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California Regional Water Quality Control Board <br /> Central Valley Region <br /> RobertSchneider Chair <br /> ynold Schv<'arzenegge <br /> Terry Tamminen F G6vernor <br /> Secretary for Sacramento Main eb.ca. _ <br /> Environmental Internet Address: #20http0 wwcho Cordova, <br /> A 9565 3v <br /> 11020 Sun Center Drive#200 Rancho Cordova,CA 95670-6114 <br /> Protection Phone(916)464-3291 <br /> J <br /> 'ry <br /> 13 May 2004 3 <br /> Mr.Bob Hopkins <br /> Mr.Phil Delk Mr. Jay Allen v <br /> Union Oil Company of California Deputy General Counsel Stone Brothers Managemen ompatl}G <br /> Montgomery Wards 1024 W. Robinhood Dr. <br /> 276 Tank Fane Road. <br /> P.O.Box 1069 535 West Chicago Avenue Stockton, CA 95207 <br /> San Luis Obispo, CA 93406 Chicago,IL 60671 <br /> REPORT OCAL sTA TION #5098 A <br /> 6 PACIFIC REVIEWAV, CLEANUP AND ABA ENUE,AND FORMER MONTGOMNT ERY WARDS AUTO SERVICE NO. 5-00-707,FORMER AT T <br /> 5400 PACIFIC AVENUE, <br /> STOCKTON,SANJOAQUIN COUNTY, <br /> I reviewed the 30 April 2004 Updated Site Conceptual Model, Monitoring And Remediation Status Report, First <br /> Quarter 2004(Report) submitted by ENSR International(ENSR)on behalf of Unocal. The Report recommends <br /> continuing pulsed operation of the Air Sparging(AS) system, and continuing quarterly monitoring. <br /> Since the SVE system was shut down,monitoring data and Figure 7 (enclosed) from the Report,with the <br /> monitoring data and the three Figure Ts from the three prior quarterly reports(enclosed), show that the B-zone <br /> benzene plume has expanded to the south(laterally) and also to the east(downgradient),beyond the monitoring <br /> well network. The benzene plume in the B-zone has more than doubled in size since last year. During the 3d <br /> quarter 2003,the B-zone benzene plume appears to be migrating laterally to the south. During the 4`h quarter <br /> 2003,the same plume appears to be migrating downgradient to the east. The Report also states that the AS <br /> system operated only 528 hours during the 4" quarter 2003, and that ENSR will troubleshoot the AS system to <br /> reduce downtime. <br /> Cleanup and Abatement Order No. 5-00-707, Order No. 15 states: If groundwater monitoring indicates that the <br /> groundwater plume has migrated beyond laterally or vertically defined limits during the quarter, the quarterly <br /> report shall include a workplan and schedule, with work to begin within 30 days of a report submittal, to define <br /> the new plume limits and cease plume movement. The Report does not include the Order-specified work plan or <br /> schedule to implement the work plan. The work plan is now overdue. If the work plan is not received by <br /> 15 June 2004,then we may recommend that formal enforcement action be taken. <br /> You may call me at(916)464-4615 for questions or additional information. <br /> AMES L.BARYON,R.G. <br /> Engineering Geologist <br /> cc: Mr.Mark Owens,UST Cleanup Fund, SWRCB, Sacramento <br /> Mr.Mike Inf nna, San Joaquin County Environmental Health Division, Stockton <br /> Ms. Jill Tracy, Esq.,UNOCAL,Brea <br /> Mr. Ben Henningburg,ENSR International, Sacramento <br /> California Environmental Protection Agency <br /> cl*Recycled Paper �� <br />