2019-08-29_PERMIT FILE - M2019028 ‎(3)‎

• Permit No: M2019028
• IBM Index Class Name: PERMIT FILE
• Doc Date: 8/29/2019
• Doc Name: Adequacy Review Response
• From: J&T Consulting
• To: DRMS
• Email Name: AME
• Media Type: D
• Archive: No

RE. J-2 Contracting Company-DPG Pit-Permit No. M-2019-028
112(c) Pen-nit Application
Adequacy Review No. 1 Response 8126119
-5-
meant by potentially backfilling pit areas not lined with a slurry wall.
Response: There will not be backfilling of pit areas not lined with a slurry wall. The areas
to be mined are all planned to be lined with a slurry wall at this time. The language has
been removed from the updated text in the mining plan.
21) There is some discrepancy in the mining plan regarding the proposed mining slope. A
3H:1V slope is proposed throughout most of the plan, but then a 2HAV slope is proposed
in the last paragraph. Please specify the proposed mining slope to be maintained during
operations. If the pit slopes will be steeper than the proposed final configuration of 3HAV,
please specify the maximum length of pit slope at any time to be steeper than 3HAV. This
information is needed to calculate the required financial warranty for the proposed
disturbance. Additionally, if pit slopes will be steeper than 3HAV, the slope stability report
provided in this application should be revised accordingly.
Response: The mining slope proposed is 3H:1 V slope. The 2H:1 V slope language has
been removed from the updated text in the mining plan.
22) The operator is proposing mining the site in five phases, creating a total of four pits, each
enclosed by a slurry wall. The operator proposes installing inlet and outlet structures on
the mined pits/reservoirs for final reclamation. However, the operator has not discussed
flood control measures to be implemented during operations. Please provide the
anticipated sequencing for installation of the inlet/outlet structures. For example, does the
operation intend to install the proposed inlet/outlet structures on the Phase 1 and 2
pit/reservoir prior to mining the Phase 3 pit/reservoir, and so on? Or does the operation
propose installing all structures after mining is completed at the site? Please describe all
measures to be taken during operations to minimize disturbances to the prevailing
hydrologic balance of the affected land and of the surrounding area and to the quantity
and quality of water in surface and groundwater systems, including preventing pit capture
of the adjacent Cache La Poudre River during high flow events.
Response: The operator is proposing to install the inlet/outlet spillways during mining of
each phase. The spillways for the Phase 1 and 2 areas will be installed as mining
progresses down. Once the mining has progressed down 15 to 20 feet in Phase 1 the
riverside spillways will be installed. The riverside spillway for Phase 1 will be installed
first, then the riverside spillway for Phase 2 will be installed (once mining occurs in
Phase 2), then the pitside spillway in Phase 3 will be installed to convey floodwaters if
encountered from Reservoir 1 to Reservoir 2. The pitside spillway from Reservoir 2 to
Reservoir 3 will be installed once mining occurs in Phase 4. The pitside spillway from
Reservoir 3 to Reservoir 4 will be installed once mining occurs in Phase 5; and the
riverside spillway in Reservoir 4 will also be installed once mining occurs in Phase 5.
These riverside and pit side spillways are designed per the Urban Drainage and Flood
Control District's Technical Review Guidelines for Gravel Mining and Water Storage
Activities Within or Adjacent to 100-Year Floodplains.
23) Please provide an approximate timetable to describe the mining operation, including an
estimate of the periods of time which will be required for the various stages or phases of
the operation, a description of the size and location of each area to be worked during each
phase, and outlining the sequence in which each stage or phase of the operation will be
carried out. Please be sure to include the proposed sequence for slurry wall installation as
it relates to each mining phase.
Response: The operator is proposing to mine Phase 1 first that is 27.15 acres and during
this mining there will be 65.4 acres disturbed to provide locations for a scale house and
I, 305 Denver Avenue-Suite D•Fort Lupton CO 80621 •Ph: 303-857-6222•Fax: [phone]