SITE INFORMATION AND CORRESPONDENCE

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ChevronTexaco - 2 - 26 March 2004 Mountain House Sites #1 and #2 The Addendum proposes the following: • Advance 22 additional borings and collect soil and groundwater samples at Site# 1 in the area of Mountain House Creek to be altered. The total number of borings will be 32, including the 10 originally proposed. • Two additional borings will be placed at Site #2 to collect soil and groundwater samples, slightly northwest of the proposed bridge. The total number of borings will be 12, including the 10 originally proposed. I have the following comments: • ChevronTexaco and Regional Board staff, to expedite the characterization process during the course of the investigation work, should collectively review the results of analyses and held observations to determine any need for additional borings, and/or sampling locations. • Representative groundwater samples from a portion of the borings need to be collected and analyzed for general minerals and nitrate. I concur with the 12 March 2004 Workplan Addendum for the additional borings at Mountain House Sites # 1 and# 2,provided the comments discussed above are addressed. Proposed Streambed Alteration and Bridge Construction Based on the imminent bridge construction and streambed alterations currently proposed, I believe that it is appropriate to address the potential environmental/permitting issues that may be encountered during construction activities. The conditions are similar to those seen during the ChevronTexaco and the City of Tracy's recent Westside Channel Outfall System project where petroleum hydrocarbon-impacted soil and groundwater associated with the OVP was encountered. ChevronTexaco continues to be the responsible party for soil and groundwater issues relating to impacts from the OVP such as could be encountered during these projects. Mountain House Creek flows southwest to northeast, generally separating Sites# 1 and #2, and crossing beneath Byron Road and the UPRR tracks. According to the Addendum, following completion of the proposed borings, the streambed will be deepened and widened, in part to accommodate the proposed Byron Road bridge construction project, but also as part of the Mountain House Creek Restoration Project. The existing bridge and UPRR crossings will be replaced by a new approximately 80 by 240 foot bridge over the creek. The additional drilling work described above is to investigate those portions of the property that would be affected by the bridge construction and streambed alteration.