WORK PLANS - Laserfiche WebLink

Home Browse Search

(MM PEA Work Plan Martin Metals Finishing Inc. (Former) Stockton, California Groundwater is not expected to be encountered at the target boring depth, and therefore no groundwater samples are planned. 4.2.5 Shallow Soil Sampling CDIM will collect a total of 15 near-surface, shallow soil samples from five transects across Mormon Slough: three samples approximately 200 feet upstream, three samples approximately 100 feet upstream, three samples adjacent to, three samples approximately 100 feet downstream, and three samples approximately 200 feet downstream of the outfall. Samples will be collected between 0 and 6 inches below ground surface and 1 to 1.5 ft bgs to assess the gradient of shallow soil impacts from historical releases to Mormon Slough. Sample locations and depths may be adjusted in the field depending on the observations of field personnel. Shallow soil samples will be collected using a hand auger, shovel, or stainless-steel trowel. Soil will be transferred directly from the sampling tool into a pre-cleaned sample container(e.g., glass jar). 4.2.6 Subslab Soil Vapor Sampling Five subslab soil vapor samples will be collected using a Vapor Pin TM technique following procedures in the DTSC Advisory-Active Soil Gas Investigations(DTSC,2015). Proposed subslab soil vapor sampling locations, shown on Figure 6, were selected due to the historical locations of MMF operations. For each location, CDIM will perform a helium shroud test for real-time leak detection by placing the shroud over the sampling train (including sample container). CDIM will fill the shroud with helium and then use a helium detector12 to test air from the sample port. If the detector reads no helium, it successfully demonstrates a closed system at each location. CDIM will then connect a 1-liter, individually certified, summa canister to the sample port to collect the vapor sample over an approximately five-minute duration. CDIM will record starting and ending pressure on each summa canister and on air sampling data sheets. 4.2.7 Dual-Nested Soil Vapor Wells CDIM will contract with an environmental drilling company to install up to nine temporary dual-nested soil vapor wells with two depth intervals (5 and 15 ft bgs) at the Site. Proposed soil vapor well locations, shown on Figures 5 and 6, were selected to evaluate potential subsurface impacts related to Martin Metal Finishing operations, including: • Five soil vapor wells in locations of historic operations and adjacent to the storm drain trench within the MMF building, and • Four soil vapor wells just north of the MMF building and adjacent to historic operations to assist with delineating any potential COPCs identified in soil vapor beneath the building. Once installed, dual nested wells will be installed using the same procedure as the subslab soil vapor samples. 12 The helium detector will be calibrated and maintained in accordance with the manufacturer's recommendations. CDIM—Fairgrounds Industrial Park Page 13