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Groundwater samples were collected from the seven wells using a disposable sampling bailer, Packed in an iced cooler and transported for analysis under chain-of-custody documentation to American Environmental Network (AEN), a state of California certified hazardous waste testing laboratory The laboratory analyzed all groundwater samples for Total Petroleum Hydrocarbons (TPH)-as-gasoline, benzene, toluene, ethylbenzene, xylenes (BTEX) and methyl tertiary butyl ether (MTBE) by modified EPA Method 8015/8020 and for volatile organic compounds including the alcohol- and ether-based oxygenates by EPA Method 8260 The laboratory reports and chain-of-custody documents are included as Appendix B Analytical results of the groundwater samples indicate that dissolved concentrations of gasoline hydrocarbons continue to exist in groundwater beneath the site Groundwater sampled from VW-2 continued to contain the highest concentrations of gasoline hydrocarbons (5,700 parts per billion (ppb) of TPH-as-gasoline, 370 ppb of benzene, 1,300 ppb of toluene, 230 ppb of ethylbenzene, 1,000 ppb of xylenes and 1,700 ppb of MTBE) Gasoline hydrocarbons were also detected at lower concentrations in VW-1, MW-1, MW-2, MW-3 and MW-5 Monitoring well MW-4 was the only well without detectable concentrations of gasoline hydrocarbons The current and historical analytical results are summarized in Table 2 MTBE was the only oxygenate detected MTBE was detected in VW-2 at 1,700 ppb, MW-3 at 1,400 ppb, MW-2 at 230 ppb and in VW-1 at 60 ppb The volatile organic compound 1,2- Dichloroethane was also detected in MW-3 at 230 ppb, VW-2 at 190 ppb, MW-2 at 120 ppb and in VW-1 at 14 ppb Neither MTBE nor 1,2-Dichloroethane was detected in MW-1, MW-4 and MW-5 Another volatile organic compound, Carbon Disulfide was detected in MW-5 at 11 ppb The analytical results from the oxygenate and volatile organic compound analyses are summarized in Table 3 ' 2.3 Wastewater Testing and Disposition Based on prior analytical results from groundwater sampling of MW-4 and MW-5, the waste purge water from these wells has never previously contained detectable concentrations of TPH- as-gasoline or BTEX compounds As such, on November 13, 1997, the drummed waste purge ' water from these two wells was discharged to the land Purge water from the current groundwater sampling effort was contained in 55-gallon drums pending laboratory results 1 3