PERMFILE51443

• Permit No: C1981031
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: Section 3: Rule 2.04
• Media Type: D
• Archive: No

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2.04.5 GENERAL DESCRIPTION OF HYDROLOGY AND GEOLOGY
' 1.0 Surface Water
The Pryor Mine is in the Santa Clara Creek drainage basin, a tributary to
the Cucharas (Figure 2.04.5.1) River. The Cucharas River flows generally
northeast and joins the Huerfano River about twenty-five miles south of
Pueblo, CO. The Huerfano River, a tributary of the Arkansas River, has .been
assigned Hydrologic Unit No. 11020006 by the U.S. Geological Survey.
Headwaters for both the Cucharas River and Santa Clara Creek are in the
Spanish Peaks. They are ephemeral streams with some snowmelt runoff in the
spring. Most flows occur in response to significant rainfall events.
Runoff from the Pryor Mine permit area flows into two tributaries of
Santa Clara Creek, Black Hawk Canyon and Pryor Canyon (Figure 2,04,5-2). Most
of the permit area drains into the mainstem of Pryor Canyon or a small,
unnamed southern tributary to Pryor Canyon. The southernmost part of the
permit area is in the Black Hawk Canyon drainage basin. No runoff data or
water quality analyses are available for either Pryor Canyon or Black Hawk
Canyon. Estimates of peak flows and runoff volumes are presented in section
2.04.7(2) of this report,
•
2.0 Geology
The permit area lies in the northern flanks of the Raton Basin coal
region (Figure 2.04..5-3 ). The coal deposits in this part of the basin are
part of the Walsenburg coal field,
The Raton Basin is a structural trough that was subjected to repeated
marine transgressions and regressions from the Pennsylvanian period to early
Eocene time resulting in the deposition of a succession of fine-to
coarse-grained sediments and carbonates as shown in Table 2.04.5-1, The
Pierre Shale of Upper Cretaceous age is the oldest formation exposed in the
general area of the mine (see Map 2 of Permit application). The upper part of
this formation is dominated by sandstone beds that intertongue with the
overlying Trinidad Sandstone. This was followed by the shallow water, deltaic
and swamp deposits of the Vermejo Formation. Most of the past and present
coal mining activity in southeastern Colorado has been concentrated in the
coal beds within the Vermejo Formation, Coal beds also exist in the overlying
Raton Formation. The Poison Canyon Formation of Paleocene age outcrops west
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