Final Draft Preliminary Assessment, Gassett Motors, St. Thomas, U.S. Virgin Islands
·- ·- FINAL DRAFT PRELIMINARY ASSESSMENT GASSETT MOTORS ST. THOMAS, U.S. VIRGIN ISLANDS PREPARED UNDER 02-8902-41-PA REV.NO.0 TECHNICAL DIRECTIVE DOCUMENT NO. 02-8902-41 CONTRACT NO. 68-01-7346 SUBMITTED BY: DIANE TRUBE ~ PROJECT MANAGER FOR THE ENVIRONMENTAL SERVICES DIVISION U.S. ENVIRONMENTAL PROTECTION AGENCY MARCH 24, 1989 NUS CORPORATION SUPERFUND DIVISION REVIEWED/APPROVED BY: ~JU~ RONALD M. JAMAN l FIT OFFICE MANAGER TUT 001 2054 *64410* 64410 - ~- () \Cj C, ·O _________ l:) ,-, I I ·-:::7 , ...... , C 0 ~-•· v--- ::r- ,.3_ )c ,i ' \ 00 l ul -ri;o t -Z'i • \ r'J o,.' '- ({_ j •\ S 01ru (_0 <' ~\A -b-n \C. exca.1...;o..::L.0-- ~\JC "-~ '$'1 S*·YY' G--+ 1-Jorrl.. e.,..cO (bock cf s-.~) \¥\.~ .1._ ~ 'D '-1 ~ ~ e.icce..uc:_-C.c.,:_ C0 .-'\ -:--<oL¼ r-s . - ~-., d ,r, b \)\~( 'S~cY; .... ~ _, c.Ji:a.- ,c+ oT \---½(5-m C!1.,C Ot\..S " 1 ~J \~ &&cs"-+ ~\.v \'4:)w . --- Lta.~s oro0tz.-h __ . ~ r ,·-7 1337 lo~ Go.~~ ~f Go'>sZi rrot<"S G:~ \~~~& be,. ~-~ _ Ga.'$sdL 'N,..s -""c o-,l ~"'~s c \ dtn.~~S\ a..\::ove o.c-. _ --~w ~rou..r6l_-:- ~ __ o_~•&_ ~c ~ccV\. …
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·- ·- FINAL DRAFT PRELIMINARY ASSESSMENT GASSETT MOTORS ST. THOMAS, U.S. VIRGIN ISLANDS PREPARED UNDER 02-8902-41-PA REV.NO.0 TECHNICAL DIRECTIVE DOCUMENT NO. 02-8902-41 CONTRACT NO. 68-01-7346 SUBMITTED BY: DIANE TRUBE ~ PROJECT MANAGER FOR THE ENVIRONMENTAL SERVICES DIVISION U.S. ENVIRONMENTAL PROTECTION AGENCY MARCH 24, 1989 NUS CORPORATION SUPERFUND DIVISION REVIEWED/APPROVED BY: ~JU~ RONALD M. JAMAN l FIT OFFICE MANAGER TUT 001 2054 *64410* 64410 - ~- () \Cj C, ·O _________ l:) ,-, I I ·-:::7 , ...... , C 0 ~-•· v--- ::r- ,.3_ )c ,i ' \ 00 l ul -ri;o t -Z'i • \ r'J o,.' '- ({_ j •\ S 01ru (_0 <' ~\A -b-n \C. exca.1...;o..::L.0-- ~\JC "-~ '$'1 S*·YY' G--+ 1-Jorrl.. e.,..cO (bock cf s-.~) \¥\.~ .1._ ~ 'D '-1 ~ ~ e.icce..uc:_-C.c.,:_ C0 .-'\ -:--<oL¼ r-s . - ~-., d ,r, b \)\~( 'S~cY; .... ~ _, c.Ji:a.- ,c+ oT \---½(5-m C!1.,C Ot\..S " 1 ~J \~ &&cs"-+ ~\.v \'4:)w . --- Lta.~s oro0tz.-h __ . ~ r ,·-7 1337 lo~ Go.~~ ~f Go'>sZi rrot<"S G:~ \~~~& be,. ~-~ _ Ga.'$sdL 'N,..s -""c o-,l ~"'~s c \ dtn.~~S\ a..\::ove o.c-. _ --~w ~rou..r6l_-:- ~ __ o_~•&_ ~c ~ccV\. -· ·=---- ~-~~~9~~ _ l~ --~ck-~~d=_J_J:;ss~_o;f .A-~r~r4 ----·- -- - -- ~?~ b.~ _ ~ \'m~- s,~~ Pr\a.'1 'fr. 4 - S:S-c;-C-1..I ,~;' "2..o~J.. &r~r\1S -,..... ~ (C(-M1 cf tm ~ ~ • \hr 9ic..ss.<."'tt SCM.t~ ~~ ~--e. ~r-<... ~ k.,.. k l.c..s.e& ,.le · be~ ·1~ ¼~..( ~ {~~~~- ('-Ar-. 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'· h .l--- -~ .. ,ml,.1.,,,-r.1 o..:;,::.. -- __ s- V~_ L~c.;'t _f'1~-~ r- _t-CO I __ __ _ _ ___ -:-f _ -- :- -'c__!\_1 Li)_ G.~-•~<;- ____________________ J _ __ ·---·~,..a..c.c .. ·_Ue.±(=_~os_ ~";; · ___ tfu;h~~,------ __ __? __ _ _ _ _ _ <fac__bt: _lia.u~-- --'~-:·~.,,.---- 9 ______ _ ,c .. c<"U:l ~~ IQ ca Cc C ==* ::r-o nr2) l'2,, ~~ c.A· ,,,L"-'ol,«_. __ l~L~-=.~ro~c,.i.::s-c'-'~ ,z.. 11 'C ('---,' \ C"r,, - · C"'.1 t- - - / c: .1 ,- \.. , 1? - '....)CO\,J.,r--,_~_ ----~ •- __,...'-i. ,L,L_ _,_,a_.~-(:- -~~LJ._'"u--_\---~---- -- --------- -- ~t{ ______ --- Gc....-=...ctt b.c::t-o.,.s. --------------- __________ JS: --- . ~o..m~ '"r C\\c ~ r ,$ - . ~ _. J .......,~_ ....,s:;c_ Lo'\ o.... 8 '--1~ __ __ A,;?or T _ t"°'~•• C'l_ rc,..;v• -~ ~~aJc:.. ..,-<"tt.? ,c. +'\ ,'.- " . -,) :,c, ,",-... l"T ,.- -~e.'~~c: ;:;> '-v I '1) ? l\.l R.. ... ,. -- __ 1~--- ... - -- _ __ ------ -------'~-- -----· - -· ,7 __IJ(_ -- __1q_ ---- 1q_ --- - - ____ '2..0 ___ -Z.O - --- 2.'2. ------- -- ... --- . --------- ------ --------+- rr-- -z:c- -, ·- --- -~~ l;n. lo-. C\,, ~ ·•· ,,./C1 f 'IC/ 1 .. -~---- -~~~---- 2 .,---; , __ .. .. --. ,-- ··-- -- NUS CORPORATION II 0398 ' ' -. <.. : • .- ;-=- . - . .,...ai.w ... m,r,~::-·_ 'L L L ,_ •. -- ,. '. I L L REF£REJIC£ NO. l TUT 00.1. './060 18. 19. 20. 21. REFERENCES (CONT'D) 02-8902-41-PA Rev. No. 0 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. Telecon Note: Conversation between D. Goeu of Polycaribe and 0. Trube, NUS Corp., on 3/14189 at 1430 hours. RE: Wells and water use on St. Thomas. 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. Record of communication, telephone conversation between L. Reid, DPNR, and A. Brochu, U.S. EPA Region 2, on 01/30/89 at 1400 hours. - TtJ-r ()t).l .'?()(~.i .t REFERENCES 02-8902-41-PA Rev. No. 0 1. Field Notebook No. 0398, U,S. Virgin Islands Drum Reconnaissance, TDD No. 02-8902-29, NUS Corp. Region 2 FIT, Edison, New Jersey, February 14 to 17, 1989. 2. U.S. Department of the Interior, Geological Survey Topographic Maps, 7.5 minute series, HCentral 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. SO CFR 17.11 and 17.12. February 1985. 8. Telecon Note: 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 I nvesti gati ons 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, In Caribbean Geological Investigations, Geological Society of America, Memoir 98. ed. H. H. Hess, 1966. 12. Climatological Data Annual Summary, Puerto Rico and Virgin Islands. National Oceanic and Atmospheric Administration, 1987. 13. Torres-Sierra, H. and R. 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. 1 S. Mer.m to Stephen D. Luftig, EPA, from Carlos O'Neill, EPA. Authorization of CERCLA Removal Action Monies for the Tutu Well Site. January 6, 1988. 16. Jordan, D.G. and O.J Cosner, A Survey of the Water Resources of St Thomas, Virgin Islands, U.S. Geological Survey Open File Report, 1973. 17. Water Management Plan for the Public Water System, Prepared for the Government of the Virgin Islands by CH]M Hll July 19A l ·r1Jr ()C;J. •i,i,., L r r L L l ~ L ATTACtlENT 8 r REFERENCES I_ j-- ! . L ' L [ l L r ......., I l. R3-P12 GASSETT ~OTORS ST. -:-HOMAS, U.S. ,:RG~il :SL..1.NOS February 15, 1989 1400 ;2-0902-.: ~-~ . .; Rev. ·;o_ 0 Sewer manho1e. Tutu Texaco in background. Ti.!'1 I , 1' l I ·-..__,,., I I I R3-P 11 - GASSETT MOTORS : 2- -~ 90 2-.:. ~ - :: .: ';eV. :)o. 2 ST. -:-:-iOMAS, J.5 . .'1RG::; ::L,:,;;os ! , • :~ \ . '. , ; ~ ·-~ '· ·- . ' February 15, 1989 ~ , I Oil- stained vegetation. 1356 I I I I ___, I R3-P8 -- - SASSETT MOTORS _:<~CZ-..:~_;.: :ev. :.o. ~ -:-:10MAS. :.i.S .. :RG~:; =:i... . .:..:rns February 15, i989 1351 Northwest corner of property, showing oil pool near drums. TUT OOJ .. :~'. () t~.• f_:, - ..... - ....,,...,,..._ -- - -) '= .J ..:. - ..... _;_ - - .... , ~ev. :.o. :, GASSETT MOTORS .)1. :-;1QMAS, J.S. '/IRGI~J ~SLANDS R3-P9 February 15, 1989 1352 Origin of Jil-filled drainage ditch at north end of property. - .. f'l.JT t_ .. )l) .·.,•.. . ... - :.::'.()(:,·:/ 18 r ,- ---, . r I ... J/ / JJA_ -;::, ·' . ,.• Q_.,· I ""\€.:Jl.~~eo Q '.:ct.,/ •'lQ.:!"" r,vi, •~a;· U.,,L/ n'\..ek:-t- i,4_!:_ a_~ C? 3e, -cfvo_ o.:+ D,t.;f~ ~~'41..;:· C& :; C t'-l.:_,f :J 1'-'fc. ~, c) -,- 12 ~ ,-h....\;Ji rr.1 .·-to C..C l~-t- ~..,; ~.;;l~~ "I , • ~' -~ d,.._c:,.-'? . C 7 :2 s: ('t-rr, :..~d 0--i -:: "~ R off,c_e.s l·"t1.•. ~ 01,..~,- o-r , , 1-"C..<:{) • we _ .--<-<..J ...,,__-c....01 ~ Ni!.J:....c --s ..,.,r \ ... ,,_c..-5 - 2... ._..~r<:-a c__ -+n....---._ 'c ~ - (' ~,(" ~""°-"'-1 k.d ((''-f'C~-- ~I~~ ~ C~ ,n "'- 6..,. 1.,4,,("~ ___ . ______________ . , ~ '-t _ ~(,/ IA-''2-£ <::. ~l;)G-DS:.!ff __ jc 'o..e... . r-f:.c.s.e.~ fc r o._ l i _____ ,.~5.:c.., - lt5 5~l_[ ___ ~----~-•~fu_-i:-__ CQ-!: __ ~~.......:_-s- --~- He.... ......i:.JL ____ tr~ __ .::f-tl__~ru~;.cQo G w, ~~~~--.:fu-.~e. *. __ ___ =pop- __ i."-~----------- ___ -._wt.lli __ -®--0:.-v-::--. __ brp,.....,Ck«- bl-t~i _____ -----· __ _ ·------------- ..... . ________ __.i..;,€;_· ~--~.!:1;.,_.~'.i:-f_...._ ____________ --· ----- -- ---··· ... ' __ :-:. _J _s~~~es~-~~--W~S +RIO&~ -~-~_o._{_ PA.k.~~---- --- -~c.._ tso""o-rd.i.. ~ s.u:... -~---l~ef._:--;.:(0-.... ~ -'~ c.::r . . a.iH.~ ms. Mc.,,s~t qo~n'\ tc:-tl I.LS_ ~--0-.~r.~_:±___ _ _ ___ _ .. __ -05£)6_ .Cl\.12.c.~-,,.,~. ~...... ~+ a...:c-?c.,t - _ ~h;.ns o:.f 4X-ib~. o·, i l'Jr,.(.v.1...'S" .... o.h. - c- I C · ~o..l.>-'_.wecc,·i;;I.,(_, --,, __ lr-ci...<: =?To..-_:_ _ c..o,c....,... -:.~~------- ~ -\_; ,-( \ • ,\. A-:• _c::\·7",vf1<- (\.:.;' cc .,,._(-f __ : ___ r~ot~---~d...t ~-"-\-o..v.,_o-.,.. (..( : __ ) I - - - 02-8902-41-PA Rev. No. 0 POTENTIAL HAZARDOUS WASTE SITE PRELIMINARY ASSESSMENT PART I: SITE INFORMATION 1. Site Name/Alias Gassett Motors Street Route 384. Tutu District City St. Thomas 2. County .... N=/A-'------------- 3 EPA ID No ..... N:..:e;.;;.w;;..;S=i=te _________ _ 4. latitude 18° 20' 38"N State U.S. Virgin Islands Zip ~08:..:0..,.0=2'--_ County Code N/A Cong. Dist._""""N"'"/.;...A ___ Longitude 64° 53' 19" W USGS Quad. Eastern St. Thomas. U.S. Virgin Islands 5. Owner Unknown Tel. No. _,;_;;Na.:../A-'----------- Street Unknown City Unknown State ...;.N=/A:...a..... ___ _ Zip N/A 6. Operator Tom Gassett Tel. No. (809) 776-4600 Street Route 384, Tutu District City St. Thomas State U.S. Virgin Islands Zip 08002 7. Type of Ownership ~ Private □Federal □State □County □Municipal □Unknown □Other _____ _ 8. Owner/Operator Notification on File ORCRA3001 Date 0 CERCLA 103c Date ____ _ ~ None O Unknown 9. Permit Information Permit None Permit No. Date Issued Expiration Date Comments 1 O. Site Status ~Active 11. Years of Operation □Inactive Unknown □Unknown to _P'-'r __ e=se;.;..n=t __ _ 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 1 Drums Facility Name for Unit Waste Oil Drums - (b) Other Areas of Concern 02-8902-41-PA Rev. No. 0 Identify any miscellaneous spills, dumping, etc. on site; describe the materials and identify their locations on site. Waste oil from a drainage ditch on the Gassett Motors Site is discharging onto the adjacent Ramsey Motors property. 13. Information available from Contact Amy Brochu Preparer Joseph Mayo Agency U.S. EPA Tel. No. (201) 906-6802 Agency NUS Corp. Region 2 FIT Date ::3/-=2"-"4/:...::8:..:9 ___ _ ·r LJ 'T (.··.,, ,.·.·.·J ~•. ,... •· -- .,.::'. () ~-7 () 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 02-8902-41-PA Rev. No. 0 1. Identify the RCRA status and permit history, if applicable, and the age of the waste unit. The site does not have a RCRA Permit. The age of the waste unit is unknown, but Mr. Gassett indicated that the drums were present when he leased the property in May of 1988. 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 waste unit is located behind the main building adjacent to an overhang garage. 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 four 55-gallon drums and three 20-gallon drums located in the northwest corner of the property. 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 drums contain liquid waste oil from automotive repair and servicing operations. 5. Identify specific hazardous substance(s) known or suspected to be present in the waste unit. The drums on site contain liquid waste oil from automotive repair and servicing operations. The drums may also contain small quantities of gasoline, kerosene, or degreasing solvents. 6. Describe the containment of the waste unit as it relates to contaminant migration via groundwater, surface water, and air. The waste is not properly contained. There were numerous spills in the area, and there was a large pool of oil in the northwest corner of the property where the drums are located. A drainage ditch containing waste oil originates along the northern perimeter of the property and proceeds westward to the northwest corner of the property, where it turns southwestward onto the Ramsey Motors property. An oil-stained area was observed on the Ramsey Motors property at the point where the drainage ditch left the Gassett Motors site. A larger ditch on the Ramsey property drains the stained area and discharges to a storm sewer. Given the above conditions, the potential exists for waste migration to surface water and groundwater. Ref. Nos. 1, 20, 21 TUT 00.1. '?0'/ 1. - PART Ill: HAZARD ASSESSMENT GROUNDWATER ROUTE 02-8902-41-PA Rev. No. 0 1. Describe the likelihood of a release of contaminant{s) to the groundwater as follows: observed, alleged, potential, or none. Identify the contaminant(s) detected or suspected, and provide a rationale for attributing the contaminant(s) to the facility. The potential exists for contaminants to be released to groundwater. Pooled waste oil was observed in the drum storage area, and a small ditch containing waste oil was dug in the soil around the garage area. In addition to the waste oil the drums may contain small quantities of gasoline, kerosene, and degreasing solvents. Ref. No. 1 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 of dioritic plutons. The Water Island Formation, which is late lower Cretaceous in age, consists of keratophyre and spill ates. The Virgin Island Group, which is probably early Cretaceous or Albian in age, consists of andesitic-pyroclastic rocks and sedimentary formations. The Virgin Island Group is divided into four formations: the Louisenhoj Formation, which consists of augite-andesite breccia, tuff, and conglomerate; the Outer Brass Limestone, which consists of partially silicified- tuffaceous-radiolarian limestone; the Tutu Formation, which consists of tuffaceous wacke, including megabreccia near the base and limestone near the top; the Hans Lollik Formation, which may be Eocene in age and consists of augite-andesite breccia and tuff. The final group is made up of one or more dioritic plutons. These unnamed dikes and plugs of quartz- andesine-hornblende porphory are Upper Cretaceous arid Lower Tertiary in age. Alluvian deposits are quarternary in age. The Water Island Formation, which consists of 95 percent volcanic flow breccias was probably extruded on a relatively level ocean floor. The absence of terrigenous sediments from this formation indicates that there were no emergent islands present in the area at the time of extrusion. Emergent islands would have served as a source of weather sediments or detritus, which are 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 eruptions near the top of the formation. Regional uplift occurred near the end of the Water Island time. The Louisenhoj Formation of the Virgin Island Group unconformably overlies the Water Island Formation and crops out on about half of the land area on St. Thomas. Pillsbury Sound between St. Thomas and St. John was the origin of this formation. Evidence of this center is based upon the coarseness of volcanic ejecta in the formation in nearby eastern St. Thomas and western St. John. Material is less coarse and tuffs are more predominant as one moves further east and west away from the center or origin. This augite-andesite formation ranges in thickness from 4,000 to 13,000 feet. In certain areas of St. Thomas and St. John conglomerates are interbedded with andesitic rocks at the base of this formation. The depositional environment of this conglomerate varies from location to location throughout this formation. The Outer Brass Formation of the Virgin Island Group is mostly siliceous limestone which overlies the Louisenhoj Formation. The limestone formation is an offshore deposit formed by radiolarian and foraminiferal remains including a minor amount of tuff. Thicknesses are known to be 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 is a megabreccia lithofacies with an average thickness of 30 feet and a limestone member with a thickness up to 300 feet. -· ':--· - 02-8902-41-PA Rev. No. 0 The Hans Lollik Formation, which consists of at least , 0,000 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; in 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-andesine porphyries, andesine-hornblende porphyries, lamprophyres, breccias, and pegmaties 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 recent Pleistocene to Holocene alluvial deposits occurred primarily in coastal embayments. However, a narrow bank of alluvium extends up to Turpentine Run on the east end of the island. Most of these deposits are composed of silt, clay, and thin, discontinuous beds of sand and gravel. Maximum thickness of these is 50 feet. Groundwater movement is limited to openings and joints along fault zones. Regional geologic information is insufficient to determine whether these fractures and fault zones are present in all of the above-described formations; however, for this report it is assumed that the fractures and fault zones are present in all of these formations. The valleys on the island are the result of weak zones caused by faulting and jointing and are primary recharge areas for groundwater. Alluvial deposits have a high porosity but low permeability, making this aquifer unfavorable for groundwater production. In coastal embankments throughout the island, saltwater intrusion is widespread in alluvial deposits. In most areas, alluvial deposits are interconnected with bedrock and act to recharge precipitation to the underlying bedrock. The direction of groundwater flow in the Turpentine Run Basin Aquifer is south-southeast which is generally along the direction of flow of Turpentine Run. Depth to groundwater in the aquifer ranges from 5 to 60 feet, and the altitude of the water levels ranges from 1 to 209 feet above mean sea level. Ref. Nos. 9, 11, 16 3. Is a designated sole source aquifer within 3 miles of the site? There are no sole source aquifers, as designated in the Federal Register, 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 in the waste unit were deposited on the ground surface. Depth to groundwater in Virgin Islands Housing Authority VIHA well Nos. 1 and 2 was reported to be 56 and 60 feet, respectively. VIHA well Nos. 1 and 2 are located approximately 630 feet southeast of the Gassett Motors Property. 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 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 TUT 001 207.::: - - 6. What is the net precipitation for the area? 02-8902-41-PA Rev. No. 0 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 SO 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 evapotranspi ration 40 inches precipitation - 38.32 inches lost to evapotranspiration = L68 inches net precipitation. Ref. Nos. 3, 5, 12, 13 7. Identify uses of groundwater within 3 miles of the site (i.e., private drinking source, municipal source. commercial, industrial, irrigation, unusable). Groundwater within 3 miles of the site is used as a source of private and municipal drinking water, and for commercial purposes. There are at least 41 wells within 2 miles of the site. Thirty-four of the 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 purposes7 Distance 630 feet Depth 150 feet The nearest well is the VIHA well No. 2, which is located approximately 630 feet southeast of Gassett Motors. This well is believed to be used for drinking. A nearby well, VIHA No. 1, was ordered closed because of contamination with volatile organic compounds. VIHA well No. 2 is not listed as being closed for contamination, and its designated use is for domestic purposes. Ref. Nos. 6, 9 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 uses 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 rur uo.1 .• :'U./.t/. SURFACE WATER ROUTE 02-8902-41-PA Rev. No. 0 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. - The potential exists for wastes on the site to be released to surface water. There is a large pool of oil on the ground in the drum storage area, and there is a drainage ditch, which contains waste oil, that runs along the northern border of the property and discharges to a drainage ditch on the adjacent Ramsey Motors property. The ditch discharges to a storm sewer. It is unknown where the storm sewer discharges, but it is likely that it discharges to Turpentine Run as this intermittent stream drains the entire Turpentine Run Basin. The drums on site contain waste oil from automotive repair and maintenance activities. Small quantitaties of gasoline, kerosene, and degreasing solvents may also be present in the drums. Ref. Nos. 1, 2 11. Identify and locate the nearest downslope surface water. If possible. include a description of possible surface drainage patterns from the site. The nearest downslope surface water is the Mangrove Lagoon which is hydraulically connected to the Caribbean Sea. The distance from the site to the nearest surface water along the course of Turpentine Run is 2.5 miles. However, the site slope is such that runoff flows south-southwest to storm sewers on the property. 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 Turpentine Run Basin. Ref. Nos. 2, 4, 5, 14 12. What is the facility slope in percent? (Facility slope is measured from the highest point of deposited hazardous waste to the most downhill point of the waste area or to where contamination is detected.) The facility is relatively flat with an overall slope toward the south-southwest. Facility slope is estimated to be 0-3 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.) 14. The slope of the intervening terrain can not be calculated as runoff discharges to storm sewers and the path of these sewers is unknown. If runoff were to follow an overland route, the slope of the intervening terrain would be as follows: • Elevation of waste areas - 240 ft • Elevation at point of entry- 0 ft • Path length - 13,200 240 ft - 0 ft X 100 = 1 .8% 13,200 ft Ref. Nos. 1, 2 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. Two-year 48-hour rainfalls range from 4 to 15 inches It has also been reported that it is not uncommon for 24-hour rainfalls to be 2 to 3 inches Ref Nos. 4, 6 TUT UO.l_ :2U/~:i 15. 02-8902-41-PA Rev. No. 0 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 above surface water is approximately 2.5 miles as measured along Turpentine Run. It appears that most runoff from the site enters the storm drains near the site. Since the point of discharge and the route of these storm drains are not known, the distance to the nearest downslope surface water along this pathway is unknown. Ref. Nos. 2, 14 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 OPNR has designated the area of the Mangrove Lagoon for preservation. Ref. Nos. 2, 14 17. Describe any wetlands, greater than 5 acres in area, within 2 miles downstream of the site. Include whether it is a freshwater or coastal wetland. There are no wetlands greater than 5 acres within 2 miles downstream of the site. However, there is a coastal mangrove wetland approximately 2.5 miles downstream. The Mangrove Swamp is designated as a preservation area in the Coastal Zone Management Program of the DPNR. Ref. Nos. 2, 14 18. Describe any critical habitats of federally listed endangered species within 2 miles of the site along the migration path. There are no known critical habitats of federally endangered species within 2 miles of the site. The Virgin Islands Tree Boa (epicrates monensis granti) is an endangered species in the U.S. Virgin Islands; however, no critical habitat has been identified for this species. Ref. No. 7 19. What is the distance to the nearest 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 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 and there are no 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 that uses seawater 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 designed as a preservation area by the DPNR. Ref. No. 14 TUT OOJ ·~ j , '/_, 22. Describe any apparent biota contamination that is attributable to the site. A patch of oil stained vegetation was observed during the on-site reconnaissance conducted by NUS Corp Region 2 FIT on February 15, 1989 Ref No 1 AIR ROUTE 02-8902-41-PA Rev. No. 0 23. Describe the likelihood of a release of contaminant(s) to the air as follows: observed, alleged, potential, none. Identify the contaminant(s) detected or suspected, and provide a rationale for attributing the contaminant(s) to the facility. No potential exists for the release of any significant quantities of contaminants to the air. No readings above background were detected on the OVA flame ionization detector or the HNu photoionization detector during the on-site reconnaissance of the drum area conducted by NUS Corp. Region 2 FIT on February 15, 1989. Ref. No. 1 24. What is the population within a 4-mile radius of the site? Based on the 1980 census, the population within 4 miles of the site is approximately 36,000. Ref. No. 17 FIRE AND EXPLOSION 25. Describe the potential for a fire or explosion to occur with respect to the hazardous substance(s) known or suspected to be present on site. Identify the hazardous substance(s) and the method of storage or containment associated with each. Although the waste oil was not properly contained, the site does not pose a significant fire and explosion threat. No readings above background were detected on the OVA flame ionization detector or the HNu photoionization detector during the on-site reconnaissance of the drum area conducted by NUS Corp., Region 2 FIT on February 15, 1989. Ref. No. 1 26. What is the population within a 2-mile radius of the hazardous substance(s) at the facility? Based on 1980 census data, 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. The potential exists for direct contact with waste oil at the facility. The oil was not properly contained, and there was a pool of oil on the ground near the drums. The area is not accessible to the public as a fence surrounds the facility. There is a potential for workers to come in contact with waste oil on the site. 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 1980 census data, the population within 1 mile of the site is approximately 11,000. Ref. No. 17 TUT OU 1 :?U?l - 02-8902-41-PA Rev. No. 0 PART IV: SITE SUMMARY AND RECOMMENDATIONS The Gassett Motors Site is located in the Ttstu area of St. Thomas, U.S. Virgin Islands. Gassett Motors is in automobile sales establishment. The site was formerly occupied by consolidated auto parts. Mr. Gassett leased the property in May of 1988 and has occupied the facility since that time. The owner of the property is unknown. The area within approximately 1 mile of the site is densely populated and contains some commercial properties. The site is bordered on the northeast by Ramsey Motors and on the southeast by Tutu Texaco. There are large housing developments north, southeast, and west of the site. The nearest residence is located approximately 200 feet west of the site. Beyond a 1-mile radius of the site there are scattered smaller villages and towns. The densely populated and highly commercial town of Charlotte Amalie is located 2.5 miles west of the site. On February 15, 1989, NUS Corp. Region 2 FIT conducted an on-site reconnaissance of the Gassett Motors Site. There are four 55-gallon drums and three 20-gallon drums located in the northwest corner of the property. There is a pool of oil around the drums, and a drainage ditch containing waste oil originates along the northern perimeter of the property and drains toward the northwest corner of the property, where it turns onto the Ramsey Motors property. Once on the Ramsey Motors property, the oil enters a large drainage ditch which drains toward a storm sewer. Mr. Gassett indicated that the site was in the condition described above when he leased it in May of 1988. No readings above background were detected on the OVA flame ionization detector or on the HNu photoionization detector in the drum area. 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 of oil 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 all their waste oil, but the facilities are not inspected or issued storage permits. These conditions, combined with drum shortages and poor housekeeping, have resulted in generally poor waste containment at many facilities. There is concern that contaminants possibly present in the waste oil will enter groundwater and surface water. There is a pool of oil that may percolate through the soil and enter groundwater. Oil is draining from the Gassett Motors Site toward a storm sewer on the Ramsey Motors Property. Groundwater in the vicinity of the site is used for domestic purposes. The nearest surface water, the Mangrove Lagoon, is surrounded by mangrove swamps that are designated for preservation by DPNR. ·r l..J'l t)(} J ~?()"/ t3 02-8902-41-PA Rev. No. 0 --.__.., Based on the above considerations, the Gassett Motors Site is given a MEDIUM PRIORITY for further action. Sampling activities should focus on determining whether the oil contains hazardous substances and whether those substances are migrating to the storm sewer on the Ramsey Motors property. Nearby wells should also be sampled. It sould be noted that a number of these wells were found to be contaminated with volatile organic compounds; therefore, judgement should be used in selecting appropriate wells for sampling. Further efforts should also be directed towards better definition of the population using groundwater for drinking. No enforcement actions have been taken against Gassett Motors in the past. The owners of the property have been identified as one of nine potentially responsible parties in the contamination of groundwater in the Tutu area. In July and August of 1987, EPA confirmed by sampling that volatile organic compounds were present in a number of wells in the Tutu area. DPNR issued orders to close 16 of the wells. EPA removal action activities in the Tutu area included sampling of wells and cisterns, removal of contaminated water from cisterns, and supplying of clean water on a regular basis to affected residents. [ [ -- [ r [ [ [ [ r r -- r- I I I [ I l -- I ATTACIIENT A MPS AND PHOTOS TUT ()01. 2ouo - GASSETT MOTORS ST. THOMAS. U.S.VIRGIN ISLANDS CONTENTS Figure 1: Figure 2: Exhibit A: Site Location Map Site Map Photograph Log 02-8902-41-PA Rev. No. 0 TUT OU.l 20tl.l .. ,, -c - SITE LOCATION MAP GASSETT MOTORS - ' ST. THOMAS, U.S. VIRGIN ISLANDS SCALE: 1·• 2000' vc..-u:,vc..-"t.1.-rM Rev. No. 0 110 - s:;, , c-- FIGURE 1 TUT 001 20U2 > l-a: LLI a. 0 a: a. Cl) a: 0 l-o == > LLI Cl) == c( "C OIL POOL DRAINAGE DITCH .,, • FENCE x------x:------x---------~ OIL flLLED SHED OVERHANG GASSETT MOTORS LOW WA.LL MANHOLE (OPEN> \, PAVED I{ If )t _______ ,J IBlll+--GRATE !~ SEWER BREAK IN a--GRATE FENCE PARKING LOT ( PAVE DI - ____ ........ _________________________ _ ROUTE 384 SITE MAP GASSETT MOTORS ST. THOMAS, U.S. VIRGIN ISLANDS NOT TO SCALE TLJT 02-8902-41-PA Rev. No. 0 :\=-STAINED :;:: VEGETATION FIGURE 2 Photo Number R3-P5 R3-P6 R3-P7 R3-P8 R3-P9 R3-Pll R3-P12 GASSETT MOTORS ST. THOMAS, U.S. VIRGIN ISLANDS FEBRUARY 15, 1989 PHOTOGRAPH INDEX ~LL ~ttn1QSRAR~S TAKEN BY DIANE TRUBE. Description Grate in front of building. Grate under fence. Drum and oil pool in corner. Nortllwest corner of property; showing oil pool near drums. 02-8902-41-PA Rev. No. 0 Time 1344 1346 1349 1351 Origin of oil-filled drainage ditch at north end of property.1352 Oil- stained vegetation. Sewer manhole. Tutu Texaco in background. fUT t.iC•J 1356 1400 I I i j I i I I ! I I I I I ! I I I -- - R3-P5 - GASSETT MOTORS :Z--;902-..:>,::. .:;,ev. :;o. j -:-:-10MAS. U.S. ::RG:il :3L,'.,;;os February 15, 1989 1344 Grate in front of building. ! l I I I - R3-P6 "'?..ev .. ,o. : SASSETT !~OTORS .:,1. -:-:-iOMAS. ,;.S. ,:RG;:;; :sL,:,irnS February 15, 1989 Grate under fence. 1346 \\.JT - """ r ,...,....,.... . i.--.:-::i....:.:.- ... G,;ssETT MOTORS ::.,. -:-HOMAS. J.S .• :RG;::; ~SLMiWS I I I R3-P7 February 15, 1989 1349 Drum and oil pool in corner. I - L r l_ I. REFERENCE NO. 2 -- .....___ ·6- ,,._ 81 ( QUAD> EASTERN ST. THOMAS, V.I. SITE LOCATION MAP GASSETT MOTORS ST. THOMAS, U.S. VIRGIN ISLANDS SCALE: 1·• 2000' 110 ----t-: .:; - s:, , FIGURE 1 REFERENCE NO. 3 - Summary Appraisals of the Nation's Ground-Water Resources- Caribbean Region , , By FERNANDO GOMEZ-GOMEZ and JAMES E. HEISEL GEOLOGICAL SURVEY PROFESSIONAL PAPER 81!-U ·, .. _.,. UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON:1980 ru·1· UOl 2091 - -------------- U20 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES TABLE 4. - Water ~t. i1t Cllbic MC~ per ,ecir (Affl.1/yr) 1111d J)ffl:fflt. for Pvrrto Rico (by ""°"° Rico Nonll Cou, ProYlnce Soutll Provi,... Wntcout to Rio G,,.,. do Rio* La Patillu TalW- L&iu w ... c-, Rio G,,.,. A-to Rio Pia\& to Ilk> to IO do ,\Nc,,bo do La Plata E:!!!!!:!tu Sanw p.,,,.. Guaaa Valley - hm11vr Pffftflt hm1fyr Pen'.'enl hmJ,vr Pffftflt hm1tyr Perttnl hm1lyr Pffftflt h,nl/yr P•rttnt hm1lvr I Pff<ellt laput PP'l."t'1p1LllJon _________________ l.lillO 73.0 1.:.!lkl !'>S.4 .;;o ;u 410 .'i(J.6 60 ~.s 100 ,2.11 ;lti(J :.!!1.0 St~amrluw t\20 ~7.0 l.03U H.li ;,YO ~.II Jl?O J11.5 175 74.5 4.4 ;J ., _, il.O 01v•r,wns _________________ IIO ~-» 33 24.0 Output !:VIIIJUl.l"Upt,al.lun ·•------•----- 1.410 lil.3 lll)4 3U JOO 2U 4:JO 53.I 60 2U ):ti) ~i.3 :!70 21.11 Stnoam ou~• _____________ llti6 3,.6 l,J,;o ,'oil., ~2111 ,3.0 IYO :e!:U 100 a.s II ll.O !l'JI) ,4.2 tiruund-wakr lou to w"1.&a.nds ur ~• -------------- 15 l!6 3,i :!O 1.6 :ti) 2.5 15 u 6.3 4 ti 4U 3.2 (.;ruund•w&Ler w1lhdrawa.b 1: T,Ol&J ·----------------·-- 10 .4 tiO 2.6 :ti) 1.6 170 21.0 60 2U .I 10 II lnduatry ___________________ ~ 26 ; 19 21 10 lmpt.tun .., ______________ II 143 :n Publ1< aupply ______________ I 26 15 II 2 1 All .cruund waLrr w1Lhdrawn wu aaunwd tu bl!' for cumu~taun sm<"t' 1t 1i. nol ava1iabM' fur uOl•r wws. 1000.-------.----.----.---..-----....... --.. 100 .. C 100 Ill ► .. Ill ._ 400 .. .. Ill ... ; zoo 0 ... u Ill % 0 u ii ::::, u ~ .,; 400 .... C I .. .. % ... i Public Supply (Putrto Rico Aqu1ducl ond Stwtr Authority) TOTAL WITHDMWAL IMS 1170 1175 IH0 1915 19to 1"5 ZOOO YUIii A zs..---.---"T"""----.---.---.----.....--....... -- 2O ~ 15 Ill ► 10 C ~ 5 .. : OL----L---'-----1--....&..--.L--....J.--....&..---' ... !~--~----~----~-~----- ... ::: 45 z ~ 40 a" • -- JO • ~ 25 • : 20 I 15 ... i 10 5 ?NO INS 117'0 IHS ltlO IHS IHO ltlS 2000 YE.ARI B F1•;1 1<t: li.-Water-use t-stimates. A, For Put-rto ttico: public-supply data provided hy tht- Puerto Rico A11u«luct and Sewer Authority (moriilit"tl from Morris. rn7fi). B. for the U.S. \'irgin Islands. i)Ul -- CARIBBEAN REGION U21 l'111-t1,u k._.,,-Conllnvt'II l·.s. Vor,con lllland, ht.·rtA• k.,,·" ofrtlh.,no -,,,t:- Eu•~• l""'""r 1-'IM"f1.A1 kru ~--- ,.,., ..... , Cult-bra Mut\.l ~l. Crun: s, ,..,, __ . SI. Juf'UI t!'U"'nn- ~- hm>lyr Pwn-nt hnt'r~·r .,.......nt hm3')r l'.-rt't'nl hm~l."·r .....,,....,, hm"~r 1-'t>n,-nt hm.11_\r 1-'..-n't'nl hrn' 1.n· .,....,,.,., hm'•~r t'e-n,·nl hfttl1\r Yrn.,-111 Input-Continued aw 43.3 IU.l!Sio IUO lo,11:IIJ IUU l:W IUO ;l!, 100 .a:, IUU ;ctll IUO »a lt.ll .-~, tuu SIU $6.7 Outpial Continiacd r,~ 31.U ti.oil ,lj_v IU,l:,t; 64.t 110 !:fl .i 24.tl SIIII 6H 4.:Mt a».v ,.1146 31.~ 6 a.II ., au 3.3 '.ttiU I.I\ 3.3 t.i .3 12 1.3 16 .2 3M 2.3 .7 .6 .114 Ill ' ,, .. t 118 It titi PR.OBLEMS AFFECTING USE OF WATER RESOUR.CI.S MANAGE.ME.NT-PUUTO I.JOO 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. I Although numerous government agencies (State and Federal) and institutions are involved in the use, plan· I ning, management, and investigation of the water 1 resources, the DNR, EQB, U.S. Environmental Protec- : tion Agency (EPA). PRWRA, PRASA, Puerto Rico! Sugar Corporation, and heavy water-use industries i VS.K 3~ .·, 1;,f' iu:, !13'' ~· ~.i t.11 u u " 3.t. t.n u S..5 ,i.:t 5,.:'1 i.r, u 1.3 ·" I.I .2 ti II 1.a ., .t ti established by PRIDCO exert the greatest influenct- 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 tht> 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 tht> National Pollutant Discharge Elimination System, and management and planning for public watt-r- supply treatment-works construction. PRWRA. The authority produces and distributes elec- trical energy and administers and operates the irri- gation systems supported by releases from reser- voirs and the hydroelectric power-generation nt>t- work on the south coast and in northwestern Puerto Rico. PRASA. The authority is charged with developmt-nt. construction, operation, and maintenanct- of watt-r and sewer systt-ms and pn1viding adequatt> watt-r TlJT ()().I_ CiTl/C fr,~ --- U22 SUMMARY APPRAISALS OF THE NATION'S GROL'.ND-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 DNR and EQB an environmental-impact statement for each industrial project it proposes to develop. The agency also cooperates closely with the Plan- ning Board in preparing its plans and programs. The new centralized form of management stipulated in Law No. 136 of June 3, 1976, is intended to improve in- stitutional structures to aid optimum water-resources development. IIANAGDIENT-U.5. VD.GIN ISLANDS In the U.S. Virgin Islands, the Department of Conser- vation and Cultural Affairs is charged with the ad- ministration and enforcement of all laws relating to water resources and water 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 hlanda 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 W APA 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. WATf.ll a.lGHTS 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 modem 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- 11 1·-.- {JU :l l \ ... l CARIBBEA:--: R£GIO!\ l.:23 ly" (Art. 8). Similarly, as to "artesian wells, tunnels, or I galleries," (major ground-water developments as oppos- ed to "ordinary wells," which are defined (Art. 20) as 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- mits art> not required if pumpage is less than 2 m3/d for benefit-ial use. Undl·r Chapter 3. Title 12, of the Virgin Islands Code, trees and other vegetation adjacent to watercourses are protectt>ci 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- rooteti vegetation. A modification of this law would be necessary in order to exclude from such provision those waten·ourses that are used for public supplies or are in hydraulic connection with aquifers tapped for supply. PUCTICES DETRIMENTAL TO GROUND-WATll QUALITY LAND USE pressed the needs of the past century. First priority was Land use may affect recharge to an aquifer and the given to water supply of towns, followed by water sup- , quality of its water. Although there has been no exten- ply of railroads, irrigation, navigational canals, mills and I sive evaluation of the effects of various land uses on other factories, ferry boats and floating bridges, and aquifers in the Caribbean Region, data from scattered fishponds. The economic importance of water-using in- I sources indicate that this could be a major problem in dustries was not foreseen, and a low preference as to ; the near future. water concessions was stipulated. Duration of the con- Urbanization has taken over large portions of the cessions was limited to 99 years of town supplies (Art. recharge areas of aquifers in metropolitan San Juan, 170) and all other uses but was "in perpetuity" for irriga- Ponce, and Mayag(iez in Puerto Rico and throughout the tion (Art. 188) and fishponds and also for industry, as Virgin Islands of St. Croix and St. Thomas. Unless ar- long as effluents were not harmful to health or vegeta- tificial recharge is provided or withdrawals are reduced tion (Art. 220). to compensate for the loss of recharge, the seawater- As of 1909 there were approximately 250 concessions freshwater interface will move inland in most of these in Puerto Rico that were originally granted by the areas. Spanish Crown (Report of the Governor of Puerto Rico, Aquifers in the Caribbean Region are threatened by 1909). The majority of these grants were given to Ian- pollution from domestic, municipal, and industrial downers in the South Coast province for the irrigation sources. The most widespread source of pollution is pro· of approximately 21,000 ha. The surface-water conces- bably sewage from cesspools, leaking sewage lines, and sions included rights to flood-waters, spring and winter· overloaded or improperly operating sewage plants. In waters, or a definite daily flow. Puerto Rico about 37 percent of the population is served An updated inventory of vested owners, diversion by sewers. and in the U.S. Virgin Islands approximately amounts, and land under irrigation is necessary to 77 percent is served. In en I the only areas served determine the degree to which these rights could affect by sewers are those within ns. a water-use and distribution plan. ~ wastes have been discharged to aquifers In the Virgin Islands, all waters are in public owner- through sinkholes and disposal wells or have entered ship and are subject to appropriation for beneficial use aquifers from accidental spillage (D.G. Jordan, written as stipulated in Chapter 5, Title 12, of the Virgin Islands commun .. 1969; R.C. Vorhis, written commun., 1972). Code. Under this policy, veated rights are recognized Of the 15 disposal wells known to exist in 1972, only 2 prior to other appropriation. Vested rights may be could be designated as deep injection wells, and the nullified by the government of the Virgin Islands (Com- others could better be designated waste-disposal holes. missioner of Conservation and Cultural Affairs) when it All the known disposal holes were between 24 and 213 m is determined that the exercise of such rights would im- deep. Wastes disposed in sinkholes and disposal holes in- peril health or welfare by endangering, impairing, or elude sewage, oil, neutralized acid, organic compounds, destroying available sources of water. Nevertheless, the dyes, pickling liquors, pineapple-cannery wastes. and occurrence of such circumstances is very remote, as brewery wastes. Jordan (written commun., 1969) most private installations are for domestic use and estimated there were at least 40 such disposal holes in withdraw less than 2 m3/d. An exception could be those Puerto Rico in 1969. individuals and companies that sell water obtained from I It has also been observed that unproductive wells are wells. Under Section 153 of Title 12, appropriation per- either abandoned without plugging or are not thor- rur ()() .1. ..,... --- - U24 SUKKARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES oughly sealed. AB a result many are used as receptacles for wastes. The effects on water quality and the extent of damage this baa caused in the Caribbean Region have not been assessed. In the Lajas Valley, Vazquez and Ortiz•Velez (1967) obeerved that a downward hydraulic gradient existed at various abandoned irrigation wells. These wells probably are serving as hydraulic connec- t.ors between perched water t.ables and the underlying regional water t.able. The effect of these "hydraulic con- nect.on" on water quality is unknown. Disposal of refuse in landfills poaea another threat t.o aquifeni in Puert.o Rico. Most landfills were estaliabed after 1972 (fig. 18), and although migration of leachates may be slow at some sites, with time these will inevi- t.ably affect t.o some degree the local ground-water IIOW'Cel. In the U.S. Virgin lalanda, landfills have been establiabed near the coast on St. Croix and St. Thomas, and contamination of freshwater sources ia not a threat. The landfill on St John, however, ia locat.ed in the in- 11'311' 11'11)' EXPLANATION terior Guinea Gut Basin, where potential for ground- water development exists. IRJUGATION PRACTICES Irrigation of crops occurs primarily in southern Puer- t.o Rico. The basic means of distributing water within cultivat.ed lands is by furrows, although overhead sprinklers are used at some farms in the early months of sugarcane cultivation. Giusti (1971) estimat.ed that ap- proximately 30 percent of the applied water.in the South Cout province (Coamo area) was recharged t.o the aquifer. Bennett (1976) indicat.ed that the ground-water reaervoir in the South Cout province ia "'vertically orient.ed," in that local recharge and dilcbarge tend to be high in any given locality relative t.o lateral ground- water flow. In areas where irrigation water ia derived from wella, recycling of the irrigation water will result in an increue in the dialolved-solida concentration of the ground water. PUERTO RICO ST. THOMAS t. Municipal 91111d _. dilpoeel-- 11"15'311' 11"15' ...... ._ CGJUIP a Id_, Ul- ■afl¢MIII aclll- CULEBRA ,,. .. FJGuu 18.- Sotid-wute di■poal lit.- in the Caribbean llep,n. TUT UOl ~,~U9b 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 hm1 of the 1,500 hm1 in available storage had been withdrawn. The depletion in storage was accompanied by a decline in ground-water levels to below sell level over large areas (pl. 1A ). The chloride concentration in the ground water increased slightly in the more severely depleted areas, but major seawater intrusion did not occur, apparently because of a slight ground-water mound in the coastal areas and the lower hydraulic con- ductivity of the coastal part of the aquifer. Heavy rains later in 1968 recharged the aquifer, but it has never recovered to early 1960 levels. A few areas where ground-water levels were below sea level still persisted in 1976 (pl. lB), but there has been no significant in- crease in chloride concentration indicative of seawater intrusion. OPTIMIZATION OF USE OF WATEll llESOUllCES In general, until recent yean the ~ffort 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 SUJlFACE- AND CJlOUND-WATEJl souaa.s The greatest potential for conjunctive use of surface. and ground-water IOlll'Cell in the Caribbean Region may be on the island of Puerto Rico, where both sources are relatively plentiful Thia 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 hm1/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- tjon 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 NATIJRAL UCHARCE Although aquifers receive recharge by-natural means, it may be practical in some areas to increase this amount artificially. Within urbanized centers the loss of rainfall infiltration capacity may be compensated for by con- struction of infiltration ponds, which may also serve for recreation. Flow into the ponds could be supplied from urban runoff or by pumpage from nearby streams. These infiltration ponds could be situated in the upland coastal areas, where coarse sediments (sand and gravel) predominate and thickness of unsaturated material and therefore storage volume is greatest. Areas of Puerto Rico that could benefit most from such modifications are those zones where urban development has decreased the infiltration capacity of aquifers (essentially the San Juan metropolitan area and Ponce). In the San Juan metropolitan area, possible sites would be the San Sebastian outcrop and areas between the haystack hills (mogotes). At Ponce the most favorable area may be near the foothills, where depth to the water table is bet- ween 15 and 20 m. Infiltration induced by this method may make it feasible to establish and continuously operate public-supply wells within city limits, thus reducing dependence on interbasin water transfer. These well fields would also be invaluable in the event of hurricane damage to centralized water-purification and distribution systems. If the recharged water is destined for domestic use, measures would have to be taken to avoid contamination with toxic substances, which may TUT ;J()l :.>J't / - U30 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES even though ground-water development may be minimal in some areas. Within aquifers for which preliminary areal models have been constructed, monitoring net- works should be maintained to determine whether or not conditions follow those predicted. If significant deviation is detected, the cause can be evaluated and remedial measures can be taken as appropriate. Among the most important needs for improving the knowledge about aquifers in the Caribbean Region are listed as follows: 1. Better definition of conditions within the two major aquifers: knowledge needed about the following: a. Hydrologic relationship between bedrock and alluvium in the South Coast province of Puerto Rico and stream-aquifer interrela- tionships b. Extent of the artesian s~stem in the North Coast province of Puerto Rico c. Ground-water flow within the North Coast province west of Arecibo 2. Areal studies made concerning the following: a. Ground-water flow system in Lajas Valley b. Water-balance for unstudied aquifers in the East Coast, West Coast, and Int.erior pro- vinces c. Water-table monitoring throughout Puerto Rico, the offshore islands, and U.S Virgin Islands d. Qualitative and quantitive assessment of aline- 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 Caril>- bean Region. At present it is unknown if under long- term conditions thick vegetation and plant debris aid ground-water recharge by reducing runoff, enhancing infiltration, and reducing direct evaporation of rainfall or whether they uae more water from the soil through transpiration. Archaeolop:al lites, surface features, and historical notes indicate that water was much more plentiful at now parched areas in Puerto Rico's offshore islands and in the U.S. Vqin Islands. SUMMAlt.Y The Caribbean Region consists of the Commonwealth of Puerto Rico (8,99o km2) and the U.S. Vir.gip Islands (350.Jtm1). It ,a among ttie n,osnlensely populated areas rn-th-e wotld, with au ovetltl population of approxunate- ly 3,200,000 peo_ple. Within the past 25 years the islands nave undergone a rapid transformation from an agriculturally based economy to one dependent on in- dustrial development, tourism, and related services. Water is among the most abundant and valuable natural resources in the Caribbean Region, but its availability varies significantly in both space and time. Rainfall contributes an annual average of 1,800 mm in Puerto Rico and 1,060 mm in the U.S. Virgin Islands. Of this amount, 1,130 mm (or 64 percent) in Puerto Rico and 990 mm (or 93 percent) in the U.S. Virgin Islands is lost to evapotranspiration. The water available for use in liquid form amounts to about 5,400 hm3/yr in Puerto Rico and 24 hm1/vr in the U.S. Virgin Isl1ods These amounts would theoretically satisfy the total water needs of both areas, which are about 919 hm1/yr and 20 hm1/yr, respectively (1975). In reality, most of this flow is contributed by intensive rainstorms and is lost to the ocean as runoff. Potential for retaining a large part of this flow exists on the ialand of Puerto Rico, but present• ly the total usable reservoir storage capacity is only about 230 hm1. In the U.S. Virgin Islands, small dams and ponds have a storage capacity of about 2 bm•. 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 provide 10 percent. Excluding desalinated-water sup- plies in the U.S. Virgin Islands, g'!'.OUJ'!d water rovides t 72 rcent of the freshwa r . 0 the 50 hm1/yr gro -water wi :wal in Puerto Rico, irriga- tion uses 53 percent; industry, 29 percent; and public water supply, 18 percent. In the U.S. Virgin Islands, ground water is withdrawn about equally from private wells and public water-supply wells. Based on past trends and future economic outlook in the region, · estimates are that by 1985 ground-water pumpage in Puerto Rico will be about 426 hm1/yr and in the U.S. Virgin Islands, about 4.5 hm1/yr. This withdrawal is the estimated maximum sustained yield of all aquifers in the U.S. Virgin Islands under natural-recharge conditions. Most large-scale ground-water developments in Puer· to Rico are in the North Coast and South Coast pro- vinces. The North Coast province contains the island'f. most productive aquifer, which has been undergoing rapid development for industrial water supply since 1968, when a major artesian system was tapped. The ex· tent of this artesian system is unknown, but it has been tapped within the lower part of the Cibao Formation (Montebello Limestone Member) and in the upper part of the Lares Limestone. The South Coast province aquifer consists of deep alluvial deposits. It has been ex- tensively developed for irrigation of sugarcane and for industrial water supply. Unlike the north-coast aquifer system, which has large untapped resources, this aquifer · ·· ·1 '._._:'_l_._i')H TUT UU. · - CARIBBEAN REGI01'i U31 will support only minor future development if effective management practices are not introduced. In the U.S. Vir ·n Islands, the most extensive ifer i!,_ igneous roe . t contri utes 1ttle water to wells, but weighed against the costs of desalinated water, its exploitation is feasible for sup- plementing domestic water needs. The most productive aquifer consists of marl and alluvium deposits in central St. Croix. Although this aquifer contributes less than 6.3 Lis to individual wells, it yields about 0.86 hm1/yr to public water-supply wells and about 0.54 hm1/yr to private wells. Future development of this aquifer could probably produce an additional 1.0 hm1/yr. Ground-water resources wilJ 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 llFI.llNCES Acevedo, G., LupLopa., II. A., and Orm-Velez, J., 1959, Occurrence of soil tumon nortbalt of die Guanica Lacoon, Laju Valley, Puerto Rico: Univenity of Puerto Rico Alricultural Station Jour• nal, V. 43, IIO. 2, p, 103-115. Adolphlon, D. G., Seijo, M. A., and Robi1110n. T. M .. 1977, Water raoun:a of Maunabo Valley, Puerto Rico: U.S. Geological Survey Wat.er-Relourtes Investigations 76-115, 44 p. Anders, R. B., 1968, Reconnaiuance of the water raources of the Centn.l Guanajibo Valley, Cabo Rojo, Puerto Rico: U.S. GeokJrical Survey open-file report, 18 p. Anderson, 1976, Ground water in the San Juan metropolitan area, Puerto Rico: U.S. Geological Survey Water-Resources Investiga- tion 41-75, 34 p. --197i, Ground water in ~ Lajas Valltey, Put'rtu ltu:o: L .::s. Geological Survey Water-Resources lnvt"Stiptiun 68-i6, 45 µ. Arnow. T .. and Crooks, J. W., 1960, Public Water supply in Pllt'rtu Rieu: Cummonwalth of Puerto Rico Water-Rt!sourct's Bullt'Lin 2. 34 p. Bennett, G.D., 1972. Ground water along Rio Bucana at Pont"t', Pllt'rto Rieu, and l'fft'Cts of a proposed floodway on ground-water quality: Cummunwealth of Puerto Rieu Water-Resoum,s Bullt'lin 11, 28 p. --1976. Elt-ctrical analog simulation of ~ aquift'rs along tht' south coast of Puerto Rieu: U.S. Geological Survey Opt'n-Filt' Report 76-4, 101 p. Bennett, G. D .. and Giusti, E. V., 1972, Ground watter in tht' Tor- tuguero area, Puerto Rieu. as n!lated to prupoSl'd harbor construc- tion: Cornmunwealth of Puerto Rieu Wat.er-Resourct"S Bulk-tin 10, 25 p. Black, Crow and Eidsness, 1976, A water rnan&gl!ment plan for St. Ill,. Croix, U.S. Virgin Islands: Black, Cn,w and Eidsl'll'SS, Inc .. Cun- T suiting Engineen, Gainsville, Fl. Black and Veatch, 1976, Water supply study fur entire island of Puerto Rieu, fint phase: Black and Veatch Cu11111lting Engineen. Kansas City, Miss. Black and Veatch, Domenech, R. A., and Als<Jciates, 1970, Water resources of Puerw Rieu, phase 11, Ground Wat.er appraisal: Black and Veatch Cunsulting Engineers, Kansas City, Miss., and R. A. Domenech and Auociates, Hato Rey, Puerw Rico. Bogart, D. B., Amuw, T.,and Crwks,J. W., 1964, Watern,suurcauf Puerto Rico, a progress report: Commonwealth of Puerto Rieu Water-Resources Bulletin 4, 102 p. Bonnett, J. A., and Brenes, E. J., 1958. Detailed salinity IIW'Vey of Lajas Valley: University uf Puerto Rieu Agricultural Experimen- tal Station Bulletin 111, 114 p. Briggs, R. P., and Akers, J. P., 1965, Hyd~ map of Puerto Rieu and ad~nt islands: U.S. Geulugical Survt'y Hydrolugic ln- vestiptiuns Atlu HA-197, lcale 1:240,000. Brins, R. P., and Seiders, V. M., 1972, Ge..,lugic map uf ~ Isla dt' Muna Quadrangll', Puerto Rieu: U.S. Geological Survt'y Miscellaneous Geologic lnvntiptions Map I-718, scalte I :20,000. Burus, 0. K., 1976, Wutewat.t-r ~lamatiun project, St. Croix, U.S. Virgin Islands: U.S. Environmental Protection Al(\'ncy, En- vironmental Protection Tt'Chnulugy Series EPA-600/2-76-134. 244 p. Calvnbert. R. J., 1970, Climate uf Puerto Rieu and U.S. Vil'l(in ~ Islands: U.S. l.>epartment uf Cummerce Environmertal Scitel'ICt' Servict'S Administrative Publication 60-52, Silver Spring, Md .. 29 p. Cederstrom, D. J., 1950, ~ and ground-water rnuurces uf St. Croix, Virgin Islands: U.S. GeuK,gical Survtey Wat.er-Supply Paper 1067, 117 p. Cuaner. 0. J., 1972, Water in St. John, U.S. Virgin lslan<4: t.:.S. ~ Geoluteical Survey upen-filt- report, 46 p. Crooks. J. W .. Grossman, I. G., and Buprt, D. B .. 1968. Watt'r n,suurces uf Ult' Guayanilla-Yaucu atta, Puerto Rico: Com- monwealth of Puerto Rieu Water-Resou~ Bulk-tin 5, 55 p. Diaz, J. R., 1968-1!174, Gn,und wat.t-r k-vt'bl in~ suuth coast of Put'r- to Rieu (Guanica tu PatilluJ: U.S. Gtoulutcical Survt'y Uata Rek!ast' PR- I. San Juan, P.R. --1973. Chemical quality of water in Cal'lu Tiburones. Puerto Rieu. A reconnaissance study carried out in 196i: l:.S. Geological Survey open-fill' report (map). 2 p. --11174, Cuastal salinity rttunnai11sancl' and munitorm~ ~ystem - south coast uf Puerto Rieu: lJ .S. GeokJvical Survtey OJ)t'n· Filte Report 74-1, 28 p. UOl REFERENCE NO. 4 - ·1. LJ .. r () () 1 :,::". .1. () (l .L () l .. STO.\'E: .l!ETEOROLOGY or THE r!RCI.V ISLANDS 19 The nature oi the shorter-period pressure variations in relation to the weather and the general circulation are discussed below under The Cpper 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 sugar cane in one or two seasons: a drought oi six or nine consecutiYe 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 = I Tomme (Paris inch) = 27.07 milli- meters= 1.0658 inches. 1 Paris li11c = 2.256 mm= .0888 inch = ~'lu foot, whereas the Danish rVcst Indian (or E11glish) line= 3.175 mm= ¼ 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 haYe 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.• \Ve have already re- ferred to the lack of standards in the instruments and observation pro- cedures at \'irgin 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 bt:fore 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 e,·ening obsen·ation 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 ;i comprthen,1ve discus5ion see Rrool-.:s. C. F., ;\e,ed for univers.al standards for measurin1 precipitation. snowfall. and snowcov~r. Trans. ~leet. Int. Comm. Snow and GJaci~n, IDL Assoc. Hydro!. Bull. 23: pp. I -52. Riga. l 9JB. TUT UOJ 20 SCIENTIFIC SURVEY OF PORTO RICO month's total may result at the same spot between a gage read each morn- ing and a gage read each evening. But it is difficult to estimate the magni- tude of this effect in the Virgin Islands except to say that the results from gages read only in the morning are probably somewhat lower than they would be if read only in the evening. The hours oi observation at the vari- ous stations are not stated or known in many cases and at some stations they were changed from time to time. Rain gages of different diameter and different 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 falsificatiens on the part of ob- servers, which arc 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 aftnual rainfall differs considerably at the various stations, ranging between about 35 and 70 inches. The absolwte 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 I). If we had TUT UUl STONE: records from ea tremes would be inches. A rain far The s,a.sowal • in May or June much more prone on record indicat month ; even Oct tions ( sec TEXT sections of St. C rainfall from no west, but from · middle was agai shift in the relat south of east, wr, peratures and h· graphic effects. E. Taylor in 1888: 42) sugg· J RICO gage read each morn- to estimate the magni- 1 that the results from what lower than they Jbservation at the \'ari- ., and at some stations ..,ht of orifice abo\'e the believed nearl_v all the >een of the standard endix A). The wind l1e rain that should go - 20 per cent too low where with shielded does not average over .veragc from the wind :s r lly equally to _~rlooYed in practical increases as the wind vere storms, hurri- gh wind sometimes of rain. Occasionally ead. Considering all ! the recorded rain- is on the part O f ob- ~uJts and largely • ies and the reputa- >servations as genu- of an efficient na- - o_f inspections by au inspections have 1n ann11a/ rainfall 1ecn about 35 and iest years at these '"tal totals ranging ILE 1 ). H we had I ~ -~.;..:,_ ----··· STONE: METEOROLOGY OF THE VIRGIN ISLANDS 21 )(Ai..( Qt, Wl~(I § J>••o - >O·•., . . [Z] •o••t .. n- •o - 0 .. 1111 •o F1avu: 2. Rainfall map of St. Crob, 1921-JO. (From Sllaw, 1932.) records from eastern St. Croix and from the mountain tops, these ex- tremes would be greater, probably reaching from 1 S to more than 100 inches. A rainfall map of most of St. Croix is shown in FIGUU 2. The seasoftal 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 ninfall from normal- from 1903 to 1908 the middle was drier than the · west. but from 1909 to 191S the middle was wetter, and after 191S 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- TUT UOl ' J 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 foun<I,. 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 prnna11r11t change in the rainfall of St. Croix since 1852. St. John and Tortola ha•.e the most forests at present because they are too mountainous for economi- TExT TABLE 4 FREQl,;ENCY Of lfo:>:TIII.Y R,\1:-IFALL TOTALS G11EATF:R TRAS SPECIFIED A.MOUNTS, ST. Cao1x Average or 3 stations for 6J years, 1852-1914 (From Ravn) :Uoar.11 Number of yean wir.11 miAfall Over lO lines Over4011 ... 0.-er 60 lines (2.50 ill.) (J.00 la.) (7.30 la.) i=, JS l ll 1 lwdl IJ 1 ~ 33 s I 37 14 JI Jue 31 19 9 July ... u l A111111t 50 2l • September S7 ll 10 Octaber 60 31 11 November S,4 30 ll December 39 JI 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 httausc they arc now more forested. Indeed, the rainfall observations ( cf. APPENDIX TABLES 2-6) lend no support to that notion. Orographic Effects The rainfall increases with elevation on all the islands. as residents and travden can readily observe and as one would expect. But rain-gage sta- tions are,Jacking at high elevations, except Pearl, Ma folie. Liliendal, Wint- bcrg, and Dorothea. Shaw's rainfall map (FIGl'RE 2) based on rainfall records (see APPENDIX TABLE 7) of sugar estates on St. Croix leaves no doubt that even moderate elevations are better watered. Yet the rate of in- crease of rainfall with elevation does not here sttm to be as large as in the parts oi Porto Rico where the mountains rise steeply to JOO) feet or more directly in the path of the prevailing winds. Rose suggests that the rain- fall of the islands is not as great as one would expect from the topography because the winds blow mostly parallel to the mountain trends. The reason ,,. {)i.) :L J ( N ~ }-'· Period 1851-61 1161-71 187Z-81t 11111· 9lt IA9Z 1901 1902 II Total Aver■f(e for 60 yurs (1151-1911) TEXT TABLES AVHAGE RAINf'AI.L rn11 EAcu 10-Yua PE1100, JSSZ-1911 (IN INCllt:s)• .... - > % ~ i5.. -. --I g ~ 0 --, "' ::i ;,;-~'8 g ~ ;::i ; ~ ."'. 1") ;,--'"" ~ I', ,,. :1 ,,, ;, 11 •; ',· ,,. II· '' •f• !'/ /1 i~ '• ,. I , .. 'I V "St. Croix, Virgin Islands"= (01ristianstcd's Fort+ Kings II ill• + Fu·ckri<-k,11-,1', Furl )/.I (From L. Smith) ·-·--·-- ·- ·------- Jan. Ftb. llar. Apr. .... , June July Au1. Sept. Ocl. Nov . Dec. Yrar 1.90 1.60 1.68 l.ll 5.SJ 3.76 J.51 4.91 7.16 8.16 4.43 l.68 1.11 1.65 Z.16 1.06 l.15 l.86 J.10. 4.18 5.16 7.80 4.07 l.40 285 I.JJ 1.57 1.43 ◄.16 4.41 J.37 4.ZS 5.11 5.11 6.61 l.ll :.78 Z 10 I.IS l.17 J.ll l.97 4.06 4.61 4.91 7.50 S.91 J.67 Z.16 1.45 I.JZ Z.15 6 Jj 4 60 5.41 4.58 6.81 5.47 5 46 4.08 l.Sl Z.ll 1.11 z.sz 4.16 l.40 Z.47 5.40 6.91 4.61 4.96 s.os ----- 14.ll 11.45 10.ll 15.57 16.90 14.0I Zl.95 11.11 36.45 J9.J8 ll.45 11.21 181.JS Z.JI 1.91 1.10 l.60 4.47 4.01 J.65 4.70 6.07 6.S6 5.23 J.SJ 46.89 --- ---- ----··----- • Th..,... 1n, lrom the s■me ob..-rv■tlons used la TIXT TAILU 19 to ll, here converted to Inclan from lhe "lines" in which rainfall was meuured (I lines= I Inch). From "Reioorts of the Vir1in Islands t:1periment S11tlon, 1911 ". t Kinp Hill was omitted hum the avera,es lot Oct. 1171 to Oct. lllll, lnduslve. \ i l I I -::.• .. .;.., . . ·.st.,.WS oe;~ril; ''-1 ·:. 24 SCIENTIFIC SURVEY OF PORTO RICO for this may also be contained in some observations of the writer: on sev- eral occasions during his stay at St. Thomas in June, 1939 when the sum- mit of the island ( I 800 ieet) was visited, he noticed that any large cumulo- nimbus cloud that had been initiated by forced ascent of the wind over the island would lean to the leeward so that most of the rain falling from it would fall on the ocean surface somewhat to the lee of the island. In other words the orographic influence on the rainfall was not fully enjoyed by the island itself owing to its small size and narrow form. This observation is confirmed (oral communication) by Sergeant Davidovic, the Aerographer stationed at the U.S. Marine Corps Fleet Air Base on St. Thomas in 1939. In general the annual 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 sea.sons. 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 ~!~, o_~_E_f Chrj_~~~~nsted, ~overage anm1at ri.infall probably varies considerably ( up to 5 inches?) from block to block; hence records taken at differcnfspots 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 (ncuu 2) is based on a homogeneous though short (10 years) series of 26 records from the Batter 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 Is characteristic of the frequency distribution of either daily, monthly or -aal -raiafalh, that the fflOfl frequent •alue (Mod•) it ceneralty mucb leu than the &Yff81'e, and in - C&N9 the zero nlue is moet frequent. STO.VE: .\IE. cane, long the chief en discusses this problem low). Du Tertre and C the poor crops of UH: 1923 to 1924 were du trary to the impressic evidence that the rain to century (see Fores has not been scientifi, show long quasi-peri( rainfall. These un<lot1 enough to reveal any 1 near the critical limit i tuations are important understanding of the for the farmers mere!) attempts to forecast f derived from analysis for long-range foreca solutions offered do nc plicability, however p1 The most successful r places, none of which I The diurnal distribt greater amount of rai1 loe's observations at , Tidende'', 1888. He gi NIGHT AND Moatb (1811) • In lilla; I Jin The frequency of r. is probably not so pro1 heavier. i:)Ol ~? i. t) ./ -o RICO ns of the writer: on sev- 1ne, 1939 when the sum- i that any large cumulo- ~nt of the wind over the the rain falling from it ! of the island. In other 1ot fully enjoyed bv the >rm. This obsernti~n is idovic. the Aerographer :>n St. Thomas in 1939. ,crease more than about 1, but some of the lower e leeward slopes or in mon Bay, or Barracks E 2). In generally rainy 1tio f different ele- 1s. '------ h Bay three rain gages from the water to the :rease in rainfall (AP- ' although they are all ow sensitive the rain- ason, within the hilly ,erage annual rain fall n block to block ; hence lt justifiably be com- els of an estate often Caroline; Adrian, Su- s of St. Thomas and ~s. Shaw's map of St. ugh short (10 years) d, which should give ,me economic consc- ,all is well below the annual yield of sugar >nthlJ or anauaJ rainfallo, ace, and ia -• ca1ea the STONE: METEOROLOGY OF THE VIRGIN ISLANDS 25 cane, long the chief crop, and the cane yield suffers accordingly ( Dr. Shaw discusses this problem with respect to St. Croix, in paragraphs quoted be- low). Du Tertre and Oldendorp mention great droughts in 1661 and 1753; the poor crops of 1841, 186..J., 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 oi many residents and travelers, there is no real evidence that the rainfall is slowly and steadily decreasing from century to century ( sec 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 arc 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 rainfal_l 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 arc 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. TuTTilU6 N1GBT AND DAY RAINFALL, CeAE.OTTS Ax.u.m, 1888* Malla (1111) Tola! JS.4 77.Z 69.0 • In lines; I llaes = l iacla. ., .. ,. 26.1 JU 44.6 ., ..... , 11.6 21.J 24.4 The frequency of rain is no doubt also greater by day but the contrast is probably not so pronounced because the intensity of the day showers is heavier. ("1() i. . t .,;'iOH 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.:\I. The amplitude of this daily variation is pre- sumably smaller than the one observed oYer 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. No hourly observations are available from the islands but the sunrise shower seems to be recognized by the residents as a more or less regular phenomenon. The daily double period in the rainfall is of course reflected in the cloudiness (TEXT TABLE 17) and in the frequency of thunderstorms. Intensity and Frequency The rainfall in this low latitude and oceanic situation is entirely of the shower type, and therefore it is of great practical importance to know how frequently showers occur, how long they last, how much rain falls per shower, and what are the average and maximum rates of fall over short periods of time. Unfortunately systematic observations using recording rain gages were begun in the islands only very recently, so we are forced to infer much from the usual rainfall observations which give only monthlv totals and numbers of rainy days. The average rainfall per rain <lay (A~PENDIX TABLES 10 and 1.2; FIGURE 10) indicates some important characteristics. The "showers" of the winter and spring seasons are characteristically brief and light, often mere sprinkles, from cumulus clouds of small or moderate size and spaced by large intervals of blue sky (cf. TEXT TABLE 9). Sometimes "norther" effects cause a low overcast cloud deck with driz- zling rain punctuated by occasional heavier showers, which condition may persist a day or two. However, yery heavy rains UP tg 2 or 3 iocbcs io a dav have fallen even Tn the driest months. In the "rainy season", from • lay to ov vier and more enduring showers · or t under and lightning at times, are to be expected roucb more often· a.t least one shower of some sort then falls almost every day. Heavy rains lasting as much u 6 or 8 hours, even with hrief intermissions, are normally very rare, but passage of a hurricane within _5_Q_.9.!"_l@.miles caa cause ennr. mous rainfall totals ! over) 0 ingjesDuda;y ar tw.o £rem yit1na1J1 coo- gnuous downooun1 The high wind during hurricane weather adds greatly to the destructi,·e 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 TUT STO."f\'E: .\IETEOROi gage has been operated since TABLE 12 and FIGUllE 10) ind and also per rain hour for eac fall during any 24 hours of ti teresting relation because in t places we can assume that tb tabulated by the U.S. \Veath basis for estimating the a1.•cra! Since February 1940. the S, rainfall rates monthly from re estates on St. Croix. An abstr and 8. Although the period of averages or extremes likely to study of the tables re~eals a _cl rainfall and the maximum m1 the average intensities. This i showers probably have more numerous lighter showers. T average intensity to be great months. It will be noted, howt months appears to be as higl whereas the total rainfall is t· the spring. This is a curious the greater frequency of hail the late summer and·autumn.' tensity of rainfall will act~ll because of hurricanes. The irr excluded, winter and spring ~ tensity as the autumn rains, bt riods. as shown in TEXT TA~L 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 001 Any practical interpretatic Virgin Islands, especially on that a large proportion of the 1 (seeTEXTTABLES9and 10).? rain gages and they augment significance for crop growth ,/1.()'1 r- PORTO RICO 1u":1 at_6 A.~r. with a secondary ,e 01 th'.s <la1ly variation is pre- .-.:r the islands, where the maxi- kely that the sea maximum at shoreward margins, causing a •urly obsen·ations are available ,eems to be recognized bv the ,enon. The daily double ~riod Ioudiness (TEXT TABLE 17) and quency nic situation is entirely of the . .;tical importance to know how 1~st, ""lw much rain falls per •m\. __ .-ates of fall over short obsen:ations using recording ·ery recently, so we are forced '>servations which give only The average rainfall per rain lO) indicates some important seasons are characteristicallv · cumulus clouds of small ~r . of blue sky (cf. TEXT TABLE ivercast cloud deck with driz- iowers. which condition mav rains up to 2 or 3 inches in ~ 'n the "rainy season", from ng showers. with squalls or ;peered much more often; at n_o_st eYery day. Heavy rains · intermissions. are normaIJv or 100 miles can cause en0 ;_ _\" or two from virtually con- ·ricane weather adds greatly from the results of the re- , the~- have been in use. 5t. Thomas a recording rain STONE: JfETEOROLOGY OF THE VIRGIN ISLANDS 27 gage has been operated since 1935. An analysis of the results (ArrEso1x 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. \Veather Bureau for all its stations. gives a rough basis for estimating the a,:eragc 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 arc 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 in the late summer and-autumn. Over a period of many years the average in- tensity of rainfall will actually be greatest in the autumn or late summer because of hurricanes. The important conclusion is that, if hurricanes are excluded, winter and spring showers probably have as great average in- tensity as the autumn rains, but the 1na.rimum rates of rainfall in short pe- riods, as shown in TEXT TABLES 7 and 8, arc 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 ii IT UO:l. - .. ~-.-~: -·~--~ 28 SCIENTIFIC SURVEY OF PORTO RICO Tu.T TABUt 7 RAINFALL INTENSITIES MEASUllJI AT SunoN SCS No. 18 F. S. A., ]OLLY H1u. ESTATE, ST. Cao1x, V. I. (From U.S. Soil Conservation Service) ---------- - ---- Total Tot&I Av.rap Muimum loteasit:, for Different lalerftll Rainfall, DllnltioD, lntemit:,, Month inches houn• in.1br. 5-miD. 10-min. 20-min. 60-mia. 120-miD. -·- ---· -------- 1940 February 0.90 IS.02 0.06 1.00 0.7S 0.35 0.13 llarcb 0.52 1.92 0.21 April 1.97 6.42 0.31 2.00 I.SO o.ao 0.50 May 7.10 30.00 0.24 3.50 Z.00 1.40 1.10 June 3.05 6.10 0.31 2.00 1.50 0.90 o.ss July 2.14 S.07 0.42 s.oo 3.50 2.SO 1.lO A111u.t 3.05 12.37 O.JS J.00 1.75 0.95 0.30 Sei>tember 4.19 12.65 0.33 7.00 5.00 J.40 1.40 October 7.47 22.45 0.33 4.50 2.75 2.SO 1.70 November 7.15 25.37 0.21 5.00 J.SO 2.40 1.45 December J.47 20.25 0.17 l.SO 2.25 l.60 o.as 1941 t~ 1.91 S.02 O.J9 2.00 l.7S 0.90 0.40 0.21 O.IO 0.26 Man:b 1.JJ 1.13 1.17 1.50 1.00 o.so 0.11 April 2.21 9.45 0.24 J.15 uo 1.40 0.56 • latmtiU.. of•- tbaD 0.10 ia./hr. are DOt llldaded. T&XTT.UU8 RAINFALL IN-r&Mstrml MEAIUUD AT STATION SCS No. 15 F. S. A., ANNA'S Hon EstATS, St. Caorx, V. I. (From U.S. Soil Conservation Service) 0.21 0.70 0.30 0.65 O.IS 0.75 I.OS 0.90 0.45 0.20 0.30 Total Total Awn,e Mazlmum lateuit:, far D'-'-t laurwall Jta.iafall, lntlmit:,, Month iacllea Duration, boun• in.;br. 5-mia. 10-mia. 20-mia. 60-miD. 120-mla. 1940 , .. \IVY G.JS 2.77 o.u - - - 1.0, 17.ll o.u uo 1.2S 0.1S 0.30 0.11 ~ 0.99 4.92 o.zo 1.00 0.7S O.JS o.u ~ l.SS 4.ZO 0.37 $.SO l.75 l.%0 O.IO 0.41 I.II IS.OS 0.19 z.oo 1.50 O.IO 0.40 o.u June l.56 4.60 0.34 3.00 J.JS 1.l0 0.40 o.zo Jal7 1.17 4.23 0.21 1.00 0.7S O.JS o.u A..- l.7S 7.41 0.23 J.00 1.00 O.IO O.JO 0.15 SeptMDlllr S.J4 6.67 0.11 7.00 5.00 4.10 1.30 1.11 OWlber 1.43 22.05 O.JI 4.00 .s.oo 1.00 O.IO 0.50 No,,ember 6.05 14.67 0.41 7.00 5.50 l.30 1.10 0.60 December 2.36 14.10 0.17 1.50 1.00 0.4S 0.11 1941 4.00 2.50 l.60 0.60 O.JI i=,. 3.67 12.25 0.30 0.19 l.SO O.OI - - J.larcll I.OS Ul O.l7 1.50 1.00 0.50 O.JO 0.15 April 2.41 7.25 O.J4 4.00 3.00 2.60 0.92 0.41 • lntc11sitia of 1- than 0.10 in./hr. are not Included. TUT U0.1 1 i STONE: METI the vegetation and the · quickly evaporated by tl PEllCENT AGES OF CBJ (Fr --7---=-=- _7 _ __::.:-_:=--_ Moath tuuary ebruary Marcb = Jwie Jul, A~ ~ NOYnnber December Yar AVUAC:.E AND ExTRE: )loath Yeu • n- ficuret are not sums < ,-r iD the period covend by th~ :~1.11 r: I j; I ti I I' ' ll r ' .. ' ... . \.. ·- .. - ~.,;.,., rtr:t).· JO SCIE.VT/FIC SC.:Rf'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 c1:aporati11g poa•cr of the air made at the Experiment Station (see APPE:-.01x TABLE 8). Consequently, the roughly 45 inches of measured average annual rainfall in the Virgin Islands is hy no means the equivalent for plant growth of 45 inches of measured pre- cipitation in rainier parts of the \Vest Indies or in the southern United States. Thunderstorms, Squalls, and Hail Tliu11derstorms occur, as in Porto Rico, chiefly from July to October, according to the records at Christiansted and Bourne Field (TEXT TABLE I 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. S quails are sometimes associated with heavy showers and probably with most thunderstorms. The familiar downrush of cold air under a thunder- storm or tall cumulonimbus cloud can be so violent as to capsize small boats and damage dwellings, trees, and crops. When the observer is located on the sunny side of the cloud. it may appear white until after the squalls reach him, giving rise to the term "white squall" of the West Indian na- tives; but when the observer is under or on the shaded side of the cloud. it appears very dark and ominous. so the accompanying gusts are called "black squalls". White squalls are also reported without heavy clouds nearby, but these are merely gusts when the trades are blowing strongly. The West Indian sailor well knows that the squalls are apt to be especially \iolent and dangerous to boats along a coast which rises to high mountains immediately back of the shore. Hail is rarely reported and most residents spend a Ii fetime 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. l\Iuch hail, with cold and rainy weather, occurred in Virgin Gorda in January 1833. according to Schom- hurgk, who also wrote of hail on the north side of Tortola in November 1829. Knox mentions that hail as big as hen eggs fell in St. Croix on April 13, 1844; and that a Mr. :Kissen told him of a hailstorm at St. ruT UUl STONE: ME.Tl Thomas on May 13, 18. St. Thomas in 1938. Alt early summer, the cases tcr and spring; perhap! thus more likely to be re Chemical analyses of Station from 1911 to 1~ tained an average of 5- nitrogen in the form of These figures varied g: The amounts do not see appear to depend on th that they are ttlated to These chemical constit- .soil and the nourishmer ~ Owing to the small at ration, and the few pe: obtain domestic water : and stored in cisterns, a cretc to catch rain for strict economy in use o · Shallow dug wells an pumped for Rushing 1 stocked with "mosquit spread chiefly by mosc of La Grange plantatio St. Croix was started but not on a scale suffic not yet been tried. Stor on which it was used fc Temperatures in th Porto Rican stations 4 small land area availal '?/CO r. Cao1x, V. I. :) for Dilfereot lotervals min. 60-min. 120-mio. ' JS 0.IJ - !O o.so 0.28 .·o 1.10 ,.90 o.ss 0.70 O.JO ,o I.JO 0.65 ,5 0.JO 0.15 0 1.40 0.75 0 1.70 I.OS 0 1.45 0.90 .60 O.IS 0.45 --~ 0.20 l 0.11 40 0.56 0.JO . Caorx, V. I. Dilfemit latervall n. 60-min. 120-mia, ----- - - O.JO 0.11 0.IJ - O.IO 0.4J 0.40 0.25 0.40 0.20 0.IJ O.JO 0.15 Z.JO I.II O.IO 0.50 I.IO 0.60 0.11 0.60 O.JI - - 0.20 0.15 0.92 0.41 - STONE: METEOROLOGY OF THE VIRGIN ISLANDS 29 the vegetation and the top of the soil and do not sink into it, and so are quickly evaporated by the sun and wind. TEXT TABU:9 PnaNTAGl.5 OF DAYS WITH SPECinED AMOUNTS OF RAINFALL. CHIUSTIANSTED, ST. CROIX, 1852-1907 (From Willaume-Jantzen and Ravn) - ~ 20mm i:_SO- 0-5 mm 70.19• (l.97· Month (0-0.20#) or more) arm«e) January 67 5 0 February 64 J 0 March 66 4 0 ~ril 55 16 2 56 10 4 .,. June 46 14 J July 55 10 2 Alllllll 54 11- 4 September 45 15 4 October 44 II 7 NOfflllber 41 12 J December 52 • 2 y., 54 11 J TuTT.uulO AVEaAGE AND ExnulE NUMBERS or DAYS WITH RAIN, CHRISTlANSTED, ST. Caorx, 1852-1907 (From Willaume-Jantzen) Bllbat 1--1 Month Meu laany-yar 1a .. ,._,._ r=,. 11 20 2 9 23 l Maida 6 14 0 ~ 7 I.S 2 11 Z6 J Juae 10 20 4 July 11 17 4 AQIUl 11 17 4 Seplniber IJ 19 6 Occober 12 19 6 NOftlllber 14 20 4 December 1J 19 6 y., 121 177• .... • Tb- 6,ura are not sums of the columns above, bat are the atreme totala oa 1-.1 far u:,- - yar la the period covered b:,- the table. . .? .L l ::: ~- '9 1 - TUl 001 2114 r ] . ' CLIMATOGRAPHY OF THE UNITED STATES NO. 60 Climate of Puerto Rico and Virgin Islands :::::::::::::::::::::::::::::::::::::::::::: :::::::::: ::::::::: :::::::::::::::::::::::::::::::::::::::::::::::::::::::: ............................ 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I!! llli!illiliil 1111 iiilliiliiiiii!~~=- : : : : : : : : :: : :::::::::::::;: ::::: ::: : : :: : : :: : : : : : :: : : : :: : : : : : : : : : : : : : : : : : : : : : : :: : : : ::::: 7 : : : : : : : : : : : : : : : =~: :r::: :! : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : "J' ·····································································... ··········••.T ::::::::::::::::::::::::::::::::::::::::::::::::::::==-~ ~·~:::;: ✓ ................................................... ~ ~ ::::: :: ::: ::::::::::::::::::: :::::::: :::: ::? , ~; ~ ~ ~ ~; ~ ~ ~ ~ ~ ~ ~ g ~ m~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~;;;, ····································•· I I I I! I~- .......... y y~✓ noaa NATIONAL OCEANIC ANO / ENVIRONMENTAL/ NATIONAL CLIMATIC: CENTER ATMOSPHERIC ADMINISTRATION DATA SERVICE ASHEVILLE, N.C. REPRINTED JUNE 1982 TUT UUl .,·1_;_'.j • 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 S111.all. It varies from 9.1° at Charlotte Amalie to 15.1°F at Wintberg. For these same reasons extremes of temperature are not as great as they are in Puerto Rico, and relatively few days have temperatures of 90° For above. Since the extent of land areas is small, the air passage over land is quite short and there is not sufficient time for extreme heating to take place. On St. Croix, Annas Hope has had a temperature as high as 99° F. During the warmest months, maximum temperatures average about 87° to 89° F, with nighttime temperatures falling to about 74° to 78° F, and a little lower at the higher elevations. In the winter, daily maximum temperatures are generally in the low 80's and nighttime minima in the high 60's or low 70's. The highest mean maximum temperatures are found in August, while the lowest mean maxima fall either in January or February. The lowest mean minimum temperatures are observed in January and February, and the highest mean minimum temperatures are generally in July or August. DROUGHT - Drought in the Virgin Islands occurs about as often and is just as damaging as it is in Puerto Rico. None of the three islands has any significant running rivers or streams and only St. Croix has an u~derground water source in a few sections. Water for irrigation is not available in quantity at any time. Large storage reservoirs do not exist so the Virgin Islands are, to some extent, more at the mercy of "Mother Nature" than is Puerto Rico where there are adequate facilities for water storage. HAIL - In the U. S. Virgin Islands, hail is even less frequent than in Puerto Rico. In January of 1969 a severe local hailstorm with hailstones up to 1 1/2 inches in diameter occurred. Thia was the first hailstorm on record in the U.S. Virgin Islands. 20 r\J-\ ------ ----- Orogry,hic lifting of the_ ture laden air over the hilly terrain of these islands is the most frequent cause of ran~ • However, due to the smaller~leoations 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, 40 and 60 inches a e. On St. a more noticeable var a on from place This greatest annual rainfall, in excess of in the northwestern corner. There are some indications that stations in a small area along the central portion of the southern coast of St. Croix receive about 40 to 45 inches. A narrow. finger of between 25 and 35 inches extends northeast to southwest over the flatlands south of the hills in the western portion of the Island. Annual rainfall averages less than 30 inches in the eastern end of St. Croix, possibly as low as 20 inches. As in Puerto Rico, there is no sharply defined vet-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 daya with measurable rainfall over the Virgin Islands, baaed 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 days annually at the stations with lowest rainfall. As in Puerto Rico, one of the most strikina fea~urea 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 64°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°4l'N, and longitudes 64°54'W and 64°34'W. The Island extends some 19 miles from east to west and 6 miles from north to south. Topography: St. Thomae b•• ag__ extremely irregular-5:~~~tJine and is very hilly with practically no flatland. The highest hills are generally ·-found near--th~enter of the Island, with Crown Mountain at 1,550 feet the highest point. The Island is relatively 911lall and many of the peaks rise above 1,000 feet. Du• results in rather steep slopes over all the island, so that rainfall runoff is quite raid and there are no ~r- manent a Like St. Th011L&s, 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 - • 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. ~. 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 alopu 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 uaed as a catchment area. On St. Th011aa and St. John it is common to see the entire side of a hill cemented to act as a catchment area. Generally, during the drier portion of the year, it is necessary to carry water by barge from Puerto Rico. Installation of a sea-water distillation unit on St. Th011&8 and St. Croix has helped alleviate the water shortage but water still raains a significant factor in the development of the island's ecQDOlly. Rainfall in·th• U. s. Virgin Islands is of the same nature as that in Puerto Rico, falling moat 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 ~u, 001 !119 REFERENCE NO. 6 t ' • . TAT-02-P-04642 W1'0 WELL SITE POTABLE WATER ALTERNATIVES REPORT AllMA' S RETREAT, ST. THOMAS, U.S. VIRGDI ISIAHOS Prepared Por: carlo• I. O'Neill, P.B. osc Luis•· Santos, osc Air and Bazardoua SUbatance Staff caribbean Field Office U.S. IPA, Region II Santurce, Puerto Rico and Bruce SpraCJUe, Chief Incident Reaponae and Prevention Section U.S. UA, Region II Bdison, • ., Jersey 08137 Prepared By: Rodolfo Hafner, TAT II Juu ll&nfreda, TAT II Region II Technical Aaaiatance T- Weston/SPD Division Zdiaon, Ne11 Jersey 01137 December 1988 TU\ 1 appear to be sufficient land available to increase the cistern volUJ1es laterally. The only way the volUJ1e could be increased is by aaking deeper cisterns. This operation would require the shoring of the existing hoaes and apartaenta, therefore, the po■si.bilty of atructural da .. ge to th••• reaidenc••• 2.0 SID PISCRIPfiQN MP CQIQITXQIS 2.1 site Background ID4 condition• The TUtu Well site ia located at the eastem end of the Island at the Anna's Retreat Section of St. Tboaas <••• Figure 2-1 page 5). Nost of the well• are used tor public drinking water supply. Tb• wells appear to be drilled into the Turpentine Run aquifer. on, or about July 7, 1917, Jlr. Eric Tillett, contacted the o.s. Virgin Islands (U.s.v.I.) Deparaent of Planning and Natural Resources (DPIIR) regarding an odor -■anating fro■ the raw well water on his property located at Anna'• Retreat, st. Thoaas, o.s.v.I. on July 16, 1987, the OSIPA received a request froa the DPNR in st. Thous, tor saapling and analys- of several Vella in TUtu. On July 21, th• USZPA and ita Technical Assistance Tm (TAT) contractor, JloJ P. Weston, Inc., aobiliaed to St. '?boaas, to perfors ... pling on the drinltincJ water wells auspected of being contaainated. Th••• vell• vere also reported to have a strong, unpleasant odor and were found to be contaainated with hazardous aubstances. Tb• DA and ita Technical Aa•i•tance T••· (TAT) in coordination vith DPIIR, initiated aaapling of wells in the affected area in July 1917. ft• tut re■ulta shoved the presence of high concentrations of gasoline and chlorinated organic coapounda. Pour wells: El9in, Pour Winds, Rartlulan, and Virgin Islands Housing Authority (VIJIA) were closed dovn by order ot DPNR due to high voe concentrations. Several of the wells in this area are aajor co-•rcial well services used for public drinking vater supply, therefore, the incident vas classified•• aajor, and the DPNR co-issioner requested the EPA to assWN the role of Lead Agency. Tb• well locations can be seen in Figure 2-2 page,. A Texaco station, located opposite the Tillet Well, 1• suspected as a possible source of contaaination. A Petrotight test conducted on the underground storage tanks at this facility indicated leaks in two of the three tanks. Th••• failures .. y have contributed GREAT_,) N_ORTB~ SIDE ~ 0'11!:ILL ,. ... - } \ NO. WE!.L N~\!E NO. J UY.l."'fS 1 .. ' -· " 'IL"fDS l a IODIIC:zES 14 % "'IINDS z I i..1 ~IADRY 1i..1 '91IU .I I l :u a.umDUN 8.llEP.Y l:U vtlt,L 2 I i.3 IWt'J'BJiUH 8.\UllY .1i.3 VDU3 I f..l GENE ECUH J 1i., '91IU ' u GENE ICUN 2 H aSA LlltfWID f..3 Ca:-IE £CUN 3 !5 DDOTRI 5 B.Lavr.-5 !I DCfC'K I I I ~'S :~.l DEYC::>N 1 j ., M.\~"S 1-., DEYCOH 2 ·- • swmrs J~.3 DEVc:>H 3 • FIWIC:>19 11 DEDI JO 'TU.LE'n JI LOCDA&T u L\MSEr"S _RED BOOK FR~CmLA.NS 3AY tyy;-;-~ ~~EVl.-.nQNI IPAN ~~k.l 2-2 \M..~~ !ME.=IGiNCf ~£91:NSI OMSICH - OJU.QS 0 'n::.:. ~ L0c:A1'I011' JIU 1------........ ---~~--::=;;;;;:-+--------~~ ST. 'rBCMU ... '-==·-=,.. -a &0T..:118GMG' &-.. c.~;o,.-.a.\a I ca.. TAT"' In -!I_ vnc;m ISUKC 1-.. a-,n •'n•-=-- rac.. ~ lleowft~ s-. U1U """_,.__ '.'!:"Ucaiuc,> ,....,_..__ lac. Jt • KAnU TU ·i () U J 2 J ./ ,:1 --------------------.--------- to the groundwater pollution probl-, resulting in th• contamination ot nearby v•lls. Another suspect•d source ot contaaination is the Tutu Easo gas station. This facility storu vast• oil in an underground storage tank. Tb• facility has had probleas in the past vith lea.Jcage fro■ their underground gasoline atorage tank and i• auapected ot using aolventa in the Mchanic abop. At the ti.lie of inapection, th• nature of the probl• bad not been cteterained. Both the Texaco and Easo gas stations are upgradient fro■ the affected vella vb.icb are beinq aupplied vitb vater. EPA continued ita etforta tovarda tb• identification of; affected wells in the area, cuatoaen vbich had received vatar froa conta.ainated wells, and possible alternate vater supplies and reaedial action alternativu. A testing prograa of vells located outaid• of the Jcnovn area of conta■ination vas conducted to evaluate tboae areas as possible alternate water supply sources. Sampling of cisterns served by the conta■inated wells vas also performed. EPA directed the Dlerqency Response Cleanup Services contractor (DCS) toi clean and disinfect the five (5) cisterns which bad tutad positive for ,a, aodity the exiating boaa plmlbing, diacoMect the contaainated vella, and dispose of the contaainated water. At ZPA'• direction, DCS also contracted a local water bauler to daliver unconta■inated drinltinq water to th• cistama by tank truck. A vell saaplinq prograa vaa ••tablisb.ed by tile EPA to aonitor the vella at th• TUtu sit• for a on• year period. Mine potential responsible parti .. bave been identiti-4. Thu• facilities included three qasolin• aervice stations, two vehicle aaintenanc• repair shops, tvo territorial qovermNtnt aqanci .. , one dry cleaner and one abandoned gasoline service station. EPA has identified Texaco as a vial:>l• potentially responaU,le party, based on the results of a soil/gas survey conducted on the Texaco Property under order fro■ DPNR and under the supervision of ZPA. Tb• survey found total hydrocarbon concentration• up to 690 pp■ ot benzene. EPA is continuing its efforts to identify potential responsible parties. 2.2 Topography and ;.o1oqy.ill. •st. Tho■as is the aoat northveat island of the u.s. Virgin Islands and the second largest. The island 1• approxi■ately 14 ail•• long and 2 to 3 ■ilea vid• and has an area of 32 square ail••· 7 TUT OUl 21.2'.c.i Th• land surface i• alaost entirely sloping and extenc ••award fro■ a central ridge, 800 to 1,200 feet high, running the length of the island. The slopes, which co-only exceed 35 degrees, are dissected by nU11er0us atre .. courses of steep gradient. The general appearance i• a panorau of steep interatreaa apura an rounded peau. Flat inland is confined to the aiarlotte Aaali• area and a few ... 11 alluvial-filled eabayaenta. 'ftl• only variation in the 9eneral topography ia in the upper valley of Turpentine Run in eastern St. 'l'ho■aa. 'ftle valley baa relatively gentle topography conaiatinq ot rolling hill• in a basin surrounded by ateep slope• and sharp ridcJ ... 'ftle TUtu Formation, the )'OWICJ .. t rock exposed on St. 'ftlo■as ia coaposed al■ost entirely ot aJ19Ular debris derived froa the Louisenhoj Poaatton (an older volcanic formation) and ainor 11.Jleatone debris fro■ thin limestone deposited cont-poraneously with the TUtu Poaation. The rocks var• subsequently tilted to fora a northvard- dipping homocline. Dip• range fro■ 15 to 90 degr••• and avera9e about 50 degr .. s. Locally th• for.ationa are overturned. 'ftle per.-abl• son .. that th-• rocJta once -Y have bad after deposition have been •••troyed by •taaorpbi• or by deposition of ainerals in pore spaces. Groundwater aov-•nt ia nov liaited to openinga along jointa and fault zone•. Th• ho■oclinal atru~ i• cut by -ts of faults trencU.JICJ II 45•w, If ss•z and north. Tbr .. well-defined joint ••ta parallel ••cb ot the ■ajor fault directions. Th• valleys of the island have siailar trend• and are apparently th• result of selective erosion of roc:Jc weakened by faulting and jointing. Pri.Jle zon•• of groundwater availability, therefore, follow the valleys. Baall alluvial deposits ranqing fro■ Pleistocene to Holocene in age, lie in the valley of Turpentine Run in -•t-cantral St. Tboaa• and the larger coastal eabayaanta. Tbe alluviua of TUrpentin• Run li•• in a narrow band ••ldo■ ■ore than 200 feet in width along the strea■• llaxillua thickn .. a of the alluviua i• about 40 f-t. No•t of the alluviua, which i• coapoaed of silt, tine sand, and clay and contains di•continuoua beds of ■and and gravel 2 to 3 feet thick: lies in the Nt. Zion-TUtu area of the upper basin and in the narrow valley fro■ Nariendal to Mangrove Lagoon in the lover basin. The alluviU11 extends out under the lagoon n .. r the ■outh of Turpentine Run. Althougb co■posed predo•inately of fine-grained ■aterial, the alluviua readily infiltratu 8 () 1.·_; :L ,:'.i:?b 2.3 streamtlow when the groundwater level is below the base of the stream. As such, the alluviwa forms a readily rechargeable aquifer, although it is of small extent and yield. So•• coastal eabayaant• beaded by interaittant atr .... contain aall depoaita of alluvi1111 aiailar to that of Turpentine Run. NaxilllDI tbiclm-• of tb ... depoait• 1• estiaated to be 50 fHt, and tbeir areal eztent ••ldo■ is greater tban a fev acres (an exception being tbe Long Bay and Airport area• near Charlotta balie). Near the sea, tb• alluvi1111 interfingera vitb calcareous aand and at tiaea containa lena•• of aanqrove avaap deposits. Therefore, tbe deposit•<tf• of ■inor significance•• source• of vatar•. Rainfa11ill •Rain is the only natural source of fresh water to replenish tbe water resources of tbe island. RaintaJ is seasonal, with a rainy aeaaon in late ■WIiier and early tall and a secondary vet season usually in Nay. Nearly half the rain falls during August-November. R4.!_ns exceeding 1 inch in 2! ~:r: c::? •!! ~= ::"!~ t.,i••• a_year. Fo:ur to 1 • il~cz -- _ f --" __ 1 _____ A hour p•~ AQOYt gnee every 2 Y~• in large stoma, Th••• ra can occur In any aon , but are aora lilca during the hurricane ... aon (Auguat-•ovallber) • About ~o ~rcent of tb• tiae annual ratnfall 1• between 40 50 c::ii••· Li•• than 10 perc:.nt of tbe tiae annual rainfall ia under 35 inch-, vbich uaually ..an■ a ■ajor deficiency during the nonaal vet season and drought. Th• cmaulative departure fro■ average and the 10-year running average of rainfall abova that at tbia tiae of writing (19&7) the island ■ay be entering a period of deficient rainfall. Witb tbe exception of a fev years in tbe late 1940'• and early 1950'•, rainfall in the past 30 years has been below average. There baa been a long-ter11 decline of about 10 inch•• in annual rainfall since the peak of the surplu■ rainfall period in th• early 1930'•· The ■oat severe droughts on record occcurred in 1964 and 19&7, when only 27 and 24 inches o~ rain tall, respectively. Areal distribution of long-tena rainfall, i• controlled by topography and the prevailing easterly to northeasterly winds. Bovever, individual storaa ■ay or ■ay not show the effects of orographic control or prevailing winds and the arealc!t•tribution of the stonas can be very irregular•. See Figure 2-3, page 10, tor average yearly rainfall. 9 2.4 sampling Results Th• TUtu well •it• has be•n •&llpled repeatedly over· th• l•st ten aonths and found to contain definite contaaination. Th• initial ••••• .. •nt wa• conducted in July through Septeaber of 1987. Sub•equant sampling and analy•i• bas proceeded on a aonthly baaia. Tb• initial a••••saent conaid•red 26 v•lla and approxi.at•lY 50 ciaterna. Of th ... well• and cisterns: 24 v•ll• and 5 ci•t•rna w•r• found to be contaainated. Th• 5 ciat•rna v•r• cl•aned and disinfected by th• DCS contractor. Subsequent 110nitoring baa be•n considered for the 24 wells that ahoved so■• type of contaaination. Table 2-1 pg. 12, list• tb• wells included in the current aaapling prograa. Tabl•• 2-2 and 2-3, page• 13-16, abov th• volatile organic analyaia results of the contmainated w•ll• and give th• highest conc•ntration of organic contaaination found during th• last •ix ■onths. The sampling, and ■ost of th• pr•li■inary Photovac portable GC scr••ning, was conducted by th• U.S. EPA Region II TAT. Drinking watar laboratori- hav• perfor■ed for■al analy••• to v•rify th• photovac acr•aning results and to cover th• entire apectrma of poaaibl• baaardoaa contaainanta. Althougb, the concentration o-r thaH contaainanta fluctuate• ■onthly, it 1• noteworthy that th• -jor contaainants have been 1,2-trana-dicbloroetbylene (DCE), trichloroethyl•n• (TCE), tetracbloroethylene (PCE), toluene (TOL), benzene (BD), tertbutyl ■ethyl ether (TBME) and various .. tals. Their high concentration in four vella; Tillat, Harvey, Saith and St••le h- been evident fro■ th• initial a••••--nt. Tb••• wells •hov concentrations of volatile orqanica (VO) in axe••• of 1,000 ppb. 1.'he -jor and ■oat con•i•t•nt contaainant appears to be PCZ. The Tillet well h•• •lao shown very high DCB and BEN conta■ination. Four other walls: Francoia, Mathias, Four Winda, and Elgin: w•r• confined to have >50 ppb voca. The last confirmation analysis conducted during OCtober 1917, included the entire Razardou• Substance Liat (HSL), (consisting of approxiaately 150 ch-icala). At that ti■e, significant lavela of TBME up to 470 ppb, •nd ••thyl•n• chloride up to 120,000 ppb var• detected. So•• saapl•• have also ahovn traces of vinyl chloride, chlorotora, 1,1,1-trichloroethane, broaodichloroethane, xylene, and ethylbenzena. Finally, the RSL •nalysis •l•o ahoved th• pres•nc• of 11 rur 001 ) ., . ,: c.:: .1: .. -~- .,: .. \._, - TABLE 2-1 CURRENT WELL MONITORING PROGRAM AND CLASSIFICATION AT TUTU WELL SITE WELL NAME CLASSIPICATIQN OPEN/CLOSED 1. Ded• Public Open 2. Staala Private Cloaed 3. Blqin fl CO...rcial Cloaed Elgin 12 C01111arcial Cloaad Elgin f3 c011aarcial Cloaad 4. Pour Winds COJmarcial Closed !5. saith Private Cloaad 6. Bryan co-•rcial Open 7. Harvey Private Cloaad a. Tillat coaaarcial Clo•ad 9. Bart!man Zatata Private Cloaad 10. Devcon fl co.aarcial Open Devcon 13 C011aarcial Open 11. VDIA 11 Institutional Cloaad VIBA 13 Institutional Cloaad 12. Dench Coaaarcial P\mp/No 13. Raaaay Private Open 14. Barthaan cruabar Coaaercial Cloaad 1!5. Alpha Leonard Private Open 16. Francois Private Open 17. Deaitri• Collllarcial Open 11. Rodri9Qaz Auto Private Open 19. llart!man Bakery Coaaarcial Cloaad 20. Mathia• Private Open ' Definition of Claaaificationa Power Private: Walls which ••rv• on• or tvo houa-. co-•rcial: Walla that are uaad to yield vatar for -1•. Institutional: Walls ovnad and operated by a non-profit inatitution or gova:maantal agency. Public: Wall• tbat are tor public uaa. 12 ru·-r nu 1 :.:: 1 :,:'S' [ t "----" l [ [ r REFERENCE NO. 7 L L r I I I. "----" fUT UUl ::C:'l:'..U ( S-721 101:1501 FISH AND WILDLIFE SERVICE LIST OF [~DANGERED AND THREA TINED WILDLIFE AND PLANTS (50 CFR 17.11, 11.12; As sbown ia Code of Federal Replations. Volume 50. Re,ised u of October I, 1983; .a FR ~7. October 11, 1983; .a FR "6331, "6336. "6337, "6:WI, October 12, 1983; .al FR 49UI, October 25, 1983; "8 FR 52742. 51746. No,etnber 22. 1983; 49 FR 1058, January 9, 1984; 49 FR 1994, January 17, 1984: 49 FR 2783, 2186. January 23, 1984; 49 FR 6102. February 17, 1984; 49 FR 7334. February ~ 1984; 49 FR 7394, 7397, February 29, 1984; 49 FR 1052!, March 20. 1984: 49 FR 14356. April 11, 1984; .C9 FR 21058, May 11, 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, Aupst 7, 1984: 49 FR 33885, 33892. Aupst 27, 1984; 49 FR 3"9-f, :WSOO, 34504. 34510, A11p1t 31, 1984; 49 FR 35954, September 13, 19"'; -19 FR 4'0038, Octobef 12. 19"'; 49 FR 43069. October 26. 1984; 49 FR 43968, No,ember 1, 1984; 49 FR 44756. No,ember 9, 1984: 49 FR 45163. No,ember 15, 1984: 49 FR 47400, December 4, 1984; 50 FR 1056. Janua~· 9, 1985) Title !IO-WlldUfe and Fl9heriN CHAPTER 1-uNITtD STATtS FISH AND WILDLlf[ S(RYICE. DUARTMENT OF TH£ INTEIIIOII su•cH.u-n• 8-TAKINIJ. POSSHSION. T.ANS. f'OltTATt0N, SALL P'UIICHAK. aa•n•. 111.• .-OltTATION, AND IIUOIITATION Of' WIL.0 Ufl PAIIT 17-[NDANGEIIED AND THltlATtNED WILOUFE AND l'LAHTS A ..... _.,. Pub. L. 93-205, 87 Stat. 884; Pub. L. 94-359, 90 S&at. 911; Pub. L. 95- 632, 92 Stat. 3751; Pub. L. 96-159, 93 Stat. 1225: Pub. L. 97-304, 96 Stat. 1411 (16 US.C. 1531 II Hq.) (Amended by 49 FR 21058, May 18. 1914: 49 FR 22329. 2233'4, May 29. 1984: 49 Fil 27514, July 5. 198'4: 49 FR 28565. July 13, 1914; 49 FR 29234. 29237, July 19, 1914: 49 FR 30201. July 27, 1984: 49 FR 31420, A111us1 7. 1914; 49 FR 33115, 33192. AUJUSt 27. 1984: 49 FR 3449'4. 34500, 34504, 34510, AU&llSl 31. 1984; 49 FR 35954. September 13. 1984: 49 FR 43968. November I. 1984: 49 FR 44756. November 9, 1984: 49 Fil 45163. Novem- ber IS. 19 ... : 49 Fil 47400, December 4, I 984; 50 FR 1056. Jaauary 9, 1985) ...,.,_u. §17.11 ~ ... ..,_...., ...., .. (a) The list in this section cantains the names of all soec1es of wildlifr. which have been determined by the Services to be Endanacrcd or Threatened. h also con- tains the names of species of wildlife treat• cd as Endan1cred or Threatened because they arc sufficiently similar in appearance to Endan1crcd or Threatened species (see 117.50 ,r s,q.). (b) The columns entitled .. Common Name:· .. Scientific Name," and "Vene• bratc Poc,ulauon Where Endanacrcd or Threatened .. define the species of wildlife within the meanin& of the Act. Thus. dif• fcrently classified aqraphic pol)Qlations of the same vcnebratc subspecies or spe• cies shall be identified by their diff'crin1 1qraphic boundaries, even tbou1h the other two columns arc identical. The term "Entire" muns that all populations tbrou1hou1 the present ran1e of a vent• brate species arc !isled. Ahbou&h common nama arc incltadcd, they cannot be relied upon for identification of any specimen, since tbcy may vary 1rcat1y in local usa1e. The Scmccs shaJI use the most recently acc:cpted sc:icnlilic name. In cues in which confusion mipt arise. a synonym(s) will be provided in oarcnthcses. The Ser• vica shall rely to the c1ncnt practicable on the hu,nt01i01111I C°"' of Zooloficot NOlft,1telotun. (c) In the -Status" column the follow- ina symbols arc used: "E" for Endan• sered ... T. for Threatened, and "E (orT) (S/A)" for similarity of appearance species. (d) The other data in the list arc non- rqulatory in nature and arc proviclcd for the information of the reader. In tbc annu- al revision and compilation of this Title, the followina information may be amend• ed without public notice: the spcllina of species' names. historical ran1e, footJIOles. references to certain other al)J'licable por• tions of this Title. synonyms. and more cuncnt names. In any of these revised entries. neither the species. as defined in paraa,aph (b) o( this scction. nor its Status may be chan1cd without followina the procedures of Pan 424 of this Tide. (e) The .. Historic Ranae" indicates the known aencral distribution of the species or subspecies as reponed in the current scientific literature. The present distribu• tion may be 1reatly reduced from this historic ran1e. This column does not imply any limitation on the application of the prohibitions in the Act or implementin1 rules. Such prohibitions apply to all indi- vicluab of the species. wherever found . (f)(I ) A footnote to the F..,_I Resis- ter publication(s) listin1 or rccla111fyin1 a spcc:ics is indicated under the column .. When listed." Footnote numbers to 1117.11 and 17.12 are in the same nu- merical sequence. since plants and animals may be listed in the same F_,.I R~ister document. That document. at least since I 973. includes a statement indicating the basis for the listin&, as ~·ell as the etrccuve date(S) of s.aid lisung. (2) The --Special Rialcs" and "Critical Habitat" columns provide a cross refer- ence to otbcr ICClions in Pans 17. 222. 226, or 227. The .. Special Ruin" column will also be used to cite the special rules that describe npenmental populations and determine if they arc essential or noneucntial. Separate listina will be made for elperimental populatio11.1. and the 1&at111 column will include the followin1 symbols: "XE" for an essential Hperimental population and "XN" for a noncucntial uperimental population. The term "'SA" (not applica• ble) appcarina in either of these t~o col• umns indicates t~l there arc no spec1ai rules and/or Crintal Hab1ta1 for 1ha1 par• ticular spcc:ia. However. all other appro- priate rules in Parts 17. 217-227. 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-cnm.- rcquirements. h is not intended that tile references in the "Special Rules·· column [lee. 17.11(f)(2)] P'utllllrleCI 1:1¥ THI 9U"IAU OF NATIONAL AFFAl"S. INC .. WalfWlglan. D.C. 20037 29 I I ENDANGERED WILDLIFE ..... ----- ,._., I I ------ ----~ - Alli111or. American----·--· Alliptor milli111ppc·.$11 ___ ._..I s--1.1.u ._ ..... OD ............... .. -- ···-···············-··········-······················· .. , ~- .................................. . I I i ------ ·1 ,,,_..._ -- I ...... ....,. I US.A 11'1. ... --- Of GA. SCI OD ..... ································; ·•··•·······-·•··············································· -~----··--···· .... 1 u.s.A II.A. n,. ······1 I OD ............................................................ ; ................. . 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' - ~--·A"'~·"·-·•··-- :~~--,- ..... --·-·· ... , ; __ ... _____ . ! r. C:..C.... . ..._.,, : 0-,.. ---- ------ -· .. I,; I A. 1r-..i .__ lo,r.l, ._.,..'-4 ;..,_ t . ... OD I I----=--~-· I c-c.,..."""',,,... . .0..-... ,......,.. ·-····1"',.... ··-·······-· .... .. ··' _.,. ~4=~-- .::· . ·- ;o-----.. ·-·· ,.----~. ··- ;~:·:: -··-·· ·-·1 0-- ..._, . ~':!=~· ~:=·-- ·-:-.. =•=1· ~--··~--···::·· :. ... ·i ... 0., ·- -··-· ....• c,_,.. ........ ~... . .... .; a--,,; .. •----·-·- - .. ·--· -. .._ • ., ..,.,;-.,, ---· .. -- -·... . ... ~: ::.or .o ··- · ·- --·· l =:::;.:..; :~. · ::::::·.-::~· ·:~;:: ·~ ·~.;;.. .;;~:·:•~::.::::l ~~::. •· · ~✓••• ,.,..,.. ', c,-· ---r-- ---··· ... : •·- ... ,...-'lll, .......................... ! .. ,10 .. ··-···· ... . c,_..,. _, __ .,.. :.:-oi--.-... ......... . ... -..- ,._.._ ,,..,;,:...,_ ,_.,_ ·1"'·•·- r-,o.::~·•S..- <aa_,_ ~..r. ......... , c., .. _. ...... -·· ~~ ...... ...,.. ... --. ~ ..... ...,.., •····-----·--- • I .,._,.,.., 11.i;·~ •.;ca,:,::a 1 . 11.._. . ._. i : ~ ·1 0--..- ··-·••· .... I Sc-Jl">n•' ..,._ , ... ., -.. • .._ --1 I-.• ·- :,.,,-.,. ,-.-:-.-. . 11-...i..- ..,,__ ... ~ .. -· • ......... ·•·--~. . .... ~ ~--·- - ~,-o,w~ ---··-•··- •US.A.!f'11911~ ... -·•-···--.. ··.. ..1 .. • ~---~---·-·· ·-·-·---1--o.a,,~ .. -·--... - l G\4Jal ·!!' ·• ..... ..., ----..; --·· •-•-···---•·· -•-·· --••·-•- - .... , 1 ·· .. oo -........ -~ ................. _ .. 1~-- ...... ~-··---- ········· ••.-:-a.-.. .... ,:~ ::::-:=:r • ...- -·-- :~:==-=~.:::: . .:-.:::...::j.::~ .:..--.-::.:::...:.::·.=.--:::.·.-··.· .. ~I· : ,...., ,._-..a, P--· . ......... Q.-~ .. -----·· .. - ·---~ ... - .,_ ,,... -• W. : • -·. I - ~ I I ~~.~•--··-·· .-.. --. !~,_,.,. -··--· 1.:,:.,...,. ........... I • 9'1& C-._ ..,.. ......... -· I c_. .-.- .,_ww --- c..,w, -· ·-··--· ·1 .... ... .. .,_..,. .:.,e., • .,,.,. -· ···-·-- 1"r-._ __ •··---·-· ... .. ..... /c..» ........ --·•·········· . .,._ .. .......,. I F-~-€.-.... ~:::.::-:~. is-g:.-~=~~ -~ds1€'=:.::.::-- :-1~ I = ==--·-_-_-_-_-_-_-- ! = ::. .... -· ~::. ~---··_· ~:--=-~ = = =-·---=-..::·:..:..::. .. :. ·1: ·~~= .. ~. -.... ·· . J __ , __ c.c.._ -- i~---··-···· -···· ___ ,.,.. ... c:--.. : ..... ·-···. ...... ._....... .C.-...... ----·· 3UU.dl\#'9"-: ... ___ . ··-·• ·--··· ...,,._ w-. - ..--- . acar • ..,...,. ·--· ·-·---- - ......- ..,_ ___ ... ·--- - .. _, . • ...... . ...,... - ea,....,._._.·-·- I c....,. ...,.--···-...... ·-·-· •· ...... --- -··· •. .... . r. -• - . . ' - IIU'I·----··--··--·- .'"-'-••~,-. ... ·-····-lu.U 1=---i.- ·-·-· 1·•-• l i..._~ .. -~. i..w- _.. , .......... -··-····. ·- - ~& - ...... _____ I Gaaia-.-. ..... -.. ·· -· ·· .. i .... .c-, I ... ........... ·-·-··- .. ---·-- .-.....,.~. ,--,. I.-\JJ.:J b~ 4'il FR 73~7. Fi:bruar} .29. 19114j ,,_ I ( Added b) 49 FR 739 i. Februa r~ .29. I 9114] PUOlllfleCI lly THI 8U"IAU 0, NATIONAL. AFFAl"S. tNC .. WUIWlg10n. DC 20037 TUT S-713 101:1511 ...... ,,.,,... c.-. s... - -- ·- , 11 S1 : E l'oA / l'oA " 111 I ' I T 20 '7 I l'oA' ,1 &aiat '° ,,, TIS/Al . . ' .:- l'oA. UQal ~, . S.:. 1,·' TfS/AI ·• .- I ., ,,, l'oA, U &al.al .. • ~ I ;_ ... ., z, 11 '.Si • .. .. l, JI .. A I ..... ,, » ! ,• ,:-i.•j I .... 1, % ... , .... : \ • ""' I !oA I .. .. .. ' ..... I I 2 .. ... I t-~-- Ei " NA: ,., ,, 11 I , ... ( ..... I' ,s I .... ' ,._,. ,1 .: i ..... ; .... E! ._.. I .... : I ,s I ~- I "' .. ~ ,_, .... 11 ,c -~ , .. »!Ci I ,., I I j ' •t: , .. ; , ... II ,s: ,.~ i ... ii : : ..... , .... 1 I ...,_: 111,1, .~ I ...... ... ,, ..... .. A El , ' h \ ~ .... E' 15 ' .,. I .. , 11 !1 t ....:.'. .. A I I ! 1- ,s' .... ' ;.• r: l. •!, r -...; ..... ,, .... ' "'·' I: ,~t. ,,,),•,; NA E• ,, ... "'" T: •1'. ... ; ..,. T I '" .... ' ..... ~· ·~ "'" I .. A l I •n· ~I NA ~i ,, NA ' I H, I IE I ,, ''" T I I }I I ... ' .... ti 18; .... , ... I I I ' I 'I •21' llt& I NA E ., "'' i NA ,· Ml ••'- I .... I 121 I ~, NA I 121 I 'CA T ,11 I .... , ""' T ,ii 17t5'~1 I NA T •211 NA' "'·' ti '" NA I ... TI IZ,' ..... ..... I· • I "~ NA Ti ·~; ,,w., .... I ,., 111A - - I T i.z : 111A ... , .... 17.11(11)) 57 ,. 1. ! I L I" I REFERENCE NO. 8 -- I NUS CORPORATION TELECON NOTE l CONTIIOLNO: DATI: TIME: 3/3/<?q t t Lf 1 DISTIIIIUTION: u1<;Z I c7-. <?<=tc t 2 c; IITWIIN: OF: "40NI: --t , \-JO-<-~ Sc\.,.__\ ct\ io r E(-'/4 - G w t-(7"""" . (2, 2 ) 2.G, 4 - it' I?~ AND: !NUii DISCUHION: -1::e~x~S>e~c¾~~~~------------------ --~ \ - r '· . ,- L I_ [ [ I - l I_ ' ' I I L I r - REFERENCE NO. 9 I I ! . . ' ' '' •. •. "· ,u __ .. ~ :. ~ . _ .... ; . ,.'. _ . ,,: --, _ .:h .• -j ·;. > ,;·,.:.1:(-.-· -) :0. .:-,.-.::_.;;: ,:;1,. \;_J.:r· ~---:~:::;::; . .. '·i;.t. ;:,. __ . < ?rap;;ni1 in cooirnrnlion wi!li llrn U.S. ENVrnDNiflENTAL PllOTEGTlO~ J\GErlCY , .,;\ -.,,li;; IJ WITED ~TATE8 "'"OL'(.l''!t'a / br: . ti t,h_ SIHIVEY WATEll -- 'l "~ o u1 ·,, r: E" I• rr. ,, 11,.0 l~VESTIGATlO~;s llf POHT 38·41:l 1 1988 POTENTIONLETRIC SURFACE 011 THE TURPENTINE RUN BASIN AQUIFER IN THE TUTU AREA, E.AST.ERN ST. THOlVIAS, U.S. VIRGIN ISLANDS, SEPTEMBER 11, 1987 .By Rober t .P . Grnves and Ralph Gon zalez Grour1d -wat er level s in th2 Tucpenti~e Run ~as in aq~i fer, in ei1ste~n " •- d · ·1-, ·, l S te _,_ ,. .. lJ ' 9R7 ·nd ·1 ,cl . . Tl·i<:rn.::i s , '.~'c•.r l~ C(~a s,1 :r e 1r:i _ L ''°<'8 .'. s on , e_p -'1;, 1.,, ... :. . 1 .:. <.; ~. ,_ 1)otc,ntiometr·i_c sur f ace map was p r epc.!red . The a l t i 1:.ud'3 uf a l l wells ·,n1.s ~-·cf e. 1_. 2 11ud to ~".:7i0',,r'. .land s u ,:fa c c; -.0d.t:I.tu d c. ~ench,1:,:-irk s by us ,:; u l· a lev~:'.. :::; urvey ·! nst r 1.1.m::>.nt. The p o t <--'ntiomet_r.:ie su ef2ce map was prepa re d by tne , - ,, (' , · I S 1~,•ev -:, 1·1 •.·oc,,o,'.Y.:t ·',· .i or, ',,,.;_ -i-_1-; -r-_J--::r~ ll.3. E:1virur~::1e1rc-.a~ ,J .::., . .1 E-.'O .,. C, _z LC ;i _ ·- ' • .c , · .1 - - ,;:c_ - - - ' -- 1- - P=o t ec~lon Age~cy . fr ,,1c t ,_ir e.d vo:.cc,rc·~c 1.-oc l-::,s lm(~e r J.ie ·:.\1r ;ler. · __ -~T:,.:, :i.ur: b8.'.; i n a n.cl ~•.re loc cc l l y ovc.rJ.2.\n 1)y .::~.l l uvia l deposits (Do;me..L .Ly , 1959) . The al l uvial .4 ~,-,-. ,i s· •; 1""' ,. ,., ,, r·-1 np c..i t r-, L: i1 f P.e t i n t :nid:ne s.s. Gt'')'..!!ld 1r'1-' att:;r :er; U1e. '-' ' ··Y - ~• .,_ _ .:, -'-'"• -'-· · ,-,•- . - - T'...Lr ps:1,_: :i.n,,;. L1.:=-i ba:::,in oc c•_1r.s i n the ~ra c~t u1~0d '✓C J.c an i c ~:ock and alluvia l ' · · u." 1' c.,,- w,.,_t:e r - 1.:.a ble cond i t i on:-;; (Jord[m, 1973). T}1e. 2.lluvial (18p0S l CS " '- . _ ., . . . .' . · I - 1 , ' 1 1 1 ""' , ~ - d ,,· ·r )· t-.), e J.'r,.tcti:.red C,s,po :3 .\. r ... '.i ;.'.:::·r~ c.'.Jn:o:~.c er ec : o ue ~,yc.r c.cl..'. ... 1.c. 2 .:..1.y '.: c. •• 11-2 ,. _'::::. "'·" - , _ . •✓ol r-:c1n"i.c -r:oc:k . Wel l depths i n t he basin can range from 55 t o 325 fe cc l b~:10~ l;ir:d S~Lrfncu. Seve ral wcd J.s we re be i ng pumpe d , or pump"i.ng had j u.st ter::ninai.:.e d, 'i/'l':'D t l:r::>. ,,.,c;:-1.:.c~r le ·-.1e1 s We}:·e me. .::1.suu: cl (1.:.able .1- ). Thes e ·v;a t er l.eve J.s r· e :f l.8c t. 2 n m1ping or n ,cover y cond i ti on ; t hen~for e , s tati c wat c r - :i.evccl c cT1. r:Lr::~on.'c tr·.:~cugLout t Le. ~·:·u-::pc.nt·~:;-ie ~-~·~1r. bas i. n. ,qt t'.10. "t. :i.r:1e. o:: me.2sL1r0:ne nt c: aD r1ot be a s s ur~ed . AdditiDn':'.l in:'.:o -rmc.ti on ;:cbo· .. 1t gro ·_md-wa tc"!r lo.v2 1.s -Ln the n:.ea of !":'': nd y is available~ fr om t.he IJ . S . Gc~ol og ic c1.l Survc!y , Wa ter .h.esour co..s [.' i vi~ic,l, C.n·i 1)b1c".an 0i s i.:1· j_c t off i co. i n S:rn .J uim , Pi..:.c!rt o R:Lco , Te l. (889) ·,- l-,e 9 ·· 4 ] Lf(,, . SKL1~C'['ED RE FEREN CE.S !Jonn f:, 1Jy, T . W., l959 , Geology of St . . Thom~ts c:ncl St . John 1 Vi rg i n J. s l;c:.n(.b : UrtJntb .l i s1ieci. ?h . J]. :Li. SS(~r cc: L:·~ on , I'ri.rccet on IJn ivc, r.si t y, l 7 () ·~ Ger:igh+:-y &. l·:i l.Le:::- , I r.c ., J.983 , Repo.c.· -<::: on c ur.::·cm-C:. gr oun d ,~·ate;::- conc.ii·cions ir' thn U. S . Vi r gin Island s : Prepar.ecl f or the gover nment. of the U. S . V:i.rg :Lr: T:.1J.an cls Dt.:: par !:me:.n t cf Cor;scr vatior: ancl Cu::.tural Af.fai.r s , i! '.1 p . .T:ir:-'Lr1, ') ,'-:1, ,,.r: d Cosner, O.J . , :.9 7], ;\. s e r vey o:: t f'. e w'~tter i:e,:::o'.\r ce s of Si~ , Thmn:is, \'ir:i:in Is l ands : lJ . S . Geo l og i cal Survey o_µen - f ile J:epor:, SS p . Steven s , K.E., G6mez, -G6me z, 1"., and Al i ce2., J,, 1981 , Water we.J.ls .in t he. t:. S. Vi cg ..:. 2.-: :::s .La.:ld .s , Pt. 1, S L. 'I.'Lo:-na~:: U.S. Gc.oiog ~.cal s,.1.c:-vey Opcr1-Fi l e Report 82 - 82 . Prn.%!r!:id In cooperntton with the ---------·---·--- ------------.•----- ·-·--·- -- !.,1.3. !21</V\l,,-'V)MM-"f,;WT.AL p;:;-ryrn::n:,M t,(;}ENCY Tab le t . Desc:iptio~1 of weJis 1:1nd Sept 1}mher 111 1-987 wa t er-level measure meni"s in Turpe n tine Run basin, S t. Thomasj U.S Vir9fn Islands [oa!um is moa n sea la vs-1. la.bbr<Jviation s: hy phons, da1a not avnilablo; (RU, <J•J~poctod rocovorin r; fevo!; (PU, s,;r,ipar, t8d pumping !eve-I] Vlell n u:m ber ,Jl OJ 05 06 07 ('') oO 09 '..J JG 2 1 26 27 'H' _c\ ') -~ . ' JO JI ]2 JJ ]4 JS \Vell :id.t>n tifi ca i;ion. number l S2 C2L,OG L;:"l:-l5 80:) 182C26064S 3.S8 0U 1320250iJ4S3 58U0 :. 2. 2 G l 8 0G L1S 35£·0 D 18,0170645].5900 :P3 2.0 J. 6 061,_'S 3 5 90 0 l2 20 1G064.S 40000 1 u·;.u 1 so 04s tfoo .Jo 18 201, 20GL1 SJ JL,00 l B20J 7GGL; '.:· :.\ .l. ::. DC 18 2 OJ 80GL,53 .1. /. CU : 82 CL, 3 C, (il;S 3 ::.1,00 1H?.0/1906L:5]09 0:) ';SL C 2 9C-GL,5 J :S OU l E2 027'.)Gl,53 1800 18'2.0270645 J l 900 13 202006!+53 2000 : 2202.00 61,~_j 319 0 1J 1B20J. 90645Jl900 lB!.01 6Q6 4SJ2000 .l 8:!.01706 L1 5322 00 l 020::'..l 06L15J 250 0 l 82018 064'i328 00 l 82017061~5330 00 18~01 806 11533100 182 01806 L15J 32 00 18201906/,53 3300 l H:~O 15 0 (; L1S 3 2 7 00 1J201 60 6 !15 3 2 9 OG 1820 l 50 611S 33000 182014064532900 ::. 8'.Wl 206 4.331 40Q 182009064S31300 J 8200806 45]11,00 ',_ 8 l 9lt306 4525J00 36 :81940064525201 3; r -·· 18'1 93sos4s2s 100 JS i J.,SJ. () 38J(ilf52.5GO~; J9 r· 1s 19J1064s24900 40 181935064524400 41 Vl ell nv.m.e :'"!ar .Lo Br yan 11\10.J.l J'.11 M,·ff :'..D HTyan \1!ell il2 Man .o B:-:-y -21.n \'i'c .Ll lJ J f.'ockhart We ll ill Lockhart Well 112 Loc~chart W8ll //3 Loc~d12rt We.:!_ l ;/ii I.,,:or.:.lchart.:. W'.->l l //5 D2.mitry Wel l VIhA 11-.1c.11 // l VIBA WeJl !/2 VI!J.1\ We.J.l /,/ 3 VlEJ._ Wel l l/ i: Ti:llet s ,.-,re_iJ_ J.i'our Winds Pl ~7. a 't1e .'... l ffl Four '~' in,:is Pla za Ge:ie Eg Lin Well ltl Gene E;;; ..L in We l~. /,'2 Gene Er,lin Well 1/3 E . S 1_·.e.el \•;rc.l l Osborn Harvey C-::-usher T.'iP. 7 :l Bakery Well (·:re.ge. r Mot ors v;eu Ill Cre.ge-:- Vot 0rs Well 1/2 Creger Motors We l l #3 Creger Mot ors WeLI. ffL1 E 1 s & A Corp Wel l lll E 1 s & A Corp We l l i/2 E's & A Corp Wel l i'l3 E I s & A Corp Well 1fL1 Er 2.r:cois La .?lace L. Smi.Ut lfatt:--ii a s Fa-::-ringto rc v:ell Pol y C2ri b/Devcon ll l Po l y Ca .".':i. b/.Devcon f/2 .. Po ly Ca.,:·.'.. b /D e v c:un _i,;·:i P0ly Carib/Dev::on /lLf Publ i c ·,:el l/Did i ,,.;ell (Gov . of t h0 Vi r gin Islands ) De.pt. o f Ag·~ i.cul ture Animal She lter Ye~.r 1. 978 '9 77 : 97 i' l978 1978 198:. Depth of well (feet) 175 l SCJ JL,2 1 L;/J 1.CD JC!) 285 22.5 n s l.950 !s lC5 l 978 160 1~73 1978 1960 1 s i 960 1 s 2lC 325 55 Depth of cv..ni:1g (feet} 41 37 73 69 1.5 36 ]6 Con.Bti-ud:ton Oper: ho l e. :)prc:.n }-:,_.:,l e Op c1!l l!'J l c Oo:::n .hc.J.1.;.• Op,c.n ~tole. Opt:'n ~1ol e Op0n hole ' I Water 18veJ below J.v..ud su:rf tu!e (feet) lJ 10 09 08 OS 06 08 H:J 56 68 17 39 21 ' 13 89 12 J7 66 76 JO 32 22 27 26 2' 20 18 19 1. 6 28 10 10 13 l .1.8 26 \Yater level c1Jt:itu.de {f eet1 209 20 3 183 l 8Lj. : 51. (RL) 175 '75 222 239 165 156 132 112(RL) 86(RL) 99 (.R..L ) 108 108 108 '.0 8 109 '.1 6 17.8 108 107 109 83 RO 80 30 - 83(PL) 01 ". c ) I ' Lnn d. au rfa. c e v.ltii:1.1.<le (feet) 215 220 218 192 192 188 189 231 2Y_ 235 239 278 "1 86 166 165 l L14 lL19 152 "'._ ;' 5· 138 ~L10 130 ). 35 135 137 1L18 123 126 126 125 " 11 90 90 43 35 ?. 7 9 o5~,oo:::' ____________ _J>_05"i-0}'0.,,_s' ____________ _ ,e<,c~r'5"-a'-;;c;:------- -------'"""""T"'"'-·---- 7 •=·r 1~ \.,) \'\ \/ 11.1-"20' --· O ,2 .1, f3 MIi. ES ~-T_J_r __ ,1J_,. ___ ,,J O 'l 4- fJ ;<.1LOMf:.TE1'lS 18°17''---------------'----------------L... _____________ _jL,_ ____ _, 3(20 8 ) ~ !W,up ol St. Thomas sho>Yin_g th e s 'i:udy area. EXPLAl,ATION POTCNTIOMETR!C CONTO!Jfl - Show ::; a,trtuda of w~t,:)r H\b!-G fn foot. Da ~h~d whom appro xim t1te!y Jo c{.lted . O•Joriad (?) whiHe loc aH,;,n ;g uncortain. Conto'Jr !ntarva r variub!B. Datum is meun soa l(rrsl. W/\TEFt- LEVEL D,\TA CONTROL POINT - Open numb-er is tr o wol! rv~m0,H !lhDvm on !Hb/e 1. Number in µv.rnn! h1;t c,1 •1u is the B.ltitu,:Jfl of wato r le vel in 'la.et o~.tum ia moan aBa IBvaL OEOL0'111CAl 8Un ·--------- --- - --------"""""-----------------··--~-.~-········'--"·-··-----,•s,•···"'-••----·--= - ·-· ________ w_A_TEA-- __ AE_IIOURCE_...;;._s_-..;_;:.;_;,_;;·;.;llOli:.,;.;:_.:,m:..-:.:::..: · .:.:rr:..:2~S-- O t:.~ 1 MllE i""·-"""F~Ly=.~-·,,l, ,, ·r--,,"·1.r~,.=}"W" . ""L: • .,==.,r=•··--~ .. ,,---1 .. ....,,._""'~ 0 0.5 REFERENCE NO. 10 - - Uncontrolled Hazardous Waste Site Ranking System A Users Manual (HW-10) Originally Published in the July 16, 1982, Federal Register United States Environmental Protection Agency 1984 ----~-=--------- :a- ------ . ~. UILI 2 fllaAIILffl or GIOLOGIC NATIIUU* 'l)'pe of Material . . ClaJ, c-,act till, ■llale; ullfnccuNII •taoiplllc ..a lpaoue roca Silt, loeea, atltJ claJa, alltJ loaae, claJ loaaa; 1••• pemuble 11-etoM, •olalt••• •• aaadatoM; aodaratalJ pemua.le till Pi••••• ailtJ aaad; .... , loau; loaa, ..... , _..ratalJ pemua.le llaaetOM, •olaltaa, aad aa•atom <• unt); aoderatalJ fnctuNII l&DNM •- •taor,ldc rocu, aoaa coane till Gra•l, .... ; 11111111 fnctuNII l&•oua •- •t-ipld.c rocu; ,-mua.le 11a .. 1c ... la••s unt llaaeto• •• •oloaite *Dari9N fna: Appndaata la•• of a,•rauuc Co•ucthtt7 ur5 - ur7 eaJeec Aaa1,_. Value 0 1 2 3 Duh, S. I.• 1HH1t7 •- fu•nld2iof latural Katen.ala la nw-ftnuall Ponua IINla, I.J.N. Dahat ... , Ac c fnu, law Torti, lttl PnaN, l.j, .... J.j,. Cbarr,, Grouanater, Pnat1ce-llall, lac., ... 'fork, 197' 15 ru r c1c1.x. </ .. ::;3 r l -- REFERENCE NO. 11 ()01 ., ,l I I t The Geological Society of America ........ Memoir 98 CARIBBEAN GEOLOGICAL INVESTIGATIONS By H. H. H~ EtliJM - DIIL 0-.,,, Pri_,_ u..,,ni,. p,..,,,_, N• J•-, Carl O. Bowin Woou Hou Oualf'.,_ lrutilrllia, W,ou H•, Mu.dtlullu 'Ibomu W. Donnelly n.,,. c,oun, Ria u,,;,,,,nty, e,.,,., ru., John T. Whetten lh/JI. G,olof, • O~-,,.,, u,,;.,,.n'1 of WuAi-,,-, SUIIU, WuAillfln E. R.. Oxburgh D.fll. G1olo0 o,ul Mwr.u,,, Oxfor,J u,,;..,n·t,, Oxford, E"llad 1966 i-ur 001 :.21.i:1,.J t: l· r-. ·. ,-- ( 94 ,- - • - CAalaH:AN ClOLOCICAL INVUTICATIONI - ·--- 1hc final b.uc map, have good ahore-line de&ail. Mappinc on s,. John was Jone on I :20,000 enlargcmenu of &he I :40,000 U.S. Coa11 and Geode1ic Survey map. Aerial ph01ograph1 of approxima1cly I: S0,000 Kale were UK• lul for some 11ruc1ural in1erprelation1. Exposures along 1he shore lina ranged in quali1y from c:xccllcnl lo very poor. Thme inland, exccp1 in recent road cuu, were almou invariably very poor. The bell OUICNlfll .. ~ S1. Thom.as and SI. John are llttp dills, whid1 arc in placet l..,llelV, • lravc:ne. More shellertd shore linn arc easily walkccl, bu1 rod. ea.-.,a llerc arc much poorer. l.aboratory invc:sligalioo1 lnch--9 11udy of several hundred d1in Kclions, X-ray diffr.aoion examination of rod aamplca and miner;al acpara1c1, about SOO p.arai .. l chemical analyses, and numerous mineral dc1crmina1ions b)· op1ic:il cumina1ion of cru•hed aampla. About a du1en fcldspan were dc1crmincd by mc;uuremc:nl of index of rclrac1ion o( graim orien1cd on 1hc univc:rul 11age, according to 1hc mc1hod of Smith (1960). Apr1oxim,uely 100 additional rbgiocl,uc: samples were dc1cnninc:d by mca111rcmcn11 of indi~s of rcbauion ol ,morientcd grains. An extensive optical 111tdy ol the ft:ldspars, complc:1cd ahrr 1hi1 m.anuscripl was fir11 111bmi11ed, has been publi,hed cl•ewhcre (Donnelly, 1965). Pyroxc:na were clc1ennlnc:d by meas• uremena of"• and 2V, according to Ilic me1hod o( Hess (1949). SUMMARY OF STRATIGRAPHY OF ST. THOMAS AND ST.JOHN The rock uniu of s,. Thomas and St. John (fig. 2) can be divided in10 1hrcc major groups: 1he W,uer Island forma&ion. which consists of kcra• 1ophyra an,I spili1es: the Vircin Island Croup, which consi111 of andnialc pyrod111ic rocks and aedimcnas: and one or more diorllic plu10111. The \V.ater bland formation possibly is b1e Lower Cretaceous. The Virgin Island Group is probably Albian (ahhough the Hans Lollilt Formalion could be Eocene), and ahe diorila are early Tertiary. The ol,lc:11 rocb in 1hc Virgin Islands are 1he lr.cra1ophyrc1 and 1pililn o( 1he Wa1cr Island Foranalion. These volcanic rocks arc prcdo1Dinandy nows and now breccias, but lr.era,ophyric pyrocla11ic rocks arc widespread. A few of 1he &ne-snincd 1ulaceou1 beds con1ain wcll-prcsnved Jladiolaria of undetermined act. Notewor1hy in 1he Waaer bland For1nation i1 ahe ab- acnce of 1erri~nous aedimen1s. This charactcrlslic, together wilh aheir ap- parcndy igneous mincraqy, has led lhe wri1er 10 1hc conclusion thal dacy arc probably volcanic rocks which were cxaruded on a rcladvely level ocean noor, prior to die existence o( a trench or island pla1form. In con1r111 10 ahe pouula1cd ab,asal environment for 1he Waler bland ~olcanic rod.s, m011 of ahe ovcrlyinc pyrocl.a11ic rocks of 1he Virgin Island Group were c:i.1rucled.1uhaeri:illy. 801h 1hc volnnic and scdimem:.uy 1ocb nhibi1 slump struclllrcs, and 10me megabicccias conaain limc11one blocb up 10 100 (eel long. The bulk or the scdimcn1ary tocks in 1hc Viigin Island ·--- ( I I I I I I I ·--- -. - ,_ --, --,( -, T. "'· DONNlLLV-ST. TIIOt.lAS ANI> Sl. JOIIN, II. s. \'IMI.IN hi 1111,os ~-·• Gao•~p ar~ co.111c wackes consi11i11g .ilmou cn1i1cly of slii;hil)· 1n·a1hc:1t:1I clcbris clern-ecl lrom 1hc an~esi1ic py1oclas1ic ro, ls. The ,lcpmi1ion of ahi, croup may lia,·e auompanitcl 1hc lorma1io11 of 1he i11i1i.1I isl.uuJ pla1l11a 111 and trench. Q. ::, 0 a: Cl C 0 a z .a .. ..J ~ Cl) ~- z C, Cl) « :J > 0 w u cf I-w 0: u C:ONGO CAr C:0.1 ,o.,., Clllfllt HANS LOLLIK FORMATION l•O 000 letl • I AUGll[•ANO[Stfl lll(CCIA eft4 •uff up,-, eft• .... , , . ._.., ......... ,. I TUTU FORMATION (6000 feel •I TllffAC[~S VII.Cit[ '"''"fH fttor tht t.ou tht Cokl Poml Me90breccio lilholoc1u. Noa, •~• ••• 11 •~• Con90 Coy L1m1slon1 Member (200- 300 feel): C:O•llsCL, CfllSIAl, IN( llM(SIOlf[. ft, ., for111etion n•I 1•1,1Ht4 1n US 11lot1dl OUTER BRASS LIMES TONE 1200 - 600 h:tl I ,allflAllY SlllClfl[D fUHAC(OUS IIAOIOl All1AN LIMUJOH(. ' ' LOUISENHOJ FORMATION 114,000 feel IW SI. Thomosl 4000 letl (E SI Thoma,) 7000 , .. , IW it. John) I AUGIT( • ANO[ Sill '111ECc:1a .. 4 IUH t•LUC •fACH el Cl[VCI. Noor•~• aau It .._ Cobe1 Point Con9lom1ro11 lilllofocies ::,:~~~• •n• ua .. 11 ti •Allll ISLAl<O fOIIMATIOlt UNCONFORAIITY------- WATER ISLAND FORMATION (15,000 fut+) IUATOPNYIIE ,lo••· ,low lll[CCIAS, .... ru,rs •1111 IPIUU _ 'LOWS •ft• Mlftor IIADIOlAIIIUS ' ... .,_.. .... , ..... an• , ••••• , •Uu, lOPHYII[. . liuatlcrapl,ic K',tiun fur S1. ·1 hu111J1 anJ 51. Juhn. \"i,i;in 1,1, 11,1, Fold~na;: _ah~r ~~l'?)itiou or 1he Virgin hfonr.J G1011p ac:u,laul l,ucd) lrom d11fe1c:n11.al u111cal mo,·emcna .111111'•0tl11cl'cl ;1n·1.,gc dips ul 111• 1,111 • Ing from IS• 10_00•. The ;usodatl'1I uiile-slip bulu 11.ne ho,iwu1.1I 0 0 11,l-~) ol k'U d,an I mile: A~1~1011gh cn111ac1 mc1amo1 phic cllcch 1<:,uhin~ from ahl· e~1pbcemc11t of d1ur111c 1•h•~om art: cx1cnsi\'e, 1he ,vcs1can 1110 ,hut.ls of s, 1 hom:it and 1he 1oud1c:rn thnJ o( 51. John arc t)scauially unmc:l.inwrphosc:d. I I -, t t :I, . t. : ·~ ---:. I .. ( CAIIIH[AN ca:oLOC.ICAL IN\'UTICATIONS WATER ISLAND FORMATION ClNHAL ITATUllNT The Water Id.and formadon of pouible late Lower Cretaceous age lomins almon entirely ol l.cratophyrc, 1pili1e, and r;adiolarian tud. The CK· 110,td 1hiclnc:u of 1hi1 formation ii 15.000 feel, based on projec1ion of du: hii;heu and lo,,eu ho1il0ftl--. ·A reasonable coneceion for lcn1icul:ari1y mit;III lower tbe uue ,hiclnaa., a.e· nposcd section 10 8000 or 10.000 feet. \\'.11cr lsl;aud, in the harbor of Olarlouc Amalie, St. Tho1n;u, has bccu ,di:ued as 1he •nic locality because of the great variety of rock types there aml the gcncr.al ci.cellcnce of cxp01urc1, although cxcc:llent exposures crop 0111 utcmi\'l:I)' along 1he south iliorn of St. Thomas and St. John. "Kera101'h)rc'", as 111eJ here, is an cx1rusivc or hypabywl in11111ive ,·ol- c.anic rod. comiuing prodimiuantly of albite and quaru, with chloriu:, mic.aceou, 111int1als, ;md iron oxides. Nearly all of 1he Virgin Island, lr.erato- t•h)rtl comain cun,ilh:r.able free qu:.1'11, commonly a, con1picuou1 phcno• cr,,11. Thoie \\ i1h 1111;11'11 phcnOCr)SlS could be called "quaru Ler;a10• l'h)rt" but m;.iny aph,ani1ic roch here called "lc.-a1ophyrc" arc chcmicall)' idemiul to the: w called "quaru leratophyres" and 1he simplest 1crm· is p1c:- feucJ for all 1he5C rod.s. A striking feature of kcutophyrea is the :ibscuce of phcnocry111 (or pscudoa,orphs) of pyroxene, anaphibolc:, and mica. Kcr;.i10- ph1 ric Dows anJ tr)'J!al tuls arc sot.lie, with a very lo,., pot,mium contcm1, but so1ac apparently vi1ric tulfs arc 1lighdy more pot.mic. Ker;atoph)IC in• ttu)ive rocks ha,·c a higher polanium content an ' commonly cont;ain ll'i:• onJ;ary monoclinic K feldspar. "Spilitc" is a gretni,h seemingly ahercd cx1rwive or hypaby11.1I inu-ush·c: 1oc.L, co11si~1ing of chlOJitc and albitc, with variable a1nounts o( epidotc, pu:hni&e, and ulc.i1c, Fresh phenocry111 of clinopyroxenc a,c ge11cr:ally present; amphibole and olivine were ROI seen in the Virgin lal;mda spiliu:1. Am}'gdulcs arc :almnJaut and commonly contain moat of the calcium con- 1cn1 of the r0<Ls as cpido1c, nlcitc, or p.-chnite, wi1h qu:ar11 and chlotitc. Thc:11,C 1pili1e1 cont.ain :about the .an1c amou111 of Na10 lll the :a11ghc :i11dcsi1n of the Louii;c11joj formation, and :about 0.S per cc111 mun: daan Virgin Islands diabase dilcs. Included with the s11ili1es here is ~ pa11i;ally ;albitiud augite andnitc which occun near the top of the formation. The name spilite hu been applied in the past 10 rnany diverse rock types, wmc of whi~h may be low-grade rc:gionally me1:amorph01Cd andcsiaes or basalu. Other spili1e1 appeal" 10 hne been unusually hydrous m.alic imru- si\·e rocks, and m,my a1c dcu1erically altered bas;alts or ;andcshes. llowC\'er, 1he1e is an imprcsiivc body of evidence 1ba1 many so-called 1pili1cs, no1.ably certain 01Jovician, Devonian, and Cretaceous gcosyndinal 1pili1cs. have charactcristics which can be best expl;aincd by assuming an csscniially mag- ma1ic origin fur 1hesc roch. h is 10 1hi1 lauer group of rocks thal 1he Water bland fonualion 1pilitcs belong . ( I --··-, ---~ ···--, -·-, ( Such 1pilitcs 111.1y be thoui;ht o( as 10, h ,~hich h.l\'C fo11m:d 1,y .,lt,i111.1 lion of andt1i1es. Ho,vc,•cr, dais process is bclievc,1 10 occur d111 i11g a la1e llage in 1he solidilicatiou of a hydrous malic magm.1 and is 1101 c;amC"d hr later mctamorphism. Given a ccruin combina1io11 of 11h)sic.1I ancl chcmiL.il conditions. spilitiaa,ion of malic utrusivc rocb is inevitable. llcmc 1hc term, applied in an ad111i11cdly rcuric1iH· gcne1ic (hence s11hjc:e1i, c) semi:, i, ;a mcful one and ,hould be re1aincJ. The a111hor a,l111iu 1h.11 lo\\l g1.11l.- me1amo1phh111 na;iy obli1cra1c 1hc 111ine1aloi;ic.il cri1cria 11cccss,11y for 1hr tc<01;ni1ion of spili1il.l1ion. Chemical anal)si, ol a 1-n~c .11111 ca1c:l11llr sclcuc:,I 111i1c: o( specimens miglu 1cvc.1I "·he1hcr or 1101 1hc 1111:1.1111111 phi, roe ls in q11cs1iu11 l1Jd been urigin;.illy sl'ili1i1t·1I. b111 ,mh ;i11.1lpis 111ii;h1 ·'"" I.ail to ,lo so, ;,i111l 1hc 1cr111 shuulJ he: a11plic,I with u1c 111 s11,h aod, suite:,. U.kA'IOl'II\ klS '"''"''"' tmy Jlllll'llltlll. Kl·1.1111ph)IC (Olllp1 i,n .11111111 r .. 111 1,111 .. 111 , ... \\la1u lsl;1111I hu 11utiu11. i1u~1 le1;a1,1phy1c O(C 111 s a, 1111,,·s .aml llm,· 111 n, i,1>. 1vi1h minor 111fh. both ct )'\l,1lli11e ;11111 ,·i11 il (1hc l.111L·1 ;,h,·.,p 1k, i11 ihnl) .11111. rarely, ,·olt.111i, l11nci;1s. Kc1.11opl1)·1ic i111r11shc 11>,l> Jlc 11111 11111,11111111111. lhr_y occur as lm1h dil.cs .11111 ph1i;\, w11111io11I)· L>·i1h ,·c1 y ,,., II tlnc:1111'• .i columnar joi111i11i;. Kc:uwphy1ic Hows ;uc l;l'll<'l.1lly tcm ol feet in 1hi1l11n, h:w 1l,i,l ll,11n .ire compk1cly cxpo1c,I hom top lo b:isc; 11,osc 1d1ich arc 11·tll npost,I :11.- uriking only for tl1cir lcXlmJI 1111iformi1y. lbLing anti dulling 1'h,·110111c11., a,c o1bsc:11t. t'I01v ba1ulini;, lhll;llly somcwh;,t co1uo11e,l. i) seen l,,1:1lly (l'I :1. Iii;. ·I). <:0111.11 u bcll\'rcn llow unih ;a1c conunonl)· ,lillicuh III ide111ilr ;is such, ancl ;111i1111ks u( 1hc 11111v) a1c 1101 ;1lw.ays c.1)ily .o<c11;1i111:1l. One 1hicl lc-r.11111111) 1c llo\\l 11c,11 1hc L;1sc of 1hc srciion, on IC.1111 I k.ul. St. Jol111, )ho"·" i;uvcl fid,I a111l 11cuoi;raphic cviilcmc of ,·t·1 tical dilft:1er11i;1 lion. The llo,v is ;al,0111 lliS feel 1l1iik, ancl nc:Jr 1he lClllc:r i~ 1t·1ltli,h g•a). gr.a,liug IU i;1cl·11i)h g1:ay clownw.inl ;a111I "l'"';1ul. l'c1111i;1,1phiL ,lilfncncn ,.,ill be cliw:ussccl !Ju:r. The color cl1a11i;c ol1)en·cJ in 1hc 111:hl .. -,ml,1 appc;11 In be 1cl;i1ctl 10" 1lilk1c:111i.1I llq;1l·c 11( olliib1i11n o( i111n \,i1hin 1hc """·· \\·hid, i, proh;ibly 1d:1h:1I In 1d:11i1·c ,1111cc111r.,1i1111 of \·11l.11ilcs in the ll1t1,· cc:n1cr ,luring rnoling. Kera,oa•hrre flow b1cuias. Ol(llllius ,IS 1li,uc1c h\:1h, :uc pwh.1l1ly I\IUll' common th.in flows in the l.er.rtoph)·•c ,cquencc but .11e ,lifficult iu Ji,- lingni,h f,om llmvs. The mallill of 1hc: flmv brccti.u <;111 f11:1p1c11ilr 1,._. clis1_inguishcd fiom 1hc fro1t;rnc:111, only h)· c.1rd11l set ulin)' u( the 01111 ,up; th<· p;11111a of ,.,ca1l1c1i11i; ,~hi,h lOl'CU 1111M 1.eraloph)ics clfrui,·d)' ubsuun 1he line dc1o1il, nccc,.,:a1y 10 u:cognizc 1hesc rocLs. t'ra1;111t·11u in "'"" L1ccci.u ate 1ubans11la1 10 )ub1oundccJ. The mauix is almmt i1lcr11ic.1! 10 1hc: hag· menu in polished scuion; howc:vcr, 1hc 111a1rix ,~c:.11111:11 moic ,a,,i,11)· .. ,1111 in 0111crop a Row brcccia \,·ill ap~ar 1ongl1tr in i;1m, h'\lll1c 1ha11 a 11., ... A few flow breccia) comi,1 of bo1h l.cr1ophpc ;in1l ipili1e hai;mt·nu. One .. ~ 1· I \· '·· •, I ( I 98 •.--- ·- ' ·- CAllllH.AN ClOI-OGlCAL lNYlSllC.UIONS ~- ·-· ,uch occunrncc (s.1mplc: GSJ-2, near lhe wcu end of Grul S1. Jamu hbnd) i, a I00-(001-1hid. bed o( lcra1ophyre and apilite rubble with a le"' liint- 11u11c: fragments 1e1 in an apparently igneou, mauix. The minor recry11.111iza, 1ion of the limo1onc 1ugge11s a low tempcraaurc of extrusion. No conglo111er- a1e1 were identified within the Water lsbnJ Formuion, although m;my ftow brecci.11 hil\'c rounded u well u 1n1ular fragments and, when weathcrr.d, rcstmblc conglomerate$. a.·, o( .a.e.e (,a,nple ST-274, U1enlund, St. Thom.ii) \\'OUM undoub1edl7 be called I conglomeritc by most fid,I gi:ul- ogi,11, but unwc:a1hcrcd apeciWM (a1111d a 1l1or1 dist:mce caltwaril .along rhc mile sho,i 1hc igneous m.11,ix ,,c,1 clearly. Tulfa an,I ,·olcanic brccdas lonn minor buc cli~1incl units in the lorm;a- 1 ion. Tulfs (grain 1i1e lc11 than 52 mm) arc much more common than l>rccci,u anJ occur as bcd1 only I or 2 feet in thict.neu. None of 1he 11111 u11i11 could be demomuaacd lo have I horiaona.al ex1tn1 greater than about h;,lf a mik Gr.1di11g is \'isible in the aulf beds, allhough 1hb gr.1cling is com1npnly i111crrup1e1J by dia11cms representing the aciio,, of 1v;e1cr currc:1111 on ,he ,u b.>l101n. Slump strucnircs, geneHIIJ in the form of contor1t1I bc,lding. 111: uncommon. t.l.1ny aull beds arc silicilicd, ahhough the original l'>·rocl;,,s1ic g,011ndman b recogniaablc in thin section. App:m:ntly the origin- ally vitric g,oundm:us of many auffs has alu:rtd 10 line-grained mic.i miner.a ls; mu~co\;ilc i, the mm, widespread, and ccladoni,e and 1tilp11omdane ha,·c been recog11i1eJ. One of the bcit ci.posures of a Leratophyre breccia is on the call shnu: of bmcshur Bay, 51. John (sample SJ-7). Here a bed several mu of feel thick consim of angular fragmen11 of kera1ophyrc I few mm to S cm in a reddish, hem11i1ic mauix (Pl. 4, fig. 4). The hcma1itic matrix con1ra111 l\'ith the more neutral colors of most other keratophyre llows .ind tulrs in ,ihich hema1i1e is generally subordinate 10 magnetite. Diles and shallow plutons of keratoph)rc occur throughout 1hc fm111;1. tion, but are most compicuou, in tlae hills southwcu of Q,arlouc Amalie, St. Thomas (llaypiecc Hill, GramLolol.a Hill, S:ara llill, Cabritabcrg), in 1he vicinil)· of N.uued1 Day, St. Thom.as, .and in the vicini1y of llollman and 1\11. Zion, St. Thomas. (J\11 Zion iuclf, ho,vever, is 1m1lcrbin by ,11\0lhc, l)pc: of i111rmh-c 11xl.) These bodies commonly exhibit cnl11nm;11 jniniinR pc, pcndicubr 10 the cooling surface, ;md examlnalion ol the joints pro- 1·idea a means of reconstructing the alaape of the intrusil'e bocly. The hills around the Submarine lla1e on St. T11omas (Cabritabc1g, Giam- bokola, Ha)piccc. and Sara hills) arc underlain by one or two inarusi\'C bodies known colkctively a, the Submarine Base Pluton. The accompanying map and Kctions t•·ig. S) ,ho,., allat the lorm ol the intrusive body is irregular. The paucrn of join11 around llaypicce Hill strongly suggests the 1m."1Cncc o( an ina,~i\c tunnel beneath this hill. The ioint p:11mn bcnc:ilh eastern Sara llill. on the o,her hand. woulJ appcn 10 suggest aim Ilic Roor ol lhc intnuil c body is subhorizunral, inegulu, anti sballo,-ly dipping hcrr. The intrush·e-cxtrutive contact near a probable vent :u the southern encl of I ·- ·- -- ·- - -,( l. W. IIONNLI u·-H. 'IIIOM,U ANII )I. JUIIN, 11. ~ \'INI.IN hi Ar,;h, !l'I ~~o1ml,olob Ifill is 111odc:1.11dy u,-el'. On C1l11 i1.tl11·1i; 11111 il1e 11111111111.11 101nu ue 11c.11ly 11111 iw111o1l or ,l1.1lluh·I) dippini; 1111,·.11,I 1h.: ~o111ht·1 n •·11,I ol lhc inu1ui,·c: L01ly, but are nc;u ly ve11iul o1pp1oi,;i111;11d) JOO ln:1 11u1111 of 1be 10111111:rn contact. An ouccrol' of CKlrusi\C rod,, ni,l.-11tl) m 1,111 i11~ C : . : . a•.• ~o ~ '·. : . : : : .. : N I LINDI( •GH .,, (3a11 . .,;. .. [Z)o••u 8~L••""'••I I• D .,, . ..,,,,, •M•v•••• le,h D······ .. "'· ,. ,. I IO .J' .lhtw.. et tll_,.At, h•MI ~ I ... .C H,are,._, ... Alt•reh .. ..... Lt .... II' •uo ... ••- H ................. ......, .. ......... ·••ta••· ..... . .. ,..,Hr ...... ,.. .. , ........ " IOOO ff•• & ~,-~~?-L~~·:_·~:7~_.! I . I -· -~- . - ------ ---- fic;ua, J. ~bp au,I uou 1c,1io111 ol'1hc S11L,n•1i11c: 11.o,· plu1u11, ~• ·1 '"'"'J' k, 1, 1 1., l'l~tc I lo, louliuu. juu unJc:rnea1h 1hc inumh-c: h0tly, ca11 he ,c:en along 1hc ,lt111c j11,1 , 0111 1, of Ille Caribbc~u ll~>tll. ll1:1c: 1hc i111ru,h·e boily ,~;is prob.iLly lc:11 1hroogh a sleep conJuu .al 1u 1ou1hc:rn cml, .in,I 1prc;ul no11hwJrtl .,, a 1011i;hl) conformable shi:et. It i, 1101 known whc1hi:r or 1101 thii. i111111,11c h0tl) connecu witb the 01he1 one :.1 ,1,allo,v Jcpth. . The occurrence of intrush-e lcralophyrc in 11101k1 Jlcly b1i;c lu11lin ,,,. ward the top o( the ,cction may rcllnt ;a 1uli1lc upw:iul ch:ini;c i11 1i1holoi;); I -·, 1._.: :,-. .:. .+:- ,·--- r --- ( lit CAIUIIEAN C[OLOGl<:Al INVUTICATIONS iure op1io), and rare bio1i1ic miu .and a mafic mintra~ whid, has ah_crcd completdy 10 a line grained, very red subua~ce. 11111 could. be. enher iJJingsi1e. lx)\~lingi1e, or some 01htr clay mmeral or combmauon ol 111inrrab. The glau lragmenu han ,tilluse ou1lines and ,011"1 be ,h.a_r,ls. Jn no case, hoh'CHr, has 1he degree ol prcserva1ion revealed 1~1c 0~1hncs 11( the original glau hagmcau. The appearance ol 1hcse beds Ill 1111~1 sec- tion is ,e1y simibr 10 1hc allfHlf le\·iarilied 1ullul'o11s bc,b lom~,I Ill CX· plosive rh)olilic suites,, but ,hrit nplosive origin is 1101 cs1abh'11c:tl h)' 11("11ographic cvi,kncc. IIIAllCIArlllC VAIIATIONS The Waler bt.m,l t·o1111a1io11 ia icmarbbly 11nilo1111, coe1~i11ing &111011gh- out ol ;ibo111 one fihh ,pili1e and 1he rcn1:ii11Jcr lc:ra1ophyrc. ·1 he lower 11~1·- 1ion of 1hc: lorm,uion seen best al Ram lfead, 51. John, and Otl G1ca1 St. J,uncs bl.ind, comi11; do111in,1111ly ol •!•icl le1a1oph)·~e 1101~1 with i11u:r• ula1ed spili1es. Breccias and py1oclasuc rucls a&e mmor a!,d lorm only ,uy 1hin uni11 wilh a limittd la1cral exacnl. Tlic "l~t>Cr poruon of d&e for• ma1ion, seen best in 1he 1·icini1y of Cl1;irlo11c Amahc, 51. Thomas, and ~• \V;a1er hland i1scll dillers principally in the grca1cr pen:cnlagc ol pyroclasuc uniu. ,\1ounJ 1hc inuush·e bodies of llilypiecc Ifill, Grambolola Hill, a,~1 Cab, i1abcrg. 1hc lot 111a1ion is dominantly pyroclaslic, with only a few 1h111 L.eratoph)ric no,,s. On Flag llitl, _sua1ig1aphic~lly sl!gl~1ly_ lower than •.hcsc p)rocbSlic ,ocL.s. a milingly duel pyroclasuc umt II mrercalatcd m a Jominanll)· no,v ~e11urnce. No mineralogical dis1i11e1ions between 1he lower ;11111 upper l'°I lions ol 1he lorma1io11 can be: scc:n _except &hat near. the •~p ol the form,11ion dte1e is one occurrence of ohgocbse and albue 1v1d1 high-1empcr.11urc optics, and 1hcie arc llncc occurrences ol albitc 1v~1h op1icnvhich dC\·i;11e significantly from 1he lo,v-tempc,amrc stale and winch have been called quasi ro,v-1c:mpc1;a111rc optics (Donnelly, 1965). [NVIRONJ.l[NT The mO\I 11riling fc:a1u1e of the \Yater bland Forma1io11 is die. co~plctc absence ol tcrrigcnous sediment: 1he entire exposed 1hlclmru coimus ol volcanic rocls only slightly reworked locally by "'alcr. Tlac acc011d irnpo•·· 1.1n1 feature of this unit is that most ol 1hr volcanic roch, except lor the 11ppcrmos1 5 per cenl of 1he lonnalion, are Hows. The py1oclas1ic 1och 1hemsclns consiu cn1ircly of relatively equ:ml, angular fragmcnll, and 1ha1ds or pumiccou1 fragments are not scc:n. The c111icKelll eruption of ;ipparen1ly h)du1c:d magmas must indica1e 1ha1 1hese magmas ,vci~ erupted unJer a confining pressure of supcrincum~nl ~a war~r a1111rox1- ma1tly e•111haltn1 to 1ha1 ol the dc:c:p-sca bouom, 1vl11ch II sufficic:nl lo pic- vcn1 1hc "l•losi,·c expam,ion ol a magma1ic gas ph.1sc. llydr;11c,_I m;~gma, erupmJ in this c:rn·ironment will upc:rience separation of vola11lc1 tf d,1c ( I ( T, W. llONNllLY-ST. TIIOMAS AND Sf. JDIIN, IJ. 5 \'lllt:IN M.ANDS 115 p:irtial pressure of these vola1iles cx<c:e,ls 1ha1 of the sea wo1ll'r (;1ho11t 500 aim al 15,000 feel). The expansion ol 1hese vob1ilrs, ho1vc:11er, will bc ii, ihe order of a few limes, not many 1ho11sand limes. as woultl be thc: c;ue if lhl· magmas were: erup1ed subacrially or in shallow walc:t. Al,lss:il ppocbs1ic roch will not be formed by explosion t,lll by 1rla1h-cly 11uil-1 n,p.11uio11 ul vol:11iks and s111Men ,hilling 1,y se;1 w;11er. nispers.11 o( py1nd.mi1 h-•!-:llll'111, will prohaLly be effce1e1l by ,low·moving bo110111 rnrienu. 111 cu111rt1iH: curren11 ini&i:ueJ by 1he rek;1st' o( heal in1n 1he sra w.urr. ·1 lie ahsl'nce ol lcrrigcnous Sl'1li111c111;ary llll'ks imli1.11cs 1ha1 1hnc: ,,·c:JT 110 r111ug1·111 i)l.11111, ,vhic.h coultl h;n·e ,ervt·cl as 1l1c: sourrc u( w1•;11hnc,I cl,·11 i1m Sh,1111• Slmclllres or 01hu evitlt·ncc:s of 1lc:posi1io11 011 sloJleS arr t"n1·111 hut all' nol ab11111J;1111; in con11:is1, near 1he lop of the rou11a1io11 1hc:1e arc Se\"l'l,tl 111ilin1t occ1111encrs of e,·enly la,·ercd ppocl,u1ic L.rr;lloph)lr ,~i1h no bi:.! ding di,1111 l,;1nccs. E, idcnil)· 11th for111:11ion acc1111111la1c:d 11111 0111)· in :1b)·\ s.11 dep1h1 b111 also on ia1her liar sea l,11110111. The a1•p1·:ir:1111 c: of sli,;htl) more explosil·c Cl 11p1ivrs onlJ ill 1he l'ery 1np or the Fo, 111a1 ion sl1111,s I hat 1he sea bottom m:1y lt.l\C bcc:n subsiding ,luring the g1ea1t:r p.111 o( 1he ;1~c c11n111l,11ion b111 1h,11 111bsi1kncc: was 1101 ra11iJ c11011i;h 1e1 111;1in1:1in a co11- 11ant ,valer le,·d al lht' crupth·c ,en1c1 u( the acc1111111la11·1I , 11ll,1nir dq10si1 Allerna1inl)', regional uplih near the encl of \\1alrt hb111l 1i111c coul,I h;,u bttn rcspomihle lo.- the ;ipp:11e111 ,l,allowi11g of w;1tn. VIRGIN ISLAND GROUP I.OlllstNIIOJ tOIIM.\llor..: lnlrod111IU1)' J/11ln11c11I. IJ111011lo1111;1ltly mr1l)in1; 1hr \\".,1n hl.111,I Fo1ma1ion and cropl'ing 0111 on ahoul h.ill 1hc la111l ;nl'a of S1. ·1 hom:is aml 51. John is lhe i.ouisl'llhoj (l.oo c' l.111 hoi) Fo1111a1i1111, 11.11111·,I Im exrdlcnl CIIIIOSUICI in ro,acl cuts in the ,·idnity of l.1111isenhoj. j11\I no11h u( C:lic11lolll' Am:ilie, 51. Thomas. fl"~i~ •.!!!c~~J!~«;n,e is p1c:,lo111ina111I)· au,;iu: a111ll'si1,· ;incl v;iric~ !~• mocl~ o( depos}1ion hom 11,-rocl~•~1ic III epid.1\lic The 111;1xi- 111u111 appa1c11t 1111,lnc,s 11a,·c1"·1I is .il1011I U,000 ln·1. Lut ;1 1l":1\onahlc: corrcc1ion for le111i, 11l:iri1y 111i;;h1 11·1l11tt· 1his co111p111c1I 1hicL.11ns h)· a 11,iul or mnrc:. Cine (INil) tallctl thi, 1tte"L. l)'lte "llluc lk;1ch" ;111111hh 11;11111: "·" ----,···· p,11iS1c:1I: .ill or 1hc 11:uh·e, 11f 1h1· \'ii~i11 hl:11111, :ill· l.1111ili.11 "i1li '"IU111 lli1ch'' or "Hine Hit." The form:11ion is 1hicle11 ;11111 almou e111iiely I')'°' l.1,1it (lu, .,111 ll'h 111 le,I tul beds arc considc:1c:d enc:ntially pyrocbstic) in wc,1,111 S1 Thom:n. In eastern S1. Thum:1, 1hc l111111a1i1111 h 11111111 1hi1111n ( IOoo kl"r) .11111 i, 111111 posc:cl .tlmust e111i1dy ol inane ,l11111pe1I a111l 1c:1rn1ll·tl I'>'"' l,1\lii ,ld11i\. proLabfy mi1:in.1ti11J: horn a '111.1II "'L:u·iial c11111:. In 1,·,·,;1r111 'i1 fol111 rlie formal ion is 1hi1 ll'r (7000 ln1 111ini11111111) ;11111 c 11mi,1s p11 ,ln111i11.1111 Ii· 111 co;auc c;oue 1ld11i,. l'ii;1111· Ii ,111110 ;111 inll'I 1'1e1:11io11 ul 1h,· u111.li1iom "hi, It irsuherl in 1hi, 1lis11 ib111io11 or toe._ •tpcs :iml 1hi, l111·n1·, l'.>i,kn, c f.,, 1111· ,-- ,--. ·-- I t ( 116 CAllHlAN ClOI.OCICAL INVUTICATIONS Cl. la.I :::Ez ::, 0 Ju 1/J :::E wo en a: a:u.. cC o en u~ u.m t. OW 0 z w 0 ~ ~ <( :::E i a: • 0 0 u. ji ti 0 en z ~ ' . <( • iii i I ..J 0 en Q. u • w 0 u a: t; bl ... l ,ct <l • ~ .,J u , 0 t a: .. .. E __;, >- C r Q. • I -~ .i 0 • T ~ Q ,- - E ~- : ~ .. ~-'· j, - § t-· ti ~- I - ! 0 ..r.::. - E ·c - .. I - - i 'I I ; ~ i ., ::s .,, ~ ... 1 i ·= I ] .. !I .. :, .,, i -. .;; i "') I 1 ~ .. I :::, (:) .... ~ ,ii en t l&J ..J )., - ~ :::E I ..., .... I ~ u l: li !j j:, t= ),,. ~ ~l )., '!I ;e: !~ ~ g II (:) ... i Q) u - ( - - - - -· -, ( T. W. DONHUI.Y-ST. TIIOMAS AND ST. JOIIN, \I. 5. \'l'RCIN 1\1 AllohS 117 pos1ulated Pillsbury Sound eruptive center is based 011 the coarm1eh ol \'olcanic ejc:ct:a in nearby wcstcm St. John and eastern St. Thom:u, on the presence in Pillsbury Sound o( a dioritic pluton, and 011 rht 11ccc~sit)· ol limling the 11c:utst 1caso11.ible source for the lithic h:1111en1s in 1he Lo11i\e11- hoj fo1111.itio11 o( western St Thomas. In weste111 S1. Thonus (15 miks hum 1he presunit·d r1upth·t te111e1) occ.isioual augulu hlocls 6 i11d1ts in di.1111- Clc:1· are fouml in 1hc :uh bccl~. ,\hid, 1hc.-111sc.-h·t·s 1a11ge f10111 lim· 1111f 111 fr:igmenu :about I huh long. Tl1e coahe cone dd11 is is mou su iling i11 wcs1c111 s, lohn ;11111 t.1)1l•111 S1. Thom:u. In l\'Cllc:111 Sr. John ·I foot blocks ol 1vl1at llllht h;l\c ltc.·cu s11b.1c1 ially dt1,usi1c,I ;uh hom lhe 1101,c:s or the cones a1c loi1111I mii.cJ in coaut conglo111cr;i1ic brtls. Nra.- M.inJal in ea\lcrn S1. 1'1111111.is l.11ge hai;- lll(tlll o( what 11\ay h:a,·c been :a mliarri;1I ;1mk,iie llm\' ;uc ~ccn in b11·ui." of debris rro,lcil hum tht cone. ,\1 one h1lali1y lia.:111enh of 1101V up 10 2 (rec long rcsc in a m:111ix of fi111:1 nutr1ial. Many of 1hnc h;1g111t·11h L10Lc ' apart just 11rio1 to c,•ss;1tio11 or u.iml'oll, and their L1olcn 0111liues c;m l,c m:uchtd in 0111cmp. This is tlu: 0111)· p1oh:1bk lloh' 111,1tc1 bl itlt-111ilic1I in 1hi1.lo11na1io11. At the type loc;ili1y the loin1;11io11 consiu1 domin.111tl)' o( Lech o( 10;11 ~ andrsitic tuff l\'hirh, lile mou of 1111: 1111r srcu. w;n ;1l'l'a1c:111I)· w;1tc:1-lai,I. The beds arr 1n1ically 6-12 lctl 1hicl a111I ha,c l.1i1 g1;11li11g ,d1h the w.11\t·,1 ma1"ial (rarely coarser th:m about 5 iru hrs: a kw 111111 ls to I fo111) 11t•,1r 111, base. These bc,ls commonly show bmin.ir sl11111pi11g (!'ii;,. 7, II). The 11111)1 miking fe:11111c o( this 1l11mpin; it the ah111ul.111lc ol '"p11II ;1p.11h'" ;11111 the frcq11cn1 intc1111p1ions ;uul 1c1tis:1ls ol 11,c g1;uli11i; ·1 Iii, l.1111i11.11 slumping is a \'l:ry Lh:aracu:ri,tic fc.-a1111t• of rhe l.011i"'11hoj 1'01111.11io11 an,1 ap)':nently lo1111ed :is follo,vs: an ;1\h foll \\'as <lcpo$ilr1I 1111,lc11,·.11n (hi-; 7,\) on a slope anll dc\clopcd fair guiling, inteuuptccl ou·a\ionall) 11) a l.11gc: angular bloc._ ,.,hich dcl'rcs~d the hc,ll!ing bclo\Y it. The r,m· a,h 011 lop bcca111e col,csfre more rapidly th;111 di,I the co.auer ;,~h bdo,.-. The Ith cohesive, c0.1uer material bclo"' slu111ped (Fig. 711), rarrt·ing on ir ;incl c11- \·elopi11g within h fragments ol the more cohesh·c, li11cr-g1;ii11r1I m3ttii.,I above. The flow was rarely npid enough 10 become 1U1hult·111: 11,c p11llc1l- 1par1 beds hne ne;uly all 1c:t;1i1ml 311 orientation parallel 10 the bc,hliug. During this process o( slump the gi:uling lost iu original .111:1.ugcment, :111ll tlie coarscsl m:i1e1i:al is commonly found som"vh:it ;1bo\·e the l,;1u· o( the unit. Additional c,·iclencc lor ,te11ini1ion on a slope is 1lu· llt':11 I) 11l,i1j11i1011\ slump urnclurt) 1er11 in li11e-1;1ain~·1I tulls in the: lorma1ion. Purdy pyroclastic l,c,ls are 1101 always easily 11i11i11g11hl11:1l hom rnll hnl~ which have slumped and hom beds which have been 11101e or lcu u-, .. o,lnl by w;1ter currenrs. Co;iiser ,,,·1ocb11ic roclts usually rxhihit 1hr fi;1g111rn1 angularity, lhe u11iformi1r ol li1hologit·s, and 1hc app;11c111lt· ig11t·1111s matrix wl,ich one associates with a\h 1lcposi11, ,,·herca1 liner ash l,1·11s rc- 1emblt volcanic 1vacle. The over-all 3\pcct o( this formation s11ggcs1S u1 i.il transpGrC and subaqueous tlcposirion or Pl roclauic 1kb1 is. T1anspo11a- -· ( 120 CAalaauN C[OLOCICAL INVUTICATIONI Cobo l'oinl Co11glornnolt htl1ofocitJ. Near the base of the formation in ahe ,icini1y of C1111 Bay, St. John, :ind C;1bts Poina, Pearson Gardens. :ind ll11nlc1 llill. SI. Thomas, conglomen1cs :i,e inlt1brdded wi1h andcsi• aic 11poc:fas1ic and tpicl;u1ic 1ocks. Tlu:se conglomr,atrs coosist almost t·nti1df ol \\tll-101mdttl \c:11101,hltc cohltlu aml IK:bbles dtrivcd hom the undc,l)ing \\',111:r hl:111d Formation. At Crut lby, ho,~enr, these conglo1n• er;it(S arc more or lcn 111bu:11I with 1ndesi1ic deb.is, 1ugge1ting ahat sub- .icrial erosion ol 1he cone dcposiu and that of the 11111lerlying kcr:itoph)·tc bcdJ were simullaneous. At C'.abd Point the conglomtratc is composccl of .. cll-rounJcJ and (;ii1ly well-sorted kcratophy,c and spilite ,obbles :ind pd,blt:s. Thci.e conglomea:ile bfds arrear to h;,ve IKen de110sittd in sh:illow waler, and ,.-ere not pro,lucll of tubidit)·•cnrrenl def101i1ion. They :ue well sorted, arc nol gradtd, and line rcbtinly liule matrix. Their pruencc i11dicate1 sub:ic:rial erosion, uanspo11. and deposition of older rol:ls duiing early l.ouiscnlmj time. . 11-'dftr Jda11J-l 011i1enhoj co11t11CI. There arc fe"' places "'here the ,u111,u hc1w1:1:11 the Water ht.nd and l.oni)Cllhoj t"ormations is well e"posed. In St. John there is om: ucc:lknt uposure of the cont:act along the west shore of Monte D.,y. :md there :ue poor exposures al Klein Hay. The cxpouue 011 Mo111c JJ;iy shows a co11i;lo111er:a1e ol tl1e l.ouiscnhoj o,·crl)ing a spilirc bcJ. The spilirc is quire lrcsh at the conlact, and rhc onr• I) ing conglumeratr cont.iins :a wi1k anonment ol Water bland lithologies imlmling. howe,er, ,·cry few rocks identifiable "·irh the underlying spilitc. At Cahary Day, St. John, there is an expos111c o( a conglomuarc or the l.ouisrnhoj form;ition o,·erlyini; lcratophyrc. On St. 'lhomas the cont:llt inclf is poo1ly cxpos,d. b\ll :in ci.tcnst\'C ex- posure of Loui~nhoj beds above the contact at the headlands between Brewer's Day and the airport is of great intcrcsr because o( the extcnt of apparently contemporaneous wcatl,cring displayed here. The Louiscnhoj beds here consist dominantly of suhurially, varicolored andc:sitic ash inter- bedded with conglomcratic Water Island detritus. Some of 1hc ash units arc brick red and consist solely of albite, hematite, and a little illitc (X-ray diffraction). The albitized plagiocbse phenocryst1 evidently withstood the weathering almost perfectly, but the tmirc mafic p.,rt ol the roe\ has been con\'Crtcd to oxide. Otlacr 1111i11 consist of varicolored fragmcnll ranging hom dccp red to grt·en, e,·idcntly rcftrcling differential susceptibility 10 weatlter• ing. Still other unh1 co11si11 of greenish or grayish fragments in a uniformly pu1plish m;iui,c. Tl1e basal 1ub:acri:illy wu1hercd unit is less than 100 fut tlaick and ,,·as lounll a, only this one locality. "l"he color of the btds sc,me1.,hat rcw:mblrs that of the weathered hydrothermally altered rocks (diKuSkd in a following section). but the bncr gra,le into whitish unwcathercd rock wi1hin a Jci,, feel o( the su1face and arc 111incr:1logically quite 1listinct. The Cllltlll ol tl1is ,~cathcrinx i, complcltly unli'-t :111y 1ecc11t wcall"ring o( any 1ocl t)pts in these islands aml 1111110111,rc,lly rcAcrlS 1vt;11heri11g conte1n1,01:a- ncous with original dcpcnition. ( I T. \Y. DONNlllY-ST. lllOMAS ANII ST. JOIIN, II. 'i. \IAGIN mA,ltS l'.!1 Another occ11rre11ce of co11rc1111)1)1;111co11, "·r,uheriui; is 110,11 I) t·,1111>c1I .11 Wintberg Hill, St. Thomas. ·1 he poor ualllral 1::1.pow1 n, "hi, h ;1 11: of liglatly me1,uno1phost1I rOl:k, Wl~l c 01 iginally 1ho11i;l11 111 ht· nl h) ,11111hn. m.1lly ahcaecl rod,. llowtvrr, tcu·111 (1963) oc;11·;11i11m 1111 111.,,l 111m1111,1i1111 rcvc;1lcJ the originally \VC:1lhc1c,I 11,1111rc ul 1ht·st· ,.,, \.,. Mintrolo,:y o/ rnofic /rt1g111t11U. The pi im ip,11 111i111'1 .,1, 111111111 in 111.,111 fragments arc plagiocbse, clinop)IOHIIC., t.101 i1c, aml p11111ptll) i1.-. ;111,I :,1,., m;atrix a111I opaque mineral,. I 6 HAIVSI LOL (.II( ,.,., 0 ruru, FM. c:::> 0 I OUTERI BRASS LS. 0 ') I 0 I • 0 1 0 • 0 ~ IMony 0 ~ LOUIS£NHOJ ,.,., - I Q Sompln 0 I ,., I -Q ~ • Q Spilitirtd Au9ile Anduilt ~ I I ,-. ) ~ :,,-, )-, '"r- .... Ano 0 • Monr WATER Sompl11 ISL ANO FM. An40 LT ond QLT (Donnelly, 19631 oplics HT optics 0 0 0 Aneo ,uc1ocusa:: l\losl phenocryst\of the Louisenhoj andci.iln arc lab1a,loii1r. about An" (Fig. 10). Near the base of 1hc formation 111;1ny l')Wd.,stic rotks con1ain a distinctly more calcic pl:1giodase (An., to about Anv:)- Some o( these pyrocla11ic rocks contain both bytownitic and bbraJoritic fragments. but a few contain only bytownitic (or ano,thitic) fragmenu. The M,lspars alt aharplJ euhcdral and slightly toned. They ahow ab11111bnt simple 11.-inning :ind some albite twinning. C1oun,lm.1u plagioclases :and pl,1i;iodascs in 1hc matrix o( coarse pyrocbuic rocls arc ,·cry fine g1:ii11c1I ;11111 cloud)·. M.my are dis1inctl)' more soclic th.in the plicnocrysrs a111I range in c:ilci11111 c1111lt·111 down lo An,.. In many lapilli lulls. the only lclJi.p:n 1011ml is all,i1c (An1); t ( c· r- ,-- 170 C'.AalBBl:AN &1.0I.OCICAL INY£fflCATIONS com110,i1iun u( 1he more siliceous dilk1e111i:11cs. The cxperimenu of Yoder ;,nJ Tilley (l!Jti:!) d,ow cle;,aly 1h;it at w:uer pressures gru1er than a~u• 1000 l,;, 11, m.ucrial u( b:uahic: composition ahoulJ b~ converted 10 a 111111- lllre of ho111Llcnilc and pl,,gicKlasc at sulilic1ui1lus u:mpcra1111es. ~• the 1cmpcra1ure rises 1he material will begin 10 melt, with _ahc pl:lg~oclue Lt-ing comumcJ (Im. The lint liquids procluccJ will be lughly fd11c .'u11I 1iliceou1. 1 he co111110sition,I u,nd of liquids proJ1Ke~ at 1ucccn1vcly higher teml't·r.111111:1 hu nor ·bdti npcrimcn1ally clc1rrn1111cd. hnt ~ co111- p;uison ,.-i1h 1he analoeous procedure in anhydrous caaes ~e1•.rr.111on or basJh) sucge,11 1ha1 hornblende will talc the pl.ice of chops1de o1s the JominJnt m.ilic ,,ha,e being co1m1mcd during the grcalcr. 1,arl o_r •h~ mch- ini;. 1 he h)thous liquid might, therefore, be more enuched m 51 1han ,,oui.l coml'Juble lii1ui1b coc:xbting with diopsiJc: in 1he :mhyclro~•~ c.nc. ·1 lie elllcnt 10 ,d,id, rcaiJual hornblende migh1 conuol the: co111pm111on or 1111: liquids will nut be easily evaluated un1il these hornbltn~les can be ,ollccicd anJ analy1cJ, but this comideration might prove 10 be pivotal. The quan1i1y or keratophyric magmas generated is pcrh_aps •~e ~ly rully serio111 objec1ion 10 the hypothesis of gencrallon of tins cntne sunc~ hom tlic upper m.:uule. 1·1ie qu,uuity or siliceous rocb is ~nknow~, but geological inlc:rence (cxposeJ area of Water _Island For~auo~, ,.-Inch is about 80 per cent Lcratophyrc) combined wuh gcophysrcal mfor~ado~ (scismk rdrac1ion and gra\'ily) suggesi that the Wale~ Island Formau~n II a 1'1ism al,011t 5 Lm ,hick. e,-;temlin,: perhaps 40 lm m _an eas1-weil dircc• 1i1111. but 1p1itc possibly 1hin11ing 10 the cast, :and extending perhaps 20 lm in .i nouh s11111h Jirellion. This ,·olume-4000 cu lnt, or 5200 cu lm of lt-iJIOj1h)1e-h 1'1ulubly ;1 111;1,-;inmm, because ponible thinning 10 the t:J\I :m,1 10 1he s11111h ,us i1,norcJ in ahe ulcul;uion. H fusion of 10 per u-111 or 1111: 11111,c:r 11u111le might yiclJ a Ler:11ophyric liquid, then 52,000 111 lm of upper 111an1le 1,·t:1e fuse1I during 1his igneous epis0tle. I~ 1hc depth ur lusiuo \\'JS 10 L111 and 1he cast-we,, hoai,ont;il Cllltnt of fusion 40 lm, lhLn 1hc hflri,unral dimension of the fuse,l zone in a 11011h-so111h direction 1111h1 h;11e 1,.-cn 80 l.m. These fig111es may 1.te oil by au or1lcr or m;1g11i1111le or more, b111 1hey c·mphnize one problem: the gcnera1io11 here or siliceous m;igma hom 1he upper man1le may require the p.ariial (us!on o{ more ma• icrial than c:in clirec1ly underlie the ,·enl, tinkss 1he fusion exlenrlccl to great dep1h. The explanation for this setming paraclox is as follo\\'s: ~ming 1he orogenic proct"U compression and thickening or h)drateJ C.u1l,bcan crmt aml upper nranile carried 1his matcri.il in10 1he o~ogen _ho111 a co~- sitlcraLle disunce pcrpcnclicular 10 the axis of 1leprenion. 1 he orogemc 111Jgma1ic process tl1en can be compareJ 10 a mill 10 which is fcJ hesh, hy- 1ha1e,I "l'IK·r nu111lc, an,1 from ,~hich t1-to 11r0tl11c1S, m~gma aml nufic IC· ,i,luum, au: 11.:mmc•I. 1he lint 1luouKh asce111 an,1 crup11on :anrl 1hc seconJ 1hrnui;h g1;11l11al Ji,pbcc·m,·111 1lo_wm,·;ml ;11111 ~n:n111ally lalt"rally: The ., 111.,11111 of l.t-1J101'h~1e e1up1t·,I 1111i;l11 h,l\c 1t·111111e1I l:i1er;1I sho11e11111,; or .,IHml 110 l..111 in 1his .uu. The 1111,1111i1y or siliceous ig11co11, r0tl seen ht"1e i) f•r in rueu of ;my that has bten recorded in similar orogenic ,ones, and ( I I l I , --, ,__., '-', ( T. w. PONN[I L ¥-ST. TIIOl'IAS AND sr. JOUN. II. s. VINGIN ISi ANUS 171 the Virgin hlan,ls may IJc an cxlremc example of a p• oc cu ,.-1,ich has 0<. curred to a lc,ser cx1cn1 in m.my places al many 1imes. Clearly our knowl- cJge or Ilic composition of upper 111:11ulc is 100 li111i1i:,I :11 1his 1i111e 10 assn, this problem lur1her. 1 he wriicr (Donnelly, 196f) also poin1ed 0111 1h.i1 1he gencra1ion of a scconcl. ,uengthkss phase (aqueous, or h)dra1ed silicate mch) J11ri11g orogc:uic 1hickening would ha,·e profound s1rue1ural implica1ious. The ,·ol11n1e in which 1his f•hase w,11 gc:-ncra1ed wo11IJ become encr11i;1II) 11rcng1hleu, anrl 1he s1r11c111ral process would be ex1ic, 1ecl to change (wm a relatively 111il1I 1hitleni11g 10 a more "iok111 1110\'emcnl along an C:Xll'II· sive d1eu. The conse11uc11ces of 1his 1110\'c:111cn1 wo11l1I be 1ha1 1hc isbud platform woul,1 IJc raised 10 an emcri;nu ICl'cl. a111I 110~sibly an a,ljoinini; oceanic l1cnch wo11lcl be fonni:11. The elkct on 1hc gc11era1ion of igneous mehs ,.-oulJ be 1hat the raic of depression of m;1111lc material (;11111 1he rate of l1c;11i11g) sl1oulJ be: incrcau·,I grc:ally. Aller 1his profo11111I Hruc111ral episode, the generation of magma will IJc rcla1i"clY rapiJ, a11J 1lie propor- Uon of malic to fclsic magma high. The rcs1ric1ion of abundant siliceous magm;n 10 the early s1;1gcs or orogcnic evolulion is ,omi11e111 wi1h il1i) Idea. In conclusion, 1he following poi1111 seem well cs1ahli,hi:tl: (I) Two l)·pes of chemically uniform m;1gmas were genera1ccl 1hrougho111 1he span of geologic hisiory or these islands. (2) Thcic has been i111aa<1io11 of t:rupcc:11 magmas wirh the environment in 1he use or alkali cxchani;c in cx1rm,i1e lcra1ophyrn. Other possible exch:inges hnc 1101 bl·en cu.1bli~hnl. l'Xll'I'' llaal a few samples of highly me1a111orphoscd kcraiophyrcs h;n e hten i111- f>ovcri1hcd in alhlics. (3) The siliceous 111.1g111:n rq11nn11 11:111.11 y 1(.)-.-\I, (h) melts clerh·ed by pu1ial fusion in a clomi1un1ly so,lic cm·i1011111rn1. a~11I 11111>1 probably, in an en\'ironmenl wi1h cousi,lcrahlc: ca lei 11111. The l.11c1 bd1J, i11r of this presumccl calcium remains one or the impor1.i111 ;1110111alit·s Thi\ parc111 material. for di,·erse reasons inc huling gcoph),i<JI Jllcl cl1t:111ir;1l t·, i dcnce, is consiclcred 10 be "l'f>C' inanilc. (·I) The tnJfic m.igm,u arc chl'll1i ully si,nilar to so-called high-alumina basahs 1ypic1I ,,r orogt'llic rrgiom geneully. Tlic high magnesium of ahe spili1cs rt"sulu hom iu g,·11rr.11io11 ' from a material l.ugcly dcplctecl in iron by ab11rac1ion of lcra1oph) re (!i) The increase in aluminum wi1h aime and 1he higher 11111111.11i,c Ab/Q ra1io of ~he la\cr 1111:1111-:mdnine porphyries of the sec0111I group m.,y intlic:11c generation at increasing depth wi1h time. (6) Crystal se11li11g anJ assimila- tion of wall rock were probably of li11le irnpor1;111cc iu 1hc grnc1.11ion 01 differentiation of this s11i1e. SUMMARY OF GEOLOGIC AND TECl'ONIC HISTORY OF TIIE NORTIIERN VIRGIN ISLANDS The tcc1011ic c1·11l111i1111 ol 1hc l'11n1u Hi<11-Vi1i;i11 l,l.11111. .111·.1 1,.,. .11 1cady been discussed by 1he wri1e1 (Donnelly. 1!161). ·1 he follm~ing auo11111 s111nm:1ri,i11g 1hc: geologic: hi~io,y of 1he 11011hc111 Vi1gi11 hl.1111h cl11d1l.11n '-', ,_ ,_. r - -~ " ,---1 ( 172 C.:.Ul- ■[AN ClOI OCICAL INVtSIIGA-UIINS 1l1nc iJcJ, 11111 i1111111lucts 110 nci.• ,onccpu. Tin: major cau-,,'l"Sl fauh tllJu,cJ IJ1i;,I) hom gravity cd,lcmc ,~a) 1101 1t'Ct>J:ni,ctl :11 the time th:tl plpcr \\"JS prcp,.rc,I; howncr, iu oiHtncc rc1111irc, 110 m01lili,;11io11 ol tht· i,l,·.1s presr111c,I. The Ltrlloph)·1t·s anJ 1pili1c1 ul 1hc \V;i1e1 !.1;111cl •·ormation \\'CIC e~1111J1:J on a rcbthdy n.u 1<:a bo11om. as imlintccl by la, k of 1t:11 igl·nous ,ku ital sc,limmt a111I paucity uf ,l11mp ,11uc111rc, in 111011 111lfa1.c:011s 11nih. A nujor c:.111-\,·csl hii;h•1ngk fauk infc11c:J hom g,a,·ity data "';" p11tb· ;,l,ly the: lurns of u nption of tlwse 111:igmas as ,vc:11 ;u most of the l:11c:1· 111Jgm.u. M<>tcmcnn along thi, b11II 1i11111lt;inc:011s wi1h emption kcl 10 acwmulation of the Water h!Jml roe.ks in a b;uin with a sharpl)· 1kli11c1I 11or1hr111 edge. Tl1e1c is some evidence of shallo,ving of 1hc \\later lc:,·cl to\\·a,J 1hc end of Water hl:md 1ime in the: greater p1oportion of tulb,c:om Lc:ra1oph)1t·s :u the ,cry top of the section. The tnd of Water blaml lime was matkcJ Ly alm1p1 rmflgcmt, pu~ibly in part alo11g the majo1· cas1-wn1 fJuh no1c,I pre, iously. This mon:mcnl, as ,vdl as 111bscquc:n1 mml·mcnh along' this f.uih, "·as of :in op110)itc acme 10 the: o,igh1al mun·mcnt: the no11hctn siJc ,,·c111 Jo,vn. O,·c:rlying basal Louisenhoj beds we1c: 1lcposi1e1I suLacrfally ancl wc:athc:rcJ 10 lu1111 a brick-red soil complc1tly unlike an)' thll arc: fo11ning at the: p1c:sen1 time. lntcrcal:itcJ conglomcralcs of ptc• Jominlnll)· Lcratoph)·ric cl:ists 1vhich arc csl'c:cially ab1111dan1 near the: base: or the· Louiscnhoj sho,v 1ha1 there: was a ra1hrr pcuistcnt cmcrgclll ,ourcc :ura of oltlcr rocks cxposcJ at this time. Slow subsiclc:ncc: :1her c;11h l.oui~cnhoj time is rcRcctcd in the gr;1dual diminution in abund,mt:c ol co11slome1a1ic units, the finer gr.1in size or the r,roclauic Jc:110siu, ;11111 1hl"i1 reh·o, kcJ c1p1iulrnu, and 1hr inncasingly excellent gra,ling of the 111II bcJs 10,,·,uJ the top o( the lo1111a1io11. The onrlying O111cr U1a)S Lime• s1onc n-1uc~cn1s almost complete ,·olcanic 1111inccncc: and sub,icleme bc:111"· the le,·cl of cffcuit·c ,va,·e erosion of the: older rock 11niu. The: btginning of Tum time ,~as the beginning of rcnc,vc,I ,liffc1c111ial ,rrtical 1110\·emtnl, ,~ith n,·,vly c1e,11ecl o.- 1ej11ven;11c:cl ••ccp 11111,c:s ,hccl,lin,; ,,;,cLc:s intu water of 11111.nown 1lcp1h. t::mc:1gcn1c of (t:111 of 1hc wm,c arn Is seen in the abundance: of parti;1lly wca1hc1cJ Loui)Cnhuj lrngmcn11 ilmong 1hc: Jc:u-ital component of the Tu111 Fonn;11io11 a111I i•J 1hc i111e1• ula1c:J blo,L.s uf fossiliferous limc)lonc: of the CuLi l'oint ~h-galncrda lilhofacics. ,\ b1·icl pcrioJ of 11c;11·-c111e1gcncc i, Ken in the C:oni;o Cay l.imcstonc Member. The 1ccry1ualli1a1ion u( this unit is too cxtcn,it·e 10 ha,c prcstncJ an,· of the di:ignos1ic 1~1rog1;1phic n iu:1 ia ,,·hi, h might hate rcnalt:J "111ltthin~ ol hs c1n·irnnme111 o( dc1M>si1ion, bnt ils mauit·c:• nc~~ and m·;ul,- 1,111e cal, itit: 101111Ml\ition ,l,m,·, 1ha1 it 11111\I lu,c: IM·rn a bJnk dr1•1"i1 of 111:;uly p111c skdc1;1I tlcb1i). . llc:ncwc1I n1lc:inh111 :ifu.-1 Tutu 1i111r i~ ~n·u iu 1hc 1hic L :111t;ilc ;11111,'!l,hc ,,,1ocl;ntit: r<Kls of 1l1c: 11:ms l.ulliL fo1111;11ion. Minc1:1loi;ic:ill)· this ;111,lcsitc ;1ppcan 10 l,c i,lc111i1.:1I 1111h;11 of 1hc l.1111i,c11h11j fm111;11iun. l'ost-lfans l.olliL fo11na1io11 hiuo,y i) 11l1~111c in 1hc Amcritan i~lancls - ( ,.._ - -- ·-,-~ ~ I _·-,--L ' ·-- -( 1·. "'· IIUNNLu.,·-u. -UIUM"S ANII SI. JOIIN, II. S \'lkUN 1\1 "NM I 7J ,md has Leen trc,11r,I in mo1c ,lc1ail L I . Vi1ci11 ldJ11,I,. A ,late of l\li 111 1: y lthlcy (19h11 rl11·,i\) in the lhili,h . I . ' 1 c 11tcnc nl·ar 1h,· ,01, f I ·1 11011 (1v 11,h indutlrs 11,c II· f Ill . . o I ic o1111b l·u1111.1- lllt·111hn, i11 the llritisl, i I la)II) .. Lot·' l·or111a11011, c.1llc1I h) lkl.lq ,1 V. • ' ·1111 ) c:,1.1 1,hl·s 1hc 1g. f I 11,:111 hlau,h G1u1111 The I .. I I 1· .. t " I ic Uf'f'CI I""' of 1111· I ·1· · ,ui;, I.II 111 nh 111 1lu: II · · I · I I · I IC: 011ul.1 1:01111 Ilion . I • . 1111' I h ,1111 , 1111111, In f , . · ant " ap1•,11c111lv crn11. I . osuhlctum Nctl"r L· • , <" 111 " 1L111r11us ,,·uh 1h,· 11.,11 . ~ .-01111.111011. lloriw111·1I fortes r . . • 0 any oric:111.111011 111 sens. . 1 1•b)·t1I an imi,011;1111 iolc al ·111 . •. . <" c,1111101 Jl" sl111h11 lo 11.111· Nc:a, ly all lhe SIi IIC1111al rd·;11·0)'1,'1'·'.Gt ,11111111.; lht· n·of11111111 ul llti) ,lll".1. · • ' ' "I'' 0 )\l"I \'l'tl · S · ·II . I . 111a11g1a1,l11c di;u;illn of thc w,l . • ·1 hl as 1 1c ph),ll.el b .. f 1· u1111S,1;1nLen1111ct1)il1· I. I ;uis o , 1Uc1c:111ial H·rti . I · t'lll1 ;1111e1 1111 1he < ,I 1110\'l"llll"llh. 1\(;111v f· It I· . . such 1110,·c:mcnts ou 1111 ,. I 1 . , ·111 I 1 .mes ;11 u1s) ,.-,11, h I ' IIIJ)' i;n•c: co11111111c,I to I . cl I · I p ueme1111 110111 C:rct;1ce1111s lo l'a1 I. T. . . ic u: uc, u lauh ,Iii• cut.• > <"ll1.1ry 111111', ;incl l'l·en 10 1l1c p1t·\· The p10Lll·m of rhe gc11c1:11io11 of lh . . 111:11 or lhc Sllllt.llltal c,·011 11· r I C IIIJGlll:as u lllci.11 i, .,l,ly liulnl ll'ilh • 011 o 1 ,c :a1c The . . 111.igmas is consiclerc:d 10 hav. 1 · grnc,auon of :ill of 1hr • I f • c 0tc11uc1 as a re,uh of 11 11:a us,on of h)'dr;uc,I llf1pcr m:i111lc '· I . . •c more or Ins p;n. fo1111d Lcnc:ith rhc C..;i1ibl . S . . d111.11c11.1 • tdc1111Cal lo th.11 f'lcsi:1111) •·-I ,un ca at q,,111 Lc:n c: , 1 1 uc 011· the: sea floor Thc laror , 1 f . vc: 11 :, ;m, :, 111 20 L111 I · D ·u 11111c o siliceous ll· • 1 I enc.·, ci.1c111, lhe ,·olumc of lacer nnlic' l . r:a op l)H·. ;uul lo ;1 manllc o,·cr a ho1iro111al extent . · 1 uc.b s, tc11111,n •he fusion of "1'1••·1 • comu c,a ly grc11rr 11 · I mtnuuus of rhc o111nopping roe l units H . . i:an I ~c PH'St•111 cli l1yd1a1c1I 10 10 15 L ( · llic fuswn "'•15 l111111ccl 111 1l1t' • 111 0 11flf'Cf 111.11111c 1hc:11 1h. I 1 llon for the: 1·ol111nc uf m.igma eri1 Heil i~ th c_ on y a, c1111;11e npl.111.1- (>0rtc:d adjace111 unfusccl n1~ ,11 _I I at ho1uo111.1I m111·c111l'llh IL11h I • .. 1 c: 11110 1 1c orn..cn , ·h . · 1taIcd, partially fultd and 1he11 i1 f -D ' , trl' II \\'JS tl,·pu·,s<-11. dowuwa,d and lattrall;. • s fl' I :u 101 )' I ni<l1111111 ,,, ·Id)' 1li,,,l.1n•,I ~lie: c,•oh11iu11 or this l'Ollion of the \\'cu I .. . . . . uf Jllllt:tf>O'Cd, physirnlly co11n.u1i11 • ,l-11cs u, in u l,.1s1ully lhl· 1cspo1ht' an ap11lic:d l1ori,ontal force. 1-·:iihu~ :,,;,n, ~r .'~ 11~1 .in,I "l'l'l'r mantle 10 rcsultcJ in thidcning and downw:11 ,in, . S I ,c. J~•~• 1,l·t,vt·u1 thnc i,la1n lime), folloll'cd Ly <0111111c'5it-c (· ,·1' C '," 1lf1c m111;il Haccs (\\'a1cr hlan,I f I ,I IIIC, I IC or111·11in11 1 f · • au t 1)'51l'III, and ra1,icl IIJ>lih '·I . I f ., . , .1 111:JJor 11:n·He (lo . • , llt I o1 mcu an c111c1 ,, . l . I I I 111sc:nhoj time) ancl, 111051 ,rob LI . . . . .,c:n_ h ;1111 I' .11101111 applica1ion of co1111,.-cuh·c f~rccsa. )', a111ra<l1n111111g orc;1111c llt·n, 11 l-"1111h1·1 c,unt·c 1111her 1hi l • · I • e111c1gc:ncc: or the islan,I I I if 1.1 . 1 (11111G ;1111 , 1111111111.-.I I I I , ·• oru1. ,c,c Iii no c . I . I • am s that submergence of . , " l·ncc 111 • ll' \'i1 gin Island time:. lf:1gma was gene,:,:~ t:r~1111udc. C\·cr occ1111etl ;1hcr \\';11n mantle:· the ·pronnr1io11 f ·1· y I ,c 1'3111:il hnio11 of h)tlrJ1l·1I "l'l•t·1 ' r- 0 11 1<c:011s and mafic 111. . . . the rate: ol cldorm:uion and the .. I f . ag1~1.1s .,1 an>· lllnc it·fl,·, h 11 ,a c O 1c111pc:ra1111c 11sc. IC c::istcrn Grc:itn A111illcs is a u11ic111c ••111·1,1·1 I I -~ 11 1 1r s;,li,·111 fr.11111n --- - ·-J '--J - - 17-1 C.\alllLAN ClOLOCICAL IN'tUTICATIONS ul 1he c.111h'1 i,IJnJ arcs. This area has ncvtr been bhinl.ettd with the 1hi,l 1enigc11ous ac:Jimcncs "·hich ha,c modified anJ lalcr guided 1he 111 uc1uul nolu1io11 ol mou 01ogc11ic regions; it rrp1c1enu ins1cacl the diiecl in1uaclion of oceanic c111s1 anJ orogcnic foaccs. The failure of 1hrse rods 10 hne been mc1anaorphoscd ;ind du:ir subsc11m:n1 cxh11111J1io11 i~ a nt·Jrly pri.linc co11Ji1i011 arc probably 1hc remit of ;a lucly gcologu.il .iccidc111-il1c dnelop1ncn1 of an eatcnsi"c 11ril.c-slip f.iuh s,·ucm s11111h of 1l1c isbucJ 11la1for111 along wl1k-h Wffe rnolvcd 1hc bull. of d~e pm1-[0tc1~t· ddurma1hc forces. \\'i1hh1 the iJ;mJ pbtfmm, the 1lo111m;1111 1t·t10111,· forces h:1,·c been Jilfcrc111i;1I ,·cr1iul naovc:111cn11 nmc:d 1,y 1hitLc11i11g ;11 dcp1h. Ahhoui;h none of the 1tr1Klural or peuologit: conclusion~ dc1h-ccl from 1his m1dy un nccnsarily be applied 10 ;my od,cr spce1fic uca, nc\'erthdcu ccr1.1in obscrn1io111 cannot fail 10 r.aisc serious questions con• cc:rning loni;-s1ancJini; ecological hypotheses which h:ive not been 1crio11sly tiucuioncJ i11 1ccc111 years. REFERENCES CITED lloc.c;IUI. 0. I. 19111. O1D D1111 .. •V~11inditn1 Ctoloai: Ccclt••ltk Tldllltlll, ltOII. Danll.s. Ceostaa,h. Sclllab, •· It, p. 6-11 (Trandatal bJ t.111. £ditlt Thcllc, Tonola. 11.V.~ .• and cun,incd by 1be writer) Do"n: f., 19!,li, Zoniliaci6n •lcrolaunl1dc.a cle IH c1ll111 ,m.tckH dcl tste clc t.ledco: Dul A-. l'.:llol Mu .. w. I. p. 919-117 Do•IN, N. 1.., a11d Tunu. 0. f .• l!JS0. The l)lltm NaAISl,O,-KAISl,O.-11,O: Jou,. Ccul- oCJ, • S8. p 48!)-51 I . llu,u,,.._,o,., A. t· .• l'l)!I, Gtanhc tmplae<n1c111 wilh 1ptclal nl•·Hll<t lo Nonh A"'cuu: A11 UM) tnic:1•·. Ctul. Soc. A-1i<a llull., "· 70, p. 611-741 Cu.u. Pu l1oi,ou, 1111. On the 1colU1J ol the no11hu11crn Wctl India bl1nd1: S1ud,· huhn, Kun,:I. s .. n,la \'e1c1111i..•Ah1I. ll•11cll., no. 12, p. l~I. -- 1191, Ou11int c,I the 1tulot) of the no11hu11.-1n Well l11di1 hl•11d1: N. Y. Acacl. Sd. Annah. w. 21, p. 115-192 CuaMLIUt, II. p, )ll~I. lur Frase dcr Abuu~l11r;u11dcn dcr Radlulasht: Ccol. ll11nd., I\J. SI. p. :!16-::21 Uu""uu, T. \V, 19;9, Tltc 1coloff ol SI. Thot1111 and S1. John, Vhsln hla11d1: !cl Caril,l,un Ccul Conf. Tuna. ft.bp1ik1, Pi,e110 lllco). p l~,-ISt -- 196:!. \\'•i1ali1e In l\'e11 Indian 1plli1k rod,1: A,n. t.ll1malu1hc, "· t7. p. 7!11-80:! -- l!JGJ. Ctnnis ul 1lt.i1c 111 ca1IJ oraccuk wul«anlc rocb: Am. Jour. Sd .• •.,:?61. P· "7- 972 -- 1961. £,ulu1iuo1 ol Hlletn An1illca11 klaml 11c: Am. A11<1<. 1'c11okum Ccul .. i111 Pull .• v. fl. p. ~ -- 1!16S. ka·bull- _,pholorr ,uunliff of pOII-PlcillO(CIIC 1cc1anlc ac1M,, uf die ca,mn Cru1cr Anlillc•: Ccvl. Soc. A111erka lull.,"· 71. p. 1291 -1291 •l)cCJ1AUA1,.c;, P., and t.hc,11ton1. G~ 1111, 1111. t.lcmoi,c ,ur In Coralliarln dca An1lllc1: t.lc•. Aud. Turin. :?cl 1u. w. II, p. 27t-'65; w. H. p. 199 ' [uu:. I. \\'., l!l:?t, The 1rolo&J ol 1l1r ftrhi1h Vi11in hbn,h: Grol. t.la&,, "· 61. P· SS'l- S~l h u, W. S. lusu. r. J., and V1111onc:1N, J., 1951. ai.-1.1no1phic 1u<1ions and n1r1a- mu1phic fuir1: Gtol Soc. A111r1ica J.ftmoir 1J. 260 p. • Nut ua,aincd bf 1hr w1iltr. -- - ..,_ T, W. DONNULY-ST. TIIOMAS AND sr. JOIIN, U. 5. VIRCIN 1$1.ANDS 175 llouuOlf. W .. l!l6t. Orisln of hi1h-1lu1nl111 t.A1al1. andctilr. anti 1bci1t 111ai;mu: Scirntt. W, lt6. p 6'S-6'7 lluun, J. J. 19~9. Some ■1lncralu1iul cquilil,1i1 In lht 1111r111 K,O Al,O0 -SiO, 11,0. Am. Juur. Sci., w. 2~1. p 2U-270 lloun, J J .. '-luu. C., ••"I ll.1c.111u, 0. II. 1961. Somr •hc,i1i,,11 1u,1iu111 i11 11>,· 1y11,·111 Na.n Al,O0 SiO, 11,O. ti. S. G,ol su .. q l'ml •••1••·1 4:!IO. I'· ,111 110 111 "·II.II. 1!11'1, c:hcmiul , ..... , .. ,,111011 and "I'll•., 1•ro1••·111t·1 ul (UIUIU0II <lint•l•)IUHII< , . l',11 I: \m MinruluGiU, •· Jt, p 6:!l -61t6 11111.•0•1. A. C. 1905, lu1 1',·110,:uphi,· ,lcr ll.-in.-11 An11llrn lll'>JIJ, 1111II c;,-.,1 lu,1 Uni•." Ii (l'J02-l~S). p. 2U-2S'.! •110 .......... II n. 1110. N011~ bc1nac1l11iu1.,·r 0\1;1 SI ·11, .. 111 ... · {;t·or11111ic ~l.111tlnt.l\ hlt· Nacurluulrin, !Met Mudc, p. 561-SGI •-- 1116, lld,c;r tlie 1ninnaliac:hc11 Vo1ku111111niur auf ,I.-, lind s,. ·11,.,,.,.,. Kid, :!hh \'ru. dcr Na1urf. untl Aewr. p. ~62-:!61 Ku,r, J. f .. 1926, Gculos, of lhc Vi11i11 hlandr, Culdna, anti Vi,·11u•1: l1111uduuio11 •nJ rnlrw of the lilrra1urc: N. Y. Au,I Sci. S<icnlific Sunry of f•u,10 ltico and 11«· Viti;in h1111J1, •· t. f•I I, p. 1-6!1 K~NNUW, G. C .• l!I~. r,u1u1c •ulumt 1rmpcu1111c nl,1iun1 In 101cr a, clnaccJ 1c111· pcra1u1n 111d prcuuacs: Am. Jou,. Sci,"· 241. p. 5f0-S64 •&No■, lhw. J. r., 1152, A hit101ic,I accou111 ol SI. Thon1:u, \V.I: Nrw Vo1l, Cbuln 5crlbtm and Sona, p. 201-219 l.nuru1N, C. C .• aml li.Ltvnow. I'. \V., 19S6. (The rcb11iu111l,ip of the 1hc,a,oJrn1n1iul parararltfl P-T-r lor 11,0 111d ,O~ 1q11rou1 NaCl 1oh11inn1): Min. Sue. U.SS R. Tuns., •· IS, p. S~SSt l.sDcA&, £. G., 1965, l'cuo'°IJ ol andc1iclc, apili1ic, and htacoph)ric Row 101\., norah cenual Purr10 Rico: Ccol. Soc. America Bull., w. 76, p. S1--81 't.hcLUH, \V., 1111, Obsrrn1iu111 on lht g.-ology ol the \Vn1 l111li• i1b11,h h,,111 IIJil,.,l,,1 10 5111111 C1111, lnduslwc: l'l1lladclpl,ia, Juur Mad. Sci., v. I. p 1, I -1 i~ J.lnuno,r, II. A., 1!126, CcolUC}' of lhc \'i11i11 hla111h, Culd,u, ,nd \'ml''"' l'h)li•'I· raphr: N. Y. Acad. Sci .. Scicn1mc Suncy of 1'0110 Ri,u 111,I chc \'i,~111 hl•111h. v. 4, pt. I, p. 71-141; pt. 2. p. 1•219 NtctlOlU, G. b .• 19S9. Au1umc1asoma1i1111 in thc lower •1•ih1u uf 1hr lluihh •olunu ectin: Quatl. Jou,. Ctol. So(. l.o11tlun, •· I U. p. 117-162 Nou-. S. ll., and AtuN, R .• 1959, The 1ruchrraim7 of ,unor ii;ncou1 ro,.l srrics: Ccodrlm. rt Co11Wochla,, Acta,"• f. p. I0S-U2 Orncu. C. D, [IYINC, J. I., HtNNIOff, J. f .. ll•UIUDU, D. G. 111d Al,u u. fl. £. 1959. Ccupls)siUI lnvc,1ig~1io111 In lhc usic111 Caribbean; 11111,n,ary uf l!l5S ,nd 1956 uuilcs, p. 17-109 i11 L. II. Ah1cn1, f. 1'101, K. Ra11h1na. anti S. K. Runcorn, E,l,10,1, l'IIJ1la a11d 01cn1i111, o( 1hr £a11h, \'ulumc 5: Lo11do11, 1',·1i;,mun l'rr.s. ~f,I p. OanLU, P. t.l .. l!ICiJ, Alhli ion nd1a11i;c l,r1wu·11 "l•L·r a11,I frkh11a1 pl1Jtc: Am. Jn111 Sci .• "· 2&1 • .,. 201-:m OsanaN, £. f., 19!.9, llolc of o~),:•11 ptcuu,c iu 1hc C1)SUl1iu1i11n an,1 ,1ilfcoc11liJti,,11 ,.f 1,asalllc m11,na: A111. Jou,. Sd., •· :?57. p. 60'>-611 Rh H, II. J .. 1960. Zur Pc11acu11hlt, Cro<licmic 1111d Gt'nrr.c: drr l\1Ji;111J111r 1111,I l.a,:ri llltlt■ dra Obc:rdoon, uml Un1~1\.a1l,on1 in 0>11h1itingt11: t rol,ng, 1 I 01>chu11,:. Ct:!, p. 1-275 Sc-N, R., 1'62. Scml-qu~n1ila1h·e an~l)til of d1luri1t1 t.r X ••r 1liffue1iv11 \111 M111 cra"'slll, w. f7. p. 1Jlt-lJ92 •Sc1t0arau11e•. R II .• 18'7. llir Jun1lra11-fnul11, 111 1ruloi;i1<hrr 111111 lh11111 111..-r 11111,idu. ln1loau1· Alm111ad1 l1i1 l11l\.u11oJe. p S67-4S!', S11Afl80, L~ and 8a11NNOCa, \V. \'I., l!lli2. R~pid an1IJti1 ul 11l1t•1r. u1L.•11•1t. anJ I''"" pha1c rocb: U. S. Ccol. Su\tJ llull. 1141 A. 56 p. Sltuun, G. L. Woa111., J. I... anJ £wu,c;, J.I., 1951, Cra•ilr 111rasu1c,nr1111 in 1hr Virr;iu lala11cla: Gtol. Sue. Amtrlca Bull .• •· 11, p. IS29-15M '~ ~-.. ( --·~ ;-- + () 1'1.."" •..• (..;!':> /.. + ( ,,,.· 13· ~ -~-~" , ... .-'/ ( Gittt.r Quaternary U. Cretaceous L. Tertiary - C--· ~ ::, C 0 0 .0 '- (!) -er - "O C 0 .,, .,, :::, 0 CD u C 0 - 0- ., '- '-u > □ B ~ ii 0 .. ,. ( :,_••·'I: . , ..... - Alluvium -... ... • i LEGEND OikH and Plugs: qo • quortz-ondeslne porphyry• oh• ondHine-hornblende porphyry Dioritic Rocks Hans Lollik Frn.: Augite ondHite volcanic breccio and t uff Tutu Fm: Volcanic wackt. X-cp outcrop of Colli Point M•tabr•ccla Ktcc - Con90 Cay L1. Member Outer BroH Ls.:Thin-bedded, siliceous Is. Louisenhoj Frn.: Augite ondHite volcanic breccia and tuff, with minor conglomerate / / Contact Fault, showing displacement Attitude of beddinQ Attitude of fault Attitude of int rusivt contact c,... UNCONFORMITY II) :::, 0 CD 0 0 - Cl) '-u '-., ~ 0 ..J ~~- Quartz kerotophyre dikes and plugs Water Island Fm.: Quartz keratophyre flows, flow breccias,ond tufts, radialarites, spilite flows 11aP,(D IY THOll.tlS W DONNlLLT 11,Sl-11511 IOUIHWllf IO ■IOL.tl IY CI NILILIY I 19SII • REFERENCE NO. 12 f U T u ( i .1. , : .l. '::, :? •• . I • ., ; ' ISSN 0500-4780 CLIMATOLOGICAL DATA ANNUAL SUMMARY PUERTO RICO AND VIRGIN ISLANDS 1987 VOLUME 33 NUMBER 13 ·1 CERTIFY THAT THIS IS AN OFFICIAL PUBLICATION OF THE NATIONAL OCEANIC ANO AT"OSPHERIC AO"INISTRATION ANO IS CO"PILEO FRO" INFOR"ATION RECEIVED AT THE NATIONAL CLl"ATIC DATA CENTER, ASHEVILLE NORTH CAROLINA" .. i' noaa 28801 DIRECTOR NATIONAL CLI"ATIC DATA CENTER NATIONAL OCEANIC ANO ATNOSPHEAIC AONINISTAATION NATIONAL ENYIROlll:NTAL SATELLITE, DATA AND INF'ORIIATION SERVICE NATIONAL CLIMTIC DATA CENTER ASHEVILLE NORTH CAROLINA ( ( TOTAL PRECIPITATION ANO DEPARTURES FROM NORMAL IINCHESI .STATION JUL AUG SEP oc T NOV PllCIP DlPARIUR( PRHIP OCPARIUR( PRIC IP O(PHIUII( PR(CIP OIPARIURI PRIC IP OIPARIUR( VIRGIN ISLANDS ., ST THDHAS 01 ODROHl[A HS ' . •2 2. 7 2 2.51 4 . ., 3 I 8 .41 ESTATE FORT HYLN[R 1.04 2. 11, .40 4. 32 I 7 . J 7 [SUI[ IIOP[ I .•• 2. •u, 2.,0 4 . '5 7 I 2 . 'I I R[D HOOk ,., I. 22 I. l,'I I_ 1,1, J.,1 I I .4'1 TRUHAN FLO FAA AP .'l'I 2.41 I .42 4.l"> IO. JI, IIINll[RG .'ll I . '5 3 I . 4 3 J. "> 3 IO. 4 l --DIVISIONAL DATA-------> ,.u • I . 8"> 2.22 • 2. 38 I . ">O - 4. 1,0 4 . I 4 . I 27 I 3 .1,2 8. "> I ST CROIX 02 AL[X HAHILTON FLO FAA I .22 - 2 . I 4 I . I, 3 . 2 .84 2. 7 'I - 2. 8 4 2 I,", • 2. 1,0 I 3 .2"> 8 . 2 l ANNALY 2.21 I. 80 2. O'l 2 80 t "> 03 ANNAS HOP[ I. 10 • I ' .. ' 2 I. 25 . 3 . I 2 I. ',Q . 4 .53 4. I 0 .. , 7 11 .4"> ">. 81,H BETH UPP[R N[II WORKS I . '12 I. 32 2.02 1H 2 .">"> I"> .27 CHRISTI ANSTED FORT 2.28 . 81, I . 4 3 3. 78 I"> .48 COTTON VALL[Y 2 2.50 " 1H 3. 81, IO. I 7 EAST HILL I . 41, I . 1 3 1 . 4 "> ., 1 J 1 l .80 ESTATE TH[ SIGHT 2.20 I. 11 I . 2 3 4 . 8 I, I 4 . ', I FOUNTAIN J.00 I. 'II I. ">O 3.00 t "> .23 fR[D[RIKSTEO I SE 2.31 2.0'1 2, '12 2 ., 2 t ">. 71, GRANARO I . 51 I . 4', 1. 11 3 . I 7 " " HAH BLUFF L-H STN 1. '1'5 I. 1,2 ;:~~ " 2. 3 3 I I, . '15 HONTP[LLl[R 2. '5', I .38 4. I, l I 3. 78 • ·DIVISIONAL DATA··-····> 2.08 - I . I 7 I . ',2 ·3.01 I .80 . 4. JO 3. I, 8 · I . 7 l I 4 .22 'I. 11 ST JOHN 03 CAN[[L BAY PLANTATION I . 7 4 2. I 5 2.2] 5.07 I 2. II, CATH[RIN[BURG 2.02 2.20 I . 22 '5. 2 7 13.08 " CORAL BAY 1 .14 " J. 1,5 l. 51, I I . ">2 CRUZ BAY I .'S't · 2. II 2.27 -2,02 2.42 - ) . '5., 3. 7 ', • I . l 7 8. ',4 • OlH CAST [NO 2. I 0 I. 18 1.01 3.01 t O. 3, LAH[SHUR ea, I . i,'5 I. '10 " " l. 01 IO. I, 4 --DIVISIONAL OAIA-·····-> I. 11 - I . 4 4 2.01 • 2. '52 2. l 2 • l. 7 8 4. I', · I . 21, 11 . I 7 I,. 01, -~ SC£ RHCACNCC NOICS fOLLOII tjG SIA TI ON IND[X DEC PRIC IP O(PARIUAI 4.43 '5 _ 1,'5 4 . 2 7 2. 3 2 2.,, 4 . I 3 l . ,o . I 2 4 ,. . 'lbN l . o;.? 4 .b2 "1 3. 7 3 2. 3 'l l. , " 2. 'l& '5 ">0 3 1• 2. 'I& 1H 4 .42 l .82 .04 3 .,o 4 42 " 4 . ",I, J . I, 7 4 .o• 4 . 0, .21, ( PUERTO RICO ANO VIRGIN ISLANDS ....Lll..L ANNUAL PA( C IP O(PAAIURI 7 0. I 7 I, 7 . I, I, 4' . J 7 42.84 ">0.08 '5 3 . 'l 7 IO. 2 3 ~ ',Q. I 0 . ',8. I I, 48 8'! ">"> . "> I "> 4 8, "> 8. 10 I, I . I, 7 ">I,. 7 "> 5'! .02 ',8 78 ">"> . 21 11 4 7 48 22 .,. 4 7 40 . 1,2 44 . 'll, t . 2 2 ( STATION OU fl YI NG ISLANDS 01 NONA ISLAND 2 V l[IIU[S ISLAND 12 --DIVISIONAL DATA-------• VIRGIN ISLANDS ST TMONAS 01 OOROTMU US R[O MOOII ■U TIIUNAN rLO r•• AP --DIVISIONAL oar•-------, ST CROii 02 ALE• MANILTON rLO rAA ANNALY 8[TM UPP(A N[N NORIIS tMRISTIANSf[O ro11r --DIVISIONAL oar•-------, ST JOHN OJ CATM[RINUUIIG CRUZ en --DIVISIONAL DATA--·----• •, -· r_r ( ( AVERAGE TEMPERATURES AND DEPARTURES FROM NORMAL (°Fl PU[RfO RICO ANO VIRGIN ISLANDS - - - ----.-----"T"""---~~----,-----"T"""-............ - JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANNUAL I I I ! ! - - - - - I I ~ - ! = ! = ~ ; - I ··I ::, ::, - - - ,, i - I - - - ~ ! I· ! :r ! ! - ! - - - .. .. .. - .. .. !; .. .. ;, .. " • :; - :; Q .. ~ ~ ~ - I - - = - = = ~ ::, i - ~ :. - - ::, - - i ::, - ! i - - i - :;; ! - ! ! ! .. ~ .. i -.. U'.1.1 7'.l.'1 11, 3 7'1 8 80 4 It 83 2 84 4 83 4 1'1 11.4 "·' 11, '5 78 1 1t7'1 '5 7'1 I 10 0 81 1 81 'I 80 8 1'1 0 71 78 1'.I.' , .. " 11, 3 1'I I 10 4 83 2 84 4 83 4 1'1 1 It , ... 1'5 .• 71 • 71 1 lt7'1 'I lt81 4 u '5 12 2 81 4 78 'I 11, '5 It It It It It It It It 71 I 7'1. I 71 'I II 1 II 4 U 4 83 I 8'5 I 8'5 I 83 82 3 81 0 82 0 71 J I 1 11 I I 2 11 '5 3 10 2 I I 10 I J II 2 2 82 • 8 83 8 I 'I 81 1 2 3 82 7 I 8 80 b I ] 71 8 80 .. I 2 lt71. J 11.1 11 'I II 3 10 I, 12 I, 83 'I lt84 1 84 83 4 82 'l 81 0 '5 It It It It It It It It 82 It It 1t11 I It It It It It 78 '5 lt11 I ,. I It It It It It It 84 J 80 I, 7'1 4 71.1 I .'5 11 .J .1 14 '5 -2 1 II J 2 'I 10 .• .• 12.• I. 2 13 'I 2 I 14 1 2 8 13 '5 2 2 81 4 7'I .. 80 'I I '5 lf74 J lt1'5 'I lt7'5 I UI 3 It 7 7 1 lt71 4 1t11 'I !tao .. lt11 1 11 2 11 1 lt81 0 ltll 3 lt12 1 ltU 2 lt84 '5 81 'I .. 11 ] 11, 'l 77 'I 83 8 2 81 8 71, 0 .. , ... 0 71, 4 8 1'I 1 I 3 1'I '5 - 3 IO I. 8 It I 7 82 b 7 82 'I I '5 8 I 4 '5 1'1 I, J 71, 'l · I l 7'1 4 0 ' SH IH(l(IC( Ill( rou 1111115 SIIIIOI 11D£1 'I REFERENCE NO. 13 l ESTIMATED WATER USE ]N ST. THOMAS, U.S. VIRGIN ]StANDS. JULY 1983 - JUNE 1984 By Heriberto Torres-Sierra and Rafael Dacosta 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 - EST/MA TED WATER USE iN ST. THOMAS, U.S. VIRGIN ISLANDS, JULY ~ 983 • JUNE ~ 984 By Heriberto Torres-Sierra and Rafael Dacosta INTRODUCTION :;ater use :iata lWithdrawal .:ind return amounts) has always ~een the ~osc jifficult element t:o aefine :n the hydrologic cycle. :he ~eed to determine the amount of water used to meet ?ublic, cor.unercial and domestic ~eeds among other uses is 2ssential where the available supply is inadequate. In St. Thorr.as, L'.S. '.'irgin Islands, where streamflow occurs mostly during periods of intense rainstorms and ground-water rescurces are limited (Jordan and Cosner, 1973), water-use information is critical. In 1983, the l'. S. Geolog- ical Survey, Water Resources Division, in cooperation with the Water Resources Research Institute of the College of the Virgin Islands, began a general- ized inventory of ·..1ater use in St. Thomas. St. Thomas is located about 20 miles east of Puerto Rico (fig. 1). The island's popula- tion increased from 16,000 in 1960 to ~ore than ➔1,500 in 1984, paralleled with an in- crease in water production to meet tu 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 <lesa1~na- tion plant by the Government cf the U.S. Virgin Islands, the demand has not been satisfied. U.S. GEOLOGICAL SURVEY WATER RESOURCES DIVISION 1nl·, ~;:iout .J ~ercenc ,·.f :he Nater ?roduceci :s accounted for, ~ostl~ ~ue :o losses from leakage in the cistribution system installed in ;949 (Priede- Sedgwick, :::nc., ; 979). ')ther losses nre :.iue co unauthorized connections, :aul tv meters, and uncontrolled pub.lie faucets (fig. 3). WATER SOURCES AND USES The principal sources and uses of water in St. Thomas are shown in fig. -.. Seawater, rainfall collected from residen- tial roof-top catchments, and ground water are the main water sources in the island. Thermo- electric-power generation, pub- lic-water supply, and domestic and commercial self-supply are the principal uses. Seawater is used indirectly as the source of condenser-cool- ing water by the Virgin Islands Water and Power Authority (WAPA). The waste heat from the Island thermoelectric facility (fig. Sa) is used by the seawater-de- salination ;:,!ant (fig. Sb). Desalinated water from storage tanks (fig. Sc) is distributed to the urban areas in Charlotte Amalie ( fig. Sd), by the Virgin Islands Public Works Department (VIPWD). Areas outside the ?Ublic-water supply distribution &ystem, such as the Donoe housing project at ~ew, (fig. Se) can be classified as self- supplied ~sers. These obtain their water supply from rainfall catchments, wells, or from com- mercial water haulers ffig. Sf). ·rur The main urban area of Charlotte Amalie is also served by a seawater svstem. Thia system supplies water :'or fire fighting and flushing of toilets and open drains. Areas outaide the seawater system depend on gray water" (wastewater from other household uses) as their source of water for flushing toilets or irrigation. Where aquifers yield significant water to wells ( 10 gal/,rin or more) these are also tapped as a source of water, even if saline, as feed for reverse osmosis units or for flushing. Bottled water produced locally or imported is an important drinking water aource. Bottled water costs approximate- ly $1.25 per gallon. In 1979 importation of bottled water waa eatiuted at 1,600 gal/d (Peeblea, 1979). There are no reliable figures for current importa. Publlc• W•ter Suppl1 Production of desalinated water during the study period averaged 2.4 million gallon• per day (Mgal/d). Only about 0.9 H&al/d (38 percent) waa accounted (revenues from sales) by the VIPWD. About 1.5 Mgal/d vaa unaccounted for as previoualy indicated. A recent inveat11a- tion ahowed that leakage in tbe diatribution aystem repreaenta 30 to 40 percent of the total lo•••• (CH2M Hill Southeaat, 1983). Th• prod~ction of deaalina- ted water for public aupply increased to a peak of about 2.4 H&•l/d in 1975, declini.og thereafter to leaa than 0.6 K&al/d in 1980. Since 1981, WAPA haa i.oatalled three n- deHlination units vith a total rated capacity of 3.1 K&al/d. At preaant only two UDiU are bei.na operated. Full production capacity vill be required vben the !aat End Traoaaiaaion Sy•t- b•c-• operational (fia. 6). Tbi■ di■tribution •Y•t- vaa conatructed in 1977 but baa not been utilized, Water puaped to tba ••-•t•r diatribution-ey•t- avera1•• 1.0 H&el/d. Only •b-t 0.35 Ha•l/d of thia ..,_t ta SCCOUDtad for at th• public nwag• treatlHnt plant Hrd.q Charlotte Aulie. The r.-1.oder uy be loat throu&h leaks 1n tba aeawater-diatribution ay ■t-. Rowver, various storm drain• ln Charlotte Am&lie are continuouslv flushed to t~e ocean by caps from the seawater- diatribution system. Discharge froa two of these taps were Maaured and had an average flov of 0.08 Mgal/d each. five of theae taps would account for Ii of the unaccounted flow •• The cost of potable water to WAPA irom 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 VIPW to consumers connected to the distribution system is $14/kgal (VlPWD personal co11111Uni- cat1on, 1984) • TINnrto•l•c trlc•Power G•n•r•tlon Therwcelectric-Power Gene- ration is the laraest aiqle vater use cataaory in St. Thoaaa. Total UH vaa about 67 H&•l/d. Thia vaa ••••ntially aeawater, except about one percent freahwater obtained directly froa the deaalination plant for boiler feed. Ooaeatlc Self•Supplled • ll•lnf•II About two-thirds of the population in St. Thoaaa ia not aerved by the potable public water supply diatribution •Y•t-, and thua claaaified aa d-•tic self-aupplied. Rain- water collected froa rooftop catclment •Y•t- and atored in ciaterna, and vitbdrawala froa around water are the aourc•• for d-•tic aelf-aupply. !atiaated -t•r uaa for thia category vaa about 0.75 Kaal/d. Of thia .-mt, 0,60 H&al/d (80 percent) vaa aupplied froa rai.ofall. Thia indicates that rooftop catcbaenta are a ujor aource of -t•r for aoat private b-• aa,ecially in the aore huaid arua of the ialand (fia. 7). Virgin Ialanda 1- require• all dwlliqa, apartaenu and botela to have• ainiam ci■tarn atoraa• of 10 aallona for each equare foot of roof area fer one atory buildinaa, and 15 pllona for each aquare foot of roof area for tvo or aore atory buildin&•• All other buildina• 3. ► ATLANTIC OCEAN C Q lfT. THOMAfl ~ -- 18LAND8 i a:2. Ill .. • z 0 _, _, C 0 z ,. 2 .... :;_ are required to have c:1•terns with a ainiaull u•••ble c:ap•city of 4~ gallons per •qu•re foot of roof •rea except churches and warehouses, which •re not required to confona to this standard (Jord•n •nd Cosner, 197' A co!lp•rison of yields bet'--, rooftop-rainf•ll catch- ments at a high rainf•ll (Doro- thea) •nd at a low rainfall •r•a (Red Rook), w•s .. de using d•ta from July 1983 to June 1984. The comparison v•s ude for a family of four using 25 gallons per c•pita per d•y {2l gpcd~ with a roof •rea of 1,000 ft and •n initi•lly full cistern (10,000 gal). The faaily would have required the service• of a water hauler only one• if they lived in the Dorothe• •r•a, •nd tvice if they lived in the Red Hook area. Raillf•ll could have supplied about SO perceut of the total vater needs in the Dorothea •rea, but only 31 percent at led Hook. The cost of vater produced by hou•ehold roof-top cistern •ysu.. ii Htiuted at $17 to S19/ltgal (CH2M Bill Southeast, 1983). Th• ujor cost 1• assocuted vith construction of a cistern. Dome•tlc S.lf•SIIPlllled • Ground W•t•r Ground vater vithdr•vn for domestic •elf-supplied u•e was about 0.15 Mgal/d. Ground-water vi 1wals by the Virgin I•'-·• Hou•ing Authority (VIHA) v•• e1tiuted at 0.10 ffaal/d. An additional 0.05 Mgal/d was u•ed by other do-•tic self- •upplied users. Ground w•ter for doaestic use is available in nearly all parts of the isl•nd. There are only a few areas where yields to wells are large enough to warrant the development of public supplies. In their 1tudy, Jordan •nd Cosner divided the island into five ground-ater areas accordinl! to their poten- tial yield and w•ter quality (fig. 8). The potentul yield ana waler quaiity 01 t~ese areas are liAited by exc•saive depth to vater, seaw•ter intru1ion, vaste-vater contamination, and contamination from aeavater uins. CotntHrcl•I Setr•Supplled Condominiums and hotels used about 2.0 Hgal/d of saline water. This is used principally for cooling, flushing toilets, and swi-ing pools. S-11 desalination plants produce about 0.1 Kgal/d freahveter. About 0.2 Kg•l/d of the commercial water-use 1• around vater. This is used -■tly for flushing toilets. In a-■ areas, where the ground vater 11 of good quality, the va•t• veter is used for irrigation of lavna (Mahogany Run). Rovever, -•t of the c,,_rcial facilities are located near the coast and puap ••line-ground water. Water hauler ■ supplied an estimated 0.07 Hgal/d of desaliu- ated water from tbe VIPIID standpipes to c-rcial unra. The average pric• of water delivered by water uulera is $55/ltgal (Ajayi and G6aes-C-.z, 1983). An e ■tiuted -nt of 0.05 Hgal/d was obtained fr- rooftop rainfall catcbaenta. Public •••t•·W•t•r r, •• ,,.,..t There are aeveu public vaste-ater treataent facilities in St. Thomas (fig. 9). The airport plant, serving Charlotte Allalie, discharges about 0.5 Hgal/d to the ocean. Inatantan- eous flow rates ■easured in June 1984 ranged from 0.16 to 1.4 Hgal/d (fig. 10), Specific conductance aeasurement• indica- ted that about 70 percent of the effluent wss seavater. The other six vaate-vater treatment plants serve ■oatly public-housing projects. These discharge about 0.20 Mgal/d to streaos and the ocean. ---~-" - _.,&a. .. -~ .. ......._ ...... ··-· _.....,_,__, ..... ~- ,.,.a.laJ.alaMU. .... ._, .._ ....... , . ...- ••-...--- ., .... , ..... _ ....... __ , .. -.. ,_ ., ... -.-- ....... ll"lla l•a.tlll ..._ _ _. ar. _,, 1. ~le• ______ , _________ ._,. ,. , ..... -- ......,, -- ,_ .... ··----- A 0 FIOU,,E ,, Co•pa,,ao11 ., ,,.. ,,.,.,.,,,, ol ... ,., dlarr/r,w,ad • ~- .... .,_ w.r ........ ,, .......... ~ SOURCE, DISTRll FIOUIIE la. S••••tor ••t•&• •t t•a T••r••••••trlc ,. ... , ,., .. , ., .. , .... , , ...... .,. ' I FIGUIIE lfl. D•eaatlc ••fl coaeor•l•I •••r• !If CIJ•rlotra A••II• •r••· EX,-LANATION El .,. IIOfYscl ■ ,-IPOIIM IMtelloCII INlt - __ ,..,., •• of ..., , .... □At ... -- 0 t 2 3 4 MILES FIGUIIE •· Ar••• •••••d IJr th lr••►••t•r fllatr•••t1011 •r•t••· l I I 0 2 J 4 MILES TUl FIGUIIE 1. A••••••••••••I r•l•tal/J. /11 /11caoa. ,,.,.pared ., 11.J. c., .. _,,_ (IIWa} IIOAA.J --"'~ Bo, (C FIG I I REFERENCE NO. 14 -- A I ·•. ( ( .... - ...... ~ ATLANTIC ---- II ----- U --- .... .. --- .. ·-- II - - U -- ,:._ -- •· ;';;':ifl'lf a't.l: :--:-;rr-_-:- - ,-::: :.. CARIBBEAN S E A ' ' :~fz!I: ·~ ' ! , If""'; ___ _ r..- U, Virgin Islands D1 f: :. of Planning and Natural Resources C 1stal Zone Management Program " ........ of ltlla .. - "'-!Nd Ill ,-t....., .. CNIIII Zw ...... _.. Act of 1172, ildllllne.■IN 11r IN Olloe of CNIIII Zw ...... -111, Na11cN111 Ocw11c and ~WIJ■I, ....... ( OCEAN -- ,_...,. ~-..,. COASTAL LAND AND WATER USE PLAN ■ Preserv1tion [I Conserv1tion Recre1tion. Tr1dition1I u,es 0 Protection, Residen1i1I Low Density ■ Reside11ti1t. Medium Density ■ Residen,i1I, High Densny 0 W1te, Dependent & Rel1ted Commerc11I M1rine Facilities ■ W1ter Oe~ndent & Relit~ lndu~lrial Marine F1cilities II Commercial !J 1ndusrrial ~ Excluded Federal Lind -- _..,. ZONING DISDICTS LIGEND .. , l- o.nt,ty, •-•IOI •-2 la- OP'"''" .• ..,,NM'fl,a,il •-J ~.llffl~IY.lltifPCM'flt ... l ... ""4lf0um OPnt,ny. ■lf'\lldreftt.al .. , H'lh Offll,ty. •-• .. I ... , ....... -.... ~-2 "1ncut1ure Tn,cll. hrm 1-1 C•n1,,1 lut1nft\ 1-2 !l«_a.n,...,, 1-J X ,1ne,red lvwnft' 1 .. ~, .• ~,,.1 C COft'Wfte'fCIII 1-1 & 1-2 l1tN .,W:, tow~" lndulfr~• W•I w11~rori1 • Pl•....,..• W-2 w,1t'f'fron1 • 1ndw11•I , "ubltc ;c:;c,.,,.,nfflf'nt ::\- il()J REFERENCE NO. 15 ru1 UNITED STATE~ ENVIRONMENTAL PROTECTION Auc.NCY DATE: JAN 06 SEE REGION 11 _, ' Preliminary Assessment and Confirmation of ~uthorization of 5'____,£CT: CERCLA Removal Action Monies for the TUTU Well Site, Anna's ~etreat, saint Thomas, u.s. Virgin Islands - ~CTION MEMORANDUM FROM: TO: THRO: Carlos E. O'Neill ~ ~--· fr:. on-scene Coordinator -,,- --~(Tv-..) '- Stephen D. Luftig, Director Emergency and Remedial Response Division George H. zachos, Acting Chief Response and Prevention Branch I. EXECUTIVE SUMMARY On July 15, 1987, Mr. Allan Smith, Commissioner of the Department of Planning and Natural Resources (DPNR), u.s. Virgin Islands, verbally requested that the o.s. Environmental Protection Agency (EPA) provide analytical support in the sampling of one well which was reported to exhibit a atrong unpleasant odor. Thia well is a major source of coaaercially provided potable water supply for the eaatern portion of St. Thomas. The well is located on the eastern part of the island in the Tutu Section of Anna's Retreat./ Thia verbal request was followed by an additional request for !PA to aaauae the role of Lead Agency after aa ■pling reaulta indicated that several commercial well ■ were found to be conta ■inated with hazardoua substances. Thia verbal requ••t waa followed by a formal request in writing by DPNR on Auguat 10, 1987. In July and Auguat of 1987, !PA confirmed by aaapling and analysis, the contamination of groundwater with volatile organic compounds. A ■ajor contaminant in the groundwater is tetrachloroethylene (TC!). Th• EPA 10-cay Health Advisory Level of 175 ppb was exceeded in three (3) of twenty four (24) wells aampled, with two of the three conta ■inated well• being private residential well• • ./ The concentration ■ found ranged from 240 to 7,600 ppb with aeven (7) additional well• being below the !PA 10-cay Health Adviaory, but above the u.s. Virgin Island'• interia ■axi ■u ■ peraiaaibl• concentration levels set on septeaber 1, 1987, by DPRR for volatile organics in drinking water in the Turpentine Run Aquifer {SO ppb for a ■ingle com- pound or 100 ppb for total volatile organic co ■pounda). Three of the pr•~iou ■ly ■entioned seven well ■ were reaidential wells. IEIIION II FORM 1320-1 (1111) -2- This ~ction ~emorandum will document funding authorizerl for Phase t of the Tutu Well Site CE~CL~ Removal ~ction. P~ase I addresses only residences having contaminated drinking water wells with volatile orqanic compounrls above levels established by the u.s.v.I.'s interim maximum permissible concentration levels for potable water. This action dirl not include wells where water is used primarily for commercial, business, industrial and/or trade purposes. It also dirl not inclurle wells contaminated solely by gasoline or gasoline by-products which are not ~azardous 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 pluabing, the delivery of water by tank trucks as a temporary alternate water supply, and a well water monitoring progra ■• The total project ceilinq 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'• 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. 9ACXGROUllD A. Historical Information A request for EPA analytical support for one well in the Tutu section of St. Thoma ■ was made verbally on July 15, 1987 from DPNR. On July 31, 1987, a verbal request for EPA to as•u•• the role of Lead Agency was made, and this w•• followed bv a written confirmation of the request, dated Augu•t 10, 1987 (received by the Emergency and Remedial Response Division on August 19, 1987). The initial request wa• ba•ed on• report that one well was reported to have a strong odor, characteris- tic of a petroleum product. Thi• well is a aajor source of com ■ercially~rovided potable water for.the eastern portion of the ialand. YSPA'• preliainarv inve ■tiqation coaaenced on July 21, 1987, vi~ a field reconnaissance and •••Plin9 of this one well and six ~dditional wells identified in th• ia ■ediate area. several of tb••• well ■ are also major water supplier• of public drinking water ~o the •••tern part of the island. ru·1 (i () l ·:;? 1,~:., \~::, - ·- -3- Laboratory results from this survey indicated that the initial well was highly contaminated with gasoline and chlorinated organics, and the additional six wells contained elevated levels of chlorinated volatile organic compounds. ~ased on these results, DPNR declared that an imminent health threat existe~, which could affect approximately 20,000 people living in st. Thomas. In addition, an indefinite number of tourists who vacation in St. Thomas were at risk since these commercial wells supply water to major hotels and restaurants. DPNR issued orders to close these seven commercial wells to protect public health. ¥subsequent to this action, ~PA expanded their sa ■pling plan due to the threat of greater conta ■ination to drinking water wells in the area. EPA along with DPHR, identified other wells within the Tutu Water/Turpentine Run Aquifer which ■ay 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) well• identified in the Tutu Section of Anna's Retreat. All twenty-four well ■ were ■a ■pled and analyzed for volatile organic co ■pounds. Following th••• results, DPHR closed the five private wells vhic~ service two three-fa ■ily ho••• and one apartment building housing twelve studio uni ts. B. Site Setting/Description The contaminated wells are located in the TUtu Section of Anna's Retreat, st. Thomas, u.s. Virgin Island ■• Th• five (5) private well ■ recently ordered closed are located in the Tutu residential area. At the present ti ■e, the affected area is not aerviced by any public water supply. EPA ■a ■pled a total of twenty-four (24) wells in the Tutu area and found five private wells and eight (8) co ■■ercial well ■ seriously contaminated with up to 7,600 ppb of PCE. (See ■ap attached). c. Quantity and Type of substance Present EPA ■a ■pled aad analyzed for suspected volatile organic co ■- pounds on July 2i and August 10, 1987. Listed below are the ■aximua concentrations of the hazardous substance ■ identified in the drinkin9 water vell ■1 ·rLJ·r (.J().J Contaminant Tetrachloroethylene Trichloroethylene Benzene -4- Maximum Concentration Found (ppb) 7,600 61 1,400 Statutory source of Hazardous Substances under CERCLA Clean Water Act Section 307(a) Clean Water Act section 307(a) Clean Water Act section 307(a) The results of the sampling are contained in Tables I and II. PCE contamination ranged fro ■ non-detectable to •even thousand- six hundred parts per billion (7,600 ppb). Sampling results adequately document 3 wells with contamination above EPA'• 175 ppb PCE 10-Day Health Advisory Level and eight (8) wells above the DPNR's interim standard• for maximum contaainant levels of volatile organic compounds in drinking water. III. THREAT A. Threat of Public Exposure Direct contact with PCE aay cau ■• eye and_no ■e irritation along with dry scaly and fi• ■ured deraatiti•• Acute expo ■ure through absorption, inhalation or inge•tion, ■ay cau•e central nervous system depre••ion, hepatic injury and anesthetic death. PCE ha• been found to be carcinogenic. This is a case of actual contaaination in excess of the EPA 175 ppb PCE 10-Day Health Advisory Level for a three-faaily house and one apartment building hou•ing twelve studio unit•• In the other thr•• fa ■ily apart■ent dwelling■, th• well con- tamination exceeded the interia DPRR drinking water standard of SO ppb for any single volatile organic constituent. In addition to the exposure via consuaption of the water, or eating food prepared ~1th this water, ■hovering with water contaminated with volatile organic ■ can contaainate the air to significantly unhealthy levels. -s- The location, direction and dimensions of the plume are af- fected by variations in water table depth, rate of pu~ping of the wells, duration and intensity of rainfall, and inter- mittent releas•s of chemicals from one or more sources, all of which are unknown at this time. Given the above variables which affect contaminant strengths in any well within the plume may vary randomly. On September 2, 1987, OPNR 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 cf Extent cf Release Investigation, sampling and analyses by EPA have identified contaminated groundwater, a ■ described above, and containing contaminates, a ■ 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 Action ■ to Abate Threat JEPA ha ■ comaenced an investigation of the TUtu Water/Turpentine Run Aquifer by establishing a cooperative agreeaent with the u.s. Geologic Survey to define the characte~i ■tics of this _. aquifer and to deteraine the extent of contamination. EPA and DPNR have also completed Aquifer and a aonthly well aonitoring progra ■ is being developed • .J OPNR 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 froa this facility are unknown at this ti••• DPNR ha ■ proposed to issue an advisory to local dry cleaning establishments instructing the ■ to properly ■tore and hold all waste for proper disposal by an industrial vaate hauler. ✓oPHR with the a ■ai ■tance of EPA i ■ conducting an as•••••ent of at least nine (9) facilities identified to be potential source ■ of hazardous vast• and/or subatance rel••••• in the Tutu area. T t.J·T -6- EPA has cleaned the homeowner's cisterns that have been conta~- inated by hazardous substances from the groundwater, modified the existing home plumbing to terminate well connections, and intends to continue to deliver clean wat~r via tank trucks on a regular basis, and establish a surveillance program for all wells in the area by a monthly groundwater monitoring program. This Phase I, short-term removal action will mitigate the threat to public health by providing a te~porary alternate source of water for affected consumers. IV. ENFORCEMENT The contaminant plume is generally believed by both OPNR and EPA, to ·have its source from past and pre ■ent iaproper 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 Ph••• I of the re ■oval action is the mitigation of the threat to public health by providing a safe potable water supply to the affected residence ■• Two three-family hoaes and one apartaent co ■plex housing twelve studio unit• were identified as being dependent on groundwater froa their own private wells. Their respective wells were ordered closed-down by OPRR for exceeding interim drinking water standards. To reach the objective of providing a safe interi ■ drinking water supply and protect the health of the public at risk, the following reaoval action was initiated. Water ■torage cisterns, which receiYed contaainated groundwater fro■ affected wells, were cleaned and sanitized. Cistern ■ were filled with clean, safe, drinkia9 water. Water tank trucks fro■ local water haul- er ■ will b~~roviding water for the affected cistern ■ on a reg- ular ba ■i ■• 'fluabing ■odification was aade to disconnect water line ■ fro ■ the conta ■inated wells which provide groundwater to the cisterns. fLJT ()(; 1 -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 i ■ thirty (30) gallons. It is estimated that the one apart■ent building ,~ has twelve studio units with the average of tvo people per unit. The two other private homes are three-faaily dwellings with the average of ten people in each. The cistern ■ in the three family houses are small and, therefore, a supply of water au ■t be deliv- ered every two or three weeks, respectively. The delivery period is currently estimated to be one year or vhen a per ■anent alter- nate water supply can be provided, whichever occur ■ first. PROJECT COST (PHASE I) Cisterns Clean-Op: Provide labor, aaterial and equipaent including one vacuum truck, pres ■ure water spray guns, water tank truck, etc., to drain and di ■po ■e contaminated water and to clean and sanitize identified cistern•••••••• $13,000 Modification of pluabing including Labor and Material•••••••••••••••••••••••••••••• $ S,035 Refill ciatern ■ with clean and safe drinkin9 water•••••••••••••••••••••••••••••••••••••••••••$ 2,665 Provide •i•t•rns with clean and safe drinkin9 water on re9ular ba ■is according to a pre- approved ■chedul•••••••••••••••••••••••••••••••• $15.000 Contingency (lO•)••••••••••••••••••••••••••••••• $ 4,300 Total Mitigation Co ■t••••••••••••••••• $40,000 11..n ')() 1. f -8- Extramural TAT Cost TAT Monitoring and sampling program (Including travel and per rliem)••••••••••••••••• $35,000 TAT Technical and administrative support (including travel and per diem) ••••• •••• $10 1 000 Total TAT Cost Intramural EPA Cost $45,000 (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 i• found sooner than the proposed 52-week ■ delivery period, might be increased, depending upon the identification of new drinking water wells found to be contaminated with hazardous substance ■ within the affected area. c. Project Schedule Project initiation of cistern clean-up and safe water de- livery ha ■ already been iapleaented 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 occur ■ first. V. RECOMMENDATIONS Condition ■ at the Tutu Well Site meet the require ■ents of Section 300.65 of the Rational Contingency Plan (HCP) for a CERCLA/SARA re ■oval action. EPA ha ■ deter ■ined that there is a threat to public.health at the ■it• (Section 300.65(b)(1). Thia detenaination va ■ baaed ona 1) Ruaaa ezpoaure to unacceptably high level ■ of acutely tozio aubatance ■ (Section 300.65(b)(2)(i), and 2) co ■ta ■ination of drinking water ■upply (Section 300.65 (b) (2) (ii). . .. ·.·l (j\.) ·'- -9- The resident population at risk currently relies on crivate -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 watP.r to the public until a permanent water supply can be secured. This is a written confirmation of the initial and revised verbal approval of up to $100,000 for the total project ceiling estab- lished on September l, 1987, by the Director of the Emerqency and Remedial Response Division to the OSC for the CERCL~ removal action at the Tutu Well Site. The mitigatinn contracting ceil- ing is estimated at $40,000, with an additional $45,000 for TAT costs, and SlS,000 for EPA costs. Your authority to authorize these funds is pursuant to Deputy Administrator ~lvin Alm 1 s·memorandum of Oeleqation Number 14-lA dated April 15, 1984, and Richard Dewling' ■ Redelegation Order R-11-1200.6 of August 29~ 1984. ·c-. ,I ' ( _ . ) APPRov-.L: ~:t.r(_ u. _e,•2,~ I J DIS~PPROVALs cc: (after approval is obtained) c. Daggett, 2RA J. R. Salkie, 2ERR-DD P. s. Luf ti g, 2ERR R. G. zacho ■, 2ERR-RP T. s. Sprague, 2ERR-RP T. J. Czapor, 2ERRD-SC P. G. Pavlou, 2ERRD-NYCRA I I DATE, DATE: Marshall, 20EP Gelabert, 2CPO Gherardi, 20PM-PIN Sullivan, P~-214P (EXPRESS MAIL) Fields, WR-5488 Mcltechnie, 2IG ·ru1 .•·: .,: .... \ 1 ,, r PH0T0VAC IAMPLIMG RESULTS TUTU IILL IITI n. !NOKAS, u.1. YJICIM ISLANDS IANPLI IANPLI DATE Dlfl LOCATJOI IVIID ,aNPLID 1111.YZIJ> IOUJCI ID TCI Pel IOI, Da GCIII •••••••• --....... --··· . ............. ••• ... ••• • •• ••••••• HllfHXAI CIDIN 11•C73 07/22/17 07/30117 II 0 ' 101 ' 0 .,. HllfKNAM IAKllf 17-474 07/22/17 07/30/17 II • • s ' 0 .,. 4 IJIDI IILl,ll 17-471 07/22/17 07/30/17 Cl ' 11 14 I 0 • ,. 4 111101 l&Wl 17-411 01/11/17 07/30/17 Cl ., 11 ,1 ' 0 .,. tiw, 17-477 0?/22/17 17/30/17 Cl .,, II 200 41 31 .,. YIHI 17-471 07/22/17 07/30/17 II 11 I a, • 0 .,. IGLrl 17-471 17/21/17 07/10/17 Cl a ll II ' .. ,. TlLLff 17-410 07/22/17 17/30/17 Cl ,,,o 7111040 411 327 .,. PIILD ILUl 17-411 07/11/17 17/J0/17 ll • 0 0 I 0 ., • • • • • TAILI I ' \ / /_\, 1UT ,,. IEU. llNPLINC J!SULTS TUTU 111.L II Tl n. THOKAS, u.1. VIRGIi 111.lMDI IAIIPLI D&TI DITI IUIIII IIIPLID WLJID IOUICI ID tel tel tDL Del GCIIS --- ---· --· ......... ••• -· -· ·- --· f IIIOI 11 1111 11110/17 11112/11 Cl I 11 71 l 113 .,. IG&.rl IILL 11 1121 11/11/17 11/12/17 Cl 0 ll '' 0 IJ ,T, IGLII QL.L 12 "'' 11/11/17 11/13/17 Cl 0 lJ ., 0 , .. ,. IGLtl IIU. 13 .. ,. 11/10/1, 01/13/17 Cl 0 11 17 0 '' .,. HAITIOIU 111111 0011 01/10/17 01/13/17 II 0 • I 0 l .t. llllTHIU CIUIN IOIA 11/11/1111/13/17 II • J II • ll .t . HUTIOIU anan-10,1 11111/17 ll/lJ/17 JI • • l • . .,. IOOIIGUII Auto Ill& 11/10/17 01/13/17 II 0 I I • 0 .,. lltd 1011 01/11/17 01/13/17 Cl I 0 I • 0 .,. AUHA.LIOIAID 111& 01/10/17 11,1,,1, N • 0 l I 0 .,. Dltll.LUClll 1111 •• ,,.,,, 01111/17" • 17 111 1 11 .,. DIYCOI 13 OIIA 01/10/17 11/13/17 Cl • I I • .. ,. DIYCOII 11 OlU 11/10/17 11/13/17 Cl • I • ' ' .,. DIDI 1141 11/10/17 ,,,1,,1, ■ I • I • .. ,. DlllnJ 0101 11/10/17 11/13/17 Cl I • I I I .t. • flHA RU. 13 Oil& 11/11/17 11/12/ff JI I • • I ' .,. ~Hl IIU.11 1111 11/10/17 11/13/17 II I I u l II .t. _)11111 IHA 11/10/17 Ol/lJ/17 II •- I 7 I I •'• nm. 0111 01111111 0111,,n" • II 171 • II .t . HUffl 1,11 11/10/17 11/13/17 ft • II 7111 I .. .,. Ufflll IIU 11/10/17 11/11/17 fl I t •• I I .t, Pl&IICOII ,111 01/10/17 11/11/H N •• II IH • 140 .,. DIICH 1111 11/10/17 01/13/17 fl I • I I I .,. tJUIT 1111· 01/10/17 01/11/17 Cl. lHO I 141 II ., .. ,. ULLIT DD 1171 11/10/17 11/13/ff Cl , ... ·• Ill II .•. ,. rllLO ILIII 1411 11/10/17 11/11/1' II • • • • . ., . • • J • TABLI II '-_...,,. .• \Ui 001. :,:Ji'.::, ' .. ' .~~ ) C> :\1, ~ r,:\_ • I-·' ••11 Location ; L. Bryans tz.) • f·._ L Rodriguez C,) i--- L Harth ■an U) o·· I. Eglin l3) , L Harvey l•) ' .. Steal ■ <..•) . ~ Nap: 7. Mathlasl,t) 13,·VIHA~2.) 19. Lockhart,-..~-. 8. Saith U) 14. Leonard") .,..,-,,._,ltJ. 9. rrancoi• l•) 1~. De■itri ~) =,t•:-t•t~li 10. Tillet t•) 16. Dench ~) •:'.':f~•"': 11 • R••••Y \! l 17 . Devcon tJ ) ~Na.11:J) lZ. 4 IIInds 11\1.)11. Dede \1) Aa~ ••• () IIOMbta tf IMt\\5••.::·: , I I t I II II 11\\ 11 ,.._, \ \ '' ' '--' "" ,,,,,.,,,, " \ ---- ~ ~' .. '' ,, ' ' '' '' ' REFEREICE NO. 16 TUT uU.1. ';;:'1) / I I I U. S. Geological Survey Water Resources Division Caribbean District Open - File Report A SURVEY OF THE WATER RESOURCES OF ST. THOMAS VIRGIN ISLANDS , ·- ... - UNITED STATES DEPARTMENT OF THE INTERIOI IN COOPERATION WITH THE ll ... !'i () (i 1. 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 mountainous, and slopes commonly exceed 35 degrees along a central ridge 800 to 1,200 feet high running the length of the island. The general appearance is a panorama of numerous steep inter stream 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 t}J.e 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-wa~er yields of 7 O, 000 and 30,000 gpd, respectively. Fully developed, the surface- and ground-water resources of the island could yi~~::1 • 3 million gallons of water per day. ' Ground water is slightly saline, commonly containing more than l, 000 milligrams per liter dissolved solids. The principal source of the minerals is bulk fallout of sea- and land-derived 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 • \ U I /_\. /,:-/ UNITED STATES DEPARTMENT OF THE INTERIOR Geological Survey Caribbean District Open-File Report A SURVEY OF THE WATER RESOURCES OF ST. THOMAS, VIRGIN ISLANDS by D. G. Jordan and O. J. Cosner Prepared in cooperation with the Government of the Virgin Islands of the United States 197 3 TUT OUl :/1HU I A SURVEY or THE WATER RESOURCES or ST. THOMAS, VIRGIN fSLANDS by D. G. Jordan and O. J. Cosner LOCATION AND GENERAL SEfflNG Location The Virgin Islands, forming part of the Antilles Island Arch separaung the Canbbean Sea from the Atlantic Ocean, are about 1 , 400 miles southeast of New York and almost 1,000 miles east southeast of Miami. St. Thomas, the northwestemmost island, lies about SO miles east of Puerto Rico A rLANrtc (fig. 1 l. St. Thomas is the second largest of the more than SO islands and cays constituting the Virgin lslands of the United States. The island is approxunately 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. OCEAN ~ .... ·-- I ... ~ PUERTO RICO ~-- C A RI 8 BEAN s EA G?. I ,,. .. ., ... .. " .. .......... j • .• .. .. --- -- •••oo· ···-· ·-· .. ... Figure I .--Location of the Virgin Islands of the United States. 1 TUI UUJ :.:'.Jbl - Population St. Thomas has about 17,000 permanent resi- dents and a transient population of tounst and im- ported laborers of about 8,000. The majonty of the population u urban--about 20,000 people live 1n Charlotte Amalle, the only c1 ty and also the seat of government of the Virgin Islands. The permanent Population 1s increasing rapidly and is expected to double by 1980 (unpubbshed data, V. I. Planrung Board, 1964) • Topography The land surface 1s almost entirely sloping and extends seaward from a central ndge, 800 to 1. 200 feet h1gh, runrung the length of the island. The slopes, which commonly exceed 35 degrees, are dissected by numerous stream courses of steep qradient. The general appearance 1s a panorama of steep 1nterstream spurs and rounded peaks. Flat land is confined to the Charlotte Amalie area and a few small alluvial-filled embayments. The only variation 1n the general topography is in the upper valley of Turpentine Run in eastern St. Thomas. The valley has relatively gentle topography consilting 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 charactenzed by steep slopes, was under culUva- tion, prunanly for grazing or growing sugarcane or cotton. Agriculture, however, has declined almost to eXUnction. A few square miles of land are sull devoted to graztng in the eastern part of the island, and about 10 acres are used for truck garderung 1n the north central part. The remainder has been allowed to revert to brush and secondary forest. Now, land uH la clwnq1ng rapidly, much of it brought on by the Jet a9e end its rapid mass trans- Portation. Increesift; populaUon, in pan caused by development of the lsland as a retirement haven and by tourism, reaulta ln more land being used for urban and suburban development. The increase in papulauon 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. 2 Climate The average aMual rainfall is about 45 inches and the average temperature 1s only 80 ° r, !::>ut the prevailing 1mpress1on of the cllmate 1s one of dryness, especially 1n the winter. This 1s 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 1s 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. Rains exceechng 1 inch, with accompanying overcast, cloudy skies, come but six or seven times a year. Thus, there are few days when the sun does not shine. Although major rains are rare, their volume 1 s noteworthy. The greatest rainfall of record was 18.0 inches September 13-14, 1928, during a hurricane. The last great rain in recent years was 10. 6 inches May 8, 1960, the result of a staUonary tropical depression. Th• island lies in the path of hurricanes and occasionally receive• heevy rains and high winds from passing storms. The incidence of direct hits 11 low--dameging storms having a frequency of about one every 33 years. The last humcane to cause extensive damage was in September 1928. The direct n1y1 of the sun are very hot, but air tempen1ture 11 modified by the almost constant trade wind. Air temperature ( table 1) n1nges from a mean low of 72 .o•F in February to a mean high of 87. 8• r in August. The highest daily temper- ature of record was gs•r and the low, 63°F. '11\e prevailing wind direction is from the east. Northeast and southeast wind a are relatively common, but west winds are rare • Monthly average wind velocity dWing 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 proxunity of the sea. At Harry S. TNman Airport during 1953-58 relative humidity was highest, averaging 81 percent,1n the early morning hours, and lowest, averaging 66 percent, in the early afternoon. Average daily humidity is given in table 1. TUT UUJ. :,?.1.H:,::: \ ._:_ c:. ,:::, ·- ( 11•2,· ·••20' ( ATLANTIC OCEAN ~ AIRPORT CARIBBEAN SEA 0 ' 2 ' J •ilH ' , Gronillc r11 ■,e11 rocks ' . A) ...... < <.s- d)v -'S) .)- •••u· Geolov, 91neroh11d after T W Donnelly, 1960 •••,o· ( ( EXPLANATION ALLUVIUM - Silt, cloy, and thin, discontinuous beds of sand and grovel. Includes beach sand. E stimoted maximum thickness 50 ft. TUTU FORMATION- Tuffoceous conglomerotic 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 a few thin beds of tuft. Estimated maximum thickness 600 ft. LOUISENHOJ FORMATION-Water-laid tuff, brecc1a 1 and a few thin beds of limestone. Maximum thickness known 13,000 ft. WATER ISL AND FORMATION-lava flows, flow breccio, and water -laid tuft intruded by dikes and plugs. Maximum thickness greater than 15,000 ft. Contact Inferred fault, dotted where concealed Figure 3 .--Geology of St. Thomas. ( Geoloqy The general geology of St. Thomas (fig. 3) hu been studied for many years, but only recently have the geologic f0rmat1ons been named and descnbed 1n detail (Donnelly, 1960, 196 6) • The names of geologic format1ons used in this report are after DoMelly. The names have not been adopted by the U.S. Geological Survey. The volcanic and sedunentary rocks of St. Thomu are of Cretaceous ( and older?) age. The oldest rocks, those of the Water Island Formauon of Donnelly ( 1960) are predominantly lava flows and flow breccias deposited at great depth on the sea floor. Uplift and su.bareal erosion followed deposition. The Louisenhoj Formation overlying the Water Island Fonnauon was extruded from a volcanic center probably sited in what 1s now Pillsbury Sound between St. Thomas and St. fohn. Near the presumed locauon of the volcanic onfice the rocks are mostly very coarse reworked cone debns • Farther from the onfice, coarse material lessens and tuffs predominate. Neer the base of the Louisenhoj Fonnat1on 1s a conglomerate composed chiefly of rock from the Water Island Format1on. The Outer Brau Limestone was deposited on the flanks of the Louisenhoj volcanic cone dunng a period of volcanic quiescence. It consists of 200 to 600 feet of thin-bedded graphitic silic1fied radiolanan limestone and a small amount of included tuffaceous matenal. The Tutu Formation, the youngest rock exposed on St. Thomas proper, is composed almost entirely of angular debns denved from the Louilenhol Formation and minor limestone debris from thin limestone deposited contemporaneou1ly with the Tutu Formation. The rocks were 1ubsequently Wted to form a northward-dippin9 bomocUne. Dips ran-ae from 1S to 90 degrees and 1v .. 9e about SO degrees. Locally the fonnaU.. er. overturned. 11_ .. _-: 'I,. The permeable ~~ that theH rucka once may have had after des,oa1uon have been destroyed by metamorphism or by deposition of minerals in pore spaces. Ground-water movement 11 nc,,, limited to operungs along joints and fault zone ■• The homoclinal structure 1s cut by sets of faults trend- ing N 45° W, N 55° E and north. Three well- defined joint sets parallel each of the major fault 6 directions. The valleys of the uland have similar trends and are apparently the result of selective erosion of rock weakened by faulting and Joinung. Prime zones of ground-water availability. therefore, follow the valleys. Small alluvial deposits ranginq from Pleistocene (?) to Holocene 1n age lle 1n the valley of Turpentine Run 1n east-central St. Thomas and the larger coastal embayments. The alluvium of Turpentine Run hes 1n a narrow band seldom more than 200 feet 1n width along the stream. Maximum thickness of the alluvium 1s about 40 feet. Most of thiS alluvium, which u composed of sHt, fine sand, and clay and cont.ams 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 Manenda l to Mangrove Lagoon 1n the lower ba ain. The alluvium extends out under the lagoon near the mouth of Turpenune Run. Although composed pre- dominately of fine-grained matertal. the alluvium readily infiltrates streamflow when the grou!'ld- water ievel is below the base of the stream. As such, the alluviwn forms a readily rechargeable aquifer, althouqh it is of small extent and yield. Some coastal embayment1 headed by interma- tant 1tream_1 contain small deposits of alluvium similar to that of Turpentine Run. Maximum thickness of theH deposit ■ 1s estimated to be SO feet, and their areal extent seldom u greater than a f..,, acres (an exception be1119 the Long Bay and Ajrport areas near Charlotte Amalie). Near the sea, the alluvium interfingers with calcareous sand and at t1me1 contains lenses of manqrove- swam p deposits. Therefore, the depo11ts are of minor significance as sources of water. OCCURRENCE AND MOVEMENT OF WATER Water mover. through a cyclic pattem--the hydrologic cyele--in which there are three storaqe areas: the sea. the land. and the atmosphere. On the land, surface water and ground water depend on: ( 1) the amount, intensity, and areal extent of the rainstorms: ( 2 l the slope of the land: ( 3) the moisture content of the soil and vegetal cover: ( 4) the infiltrat1on capacity of the soil and underlying rock■: and ( 5) the size. number. and intercoMecuon of openings in the aquifer. Rainfall Rain 1s the only natural source of fresn water to replenish the water resources oi the island. Rainfall 1s seasonal. ·.·::th the rainy season 1n late summer and early fall and a secondary wet season usuaHy in May. ::early half the rain falls dunng August-November (fig. -I\. Rains exceed- ing 1 inch 1n 24 hours come SIX or seven tunes a year. f'our to 15 inches of rain falls 1n a -18-hour penod about once every 2 years in large storms. These rains can occur 1n any month but are more likely dunng the hurricane season ( August- >iovember). ~bout half the time annual ra1niall is between -10 and 50 inches f £1<;. 5 l. Less than 10 percent of the ume annual rainfall is less than 35 inches. ·Nh1ch usually means a major deficiency dunng 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 ( 1967 l 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 1n the past 30 years has been below average. There has been a long-term decline of about 10 inches in a Mual rainfall since the peak of the surplus rainfaH period in the early 1930 's. The most severe droughts of record occu1Ted in 1964 and 1967, when but 27 and 24 inches of rain fell, respec- tively. ;,real distribution of long-tenn rainfall, shown in figure 7 ( see letter "a"), 1s controlled by topo- graphy and the prevailing easterly to northeasterly winds. However, individual storms may or may not show the effects r,f orographic control or pre- vailing winds and the areal distnbuuon of the storms can be very irraqular ( fig. 7--letters "b" to "f "l. .. ... ---:., .)foil Moisture The soil zone over most of St. Thomas is not more than 1 foot thick. Where of sufficient thick- ness 1t has, however, the unique property of absorbing large volumes of water--as much as 12 inches in 24 hours (R. Scott, SCS, oral commun •. 8 1963 l. E:xamrnauon oi the soil zone wnen dr1 shows 1 t to be coarsely -Jranui.ar, .:wing to clump- ing of clay and silt particles. Frolonc;ea satura- tion is necessary oeiore tne ..;ranules break down. ;,.s a result, t!-:e soil :-:as a r.i.;h perrr.eaol11ty until well saturated. out, once saturated. 1t ::,ecomes poorly permeable and retains water in tr.e pore spaces between particles and rejects an·; excess. 1.: bservaucns cur1r.y rainstorms indicate t:1at the typical soil zone will absorb about 2 1ncnes of water before some water is rejected or moves to the underlying bedrock. Fully s.:iturated, t~e soil will probably retain 3 ,nches ot water per teat of depth. T!:e capacity of the soil to hold large volu:nes of water, together with infrequent maior rainstorms and a high evapotransp1rat1on rate, seriously reduces .;rouna-water recharge and storm runoii. Eva potra ns p1ra tion Most of the water trapped in the soil zone returns to the atmosphere by evaporation or tran- spiration by plants ( evapotransp1ration). On St. Thomas this process 1s active throughout the year, and 90 to 95 percent of the rainfall 1s returned to the atmosphere. The tendecy of the soil to granu- late 1s also conducive to evaporation, ,\s water 1s evaporated from the surface cf a saturated tight soil, the soil again becomes granular and exposes the soil at depth to the circulation of a 1r. Con- sequently, further ra p1d eva para t1on of soil mouture results. Transpiration is a major means of water loss from the soil zone and also from the upper part of the aquifer, 1f the water table u 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 tamannd, transpire water from depths of more than 2 0 feet. The effects of evapotranspiration may be seen in the channel of BoMe Resolution Gut below the gaging station. The gut flows 1n a predominantly bedrock channel a few feet wide for about 1. 500 feet before reaching the alluv1ated embayment at Dorothea Bay. Base flow of the stream. 'Nhen less than 10,000gpd (gallons perdity), disappears in this reach. The loss is attributed principally to transpiration by the dense growth of brush and TUT (:() 1. \ ( (a) avera t annual co (b) March 25-26 1963 c:- l-,.-. k) April 7-8 1963 ( (d) Ma 9-13 1963 (t) Au ust 28-29 1963 0 I , I J 4 5 MILU IC&LI fCNt ALL IIA,S (f) December 10-13 1965 Fl(Jure 7 .--laohyetalt ln lnchea of the long-term distribution of rainfall (a I and of lndlvldual ralnatonn a ( b-f) on St. Thomas. ---- trees bordering the stream. from the appearance ~f the vegetation in a dry period, only the vegeta- tion in a stnp about 100 feet wide with a total area of about 3 acres benefits from the stream. ;., mini:num water loss of 10,000 gpd, 3. 6 :-:-:illlon ;a llons annua llv, •.11ould indicate r.n eva ootra ns ci- :a tion rate of 1.2 :nillion .:;aUons ceracre ;ier y~ar, -Jr 44 mcnes. Bowden ( 1968 l computed monthly potenual evaporauon ana soil-moisture deficiency at SL'< stauons on St. Croix using the method devised by ·:. ·.v. Thornthwa 1te. Potential eva porauon ranged from 58 to 69 inches and averaged 62 inches per year. Actual eva potranspiration ( den ved from potential e•,apotranspiration and change in soil moisture) ranged from 41 to 46 inches and averaged 43 inches per year. Bowden's data shows a soll- ,ioisture deficiency 9 to 11 :nonths of the year at the different stations. Surplus soil moisture -Jccurred only in the months of Septemoer to November. The authors believe that condiuons are similar in St. Thomas. Streamflow The 5 to 10 percent of rainfall not returned to the atmosphere by evapotranspirauon from the soil zone either recharges the ground-water reservoir or runs off to the sea. Annual runoff in a time of average rainfall ranges from about 2 to 8 percent of the rainfall. Most stream channels on St. Thomas are dry •nd carry only stonn runoff. Only two streams on :he island have perennial reaches. In these reaches, about one-half to three-fourths of the flow is storm runoff, and the remainder 1s base flow I ground- water outflow to the streams). From O. 5 to 2 inches of water annually reaches the sea as storm runoff. The .!mount of storm run- off vanes from basin to basin, depending upon topography. soil moi1ture, exposure, and vegeta- tion. Base flow of the streams with perenrual reaches. wl-ule often equal in volume to storm run- off, seldom reache1 the aea. The flow usually 1nflltrates into alluvtel deposits m the lower reaches of the streams. Ground Water From O. 5 incn to as much as 5 inches of the 10 rainfall annually infiltrates the so:l ~nd rocks to reach the ground-water reservoir. ·x,Her 1n the ground-water reservoir or aquifer :!:oves ov :;rav1ty toward the sea. ·,\'here the water :a::ile 1s intercepted by the land si.;rface. ·.vater :s dis- charged as a spring or as :::ase tlow t.: a stream. 'Nhere :t :s r.ear the lana surface, :i.;cn as along stream cnannels and in coastal <2mbayrr.ents. large volumes of water are transpired b•r plants whose roots tap the ground-water reservoir. T!"le transpiration by plants directly :rcr:: :!"le water table 1s so great that only !':llnute quantities of ;round water ever reach the sea. 1.?1t:-ier as stream- flow or as seepage directly t:-.rou<;n t:-ie sod ,Jnd rocks. i"resh- Salt-\Vater :nterfoce Fresh water :n the aqu1iers -"lom; ~:-ie coast ;s :n contact with salt water 1n a c·,nar.::c =·,ste,i. So long as water levels grade seawara, fresh water will discharge to the sea 3t t~e snore. During times of ground-water recharge. the tresh- water lens thickens, duplac1ng the underly1 ng. heavier, salt water downward and seaward. Dur- ing times of no recharge, the fresh-water lens thins, as ground water ducharges to sea. Salt water, which moves into the normally fresh zone ::f water dunng times of no recharge, is not entirely flushed out by fresh water when rech11rge occurs. Some remains behind, where 1t mixes with 1nflwc1ng fresh water. The interface zone of brackish water 1s thick where fluctuauons 1n the size of the fresh-water lens are large. In some coastal areas, where the fresh-water lens 1s thin because of lack of rainfall or unfavor- able topographic or ge0Jog1c 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 1s delicate and can easll·1 be d1srupteci by man's quest for water. Salt-water encroachment can readily result by removing more water from the fresh-water lens than 1s being replaced by recharge or by pumping a well at un excessive rate. 1n which case the fresh-water head 1s lowered, and movement of salt water upward or honzontally into tbe fresh-water zone 1s induced. Tl.J·r u,Jl ·.v ,HER SOl'RCES Fresn water has always oeen tn cr:ttcal supply ~n St. T~oma s. Rain collected on roofs a nci stored tn cisterns is sull the source of water for most rural ano 1.:rnan do:-!1estic supphes. 3efore 1960 :ullstde ram catch::1ents and a iew dug wells ·Nere the maior source of ·.-1ater k,r puollc supplies. Since t!":en, ::esalteci water nas :::iecome tne maier source of water for pu~hc supplies, 3nd water ::arged frorr: Puerto Rico :s a close sec one::. Charlott1::: .:.:nahe Charlotte Amalle has a dual public ·.vater system. fresh water is used for dnnklng and general house- hold needs, and saltwater is used for sanitary and ~ire-control purposes. The fresh-water sucply. obtained from salt-water dist1llat1on plants, hill- s1cie rain catchments, and a well, 1s supplemented by water barged from Puerto Rico. ?otable water use and the sources of the water tn figure 8 not only show the increasing demand for water but also the shift m sources of the water. In the late 19S0's, with the exception of 1957, a drought year, catchments were the major source of water. Barged water became the major source of supply 1n the early 1960 • s. but by the late 1960' s, desalted water became the principal source of supply. Nearly all buildincs, both pnvate and public, in Ch.ulotte Amalle have roof catchments and cisterns. In 1926. before the establishment of a public water system, ,3bout 2 00 pnvate and 17 public dug wells were in use m the urban area. Since then most of the wells have been abandoned because of sewage and sa it-water con ta min .. oon. Some of the salty water was drawn mto the wells from the sea as a result of overpump1ng, and some of 1t entered the wells from leaky salt-water pipes • . .), few of the wells are sull pumped occasionally for nondnnlung domestic supplies and for construe - uon p1..rposes. In recent years, wells have been dug tn eastern Charlotte Amalie for a supplemental ·.-,ater supply for the two pubhc-housmg projects. Several other wells have been dug tn the same ;eneral area for wac« for nondrinkrng domesuc -.ise. Since 1926, 18 public h11ls1de rain catchments have been constructeci. Of these, 14 are con- :-iected to the urban water-d1stnbuuon system. 11 'Nater 1s haded from the rema1rung four catch- ments by md1v1ciual users or by water haulers. The total area oi the public catchments 1s esu- :r.ateci to be 24 acres. and the storage 1s esumated to be 1-l miihon qallons. Reli~ble figures are not available on the amount of water useci from any of the catcn::1ems, ;;iut total yield 1s estimated to be 30,000 gpd. :n addition to the pubhc catchments, four privately owned catchments are 1n the urban area. .::.. gallery well at the airport was an important source oi water 1n the 1950's. :t reoortecily ,1elded 13,000 gpd. :.n attempt to increase pro- duction resulted m salt-water encroachment, ruining the well as a source of potable water. la 1962 the first desalting plant, wnh a capa- city of 250,000 gpd, was put into production. :n 1966 a plant of l million gpd was put into produc- tion, and, by 1967, the start was made on a 2.5 :nillion gpd desalting plant. The demand for water has increased six-fold su\Ce 1960 and shows little 1nd1cation of levellnq 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, h_as had to be continued to meet the demand. The desalting plants reportedly will produce water at an average cost of about Sl.00 per l.000 gallons when operating at maXimum efficiency. The cost of barged water from Puerto Rico depends upon equipment used, but in 1967 averaged about S3. SO per 1,000 gallons. Water 1s sold to the consumer at a cost of SO cents per ton, about S2.00 per 1,000 ai'111_,....ns. The d1fference betwe6n pro- duction cost and delivery cost u absorbed by the '.'1rgin Islands Government. Rural St. Thomas Rooftop catchments and cisterns are still the ::-: ajor source of water for rural St. Thomas. Dur- .ng prolonged dry periods, rain water 1s supple- ~.ented by water hauled from public-supply points .:1 Charlotte Amalie. Small ponds have been con- structed, tapping storm runoff for irngauon water :or truck gardening and drinking water for stock. Since 1962 several private wells have been drilled Tl...lT -- C'bservat1ons md1cate that wind velocity ana roof ccnfigurauon are major factors in the recovery :;f rainfall from res1dent1al structures. 21gh wind ·.v1ll blow rain off a pitched roof onented parallel to the w1nd, whereas a rain shadow in proport1on to the degree of roof pitch will occur on the lee side of a roof onented perpendicular to the wind. A V-snaped roof will be affected in the same ::-.anner, 3lthoug:-. probably to a lesser degree. T~e :::ost efficient 1s probably a flat roof with a low lip c:r:Ju:10 tne edge. '.Vater cannot blow otf tr.e roof. ncr 1s a rain shaciow created, and the hp converts tne root lnto a temporary storage container dunng ::1gh-ir.tens!t'1 rains. Rainfall recovery on flat rc,ofs :s probably greater than that measured fror:, the h1l1s1ci~ catchments, whereas recovery 0n pitch roofs 1s probably 10 to 20 percent less, depending •Jn orientation and steepness of pitch. F:gure 2 S shows an estimate of the annual costs of collecting rainwater and of cistern storage for a small home. Cistern cost, amortized over a 20- year period at 5 percent per year ( interest costs r.ot included), 1s estimated to range frc~ 55 .00 per cuo1c foot for 10 percent storage to :52. SiJ per '.:ubic foot for 100 percent storage of the total annual recovered rainfall. Rainfall recovery was est1:natea to oe 70 percent ct an annual rainiall Jf 40 inches over l. 000 square feet oi root. :.e- covery under these conditions would Ylela -l6 gpd. !twas assumed that water loss due to :nsufficient storage would be macie up by water purcnasea from water haulers at costs of 10. 20. or JO dollars per 1,000 gallons. The figure shows that, using these cntena, the opumum c1stern storage would be about 20 percent of expected annual recovery, 0r about 3. S gallons per square foot of catchment. ,.;verage yield from rainfall alone would be about -l0 gpd. AMual water cost would range from Sl30 to 5196 aMually, or 57 .45 per 1,000 gallons to 311. 20 per 1, 000 ga Uons. .:..Mual cost of 100 percent cutern 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 of wells are sufficient only for 1nd1v1dual domestic supplies. There are. however, a few areas where ytelds to wells are large enough to warrant 500------------------~--,-----,--,---r-,---r--, 4001---------- ------------·--- ------------- Cl) ~ I < i~Storoge 15 gallons per square, footl j I" (28 P,rcentl · i o , ' I 0 300 ..,__,_ _ __, ___________ -----+----·---- r· ------~-...... -+--...,...-1 z Supplement water ! ~ I 20 i,er 1000 gallons 0 ,, u ...I ~ 200 z z ~ 100 I, I Supplement water I IOI per 1000 allons 0 '---!:,10 ______ ----,120------:3~0---:4:1::-o--=':so::--~6;:1;:o:---;;70::--:a::-;;0~90;.-;;,oo~ CISTERN STORAGE. IN PERCENT OF TOTAL CATCH Figure 2 S. --AMual coat of water from a roof catchment of l , 000 square feet with a ma;c..'!1um yield of 48 gallons per day. 31 TUT Ra1nfau 7acie .;.--Scaie ;::;t ·.aiues tor aeterm1ning .;rouna-water potential from physical critcn<1 ana .,xamples for selected wells Topograpny !:xposure Drainage area Potential I Long term Inches ·:alue '/alue ! 1/alue :.-:res Value Sum of values v1eld. ,.pd I Crest of I North or south < 40 ! 0 d 0 < 100 1 4 or less < 500 I ridge ' .;lope I ' I General , South slope 1 40-45 l l I 101-200 2 5-6 500-1,000 I slope ; North slope 2 I Central I SheJte,ed ' valley on 45-50 I 2 2 1ntenor 2 201-300 4 7-8 1,000-5,000 I general i slope 1 valley I Large I >so 3 valley or 3 301-400 6 9-10 5,000-10,000 alluvial flat I > 400 B 11 or 1,1rea ter 10,000 + Examples Well 3 2 2 2 1 1 1,000-5,000 Well 10 1 1 1 1 4 500 Well 22 1 2 2 2 7 1,000-5,000 Well 20 1 3 2 g 12 10,000 WeU 16 1 4 2 6 13 10,000 r Ln 0 )'\ the development of public supplies for local use. The water, as a ·.vhole, 1s oi poor quality, being slightly :nrnerahzed, but Ciln still be considered ;;otable. :~ CJr. oe blended ·:11th cistern ·.vater, ;•1elding a ::-i1.xea ·.vater of more acceptable pota- ::J1llt·1. Householders ·.vno -ia•:e wells ;;enera ll·1 i::reier a dual s·;stc:n. us1nq t~e ·Nell ·.vater for washing, lawn wutenn; .. ,:-.c sanitary purposes and nm ·.vater for dn:ii-::r.; Jr.c: c:o-:1r.;;. ~rounci-Xute, ;: :tent1Jl .,...,,.. "!'')'1"'1~-w~ter potent1ul _,f Jn .1r1;J cJn 1n large part be deter:nined by Lne a, .. ,," " -"nual r,Hnfoll, t:)pvgr,1pny, and e:<posur•.: to s-.:ilar ra::1.1- t1on. [n general, ureas receiving J•.::ss t:ian ~•J .nches of rainfall hil•1e a 1-:w ,1rouna-·N,iter :::ten- t1al. The southern slopes of t!'le 1sluna. ·:;nere. because oi so!ur rad1at1on, -2•1apotransp1ruuon 1s high and recharge 1s b·N, generally have less ground-water potentiill and yield more niqhly r:11n- erallzed water than the north slopes. T-:,pography 1s important 1n th-"t ~ t..,,, !l.1tter slopes ,Jround- water recharge 1s favored. A crude scale based on rainfall, topography, exposure, and drainage-basin area was developed for est1mat1ng ground-water potential of the rocks of the 1 s land I table 4) • The different features are assigned vclues ranging from u to 8. The sum of these valu,:s 1s a number from which an estimate of the lon~-term v1eld of u well cJn be obtained. ;:,, deep well will .,;enerally ·,·1eld more water than a shallow well 1n the same location. for the purpose of the scale, a well depth of .JbOut 200 feet 1s assumed with the water level 1n the well at 50 feet below land surface. Little water 1s yielded from depths of more than 2 00 feet below the water table. It 1s emphasized that even though cond1t1ons appear favorable for obtaining .:i .Jround-water supply, there 1s always .:i p1J:is1bihty no water will be obtained as c) ,well may n.,t pcnctrute water- beanng strat.:1. ·•-;,;_ ... -;,'t;ef:":<- ~~-··. Water 1n Consolidated Rocks The permeable zuncs oi tn~ consohrl-ti:-rl rncks consist of ooen Joints and fr.Jctures. Xear t-:.e 33 land surface the joints are open--the result of ·.veathenng and release of pressure. Joint open- ings, however, narrov,, rap1dlyw1th ::ieptn, and ,;enerall, at depths of a iew hundred feet they are too narrov,, to transmit s1gniflcant quantities of ·.vater. ,\ll the bedrock for:nauons are ::>roken 0·1 faults-- :ractures a lonq '.\':'11Ch '.'."lo•;~~ent -:.Js t.J -:en :::lace. !n some faults, earth :novement has crushed tr:e rock to .,iravel-s1ze brecc1a, whereas 1r. ot'1ers t:-:e rock has oeen reduced to a ilourhke suostance called fault gouge. !kecciate<i fault zones not sealed by mineral deposits or iault gou.;e canoe very permeable u nd often extend to depths of hundreds of feet. The ,,nentatlon of :nany of the valleys Jnd bays -:v1dentl11s controlled by a iault and 101nt s·tstem ulong which erosion has occurred. ·:alleys. :herefore, are often ind1cators oi zones ,:,f Jn extensive jointing or fractunng system that may con ta in ground water. The yield to :,ells dnlled in the bedl'O<.;k 1s small--qenerally less than 1,000 ~pd. :'l.1any wells will yield 5 to 10 gpm ( gallons per minute 1 for about 10 hours. After that they yield at a :nuch reduced rate as a result of removal vf water from storage in the immediate vicinity of the well. Once water in local storage is removed, the yield to the well ts reduced to the general yield of the aquifer. For example, well 17 near Wintberg re- portedly yielded 12 gpm (17,000 gpd l for a 24- hour pumping period when first dnlled. Hov,,ever, almost daily use over the past S years has shown that the long-term yield of the well is abOut 250 ;allons 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 s1gn1hcantly alon~ a lineauon. One example of possible linear permeability LS the north-south fault in eastern Charlotte ,:,mahe. Permeability, as determined from pumping tests of wells, ranged from about 1 to 9 gpd per ft 2 ( gallons per day per square foot l east and west of the fault. Immediately along the fault zone 1n the vicinity of the race track, however, permeability ranged from about 70 to 150 gpd per ft2 . South- 2 ·.vard along the fault permeability was 1 gpd per ft • ~·: . .L TUT The effective porosity, or storage capacity, of .____ the consolidated rock also is related to open inter- coMected fractures and Joints. Effective porouty 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 1n Unconsolidated Rock Water-bearing unconsolidated deposits are present only in Turpentine Run Valley and in coastal embeyments. These deposits consist of two dif- ferent lithologic types, which have a variety of water-bearing characteristics. They can be divided into ( 1) a bouldery silt and clay alluvium, which contains lenses and beds of sand and gravel, and ( 2) beach deposits, predominantly coral sand and occa11onal tnterbedded zone ■ of coral, beech rock, and organic silt and clay. In the coastal embey- mentI, alluvtal and beech depo11ts may interfinger. The alluvial deposits are predominantly fine 919ined, and, although they have • high porosity, they have a low permeability and will yield water only slowly to wells. Weter in the•• depo11t1 11 with faw exceptions under water-table conditions. Send end gravel beds and lenN1 in the elluvtwn are rerw. Where preHnt, however, they will yield water readily and act a• • large collector' system into which water from the lHs permeable alluvium will percolate. Occa11onelly the water in the send and gravel beds is under artesian pressure because they are confined by the le ■s permeable ovwlyin; alluvium. The beach deposits, principally medium to coar•• coral sand, have• moderate to h19b per- meebility and poro11ty and wtll yield water readily to well•. The moderate to high permee111ty of the beech depo11t1 1s often detrimental in that Hlt- water encroachment can Nlily OCCW'. Ground water 1n St. 'ftloma• 11 HIUmed to be under water-table conditlona--that 11, the water ■urface is unconfined, open to the atmosphere, and frN to riH end fall. Sufficient data are not avail- able to 1how contours of the surface of the wetar table throughout the 1Ilend. In genenl, the water table roughly parallel• the topography. The depth 34 to the water table ls a few feet below land surface in the coastal embeyments 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 1n the ground-water reser- voirs. The water table nses when recharge from rainfall or streamflow exceeds the discharge: it declines when diScharge to spnngs, streams. or the sea, evapotran1piration from the water table. and withdrawal of water from wells exceed recharge. Water-table fluctuations The hydl"09raph of well 1 in figure 2 6 is typical of the water-level nuctuauons in the rock aqwfer 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 r11e 1n water levels, but the steep hydraulic gradients result in rapid lo11e1 and almo1t a1 rapid declines. Fi9ure 27 11 the hydl"09raph of well 24 tapping the alluvium end weethered bedrock in the lower Turpentine Run Valley, and figure 28 is the hydro- graph of well 21 1n the alluvium of the upper basin. Rech81"9e 11 received every time 1tonn water runs off 1n the 1nam and water level• r1H. BetwNn Um•• of 1tcnn runoff, ground-water levels are partly maintained by the inWtraUon of base flaw from the stream when now ts pr91ent. The hydl"09raph of well 19 in figure 29 show1 the pattern of watar-level fluctuations of the rock aquifer 1n upp« Turpentine Run basin. The pattam 11 11miler to that of the rock aquifer of the north coast and Jarver valleys on the south coast. Here, greater permeability end 1torage c.pecity and generally thicker 10U end elluVium re1ult in a slower but more prolo119ed response to recharv• and a slower discharge. The "trougti." in the hydrograph dur1119 Nrly 1965 were cau1ed by pump- age ( aventglnQ 18,000 gpd) from a nearby well. Recha,ve 'nl• bedrock aquifer ii principally reche,ved by infiltration of rain on the lend ■urfece. Stream- flaw and 1tonn runoff locally recharv• the alluvium, which may, in tum, contribute water to the bedrock aquifer ln the maJcr valley• end allu- viated coastal embaymentl. TUT OU.1. i I t i Ra1niall, vegetation, evaporation, surfic1al dePoslts. and exposure to solar radiation are the main factors affecting recharge to the aquifers. Leaky-salt water and sewage mains 1n Chadotte ~malle and effluent from sewage plants in the Turpentine Run basin also contribute water to the aquifers as does effluent from septic tanks through- out t!-.e island. Recharge from these sources 1s detrimental as lt 1s a potential source of pollution. The bedrock aquifer is recharged infrequently and only after a heavy rain or series of lesser rains. 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 rap1d evapotransp1rauon. Conversely, the granular nature of the s011 wlll allow water to pass through the soil zone without the soil being completely saturated--saturat1on being required only along the conduits between the soil granules. This reduces the water needed to satisfy soil-mouture requirements before recharge can take place. Even then, under dry conditions, a major rainstorm of 2 inches or more, or the equi- valent 1n lesser rains, is necessary to initiate re- charge to the bedrock aqwfer. The amount of rainfall necessary for recharge vanes from one part of the island to another. On the north slope 1 1nch of nun 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-fac:1n9 slopes u less frequent than on the north-factnq slopes. Less frequent recharge on the south slopes is attnbuted to the greater solar radiation received .by these slopes, which results in increased evapo- transpirauon and a greater soil-mouture deficiency. Consequently, a greater volume of water 1s neces- sary to overcome the soil-moisture deficiency before recharge takes place. Where the surficial deposits ( saprolite or alluvium) are thict;:-rancJin; from 2 to 15 feet, as on the north slope in tlaa vicinity of Dorothea, in upper Turpentine Run bean, and in the alluvial embay- ments. such as at 1.on9 Bay and the Harry S. Truman Airport, water is retained 1n the surficial depcs1ts and takes a much longer time to reach the bedrock aqwfer. Peak recharge to the bedrock aquifer may la; as much as a month behind the rainfall. In some places little recharge reaches 37 the bedrock aqwfer--as most 1s discharged to spnngs or streams directly from the saprolite or alluvium, as has been observed in the vic1ruty of Dorothea on the north slope. Runoff from major rainstorms is the principal recharge to the aqu1fers of the coastal embayments and is an important source of recharge to the alluv1um of Turpentine Run. Base flow of Turpen- tine Run and Bonne Resolution Gut at Dorothea Bay, when present, also contributes recharge to the unconsolidated aquifers in their respective basins. For convenience of discussion, the island has been divided into hve ground-water areas as shown in figure 30. Estimates of yield in these areas are g 1ven 1n table 5. Table ; . --Esumatecl yield of ground-water .. reas. , See fig. lu I ..,round .. wate-r ~,ea, estimated y1eid .:r:nuttl rKnarq•. 1rea lq ffll HXI ,,.,q,yr , ,-ches l 13.6 450,000 164 ,J. 7 l I Long Bay l . 3 !/ 70,000 ,11 25 ~.9 I I undberq !14y I . 2 1 30,000 ,11 11 ~.3 2 3.4 350,000 128 2.2 Z Upper oas,n 2.3 300.000 :!; 110 2.8 2 3 4 5 Lower 0as1n l.1 50.000 ~/ 18 1. I - 4.6 250,000 91 1.1 .q/ 100,000 16 ; . 3 10.0 100.000 36 .2 Total 12 I. 250. 1100 ~55 .V Apprcx1mate are• of alluvium only. Y Does not include dnuna9e be11n1 at Ar••• 1 and 5 ·Nh1ch eontnbut• reeharqe to Area ~ from surfaee- . .,ater runoff. Y 'i':eld 1neludecl ,n Aree I total. Y 'field included ,n Are• 2 to'8l • Ground-Water Areas Area 1 Area 1 encompasses about half the land area. It is underlain principally by fractured volcaruc tuff and breccia of the Louiaenhoj FOffllation, on which l or 2 feet of soil have developed. On the south side of the island, from the vicinity of Charlotte Amalie westward to Brewers Bay. the volcanic rock ha• been extensively fractured. The fractures. however. have been filled with rur 001 ( ... i-:. A •' 0 (·•··~ ······· 2 ( .A TL.ANT.IC OCEAN ~ ~ EXPLANATION POii IYM80L I Surface-water 909in9 station OriUed well, number reftred to ,n teat. Dug well Gallery Sprint, llllfflber ref ered to in teat. Roin 909e Pollution from salt -wot er moins Encroachment by sea water Boundary of area Alluvial deposits Areas, see taplonotian below •••oo· CARIBBEAN 0 2 J ...... ... ,,. ( SEA •••,o· ( ( A If.I' A fr-,• E X P L A N A T I O N . ' . Areu 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 ( Area 3 Wells in rock SU to 200 feet 111 deµth will yield uµ to 5,000 gµd. l11 some larljcr drainolJP b<..1si11s, yields up to )U,OLIO ypd may !Je possible. Water contains about 1,000 my/I dissolved solids and about 200 my/1 chloride. Wt'lls drilled near the sea and below sea level 111<1 y yield l>racki sh water when drilled or if punipetJ ,it excess1Vl' r.iks. Area 4 Wells in limestone SU to 150 fovt 1n depth will yield up to 50,UUU ypd. Short-term yields of selected wells may be ilS yreut .:ls 1 511, 111111 ypd. Water contains about J, 5110 m<.J/1 disso/v(?d solids and 200 to 300 mg/I chloride. Wells drilled near the sea or below sea level nwy yield brackish water when drilled or if µumped ut excessive rates. Area S --.i lower Turpentine Run. Wells in rock 50 to 300 feet in depth will yield up to 1,000 gpd. In general yields are small. Water contains 1,000 to 1,500 mg/1 dissolved solids and 300 to 500 mg/I chloride. Wells drilled on penin- sulas and in coastal areas yenerally will encounter brackish water. Ground water polluted by leaky salt-water mains in Charlotte Amalie c1rec1. ; __ _ ---1 '..._.• ~ Figure 30 .--Ground-water areas of St. Thomas show1ny location of wells, sprin,Js, stream gages, and rain gayes, ,. secondary minerals. Alluvium and beach deposits fill the coastal embayments and are especially prominent in the Charlotte Amalie area. Ground-water levels range from a few feet below land surface 1n 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 ridges and least in the valleys and lowlands. Wells range in depth from 50 feet in the low coastal areas to 250 feet or more near the central ridge. In general. the higher the altitude of the well site the greater the depth of the well. There 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. 'n\ese, of course, are extremes. Long-term yield• of wells generally ran9e from 2 SO to 1. 000 9pd, althou9h initial or short-term yields may be 10 time• greater. 1\¥0 valley areas, Long Bay and Lindberg Bay on the east and west edge of Charlotte Amlllie, re- spectively. have 9reater 9round-water potential than the remainder of Area l . Long Bay. --The Long Bay area lie• in a bHin about 1 1quar9 mile 1n extent, of which about O • 3 square mile is alluviated coaatal embayment, and the remainder is steep-sloped volcanic rtd9e1 with little 1011 cover. Alluvium a• thick as 60 feet overlies the bedrock. Near the coeat the alluvium underlies and interf1n9er1 with a thin beach-sand deposit. A relatively impervtoua clay overlies the bedrock from a line about 1,500 feet lnland aee- ward to the shoreline 1t l.oft9 Bay, and probably extends out under Loaf lay. Water 11 present in the alluvial deposita, llut the main aquifer 11 the underlyin9 volcanic ro.ok~ In 9en .. 1, the bedrock underlying the elluvtuiia yteld1 more water than that underlying the rtd9H. The &one of graatelt yield 40 to wells 1s bound by the t'NO fauits pass;;:c; ::,r,:-_.;;-. the area. -~ factcr c:;..;r::r:i::r.:~::-:; ::, the :)r.::duc~:·:tt·,· -f ·.,v: ::>edrc,ck 1s ~he -;•,<?r.ir,::1 alluv11 .. :n that .:ic:s ::,; J st,;~J~,e r~s 1r-:c lr. T:·.e : llu 1:!1-::1 ,:::-r.tj:::s .. j:":J.:? -.;uar.t.~~s -)f ·.·n~::?r. ~~c~us.:? cf :ts; :-.v ~~r'T1Ed- b1lity 1t generally ·,-teids l1tt!e w<1ter '.0 ·.-:e!ls. but 1t yields ·.vat~r sic·::ly to tne .. ;-.::er!·::r..; :::e-:- rock aquifer. rhe i:;n:ic1pal .:irea ~f rec:-: ,~,e t..: th'! bedrocic aquifer tr.:irn rhe a1l1.:·:,:..:~ : : : :::,~ foot of the volcanic ndqes 1nlanc .::r .::·? •:-: ;e ·: the impervious clay wedge capp1nq =~-= .::•..!':~..:,:-: and mostly upgrad1ent irom the area ,,i c.:iit.·,· :~- water mains. The long-term y1eid cf the allu·✓1um-:;P.drcc!c <Jquifer 1s estimated tc be from 60, OCG ··1 <:;1 :;r,o ;pd. The yield of wells ranges frcm a:::;:.it ;:O to 70,000 gpd. The h1gh yield ot s.::rr.e •.)t :h? wells, however, has little to do ·Nlth :rie [,_;-,: - :erm yield of the aquifer. Susta1:iec ;,•;mpag~ ::-. excess of the long-term yield of the a ◄u1fer wul deplete the fresh ground water 1n storage ar,d r~ob- ably result in salt-water encroachment. Salt water has encroached in a MITOW strip c! the alluvial aquifer bordering Long Bay because oi p.unptng dUCJ wells 13, 14, and 15. which su;Jpiy Pearson Gardena public hou11ng. Nearly half the alluvial aquifer, however, ii contaminated to some degree by lNlcy salt-water mains. The approximate limits of salt-water contamination are shown in figUl'9 30. The bedrock aquifer under- lying most of the contaminated alluvium contiuns fresh water becauae the prineipal recharge area 1s upgradtent of the relatively impermeable clay cap overlying the bedrock throu9hout moat of the contaminated ar••. Salt water ha• 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 eMular space between the wall of the well and the caainCjJ was left open, and salt water moved down the aMular space, contam- inating the bedrock aquifer in the vicinity of the well. TUT <)()l ) I ' I I t ·- ~-...:.:~··-:-.i ~·, -- ~~'= ali'...l\.-t~. ~~-:: ::--.- . .: .,.~r_.r ~1:-:iiL::- ·.c .::- --~ ~~-~~ ~~-·:r-=! _. -::: ,;r.?9rvt0 1 ~.: .- •• .- ·.:, ::::; ti':i;i. :~e a r.c ::>~: - _..,_ : : : .• ·•:-.-::.; :r-- :'1 . : .. ~- : -. -: t~:: _; . :·:: :: ; •:.'~l~S ~n tr.I:? , --- : ~ :.·, per::-.•.:~011:t·:. . :-:~ : ·: r. ~ SL t·, ,:,f ::--.'? ! -··- ',/~,; ·;-. lS ;;r~ :)~ ~ 1y , ... ;,,::-.;, '.; :·. t. :-· -· · .. ,.cr~~!/L:::; ':~irccK 1.: . ·<..:.J;.;.~ ::r0cc1a -1n,. :'.J:~. -,t.-::: :: :t ,Jit~~~,j :}: ... · --:::j: ::--:;:;. i'\trUSlOns. . -~""' · ··r~ -=~·..;ru:.: ~-= ~:<t~r.3:·. ~ ··:..: ::-:c:"i·/ -:f tt'":e :::..::. ~~:, ~l~ fdt~u ·;.'1th.:-=-·~~:- :.~r; :·.::it!r3~S. ~.: 1 '°:':r:, ci 2:.10 f~~t. .'.'-1:.-: -, ::11J O 7-3ve :: . >:-.;- iG:-:-. ·~-'Id. ~,H~rna ~"'•.! ~c '),1 : • j ,,J ,::pd. 3e~r::i:i: · .. 1:-•. 1 ~ '.:-:ihab1·1 ·.•1di :::C?ld i:.:.:•.•J oi:d 1n the ".'i::,.:.:~, -,~t , ,~e 'O!r-.ba'frr.cn: !.or.,·, .-::t the ,:11r;:ort. !::e 1J..!-· . .-:,_::~ ·e ~e!dt1t.1 ~i·., :hie·~ :~'!rill! ~nd, tn'Js, ,t ;l~.:,•1!·..: .:ontr:::-i..:a :;.:,::.i!C~-~~le :,uJnt:t.es ::: wJter '.J -~ . .:. ·.:,.i12rlv,nq o<o/.iro-:i<: .;.;i.::for. ~ .• r1,;,:~!"-~::3l yield::,! :!ie ::~drock aqu1!1:r ·- .. ,·::: ·,•••.i :c .:,e JC. J11J ;pd, JSSi..!':un,; ::1.:ita -:: :ai ,~tl -r~~. . ·a I.vn~ aay ,1L!a ca~ ce applied. 5a1t-·N11ter mains ln the 9oume Field housing ~rea or~ known to leak, <1nd 1t must be assumed :::Jt ::-.:? ,Jlluv1um in that vicinity 1s contammat'!!d. 7::e same care to prevent salt-water contam1nat1on :,y 1r..:;roper well construcuon must be taken n~re , s in the L~n-; Say area. .:.t on<! U:r.e a gallery parallelin9 the runway H :he :urport w•• used for water supply. This ;;.:ill=ry, which cotlectad Nnoff from the l"' . .mway ~r.ci :.toreu w3ter tn Che •lluvium and landfill ; .:ir .:\ .. t~re •J:.e, :-;,1d • yteJd estimated to be 11,000 ~pd. TJ:-.for:ur.dtei.y, the 9allery wa1 overpumped ~nd salt-water encroachment followed. Salt w~ter 1s still present in the alluvium near the well and is :r: a position to intrude the bedrock aquifer. '.'later from the gallery occasionally is used for 41 -.::,::3ble purposes. The use of water from -4··:::.:i·: drainage for dnnking purposes, of course, ~ :.;d r.;erous because of the presence of tox1c ~;;".'.O!"tJnds such as hydrocarbons and tetraethyl ,-': .. -: :r:im spilled a1rcraft fuels. red 2 is the drainage basin of Turpentine Run. ,· . ;r_•,.emence 1t 1s separated into an upper anci . · ·:1ter :;a sin; the upper basin above the stream- -, :1:-.-! .;tation near Mt. Zion, and the lower basin . ..: .. • ,,. The pnnc1pal rocks are volcanic flows . · .. :·:. Jr.d brecc1a. Alluv1um as thick as 40 feet . . ..:5 .:c ::,e main stream chaMel of the lower basin. ·. . :r:hwest-onented fractured a net jointed zone ·.:,.~rrit:,ermally altered rock buects the upper .. ·;.; 1r. . -:'i:l:~ wells range from 40 to 250 feet in :!::Cth. 7he shallower wells tap the alluvium anci · :-~a:..th<!r-:·.! bedrock of lower Turpentine Run. 7he :iepth :::f !he rock wells is not necessanly a cn- ~0r,:::-; of ,reater yield, but is usually an 1nd1c3- ·: .;n cc 'Nhere a zone of water-bearing fractures ··:,u oeno!trated. Short-term yields from indi- '-"'.Ju.i l rock wells in the upper basin are as ~reat -.s l ~ v, JOO gpd. Sustained yields, however, ~, :,qc from about 3,000 to 30,000 gpd. Inch- ·:: .,i.:J! ·Neils in lower Turpentine Run yield as :-:-.,·-:::, 1s 30,000 gpd, but sustained ground-water ·.-:,:!-:draw<Ji.s of more than 10,000 gpd will r::robably r~ "'.llt ,n sea-water encroachment. .";r,;,ur.c!-water levels.--Contours of the ground- ·:1.3ter Sl.irface during August 1965 and January 1 %6, .:ire shown in figures 31 and 32. The arrows on these map■ indicate the general direction of :1round-water movement. In the upper basin, ·,,hen water levels are high, ground-water flow 1s spht--part moving along the course of Turpentine Rur. .1nd pa:-t moving through the fractured and :iltered zone at Mt. Zion and emerging as a sen~s ()f springs discharging to Turpentine Run in the lower basin. When ground-water levels are low :n tne •J pper basin, nearly all ground water Is .-robably d1 scharged through the fractured zone at ~-1t. Zion, and a temporary ground-water divide 1s establuhed at the position shown in figure 31 • Grour..d-water levels in the basin fluctuate 1n relation to discharge from and recharge to the aquifers. Figure a 29 and 27 are the hydrographs of wells 19 and 24 arilled in bedrock in the upper basin and in the alluvium and weathered rock of i'j Ir J •._I t (i()J. REFERENCE NO. 17 ·- . :, '\ ,;, '·i - 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 HCh district within the radius of interest. In cases where only a portion of a district is within the radius, population was prorated by area. TUT uUJ_ t j f t ,• ' t f . - Kris BUl'OI WATER MANAGEMENT PLAN FOR THE--~-- ___ --.- ___ _ PUBLIC WATER SYSTEM -.. - ) l: ,....., ., ... I Prepared for ._ , THE DEPARTMENT-OF _____ - ------ -- ---- ---- ---- -- --- -- - · CONSERVATION AND . CULTURAL AFFAIRS GOVERNMENT OF THE VIRGIN ISLANDS -...~-· -· --:- ~~~~ .·_· . ,, . Prepared by - . CH2M _ CH2M HILL SOUTHEAST, INC. IIHILL Project No. GN1432.5.AO ----;..... July, 1983t .._ - '- A- .._ ... - .. .. ... ... - ' I I \ Table 3-3 DEHOGRAPHIC DATA FOR THE U.S. VIRGIN ISLANDS '"6:9: !!!! !'L'C!" •11• JIICIO P•~•c&e4 hf• ...... ti. Uid. fNca .... .. ... ,.,..c .... lad• ... ..... .. .., ... ...,.,ea1 fiijiiiT •U• .,, '"'"· . ....... • Mot. .. ....... , !:·=~11"1 m;pL '-'IF') ~ ~ Sl•• .. a ll!•-1 ,.,_,., ··•.!l ";r> ,, ...... ll!Hs_, U!fiir!L ~!!l er;> ~ D! m ,. ....... ' 1,•n , .. ~" " .. ,.:au 11• loH " ,. 1,,s. Hlo u, ,. n• I "' ' .. , •• 11 Ml ,. •• l,Uo '° ue ,. > JSI 06 - :a, Ml ,,. >SI H ,. .. ,. >N n • IM II ... n, II n u, JO ., .. s ,s ·- •• "' ftJ'MAI• l";QI ... ID· - II r.tn r.m m m m J;lU 0~ nl !.ll m I II.a.- l l>S IU ,,.. I J16 II .. HS II ... ,... u ... J us • .,, • JH • so u • •. ,n u .. .. , ... , ,. , .. NI ,. ..... SJ J .. JC, >• s '·"" ,. u ,. 1.11• JI 12 ,. J,IM JS 12 0 • .. ,., , .... , .... u: .. ,.121 '·'" 1.u, ii,)) IH , .... ),SU J,SU, 1oU IH 1 .. ,,.. II ,,. n .... , IS ,,.. JIO ,, l,JSI H ,,,. JU H • ..,u SI ; .. l,JSJ .. "" J,tH "' I ,29" •• • '·"' ~ , ... n , •• ,s ,n .... H t,HJ ... , .... u .. .,.. lM · HI Jll a• ··=~ , .. ISi .. , 1n l,IH sso HI UI IU u ,.. I I 161 , II :a.an 114 ... Hill ,. Mft an ,.. u, .,. J,JJ:a u, ..... , ... , . u ,.,,, 211 .... , ... ... • 116 .... , '" Ill ,,.,,. JSO 1,061 JH ... .,. .. , 21 .... JtJ . 11 .,.. HJ "' J64 IS J,HI ... JI MJ >,>H u ,a 26) • ,,,.,. . ... n 2'1 , . •• ,.,,. . ... ,,us .. ,. ... ,.,u J , .. ,. us ... us ,.,n ,.,u ,,us u, ... n , .... ···" 1,161 HJ HI .... , ,:ast ,:n, Hill atl '··" ,.us J,SiS '"' HS II II n • IS ,.. ... H •• ,,.. .-;JI dU ldl n;dl 111 ... u• 111 r.ril ... _ ... «;t1I R';l1I m li;4il r.m m ti:m n:m IT.Iii r.n1 II. C.el• I >JS Ill u .. • ,.,, ,. n HO H '" ,o JU HU H I >,NJ .,, l,OK ., ss ,.,,., ... .... , H st s,, • ...... J,OtS IIS H > ...... n, 1,111 ... .. ... us aff •• ,u n• •• u,, .. tS1 1,111 110 II ,. U1 IH .. - aM •• .,. 22, •• ' HJ II •• .. )SJ lJ • .... H t .. IS ,., .. • ti JS ... .., t l)I,, ,. , ..... ..... ,,,,. ..,,,. •••• a.,,. 1.11, .... , J,4SO I a.• ···" ··- IS • •••• .... , , .... ,. • 1,111 l,tn ,,,u S6 H t ..... •.•u , .•. •• ..... ..• , ,,,., •• . .... , ill,HI ,.-• •• •• a,•1 - ... u n l,Ht .. ... II n 1,1u H6 "° 6Z JS 11 1,illtl .. " ... n , .... .. , " - u ,.11a .. . "' ,.. ,. ll ,,,,. •••• .... . , • • , .. ..... •••• ,., a• ,.,n ..... I ,Ht ., ... IJ ,.,n UI , ..• ,. - a• ..... ,u ... aoe .. - '" .. .., II as ... ffl '" ... H SIJ . , Jtt a.a H •• JJJ Jtt ,., u •• "' ... .. .. n ... an ,.. a• II IU IU ,.. JIJ H 11 •• - lM ., ,.., ,.,. Hill ., ,. .. u, JSI, IS •• .. .. u II u u It HI ,.., •• ,.., II • ..bW .J.W ...!.Jil JI! JI ..hlll ..Ll.11 ..L!!! _!!! .J! .iJ!! -L!1! , .... -1!! . .!! lb-.U ···- .. , .. ~·-- i.,aa ffl 61,1"S u,,. •••" , ... , ... 1,,,,.. H,Jtl n,o, a,u, ... ... Ila!!! !LBI JlJJI ~ la!Jl 1ll.eil! H&W - - !LI!! s.su Lt!! .,.,,,.. IL!.!! O.M !..iH 1,000 ..... • • ,.,._. •••• .., • -Ill f•caa ICII • 11C11eel1 ,.. • ,_,., .,,., ... GalS6 /(f/ (i(/J .. !~/()', °fflPUI 'lft'A FJr,lAA flli -- - - - -- - .. .... .. -- - - ... .. ( o,sn11cr • 01 DIHRICf • OJ DIHRICf • OJ DIHRICf • o• DISIRICI • o• DUIRICf • 06 OISIRICI • o, IHSIRICf • o• DISIAICI • 09 IUlfRICf • 10 OHIRICI .• II DISfAICf • u DHIIIICf • u DISfAICf • •• DllfAICf • 15 DISUIICI • 16 DIHAICf • 1, DISIIIICI • •• DIHAICf • 19 DISIRfCf • 20 IOfAL I SI.AND <.:: ·--·- INfl!,.NAL Ol!NAND •-------------( ( ---~• "'fl!"NAL wAfl!" SuPPt.Y -------------• •--- l!•fEAHAL OE .... ..a ---· ·---- POfA8LI! WAfl!R ----• •-- NON-POr Aal! ••11•--· POUIILI! NON-POI roua. CISfl!AN OftteA IOIM. SALf DfteA IOIAL POfABLI! NOH-POf fOfAL IUioM.10 llGM.'0 llGALID aGAI..ID ac.M.,o llGAL,o aGAL,o aGM.,o llGAl..10 llGALIO 11.GALID KGAL,O ~--------------------·---------------------------------------------------------------·--------------------- • ., .. o.o • ,.9 , .. o.o , .. o.o o.o o.o 400!1 o.o •o•• ,,.., J6.J ... ,., ... , o.o . .. , o.o o.o o.o .226•0 .J6o2 261.a .,o •• ••• •10.• I 1008 1.0 11508 o.o OoO o.o sss.o o.o sss.o I.Jlol ••• I.JSeS ••• 100.0 109 •• o.o o.o o.o 26 • I o.o 26. I , ... ••• 19.1 6e9 •• o ••• o.o o.o o.o 22.2 • •• 22.a J1.1 ••• Jr., ·•.J o.o •·.J o.o o.o o.o 11 •• o.o .JI•• 29.J •• ••• 19.J •• 64.2 o.o ••• z o.o o.o ••• 22906 o.o 21906 , .... ••• , ... , .J9o8 •••• 90oe o.o ••• OoO J.J6.5 o.o J.J6.5 .2••••' ..... o , ••••• o 11009 •12.1.s •Z.J4 • • 21uoo.o o.o ;11000.0 415.J o.o 415.J I.Jlol ••• I JI • I , ... o.o 29e I o.o o.o o.o 10200 o.o 102.0 I.I.Joo ••• IJ.JoO .J1.9 o.o .s, •• o.o o.o o.o • •••• o.o 195. I •or.a a, •• ., ... . .. , o.o . S6ol o.o o.o o.o sso.9 a, •• ., ... I .J•., ••• ,., .. , .,, .. o.o JI• S .o.o o.o o.o 10.J.2 o.c. 10.J.2 ... , o.o , .. , •• o o.o 600 o.o 0 oll o.o 19.2 o.u . I 9.2 1,a.s •••• ••••• 9e9 ao.o 59.9 o.o so.o ao.o ••• 6 o.o ••• 6 ... , ••• ... , 6• I a.o II• I o.o ao.o aooo 90.5 OoO 90.S ...... ,., 111 •• ••• 110.0 1••·· o.o 10.0 10.0 2•.2 o.o , .. , a.6 o.o lo6 o.• ••• o •• o.o o.o o.o 2.2 o.o 2o2 • •• 9 ••• •••• J •• -o.o .J •• o.o o .• o o.o 15.S o.o • ••• .,, •• s .Jr.a ...... so.• o.o so.a o.o o.o o.o 20,.7 .J7.2 .104.9 5988.J 191sa., ;,,•1••·· •Ja., •••••• 5082e6 21000.0 110.0 II I IOoO JZ I I • 7 • 0 ® ·= , .... , ... l,IOO 1.L ....... 101.c. J.JIZ.1 FIGURE 3-4. /1111tl Proj~ted demand of the service districts on St. Croix for the year 1980. ... ... ... ... .. ... .. .. - - - - - - - .. - ... • rttUNAS I !tL ANO UI'(' UUIPUI UA <QA YEAA 1980 \ OISIAICI • 01 DIIUAICI • ~l UISfAICf • OJ Ol~fRICf • o• OISfAICf • 05 Ul!afAICf .... OISfNICf • 07 01su•1cr • 08 DISIAICI • 119 OISfAICI • I c, OISINICI • II onr•ac, • ll DISfAICI • I J 01a1•1c, • •• UISIAICI • 15 PISfAICf • •• 01sr•1cr • I, Dl51AICI • •• DHIAICI • I 9 fOfAL ISLANI 'I I ;·._, •---- INfEANAL lleNAHO ----• POfABLI! ttOtt-POI KGAL,o ltGAL,o •-------------- INIEANAl. -AIEA SuPPL'I --------•----• •---- POfA8LI! WAfEA -~1·-• •-- HOH-POraa.£ ·••£•--· Cl!tfEAft OIHIEA 10 AL SALf OfHEA fOIAL KGAL,o KGAL,O KGAL,o KGAL,o KGAL,o KGAL,o •--- Eal~MHAL OtNAND ---• POIARLE NON-~Uf fl.GAL ,o IC GAL ,o ~-------------------------------------------------4-------------------------------------------------------- ••• o.o ••• ••• o.o .. , o.u o.o o.o s.• o.o s-• . .,. , o.o I 'lo 1 .. , o.o .., o.o o.o o.o 15 ■6 0.11 IS•6 a1.9 ••• 21.9 s.o o.o s.q o.o o.o o.o 22 ■9 o.o 22.v . , .. ••• es.e 22. I o.o ;u.) 0.11 ••• o.o 6,Jo 1 "." oJ.1 ll1e0 ••• ll8o9 J•. 1 o.o >•· o.o ••• •• o 102.,J o.u 102 ■l ::::: •)' . 41•• •••• s .,, .. JO.O Ill•~ o.c, o.o o.o .,s., JI •• so,.s ..... 210.1 20.J .,.o es. o.o 56.0 56.o 1J •• so.o 12J•• . ., .. •••• e2.s ... , •• c, ··-~ o.o o.o o.o 6,J • .J o.o 6J ■.J s•••• ••• ••••• 102.e 16.0 I I•• o.o o.o o.o •22 • .t o.o •2.t ■it .,.o 11.1 100.1 I .J • I u.o I lo Ii o.o 1&.o 15.0 eJ.9 o.c, 11Jo9 so.J ••• so • .J .... o.o .. .. o.o o.o o.o •••• o.o • ••• . , ... •••• 10s.• , ... 10.0 . ., .. .: o.u 11.0 as.u 1, •• , Uol> I 39 • 1 J'al., D~. I J42o0 •o.o 110.0 210.0 .o.o 6:l ■O .. 1.0 195 ■11 4 • it 200.11 ... , (,.0 ... , .. , o.o •• 1' o.o o.o 0 ·" Jl ■O o.o lloO , .... ., •• J .: ·•I• 1 JJ ■O o.o .,., .. o.o •l oO o.o I 8 I • t, 26.,J 201 ■9 ,.,.o s, .• , . .,, .. ..,. 1 .. , ., .. , o.o ".o o.o 591.,J s, • ., ••a.9 567.2 20., .. , .. 'IJ.5 ,a.o 11 e.5 o.o 11.0 o.o .... , 20., ...... 0.6 o.o o •• 0 • I o.o o. I o.o o.o o.o o.~ o.o u.s as., ••• as., .. .. o.o lo6 o.o o.o l.l za., o.o za., -------------------------------------------------------------------------------------------·--------------- J;,J ... •o•• •• 62J.9 .J.J2.0 o.o • ·~ '!:!98 '- :---~ .. ar•--i• .... " ....... as,.o 152.0 191116 ■0 -..• • ~ Dillricl• •• Nun,1.,..,1 ',," \\ I I I 190 0 6 JI 1b ■C> REFERENCE NO. 18 TUf (..',() 1. cc~- I NUS CORPORATION TELECON NOTE I ____,. CONTIIOL NO: DATE: TIME: 9.., 3>t,of11'\ I~« DISTIIIIUTION: IE'TWEIN: OF: PHONE: lJ 5 G-~ f~~~ ( ~"I h•rer ·~~ "t'c.- AND: INUII DISCUSSION: ~t'w X · Qv:S · - • e \ wL,,;,l \o:e'S6,,b- de h 9::, 0 f f'lt:i I 9 ~f - . . w:Lscb > t e!: N ,\ I ff t s::boe,. id ~ ~ ~ ,1 6:::: Ae:{«4069 :,t, .. & JJ+.drJ t.L+:---+ 2-: ~ doM:: ~ ~ fx o:4i~ ,e-- ~ ~- l, 1 b+!:>: A:3hJ v--( ,1,... .£1,Lef ::;;t.4,,t '7L., 0.i ~ .t( ,olH1<14 ,cn:::;tM- 0044 -'t ~ o(, v-:r, re~ T&:!t: ;fh- REFERENCE NO. 19 I NUS CORPORATION TELE CON NO TE l CONTROL NO: TIME: DIITIIIIUTION: IElWIEN: OF: "40NI: ---"DcV"'I hoe-f2 - W<.il C,.r~l/er ""'F>c I ca. r ·, b.e ( go~) 7,j- l/1,,o INUSI DIICUIIION: ro r 6c,J:z. S2) Q - 40 c> pc ,;.,a..t, 16d Us Qo $-f :rf.,cm 4c ' ;)'\ r G2sd Z :::tR;,..o'< S U I H A WC I { S 9.tS '? ID \:xJ b L ( S)}• 1: eci w% [Q ) 0. It p ~ (" - :&.a .--('. 9,-~ :§:< Uf rnJ ; ¢ II ; 11 v& -Cc -, c ,·, oe±,0~ , jr,,, c.. ly.dA...--. ~ ACTION rnll8: . ~c u--t '2. Q o , ;rs a s::c: ... w&·* bawt lcco ii~ coo.C•i+_-o q c la,4 REFERENCE NO. 20 -......-· IU/ uu J . ;- . .. I NUS CORPORATION TELE CON NO TE I -- CONTIIOLNO: TIMI: , L/40 OIITIIIIUT10N: IETWIIN: OP:: IIIMONI: Le.of"lar&. T-?e~d ,JPNR (v::c) (f'C9 ) 77 'f 33-Z.~ ,,.~ INUSI 1 ~--· Z . S ~ :ti. Cw t'H! i S b:,.p Yo, be+ Ho.uen HA-• in, 5-c Tb 9 c, ~a.ue o,, W ~ ,- 11 - w, l I loCA--iJQ..,,s , <AJe// '"jS« depif, -to 9roµa&½aJiw., 1?' ~ \ Sr $i '"Y:1(0 'p ~ tw:< l I s 1... ... 1, . TUT U(.11.. .::'./1U - - REFERENCE NO. 21 {)() 1 ---- RECORD OF COMMUNICATION T 0Leonc~ Ke;~ 1/.I --t. ef A!d !.; ~ . IU .... ARY o, C:OIIIIIIIUNIC:ATION : REC'D (J.ecM• of 111111 cllecU9 •~I IMll ~ ~00 S1.1rfac1 Water Rou1• wo,i.: Sne11 Rating Factor I - ASIIQfted va111• I M1o1ll~1 SI ~u. I tClrcte On11 011er HA Scare 1 (] 0DHtvld ReteaH 0 ,s If ooHrved r•••aae 11 given a va111e of ,s. oroceed 10 llne [!]. If ooae~ reteue II ;, .. ., a Yallll of o. OtOCeed 10 line [D. en Aoute CNrac1ertauca ,ac,lltv saooe ana 1n1.,.,.ntno _!1, 2 3 Terraan 1-yr. 2'-'V. Au,fall O].lll3 011tanc1 to Nearest SYl'face £11 2 l ware, Pftyl&Cal Stale 0 1 21iJ I Tow Rout• 01uacter11uca Score m Con1a1nment 0 1 2& rn Wute CJ\araCtertauca Toaic1tytPersa11ence $ l I I 12 15 if1 HuarGOUI W&ate fil 2 l " 5 • 7 0YMUfY I Total Wuta Cl'larKtertlUCI Score [i) Taroe11 SIU'face waae, UN 0 , in 3 01aWI08 ..... IIM !1 1 2 l ltmnN ..... ._,,11n ..,.,.,01a1111ee } g1 ,; • I 10 !OW ........ ,. 20 0o•-- 2, ~ ~ 31 '° I Total Taroeta Score [!J If llfte u] ii ••• muttiotY [j] I m I Ill If line [!1 ii 0, fflUlliO'J [D I [l] I GJ I [iJ l!J Oi,,,cs• line [i) Dy M,350 and mulllDIY Dy 1CO C)- (f ~5 Q_-fAC • I -- I I 1 C ,s , 6 3 1 I 3 2 ' D • 1 3 3 4- 15 1 3 l 1 C ,. ' C • C 21 l ~ ' 2 0 • 1 0 '° J...- 55 0 ..... s, •• C 02-8902-41-PA Rev. No. O I I PAO ' I ----- i ~ C J C :> .,, _5' 3 !~ I \ l rt j_ 0 '...) - $70 6·¥? Grcuna Water Route Work Sl'leet 02-8902-41-PA Rev. No. 0 .lSS1gneo viaue , C,rcte One1 I Yu•t•• 1 ' '.41.1 J :1ier HAS I se:,re . PAO CD 0t)Hrtee2 AtleHe 0 •5 , I (' I •5 I r- I..., (_ 11 oc,er-,eo re1e11e 11 \;•v•n a sc0re ot •5. i:aroceea to 11ne [!]. I II ODIINIG flllHI ti 01v1n I SCOfl Of 0, OfOCIIG 10 hf'le m [i] · Flou1e CftatlCllrllbCI L; i 0101ft to AQu,ler ot 0.1 {Dl z l./ I Concern I I Net PreclD1tataon 0 l!) 2 l 1 ' l I Permeac111r, ot u,e 0 1;f33 1 ] l J I Uftaa1uratea Zone 3 ] PP1y11CM SUie 0 1 2~ 1 l I Total Route 0\M1Ctenauc1 Scot• I,. L, 15 10 I [D Contatnment 0 1 2~ 1 3 3 3 ' Gl Waste CNrac1en111ea ,s Toa1c1ty, Pers111ence ~l I t 12 15 jJl 1 C 11 MuataOUI WUte ~ 1!1 ~. l ' 5 • 1 • 1 0 • I 0UMUly . I Total Waate O\arlCtenabCI Score u 21 '1 I u) Taroe11 ~ le Ground Water UH 0 1 Fl21l 3 t 011tanc• to .. .., ... ) (Q) ' I I 10 , C .a 4C Wetl/flOli,IIIIOfl 12 ,, ,. ~~ s.,.,.. 2, JO l2 I Total TMQ8tl Scof9 ~ ., q~ (!] If hne [i] 11 ''• fflUtltllY [i] & G] I m 6 (] ii o. ITIUIIIDIY [D I I] I Gl I [ii 57.3:SO )~. - . If""• .._,1- '-"' [i] Oiv,oe tine {!) l:ly 57.3:JO Incl mull1DIY Dy 100 s, •• C 'l/5.'1tf\ TUT 001 .•2J4 HRS Grounowa11r Route Score IS;wl Surface Water Route Score IS9w) Air Route Score (Sa) s2 + s2 • s! QW SW • ✓ s2 • s2 • s2 gw sw a V s2 • s2 • s2 / 1.73 gw sw a s r. V WORKSHEET FOR COMPUTING SM PRO s Grounawa1er Route Score lS;wl Lj5. Surface Water Route Score cs,w > C>. &' Alt Route Scof9 (Sa) s2 • s2 • s2 QW 1W & ✓ s2 • s2 • s! gw SW • V s2 • s2 • s2 / 1.13 • s,. • QW SW I WORKSHEET FOR COMPUTING SM .:)_ 02-8902-41-PA Rev. No. 0 52 C ( c D 52 I ~ :J /5 \ C>,