APPCOR10365

• Permit No: C1987072
• IBM Index Class Name: Application Correspondence
• Doc Date: 5/14/1987
• Doc Name: LA PLATA COAL DRAFT FINDINGS
• From: MLRD
• To: PETER O CONNOR
• Media Type: D
• Archive: No

La Plata Coal Draft Finings - 7 - May 18, 1987
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 of this document). This demonstrates that sufficient water
is available for subirrigation purposes. Furthermore, the identified land use
on the AVF is primarily pasture land with occasional hay production. The
essential hydrologic functions that supply water to the AVF are both flood
irrigation and subirrigation as described above. The applicant has not
presented any information regarding the significance of the AVF 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 of this document).
2) The quality of the alluvial aquifer could be impacted by drainage
from access/haul roads which cross the AVF. 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 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 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.
Upon examining the proposed and existing sediment control facilities at each
mine site, as well as data obtained from an alluvial monitoring point, the
Division has determined that each site has been designed to minimize impacts
to the AVF. Therefore, the Division makes the following findings:
1. Pursuant to Rule 2.06.8(5)(a)(i)(A)(1), the current and proposed
operations will not interrupt, discontinue or preclude farming on
the Alluvial Valley Floor;
2) Pursuant to Rule 2.06.8(5)(i)(A)(II), the current and proposed
operations will not materially damage the quantity or quality of
the surface or ground water systems which supply the Alluvial
Valley Floor;