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Mr. Jeff Whitworth • - 2 - • 2 October 2006 <br /> included with the report. Monitoring and Reporting Program (MRP) No. R5-2005-0810 <br /> requires that semiannual reports include groundwater elevation contour maps and <br /> isoconcentration contour maps for each contaminant of interest instead of all data plotted on <br /> one figure. Additionally, the site vicinity map provided in the report depicts the site location <br /> incorrectly showing the former Tosco facility to the east as the Shell site. <br /> The groundwater extraction system extracts water from one well, MW-1, at a rate of <br /> approximately 0.2 gallon per minute (gpm). Extracted water is temporarily stored in an onsite <br /> tank for transportation and recycling at Shell's Martinez Refinery. Shell states that the system <br /> will continue to be operated while MNA results are being evaluated as the preferred remedy. <br /> There was no evaluation of the effectiveness of the current remedial approach other than a <br /> tabulation of contaminant mass removal data. <br /> Regional Water Board staff requests that the 2006 First Semiannual Report be revised and <br /> resubmitted to this office based on the deficiencies stated above. The revised report should <br /> include discussions or tabulations of groundwater contaminant concentrations trends at <br /> individual wells along with a more thorough description of plume stability. Separate <br /> groundwater isoconcentration contour maps should be provided for TPH as gasoline, TPH as <br /> diesel, benzene, and MTBE as well as groundwater elevation. The site vicinity map should be <br /> revised to show the correct site location. The revised semiannual report is due to this office by <br /> 27 October 2006. <br /> If you have any questions regarding this letter, you may contact me at (916) 464-4719 or <br /> mclardy@waterboards.ca.gov. <br /> IM4A 4, <br /> Mark W. Clardy, P.G. <br /> Engineering Geologist <br /> Private Sites Cleanup Unit <br /> cc: Margaret Lagorio, San Joaquin County Environmental Health Department, Stockton <br /> Rita Koehnen, Port of Stockton, Stockton <br /> Ron Orallo, Shell OPUS, Stockton <br /> Mark O'Brien, ERS, Walnut Creek <br /> Yuanyuan Hui, Earthtech, San Jose <br /> Thomas Kosel, ConocoPhillips, Sacramento <br /> MWC/W\slit dod'AustinStaff\Mark\Shell StocktoM9-1-06 Shell Stockton 1st semiannual.doc <br />