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STATE OF COLORADO <br />DIVISION OF RECLAMATION, MINING AND SAFETY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />Denver, Colorado 80203 <br />Phone: (303) 866-3567 <br />FAX: (303) 832-8106 <br />COLORADO <br />D I V I S I ON OF <br />RECLAMATION <br />MINING <br />SAFETY <br />MEMORANDUM John W. Hickeniooper <br />Governor <br />Mike King <br />Executive Director <br />To: Michael Cunningham, Environmental Protection Specialist Loretta Pineda <br />Director <br />From: Tim Cazier, P.E., Environmental Protection Specialist <br />Date: February 4, 2011 <br />Re: Slope Stability Analyses Review for Goose Haven Reservoir No. 2, Permit <br />No. M-2010-071 <br />The Division of Reclamation, Mining and Safety engineering staff (DRMS) have reviewed the <br />Slope Stability analyses submitted with the October 22, 2010 permit application for the Goose <br />Haven Reservoir No. 2, Boulder County, Colorado prepared by the City of Lafayette. <br />The review consisted of comparing the application content with specific requirements of Rule <br />6.5 of the Minerals Rules and Regulations of the Colorado Mined Land Reclamation Board for <br />the Extraction of Construction Materials. Any inadequacies are identified below along with <br />suggested actions to correct them. <br />1. Figures 1, and 3 - 8: Please identify the double dot, dash line either with a label or adding to <br />the legend. <br />2. There is a discrepancy between the density used for Silty Sands (SM) in the table on p. 18 <br />and Figure C-1 in Appendix C. Did you use 100 pcf or 120 pcf? <br />3. Drawing No. 4: According to the scale for Section B, the dimensioned 50 ft minimum buffer <br />from the property line measures only 40 ft. <br />4. Drawing No. 3: The Section B-B line indicates the left end of the section is to the north. <br />However, on Drawing No. 4, the left end of the section is clearly on the south end. The <br />slurry wall is not included in the legend. Please make appropriate corrections. <br />5. East Slope: <br />a. Figures C-2 through C-6: i) The approximate scale (1"=300') appears to be off by an <br />order of magnitude. According to that scale, the slurry wall is about 200 ft from the <br />crest of the slope and is 430 feet deep. Based on Drawing 3, the slurry wall is about <br />10 feet from the crest of the slope. Based on borehole locations (e.g., Figure 4) and <br />the borehole log for the hole (TH-21/Figure A-1) closest to the middle of the east <br />Office of Office of <br />Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines