2022-07-19_REVISION - M1987026 (2)

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RECEIVED Black Obsidian Pit—Permit M-1987-026 JUL 19 2022 112c Conversion Application (rev 07/13/22) DIVISION OF RECLAMATION Rule 6.4.7 MINING AND SAFETY Exhibit G Water Information The site is located in a dry upland setting. There are no aquifers, perennial streams or ditches that will be affected. The project has no water requirements,either during the development, mining or reclamation stages of the project. The site is on gently rolling rangeland, and includes several ephemeral drainages, which do not typically flow except after significant precipitation events. The operation is not expected to directly affect surface or groundwater systems. Based on observations at the site during the past four decades, no groundwater is expected to be exposed during operations. Any surface water captured in the pit during mining will be released to the stream system within 72 hours. All drainage from affected land in the existing operation reports to a sediment pond below the entrance to the permit. It is unlined and percolates into the surface. Drainage from the expanded operation will report to a sediment pond to be constructed immediately below the toe of the quarry pad (in Phase 1). Due to the nature of the obsidian and the below-grade quarry floor,the quarry does impound a small amount of water. Prior to initiating activities in the quarry,the operator dewaters the limited amount of impounded water,which reports to a nearby unlined sediment pond. Effluent from this pit does not generate or carry appreciable amounts of sediment, and the existing pond therefore retains its design capacity;the new sediment pond will receive effluent from the same obsidian deposit and very little sediment is expected to be transported to that pond also. The operator has a CDPHE—WQCD stormwater management permit. Stormwater and sediment controls to be used onsite include: existing sediment pond below the operations pad, earthen berms or silt fence to divert or direct surface flows to proper control structures,appropriate slope gradients on pit slopes and stockpiles to reduce erosion,timely revegetation on affected surfaces. Please see the ephemeral drainages, and stormwater and sediment controls shown on the maps in Exhibit C.