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2. Surface Water <br /> Surface water flows drain naturally in two directions due to the topography: water on the west <br /> side of the permit boundary drains towards an existing sump in the northwest of the site, while <br /> water on the east of the site drains to the San Miguel River to the east via the Nelson ditch. Map <br /> C-1 shows these drainage directions. During mining, water runoff will be routed to the active <br /> mining pit to prevent runoff exiting the site. A berm will be constructed on the east side of the <br /> site to contain surface water runoff and prevent any eastward discharge. A berm of the same <br /> type will be maintained between the Skelton Pit and the San Miguel County on the west side. <br /> A sump will be installed on the west of the pit for stormwater containment and evaporation. No <br /> sediment will be allowed to leave the site and cloud any downstream waters. The site will not <br /> affect existing water rights as the pit will not expose groundwater and will not store stormwater <br /> for more than 72 hours. Sump locations and drainage directions during mining can be seen on <br /> Map C-2. Post mining conditions can be seen on Map F-1. Stormwater berms and sumps will be <br /> removed during final reclamation. This will lead to a post mine drainage condition that generally <br /> drains to the west. <br /> Based on using an encompassing site berm, the worst-case stormwater scenario to evaluate is <br /> at the end of mining. This is when the greatest drainage area for the site exists. Using the <br /> Natural Resource Conservation Service T-55 Method, the runoff for the 100-YR 24-HR event <br /> was calculated for each sump. This is then compared to the total capacity of that portion of the <br /> site to a depth of two feet to determine if there is sufficient storage capacity. <br /> Skelton Pit <br /> January 2022 G-2 Lewicki&Associates <br />