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~~~ <br />III IIIIIIIIIIIIIIII STATE OF COLORADO <br />Roy Romer, Governor <br />Q <br />DEPARTMENT OFNATURALRESOURCES <br />MINED LAND RECLAMATION DIVISION <br />FRED R. BANTA, Dlraetor <br />November 27, 1987 <br />Mr. Robert Hagen <br />Office of Surface Mining Reclamation and Enforcement <br />625 Silver Avenue S.W., Suite 310 <br />Albuquerque, New Mexico 87102 <br />Re: Response to Ten-Day-Notice IJO. 87-02-107-14 Twin Pines Mine, C-83-058 <br />Dear Mr. Hagen: <br />The Division received the above referenced Ten Day TJotice on November 20, <br />1987, pertaining to the pond design at Twin Pines. The TDN indicated that two <br />ponds failed to have "an appropriate combination of principal and emergency <br />spillways". Our review of the designs and follow up inspections of the site <br />on November 18, 1987 revealed that the ponds do indeed have both a principal <br />and emergency spillway. <br />On both ponds the principle spillway is a 6 inch drain at the sediment storage <br />level designed to dewater a 10 year event. The pond also has a riser opening <br />of 24 inches in diameter which is capable of handling a 25 year event. Both <br />spillways are conveyed through the embankment by a six inch conduit. The rule <br />referenced in the TDN does not exclude this. This design is environmentally <br />sound and is a common engineering practice. (For example, Cherry Creek <br />reservoir in Denver is built with this configuration). We understand this <br />rule is subject to interpretation but our interpretation is as environmentally <br />sound as any other and meets the performance standard of safely conveying the <br />10 year and 25 year event. We see no need to enforce a more stringent design <br />interpretation if the performance standard is being achieved. <br />In summary, we feel the pond design is in accordance with what we approved and <br />meets the design and performance standards. Accordingly, no enforcement <br />action is needed. Please contact me if you concur. <br />Sincerely, <br />.~ ~ ~~ <br />V` ~ ~` ~. <br />Robert G. Liddle <br />Senior Reclamation Specialist <br />RGL/bdc <br />cc: Lynn Woomer <br />Joseph Carpine, Twin Pines Investment <br />3686E <br />423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. (303) 866-3567 <br />