GENERAL30475

• Permit No: C1981019
• IBM Index Class Name: General Documents
• Doc Date: 5/4/2007
• Doc Name: Proposed Decision & Findings of Compliance for PR2
• Permit Index Doc Type: Findings
• Media Type: D
• Archive: No

Lower segment of Wilson Creek valley deposits mapped as Qa on Map 11A, extending
from lower boundary of "Area Affected by 1985 Erosion and Mass Wasting Event", in
SE'/o of Section 21, T4N, R93W downstream for the length of the valley.
Lower Elkhorn Creek valley deposits mapped as Qa on Map 1 lA.
Jubb Creek and its tributary valleys with deposits mapped as Qa on Map 11A.
Stream Valley Segments Determined Not to be Alluvial Valley Floors
Taylor Creek was investigated in the early 1980s in association with initial permitting of
Colowyo, and was determined not to be an alluvial valley floor. The West Fork of Good Spring
Creek was investigated in association with PR-2, and was determined not to be an alluvial valley
floor. A middle segment of Wilson Creek within the expanded permit boundary was investigated
in association with PR-2. The segment had originally been designated an alluvial valley floor,
but based on information presented in the PR-2 application and field reconnaissance by Division
staff, the Division has determined that the segment no longer meets the alluvial valley floor
criteria. These valley segments are discussed in more detail below.
Taylor Creek
Lower Taylor Creek, a tributary to Wilson Creek, contains small areas with alluvial deposits but
does not contain enough water to provide for sub-irrigation of croplands. Taylor Creek, which
will be mined in ifs upper reaches, is therefore not considered an alluvial valley floor.
West Fork Good Spring Creek
West Fork of Good Spring Creek contains a narrow band of alluvial deposits. The alluvial
deposits along the West Fork extend approximately two miles upstream from the confluence with
the East Fork (which forms the main stem of Good Spring Creek). Mining of the South Taylor
pit within the southern portion of the proposed PR-2 permit expansion area will occur within the
watershed of the West Fork, and the pit bottom orientation is such that ground water from the pit
will eventually discharge into the West Fork. It is projected that water quality along lower
segments of the West Fork will be degraded by discharge of this relatively high salinity spoil
water.
Based on reconnaissance investigation performed by the operator and described on page R2-]26
of Volume 12, and supplemental adequacy response submittal information, and based further on
site visits conducted by Division staff, the Division has determined that the West Fork Good
Spring Creek valley does not meet the alluvial valley Floor criteria.
Reconnaissance investigation revealed narrow, intermittent reaches of alluvium, with the valley
bottom constricted in various locations by sheet wash and debris flows from the steep south
facing slopes. The valley bottom ranges from tens of feet wide to a maximum width of
Proposed Decision and Findings of Compliance 4 May 2007
Permit Revision 02 Page 63