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N APPENDIX A INVESTIGATIVE PROCEDURES Exploratory Soil Boring and Monitoring Well Installation The soil borings were drilled using hollow-stem auger drilling equipment, and logged by a PACIFIC geologist using the Unified Soil Classification System and standard geologic techniques. Soil samples for logging and chemical analysis from Wells U-7 through U-9 were collected at a maximum depth interval of S feet by advancing a California modified split-spoon sampler with brass sample liners into undisturbed soil beyond the H tip of the auger. The sampler was driven a maximum of 18 inches using a 140-pound hammer with a 30-inch drop. Soil samples from Well U-TO were collected by advancing a'Standard Penetration split-spoon sampler. The sampler was driven a maximum of 18 inches using a 70-pound hammer with a 30-inch drop? Soil samples for chemical N analysis were retained in the brass liners, capped with aluminum Moil and plastic end caps, and sealed in clean glass jars. The samples were placed on ice and transported to the;;laboratory accompanied by the appropriate chain-of-custody documentation. The drilling equipment was steam-cleaned after each boring. I Selected borings were converted to groundwater monitoring wells by the installation of 3-inch diameter flush-threaded Schedule 40 PVC casing with 0.0201inch factory-slotted screen. Graded 2x12 sand pack was placed in the annular space across the screened interval, and the wells were surge-blocked to remove void spaces in the sand pack. A bentonite and concrete seal was placed from the top of Ithe sand pack to the ground surface. A locking cap and protective vault box were installed on the top of each well. Well elevations were surveyed by a licensed surveyor oto an accuracy of 0.01 foot, relative to the USGS mean sea level datum. j Organic Vapor Analysis Soilsamples collected during drilling were analyzed in the field for' ionizable organic compounds using the HNU Model PI-101 photo-ionization detector with a 10.2 eV lamp. The test procedure involves measuring approximately 30 grams from an undisturbed soil sample, placing this sub-sample in a clean glass jar,11and sealing the jar 3100103/REPO RT3 A- 1 June 11, 1993 L l j.