GENERAL30444

• Permit No: C1987072
• IBM Index Class Name: General Documents
• Doc Date: 6/1/1987
• Doc Name: PROPOSED DECISION AND FINDINGS OF COMPLIANCE
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

information to dispute this finding has been submitted to the Division,
therefore, the AVF determination remains.
Field observations by Division personnel and information contained in permit
applications indicate that small areas of unconsolidated stream-laid materials
are present in adjacent drainages. With the possible exception of Roberts
Canyon, these areas are generally not extensive enough to meet the size
criteria of AVF's.
The Hay Gulch Irrigation Ditch, which parallels La Plata County Road 120,
provides water for flood irrigation purposes in the vicinity of present mining
activity. It has been demonstrated that the naturally occurring water table
of the AVF varies from above ground surface to as much as eight feet below the
surface (Section V-Ground Water Hydrology of this document). This
demonstrates that sufficient water is available for subirrigation purposes.
Furthermore, the identified land use on the AVF is primarily pastureland with
occasional hay production. The essential hydrologic functions that supply
water to the AVF are both flood irrigation and subirrigation. The applicant
has not presented any information regarding the significance of the AYF to the
individual farming units; therefore, the AVF must be considered significant
for purposes of this findings document.
The potential for impact to the AVF from mining activity is minimal, however,
three potential impacts have been identified:
1) Water which has collected in sediment ponds could infiltrate into
the AVF at each mine site. The potential for adverse impacts to
occur is limited due to the relatively small quantities of water
impounded by each pond and by the great quantity of water moving
through the alluvial aquifer (Section V-Ground Water Hydrology of
this document).
2) The quality of the alluvial aquifer could be impacted by drainage
from access/haul roads which cross the AVF (e. g.: King Coal Mine
road). It is thought that the potential for significant
degradation due to access/haul road drainage is minimal. This is
again due to the probability of immediate dilution of this drainage
within the AVF, as discussed above. This is especially significant
when considering the total area of the AVF in respect to the total
area of the one present and one proposed (Blue Flame Coal)
access/haul road crossing the AVF.
3) The quality of the alluvial aquifer could be impacted by leachate
from the proposed La Plata No. 1 Mine leach field. The probability
of significant degradation occurring to the AVF is minimal. Due to
the limited work force at the mine site, only small quantities of
effluent are expected. Dilution of this effluent should occur
rapidly. Finally, the nitrite/nitrate provided to the alluvial
system could potentially benefit agricultural production. The
monitoring of the leach field through a downgradient ground water
well will indicate any impact. Should any impact occur appropriate
steps will be taken to mitigate the effect.
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