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I T Geological Technics Inc.. Page 2 4 Former Moresco Property Site Characterization Work Plan Project No.251.2. , March 14,1995 contamination or until it intercepts groundwater. The relevant depth-to- groundwater in this area is approximateiy;.9,0 feet below grade, based on information from the 1986 San Joaquin County Flood .Control Map, Lines of Equal Depth to Water in Wells. The boreholes will be closed by installing a granular bentonite plug approximately 2 feet thick. This will`be hydrated with tap°,water. A ea cement grout n ai in <4% to e by weight will be pumped to grade, using a grout pump and tremie pipe. Clean soil cutting will be added. to the existing stockpile and' obviously contaminated soil cuttings may be underlain and covered with plastic and segregated from the existing stockpile or containerized in D.O.T. approved 55 gallon steel drums. 2.3 Soil Sampling Procedure Soil samples will be collected for geological and analytical evaluation at five foot intervals. A boring log providing sediment description using the U.S_C.S. and field observations will be maintained by a professional geologist working,under the supervision of a registered geologist.' Soil,samples will be collected in 6.0 inch brass liners using a 2.0 inch modified California split spoon sampler. All soil samples will be sealed with aluminum foil, capped with ,Teflon' end caps, labeled and placed in a cooler at 4° Celsius for transport.to the laboratory following Chain of Custody , protocol Because every soilsample collected will not be submitted for laboratory analysis, a screening process will be used to gather additional information through field observation noting sediment type, especially grain size and clay content; moisture content; visible evidence of contamination; i.e.,color change due to reduction of iron or discoloration from hydrocarbons and other pollutants, and the readings above background on a organic vapor meter (OVM). The OVM is a field portable photo L ionization detector that uses a 10.0 eV lamp to detect compounds with ionization potential below 10.0 eV (hydrocarbon,range). 2.4 Soil Laboratory Analyses Based on field screening observations up to three soil samples per borehole will be r submitted to Sherwood Laboratories of Hilmar (State Certified Laboratory #1400) L for analysis for benzene, toluene, ethylbenzene and xylene, BTEX by EPA method 8020, and gasoline range petroleum hydrocarbons by TPH-Gasoline by EPA method 3550/8015m. In addition, one selected sample, from the borehole installed at the location of the former underground storage tank will be tested for total Lead by EPA method AA 7420. The detection limits for. these compounds are listed below. A i L