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Richard Powell - 3 — <br /> Drainage <br /> 3 — <br /> Drainage Channel Confirmation Report <br /> NCTS, Stockton <br /> The report states that, "Given that the soils in the drainage channels are native clays, and that 4,4- <br /> DDD, 4,4'-DDD, and 4,4'-DDT are hydrophobic, DDT total detected in the native clays of the <br /> drainage channel would most likely remain heavily sorbed onto the clays and therefore, be less <br /> likely to leach than the soils used to determine the leachable limit. In this regard, the Navy should <br /> determine the actual leachability of a representative sampling of the most contaminated sample <br /> sites. Two options are recommended for calculating the soluble fraction of pesticides in soil. There <br /> is the standard DI WET method and the USEPA recommended Sediment Quality Guidelines for <br /> Non-Ionic Organic Pollutants (see attached). <br /> 3. Ecological Receptors Analysis. The Navy should receive acceptance of their analysis by the <br /> California Department of Fish and Game or the Department of Toxics Substances Control's <br /> toxicology department with regards to the ecological risk assessment. <br /> 4. Table 2. Metals Detected in Soil. Please include the depth of the samples on the table. Results <br /> of samples DC 13, -14, and—15 are not listed on the table. Please include the results in a revised <br /> table. <br /> The Navy should respond to these comments in a revised drainage channel investigation plan to <br /> determine whether pesticides remaining in sediment/soil pose a threat to surface and groundwater <br /> quality. <br /> If you have any questions, please contact me at (916) 255-3078 or schwabk a,rb5s.swrcb.ca.Qov. <br /> KIM A. SCHWAB <br /> Associate Engineering Geologist <br /> Enclosure <br /> cc: Francesca D'Onofrio, DTSC, Region 1, Sacramento <br /> Eric Hong,DTSC, Region 1, Sacramento <br /> Charlie Huang, CA Department of Fish and Game, Sacramento <br /> San Joaquin County Environmental Health Department, Stockton <br /> Dana Sakamoto, Environmental Program Department Manager,Naval Facilities Command <br /> (SWDIV), 1220 Pacific Highway, San Diego, CA 92132 <br /> Brad Beeman,NCTS, Stockton <br /> Jay Jahangiri, Port of Stockton <br /> Kas:NCTS DrainChanConf <br />