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~ III IIIIIIIIIIIII III 999 STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY Depanmem of Natural Resources 1313 Sherman SI., Room 215 Denver, Colorado 80203 Phone: 0031 866-3 56 7 FAX:f}031812-8106 September 27, 1994 Mr. Jim Stover MINREC 2768 Compass Drive Grand Junction, CO 81506 RE: North Thompson Creek Mine (C-81-025) Dear Mr. Stover: ~~~ DEPARTMENT C NATURAJ RESOURCE Roy Romer Governor lames 5 Lochhead Exttmrve DlrMror Michael 6. Long Division Dneao, During the Division's recent inspections of the North Thompson Creek mine site on September 14 and 23, a number of items were noted which need to be corrected and/or clarified in the permit application package. You and I discussed most of these items during our site visit on September 23. This letter is to notify you that the Division will require a technical revision to the North Thompson Creek permit be submitted by October 26, 1994. The revision should address the following topics. 1. Drawing D-4-5 and pages 4-ii and 4-19 indicate that ponds P-1, P-2, and P-7 have been reclaimed. These, and other water control structures, are still very apparent on the ground and require further reclamation. The permit needs to be revised to include designs for a stable diversion and/or energy dissipating devices in front of road culverts where ponds P-1,4,5,6, and 7 exist. Diversion designs should comply with Rules 4.03.2(4) and 4.05.3 and should be based on a 10-year, 24-hour storm event. Energy dissipating sumps at culvert inlets, if any are proposed, do not need to be designed as impoundments if they do not impound water behind an embankment or the road fill. A sump in a ditch at a culvert inlet which serves to decrease the energy of runoff prior to entering the culvert does not require permit designs so long as the sump is not a significantly large one and the bottom of the culvert is at or below the bottom of the ditch. In addition, Drawing D-4-5 and page 4-ii indicate pond P-2 has been reclaimed. This structure remains on the ground. The pond needs to be reclaimed to blend with the surrounding topography and the relevant permit sections revised accordingly.