GENERAL31415

• Permit No: C1981038
• IBM Index Class Name: General Documents
• Doc Date: 9/3/1992
• Doc Name: PROPOSED DECISION & FINDINGS OF COMPLIANCE FOR FEDERAL COAL LEASES
• Permit Index Doc Type: Other Permits
• Media Type: D
• Archive: No

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fie entire Roatcap Creek system contains no alluvial deposits due to the steep
topography and overall drainage gradient. One irrigation ditch, the Overland
Ditch, follows the topographic contours between the upper Roatcap Creek
Drainage Basin to the upper West Muddy Creek Drainage Basin.
There are many springs and numerous ponds within the permit and hydrologically
adfacent area of the Orchard Valley Mine. It appears that most of these
springs and ponds are intermittent and depend upon seasonal precipitation and
long-term weather patterns. The source of most of the springs appears to be
related to landslide complexes, faults and fractures, areas of
colluvium/alluvium where ground water has accumulated, or the discharge points
at the contact of the Rollins sandstone with the lenticular sandstones of the
Mesa Verde Formation.
PROBABLE HYDROLOGIC CONSEQUENCES OF THE ORCHARD YALLEY MINE
Effect of the Orchard Valley Mine -Ground Water
The Orchard Valley Mine has the potential to affect ground waters in three
wdys--degradation of water quality, mine consumption of water, and dewatering
of insignificant bedrock aquifers. Each of these cases will be discussed in
detail in the following paragraphs.
Degradation of ground water quality could occur in three locations. The train
loadout and auxiliary coal stockpile are located on an alluvial terrace of the
North Fork of the Gunnison. Runoff infiltration could result in the
dissolution of salts. Colorado Westmoreland has installed three monitoring
wells and has not detected arty significant water quality changes. The
Division has expressed same concern about the narrow band of alluvium found
downdip of the underground waste development stockpile. Colorado Westmoreland
has installed a well (Node 22) and is monitoring that location for impacts.
Lastly, there is a slim probability that subsidence-related impacts to springs
might result in the modification of springs water quality due to a change in
routing of the water. CWI is monitoring springs in currently affected areas
quarterly for mafor cations and anions, and no changes have been detected.
Water utilized for mine operations is obtained from a well in the Steven's
Gulch well field. Consumption from this alluvial-colluvial deposit is
measured with a wellhead gage. Water quality information is also collected
and reported to the Division. In 1986, CWI produced 333,292 tons of coal and
consumed 8700 gpd while in operation. In 1983, CWI produced 1.3 million tons
of coal and consumed 27,400 gpd. There has not been arty detectable impact to
the groundwater/surface water regime in this well field since they initiated
pumping at the site.
Dewatering will occur at the Orchard Valley Mine but will be insignificant in
extent. Mine inflows may be derived from fractures associated with perched
aquifers within the overlying Mesa Verde, surficial alluvial-colluvial
sediments, and stream flows associated with fracture systems as well as from
dewatering of the coal aquifer itself. In 1983, approximately 300,000 gallons
of water flowed into the mine from perched, discontinuous, water-bearing
sandstones overlying the "D" seam. A Division inspection in March, 1986,
documented inflows of 200 gallons per day. This inflow gradually slowed once
this perched aquifer was completely dewatered.