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eft%sewiII110 <br />CALI POIIN IA <br />Water Boards <br />Central Valley Regional Water Quality Control Board <br />25 July 2019 <br />Forrest McFarland <br />Ninyo & Moore, Inc. <br />2020 Challenger Drive, Suite 103 <br />Alameda, CA 94501 <br />nGAVIN I.f IYEWSOM <br />GOVERNOR <br />REVIEW OF SITE ASSESSMENT WORK PLAN, STOCKTON COURTHOUSE, <br />180 EAST WEBER AVENUE, STOCKTON, SAN JOAQUIN COUNTY <br />JARED BLUMENFELD <br />SECRETARY FOR <br />ENVIRONMENTAL PROTECTION <br />Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff <br />reviewed the 23 May 2019 Site Assessment Work Plan prepared by Ninyo & Moore on <br />behalf of the Judicial Council of California (JCC) for the Stockton Courthouse located at <br />180 East Weber Avenue in Stockton (Site). The site assessment is in response to the <br />removal and soil excavation of two underground storage tanks (USTs) and one area -of - <br />concern (AOC) conducted during Site redevelopment in 2014. Approximately 260 cubic <br />yards of impacted soil and 4,000 gallons of groundwater were removed and disposed <br />offsite during these activities. Concentrations of total petroleum hydrocarbons (TPH) as <br />motor oil (TPHmo), as diesel (TPHd), and gasoline (TPHg), volatile organic compounds <br />(VOCs), and polycyclic aromatic hydrocarbons (PAHs) were detected in confirmation <br />soil and groundwater samples. The lateral extent of impact to soil and groundwater was <br />not determined at that time. <br />Ninyo & Moore proposes to conduct the following scope -of -work: <br />• Drill seven borings to groundwater, estimated at 17 to 30 feet bgs. Collect two <br />discreet soil samples from each boring and analyze for TPHmo and TPHd by <br />United States Environmental Protection Agency (USEPA) Method 8015M, TPHg <br />and VOCs by USEPA Method 8260. See attachment for boring locations. <br />• Collect grab -groundwater samples from each of the seven borings and analyze <br />for TPHmo and TPHd by USEPA Method 8015M, TPHg and VOCs by USEPA <br />Method 82608. <br />The Central Valley Water Board staff concur with Ninyo & Moore's Site Assessment <br />Work Plan for the Site. Please notify staff of the field schedule at least one week in <br />advance of the start of various field activities. A report of findings should be submitted <br />to this office by 15 October 2019. <br />KARL E. LONGLEY SCD, P.E., CHAIR I PATRICK PULUPA, EGO., EXECUTIVE OFFICER <br />11020 Sun Center Drive #200, Rancho Cordova, CA 95670 I www.waterboards.ca.gov/centralvalley <br />RECYCLED PAPER <br />