2018-09-04_REVISION - C1980007 ‎(11)‎

• Permit No: C1980007
• IBM Index Class Name: Revision
• Doc Date: 9/4/2018
• Doc Name: Proposed Decision and Findings of Compliance
• From: DRMS
• To: CAM Mining, LLC
• Type & Sequence: PR15
• Email Name: LDS
• Media Type: D
• Archive: No

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the South of Divide area and the subsidence magnitudes of Minnesota Creek
(as set forth in Exhibit 32 of the permit application); conducting hydrologic
monitoring (as set forth in Exhibit 71 for the South of Divide area, and in
Section 2.05.4 of the permit application for other areas); and augmenting any
water supply losses, including any mining-caused losses from Minnesota
Reservoir or the Deep Creek Ditch (as set forth in the Augmentation Plan
contained in Exhibit 52 of the permit application).

To detect subsidence impact, MCC has committed to monitoring the
following items: wetland vegetative health in the South of Divide area;
subsidence magnitudes of Panel El, Minnesota Creek (as set forth in Exhibit
32 of the permit application), and the Deep Creek Ditch (Section
2.05.6(6)(f)(iii)(C)(IV); surface and ground water flow and quality (as set
forth in Exhibit 71 for the South of Divide and Dry Fork lease areas, and in
Section 2.05.4 of the permit application for other areas). MCC has committed
to performing periodic visual inspections of subsidence impacts to structures
and conducting annual traverses recently mined areas. The results of
monitoring and inspections are to be submitted to the Division in periodic
reports as required by the Rules and the permit application.

MCC predicts rock falls or landslides may occur as a result of mining-induced
seismicity. To mitigate these impacts, MCC has committed to placing
warning signs where appropriate, conducting visual inspections of possible
rock fall and landslide areas, and removing any blockages of roads or
drainages caused by mining-caused rockfall or landslides.

2. Section 2.05 and Map 53 of the permit application provide information on the
perennial portion of Sylvester Gulch. The information was submitted in TR-25. The
information includes: depth of mining, height of mining, lithologic description of
overburden, and a map of the workings. Based on this detailed subsurface
information, the Division previously found that MCC’s proposed undermining of the
portion of the perennial portion of Sylvester Gulch will not cause material damage to
the main channel or east fork of Sylvester Gulch. (4.20.4).

Flow in Deep Creek in the Dry Fork lease area is perennial. Two of the operator's
B seam panels previously undermined the segment of Deep Creek that is
downstream from the Dry Fork lease area. Detailed underground information
provided in the PR-12 submittal and in the existing permit application (workings
maps, depth of mining, height of mining, and the lithologic description of
overburden) indicates subsidence may cause localized temporary pooling and
temporary accelerated erosion in the channel. Exhibit 55 B contains a prediction
that undermining of Deep Creek in the Dry Fork lease area by panels 3 and 4 will
tilt the 7.3% pre-mining slope of the stream by 1.9%, an amount too small to
significantly change the hydraulic characteristics of the stream. Exhibit 55 B
predicts mining effects on Deep Creek in the Dry Fork lease area will be the same
as the previously undermined section of Deep Creek which had no detectable
impacts, indicating the depth to mining in the Dry Fork lease area (which is similar