GENERAL33488

• Permit No: C1981012
• IBM Index Class Name: General Documents
• Doc Date: 6/1/1984
• Doc Name: PROPOSED DECISION & FINDINGS OF COMPLIANCE for PR1
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

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The location and geometry of the Purgatoire River does not appear to be
related to the occurrence of fractures, jointing, or faulting. There does not
appear to be any direct hydrologic connection through fractures between the
stream-alluvial system and the Allen coal seam. The mine workings maps for
the New Elk Mine do not show fault systems beneath the surface streams. This
further supports the contention that surface stream valleys are not
fault-controlled. Faults located below and adjacent to overlying streams do
not contribute point source mine inflows.
The Allen and Maxwell seams are confined artesian aquifers in the general
area. The coal seams are confined by the shales and siltstones of the
overlying Raton formation and the underlying Raton and Vermejo Formations.
Ground water flow in the coal is through coal cleats and minor fractures. The
coal seams are recharged by old mine workings and oxidized coal/burn zones
along the coal outcrops, and by surface/alluvial systems at the coal subcrops
in stream valleys. The major recharge area for the coal seams adjacent to the
mines are located just west and southwest of the existing New Elk Mine
workings. Both the Allen and Maxwell coal seams lie more than 300 ft. below
the Purgatoire River. The coal seams discharge to the center of the Raton
Basin. No springs or seeps have been identified which discharge from the coal
seams. There are no water wells completed in the coal seams.
Water quality data from well LA 221A is believed to be representative of the
undisturbed waters in the coal seam. Water pumped from well LA 264 is
believed to be produced from a thin fracture zone in the overburden at a depth
of approximately 72 feet, as discussed previously. Though the water sample
from this well represents a zone high in the overburden, the composition and
total concentrations are very similar to the corresponding parameters from
well LA 221A completed in the coal. This observation suggests a uniform water
quality throughout the profile. Both the coal water and the overburden water
show a similar chemistry. The water is a sodium-bicarbonate type water. The
coal seam has higher concentrations of carbonate, total iron, total manganese,
total zinc, and a slightly higher pH than found in the overburden water.
Sulfate concentrations in the coal seam were slightly lower than in the
overburden. Data on other trace metal concentrations were not provided.
C. Ground Water - Alluvial Aquifers
Investigation of the alluvial ground water along the Middle Fork and main stem
of the Purgatoire River was conducted by drilling eight holes (3 at the New
Elk Mine, and 5 at the Golden Eagle Mine) through the alluvium to bedrock and
excavating several backhoe pits. Ground water was encountered only in the
alluvium in direct contact with the river. The thickness and lateral extent
of the saturated alluvial material is limited. The water table depth in the
alluvial wells ranged from about 4 to 5 feet below the ground surface, and was
largely controlled by the water level in the river.
Drill holes and backhoe pits encountered no ground water in the strath
terraces and no prominent springs were observed near the contact between the
strath alluvium and bedrock. This indicates that the strath terraces do not
contain a water table aquifer and that these deposits are not hydrologically
connected to the alluvial terraces adjacent to the Middle Fork and mainstem of
the Purgatoire River.