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GAVIN NEWSOM <br /> 00'� M cnV-vrRNnR <br /> CIA <br /> SE N 'RETAARY�FOR <br /> WaterBoards ENVIRONMENTAL PROTECTION <br /> Central Valley Regional Water Quality Control Board <br /> 3 April 2024 <br /> Andrew Richle <br /> Utilities Superintendent <br /> City of Lodi <br /> 2001 W. Turner Road <br /> Lodi, CA 95242 <br /> Arichle(a)-lodi.gov <br /> ADDITIONAL SOIL VAPOR ASSESSMENT WORK PLAN, CENTRAL PLUME SOURCE <br /> AREA, LODI, SAN JOAQUIN COUNTY <br /> Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff <br /> reviewed the 22 March 2024 Additional Soil Vapor Assessment Work Plan (Work Plan), <br /> submitted by Civil Hydro Tech (CHT) on the behalf of the City of Lodi Public Works Department <br /> (City) for the Central Plume Source Area (CPSA). The City submitted the Work Plan to further <br /> evaluate the extent of residual tetrachloroethylene (PCE) in soil and soil vapor beneath several <br /> commercial properties located in the CPSA. These areas were identified in the 15 January 2024 <br /> Soil Vapor Assessment Report. The Work Plan additionally addresses the comments identified <br /> in the 9 February 2024 Central Valley Water Board staff letter and the 7 March 2024 Board <br /> staff meeting summary. <br /> The CPSA is defined as the area bounded by West Pine Street, South Church Street, Lodi <br /> Avenue, and South Pleasant Avenue to the north, east, south, and west, respectively. Previous <br /> investigations have identified the presence of PCE and other volatile organic compounds <br /> (VOCs) in the soil, soil vapor, indoor air, and groundwater beneath the CPSA from former <br /> historic operations of dry cleaners and a printing press. <br /> The 2023 depth discrete soil vapor sampling results behind the 212 West Pine Street building <br /> identified PCE in soil vapor at concentrations ranging from 25,000 micrograms per meter cubed <br /> (pg/m3) to 2,600,000 pg/m3. These concentrations exceed the PCE commercial soil vapor <br /> environmental screening level (ESL) of 67 fag/m3 (San Franciso Bay Regional Water Quality <br /> Control Board, 2019). The highest PCE concentrations detected in each boring were at depths <br /> of 14 to 15 feet below ground surface (ft-bgs) along the sewer lateral. Additionally, indoor air <br /> samples within the 212 West Pine Street building in Spring 2023 ranged from 5.69 to <br /> 33.6 fag/m3. These concentrations all exceed the commercial indoor air ESL of 2 fag/m3. <br /> The Work Plan proposes to conduct additional assessment of the CPSA in the following three <br /> phases. <br /> MARK BRADFORD, CHAIR I PATRICK PULUPA, ESQ., EXECUTIVE OFFICER <br /> 11020 Sun Center Drive#200, Rancho Cordova, CA 95670 1 www.waterboards.ca.gov/centralvalley <br />