfall observations (cf. APPENDIX TABLES 2-6) lend no support to that notion. Orographic Effects The nun fail increases with elevation on all the islands, as residents and travetenoui readily observe and as one would expect. But rain-gage sta- tion«ltf«Bcking at high elevations, except Pearl, Mafolie. Liliendal, Wint- berff, ttftfl Dorothea. Shaw's rainfall map (FIGCRE 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 3000 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 H Xa TUT TEXT TABLE 5 AVKMACK RAINKAII. KOR EACH 10-YKAR PERIOD, 1852-1911 (IN INCHES)* "St. Croix, Virgin Islands" = (Cliristiunstcd's Fort + II ill* + l-'mlrrii-kslrd's K (From L. Smith) Period Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Year 1852-61 1862 71 1872 8lt 1S82 9lt 1892 1901 1902 11 Total Average for 60 years (1852-1911) • These are from the 1 90 2.11 285 2 78 2.16 2.52 , 14.13 1 2.38 same observations .60 1.68 .65 2 3( .33 IS! 10 1.15 .45 1.32 .31 1.12 .45 10.21 .91 1.70 used in TEXT 3.12 2.06 1.43 3.27 2.15 2.52 15.57 2.60 TABLES 19 to 553 3.35 4.16 322 633 4.26 26.90 4.47 22. here 3.76 3.86 4.48 3.97 4.60 3.40 24.08 4.01 converted to 3.51 3.10 3.37 4.06 5.42 2.47 21.95 3.65 inches from 492 4.18 4.25 4.62 4.58 5.40 28.11 4.70 the "lines 7.26 5.26 5.28 4 92 6.81 6.92 3645 6.07 " in which 8.16 7.80 5.11 7.50 5.47 4.68 39 38 6.56 rainfall 443 4.07 6.61 5.92 5 46 4.96 31.45 5 23 was measured 2.68 3.40 2.33 3.67 408 5.05 21.23 3.53 (8 lines 48.61S 43.00 44.86*\ 1 47. 50' > \4987 »7.62. 281,15 4689 — 1 inch). From "Reiwrts of the Virgin Islands Eiperimenl Station, 1911". t Kings Hill was omitted from the average! for Oct. 1878 to Oct. I88S, inclusive. 24 SCIENTIFIC SURVEY OF PORTO RICO \K: .UCV 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 feet) 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 rainfall 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 yards 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 are 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, orj?f^ Christiansted, jhe_avgragc annual raipfall probably varies considerably (up to 5 inches ?) from block to block: hence records taken at different 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 (FIGURE 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 normal rainfall,* which is just about sufficient for an annual yield of sugar • It it characteristic of the frequency distribution of either dailr, monthly or annual rainfalls, that the most frequent value (mmit) is generally much less than the average, and in some case* th« zero ralue is most frequent. cane, long the chief en discusses this problem low). Du Tertre and C the poor crops of 1841 1923 to 1924 were dui trary to the impressio evidence that the rain to century (see Foresi has not been scientific, show long quasi-perk rainfall. These undou enough to reveal any 1 near the critical limit f tuations are important understanding of the for the farmers merely attempts to forecast tl derived from analysis for long-range foreca solutions offered do nc plicability, however pr The most successful r places, none of which 1 The diurnal distribi greater amount of rait loe's observations at < Tidende", 1888. He gi NIGHT AND Month (ISSS) Julr August September * In lines; g lin The frequency of r; is probably not so proi heavier. O02 0445 I "O RICO STO.VE: METEOROLOGY OF THE VIRGIN ISLANDS 25 is of the writer: on sev- une, 1939 when the sum- 1 that any large cumulo- •nt of the wind over the the rain falling from it ^ of the island. In other lot fully enjoyed by the .urn This observation is idovic. the Aerographer 3n St. Thomas in 1939. :rease more than about n, but some of the lower ' e leeward slopes or in mon Bay, or Barracks E 2). In generally rainy ^tions of different ele- is ,.. Bay three rain gages -' from the water to the :rease in rainfall (AP- although they are all tow sensitive the rain- ason, within the hilly 'erage annual rainfall n block to block; hence not justifiably be corn- els of an estate often ^aroline; Adrian, Su- s of St. Thomas and s. Shaw's map of St. ugh short (10 years) "d, which should give me economic conse- all is well below the annual yield of sugar mthljr or annual rainfalls, »*e. and in <onw caxt the 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 Oldendorp 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. TSXT TAMX 6 NIGHT AND DAY RAINFALL, CHARLOTTE AMALIE, 1888* Month (1888) Total Byd»y Bynifht July Anfint September 38.4 77.2 69.0 26.1 S5.9 44.6 11.6 21J 24.4 * la lines; S line* = 1 inch. 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 26 SCIENTIFIC SURVEY OF PORTO RICO At sea the rainfall frequency is a maximum at 6 A.M. with a secondary maximum at about 10 P.M. The amplitude of this daily variation is pre- sumably smaller than the one observed over the islands, where the maxi- mum comes in the afternoon. It is very likely that the sea maximum at 6 A.M. 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 monthly totals and numbers of rainy days. The average rainfall per rain day (APPENDIX 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. J3owever. very heavy rains nn to 2 or ft it^h** in a day have fallei^pfen_in_jtig_dngst_rnonths.Jn the "rainy season", from ^lay to NovJjB3aigJgT_and more enduring tnunder and ^fjjgflf it times, are to ly *>x[yf"'o mum m^ry often: at least one shoiKlrtoae sort then falls almost every day. Heavy rains lasting as mujMPp Of 8hours, even with brief intermissions, are normally very rare, but paswge of a hurricane within ^OnrJ QQ mil^s ran rans»» mous rainfall totals (over 10 inches\ jnT^l-ty nr ______ —..-.-..„ ...^.._VJM_ in ,it.-/ ••• rwn frpm virtr?")"-""- tmuous downnoiirs, 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 STO.\'E: .METEOROL gage has been operated since 1 TABLE 12 and FIGURE 10) indi and also per rain hour for eacl fall during any 24 hours of tb teresting relation because in tl places we can assume that th< tabulated by the U. S. Weatlu basis for estimating the avcraii Since February 1940. the S< rainfall rates monthly from ra estates on St. Croix. An abstr and 8. Although the period of averages or extremes likely to study of the tables reveals a cl< rainfall and the maximum int 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 u the spring. This is a curious the greater frequency of hail the late summer and'autumn. < tensity of rainfall will actuall because of hurricanes. The im excluded, winter and spring .•- tensity as the autumn rains, br riods, as shown in TEXT TABL greater 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 the Any practical interpretatic Virgin Islands, especially on that a large proportion of the t (see TEXT TABLES 9 and 10). I rain gages and they augment significance for crop growth 002 0447 • PORTO RICO iitim at 6 A.M. with a secondary !e of this daily variation is pre- er the islands, where the maxi- ikely that the sea maximum at r shoreward margins, causing a itrly observations are available -eems to be recognized by the nenon. The daily double period 'oudiness (TEXT TABLE 17) and •juency inic situation is entirely of the ictical importance to know how last, how much rain falls per ;im rates of fall over short • obturations using recording ery recently, so we are forced ibservations which give only The average rainfall per rain 10) indicates some important seasons are characteristically i cumulus clouds of small or of blue sky (cf. TEXT TABLE overcast cloud deck with driz- •howers. which condition may rains up to 2 or 3 inches in a In the "rainy season", from ing showers, with squalls or .pected much more often; at nost every day. Heavy rains f intermissions, are normally i or 100 miles can cause enor- y or two from virtually con- :rricane weather adds greatly from the results of the re- 1 they have been in use. St. Thomas a recording rain STO\E: METEOROLOGY OF THE VIRGIN ISLANDS 27 gage has been operated since 1935. An analysis of the results (APPENDIX 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 24 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 24 hours", which is tabulated by the U. S. Weather Bureau for all its stations, gives a rough basis for estimating the average intensity of rainfall per day and per hour. Since February 1940, 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 rainfall and the maximum intensities than between the total rainfall 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 ifi 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 in- tensity as the autumn rains, but the maximum 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 9 and 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 TOT 002- 0445 28 SCIENTIFIC SURVEY OF PORTO RICO TEXT TABLE 7 RAINFALL INTENSITIES MEASURED AT STATION SCS No. 18 F. S. A., JOLLY HILL ESTATE, ST. CROIX, V. I. (From U. S. Soil Conservation Service) STONE: METE the vegetation and the t quickly evaporated by th Month 1940 February .March April May June July August September October November December 1941 January February March April Total Rainfall. inches 0.90 0.52 1.97 7.10 3.05 2.14 3.0! 4.19 7.47 7.1! 3.47 1.97 0.21 1.33 2.21 Total Duration, hours' IS. 02 1.92 6.42 30.00 8.10 5.07 12.37 12.65 22.45 25.37 20.25 5.02 0.80 1.13 9.45 Average Intensity, in./hr. 0.06 0.27 0.31 0.24 0.33 0.42 0.25 0.33 0.33 0.28 0.17 0.39 0.26 1.17 0.24 Maximum Intensity for Different Intervals 5-min. 1.00 2.00 3.50 2.00 5.00 3.00 7.00 4.50 5.00 3.50 2.00 1.50 3.75 10*min. 0.75 1.50 2.00 1.50 3.50 1.75 5.00 2.75 3.50 2.25 1.75 1.00 2.50 20-min. 0.35 0.80 1.40 0.90 2.80 0.95 3.40 2.80 2.40 1.60 0.90 0.50 1.40 60-min. 0.13 0.50 1.10 0.55 1.30 0.30 1.40 1.70 1.45 0.85 0.40 0.1S 0.56 1 20-min. _ _ 0.28 0.70 0.30 0.65 0.15 0.75 1.05 0.90 0.45 0.20 . 0.30 PERCENTAGES OF i CHF (Fr Month • Intensities of lea than 0.10 in./hr. an not Included. TEXT TABLE 8 RAINFALL INTENSITIES MEASURED AT STATION SCS No. 15 F. S. A, ANNA'S HOPI ESTATE, ST. CROIX, V. I. (From U. S. Soil Conservation Service) January February March April flay June July August September October November December Yew Month 1940 January February March Anril June July August September October November December 1941 January February March April Total Rainfall, inches OJS JM O.M US 1M Lit 1.17 1.7S SJ4 8.4J 6.05 2.36 3.67 0.19 1.05 2.48 Total Duration, hours1 2.77 17.18 4.92 4.20 15.05 4.60 4.23 7.4* 6.67 22.05 14.67 14.10 12.25 2.50 2.83 7.25 Average Intensity, in./hr. 0.13 0.12 0.20 0.37 0.19 0.34 0.28 0.23 0.82 0.38 0.41 0.17 0.30 0.08 0.37 0.34 Marimum Intensity (or Different Intervals 5-min. 10-nu'n. 20-min. 60-min. 120-min. _ 1.80 1.00 3.50 2.00 3.00 1.00 3.00 7.00 4.00 7.00 1.50 4.00 _ 1.50 4.00 .. 1.25 0.75 1.75 1.50 2.25 0.75 2.00 5.00 3.00 5.50 1.00 2.50 — 1.00 3.00 — 0.75 OJS 1.20 0.80 1.20 0.35 0.80 4.20 2.00 3.30 0.45 1.60 — 0.50 2.60 — 0.30 0.13 0.80 0.40 0.40 0.13 0.30 2.30 0.80 1.10 0.18 0.60 — 0.20 0.92 — 0.11 — 0.43 0.25 0.20 _ 0.15 MS 0.50 0.60- 0.31 — 0.1S 0.48 * Intensities of less than 0.10 in./hr. are not included. AVERAGE AND EXTRE: Month January February March April Mly June July A nrn» September October November December Year • These figures are not sums < year in the period covered by the \ 30 SCI EXT IF 1C SL'Kl'Ey OP PORTO RICO Evaporation The actual water loss from the ground by evaporation and by transpira- tion of plants is probably high, judging from the general weather condi- tions and from the measures of evaporating poiucr of the air made at the Experiment Station (see APPENDIX TABLE 8). Consequently, the roughly 45 inches of measured average annual rainfall in the Virgin Islands is by no means the equivalent for plant growth of 45 inches of measured pre- cipitation in rainier parts of the West Indies or in the southern United States. Thunderstorms, Squalls, and Hail Thunderstorms occur, as in Porto Rico, chiefly from July to October, according to the records at Christiansted and Bourne Field (TEXT TABLE 1 and 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, hMt these are merely gusts when the trades are blowing strongly. The Mjfttf TjLiiliiin sailor well knows that the squalls are apt to be especially violeafAMH&uigerous to boats along a coast which rises to high mountains immttlUS^ bade of the shore. //a? it nitty 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 few years, even several times in some years in which conditions are favorable for it. Much hail, with cold and rainy weather, occurred in Virgin Gorda in January 1833. according to Schom- burgk, 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. Xissen 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; perhaps thus more likely to be rei Chemical analyses of Station from 1911 to 1( tained an average of 9 nitrogen in the form of These figures varied g The amounts do not se appear to depend on tl that they are related to These chemical constit soil and the nourishmer Owing to the small ai ration, and the few pei 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 stocked with "mosquit spread chiefly by mos< of La Grange plantatio St. Croix was started but not on a scale suffic not yet been tried. Stor on which it was used f c Temperatures in th Porto Rican stations small land area availa' 0-4-3' "/CO 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. '. CROIX, V. I. for Different Intervals "in- 60-min. iro-min. 0 0 .'.90 »0 5 •tU 60 0.13 0.50 1.10 O.S5 1.30 0.30 1.40 1.70 1.43 0.85 O.li 0.56 TEXT TABLE 9 PERCENTAGES OF DAYS WITH SPECIFIED AMOUNTS OF RAINFALL. CHRISTIANSTED, ST. CROIX, 1852-1907 (From Willaume-Jantzen and Ravn) 0.28 0.70 0.30 0.65 0.1S 0.7S 1.05 0.90 0.45 0.20 0.30 Month January February March April May JUM July August September October November December 0-5 mm (0-0.20-) 67 64 66 55 56 46 55 54 45 44 48 52 > 20 mm "(0.79" or more) 5 3 4 16 10 14 10- 11 15 IS 128 > SO mm (1.97- or more) 00 0 2 4 3 2 4 4 71 2 Yew 54 a CHOIX, V. I. Different Intervals n. 60-min. 120-min. TEXT TABLE 10 AVERAGE AND EXTREME NUMBERS OP DAYS WITH RAIN, CHRISTIANSTED, ST. CROIX, 1852-1907 (From Willaume-Jantzen) 0.30 0.13 0.10 0.40 0.40 0.13 0.30 2.30 0.80 1.10 O.U 0.60 0.20 0.92 0.18 0.43 0.2S 0.20 0.15 1.18 0.50 0.60 0.38 0.15 0.48 Mtatk January ... February March H July Aoiat September October November December Mean 11 9 6 7 11 10 11 11 13 12 14 13 Blfhtat in any on* year 20 23 14 13 26 20 17 17 19 19 20 19 Lomrt in any one year 21 0 2 3 4 4 4 6 6 4 6 Year 12S 177* • Thoe Acnrei an not »rai of the columns above, but an lie extreme total* oo record for any < year in tbt period covered by the table. REFERENCE NO. 5 . , ·. ~ ' ' . ,. ·~UT!Jt'FtfJMETRlC SURFACE OF THE TURPtHTfNf' RUN BASIN AQUIFER IN· . ' . THE TUTU AREA, EASTERN ST. THOMAS. H,3. VHt'OIN.lSLANDS, SEPTEMB.ER 11, 19.81 :Pr:&pc11r11d in coo1rnr1Hun with !ch u · IJ.S. l'JfV!RfJNMENTAL PROTECTION AGENCY UNITED STATES ' GEOLOGICAL sliR 1IEY WATER· RESOURCES , INVEStlSATIOMS REPORT 88·4131 1988 PO'l'ENTIOllitETRIC SURF'ACE OF' THE TURPE•NTINE RUN BASIN AQ{)IJ!'ER IN THE TUTU AREA, EASTERN ST. THOMAS, U,S.. VIRGIN ISLANDS, 8'EP1'EMBER- ·11,-~19a7--· - ·. · - ·•·~- .. -.- - -·- By Robert P. Graves and Ralph Gonzalez Gt:oun<l-in1ter l(~Vels in t_he 'l1u-rperltine ·Run basin aquifi~r, in eastecn St. Thomas., weT-e mea.sured in 32. wells on .S@ptember 11, 1937 and a potent.ivi,1etr:'c su,rf.a.ce map was p·repared •. '£he a].tltude of all well::. was refure.nc::'e<l to knoWn lan.r.! surface altitude bench:ioark-s by use of a level ·survr.,y inS-tL·um•Jn':. Tht~ potentiomc.tric sui-·fat:~ map Wij.3 prepared by the U. s, Ueologic-:,..:. Survey. ifl co•-p~pation with the U.S. Environmentaj, Protf:!ct."lon Agunc:;:. Fraotureod volcanic roch;·· un<J,.arlie Turpentine Run basin anil are loca}l-y O'fl:~:la Ln by alluvial deJ)oslts (Donnelly, l 959). The ae '.lvial c1,_e1;0!1it:'l cm1 range to t,O feet in thickness. Gt"ound water lri the Turpentlne Run t>aslJ\ occurs iri the fractured volcanic rock and alluvial dep•:)s·~P.s under War..et··table con~}.it.lons (JordaflJ 197]). The alluvial do;:>os.L ts a r:;:,. eons .i..dei;·l'.:!d to bu Yty<l.r:a9.Licall:t ,. '.oonnecte.d with tt~I:', f r:act;ured vo).c,:rntc ru,::k. Vlell <levths. iri the ba$in c;an range from 55 to J25 feet belC!w hmd surfac:~,. Se•1eral wells- •1ur.e being p·~mped, 6r pwnping had just termin.;1ted, wHun th_e ,,ni.ter .ltc•.;als were roe.as.ured ( table l). '!'he.st! water levels reflet:t ·a pu•n1Jing or recovo-r.y C.Qndi-tion; therefore, static water.·lev:el crmd i t::ions thcou,ghout the 'l'uqrnntine Rlln basin ilt the time of mea-su.n.~ment Cltn:int ~>c as.swiJeJ. Ad:'i 1.:.lonnl information- ubout g·,:o·~n<l·water· levels in thn area of stud~,: is .:wid.lable. f:rom t·he U,S. Ge9'1ogical Survey, W,c,1tet· Resources ')i 11ision, Gc.rr.iblJean District o.ff_:i.ce .. in San Juan, J)uer'.to Rico, Tel. (809.) 7,,q_f:]/16. SELECTED REFERENCES ·Jonnelly, T.',.J,, 1')59, Geology 1Jf St. Thomas and St. J•hii, V.i.cgin ~slm~'.13: U,niu.blishe<l Ph.D. dissertatiori, ~Prinoeton 'Ji1ive,sity, 179 p. ;,_:r-aghty t~::-MiJ.ler, lnc., .l,98J, Report on cutce.nt gL'QUn<l watut' c.:or.ditions 'i11 the 1_;,s, Virgin !sld.nds: Prepat~.d ft?X thB government cf the U.S. \'ii:gin lslawh: L;e-par:tment,of Con~er 11atHin ltnd C_l:1turul Aff,1i.rs, 8G p. J(frd;m, D,,.C. <Hid Co:,:'1.a:r, O.J., 1973, A survey .of the water resol,lrces of St. 'hicnas, \'irg.in L;lands: U.S. Gc9Io8.Lc~l S\!-rvny open-fi'h.! ri· ,_f}A'PO,r[, :J::i p. t1t:.:!v-eris, K.E.> G6meZ-C.:6rnez, F., and A'l_ice4, J, 1 l'tJ.8--1, Water wells in the 1.,.:._s. Virgin Islands_J, .. Pt.. lj St. Thomas:, lJ.'S. Geologlc,'11 Survey Op•n·File Hepurt 82-82, Well nuniber . 01 02 OJ OL1 05 06 07 0(1 '' ' ' "' 16 21 n 23 26 l.l 28 '1.9 JC :o ••v Table 1. Description of wells and September 11, 1987 water-level measurements In Turpentine Run basin, St. Thomas, U.S Virgin Islands [ootum 18 moan sea Jovel. Abbreviations; hyphens, data not available; <Al}, uu1;1pocted rocovarlng love!; (PL), sua-peoted pumping laveD Well identification number ! 82 02A0611 ~, 3 5 800 l 8'.c026061, 5 35800 182025061, :,JS800 18 ::o 18061, 5 35900 lH;.'.Ol 7CfJ.!15'35900 182010061,5J59CO t 8'..'.0160(Jii51,00CO ' 8'.'. Cl)() &l1~i1100(JQ ; :i :.:c 11.:: 0&11 '.i 3 ·1,,oc 1H20",/06115·\ l ! :;u 1 :J,2WJ8i)(,t,5] 1200 : ··,?.Ol1006l,'.:.J l l10U : !fl.()!1'.)0f.!15](:f)CJO ;. 2, ;· '!2 1)11011 :i ·1 t .seu : ;,L_ 'l'.1 .,, ::(;,. ~:1 UW'J ~31.)2~J06h53:WGO t820iu0&.',.'.1]~ 1)f!0 18201006/iSJ '. 'JOO 18?.0~60~1!1~)]:2!)00 '. 82ql 70(Jl,_:.,]'!.2tH) : O~O~'. ~ GUli)JLSOC ~ 020~8("1.J/1'.}]28'.)r) ~8201 ?~;f)/1,JJJ0Q0 18201 BUG,,;~ JJl 00 l820180M5JJ200 ;32019061,5]3300 ~ 8201506lf532700 '. O'.W l fJQ6/1.532900 l s:W l 5061,5:JJ000 1820l l,06Li5 32900 l.82012 06115 J l 1100 : -~. ~: 00906115 J 1 JfJO '. A 200306/1 53 i. ~. S'J l .81 91, 'iDbi1 5:'. 5 J '._\ ,-, J '. :1 ', l ,-. I . , Well name !-1r1rio Bryan \l'eU II~ ~far Lu l.\ryan !,;ell /i2 ~lat' 'o Br van 'o<,l] 113 :..0ckhar t '.,iel l Ill Lockhar_.t Well 112 Lockhart Wel: !IJ '.~r >(' I< h<i r r '•k• I ~ rl ~J Dl'111i' r:1 W1•Ll \IHA ¼pl: Ill VULJ\ 1~t~'.1 i/2 ·;:HJ. \,'r,~: tJJ VI!L\ ',.;p1_l /IL1 '.'i.llnr.~ •~·1~t: f.i~1r ·,.;:nd-, '-'i.,1?:1 ';\.'II~! !~z1in l'i'ni.l Ill ';Pfl/2 t:i:_;_.'..n 1..Je:; II',' Gerw E;g:: ~; 'Au~ i 1• l E. \t.er•~ •..;e!.1 O~;bun1 Han,ey \.:ru,;hv,· ·,,c:l Bak(''.·:,; '1if' '. '. r>Pgu: ~·k·,,;s 'Aid: 'I' '.;:·1.1g1~r: Mo:c•rs >h:l;. i; Creger Mot.or.,; Wd I 1FJ Cre~e~ ~otors Wa~l ~4 R's & A Corp We",l 01 E 1 s & A 1..'.orp \,j@J.1 i.12 E's & A Corp Wel.~ liJ E I s & A Curp Well /1!1 1"ranc:ois ~.a I'~ace L. S:nLth ~\al.Lhi.a~; ?arricgton 'A!-'!'..l ,, ' ". Pu7' 1 i.-- WP 11 /n; .! ' 'I Jep(. o: Ag1· Lculture Ani:nal Shelter Year drilled 1918 \ {' ., ., ~ ) I I 'I _; . --~ ·, ·- 1%0' 8 ~- 960 1 c; Depth of well (feet) : /10 ·v· ,, ,, .. ,, ~,) ' Dopth of casing (feet) ' ' ,, I '\ i' ·1,1, Water level; Water below land ! level Construction SU.l't'Uce i altitude (feet) (feet) 11 209 10 :l08 09 18] UH l 8!1 0) lUJ or, l 8:l 0~ iHJ l ', I (HI,) Opr•n h" Lo '.)6 I I 'I 'Jpon hu ! 1:.• r,o 1 ,.,. . ' ' I ) ~ ! i ~ I ' h" " ' ' ' . ' ,._ .... ,·,;,nn hv -~ ,, '}9 /. l') I,' [>f, • I h!' ~I' :n : 6 •1 I 'I ' ~, l '.(·; ,;, : ') ' ' 1·· :, ' '' 'H': 1~ l -h )!)• .. ! •c '. f}l/ )J. ,:.;s :J~\ '.OB :ui ' ,,. . ' . ., tl(1 '. 20 1.ZB 18 ! ')$ 19 lQl (1 : ,_; () .,. .'.0 ,U /·''._' '" - ' BC : J JC 05 Ltnd autfa.ce •ltitudo (r1et) 215 220 218 l92 19:! ',' , ',. ·, )'J 'f', \ ' > C (j (l 9 6e'OO' 16""'25'~-------------""'i""'--------------"'.,=.~,-------------=..=-----, ea00l5' e-40~• ft.4°60' ,o 0 I 0 2 • VIEST ENO 6 MiLES 6 KILOMETeRS ~ ~ OWt..OrTE Willer ,-.'-' Jaland 0+ ,.<' ~'\• V ! I ~ I 1w11·-~-----------~--------------~--- -----------'------' -?·--1:JO- ---··--... Map of Sr, Thomas showing the study area, EXPLANA:ION POTENTtOMETA:lC CONTOUR - Shows 11/titud'J of water tablo In faot. Dashed whero approxirnattdy locatud. Qverlod (?) whete locatlr1n Is l)rJCor!uln. Contr;ur lntarval varl1.1b$a. Oaturn i!l moon soa lovul. WAT~A-LEVE\. l)ATA CONTROL POINT - Open number l:s 1ho well numb'Jr uhown oti table 1. llumbar In parentheses is the altitude of wator le vet In !eel. Datum la moan sea level. BASIN BOUNO~AY :,w• 0 Q, 1--r-..L..,.., -_,,.1.L>-....,.1 _,.,,, __ ,,,_. --..c' u 0,6 ... ~ .. -----·------~-----------"--------------------,;__--~---------- ,--:\ · . .'i\l. .'jl)fll/S,V .. ~.:; -.\iGW3 0-!VJOION , . 1 MILE t ,. ,J 1 KflC',IAETEA Man,grove :/.-i¾--'c,c\b-CS..,,.....,+-i--'-",---+-~- La~ ···O D CLIMATOGRAPHY OF THE UNITED STATES NO. 60 Climate of Puerto Rico and Virgin Islands TUT 002 0454 noaa NATIONALOCEANICANO y ENVIRONMENTAL/ NATIONAL CLIMATIC CENTER ATMOSPHERIC ADMINISTRATION/ DATA SERVICE / ASHEVILLE. N.C. REPRINTED JUNE 1982 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* F or 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 underground 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, hall 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 QM£r_aphic_JLifting of the moisture laden air^ over the hilly terrain of these islands is~the~most frequent cause_of^jralnFaTI. However, due to the smaller elevations"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 amounts. On St. Thomas and St. John, on the basis of the limited data available, anmigj average^ of hefajeen_40_and 60 inches ^p_pear reasonable. On St. Croix there is a more noticeable variation from place to place. This Island has the greatest annual rainfall, in excess of 50 inches 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, baMMI on a few known-to-be reliable stations, ranges from a little less than 200 days annually at the higher rainfall stations to less than 100 day* annually at the stations with lowest rainfall. As in Puerto Rico, one of the most striking features 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 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 6A°50'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 of only about 20 square miles. It is also the least populated. St. John lies between latitudes' 18°23'N and 18°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°41'N, and longitudes 64854'W and 64°34'W. The Island extends some 19 miles from east to west and 6 miles from north to south. Topography; S_tj._Thomaa_haa_4n__extremely irregular ^coastline and is very hilly with practically no flatland. ~TKe~nTgnes t "hills are generally found near— the- center 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. This results in rather steep slopes over all the island, so that rainfall runoff is quite rapid and there are_np manenfc «t™"»n ftr r™»r« ————————— Like St. Thomas, St. John has an extremely irregular shoreline and a very hilly topography. It has a number of peaks over 1,000 feet, topped by Bordeaux 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 0457 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. Thomas and St. Croix has helped alleviate the water shortage but water still remains a significant factor in the development of the island's ecooomy. 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 REFERENCE NO. 6 TUTU WELL SITE POTABLE WATER ALTERNATIVES REPORT ANNA'S RETREAT, ST. THOMAS, U.S. VIRGIN ISLANDS Prepared For: carlo* E. O'Neill, P.E. OSC Luis E. Santos, OSC Air and Hazardous Substance Staff Caribbean Field Office U.S. EPA, Region II Santurca, Puerto Rico and Bruce Spragua, Chief Incident Response and Prevention Section U.S. EPA, Region II Edison, New Jersey 08837 Prepared By: Rodolfo Hafner, TAT II Jaaas Manfreda, TAT IX Region II Technical Assistance Tea* Heston/SPER Division Edison, New Jersey 08837 December 1988 002 0460 appear to be sufficient land available to increase the cistern volumes laterally. The only way the volume could be increased is by making deeper cisterns. This operation would require the shoring of the existing homes and apartments, therefore, the possibilty of structural damage to these residences. 2.0 SITE DESCRIPTIOM AMD CONDITIONS 2.1 Site Background and Conditions The Tutu Hell site is located at the eastern end of the Island at the Anna's Retreat Section of St. Thomas (see Figure 2-1 page 5). Most of the wells are used for public drinking water supply. The wells appear to be drilled into the Turpentine Run aquifer. On, or about July 7, 1987, Mr. Eric Tillett, contacted the U.S. Virgin Islands (U.S.V.I.) Department of Planning and Natural Resources (DPNR) regarding an odor emanating from the raw well water on his property located at Anna's Retreat, St. Thomas, U.S.V.I. On July 16, 1987, the OSEPA received a request from the DPNR in St. Thomas, for sampling and analyses of several wells in Tutu. On July 21, the USEPA and its ~ Technical Assistance Team (TAT) contractor, Roy P. Weston, Inc., mobilized to St. Thomas, to perform sampling on the drinking water wells suspected of being contaminated. These wells were also reported to have a strong, unpleasant odor and were found to be contaminated with hazardous substances. The EPA and its Technical Assistance Team (TAT) in coordination with DPNR, initiated sampling of wells in the affected area in July 1987. The test results showed the presence of high concentrations of gasoline and chlorinated organic compound*. Pour wells: Elgin, Pour Winds, Harthman, and Virgin Islands Housing Authority (VIHA) were closed down by order of DPNR due to high VOC concentrations. Several of the wells in this area are major commercial well services used for public drinking water supply, therefore, the incident was classified as major, and the DPNR Commissioner requested the EPA to assume the role of Lead Agency. The well locations can be seen in Figure 2-2 page 6. A Texaco station, located opposite the Tillet Well, is suspected as a possible source of contamination. A Petrotight test conducted on the underground storage tanks at this facility indicated leaks in two of the three tanks. These failures may have contributed GREAT NORTH SIDE RED HOOK FRENCHMANS BAY ICURZ 2-1 ( ITS LOCATIOK MAP ! ST. THOMAS ,' .S. VIRGI1I ISLANDl SPILL PREVENTION A EMERGENCY RESPONSE OMSION CARLOS O'NZXLL •vk iCFTedumiov lac. CC JofcOKW * Ioc_ BCJOUTCC AppUcaciOfM. Inc. Cco/ Raourc* and Cirnnwi^caai Ibxtcoto^r Imcnuuaaal. lac. TATMd R. BAFNZR 13.4 •13-2 •14 r«io • 18 -NEW 2.3" NO. WELL NAME NO. W5LL NAME 1 2 3.1 3J2 3^ 4.1 O 4.3 9 8 7aa 1011 BRYANS BOORIGUES BAR7BVAN BAKERY BARTH1UN BAKERY RARTHkAM BAKERY GENE EGUN 1 GENE CCUN 2 GENE ECON 3 BARVETS ST£CL£*S MATHIAS'S SMITH'S FRANCOIS THiETS ftiMSEY-S r^g^t/imr i vi 12. 1 12JI 13.1 13-2 13.3 13.4 14:s 18:7.i 17^ 17.3 18 18 it* •» » T 4 WINDS 1 4 WINDS 2 VTHA 1 VBA 2 VIHA3 VIHA 4 ALPHA LEONARD OEMITRI OENCH OEVCON 1 OEVCON 2 OEVCON 3 OEOf LOCXHART ,^^ __RED HOOK TUT 0463 SPIU.?*SV€NTICN4 »eS?CNS€ OMSJCN .Inc. CARLCS O'NZZLL ifXGURg 2-2 WELL LOCXTXOH MA? 3TU ST. THOMAS U.S. VT3USIK ISLANC: to the groundwater pollution problem, resulting in the contamination of nearby veils. Another suspected source of contamination is the Tutu Esso gas station. This facility stores vaste oil in an underground storage tank. The facility has had problems in the past with leakage from their underground gasoline storage tank and is suspected of using solvents in the mechanic shop. At the time of inspection, the nature of the problem had not been determined. Both the Texaco and Esso gas stations are upgradient from the affected veils vhich are being supplied with vater. EPA continued its efforts tovards the identification of; affected veils in the area, customers vhich had received vater from contaminated veils, and possible alternate vater supplies and remedial action alternatives. A testing program of veils located outside of the knovn area of contamination vas conducted to evaluate those areas as possible alternate vater supply sources. Sampling of cisterns served by the contaminated veils vas also performed. EPA directed the Emergency Response cleanup Services contractor (ERCS) to; clean and disinfect the five (5) cisterns vhich had tested positive for PCE, modify the existing home plumbing, disconnect the contaminated veils, and dispose of the contaminated vater. At EPA's direction, ERCS also contracted a local vater hauler to deliver uncontaminated drinking vater to the cisterns by tank truck. A veil sampling program vas established by the EPA to monitor the veils at the Tutu site for a one year period. Nine potential responsible parties have been identified. These facilities included three gasoline service stations, tvo vehicle maintenance repair shops, two territorial government agencies, 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 from 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 Cec-looy-iH- •St. Thomas is the most northvest island of the U.S. Virgin Islands and the second largest. The island is approximately 14 miles long and 2 to 3 miles vide and has an area of 32 square miles. The land surface is almost entirely sloping and extenc 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 gradient. The general appearance is a panorama of steep interstream spurs an rounded peaks. Flat inland 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 relatively gentle topography consisting of rolling hills in a basin surrounded by steep slopes and sharp ridges. The Tutu Formation, the youngest rock exposed on St. Thomas is composed almost entirely of angular debris derived from the Louisenhoj Formation (an older volcanic formation) and minor limestone debris from thin limestone deposited contemporaneously with the Tutu Formation. The rocks were subsequently tilted to form a northward- dipping homocline. Dips range from 15 to 90 degrees and average about 50 degrees. Locally the formations are overturned. The permeable zones that these rocks once may have had after deposition have been destroyed by metamorphism or by deposition of minerals in pore spaces. Groundwater movement is now limited to openings along joints and fault zones. The homoclinal structure is cut by sets of faults trending H 45*W, N 55*B and north. Three well-defined joint sets parallel each of the major fault directions. The valleys of the island have similar trends and are apparently the result of selective erosion of rock weakened by faulting and jointing. Prime zones of groundvater availability, therefore, follow the valleys. Small alluvial deposits ranging from Pleistocene to Holocene in age, lie in the valley of Turpentine Run in east-central St. Thomas and the larger coastal embayments. The alluvium of Turpentine Run lies 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 the 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 Mariendal to Mangrove Lagoon in the lover basin. The alluvium extends out under the lagoon near the mouth of Turpentine Run. Although composed predominately of fine-grained material, the alluvium readily infiltrates streaaflow when the groundvater 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. Some coastal embayments headed by intermittant streams contain small deposits of alluvium similar to that of Turpentine Run. n*yi«M thickness of these deposits is estimated 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 interfingers with calcareous sand and at times contains lenses of mangrove swamp deposits. Therefore, the deposits are of minor significance as sources of water11.'1' 2.3 Rainfall-^- "Rain is the only natural source of fresh water to replenish the water resources of the island. Rainfa] is seasonal, with a rainy season in late summer and early fall and a secondary wet season usually in May. Nearly half the rain falls during August-November. Raj.ns exceeding 1 inch in 24—hours eom^ «•»* nr **vm*^ feimes~]a_year. Fmir T,n 1^ in^**^* ~f r«<™ f«n^ in a A hourjgeriQd atyout once every 2 vears in large atorma. xnese rains can occur la any month, but are more like during the hurricane season (August-November). About SOpercent of the time anpui*1 Mtng«n is between 40 50~incBes; Less tnan 10 percent of the time annual rainfall is under 35 inches, which usually means a major deficiency during the normal wet season and drought. The cumulative departure from average and the 10-year running average of rainfall shows that at this time of writing (1967) the island may 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-term decline of about 10 inches in annual rainfall since the peak of the surplus rainfall period in the early 1930's. The most severe droughts on record oeccurred in 1964 and 1967, when only 27 and 24 inches of rain fell, respectively. Areal distribution of long-term rainfall, is controlled by topography and the prevailing easterly to northeasterly winds. However, individual storms may or may not show the effects of orographic control or prevailing winds and the areal distribution of the storms can be very irregular".I1' See Figure 2-3, page 10, for average yearly rainfall. 2.4 Sampling Results The Tutu well site has been sampled repeatedly over the last ten months and found to contain definite contamination. The initial assessment was conducted in July through September of 1987. Subsequent sampling and analysis has proceeded on a monthly basis. The initial assessment considered 26 veils and approximately 50 cisterns. Of these veils and cisterns; 24 veils and 5 cisterns vere found to be contaminated. The 5 cisterns vere cleaned and disinfected by the ERGS contractor. Subsequent monitoring has been considered for the 24 veils that shoved some type of contamination. Table 2-1 pg. 12, lists the veils included in the current sampling program. Tables 2-2 and 2-3 , pages 13-16, shov the volatile organic analysis results of the contaminated veils and give the highest concentration of organic contamination found during the last six months. The sampling, and most of the preliminary Photovac portable GC screening, vas conducted by the U.S. EPA Region II TAT. Drinking vater laboratories have performed formal analyses to verify the photovac screening results and to cover the entire spectrum of possible hazardous contaminants. Although, the concentration of these contaminants fluctuates monthly, it is noteworthy that the major contaminants have been 1,2-trans-dichloroethylene (DCE), trichloroethylene (TCE), tetrachloroethylene (PCZ), toluene (TOL), benzene (BEN), tertbutyl methyl ether (TBME) and various metals. Their high concentration in four veils; Tillet, Harvey, Smith and Steele has been evident from the initial assessment. These veils shov concentrations of volatile organic* (VO) in excess of 1,000 ppb. The major and most consistent contaminant appears to be PCE. The Tillet veil has also shovn very high DCE and BEN contamination. Four other veils; Francois, Mathias, Four Winds, and Elgin; vere confirmed to have >50 ppb vocs. The last confirmation analysis conducted during October 19t7, included the entire Hazardous Substance List (HSL), (consisting of approximately 150 chemicals). At that time, significant levels of TBME up to 470 ppb, and methylene chloride up to 120,000 ppb vere detected. Some samples have also shovn traces of vinyl chloride, chloroform, 1,1,1-trichloroethane, bromodichloroethane, xylene, and ethylbenzene. Finally, the HSL analysis also shoved the presence of 11 TABLE 2-1 CURRENT WELL MONITORING PROGRAM AND CLASSIFICATION AT TUTU WELL SITE 1WIK CLASSIFICATION OPEN/CLOSED 1. Dede Public Open 2. Steele Private Closed 3. Elgin fl Commercial Closed Elgin f2 Commercial Closed Elgin 13 Commercial Closed 4. Four Winds Commercial Closed 5. Smith Private Closed 6. Bryan Commercial Open 7. Harvey Private Closed S. Tillet Commercial Closed 9. Harthman Estate Private Closed 10. Devcon fl Commercial Open Devcon f3 Commercial Open 11. VTHA fl Institutional Closed VTHA 13 Institutional Closed 12. Dench Commercial Pump/No Power 13. Ramsay Private Open 14. Harthman Crusher Commercial Closed 15. Alpha Leonard Private Open 16. Francois Private Open 17. Demitris Commercial Open 18. Rodriguez Auto Private Open 19. Harthman Bakery Commercial Closed 20. Mathias Private Open Definition of Classifications Private: Wells which serve one or two houses. Commercial: Wells that are used to yield water for sale. Institutional: Wells owned and operated by a non-profit institution or governmental agency. Public: Wells that are for public use. 12 REFERENCE NO. 7 FISH AND WILDLIFE SERVICE LIST OF ENDANGERED AND THREATENED WILDLIFE AND PLANTS (50 CFR 17.11, 17.12; As shown in Code of Federal Regulations, Volume 50. Revised as of October 1, 1983; 48 FR 46057, October 11, 1983; 48 FR 46331, 46336. 46337, 46341, October 12, 1983; 48 FR 49248, October 25, 1983; 48 FR 52742, 52746. November 22, 1983; 49 FR 1058, January 9, 1984; 49 FR 1994, January 17, 1984; 49 FR 2783, 2786, January 23, 1984; 49 FR 6102, February 17, 1984; 49 FR 7334, February 28, 1984; 49 FR 7394, 7397, February 29, 1984; 49 FR 10525, March 20, 1984; 49 FR 14356, April 11, 1984; 49 FR 21058, May 18, 1984; 49 FR 22329, 22334. May 29, 1984; 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, August 7, 1984; 49 FR 33885, 33892, August 27, 1984; 49 FR 34494, 34500, 34504, 34510, August 31, 1984; 49 FR 35954, September 13, 1984; 49 FR 40038, October 12. 1984; 49 FR 43069, October 26, 1984; 49 FR 43968, November 1,1984; 49 FR 44756, November 9, 1984; 49 FR 45163, November 15, 1984; 49 FR 47400, December 4, 1984; 50 FR 1056, January 9, 1985) S--J8 101:1501 Titfc SO— Wildlife and FtohcriM within the meaning of the Act. Thus, dif- cies $ha|| CHAPTER I—UNITED STATES FISH AND ferently classified geographic populations WILDLIFE SERVICE. DEPARTMENT OF of the same vertebrate subspecies or spe- * identified by their differing boundaries, even though the other two columns are identical. The term "Entire" means that all populations PART 17—ENDANGERED AND THE INTERIOR SUKHAPTEM •—TAKING. POSSESSION. TRANS- PORTATION. SALE. PURCHASE. BANTER. EX- PORTATION. AND IMPORTATION OF WILD LIFE THREATENED WILDLIFE AND PLANTS AMhorttr Pub. L. 93-205, 87 Slat. 884; Pub. L. 94-359, 90 Stat. 911; Pub. L. 95- 632, 92 Stti. 3751: Pub. L. 96-159. 93 Stat. 1225; Pub. L. 97-304, 96 Stat. 1411 (16U.S.C. 1531 etseq.) (Amended by 49 FR 21058. May 18. 1984; 49 FR 22329. 22334. May 29, 1984; 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, August 7. 1984. 49 FR 33885, 33892, August 27, 1984: 49 FR 34494. 34500. 34504, 34510, August 31. 1984; 49 FR 35954. September 13, 1984; 49 FR 43968. November I. 1984; 49 FR 44756. November 9, 1984; 49 FR 45163, Novem- ber 15. 1984; 49 FR 47400. December 4, 1984; 50 FR 1056. Jawary 9. 1985] §17.11 EMa^tntf aatf tkrwtnrf •tUifc. (a) The list in this section contains the names of all species of wildlife which have been determined by the Services to be Endangered or Threatened. It also con- tains the names of species of wildlife treat- ed as Endangered or Threatened because they are sufficiently similar in appearance to Endangered or Threatened species (see JI7 .50 et sea..). (b) The columns entitled "Common Name." "Scientific Name." and "Verte- brate Population Where Endangered or Threatened" define the species of wildlife throughout the present range of a verte- brate species are listed. Although common names are included, they cannot be relied upon for identification of any specimen, since they may vary greatly in local usage. The Services shall use the most recently accepted scientific name. In cases in which confusion might arise, a synonym(s) will be provided in parentheses. The Ser- vices shall rely to the extent practicable on the International Code of Zoological Nomenclature. (c) In the "Status" column the follow- ing symbols are used: "E" for Endan- gered. "T" for Threatened, and "E (orTJ (S/A)" for similarity of appearance species. (d) The other data in the list are non- regulatory in nature and are provided for the information of the reader. In the annu- al revision and compilation of this Title, the following information may be amend- ed without public notice: the spelling of species' names, historical range, footnotes, references to certain other applicable 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 changed without following the procedures of Part 424 of this Title. (e) The "Historic Range" indicates the known general distribution of the species or subspecies as reported in the current scientific literature. The present distnbu- tion may be greatly reduced from this historic range. This column does not imply any limitation on the application of the prohibitions in the Act or implementing rules. Such prohibitions apply to all indi- viduals of the species, wherever found. (0(1) A footnote to the Fc4cral Regis- ter publication)s) listing or reclassifying a species is indicated under the column "When Listed." Footnote numbers to §§17.11 and 17.12 are in the same nu- merical sequence, since plants and animals may be listed in the same Federal Register document. That document, at least since 1973. includes a statement indicating the basis for the listing, as well as the effective date(s) of said listing. (2) The "Special Rules" and "Critical Habitat" columns provide a cross refer- ence to other sections in Parts 17. 222. 226, or 227. The "Special Rules" column will also be used to cite the special rules that describe experimental populations and determine if they are essential or nonessential. Separate listing will be made for experimental populations, and the status column will include the following symbols: "XE" for an essential experimental population and "XN" for a nonessential experimental population. The term "NA" (not applica- ble) appearing in either of these i«o col- umns indicates tfeat there are no special rules and/or Crirtcal Habitat for that par- ticular species. However, all other appro- priate rules in Parts 17. 217-::?. and 402 still apply to that species In addition, there may be other rules in this Title that relate to such wildlife, e.g., port-of-entrv requirements. It is not intended that tne references in the "Special Rules" column [S«c. 1 2-*-« PuMMIWd by THE BUREAU OF NATIONAL AFFAIRS. INC.. Wasftington. 0 C. 2003? 29 ENDANGERED WILDLIFE loA'l]3, Sddbdd Rc^xji Alli|ator. American ........... do .. •- ...... .- - • •• ........... ....... do ... .. . ......... .. ....................... do ... - ............. So^W Alligator mmiiuppte si» ........... ..do........................................ ....... . -• do .do..... ................. .................................. 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E l f E f : E E • T , T i E ' E E T T E l I! c . . • 2> 17 '.V J I SA I 33 ; i "=..-, ! ! *'• « 1 NA •» 1 NA i '» ' " ' IS 1 U i 4 '•* ' NA i N» . SA 1C »? i">4ic, ! IS ! 11 3 \ 3 ' IS • ;7 i i2> 1?»I II '-•» ' '•* ; N.» N* ' N-- N» •«- SA > NA NA NA SA SA NA I "A i '•>> 15* ' NA | Ml NA | Hi •-» I I2» ! NA I 12» I NA I '» ' NA I 33 ' i7*S<ci ' 12« ! NA | 1M I NA I :2» ' NA NA >.* "A N* '.« l.\ *•* N> *» N» •»•> "A NA SA MA KA NA N» NA NA NA NA NA NA N* NA NA [Added by 49 FR 7397. February 29. 1984] ir.H(h)J 10-12-84 PuMWWd by THE BUREAU OF NATIONAL AFFAIRS. INC.. WMNogtoo DC 20037 r NUS CORPORATION TELECOM NOTE CONTROL NO: DATE: TIME: DISTRIBUTION: C ~?- BETWEEN: OF: PHONE: AND: [) \ (X A-jL ^ '' INUS) DISCUSSION: \ ACTION ITUM: REFERENCE NO. 8 REFERENCE NO. 9 REFERENCE NO. 10 The Geological Society of America Memoir 98 CARIBBEAN GEOLOGICAL INVESTIGATIONS By H. H. Hen, Editor Dtpt. Otology, Prinetton Umatrsity, Prinetton, Ntw Jtrtry Carl O. Bowin Woods Holt Oetanografkie Institution Woods Holt, Musttlmsttts Thomas W. Donnelly Dtpt. Otology, Rie* Umvtrtity, Houston, Ttxat John T. Whetten Dtpt. Otology and OcianograpJty, Untotrsity of Washington, StattU, Washington E. R. Oxburgh Dipt. Otology and Mintralogj, Oxford Uautrsity, Oxford, England t I 1966 94 CARIBBEAN GEOLOGICAL INVESTIGATIONS 1.1 f, the final base map, have good shore-line detail. Mapping on St. John was done on 1:20.000 enlargements of the 1:40.000 U.S. Coast and Geodetic Survey map. Aerial photographs of approximately 1:30.000 scale were use- ful for some structural interpretations. Exposures along the shore lines ranged in quality from excellent to very poor. Those inland, except in recent road cuts, were almost invariably very poor. The best outcrop* on both St. Thomas and St. John are steep cliffs, which are in placet uftpenibk 1° traverse. More sheltered shore lines are easily walked, but rock expottirc* there are much poorer. laboratory investigations included study of several hundred thin sections, X ray diffraction examination of rock samples and mineral separates, about 300 partial chemical analyses, and numerous mineral dctermin.itions by optical examination of crushed samples. About a doien feldspars were determined by measurement of index of refraction of grains oriented on the universal stage, according to the method of Smith (I960). Approximately 100 additional plagioclase samples were determined by measurements of indices of refraction of unoriented grains. An extensive optical study of the feldspars, completed after this manuscript was first submitted, has been published elsewhere (Oonnclly. IOCS). Pyroxenes were determined by meas- urement of u, and 2V, according to I lie method of Hess (1949). SUMMARY OF STRATIGRAPHY OF ST. THOMAS AND ST. JOHN The rock units of St. Thomas and St. John (Fig. 2) can be divided into three major groups: the Water Island Formation, which consists of kera- tophyres and spilites; the Virgin Island Group, which consists of andcsilic pyroclastic rocks and sediments; and one or more diorilic plutons. The Water Island Formation possibly is late Lower Cretaceous. The Virgin Island Croup is probably Albian (although the Hans Lollik Formation could be Eocene), and the diorites are early Tertiary. The oldest rocks in the Virgin Islands are the keratophyres and spilitcs of the Water Island Formation. These volcanic rocks are predominantly flows and flow breccias, but keraiophyric pyroclaslic rocks are widespread. A few of the fine-grained tuffaceous beds contain well-preserved Radiolaria of undetermined age. Noteworthy in the Water Island Formation is the ab- sence of terrigenous sediments. This characteristic, together with their ap- parently igneous mineralogy, has led the writer to the conclusion that they are probably volcanic rocks which were extruded on a relatively level ocean floor, prior to the existence of a trench or island platform. In contrast to the postulated abyssal environment for the Water bland volcanic rocks, most of the overlying pyroclaslic rocks of the Virgin Island Group were extruded suhaerially. Both the volcanic and sedimentary locks exhibit slump structures, and some megabieccias contain limestone blocks up 10 100 feel long. The bulk of the sedimentary locks in the Viigin Island T. W. DONNtLLY — ST. THOMAS AND SI. JOHN, |l. S MMI.IN !•>! AM» Cioup are to.nse wackes consisting almost entiidy ot slightly uuihtml debris denied from the undesiiic pyiod.istic rocks I IK deposition of tint group may have accompanied the formation of tlic iniii.il isl.ind pLulniiii and trench. UJo liJ HANS LOLLIK FORMATION (tO.OOO feel ») A U S l I C - A N D C S i r C IMtCCU «"J TUFF Un>tr on* TUTU FORMATION (bOOOIeel'l TUFMCEOUS WACKt Includd mar It.. Do Cokl Point Megobreccio lilhofocies ih> ioo ii ih> Congo Cay Limestone (200-300 feel): COARSILY LIUCSIONE !ep Ol farniolioii nol ij S .lU OUTER BRASS LIMESTONE (20O - 600 leel I PARTIALLY SlUClFllO. TUFFACEOUS. HADiOLARlAN LIMESTONE LOUISENHOJ FORMATION (14.000 feel (W Si Thomas). 4000 feel (E Si Thomas). 7000 reel (W Si John)) AUCITC-ANDCSITE BRECCIA •i>4 TUFF (Sll/f BfACH «l CLCVEI N.or tni »,,, ii MX Cobes Point Conglomerate lilhofocies Milk plbWll •»< obblll il WAIER ISLAND FORMAT lllh.lojr TION UNCONFORMITY WATER ISLAND FORMATION (15.000 leel t) KCftiTOPHTRE FLOWS. FLOW •HCCCIAS. wtd TUFFS. •lift SPILITC FLOWS a/id minor RAOlOl AN|T(S I«lry4<4 b 1'* Slraii|jr4|>liic tcilion (nr M. I liunus jnJ Sr jt»lm. \'n^ni Folding after deposition of die Vngiu Ul.ind Cioup loulitil l.ngi-l) from dilfeientijl vciiicjl nioveiiicnt .md pioiluccd .nci.igc dips ol ID', i.iny ing from IS* to UO*. Tlic assou.accl snike slip faults line lioii/oni.d oll>iis of less than I mile. Although coni.ni iiici.niioipliic elk-civ loiiliint; fiom the emplacement of diorilic pinions nu cxiensive, the weslein tuo ilinds of Si I'homaf and the southern third of St. John are essentially niiincijinoiplioscd <jti CARIBBEAN GEOLOGICAL INVESTIGATIONS WATER ISLAND FORMATION GENERAL STATEMENT The Water Island Formation of possible late Lower Cretaceous age consists almost entirely of keraiophyie. spilite. and radiolarian lulf. The ex l>o>cd thickness of iliit formation is 15,000 feel, based on projection of the highest and lowest hoiiton* Ken. A reasonable correction for Icniiculariiy might lower the tine ihicknct* of the exposed section lo 8000 or 10.000 feel. U'aiu Island, in the harbor of Our lot le Amalie. Si. Thomas, has been selected as die iyj»e locality because of the great variety of rock types there and the general excellence of exposures, although excellent exposures crop oui extensively along the south shores of St. Thomas and St. John. •'Keraio|>h)ic". as used here, is an extrusive or hypabyssal intrusive vol- cjnic rock consisting prodiminantly of albiie and quarti. with chloriic. micaceous inineials. and iron oxides. Nearly all of the Virgin Islands keralo ph)re| contain considerable free quarti, commonly as conspicuous phcno cr)iis. Those with <|iuiu phenocrysts could be called "quant keralo- I'll)re" but many aphanitic rocks here called "keraiophyre" are chemically identical to the so called "quartz keratophyres" and the simplest term is pie- fcrred for all these rocks. A striking feature of keralophyrcs is the absence of phenocrysts (or pseudomorphs) of pyroxene, amphibole. and mica. Keralo phjric flows and crystal tuffs are sodic, with a very low potassium coiucni. but some apparently viiric tuffs are slightly more potassic. Keraioph)ic in- trusive rocks have a higher potassium content an ' commonly contain sec- ondary monoclinic K feldspar. "Spiliie" is a greenish seemingly altered extrusive or hypabyssal intrusive icnk. consisting of chloriie and albiie, with variable amounts of epidotc. prchniie. and caliile. Fresh phenocrysts of clinopyroxene aic generally pie»em; amphibole and olivine were not seen in the Virgin Islands spililcs. Amygdulcs arc abundant and commonly contain most of the calcium con- tent of the rocks as epidoie. calcite, or prehniie. with quarii and chloiiie. These spililcs contain about the same amount of Na,O as the augiic andcsitcs of the Louiscnjoj Formation, and about 0.5 per cent more than Virgin Islands diabase dikes. Included with the spililcs here is a partially albiiized augiie andesiie which occurs near the top of the formation. The name spilite has been applied in the past to many diverse rock iy|>es. some of which may be low-grade regionally metamorphosed andesiies or basalts. Other spilitcs appear lo have been unusually hydrous mafic intru- sive rocks, and many aie deuierically altered basalts or andesiies. However, ihcie is an impressive body of evidence thai many so-called spililes. notably certain Oidovician. Devonian, and Cretaceous geosynclinal spililes, have characteristics which can be best explained by assuming an essentially mag- matic origin for these rocks. It is to this latter group of rocks that the Water Island Formation spililes belong. 1. >V. llU.VNtltl — Jl. r l l t ) . M \ > AMI JiMI.N. I' Such spililcs may be thought of js locks which have funned by .ilhm/.i lion of andesiies. However, this process is bclievtd to occur dining a lair siage in the solidification of a hydrous mafic nugina :md is nut c.uued by later meiamurphisrn. Given a certain combination of phjsicJl anil cliemu.il conditions, spiliiization of mafic extrusive rocks is inevitable:. Heine the lerm, applied in an admittedly restrictive genetic (hence subjective) sense. i> a useful one and should be retained. The author admits lli.u low giadc mcfanioiphiim may oblilcraie the miiicialogical criteria neicss.iiy for the recognition of spiliti/.ition. Chcmicjl analysis of a l.iit,e and caiefull) selected suite of specimens might icve.il whether or not tin: iiiri.im»i|>lut rocks in question lud heen originally spilniud. bin such .m.il)>i:> might ,il..> fail lo do so. and the term should he applied with C.IK in null lock suite* HIK.VioriM KtS Iiilroiliuliny iliilriiicnt. Kei.unphvje compute* .ilium fom l i l i l n ,>l iln Water Island l-oiin.ition Most Ici.ilojiliyic ocnui a> M.IVM and llu\\ Intnl.u wild minor lulls, both cijbl.illinc and vitiii (ihc l.um .ilw.ip tk-\ in ilicd) .ind rarely, volc.mii hu-icias. Kci.ilo|iliyiic inirusixc l u i k i .iu inn U I I I O I I I I I I D I I . they occur .is lioth dikes jml plu^s, commonly unli \ c i y \\-c II clc-\c-l«i|jnl columnar joint ing Kfl.llojiliyiiL llou-i au- gent-Lilly tens of feel in lliickiic» | r\, t h u L ll.nv> are completely exposed fioin |O|> lo base, those which aic well ivj.osc.l .uc striking only fcir their lexluial unifcjrmily lijling and c lulling |.In noun n.. aic absent. Flow banding, uxially somcn'h.il conioiltcl. ii seen locally (PI :l, fig. I). ConUcis Lci\>een How u u i i j aic commonly dilliruh lo i c l c n t i l y as such, nnd alliludes of the Hows aic not always easily ascei lained One thick Li-ratojilijic. 1 flow neai the base of the section, on Kam Head. St. John, shows good field and j>etn>gra|ihic evidence of veilical ililfcienii i lion. The flow is about IC5 fec-l thick, and near the tenter is inUoli giay. grading logiecuisli giay downwaid and iijiw.nd. Peliogr.iphic diflnenres will be discussed later. The color change observed in the held would appeal to be icl.ilccl to a dilfeienli.il dc-pce of oxidation of iion within ehe floi., which is probably iclaled lo icl.ilive c onceiilt.Ulon o( \ol.iides in (lie Hot. center during cooling. Keraiopliyre flow bieuias. occuriiiig a> discrete beds, aic pioh.dily niou common than flows in ihc keraiophyie sequence but aie difficult to dis- tinguish fiom flows. 'I he matrix of the flow breccias can fiecpieml) In clislingnishccl fiom die fragments only by careful scimiii) of (he- ouii iop; tin- patina of wealheiing which covers most kcralo|>h)ic> elfeciivrl) ubseuies the fine details ucccssaiy to lecogniic these rocks. Fragmeiils in flow breccias aie subangulai to subionridcd The matrix is almost idenlica! lo the fi.ig ments in polished section; however, ihc matrix wcatheis mote lapidly. ami in outcrop a flow breccia will appear tougher in gio>t u x i i n e than a flow A few flow breccias consist of both kerlophyre and spilue fugmeiits One y8 CARIBBEAN GEOLOGICAL INVtilICA1 IONS such occurrence (sample GSJ-2, near the west end of Great Si. James Island) is a 100 fool-thick bed of keraiophyre and spilile rubble with a few lime- stone fragments set in an apparently igneous matrix. The minor recrystalliza- lion of the limestone suggests a low temperature of extrusion. No conglomer- ates were identified within the Water Island Formation, although many flow breccias have rounded as well at angular fragments and, when weathered, resemble conglomerates. O«f*«4 ikae (sample ST-274. Liscnlund. Si. Thomas) would tindoubledlf<'fec calttil a conglomerate by most field geol- ogists, but unweaihercd tpedmcai found a short distance eastward along the sn ike slioxv the igneous matrix very clearly. Tulfs and volcanic breccias form minor but distinct units in the forma- tion. Tuffs (grain size less than 32 mm) are much more common than breccias and occur as beds only I or 2 feet in thickness. None of the lulf units could be demonstrated lo have a horizontal extent greater than about half a mile. Grading is visible in the tuff beds, although this grading is commonly interrupted by diasiems representing ihc action of water currents on the sea bottom Slump structures, generally in the form of contorted bedding, aic uncommon. Many tuff beds are silicified, although the original pyroclasiic gioundmass is recognizable in thin section. Apparently the origin- ally vilric gtoundmass of many tuffs has altered lo fine grained mica minerals; muscovite is the most widespread, and celadonite and siilpnomelane have been recognized. One of the best exposures of a keraiophyre breccia is on the cast shnic of Lameshur Bay, St. John (sample SJ-7). Here a bed several tens of feet thick consists of angular fragments of keraiophyre a few mm to 5 cm in a reddish, hematitic matrix (PI. 4, fig. 4). The hemaiiiic matrix contrasts with the more neutral colors of most other keraiophyre flows and luffs in which hematite is generally subordinate lo magnetite. Dikes and shallow plulons of keraiophyre occur throughout the fonn.i- lion, but are most conspicuous in the hills southwest of Charlotte Amalic, St. Thomas (Haypiece Hill, Grambokolu Hill. Sara Hill. Cabriiaberg), in the vicinity of Nazareth Day, St. Thomas, and in the vicinity of Ifoffman and Ml. Zion, Si. Thomas. (Ml Zion itself, however, is underlain by another type of intrusive iotk ) These bodies commonly exhibit cnliiinn.n jointing |>cipcndicular to the cooling surface, and examination of the joints pro- vides a means of reconstructing the shape of the intrusive body. The hills around the Submarine llase on Si. Thomas (Cabriiabeig. Giam- bokola, Haypiece, and Sara hills) are underlain by one or two intrusive bodies known collectively as the Submarine Base Pluton. The accompanying map and sections (Fig. 3) show that the form of the intrusive body is irregular. The pattern of joints around Haypiece Hill strongly suggests the presence of an intrusive funnel beneath this hill. The joint pattern beneath eastcin Sara Hill, on the other hand, would appear to suggest that the floor of the intrusive body is stibhoriiontal, irregular, and shallowly dipping here. The intrusive-extrusive contact near a probable vent at the southern end of 1. W. UllNNLI I V—il. I HUM AS ANU i I. JDIIN. II s \IKI.I.\ IMAMU (I'l GrainnoLola Hill is mudeiaiely »(«•(, On Cain ii.il,, iy IMI ,!„• )(,|,iiiui..i joints are nc.nly lioii/onul Oi jli.illoul) dipping i.nv.n.1 the >uiulu-in n,,l of the intrusive body, but are neatly venital dppioxim.iu-l) Wl fed n.inli of the southern comau An ouurop of exmmve ro.l. cM.kml, oumm,.; j , , , • • ^ IWL.ll-".:::. J o>n«'*»l All«rol.«fl FICUIC J. Mjp .mil ooii icciiuiu ol'ilit S.iliinJiiiiL ll.ii, I.I.H.IN. ii | i,,,,,,.,j «,|, , ,., I'Ulc I lot lucaiiuii just underneath the limiimc body, (an !«.• seen along ihc shoir jnsi south of the Caribbean !Ion-1. Hue the intrusive body was probably fed through a steep conduit at iu southern end. and spread noiihwatd .1$ a ioi.Khl) conformable sheet. It i> not known whether or not iliiv immune l>o<l) connects with (he oilier one at shallow depth The occurrence of intrusive kciatophyre in moduaitly l.iiyc bodies to ward the lop of the section may relied a subtle upwaid change in 114 CARIBBEAN GEOLOGICAL INVLSTICATIONS lute optics), and rare biotiiic mica and a mafic mineral which hat altered completely to a hue grained, very red substance. I hit could be either iddingsitc. bowlingite, or some oilier clay mineral or combination of mineral). 1 he glass fragments have diffuse outlines and could be shards. In no case, however, hat the degree of preservation revealed the outlines of the original glass fiagmenu. The appearance of these beds in thin sec- tion is veiy similar to the tUflttly deviirified luflaceoiis beds found in ex- plosive rhyolitic suites, bin ibeir explosive origin is not established by peliographic evidence. SlkAllCNAHIIIC VAKIAIIONS The Wain Island Koimation it icmarkably iinifoini, consisting ilnoiigh- out of about one lidh spilitc and the remainder keratophyre. 'I he lower por- tion of the formation, seen best at Ram Head, Si. John, and on Cicat St. James Island, consists doiuinantly of thick keiaiophyre Hows with inter- calated spilitet. Breccias and pyioclattic rocks aie minor and form only very thin units with a limited lateral extent. The upper portion of the for- mation, seen best in the vicinity of Charlotte Amalie, St. Thomas, and on XVater hland itself dillers principally in the greater percentage of pyroclastic units. Aiound the iiitiusive bodies of llaypiece Hill, Crainbokola Hill, and ('abiiiabeig. the foiinaiion it doiuinantly pyroclastic, with only a few thin kctatophyiic flows. On Flag Hill, stratigiaphically slightly lower than these pyroclastic rocks, a strikingly thick pyroclastic unit is intercalated in a dominant!) flow sequence. No mineralogical distinctions between the lower and upper portions of the formation can be seen except that near the lop of the formation theie is one occurrence of oligoclase and albite with high-temperature optics, and theie are three occurrences of albite with optics which deviate significantly from the low-ieinpeiaiure state and which have been called quasi low Icmpciattire optics (Donnelly. IOCS). ENVIRONMENT The most striking featuie of the Water Island Formation is the complete absence of terrigenous sediment: the entire exposed thickness consists of volcanic rocks only slightly reworked locally by water. The second impor- tant feature of this unit is that most of the volcanic rocks, except for the uppermost 5 per cent of the formation, are flows. The pyioclastic locks themselves consist entirely of relatively equanl, angular fragments, and shards or pumiceous fragments are not seen. The quiescent eruption of apparently hydialed magmas must indicate that these magmas weie erupted under a confining pressure of superincumbent sea water approxi- mately equivalent to that of the deep sea bottom, which is sufficient to pic- vcnl the explosive expansion of a maginatic gas phase, llydr.ilcd magmas erupted in this environment will experience separation of volalilcs if the T. W. PONNILLV—ST. THOMAS AND SI". JOHN, U S MKr.lN ISl AMDS I 15 partial pressure of these volalilcs exceeds that of die sea water (about 500 aim at 15,000 feel). The expansion of these volaliles, however, will he in ihe order of a few limes, not many thousand limes, as would be the c.ise if the magmas were erupted subaerially or in shallow water. Abyssal pyiodasiii rocks will not be formed by explosion but by relatively qnic-t expansion <>l volaliles and sudden chilling by sc.i w.itcr. Dispeis.il of pyiocl.istii liai;meni^ will probably be effected by slow moving bottom curieiilv 01 eomtciivc currents initialed by the rele.ise of heat into the sea water. 'I lie .discncc <>l terrigenous sedimentary locks indicates that there weir no cmuneiit islands which could have served as the source of wcathcied denims Slmii|> structures or other evidences of deposition on slopes arc pusciil hut jie not abundant; in contiasl, near the lop of the formation llieic arc several miking orcunencc-s of evenly layered pyrochsiic (.erainphyie with no bed ding disluibances. Evidently this formation .icciitmd.iied not only in ab)s s.iI depths but also on t.iiher Hat sea lioiioiu. The appi-arame of slightly more explosive eiuptivrs only at the very lop of the Koiin.ition shows that the s e a bottom — - - ' - ~ ' • • . - . • • cumulation slant w.itei Alternatively, _ _ . ... been responsible for the appaient shallowing of watei — ............ ...~ ...............i ... i..s...., (plosive eiuptivrs only at the very lop of the Koiin.it ion shows I ha I the Horn may have been subsiding during the gieater pan of the ac- ^f lion but lli.il subsidence was not rapid cnoui>h to maim.tin .1 con- j^^ atei level at the eruptive (enter of the accumulated \olc.mir deposifJ^ jS lively, regional uplift near the end of Walet Island time could liaviV-^ ...„...:!.i- i-.. .1.- - . . , 11 VIRGIN ISLAND GROUP I OlIISl NIIOJ IOI1MAIKIN Inlrothn fcii)1 slntiinciit. Um oufoimahly miiljin^ ilic \ \ . i n i Islaml Fotniation and cropping out on alioul half the land .uea of Si. I liomas and St John is the l.ouisndioj (Loo e' /au lioi) FOIIM.III.HI. ninud loi excellent exposuics in road cuts in the vicinity of I niiiscnlm). just nonli uf ( li.nloiu Amalie, St. Thomas. [Ibis lhick_scijueiiie is piedoniinanily .inriic andesiir and varies in mode of deposition fioin pyroclastir to epidastit 'I lie m.i\i Ilium apparent thickness II.IVCIMI! is aluiut 13,000 feel, but a ic1.tollable correction for Icnlii ul.irily iiii^hl iedu<e this computed iliidness by a tliinl or more. Cleve (IH7I) called (his nxL type "Ithie lleach" and iliis II.MIII- h.is jXlsislrd: all of the natives (if lln \'iii;iii Islands .ne l.iniili.n uiih "Him Iliich" or "Illuc Kit." The formation is thickest and almost enliiely p)ioi I.I-.IM (lu< .ill) lewoileil tuff beds arc considcted essentially pyrochsiic:) in western Si Thomas In eastern Si. 'I homas the loim.ilinu !•> nun h lliimui (HHMl (eel) .mil i> «MII posed almost euliu-ly of Ki.use slumped and icuoiknl p)io< l.isiii ileluiv probably oii|;inaiin^ fiom a sm.dl snbaci ial cone In w< stem Si |»lui ilic formation is thicker (700(1 feel minimum) and comiiis |iu ilnuiui.inil) <>f co.use cone ih-biis. Figuit- <i slunvb an intei | net a lion of the inniliiioiit wliu li irsulted in this disli ibnlmn of mck types and thiilnessii l.\ ideme f<» iln 116 CARIDUEAN CEOIOCICAL INVES1ICATIONS T. W. DONNCI.I.Y—ST. THOMAS AND ST. JOHN, II S VIRGIN ISIANH? ||7 postulated I'illsbury Sound eruptive center is based on the cojisrncs> ul volcanic ejecla in nearby western Si. John and eastern St. Thomas, on the presence in Pillsbury Sound of a dioritic jiluton, and on (he necessity ol finding the nearest leasonable soince for the lithic (laments in tlic l.onisen hoj Foiination of western St. Thomas. In western St. Thorn.is (15 miles (nun the presumed ciuptive teiitei) occasional angiilai blocks 6 iiulics in diam eter are found in the ash bed>, which themselves langc fiom fine lull u> fragments about I inch long The coarse cone dchiis is most sinking in western Si John .mil e.isiein St. Thomas. In western St. Jolm -I foot blocks of \vlui HUM li.it e IK en subaciially deposited ash fiom the slopes of llic cones .uc (omul mixed in coaise conglomeratic beds Near Mandal in eastern St. "Ilium.is l.uge fug incuts of what may have been a suhaerial audesiic (low .ne seen in bi< cci.is of debris eroded (loin the cone. At one duality (u^menls ul How up to 2 feel long rest in a inaliix of fiuei in.ilcii.il Many of these h.laments bloke apart just piioi to cessation of irjns|>oil, and llan Inokcn unilines tan be matched in oulcinp. Tin's is the only pioh.ible How in.neii.il identified in lliivfoiinalion At the type locality the foimaliuii consists doiiiiiimll) of beds of toaiie andesilic tuff which, like most of the (nil seen, was appamiil) w.nei laid The beds are typically 6-12 feet thick and haxc laii giading with the' co.useM material (rarely coarser than about 1 indies; a (ew blocks to I loot) ne.u tin. base. These beds commonly show l.imin.ir slumping (I'i»->. 1. H) I Me nu»i striking featme of this slumping is the abundance ol "pull ,ip.ni>" .mil the frequent inteiioptions and leteisals ol (lie giadin<j 'I hit I.mini.n slumping is a veiy Lharacterislic featuir of the I.oniic nhoj 1 Oi ni.nion ami apparently fonneJ as follotvs: an ash (all was deposited undc-i i\ jtc i (I ig 7.\) on a slope and developed fair grading, inteiruptecl <>«.mc>nall) l>) a l.ngt; angular block which depressed the liedding below it I lie (me .iJi on lop became cohesite more rapidly than did the (oaiser .i-.li below the }<••>•> cohesive, coaiset material below slumped (Fig. 711), carrying on it and en- veloping within it fragments of the more cohesive, linei-giained in.iicii.il above. The flow was rarely rapid enough to become (mhnleni; die pulled apart beds have ne.irly all ict.iined an orientation parallel to the bedding During this process of slump the giading lost its original .•iiraugemenl. and the coarsest material is commonly (omul somewhat aboie the base of the unit. Additional evidence for deposition on a slope is the ur.nl\ uliiijiiiimis slump structures seen in fine-giained lulls in the (oim.ition Purely pyroclastic beds are not alwa)S easily distinguished fiom tnlf hcd> which have slumped and fiom beds which have been incne or less rewoiked by water currents. Coaisci pyioclastic rocks usinlly c-xhil>ii the h.iginenl angularity, the uniformity o( lithologies, and the npp.urnlly igiieous matrix which one associates with ash deposits, whereas liner ash beds re semble volcanic wacke. The over-all aspect of this form.iiion suggests aciul transport and subaqueous deposition of pjiocl.istic debiis. 7ianspoiu 120 CARIBBEAN CCOt.OCICAL INVESTIGATIONS Cabei I'oinl Conglomerate Inliolaciei. Near the base of the formation in the Niciniiy of Cn.r Bay. Si John, and Cabes Point. Pearson Gardens, and Bunker Hill. Si Thomas, conglomerates arc interbedded with andcsi- lic pyrotlastic and epiclastic locks. These conglomerates consist almost entirely of well-founded keiatophyre cobbles and jubblcs derived from the middling Water Island Formation At Cm/ Bay. however, these conglom- erates are more or less mixed with andesiiic debiis. suggesting that sub aciial erosion of the cone deposits and that of the underlying keratophyic beds were simultaneous. At Cabcs Point the conglomerate is composed of well-rounded and faiily well sorted keratophyie and spilite robblcs ami pebbles These conglomeiate beds appear to have been deposited in shallow water, anil were not products of mbidii) current deposition. They aie well sorted, ate not graded, and have relatively little matrix. Their presence indicates subacrial erosion, transpoit. and deposition of older tucks dining early l.ouisenhoj lime. Waltr hlandl oiiiicnhoj contact. There arc few places where the luntact between the Water Island and l.oui»enlioj Formations is well exposed. In St. John there is one excellent exposure of the contact along the west shore of Monte B.iy. and there are poor exjwsurcs at Klein Bay. The cxposme on Monic Bay shows a conglomerate of the Loiiiscnhoj overlying a spiliie bed. The spiliie is quite fresh at the contact, and the over I,ing conglomerate contains a wide assortment of Water Island liiholog.es including, however, very few rocks identifiable with the underlying spiliie. At Calvary Bay. St. John, there is an exposuie of a conglomerate of the Louisenhoj Formation overlying keratophyre. On St. Thomas the contact itself is poorly exposed, but an extensive ex- posure of Louisenhoj beds above the contact at the headlands between Brewer s Bay and the airport is of great interest because of the extent of apparently contemporaneous weathering displayed here. The Louisenhoj beds here consist dominantly of subaerially. varicolored andesiiic ash inter bedded with conglomeratic Water Island detritus. Some of ihe ash units are brick red and consist solely of albite. hematite, and a little illite (X-ray diffraction) The albiiiicd plagioclase phenocrysts evidently withstood the weathering almost perfectly, but the entire mafic part of the rock has been converted to oxide Other units consist of varicolored fragments ranging from deep red to gicen. evidently reflecting differential susceptibility to weather- ing. Still oiher units consist of greenish or grayish fragments in a uniformly puiplish matrix. The basal subaeri.illy weathered unit is less than 100 feet thick and was found at only this one locality. The color of the beds somewhat resembles that of the weathered hydrothcrmally altered rocks (discussed in a following section), but the latter grade into whitish unwcathcred rock within a few feet of the suiface and are mineraloeically quite distinct. The extent of .his wcaihciing is compleicly unlike any iccrnt weathering of any rock t,pes in these Islands and umloub.c.lly rcfleris weathering contempora- neous with original deposition. T. W. DONNtl LV——ST. THOMAS ANN SI. JOHN. II <, \IK(,IN ISIAM". I .'I Another occuirence of coniempoianeom wi-jibeiing is pooil) r\|»»cil .11 VVintberg Hill, St. Thomas. 'I lie poo. nanual e\pusmc->. uliuli ,nc nl lightly metamorphosed rock, weie oiiginally thought in l>c nl li)<lioilu i mally alleied rock. However, icccnl (1903) exc.i\aii<>ns Im in.nl < onsii in timi revealed the originally wcatlicicil n.iline of (In si- KM U Mineralogy of mafic fragments, the piimipal niiini.il, linnul in in.ilu fragments are plagioclasc. clino|>)iovc-iic. ihloiiu-, .nnl pmnpi-lljiu-. .mil .din matrix and o|>aque minerals. 1 HAHS IOLLIK FM TUTU O Ftt. 0 OUTER BRASS LS. 9 o 1 ° 0 ° I 8o f\ a»° "<Mony .A~\ Somples LOUISENHO Spililiicd Aug WATER ISt O CZD • 0 > ° / FM ..... It Andesile AND FM Mon> O 2) Samples -o oo o An, An'20 An60 An 80 An100 O LT ond QLT (Donnelly. I9C3) oplicj 9 HT optics KicutI 10. Oiitpuiiiioiis of p|jgio(b«t aiiingnl iccouling lo ilr jiifuplni IM.HIMUI rUACtocLASE: Most phenocrysls. of the l.ouisenhoj andesius aic labiailoiiie. about An,, (Fig. 10). Near the base of the formation many |>)roil.isiic ioiks contain a distinctly more calcic plagioclase (An§J in about An,.) Some of these pyroclasiic rocki contain both bylownilic and labratloiiiic fragmrnis. but a few contain only bytownilic (or anortliitic) fragmrnis 1 he ft l>lsj>ais aie sharply euliedra I and slightly zoned. They show abundant simple luimimg and some albile twinning. Groundmass plagioclases and plagiodascs in ilie matrix of coarse pyroclasiic rocLs aic very fine -giaincd ami cloudy. M.my are distinctly moresodic than the phcuociysis and range in calcium content down to An,0- In many lapilli luffs, the only feldspar found is albile (An,); r— 170 CARIDIILAN CtOIOGICAL INVESTIGATIONS composition of the more siliceous dilfeieniiates. The experiments of Yodcr jiiJ Tilley (196-') show clearly that at water pressures greater th.in nboul 1000 bais. material o( basallic composition should be converted to a mix- lure of huinblcmlc and pl.igioclase at subliqiiidus icni|>eratiucs. As the temperature rises the material will begin to melt, with the plagioclase being consumed fust. The first liquids produced will be highly felsic and siliceous. 'Ihe compositional trend oC liquids produced at successively higher iciii|K-i.units hat Milf ^c%M experimentally determined, but a com- panion with the ana logout procedure in anhydrous cases (generation of basalt) suggests thai hornblende will lake the place of diopsidc as the dominant mafic phase being consumed during the greater part of the melt- ing. 1 he hydrous liquid might, therefore, be more enriched in Si than would coiupaiablc liquids coexisting with diopside in the anhydrous case. 'I lie extent to which residual hoinblcnde might control the composition of ilic liquids will not be easily evaluated until these hornblendes can be t ollcclcd and analyted, but this consideration might prove 10 be pivotal. The quantity of keralophyric magmas generated is perhaps the only really serious objection 10 the hypothesis of generation of (his entire suite from the upper mantle. The quantity of siliceous rocki is unknown, but geological inference (exposed atca of Water Island Formation, which is about 80 per cent kcratophyre) combined with geophysical information (seismic refraction and gravity) suggest that the Water Island Formation is a pi ism about 5 km thick, extending perhaps 40 km in an east-west direc- linii. but quite- possibly thinning to the east, and extending perhaps 20 km in a nonli souih direction. This volume—4000 en km, or 3200 cu km of Uiatophyie — is pioh.ibly a maximum, because possible thinning to the tast and 10 ilit souili was ignored in the calculation. If fusion of 10 per cent of llic upper mantle might yield a keralophyric liquid, then 32,000 in Im of upper manilc wtie (used during this igneous episode. If the depth of fusion was 10 km and the cast west hoii/ontal extent of fusion 40 km, iIKn the hori/onial dimension of the fused lone in a nonli south direction must haie bten 80 km. These figuies may be off by an order of magnitude or more, but they cmphasiie one problem: the generation here of siliceous magma fiom the upper mantle may require the partial fusion of more ma- icrial than can directly underlie the vent, unless the fusion extended 10 great depth. The explanation for this seejning paradox is as follows: Dining the orogenic process compression and thickening of hydraled Caribbean crust and np|>cr mantle carried this material into the orogen from a con- siderable distance perpendicular to the axis of depression. The orogenic nijgin.ilic process then can be compared to a mill to which is fed fresh, hy- dialed upper mantle, and from which two products, magma and mafic ie- siiluiini, ait icmoted. the first ihioiigh ascent and eruption and the second iliiouijh giadual displacement downward .mil eventually laterally. The .uiiiiuiil of keiaioplmc eiupled might li.nt lequiied lateral slioiIdling of .iljiiul 80 km in this area. The quantity of siliceous igneous ro(k seen hcic is l^r in cxiesi of any that has been recorded in similar orogenic ?oncs. and T. w. noNNit I.V — sr. THOMAS ANU si. JOHN. 11. s. VIKI.IN m ANUS 171 the Virgin Islands may be an extiemc example nf a pioiess which h.is m currcd to a lesser extent in in.my places at many limes, (lleaily our know! edge of the composition of upper manlle is too litiiiltd .11 ilns lime ID .nsi ii this problem further. 'Ihe writer (Donnelly. 1964) also pointed out that the genciaiion of a second, sirengthlcss phase (aqueous, or hydiatcd silicate nicli) during orogenic thickening would have profound slniciiii.il implications I lie volume in which this phase w.is generated would become essentially strength less, and the structural process would be cxptncil to change- fiom a relatively mild thickening to a more violent movement along an exten sivc shear. The consequences of this movement would be that the island platform would be raised to an emergent level, ami possibly an adjoining oceanic liciuh would be foiined. The effect on the genci.iiioii of igneous melts would be that the rate of depression of rn.iiille material (and tlie rate of healing) should be increased gieatly. After this profound structural episode, the generation of magma will be relatively rapid, and the piopoi lion of mafic lo felsic magma high. The restriction of abundant siliceous magmas lo the early stages of oiogenic evolution is consistent wild this idea. In conclusion, the following points seem well established: (1) Two types of chemically uniform magmas were generated ihtouglmut the span of geologic history of these islands. (2) Time has been inteiadion of erupted magmas with the environment in the case of alkali exchange in cximsixe kcratophyres. Other possible exchanges have not been esi.ibliJicd. exiept that a few samples of highly metamorphosed keraiophyrcs liate been im povcrished in alkalies. (3) The siliceous iii.igin.is upi01111 tiTii.iiy (O \\> < ) i ) melts derived by partial fusion in a dominanily sodic enviioinncni. .mil mini probably, in an environment with considerable calcium I he I.HCI bth.i\icu of this presumed calcium remains one of the imponani anomalies Tim parent material, for diverse reasons including geophysical ami chemical 01 dence, is considered to be upper mantle. (I) The mafic magm.is are cluini cally similar lo so called high alumina basalis lypi(.i) of orogruic legions gencially. The high magnesium of the spiliies rcsiihs from its general ion 1 from a material largely depleted in iron by abstraction of Leraiophyrc (5) The increase in aluminum with lime and the higher noiin.unc AI'/Q ratio of the later quaiu-.indesine porphyries of the second group may indicate generation at increasing depth with lime. (6) Crystal striding and assimila lion of wall rock were probably of little importance in the gcnei.ilion 01 differentiation of this suite. SUMMARY OF GEOLOGIC AND TECTONIC HISTORY OF THE NORTHERN VIRGIN ISLANDS The tectonic evolution ol die I'utno Uio> Vii^iu Kl.uuN .IM.I h.i> .<! teady been discussed by the writei (Uonntlly, 1961) I lie following accouni summarising llic geologic hisloiy of the noilhein Virgin Islands elucidates V f I7L> CARIUUCAN CIOIOCICAL these ideas but iniioduces no new concepts. The major cast-west fnuli deduced laigel) fiom gravity evidence wa» not lecogni/cd at the lime th.il paper was prepared; however, iis existence require* no modifu.ilion <>l the iilo.is presented. The keraiophyics and spiliics ul the Watci Kland Formal ion weic cxtiuded on a relatively flat sea bottom, as indicated by lack of Icnigcnons deliilal sediment and paucity «(f slump structures in most liillaccons units. A major cast-west high-anffe'twill infeircd honi giavity data was prob- ably the locus ol tiupiion ol llicx magmas as well as most of the later magmas. Movements along this fault tiinulianeiius with eruption led to accumulation of ihc Water Island rocks in a basin wild a sharply defined northern edge. 'I line is some evidence of shallowing of the water level lowaid the end of Water Island time in the greater pioportion of lulT.iicous kcratophyics at the \ery top of the section The end of Water Island lime K.IS maikeJ Ly abrupt emeigenie, possibly in part along the major cast-west fault noted piexiously. This movement, as well us subsequent movements along' this lauli, was of an opposite sense to the original movement: the not them side went down. Overlying basal Loiiisenhoj beds weic deposited subacrially and weathered to foini a brick-red soil completely unlike any that are funning al the piesent time. Intercalated conglomerates of pic dominant!) keraiophyric clasts which are especially abundant near the base of theT.otiisenhoj show that iheie was a rather persistent emergent source aica of older rocks exposed at this lime. Slow subsidence aficr e.nlv l.ouiscnhoj lime is reflected in the gradual diminution in abundance ol conglomciaiic units, the finer gi.iin siic of the pyroclastic deposits and theii rewoikcd c<|iii\alcius, and the increasingly excellent grading of the mil beds toward the lop of the foimaiion. The oveilying Outer liinss Lime stone icpicicnis almost complete volcanic quiescence and subsidence below the level of eflcclive wave erosion of the older rock units. The beginning of Tutu lime was the beginning of renewed dilleieulial vertical movement, with newly cieatcd or lejiivcnaled sleep slopes shedding wades into water ol unknown depth. Emergence of pail of the souite area is seen in the abundance of partially wcalhcicd Loiiisenhoj fiagmcnis among the detiital component of the Tutu Formation and in the inlci- lalated blocks of (ossiliferous limestone of the Coki I'oint Megahicccia liihofacies. A brief period of ncai cincigcncc is seen in the Congo Cay Limestone Member. The iccryslalliialion of this unit is too extensive 10 have preserved any of the diagnostic petrngiaphic ciiiciia which might have revealed something of its environment of clc|K>siiion. but its massive- ness and m.iiI) juiie c.ihilic ((imposition shows ili.il it uiiisi h.ne lu-cn a bank deposit of ne.nl) pine skeletal debt is. Renewed vulcanisin aflei Tutu lime is seen in the ihitk aiigile andcsiic p)ioclaslic rocks of the llans Lollik l-'oimalion. Mincialo«ically this aiulesiie appeals to l<e ideniiial lo that of the Loiiisenhoj Foimaliun. Post llans l.ullik Foimaiion liisioiy is cihsciuc in die Amcrii.m islands T. W. DCJNNLIIV—SI. 'IIIOMAS ANI> SI. JIUIN. II S V.IKC.IN isMNIiS 171 and has been treated in mote detail Ly llelslcy (I'JliO thesis) in the Iliiiish Viigin Islands A dale ol Middle I ocene near the lop of (lie I oilula I OIIH.I lion (which includes the llans l.ollik 1'orm.iiion. called h> llehle) a member, in the llrilish isl.mds) establishes (he age nl die ii|>|>c-i pail of llie Viigin Islands (,ioii|> 'the laigc li.iiholiih in (he Iliiiish islands iiinmlrs llie loilol.i I uiin.ilioii and is apji.iicully (oiiiein|»>i.iiicons uiih llu mm fossililc-ious Nciker Fuimalion. Horizontal fortes of any OIHIH.IHOII 01 sense i.niuui he shown in h.nr played an impoiiani lole al any si.ige dining ihc eviilniiuu ul ihi> .m.i Neaily all ihc Sliuciuial relalionshijis olmivc'd, .1$ well as the ph)>ii.il Sllaligiaphic cli.ii.uUi of I he lock nuns, can be mine easily ex |> (.lined on the basis of dillcienlijl vertical movements Al.iuy I.mil |i|anes acioss vvludi such movemrnts occinied m.iy have coiiiinued lo he ihe loci of fanh clis placements fiom del iceons to eaily Teili.uy lime, .mil even in die pus enl.4 1 he pioblem of the geneialioii of the magmas is inexinc.ilily linkc'il iviili thai of ihc Sliuciuial evolution of the aic. The gcneialion of all of the magmas is considered to have occuned as a result of the mnie or Ic-ss p.u lial fusion of hydratcd upper mantle in.iieiial, identical lo th.ii piesenil> found beneath the Caiihhean Sea at dcpihs betwem !> and lf» <n 20 km below the sea floor. The large volume of siliceous keraic>|>h)ie. and 10 .1 Icssei cxient. the volume of later mafic locks, icquiies the fusion of U|>|>< i mantle over a hoiizonl.il extrnl consiclciably gieater than llie |>ieseni cli infusions of the outcropping rock nniis. If the fusion was liiiniecl 10 ihc hydiaied 10 to 15 km of upper in.mile, ihen the only adeijiiaie e\|il.m.i lion for the volume of magma t-inpiecl is that hoii/oiu.d inoveuic nis ii.uis ported adjacent, unfusecl niantle into the orogcn, where it was dcjuessed. heated, partially fused, and then iis refiactoiy lesidniini sluuly clii|il.ued clownwaid and laterally. The evolution of this poilion of llie West Indies is basically (he lespontc of juxtaposed, physically coiiirasling plates of ciust and ujijicr in.mile 10 an applied horizontal force. F.iilme along the join between these plaies resulted in thickening and downw.uping in the initial stages (U'aicr Island lime), followed by compressive faihne, the formation of a majoi it-veise fault system, and rapid uplift, which funned an enieigent island |>l.iilonn (Loiiisenhoj lime) and. most probably, an adjoining oceanic nemli Fniihei application of compressive forces caused fuither thickening and cuiiiimud emeigeiice of the island plalform. Time is no eiidcnce in ihc Vngin Islands that submergence of any magnitude ever occnned .ifier \Vaici Island lime. Magma was generated by the partial fusion of hydiaied np|>ci mantle; the proportion of siliceous and mafic magmas at any time- ielleii> llie rale of deformalion and the i.iie of teinpeiaiuie I ise. The eastern Greater Antilles is a iiiiiijue exhibit ol the s.duni linuns 'Src fixHiioic 2. |Mji' HO .1 —J 174 CAIMObLAN CKJIOCICAL INVtSTICATIONS ul the cauli's iiljnd arcs. This area his never been blanketed with the ihiik lenigcuuus sediments which have modified and later guided, the iiiuctural evolution of most oiogenic regions; it repiescnts instead the diied interaction of oceanic cinsl and erogenic forces. The failure of these rods to have been metamorphosed and (heir subsequent exhumation in a nearly pristine condition are probably the result of a lucky gcologit.d jccident—the development <jf at} e*l«nsive strike slip fault system south of the island platform along wJuth were resolved the bulk of the post totem' dilorirumc forces. \\'ilhiu the bland pl.iiinim, the tloiiiin.ini tectonic forces have been dilfercnlial vertical move-menu canted hy thickening :it depth. Although none of the structural or petrulogic conclusions deiived from this study can necessarily be applied to any other sjjecific area, nevertheless certain observations cannot fail to raise serious questions con- cerning long standing geological hypotheses which have not been seriously (jucsiioncd in iccenl years. REFERENCES CITED UOCCILB. O. B. 1907. Om Dansk-Vt-itindicns Ceologi: Ceogiafiik Tidukrilt. Hon. Uansks. Ccogra|>h. Schkab. v. 19. p. 6-11 (Translated by Mil. Ediili Thcile. Toilola. M.V.I.. and eiamined by ll>c wriici) BONIT! F. 1966. ZoniGcacion miciolaun/siica de lai caliiai creiJcicas del esit dc Mcnico: Dul Awe Petrol Me«.v. l.p 389H87 UywtN. N. I... and Tunil. O F. 1950. The S)stem NaAISi.O, KAISi.O. H.O: Joui. Ccol og>. v 58. p 4B9-5I I Hi UMM.IO*. A. F. I95'J. Cianiie emplacement wild special icleience lo Noiili Aineiica: An ei»j) review: Ccul. Sac. Aineiica Dull., v. 70. p. 67I-74S Ci.iv i. Pii Tiouou, 1871. On the geology of the northeastern Wen India Islands: Stuck- holm, kimgl Svcmla Veienik.-Akail lljndl.. no 12. p. Ml. —— 1831. Outline of the (eulogy of >hc noillieasifin West India Islands: N. Y. Acad. Sci. Annali. v. 21. p. 185-192 CoiMlius, II P. 1951. /ur Fia(C dec Abialibedinguiiden dcr Radioliiile: Ceul. Rund.. Dd 58. p 216-221 UONM.IU. T. W. I9>9. The geology ol Si. Thomai and Si. John. Viigin lilandi: 3d Caribbean Ccol Conl Trails. (Mataguri. Puerto Rico), p 153-155 —— 1962. U'airakiie in U'csl Indian spilitic roclj: Am. Mineralogist, v. 47. p. 791-803 —— 196], Gennis ol albile in early oiogenic volcanic mcli Am. Joul. Scl.. » ,261. p. 957- 972 —— I9CI. Eioluiion of easicin Aniilkan island aic: Am. Asioc. Pcuohuin Cculufisit Dull. v. 48. p 680-696 —— 1965. Sea bottom moiphologr luggeslivc of potl-Pleiuocene leclonic acliviiy of the eaiiein Cicaier Aniillci. Ceol. Soc. America Dull., v. 76. p. 1291-1291 •DuuusiAiNC. P.. and Micniumi. C., 1861, IS66. Memoiie tur le> Coralliatict dci Antilles: Mem Acad. Turin. Id tti.. v. 19. p 279-365; v. 23. p. 199 L-.ni. K \V , IV2t. 1 he geology of ihe Fliilish Viigin Islimli: Ceol. Mag . v. 61. p. 3)9- 351 luc. IV. S. Ttk.Mi. F. j. and VtmoociN, J.. 1951. Mtumoipliic leaciioni and incia- inoiplnc lacies: Ceol Soc. Ainriica Memoir 73. 260 p. • N'ol enamined by the wiiier. T. W. UONNtLLV—ST. THOMAS AND Sr. JOHN, U. S. VIRGIN ISI ANUS | 75 HAMIIIOH. \V . !9Ct. Oiigin ol high alumina buall. andciiie. and ibcnc mjjjiiui SIHIHC. v. MO. p 6)5617 lliHKr, J. J. 1959. Some Dilncialugitjl equilibiia in the i)ilcm K;O AI.O. SiO, II.O Am. Juui. Sci.. v. 257. p 241-270 HIMKT. J J.. Mirm. C, and HICIIIH. D. II. I9lil. Some jlituiimi icjiiiuns in il» lysiuii Na.O Al,(). SiO, II.O. U. S Ci-ol Suncy Tii,! l'j|,. i 4'.'||). (, JJH JIO IIIil. II. II . I'JI'J. Clicmical c<>ni|><>iiiiiui and o|Hiul |>KI|KIIUI ol common <|IIKI|>)II>M n., I'au I: Am Mincialoyisi. v 34. p 6L'I 61.6 HIK.OM. A. C. 1905. Zui IVhugupliM ilci kl,,,.,,, Annlltn ll|i>jla. Hull (i.,,1 h,-i Univ . v li (I902-IW3). p 2I4-23L' •lloiiNkM.lt.il It. 1810. Noglc UtlliaelL.niii|;i[ mil 5l I II.MII.U (.11.1•unlit- il.in.liiui i,ki NaiuiluiiLeict. LMn Mudc. p 301-368 •—— 1816. Dcbcr die inineialitchcn Voikumniniiie jul tin Intel Si I IM.UUI Kul. 'Jhli V'rn tier N'aiuif. und Aeulc. p. 1:62 'J6I KiMr. J. F . I9?6. Cculogy of Ihe Viigin lilandi. Culclna. and Vu.|iui: Iniioilutiion ^nd review of ihe liieiaiuie: N. V. Acid S<i. Sticnlilic Sunc) ol I'uiio Kito and ilir Viigin lilandi. v. 4. |.i I. |i I 6'J KlnNLct, G. C, IU50, PICIIUIC volume lrni|it:ij|uic iclaiinns in wjit-i ai elc\ned inn pcialuu'i and pieisuici: Am. Jour. Sci, v. 248. p. 540-564 •KNOI, Riv. J. P.. 1852. A hilloiical account ol Si. Thoniu. \V I : New Voik. Cbailei Sciibner and Sons. p. 207-213 LIMMLEIN. C. C.. and KLIVIJOX. P. W.. 1956. flhc lelaiionship of the iheiaiodynamital parameleii P-T-V for M,O and 30% aijiicoui NaCI sulmiimi): Min Si.c. U S S R Tram. v. 85. p. 529-534 I.IDMK, E. C.. I9C5, Penology of andesiiic. (piliiic. and keiaio|>h)iic lluiv rod. nuiili cenual Pucno Rico: Ceol. Six. America Bull. v. 76. p. 57 88 •MAClum. W. 1817. Observations on the gtology ol Ihe Win Imlij isljmh li,-ii, lljil,j,l,.i lo Sania Ciiu. inclusive: riiiladel[ilua. Jour Acad. Sti, v. I. p 131 II') Mcvuiioir. II. A.. 1926. Ceology ol Ihe Virgin Islands, Cult I,u. and Vni|.m Pliim.g rapliy: N. V. Acad. Sci., Scientific Suitcjr ol I'uiio Kitti and ilie Viigin hljn.h. v 4. pi. I, p. 71-141; pi. 2. p. 1-219 NICMOIU. C. U.. 1959. Auiomelasomaiisni in the lower sjuliics of Hie Uuilih loltjnu teriei: Quail Jour. Ceol. Soc. Ijomlun. v. m. p. 137-162 NOCKOLM. S. R. and ALUN, R. 1953, The geochemiiny ul ic.n.c igutous rotk seiirs Ccocliim. el Cosmochim Acia, v. 4, p. 105-142 Orricin. C. D, EWINC. J. I. HINNION. J. F. HAHIIOH. O C . and Mililn. II E. 1959. Ceupli)sical investigations in Ihe CJJUMI Caiibbcjn: siiinmaiy of 1955 md 1956 cruises, p. 17-109 m L II. Ahum, F. Pirss, K Raiikanu. and S K Rnnciirn. f.tilon. I'hysicJ and Clicmisny of the Earth, Volume 3. london. I'tigamoii Pre^s. 4(>l p OIVIILC. P. M., l%5. Allah ion itchaniji l.eiwiui xjpt.r ami feldt|iar plujc. Am l.n.i Sci. v. 261. |i. 201-237 OsaoiN. E. F.. 1959. Role of ov)(;cn pituuic in the (I)SII||HJII..M an.I dilltii-niijii,,ii ,.| basaltic magma: Am. Jour. Sci. v. 257. p 009-617 Rotii*. II. J.. I960. Zur Pcllogu|ihic. Ceothemie und (icuru dri Mjgnunir on.I I j^;< i slatlen del Obfidcvons und UnieiKaidons in Oilllniiin^rn fi.il.iig, i luiulmiiK C 92. p. 1-273 SCIIOIN. K., 1962, Scrni-quanliiaiitc anj|)>ii ol chloiitts liy X uy ilifluiiu.ii \.n Mm eialiifisi. v. 47. p. 1384-1392 •ScilOMluncn. R II. 1837. Die Jungfraii-Inscln. in grulogiuhri un.l llmni t,l.,, I|IIIM,IH Deighaus' Almanach Inr Eidkiinde. p 307H55 SIIAMHO. L.. »nd DHANNOCH. W. W.. 1962, Rjpid jnalyns ol uli.jic. c4il,,.iuic. and |.!M.> phalc rocks: U. S Ceol. Suvey Hull. 1141 A. 56 p. Siiuutr. C. L.. \VoUfL, J. L.. and EWINC, M., 1956. Gravity mrasuieiiifius in the Vngin Islandc Ceol. Soc. America Dull., v. 67. p. 1529-1536 •N If* I L E G E N D Quaternary Alluvium U Cretaceous L Tertiary Dikes and Plugs: qa* quartz-andesine porphyry •, ah = andesine-hornblende porphyry Contact Fault, showing displacement c~ co 103 O a>oo O a. 3 O k_ O cft M Dioritic Rocks Hons Lollik Fm.: Augite andesite volcanic breccia and tuff Tutu Fm: Volcanic wacke. X-cp outcrop of Coki Point Megabreccla Ktcc - Congo Cay L*. M«mb«r Outer Brass Ls.:Thin-bedded, siliceous Is. Louisenhoj Fm.: Augite andesite volcanic breccia and tuff, with minor conglomerate Attitude of bedding Attitude of fault Attitude of intrusive contact UNCONFORMITY ca '-' C K; O "5 O 5. a> o Quartz keratophyre dikes and plugs Water Island Fm.: Quartz keratophyre flows, flow breccias,and tuffs; radiolarites, spilite flows MAPPtO Br THOMAS w DONNELLY U5 SOuTHvXtr TOKIOli BT C I "[LSLtt REFERENCE NO. 12 ISSN 0500-4780 CLIMATOLOGICAL DATA ANNUAL SUMMARY PUERTO RICO AND VIRGIN ISLANDS 1987 VOLUME 33 NUMBER 13 'I C E R T I F Y THAT THIS IS AN OFFICIAL P U B L I C A T I O N OF THE N A T I O N A L OCEANIC AND ATMOSPHERIC A D M I N I S T R A T I O N AND IS COMPILED FROM INFORMATION RECEIVED AT THE N A T I O N A L C L I M A T I C DATA CENTER. ASHEVILLE NORTH C A R O L I N A - 28801 DIRECTOR NATIONAL CLIMATIC DATA CENTER noaa NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION NATIONAL NATIONAL ENVIRONMENTAL SATELLITE. DATA CLIMATIC DATA CENTER AND INFORMATION SERVICE ASHEVILLE NORTH CAROLINA TUT 002 049U TOTAL PRECIPITATION AND DEPARTURES FROM NORMAL (INCHES SEC REFERENCE NOTES P U E R T O R I C O A N D V I R G I N I S i A N O S _ I9B 7 S T A T I O N V I R G I N 1 S L A N O S S T T H O M A S 0 1 D O R O T H E A A E S E S T A T E F O R T H Y L N E R E S T A T E HOPE R E D H O O K B A T T R U M A N F L O F A A A P M 1 N T B E R G - - D I V I S I O N A L D A T A - - - - - - - > ST CRO 1 X 02 A L E » H A M I L T O N F L O F A A ANNAL Y A N N A S HOPE B E T H U P P E R N E M U O R K S C H R I S T 1 A N S T E O F O R T C O T T O N V A L L E Y 2 E A S T H I L L E S T A T E THE S I G H T F O U N T A 1 N F R E O E R I K S T E O 1 SE G R A N A R O HAM BLUFF L -H S TN M O N T P E L L 1 ER - - D I V I S I O N A L D A T A - - - - - - - > ST JOHN 0 3 C A N C E L B A Y P L A N T A T I O N C A T H E R 1 NEBURG C O R A L B A Y CRUZ B A Y E A S T E N D L A M E SHUR B A Y - - D I V I S I O N A L D A T A - - - - - - - > JUL PRECIP 1.12 2 . 04 1 §• 1 . 22 . It . 13 1 . 4 0 1 . 2 2 2 . 2 8 1 . 8 0 1 92 2 . 28 2 . 50 1 4b 2 . 2 0 3 . 00 2 . 3 1 1 . 5 7 1 95 2 55 2 08 1 . 7 4 2 . 02 1 . 7 4 1.59 2 . 1 0 1 . b5 1 . 8 1 DEPARIURC - 1 85 - 2 . 1 4 - 1 . »' 2 - 1 . 1 7 - 2 . 1 1 - 1 . 4 4 A U G PRECIP 2 7 2 2 7b 2 9b 1 b9 2 . 4 1 1 . 5 3 2 2 2 1 b 3 1 8 0 1 25 1 . 32 8b h 1 . 1 3 1 . B 1 1 . 9 1 2 . 09 1 . 4 5 1 . 6 2 1 . 38 1 5 2 2 1 5 2 . 2 0 M 2 . 2 7 1 6 8 1 . 90 2 08 DEPARIuRE - 2 38 - 2 84 - 3 . 1 2 - 3 . OB - 2 . 0 2 - 2 52 S E P PRECIP 2 5 7 . 40 2 . 90 1 . bb 1 . 4 2 1 . 4 3 1 . 5 0 2 . 7 9 2 09 1 . 5 0 2 . 0 2 1 . 4 3 1 . 4 5 . 23 50 2 9 2 . I B . 42 2 . 1 0 1.80 2 . 2 3 1 . 2 2 3 . b5 2 . 4 2 2 . 0 8 H 2 . 3 2 OCPARIURE - 4 . bO - 2 84 - 4 5 3 - 4 . 3 0 - 3 55 - 3 . 7 8 OC T PRECIP 5 3 32 . 5 7 9 7 . 35 . 5 3 4 . 1 4 2 b5 2 BO 4 1 0 H 2 5 5 3 7 8 3 Bb 5 . 1 3 4 . 8b 3 . 00 2 5 2 3 1 7 H 2 . 3 3 4 . b 3 3 t.8 5 . 0 7 . 2 7 . 5b . 75 . OB M .08 4 1 5 OtPARIURE - 1 2 7 - 2 bO - . 9 7 - 1 . 7 3 - 1 . 3 7 - 1 2b NO V PRUIP 8 4 7 7 . 3 7 2 . 9 1 1 49 0 3b 0 4 3 3 b2 3 25 5 0 3 1 45 5 2 7 5 4 8 0 1 7 3 . 80 4 . 5 1 5 . 2 3 5 . 7 b M b . 95 3 7 8 1 4 2 2 2 8b 3 . 08 1 5 2 8 5 4 0 3 9 0 b4 1 1 . 1 7 OIPABIURE 8 5 1 8 2 3 5 Bb 9 1 1 4 0 3 b Ob D E C PRCCIP 4 4 3 5 . b5 4 2 7 2 3 2 2 9 9 4 1 3 3 . 9 0 4 9 4 3 . 5 2 M 4 b2 3 7 3 2 3 9 3 1 9 2 9b 5 50 3 74 M 2 9b 4 4 2 3 R J . O £ 3 9 0 M 4 4 2 4 5b M 3 b7 4 04 4 0 4 OEP»RIUR( 1 2 9b 04 . 2b A N N U A L . PRFCIP 7 0 1 7 b 7 bb 4 1 3 7 4 2 8 4 5 0 0 8 5 3 9 7 M 50 10 58 1 b M 4 B 89 5 5 5 1 5 4 8 9 5 8 1 0 b 1 b 7 5fa 75 M 5 9 0 2 5 8 7 8 5 5 2 1 4 8 2 2 M 4 9 4 7 4 0 b ? 4 4 S h OCPARIURE < 1 0 2 3 « i 11 4 7 1 22 0/Vl/Vl rOLLOUING STAIION INDEX 7 AVERAGE TE STATION QUILTING ISLANDS 07 MONA ISLAND 2 V1EQUES ISLAND 12 V I R G I N ISLANDS ST THOMAS 01 DOROTHEA AES RED HOOK BAY TRUMAN FLO FAA AP ST CROIX 02 ALE» HAMILTON FLO FAA ANNALT BETH UPPER NEW WORKS CHRISTIANSTEO FORT - - D I V I S I O N A L D A T A - - - - - - - > ST JOHN 03 CATHERINEBURG CRUZ BAT JAN I 175 7 7k 4 75 7 1 1 78 8 78 3 178 3 1 177 8 78. 1 174 3 177 7 7b 0 I 1 7 1 5 - b EEB I 75.9 75 fc 75 » 75 b 1 79 1 77 8 77 8 1 1 7b 8 7 7 3 175 9 77 2 7b b S 5 1 2 7 0 HPERATURES AND MAR 1 UJ 7b 3 7fa 5 7b 3 75 b 1 78 9 77 5 77 9 1 171 1 1 74 5 175 1 77 7 7b 4 W 5 3 -2 7 - a A P R II 79 8 78 7 79 8 78 fc 1 81 7 80 2 81 3 1 1 1 81 3 178 3 181 0 79 7 = a. S 1 8 2 9 1 3 $[[ •( M A Y s m Lu 80 4 N79 5 80 4 78 7 M 81 4 80 1 80 b d 1 80 b (177 7 181 3 79 5 F(*[NC = S 3 8 - 3 E KOIf DEPARTURES EROM NORMAL (° JUN g J £ i 79 1 179 9 1 82 4 81 2 82 b 1 1 1 82 b 178 4 182 7 80 b i fOtll => S - 2 1 2 - 8 vine $ JUL «; ^ 83 2 80 0 83 2 181 4 1 83 a 82 b 83 9 1 1 1 8 3 9 178 9 183 2 81 1 1*1 ION = S 8 2 1 - 7 mod A U G i * ~ 64 4 61 7 64 4 82 5 1 85 1 83 8 184 7 1 1 1 84 7 180 b 184 5 82 b = S 1 9 2 a 7 SEP 1 f 83 4 81 9 83 4 82 2 1 85 1 83 ' 84 1 82 1 1 (184 3 83 5 (181 9 83 8 82 9 = 0 2 3 2 1 1 5 OC T 1 2 S M 80 8 81 4 1 83 9 82 7 83 4 1 82 a 83 1 N79 b M83 2 81 4 I S 1 8 2 2 - \ PUERTO RICO AND - 1 V I R G I N ISLANDS N O V I * £ 79 0 ;a 9 i 82 3 80 b 62 2 1 n neo b 81 4 M77 3 81 8 79 b tat £ 1 3 2 1 3 D E C I 1 179 7 78 1 79 7 7b % n 81 0 78 a 81 0 1 (178 5 79 4 79 b 17b 2 1 7fc 2 1 1 1 J 2 1 1 j ANNUAL 1 E i 178 9 1 1 82 0 ao b (181 ^ M 1 1 80 9 «; 7 9 * PS 4 1 S i . I ' r REFERENCE NO. 13 ESTIMATED WATER USE ;N ST. THOMAS, U.S. VIRGIN ISLANDS, JULY 1983 -JUNE 1984 ay Heriberto Torres-Sierra and Rafaei Qacosta 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 •STJ MATED MATER JSE IN ST. 'HOMAS, U.S. /IRGIN ISLANDS. JULY 983 • JUNE *98* By Heriberto Torres-Sierra and Rafaei Dacosta INTRODUCTION "..'ater use data iwithdrawal and return amounts) has always Deen the ~.ost jitficult element co refine in the hydro logic •:ycle. The r.eed to .:etermine the amount of water used to meet public, commercial and domestic needs among other uses is essential where the available supply is inadequate. In St. Thomas, U.S. Virgin islands, where streamflow occurs mostly during periods of intense rainstorms and ground-water resources are limited (Jordan and Cosner, 1973), water-use information is critical. In 1983, the U.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 east of Puerto Rico (fig. I). The island's popula- tion increased from 16,000 in 1960 to more than 47,500 in 1984, paralleled with an in- crease in water production to meet tfeft public water-supply demand (fig. 2). The water demands have increased also in response to tourism development. Although the production of water increas- ed with the installation of a large-scale seawater desalina- tion plant by the Government of the U.S. Virgin Islands, the demand has not been satisfied. •niv .oouc ••.' ~erc_-nt • r trie vater rrocuc-jc is accounted for, r.ostiv ^ue :o losses from leakage in uhe distribution system installed in 1949 (Priede- Sedgwick, Inc., .979). 'ither losses are _ue co unauthorized connections, faulty meters, and uncontrolled public faucets >fig. 3). WATER SOURCES AND USES The principal sources and uses of water in St. Thomas are shown in fig. 4. 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. 5a) is used by the seawater-de- salination plant (fig. 5b). Desalinated water from storage tanks (fig. 5c) is distributed to the urban areas in Charlotte Amalie (fig. 3d), by the Virgin Islands Public Works Department (VIPWD). Areas outside the public-water supply distribution system, such as the Donoe housing project at New, (fig. 5e) can be classified as self- supplied users. These obtain their water supply from rainfall catchments, wells, or from com- mercial water haulers ffig. 5f). U.S. GEOLOGICAL SURVEY WATER RESOURCES DIVISION The aain i:rban area of Charlotte Amalie is also served by a seawater svstem. This system supplies water for fire righting and flushing of toilets and open drains. Areas outside the seawater system depend on "gray water" fwastewater from other household uses) as their source of water for flushing toilets or irrigation. Where aquifers yield significant water to wells (10 gal/>in or more) these .ire also rapped as a source of water, even if saline, as reed for reverse osmosis units or for flushing. Bottled water produced locally or inported is an important drinking water source. Sottled water costs approximate- ly 51.25 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. Public-Water Supply Production of desalinated water during the study period averaged 2.4 million gallons per day (Mgal/d). Only about 0.9 Mgal/d (38 percent) was accounted (revenues from sales) by the VIPVD. About 1.5 Mgal/d was unaccounted for as previously indicated. A recent investiga- tion showed that leakage in the distribution system represents 30 to 40 percent of the total losses (CH2M Hill Southeast, 1983). The production of desalina- ted water for public supply increased to a peak of about 2.4 Mgal/d in 1975, declining thereafter to less than 0.6 Mgal/d In 1980. Since 1981, WAPA has Installed three nev desalination units with a total rated capacity of 3.1 Mgal/d. At present only two units are being operated. Full production capacity will be required when the East End Transmission System becomes operational (fig. 6). This distribution system was constructed in 1977 but ha* not been utilized. Water pumped to the seawater distribution-system averages 1.0 Mgal/d. Only about 0.3S Mgal/d of this amount Is accounted for at the public sewage treatment plant serving Charlotte Amalle. The remainder may be lost through leaks In the seawater-distrlbution system. However, viricus storm arains in Charlotte Analie are continuousiv flushed to the ocean by taps from cae seawater- distribution svstem. Discharge from two of these taps were measured and had an average flow of 0.08 Mgal/d each. Five of these taps would account for '5 of the unaccounted flow.. The cost of potable water to WAPA from 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 Gomez, 1983). The actual costs charged by VIPWD to consumers connected to the distribution system is 514/kgal (VIPWD personal communi- cation, 1984). rfcermoe/ecfr/c-Powe/- Thermcelectric-Power Gene- ration is the largest single water use category in St. Thomas. 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. Oooiost/c S*lf-Suppll*d • Hulnfull About two-thirds of the population in St. Thomas is not served by the potable public water supply distribution system, and thus classified as domestic self-supplied. Rain- water collected from rooftop catchment systems and stored In cisterns, and withdrawals from ground water are the sources for domestic self-supply. Estimated water use for this category was about 0.75 Mgal/d. Of this amount, 0.60 Mgal/d (80 percent) was supplied from rainfall. This Indicates that rooftop catchmenta are a major source of water for moat private homes especially in the more humid areas of the island (fig. 7). Virgin Islands law requires all dwellings, apartments and hotels to have a minimum cistern storage of 10 gallons for each square foot of roof area for one story buildings, and 15 gallons for each square foot of roof area for two or more story buildings. All other buildings 3 6T»OO' ie»ao'- 1B*OO'- 12. ina. 09 O z t. O ire recuirec to have cisterns with a minimum useable capacity jf i* gallons per square foot of roof area except churches and warehouses, which are not required tc conform to this standard (Jordan and Cosner, 1973). A comparison of yields be n rooftop-rainfall catch- mev _ at a high rainfall (Doro- thea) and at a low rainfall area (Red Hook), was made using data from July 1983 to June 1984. The comparison was made for a family of four using 25 gallons per capita per day (25 gpcdl with a roof area of 1,000 ft and an initially full cistern (10,000 gal). The family 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 systems is estimated at $17 to S19/kgal (CH2M Hill Southeast, 1983). The major cost is associated with construction of a cistern. Domestic Self-Supplied - Ground Wfttr Ground water withdrawn for domestic self-supplied use was about 0.15 Hgal/d. Ground-water withdrawals by the Virgin Ir 's Housing Authority (VIHA) wa._estimated at 0.10 Hgal/d. An additional 0.05 Hgal/d was used by other domestic self- supplied users. Ground water for domestic 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 wai.dr qua^nv ,_ i tnese areas ire limited by excessive depth to water, seawater intrusion, waste-water contamination, and contamination fron seawater mains. Commercial Salt-Supplied Condominiums and hotels used about 2.0 Mgal/d of saline water. This is used principally for cooling, flushing toilets, and swimming pools. Snail desalination plants produce about 0.1 Mgal/d freshwater. About 0.2 Mgal/d of the commercial water-use is ground water. This is used mostly for flushing toilets. In tome areas, where the ground water Is of good quality, the waste water is used for irrigation of lawns (Mahogany Run). However, most of the commercial facilities are located near the coast and pu*p saline-ground water. Water haulers supplied an estimated 0.07 Mgal/d of desalin- ated water from the VIFW standplpes to commercial users. The average price of water delivered by water haulers la S55/kgal (Ajayl and G6mex-C6maz. 1983). An estimated amount of 0.05 Mgal/d was obtained from rooftop rainfall catchment*. Public Watte-Witer Treatment There are seven public waste-water treatment facilities in St. Thomas (fig. 9). The airport plant, serving Charlotte Amalie, discharges about 0.5 Mgal/d to the ocean. Instantan- eous flow rates measured in June 1984 ranged from 0.16 to 1.4 Mgal/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 mostly public-housing projects. These discharge about 0.20 Mgal/d to streams and the ocean. SOURCE, DISTRIB FIOUKe St. Seaveter inte«* it tke r»»rmoele«»rlc Pomtr fltm at Krvm Cay (Sub »•••)• FlOUlie Sd. D»m»tllc and commirclml men at Cftariorr* /••«;/• area. I Pipeline Installed but not operational as of July 1M4. | | Areat not torved FIQUHe «. Area* *«r»ed or f»e rreeft-varer dlttrlbftlon *y*teai. 0 1 2 3 4 MILES IOU*C 7. ..... .......i, III !«»• fPropared o, H.J. Ca'reaftcrt. tHWt) HO**.} FIGURE 3. Compariton or lh» qutnlfty of mtttr ji KJ Uncontrolled Hazardous Waste Site System A Users Manual (HW-10) Originally Published in the July 16, 1982, Federal Register United States Environmental Protection Agency 1984 TUT oo: TABU 2 PKIIBAIII.ITT or GEOLOGIC MATIKIALS* Approxlaata tang* of Aaaigatd Typ* o f M a t e r i a l H y d r a u l i c C o o d u c t i v l t y V a l u * Clay, coapact till, ahala; unfracturad <10~7 ca/*ac aataaorpblc aad igaaoua rock* Silt, loaaa, ailty claya, ailty 10~5 - 10~7 ca/ loaaa, clay loaaa; laaa paraaabla llaaatoaa, doloaitaa, aad aaadatoaa; •odarataly paraaabla till Flo* aaad aod ailty aaad; aaady 10~3 - 10~5 CB/MC loaa*; loaay aaoda; aodarataly p«tM*bl* ll***coo*. dolomitaa, aad •aodacoo* (no kanc); aodorataly fraccvnd Igvaova aad Mtaaorpbic rock*, «oa* coarM till Gravtl, saad; hlfhly fracturad >10~3 ca/Mc Ignaou* aad aataaorphic rock*; pcraaabl* baaalt aad lam*; kant llaaatoaa aad doloait* froa: Da via, S. »., Po realty aad Hraaakillty of aitural Mat*rtala la Flow-Throutk Porou* Madia, PIMM, t.A. aad J.A. Charry, Crouadwatar. Prantlea-Ball, lac., fc« York, 1979 , Forealty aad FUraaabillty of »atural •at*ti«l* la , R.J.M. Mfa*t ad., Acadaalc Pr***, lav York, 1969 15 TUT 002 049 REFERENCE NO. 11 REFERENCE NO. 14 A T L A N T I C C A R I B B E A N U.S. Virgin Islands Dept. of Planning and Natural Resources Coastal Zone Management Program IN* m*> wm ffcunccd hi pwl under th» CoMtil Zoo. MwMg*nwnl Act of 1t72. (dmlntolwwl by lh» Office of Coutal Zone MwMgwnwri, NMontt Oc*«He and ZONING DISTRICTS LEGEND COASTAL LAND AND WATER USE PLAN i—I | Preservation | Conservation Recreation. Traditional Uses j_| Protection, Residential Low Density ^| Residential. Medium Density | Residential, High Density l~] Water Dependent & Related Commercial Marine Facilities | Water Dependent & Related Industrial Marine Facilities U Commercial H Industrial fS3 Excluded Federal Land w-1 W-2 Light jnd Hedvv InduMru' Wjicrlronl • Plvtturc Warerfronl • InduMrul TUT REFERENCE NO. 15 DATE: JECT: FROM: TO: JAN 06 S68 UNITED STATEb ENVIRONMENTAL PROTECTION AGcNCY REGION II Preliminary Assessment and Confirmation of Authorization of CERCLA Removal Action Monies for the TUTU Well Site, Anna's Retreat, Saint Thomas, U.S. Virgin Islands - ACTION MEMORANDUM Carlos E. On-Scene O'Neill Coordinator Stephen D. Luftig, Director Emergency and Remedial Response Division THRU: 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 eastern 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 assume the role of Lead Agency after sampling results indicated that several commercial wells were found to be contaminated with ~- hazardous substances. This verbal request was followed by a formal request in writing by DPNR on August 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 tetrachloroethylene (TCE). The EPA 10-Day Health Advisory Level of 175 ppb was exceeded in three (3) of twenty four (24) wells sampled, with two of the three contaminated wells being private residential wells.* The concentrations found ranged __ from 240 to 7,600 ppb with seven (7) additional wells being below the EPA 10-Day Health Advisory, but above the U.S. Virgin Island's interim maximum permissible concentration levels set on September 1, 1987, by DPNR for volatile organics in drinking water in the Turpentine Run Aquifer (50 ppb for a single com- pound or 100 ppb for total volatile organic compounds). Three of the previously mentioned seven wells were residential wells. REQIOM II FORM 132O-1 (•/8fi) -2- Th i s Action Memorandum will document funding authorized for Phase I of the Tutu Well Site CERCLA Removal Action. Phase I addresses only residences having contaminated drinking water wells with volatile organic 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 primarily 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 ceiling authorized for a 52-week period is $100,000 of which $40,000 is estimated for mitigation contracting; $45,000 for TAT's extramural costs; 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 subsequently 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 was made verbally on July 15, 1987 from DPNR. On July 31, 1987, a verbal request for EPA to assume the role of Lead Agency was made, and this was followed bv a written confirmation of the request, dated August 10, 1987 (received by the Emergency and Remedial Response Division on August 19, 1987). The initial request was based on a report that one well was reported to have a strong odor, characteris- tic of a petroleum product. This well is a major source of commercially provided potable water for.the eastern portion of the island. VKPA's preliminary investigation commenced on July 21, 1987, with a field reconnaissance and sampling of this one well and six additional wells identified in the immediate area. Several of th««e wells are also major water suppliers of public drinking water to the eastern part of the island. -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. Based 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, EPA 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 which service two three-family homes and one apartment building housing twelve studio units. 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—four (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 and analyzed for suspected volatile organic com- pounds on July 22 and August 10, 1987. Listed below are the maximum concentrations of the hazardous substances identified in the drinking water wells: -4- Con tami nan t Tetrachloroethylene Trichloroethylene Benzene Max imum 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-Day 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 excess of the EPA 175 ppb PCE 10-Day Health Advisory Level for a three-family house and one apartment building housing twelve studio units. In the other three family apartment dwellings, the well con- tamination exceeded the interim DPNR drinking water standard of 50 ppb for any single volatile organic constituent. in addition to the exposure via consumption of the water, or eating food prepared with this water, showering with water contaminated with volatile organics can contaminate the air to significantly unhealthy levels. -5- 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 releases 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. D. Current Actions to Abate Threat v EPA has commenced an investigation of the Tutu Hater/Turpentine Run Aquifer by establishing a cooperative agreement with the U.S. Geologic Survey to define the characteristics of this aquifer and to determine the extent of contamination. EPA and DPNR have also completed Aquifer and a monthly well monitoring program is being developed. V DPNR has issued a total of ten (10) orders/advisories to well owners to close sixteen (16) wells. A local dry-cleaner has been identified as using and storing PCE. Handling, storage and disposal practices from this facility are unknown at this time. DPNR has proposed to issue an advisory to local dry cleaning establishments instructing them to properly store and hold all waste for proper disposal by an industrial waste hauler. \/DPNR with the assistance of EPA is conducting an assessment of at least nine (9) facilities identified to b« potential sources of hazardous waste and/or substance releases in the Tutu area. -6- EPA has cleaned the homeowner's cisterns that have been contam- inated by hazardous substances from the groundwater, modified the existing home plumbing to terminate well connections, and intends to continue to deliver clean water 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 temporary alternate source of water for affected consumers. IV. ENFORCEMENT The contaminant plume is generally believed by both DPNR and EPA, to have its source from past and present improper handling and disposal practices of organic solvents, possibly 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 A. Objective of the Phase I Removal Action The primary objective of the Phase I of the removal 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 complex housing twelve studio units were identified as being dependent on groundwater from their own private wells. Their respective wells were ordered closed-down by DPNR 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 removal action was initiated. Water storage cisterns, which received contaminated groundwater from affected wells, were cleaned and sanitized. Cisterns were filled with clean, safe, drinking water. Water tank trucks from local water haul- ers will be providing water for the affected cisterns on a reg- ular basis. Plumbing modification was made to disconnect water lines from the contaminated wells which provide groundwater to the cisterns. TUT 002 0510 -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 objective 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 vacuum 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 cisterns with clean and safe drinking water........................................... $ 2,665 Provide cisterns with clean and safe drinking water on regular basis according to a pre- approved schedule............................... $15,000 Contingency (10%)............................... $ 4,300 Total Mitigation Cost................. $40,000 TUT -8- Extramural TAT Cost TAT Monitoring and sampling program (including travel and per diem)................. $35,000 TAT Technical and administrative support (including travel and per diem)......... $10.000 Total TAT Cost $45,000 Intramural EPA Cost (Including travel and per diem)..................$15,000 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-weeka 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 Conditions at the Tutu Well Site meet the requirements of Section 300.65 of the National Contingency Plan (NCP) for a CERCLA/SARA removal action. EPA has determined that there is a threat to public health at the site (Section 300.65(b)(1). This determination was based on: 1) Human exposure to unacceptably high levels of acutely toxic substances (Section 300 .65(b)(2)(i), and 2) Comtamination of drinking water supply (Section 300.65 -9- The resident population at risk currently relies on private 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 supply of potable water 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 1, 1987, by the Director of the Emergency and Remedial Response Division to the OSC for the CERCLA removal action at the Tutu Well Site. The mitigation contracting ceil- ing is estimated at $40,000, with an additional $45,000 for TAT costs, and $15,000 for EPA costs. Your authority to authorize these funds is pursuant to Deputy Administrator Alvin Aim's memorandum of Delegation Number 14-lA dated April 15, 1984, and Richard Dewling's Redelegation order R-ll-1200.6 of August 29, 1984. APPROVAL: DATE: DISAPPROVAL: DATE: cc: (after approval is obtained) C. Daggett, 2RA j. R. Salkie, 2ERR-DD P. S. Luftig, 2ERR R. G. Zachoa, 2ERR-RP T. B. Sprague, 2ERR-RP T. J. Czapor, 2ERRD-SC P. G. Pavlou, 2ERRD-NYCRA Marshall, Gelabert, Gherardi, Sullivan, 20EP 2CPO 20PM-FIN PH-214F (EXPRESS MAIL) Fields, WH-548B McKechnie, 2IG 0613 #0. M/29/V SAMPLE LOCATION r PHOTOVAC SAMPLING RESULTS TUTU VELL SITE ST. THOMAS, U.S. VIRGIN ISLANDS SAMPLE DATE DATE HARTHMAS CRUSH HARTKMAN WIRY 4 USDS VELU1 4 VIVOS VELM1 fZLLtf ?IHA RUN TILiET MELD •7-473 17-474 I7H75 17-471 17-477 17-471 17-471 •7-410 17-411 07/22/17 07/22/07 07/22/07 07/22/«7 07/22/07 07/22/17 07/22/07 07/22/07 07/22/07 07/30/07 II 07/30/07 IN 07/30/07 CV 07/30/07 CH 07/30/07 C» 07/30/17 I« 07/30/07 CV 07/30/07 CV 07/30/07 U 0 0 7 7 133 IS 3 7 0 If it fSt 11 102 3 f4 Cl 200 31 II ••• ••• 41 31 'HO 711 2040 412 327 TABLE I NELL SAMPLING RESULTS TUTU NELL SITE ST. THOMAS. U.S. VIRGIN ISLANDS SAMPLE DATE DATE V0MBZR SAMPLED ANALYZED SOURCE BEV TCI PCI fOL OCX OCNS f 4 IIBOS 11 001A 00/10/07 00/13/07 CV CGLZN NELL 01 002K 00/10/07 00/13/07 CV ICLIN NELL 02 003A 00/10/07 00/13/07 CV ECLIN NELL 03 004* 00/10/07 00/13/07 CV HASTHNAN IAKERT OOftA 00/10/07 00/13/07 XV HARTHXAJI CRUSH 004A 00/10/07 00/13/07 XV HARTXXAV ESTATE 007A 00/10/07 00/13/07 IV ROORIG0U AOTO OOOA 00/10/07 00/13/07 XV BRTAM OOU 00/10/07 00/13/07 CV ALPHA,LtONA*0 010A 00/10/07 00/13/07 IV IMXTfMOCXTA 011A 00/10/07 00/13/07 N DCVCOV 03 012A 00/10/07 00/13/07 CV OITCOV 11 013A 00/10/07 00/13/07 CV CEDE 014A 00/10/07 00/13/07 VA DMITRI 020A 00/10/07 00/13/07 CV fXHA VtLL 03 OtlA 00/10/07 00/13/07 XV ?XHA VBU. 01 022A 00/10/07 00/13/07 XV UMSfl 030A 00/10/07 00/13/07 XV ,TEXL 031A 00/10/07 00/13/07 If NARVtT 032A 00/10/07 00/13/07 If HATHXAS 033A 00/10/07 00/13/17 M FRANCOIS 034A 00/10/07 00/13/07 If DWCH 03SA 00/10/07 00/13/07 If TXLLIT 03SA 00/10/07 00/13/07 CV 130< TILLIT DOT 037A 00/10/07 00/13/17 CV 140( FIELD ILAVI 040A 00/10/07 00/13/07 VA ( 2] 11i: 11 1 21 4; ( K( > ( ) 34 1 i 1 79 i 31 1 43 ; 11 3 31 13 N \ \ 171 I 7CO( 1 €1 1 111 1 1 1 24( \ 121 1 < I l 1 \ \ \ r i\\\\ \ ii 1 3! 1 ( 213 43 74 41 1 1! 0 1! 1 I! •4 i 144 i \ 174 1 42f 1 4 1 .T 1 . I . i . > • ! . • . • •. • • • • » I . L . L . I , 1 . I . 1 . » . » . » .ff TABL1 IX ttipn Nap: 7. Nathlas 0) 8. Smith U) 9. Francois 10. Tillct 11. Ramsay U 12. 4 Hinds REFERENCE NO. 16 U. S Geological Survey Water Resources Division Caribbean District Open - File Report A SURVEY OF THE WATER RESOURCES OF ST. THOMAS. VIRGIN ISLANDS OO2 OSIB UNITED STATES DEPARTMENT OF THE INTERIOR IN COOPERATION WITH THE GOVERNMENT OF THE VIRGIN ISLANDS OF THE UNITED STATES ABSTRACT St. Thomas, with an area of 32 square miles, is the second largest of the Virgin Islands of the United States. The island is i mountainous, and slopes commonly exceed 35 degrees along a central ndge 800 to 1,200 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 predominantly storm 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. Two smaller areas—Long Bay and Lindberg Bay on the outskirts of Charlotte Amalie have estimated ground-water yields of 70,000 and 30,000 gpd, respectively. Fully developed* the surface- and ground-water resources of the island could yieid^i.S million gallons of water per day. 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-derived j 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 mineral content to ground water during base flow. Caribbean District Open-File Report UNITED STATES DEPARTMENT OF THE INTERIOR Geological Survey A S U R V E Y OF THE WATER R E S O U R C E S OF S T . T H O M A S , V I R G I N I S L A N D S by D. G. Jordan and O.I. Cosner Prepared in cooperation with the Government of the Virgin Islands of the United States 1 9 7 3 A S U R V E Y O F T H E W A T E R R E S O U R C E S O F S T . T H O M A S , V I R G I N I S L A N D S by D. G. Jordan and O. J. Cosner LOCATION AND GENERAL SETTING Location The Virgin Islands, forming part of the Antilles Island Arch separating the Caribbean 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 50 miles east of Puerto Rico (f ig. 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 in area from slightly less than a square mile to a few hundred square feet. ATLANTIC OCEAN C A R I B B E A N S E A Figure 1 .--Location of the Virgin Islands of the United States. Population Climate St. Thomas has about 17,000 permanent resi- dents and a transient population of tourist and im- ported laborers of about 8,000. The majority of the population is urban—about 20,000 people live in Charlotte Amalie, the only city and also the seat of government of the Virgin Islands. The permanent population is increasing rapidly and is expected to double by 1980 (unpuolished data, V.I. Planning Board, 1964). Topography The land surface is almost entirely 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 gradient. 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 relatively 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, primarily 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 allowed to revert to brush and secondary forest. Now, land use is changing rapidly, much of it brought on by the jet age and its rapid mass trans- portation. Increasing population, in part caused by development of to* Island as a retirement haven and by tourism, result* in 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 land use could very well affect the available quantity and quality of the water resources. The average annual rainfall is about 45 inches and the average temperature is only SOT, but the prevailing impression of the climate is one of dryness, especially in the winter. This is espe- cially true of the east 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 driest months and September and October the wettest. Most of the rain occurs as short, intense showers lasting but a few minutes. Rams 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 rams 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 , 1 960 , the result of a stationary tropical depression. The island lies in the path of hurricanes and occasionally receives heavy rains and high winds from passing storms. The incidence of direct hits is low—damaging storms having a frequency of about one every 33 years. The last hurricane 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 low of 72 .0°F in February to a mean high of 87 .8°F in 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 is given in table 1. A wind rose for the same period is shown in figure 2. Relative humidity is high owing to the proximity of the sea. At Harry S. Truman Airport during 1953-58 relative humidity was highest, averaging 81 percent,in the early morning hours, and lowest, averaging 66 percent, in the early afternoon. Average daily humidity is given in table 1. *i -(••29 ATLANTIC OCEAN Granitic rocks fifty///.aqtf/jfca x fit* o o V^-4i-vv-A^ * / / / / / _ ^ _ ^ AMALIEZT -ia*zo CARIBBEAN SEA • 5«00' 3 miltt «4»S9 Geology generalised after T W Donnelly, I960 64*50 EX P L A N A T I O N ALLUVIUM-Silt, cloy, ond thin, discontinuous beds of sond ond grovel Includes beoch sond. Estimated maximum thickness 50 ft TUTU FORMATION -Tuffoceous conglomeratic mixture 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 o few thin beds of tuff Estimated maximum thickness 600 ft. LOUISENHOJ FORMATION-Water-laid tuff, breccia, and o few thin beds of limestone Maximum thickness known 13,000 ft WATER ISLAND FORMAT ION-Lava flows, flow breccia, and water-laid tuff 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) has been studied for many years, but only recently have the geologic formations been named and described :n detail (Donnelly, 1960, 1966). The .-.ames of geologic formations used in 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 (and older?) age. The oldest rocks, those of the Water Island 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 Louisenhoj Formation 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 volcanic orifice 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 Formation. The Outer Brass Limestone was deposited on the flanks of the Loulsenho) volcanic cone during a period of volcanic quiescence. It consists of 200 to 600 feet of thin-bedded graphitic slllclfied radlolarian limestone and a small amount of included tuffaceous material. The Tutu Formation, the youngest rock exposed on St. Thomas proper,is composed almost entirely of angular debns derived from the Louisenhoj Formation and minor limestone debris from thin limestone deposited contemporaneously with the Tutu Formation. The rocks were subsequently tilted to form a northward-dipping homocllne. Dips range from 15 to 90 degrees and average about SO degrees. Locally the formation* are overturned. The permeable zones that these rocks once may have had after deposition 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 is 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 directions. The valleys of the island have similar trends and are apparently the result of selective erosion of rock weakened by faulting and jointing. Prime zones of ground-water availability, therefore, follow the valleys. Small alluvial deposits ranging from Pleistocene (?) to Holocene in age he in the valley of Turpentine Run in east-central St. Thomas and the larger coastal embayments. The alluvium of Turpentine Run lies 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 Mariendal 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 infiltrates streamflow when the ground- water 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. Some coastal embayments headed by intermit- tant streams contain small deposits of alluvium similar to that of Turpentine Run. Maximum thickness of these deposits is estimated to be SO feet, and their a real 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 interfingers with calcareous sand and at times contains lenses of mangrove- swamp deposits. Therefore, the deposits are of minor significance as sources of water. OCCURRENCE AND MOVEMENT OF WATER Water mover through a cyclic pattern—the hydrologic cycle—in which 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 a real extent of the rainstorms; ( 2 ) the slope of the land; ( 3) the moisture content of the soil and vegetal cover ( 4) the infiltration capacity of the soil and underlying rocks; and (5) the size, numDer, and interconnection of openings in tr.e aquifer. Rainfall ~am is the only natural source of fresn water to replenisn the water resources of the island. R a i n f a l l is seasonal, v.-ith the rainy season :n late summer and early fall and a secondary wet season usually in May. '.'early naif the rain tails iuring August-Novemoer ( :':g. 4 '> . Rams exceed- ing 1 inch in 24 hours come six or seven times a •/ear. Four to 1 5 inches of rain falls in a 48-hour period about once every 2 years in large storms. These rains can occur in any month but are more likely during the nurncane season ( August- Xovember) . About half the time annual rainfall is between 40 ana 50 inches i fig. 5 ) . Lass than 10 percent of the time annual rainfall is less than 35 inches, which usually means a major deficiency during the normal wet season and drought. The cumulative departure from average and the 10-year running average of rainfall shown in figure 6 shows that at this time of writing (1 967 ) the island may be entenng a period of deficient rain- fall. 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-term decline of about 10 inches in annual rainfall since the peak of the surplus rainfall period in the early 1930's. The most severe droughts of record occurred in 1964 and 1967 , when but 27 and 24 inches of rain fell, respec- tively. Areal distribution of long-term rainfall, shown in figure 7 ( see letter "a ") , is controlled by topo- graphy and the prevailing easterly to northeasterly winds. However, individual storms may or may not show the effects of orographic control or pre- vailing winds and the a real distribution of the storms can be very irregular ( fig. 7—letters "b" to " f " ) . Soil Moisture The soil zone over most of St. Thomas is not more than 1 foot thick. Where of sufficient thick- ness it has, however, the unique property of absorbing large volumes of water—as much as 12 inches in 24 hours (R. Scott, SCS, oral commun. , 1963 i . Lxammation ci the soil zone wnen arv shows it to oe coarsely ^-ranuiar. rv/mg to dump- ing of ciay ana silt particles, rroicngea satura- tion is necessary oefore t.-.e granules creak down. As a result, the sou ~as a r.ign perrr.eaoiiity -ntil well saturated, o u t , once saturated, :t oecornes poorly permeaole and retains water in tr.e pore spaces oetween carticies and rejects any excess. . oservaticns a unrig rainstorms indicate tr.at the typical soil zone will aosorb aoout 2 .ncr.es of water before some water .s rejectee or moves to tr.e underlying oedrock. fully saturated. :r,e soil will prooaoly retain 3 inches o: water per root of depth. The capacity of the soil to hold large volumes of water, together with infrequent major rainstorms and a high evapotranspiration rate, seriously reduces ground-water recharge and storm runoff. Evapotranspiration Most of the water trapped in the soil zone returns to the atmosphere by evaporation or tran- spiration by plants (evapotranspiration). 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 granu- late is also conducive to evaporation. As water is evaporated from the surface of a saturated tight soil, the soil again becomes granular and exposes the soil at depth to the circulation of air. Con- sequently, further rapid evaporation of soil moisture results. Transpiration is a major means of water loss from the soil zone and also from the upper part of the aquifer, if the water table is 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 evapotranspiration may be seen in the channel of Bonne Resolution Gut below the gaging station. The gut flows in a predominantly bedrock channel a few feet wide for about 1, 500 feet before reaching the alluviated embayment at Dorothea Bay. Base flow of the stream, when less than 10, 000 gpd (gallons per day) , disappears in this reach. The loss is attributed principally to transpiration by the dense growth of brush and TUT (o) overoge onnuol (b) March 25-26. 1963 (d) Moy 9-13, 1963 (e) August 28-29. 1963 0 1 2 5 4 SMILES (c) April 7-6. 1963 (0 December 10-13, 1965 Figure 7 .—IiohyetaU In Inches of the long-term distribution of rainfall (a ! and of Individual rainstorms (b-f) on St. Thomas. trees oordering tne stream. from :.-.e appearance ~f the vegetation in a dry period, jruy trse vegeta- tion in a strip about 100 feet wide witn a total area 3f about 3 acres benefits from tne stream. A minimum water loss of 10,000 gpd, 2. 6 million ;a lions annually, would indicate sn evaootransDi- ration rate of 1.2 million gallons cer acre cer year, :r 44 incnes. Bowden i 1968) computed mcntnly potential evaporation and soil-moisture deficiency at six stations on St. Croix using the method devised by 3. .V . Thornthwa ite. Potential evaporation ranged from 58 to 69 inches and averaged 62 incnes per year. Actual evapotranspiration (derived from potential evapotranspiration and change in soil moisture) ranged from 41 to 46 inches and averaged 43 inches per year. Bowden's data shows a soil- moisture deficiency 9 to 11 months of the year at the different stations. Surplus soil moisture occurred only in the months of Septemoer to November. The authors believe that conditions are similar in St. Thomas. Stream flow The 5 to 10 percent of rainfall not returned to the atmosphere by evapotranspiration 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 and carry only storm runoff. Only two streams on the island have perennial reaches. In these reaches, about one-half to three-fourths of the flow is storm runoff, and the remainder is base flow (ground- water outflow to the streams ). From 0.5 to 2 inches of water annually reaches the sea as storm runoff. The amount of storm run- off varies from basin to basin, depending upon topography, soil moisture, exposure, and vegeta- tion. Base flow of the streams with perennial reaches , while often equal in volume to storm run- off, seldom reachet the sea. The flow usually infiltrates into alluvial deposits in the lower reaches of the streams. Ground Water From 0.5 men to as much as 5 inches of the rainfall annually infiltrates tne sou ^r.a rocks to reacn the ground-water reservoir, v.'ater in the ground-water reservoir or aquifer moves cy gravity toward the sea. '.'.'here tne water taole is intercepted by the land surface, v/ater is dis- rnarged as a spring or as case tlow to 3 stream. 'A'here it is -ear the land surface. =ucn as along stream channels and in coastal omoayments. large volumes of water are trar.spirea by plants whose roots tap the ground-water reservoir. The transpiration by plants directlv rrcrr. :ne water table is so great that only minute quantities of jround water ever reacn the sea, -jitner as stream- flow or as seepage directly tr.rou^n tr.e soil rocks . fresh- Salt-Water Interface fresh water in the aquifers =>lonc :r.e coast is .n contact with salt water IP. a dynamic r/3tem. So long as water levels graae seawara , fresh water will discharge to the sea at the snore. During times of ground-water recharge, the tresh- water lens thickens, displacing the underlying, heavier, salt water downward 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, is not entirely flushed out by fresh water v/hen recharge occurs. Some remains behind, where it mixes with influxing freshwater. The interface zone of brackish water is thick where fluctuations in the size of the fresh-water lens are large. In some coastal areas, where the fresh-water lens is thin because of lack of rainfall or unfavor- aole topographic or geologic factors, the under- lying interface zone may extend inland several hundred feet at depths of but a few feet below the water table. The balance between salt water and fresh water in coastal aquifers is delicate and can easily be disrupted by man's quest for water. Salt-water encroachment can readily result by removing more water from the fresh-water lens than is being replaced by recharge or by pumping a well at an excessive rate, in which case the fresh-water head is lowered, and movement of salt water upward or horizontally into the fresh-water zone is induced. 10 .VATER 3 C URGES Fresri water has always seen :n critical supply .n St. Thomas. Rain collected on roofs ar.a stored in cisterns is still the source of -.vater fcr r.cst rural ana ijrsan dcrr.estic supplies, before I960 .-.illside rain catchments ana a few dug -.veils -.vere tr.e major source cf v/ater for cuolic sucpues. Since tr.en, desaiteo water r.as oecorr.e tr.e major source of water for public suopues, jnd v/ater cargea fro.r. Puerto ?>icc .s a ciose secor.c. Charlotte -.ma he Charlotte Ama'lie nas a aual puolic v/ater system. Tresh water is used for drinking and general house- r.old needs, and saltwater is used for sanitary and fire-control purposes. The fresh-water sucply. ootained from salt-water distillation plants, hill- side rain catchments, and a well, is supplemented by water barged from Puerto Rico. Potaole water use and the sources of the water in 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 in the early 1960's, but by the late 1960's, desalted water became the principal source of supply. Nearly all buildinas . both private and public, in Charlotte Amalie have roof catchments and cisterns. In 1926, before the establishment of a public water system, about 200 private and 17 public dug wells were in use in the urban area. Since then most of the wells have been abandoned because of sewage and salt-water contamination. Some of the salty water was drawn into the wells from the sea as a result of overpumping, and some of it entered the wells from leaky salt-water pipes. A few of the wells are still pumped occasionally for nondnnking domestic supplies and for construc- tion purposes. In recent years, wells have oeen dug in eastern Charlotte Amalie for a supplemental •.vater supply for the two public-housing projects. Several other wells have been dug in the same general area for water for nondnnking domestic use. Since 1926, 18 public hillside rain catchments have been constructed. Of these, 14 are con- nected to the urban water-distribution system. •'» ater is -.aulea from tr.e remaining four catcn- ments oy inciviaual users or by water haulers. The total area of the public catchments is esti- mated to 3e 24 acres, and the storage is estimated :o oe 1-4 minion gallons. Reliable figures are not available or. :r.e amount cf water usea from any of the catcn.-.er.is, jut total yield is estimated to be 3 0 , 0 0 0 3pd. :.-. addition to the puolic catchments, four pnvateiv owned catchments are in the ursan area. A gallery '.veil at tr.e airport v/as an important source of -.vater in the 1950's. :t recortealy yielded 13,000 gpd. An attempt to increase pro- duction resulted in salt-water encroachment, ruining the well as a source of potable v/ater. I;i 1962 the first desalting plant, with a capa- city of 250,000 gpd, was put into production, in 1966 a plant of 1 million gpd was put into produc- tion , and, by 1967 , the start wa s made on a 2.5 million gpd desalting plant. The demand for water has increased six-fold since 1960 and shows little indication of leveling off. In 1962 and again in 1966, when desalting plants were put on line, water demand increased almost overnight 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 SI .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 53.50 per 1,000 gallons. Water is sold to the consumer at a cost of 50 cents per ton, about S2.00 per 1 ,000 a a l i n n s . The difference between pro- duction cost and delivery cost is absorbed by the Virgin Islands Government. Rural St. Thomas Rooftop catchments and cisterns are still the -.ajor source of v/ater for rural St. Thomas. Dur- .r.g prolonged dry periods, rainwater is supple- :-ented by water hauled from public-supply points .n Charlotte Amalie. Small ponds have been con- structed, tapping storm runoff for irrigation water for truck gardening and drinking water for stock. Since 1962 several private wells have been drilled 11 "bser/ations :ncicate tr.at wind velocity ar.a roof configuration are major factors in t.-.e recover/ ;: rainfall from residential structures. Kign '.vine -.•/ill blow ram off a pitched roof oriented parallel :o trie wina, v/nereas a rain shadow in proportion to the degree of roof pitch will occur on the lee siae 3t 3 roof oriented perpendicular to tne wind. A V-snaped roof will be affected in the same :r. anr.er. iitr.ouqr. probably to a lesser degree . The "at e:;icient is probably a flat roof with 3 irjw Up j.':ur.c :.-.e eaqe. '.Vater cannot blow or: t-.e r c o f . .-.or .s a rain sr.aaow created, and the lip converts t.-.e roc: into a temporary storage container during -.igh-ir.ter.sity rains. Rainfall recovery on flat roofs is prooaoly greater than tnat measured from tne ,-.ills;dc- catchments, wnereas recovery on Ditch "sets .5 probably 10 to 20 percent less, aeoenamg -n crientation and steepness of pitcn. Figure 25 shows an estimate of the annual costs }f collecting rainwater and of cistern storage tor 3 small home. Cistern cost, amortized over 3 20- year period at 5 percent per year (interest costs not included 1, .s estimated to range frc.r. ; 5 . 0 0 per cuaic foot for 10 percent storage to £ 2 . 5 0 per cubic root for 100 percent storage of the total annual recovered rainfall. Rainfall recovery was 500 •estimates :o oe "C cercer.t c: -r. ar.r.La^ .-2..-.:aii :: 40 ..-.c.-es over 1 , 0 0 0 square feet :r -cct." -e- : a very uncer tr.ese conaitions would y.eia ^8 - pd. it was assumed that water less cue tc insufficient storage would oe mace up oy v/ater pure .-.a sea :rcm water nauiers at costs of 10, 20, or 30 dollars per 1,000 gallons. The figure snows that, using these criteria, the optimum cistern storage would be about 20 percent of expected annual recovery, :T aoout 3.5 gallons per square foot of catchment. -verage yield from rainfall alone would be aoout 40 gpd. Annual water cost would range from 5130 to il 96 annually, or 5 7 . 4 5 per 1,000 gallons to i l l . 20 per 1 , 0 0 0 gallons. Annual cost of loo percent cistern storage would be 5294 or 516.80 per 1 ,000 gallons . Ground Water Ground water is available in nearly all parts of the island in sufficient quantity to be of impor- tance to the water supply. In general, yields cf wells are sufficient only for individual domestic supplies. There are, however, a few areas where yields to wells are large enough to warrant 400 to ac. <= 300 z CO Oo 200 100 Supplement water 130 per 1000 gallons k Storage i5 gallons per squarei foot! (28 percent) ; Supplement water | 120 per 1000 gallon's f^StdragejlO gallons per siuore foot (58 percent) s Supplement water »101 per 1000 bollons "Annual cost cistern 10 20 30 40 50 60 70 80 90 100 CISTERN STORAGE. IN PERCENT OF TOTAL CATCH Figure 25.—Annual cost of water from a roof catchment of 1,000 square feet with a maximum yield of 48 gallons per day. 31 -.--.}<:3ie ,: .iraes :cr aetermiru.-g ,T3ur.a-water pctenuai from pnysical :.-;ieria jr.o "xamoies for selected wells Ka;n:.3u Inches Value < -10 •4U-45 1 -45-50 2 >SO 3 1 ropoqraor.y Crest of riage General slope Central Value 1 .' 1 valley onj general slope Large valley or. alluvial flat 3 Exposure North or south jlope South slope North slope Sheltered interior valley Value j 1 2 2 Drainage area • -res <100 ——————— 101-200 201-300 301-400 >400 Value 1 2 ————— 4 6 8 Potential Sum of values 4 or less 5-6 7-8 9-10 11 or greater Long term yield . gpd <500 500-1,000 1,000-5,000 5,000-10,000 10,000 + Examples Well 3 Well 10 Well 22 Well 20 Well 16 2 1 1 1 1 2 1 2 3 4 2 1 2 2 2 1 1 2 6 6 7 4 7 12 13 1,000-5,000 500 1,000-5,000 10,000 10,000 32 tr.e development of puohc supplies for local use. The v/ater, 33 a -.vhole, is or poor quality, being slightly mineralized, but can still be considered cotaole. :: :ar. oe blencea -.vit.-. cistern v/ater, yielding 3 mixea v.-ater of more accectable pota- 3.hty. Householders v/no nave '.veils generally prefer a cual systc.T.. u s i n g the '.veil v/ater for •.vasning, lawn •.vatenr..;, : r.c sanitary purposes and run water for Tr:.ikir.; -.r.c :"?-'.ing. jrouno- A ate: P o t e n t i a l ~u" -r-5iiT-i-water potential _f jr. -.roa can in large part be determined by ine av c r- ^ "n.uai r a i n f a l l , topogmpny, and exposure to = j l a r r a . a a - tion. In general, areas receiving Ivss :.-.,in ->'J .nches of rainfall hove a lev; :rouna--.v iter poten- tial. The southern slopes of the islana, .vnere, because of solar radiation, -r'/jpotranspiration is nigh and recnarge is low, generally nave less ground-water potential and yield more nighly min- eralized water than the nortn slopes. Topograpny is important in th-T - tK^ Hotter slopes grouna- water recharge is favored. A crude scale based on rainfall, topography, exposure, and drainage-basin area was developed for estimating ground-water potential of the rocks of the island I table -1) . The different features are assigned values ranging from 0 to 8. The sum of these values is a number from wnich an estimate of the lone-term vield of a well can be obtained. A deep well will ^snerally yield more water than a shallow well in the same location. For the purpose of the scale, a well depth of about 200 feet is assumed with the water level in the well at 50 feet below land surface. Little water is yielded from depths of more than 200 feet below the water table. It is emphasized that even tnough conditions appear favorable for obtaining j ground-water supply, there is always o possibility no water will be obtained as a w»lj may not penetrate water- bearing strata. Water in Consolidated Rocks The permeable zones or me consohri-tori rocks consist of open joints and fractures. Xear t-.e land surface the joints are open—the result of v/eathermg and release of pressure. Joint open- .ngs , however, narrow rapidly with aeptn, anc generally at depths of a few hundred feet they are too narrow to transmit significant quantities of •.vater. All the bearock formations are broken oy faults-- fractures along v/nicn mover-.er.t r.as :a-:en dace, in some faults, earth movement n.as crushed :r.e rock to -jravel-size oreccia, whereas ir. ethers cr.e rock has oeen reduced to a flourlike suostar.ee called fault gouge, lirecciated fault zones not sealed by mineral deposits or fault gouge car. oe very perrreaole and often extend to depths of Hundreds of feet. The orientation of many of the valleys jr.a oays ?'/:dentl/ is controlled by a fault ana joint system along which erosion has occurred, .'alleys, tr.erefore, are often indicators of zones of an extensive jointing or fracturing system that may contain ground water. The yield to .veils drilled in the bedrock is small—generally less than 1,000 gpd. Many wells will 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 of water from storage in the immediate vicinity of the well. Once water in local storage is removed, the yield to the well is reduced to the general yield of the aquifer. For example, well 17 nearWintberg re- portedly yielded 12 gpm (17,000 gpd) fora 24- hour pumping period when first drilled. However, almost daily use over the past 5 years has shown that the long-term yield of the well is about 250 jalions per day. The consolidated rocks are permeable as a result of interconnected open fractures along joints and faults, which tend to be linear. How- ever, permeability may vary significantly along a lineation. One example of possible linear permeability is the north-south fault in eastern Charlotte Amalie. Permeability, as determined from pumping tests of wells, ranged from about 1 to 9 gpd per ft2 (gallons per day per square foot) east and west of the fault. Immediately along the fault zone m the vicinity of the race track, however, permeability ranged from about 70 to ISO gpd per ft2 . South- ward along the fault permeability was 1 gpd per ft 2. 33 The effective porosity, or storage capacity, of the consolidated rock also Is related to open Inter- connected 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 esti- mated to be 1 percent or less. Water in Unconsolidated Rock Water-bearing unconsolldated deposits are present only in Turpentine Run Valley and In coastal embayments. These deposits consist of two dif- ferent llthologic 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 interflnger. 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 few exceptions under water-table conditions. Sand and gravel beds and lenses in the alluvium are rare. Where present, however, they will yield water readily and act as a large collector system into which water from the less permeable alluvium will percolate. Occasionally the water In the sand and gravel beds is 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 high 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 easily occur. Water Table Ground water In St. Tboeut is assumed to be underwater-table condttteos—that is, the water surface is unconflned, 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 general, the water table roughly parallels the topography. The depth 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 ridge. The water table responds to changes in the quantity cf water stored in the ground-water reser- voirs. The water table nses when recharge from rainfall or stream flow exceeds the discharge; it declines when discharge to springs, streams, or the sea, evapotransptration from the water table, and withdrawal of water from wells exceed recharge. Water-table fluctuations The hydrograph of well 1 in figure 26 is typical of the water-level fluctuations 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 rise in water levels, but the steep hydraulic gradients result in rapid losses and almost as rapid declines. Figure 27 Is the hydrograph of well 24 tapping the alluvium and weathered bedrock in the lower Turpentine Run Valley, and figure 28 Is the hydro- graph of well 21 in the alluvium of the upper basin. Recharge Is received every time storm water runs off In the stream and water levels rise. Between times of storm runoff, ground-water levels are partly maintained by the infiltration of base flow from the stream when flow is present. The hydrograph of well 19 in figure 29 shows the pattern of water-level fluctuations of the rock aquifer in upper Turpentine Run basin. The pattern Is similar to that of the rock aquifer of the north coast and larger valleys on the south coast. Here, greater permeability and storage capacity and generally thicker soil and alluvium result In a slower but more prolonged response to recharge and a slower discharge. The "troughs" in the hydrograph during early 1965 were caused by pump- age (averaging 18,000 gpd) from a nearby well. Recharge The bedrock aquifer Is principally recharged by infiltration of rain on the land surface. Stream- flow and storm runoff locally recharge the alluvium, which may, in turn, contribute water to the bedrock aquifer In the major valleys and allu- viated coastal embayments. 34 Rainfall, vegetation, evaporation, surficial deposits, and exposure to solar radiation are the main factors affecting recharge to the aquifers. Leaky-saltwater and sewage mains in Charlotte Amahe and effluent from sewage plants in the Turpentine Run basin also contribute water to the aquifers as does effluent from septic tanks through- out the island. Recharge irom these sources is detrimental as it is a potential source of pollution. The bedrock aquifer is recharged infrequently and only after a heavy rain or series of lesser rams. The amount depends on the antecedent rainfall and the degree to which soil moisture has been depleted by evapotranspiration 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 — saturation 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 varies 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 is attributed to the greater solar radiation received by these slopes, which results in Increased evapo- transpiration and a greater soil-moisture deficiency. Consequently, a greater volume of water is neces- sary to overcome the soil-moisture deficiency before recharge takes place. Where the surficial deposits (saprolite or alluvium) are thick, ranging from 2 to 15 feet, as on the north slope in tn* vicinity of Dorothea, in upper Turpentine Run basin, and in the alluvial embay- ments, such as at Long 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 the bedrock aquifer—as most is discharged to springs or streams directly from the saprolite or alluvium, as has been observed in the vicinity of Dorotnea on the north slope. Runoff from major rainstorms is the principal recharge to the aquifers of the coastal embayments and is an important source of recharge to the alluvium of Turpentine Run. Base flow of Turpen- tine Run and Bonne Resolution Gut at Dorothea 3ay, when present, also contributes recharge to the unconsolidated aquifers in their respective basins. For convenience of discussion, the island has been divided into five ground-water areas as shown in figure 30. Estimates of yield in these areas are given in table 5. S.--estimated yield of ground-water areas . 5 e e f i < j . 5U I j.-ound-water irea 1 1 ! Long Bay i 1 ( Lindberg 3ay I 2 2 Upper oa sin 2 Lower oasm' 3 4 5 Total -rea, 3q mi 13.6 .3 I/ .2 I/I 3.4 2 . 3 1.1 4.6 .42/ 10.0 32 estimated yieid JPd 450,000 70,000 3/ 30,000 3/ 350,000 300,000 4/ 50,000 4/ 250,000 100.000 100.000 1,250.000 rrq/yr 164 2 5 11 128 110 18 91 36 36 4 5 5 Annual r»cnarqe. .riches 0.7 •1.9 4 . 3 2.2 2 . 8 1 .1 1 .1 5 . 3 .2 I/ Approximate area of alluvium only. U Does not include drainage basins at Areas 1 and 5 which contribute recharge to Area 4 from surface- water runoff. j/ Yield included in Area 1 total. 4/ Yield included in Area 2 total. Ground-Water Areas Area 1 encompasses about half the land area . It is underlain principally by fractured volcanic tuff and breccia of the Louisenho) Formation, on which 1 or 2 feet of soil have developed. On the south side of the island, from the vicinity of Charlotte A ma lie westward to Brewers Bay, the volcanic rock has been extensively fractured. The fractures, however, have been filled with 37 I 16*29 •' O ATLANTIC OCEAN 94 E X P L A N A T I O N FOft SYMBOLS Surfoce-woler gaging station Drilled well, number refered to in text Dug well Gallery Spring, number refered to in text Rain gage Pollution from salt-water mains !iii!!!i!i!l!!l Encroachment by sea water _ _ _ _ _ _ Boundary of area C. ;.'.'-• Alluvial deposits 2 Areas, see explanation below C A R IB B E AN SEA J milo •s*oo I •4*33 6«"SO - I Cdto A R E A S E X P L A N A T I O N Area 1 Wells in rock 50 to 300 feet in depth will yield up to 1 ,000 gpd. In some larger basins and alluviated embayments yields up to 10,000 gpd may be possible. Water contains 1,000 to 1,500 my/1 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 50 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 salt-water encroachment except in lower Turpentine Run. Area 3 Wells in rock 5u to 200 feet in depth w i l l yield up to 5,000 gpd. In some laryer drainage basins, yields up to 10,000 ypd may he possible. Water contains about 1,01)0 nuj/l dissolved solids and about 200 my/I chloride. Wells drilled near the sea and below sea level m.iy yield brackish waiter when drilled or if pumped <it excessive r.ites. Area 4 Wells in limestone Si) to ISO feet in depth w i l l yield up to 50,000 ypd. Short-term yields of selected wells may be us great as ] 511, 000 ypd. Water contains about 1 ,500 my/1 dissolved solids and 200 to 300 my/1 chloride. Wells drilled near the sea or below sea level may yield brackish water when drilled or if pumped (it excessive tales. Area j> Wells in rock 50 to 300 feet in depth w i l l yield up to 1,000 gpd. In general yields are small. Water contains 1,000 to 1,500 my/1 dissolved solids and 300 to 500 mg/1 chloride. Wells drilled on penin- sulas and in coastal areas generally will encounter brackish water. Ground water polluted by leaky salt-water mains in Charlotte Amalie area. Figure 30.--Ground-water areas of St. Thomas showing location of wells, sprm.js, stream gages, and rain gages. 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 ridge. Depth to the water table is greatest beneath ndges 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 is 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 drilled to a depth of 120 feet before water-bearing fractures were penetrated. Well 10, 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 250 to 1,000 gpd, although initial or short-term yields may be 10 times greater. Two 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 1. Long Bay.—The Long Bay area lies in a basin about 1 square mile In extant, of which about 0.3 square mile is alluvia ted coastal embay men t, and the remainder is steep-sloped volcanic ridges with little soil cover. Alluvium as thick as 60 feat overlies the bedrock. Near the coast the alluvium underlies and interflngers with a thin beach-sand deposit. A relatively impervious clay overlies the bedrock from a Una about 1,500 feet Inland sea- ward to the shoreline at Long Bay, and probably extends out under Loog Bay. Water is present in the alluvial deposit*, but the main aquifer is the underlying volcanic rock. In general, the bedrock underlying the alluvium yields more water than that underlying the ridges. The zone of greatest yield :o wells is oound by the two faults oassi.-.c :.-.r:•-„•;-. tne area. A factcr c^r.:r:a.:•:.-.; '.o tne :;rcauc'.:v:tv v" -.:v: bedrocK is :ne overly;:/} alluvium that 3c:3 j< 3 storage resjrvcir. 7"-.e = iluviu:n :?r.tj::-.s . i-;;o Tuar.tities )f v/i^r. ~?c3uso cf :ts . .w Lerred- bility it generally yields little water 'o -.veils, but it yields water sicv.'ly to tne ^r.cerlv:r.,- cod- rock aquifer. The crincipal area of roc-.-r;e t: the bedrocK aquifer trom rhe alluviLirr. : : : :::•: foot of the volcanic riaqes inlanc ;t .,-.; -:i.;e •: the impervious clay wedge capping :r.-j ^•_••::.:-•. and mostly upgradient from the area : oa/.y ,L- water mains. The long-term yield cf the alluviun'--,edrcc'< aquifer is estimated tc be from 60.00J -i '-.'' ;oo 9pd. The yield of wells ranges :r-?m ar;ut :"0 to 70, 000 gpd. The high yield of seme of :h3 wells, however, has little to do with t^e !•_.-.;- term yield of the aquifer. Sustained p^mpaca ;r. excess of the long-term yield of the aquifer wul deplete the fresh ground water in storage and rroo- ably result in salt-water encroachment. Saltwater has encroached in a narrow strip cf the alluvial aquifer bordering Long Bay because of pumping dug wells 13, 14, and 15, which supply Pearson Gardens public housing. 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 principal recharge area is 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. Salt water from the alluvium has apparently entered the bed- rock aquifer through several improperly construc- ted wells. In each the annular space between the wall of the well and the casing was left open, and salt water moved down the annular space, contam- inating the bedrock aquifer in the vicinity of the well. 40 oasin ar?- ./men is .:: :-. ;3 :riji. ige ar.c .; : - 7 ttr ~ " .-'. : t 1a£ ••=;:•/ of - " '. ': :. 7 "•"Us -n rro -" • . -.-I per:--: soii.f.-. - ..-v; . - 13 ur: r;ariv intrusions. : :-any :f the fillsu sr.c . ' -e ~een arilieu ir. r -5 o- jr:c'-. jio.-y T0 v.-p*: -jo:"> ". :he ailuvidi .'L-05.13. .'eii ," j j a r / .if •— .u-jri >.t v.-js -.rilled '.: i -:c-r:-i of 2'JO f-aet. .V-i'.-: -. ;n. j 6 nave ; .:•,-. 5 :«rr; -:--ld. •esumarad to bo : , j ; 0 opd. 3erircc!'. •••e'.!- -rohabiy -vili y;sld i.\L''. v qpd in the cer.L-.n •Tt : i-.9 er.caymon: :.or:r. cf the airport. T/.e ui_. :'_:.•. •= relativaiv :hic'- there 2nd, tnus, .f •'•ij'iiu conmoute -or. .-siae'sbla su.3nt:ties c: wite-r '_-> -hi --.JarJving oedroc< .•i.:u:for. ' j .-.'oter.f.al yield of the c«drock aquifer .3 . ..... ..,,-j .„ oe JQ ooo gpd, josumin'} data -c'.aine TT. . .• Lung Bay r:rja can ce applied. Salt-water mains in the Bourne Field housing jraa are known to leak, and it must be assumed ;.-.jt t.-.e diluvium in that vicinity is contaminated. The same care to prevent salt-water contamination jy in. -roper well construction must be taken nere is in the Long Bay area. At one tiT.e a gallery paralleling the runway jt the jirport waajffpd for water supply. This gallery, which caotocttci runoff from the runway ir.a stored water ttilM alluvium and landfill for :uture use, nad •^jW^atlmated to be 13, 000 gpd. Unfoaunateiy, tho gaitory waa overpumped 2nd salt-water encroachment followed. Salt water is sull present in the alluvium near the well and :s .p. a position to intrude the bedrock aquifer. :.Vater from the gallery occasionally is used for purposes. The use of water from .-./a•: drainage for drinking purposes, of course, ^ar.aerous oecause of the presence of toxic ;-.c"imds such as Hydrocarbons and tetraethyi •; :r^m spilled aircraft fuels. ~- 3 - 'rea 2 is the drainage oasin of Turpentine Run. :rvenience it is separated into an upper ana • •-f -asm; the upper basin above the stream- :ir. j station near Mt. Z:on, and the lower basin '. •• ''. The principal rocks are volcanic flows, :. 3T.-1 breccia. Alluvium as thick as 40 feet 5 -. :r,e mam stream channel of the lower oasin. ;r'.hv/est-oriented fractured and jointed zone -y-.r'jtnermally altered rock bisects the upper ?;.ll-?d wells range from -40 to 250 feet in •rcth. The shallower wells tap the alluvium and .. Oj'.her*;.: bedrock of lower Turpentine Run. The iepth cf the rock wells is not necessarily a cri- :™ri-:r. ot greater yield, but is usually an indica- •:^n ot where a zone of water-bearing fractures .•ri3 oenetrated. Short-term yields from indi- .-.Jujl rock wells in the upper basin are as great •;5 1 5 0 , J O O g p d . Sustained yields, however, ':ri',*e from about 3,000 to 30,000 gpd. Indi- v. ,L:J! veils in lower Turpentine Run yield as ~.-"zn is 30,000 gpd, but sustained ground-water •.•.-L:hdrawfjis of more than 10,000 gpd will probably ro-ult in sea-water encroachment. .1 r?ur.d-water levels.—Contours of the ground- v/acer surface during August 1965 and January 1066, are shown in figures 31 and 32. The arrows on these maps indicate the general direction of jround-water movement. In the upper basin, ••/hen water levels are high, ground-water flow is split—part moving along the course of Turpentine Run .ind part moving through the fractured and altered zone at Mt. Zion and emerging as a series of springs discharging to Turpentine Run in the lower basin. When ground-water levels are low in tne uoper basin, nearly all ground water is .rcoably discharged through the fractured zone at Mt. Zion, and a temporary ground-water divide is established at the position shown in figure 31. Ground-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 drilled in bedrock in the upper basin and in the alluvium and weathered rock of 41 TUT 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 each district within the radius of interest. In cases where only a portion of a district is within the radius, population was prorated by area. , " FINAL REPORT-FINAL i WATER MANAGEMENT PLAN J FOR THE ~ PUBLIC WATER SYSTEM I KifeBunx Prepared for THE DEPARTMENT OF - - — - CONSERVATION AND CULTURAL AFFAIRS GOVERNMENT OF THE VIRGIN ISLANDS CH2M Prepared by CH2M HILL SOUTHEAST, INC ••LJII I •• n ILL No> GN14325JKO Juiy,1983><r J J J J J J J oz o at i UJ V — I— .0 fQ flC I- O - a J3 LJ- 22g* : : sss : : 8| S " ^S 2""°' • ~i • • • > 19*9 •'•!•*< > 01 • ~, sK 2==' • c' "•-lal'saa- •• 3 ; u" ' « -i yfs ^5r is-j ftif 3 si U 1 M^ i I M I 3** a:8'"' K * sa: : isas: •• • • I I to t » i l M MA I t «ri* < •* 1^4^ I f+ttf A ^ • t -'I1 -K • • • t85S' • a'sj 'sss-sg **s' «- M - «i s 5-5 2552*1! ^5S253.3 — " U" ~H*~~ fi 5a 2 SI! gjl !! e ^ ! I I a •——- INTERNAL DEMAND ——••» *-———--.___._; .NIERNAL "ATER SUPPLY -- — ——————— • *——— POTABLE MATER -—-• *— NON-POTABLE MATER — * POTABLE NON-POT TOTAL CISTERN OTHER TOTAL SALT OTHER TOIAL KCAL/O KCAL/O KCAL/O KCAL/O KCAL/O KCAL/O KCAL/O KGAL/D KGAL/O EXTERNAL OE*«»ND —-« POTABLE KCAL/O NON-POT KCAL/O TOTAL KCAL/O DISTRICT DISTRICT DISTRICT DISTRICT OISIRICI DISTRICT OISIRICI DISTRICT OISIRICI DISTRICT DISTRICT . DISTRICT DISTRICT DISTRICT DISTRICT OISIRICI DISTRICT OISIRICI DISTRICT DISTRICT 01 02 03 04 Oft 0* 07 O* 09 10 II 12 13 14 19 16 17 1* 19 20 TOTAL ISLAND 47.9 271.7 670. • I3S.S 29.1 3?,» "*•• 2**if 24*6. • 131. 1 2J3.* 607.1 134.7 >s. a II*. 9 96.7 43. 3 2.6 18.9 31*. 9 99BB.3 j£^ •>*> r* > •?\^ o. J6. 0. 0* • • •ixjr ..,-«* &\-*t * •»• ' !••••. 0. 0. I?. *. 0. 90. 0. 7. O.f 0»( 37. i 14158. I ^ ——— ^- 4 » 47. < 307. 670. 139. 29. 37. 293. 2*6. 214*6. 131. 233. 634. 134. 29. 16*. 96. 91. > 2. > 1*. ( 399. ' 29146.! ^ "1 J* *J » 7. r 49. 110. 9. 6. 6. 64. 39. 110. 29. 37. 96. Jl ..... . 90. » 6.18.1 ^-"Ifflfc 6 ^~^ -^*/» Tlr 6 fr ^ 1 1 1 0.0 . 0.0 9.0 100. 0. 0. 0. 91. 4123. 0.0 O.O 0.0 • 0.0 0.0 90.0 9.0 1 10. 0 0.0 •O.O 0.0 4444.9 -,:——. ^/\ s#\ /• I n \. /•x r 10 ^^ • 7.' 49.1 119. IO9. 6. 6. 64. 90. 4234. 29. 47. 96. Jl. 6. 99. II . 119. 0. 3. 90. 5082. < aoS^X; s* k 0.0 r o.o 0.0 0.0 o.o 0.0 o.o o.o 2IOOO.O 0.0 o.o 0.0 .0.0 0.0 0.0 0.0 o.o 0.0 0.0 o.o > 2IOOO.O ,, /~r _.j~C /\j*\_v\»iv-L *0 14 I* 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 o.o 0.0 o.o o.o 90.0 90.0 10.0 0.0 0.0 0.0 IIO.O -^/-^ y. te M C-X* SoX r%j 0.0 0.0 o.o 0.0 0.0 0.0 o.o o.o 21000.0 o.o 0.0 o.o o.o 0.0 90.0 90.0 10.0 0.0 0.0 o.o 21 1 10.0 •tetvjH 19 .^vr s^£% 'tl ^~ 40.9 226.0 999.0 26. 1 22.2 31.4 229.6 236.9 419.3 102.0 195. 1 99O.9 IO3.2 19.2 98.6 90.5 24.2 2.2 15.9 207.7 J2I 1 . 7 «V - -~J~—T^ ^-»-» " 1&-^~/ j* ™ »^ 0.0 36.2 O.O O.O O.O O.O O.O O.O O.O 0.0 o.o 27.6 O.C O.O O.O o.o 0.0 0.0 o.o 37.2 101 .C > 40.9 262.2 999.0 26.1 22.2 31.4 229.6 236.9 419.3 IO2.0 199.1 578.5 IO3.2 ' 19.2 SB. 6 90.9 24.2 2.2 19.9 3O4.9 J3I2 . 7 13 Stfvic* DilliKti M* NumlMitd FIGURE 3-4. Projected demand of the service districts on St. Croix for the year 1980. ISLAND OF/ OUTPUT DAY THOMAS 'UK YEAR I960 0.—. INTERNAL DEMAND POTABLE KGAL/0 NON-POT KGAL/D .-• •--—------—— INTERNAL HATER SUPPLY --—----——-* «—— POTABLE WATER --4-* O-- NON-POTABLE •AT€R--« TOTAL CISTERN OTHER I DIAL SALT OTHER TOTAL KGAL/D KGAL/O KGAL/D KGAL/O KGAL/O KGAL/O KGAL/O EllItHNAL OtMANO ---O POIABLE KGAL/D NUN-PUT KGAL/D 101 AL KGAL/D DISTRICT DISIRICI DISTRICT DISTRICT DISTRICT DISTRICT DISTRICT DISTRICT DISIRICI DISTRICT OISIRICI DISTRICT DISTRICT DISTRICT DISTRICT DISTRICT DISTRICT OISIRICI OISIRICI 01 02 03 04 05 06 07 oa 09 10II 12 I 3 14 15 16 I' ia 6. a 19. 1 27.» as. a 13?. 0 *•«.» 104, | 82. » 540. a 0.0 0.0 o.o 0.0 6 14 27 as 198 616 210 a2 99.3 174. » 2«i.? 40. r 21ft. • 712. 0 567.2 ! 0.6 29.7 ••a M. i a. a 10. » ot . I O.O 26. J S7.6 20.7 0.0 O.O loa. so. las. 142. 00. .• . I . 76V. 507. O. 25. I .4 4.1 9.0 22. I 34.7 83.a 20.3 I I .2 102.a 13.1 J.4 28.6 4O.O 9.7 J3.8 112.7 43.5 O.I J.6 0.0 0.0 O.O O.O 0.0 30.0 65.0 8.0 16.0 0.0 0.0 10.0 I 70.0 0.0 0.0 a.o 25.0 O.O 0.0 '•j i.a 4.1 ••4 22.1 34. jj 113. a, as. 19. 118. 13.li J.4 38.6* 210.0 9.7 Jj.e 120.7 I 18. 5 O.I 3.6 0.0 O.O O.O 0.0 0.0 0.0 O.O 0.0 0.0 O.O 0.0 0.0 .0.0 O.O 0.0 O.O 0.0 O.O O.O 0.0 0.0 O.O 0.0 4.0 O.O 56.0 0.0 0.0 15.0 0.0 19.O 62. O O.O •>.o O.O O.O 0.0 O.O 0.0 0.0 0.0 0.0 4.0 O.O 56. 0 O.O 0.0 IS.O 0.0 15.0 (,?.0 0.0 0.0 6.0 0.0 0.0 J. J 5.4 15.6 22.9 63. 7 102.3 475. 7 7J.4 63.3 442.2 83.9 46.9 I 39.7 195.» 31 .0 |8I .6 591 .3 448.7 O.b 22. I O.O O.O 0.0 O.O O.O 31 .8 50.0 O.O O.O O.b 0.0 O.O 4.2 O.O 26. J 57.0 20. 7 O.O O.O 5.4 15.6 22. V 63. 7 102.3 507.5 I 2 J.4 63.3 U3.9 46.9 I 39.7 2OO.O 31 .0 2O7.9 64B. 9 4b9.4 O.5 22. I TOTAL ISLAND 3754.8 3^7. c 4081.8 623.9 332.0 955.9 0.0 152.0 152.0 2946.0 ifliictt «• I VO.6 Jl C/7 FIGURE 3-6. Projected demand of the service districts on St. Thomas for the year 1980. J REFERENCE NO. 18 NUS CORPORATION TELE CON NOTE CONTROL NO: DATE: TIME: DISTRIBUTION: BETWEEN: V tA/Y^^-t)-^ OF: U S G-' PHONE: AND: U (NUS) DISCUSSION: j — A £ JCT Vv- .X "f i 4= X-v i-Atv^ •*/»•-»- i /.">/ ? ^L^. cit^ c**»*^ jL-v 0 iA/i>t REFERENCE NO. 19 NUS CORPORATION TELECON NOTE CONTROL NO: DATE: TIME: DISTRIBUTION. BETWEEN: <3-f<Her Of: car PHONE: ( SC<?) -771- AND: (NUSI DISCUSSION: (Y\ r Q - 6, V r \'i LA-^C. I V-k/ <s\Q 0 dLoirC +or Vv^ Lutll >\A_-t-i^/ ) ""I"* f. -^^ f\ _f*£ i^V^T I ^ft.O if\. O E"^^_ \\ I T^ I i p/'-Q '^nixo <^, ) ci^ov- /^ rrftc \<a ~T~ P^ kliV cOorkC u^fg/ firco o ) ui no. Cv\ ^" - v c- r\ OflT—iftiA. «TiA^ ACTION ITUM: af\o,.4 ? TVvcc-t fV-r*" ji_i i f , \ ~ S>Wc/^ — vhjt L v.g<^Vv ixicxti f ^£~«n (CLL, "f- f^JTV f g.S :V\'u'.4u. vEjc cvv< \«» I O ( Of tf\ NUB 0«T MMHO OM1 REFERENCE NO. 20 NUS CORPORATION TELECQN NOTE CONTROL NO: DATE: TIME. DISTMISUTION: a BETWEEN: OF: PHONE: AND: (NUSI DISCUSSION: —L c- ryv-o—* CL fv\-<_ "tvcf-» <i rn~ro 2- rv^ CT ~TV\A Q_r\ o »^a. OL CftXfl. ccr - W. .o\ oo.^yv — ^^Lio -^ Tn~ro / r ACTION TOMS: vS » i Cofj \ r.t- 7"<-w^vr>r» "T~«O >— d »^v O"4 - Tt\^.<v» Q. & -w. TUT 002 REFERENCE NO. 21 v~v— ^- "~M " - - V1 C - •> ' RECORD OF COMMUNICATION CALL QOISC (*• TO: FROM: OATf TIME 'a^tt £// SUMMARY Or COMMUNICATION F yp^r-L CEWED L3 IRtC'D ^ Oo.vrortMnUfl REGION II SE1 T TO CONCLUSIONS. ACTION TAKCN ON MIQUMCO x^x j: cs. 7& jTi"'*. />'<*— -&* oe-aA**-^*. riON corns TO: z^-rtxv^ If A P«» 1 ••SLACKS K»A HO PO«M U«*4 NMICM MAT •• UKO UNTIL •(«»»• - - "--• TUT Oi REFERENCE NO. 22 . - ^PRELIMINARY INVESTIGATION OF TEXACO VIOLATIONS DATE: 05 AUG. "87 TO: TEXACO's FILE FROM: LEONARD REED SUBJECT: TEXACO's VIOLATIONS [waste oil, etc.) On 05 August 1987 at about 07:45 hrs. an inspection was conducted of the Texaco Tutu facility located at ?? Anna's Retreat. Mr. Vernon Morgan was contacted for information relative to the inspection. The inspection revealed that there were several violations of V.I. Laws/Regulations. The findings are as follows: 1. A large underground container with concrete top that is ' part of the entire surface area was on site. This container had a concrete partition that may have holes towards the bottom since the material contained therein was of the exact height in both compartments. The container was protected with a circular cast iron cover. The material contained appeared to be waste oil. It was not possible to determine the construction of the subsurface tank to include depth, width, length, type of bottom [concrete, dirt, etc.]. Waste oil is classified as a hazardous waste in 19 R&R ch. 56 sec. 1560-500. Said waste oil was generated in violation of 19 R&R sec. 1560-501. Said waste oil was also stored in the above tank in violation of sec. 1560-501. 2. There were there (3) service areas, each equipped with hydraulic hoist and waste oil collection trap that had pipes installed to transfer the waste to one (1) or more of the waste oil storage tanks. Each of the three (3) traps contained waste petroleum products in violation of 1560-501. 3. There was a filled septic tank on the property that will be in violation of 19 R&R sec. 1404-73 if further investigations revealed that there is public sewer available. 4. The soil of the unpaved area along the northern boundary was saturated with waste petroleum products. There were several containers of petroleum products stored in said area along with automotive parts all in violation of 1560-501. The auto tires contained in the above accumulation are capable of breeding mosquitoes in violation of 19 VIC section 1563 (5). TEXACO's VIOLATIONS 05 AUG. "87 continued ___ JL^-There was a large distinctly circular area with a square steel plate cover that was also filled with waste oil. It was not possible to determine the length, depth, width, type of bottom [concrete, soil, etc.]. Said waste oil was generated and stored in violation of 1560-501. 6. The storm drain contained waste oil or similar petroleum products in violation of 19 VIC section 1563 (13) and 19 R&R section 1560-2 (j). 7. There were two additional man holes covered with square steel covers. It was not possible to determine the contents of said man holes due to the rear wheels of the most north of three (3) (semi) trailers being on the said covers. These are suspect of containing petroleum products since the cistern and the septic tank were identified. FOLLOW UP IS NEEDED! REFERENCE NO. 23 J. F. MARTINET & CIA.. INC. MECHANICAL CONTRACTORS CAtt. If. KM. 0.3, SO. MONAQUOS GUAYNAiO. WfKTO MCO TftS. 711.(0*7 • 7tt.U34 f. O. MX -AX CAPAUA MtlCHTS STATION SAM JUAN. KJEftTO HCO 00*77 JULY 18, 1987 Re: Test Location: Petro Tite Tank Test JULY 11, 1987 TAJTU TEXACO SERVICE STA. ESTATE ANNA'S RETREAT, NO. 1 ST. THOMAS, U.S.V.I. Petro Tite test performed on tank system #3, in order to determine tank'a mechanical integrity. Tank system #3 subject to Petro Tite test under the conditions' detailed in tank chart ( A ) * Results of july 11, 1987 demonstrated that tank system #3 tdoes. does not) meet the criteria ("TIGHT" + .050 gph) establi5fie""y \he national Fire Protection Association Pamphlet 329. The criteria established of + .050 gallon/hour is a mathematical calculation based on actual liquid volume change and temperature change, and is not intended as a permission of a leak. "LEAKAGE INDICATED —— GALLON/HOUR*4 F MARTIBEZ & CIA/), INC. M>l\H, Mafeio Urdaneta Tank Testing Technician S.N. 1318 MU/cjt Enclosure TAtBL Comments: SEE TANK CHART A. STRUCTURAL RREAKAfn? nr nNnrRmntiNn TPAKTNfl TANK 200'19yd oiaand aa 000x21 woaj is, is inr «, TA» nn v ' 'A ^IA K jj F 2 •c J. F. MART1NEZ & C1A., INC. MECHANICAL CONTRACTORS CAM. If, KM. 0.3, tO. MONAOUOS GUAYNA4O, mOTO IICO T&S. ?|t.|0f7 • 711. ISM JULY 18, 1987 P. O. KM -AX CAPAIftA HEIGHTS STATION JAN JUAN, fUMTO tICO OOW3 Re: Petro Tite Tank Test JULY 11, 1987 Test Location: TUTU TEXACO SERVICE STA. ESTATE ANNA'S RETREAT, NO. 1 ST. THOMAS, U.S.V.I. Petro Tit* teat performed on tank system #1 , in order to determine tank's mechanical integrity. Tank system # i subject to Petro Tite test under the conditions' detailed in tank chart ( R)« Results of July 11, 1987 demonstrated that tank system # l (does, jbUfcAflSJ meet the criteria ("TIGHT" ± .050 gph) established by the National Fire Protection Association Pamphlet 329. The criteria established of ± .050 gallon/hour is a mathematical calculation based on actual liquid volume change and temperature change, and is not intended as a permission of a leak. "LEAKAGE INDICATED -f- GALLON/&OUR" J. F MARTINE2 & CIA., INC. KU/cjt Enclosure Masio tJrdaneta Tank Testing Technician S.N. 1318 Comments s SEE TANK CHART B TUT OO2 oiaand 3a 000x21 woaj 12:^1 LQ, :e inr AKMC»-fM___ V1CXMMIO*! MA. W?^-IWI Q CO Cr u 00 ^J fe • • Nro c3 XIrc c fT 1 C fT c X rc I Cn C Co REFERENCE NO. 24 Suite 201,1090 King Georges Post Raid, Edison, NJ 08837 • (201) 225-6116 TECHNICAL ASSISTANCE TEAM FOR EMERGENCY RESPONSE REMOVAL AND PREVENTION EPA CONTRACT 68-01-7367 TAT-02-F-04398 TO: MEMORANDDM Carloa O'Neill U.S EPA Caribbean Field Office FROM: Arnaldo Martinet. TAT II P .Douglas Henne4t>TAT II QC r^ v SUBJECT: St. Thomaa, Tutu RSL + 40 Sampling Reaults DATE: January 27, 1988 The following letter report ia provided in accordance with TDD #02-8709-29. The completed analysis report of the HSL+40 aampling of the Tutu well aite waa received on January 18, 1988. A copy of the laboratory report waa delivered to the EPA PM on January 20, 1988. Table tl shows the concentration of contaminants found in each well. The major contamlnanta found are 1,2- tranadichloroethylene (DCE), trichloroethylene (TCE).,. tetrachloroethylene (PCE) and tertbutyl methyl etherf<TBME). TBME waa not detected during previoua aamplinga. -Otf compounda found in low or trace concentration are: 1,1,1- trichloroethane; bencoic acid; 4-methoxy-l,1-dimethyl ethyl phenol; 2-butoxyethyl phoaphate; 1,2-dlchlorobentene; 2-ethyl- 1-hexanol; N-2-dimethyl -1- propaneamlne; chloroform; toluene; pentachlorphenol, methylene chloride and 2-methyl naphtalene. A high concentration (120,000 ug/1) of methylene chloride waa found in the Harvey's Veil.. Toluene waa detected in low or trace concentrations in two wells (Byran'a and Leonard'a). Unlike previoua aamplinga, benaene waa not detected in any of the aampled wells. TUT Roy F. Weston, Inc. SPILL PREVENTION * EMERGENCY RESPONSE DIVISION In Association with ICF Technology, Inc., C.C Johnson ft Malhotra, P.Q, Resource AooUcations. lac.. The following veils show no detectable concentration of any of the organic compounds tested: Rodriguez Auto, Devcon II, Devcon 13, Dench, and Rarthman Estate. Table 92 shows the compounds and aietala that are regulated under CERCLA, their reportable quantities (RQ) and their Drinking Water Standards Maximum Contaminant Level (MCL), if any. Of the metala tested, arsenic, selenium and zinc were found in greater than trace concentrations* Arsenic was found only in the Harthman Crusher Well. Zinc concentrations ranged from nondetectable in Devcon II to 460 ug/1 in Smith Veil. Other mVtals found in detectable but not quantifiable concentrations are chromium, copper, thallium and antimony. The concentration of metals found in each well is listed in Table II. Cyanide was found in five wells. The concentrations ranged from detectable but not quantifiable (trace), to 58 ug/1 in Eglin II well-. The concentration of cyanide found in each well is listed in Table ll. The RSL+40 sampling results confirm that the major pollutants in the Tutu well site are DCE, TCE and PCE. Seven wells show concentrations greater or equal to 100 ppb of one or more of these compounds. A new major contaminant was found in this sampling. Six wells show a concentration greater or equal to 100 ppb of tertbutyl methyl ether. Benzene was not detected in any of the samples taken for this analysis. Previous analysis with the photovac portable chromatograph and GCMS confirmation aamples had shown concentrations greater than 1000 ppb in the Tillet Well. This was also found in the photovac samples for the month of November. Samples for photovac analyis taken concurrently with the RSL samples show a concentration of 46 ppb of benzene in the Tillet Well. The cause of this discrepancy is unknown at present, TAT will review previous data to Identify potential causes for this occrrence as well as discuss the analysis with the presently contracted laboratory. -2- OCT.1987 TABLE 1 CONTAMINANT CONCENTRATIONS (ug/1) POUND IN TDTU WELL SITE October 1987 Bryan'i Wall Toluene Trace Zinc Trace Tlllet'a Well 1,2-tranadlchloroethylene 600 Trichloroethylene 25 TetracRloroethylene 140 Tertbutylmethyl ether 470 1,2-dichlorobenzene Trace Trichlorobenzene Trace 2-aethyl naphtalene Trace Chromium Trace Copper Trace Four Winda Plata II 1,2-tranadichloroethylene 280 Trichloroethylene 18 Tetrachloroethylene . 140 Tertbutylaethyl ether 470 Chroniua Trace Copper Trace Zinc 51 Elgin »3 1,2-tranadichloroethylene 78 Trichloroethylene 8.4 Tetrachloroethylene 40 Tertbutylvethyl ether 270 eatlaated ChroaiuB Trace Copper Trace Thalllua Trace : - .— Zinc 98 Eglin 12 1,2-tranadichloroethylene 57 Trichloroethylene 7.5 Tetrachloroethylene 21 Tertbutylaethyl ether 390 eatiaated Copper Trace Zinc 200 rir TABLE 1 CONTAHINANT CONCENTRATIONS (ug/1) POUND IN TUTU WELL SITE (Continued) Eglin II 1,2-tranadichloroethylene 56 Trichloroethylene 10 Tetrachloroethylene 100 Tertbutylaethyl ether 270 estimated Copper Trace Zinc 82 Cyanide" 58 Francoia Well 1,2-tranadichloroethylene 100 Trichloroethylene 15 Tetrachloroethylene 130 Tertbutylaethyl ether 180 estimated Chroalua Trace Zinc Trace Cyanide Trace VIHA fl 1,2-tranedichloroethylene 4.9 1,1,1-trichloroethane Trace Trichloroethylene Trace Tetrachloroethyelne Trace Benzole Acid Trace Copper Trace Zinc Trace Cyanide 23 VIHA 13 "r Methylene chloride 6.9 Trichloroethylene Trace ~.~/> Benzole acid Trace 4-«ethoxy-l,l-di«ethyl ethyl phenol 2.1 estimated 2-butoxy ethyl phoaphate 3.1 estimated . , Copper . Trace — ~ Seleniua Trace „ * ... ; Zinc Trace .. : , Cyanide Trace r i c b I c t - « • • .-. ': i t r . ... h r o i»- • . • - . TUT -2- TABLE 1 CONTAMINANT CONCENTRATIONS (ug/1) POUND IN TUTU HELL SITE (Continued) Dealtri'a Wall Tetrachloroethylene Trace Copper 20 estimated Selenium Trace Zinc 40 estimated Harthm^n Estate Well Selenium Trace Zl'nc Trace Rodriguez Auto Well Copper Trace Zinc Trace Ramaey Motors Well 1,2-transdichloroethylene 6.3 Trichloroethylene Trace Tetrachloroethylene 22 Antimony Trace Zinc Trace Cyanide Trace Steele'a Well 1,2-transdichloroethylene 47 Trichloroethylene IS Tetrachloroethylene 320 Tertbutylmethyl ether 37 1,2-dichlorobenzene Trace Chromium Trace .. >-,r> Copper Trace Antimony Trace Zinc Trace Harvey'a Well Methylene chlorde 120,000 1,2-tranadichloroethylene 49 Trichloroethylene 23 Tetrachloroethylene 2,000 Chromium Trace Copper Trace Zinc 340 -3- TABLE 1 CONTAMINANT CONCENTRATIONS (ug/1) POUND IN TUTU WELL SITE (Continued) Mathias Trichloroethylene Trace Tetrachloroethylene 3.6 2-ethyl-l-hcxanol 4.7 estimated N,2-dimethyl-l-propaneamine 32 estimated Copper Trace Selenium 5.6 Zinc •• Trace Saith'a Well 1,2-tranadichloroethylene 100 Chloroform Trace Trichloroethylene 21 Tetrachloroethylene 150 Tertbutylmethyl ether 34 activated Copper 7 Selenium 3 Zinc 460 Devcon II Well None detected Devcon 13 Well Chromium Trace Selenium 7.1 Zinc Trace Alpha Leonard Well Tetrachloroethylene Trace Toluene 22 , -, Selenium 8*5 DeDe Well Pentachlorophenol Trace Copper Trace Zinc Trace -4- TUT 002 0568 TABLE 1 CONTAMINANT CONCENTRATIONS (ug/1) FOUND IN TUTU WELL SITE (Continued) Harthaan Crusher Well 1,2-transdichloroethylene Trace Trichloroethylene Trace Tetrachloroethylene 6.2 Arsenic IS Zinc Trace Dench Well Copper _ Trace Antimony Trace Thai 11un 12 Zinc 68 Harthaan Bakery Well 1,2-transdichloroethylene Trace Trichloroethylene Trace Benzole acid Trace Antlaony Trace Zinc Trace NOTE: These result* have been corrected for contaminants found in the field blanks and laboratory blanks. -3- 002 O569 TABLE 2 REGULATED COMPOUNDS COMPOUND NAME 1,2-tranadichloroethylene Trichloroethylene Tetrachloroethylene Tertbutylmethyl ether 1 ,1,1-trichloroe thane Benzole acid Methyl^ne chloride 4-«etoxy-l , l-dl«ethyl ethyl phenol * 2-butoxy ethyl phosphate 1, 2-dichlorobenzene 2,ethyl-l- hexanol N,2~dlaethyl-l-propaneaa)lne Chloroform ~ Toluene Pentachlorophenol 2~methyl naphtalene Chromium Copper Zinc Cyanide Thallium Selenium Antimony Araenic CERCLA REG. X X X X X X X X X X X X X X X X X X RQ NCL RMCL (Pda) (ai/1 (uc/1 1.000 1,000 1 1,000 200 5,000 1.000 100 5,000 100 (total trlhalomethane) 1,000 10 1 (duata) 50 1 (duata) 1,000 1 (duata) 1 (duata) 1 (duata) 1 (duata) 10 1 (duata) 1 (duata) 50 S o o « s a T ?l Ifl n ] <> C r , 1 r. a c ; (X' SUMMARY OF LABORATORY RESULTS FOR OIL AND WATER SAMPLES COLLECTED FROM TANKS, STORM DRAINS AND SUMPS AT GASOLINE STATIONS AND AUTO BODY SHOPS IN TUTU, ST. THOMAS, U.S. VIRGIN ISLANDS ON AUGUST 17, 1987 Personnel from the Region II Technical Assistance Team (TAT) and the St. Thomas Department of Planning and Natural Resources (DPKR) collected eleven oil and wa~ter samples on August 17, 1987, from various storage tanks, storm drains and sumps at gasoline stations and auto body shops in Tutu, St. Thomas, as directed by TDD Numbers 02-8708-16 and 02-8708-32. Table I provides descriptions of all samples. The Tutu oil samples were taken from waste oil storage tanks, sumps and storm drains. Sample numbers one through eleven were analyzed for polychlorinated biphenyls (PCBs) and numbers twelve through twenty-two were analyzed for volatile organic compounds (VOCs). Split samples were provided for Tutu Texaco and Tutu Esso. VOC analysis was performed in an attempt to match the VOCs found in the-contaminated Tutu Wells with those found in these samples. Note that sample numbers one through eleven correspond to sample numbers twelve through twenty-two. The saoples were shipped on August 26, 1987 to S-Cubed Laboratories in San Diego, California. The samples were detained in customs and not received by the laboratory until September IS, 1987. The sample analysis was conducted through the Contract Laboratory Program (CLP). The CLP designated holding times for VOCs were exceeded, and the samples were warm upon arrival at the laboratory-.-- The PCB samples, however, do not require preservation and did not exceed their designated holding times. The PCB data meets the EPA quality assurance/quality control (QA/QC) requirements and is acceptable. The results indicate that all samples analyzed for PCBs we're below the method detection limits of 80 and 160 ug/kg. Table II illustrates the volatile organic compounds .(VOCs) identified in the samples. Some samples show very high levels of VOCs typical for samples collected from gasoline stations and auto body shops. In addition to those compounds found in Table II, several unknowns were detected as tentatively identified compounds. Attachments DRAFT TA3L2 I Saaole Muaber Descriotion 3239B-1.................Bay 11 sump, Tutu Texaco 3239B-2................. Bay 12 suop, Tutu Texaco 3239B-3.................Bay #3 suap, Tutu Ttxaco 3239B-4.................Oil and water separator, Tutu Texaco 3239B-5.................Waste oil tank, Tutu Texaco 3239B-6.................Storm drain, Tutu Texaco .3239B-7.................Cutter, Consolidated Auto Parts '3239B-8................. Storm drain, Consolidated Auto Parts 32398-9.................Waste oil storage tank, Ramsey Motor 32393-10................Virgin Islands Housing Authority (VIHA) — .................waste oil Underground Storage Tank (UST) 3239B-11................Oil and water separator, Tutu Esso "3T39B-T7. ...............Bay II sump, Tutu Texaco 32393-13................ Bay *2 sump, Tutu Texaco 32393-14. ............... Bay 13 sump, Tutu Texaco 32393-15................Oil and water separator, Tutu Texaco 32393-16. ...............Waste oil tank. Tutu Texaco -3239 B-17.... ._._^*-————. . ^Starm drain, Tutu Texaco 32393-18. ...............Gutter, Consolidated Auto Parts 3239B-19................ Storm drain Consolidated Auto Parts 3239B-20. ...............Waste oil storage tank, Ramsey Motor 3239B-21. ...............VIHA waste oil UST 3239B-22 ................Oi1 and water separator, Tutu Esso DRAFT °™ IBLE II JrtF )UTIU tCANIC COMPOVND •ton* BtltMOM >ns«iM .lu«n« hvlbcnMiM t.l XTlM.. lor of or* 1,1 TrlcMvrwttun* tr«ehloro«tlttM EttlMted Valut 3239B-12 140P 3000 - • f : i X » / * V 3239B-13 1300 3100 270 2300 1300 9100 , > SAMPLE NO! 32MB- 14 2200 4100 870 960 7000 260 ft'/*' tBEIt^ 3239B-13 5300 2800 43000 14000 110000 2400 V k~~ *** 3239B-16 1900 6300 1000 9300 f 0 3239B-17 2200 4000 1100 660 4400 3239B-18 2100 4200 780 390 2600 1 3239B-19 2600 100J 3239-20 130000 210000 1400000 290000 1700000 ^ 3239B-21 97000 98000 300000 2900000 3239B-22 59000 970000 200000 1200000 5POOO V iioooo \r i i - . ' t i • • : UM *" - I * - - I r (X n Oisi i'.-j :::TT 33- CHAIN OF CUSTODY RECORD MSTICr-CN lOtWCY . MCICN II Snviroasent*! Services Division IOIION, NIW JIIJIT euir UT OO2 OS 74 PC" EV:..EPC< -E- S: JO (X; CHAIN OF CUSTODY RECORD IMVIIOMMINTAl MOTKT-OK AOINCT - IIOIOM » Environsentil Services Divtilon IBUOM, MIW JIIKT «||ir P.3 ' jr N.afctr •1 -r*r-r , odPow.su A Cist. A f« -44—————U. <<!•*•> y (*•!•• t»r Cki«f« tl Cifvtfv Tl.. e.u Ip o-V| •'.S. ENVIRONMENTAL PROTECTION AGENCY _^LP Sample Management Office P.O. Box 818 - Alexandria, Virginia 22313 Phone: 703/557-2090 - FTS/557-2<»90 I-' (5 5AS Number SPECIAL ANALYTICAL SERVICE PACKING LIST Sampling Office: Jf-fc* Sampling Contact: -p'i (namea" Sampling Date(s): Date Shipped: Site Name/Code: Ship To: 33 ?S A/77.^J?. Attn* For Lab Use Only Date Samples Rec'd: Received By: Vsis/ttt. Li *\/iPLi* i*a, 3. «. 6. 7. 8.- 9. 10. 11. 12. 13. 13. 16. 17. 18. 20. Sample Numbers i*S ") Sample Description i.e.. Analysis, Matrix, Concentration i u*r*«; a )AI ^4A ^ft; M ) Sample Condition on Receipt at Lab White - SMO Copy, Yellow - Region Copy, Pink - Lab Copy for return to SMO, C Fnr I .U. « •-- — - TUT 002. OS 76 . ENVIRONMENTAL PROTECTION AGENCY Sample Management Office P.O. Box 818 • Alexandria, Virginia 22313 Phone: 703/557-2090 - FTS/557-2<»90 iJ fe'- v 1 ?y SPECIAL ANALYTICAL SERVICE PACKING LIST SAS Number Sampling Office: (i^f.tSt^ Sampling Contact: lLt,< D name) (phone Sampling Date(s): Date Shipped: Site Name/Code: ITU L Ship To: Attn: For Lab Use Only Date Samples Rec'd: Received By: (j/CA 5Afl(P<J& ) sample Description i.e., Analysis, Matrix, Concentration V6A: kU/feju^ji. { ul* ^^i^-^^^^^^B^ t -7" Sample Numbers 3. 5. 6. 7. 8. 9. 10. 11. 12. 13. 15. 16. 17. 18. 20. v.it / ^ fiA tilL /LiA Sample Condition on Receipt at Lab White - SMO Copy, Yellow - Region Copy, Pink - Lab Copy for return to S.