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J. TERRA PACIFic GROUP 201 North Civic Drive,Suite 135,Walnut Creek,California 94596 Environmental Engineering,Consulting,and Construction Phone(925)951.6000•Fax(925)951.6005 December 2, 2014 PGE-1066 Mr.John Yoakum San Joaquin County -Environmental Health Department 600 East Main Street Stockton CA 95202-3029 RE: Soil Gas Well Destruction Notification Permits SR0068418 and SR0068908 Former Lodi Manufactured Gas Plant 712 South Sacramento Street Lodi,California Dear Mr.Yoakum: Terra Pacific Group (TPG) is submitting this letter to document the soil gas well destructions conducted at the former Lodi manufactured gas plant (MGP) site (Site) located at 712 South Sacramento Street,Lodi,California (Figures 1 and 2). During November 2013 and February through April 2014, a total of 21 soil gas wells were destroyed under permits SR0068418 and SR0068908 (attached for reference). The soil gas wells were properly destroyed in accordance with the California Well Standards Bulletin 74-90 and the decommissioning guidelines presented in the April 2012 Advisory — Active Soil Gas Investigation (ASGI) document published jointly by the California Environmental Protection Agency (Cal/EPA) Department of Toxic Substances Control (DTSC), Regional Water Quality Control Board, Los Angeles Region (RWQCB-LA), and Regional Water Quality Control Board, San Francisco Region (RWQCB-SF). This work was completed in advance of or during the planned soil remedial excavation activities at the Site. The destructions of soil gas wells SG-1, SG-3, SG-4, SG-5, SG-6, SG-10 and SG-11 (Figure 2) were conducted in November 2013 by National EWP, a licensed C-57 contractor. Each soil gas well was destroyed by over-drilling with 6-inch diameter augers to the total well depth and grouting by tremie pipe through the augers with neat cement up to the surface. Soil gas wells OBS-1, OBS-2, OBS-3, OBS-4, OBS-5, OBS-6, SVE-1, SG-2, SG-7,SG-8, SG-9, SG- 12, SG-13, and SG-14 (Figure 2) were destroyed during the soil excavation activities conducted between February and April 2014. For these soil gas wells, the entire soil gas well and annular seal was excavated to the soil gas well total depth, at minimum, and removed from the Site by the remedial excavation contractor Pivox Corporation with oversight by TPG. The excavation cavity was backfilled with either imported clean engineered fill or 2-sack sand-cement slurry to a depth of four inches below grade followed by imported crushed gravel base rock up to the surface. Notification for the soil gas well destructions completed in November 2013 was given on November 5, 2013, approximately one week in advance of the scheduled drilling, by electronic mail. Subsequently, on November 13, 2013, Mr. John Yoakum of the County of San Joaquin County