2020-06-29_PERMIT FILE - M2020007 ‎(3)‎

• Permit No: M2020007
• IBM Index Class Name: Permit File
• Doc Date: 6/29/2020
• Doc Name: Adequacy Review Response #3
• From: Environment, Inc.
• To: DRMS
• Email Name: ECS
• Media Type: D
• Archive: No

L.G. Everist, Inc Ragsdale Reservoirs
M-2002-007 June 26, 2020
BANK ARMORING PLAN
This bank protection plan is presented to explain the bank
armoring proposed for reservoir bank protection in Phase 1 and
Phase 2 that run parallel to the South Platte River channel .
Only the reservoir side armoring is being proposed since the
river bank lies 150 to 250 feet west of the top of the slope of
the permit area.
The attached Figure 1 shows the cross-section of the area
discussed below and details of the armoring to protect the banks
along the west side of Phase 1 . The west and south banks in
Phase 2 will also be armored using this plan. The Reclamation
Plan Maps have been revised to show the location of the areas to
be armored in the mine .
The armor is intended to protect the reservoir banks should a
100-year flood event occur after an area has been reclaimed. The
armoring will be covered with a 6-10 inch layer of growth medium
and seeded with the approved seed mix.
The toe of the slope armoring will be at least 5 feet below the
thalweg of the adjacent riverbed. The base of the armoring will
average 10 feet below the existing ground surface at the mine .
The 100-year Floodplain information has been included on all of
the Map Exhibits in the Reclamation Packet .
Armoring material will be recycled concrete fragments with
surface rebar removed, so that it meets the definition of Inert
Materials . The concrete will be sized 9 to 15 inches averaging 12
inches . Fines will be mixed in to fill voids . This size material
will have a Safety Factor of 1 . 26 . See Bank Armoring Calculation
page following this text .
The operator will keep enough material stored on the mine to
complete armoring needed on any area where sloping is being
completed and is ready for armoring. At a minimum, 2 , 350 cubic
yards will be stockpiled on the mine for use in armoring. This
is enough to armor a minimum of 1, 000 feet of excavation bank.
At no time will there be more than 1, 000 feet of armoring needing
to be placed.
The stockpile of armoring material will be placed parallel to the
water flow so it will not interfere with flows in the flood plain
if flooding occurs . It will be within the setback between the
permit boundary and the mine highwall so it is close to the area
where it will be placed.