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STANDARD OPERATING PROCEDURE: SOIL SAMPLING FROM BORINGS HOLLOW-STEM AUGER METHOD Soil samples for chemical analysis are collected in thin-walled brass tubes, 6-inches (in) long by 2-in or 2.5-in outside diameter (OD). Three of these tubes are set inside a 2-in or 2.5-in inside diameter (ID) 18-in long split-barrel sampler. The split-barrel sampler is lowered to the bottom of the hollow stem auger string and driven its entire length either hydraulically or using a 140-pound drop hammer. Thus, the sampler retrieves relatively undisturbed soils below the advancing auger. The sampler is extracted from the borehole and the brass tubes containing the soil samples are removed. Upon removal from the sampler, the selected brass tubes are immediately trimmed and capped with aluminum foil or teflon liners and plastic caps. They are then labeled and refrigerated to 4° C for delivery, under chain-of-custody, to the analytic laboratory. These procedures minimize the potential for cross-contamination and volatilization of volatile organic compounds (VOCs) prior to chemical analysis. One soil sample collected at each sampling interval is analyzed in the field using a photoionization detector (PID). The purpose of this field analysis is to qualitatively determine the presence or absence of hydrocarbons and to establish which soil samples will be analyzed at the laboratory. The soil sample is sealed in a zip-lock plastic bag and placed in the sun to enhance volatilization of the hydrocarbons from the sample. The sample is then measured by the PID and the data recorded at the depth corresponding to the sample point in the field notes. Other soil samples are collected to document the stratigraphy and estimate relative permeability of the subsurface materials. Up to 4.5 feet of continuous sample interval may be recovered without advancing the auger by driving 2.5-in ID, 2-in ID, and 1.5-in ID 18-in long split-barrel samplers in succession ahead of the lead auger. This procedure is known as "telescoping". Density or consistency of soils are measured by blow counts, Torvane or pocket penetrometer. All drilling and sampling equipment is steam-cleaned prior to use at each site and between boreholes to minimize the potential for cross-contamination. Brass tubes and split-barrel samplers are steam-cleaned or washed with Liquinox'detergent and double-rinsed between each use. r r r .r