2023-09-06_PERMIT FILE - M2023032

Home Browse Search

Mining Plan All mining will occur north of the Arkansas River. The Arkansas River forms a hydraulic boundary. The mining and reclamation will not affect groundwater flows on the south side of the Arkansas River. Three (3) mine cells are currently planned at the site. Two (2)of the cells will initially be dewatered prior to lining with slurry walls, clay liners, or combinations thereof. The other cell will be an unlined fresh water and siltation pond which will be mined with typical mining equipment that may include dredges and/or excavators in a manner that will minimize dewatering. An approved SWSP will be obtained prior to mining below the water table. Potential Lining&Mining Impacts to Local Groundwater Levels Properly constructed slurry walls, clay liners, or a combination thereof will tend to isolate the surrounding alluvial aquifer allowing for dewatering from within the lined cells without major impacts to water levels exterior to the lined cells. The lined cells will likely cause"mounding"of groundwater(increase in groundwater elevation)on the upgradient side (north and northwest)of the proposed lined cells and a "shadow effect" (reduction in groundwater elevation)on the downgradient side (south and southeast)of the lined cells. Any mounding effect on the upgradient side is anticipated to be relatively minor(on the order of a few feet or less) and will dissipate with distance from the mine. The shadowing affect will likely be minor on the order of less than a foot to a few feet and will also dissipate with distance from the lined cells. Due to the presence of the lined cells, limited to no affects are anticipated outside of the lined cell due to dewatering during mining. The mounding effect on the upgradient side of the lined cell may result in some increased flow in the Excelsior Ditch. Area wells, discussed below, should not be affected due to their distance from the lined cells. Area Wells Within Approximately 600 Feet of the Mine A review of permitted wells on file at the State Engineer's Office (SEO), Division of Water Resources(DWR) indicates there are ten (10) permitted wells(not owned by Martin Marietta)within 600 feet of the permit boundary. All of these wells are screened in the alluvium. Six (6)of these wells are on the west, northwest, and north (upgradient)sides of the mine. Two (2)of the wells is north and cross-gradient of the mine. Two (2)of the wells are on the south side of the river. In addition, several wells are on the site itself and are owned by the Martin Marietta. A map showing the approximate well locations is included in Figure G-1. A discussion of the wells not owned by Martin Marietta and located within 600 feet of the permit boundary are discussed below(note a domestic well is usually for household use but sometimes may also indicate use in yards and/or livestock watering): • RBK Construction, Inc. (57014F, 80290F): This is a gravel well permit that is shown on the State well permit map as approximately 485 feet from the permit boundary, however the permit documents indicate the gravel pit extends to an area just west of Baxter Road. This is a distance of approximately 100 feet west of fresh water and siltation cells. Because this is a gravel mine permit, it is unlikely that RBK will complain about dewatering effects at the Thunderbird Mine. • Bregar(213102): This well is located at 312 Baxter Road, approximately 185 feet north of and upgradient of the permit boundary and approximately 800 feet from and on the opposite side of the Ditch from the nearest lined cell. The use of this well is industrial. Water was first used in 1967 at a rate of 15 gpm. This well appears to no longer exist. Martin Marietta Materials—Thunderbird Sand and Gravel—MLRB 112 Permit Application Exhibit G-4