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under chain-of-custody manifest and submitted to American Environmental Network(AEN)in Pleasant Hill, California,a California-certified laboratory,for chemical analyses ' One or more sod samples per coring,based on the highest PID reading or other selective criteria,was submitted for chemical analyses of total petroleum hydrocarbons as gasoline(TPH-g)and benzene, toluene,ethylbenzene,and total xylenes(BTEX) by Environmental Protection Agency(EPA) ' Methods 8015/8020 Subsurface Assessment-Groundwater. Groundwater samples were collected from borings C8,C9,and ' C10 for laboratory analysis to determine water quality Sod boreholes C8,C9,and C10 were converted to temporary groundwater collection points by installing 10 feet of 1-inch slotted polyvinyl chloride(PVC) pipe and 15 feet of i-inch blank PVC casing Groundwater was allowed to accumulate in the casing and grab ' water samples were collected in 40 milliliter vials Field screening of groundwater samples was also conducted using Draeger tubes to determine the presence of benzene,toluene and xylenes Field screening of groundwater samples was accomplished through head space analysis using compound ' specific draeger tubes to determine the qualitative presence of benzene This was done as a decision method to determine the need for additional corings for water sample collection Once the groundwater samples were collected the casings were removed and the borings backfilled with bentonite and cement ' Boring C8 was backfilled to 20 feet below surface grade and then converted to a temporary vapor monitoring point ' The groundwater samples from boreholes C8, C9,and C10 were placed on ice in an insulated cooler chilled to 41,centigrade The samples were maintained and transported under chain-of-custody manifest and submitted to AEN for chemical analyses for TPH-g and STEX Soft Vapor Extraction Test Soil boreholes C4 and C8 were converted to temporary vapor pressure monitoring points to measure the induced vacuum versus distance from the operating vapor extraction wells The drive casing used to collect soil samples from the core holes were converted to temporary mondonng points Approximately 24 hours after placing the points, pressure gauges were connected to the ' casing,the induced vacuum readings were allowed to stabilize, and readings recorded The vacuum readings were used to evaluate the extent of influence of the operating vapor extraction wells After the vacuum readings were recorded the casings were removed and the soil boreholes backfilled with cement ' grout to surface grade Physical Propenjes of Sort. In addition to the chemical analysis for sod samples,four sod samples were ' collected and subsequently analyzed for physical properties by PTS Laboratories, Inc of Santa Fe Springs, California These tests included analysis for effective porosity, bulk density, and total organic carbon (TOC) content This data was obtained for use to the fate and transport modeling of the site (section 5) The ' physical soil data properties are included in this appendix RESULTS ' Subsurface Matenal On April 22,23,and 24, 1996,ten (10)soil bonngs were advanced at the site during the subsurface assessment program Soil boring depths ranged from 20 feet below grade to 36 feet below ' grade A rewew of the soil boring logs(appendix B) indicates that the subsurface material consists mainly . of sand with some interbedded silts Groundwater was encountered between approximately 14 and 18 feet below grade in the soil bonngs The boring logs were used to construct the geologic cross-sections which are presented as figures 5,6, 7 and 16, 17, 18 �auEwPD FLUOR DANIEL GTI - '