REV99894

• Permit No: C1981022
• IBM Index Class Name: Revision
• Doc Date: 2/20/2001
• Doc Name: MINOR REVISION 56 CBM-1 DRILL PAD SANBORN CREEK MINE
• From: DMG
• To: SANDY BROWN
• Type & Sequence: MR56
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Deparlmern of Natural Resources
iii iiiiiiiiiiiii iii
999
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
DATE: February 20, 2001
TO: Sandy Brown
DIVISION OF
MINERALS
GEOLOGY
RECLAMATION
MINING•SAFETY
Bill Owens
Governor
Greg E Watcher
Execmrve Director
Michael B. LOng
FROM• Joe Dudash ~~ Division Director
RE: Minor Revision No. 56, CBM-1 Drill Pad, Sanborn Creek Mine
At your request, I reviewed the hydrology issues concerning MR-56. Most of the design work is
conservative and is acceptable to the Division. However, it appears that the operator will need to
redo some of the design considerations. Ihave put a copy of this memo on the M drive at
M:/coal/sbl/mr56memol. The following are my comments:
The hydrology design does not take into account the drainage area upgradient of the pad area.
That area appears [o be quite a few acres in size. The hydrology design either should include
the runoff from this upland area or an upland diversion ditch should be included in [he design
and in the field to keep [his runoff off of the disturbed area. Please modify [he hydrology
design and maps accordingly.
2. It is the Division's understanding that the drill pad will be an active site for some time. It
may be months before the second and third holes are drilled. Ordinarily, the Division does
not require Sedcad designs for a project that has a short active period. The Division assumes
that proper sediment control will be employed during the active phase, without the need for
actual hydrology designs, unless a sedimentation pond is being used for sediment control.
However, since this site will remain active for a long time, it is appropriate to submit these
Sedcad designs.
;;~.. ti rn cc,,,~~.ahM iF a0 rt:,ll~~.
However, Sedcad designs should also be submitted that reflect the post rcclamatiet~period.
These designs should reflect the field condition when the mud pits have been filled in, the
baze dirt areas and topsoil stockpiles have been seeded and mulched, and the seed has started
[o take, and any of the pad area has been graveled, if that is the plan. Please submit a Sedcad
design to reflect this post-re~e}+~at-ierrl~iasg•
dr,lhr,~ rn.A'i }i en.
3. Since the berm is considered a hydrologic structure, a design should be submitted to show the
height of the berm and that the height of the berm will be sufficient to channel runoff,
without being overtopped. The design should take into account a freeboard of 0.3 feet. Please
submit this berm design.