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Californiagional Water Quality Con*] Board <br /> 4 Central Valley Region r;� <br /> Linda S.Adams IREC VED Arnold <br /> Secremryfor Sacramento Main Office ``���� Schwarzenegger <br /> Environmental 11020 Sun Center Drive#200,Rancho Cordova,California 95Yf76 12 1 2006 Governor <br /> Protection Phone(916)464-3291 •FAX(916)4644645 <br /> http://www.waterboads.ca.gov/ entralval]4t,JVfPONN'Et4T HEALTH <br /> PERVTiSERVICES <br /> 19 December 2006 <br /> Jeff Baker <br /> Tesoro Companies, Inc. <br /> 3450 South 344th Way, Suite 100 <br /> Auburn, WA 98001-5931 <br /> REVIEW OF RESPONSE LETTER AND THIRD QUARTER 2006 GROUNDWATER <br /> MONITORING REPORT, STOCKTON TERMINALS TECHNICAL COMMITTEE FACILITIES, <br /> PORT OF STOCKTON, STOCKTON, SAN JOAQUIN COUNTY <br /> Staff of the Regional Water Quality Control Board, Central Valley Region (Regional Water <br /> Board) has reviewed the 12 October 2006 Response to RWQCB Letter Dated September 8, <br /> 2006 (Response Letter) and the 1 November 2006 Third Quarter 2006 Groundwater <br /> Monitoring, and Remediation Summary Report (Third QMR) submitted by SECOR <br /> International, Inc. (SECOR) on behalf of the Stockton Terminals Technical Committee (STTC). <br /> STTC represents three bulk fuel facilities composed of ARCO Products Company, Tesoro <br /> Petroleum Company, and Time Oil Company at the Port of Stockton (site). The Response <br /> Letter responds to review comments by Regional Water Board staff on the three previous <br /> groundwater monitoring reports and the Third QMR describes groundwater monitoring and <br /> remediation activities performed during the third quarter 2006. <br /> The Response Letter clarifies several issues discussed in the Regional Water Board's letter <br /> dated 8 September 2006 (Letter). The East and-West ozone injection systems (OS) began <br /> operation in September 2004 and November 2004, respectively; therefore full-scale operation <br /> began during the fourth quarter 2004 instead of the third quarter 2004 as stated in the Letter. <br /> Groundwater chemical concentration trends were to be evaluated over nine months following <br /> an anticipated one-year spike period. Based on this schedule, the evaluation would occur <br /> from the first quarter 2006 through the third quarter 2006. If an increase of more than one <br /> order of magnitude above historical concentrations were observed at remedial observation <br /> wells for three consecutive quarters, then the contingency plan in STTC's 27 June 2003 letter <br /> would be implemented. Although groundwater benzene concentrations at remedial <br /> observation well PS/WC-1 M increased from 14 micrograms per liter (ug/L) in the fourth quarter <br /> 2005 to 1,600 ug/L in the second quarter 2006, the concentration decreased to 3.0 ug/L in the <br /> third quarter 2006 indicating that the threshold criteria for contingency plan implementation <br /> has not been exceeded. <br /> SECOR also clarified in the Response Letter that a second condition for contingency plan <br /> implementation is that if the concentration threshold criterion has been exceeded, then <br /> existing natural attenuation parameter data would be used to evaluate whether natural <br /> California Environmental Protection Agency <br /> 0 Recycled Paper <br />