SITE INFORMATION AND CORRESPONDENCE

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r - �tevion tz;j::Chevron by onsite screening methods and those above the.groundwater interface.In monitoring wells EA=1, 2, and 3 only soiLsamples above the groundwater_interface{46:0 feet bgs) were analyzed..No hydrocarbons were.detected above the'MDL's: Samples from 36:0 acid 41.0.feet bgs were analyzed in monitoring well EA-4. Na hydrocarbons were detected above the MDL:s at these depths. On February 18, 1988 groundwater samples were collected from monitoring wells EA-1, 2,3, and 4, as well as, from monitoring wells MW-1, 2, and 3. Depth'to groundwater ranged from 44.6 to 46:9 feet bgs. Water samples were analyzed for TPHGas and BTEX constituents using modified EPA methods-8015 and 8020. The MDL's-in effect were 50.0-ppb for TPHGas, 0.5 ppb for benzene, and.1.0 ppb for:toluene; ethylbenzene; and:xylene:constituents. TPHGas ranging from 90.0 to 250.0 ppb was detected in all monitoring wells except'EA-2,3. and 4. No TPHGas was found in monitoring wells EA-2,.3,-.and 4..Detectable concentrations of benzene ranging from 0.7 to 8.0 ppb were found only in monitoring'we11s MW=2, 3, and EA-2. Of these,-;only MW-2 and 3 were above the State Department of Health Services(DHS)action level(0.7 ppb). On August 7 and 8, 1990 EA installed monitoring wells EA-6 and EA-7. At this time monitoring wells MW-1, 2, and. 3 were 'abaidoned. In, their report (Report of Soil And Groundwater Investigation at Former Chevron;Service. Station'# 9-7780) dated_-September 19, 1990, EA ..describes the well installations; soil and water sampling; and,test'results. Soil samples'were .analyzed.for TPHGas and BTEX constituents according to modified EPA methods 8015 and 8020. The MDL's in effect were .1.0 ppm and 0.05 ppm. Groundwater samples_collected were analyzed . for TPHGas and BTEX according to modified EPA.methods 8015 and 8020. The MDL's in effect . Were 50.0 ppb and 0.5 ppb. t On August 7, 1990 five soil samples (30.0 to 70.0 feet bgs) taken from.EA-5 were selected for analysis. On August 8, 1990 six soil-samples (30:0 to 67.0 feet bgs) were selected for analysis. . No hydrocarbon concentrations -above the MDL's were detected in any of the soil samples' submitted from both wells. The depth to groundwater measured in monitoring wells EA-5 and.EA-6 was'69.5 and 68.9 feet bgs: Water samples were collected'for analysis on--August 17, 1990: Both samples did not detect TPHGas or BTEX constituents above the M012s. On November 22, 1991 GTI_drilled soil'.boring SB-=I to a total depth of 70,0 feet bgs. Their.report (Environmental"Assessmenf Report-Former Chevron_Service Station #9-7780) dated December 20, 1991; describes the soil sampling and associated analytical results, Soilsatriples were analyzed for TPHGas and BTEX constituents,using modified EPA methods 80.15 aril 8020. The MDL's in effect were 1.0-ppm and 0.005 ppm. The sample collected from 70.0 feet bgs was also analyzed for total lead according to EPA method 6010 having a MDL of 0..1,p0m. Samples were collected every five feet-between the depths.of 20.0 feet and 70.0 bgs. All samples were submitted for analysis. With the exception of a measured xylene concentration of 0.013-ppm at 70.0 bgs, all soil samples were non detect for TPHGas; BTEX, and total.lead constituents. Groundwater at the subject site has.:been monitored since March; 1987. The.depth to groundwater beneath the site has been measured At approximately-40.0 feet bgs.in March...1987 to approximately 77.0 feet-bgs in May,.1992'.The depth to groundwater has consistentlyAncreased throughout this monitoring period. The regional groundwater flow direction beneath the site is reported to,be to the northwest(Flood Control and Water Conservation Districf Report.-Fall 1989). However, measured Znk Racyool }�acye�able.