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Working To Restore Nature of product removed. All bailed product has been stored in a DOT approved double containment drum pending appropriate disposal. Groundwater samples were collected on April 25, 1994 from wells MWl, MW2, MW3, MW5 and MW6. No groundwater sample was collected from MW4 due to the presence of free product. Prior to sample collection, each sampled well was purged of a minimum of three well casing volumes of water. Purged water was contained in labeled 55 gallon drums (DOT H), and stored on-site. Groundwater samples were collected after physical parameters (pH, temperature, and conductivity) were monitored and had stabilized. Dedicated disposable bailers with bottom- emptying devices were used to collect samples from the wells. Field purge logs are presented in Attachment 1. LABORATORY ANALYSES Collected groundwater samples were analyzed for benzene, toluene, ethylbenzene, xylenes (BTEX) and total petroleum hydrocarbons as diesel (TPHd) by Sequoia Analytical, a State- certified laboratory, utilizing EPA methods 5020 and modified 8015, respectively. Analytical {f� results are summarized in Table 3. Laboratory data sheets and chain-of-custody documentation aril=i are included in Attachment 2. Laboratory results indicate that BTEX was not present above method detection limits in collected groundwater samples. Total petroleum hydrocarbons as diesel were present in well MW2 at 140 parts per billion (ppb), well MW3 at 230 ppb, and well MW6 at 150 ppb. CONCLUSIONS In accordance with San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) correspondence dated May 17, 1994, RESNA will implement the following sampling schedule: o All site wells will be monitored for fluid levels on a quarterly basis; O Monitoring wells MW3 and MW6 will be sampled on a quarterly basis; o Monitoring well MW2 will be sampled on a semi-annual basis during the first and third calendar quarters; 4 =' 0W03651QRTERLYI2QMR1994.FNL i