2018-08-02_PERMIT FILE - M2016054

• Permit No: M2016054
• IBM Index Class Name: PERMIT FILE
• Doc Date: 8/2/2018
• Doc Name: Adequacy Review Response #3
• From: Blue Earth Solutiuons
• To: DRMS
• Email Name: AME
• Media Type: D
• Archive: No

REVISED EXHIBIT L
Reclamation Costs
In order to calculate maximum potential reclamation liability to the State, we have selected a point in
time where reclamation costs could be at a maximum. It is assumed that the time of maximum mining
disturbance will be at the end of Phase 1. During this scenario, mining is almost complete in Cell 6
and reclamation has included backfilling and grading side slopes in Cells 1 through 5 and most of
Cell 6 with overburden material stripped from the active mining areas. Since additional backfilling
with off-site material and groundwater pond and wetland development was expected to occur, no
topsoil or seeding has occurred on the backfilled side slopes. However, if off-site backfill material is
not available and water rights for permanent augmentation have not been secured, a soil-bentonite
slurry wall will be constructed around MA1 to separate alluvial groundwater from the below-grade
mining cells. No disturbance has occurred in MA2, MA3, or MA4.
The active mining area includes Mining Cell 6. In front of the active mining face, an area
approximately 100 feet wide by 500 feet long will have been pre-stripped in anticipation of mining
(1 acre). The pre-stripped area receives topsoil placement, final grading, and seeding for revegetation.
The active mining highwall is approximately 500 feet long and adjacent 500-foot long cell walls have
not yet been backfilled. Both the mining highwall and adjacent cell walls (1,500 linear feet total) are
backfilled and rough graded to 3H:1 V slopes(assume move 1-foot of material over entire grading area)
in preparation for topsoil placement, final grading, and seeding for revegetation.
Stockpiles for visual screening have been constructed along the west and south side of MA1. The
stockpiles contain approximately 35,000 cubic yards (yds) of overburden and topsoil material and
cover an area of about 5.5 acres. From stripping the active mining area, an additional 47,000 yds of
overburden and topsoil are available in other stockpiles on-site. Haul distances to use the stockpiled
topsoil for on-site reclamation ranges from less than 100 feet to over 1,500 feet, but averages only
about 300 feet.
Miscellaneous disturbed areas at the point of maximum disturbance will include the scale house and
staging area (5 acres), internal haul roads and the main site access road (3 acres), and stockpile areas
(5.5 acres). Additionally, the sediment pond area (1.9 acres) will not have been mined and will need
to be backfilled prior to final reclamation. These areas will be tilled in preparation for topsoil
placement, final grading, and seeding for revegetation. It is estimated that the combined area of these
disturbances will be approximately 15.4 acres.
If available, a minimum of 12 inches of topsoil or growth medium will be placed on all disturbed areas
following backfilling, scarifying, and/or rough grading. Enough topsoil should be stockpiled on-site
for reclamation. Final grading of the topsoiUgrowth medium is assumed to move 0.5 feet of material
over the entire grading area and will prepare the surface for seeding. In this scenario, only the Upland
Grass Seed—Soil Stabilization mix will be used. After initial seeding and the first season's growth, it
is estimated that approximately 20 percent of the seeded area will need to be re-seeded.
Each aspect is listed in the following table with associated disturbed area. Please refer to Exhibit D,
Pre-Mining/Mining Plan, for a listing of disturbed areas that total 49 acres. This estimate will follow
the same order as the listing in Exhibit D. Since all structures used in the mining operation are portable,
it is assumed that removal of the structures do not have associated costs.
Irwin/Thomas Mine
DBMS 112 Permit Application Adequacy Response Page 33