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V Page 4 <br /> Geological Technics Inc. <br /> Appendix A <br /> Project No.251.2 <br /> December 20,1995 <br /> monitor possible cross contamination from any source,a trip blank prepared from water <br /> provided by the lab, is carried throughout the sampling,storage,and shipping process. <br /> A chain of custody document is filled out which listed all samples collected, their date of <br /> collection,transfers of custody,and laboratory analyses requested. This document is used to <br /> track the samples and to ensure their integrity. <br /> Groundwater physical parameters including temperature, conductivity(EC), and pH are <br /> measured and recorded in the field and are provided in report as field logs. <br /> The groundwater samples may be analyzed by Sherwood Laboratories of Hilmar, California <br /> and tested for benzene, toluene, ethylbenzene,and total xylenes (BTEX)by EPA method 602 and <br /> total petroleum hydrocarbons as gasoline(TPH-Gasoline)by EPA method 5030/8015m. <br /> The detection limits for these analyses are as follows: benzene, toluene, ethylbenzene, total <br /> xylenes 0.3µg/l,and TPH-Gasoline 50µg/1. <br /> 2.8 ' Soil Boring Installation <br /> The soil borings will be drilled using a continuous flight hollow stem auger to a total depth to <br /> be determined but not to intercept the groundwater. Soil cuttings will either be containerized in <br /> DOT approved 55 gallon drums,labeled or lain on and covered by plastic sheeting,and stored on <br /> site until their proper disposition can be arranged. Soil samples will be collected for geological <br /> and analytical evaluation at five foot intervals. Soil samples will be collected in 6.0 inch brass <br /> liners using a 2.0 inch modified California split spoon sampler. All soil samples will be sealed <br /> with aluminum foil,capped, labeled and placed in a cooler at 4°Celsius for transport to the <br /> laboratory following Chain of Custody protocol. <br /> Because every soil sample collected will not be submitted for laboratory analysis, a screening <br /> process will be used to gather additional information through field observation noting sediment <br /> type, especially grain size and clay content; moisture content; visible evidence of <br /> contamination,i.e.,color change due to reduction of iron or discoloration from hydrocarbons and <br /> other pollutants,and the readings above background on a organic vapor meter(OVM). The <br /> OVM is a field portable photo ionization detector that uses a 10.0 eV lamp to detect compounds <br /> with ionization potential below 10.0 eV (hydrocarbon range). <br /> The soil borings will be closed as follows: A tremie pipe of sufficient length to reach the total <br /> depth of the boring will be installed through the center of the hollow stem augers and then the <br /> augers will be withdrawn from the hole. The borehole annulus will be closed by pumping a neat <br /> cement grout(<4%bentonite/cement) through the tremie tube up to grade. <br /> 2.9 Monitoring Well Construction <br /> The monitoring wells will be constructed with 2.0/4.0 inch diameter, schedule 40 PVC casing <br /> with flush threaded joints. A screened interval will consist of 0.020 inch perforations extending <br /> from approximately 10 feet below and 5 feet above the water table. <br /> A number three sand will be used to form a filter pack about the saturated zone (0.020") <br /> perforations and will extend two feet above this screened interval. An annular seal will be <br />