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1 <br /> ROYAL OAK SAVINGS & LOAN <br /> lnsitu-Treatment Soil Gas Extraction Aar Quality Permit Application <br /> Page 2 <br /> 1 <br /> MW-1, drilled in the area where the underground tank was removed, showed an initial <br />' concentration of 11mg/1 and 10 months later, a concentration of 37 mg/l of total <br /> petroleum hydrocarbons (TPH) The soil samples taken, at the time of the well <br /> installation, showed a maximum level of 4,800 mg/kg of total hydrocarbon <br /> Wells MW-2, 3 and 4 were all installed at a later date by Harding & Lawson <br /> Associates All were sampled initially on January 26, 1989 Monitoring Well 2 (MW- <br /> 2) showed a substantial increase from the initial sampling to the second sampling seven <br /> (7) months later MW-3 showed a decrease to a "none detected" level and MVS'-4 <br /> showed a slight increase in the benzene level <br /> MW-5, 6 and 7 were installed in December of 1990, by WHF Wells 5 and 6 showed <br /> "none detected" levels, and MW-7 showed significant levels of BTX&E Minor <br /> hydrocarbon contamination was visually detected in soils at a 20 foot depth in MV1-7 <br /> After the pump test and well development, a sampling round was conducted and all <br /> wells showed "none detected" in February of 1991 A subsequent round was taken in <br /> March of 1991, and this round showed all wells "none detected", except Well 2 Well <br /> 2 had Benzene in it at 1 i ppb Groundwater gradient has been measured in several <br /> directions oyer the life of this project These measurements show swings from southeast <br /> to east to northeast The Regional Water Quality Control Board (RWQCB) and the San <br /> I Joaquin County Environmental Health Department had determined that down gradient <br /> is northeast and had asked for a monitoring well to be installed to the northeast <br /> On May 2, 1991, MW-8 was installed, northeast of the remedial excavation This well <br /> was installed at the direction of the RWQCB to determine if groundwater had migrated <br /> to the northeast portion of the site Soil and groundwater samples tested negative for <br /> BTXE and gasoline <br /> In the July sampling round, all wells (MW-2, MW-4, MW-5, MW-6, MW-7 and MW- <br /> 8) showed "ND" for BTXE and gasoline In October and November of 1991, MW-2 <br /> and MW-7 had low levels of some compounds The January, 1992 sampling showed <br /> low levels of Benzene and Xylene in MW-2 In the April, 1992 sampling, MW-2, <br /> MW-6 and MW-7 were tested All three (3) wells showed "ND" levels for BTXE and <br /> gasoline <br /> I <br />