GENERAL45871

• Permit No: C1981011
• IBM Index Class Name: General Documents
• Doc Date: 3/1/1983
• Doc Name: PROPOSED DECISION AND FINDINGS OF COMPLIANCE
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

DESCRIPTION OF THE ENVIRONMENT
A general description of the existing environment, the operations and
reclamation plan is briefly summarized in the following sections.
Greater detail on items that were concerns during the review of the
permit application is provided in the Findings of Compliance section of
this document.
The topography of the general area is one of a semi-arid steppe region
with numerous dip slopes formed by differential erosion of the strata.
Elevations within the permit area range from 8000' on the NE-SW trending
ridgeline to 740U' alony the banks of Trout Creek as is shown on f4ap 2 of
this document. Within the permit area, rangeland is restricted to the
high plateau and the valley bottom, whereas, the steep-sided valley is
utilized by wildlife. Previous underground rnininy has occurred within
the permit area.
Geologically, except for surficial deposits, only the coal bearing
Cretaceous Mesaverde Group outcrops within the pe rnrit area. The Expanded
Columnar Section, Fiyure 1 of this document, shows the stratigraphic
location of the three coal seams to be mined. They are in ascending
order the Lower Pinnacle, The Upper Pinnacle and Zone 3 seams. All three
seams are part of the Iles Formation which is bounded by the Trout Creek
Sandstone Member above and the Tow Creek Sandstone Member below. Horst
and graben faulting has divided the permit area into three fault blocks.
The faults run towards the northwest and the coal dips lUo also to the
northwest.
Two categories of potential aquifers exist with
alluvial deposits associated with the stream of
groundwater stored in the Tow Creek Sandstone.
deposits line Trout Creek within the permit and
nearest alluvial well downstream of the mine is
away.
in the permit area:
Trout Creek and bedrock
Small, isolated alluvial
adjacent areas. The
over a mile and a half
The only regional aquifer within the permit area is the Tow Creek
Sandstone which is over 60U-feet below the coal seam to be mined. The
Trout Creek Sandstone, another regional aquifer in the general area, has
been eroded from above the coal seams to be mined. Because of the low
permeability of the interbedded shales and siltstones of the Iles
Formation, the Tow Creek Sandstone is recharged primarily where it
subcrops in the stream bottoms. The nearest subcrop of the Tow Creek
Sandstone to the permit area is approximately one mile upstream of the
mine. Low vertical permeability results in the formation of perched
aquifers in local lenticular strata. These perched aquifers recharge and
discharge within a short distance forming small seasonal springs and
seeps. These springs have been identified and are shown on the attached
map of the Regional Geology and Cross-Section, P1ap 2.