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the samples are collected. A five-foot deep soil gas probe will be installed proximate to the location of the sub-slab soil gas sample that has the greatest detection of PCE and/or TCE. The deeper probe would be installed as described in Section 5.3. 5.3 Proposed Site Boundary, Sewer Lateral, and Petroleum Hydrocarbon Release Soil Gas Assessment Proposed soil gas samples will be collected from four 5-foot deep soil gas probes along the southern boundary of the subject property. The four soil gas probes to be installed as depicted shown on Figure 7. The alignment of the approximately 660-foot long sanitary sewer lateral will be identified by a private utility locator as noted in Section 5.1.2. The six proposed 5-foot deep soil gas probe locations along the sewer lateral alignment are shown on Figure 8. The depth of the sewer lateral within the subsect property will be assessed by measuring the depth using the sewer cleanout vaults using a tape measure prior to implementing the field work. The 5-foot deep soil gas samples proposed for two locations associated with the petroleum hydrocarbon release are shown on Figure 9. The proposed three cumulative soil gas assessments will be conducted in general accordance with the July 2015 DTSC Advisory and will consist of soil gas samples from probes installed with a direct push Geoprobe. The soil gas samples will be analyzed for VOCs by an on-site mobile laboratory. The methods to be used for installing soil gas samples from shallow soil are described below. 5.3.1 Proposed Shallow Soil Gas Sample Probe Installation Methods The soil gas probes will be installed with dual-tube direct push equipment using a Geoprobe. Specifically, the probes will be constructed as the inner tube is being withdrawn such that the disturbance to the surrounding soil is minimized. A porous sample tip with a barbed fitting was attached to the end of 1/4- inch diameter Teflon tubing. New or unused sampling tubing will be used for each probe location. The tubing and sample tip will placed approximately five feet bgs (approximately five feet above the water table) using a narrow diameter length of polyvinyl chloride (PVC) pipe (downhole rod) which was kept in place until a one-foot thick sand pack (from 5 to 4 feet bgs) is slowly poured into the borehole as the outer tube was withdrawn. Six inches of dry bentonite transition seal followed by a neat cement grout will be introduced into the boring as the outer tube was withdrawn. This technique will allow a soil gas probe to be purged and sampled approximately two hours following the final installation of the probe. The soil gas probes will be secured and completed to prevent infiltration of water or ambient air into the subsurface and to prevent accidental damage or vandalism. The tubing will be marked at the surface to identify the probe location and depth. A gas-tight valve or fitting for capping will be affixed to the sampling tube. To allow for the subsurface to equilibrate to representative conditions, each probe will not purged or sampled for at least two hours following probe installation. Sampling and Analysis Plan Tracy Corners Shopping Center 3225 North Tracy Boulevard Tracy,California 95376 Partner Project Number SM14-129814 Docket Number HAS-VCA 14/15-108 August 15,2016 Page 15