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January21, 2026 <br /> Zachary Walton, Partner <br /> Proposal for Supplemental Environmental Support Services at 1010 Industrial <br /> Drive, Stockton, California <br /> Scope of Work <br /> Task 1 - Pre-Field Activities <br /> Terraphase will perform the following pre-field activities needed to support the supplemental <br /> investigation: <br /> • Preparatory site visit to identify and mark groundwater monitoring well and soil gas well installation <br /> locations; <br /> • Mark the investigation locations in white paint, as required by law, for Underground Service Alert of <br /> Northern California (USA North) notification; <br /> • Clear the groundwater monitoring well and soil gas probe installation locations by a private utility <br /> subcontractor. <br /> • Schedule sub-contractors (private utility locator, drilling contractor, analytical laboratory, and <br /> investigation-derived waste disposal contractor); <br /> • Obtain drilling permit from San Joaquin County Environmental Health Department; <br /> • Update the site-specific health and safety plan (HASP); and <br /> • Notify underground service alert (USA) a minimum of 48 hours before commencement of intrusive <br /> activities. <br /> Task 2 - Field Investigation <br /> Groundwater Monitoring Well and Soil Gas Well Installation <br /> Groundwater monitoring well and soil gas probe installation locations will be cleared to five feet below <br /> ground surface (bgs) with a hand-auger prior to drilling operations. Drilling will be performed by a State <br /> of California-licensed (C-57) drilling subcontractor under the oversight of a Terraphase Professional <br /> Geologist. <br /> The groundwater monitoring well installation will include advancement of borings to 30.5 feet bgs by <br /> direct push technology drilling methods for collection of soil samples for logging and laboratory analysis. <br /> Soil will be continuously cored to facilitate completion of lithologic boring logs and screened for the <br /> presence of volatile organic compounds (VOCs) with a photoionization detector(PID). Seven soil <br /> samples will be collected at approximate depths of 1-1.5, 3-3.5, 5-5.5, 10-10.5, 15-15.5, 20-20.5, and 30- <br /> 30.5 feet bgs and be submitted to a California-certified analytical laboratory under chain of custody <br /> procedures.Soil samples will be analyzed for: <br /> • pH using EPA Method 9045C; <br /> • VOCs using EPA Method 826013; <br /> • Nitrogen as Nitrate using EPA Method E300; <br /> • Nitrate as Nitrate using EPA Method E300; and <br /> • Chloride using EPA Method E300. <br /> 4 Page 2 of 7 <br />