USVI Public Records

Document text

R SIf Ps bas in cooperation with the DEPARTMENT OF THE INTERIOR ARIBBEAN RESEARCH INSTITUTE | WATER RE CS , e4-1>) UNITED STATES GEOLOGICAL SURVEY COLLEGE OF THE VIRGIN ISLANDS OPEN-FILE REPORT Btn HEPORY Sens ESTIMATED WATER USE IN ST. THOMAS, The main urban area of Charlotte Amalie is also served by a seawater system. This system supplies water for fire However, various storm drains in Charlotte Amalie are continuously flushed to’ the ocean by taps from the seawater- ‘ are required to have cisterns with a minimum useable capacity of 4% gallons per square foot of roof area except churches and and water quality of these areas are limited by excessive depth to water, seawater intrusion, waste-water contamination, and SOURCE, DISTRIBUTION, AND USERS OF DESALINATED : fighting and flushing of toilets distribution system. Discharge warehouses, which are not contamination from seawater 4 | U.S. VIRGIN ISLANDS, and open drains. Areas outside from two of these taps were required to conform to this mains. the seawater system depend on measured and had an average flow standard (Jordan. and Cosner, "gray water" (wastewater from of 0.08 Mgal/d each. Five of 1973). A comparison of yields i i i [¢] 1 2 3 4 MILES Area served by public sewage U.S. VIRGIN ISLANDS (fig. 8). The potential yield streams and the ocean. ea Area served 0 1 : | wectnea ne 9 Fe -o. 3 Water pumped to the Virgin Islands law requires ee Pipeline installed but not ee eee JULY 1983 - JUNE 1984 seawater distribution-system all dwellings, apartments and au dd tiie os teen a operational as of July 1984. averages 1.0 Mgal/d. Only about hotels to have a minimum cistern Cov ekument Age O©), SBE sere Chet Cooter [_ ] Areas not served Nadir Sewage treatment plant and effluent, By 0.35 Mgal/d of this amount is storage of 10 gallons for each Virigta Talandn: Public Sima Meparenents! Woe. ettia 5 i tes (0.02) _in million gallons per day during 3-7 April 1984 ne accounted for at the public gquare foot of roof area for one muerte manner FIGURE 6. Areas served. by the fresh-water distribution system FIGURE 9. Location, outflow volume, and areas served b "JUNE 16 JUNE 17 JUNE 19 ==JUNE 20 j j ‘ gin Teldnde Housing Autwortey: r Aiithony 5. Bomehules : ‘ y the JUNE 21 JUNE 22 Heriberto Torres-Sierra and Rafael Dacosta sewage treatment plant serving story buildings, and 15 gallons GM GER Ge Sp pie ge public sewage treatment plants in St. Thomas. FIGURE 10. Effluent discharge rate at the Charlotte Amalie waste-water Charlotte Amalie. The remainder for each square foot of roof of the St, Shenae boeaarfud-cpntoniniimn 66 thet Geter cenaead treatment facility during June 16-22, 1984. | “ cooperation, may be lost through leaks in the grea for two or more story es INTRODUCTION ener Sp eUe ae ; ee seawater-—distribution system. buildings. All other buildings 3-0 i SUMMARY | water produced is accounted for, eee | Water use data (withdrawal mostly due to losses from Seawater is the principal and return amounts) has always leakage in the distribution ; ' enat source of water in St. Thomas. | ‘: : ; 67°00 66°00 65°00 | been the most difficult element system installed in 1949 (Priede- T ; ! Y About 67.1 Mgal/d are used for to define in the hydrologic Sedgwick, Inc., 1979). Other < thermoelectric power generation cycle. The need to determine losses are due to unauthorized ATLANTIC OCEAN = and 23.6 Mgal/d are withdrawn the amount of water used to meet connections, faulty meters, and = for desalination purposes. public, commercial and domestic uncontrolled public faucets = Commercial self-supplied users : 18°30". ST. THOMAS] needs among other uses is (fig. 3). x = withdraw about 2.0 Mgal/d mostly essential where the available i ° for cooling, and flushing of supply is inadequate. In St. Culebra St. John = toilets. The seawater distribu- Thotias, U.S. Virgin Islands, WATER SOURCES AND USES U.S. S : tion system supplies about 1.0 where streamflow occurs mostly Vieques VIRGIN Z 1.0b Mgal/d for fare fighting and for | during periods of intense The principal sources and 18°00" ISLANDS = flushing of toilets and storm | rainstorms and ground-water uses of water in St. Thomas are 2 drains (fig. 11), rescurces are limited (Jordan shown in fig. 4. Seawater, - = and Cosner 1973) water-—use rainfall collected from residen- SALE REA SS Seawater desalination is 2 me . St. Croix FIGURE 7. Average-annual rainfall, in inches. Paes information is critical. tial roof-top catchments, and 9 10 20 30 40 MILES (Prepared by R.J. Calvesbert, (NWS) NOAA.) the principal source of fresh- ground water are the main water 17°30’ 3 water with an average production In 1983, the U.S. Geolog- sources in the island. Thermo- 1 hs " eer of 2.5 Mgal/d. About 2.4 Mgal/d ical Survey, Water Resources electric-power generation, pub- FIGURE 1. Location of the U.S. Virgin Islands. FIGURE 3. Comparison of the quantity of water distributed (96 HERCEUE of total production) Division, in cooperation with lic-water supply, and domestic and accounted use by Virgin Islands Public Works Department. are distributed for public the Water Resources’ Research and commercial self-supply are supply. Of this amount 2.3 Institute of the College of the the principal uses. Mgal/d are pumped to the public- | 50 water supply distribution system L Ww * ; : St. Thomas. as the source of condenser-cool- > E Wg ctar ‘cost the island's population. The ing water by the Virgin Islands é cc > ; remainder, or 0.10 Mgal/d, is St. Thomas is located about Water and Power Authority (WAPA). 24 Za 1 distributed by commercial water 5 = 40 FIGURE 11. Water sources, uses, dispositi 20 miles east of Puerto Rico The waste heat from the Island . 2 « in St. Thomas, in illfon gatiane nae ats ee ey haulers to rural areas in St. (fig. 1). The island's popula- thermoelectric: faeility (fig. a ] aes a enn Thomas or barged (0.02 Mgal/d) tion increased from 16,000 in 5a) is used by the seawater-de- = ~~ Wr ‘ a2 GROUND WATER EXPLANATION Te ee to the adjacent islands of St. | 1960 to more than 47,500 in salination plant (fig. 5b). . Hopulation ey oo ZO 0.35 MGD Bare ei Mature snowrses Miscotlancous Mop. so | 1984, paralleled with an in- Desalinated water from storage 230 ey Area per day Possible restraints Ajeyt, 0... and a eee Fa 128, i Series. self-supplied users obtained * . i | ‘ . < eerie es cheeses Jordan, D.G., and Cosner, 0.J., 1973, A sur- bout. 0.20-M 1/d eoeets h crease in water production to tanks (fig. 5c) is distributed z ‘ f <5 the Virgin Islands area, St. Thomas: , ae as abou : ga of freshwater = 000-30,000 | Waste-water contamination and seawater intrusion 2 g f£ the wat sources of St.Thomas ; meet the public water-supply to the urban areas in Charlotte 2 L a Zz | igi Blac sie SS Virgin Lelende: 0.8. Geological Survey from privately operated desalin- = 0 < es a . | = wo a oz fe) -= o cz aoe > < L ‘ -Si : these are also tapped as a units is about $9.00 per The comparison was made for a for cooling, flushing toilets, Heriberto Torres Sierra and Rafael Dacosta source of water, even if saline, thousand gallons ($9.00/kgal). family of four using 25 gallons and swimming pools. Small as feed for. reverse osmosis This does not include amortiza- per capita per day (25 gpcd} desalination plants produce units or for flushing. tion costs of the desalination With a roof area of 1,000 ft about 0.1 Mgal/d freshwater. units (Ajayi and Gomez, 1983). and an initially full cistern ¥ Bottled water produced The actual costs charged by (10,000 gal). The family would About 0.2 Mgal/d of the locally “or . imported, is. an VIPWD to consumers connected to have required the services of a commercial water-use is ground DEPARTMENT OF important drinking water source. the distribution system is water hauler only once if they water. This is used mostly for : Bottled water costs approximate- $14/kgal (VIPWD personal communi- lived in the Dorothea area, and flushing’ toilets. In some es * ie increased to a peak of about 2.4 domestic self-supplied. Rain- An additional 0.05 Mgal/d was in St. “Thomas: (fies 9). The Mgal/d in 1975, declining water collected from rooftop used by other domestic self- airport plant, serving Charlotte ad i i i thereafter, to less than —§0.6 catchment systems and stored in supplied users. Amalie, discharges about 0.5 I T T Prepared in cooperation with the Mgal/d in 1980. Since 1981], cisterns, and withdrawals from Mgal/d to the ocean. Instantan- CARIBBEAN RESEARCH INSTITUTE COLLEGE OF THE VIRGIN ISLANDS ST. THOMAS, U.S. VIRGIN ISLANDS JULY 1983 - JUNE 1984 By THE INTERIOR DIVISION ESTIMATED WATER USE IN ST. THOMAS, Virgin Islands, began a general- ized inventory of water use in demand (fig. 2). The water demands have increased also in response to tourism development. Although the production of water increas- ed with the installation of a large-scale seawater desalina- tion plant by the Government of the U.S. Virgin Islands, the demand has not been satisfied. Seawater is used indirectly Amalie (fig. 5d), by the Virgin Islands Public Works Department (VIPWD). Areas outside the public-water supply distribution system, such as the Donoe housing project at New, (fig. 5e) can be classified as self- supplied users. These obtain their water supply from rainfall catchments, wells, or from com- mercial water haulers (fig. 5f). UNITED STATES WATER RESOURCES OPEN-FILE DATA REPORT 84-721 other household uses) as their source of water for flushing toilets or irrigation. Where aquifers yield significant water to wells (10 gal/min or more) ly $1.25 per gallon. In 1979 importation of bottled water was estimated at 1,600 gal/d (Peebles, 1979). There are no reliable figures for current imports. Public-Water Supply Production of desalinated (revenues from sales) by the VIPWD. About 1.5 Mgal/d was unaccounted for as_ previously indicated. A recent investiga- tion showed that leakage in the distribution system represents 30 to 40 percent of the total losses (CH2M Hill Southeast, 1983). The production of desalina- ted water for public supply WAPA has installed three new desalination units with a total yated capacity of 3.1 Mgal/d. At present only two units are being operated. Full production constructed in 1977 but has not been utilized. these taps would account for % of the unaccounted flow.. The cost of potable water to WAPA from the desalination cation, 1984). Thermoelectric-Power Generation Thermcelectric-—Power Gene- ration is the largest single water .use’ -category in St. directly from the desalination plant for boiler feed. Domestic Self-Supplied - Rainfall About two-thirds of the population in St. Thomas is not served by the potable public water supply distribution system, and thus classified as ground water are the sources for domestic self-supply. Estimated water use for this category was about 0.75 Mgal/d. Of "this amount, 0.60 Mgal/d (80 percent) especially in the more humid areas of the island (fig. 7). se ° \l LO ra a 7 rd a 7 ~ L) So aN \ ae it =i [o) eee \ N \ » Water production a (Water and| Powe desalination plant 7 r Authority only) ay (e] 8 S N 64 66 68 70 a Le) 72 «674 76 78 80 82 84 CALENDAR YEARS FIGURE 2. Water production and population trends in St. Thomas. (Source: Virgin Islands Office of Policy, Planning, and Research.) U.S. GEOLOGICAL SURVEY WATER RESOURCES DIVISION between rooftop-rainfall catch- ments at a high rainfall (Doro- thea) and at a low rainfall area (Red Hook), was made using data from July 1983 to June 1984. twice if they lived in the Red Hook area. Rainfall could have supplied about 50 percent of the total water needs in the Dorothea area, but only 31 percent at Red Hook. The cost of water produced by household roof-top cistern a cistern. Domestic Self-Supplied - Ground Water Ground water withdrawn for domestic self-supplied use was about 0.15 Mgal/d. Ground-water withdrawals by the Virgin Islands Housing Authority (VIHA) was estimated at 0.10 Mgal/d. Ground water for domestic use is available in nearly all parts of the island. There are only a few areas where yields to wells are large enough to warrant areas according to their poten- tial yield and water quality Commercial Self-Supplied Condominiums and hotels used about 2.0 Mgal/d of saline water. This is used principally areas, where the ground water is of good quality, the waste water is used for irrigation of lawns (Mahogany Run). However, most of the commercial facilities are located near the coast and pump saline-ground water. Water haulers supplied an GEOLOGICAL SURVEY water during the study period Thomas. Total use was about 67 systems is estimated at $17 to estimated 0.07 Mgal/d of desalin- Cus) averaged 2.4 million gallons per Mgal/d. This was essentially $19/kgal (CH2M Hill Southeast, ated water from the VIPWD Rik day (Mgal/d). Only about 0.9 seawater, except about one 1983). The major cost is standpipes to commercial users. Mgal/d (38 percent) was accounted percent freshwater obtained associated with construction of The average price of water delivered by water haulers is $55/kgal (Ajayi and Gémez—Gémez, 1983). An estimated amount of 0.05 Mgal/d was obtained from rooftop rainfall catchments. Public Waste-Water Treatment There are seven’ public waste-water treatment facilities eous flow rates measured in June 1984 ranged from 0.16 to 1.4 Mgal/d™ (tig. . 10). Specific conductance measurements indica- ted that about 70 percent of the public-housing projects. These discharge about 0.20 Mgal/d to SALINE WATER 93.72 MGD RAINFALL 0.65 MGD PF — Thermoelectric Power WS - Public Supply DO - Domestic CO - Commercial! FIGURE 4. Estimated water use by source and major use category in St. Thomas during July 1983 to June 1984. FIGURE 5a. Seawater intake at the Thermoelectric Power Plant at Krum Bay (Sub Base). FIGURE 5d. Domestic and commercial users at Charlotte Amalie area. EXPLANATION 1000-10,000 |Seawater encroachment Excessive depth to water or seawater intrusion Under 50,000 | Seawater intrusion Contamination from seawater mains or Under 1000 seawater encroachment 3) BB | 250-1000 L FIGURE 8. Ground-water areas, potential yield to wells, and restraints which could limit withdrawals. (Adapted from Jordan and Cosner, 1973.) a ec a Ee FIGURE 5b. Seawater flash vaporization desalination plant at Krum Bay (Sub Base). WATER IN ST. THOMAS FIGURE 5c. Desalinated water storage tanks at Sara Hill near Sub Base. FIGURE Se. Domestic self-supplied users at Donoe housing project. FIGURE 5f. Commercial water hauler at Virgin Islands Public Works Department’s potable water standpipe at Sub Base. Bordeaux Old Tutu (0.03) Charlotte Amalie (0.50) EXPLANATION = [=] DISCHARGE, IN MILLION GALLONS PER DAY o a To St. John and Culebra Research Institute, College of the Virgin Islands, St. Thomas, U.S. Virgin Islands, 70 p. CH2M Hill Southeast, Inc., 1983, Water man- agement plan for the public water sys- tem - U.S. Virgin’Islands: CH2M Hill Southeast, Gainesville, FL., 290 p. CH2M Hill Southeast, Inc., 1983, Water dis- tribution system master plan for St. Thomas, U.S. Virgin Islands: CH2M Hill Southeast, Gainesville, FL., 215 p. Francois, D.C., Thompson, T.P., and Ajayi, 0., 1983, Managing water supply opera- tions in the Caribbean lessons from the U.S. Virgin Islands: Natural Resources Forum, vol. 7, no. 4, United Nations, N.Y., p. 351-362. Open-File Report, 55 p. Peebles, R.W., Pratt, A.E., and Smith, H.H., 1979, Waterplan: A comprehensive water management framework for the U.S. Vir- gin Islands, Virgin Islands Water Re- search Center, Caribbean Research In- stitute, College of the Virgin Islands, 43 p. Priede-Sedgwick, Inc., 1979, Summary report of self-sufficient water supply alterna- tives - U.S. Virgin Islands: U.S. Army Corps of Engineers, Jacksonville Dis- trict, Jacksonville, FL., 170 p. U.S. Environmental Protection Agency, 1984, Final environmental impact statement for the Mangrove Lagoon/Turpentine Run Waste-water Facilities Plan, St. Thomas, U.S. Virgin Islands, 180 p. capacity will be required when was supplied from rainfall. the development of public effluent was seawater. (0.02) the East End Transmission System This indicates that rooftop supplies. In their study, ? ‘i , : = es becomes operational (fig. 6). catchments are a major source of Jordan and Cosner divided the The other six waste-water : L I I r j t i This distribution system was water for most private homes island into five ground-water treatment plants serve mostly cal which serves only one-third of ation units. Rainfall and ground water supply about 1.0 Mgal/d and are the main source of freshwater to i two-thirds of the island's population. Public waste-treatment plants discharge an average of 0.7 Mgal/d. Seventy percent of the effluent is seawater. CARIBBEAN DISTRICT SAN JUAN, PR