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t ` California Regional Water Quality Control Board Central Valley Region Robert Schneider,Chair Winston H. Hickoa Cray Davis Secretaryfor Sacramento Alain Office Governor Environmental Internet Address: http:/h�-NNw.swrcb.ca.gov/rwgcb5 Protection 3443 Routicr Road.Suite A,Sacramento,California 95827-3003 Phone(916)255-3000•FAX(916)255-3015 9 February 2001 Richard Powell Naval Facilities Engineering Command, West Environmental Compliance Mail Code 6423 900 Commodore Drive San Bruno, CA 94066-2402 DRAFT LETTER REPORT REGARDING CONFIRMATION SAMPLING IN UNLINED DRAINAGE CHANNEL SYSTEM WET REACHES(REPORT), NAVAL COMPUTER AND TELECOMMUNICA TION STA TION SAN DIEGO DETACHMENT, STOCKTON The Central Valley Regional Water Quality Control Board (Board) is pleased to have received the subject document, dated 14 December 2000, as prepared by Tetra Tech EM, Inc. In August 1999, the Navy conducted dredging of the unlined drainage channel wet reaches and removed the sediment down to the native clay based on the Board's request. This request was based on the fact that contaminated sediments were found in drainage channels associated with parcels that were proposed for transfer during Phase I; specifically parcels 37 and 45. We refer you to our letter of 8 October 1998 where the Navy was requested to provide additional evaluation due to the presence of non-point source contaminants in sediment in the drainage channels. The Board did not concur with the transfer of these parcels at that time and requested the Navy provide further evaluation of the remaining contaminated sediments. We maintain that further analysis of contaminated sediments be performed in order to determine whether sediments/soil pose a threat to surface and groundwater quality based on results of the confirmation samples taken from the wet reaches of the open drainage channel. Our specific comments on the Report follow: 1. Drainage Channel Description and Background. Briefly, the Report states that pesticides, insecticides, and rodenticides were applied per the manufacturer's directions. Telephone interviews with people who worked at NCTS, Stockton and witnessed the application of pesticides and herbicides depict a different picture. Based on information provided by the Sacramento-Yolo Mosquito Abatement District, DDT was mixed with diesel, as a carrier/solvent, and used for mosquito abatement in the mid 1950s through the mid 1960s, possibly into the early 1970s. Motor oil was used for weed control and not necessarily mosquito abatement because of its high viscosity. Because portions of the island have been used for agricultural purposes, it is suspected that surplus pesticides and used motor oil/diesel/gasoline were spread over the area indiscriminately for disposal,which was acceptable at the time. Used petroleum hydrocarbons drained from Naval or agricultural machinery would account for the detection of PCBs and metals California Environmental Protection Agency pia Recycled Paper The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. For a list of simple ways you can reduce demand and cut your energy costs,see our Web-site at http://www.swrcb.ca.gov/rwgcb5