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'Mi. Tim Smith County of Los Angeles %.00 Department of Public Works October I9, 2009 Page 3 SAMPLING PLAN Sam lin Location and De the At this time, OGI is proposing to drill a minimum of two borings along both sides of the south end of the center island (Figure 2). Attempts will be made to locate the borings as close to the southern dispenser as possible. An "air knife" will be used to locate the product lines prior to drilling to minimize risk of damaging a line during drilling. Each boxing will be drilled to a minimum depth of - 25 feet below ground surface. Soil samples will be collected at five foot intervals or as lithologic conditions permit using split spoon sampling techniques. Boring depths may be extended beyond 25 feet if there is evidence of hydrocarbon impacts at the 20 and/or 25 foot depth interval. If hydrocarbon impacts are encountered in either boring, then step-out borings may also be required to further delineate the lateral extent of the impacts. This will be a field decision based on field screening results. Field Screening and Lithologic Logging Soil from each boring will be screened visually and with a Photo-Ionization Detector (PID)-for evidence of hydrocarbon impacts. Soil samples will be logged in accordance with the Unified Soil Classification System with descriptions and classifications recorded on field soil boring logs. PTD concentrations and physical observation will also be noted on the logs. PID screening will be conducted using the headspace procedures. Sample material will be transferred to a zip-locked baggie and a headspace reading will be collected from the baggie following a 10 to 15 minute stabilization period- Samole Collection Soil sampling will be conducted at five foot intervals using a split spoon sampler. At each sample interval, the sampler will be driven into undisturbed soil using a 140 pound hammer. Soil samples for TPH analysis will be collected in brass tubes that will be fitted within the split-spoon sampler. After sample retrieval, the tubes will be sealed with Teflon tape and plastic end caps. Samples for analyses of volatile constituents will be collected using the EnCore system (EPA Method 5035). 1;�ay; Depth to groundwater in this area is not known. If ground water is encountered,a water sample will sc be collected from the open boring using a disposable Teflon bailer. Water samples will be ,.. transferred to laboratory provided sample containers, sealed, labeled and stored in a cooler with ice. _ n2 Laboratory Analyses Soil and water samples will be sealed, labeled, placed in a cooler with ice, and submitted to the analytical laboratory under chain-of-custody. The samples will be analyzed by Environmental Science Corporation (ESC). ESC is certified in the State of California to perform the analyses required for these samples. A minimum of 10 soil samples will be submitted (five from each boring). Additional soil samples will be submitted if there are field indications of hydrocarbon impacts and borings are extended beyond the 25 foot depth. The samples will be analyzed for TPH