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Mr. Marshall Cloud <br /> March 22, 2007 <br /> Page 2 <br /> 2.) Page ES-3, section ES.2.2.7, second sentence; In the final report, please <br /> identify the wells with chromium concentrations above baseline and any wells <br /> showing significantly increasing trends. <br /> 3.) Page ES-4, section ES.4.2, first sentence; Since the 2006 annual progress <br /> report is only evaluating data from two quarters instead of the usual four <br /> quarters, DTSC is skeptical of the claim that DDJC-Sharpe's extraction and <br /> treatment systems are capturing 96% of the plumes in the A, B, and C zones. <br /> Additionally, DDJC-Sharpe has recently discovered a continuing source of <br /> volatile organic compounds (VOCs) (Site P-5A) in ground water responsible <br /> for producing TCE concentrations of 1,350 micrograms per litre (Ng/L) in <br /> ground water and soil gas concentrations in excess of 1,600 parts per billion <br /> volume. Finally, with the submittal of a draft cone-penetrometer test <br /> investigation work plan whose purpose is to further delineate the horizontal <br /> and vertical extent of the Central Area and North Balloon VOC plumes in. <br /> Spring 2007, DTSC believes it is premature to quantify the plume capture <br /> when additional characterization data is still being collected or planning to be <br /> collected. <br /> 4.) Page 2-1, section 2.2.2, second sentence; The report should identify that <br /> summer temperatures in the San Joaquin Valley can range from 60 degrees <br /> to over 100 degrees Fahrenheit. Please amend the temperature range in this <br /> section to reflect the fact that summer temperatures can exceed <br /> 100 degrees. <br /> 5.) Page 2-6, section 2.5.3.10, first sentence; Previous review from DTSC's <br /> Geologic Services Unit stated the peak ground water elevations occur <br /> approximately 10-12 months after peak precipitation months. Please review <br /> the data to verify that the proposed ground water elevations do indeed occur <br /> within 2-3 months after periods of peak precipitation. <br /> 6.) Page 3-2, section 3.2.1.4, fourth sentence; The sentence should clearly state <br /> that Site P-5A is a continuing source of VOCs to ground water. This fact is <br /> supported by the recent Site P-5A Investigation Results Report identifying <br /> TCE concentrations in ground water at approximately 1,350 parts per billion <br /> at the site. <br />