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Californil. !gional Water Quality Co*l Board , <br /> Central Valley Region -t <br /> Linda S. Adams Arnold <br /> �,-,reran bw Sacramento Main Office Schwarzenegger <br /> F.nvn-onmenral 11020 Sun Ccntcr Dave#200.Rancho Cordoxa.Cahl'ornia 95670.6114 Governor <br /> Protvrr1oi Phone(916)464-3291 •FAX(916)464-4645 <br /> httPJhvww.waterhoards.ca.gov/centralxal lex((_1E1__ <br /> Il�n <br /> 4 December 2006 V �D <br /> Ms. Kerry Heckman DEC 0 8 2006 <br /> Connell Tire ENVIRONMENT HEALTH <br /> 2211 North Wilson Way PERMIT/SERVICES <br /> Stockton, California 95205 <br /> DOCUMENT REVIEWS, FORMER RIVER CITY PETROLEUM & FORMER CONNELL <br /> MOTOR LIFT TRUCK, 2.211 NORTH WILSON WAY, STOCKTON, SAN JOAQUIN COUNTY, <br /> MONITORING AND REPORTING PROGRAM NO. R5-2005-0827 <br /> I reviewed the 16 November 2006 Ozone Injection Bench Scale Pilot Study Report (Study <br /> Report) and the 21 November 2006 Quarterly Report — Third Quarter (3Q2006 Report), <br /> submitted on your behalf by Advanced GeoEnviron mental, Inc. (AGE) to the Regional Water <br /> Quality Control Board — Central Valley Region (Regional Board). The Study Report provides <br /> the results of an ozone injection/air sparging Bench Scale test, as proposed in an AGE email <br /> on 3 July 2006 and approved by Regional Board staff letter of 10 July 2006, conducted prior to <br /> a pilot study of a groundwater remediation technology for a corrective action. The 302006 <br /> Report provides the Site (Figure 1) quarterly groundwater monitoring sample results of forty- <br /> eight monitoring wells (Figure 2) and the interim soil vapor extraction (SVE) system's volume <br /> of contaminants removed, and also provides new recommendations for the groundwater <br /> cleanup. <br /> The Study Report provided data that show that ozone injection and air sparging effectively <br /> reduced groundwater pollution to concentrations below Water Quality Goals. While air <br /> sparging required additional time to reduce the pollution concentrations when compared to <br /> ozone injection, ozone created toxic byproducts Hexavalent Chromium (Cr +) and Bromate <br /> (BrO3 ) at concentrations that did not naturally reduce below Water Quality Goals at three <br /> weeks after stopping the ozone injection. Due to the recalcitrance of the ozone injection <br /> byproduct compounds Cr 6+ and BrO3-, which have adverse (non-carcinogenic and <br /> carcinogenic) effects on human health, and the depth of the proposed remediation; Regional <br /> Board staff and AGE discussed the Study Report results in a phone conversation on <br /> 21 November 2006 and agreed to implement an air sparging pilot study in lieu of ozone <br /> injection. The 3Q2006 Report also recommends that the air sparging be implemented. An air <br /> sparging addendum to the approved workplan for the proposed (and subsequently rejected) <br /> ozone pilot study is due on 31 December 2006. <br /> The 3Q2006 Report shows that petroleum hydrocarbon levels continue to persist as a bimodal <br /> dissolved pollution groundwater plume (Plume). The Plume consists of gasoline and diesel- <br /> range components in soil and groundwater emanating from the Underground Storage Tanks <br /> (USTs) and Dispensers source area (Source) east of the Site building and extending down into <br /> California Environmental Protection Agency <br /> �a Recycled Paper <br />