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27 September 2024 AdvancedGeo <br /> p An Employee-Owned Company <br /> Project No. 23-7573 _ <br /> Page 5of6 '�"""I <br /> labeled with the initial and final vacuum to ensure that the regulator was functioning <br /> properly. <br /> All air samples will be analyzed by a ELAP-certified laboratory for volatile organic <br /> compounds (VOCs) in accordance with EPA Method TO-15. <br /> Laboratory reports for air sample analyses, testing methods, laboratory quality <br /> assurance/quality control (QA/QC) reports and sample chain of custody documentation <br /> will be presented in a report with findings and recommendations. The lowest possible <br /> method detection limits will be achieved, which will allow comparison with established <br /> guidelines. Analytical data will be evaluated and compared to the January 2019 San <br /> Francisco Bay Regional Water Quality Control Board Environmental Screening Levels <br /> (ESLs) for a commercial setting. <br /> 4.2.2. Crawl Space Air Sampling Method <br /> All crawl space samples will be collected in six-liter Summa canisters using passive <br /> integrated sampling procedures. Each canister's initial vacuum will be measured and <br /> recorded to ensure the initial vacuum is greater than 25 inches of mercury (in hg). The <br /> sampling inlet on the canisters will be connected to a mass flow controller containing a <br /> particulate filter and calibrated to 3.8-milliliters/minute (ml/min) so that indoor and ambient <br /> air samples are passively collected over an approximate 24-hour period. <br /> Crawl space samples will be collected by placing the container on the outside of the <br /> residential structures and then running tubing to the center of the building structure. The <br /> tubing will be placed within 3-4/inch PVC stabilizer piping in order to deploy it beneath the <br /> center of each structure. Once the air sampling canisters are placed and positioned <br /> properly, the Summa canister valves will be opened to begin air sample collection. <br /> Following approximately 24-hours of sample time, the indoor air and ambient air sample <br /> containers will be retrieved, closed, and sealed. The sample containers will then be <br /> labeled with the initial and final vacuum to ensure that the regulator was functioning <br /> properly. <br /> All air samples will be analyzed by a California Environmental Lab Accreditation Program <br /> (CELAP)-certified laboratory for volatile organic compounds (VOCs) in accordance with <br /> EPA Method TO-15. <br /> Laboratory reports for air sample analyses, testing methods, laboratory quality <br /> assurance/quality control (QA/QC) reports and sample chain of custody documentation <br /> will be presented in a report with findings and recommendations. The lowest possible <br /> method detection limits will be achieved, which will allow comparison with established <br /> guidelines. Analytical data will be evaluated and compared to the January 2019 San <br />