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1993 Third Quarter Report,Site Code 1178 City of Stockton,Police Facility .. Project No.W0148.02 Page 2 Laboratory analyses of soil samples collected at five foot intervals from 10.0 to 40.0 feet in the well boring did not detect the presence of gasoline constituents above the method detection limit. The depth to first groundwater beneath the site was recorded at approximately 38 feet below grade. Analysis of groundwater samples collected subsequent to the development of MW 1, indicated groundwater was not impacted by petroleum hydrocarbons. Excavation On July 23, 1992, under the direction of RESNA, excavation activities were initiated. The excavation was performed by Falcon Energy Associates (Falcon Energy, license#584524) using a backhoe tractor. Visible hydrocarbon impaction of soil was evident to a depth of approximately 6 to 6.5 feet below grade. PID measurements detected vapors intermittently to approximately 8 feet below grade. Analytical results of confirmation soil samples collected from the excavation floor and sidewalls indicated hydrocarbon impacted soils remained in place along the northern wall of the excavation, apparently extending some distance beneath the existing structure. All excavated materials were transported to the City of Stockton Municipal Service Center where they were placed on asphalt and covered by 6 mil plastic sheeting. Approximately 305 yards of native and backfilled soil were excavated from the subject site and stockpiled at the City Service Center. Subsequent to excavation and soil sample collection, the open excavation was backfilled with clean engineered sand under the requirements set forth by the City of Stockton Public Works Department. Characterization of the stockpiled soil at the Service Center, which consisted of the collection of three 2:1 composite samples on July 31, 1992, was conducted by RESNA. CURRENT SITE ACTIVITIES Groundwater Sampling On August 9, 1993, RESNA monitored current groundwater conditions beneath the site. The depth to water was measured using an electronic water level probe. Groundwater was present at 43.51 feet below grade. The groundwater level has risen approximately 3.3 feet since August 1992. Subsequent to monitoring, sixteen casing volumes of water were purged from the well prior to sample collection. Electrical conductivity, pH and temperature readings were measured during well purging to confirm collection of a representative groundwater sample. Purge water was contained in an approved DOT 55 gallon drum and remains on site. If analytical results QRTLYRPT%QR082393.DRF