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2. Portal Surface Water Inflow <br /> As noted by Division inspectors, during the summer months the portal at the Detroit City Mine <br /> has a number of small drippings of water entering it around the steel and shotcrete that makes up <br /> the portal. This flow is gathered in a small sump on the left side of the portal (looking inby). <br /> From this sump, the water then flows through the talus rock on the mountainside down to the <br /> creek near County Road 8. This water is collected into a sump for operational cleanliness and <br /> orderliness reasons. The sump is not lined so that the water collected can continue to flow <br /> through the talus as it naturally does. <br /> 2_1 Portal Sump Water Usage—Legal Water Source <br /> Periodically, as allowed by their Colo. Division of Water Resources administrative exchange, <br /> Detroit City Mine pumps water from the portal sump to supply drilling underground. Colorado <br /> Calumet Co. is legally permitted to pump this water as part of their exchange contract with the <br /> Headwater Authority of the South Platte (HASP). A copy of the exchange contract and local <br /> water commissioner clarification that the sump pumping falls under the exchange contract, are <br /> attached. When this sump water is not available,the mine pumps from the creek drainages <br /> according to the same exchange contract. This contract is renewed annually depending on water <br /> availability. <br /> 2.2 Groundwater Source Grouting <br /> The water that enters the portal area via drippings is surface water flow from storm events and <br /> snow melt on the mountain side that the mine portal daylights out of. The mountainside is <br /> covered with a high porosity talus consisting of broken igneous rock. Any runoff that is flowing <br /> downhill along material like this quickly drops out of site and flows through the talus. This talus <br /> eventually interfaces with the colluvium/alluvium along Buckskin Gulch, and the surface water <br /> flow within enters the creek the same as any other surface water from a drainage. <br /> Since this water flows along the surface and joins the area surface water regime, it is not <br /> appropriate to consider it groundwater. Groundwater as found within igneous rock like that <br /> which hosts the Detroit City Mine is water found within the cracks, fractures,joints, faults, veins, <br /> and other geological structure of the mountain. One hundred feet into the main tunnel at the <br /> Detroit City Mine, the difference between surface water and groundwater can be clearly <br /> observed: despite the presence of water dripping at the portal entrance the mine, further in, is <br /> dry. <br /> Furthermore, if the portal drippings were from groundwater,there would be a correlation of flow <br /> intensity. Surface water at the portal is seasonal and only flows when the temperature is high <br /> enough. There are no groundwater flows within the mine regardless of the surface temperature or <br /> time of year. <br /> Given the portal drippings are surface water in nature,they are handled as such. Groundwater <br /> flows, if ever encountered, will be grouted as follows: <br /> If drilling and blasting underground encounters any groundwater inflows, the source of said flow <br /> will be immediately grouted to completely seal the source. Pressure grouting will use a resinous <br /> or cementitious grout that will stop said water flow and prevent future in flows from that source. <br /> Annual reports will note if grouting was conducted in the previous year and describe the type <br /> Detroit City Mine <br /> January 2020 2 Creg 1—ic►i and Ass ialrs,PLIA <br />