COMPLIANCE INFO_2024 DRAFT REVISED SITE CHARACTERIZATION WORK PLAN

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5 Site Characterization Work Plan SWT Engineering Z:\PROJECTS\SiteLogIQ\Site Characterization Work Plan\Text\sdwrev 2-4-2024 Riverbank_Site Charac. Work Plan (Rev Feb 2024).doc proposed to determine the vertical and horizontal extents of waste fill. Minimally invasive augur borings up to 3 - 4 feet are proposed to verify the limits of waste to Jacob Myers Park. Trenches are not proposed in order to minimize the impacts of material required by the LEA to be backhauled to a permitted disposal facility. The amount of potholes and/or trencheslocation and number of potholes/borings may change depending on conditions in the field. Because it is likely that large, resistant materials will may be encountered, such as concrete slabs or asphalt, drilling or direct-push equipment are not suitable for the intrusive investigation. This intrusive field investigation (i.e., potholing and trenching) will be performed by sampling and analysis. The sampling and analysis is intended to document the procedural and analytical requirements for collection and analysis of the potentially contaminated soil hazardous materials. Representative sSamples will be taken of all four sides and bottom offrom each pothole and trench. The thickness, soil type, and condition of any cover soil is part of the evaluation from the potholes and augur borings. A Sampling and Analysis Plan is provided in Appendix B. Results of exploration will be documented on a topographic drawing for the disposal area which will depict the waste boundary, proper ty lines, structures, and other investigation information. A magnetometer (metal detector) or ground penetrating radar (GPR) survey may be conductedwas considered to further define the area of potholing and trenching. However, the small area and dense spacing of potholes/borings obviates the usefulness of geophysical survey methods. A utility line field survey will be conducted prior to excavation to preclude any excavation from impact to utility lines. The proposed pothole and augur boring locations are shown on Figure 3 and will be marked prior to implementation. Twenty-two (22) pothole and eight augur locations are proposed (approximately 50-foot spacing). The number and location of potholes and augur borings test pits and trenches, as shown on Figure 3, may be adjusted based on field conditions. The approximate limits of waste are shown on Figures 2 and 3. For decades, the LEA has visited and visually surveyed the site during routine quarterly inspections of the closed landfill. As part of the proposed potholing, an additional geophysical visual survey of the disposal site area will be conducted. In addition to the assessment of historical aerial photograph analysis and topographic maps already included in this Work Plan (Appendix A), the suspected boundary will be further assessed, as needed, using photograph analysis and topographic maps. The most effective methods for determining horizontal and areal extent based on site conditions, e.g., physical properties of geology, development and the fill area, are part of the intrusive investigation/field work activities outlined in this section. Once limits of waste are better defined during this intrusive field work, the estimated volume of waste in-place will be updated from the information provided in Section 3.0. The types and relative quantities of materials excavated will be characterized by using the authoritative sampling method, as discussed in Sampling and Analysis Plan (see Appendix B) . The LEA will be notified at least a week or five days when excavation activities (potholing and trenching) occur to allow them to observe the materials. Soil sampling will occur at each pothole and trench location as augur boring discussed in the Sampling and Analysis Plan is provided in Appendix B. If burn ash is encountered during potholing and trenchingaugur boring, soil/ash samples be collected and analyzed to meet the site- specific DRAFT