HYDRO22512

• Permit No: C1981015
• IBM Index Class Name: Hydrology
• Doc Date: 3/10/1997
• Doc Name: MEMO-FRUITA MINES CDPS PERMIT DMG FN C-81-015
• From: DMG
• To: JON KUBIC
• Permit Index Doc Type: NPDES
• Media Type: D
• Archive: No

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~II ~I~~I~~I~~~~~~I~
999
STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Deparlmem of Natural Resources
1313 Sherman 51., Room 215 ~~~
Denver, Colorado 80203
Phone:[phone]~3567
FAX: [phone]
DATE: March 10, 1997 DEPARTMENT OF
NATURAL
TO: Jon Kubic RE$OLJRCE~
Roy Romer
FROM: Larry Routten Governor
lames 5. Lochhead
RE: Fruita Mines CDPS Permit Evecmrve Director
DMG File No. C-81-015 r.~ichael B. LOnp,
Division Direc mr
Here is the information I promised to forward to you regarding the
conditions at the Fruita Mine. The description of the sediment
pond remaining on site is taken from a recent inspection report
written by Dan Mathews of our office. The characterization of the
revegetation on the mine site is from the same inspection report.
If you have any further questions, give me or Dan a call.
One impoundment still exists at the site, the large sediment pond
which controls runoff from the entire disturbed area, with the
exception of approximately 1/2 acre of disturbance in the vicinity
of the reclaimed sediment pond and former topsoil stockpile
location. The total area that drains to the pond is 79.6 acres, of
which approximately 11 acres was disturbed by the Fruita Mines.
The pond has a gated 4" PVC primary spillway which is mounted and
braced inside a 30" CMP emergency spillway. The gated primary
spillway is located approximately 2 feet above the bottom of the
pond, with an 8 foot riser section on the emergency spillway
providing a total pond volume of approximately 7.4 acre feet. The
pond is designed to contain, and the emergency spillway is designed
to safely convey the flow from a 25 year/24 hour precipitation
event. The pond embankment forms a segment of the mine access
road, and. the landowner has requested that the embankment, and
road, remain in place to allow for future vehicle access to the #1
Mine bench. When sediment control for the site is no longer
needed, the riser section will be removed, leaving only the 30"
culvert under the road. The culvert is adequate to pass the flow
from a 100 year/24 hour peak flow with only minor detention time.
The embankment shows no signs of bulging, cracking, displacement,
or seepage, and only minor erosion at inlet locations. The primary
and emergency spillway structures are in good condition, with the
exception of a small hole approximately 1/4" in diameter, through
the principal spillway gate valve. Given the small size of the
hole, it would appear that the pond would provide sufficient
settling time for the design storm event.