HYDRO21585

• Permit No: C1981047
• IBM Index Class Name: Hydrology
• Doc Date: 12/13/1988
• Doc Name: WASTE PILE DIVERSION DESIGN UPDATES
• From: MLRD
• To: CANDY THOMPSON
• Permit Index Doc Type: CORRESPONDENCE
• Media Type: D
• Archive: No

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999
STATE OF COLORADO
Roy Romer, Gove
DEPARTMENT OF NATURAL RcSOURCES
MINED LAND RECLAMATION DIVISION
FRED R. BANTA, Director
DATE: December 13, 1988
T0: Candy Thompson
FROM: Tim Y.ing
RE: Waste Pile Diversion Design Updates
On-site inspections produced the following revisions of my memo to you dated
November 19, 1988.
C-80-007 P1t. Gunnison
All of the ditches around the lower wastepile are designed using a 100-year,
24-hour event. However, one collection ditch and one diversion ditch, labeled
South and Southwest, are presently undersized on-site. After his recent
inspection, 14att Hayes instructed the operator to rework these areas to bring
them into compliance. We will verify this in January. The 100-year, 24-hour
design calls for triangular ditches, 2 feet deep. All the other ditches at
the site meet this requirement
C-83-038 Orchard Valley
The East Ridge and Ylest Ridge waste pile diversions are in fact designed using
a 10-year, 24-hour event. These two piles constitute an interim phase of
waste pile construction. However, the 49-year pile, which is the combination
of the two piles, and is the final permanent structure, will use a diversion
calculated using a 100-year, 24-hour event. Please note that the East Ridge
pile has not been started and therefore the 49-year pile does not yet exist
either. Field measurement at the West Ridge pile indicate the ditches are in
compliance. CWI expressed a belief that the West Ridge ditches were in fact
constructed to 100-year specifications. They have been unable to demonstrate
this to date. We will continue to pursue this issue. There also exists an
old refuse pile which we will finish investigating in January.
C-81-034 Red Ca
As stated previously, these diversions are designed using a 100-year, 24-hour
event. Red Canyon remains in compliance. Field measurements show triangular
ditches from 15 inches to 48 inches wide, and from Z4 inches to 33 inches
deep. These exceed the designed requirements.
215 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. [phone]