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2 Tutu Wellfield St. Thomas, U.S. Virgin Islands CERCLIS #YID982272569 i Site Exposure Potential The 44-hectare Tutu Wellfield site, a group of contaminated public supply wells, is located in a mountainous, semi-rural area of cast-central St. Thomas, U.S. Virgin Islands. The site skirts Turpentine &un, an intermittent stream that flows south and discharges to Mangrove Lagoon, 4.5 km downstream (Figure 1). This lagoon is hydraulically connected to the Caribbean Sea and, ultimately, the Atlantic Ocean. In 1987, a strong odor was detected in one of the public supply wells in the area. The Virgin Islands Department of Planning and Natural Resources requested the U.S. Environmental Protection Agency to sample one hundred area wells. VOCs were detected in approximately 60 percent of the wells, and trace elements were detected in ap- proximately 30 percent of the groundwater wells. Petroleum, waste oils, solvent-based auto flushes, degreasers, antifreeze, kerosene, hydraulic fluids, spent PCE, wastes, dry cleaning fluids, ammo- nium hydroxide and mineral spirits may have been disposed of via catch basins, floor drains, sump holding tanks, leaching pits, evaporation pits, above-ground tanks, and drum storage areas in the area (U.S. EPA undated). Coastal Hazardous Waste Site Review / Tutu Wellfield • 9 TUT OO6 213t? *64928* 64928 iO * Region 2 Tutu ST. T HO M A S 13. U* V 0.5 1km ••— Tulu WeHfietd area :;•;) Mangrove •** Wetlands Figure I. General vicinity of the Tutu Wellfield groundwater sampling sites. 10 • Coastal Hazardous Waste Site Review / TuttJ Wellfield . OO6 2136 TU"1 Region 2 • 11 The site overlies two aquifers: the Turpentine Run Basin Alluvium (shallow) and the Water Island and Louisenhoj Formations (deep). The shallow aquifer is 6 to 21 m deep, with the deep bedrock aquifer located directly below. Ground- water samples were collected from the deep aquifer at depths between 24 and 68 m during four monitoring periods (September 1990, May and September 1991, and January 1992). Groundwater generally flows south throughout the Turpentine Run basin. Discharge to Turpen- tine Run is the primary pathway by which site- related contaminants can migrate to NOAA trust habitats (NUS 1991). I NOAA Trust Habitats and Species Habitats of concern to NOAA are surface water and associated bottom substrates of Mangrove Lagoon (Boulon 1990; Beets personal communi- cation 1992). Turpentine Run serves as a drain- age corridor for eastern St. Thomas and receives various inputs of municipal effluent. Turpentine Run discharges to the northwestern corner of the inner lagoon. Turpentine Run is approximately 1 m wide and 0.3 m deep and is dominated by blue algae. Dissolved oxygen levels are reportedly very low, but no data were available (Beets personal communication 1992). No NOAA trust resources are known to use Turpentine Run because of the severely degraded water condi- Mangrove Lagoon is subdivided into three areas known as the inner, middle, and outer lagoons and is bordered by a small fringe of red mangrove (Rhizopora). Bottom substrate in the lagoons is composed mainly of carbonate silt, mud, and sand, with varying amounts of organic detritus, peat, and siliceous skeletons derived from diatom algae and sponges. Aquatic vegetation is pre- dominantly turtle grasses (Thalassia) and algae (Beets personal communication 1992). The habitats of the inner lagoon are severely degraded from approximately 1.7 million 1 of "treated" sewage effluent that are discharged into the inner lagoon each day (Boulon 1990). An undetermined amount of contaminated leachate originating from the St. Thomas Municipal Landfill is also considered likely to accumulate in the inner lagoon via Turpentine Run (Boulon 1990; Beets personal communication 1992). Surface waters of the inner and middle portions of Mangrove Lagoon arc productive and are known to provide nursery and adult habitat for numerous Caribbean reef fish (Table 1). Reef fish in the lagoons use the inshore fringing reef of the outer portion of Mangrove Lagoon for spawning habitat (Beets personal communication 1992). Grunt (Pomadcuyidni) and parrotfish (Scaridae) are the most abundant species in the Mangrove Lagoon system. Other species found in consider- able numbers in the lagoon include schoolmaster (Lutjanus apodus) and sea bream (Archosargus rbomboidnlis). Larger species frequently observed in the lagoons include great barracuda (Sphyaena barracuda) and ycllowtail snapper (Ocyurus chrysurtts). Great barracuda are abundant in the Coastal Hazardous Waste Site Review / Tutu Wellfield • 11 TUT 006 2137 12 * fcegiohl I Table I. Marine species that regularly or Intermittently use the Mangrove Lagoon and associated mangrove habitats near the site. Common Name Sergeant major Ocean surgeon Dodorflsh Blue tang Bonellsh Redspotted hawkfish Sea bream Porkfish Hardhead silversides Frllllin goby Jolthead porgy Sharpnose puffer Yellow jack Blue runner Bar jack Snook . « . ' - . ' • . Foureye butterflsh Bridled goby Spotfin mojarra Green moray Grunt Slippery dick Longjaw squirreKish Grouper Dwarf herring Schoolmaster Gray snapper Dog snapper Lane snapper Tarport Yellowtail damsetfish Yellowtall snapper Gray angetlish French angelflsh Parrotfish Striped parrotflsh Princess parrotfish Redtall parrotfish Bucktoolh parrotfish Great barracuda Bluehead Species Scientific Name . Abudefduf saxatitis Acanthurus bahlanus Acanthurvs chlrumus Acanthurus coeruleus Albula \fulpes Amblyclrrhitus pinos Archosargus rhomboidalis Anisotremus \firginlcus Atherinomorous stipes Bathygoblus soporator Calamus bajonado Canthigaster rostrata Caranx bartholomael Caranx crysos Caranx nicer Cenlropomas undecimalis Chaetodon capfstratus Corypnopterus glaucofraenum Eucinostomus argenteus Gymnoihorax funebris Haemulon spp. Halichoeres bivittaius Holocentrus ascensionis Hypoplectrus spp. Jenkinsia lamprotaenia Lutjanus apodus Lot/anus griseus Luiianusjocu Lutjanus synagris Megalops atlanticus Microspathodon chrysurus Ocyvnjs chrysurus Pomacanthus arcuatus Pomacanthus paru Scaridae spp. Scan/s crolcensis Scanjs taeniopterus Sparisoma chrysopterum Sparisoma radians Sphyaena barracuda Thalassoma bifasdatum Spawning Ground1 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 Habitat Nursery Ground 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 Adult Forage 4 4 4 4 4 4 4 4 4 4* * 4 4 4 4 4 4 4 4 4 4* 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 Fisheries Comm. hecr. 4 4 4 4 4 4 4 4 4 1 Spawning occurs within the inshore fringing reef of outer Mangrove Lagoon. lagoons From April to May (Boulon 1990). No data were available for invertebrate species. Snapper (LlltjAhidne), the only commercial fishery in the area1, are commercially fished out- side Mangrove Lagoon, which, with its surround- ing surface water, supports a popular sport fishery !l • Coastal Hazardous Waste Site Review / Tutu Wellfield TUT OO6 2.138 1IiiI i For bonefish (AlbUla vulpes), tarpon (Megalops atlantica), and snook (Centropomas bndecittialis). There are currently no landing restrictions, nor health advisories for die consumption offish in the area (Beets personal communication 1992). I Site-Related Contamination Investigations have focused on groundwater sampling. Samples collected in September 1990 were analyzed for trace elements and organic compounds. All subsequent samples were'ana- lyzed only for organic compounds. Minimal soil samples have been collected and analyzed for organic compounds. No off-site surface water, sediment, or biota sampling has been conducted. Region! * 13 No organic compounds were detected in any of the groundwater samples at concentrations exceeding chronic freshwater or marine AWQC by a factor often (U.S. EPA 1986). Five trace elements were measured infrequently in ground- water at concentrations exceeding screening criteria. Cadmium, lead, ind silver concentrations exceeded their respective freshwater screening criteria. However, the measured concentrations of silver were qualified in the data report as esti- mated concentrations (Geraghty & Miller 1991). Copper dnd nickel concentrations exceeded the marine AWQC In several samples, but did not exceed the screening criteria for freshwater (Table 2). I Table 2. Maximum trace element concentrations (Ug/l) in groiindwatef at the Tutu Wellfield site compared to chronic AWQC1. Trace Elements Cadmium Copper Lead Nickel Silver Groundwaler 11 59 33 95 1B AWQC* freshwater marine 1.1+ 9.3 12+ 2.9 3.2+ 8.5 160* 8.3 .12 .92 1: ten times the AWQC is used for screening purposes to account for dilution in surface water. 2: Ambient water quality criteria tor the protection of aquatic organisms. Chronic criteria presented (U.S. EPA 1986). 4: Hardness-dependent criteria (100 mg/l CaCOs used) Coastal Hazardous Waste Site Review / TutU Wellfield • 13 TUT 006 2139 14 * Region! • Summary Numerous hazardous wastes were disposed of at this site in a manner that could permit them to enter the main drainage system of the area via surface runoff or groundwater discharge. This drainage system empties into Mangrove Lagoon, an important habitat for NOAA trust resources in the area. Elevated levels of organ ics and metals have been detected in groundwater near the site, and it is of some concern to NOAA that these groundwater contaminants, as welt as other site- related contaminants, could migrate to Mangrove Lagoon via the drainage system. IReferences Beets, J:, Chief, Bureau of Fisheries, Division, of Fish and Wildlife, St. Thomas, U.S. Virgin Islands, personal communications, June 8 and July 7,1992. Boulon, R.H. 1990. Mangrove as nursery grounds for recreational fisheries. Final Report, U.S. Virgin Islands, Dingcll-Johnsoh Expansion Project F-7, Study V. St. Thomas, U.S. Virgin Islands: Virgin Islands Division of Fish and Wildlife, Department of Planning and Natural Resources. Geraghty 8c Miller. 1991. 1st sampling report, September, 1990; Tutu Wells site quarterly sampling, St. Thomas, U.S. Virgin Islands. St. Thomas: Tutu Environmental Investigadon Committee. NUS Corporation. 1991. Final Draft: Hazard ranking system documentation; Tutu Wellficld, St. Thomas, USV1. Report No^ 02-9102-11-HR. New York: Environmental Services Division, U.S. Environmental Protection Agency. U.S. EPA. 1986. Quality criteria for water. EPA 440/5-87-003. Washington, D.C.: Office of Water Regulation and Standards, Criteria and Standards Division, U.S. Environmental Protec- tion Agency. U.S. EPA. undated. National priorities list: Tutu Wellfield. Washington, D.C.: Hazardous Site Evaluation Division, U.S. Environmental Protec- tion Agency. U • Coastal Maiardous Waste Site Review / TutU Wellfleld TUT O06 >140