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JPI Tracy Work Plan 2605 S MacArthur Drive, Tracy, CA 96376 Site History I The site is located on the northwest corner of the intersection of South MacArthur Drive and Valpico Road in Tracy, California. Historically, the property was used for a gravel pit operation, orchards, railroad spurs, labor houses, and more recently a residential building, a vacant field, and a water well shed. In June of 2019, ENGEO performed environmental soil sampling. They reported concentrations of OCP's, CAM-17 metals, total petroleum hydrocarbons, and PAHs below the applicable Regional Water Quality Control Board (RWQCB) Environmental Screening Levels (ESLs) using the residential land use screening levels. Purpose and Procedures Leighton and Associates, Inc. (Leighton) plans to advance soil gas probes at eight locations (2 nested at each location) at the property located at 2605 S MacArthur Drive, Tracy in California. A soil gas survey will be performed to evaluate site conditions for the presence of VOCs. The soil gas survey will be performed in general conformance with the California Environmental Protection Agency—Department of Toxic Substances Control (DTSC) and California Regional Water Quality Control Board — Los Angeles and San Francisco Region's(LARWQCB and SFRWQCB)Advisory—Active Soil Gas Investigations, July 2015. Soil gas samples will be obtained from soil gas probes installed at depths of 5 and 15 feet bgs (conditions permitting) at eight locations. The soil gas probes will consist of inert'/- inch nylaflow tubing (or equivalent)fitted with a porous airstone at the terminus, which will be set within one foot of sand with one foot of dry bentonite above extending to the surface. The surface end of the probe will be fitted with a gas-tight luerlock fitting to prevent infiltration of water or air. Typical soil gas probe installation details are provided on the attached Figure. Soil gas probes will be allowed to equilibrate for a minimum of 2 hours prior to sampling. After sampling is complete, an attempt will be made to pull the plastic tubing out of the ground by hand. The boreholes will then be overdrilled to 20 feet using the direct-push rods. The rods will be removed from the ground and the borehole will be filled with cement grout by slowly pouring from the surface. The borehole will be grouted to within one foot of ground surface. The remaining one foot will be filled with native soil. TEG-Northern California, Inc. (C-57#706568)will be conducting the field work overseen by Leighton. All work will be overseen by a California Professional Geologist. Disposal Soil and groundwater waste is not anticipated during the installation or removal of the soil gas probes.