& MILLER, INC. nvironmental Services Ground Water Engineering Hydrocarbon Remediation Education March 17, 1993 Ana Gloria Ramos, P.E. Tutu Environmental Investigation Committee P.O. Box 364269 San Juan, Puerto Rico 00936-4269 Re: Current MCL Standards Dear Ms. Ramos: The enclosed tables (labeled as Table 1 through 5) provide the current Maximum Contaminant Levels (MCLs) for volatile organic compounds (VOCs), base neutral and acid extractables (BNAs), metals, cyanide, and pesticides/PCBs that were detected in Sampling Rounds 1 through 7 during the period September 1990 through September 1992. Please call if you have any questions. Sincerely, GERAGHTY & MILLER, INC. Thomas V. Danahy Senior Scientist/Project Manager A - Daniel A. Nachman Vice President/Project Director c: Jose Agrelot, Soil Tech Caroline Kwan, USEPA PR01301-WP3/031793B.LTR/df:lcb TUT 006 1652 201 West Passaic Street, 3rd Floor• Rochelle Park, New Jersey 07662-(201) 909-0700-FAX (201) 909-0567/0568 *64833* 64833 Table 1. USEPA Maximum Contaminant Level Standards for Volatile Organic Compounds Detected in Sampling Rounds September 1990 through September 1992, Tutu Wells Site, St. Thomas, U.S. Virgin Islands. Compound Current MCL Chloromethane —— Vinyl chloride 2 Methylene chloride 5 Acetone — — Carbon disulfide - — 1,1—Dichloroethene 7 1.1—Dichloroethane - — cis-l,2-Dichloroethene* 70 trans-l,2-Dichloroethene* 100 Chloroform — — 12—Dichloroethane 5 Bromodichloromethane ** Trichloroethene 5 1,1,2-Trichloroethane 5a Benzene 5 2—Hexanone — — Tetrachloroethene 5 Toluene 1,000 Chlorobenzene —— Ethylbenzene 700 Xylenes (total) 10,000 Maximum contaminant level (MCL) standard in micrograms per liter (parts per billion [ppb]). Other Volatile Organic Compounds (VOCs) were analyzed but not detected in any wells in any sampling rounds. USEPA U.S. Environmental Protection Agency. * - No MCL established for this compound. * Results reported as sum of cis— and trans—isomers. * * Sum of trihalomethanes MCL is 100 ppb; no MCL established for this specific compound. a Effective Janaury 17,1994. All other values currently in effect. PRO 1301 -Tl/