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4.3 No existing water supply wells, deeper aquifers, surface waters or other receptors are threatened by pollutants remaining in the aquifer. The Regional Board,issued a document entitled "A-Compilation of Water Quality Goals," dated March 1998, which;describes applicable water quality goals related to various organic and inorganic substances in groundwater. Diesellfuei, also described as diesel oil, has no listed goals i for California or Federal Maximum Contaminant Levels (MCLs), California Public Health Goals in Drinking Water, California State Action Levels, and for many other categories. Diesel fuel is listed in the "Other Taste and Odor Thresholds" category at a concentration of 100.ug/L, and in the USEPA"Drinking Water Health Advisories or Suggested No-Adverse-Response Levels (SNARLS) for toxicity other than cancer risk" category at a concentration of 100 ug/L for aJ0-day exposure. Diesel fuel has been detected in the groundwater.in the vicinity of the former UST at a maximum concentration of 150,ug/L. Although this slightly:exceeds the 100 ug/L guidelines described above, this shallow groundwater is not currently used as drinking water and is not readily accessible for public contact. 4.4 The total pollutant- mass remaining in the ground water is decreasing at predicted rates and neither creates, nor threatens to create, a risk to human health and safety or future beneficial use(s) of the aquifer. The groundwater impacted by diesel fuel is confined to an area in the vicinity of the former UST with lateral dimensions of approximately 50 feet long by 35 feet wide. The limits of this release are depicted in Figure 5. ;,Samples of groundwater collected on August 24, 1999 during a Geoprobe investigation, found that diesel fuel concentrations attenuated to 58 ug/L at a distance of 35 feet south of the center of the former UST and to 97 ug/L at a distance of 20 feet east of the center of the former UST. Both of these concentrations are less than the "Other Taste and Odor Thresholds"and SNARLs listed above. With the source of the release removed and the most highly contaminated g y soil excavated and removed from the site, it is expected that the diesel fuel in the soil and ` groundwater will passively biodegrade over time: Four quarters of groundwater:monitoring have confirmed that very little migration of the impacted groundwater has occurred. Since this aquifer is not currently used fordomestic use and since"-no'.`near-term.;,use of the aquifer is anticipated, ATC recommends that passive bioremediation of the soil and groundwater is suitable for this low risk groundwater site. L 5.0 NO FURTHER ACTION CHECKLIST The Regional Board document entitled Recommendations For Preliminary Investigation And Evaluation Of Underground Tank Site,No Further Action Request," contains a Table 1- "Checklist ' of Required Data For.No Further Action Requests At Underground Tank Sites." A copy of this checklist is presented in Appendix A. The checklist represents the minimum information required for a request for no further action. The 16 points of the checklist,' with explanations', are presented below: i A ` ATC Associates Inc 5 Project No,53.75123 OOGI I L°-