APPCOR11830

• Permit No: C1981014
• IBM Index Class Name: Application Correspondence
• Doc Date: 4/26/1982
• Doc Name: MAGPIE CREEK DIVERSION
• From: MLR
• To: CAROL RUSSELL
• Media Type: D
• Archive: No

STATE OF COLORA00 RICH IRD D. LA WA, Gm cram III ~1~~1~~1~11~~ 11~
DEPARTMENT OF NATURAL RESOURCES 999
D. Monte Pascoe, Executive Director
MINED LAND RECLAMATION
423 Centennial Building, 1313 Sherman Street
Denver, Colorado 80203 Tel. [phone]
~.
April 26, 1982
David C. Shelton
Director
TO: Carol Russell and Ed Bischoff
FROM: Jerry Zimpfer
RE: Magpie Creek Diversion
I have finally completed my review of the Afagpie Creek Diversion. Since infor-
mation concerning this diversion is scattered throughout the permit applications
and revisions for two different mining operations (Dorchester Coal and G.E.C.
Minerals)o I have attached a list of the materials reviewed in this assessment.
This dispersion of information has made review difficult. In addition, some
of the information necessary to judge compliance with the performance standards
has not been provided. Finally, neither operator has submitted a plan certified
by a qualified registered professional engineer, as required under Rule
2.05.3(4)(a)(ii). Both operators should resubmit their information as certified
plans.
As best I am able to determine, the diversion may be divided into three reaches;
an upper, middle and lower reach. The upper reach is located in and adjacent to
the Ibrchester Coal mine permit area. The channel was designed to contain the
100-year event. It was constructed with a more gentle slope than the original
stream. Rt one time, the diversion ended at the boundary of the Dorchester permit
area, where flow cascaded into the valley below.
The middle reach was constructed at a later time by G.E.C. 1?inerals, Inc. This
reach crosses the G.E.C. permit area, connecting the Dorchester diversion with an
unnamed tributary to Magpie Creek. This reach consists of two parts, a steep
transition, and a designed channel between the transition and the haul road
culvert. The transition is hydraulically steep, and is sized to the 10-year
event with the floodplain handling the remainder of the 100-year event. The
tiptop used is sized to the 10-year event, and "may experience some damage during
the 25-year and 100-year events." The design event for the design channel has
not been provided. The diversion then flows through a culvert beneath the G.E.C.
haul road. The culvert is somewhat undersized and requires a headwater depth
of 17 feet in order to pass the SO-year peak discharge. Presumably, the road and
culvert are temporary and would be removed upon reclamation.