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CpealaNicdTwhnics Inc_ %401 Page 2 McGranahan(Gawne Road) Project No.251.2 February 9,1996 30 feet north of the tank and SB-6 is proposed to be located about 25 feet east- northeast of the tank. 2.1.1 Soil Boring Installation Prior to commencing work, soil boring/monitoring well permits will be secured and the SJCPHSEHD will be notified 48 hours in advance. The subsurface will be cleared of underground utilities by notifying Underground Service Alert 48 hours in advance of drilling work. In all cases, any boring will be extended to a depth of twenty feet past the last field evidence of contamination or until it intercepts groundwater. The expected depth- to-groundwater in this area is approximately 90 to 100 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 h rated with tap water. A neat cement grout containing c4% bentonite bwill be pumped to grade, using a grout pump and tremie pipe. Clean sol ing 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. 2.1.2 Soil Sampling Procedure Soil samples will be collected for geological and possible 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 or Teflon sheets, capped, labeled and placed in a cooler at V Celsius for transport to the laboratory following Chain of Custody protocol. Because every soil sample 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 ionization detector that uses a 10.0 eV lamp to detect compounds with ionization potential below 10.0 eV (hydrocarbon range).