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CRA STANDARD FIELD PROCEDURES FOR SOIL BORINGS This document describes Conestoga-Rovers&Associates' standard field methods for drilling and sampling soil borings. These procedures are designed to comply with Federal, State and local regulatory guidelines. Specific field procedures are summarized below. 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 Professional Geologist (PG) 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 product saturation percentage, • Observed odor and/or discoloration,and • Other significant observations(i.e.cementation,presence of marker horizons,mineralogy). Soil Boring and Sampling Soil borings are typically drilled using hollow-stem augers or hydraulic push technologies. At least one and one half ft of the soil column is collected for every five ft of drilled depth. Additional soil samples are collected near the water table and at lithologic changes. Samples are collected using lined split-barrel or equivalent samplers driven into undisturbed sediments beyond the bottom of the borehole. The vertical location of each soil sample is determined by measuring the distance from the middle of the soil sample tube to the end of the drive rod used to advance the split barrel sampler. All sample depths use the ground surface immediately adjacent to the boring as a datum. The horizontal location of each boring is measured in the field from an onsite permanent reference using a measuring wheel or tape measure. Drilling and sampling equipment is steam-cleaned 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. 1 of 2