Draft Environmental Impact Statement for Roca Honda Mine

Chapter 3. Affected Environment and Environmental Consequences
Like alternative 2, impacts of alternative 3 on both geology and soils would be adverse but not
significant. However, alternative 3 would result in a smaller extent of disturbed soils than
alternative 2, 155 acres versus 218 acres.
Cumulative Effects
The cumulative effect on surface and subsurface geology considers the impacts of the two action
alternatives when added to past, present, and reasonably foreseeable future human actions in the
area. Cumulative effects analysis requires spatial and temporal boundaries. For geology and soils,
a logical spatial boundary is the Grants Mineral Belt, an important uranium-producing region
primarily in Cibola and McKinley Counties of western New Mexico. The initial temporal
boundary begins with the latter half of the 20 th century and continues to approximately 2050.
For more than half a century, the Grants Mineral Belt in which the proposed Roca Honda uranium
mine is located has been subjected to a substantial amount of mining exploration and
development, both surface and underground; a number of these projects are cited in chapter 2.
Geologic landforms have also been altered by road cuts, logging, transmission lines, pipeline
construction, and other human activities and structures. Because the proposed action (alternatives
2 and 3) would not permanently modify the ground surface at the mine site, it would not
contribute to these long term cumulative effects on the area’s surface geology. However, the act
of extracting uranium ore and backfilling mined rooms with waste rock rubble hundreds of feet
underground would permanently alter the stratigraphy (order and relative position of native rock
strata) of these subsurface zones, adding to similar effects from many other underground mines in
the region.
The cumulative effect on soils considers the impacts of the proposed project when added to soil
disruption impacts from activities at the Roca Honda Mine site itself and the Mt. Taylor area,
ranging from the mid-1900s to the present.
Past impacts to local soils have occurred from road construction and use, including road cuts
between NM 605 and the mine site from private roads and Forest Service roads and Forest
Service and other 4-wheel roads across Sections 9, 10, and 16. Long-term livestock grazing in the
vicinity may have caused some degree of soil compaction and erosion (from removing plant
cover). Constructing and maintaining the power line that crosses Section 16 probably caused
some soil disturbance, compaction, and erosion. Additional soil impacts in the vicinity of the
project resulted from surface disturbances associated with past uranium exploration activities that
included drill holes, trenching, and exploratory mining in the middle to late 1900s. Exploratory
drilling has already occurred as part of the proposed action, as well as earlier by a previous
mining company in an effort to discover and characterize uranium ore grade. As indicated above,
because soil impacts would be mitigated through BMPs and implementation of the reclamation
plan, cumulative impacts to soils in the immediate mine area would be at most minor.
Although the project area represents approximately a tiny fraction of percent of the Mt. Taylor
Ranger District, in combination with past, present, and foreseeable future actions, it would result
in the incremental increase in impacts to soils in the Cibola National Forest. Other potential mine
exploration and development projects in the vicinity of the proposed action include the proposed
La Jara Mesa uranium mine located 8 miles south of the site and others listed at the end of
chapter 2. The La Jara Mesa proposal would entail less than 20 acres of surface disturbance, and
would contribute to the soil impacts from mining in the Mt. Taylor area. A separate EIS has been
110 DEIS for Roca Honda Mine, Cibola National Forest