REV05718

• Permit No: C1981019
• IBM Index Class Name: Revision
• Doc Date: 9/13/1993
• Doc Name: COLOWYO MINE PN C-81-019 TR NO 22
• From: DMG
• To: COLOWYO COAL CO
• Type & Sequence: TR22
• Media Type: D
• Archive: No

III IIIIIIIIIIIIIIII
STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department of Natural Resources
1313 Sherman St., Room 275
Denver, CO 80203
Phone: [phone]
FAX: [phone]
September 13, 1993
Juan Garcia
Hydrologist/Environmental Engineer
Colowyo Coal Company
5731 State Highway 13
Meeker, CO 81641
RE: Colowyo Mine, Permit C-81-019, Technical Revision No. 22
Dear Mr. Garcia,
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Roy Romer
Gwemor
Michael 8. Long
Drvrsiun Direcwr
As we discussed on September 9, 1993 The Division has one concern remaining regarding the
design plans for the West Tributary to Streeter Drainage Colowyo proposes in the application
for technical revision No. 22. The Division agrees with Colowyo that predicted flows and
velocities do not necessitate rip rap. Therefore, rip rap is not necessary for this channel and
not desirable. Since the channel is permanent, a vegetative lining in the ditch would be
preferable. Please submit to the Division a design for this ditch using vegetative cover as the
primary channel protection. Initial channel protection could be accomplished through the use
of a biodegradable channel liner. If absolutely necessary, intermittent check dams or other such
energy dissipators would be an acceptable means of reducing the velocity of flow in the channel.
The regulatory requirement that supports this request is Rule 4.05.3(3), which states:
To protect fills and property and to avoid danger to public health and safety,
permanent diversions shall be constructed to pass safely the peak runoff from a
precipitation event with a 10-year, recurrent interval, or a larger event as
specified by the Division for good cause shown. Permanent diversions shall be
constructed with gently sloping banks that are stabilized by vegetation. Asphalt,
concrete, or other similar linings shall be used only when approved by the
Division to prevent seepage or to provide stability.
If any further question remain, please contact me.
Sincerely,
1~^^
Specialist
cc: )Varry P. Routten, DMG
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