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ATTACHMENT A FIELD AND LABORATORY PROCEDURES Exploratory Drilling The soil borings for well installations will be drilled using 8-inch hollow-stem auger drilling equipment to depths of approximately 28 feet below ground surface (bgs) (MW-1 through MW-4) Borings will be logged by a Pacific Environmental Group, Inc geologist using the Unified Soil Classification System and standard geologic techniques Soil samples will be collected at 5-foot depth intervals using a California-modified split-spoon sampler The sampler will be driven a maximum of 18 inches using a 140-pound hammer with a 30-inch drop All soil samples for chemical analysis will be retained in brass liners, capped with Teflon squares and plastic end caps, and sealed in ZiplockT"'-style bags The samples will be • placed on ice for transport to the laboratory accompanied by chain-of-custody docu- mentation All down-hole drilling and sampling equipment will be steam-cleaned following the completion of the soil boring Down-hole sampling equipment will be washed in a tri- sodium phosphate or alconox solution between samples Geoprobe® Procedures The GeoprobeO boring will be advanced using a direct-push, hydraulic and percussion drive- point sampling system This will involve the driving of a one-inch O D screen point sampler to deep groundwater (expected to be approximately 39 feet bgs) Once to depth, the sampler case will be retracted a distance corresponding to the length of an enclosed 112 inch x 18 inch stainless steel screen This disengages an expendable point and allows the slotted screen to extend into the open borehole The water is then allowed to enter the sampler through the screen for collection Groundwater will be collected from the boring using a mini-bailer, lowered to the screened interval through the hollow drive tube The collected water samples will be submitted to a California State-certified laboratory for analysis 911-00 5 18/WRKPLN DOC A-1 June 10, 1998