APPCOR10230

• Permit No: C1981034
• IBM Index Class Name: Application Correspondence
• Doc Date: 3/21/1980
• Doc Name: MEMO GRAND MESA COAL SEDIMENT CONTROL
• From: MLR
• To: LINDA
• Media Type: D
• Archive: No

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STATE OF COLORADO RICHARD D. ~. Govemm
DEPARTMENT OF NATURAL RESOURCES III'll'll'II"II'II
Harris D. Sherman. Executive Director
999
MINED LAND RECLAMATION
23 Centennial Building, 1313 Sherman Street
Denver, Colorado 60203 Tet. [phone]
Hamlet J. Barry, I I I,
Director
M E M O R A N D U M
T0: Linda
FROM: Todd
DATE: March 21, 1980
RE: Grand Mesa Coal - Sediment Control
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1) A runoff curve number of 76 was cited in the drainage study. Given
C and D group soils (Beenom-Absarokee), this is definitely too low for
the disturbed area, much of which is bare, and maybe too low for the
undisturbed area as well. This will change runoff and peak flow values.
2) Some of the old spoil area was not included in the drainage plan,
while the regulations say that all disturbed area runoff must be passed
through a pond. Acreages, sediment, runoff, and peak flow values should
be adjusted accordingly if any new disturbance will take place. Provision
must also be made for sediment control on the powder magazine site(if
it is to be used).
3) When the area marked OA on the drainage maps is disturbed, a
technical revision will need to be submitted, as ditches will be re-
routed, etc.
4) Ditches
a) Explain or delete the uppermost portion of ditch 19 (seems
to cross undisturbed ditch 8).
b) Explain or delete ditch number 25 (how will an acute angle
be turned into ditch 26?)
c) Explain how undisturbed ditch 6 drains into culvert C'',
If it does not, where will the flow be routed?
d) Clarify how undisturbed ditch 13 will cross disturbed
ditch 28.
e) Clarify the drainage at the intersection of culverts
A and C, and ditch 15 and 16.
f) Will there be a culvert where ditch 5 (disturbed)
crosses the road to the bath house area? If not, please
explain the nature and amount of traffic on the road, and
how the ditch would be maintained.
5) f'll from e sediment p nd cu to 6e-pl ced on its own-1
m ~ze~s suffi~iently~small hat th sedimen cont`ry'of m sur s
ulined'in the report will be suf 'cientc he dike w~l~--n~
Inee~ pond specifTCations-as-}~revie~ Please confirm that
sediment will be cleaned out when it reaches 60~ of its calculated
capacity (1.26 AF) in the pond.