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Ryegrass Limited Purpose Landfill and Balefill Closed Landfill <br />Groundwater and Leachate Sampling and Analysis Plan <br />Kittitas County Solid Waste <br />This sampling and analysis plan (SAP) outlines procedures for the sampling and analysis of <br />groundwater and leachate at the Ryegrass Limited Purpose Landfill (LPL) and Ryegrass Balefill <br />Municipal Solid Waste (MSW) Landfill (Balefill Landfill) located in Kittitas County, Washington. It is an <br />update of previous SAPs prepared for the LPL by HWA Geosciences (HWA 2020) and for the Balefill <br />Landfill (HWA 2018). <br />The Facility is owned and operated by Kittitas County Solid Waste (County) and encompasses 640 <br />acres of land located within Section 16 of Township 17 North, Range 21 East on Kittitas County <br />parcel identification numbers 040833 and 956102 (Figure 1). It is addressed at 25900 Vantage <br />Highway in Ellensburg, Kittitas County, Washington and accessed from a paved roadway off Vantage <br />Highway north of the Facility. In addition to the active 13.5-acre LPL and the closed 27-acre Balefill <br />Landfill, the Facility includes a leachate pump station, two lined 500,000-gallon leachate <br />evaporation ponds, two lined 500,000-gallon LWELS, and biosolids land application fields (see <br />Figure 2). <br />The LPL is located on the northwest portion of the Facility. Environmental monitoring of the LPL is <br />completed in accordance with Chapter 173-350 Washington Administrative Code (WAC) and Kittitas <br />County Public Health Department (KCPHD) Permit Number LPL-05. <br />The Balefill Landfill was operated on the Ryegrass Facility from 1980 until 1997 under Chapter 173- <br />304 WAC and later Chapter 173-351 WAC. The MSW landfill was closed in 2005 under Washington <br />State Department of Ecology (Ecology) Agreed Order DE98-SW-C168 (Ecology 1998, 2012). <br />Environmental monitoring of the Balefill Landfill is completed in accordance with the Post -Closure <br />Environmental Monitoring Plan (HWA 2018). <br />1.1 Physical Setting <br />The physical setting surrounding the Ryegrass Facility is described in the Hydrogeologic Investigation <br />Report (HWA 2023). A brief summary is included below: <br />Soils in the Ryegrass Facility vicinity are mapped as Argabak very cobbly loam, Argabak-Vantage <br />complex, and the Palerf-Vantage complex (NRCS 2023). All soil types consist of cobbly loam <br />averaging in thickness of approximately 6-inches above bedrock with nearby dry channels having soil <br />thickness up to 35-inches. <br />The surface geology of the Ryegrass Facility is mapped as the Frenchman Springs member of the <br />Wanapum Basalt (DNR 1994). Outcrops of the Vantage Interbed (mapped as Mc) are also located <br />nearby. The surface geology is locally defined as the lowermost flow of the Frenchman Springs <br />known as the Gingko Flow. The basalt consists of massive and columnar formations with the bottom <br />of the unit above the Vantage consisting of palagonite, pillow basalts, and petrified wood. The <br />Vantage Interbed consists of sandstone, siltstone, and claystone and serves as a confining layer. <br />Groundwater is present in the bottom flow zone of the Gingko Flow above the Vantage Interbed. The <br />depth to the Vantage Interbed ranges from 70 to 130 feet below ground surface near the LPL. <br />Groundwater below the LPL predominantly flows to the west-southwest. Several springs are located <br />to the west and south of the LPL related to outcrops of the Vantage Interbed. <br />April 2024 1 553-1763-010 1-1 <br />Revised May 2024 <br />