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P'r! V,At S 4.2 Groundwater Results The analytical groundwater parameters included total petroleum hydrocarbons("I'Pfl)as gasoline (Modified EPA Method 8015), benzene, toluene, ethylbenzene, and xylene (BTEX) (EPA Method 8020); and total lead (EPA Method 7421). TPH was not detected in any of the three monitoring wells. The constituents of BTEX were not detecied in monitoring well SItK MW 1, while trace levels of toluene were detected in monitoring well SRK-MW2 at 0.82 ppb, and in f.x monitoring well SRK-MW3 at 0.63 ppb. It should be noted that the detection limit for toluene (water) is 0.50 ppb. Lend was not detected in rnonitoring wells SRK-MW2 and SRK-MW3, however, lead was detected in monitoring well SRK-MW1 at 53 ppb. The analytical detection limits are as follows:TPH, 50 ppb;Benzene,Toluene,Ethylbenzcne, and Xylene,0.50 ppb; and lead, 1.0 ppb. Copies of the analytical groundwater data are provided in Appendix G. f 5.0 TFMpURARY MONfrORJNG WELL CLOSURE During the SRK field program a temporary monitoring well was discovered approximately 5 feet south of the former USTs. The well was reportedly installed by J.H. Kleinfelder in 1985. The well consisted of 4-inch diameter Schedule 40 screen that extended from the ground surface to an approximate depth of 52 feet BGS. The annular space between the perforated casing and the original boring was open from the ground surface to a depth of 18 feet BGS. The remainder of the annular space was filled with sandy clay and wood/metal debris. No odors or soil staining were observed in the cuttings. The bottom five feet of the well appeared to be filled with sediment. " Following discussions with the San Joaquin County representative, Margaret Lagorio, Turner Explorations Inc.,was retained to overdrill the temporary monitoring well,remove the perforated casing,and thoroughly grout the hole. A rotary drill rig equipped with 10-inch diameter augers was used to overdrill the boring to an approximate depth of 55 feet BGS. The perforated casing was carefully removed from the hale,along with a minor amount of cutting. The overdrilled hole was then grouted and scaled at the ground surface with concrete. The drummed cuttings were placed adjacent to monitoring well SRK-MW2. 6.0 REGULATORY SITE- VISITS Ms. Margaret Lagorio, Senior REAS, San Joaquin County PHSIEHD inspected the grout installation of each monitoring well,and also the temporary monitoring well closure. Ms.Lagorio - - '� was also present during the�rountlwatcr sampling event. After monitoring well SRK-MW2 was - _, bailed dry after one casing volume was removed, Ms Lagorio dire ted SRK to sample the well after the well had recharged. Steffen Robcrwu and Kintea