SITE INFORMATION AND CORRESPONDENCE

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C. Scott Mansholt - Chevrce - 2 - 0 20 June 2008 Mountain House Site #4 samples from boring MH4-6. Additionally, polynuclear aromatic hydrocarbon (PAH) constituents coupled with the TPH compounds, suggests the presence of refined petroleum product(s) possibly leaking from the adjacent active pipeline(s) not associated with the OVPITAOC. • We concur that a request for a No Further Action Required determination can be submitted in accordance with Central Valley Regional Water Quality Control Board's 16 April 2004 update to Appendix A of the Tri-Regional Board Staff Recommendations for Preliminary Investigation and Evaluation of Underground Tank Sites - No Further Action Required (NFAR). It should follow Sections 6.516.6 - NFAR for Cases Exceeding Water Quality Objectives and Documentation. • SAIC needs to conduct a technological feasibility evaluation in accordance with State Water Resources Control Board Resolution No. 92-49, addressing the viability of implementing remedial options for affected soil and groundwater to remain at the site. • According to SAIC, the development of shallow groundwater for future residential or commercial with the installation of new water supply wells is unlikely, since groundwater is of poor quality, and within fine-grained soils that typically yield low flow wells. • A site specific Soil Management Plan (SMP) should be prepared and submitted with the request for No Further Action Required determination. The identification of a possible refined product pipeline leak will be referred to the Sacramento Regional Water Board office. By 1 September 2008, submit documentation that Mountain House Community Services District has been notified regarding the soil and groundwater conditions associated with Mountain House Development Site #4 and that the SMP was provided. The notice needs to reflect that land use within the Byron Road ROW is limited and if land use conditions change, the health risk evaluation may need to be revised. By 15 September 2008, please provide the No Further Action Required documentation and the SMP. Our comments discussed above should be addressed in the accompanying documentation.