Draft Environmental Impact Statement for Roca Honda Mine

Chapter 3. Affected Environment and Environmental Consequences
Table 10. Estimated types and quantities of excavated materials at the Roca Honda Mine
Source of Material
Excavated
Ore from mine
Westwater Canyon
Recapture Member?
“Nonore” from mine
(mineralized but below
current ore grade)
Westwater Canyon
Recapture Member
Production shafts
(including nonmineralized
mine drifts, raises, etc.)
Vent shafts
(Some material will be
stockpiled at vent shafts,
when they are distant.)
Potential Groundwater
Contaminants
Uranium, radium, heavy
metals, acid drainage.
Uranium, radium, heavy
metals, acid drainage.
Acid drainage from thin coal
beds in Dilco Coal and
Gibson Coal Members of
Crevasse Canyon Formation
traversed by drilling of
vertical shafts. Historically,
has not been a problem in
Grants Mineral Belt.
Stockpile Disposition
Concrete-floored, walled
temporary storage ore bays;
12,500 tons capacity each; 5 bays
each in Sections 10 and 16.
216,900 cu. yd. stockpile in
Section 16; 4,050 cu. yd. stockpile
in Section 10. (Removed from
mine initially to create working
room; most of such material
would remain underground in the
mine.)
83,970 cu. yd. stockpile in Section
16; 51,970 cu. yd. stockpile in
Section 10; each mixed with vent
shaft materials.
26,230 cu. yd. stockpile in Section
16 (from 3 vents in Section 9);
20,750 cu. yd. stockpile in Section
10 from 2 vent shafts in that
section.
Location of “designated”
stockpiles uncertain.
Removed from site for
processing.
Most nonore to remain in
mine; that hoisted to
surface will be blended
with ore after transport
offsite, or returned to mine
(after character-ization), or
removed from site at the
end of mining.
Assuming characterization
sampling indicates no
problems, returned to
shafts and mine as
backfill; if problematic,
removed from site.
Controls Upstream of Water
Treatment Plant (WTP)
Downstream lined retention pond with
sump and lift station, plumbed to WTP;
sloped concrete floor in bay drains to
pond. Truck wash plumbed to pond.
Liner beneath stockpile to prevent
seepage into the ground surface;
drainage swales to prevent runon
erosion; storm runoff diverted to
downstream lined retention pond with
sump and lift station, plumbed to WTP.
Solids trapped by sump to be removed,
dried and transported off-site with ore.
Assuming characterization sampling
indicates no problems, drainage swales
where necessary to minimize storm
runon erosion. Material failing the
characterization sampling presumably
will be subject to controls analogous to
those applied to nonore for any time that
it remains onsite.
Dewatering wells Drilling fluids and cuttings
Dried in a second pit and Grading to minimize storm runon;
Development wells
from mud pit.
stockpiled.
contemporaneous reclamation.
Topdressing
None expected. 190,000 cu. yd. stockpile in Used in concurrent and Stabilized with grass cover; diversion
(localized stockpiles in
Section 16; 105,000 cu. yd. final reclamation.
ditches and/or wattles to minimize storm
distant areas)
stockpile in Section 10.
runon/runoff and erosion.
Subbase rock
None expected. 50,200 cu. yd. stockpile in Section Used for rip-rap and road Drainage swales to minimize runon
(excavated as part of
16, 9,400 cu. yd. stockpile in base in mine construction; erosion; wattles or other best
surface facility
Section 10.
used for fill in
management practices below piles to
construction)
reclamation.
minimize sediment release.
Notes: All stockpile volumes from mine operations plan, revision 1 (2012); 15 percent swell assumed for topdressing stockpile, 50 percent swell assumed for all other
stockpiles. “Swell” is the increase in volume of excavated material from its in-situ volume.
150 DEIS for Roca Honda Mine, Cibola National Forest