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J L �• ATTACHMENT A FIELD AND LABORATORY PROCEDURES Chevron Service Station 20-1761, 1103 South Main Street, Manteca, CA Health and Safety As required by the Occupational Health and Safety Administration (OSHA) Standard "Hazardous Waste Operations and Emergency Response" guidelines (29 CFR 1910.120), and by California Occupational Health and Safety Administration (Cal-OSHA) "Hazardous Waste Operations and Emergency Response" guidelines (CCR Title 8, Section 5192), SECOR prepared a Site-Specific Health and Safety Plan prior to the commencement of fieldwork. The Site-Specific Health and Safety Plan was reviewed by the field staff and contractors before beginning field operations at the site. Exploratory Drilling The soil borings were drilled using an 8-inch hollow-stem auger drilling equipment to approximately 31 feet bgs. The borings were logged by a SECOR representative using the Unified Soil Classification System and standard geologic techniques. Soil samples for logging were collected at 5-foot depth intervals using a California-modified split-spoon sampler. The sampler was driven a maximum of 18 inches using a 140-pound hammer with a 30-inch drop. Soil samples for chemical analysis were retained in brass liners, capped with Teflon squares and plastic end caps, and sealed in clean zip-lock bags. The samples were placed on ice for transport to the laboratory accompanied by chain-of-custody documentation. Down-hole drilling and sampling equipment was steam-cleaned prior to and following the completion of the soil boring. Down-hole sampling equipment was washed in a tri-sodium phosphate or alconox solution between samples. Groundwater Monitoring Well Installation The borings were 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 feet of screen was placed in the bottom of each boring. A #2 sand was placed in the annular space across the entire screened interval, and extended approximately 2 feet above the top of the screen for each well. A two-foot thick bentonite seal was placed above the sand pack. The monitoring wells were completed with neat cement from the bentonite seal to ground surface. The well casings were topped with a locking cap, and the well heads were contained in watertight well boxes, either traffic rated and flush mounted or in a "stove-pipe" arrangement. The boring logs show well construction details. The wells were developed after completion by pumping or bailing water from the wells until the water was visibly clear, the wells went dry, or until a maximum of ten casing volumes had been removed. Organic Vapor Procedures Soil samples collected at 5-foot depth intervals during drilling were analyzed in the field for ionizable organic compounds using a photo-ionization detector (PID) with a 10.2 eV lamp or a flame ionization detector (FID). The test procedure involved measuring approximately 30 grams from an undisturbed soil sample, placing this subsample in a sealed container (either a