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.A <br /> EotnuHo G. BROwu JR. <br /> ,,�I�; DOVERNOR <br /> C A L I I O R H I A MATTHEw RODRIQUEZ <br /> ARY E S <br /> Water Boards SECRETARY FOR <br /> CR TARP TAL PROTECTION <br /> Central Valley Regional Water Quality Control Board <br /> 23 May 2017 <br /> Sharon Evans Chris Panaitescu <br /> Phillips 66 Company Thrifty Oil Company <br /> 1380 San Pablo Avenue 13116 Imperial Highway <br /> Rodeo, CA 94572 Santa Fe Springs, CA 90670 <br /> BP #172 (THRIFTY), 7647 PACIFIC AVENUE, STOCKTON, SAN JOAQUIN COUNTY, <br /> CASE# 390652 <br /> Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff <br /> reviewed the Work Plan for Additional Soil and Groundwater Assessment (Work Plan) dated <br /> 8 May 2017, submitted on your behalf by ATC Group Services Inc. (ATC) for the BP #172 <br /> property located at 7647 Pacific Avenue in Stockton (Site). <br /> In order to assess the lateral and vertical extent of hydrocarbon impacts to groundwater, in the <br /> Work Plan, ATC proposes installing two (2) monitoring wells in the vicinity of existing well MW- <br /> 23. ATC proposes installing one well with a screened interval from 30 to 45 feet below ground <br /> surface (bgs), and one well with a screen interval from 75 to 80 feet bgs. Additionally, in order <br /> to properly assess the nature of the release, ATC proposes advancing a soil boring in the <br /> vicinity of the former waste oil tank to a depth of approximately 20 feet bgs. <br /> ATC proposes collecting soil samples from the well bores at 5 foot intervals, and submit at least <br /> two (2) soil samples from each well for analysis, to include total petroleum hydrocarbons as <br /> gasoline (TPHg), benzene, toluene, ethylbenzene, xylenes (collectively BTEX), methyl tert butyl <br /> ether (MTBE), and additional fuel oxygenates and lead scavengers. In the soil boring in the <br /> vicinity of the former waste oil tank, ATC proposes collecting soil samples at 4 foot intervals, <br /> and submit at least one (1) sample for analysis, to include TPHg, TPH as diesel (TPHd), total oil <br /> and grease (TOG), volatile organic compounds (VOCs), semi-VOCs (SVOCs), polycyclic <br /> aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and Title 22 metals. <br /> Samples submitted for analysis will be determined by field screening with a photo-ionization <br /> detector (PID). Additionally, in order to provide background concentrations, at least one soil <br /> sample from the well bores will be analyzed for Title 22 metals. <br /> Central Valley Water Board staff concurs with the scope of work as proposed in the Work Plan <br /> with the following comments: <br /> 1. ATC proposes advancing the former waste oil tank soil boring through the center of the <br /> former waste oil tank location. Please make sure that collected samples are taken from <br /> native soil to avoid analyzing backfill material. <br /> KARL E. LONOLEY SCD, P.E.,CHAIR I PAMELA C. CREEDON P.E., BCEE, EXECUTIVE OFFICER <br /> 11020 Sun Center Drive 0200,Rancho Cordova,CA 95670 1 www.waterboards.ca.gov/centralvalley <br /> C j RECYCLED PAPER <br />