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.` California Regional Water Quality Control Board <br /> Central Valley Region <br /> Winston H.Hickox Robert Schneider,Chair Gray Davis <br /> Secretaryfor Sacramento Main Office Governor <br /> Environmental Intemet Address: http://www.swrcb.ca.gov/—mgcb5 <br /> Protection 3443 Routier Road,Suite A,Sacramento,Califomia 95827-3003 <br /> Phone(916)255-3000•FAX(916)255-3164 <br /> 2 June 2003 <br /> 3'Jind <br /> Mr. Mike Lescisin #lld�N <br /> Diamond Walnut Growers Inc. <br /> 1050 South Diamond Street <br /> Stockton, California 95201 <br /> REVIEW OF WORK PLAN, DIAMOND WALNUT GROWERS, STOCKTON PLANT, <br /> SAN JOAQUIN COUNTY <br /> We have reviewed the 8 May 2003 Summary Report of Additional Subsurface Investigation, <br /> Deep Well Installation (Well Installation Report) and the 8 May 2003 Second Quarter 2003 <br /> Monitoring Report(QMR) submitted by ATC Associates Inc. (ATC) on behalf of Diamond <br /> Walnut Growers Inc. (DWG) for its Stockton Plant. The QMR contains the groundwater <br /> monitoring results for samples collected on 22 April 2003 and reports that monitoring well <br /> MW-3 continues to contain the highest pollutant concentration with 3,800 µg/1 of hexavalent <br /> chromium. The remaining seven shallow monitoring wells contained hexavalent chromium <br /> between 2 and 75 gg/l. <br /> The Well Installation Report contains well detail information for MW-9, which was installed on <br /> 30 April 2003 and is screened between about 103 and 113 feet below ground surface. A <br /> groundwater sample collected from MW-9 on 5 May 2003 contained hexavalent chromium at <br /> about 5 µg/1 and total chromium at about 8 µg/1. These sample results indicate that the deeper <br /> groundwater at MW-9 is not polluted above background levels. Monitoring and Reporting <br /> Program No. R5-2002-0821 (MRP)requires that any new wells be added to the monitoring <br /> program, and ATC recommends continued quarterly monitoring of MW-9. Thus, MW-9 shall be <br /> sampled quarterly according to the MRP. <br /> The Well Installation Report also reports the video log information for the on-site facility supply <br /> well. This well has a one-foot diameter steel casing, extends to a depth of about 108 feet below <br /> the top of the casing and is perforated from about 67 feet below the top of the casing to the <br /> bottom of the well. ATC concludes that the facility well is screened over more than one water- <br /> bearing zone, states there are no plans to use the well and recommends that it be properly <br /> destroyed. We concur with this recommendation, and DWG should proceed to accomplish this <br /> work. <br /> California Environmental Protection Agency <br /> Recycled Paper <br /> The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. For a list of <br /> simple ways you can reduce demand and cut your energy costs,see our Web-site at httpV/www.swrcb.ca.gov/Mgcb5 <br />