REV14092

• Permit No: C1981022
• IBM Index Class Name: Revision
• Doc Date: 5/6/1997
• Doc Name: SANBORN CREEK MINE C-81-022 TR 29
• From: DMG
• To: BILL CARTER
• Type & Sequence: TR29
• Media Type: D
• Archive: No

~
~.
~~
*
STATE OF
III IIIIIIIIIIIII III
COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department u( Natural Resources
1313 Sherman SL, Room 215 r~`

Denver, Colorado 80203 Il
~
I

Phone: [phone] I
I
FAX: [phone]
DEPARTMENT OF
NATURAL
RESOURCES
DATE: May 6, 1997
J Roy Romer
Gov
rn
r
TO: Bill Carter e
o
James S. Lochhead
EaecNive Director
FROM: Susan Burgmaier M¢hael B. Long
Division D~reaor
RE: Sanborn Creek Mine (C-81-022)
Technical Revision No. 29
I have completed a preliminary review of the Sanbom Creek TR-29 application. I reviewed the
application for technical adequacy of the surface water and reclamation cost estimate sections.
Following aze my comments.
2.05.3 aeration Plan -Permit Area
2.05.3(4) Ponds, impoundments, and diversions.
1. Figure 4.1 of the WESTEC report, "Sub Basins and Major Flow Routes", shows an area east
of Ditch D-4 which would appear to drain into D-4. The calculations do not include the azea,
so it would appear that WESTEC has determined that this area will not drain to D-4. Please
explain the field conditions which will or do currently route flow from this azea elsewhere.
Please see attached Figure 4.1 for a graphic representation of this concern.
2. Figure 4.1 also shows a Ditch D-3. The referenced feature appears to be the crown of the
refuse pile, and not a ditch. Please clazify or remove the Ditch D-3 label.
3. The designs for Ditch D1 do not include runoff from subwatershed Asb. Based on the
proposed construction plan for the refuse pile, it would appear that this area will drain to D1.
Please revise the ditch designs, of clazify the proposed pile construction if DMG's assumption
is incorrect. Please see attached Figure 4.1 for a graphic representation of [his concern.
4. The watersheds shown on Figure 4.1 appeaz to be inaccurate. Please see attached Figure 4.1,
which indicates the watersheds apparent to DMG. Unless OCM has information unavailable
to DMG which further explains OCM's demarcation, the figure should be revised.
5. Based on Figure 4.1, it appears that the undisturbed azea above the West Valley Fill, but
below the upland diversion, will drain to the refuse pile collection ditches. This being the
case, the collection ditches will also serve as a diversion for the pile, and so should be
designed for the 100-yeaz, 24-hour event.
6. The upland diversion ditch over the West Valley Fill is shown differently on several small
scale maps, so it is difficult to determine exactly where the constructed ditch initiates (east)
and terminates (west). Please provide a small scale map of the ditch location which clearly
indicates where the ditch starts and ends, so that DMG can verify the adequacy of the ditch
design.
7. Map E-3211 indicates the west end of the upland diversion ditch flows to Second Drainage.