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NA i f Mr. Kenneth Olds 90vember 15, 1988 202/799--5055 Page 3 Laboratory analyses of water samples for BTEX and TPH as gasoline concentrations were performed using U. S. Environmental Protection Agencv (EPA) Methods 5034/8015/8020, which are equivalents of modified EPA Method 602. In addition, the samples were analyzed for TPH as diesel using modified EPA Method 8015; ethylene dibromide (EDB) by EPA Method 504; and total lead by EPA Method 3020/7421 . The laboratory reports are enclosed in Appendix III, and the analytical results are summarized in Table 2. Groundwater monitoring data, collected twice during October 1988, are summarized in Table 1, and contoured on Figures 3 and 4. The dominantly northeastward groundwater flow direction appears to have persisted since monitoring began in June 1987, although some changes in the configuration of the groundwater elevation contours has occurred, possibly due to pumping ac- tivities in nearby water wells. Chemical analyses of water samples indicated 8,000 ppb TPH as gasoline in MW-2, but no detectable gasoline-range hydro- carbons in the other four monitoring wells (Table 2) . The absence of detectable TPH as gasoline in M.w-3 through MW-5 indicated a Limited lateral extent of the dissolved gasoline plume to the south, southeast and north of the abandoned gasoline tank pit. In MW-1, which is located only a few feet from MW-2, the apparently anomalous non-detectable levels of TPH as gasoline may have been caused by the depth of the screened interval in MW- --. relative-_tothe- depth-to-water.----In MW-1-the-top--of-the- screened W-1the-top -of-the screened interval is at a depth of about 9 feet below grade, approximately four feet deeper than in the other four monitoring wells at the site. On September 28; 1988, when MW-1 was sampled,