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r: CAMBRIA Objectives Soil samples are collected to characterize subsurface lithology, assess whether the soils exhibit obvious hydrocarbon or other compound vapor odor or staining, estimate ground water depth and quality and to submit samples for chemical analysis. Soil Classification/Logging All soil samples are classified according to the Unified Soil Classification System by a trained geologist or engineer working under the supervision of a California Registered Geologist(RG)or a Certified Engineering Geologist(CEG). The following soil properties are noted for each soil sample: • Principal and secondary grain size category (i.e., sand, silt, clay or gravel) • Approximate percentage of each grain size category, • Color, • Approximate water or separate-phase hydrocarbon saturation percentage, • Observed odor and/or discoloration, • Other significant observations(i.e.,cementation,presence of marker horizons,mineralogy),and • Estimated permeability. Soil Sampling Soil samples are collected from borings driven using hydraulic push technologies. A minimum of one and one half ft of the soil column is collected for every five ft of drilled depth. Additional soil samples can be collected near the water table and at lithologic changes. Samples are collected using samplers lined with polyethylene or brass tubes driven into undisturbed sediments at the bottom of the borehole. The ground surface immediately adjacent to the boring is used as a datum to measure sample depth. The horizontal location of each boring is measured in the field relative to a permanent on-site reference using a measuring wheel or tape measure. Drilling and sampling equipment is steam-cleaned or washed prior to drilling and between borings to prevent cross-contamination. Sampling equipment is washed between samples with trisodium phosphate or an equivalent EPA-approved detergent. Sample Storage, Handling and Transport Sampling tubes chosen for analysis are trimmed of excess soil and capped with Teflon'tape and plastic end caps. Soil samples are labeled and stored at or below 4°C on either crushed or dry ice,depending upon local regulations. Samples are transported under chain-of-custody to a State-certified analytic laboratory. Field Screening After a soil sample has been collected, soil from the remaining tubing is placed inside a sealed plastic bag and set aside to allow hydrocarbons to volatilize from the soil. After ten to fifteen minutes, a portable photoionization detector measures volatile hydrocarbon vapor concentrations in the bag's headspace, extracting the vapor through a slit in the plastic bag. The measurements are used along with the field observations, odors,stratigraphy and ground water depth to select soil samples for analysis. i