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eft%411111%� <br />CALIFORMIA <br />Water Boards <br />9 !-001 I �1 � <br />^• 5}� GAVIN NEWSOM <br />/1 GOVERNOR <br />�7f✓ <br />JARED BLUMENFELD <br />SECRETARY FOP <br />ENVIRONMENTAL PROTECTION <br />Central Valley Regional Water Quality Control Board <br />DECEIVED <br />12 November 2020 <br />NOV 2 3 F"7 <br />1:\\ 11�O\111:\"TAL IIEAU11I <br />Mr. Phil Cohn 1)11"PARtI NILn 1 <br />Cohn Enterprises <br />P.O. Box 900169 <br />San Diego, CA 92190 <br />Work Plan Addendum Review, Pacific Coast Recreation (aka Cohn Property), <br />3755 Mumford Avenue, Stockton, San Joaquin County <br />Dear Mr. Cohn, <br />Central Valley Regional Water Quality Control Board (Central Valley Water Board) <br />staff reviewed the Well Destruction, Well Installation, and Soil Boring Work Plan <br />Addendum 2 (Addendum) dated 14 September 2020, and the First Semi -Annual 2020 <br />Groundwater Monitoring Report (2Q2020 Report), both submitted on your behalf by <br />Apex Envirotech, Inc. (Apex). The Pacific Coast Recreation, also known as the Cohn <br />Property, is located at 3755 Mumford Avenue in Stockton (Site). <br />Existing groundwater monitoring wells are screened between 58.5 and 80 feet below <br />ground surface (ft bgs) or between 83 and 146 ft bgs. Depth to water at this Site has <br />risen approximately 20 feet since wells were installed in 1998. During the second <br />quarter 2020, petroleum hydrocarbons were detected in groundwater samples at up to <br />130,000 micrograms per liter (ug/L) total petroleum hydrocarbons as gasoline (TPH-G), <br />and 16,000 ug/L benzene. <br />There are multiple inconsistencies and lack of specific information on particular aspects <br />of the scope of work presented in the Addendum. Due to these inconsistencies and <br />lack of information, Central Valley Water Board staff do not concur with the Addendum. <br />By 31 January 2021, submit a work plan presenting a clear and consistent scope of <br />work. Notable issues in the Addendum include: <br />In the table on Page 5, Apex states that the screen interval of proposed well <br />MW -15 will be 55 to 65 feet below ground surface (ft bgs), however on Page 8, <br />Apex states the well will be advanced to a total depth of 62 ft bgs with a 10 foot <br />well screen. <br />KARL E. LONGLEY SCD, P.E., CHAIR I PATRICK PULUPA, ESQ., EXECUTIVE OFFICER <br />11020 Sun Center Drive #200, Rancho Cordova, CA 95670 1 www.waterboards.ca.gov/centralvalley <br />