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~~~ STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY Department of Natural Resources t 313 Sherman St., Room 215 Denver, Colorado 80203 Phone: (303) 866-3567 FAX: (303) 832-8106 Mazch 13, 2002 Banks and Gesso, LLC Attn: Tug Martin 720 Kipling Street, Suite 117 Lakewood, Co 80215 DIVISION OF MINERALS GEOLOGY RECLAMATION MINING•SAFETY Bill Owens Governor Greg E. Walther Executive Director Michael B. long RE: File No. M-2001-046; Nix Sand and Gravel Mine; Owens Brothers Concrete Division Director Company; Preliminazy Adequacy Review Response Deaz Mr. Martin: The division received your adequacy responses to our letter of August 10, 2001 on February 13, 2002. This response addressed many of the outstanding issues identified during our initial adequacy review. However, there are still a few areas that will need to be addressed in more detail in order for us to render a final decision on your application. Following is a listing of the remaining items under the headings as they appeared in the original adequacy letter. The new decision date for this application is March 29, 2002. If you aze unable to adequately address concerns identified either in this letter or the previous one, it will be your responsibility to request an extension of the decision date or the application could be denied. 6.4.4 Exhibit D -Mining Plan Several aspects of the mining plan have changed since the original submittal. The main change is the method of mining going from dry mining the designated areas to wet mining the azeas utilizing a suction dredge. This, coupled with a different mining sequence, goes towazds mitigating the potential problem associated with de-watering the pit. However, we aze still in the process of reviewing the reports submitted with your responses. This will be covered in more detail under section 6.4.7. The potential stability problem associated with vertical highwalls is being addressed by now proposing to mine at 2H:1 V, which is the maximum slope allowed without a stability analysis. This also addresses the potential problem of importing material to backfill to a stable configuration once mining is completed. However, a new concern that was identified is the production of approximately 1,000,000 cubic yards of overburden. This should not present a problem for disposal since it will be a simple matter of backfilling into the various mine areas as they are mined out. However, this material does present a bonding liability problem as mining progresses as well as a storage or location problem, especially as the mine is opened up. Once the operation moves on to the second phase, there should be room in the previous phase to dispose of excess material.