2025-03-11-minutes-solid-waste-and-maintenance

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Ryegrass LPL and Ryegrass Balefill Landfill Upgradiant Groundwater Investigation Kittitas Couruy Wid waste 3.7.1 Top off'the Vantage lntexbed As noted above, the Vantage Interbed serves as the local bottom confining layer for the Shallow Aquifer. At the proposed location of monitoring well B8, the top of the Vantage Interbed is projected to be approximately 1.85 feet bgs. The new well should be targeted to approximately 200 feet below ground to ensure the well fully penetrates the Shallow Aquifer to account for natural variation. Drilling, Construction, and Testing The groundwater investigation will include drilling one monitoring well, B8, located upgradient of both the Balefill Landfill and LPL to a depth of approximately 200 feet bgs from an elevation of approximately 2,650 feet AMSL located just north of the Facility office and south of the septage and leachate lagoons (Figure 3), 4A Drilling The well will be drilled with a minimum borehole diameter of 6-inches to facilitate construction of a 2-Inch diameter monitoring well. The well will be drilled by a Washington State licensed driller in accordance with Chapter 173-160 WAC. The driller will submit a notice of intent prior to mobilization. Drilling will be completed using open borehole drilling or use with a conductor casing depending upon the methodology selected. Clean potable water may be utilized to assist with drilling through the basalt to the target zone. The field geologist will log the geology of the borehole and confirm drilling observations with the licensed driller. This includes evaluations of: ■ Drill/penetration rate ■ Llthology, color, density, fractures, vesicles. weathering, size, angularity, texture, and mineralization P Water Content/Saturation ■ Voids and drilling problems Drill cutting samples will be collected by the field geologist and stored in zip -lock bags labelled with the collection depth and date. Unused drill cuttings will be disposed of at ground surface. At a minimum, samples will be collected at 2.5-foot intervals In water bearing zones and approximately 10-foot intervals In non -water bearing zones by the driller or by the field geologist as necessary. 4.2 Construction The well will be constructed with 2-inch diameter Schedule 80 PVC screen and risers. Approximately 10 to 20 feet of 0.020-inch (10-slot) or 0.020-inch slot (20-slot) screens will be used for the well. The screen is anticipated to be placed approximately 170 to 190 feet bgs matching the hydrostratigratphy in Figures 4 and 5. The screen will be packed with 12x20, 10x20 or 8x12 silica sand pack. The pack will extend a minimum of 3 feet above the screened zone. A bentonite seal will be placed from the top of the pack to approximately 2 feet bgs. An above -ground monument and concrete will complete the construction of the well. Figure 6displays the approximate details of the proposed well design and summarizes the anticipated corresponding geology to the approximate construction. April 2024 1 553.1763-010 Revised May 2024