GENERAL42646

• Permit No: C1981014
• IBM Index Class Name: General Documents
• Doc Date: 2/1/1991
• Doc Name: PROPOSED DECISION & FINDINGS OF COMPLIANCE FOR PR1
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

As a part of Permit Revision No. 1, EFCI proposed a change in the mine's
reclamation plan involving the Magpie Creek Diversion. This diversion was
constructed in 1982 to temporarily divert upland drainage around the mine
facilities area. Prior to construction of the mine, Magpie Creek flowed
through what is now the facilities area and left the north end of the permit
area near the present location of Sediment Pond No. 5. The diversion was
designed to carry runoff from a 10-year, 24-hour storm, as required for
temporary stream channel diversions (Rule 4.05.4(2)(b)).
In the permit revision, EFCI proposed to make Magpie Creek Diversion a
permanent structure. The Division raised several adequacy concerns regarding
permanent diversion of the stream channel. In order to satisfy the
requirements of Rule 4.05.4(4) regarding permanent stream channel diversions,
the Division asked EFCI 1) to demonstrate that the constructed drainage
channel would remain in dynamic equilibrium with the drainage basin system
(as required by Rule 4.05.4(4)) and, 2) to submit design plans fora stable
diversion in compliance with Rule 4.05.4(2). In response to these concerns,
EFCI conducted studies of the affected drainage basins and demonstrated to the
Division's satisfaction that the basin receiving water from the diversion
would be capable of handling the diverted flow. However, there are still a
number of unanswered design questions. Therefore, the Division finds that the
requirements of Rule 4.05,4 have not been met and does not approve a permanent
diversion of Magpie Creek.
The temporary diversion of Magpie Creek has functioned adequately during the
eight years since its construction. Little maintenance work has been
required. Flows in the channel are very infrequent.
The original Findings Document indicates that final design details for the
reconstructed Magpie Creek channel were to have been submitted by
Dorchester Coal following permit approval. No design has been submitted,
other than a plan view and longitudinal profile of the channel. Bond
calculations have been based on conservative assumptions of material
requirements for channel reconstruction. In order to ensure that an approved
channel design is included in the permit, the following stipulation is
included here:
Stipulation No. 17
WITHIN 120 DAYS OF PERMIT REVISION APPROVAL, THE APPLICANT SHALL SUBMIT
DESIGNS FOR THE MAGPIE CREEK CHANNEL IN COMPLIANCE WITH THE REQUIREMENTS
OF RULE 4.05.4. THE DESIGNS SHALL INCLUDE PLAN VIEWS, LONGITUDINAL
PROFILE, CROSS-SECTIONS AND CHANNEL PROTECTION DETAILS IN ORDER TO MEET
THE REQUIREMENTS OF RULE 4.05.4(4).
With acceptance of the stipulations above, the operation is in compliance with
the requirements of this section.
XVII. Backfilling and Grading - Rules 2.05.3(6)(b), 2.05.3(9), 2.05.4(2)(a
There are no changes in this section, The operation is in compliance with the
requirements of this section.
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