ARCHIVED REPORTS_2019 SOIL MGMT PLAN (JULY-REVISED)

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EKI B90047.00 Page 4 Former Pilkington North America Site Lathrop, California 2019). A WU1 Clean Closure Plan and Work Plan Addendum (“WU1 Plan Addendum”), dated 22 February 2019 (AGE, 2019), was conditionally approved by the RWQCB on 15 March 2019. In late March 2019, and in accordance with the WU1 Plan Addendum (Appendix B), soil/waste material was excavated from the WU1 Sliver and stockpiled for reuse at the Site. • North and South Waste Cells: The third subarea within SWIS 39-CR-0022 contained two deep waste pits or cells containing waste glass, rubbish and other materials located on the western boundary of Parcel B. They have been designated as the North and South Waste Cells and investigation results are summarized in Appendix G. Similar materials are also present on the San Joaquin Cogeneration facility (“Cogen”). Extensive analyses were conducted on materials excavated from the North and South Waste Cells and WU- 1; two samples (out of more than 230 conducted in SWIS 39-CR-022) contained concentrations of lead and/or dioxin/furan above regulatory goals and both were detected in a waste cell (see Appendix F). The excavated materials were properly disposed of off site. • Diesel Spill Area: A diesel fuel leak from underground piping associated with an aboveground storage tank (“AST”) was discovered at the site in 1996 and was also excavated in 1996. Excavation activities removed the AST underground piping, approximately 15 cubic yards of soil, 3,000 gallons of diesel, and 2,000 gallons of a diesel and water mixture. A recovery and monitoring well network was installed in 1999 to passively remove additional light non-aqueous phase liquid (“LNAPL”) present in the subsurface at an average rate of less than 20 gallons per year (CRA, 2012; ACE, 2015). The recovery and monitoring well network was expanded in 2015 and a temporary dual-phase extraction (“DPE”) system began operation in June 2016 to actively recover LNAPL (AGE, 2018c). Three rebound tests were conducted from late 2017 to late 2018 (AGE, 2018c). Approximately 3,400 pounds (“lbs”) of diesel was removed by the DPE system as of September 2018 (AGE, 2018c). Based on test results, it was recommended that DPE system operation cease as LNAPL has been removed to the extent practicable and mass removal reach asymptotic conditions (AGE, 2018c). The RWQCB did not concur with this recommendation and requested additional monitoring and evaluation of the data in a letter dated 22 March 2019 (RWQCB, 2019a). That process/work is ongoing. Summary tables and figures of data for the Diesel Spill Area are included in Appendix H. • Stained Areas Observed in Utility Trenching: Stained soils were observed in utility trenching being conducted in April 2019 to the east of the main building (Figure 1-2). These areas were discussed in a Site meeting with RWQCB representatives and EKI on 3 0 April 2019. Collection of a soil sample was agreed to at that meeting. The sample will be analyzed for the list requested by the RWQCB in an email dated 6 May 2019. The list is provided below. The results will be reported in a memorandum to the RWQCB. • Cement/Glass Pad Along Utility Trench: There is an area of cement and concrete covered with asphalt slurry that was encountered in the excavation to the northeast of the larger of the two metal buildings at the Site. (Figure 1-2). This area was discussed in a Site