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Adam Wolfe - 2 - 14 October 2021 <br /> Department of Corrections and Rehabilitation <br /> controllers set to collect a sample over 24 hours. Canisters will be placed on the floor <br /> adjacent to crawl space access locations, and a short run of Teflon tubing and PVC pipe <br /> will be connected to the canister and placed in the crawl space. An outdoor ambient air <br /> sample will be collected contemporaneously with the crawl space samples. <br /> Indoor air samples will be collected at two locations in the Laundry/Print Shop following <br /> the completion of crawlspace sampling but within 48 hours of that sampling. Indoor air <br /> samples will be collected into laboratory-supplied 6-liter canisters fitted with flow <br /> controllers set to collect the sample over 24 hours. <br /> Following sample collection, crawl space, indoor air and ambient air samples will be <br /> submitted for off-site analysis of VOCs by EPA Method TO-15 SIM. <br /> Soil Gas Sampling <br /> Permanent soil gas wells will be installed at 10 locations in the exterior areas near the <br /> Laundry/Print Shop and around the grease trap previously identified as a potential VOC <br /> source in the passive soil vapor survey. Soil gas wells are proposed to be constructed <br /> by first advancing a boring to a maximum depth of 20 feet below ground surface (bgs) at <br /> each location using a direct push drill rig, with continuous coring for lithologic description <br /> at the first location and soil samples collected every 5 feet at subsequent borings. A <br /> deeper soil gas probe will be placed in a one-foot-thick sand pack at a depth of <br /> approximately 15 feet bgs. One foot of dry bentonite will be placed on top of the sand <br /> pack, followed by bentonite grout to approximately 5.5 feet bgs. A shallow soil gas <br /> probe will be placed in a one-foot-thick sand pack at approximately 5 feet bgs, followed <br /> by a one-foot-thick layer of dry bentonite and bentonite grout to the surface. Each soil <br /> gas probe will be connected to the surface by Nylaflow or Teflon tubing. <br /> Following installation of soil gas wells, they will be allowed to equilibrate for at least 48 <br /> hours prior to sampling. Samples will be collected into laboratory-supplied 1-liter <br /> canisters following a shut-in test and purging. Gaseous 2-propanol or isobutane will be <br /> used as leak test compounds, and will be included in the analyte list. A duplicate soil <br /> gas sample will be collected. Soil gas samples will be submitted for analysis by EPA <br /> Method TO-15. <br /> Comments <br /> Central Valley Water Board staff has the following comments on the SI Work Plan: <br /> 1. Section 4.2 and 4.3 note that duplicate samples will not be collected from indoor <br /> air and crawl space areas. In the experience of Central Valley Water Board staff, <br /> the flow controllers used for sample collection have a relatively high rate of <br /> failure, which can result in a sample being collected far more quickly than <br /> intended. Due to the scheduling complications associated with sampling inside <br /> the correctional facility, Staff recommends preparing an additional canister to be <br /> used as a backup in case a crawl space or indoor air sample fails to perform as <br />