Laserfiche WebLink
STATE OF COLORADO <br />DIVISION OF RECLAMATION, MINING AND SAFETY <br />Department of Natural Resources <br />1313 Sherman $t., Room 215 <br />Dever, Colorado 80203 <br />Phone: (303) 8663567 <br />FAX: (303) 832.8106 <br />DATE: June 4, 2010 <br />TO: Wally Erickson <br />FROM: Allen Sorenson <br />COLOILADO <br />DlVtftON OF <br />RECLAMATION <br />MINING <br />SAFETY <br />Bill Rift, Jr. <br />Covemor <br />James 8. Martin <br />Exams ve Di e= <br />RE: Access Road Review, Wildcat Mining Corporation, Idaho Mine, File No. M-2010-003 <br />The Division of Reclamation, Mining, and Safety (DBMS) engineering staff have reviewed those <br />portions of the permit application submittals received from Wildcat Mining on June 1, 2010 related to <br />the access road from La Plata County Road 124 to the La Plata River. The Geotechnical <br />Reconnaissance Report provided presents the conclusion that if construction is completed and repairs <br />are made, the road can be put to restricted use as access to the mines. The DRMS concurs. The <br />Geotechnical Reconnaissance Report recommends that a Work Plan be prepared by an experienced <br />geotechnical engineer and presents the minimum elements to be addressed in the Work Plan relative to <br />roadway fill, retaining walls, and monitoring. The Geotechnical Reconnaissance Report further <br />recommends that implementation of the Work Plan be overseen by an experienced geotechnical <br />engineer. DRMS engineering staff have not been involved in the Board Orders issued to Wildcat <br />Mining Corporation, and therefore cannot conclude if the proposal to prepare and implement a Work <br />Plan to complete and repair the road satisfies the terms or meets the deadlines of the Board Orders. If <br />the Board allows Wildcat to proceed with preparation and implementation of the Work Plan, the <br />following elements must be addressed. <br />1. The Geotechnical Reconnaissance Report states that that the upper 30 inches of the road must be <br />compacted to at least 90 percent relative compaction per ASTM D1557-02 and that in areas where <br />less than 30 inches of fill will be placed to complete construction of the road, to over excavate, <br />scarify, and compact to 95 percent. DRMS would require compaction to 95 percent throughout the <br />upper 30 inches of road, and notes that ASTM D1557-02 has been superseded by ASTM D1557- <br />09. The Work Plan must also include a specification for maximum lift thickness for fill to be <br />placed, and must call out a frequency for testing of fill and test methods to be employed. <br />2. The Geotechnical Reconnaissance Report states that the cut slopes in the cut through section at the <br />top of the hill are performing well. However, DRMS will require that these slopes be laid back to <br />1.25:1 (H:V) as recommended in the Trautner Geotech report to La Plata County that is included in <br />the Idaho Mine permit application. A description of how these slopes will be laid back must be <br />included in the Work Plan. <br />3. All other recommendations for fill, sloping, retaining walls, and monitoring contained in the <br />Geotechnical Reconnaissance Report are acceptable to the DBMS, and must be incorporated into <br />the detailed Work Plan. The Work Plan must include design details and specifications for all <br />elements of road construction and repair, and must specify a monitoring frequency for road <br />performance monitoring systems to be installed, and specify maximum allowable movement <br />tolerances. <br />Office of Office of <br />Mined Land Reclamation Denver • Grand )unction • Duranso Active and Inactive Mines