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r Additionally, a confirmation sample, 1ON25 was collected from the north sidewall. ,7UlY 11 12 1989 The excavation area was backfilled and compacted with 2920 cubic yard of fill material. Samples were collected of the fill material on July 10, 1989 to verify that it was free of hydrocarbons. 'These samples are designated BKFL 1, BKFL 2, BKFL 3 and BKFL 4. These sample results indicated that the backfill was free of petroleum hydrocarbon compounds. The analytical results for the samples collected 8 feet laterally into the south sidewall indicated that _. the relatively high concentrations of TPH seen at the face of the wall were not present in significant amounts further south of the excavation (under the sidewalk and Washington Street) . 5.0 Well Abandonment Monitoring well MW-1 was abandoned on August 18, 1989. The well had originally been installed as part of the sates' groundwater investigation. ROY F. WESTON, INC. performed the abandonment and all activities were observed by a representative of the San Joaquin Local Health Districtis Environmental Health Division. This well was abandoned as it was situated such that it would interfere with the future building construction. MW-1 was removed from the ground by pulling the 4 inch PVC well casing (including the screened section) from the ground. The casing remained intact during the withdrawal. The resultant hole J was completely filled by pumping grout into place under pressure using a tremie pipe from the bottom up to ensure a good seal. The .. grout was composed of 51 bentonite and Portland type 1-1I cement. 6.0 Fuel Oil Tank Removal After the completion of the remedial excavation and during the course of initial construction activities at the Human services building site, an additional abandoned underground fuel oil tank ~~ was discovered. The location of the tank is indicated on Figure 6 and was approximately 500 gallons in size. i The tank was removed and disposed of on August 8, 1989. To evaluate the possible presence of petroleum hydrocarbon compounds in the tank area, two soil samples were collected the same day from a depth of 1 foot beneath either end of the tank. The soil samples were collected by hand augering a hole to approximately 0.9 feet below the surface. A brass tube was then — driven into the native soil to collect the sample. Once collected, the sample tube ends were covered with teflon, capped with plastic caps and sealed with electrical tape. The samples were labeled TNWA (tank sample northwest A) and TNEB (tank sample northeast B) , sealed in plastic baggies and placed with ice in an insulated cooler. The samples were transported with a completed Chain-of- - 13 -