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Greg Lewicki And. Associates, PLLC <br /> 3375 W. Powers Circle Phone: (720)842-5321 Fax(303)346-6934 <br /> Littleton,CO 80123 E-mail: info(a-'lewicki.biz <br /> June 19, 2019 <br /> Eric Scott <br /> Colorado Division of Reclamation, Mining, and Safety <br /> 1313 Sherman St, Rm 215 <br /> Denver, CO 80203 <br /> Ioana Comaniciu <br /> Colorado Division of Water Resources <br /> 1313 Sherman St, Rm 821 <br /> Denver, CO 80203 <br /> Asphalt Paving Co.,Ralston Quarry M-1974-086 <br /> Technical Revision—Demonstration of Mining Plan Avoidance of Groundwater <br /> Mr. Scott: <br /> Asphalt Paving Co.,the permittee of the Ralston Quarry, is submitting this technical revision to <br /> satisfy the conditions of approval of Amendment 04. Specifically,this technical revision <br /> demonstrates how the mining plan, as approved in AM-04, will not intercept groundwater in <br /> excess of the Colorado State Engineer's Office, Division of Water Resources lined reservoir <br /> criteria. <br /> 1. Hydrogeology of the Ralston Plug <br /> The Ralston Quarry is situated entirely in an intrusive basalt dike that thrusts through the <br /> surrounding Pierre Shale. The Pierre Shale serves as the boundary for the current quarry to the <br /> west along the ridge top. The basalt is classified by the US Geological Survey as an intrusive <br /> mafic monzonite (Horn, 1972). Basalts of this type generally have very low permeability with a <br /> few exceptions. 1) As basalt cools, gases are trapped in the aphanitic groundmass and result in <br /> cooled solid rock with considerable pore space at the tops and bottoms of each flow. 2)Multiple <br /> flows form layers that can be separated by various soil zones and alluvium that serve as <br /> permeable zones. 3) Post formation fracture and joint structures that occur within basalt <br /> formations can serve as hydraulic conduits for groundwater flows. However, as detailed below, <br /> the general structure of the basalt at the Ralston Quarry exhibits very low permeability and does <br /> not facilitate the transmission of water. <br /> As part of their evaluation of the Ralston Quarry's usability as a water storage reservoir <br /> following mining and reclamation, Asphalt Paving Co. contracted Brierley Associates to <br /> investigate the hydrogeologic conditions of the basalt formation. This investigation was <br /> conducted expressly to determine if the basalt formation at the quarry was hydraulically isolated. <br /> Hydraulic isolation is necessary to ensure that any water stored within the reclaimed quarry <br /> Ralston Quarry GW I (:ra 1 <br /> .r-1.and 15xoa iata.,-E.( <br />