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C4010gicalTechalamc. S+, Page 2 Work Plan—Additional Site Characterization Marci's Property Project No.770.2 October 25,2001 appears localized around well MW-5. GTI proposes to install two additional deep-screened wells, MW-104 and MW-106, located adjacent to the north corner of the site building and adjacent to well MW-6. The spatial orientation of the new wells will allow the deeper aquifer gradient to be determined and refinement of the site conceptual model. 2.1 Soil Boring and Monitoring Well Installation Soil boring permits will be secured as necessary and the local regulatory agency will be notified 48 hours prior to commencing work. The subsurface will be cleared of underground utilities by notifying Underground Service Alert. The soil borings will be drilled to a depth of 95 feet bgs using an 8-inch outside diameter, continuous flight, hollow stem auger owned and operated by V&W Drilling(C57# 720904). 6W continuous current depth to groundwater is approximately 58 feet below ground surface. 2.1.1 Soil Sampling Procedure Soil samples will be collected for geological and analytical evaluation at 5-foot intervals in boring MW-104. A boring log providing sediment description using the USCS 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 Teflon, capped with Teflon end caps, labeled and placed in a cooler at 4° Celsius for transport to the laboratory following Chain of Custody protocol. Boring MW-106 will be free drilled to 75 feet bgs due to its proximity to well MW-6. Soil samples will be collected for geological and analytical evaluation at 5-foot intervals starting at 75 feet bgs and managed as above. 60Since only selected soil samples will be submitted for laboratory analysis, a screening process will be used to gather additional information through field observation including: • 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 • readings above background on a organic vapor meter(OVM) The OVM is a portable photo ionization detector that uses a 10.0 eV lamp to detect compounds with ionization potential below 10.0 eV (hydrocarbon range). 2.1.2 Soil Laboratory Analyses Based on field screening observations, up to eight soil samples from the boreholes will be submitted to Sherwood Laboratories of Hilmar(State Certified Laboratory#1400) for: • Benzene,Toluene, Ethyl Benzene and Xylene(BTEX) by EPA method 8020 • Total Petroleum.Hydrocarbons as Gasoline (TPH-G) by EPA method 5030/8015(m) • Total Petroleum Hydrocarbons as Diesel (TPH-D) by EPA method 3540/801.5(m) v r