Laserfiche WebLink
Own HERWww <br /> =`a�Water Boards "'-_�• <br /> Central Valley Regional Water Quality Control Board <br /> 8 November 2021 <br /> Chevron Environmental Management Company <br /> do Sioblew Pritchard <br /> Arcedis U.S., Inc. <br /> 630 Plaza Ones, Suite 200 <br /> Highlands Ranch, CO 80129 <br /> REVIEW OF CONFIRMATION SOIL VAPOR SAMPLING REPORT, 401 NORTH SAN <br /> JOSE STREET, STOCRTON, SAN JOAQUIN COUNTY <br /> Central Valley Regional Water Quality Control Boats (Central Valley Water Board) staff <br /> nefewed the 22 October 2021 Confirmation Soil Vapor Sampling Report (SV Sampling <br /> Report) prepared by Arcadis, U.S. Inc. (Arcar is) on behaff of Chevron Environmental <br /> Management Company (CEMC) for the property at 401 NOme San Jose Street in <br /> Stockton (Site). The SV Sampling Report was submitted pumu mm our 29 "1 2021 <br /> letter that concerned with the 14 April 2021 Remed2l Acaum RePod and Soil Vapor <br /> Work Plan (Work Plan). <br /> The purpose of the sampling was to assess the concentrations of petroleum <br /> hydrocarbon constituents in soil vapor following the call excavation activities conducted <br /> earlier this year and cempam them with applicable screening levels, including chose in <br /> the Underground Storage Tank Low-Threat Closure Policy (LTCP) and San Francisco <br /> Bay Regional Water Quality Control Board Environmental Screening Levels (ESLs). <br /> Prior to excavation activities, soil vapor near and within the excavation area contained <br /> maximum concentrations of Mal petroleum hydrocarbons as gasoline (TPHg) and <br /> benzene of 110,000,O00 micrograms per cubic meter (ughn') and 29,000 uglm', <br /> respectively. Congrmagon soil samples following excavation were below cleanup goals <br /> wide the exception of one side wall sample next to a utility candor that contained TPHg <br /> at 120 milligrams per kilogram (mg/kg) and TPH as diesel (TPHd) at 55 mgrkg. These <br /> concentrations exceed the cleanup goal in the LTCP of 100 mglkg for the Intel of TPHg <br /> and TPHd. <br /> Arcadis installed three permanent soil vapor probes (SV-T through SV-9) on <br /> 15 June 2021 at the locations shown on Figure 3 of the SV Sampling Report. Ancadis <br /> collected sell vapor samples from each probe and submitted them for laboratory <br /> analysis in accordance with the Work Plan. Sol vapor probe SV-7 was rewampled on <br /> 15 September 2021 due to an exceedancs of the leak check helium analysis in the <br /> sample from 15 June 2021 . Benzene was detected in each of the three soil vapor <br /> ous E. LanaLEY nor, P.E. ale <br />