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<br /> <br />1313 Sherman Street, Room 215, Denver, CO 80203 P 303.866.3567 F 303.832.8106 http://mining.state.co.us <br />Jared Polis, Governor | Dan Gibbs, Executive Director | Virginia Brannon, Director <br /> <br /> <br /> <br /> <br />August 17, 2023 <br /> <br />Julie Mikulas <br />Martin Marietta Materials, Inc. <br />1800 N. Taft Hill Road <br />Fort Collins, CO 80521 <br /> <br /> <br />RE: Corrective Actions Required; Disturbance to Hydrologic Balance, Home Office Mine, <br /> Permit No. M-1977-439 <br /> <br />Dear Ms. Mikulas, <br /> <br />On August 16, 2023, the Division of Reclamation, Mining and Safety (Division/DRMS) received the quarterly <br />groundwater level monitoring results for the Home Office Mine, Permit No. M-1977-439. After reviewing <br />the data provided, the Division is citing a problem for which corrective actions are required (detailed below). <br /> <br />Background <br />During the adequacy review of Amendment 4 (AM4), specifically the responses to adequacy review 3 dated <br />February 7, 2023, the Operator made a commitment in item 40(a) to collecting groundwater level <br />monitoring data from site wells and submitting the data to the Division on a quarterly basis. AM4 was <br />approved on February 15, 2023. <br /> <br />Additionally, within the same review response document, the Operator committed in item 40(f) to submit a <br />Technical Revision for the designs of an underdrain located on the north side of Cell G-I by May 31, 2023. <br />The underdrain will be installed if groundwater level is within 4 feet of the ground surface for more than 2 <br />consecutive months. <br /> <br />On June 1, 2023 the Division approved an extension request for submitting the Technical Revision from May <br />31 to June 14, 2023. On June 15, 2023 the Operator submitted Technical Revision 6 (TR6) for the designs of <br />an underdrain located on the north side of Cell G-I. During the preliminary adequacy review of TR6 the <br />Division determined the Operator had not submitted the quarterly groundwater level data as committed to <br />during AM4. The Division requested the missing quarterly groundwater level data in a letter dated June 28, <br />2023. <br /> <br />On August 16, 2023 the Operator responded to the Division’s preliminary adequacy review. Part of the <br />response contained the missing quarterly groundwater level data. The data indicated groundwater level at <br />monitoring well HO-01, located at the northwest corner of Cell G-1 has had water levels within 4 feet of the <br />ground surface since February 6, 2023 through the last measured date of August 9, 2023. The Division <br />approved TR6 on August 17, 2023. <br /> <br />Based on the groundwater level data provided for the Home Office Mine from February through August <br />2023, the Division is citing a problem pursuant to Rule 3.1.6(1) for failure to minimize disturbances to the