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ED1.1110110 G. BROIVN <br />Defferi•bil <br />CALIVORRIA <br />Water Boards a IVAITII Ell ROCIFIEUEZ <br />asai • IMIT FON <br />MINIMPIJIONTAL PA10115CRKP4 <br />Central Valley Regional Water Quality Control Board <br />11 September 2015 <br />Sal Hernandez <br />Facilities Management Division <br />County of San Joaquin <br />4520 West Eight Mile Road <br />Stockton, CA 95202 <br />WORK PLAN REVIEW, PUBLIC WORKS, 1810 EAST HAZELTON AVENUE, STOCKTON, <br />SAN JOAQUIN COUNTY, RB #390489 <br />California Regional Water Quality Control Board, Central Valley Region (Central Valley Water <br />Board) staff reviewed the Ozone Remediation Pilot Test Work Plan (Work Plan), dated <br />15 June 2015, and the Fourth Quarter 2014 (Semi-Annual) Groundwater Monitoring Report <br />November 2014 (Monitoring Report) dated 8 June 2015, each document submitted by Condor <br />Earth Technologies, Inc. (Condor) on behalf of the San Joaquin County Facilities Management <br />Division. <br />In the Work Plan, Condor states that an interim remediation consisting of air sparging (AS) and <br />soil vapor extraction (SVE) ran from April 2012 to February 2013. However during the Fourth <br />Quarter of 2014, the Monitoring Report Methyl Tert-Butyl Ether (MTBE) concentrations of up to <br />26,000 micrograms per Liter (pg/L) and Benzene up to 6,400 pg/L show that the Site does not <br />meet the groundwater criteria for closure under the State Water Resources Control Board Low <br />Threat Underground Storage Tank Case Closure Policy. <br />In the Work Plan, Condor proposed installation of eight (8) ozone injection wells in borings <br />advanced to 45 feet below ground surface ( bgs) in a well graded sand zone previously <br />identified in a boring log for MW-1. Depth to water in November 2014 was approximately <br />38' bgs. Each injection well will consist of an 18 inch long, 1.5 inch diameter permeable sparge <br />point installed at approximately 45' bgs, and connected to one inch diameter PVC casing. Wells <br />will be spaced approximately 40 feet apart in two rows of four wells each. An ozone generator <br />with a 3.0 pounds per day capacity will be utilized to inject ozone gas into one well at a time. <br />Condor will optimize treatment time to allow the most polluted areas of groundwater to receive <br />the longest exposure to ozone gas. <br />Groundwater will be monitored for Arsenic, Total Chromium, and Hexavalent Chromium prior to <br />ozone injection start-up, to provide background data, and also semi-annually for 12 to 24 <br />months during ozone injection. Total Petroleum Hydrocarbons as Gasoline, Benzene, Toluene, <br />Ethylbenzene, Xylenes, and MTBE will also continue to be monitored semi-annually in <br />groundwater. Installation and start-up of the ozone treatment system might be delayed by San <br />Joaquin County budgetary shortages and the work may not be implemented until the Fiscal <br />Year 2016/2017 (July 2016 to June 2017). <br />KAPt E LortaLer BcD, P.E., atsula I PAMELA C. Crieericol P.E., BCEE, EICEI:a.nre€ OFFICER <br />1102C Sun Coeur Ortve 1200, Rena° Cordova, CA atle70 Iwww.waterboarde.aa.gorfainralvailay <br />C,,, RECYCLE° PAPER