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AGGREGATEIV�p <br /> INDUSTRIES <br /> September 16, 2019 DMSION OF RECLAMATION <br /> MINING AND SAFETY <br /> Jared Ebert <br /> Environmental Protection Specialist III <br /> p ` <br /> Colorado Division of Reclamation, Mining and Safety <br /> 1313 Sherman Street, Room 215 <br /> Denver, CO 80203Civic Center <br /> RE: Tucson South Resource, M-2004-044, Amendment Number 1 (AM01) Adequacy Review No. 2 <br /> Dear Jared: <br /> Please accept this response to your adequacy review comments dated July 26, 2019. Our response <br /> follows the format of your comments: <br /> Rule 6.4.3, Exhibit C — Pre-mining and Mining Plan Map(s) of Affected Lands <br /> 3. Page D-5 indicates topsoil stockpiles within the floodplain will be created parallel to the South Platte <br /> River flows and will only be 300 feet in length with 100 foot spacing in-between the piles for flow. The <br /> topsoil stockpile depicted in the south area shown on the Exhibit C-4 map does not appear to comply <br /> with these requirements as a portion of it is within the 100 year floodplain and is perpendicular to the <br /> river flow. Either revise the map to configure the pile in accordance with the approved plan or provide <br /> an explanation why this pile is not configured as discussed in the narrative. <br /> a. Al Response: A hydraulic model was prepared as a part of the Floodplain Development Permit. The <br /> hydraulic model and mapping shows that there are certain areas within the proposed mine where <br /> stockpiles can be stored without impacting flood elevations. On the north side of Highway 7, the <br /> stockpile is in an area that is not anticipated to be flooded during a 100-year storm. On the south side of <br /> Highway 7, the stockpile is in an area that is considered ineffective flow area due to the contraction <br /> effects of the bridge. An ineffective flow area is an area where ponding will occur but does not convey <br /> flows further downstream and is typically found adjacent to bridges and culverts. Stockpiles placed <br /> within and ineffective flow area are not expected to contribute to increases in water surface elevation. <br /> Since stockpile placement in each of these areas is not expected to increase water surface elevations, <br /> the restrictions on length and width of the stockpile are not pertinent. Exhibit D has been revised with <br /> language describing the justification for differing stockpile dimensions. <br /> b. DRMS Response: Your response indicates the length and width of the stockpiles in the applicable <br /> "ineffective flow area" is not pertinent. The Division assumes based on this information the orientation <br /> of the stockpiles in question are also not pertinent. Please clarify? <br /> Aggregate Industries—WCR,Inc <br /> 1687 Cole Blvd Suite 300 <br /> Golden,CO 80401 <br />