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Environmental Protection Plan-Amendment <br /> • BP-1 Beaver Pond(Wetlands)—ponded surface water adjacent <br /> to the access road retaining wall; <br /> • LDG-1 Little Deadwood Gulch surface water above the Chief Portal;and <br /> • LDG-2 Little Deadwood Gulch surface water below May Day 2 mine bench; <br /> Groundwater will be monitored from four groundwater wells [Section 6.4.21(12)and <br /> 6.4.21(19)].(Detailed water resource discussion is presented in Exhibit G Figure G-6) <br /> • LP-IGW-La Plata River alluvium; <br /> • MD-1-May Day well is located inclose proximity to the May Day No. 1 portal; <br /> • MD-2 May Day well is located in close proximity to the May Day No. 2 portal; and <br /> • ID-1 Idaho well close proximity to the Idaho No.1 collapsed portal; <br /> 6.4.21(8) Groundwater Information <br /> (a)Map <br /> Ground water information is presented in Exhibit G-Water Information. <br /> (b)Known Aquifers and Related Subsurface Water Bearing Fracture Systems Within 2- <br /> miles <br /> The permit area is located at the northern boundary of the San Juan Hydrogeologic Basin <br /> (Topper et. al.,2003). The Morrison Aquifer is the only significant hydrogeologic unit of <br /> the San Juan Basin present within the permit area and is stratigraphically higher than the <br /> ore-bearing zones.The May Day and Idaho mines are located within southward-dipping <br /> sedimentary rocks cut by a series of east-west faults. The May Day-Idaho Fault System is <br /> comprised of two eastward-trending reverse faults,each with a down throw to the south <br /> with vertical displacement along the two faults of 350-475 feet. <br /> The sedimentary units associated with the San Juan Basin are shown below with units <br /> hosting the workings shaded(Sources: Eckel, 1949;Topper et.al., 2003): <br /> Age Formation San Juan Basin Hydrologic <br /> H dro eolo is Unit Characteristics <br /> Upper Cretaceous Mancos Shale Co_nfinin_g Layer Well yields as much as I O'gpm <br /> Dakota Sandstone Dakota Aquifer Well yields as much as 10 gpm <br /> Upper Jurassic Morrison Formation Morrison Aquifer Well yields as much as 25 gpm <br /> Junction Creek Sandstone Porosity<1% <br /> Wanakah Formation <br /> Entrada Sandstone Porosity ranges from 2.6 to 12.1% Not <br /> considered a significant aquifer in Colorado. <br /> Well yields on site are less than 2 gpm. <br /> Jurassic and Dolores Formation Not considered a significant aquifer in <br /> Upper Triassic Colorado <br /> 2 Trautner Geotechnical,June,2011 Porosity Results for Entrada and Junction Creek Sandstone Samples, Durango <br /> Colorado <br /> Exhibit U-EPP Amendment <br /> 112d-M-1981-185 <br /> May Day Idaho Mine Complex <br /> March 10,2017 <br /> Page15 <br />