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ATTACHMENT A FIELD AND LABORATORY PROCEDURES Soil Borings and Groundwater Monitoring Well Installation The soil bonngs and groundwater monitoring wells will be drilled using 8-inch hollow-stem auger drilling equipment and logged by a Pacific Environmental Group, Inc geologist using the Unified Soil Classification System and standard geologic techniques Total depth of the soil borings is anticipated to be 20 feet The total depth of the groundwater monitoring wells is anticipated to be 30 feet The specific depths for the installation of these borings and wells will be based on field conditions, specifically the subsurface stratigraphy and hydrocarbon distribution Soil samples for logging 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 Soil samples for chemical analysis will be • retained in brass liners, capped with Teflon squares and plastic end caps, taped, and sealed in clean zip-lock bags The samples will be placed on ice for transport to the laboratory accompanied by chain-of-custody documentation Down-hole drilling and sampling equipment will be steam-cleaned following the completion of each soil boring Down-hole sampling equipment will be washed in a tri-sodium phosphate solution between samples The borings will be converted to groundwater monitoring wells by installing 2-inch diameter, flush-threaded, Schedule 40 PVC casing with 0 020-inch factory-slotted screen Approxi- mately 15 to 20 feet of screen will be placed in the bottom of each boring An RMC 2 x 12 sand pack will be placed in the annular space across the entire screened interval, and will extend approximately 3 feet above the top of the screen for the well A bentonite and Port- land cement seal will extend from the sand pack to the ground surface Following well completion, the vault box elevation and the elevation of the top of the PVC well casing of the monitoring wells will be surveyed to the nearest 0 01 foot, relative to mean sea level, by a licensed surveyor The boring logs will show well construction details and the well head elevations 3201591A/WKPLAN A- 1 November 8, 1995