HYDRO20716

• Permit No: C1981008
• IBM Index Class Name: Hydrology
• Doc Date: 7/21/2006
• Doc Name: Response to Reporting of Off Site Surface Water Discharge
• From: DMG
• To: Western Fuels-Colorado
• Permit Index Doc Type: Correspondence
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: (303) 832$106
July 21, 2006
Mr. Ross Gubka, P.E.
Chief Engineer
Western Fuels-Colorado
P.O. Box 628
Nucla, Colorado 81424
Re: New Horizon Mine (Permit No. C-81-008)
Response to Reporting of an Off Site Surface Water Discharge
Dear Mr. Gubka:
COLORADO
DIVISION O F
MINERALS
GEOLOGY
0.ECLA NATION•N INING
EAEETY•EQENCE
Bill Owens
Governor
Russell George
Executive DlreCtOf
Ronald W. Cottony
Division Director
Natural Resource Trustee
This letter is in response to Western Fuels-Colorado (WFC's) letter report entitled Reporting of
an Off Site Surface Water Discharge on July 10, 2006, New Horizon Mine. On July 11, WFC
informed the DMG of an intense thunderstorm event that occurred at the mine site on the
previous day resulting in surface water from the disturbed area being dischazged to off site
locations. The discharge occurred from surface water collection ditches that were breached prior
to treatment by a sedimentation pond. All five active Sediment Ponds (7,8,9,12, and 14)
withstood the event and performed as designed.
In response, Dan Mathews from our Grand Junction Field Office went to the site to conduct an
inspection. Dan Mathew's inspection report was sent to WFC on July 12, 2006 and indicated
that an enforcement action may be forthcoming pending review of the inspection report and
WFCs letter report as requested by DMG's Denver Office.
Based on our review of Mr. Mathew's inspection report and WFCs letter report an enforcement
action will not be issued. The information contained in the DMG inspection report and WFCs
report both indicated that a breach of surface water collection ditches occurred at five locations
but that off-site damage was very limited and impact appeazed to be insignificant. Only one of
the ditches (C 17) as measured by Mr. Mathews was found to be shallower than the design depth.
The ditch was found to be 7 inches deep and the design depth with freeboard is 1.36 feet.
However, this ditch was found to be wider than required (15.8 feet wide and only 9 feet wide
required). Further, based on the drainage area of 31.8 acres the ditch is required (by Rule 4.05.3)
to be designed for the 10-year, 24-hour precipitation event for a permanent ditch. The approved
ditch design is conservative since it is based on the 100-year, 24-hour precipitation event. The
Office of Office of Colorado
Mined land Reclamation Active and Inactive Mines Geological Survey