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Site Investigation Work Plan <br /> Carousel Cleaners, Sacramento, California Sampling and Analysis <br /> 4.0 Sampling and Analysis <br /> This section describes the planned methods of the field investigation. <br /> 4.1.1 Field Activities <br /> Field activities will include IA/CS and SG sampling from soil gas wells. Soil gas well installation <br /> locations and sampling locations are shown in Figure 5. <br /> 4.2 Crawl Space Soil Gas Sampling <br /> Crawl space SG sampling will be used to assess whether vapors are present beneath the building near the <br /> area of SG-2 and beneath the IA locations,to help assess potential indoor air issues,preferential pathways <br /> of accumulated vapors, and the impact that crawl space vapors may have on the indoor air quality of the <br /> Laundry/Print Shop. <br /> 4.2.1 Crawl Space Sample Collection <br /> Crawl space sample collection will be performed as follows: <br /> • A laboratory-supplied flow controller will be connected to a laboratory-supplied, 6-liter certified <br /> clean canister. The flow controllers will be set for an approximately 24-hour sampling period. <br /> The ambient air(outdoor background) sample also will be collected over the same period, at an <br /> upgradient location. The canisters will be evacuated by the laboratory to more than 25 inches of <br /> mercury gauge pressure,before sampling. <br /> • For each sample location,the 6-liter certified clean canisters will be placed at the entrance of the <br /> opening to the crawl space area. <br /> • Teflon/high-density polyethylene tubing will be attached to a polyvinyl chloride pipe and placed <br /> beneath the proposed indoor air sampling locations in the crawl space. <br /> • Crawl space samples will be taken before but within 48 hours of indoor air sampling. <br /> • The valve on the canisters will be opened to begin sample collection. The initial vacuum pressure <br /> indicated by the canister pressure gauge will be recorded on the chain-of-custody form. <br /> • After approximately 24 hours,when the vacuum gauge pressure is between 1 and 10 inches of <br /> mercury,the valve on the canister will be closed to end the sample collection. The final vacuum <br /> pressure indicated by the canister pressure gauge will be recorded on the chain-of-custody form. <br /> • Duplicate crawl space air samples will not be collected. <br /> • On completion of sampling, all crawl space sampling equipment will be removed. <br /> 4-1 <br />