SITE INFORMATION AND CORRESPONDENCE

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New West Station No. 1003 _ 2 _ 1 September 2006• Groundwater monitoring information for Total Mercury and Toxicity are not included in the RWD. This letter is a Notice of Applicability (NOA) for coverage under the General Order For Discharge To Surface Waters Of Groundwater From Cleanup Of Petroleum Fuel Pollution (Order No. 5-00-119). The NOA requires the Discharger to monitor and report on the following constituents: USEPA Standard CWA 303(d) Constituent Reporting Level Method Total Mercury (ng/L) 0.2 ng/L 7470A roundwater' 600/4-91-002 or Toxicity2 latest USEPA (treated groundwater) Method Monitoring to be conducted on groundwater prior to treatment. 2 Three Species Test to be conducted on groundwater after treatment. Monitoring results for Total Mercury in the groundwater must be submitted to our Regional Water Board office no later than 31 October 2006. Monitoring results for Toxicity of the effluent must be conducted after the treatment site is fully functional, and must be submitted to our Regional Water Board office no later than 30 November 2006. General Order coverage for the proposed discharge of treated groundwater is assigned Order No. 5-00-119-52 and National Pollutant Discharge Elimination System (NPDES) No. CAG915001. We do not anticipate any water quality concerns regarding mercury or toxicity for this discharge. However, if monitoring results indicate potential concerns, the appropriateness of coverage under this General Order will be reconsidered. PROJECT DESCRIPTION The proposed site remediation project is located at 6437 West Banner Street in Flag City, near the City of Lodi. The purpose of the project is to pump and treat polluted groundwater caused by leaking underground petroleum fuel storage tanks. The fuel plume is near and moving closer to one of the two municipal supply wells serving the Flag City development. It is imperative that groundwater treatment begins as soon as feasible to protect the municipal water supply well. Groundwater pumped from extraction wells will be treated by an air stripper, and then filtered by five 1000-pound activated carbon modules, two for vapor-phase treatment and three for liquid-phase treatment. The maximum design groundwater extraction rate is 80 gallons per minute (gpm) for this treatment site. However, the actual total pumping rate from the pneumatic pumps inside the extraction wells is approximately 20 gpm. Therefore, approximately 20 gpm of treated groundwater will be discharged to a nearby storm drain that enters the Highline Canal, a tributary of White Slough.