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.� California Regional Water Quality Control Board <br /> . Central Valley Region <br /> - Robert Schneider,Chair <br /> Terry Tamminen � � <br /> Arnold <br /> Secretary for Sacramento Main Office unegger <br /> Environmental Internet Address httpJlwww swreb ca govlrwgcb5 Goovernvers or <br /> Protection 11020 Sun Center Dnve#200 Rancho Cordova,CA 95670-6114 <br /> Phone(916)464-3291 <br /> 4 October 2004 <br /> Mr Ken Hillard .�F� OCT 0 5 2H') <br /> 7-Eleven Corporation <br /> P O Box 711 <br /> Dallas,TX 975221-0711 BY:____,_ _______--.._ <br /> FIELD TEST PROGRAM FOR EVALUATION OF OXIDATION CAPACITY OF GROUNDWATER, <br /> 7-ELEVEN STORE#14177,2 725 COUNRTY CLUB BOULEVARD,STOCKTON,SANJOAQUIN COUNTY, <br /> I reviewed two documents,dated 22 July 2004 and 31 August 2004,titled Field Test Program for Evaluation of <br /> Oxidation Capacity of Groundwater(Reports), and submitted by SECOR International Inc (SECOR) on behalf <br /> of 7-Eleven Corporation The 22 July 2004 Report provides a Workplan for a Pilot Study utilizing batch oxygen <br /> injection into a new 2"well (1=1)from a compressed gas bottle into the aquifer,to enhance degradation of <br /> petroleum hydrocarbons The 31 August 2004 Report uses analytical results of dissolved metals and general <br /> minerals from a groundwater sample from monitoring well MW-1 (located 5 feet from I-1),to produce theoretical <br /> calculations in a geochemistry evaluation Based on the evaluation, SECOR concluded that a Bench Scale Study <br /> is not necessary prior to the Field Pilot Study <br /> The Workplan is tentatively approved as written with the following conditions <br /> n SECOR must collect and analyze one representative soil sample from the oxygen injection target zone at <br /> the site Soil analyses will repeat the previously groundwater analytical suite,so that the revised <br /> geochemicai evaluation(GE)report may compare the results of the soil and groundwater,and thoroughly <br /> discuss the expected worst-case scenario reactions,i e, 100%conversion of constituents of concern into <br /> contaminants,reporting the chemical reactions to molar concentrations <br /> o If metals of concern(Cr6+, etc)are not detected,or gcneral minerals(SO4, etc) are not present at levels <br /> favorable for adverse reactions in saturated soil,then you may proceed to the Pilot Study after final <br /> approval of the GE report Note that all Pilot Study analytical detection limits must be sufficiently low to <br /> test the theories proposed in the Reports and provide comparisons to Water Quality Objectives in the GE <br /> report You will continue to monitor groundwater during the Pilot Study for the know petroleum <br /> hydrocarbon contaminants and general parameters(dissolved oxygen,pH,specific conductance, <br /> temperature) <br /> o If metals of concern(Cr6+,etc)are detected,or minerals of concern(SO4i etc )are detected at potentially <br /> harmful levels,then a Bench Scale Test(BST)will be conducted to show which contaminant(s)are <br /> produced, and whether the produced contaminant(s)will persist after termination of oxygen injection, <br /> using the graphed slope of the declining contaminant(s)concentrations versus time to calculate a decay <br /> rate(time to revert to non-detect) If a contaminant(s) is produced and persistent,provide that <br /> information in a report for my evaluation If contammant(s)produced are not persistent,provide a BST <br /> Report containing modifications to the Pilot Study monitoring program,specifically,the frequency of <br /> analyses needed to confirm contaminant decay rates as calculated from BST analytical evidence <br /> Cal fornra Environmental Protection Agency <br /> %I Recycled Paper <br />