2019-09-16_REVISION - M1994117 (2)

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RECEIVED COLORADO MILLING COMPANY, LLC P.O. sox 1523 SEP 16 2019 Longmont, Colorado 80502 DIVISION OF RECLAMATION MINING AND SAFETY *5wa!l �77q 11V1&d0f,' Colorado Division of Reclamation, Mining and Safety September 15, 2019 Attention: Amy Eschberger 1313 Sherman Street—Room 215 Denver, Colorado 80203 RE: Gold Hill Mill, Permit No. M-1994-117, Amendment Application (Revision No. AM-01), Adequacy Review No. 5 Attention: Amy Eschberger: This is the Colorado Milling Company, LLC's Response Letter to the items listed in Amy Eschberger's July 23, 2019 Adequacy Review No. 5 of the Application for an Amendment to the Gold Hill Mill Limited Impact 110 (2) Permit No. M-1994-117, to formally add the previously permitted Left Hand Creek Pump Station, Gold Hill Mill Pipeline, and the Times Mine adit portal to the affected land boundary of the Gold Hill Mill Permit. These three features are collectively referred to as the Gold Hill Mill Waterline in this Response Letter. In order to ensure that the responses to the Division of Reclamation, Mining and Safety's request for additional information and clarification can be properly reviewed, the responses are set out below each of Amy Eschberger's Adequacy Review comments. Exhibit C—Mining Plan (Rule 6.3.3): 1) The operator's response to Item no. 1(a) states the requested mine pool drawdown plan cannot be developed and submitted to the Division until a pumping test has been conducted at the site. Therefore, the Division has the following comments regarding this item: a. Please provide a pumping test plan detailing the proposed procedures. This plan should include a detailed description of how water pumped from the workings will be managed during testing, and whether a discharge permit will be required from the CDPHE, WQCD. CMC Response: The Times and Wynona Mines pump test has been designed to determine the mine pool volume above the collar of the winze that connects the Times Mine with the Wynona Mine workings. To perform this evaluation, mine pool drawdown data from a pumping test needs to be acquired. The pump test involves the following activity: 1