2017-02-03_PERMIT FILE - C1980004 ‎(2)‎

• Permit No: C1980004
• IBM Index Class Name: Permit File
• Doc Date: 2/3/2017
• Section_Exhibit Name: Volume I Sections 2.03 & 2.04
• Media Type: D
• Archive: No

2.04.7 Hydrology Description
(1) Ground Water Information
(a)(i)(ii)(iii), (iv) and (b)
Within the regional area, there is alluvial and bedrock groundwater.
Alluvial groundwater occurs in unconsolidated deposits of sand and gravel
formed along drainage courses. The alluvial aquifer is capable of yielding
sufficient water for domestic and stock water uses, and as irrigation water
near the Colorado River where the alluvial aquifer is broad and the
saturated thickness is greater. Groundwater also occurs in consolidated
sandstone, siltstone and shale of the Mesaverde Group. The McClane
Canyon Mine extracts coal from the Cameo coal zone, which is in the
lower portion of the Mesaverde Group. Based on borehole drilling logs
and monitoring wells near the mine and hydraulic testing elsewhere in the
Piceance Basin, the Mesaverde sandstones and coal beds are tight and
yield small quantities of water. Underlying the Mesaverde Group is the
Mancos Group, which is comprised predominantly of marine shale,
mudstone and claystone with interbedded sandstone, siltstone, and
limestone. Some of the sandstone maybe water -yielding; however, the
Mancos Group is a confining unit and a barrier to vertical and lateral
groundwater flow (Robson and Banta 1995).
Alluvial Groundwater
Alluvial groundwater near the operation occurs in Quaternary age sands
and gravels within the East Salt Creek drainage west of the mine.
Saturated alluvium within the permit and adjacent area is limited to the
headwaters of East Salt Creek. The width of the alluvial valley ranges
from as little as approximately 200 feet in the headwaters to as much as
2,000 feet south of the mine near the Colorado River.
Groundwater in the alluvial drainages occurs primarily under unconfined
conditions. Localized confined conditions may occur where clay layers
are laterally extensive. The direction of groundwater flow in the alluvium is
generally parallel or sub -parallel with the axis of the drainage. The
groundwater gradient is expected to be similar to the slope of the land
surface within the alluvial valleys ranging from 0.02 to 0.03 in the upper
reaches decreasing to between 0.01 and 0.015 in the lower reaches.
PR -02 2.04-16 03/13