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Former Moresco Property Page 4 Site Characterization Work Plan Appendix A Project No.251.2 March 14,1995 A chain of custody document is filled out which listed all samples collected, their date of collection, transfers of custody, and laboratory analyses requested. This document is used to track the samples and to ensure their integrity. �. Groundwater physical parameters including temperature, conductivity (EC), and pH are measured and recorded in the field and are provided in report as field logs. The groundwater samples may be analyzed by Sherwood Laboratories of Hilmar, California and tested for benzene, toluene, ethylbenzene, and total xylenes (BTEX) by EPA method 602 and total petroleum hydrocarbons as diesel (TPH-Gasoline)by EPA method 3550/8015m. The detection limits for these analyses are as follows:benzene,toluene,ethylbenzene, total xylenes 0.3 gg/l,and TPH-Gasoline 50 gg/l. �. 2.8 Soil Boring Installation The soil borings will be drilled using a continuous flight hollow stem auger to a total depth to be determined but not to intercept the groundwater. Soil cuttings will either be containerized in DOT #6a approved 55 gallon drums,labeled or lain on and covered by plastic sheeting,and stored on site until their proper disposition can be arranged. Soil samples will be collected for geological and analytical evaluation at five foot intervals. 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, labeled and placed in a cooler at 40 Celsius for transport to the laboratory following Chain of Custody protocol. Lo 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 L• eV(hydrocarbon range). The soil borings will be closed as follows: after the last soil sample has been collected the augers will be lifted 3 feet and 50 pounds of bentonite will be poured through the hollow stem of the augers and hydrated with clean tap water. A tremie pipe of sufficient length to reach the total depth of the boring will be installed through the center of the hollow stem augers and then the augers will be withdrawn from the hole. The borehole annulus will be closed by pumping a neat cement grout (<4%bentonite/cement) through the tremie tube up to grade. 2.9 Monitoring Well Construction The monitoring wells will be constructed with 4.0 inch diameter, schedule 40 PVC casing with flush threaded joints. A screened -interval will consist of 0.020 inch perforations extending from La approximately 15 feet below and 5 feet above the water table. A number three sand will be used to form a filter pack about the saturated zone(0.020")perforations and will extend two feet above this screened interval. An annular seal will be constructed by t.. v