rn~p~~ ,-- C)A Halliburton C - - "--" - FIELD INVESTIGATION TEAM ACTIVITIES AT UNCONTROLLED HAZARDOUS SUBSTANCES FACILITIES - ZONE I NUS CORPORATION SUPERFUND DIVISION ·r U I U U l , :-:C: ,_ h *64411* 64411 .. FINAL DRAFT PRELIMINARY ASSESSMENT TUTU ESSO ST. THOMAS, U.S. VIRGIN ISLANDS PREPARED UNDER TECHNICAL DIRECTIVE DOCUMENT NO. 02-8902-43 CONTRACT NO. 68-01-7346 I, FOR THE ENVIRONMENTAL SERVICES DlVISION U.S. ENVIRONMENTAL PROTECTION AGENCY MARCH 24, 1989 NUS CORPORATION SUPERFUND DIVISION 02-8902-43-PA REV. NO. 1 SUBMITTED BY: r - {,,let,~::. /J ___, t,L \... ~·-t < DIANE TRUBE PROJECT MANAGER REVIEWED/APPROVED BY: ~.VY}~n ROAlDM.NAMAN~ FIT OFFICE MANAGER ,,.; J . ' :, \ / 02-8902-43-PA qev ;'Jo 1 POTENTIAL HAZARDOUS WASTE SITE PRELIMINARY ASSESSMENT PART I: SITE INFORMATION 1. Site Name/Alias Tutu Esso 2. ----------- Street Route 384 (Tutu District) City St. Thomas County_N_A ___________ _ 3 EPA ID No._.,;,,.N~e""-w"-S=i...:..te~-------- 4. Latitude 18° 20' 25" N State U.S.Virgin Islands Zip0~8~0~0_2 __ _ County Code_N.;;.;.A....;,.__ __ Cong. Dist. NA Longitude 64° 53' 18" W USGS Quad. Eastern St. Thomas, U.S. Virgin Islands 5. Owner Esso VI Inc. Street GPO Box 4269 City San Juan 6. Operator Danill Bayard Street P 0. Box 7441 City St. Thomas 7. Type of Ownership ~ Private D County O Federal O Municipal 8. Owner/Operator Notification on File 0 RCRA 3001 ~ None 9. Permit Information Date ---- □ Unknown Tel. No.(809) 792-2920 State Puerto Rico Zip 00936 Tel. No. 809-775-2360 State U.S Virgin Islands Zip 00801 O State D Unknown □Other __ _ 0 CERCLA 103c Date ------ Permit Permit No. Date Issued Expiration Date Comments None 10. Site Status ~ Active D Inactive O Unknown 11. Vea rs of Operation 1969 to Present I U T () U l ,: : ,.! 1 t3 02-8902-43-PA Rev. No. 1 12. Identify the types of waste units (e.g., landfill, surface impoundment, piles, stained soil, above- or below-ground tanks or containers, land treatment, etc.) on site. Initiate as many waste unit numbers as needed to identify all waste sources on site. (a) Waste Management Areas Waste Unit No. Waste Unit Type Underground Storage Tanks (b) Other Areas of Concern Facility Name for Unit Waste Oil Underground Storage Tanks Identify any miscellaneous spills, dumping, etc. on site; describe the materials and identify their locations on site. No miscellaneous spills, incidents of dumping, etc. were observed on the site during the NUS Corp. Region 2 FIT on-srte reconnaissance. It should be noted, however, that an underground gasoline tank has been suspected of leaking on s,te. 13. Information available from Contact Amy Brochu Preparer Joseph Mayo Agency U 5. EPA Tel. No. (201) 906-6802 Agency NUS Corp. Region 2 FIT Date~3/ ___ 2_4 ..... /8~9 ___ _ IU! {_j().J. ~'.:.::'. ..L c; '.)2-8902-43-PA Rev. No. 1 PART II: WASTE SOURCE INFORMATION For each of the waste units identified in Part I, complete the following six items. Waste Unit Underground Storage Tanks, Waste Oil Underground Storage Tanks 1. Identify the RCRA status and permit history, if applicable, and the age of the waste unit. There is no known RCRA permit for the underground storage tanks for waste oil The manager indicated that the tanks were installed in 1969. 2. Describe the location of the waste unit and identify clearly on the site map. The waste units are located underground below a tire rack inside the 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. 4. 5. The volume of the storage tanks is unknown. Identify the physical state(s) of the waste type(s) as disposed of in the waste unit. The physical state(s) should be categorized as follows: solid, powder or fines, sludge, slurry, liquid, or gas. The physical state of the waste oil 1n the tanks is liquid Identify specific hazardous substance(s) known or suspected to be present in the waste unit. The waste units contain waste oil from automotive repair and servicing act1v1t1es. The manager 1nd1cated that only waste oil was put in the tanks. Solvents and cleaners are not disposed of 1n the tanks. Tank sampling, conducted by Cenref Labs and Belgodere and Associates Inc, indicates the presence of toluene, ethylbenzene, and xylene in wastes stored there. 6. Describe the containment of the waste unit as it relates to contaminant migration via groundwater, surface water, and air. The waste is contained 1n underground storage tanks There 1s no information that indicates that the tanks are leaking; therefore, there is little potential for contaminant migration to air, groundwater, or surface water. The manager indicated that the tanks are periodically emptied by ESSO Corp and the waste is shipped off St. Thomas for disposal. Ref. Nos. 1 18 19 20 21 22 11 .. n OUJ. PART Ill: HAZARD ASSESSMENT GROUNDWATER ROUTE 02-8902-43-PA r{ev No. 1 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. There is a potential for contaminants to be released from the waste oil storage tanks to groundwater. The manager of the facility indicated that only waste oil was stored in the tanks. Cleaners and solvents are not put into the tanks. Small quantities of contaminants may have been introduced into the oil in the normal course of ,ts use as motor 011. Tank s.impling ' indicates the presence of toluene, ethylbenzene, and xylene ,n wastes stored on site in the tanks; however, these results are questionable due to chain-of-custody problems. A soil gas vapor study also confirmed chlorinated hydrocarbons on site. Ref. Nos. 1, 21, 22 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 ma1or groups: the Water Island Formation, the Virgin Island Group, and an unnamed group of diont1c plutons The Water Island Formation, which is late lower Cretaceous in age, consists of keratophyre and spillates. The Virgin Island Group, which is probably early Cretaceous or Alb,an ,n age, consists of andesitic-pyroclastic rocks and sedimentary formations. The Virgin Island Group is divided into four formations: the LouisenhoJ Formation, which consists of aug1te-andesite brecc1a, tuff, and conglomerate; the Outer Brass Limestone, vv.hich consists of partially silicified- tuffaceous-radiolarian-l1mestone; the Tutu Formation, which consists of tuffaceous wacke, including megabreccia near the base and limestone near the top; and the Hans Lollik Formation, which may be Eocene ,n age and consists of aug1te-andesite breccia and tuff. The final group Is made up of one or more diontic plutons. These unnamed dikes and plugs of quartz-andesine-hornblende porphyry are Upper Cretaceous and Lower Tertiary In age. Alluvian deposits are quarternary in age The Water Island Formation, which consists of 95 percent volcanic flow breccias. was probably extruded on a relatively level ocean floor T'le absence of terrrgenous sediments from this formation indicates that there were no emergent islands present ,n the area at the t1 me 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, ~he subsidence was not rap,d 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 andes1tic 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 This limestone formation is an offshore deposit formed by radiolanan and foraminiferal remains including a minor amount of tuff. Thicknesses are known to be at least 600 feet 02-8902-43-PA qev No. 1 Overlying the Outer Brass Formation 1s 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 Lou1senhoJ andes1tes. Exposed thicknesses are known to be as much as 6000 feet. Within this formation are a megabrecc1a l1thofacies with an average thickness of 30 feet and a limestone member with a thickness up to 300 feet. The Hans Lollik Formation, which consists of at least 10,000 feet of aug1te-andesite pyroclastic rocks, crops out on Little Hans Lollik Island. Diorit1c 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 pegmatites appear. • Folding occurred after the deposition of the Virgin Island Group. Rocks were tilted to form a northward-dipping homocline, which is cut by sets of faults trending N 45°W, N 55°E, and north. Well-defined joint sets parallel each of the maier 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. \/lost recent Pleistocene to Holocene alluvial deposits occurred or1mar1ly 1n coastal emoayments. 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 slit, clay, and thin, d1scont1nuous beds of sand and gravel Maximum thickness of these Is 50 feet. Groundwater movement Is limited to openings and 10Ints along fault zones. Regional geologic information is 1nsuffic1ent to determine whether these fractures and fault zones are present in all of the above formations; however, for this report It is assumed that the fractures and fault zones are present in all of the 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 1n 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 1n the Turpentine Run Basin Aquifer ,s south-southeast which Is generally along the direction of flow of Turpentine Run Depth to groundwater 1n 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. 8, 10, 14 3. Is a designated sole source aquifer within 3 miles of the site? No sole source aquifer, as designated in the Federal Register, is located within 3 miles of the site. Ref. No. 7 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? The lowest point of the waste oil storage tank is unknown. It is assumed that the bottom of the tank is at least 6 feet below the ground surface. Depth to groundwater in Four Winds Shopping Plaza Well Nos. 1 and 2 is 13 feet and 9 feet, respectively. The Four Winds Shopping Plaza wells are located approximately 400 feet from the Tutu Esso facility. The depth from the lowest point of waste storage (6 feet) to the highest seasonal level of the saturated zone (9 feet) is 3 feet Ref. Nos 1, 2, 8 02-8902-43-PA =\ev No. i 5. What is the permeability value of the least permeable continuous intervening stratum between the ground surface and the aquifer of concern? There are no continuous intervening strata between the ground surface and the bedrock aquifer. Soils are generally thin in the area around the site. The water-bearing formations In the Turpentine Run Basin Aquifer are composed primarily of fractured and jointed volcanic rocks. The range of hydraulic conductivities associated with these formations Is 10j to 10' cm/sec. Ref. Nos. 9, 10, 14 ' 6. What is the net precipitation for the area? Net precipitation is usually calculated by subtracting mean annual lake evaporation (a surrogate measure for evapotranspiration) from normal annual total prec1p1tation. Mean annual lake evaporation information was not available for St. Thomas; however, evapotranspiratron data were available. These data indicate that 95.8 percent of the incident precrp1tation on St. Thomas is lost through evapotranspiration. The normal annual total precipitation for St. Thomas 1s 43.74 inches, but because of orographic effects on the Island, normal annual total precipitation can range from 35 inches to 50 inches over short distances. :n the Turpentine Run Basin, normal annual precIpItatIon Is 40 inches. Calculations for net precIp1tatIon are provided below: 40 inches prec1pitat1on x 95.8 percent lost to evapotranspirat1on = 38.32 inches lost to evapotranspI ration 40 inches precipitation - 38.32 inches lost to evapotranspirat1on = 1 68 inches net prec1p1tation. Ref. Nos. 3, 5, 11, 12 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 w1th1n 2 miles of the site. Thirty-six of these wells are within 1 mile of the site. Sixteen of these wells have been ordered closed because of contamination with volatile organic compounds. Ref. Nos. 6, 8 8. What is the distance to and depth of the nearest well that is currently used for drinking or irrigation purposes? Distance ..;..1..;..10-=-0.;:.....;..fe-=-e-=-t;;__ _____ _ Depth Unknown The nearest well that Is used for domestic purposes is the Francois Laplace well. It is uncertain whether this well is used for drinking. A number of wells in the vicinity of the Francois well have been closed because of contamination with volatile organic compounds. Ref. Nos. 6, 8 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 1s trucked to private houses and pumped ,nto cisterns to augment 1 \J 1 1,u l collected from roofs. Groundwater 1s also bottled and sold in supermarkets ' 02-8902-43-PA Rev No. 1 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. 8, 12, 13, 16, 17 SURFACE WATER ROUTE 10. Describe the likelihood of a release of contaminant(s) to surface water as follows: observed. alleged, potential, or none. Identify the contaminant(s) detected or suspected, and provide a rationale for attributing the contaminants to the facility. No potential exists for wastes to the released to surface water. Waste o,I is stored in an underground storage tank. The tank is located under the garage, and no incidents of leaks or so1lls have been reported. Ref No. 1 11. Identify and locate the nearest downslope surface water. If possible, include a description of possible surface drainage patterns from the site. Not applicable. Containment of the waste unit precludes any release to surface water Ref. No. 1 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.) Not applicable Containment of the waste unit precludes any release to surface water Ref No. 1 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.) Not applicable. Containment of the waste unit precludes any release to surface water Ref. No. 1 14. What is the 1-year 24-hour rainfall? Not applicable Containment of the waste unit precludes any release to surface water. Ref No. 1 15. What is the distance to the nearest downslope surface water? Measure the distance along a course that runoff can be expected to follow. Not applicable Containment of the waste unit precludes any release to surface water Ref. No 1 !UT •:)() .. 02-8902-43-PA Rev. No 1 16. Identify uses of surface waters within 3 miles downstream of the site (i.e., drinking, irrigation, recreation, commercial, industrial, not used). Not applicable. Containment of the waste unit precludes any release to surface water. Ref. No. 1 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. Not applicable. Containment of the waste unit precludes any release to surface water. : Ref. No. 1 18. Describe any critical habitats of federally listed endangered species within 2 miles of the site along the migration path. Not applicable. Containment of the waste unit precludes any release to surface water Ref. No. 1 19. What is the distance to the nearest sens1t1ve environment along or contiguous to the migration path (if any exist within 2 miles)? Not applicable. Containment of the waste unit precludes any release to surface water. Ref. No. 1 20. Identify the population served or acres of food crops irrigated by surface water intakes within 3 miles downstream of the site and the distance to the intake(s). Not applicable. Containment of the waste unit precludes any release to surface water. Ref No. 1 21. What is the state water qua I ity classification of the water body of concern? Not applicable Containment of the waste unit precludes any release to surface water Ref. No. 1 22. Describe any apparent biota contamination that is attributable to the site. Not applicable. Containment of the waste unit precludes any release to surface water Ref. No. 1 AIR ROUTE 23. Describe the likelihood of a release of contaminant(s) to the air as follows: observed, alleged, potential, none. Identify the contaminant(s) detected or suspected, and provide a rationale for attributing the contaminant(s) to the facility. There is a potential for contaminants to be released to the air. Waste oil is contained in underground storage tanks. There are no reports of any spills, and the wastes are not known to contain volatile compounds, however, volatile compounds have been detected in soil gas vapor screening surveys Ref Nos 1, 22 I > I I '·' I ' .. ·,,._} j 24. What is the population within a 4-mile radius of the site? 02-8902-43-PA ~ev No 1 Based on the 1980 census, the population within 4 miles of the site is approximately 36,000. Ref. No. 15 FIRE ANO EXPLOSION ~ 25. Describe the potential for a fire or explosion to occur with respect to the haz:ardous 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. Wastes on site are stored in an underground storage tank; however, due to their volatile nature, there is a potential for fire or explosion conditions present on the site. Ref. Nos.1, 22 26. What is the population within a 2-mile radius of the hazardous substance(s) at the facility? 3ased on the 1980 census, the population within 2 miles of the site 1s approximately 19,000 Ref. No. 15 DIRECT CONTACT/ON-SITE EXPOSURE 27. Describe the potential for direct contact with hazardous substance(s) stored in any of the - waste units on site or deposited in on-site soils. Identify the hazardous substance(s) and the accessibility of the waste unit. There is no potential for direct contact with hazardous substances. The waste 1s stored in an underground storage tank under a garage. The area of the storage tank 1s accessible only to workers. ~ef 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. 15 ru 1 ,_),); ,:... ,:· c .. PART IV: SITE SUMMARY AND RECOMMENDATIONS 02-8902-43-PA .~ev. No. 1 Tutu Esso is an automotive service station located in the Tutu area of St. Thomas, U.S. Virgin Islands. The primary activities at the site are gasoline sales and automotive repair and maintenance. The area within approximately 1 mile of the site is densely populated and contains some commercial properties. The Four Winds Plaza shopping center is located just west of the site There are large housing developments northwest, north, and east of the site. Beyond 1 mite, there are s<.>attered \ . smaller villages and towns. The densely populated and highly commercial town of Charlotte Amalie is located approximately 2.5 miles west of the site. On February 15, 1989, NUS Corp. Region 2 FIT conducted an on-site reconnaissance of the Tutu Esso Site. The station manager indicated that all waste oil from the station operations was stored in two underground tanks located under a tire rack 1n the garage. The tanks have been in use since about 1969 and contain only automotive waste oil which 1s periodically removed by Esso Corp and disposed of off St. Thomas. The volume of the tank 1s unknown, and there are no known permits for the tanks. The waste oil at the Tutu Esso station is contained in underground tanks. There is no evidence that the tanks are unsound or that there were any spills or releas-es to the en· , ronment The tanks reportedly hold only waste oil which is disposed of by Esso Corporation. Based on the waste containment, there is no potential for contamination of surface water or air, and there 1s no potential for fire and explosion or exposure by direct contact. There is a small potential for groundwater contamination if the tanks are unsound; however, there is no evidence of this On the bam of the above information, a recommendation of MEDIUM PRIORITY is provided There were no known enforcement actions taken aga,nst Tutu Essa in the past. However, the owners of the Tutu Esso Site 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. One of the wells was a major source of commercially provided potable water for the eastern end of the island. Additional sampling of wastes on site indicated the presence of toluene, ethylbenzene, and xylene; however, these results are suspect due to problems with regard to chain-of-custody integrity. Soil gas vapor sampling indicates the presence of chlorinated hydrocarbons. EPA removal action activities ,n the Tutu area included sampling of wells and cisterns, removal of contaminated water from cisterns, cleaning of cisterns, and supplying of clean water on a regular basis to affected residents. Additional sampling procedures are recommended to ascertain the extent, if any, of contamination associated with this site. I:.! i ATTACHMENT A MAPS ANO PHOTOS * No photos were taken as the waste unit was below ground. ; ii; TUTU ESSO ST. THOMAS, U.S. VIRGIN ISLANDS CONTENTS Figure 1: Site Location Map 02-8902-43-PA Rev No. 0 ·r LJ i (}i.J J ,::. •- .,: .. -., und !'!\ •••• /' ✓ /11 SITE LOCATION MAP TUTU ESSO SERVICE STATION ST. THOMAS, U.S. VIRGIN ISLANDS SCALE: 1"• 2000" 02-8902-43-PA Rev. No. O FIGURE 1 ATTACHMENT B REFERENCES REFERENCES 02-8902-43-PA Rev. No. 1 1. Field Notebook No. 0398, U.S. Virgin Islands Drum Reconnaissance, TDD No. 02-8902-29, NUS Corp. Region 2 FIT, Edison, New Jersey, February 14 to 17, 1989. 2. U.S. Department of the Interior, Geological Survey Topographic Maps, 7.5 minute series, "Central St. Thomas, Virgin Islands and Eastern St. Thomas, Virgin Islands Quadrangle" 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, Western/SPER Division, December 1989. 7 Telecon Note: Conversation between Nancy Schlater, EPA, and Diane Trube, NUS Corp., Re: Sole source aquifer in VI. March 3, 1989. 8. Graves, R.P. and R. Gonzalez. Potentiometric surface of the Turpentine Run Basin Aquifer 1n the Tutu Area, Eastern St. Thomas, U.S. Virgin Islands, September 11, 1987. US Geological Survey Water Resource Investigations Report 88-4131, 1988. 9 Uncontrolled hazardous waste site ranking system, A user's manual, 40 CFR, Part 300, Appendix A, 1986. 10 Donnelly, T W, Geology of St. Thomas and St. John, U 5. Virgin Islands, In Caribbean Geological lnvest1gat1ons, Geological Society of America, Memoir 98. ed H. H. Hess, 1966. 11. Climatological Data Annual Summary, Puerto Rico and Virgin Islands. National Oceanic and Atmospheric Adm1nistrat1on, 1987 12. Torres-Sierra, H. and R. Dacosta, Estimated Water Use in St. Thomas, US Virgin Islands, July 1983 to June 1984. Caribbean Research Institute, Technical Report No. 21. 13. Memo to Stephen D Luhig, EPA, from Carlos O'Neill, EPA. Authorization of CERCLA Removal Action Monies for the Tutu Well Site. January 6, 1988. 14. 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. 15. Water Management Plan for the Public Water System, Prepared for the Government of the Virgin Islands by CH2M HILL. July 1983. l i...l. i i. __ . ,_.) J. REFERENCES (cont'd) 02-8902-43-PA R.ev. No. 1 16. 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. 17. Telecon Note: Conversation between 0. Goetz of Polycaribe and D. Trube, NUS Corp., on \. 3/14/89 at 1430 hours. Re: Wells and water use on St. Thomas. 18. Tel econ 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. 19. Telecon Note: Conversation between T. Gutshall, Tutu Esso Manager, and J. Mayo, NUS Corp., on 3/15/89 1510 hours. RE: Background information for Tutu Esso. 20. Record of Communication, telephone conversation between Leonard Re1d,DPNR, and A. Brochu, U.S EPA Region 2, Jan. 30, 1989, 1400 hours. 21 Tutu Well field Area Sample Analysis Data Summary, Tutu Esso Service Station, St Thomas, U.S. Virgin Islands. Prepared for US. EPA Region 2 by Cenref Labs, COM, Federal Programs Corporation, March 6, 1989. 22. Esso Tutu Service Station Soil Gas Vapor Screening Survey Report, St. Thomas, U S. Virgin Islands. Prepared for Esso Standard Oil S.A. LTD, by Belgodere and Associates Inc., August 1988 REFERENCE NO. l I NUS CORPORATION II 0398 ' . 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REFERENCE NO. 2 und ~2 \ .• SITE LOCATION MAP TUTU ESSO SERVICE STATION ST. THOMAS, U.S. VIRGIN ISLANDS SCALE: 1·• 2000' lee ~te. f \' I • ---• :-.. ~ \.~110 . ~::::: 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 813-U UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON:1980 ,: ,. i-'> ---- - ------------ 02-8902-43-PA Rell. No. 0 O11erlying 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 deri11ed 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 a11erage thickness of 30 feet and a limestone member with a thickness up to 300 feet. The Hans Lollik Formation, which consists of at least 10,000 feet of augite-andesite pyroclastic rocks, crops out on Little Hans Lollik Island. Dioritic plutons are located in Pillsbury Sound between St. Thomas and St. John; 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 pegmatites appear. Folding occurred after the deposition of the Virgin Island Group. Rocks were tilted to form a northward-dipping homocline, which is cut by sets of faults trending N 45°W, N 55°E, and north. Well-defined joint sets parallel each of the major fault trends. Dips range from 15° to 90Q with the a11erage being 40Q. 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 Lo11ango 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 abo11e formations; however, for this report it is assumed that the fractures and fault zones are present in all of the formati~s. The-valleys on the island are the result of weak zones caused by faulting and jointing anl are primary recharge areas for groundwater. Alluvial deposits have a high porosity but low permeability, making this aquifer unfa11orable 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 abo11e mean sea level. Ref. Nos. 10, 14 3. Is a designated sole source aquifer within 3 miles of the site? No sole source aquifer, as designated in the Federal Register, is located within 3 miles of the site. Ref. No. 7 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? The lowest point of the waste oil storage tank is unknown. It is assumed that the bottom of the tank is at least 6 feet below the ground surface. Depth to groundwater in Four Winds Shopping Plaza Well Nos. 1 and 2 is 13 feet and 9 feet, respectively. The Four Winds Shopping Plaza wells are located approximately 400 feet from the Tutu Esso facility. The depth from the lowest point of waste storage (6 feet) to the highest seasonal level of the saturated zone (9 feet) is 3 feet. Ref. Nos. 1, 2, 8 '!, .. lJ20 SUM.MARY APPRAISALS OF THE :-JATION'S GROUND-WATER RESOURCES Wm eout to R1oG...- 0te AreJ.l .-)~ •ti d Ouq,ut IUO .::u nu 7J 0 .N !ti .N I 6 15 Puerto Rtco South Province Patdlu Tallaboa to to Ponre Guanica hmJfyr Perce-nt hm'lyr Percen, 110 .-,oti 60 ~.5 j;IO J~.5 175 14.5 1IO ~.~ ~JO oJ.l 60 ~.5 I~ :!3.5 100 42.S LO l.5 15 6.4 170 !1.0 60 2U I~ 21 143 J7 d 2 L&iu WHt(oat Vali.y proYlnn hm'lyr Perc.nt hm•1yr Percent LUO ;i ~ ttiO !'Ju H I.! - 71 U J:l ~ .. u !LO ,; J .!70 Ll.d II so ,w 74 l 6.3 4ti •o J.l to d tu 1 All l(ruund waLt.-r withdrawn wu •-ufflt'd to IA! for eunwmpuun sinC"t' 1t ts nut ava1lavk!' fur ulh~r u..s. 1000--....... ----,-----.----,---..--....... ----,---- 100 IC C 100 "' ► IC "' ._ 400 .. IC "' ... I zoo 0 ... u ... % 0 u • ::, u ! .,; 400 ~ C I IC Q % !:: • Public SupplJ (Pulfto Rico Aqueduct and Stwtr Authority) TOTAL WITHOll.laU. : : J 1990 19'5 2000 A 2,,---"'T""---,,--~---,-----.---r---..----- 20 I " ... >- 10 C : , -... LltNT INOUSTIIY __ ,,, \ -- -- --- ... OOIIUTIC AND COltlltlUCIAL ... : o,._ _ ___. __ __._ __ ....._ __ ....._ __ _._ __ _._ __ _.__~ ► ~~-----..-------------..--- ► :;: 41 z u 40 • a JS • ~30 ... ~2' • = 20 Q ~ ,, i IO , ?990 TOTAL WITN!Mt-ALS (hclffnHlf• ..... iN i...,, ..... ........... ... .,, 19?1 lt«I IH!J YUIIS 8 1910 ltff 2000 f'1,.1 Ht 17.-Wat.er-use estimates. A, Fur Pu~rto Rico; public-supply data provided hy tilt' Puerto Rico A,1ueduct and Sewer Authority (moriiti~I from Morris. rn76). B. For the U.S. Virgin lillan,L~. CARIBBEAN REGION l'21 prov111tt) afld ita ojJMON "'4IMU (Vieqlu,, CIIUbra. afld MO'llll lslaflds) afld for tJae U.S. Virgin /slanda. 1975 PUt-rLu KK."11 - CunllnUt"II l'.S \. 1rl{111 1~1an,1, Pue.•rt.u H.K .. •~ urfshuno •~lar\(f, ~ul(.;.uu.L In- Pu.-rt.u k,ar,, 1'1antlLuLJ&I V""l'I"> Cui<-t,n, M,,nc1 :--1. lrtll). SI l'homa., . :,,.l Jnhr1 µn1Yln<'l" t:!"'''llfk,- hmJ1,r Pt-r<'t-nl hm'r"·r Pt-rt"t'OI hm.1'\r Pt'rrt'Ol hmJ/~r Pt'n·t'nl hm'1)r Pt'n·""nl 11m••\1 Pt>nt·nt t,m• \I Pt'n·,·11l hmJ•,, Pt'n1·111 l'lffl'\r t-'t-111·Pt lnpu1-Contin~ J!KJ 43 J I0.1f;'O IUO 15.K~ IUO l.!U IUU i;!:, IW ";, 100 ~o IUU ~--) I'-"' 111111 :})(I 56; Outpul Continued :liM 31.U 6.5ll 5S S 10.1;,, ML 110 ijJ.j l4.II 580 &I 4 4.34l JS S 5.U4ti Jl.S :1.U JU 3.J lt,0 l.h :13 'l..i 12 I 3 16 :1511 l.3 h .04 IU 4 ,, .. L 188 ll hh PROBLEMS AFFECTING USE OF WATER. RESOURCES MANACI.MI.NT-PUI.I.TO RICO By adoption of Law No. 23 of January 1973, the Puer- to Rico Department of Natural Resources (DNR) was charged with the responsibility for implementation of the operational phase of the public environmental policy of Puerto Rico. Law No. 23 also provides for centraliza- tion of operational functions and implementation of regulations that had previously been dispersed throughout many governmental agencies. In addition, the new Water Law, No. 136 of June 3, 1976, assigned to the Secretary of DNR the responsibility to plan and regulate the use of and to improve, conserve, and develop the waters of Puerto Rico. In acknowledgment of the need for a centralized information center, the new water law also stipulates that the Secretary be assisted by a staff that has representatives from the Planning Board, the Puerto &ilo, Industrial Development Com· pany (Pruoc:: l:ronmenbd Quality Boord (EQB), the Puerto ~t and Sewer Authority (PRASA), the ' _ Water Resources Authority (PRWRA), the . t of Agriculture (DOA), the Department of Heaftl (DOH), the Department of Trans- portation and Public Works, and the University of Puer• 1 to Rico. Although numerous government agencies (State and Federal) and institutions are involved in the use, plan-I ning, management, and investigation of the water resources, the DNR. EQB. U.S. Environmental Protec- : tion Agency (EPA). PRWRA, PRASA, Puerto Rico! Sugar Corporation, and heavy water-use industries j S5 • JIJ ;, !'ti I" ., .. -. SJ~ SI ';I'(.!, lS I) u " J.h :.!ti IL ~.-. LL! 5 ;, "t,.:, L! 1 ,} ' I I j established by PRIDCO exert the greatest influence over the future of this resource. The responsibilities these agencies and public corporations have with respect to water resources are listed as follows: DNR. The functions of this Puerto Rican agency were established by Laws No. 23 and No. 136, previously stated. EQB. This is the Puerto Rico policy-making and regulatory agency responsible for the enhancement and protection of water quality; it is invested with quasijudicial powers to enforce its regulations. For purposes of the Federal Water Pollution Control program (Public Law 92-500) the Board is designated the State water-pollution control agen· cy. EPA. This is the Federal agency charged with ad- ministration of Public Law 92-500 aimed at restor- ing and maintaining the chemical, physical, and biological integrity of the Nation's waters. Among the programs the agency administers are establish- ment of effluent limitations, administration of the National Pollutant Discharge Elimination System. and management and planning for public water- supply treatment-works construction. PRWRA. The authority produces and distributes elec- trical energy and administers and operates the irri- gation systems supported by releases from reser· voirs and the hydroelectric power-generation net· work on the south coast and in northwestern Puerto Rico. PRASA. The authority is charged with developmenl. construction, operation, and maintenance uf water and sewer systems and providing adequate water { ,rq/0 fr ~fl" U22 SUMMARY APPRAISALS OF THE NATION'S GROL'ND-WATER RESUL'RCES and sewer services and any other related services and facilities. Puerto Rico Su,ar 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, especiaJ!y 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. MANAGIM!.NT-U.S. VU.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 Work• Department. Under Title 30, Section 51, of the Virgin lsJands Code, the Commissioner of Public Woru if dilliarnated to mpervise and control the co=l::ns.....-r, maintenance, operation, and adm · · of the potable-water systems. The po . wyst.em wu defined as "all fresh water storel"'_dt-' eeUected by the government, whether in cat.dnnenta, dams, wells, or reservoirs, for public distnbution." Virgin Ialancla Water and Power Authority (WAPA). This authority was established in 1964 under Virgin Islands Code, Section 103, Title 30, for production and distribution of electrical energy and provision of potable water from its water-distillation systems. In the enabling legislation is a provision, 104e, for the transfer of the water-supply functions of the Public Works Department to W AP A at a date to ~ deter- mined by law. The transfer of functions has not been acted upon by the legislature. and WAPA sells the distilled water to the Public Works Department. U.S. Virgin IsJands 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. WA TEil lllGHTS 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- CARIBBEA:-S R!'.:GIO\ ly" (Art. 8). Similarly, as to "artesian wells. tunnels. or I galleries," (major ground-water developments as oppos- I ed to "ordinary wells," which are defined (Art. 20) as I those for which no other motive power than man is I employed for raising the waters), the right of the person · discovering and bringing the water to the surface is recognized "in perpetuity ... as long as such development does not interfere with preexisting rights to public or private waters (Art. 23). These rights (surface- or ground-water appropriation) were also recognized for all individuals who had enjoyed the use of public waters for a period of 20 years (prior tu 1886) even though no proper authorization had been obtained. The order of preference in utilization stipulated by the previous law (Art. 160 of the Spanish Water Law) ex- pressed the needs of the past century. First priority was given to water supply of towns, followed by water sup- ! ply of railroads, irrigation, navigational canals, mills and I other factories, ferry boats and floating bridges, and fishponds. The economic importance of water-using in- I dustries was not foreseen, and a low preference as to water concessions was stipulated. Duration of the con- ' cessions was limited to 99 years of town supplies (Art. 170) and all other uses but was "in perpetuity" for irriga- tion (Art. 188) and fishponds and also for industry, as long as effluents were not harmful to health or vegeta- tion (Art. 220). As of 1909 there were approximately 250 concessions in Puerto Rico .that were originally granted by the Spanish Crown (Report of the Governor of Puerto Rico, 1909). The majority of these grants were given to lan- downers in the South Coast province for the irrigation of approximately 21,000 ha. The surface-water conces- sions included rights to flood-waters, spring and winter waters, or a definite daily flow. An updated inventory of vested owners, diversion amounts, and land under irrigation is necessary to determine the degree to which these rights could affect a water-use and distribution plan. In the Virgin Islands, all waters are in public owner- ship and are subject to-appropriation for beneficial use as stipulated in··· . Tltle 12, of the Virgin Islands Code. Under this Ml&ed rights are recognized prior to other · . . Vested rights may be nullified by the t1l the Virgin Islands (Com- missioner of C . ·and Cultural Affairs) when it is determined that the exercise of such rights would im- peril health or welfare by endangering, impairing, or destroying available sources of water. Nevertheless, the occurrence of such circumstances is very remote, as most private installations are for domestic use and withdraw less than 2 m3/d. An exception could be those individuals and companies that sell water obtained from I wells. Under Section 153 of Title 12, appropriation per- mits are not required if pumpage is less than l mJ:d for benefinal use. Cndt•r Chapter 3. Title 12. of the Virgin Islands Code. trees and other vegetation adjacent to watercourses are protected by law. This regulation protects the es the tic value~ Pt° stream channels but results in a significant loss of ground water to evapotranspiration by the deep· rooted \·egetation. A modification of this law would be necessary in order to exclude from such provision those watt!reuurses that are used for public supplies or are in hydraulic connection with aquifers tapped for supply. PRACTICES DETRIMENTAL TO GROUND-WATER QUALITY LAND USE Land use may affect recharge tu an aquifer and the quality of its water. Although there has been no exten- sive evaluation of the effects of various land uses on aquifers in the Caribbean Region, data from scattered sources indicate that this could be a major problem in the near future. Urbanization has taken over large portions of the recharge areas of aquifers in metropolitan San Juan, Ponce, and Mayaguez in Puerto Rico and throughout the Virgin Islands of St. Croix and St. Thomas. Unless ar- tificial recharge is provided or withdrawals are reduced to compensate for the loss of recharge, the seawater- freshwater interface will move inland in most of these areas. Aquifers in the Caribbean Region are threatened by pollution from domestic, municipal, and industrial sources. The most widespread source of pollution is pro- bably sewage from cesspools, leaking sewage lines, and overloaded or improperly operating sewage plants. In Puerto Rico about 37 percent of the population is served by sewers, and in the U.S. Virgin Islands approximately 77 percent is served. In en the only areas served by sewers are those within ns. ~ wastes have been discharged to aquifers through sinkholes and disposal wells or have entered aquifers from accidental spillage (D.G. Jordan, written commun .. 1969; R.C. Vorhis, written commun., 1972). Of the 15 disposal wells known to exist in 1972. only Z could be designated as deep injection wells. and the others could better be designated waste-disposal holes. All tht> known disposal holes were between 24 and 213 m deep. Wastes disposed in sinkholes and disposal holes in- clude sewage, oil. neutralized acid, organic compounds, dyes, pickling liquors, pineapple-cannery wastes. and brewery wastes. Jordan (written commun., 1969) estimated there were at least 40 such disposal holes in Puerto Rieu in 1969. It has also been observed that unproductive wells are either abandoned without plugging or are not thor- - - U24 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES oughly sealed. As a result many are used as receptacles for wastes. The effec:ta on water quality and the extent of damage this hu cauaed in the Caribbean Region have not been assessed. In the Lajas Valley, Vazquez and Ortiz-Velez (1967) observed that a downward hydraulic gradient existed at various abandoned irrigation wells. These wells probably are serving as hydraulic connec- tors between perched water tables and the underlying regional water table. The effect of these "hydraulic con- nectors" on water quality is unknown. Disposal of refuse in landfills poses another threat to aquifers in Puerto Rico. Most landfills were estalished after 1972 (fig. 18), and although migration of leachates may be slow at some sites, with time these will inevi- tably affect to some degree the local ground-water sources. In the U.S. Virgin Islands, landfills have been established near the coast on St. Croix and St. Thomas, and cont.amination of freshwater sources ia not a threat. The landfill on St John, however, ia located in the in- JI' 18"30' 18'00' EXP\.ANATION 6 MI.Wlicipal IOlld ..... ----- CULEBAA VIEOUES terior Guinea Gut Basin, where potential for ground- water development exists. IRJlJGATION PRACTICES Irrigation of crops occurs primarily in southern Puer- to Rico. The basic means of distributing water within cultivated lands is by furrows, although overhead sprinklers are used at some farms in the early months of sugarcane cultivation. Giusti (1971) estimated that ap- proximately 30 percent of the applied water in the South Coast province (Coamo area) was recharged to the aquifer. BeMett (1976) indicated that the ground-water reservoir in the South Coast province is "vertically oriented," in that local recharge and diacharge tend to be high in any given locality relative to lateral ground- water flow. In areas where irrigation water is derived from wells, recycling of the irrigation water will result in an increue in the diuolved-aolida concentration of the ground water. PUERTO RICO 17"45' FtGuu 18.- Solid-waN dilpoal litel in the Carilbwl Rapin. CARIBBEAN REGION U25 During the mid-1960's, drought nearly eliminated surface-water supplies that were used in the South Coast province area for irrigation, and ground-water production was increased to make up the deficit. By 1968, after 3 years of increased pumpage, the ground water in storage was drastically depleted. An estimated 1,000 hm3 of the 1,500 hm3 in available storage had been withdrawn. The depletion in storage was accompanied by a decline in ground-water levels to below seal level over large areas (pl. IA). 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 years the Mfort 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 USI. OF SUUACE· AND GaGUND-WATll. IOIJ&CIS The greatest ~for conjunctive use of surface- and ground-water ' in the Caribbean Region may be on the island of · Rico, where both sources are relatively plentiful.-. _ · a may be achieved by res- ervoir management, 111p1enting natural recharge, ground-water salvage, ground-water mining, and use of seawater. RESEJlVOIR 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 wwater 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- ~ion 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 f18C&l year, partly by north-coast hydroelectric plants. · AUGMENTING NATURAL RECHARGE Although aquifen receive recharge by natural means, it may be practical in some areas to increase this amount artificially. Within urbanized centers the loss of rainfall infl1tration 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 aquifen (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 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!i(stem in the North Coast province of Puerto Rico c. Ground-water flow within the North Coast province west of Arecibo 2. Areal studies made concerning the following: a. Ground-water flow system in Lajas Valley b. Water-balance for unstudied aquifers in the East Coast, West Coast, and Interior pro- vinces c. Water-table monitoring throughout Puerto Rico, the offshore islands, and U .S Virgin Islands d. Qualitative and quantitive asaeument of saline- water reserves of St. Croix and in the coutal 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 evapotranapiration and its relationship to soils and vegetation under the climatic conditions in the Carib- bean Region. At present it is unknown if under long- term conditions thick vegetation and plant debris aid ground-water rechalp by reducing runoff, enhancing infiltration, and reduciDc direct evaporation of rainfall or whether ~¥- the soil tlu'OUgh transpiration. litea, surface features, and historical · that water was much more plentiful at now · · · in Puerto Rico's offshore islanda and in the U :v,.p lalanda. SUMMARY The Caribbean Region consists of the Commonwealth of Puerto Rico (8,99o km2) and the O .S. Virgill Islands (3SO..km1). It i1 arnong 6he n1ost densely populated areas in tlle Woi'td, wlU1 an ovetlll populaiton di approximate- ly 3,200,000 peo__£le. Within the past 25 years the islands liive 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 hm3/yr in the U.S. Virgin l§lapds These amounts would theoretically satisfy the total water needs of both areas, which are about 919 hm3/yr and 20 hm3/yr, respectively (1975). In reality, most of this flow is contributed by intensive rainstorms and is lost to the ocean as runoff. Potential for retaining a large part of this flow exists on the island of Puerto Rico, but present- ly the total usable reservoir storage capacity is only about 230 run•. In the U.S. Virgin Islands, small dams and ponds have a storage capacity of about 2 hm•. Aquifers constitute a valuable water resource in the Caribbean Region. In Puerto Rico, ground-water withdrawals provide about 38 percent of the total water requirements, whereas in the U.S. Virgin Islands, they provide 10 -percent. Excluding desalinated-water sup- plies in the U.S. Virgin Islands, (m)Ul!d water rovides t 72 rcent of the freshwa r the 50 hm1/yr -wa r 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 hrn1/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'~ 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 ·II I'·' l CARIBBEAN REGION L'31 will support only minor future development if effective management practices are not introduced. In the U.S. Vir ·n Islands, the most extensive uifer is ra n I roe . t contn utes 1ttle water to wells, but weighed against the costs of desalinated water, its exploitation is feasible for sup- plementing domestic water needs. The most productive aquifer consists of marl and alluvium deposits in central St. Croix. Although this aquifer contributes less than 6.3 Lis to individual wells, it yields about 0.86 hm3/yr to public water-supply wells and about 0.54 hm3/yr to private wells. Future development of this aquifer could probably produce an additional 1.0 hm3/yr. Ground-water resources will continue to play an im- portant role in the future development of both Puerto Rico and the U.S. Virgin Islands. In order to meet future needs, it is necessary that hydrologic principles be effectively applied in managing the total water resource. Optimization of the water resources can be ac- complished through conjunctive use of surface and ground waters and through conservation practices. Op- timal use may involve artificial recharge, ground-water salvage, saline- or fresh-ground-water mining, use of seawater, wast.e-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. s 1 ~,UftaENCIS Acevedo, G., Lup,Lapa. " :• udO.U.~ela,J., 1959, Occurrence of soil tumors 111a 6--- J...aaoon. Laju Valley, Puerto Rico: U~ Rico Apicultural Station Jour• nal, v. '3, no. 2, p. lOI-JJ!. Adolphaon. D. G., Seijo, M. A., and Robi11110n, T. M., 1977, Water l'elOW'CeS of Maunabo Valley, Puerto Rico: U.S. Geological Survey Water-Rellourcel Investigations 76-115, 44 p. Anders, R. B., 1968, Reconnaiaance of the water reaources of the Central ~ibo Valley, Caho Rojo, Puerto Rico: U.S. Geolotiical Survey open-file report. 18 p. Anderaon, 1976, Ground water in the San Juan metropolitan area, Puerto Rico: U.S. Geological Survey Water-Relourcel lnv•tip- tion 41-75, 34 p. --19i7. Gruund watt'r 1n tht' La.ias \'aJlt>y. Put'rlu KKv L .:,. Gt"Ulogical Survey Water·Rt>suurct>s lnvt'St1gatiun ti8- 76. 45 µ Arnow. T .. and Cruoks. J. W., 1960, Pubhc Watt>r supµly in Put>rto Rieu: Cummunwt>alth of Put>rtu Rico Wa~r-Rt'Suurct>s Bullt>lm .!. 34 p. Bennett. G. 0., 1972, Gruund wa~r alunic Rio Hucana at Ponct-. Put>rl" Rieu. and t>fft'Cts uf a proposed fluodway un icruund-watt'r quality Commonwealth of Puerto Rico Watt'r-Resuurct>s Bullt>lm 11. 28 µ --1976. Elt>etncal analog s1mulat1un of tht' aqu1ft-rs alonl{ tht' south coast of Put>rtu Rieu: l:.S. Gt>olug1cal Survt-y Opt,n-FII .. Report 76-4, 101 p. Bennett. G. D .. and Giusti, E. V .. 1972, Gruund walt'r m lht> Tor· tugut>ro area. Puerto Rico, as n:,la~ to propo~ harbor construe· tion: Commonwealth of Puerto Rico Water-Resuurct's Bullt>tm 10. 25 p. Black. Crow and Eidsnt'SS. 1976, A watt>r man&gemt'nt µIan fur St. 1111'... Cruix, U.S. Virgin Islands: Black, Cruw and Eidsnt>ss, Inc .. Cun· T suiting Engineen, Gainsville, Fl. Black and Veatch, 1976, Water supply study for entire island uf Puerto Rico, fint phase: Black and Veatch Consultinar Engmeers. Kansas City, Miss. Black and Veatch, Domenech, R. A .. and Asaociates, 1970, Water resources of Puerto Rico, phut! 11. Gl'\IUnd Water appraisal: Black and Vt'Btch Consultinar Engineen. Kansas City. M~ .. and R. A. Domenech and Asaociates, Halo Rey. Put!rto Rico. Bogart, D. B., Arnow, T., and Cruuka, J. W., 1964. Water ~rces of 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 survey of Laju Valley: Univerwity of Puerto Rico Agricultural Experimen- tal Station Bulletin lll, 114 p. Briggs, R. P., and Akerw, J.P .• 1966, Hyd~lugic map of Puerto Rico and ad~nt islands: U.S. Gwlugical Survey Hydrulogic In- vestigations Atlas HA-197, ac:ale 1:240,000. Briggs, R. P., and Seiden, V. M., 1972, Geologic map of the Isla de Mona Quadranglt>, Puerto Rieu: U.S. Gt'Ulogical Survey Miscellaneous Geologic Investigations Map 1-718. scalt' 1:20,000. Buros. 0. K., 1976. Wastewater reclamation project, St. Cruix, U.S. Virgin Islands: U.S. Environmental Protection Agency, En- vironmental Protection TechnulCJKY Series EPA-600/2-76-134, 244 p. Calvesbt'rt, R. J., 1970, Climate of Puerto Rico and U.S. Virgin ~ Islands: U.S. Department of Commel'C1c' Envirunmertal Sc1t>nct> Services Administrative Publication 60-52, Silver Spnng, Md., 29 p. Cedentrom, D. J., 1950, Geolugy and ground-water resources of St. Croix, Virgin Islands: U.S. Geological Survey Water-Supply Paper 1067. 117 p. Cosner, 0. J., 1972. Water in St. John. U.S. Virgin Island~: t:.S. ~ Geoluicical Survey open-file report. 46 p. Crooks. J. W .. Gl'Ul!llman, I. G .. and Buprt, D. B .. 1968. Watt>r rt>sources of tht' Guayanilla-Yaut-u ~. Puerto Rico: Com• monwealth or Puerto Rico Water-Resoun:t"ll Bullt>tm 5, 55 p. Diaz. J. R .• 1968-1974, Ground water levels in the south coast of Put>r· to Rieu (Guanica to Patillas): U.S. Gt-olUl(ical Survey Oata Rt>least' PR-1. San Juan, P.R. --1973. Chemical quality of water in Callo Tiburones, Puerto Rico, A reconnaissance study carried out in 196i: L:.s. Geological Survey ~n-file report fmap). 2 p. --1974, Coastal salinity rt"Connaiuance anrl monitorml(" ~ystem -south cuut of Puerto Rico: lJ .S. Geological Survey Opt-n- File Report 74-1, 28 p. r i. _l , ; J. CARIBBEAN REGION L"31 will support only minor future development if effective management practices are not introduced. In the U.S. Vir ·n Islands, the most extensive uifer is 1 eous roe . t contrt utes 1ttle water to wells, but weighed against the costs of desalinated water, its exploitation is feasible for sup- plementing domestic water needs. The most productive aquifer consists of marl and alluvium deposits in central St. Croix. Although this aquifer contributes less than 6.3 Lis to individual wells, it yields about 0.86 hm3/yr to public water-supply wells and about 0.54 hm3/yr to private wells. Future development of this aquifer could probably produce an additional 1.0 hm3/yr. Ground-water resources will continue to play an im- portant role in the future development of both Puerto Rico and the U.S. Virgin Islands. In order to meet future needs, it is necessary that hydrologic principles be effectively applied in managing the total water resource. Optimization of the water resources can be ac- complished through conjunctive use of surface and ground waters and through conservation practices. Op- timal use may involve artificial recharge, ground-water salvage, saline• or fresh-ground-water mining, use of seawater, waste-water reuse, and use of underground space for temporary storage of wastes, which could otherwise contaminate valuable water supplies. Efficient development of the water resources within a basin also requires a thorough knowledge of the rela- tionship that exists between surface and subsurface water. Among the most urgent needs in the Caribbean Region is a computerized data bank containing informa- tion on ground-water withdrawal, consumptive use, sur- face diversions, and such other flows necessary for water-budget estimates. These data can be used with the available knowledge of the aquifers to construct digital or analog models. Such an approach would serve to point out areas where new information is needed, aid in assigning investigation priorities, and contribute to ef- fective management of the total water resource. uu~:_&UEUNm Acevedo, G., LupLopa. a.a., ud Ortiz.Veles., J., 1959, Occurrence of soil twnon nr-tb •• If_ * Gaaait& Lapin. Laju Valley, Puerto Rico: U~ Rico Acricultural Station Jour- nal, V. '3, IIO. 2, p. 108-111. Adolphaon, D. G., Seijo, M. A., and RobilllOll. T. M., 1977, Water reeources of M.aunabo Valley, Puerto Rico: U.S. Geological Survey Water-Rellourcel Investigations 76-115, 44 p. Anders, R. B., 1968, Reconnaiuance of the water l"NOW'Ces of the Central Guanajibo Valley, Cabo Rojo, Puerto Rico: U.S. Geolop:al SUJ"Vey open-file report, 18 p. Andel'IOII, 1976, Ground water in the San Juan metropolitan area, Puerto Rico: U.S. Geological SUJ"Vey Water-Raourc:ea Inv•tiga- tion 41-75, 34 p. --1977. Gruund water in the La;as VaJley. Puertu K1c11 L ~- Gl'()IU!PCal Survey Water-Resources lnvl'St11fat1un 68- i6. 45 p. Arnow. T .. and Cruoks. J. W .• 1960. Public Water supply in Puertu Rieu: Cummunwealth of Puertu Rico Water-Resuurces Bulletin 2. 34 p. Bennett. G.D .. 1972. Gruund water alung Riu Hucana at Pone.-. Puert" Rieu. and i:,ffl:.'Cts uf a proposed fluodway un ground-wat"r quahl~. Cummunwealth of Pu.-rtu Rieu Water-Resourc.-s Bulletin 11. 28 p. --1976. Ele-ctncaJ analug s1mulat1un of the aqu1fi:,rs alung th.- south coast uf Puerto Rico: C .S. G,,ological Surv.-y Open-fil.- Repurt 76-4, IOI p. Benllt!tt. G. D .. and Giusti. E. V., 1972. Ground water m the Tor· tugueru area, Puerto Rieu, as relatt,d tu prupuseat.a Releast' PR- I. San Juan, P.R. --1973. Chemical quality of water in Calk> Tiburones, Puerto Rieu. A reconnaiaaance study carried out in 196i: L:.s. Geological Survey open-file report (map). 2 p. --1974, Coastal salinity rtt0nnai11sance and mun1turml{ ~yslA!m - suuth cuul uf Puerto Rieu: U.S. Geological Survey Opt-n · Fil~ Report 74-1, 28 p. :u I REFERENCE NO. 4 -- -·~ - - • STD.VE: J!ETEOROLOGY OF THE f"!RGI.V ISL.-LVDS 19 The nature oi the shorter-period pressure variations in relation to the weather and the general circulation are discussed below under The L-pper Air and General Circulation, etc. PRECIPITATION Rain is the climatic element oi 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 consecutive months occurs every decade or so. caus- ing much hardship to the townspeople and small native farmers as well as to sugar and cotton estates and cattle ranches. Since early in the nineteenth century rainfall in the Virgin Islands has been measured in a unique unit oi depth, called the "line". The reason for the adoption of this measure is not known. It is an old English measure, in which 1 inch = 8 lines ( == 25. 40 millimeters). In Denmark they once used the Paris measure of 12 Linicn == 1 To1nme (Paris inch) = 27.07 milli- meters= 1.0658 inches.- I Paris line= 2.2S6 mm= .0888 inch= ½u foot, whereas the Danish West fodian (or E11glish) line= 3.17S 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 have been use