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Geological Technics Inc� _ _ - f- _ �-- - � -- -- = Page 4 Appendix A I Project No 2812 January 29,1996 ' Groundwater physical parameters including temperature, conductivity (EC), and pH are measured and recorded in the field and are provided in report as held 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-Diesel)by EPA method 3510/8015m The detection limits for these analyses are as follows benzene,toluene, ethylbenzene,total xylenes 0 3 gg/l,and TPH-Diesel 50µg/1 ' 2.8 Soil Boring Installation The soil borings will be drilled using a continuous flight hollow stern auger to a total depth to be determined but not to intercept the groundwater Soil cuttings will either be containerized in DOT 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 4°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, 1 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) The soil borings will be closed as follows 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total depth of the boring will be installed through the center of the hollow stem augers and then the augers will be withdrawn from the hole The borehole annulus will be closed by pumping a neat cement grout -(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 tremae tube up to grade 2.9 Monitoring Well Construction The monitoring wells will be constructed with 2 0/4 0 inch diameter, schedule 40 PVC casing with flush threaded joints A screened interval will consist of 0 020 inch perforations extending from approximately 10 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 installing 50 pounds of granular bentonite that will be hydrated with tap water and be allowed to expand for a period of one hour In the remaining annulus, neat cement grout will be installed using ' a slurry pump and tremae pipe The well will be secured with a water tight locking cap encased within a traffic safe well box A well ' S construction schematic is attached