ARCHIVED REPORTS_2018 REV SITE INV WK PLAN+

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Revised (Second) Confirmation Site Investigation Work Plan 17100 Murphy Parkway, Lathrop, San Joaquin County, California Solid Waste Information System (SWIS) number 39-CR-0022 (APN 198-120-09) 1.0. INTRODUCTION At the request Mr. Dana Parry of R & B Louise LLC, et al, Advanced GeoEnvironmental, Inc. (AGE) has prepared this Revised(Second) Confirmation Site Investigation Work Plan for the property located at 17100 Murphy Parkway, Lathrop, California (site — the site is considered only the western portion of Parcel Number 198-120-09). A location map of the site is presented in Figure 1. A site plan depicting site features is presented in Figure 2. A map depicting the waste cells and proposed soil boring locations is presented in Figure 3 and cross-sections of the waste cells are presented in Figures 4 and 5. An initial Confirmation Site Investigation Work Plan dated 19 October 2017 was prepared as required by Central Valley Regional Water Quality Board (CVRWQCB) letter dated 26 September 2017 to evaluate soil beneath the interface of the imported fill in the North and South Waste Cells; no additional investigation was directed. The CVRWQCB conditionally approved the Confirmation Site Investigation Work Plan (19 October 2017) by letter dated 16 November 2017. The conditional approval letter requested a revised work plan be submitted incorporating the comments and conditions outlined in the 16 November 2017 letter, which included additional investigation surrounding the waste cells. AGE submitted the Revised Confirmation Site Investigation Work Plan on 20 November 2017. Following review of the Revised Confirmation Site Investigation Work Plan, the CVRWQCB requested preparation of a Re-Revised Confirmation Site Investigation Work Plan by letter dated 22 December 2017 to clarify and address comments that were not addressed in the Revised Confirmation Site Investigation Work Plan. Therefore,AGE has prepared this Revised(Second) Confirmation Site Investigation Work Plan to address all comments and requests from the CVRWQCB by letters and phone conferences. The scope of work has been expanded to further investigate the waste cells and the surrounding areas. Regional Board staff has stated visual observations of clean excavation limits are not a substitute for confirmation sampling of the sidewalls and excavation floor (CVRWQCB letter dated 22 December 2017). However, AGE has still provided the following summary to discuss the limits of the waste determined in the field and the waste removed based on a combination of sampling results and visual observations. But as mentioned above, AGE has expanded the scope of work in this work plan to investigate, confirm, and verify the limits of waste within and surrounding the waste cells through sample collection and analysis. • The eastern boundaries of the North and South Waste Cells have been defined by previous work performed at the site. The eastern limits of waste were defined by trench T55, excavated to nine (9) feet below surface grade (bsg) east of the South Waste Cell; and trench T69, excavated to five (5) feet bsg east of the North Waste