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Mr. Richard Powell - 2 - 1 March 2002 <br /> NCTS, Stockton <br /> Specific comments: <br /> 1. Page 16. Section 4.3.2.2. Third paragraph, second sentence. Replace "blow"with <br /> "below". <br /> 2. Page 22. Section 5.2.2. For enhanced NINA,we suggest that a pilot test be conducted to <br /> determine the design parameters, including the airflow/pressure for low-flow sparge well, <br /> area of well influence, and the number of wells for full-scale implementation. A workplan <br /> for the pilot test should be submitted for our review and approval. Also, a design report <br /> should be submitted for our review and approval prior to system installation. System <br /> startup and monitoring plans are also required. <br /> 3. Page 23. Section 5.2.2. Fifth paragraph. Itis proposed that the evaluation of MNA <br /> parameters will be conducted for a minimum of one quarter. We suggest a minimum of <br /> four quarters of MNA parameter monitoring to gather adequate data for evaluation. <br /> However, as stated in our general comments,we do not believe that MNA is a viable <br /> option for this site,based on the chemical data already gathered,which does not <br /> demonstrate any noticeable contaminant reduction. <br /> 4. Table 4. The contaminant concentrations are listed as milligrams per liter. The response <br /> to comments state that the concentrations should be micrograms per liter. Please revise <br /> the reporting units for concentrations. <br /> 5. Table 4. It would be useful to indicate the sampling dates. We assume the sampling <br /> concentration information is presented in chronological order, ending with the most <br /> recent data available. <br /> 6. Table 4. Sample numbers 176917-3GW5, and 176917-4GW5. The gasoline <br /> cdticentrations are shown as less than 50 micrograms/liter although elevated <br /> concentrations (upto 54 milligrams/liter)were reported for previous sampling events. <br /> Please confirm the concentrations shown for these samples. <br /> Please submit a workplan for the next phase of work. We will be glad to further discuss these comments <br /> and other any other cleanup options, if proposed, for this site. Please contact me at(916) 255-3078 or <br /> TalankS(a),rb5s.swrcb.ca.gov if you have any questions regarding this matter. <br /> Sincerely, <br /> Sudhakar Talanki, P.E. <br /> Associate Water Resources Control Engineer <br /> cc: Mr. Brad Beeman,NCTS, Stockton <br /> Mr. Terry Escarda,Department of Toxic Substances Control <br /> Ms. Regina Donohoe, California Department of Fish and Game <br /> Mr. Jay Jahangiri, Port of Stockton <br /> Mr. Walter Kim, Tetra Tech EM Inc. <br /> Ms. Dot Lofstrom, San Joaquin County Environmental Health Department <br />