SITE INFORMATION AND CORRESPONDENCE FILE 2

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76/former BP# 11192 page 2 1403 Country Club Blvd, Stockton May 28, 2010 The Plan is the response to the comments noted in the EHD letter of July 9, 2009, and proposes the installation of three monitoring wells - one shallow A-zone monitoring well and one B-zone monitoring well offsite and one D-zone onsite monitoring well. The Plan includes installation of MW-14 (B-zone) and MW-15 (A-zone) approximately 350 to 380 feet offsite to the northeast, beyond Shell's A and B zone wells that are approximately 250 feet northeast of the 76/BP site. Limited 2008 TBA groundwater data collected from these Shell wells indicate that 16 micrograms per liter (ug/1) was present in monitoring well S-6 (A- zone) and 88 ug/I of TBA is in monitoring well S-15 (B-zone). Shell's C-zone well in this area, (S-17), was non-detect for TBA. The EHD has concluded that the proposed placement of monitoring wells MW-14 and MW-15 may be too far to the east and may not provide a sufficient understanding of the lateral extent of TBA-impacted groundwater. Without a groundwater investigation to the north and north- northwest of MW-11 in the C-zone where no data is currently available, the EHD has concluded that the Plan may is not adequate and does not fulfill the EHD requirements to define the lateral extents of the TBA contamination documented in MW-11. An additional C-zone groundwater investigation along Elmwood Avenue, west of Pershing Avenue and along Pershing Avenue at, and north of the intersection of Elmwood and Pershing Avenues, is needed to better characterize the distribution of TBA-impacted groundwater and to select optimum monitoring points. The EHD recommends a series of soil borings with grab groundwater sampling collection be proposed and completed before additional monitoring wells are proposed. After reviewing the most recent groundwater data from the 76/BP and the Shell site across the street, the EHD has determined that the Plan is inadequate as submitted and does not address all of the requirements established by the EHD. The Plan is not approved. [H&S 25296.10(c)(3)]. A revision is needed that addresses the EHD's comments noted above. The revision is due on Geotracker for review by the EHD on July 7, 2010. You may contact Michael Infurna at (209)468-3454 if you have any questions. Michael J. Infurna Jr., REHS Nuel C. Henderson Jr., PG Senior Registered Environmental Health Specialist Engineering Geologist c: Mr. James L. Barton, CVRWQCB Mr. Mark Owens, SWRCB Mr. Brad Shelton, Stantec, 3017 Kilgore Road #100, Rancho Cordova, CA 95670