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Introduction <br /> This South Chieftain Mine (Mine) Preliminary Drainage Study provides the narrative laying the <br /> groundwork for the redesign of the outer drainage channel. The purpose of the outer drainage channel <br /> is to route stormwater flows originating upgradient from the mine around the mine so as not to <br /> interfere with mine operations. <br /> The narrative begins with a summary of the drainage issue facing the mine and its neighbor to the south, <br /> Brookfield Development, also known as Solterra. The latter part of the narrative then quantifies the <br /> impact of a 100-year storm utilizing methods developed by the Urban Drainage and Flood Control <br /> District and refined by the City of Lakewood. The last part of the narrative presents the basis for the <br /> design that is forthcoming. <br /> Issue <br /> Figure 1 illustrates what the drainage basin boundaries looked like in 1939 when mining operations <br /> began. Since the early 1990s, runoff collected and transported around the mine has been channeled to <br /> the drainageway east of the natural drainage channel. The current discharge point is at the SE corner of <br /> the mine. Solterra has, or is constructing a subdivision on the east, south, and west of the mine, said <br /> location either being cross gradient(east and west)or down gradient of the mine. Solterra has already <br /> constructed the development on the south end, and the gap (and related channel) left by Solterra for <br /> drainage at the SE corner of the mine is not adequate for carrying large flows such as what might occur <br /> with the 100-year storm. <br /> General Shale has obtained the services of HMD Consulting, Inc. (HMD [Doing business as HMD Water]) <br /> to design a stormwater conveyance system to reroute said flows to the prior drainage at the SW corner <br /> of the mine. General Shale has also tasked HMD with accomplishing this task while preserving the <br /> ability to mine its owned and leased mineral rights to the clay in the fee and leased mine footprint. <br /> Location and Mine Operation <br /> The South Chieftain Mine is an open pit clay mine located in The Rooney Valley part of Jefferson County <br /> south of Alameda Avenue, East of C-470,just east of South McIntyre Street and north of Bear Creek <br /> Reservoir. The mine consists of fee and leased land with owned mineral rights occupying a portion of <br /> the SW-1/4 of Section 24 and NW-1/4 of Section 25,T4S, and R7OW of the 6th Principal Meridian (see <br /> Warr <br /> 1 07/30/2017 <br />