Current through Register Vol. 6, March 22, 2024
(1) In order for
SMES placer and dredge operators to meet the requirements of
82-4-305(1), MCA,
which requires that the small miner agree in writing not to pollute or
contaminate any stream, the department recommends the following best management
practices as minimally necessary to assure that operations do not result in
water quality violations:
(a) Mining
equipment should not be operated in a live stream or diversion, or in any
manner to cause bank caving or erosion of the bank of any live stream or
diversion.
(b) The amount of
make-up water should be limited to only the amount required to operate the wash
plant with spent water being recirculated back to the wash plant.
(c) Runoff from undisturbed areas should be
minimized through use of temporary berms.
(d) Adequate temporary berms and/or natural
undisturbed areas of vegetation should be placed or left as a buffer zone
around diversion ditches and live streams to prevent water quality degradation
and erosion of disturbed areas as a result of runoff from a ten-year, 24-hour
precipitation event.
(e) During
operations, care should be taken to protect streambanks and streambank
vegetation, streambanks, ditches, and diversions should be lined, riprapped, or
otherwise stabilized to prevent excess erosion.
(f) Roads should:
(i) be constructed to provide controlled
drainage, include culverts, waterbars, and slash filters necessary to
facilitate drainage and minimize erosion and be constructed to reduce
concentrated flows;
(ii) be located
on well-drained soils and located back from stream bottoms in order to provide
a buffer zone for preventing road sediments from washing into stream
channels;
(iii) be located outside
slide-prone areas characterized by seeps, steep slopes, highly weathered
bedrock, clay beds, concave slopes, hummocky topography, and rock layers that
dip parallel to the slope;
(iv) be
constructed to stabilize sloped exposed surfaces by seeding, compacting,
riprapping, benching, mulching or other suitable means prior to fall or spring
runoff;
(v) not be left in an
erosive condition over a winter season; and
(vi) be used only minimally during wet
periods and spring breakup when damage to the roads, which would result in
increased sedimentation, is likely to occur.
(g) Cut-and-fill slopes should be constructed
at a stable angle and stabilized by seeding, mulching, benching or other
suitable means during the same season as construction.
(h) Clearing, grubbing or logging debris
should not be placed in streams or used for diversions or cause water quality
degradation.
(i) Diversions and
impoundments should be sized to pass the ten-year, 24-hour precipitation event.
Diversions should be constructed with drop structures or energy dissipators
whenever necessary to prevent erosion. Diversion ditch berms should be sloped
to account for site-specific conditions, including soils, climate, height of
structure and existing natural slopes, and should be revegetated, riprapped, or
otherwise stabilized to minimize stream sedimentation.
(j) Before winter shutdown, a small miner
should take the following precautions:
(i)
Diversions should be sized to pass spring runoff (minimum ten-year, 24-hour
event) or streams should be returned to original channels.
(ii) Ponds should have adequate freeboard to
prevent over-topping during spring runoff from direct precipitation and
over-land flow. Whenever ponds are located within a flood plain and diversions
are not sized to pass the ten-year, 24-hour precipitation event, ponds should
be filled and reclaimed prior to onset of winter.
(iii) Soil, overburden, and tailings
stockpiles should not be placed near streams, unless necessary, and, or if so
placed, should be bermed at the toe to prevent erosion of sediments into
streams.
(iv) Fuel storage tanks
should be drained before winter shut down and should be drained and disposed of
in a manner which protects adjacent streams.
(k) Dikes should be constructed around fuel
storage areas to prevent a spill or discharge of fuel to any waters.
(2) A placer or dredge operator
who proposes a "project", as that term is defined in
75-7-103, MCA, on a perennial
stream, must comply with the requirements of the Natural Streambed and Land
Preservation Act, as amended, by obtaining a permit required by the appropriate
conservation district.
(3) In order
for a SMES placer or dredge operator to meet the reclamation requirements for
bond release, the following reclamation planning guidelines should be followed:
(a) A reclamation plan, or appropriate
waiver, for all roads is necessary.
(b) The postmine land use should be
identified and a reclamation timetable should be established.
(c) Soil should be salvaged from all areas to
be disturbed and should be stockpiled for use in reclamation.
(d) Site disturbances should be recontoured
to a minimum of 3:1 slopes or flatter by backfilling excavated material, unless
otherwise approved by the department as achieving comparable stability and
utility in the postmining landscape.
(e) Soil and approved soil amendments should
be redistributed over all areas disturbed by mining.
(f) The site should be seeded with perennial
nonweedy species.
(g) Stream
channels should be reconstructed, using coarse placer tails as necessary to
dissipate energy. Riprap, temporary synthetic erosion control, or biodegradable
revegetation fabrics in combination with permanent vegetation should be used to
stabilize streambanks, as necessary. Streams should be reconstructed with
grades, pools, and meanders comparable to premine drainage.
(h) Clays and fines available on-site should
be used to create a relatively impermeable layer beneath reclaimed channels and
floodplains.
(i) The floodplain
should be returned to original contour with the gravel, overburden, and soils
replaced to resemble their original stratigraphy.
This rule is advisory only, but may be a correct
interpretation of the law,
82-4-321, MCA; IMP,
82-4-305(1), (3),
(4), and (5),
MCA;