APPCOR13351

• Permit No: C1981053
• IBM Index Class Name: Application Correspondence
• Doc Date: 3/3/1986
• Doc Name: BLUE FLAME ADEQUACY REVIEW REGARDING SURFACE DRAINAGE
• From: MLRD
• To: PETER O CONNOR
• Media Type: D
• Archive: No

Richartl D. Lamm
Governor
DATE
70:
III IIIIIIIIIIIII III
DEPARTMENT OF NATURAL RESOURCES
Davitl H. Getches. Executive Director
MINED LAND RECLAMATION DIVISION
DAVID C. SHELTON, Director
March 3, 1986
Peter O'Connor
FROM; Anne Baldrige ~ ~/
RE: BLUE FLAME - ADEQUACY REVIEW REGARDING SURFACE DRAINAGE
I have completed my review of the proposed drainage control system for this
mine. Following are my comments.
1. The design for the propoed pond is adequate, however, the pond is
circular and would be difficult to build. I suggest building a square pond
with the same depth and side slopes. The surface dimensions should be 50' x
50' with inside bottom dimensions of 46' x 46'.
2. The pond design does not include a principal or emergency spillway. A
principal spillway is not necessary for this small pond as long as the
operator commits to pumping the pond to maintain enough storage for the 10
year - 24 hour storm.
The pond should have an emergency spillway. This spillway must be designed tc
pass the peak flows from the 25 year - 24 hour storm event. Using the
criteria established for the 10 year - 24 hour storm the design is as follows.
L = 320 ft.
Z=100 ft.
5=31%
A = 1.9 acres
Rainfall = 2.5"
CN=81
Runoff = 0.94"
No shape adjustment
Slope Adjustment = 1.09
Q 25 years = (1.09)(4.83 CFS/in)(0.94")
Spillway Design:
n
i~ ~ t
I`- ~ --~I
= 4.95 CFS
determine L using
broad-crested weir:
Q = CLH 3/2
423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. [phone]