REV02482

• Permit No: C1981010
• IBM Index Class Name: Revision
• Doc Date: 5/8/1989
• Doc Name: HYDROLOGY ISSUES OF TRAPPER MINE C-81-010 TR 44 1988 ANNUAL REPORT
• From: MLRD
• To: TONY WALDRON
• Type & Sequence: TR44
• Media Type: D
• Archive: No

• • III IIIIIIIIIIIIIIII
STATE OF COLOR~v
Roy Romer, Governor
DEPARTMENT OFNATURALRESOURCES
MINED LAND RECLAMATION DIVISION
FRED R. BANTA, Director
DATE: May 8, 1989
T0: Tony Waldron
~;L
FROM: Bill Crick
RE: Hydrology Issues of Trapper Mine (C-81-010) Technical Revision 44
(1988 Annual Report)
The principle hydrology issues are a) the proposed construction of up to 43
additional stock ponds on reclaimed lands, b) granting permanent status to
water harvesting ditches which convey runoff to these ponds, c) approval of
the permanent drainageway construction work done so far, and d) reduction in
quarterly groundwater monitoring requirements.
The planned stock pond construction is scattered through the East Buzzard,
Coyote, No-Name, and Johnson drainages. As part of MR 52, the Division and
the Operator agreed on a minimum pond drainage area of ten acres per pond. In
certain areas of the mine (between the current Derringer Pit and the Coyote
drainage, parts of the Johnson drainage south of Ashmore Pit) this density
will have been reached following 1989 construction, and no more ponds should
be necessary in these areas. Following construction, the operator will submit
a memo from the SCS confirming that the ponds were designed and constructed
according to their guidelines.
The water harvesting ditches leading to the approved stock ponds should also
be given permanent status. They are useful as water collection structures for
the stock ponds, and appear to have been very effective in reducing gully
erosion and downstream peak flows in reclaimed areas. The mine has realized
dramatically lower sediment pond cleaning expense, and areas which were
previously susceptible to severe gullying are now relatively stable. The
drainage network in the D Pit reclaimed area, including reconstructed
drainages, stock ponds, and water harvesting ditches, appears from field
examination to be functioning well. Page 3-151 of the Trapper permit
application describes the repair procedures they will follow should gullying
due to infilling and/or breaching of the ditches occur. The Division should
stress that only those ponds on map 6-1 (dated February 23, 1989) and ditches
on Map 3-1 are approved for permanent status.
The permanent reconstruction of Coyote drainage was examined in the field in
April, and appears to have functioned well during the spring runoff.
Extensive erosion-control treatments have also been applied in the No-Name,
Johnson, Coyote tributary, and Johnson tributary drainages.
215 Centennial Building, 1313 Sherman Street Denver, Colorado 80203.2273 Tel. [phone]