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0 <br /> California Regional Water Quality Control Board <br /> �iEAI_lfl <br /> Central Valley Region E <br /> Robert Schneider,Chair <br /> Winston H.Hickox Gray Davis <br /> Secretaryfor Sacramento Main Office ` <br /> 17 Governor <br /> Environmental Internet Address: http://w .sw b.ca.gov/- gcb5 <br /> Protection 3443 Routier Road,Suite A,Sacramento,California 95827-3003 <br /> Phone(916)255.3000•FAX(916)255-3015 <br /> 12 September 2003 <br /> Mr.Nick Nickerson Mr.Phil Delk Mr. Jay Allen <br /> Unocal DBG/AMG Deputy General Counsel Stone Brothers Management Company <br /> 8788 Elk Grove Blvd. Montgomery Wards 1024 W.Robinhood Dr. <br /> Building 3, Suite 15 535 West Chicago Avenue Stockton, CA 95207 <br /> Elk Grove, CA 95624 Chicago,IL 60671 <br /> REVIEW QUARTERLYMONITORING REPORT,FORMER UNOCAL STATION #5098 AT <br /> 5606 PACIFICA VENUE,AND FORMER MONTGOMERY WARDS AUTO SERVICE AT <br /> 5400 PA CIFICA VENUE,STOC%TON, CLEANUP AND ABATEMENT ORDER NO. 5-00-707, <br /> SANJOAQUIN COUNTY, <br /> I reviewed the 23 July 2003 Updated Site Conceptual Model And Second Quarter 2003 Monitoring And <br /> Remediation Report(Report)submitted by Environmental Audit,Incorporated(EAI) on behalf of Unocal. <br /> Unocal is the primary responsible party for this commingled plume site. The following are my comments on the <br /> Report. <br /> 1. The Report states"EAI proposes to conduct field readings from individual wells and obtain soil vapor <br /> samples in the mid-July(2003). Based on the result of this testing, a decision will be made whether to <br /> operate the oxidizer. CAO No. 5-00-707 specifically states"Any interruption in the operation of the <br /> cleanup system(s), other than for scheduled maintenance, without prior written approval of the Executive <br /> Officer, is a violation of this Order". Failure to comply with CAO requirements may result in a <br /> Notice of Violation or civil penalties for the Responsible Parties. <br /> 2. The Report states "Sparging of Units C and D will not be conducted at this time. It is EAI's opinion that <br /> with time oxygen injected into Units A and B will diffuse downward to remediate deeper zones." There <br /> is no corroborating evidence supplied to support this opinion. Therefore, I do not concur with this <br /> change in operation of the remediation system. As stated above, any change to the CAO No. 5-00-707 <br /> requires prior written approval from the Executive Officer. Changes to remediation without written <br /> approval of the Executive Officer are violations of CAO No. 5-00-707. If you have stopped Sparging <br /> Units C and D,then you are in violation of CAO No. 5-00-707. <br /> 3. In the 8 February 2002 letter(Letter),Regional Board staff requested that the updated Site Conceptual <br /> Model (SCM) contain a minimum of two hydrostratigraphic cross-sections, one across the former Unocal <br /> site and one across the former Montgomery Wards site. The SCM cross-sections were to be constructed <br /> through the contaminant source areas and parallel to the current groundwater flow direction. The new <br /> hydrostratigraphic units(A through D)were to be labeled, and the lateral and vertical extent of <br /> groundwater contamination were to be included on the cross-sections for the First Quarter of 2002 <br /> groundwater monitoring event. The SCM was to be reviewed and updated quarterly in future reports. <br /> Though it was not specifically stated,the Letter requested a series of cross-sections to represent changes <br /> in vertical and lateral distribution of contaminants through time. The SCM provides pictorial <br /> representations of contamination in three dimensions,plan view and cross-sections,to aid with the <br /> decision-making processes in the remediation. The Report does not include these cross-sections. All <br /> future reports shall include Letter-required site cross-sections,to be updated quarterly,within the SCM. <br /> California Environmental Protection Agency <br /> 0 Recycled Paper <br />