PERMFILE69598

• Permit No: C1981041A
• IBM Index Class Name: Permit File
• Doc Date: 5/13/2002
• Section_Exhibit Name: Tab 19 Probable Hydrologic Consequences
• Media Type: D
• Archive: Yes

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• Effects on Groundwater from the Roadside North Portal
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Dewatering, if any, would drain undeveloped or noncritical zones immediately
adjacent to the coal seam. The RSN will have minimal impacts to the
groundwater resources of the area. Mining in Sections 2t3, 29, 32 and 33 will
be at an elevation higher than the river. Continued in-flows from these areas
beyond closure of the mine could create a higher water level in the mine than in
the adjacent alluvial water table and have the effect of recharging the alluvial
groundwater. The adjacent Cameo mine was primarily mined in Sections 28
and 33 above the river level. The mine was dewatered when the RSN was
developed east and north of the old mine and continues to be dewatered by the
RSN. It is estimated that less than 10 gallons per minute is being dewatered
from the old Cameo mine through seepage into the RSN. Similar inflows are
expected from other mining above the river. These small inflows will have
minimal affects upon the groundwater. The mined out area and the adjacent
• rubblized zone will result in an area of high porosity. This increased porosity
will have the effect of rapid dewatering above the resulting mine water level and
higher storage capacity below the water level of the mine.
Effects of Groundwater Discharge on the Surtace Water
Another probable hydrologic effect of mining is discharge of mine water to the
Colorado River. Powderhorn Coal Company has an existing NPDES (National
Pollution Discharge Elimination System) permit through the Colorado
Department of Health (i.e. Permit No.CO-0027146). Powderhorn Coal
Company may discharge mine water from four locations: Roadside South
Portal supply water overflow (outfall 001), Roadside South Portal discharge at
the Northwest Intake (outfall 002), Roadside South Portal discharges at the 2
West Portals (outfall 015), and Roadside North Portal discharge (outfall 004).
In addition, Powderhorn has outfalls designated for each of the sedimentation
ponds, and water quality samples will be taken if and when there is a
• 19-6 (New 3/1 /96)