SITE INFORMATION AND CORRESPONDENCE

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Mr. James Mills and Ms. Kare't"Giacopuzzi - 2 - 23 April 2002 Westrec Properties The Report recommends that (1) the socks continue to be used for free product removal from MW-3, (2) groundwater monitoring be continued as stated in the Regional Water Quality Control Board Monitoring and Reporting Program No. 5-00-824 (MRP), and (3) tert-butanol (TBA) and ethanol be removed from the MRP, since they have not been detected in groundwater during 2001. The Letter modifies the Report's recommendations, as follows: • Use of the adsorbent socks should be discontinued at MW-3. MW-3 would continue to be monitored for free product, and the adsorbent socks would be replaced if free product returns. • The MRP should be revised to change the groundwater sampling schedule from quarterly to annual, • And groundwater sampling should be discontinued in monitoring wells MW-1 and MW-5. The Letter also states that the application of the Regional Water Quality Control Board's "most conservative water quality goals" is unwarranted, since the "impacted groundwater exists in a shallow, low-quality aquifer which is unlikely to qualify as beneficial use under the existing Basin Plan", and that historic data show that natural attenuation and degradation is occurring, with no measurable impact downgradient of the site. General Comments: 1. We disagree with the Letter statement that the aquifer is not appropriate for beneficial uses. The Fourth Addition of the Water Quality Control Plan (Basin Plan)for the Sacramento River and San Joaquin River Basins states that "Unless otherwise designated by the Regional Board, all ground waters 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 Basin Plan further states "In making any exemptions to the beneficial use designation of MUN (municipal and domestic supply, including drinking water sources), the Regional Board will apply the exceptions listed in Resolution 88-63." State Water Resources Control Board Resolution 88-63 Sources of Drinking Water(Policy) states that"All surface and ground waters of the State are considered suitable, or potentially suitable, for municipal or domestic water supply...". There are exceptions to the Policy, for TDS, yield, geothermal, and inability to use Best Management Practices or best economically achievable treatment to cleanup groundwater, that do not apply to this aquifer. The Basin Plan states that State Water Resources Control Board Resolution No. 92-49 directs the Regional Water Boards to ensure that dischargers are required to cleanup and to abate the effect of discharges. The cleanup and abatement will promote the attainment of background water quality, or the highest water quality, which is reasonable if background water quality levels cannot be restored. Any cleanup less stringent than background water quality shall be consistent with maximum benefit to the people of the state and not unreasonably affect the present and anticipated beneficial uses of such water. 2. We cannot concur with the Letter statement that no measurable downgradient impact is present, due to the lack of data downgradient of the monitoring network at the site. To support this statement, additional characterization of contaminants in groundwater downgradient of the site is necessary.