SITE INFORMATION AND CORRESPONDENCE

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Draft Final Investigation Repw, - 3 - OWS 12,410A&508 NCTS, Stockton investigation. Furthermore, the Navy should transfer this contaminated site into the Installation Restoration Program under CERCLA to ensure that monies are available for cleanup. Groundwater AGS states that, "Although a formal RWQCB designation of"non-beneficial use" has not been obtained for the NCTS Stockton facility, the SWBZ at the site is not considered to represent a viable drinking water source based on anticipated low pumping rates and elevated concentrations of total dissolved solids." The following excerpt is from the Board's letter of 1 March 2000, regarding comments on the Draft RI for OU#3, which clarify Board policy found in the Water Quality Control Plan (Basin Plan)for the Sacramento River and San Joaquin River Basins (Fourth Edition). "Unless otherwise designated by the Regional Water Board, all groundwaters in the Region are considered as suitable or potentially suitable, at a minimum, for municipal and domestic water supply(MUN), agricultural supply(AGR), industrial service supply (IND), and industrial process supply(PRO). The criteria for exceptions relative to the Navy's purposes are: ■ "The total dissolved solids (TDS) exceed 3,000 mg/1 (5,000 µmhos/cm, electrical conductivity) and it is not reasonably expected by the Regional Water Board [for the groundwater] to supply a public water system." Current average TDS values equal 2500 mg/1 based on all monitoring wells at the facility. Nevertheless, background water quality data has yet to be developed at the facility. Once background concentrations have been established, TDS and metal concentrations in groundwater may be compared to background to assess potential impacts at specific sites and to evaluate these criteria. Therefore, a special study to evaluate potential remedial actions may be preliminary at this time. • "There is contamination, either by natural processes or by human activity(unrelated to a specific pollution incident), that cannot reasonably be treated for domestic use using either Best Management Practices or best economically achievable treatment practices." The Navy refers to the non-petroleum hydrocarbons that have been detected in soil as motor oil, gasoline, and diesel range organics. We do not concur with the Navy's conclusions that these organics are naturally occurring. Further research and documentation are warranted. ■ "The water source does not provide sufficient water to supply a single well capable of producing an average, sustained yield of 200 gallons per day." The Draft RI report states that 24 hours was required to extract 15 gallons of water from Confining Unit 1 during purging for groundwater sampling. According to the hydrogeologic study, the Shallow Water Bearing Zone (Confining Unit 1), Aquifer ),