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2020-12-28_GENERAL DOCUMENTS - M1977300 (22)
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2020-12-28_GENERAL DOCUMENTS - M1977300 (22)
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Last modified
1/9/2025 6:28:15 AM
Creation date
12/29/2020 5:26:52 PM
Metadata
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Template:
DRMS Permit Index
Permit No
M1977300
IBM Index Class Name
General Documents
Doc Date
12/28/2020
Doc Name Note
Part 1 of 3
Doc Name
North Waste Rock Pile Diversion
From
Colorado Legacy Land
To
DRMS
Email Name
AME
Media Type
D
Archive
No
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PERMIT#: M-1977-300 <br /> INSPECTOR'S INITIALS: AME <br /> INSPECTION DATE:November 19,2020 <br /> concrete-lined diversion channel appeared to have been constructed in accordance with the proposed design. <br /> The areas adjacent to the channel have been backfilled and graded to create positive drainage into the channel. <br /> It should be noted, the low-lying diversion berm constructed south of the channel (where the channel curves <br /> around the hillside) may need maintenance or additional material added, as discussed during the inspection. The <br /> disturbed slope south of the access road and channel and the side slope of the access road were graded to <br /> 2H:1 V. The riprap-lined energy dissipation basin appeared to be constructed per the approved design. The road <br /> crossing installation had some slight deviations from the approved design to include 6 inch thick Geoweb panels <br /> instead of 4 inch thick panels, and a gravel infill rather than a concrete infill. The Geoweb panels were filled <br /> with 1-1/2 inch minus gravel and surfaced with an approximate one inch thick layer of pea gravel. Any <br /> deviations from the design approved in TR-28 will be incorporated into the as-built drawings to be submitted <br /> with the final construction report. Areas disturbed by the NWRP diversion channel project, including the top of <br /> the NWRP, the disturbed slope located south of the access road and channel (near the top of the NWRP), the <br /> side slope of the access road, and areas immediately adjacent to the channel, have been seeded in accordance <br /> with TR-28. The operator will continue to monitor revegetation success in the seeded areas and reseed next year <br /> as needed. <br /> The NWRP diversion channel project was completed as part of a corrective action for two hydrologic balance <br /> problems cited in the Division's inspection report signed on April 9, 2019. The operator believes the <br /> contaminated water observed ponded between the toe of the NWRP and Ralston Creek was most likely derived <br /> from surface flows onto the NWRP from the ephemeral drainage above the pile. The installation of the <br /> diversion channel should divert these flows around the NWRP, preventing future seep issues. The Division <br /> accepts the work completed for the NWRP diversion channel project, and will continue to monitor this facility <br /> during future site inspections. <br /> At the time of the inspection, the mine pool was at 318 feet below the Steve Level, which is 168 feet below the <br /> required 150 foot depth. The water treatment plant was shut down for the winter. The operator will continue to <br /> monitor the mine pool level throughout this period and turn the plant back on as needed (currently expected to <br /> occur in May of 2021) to keep the mine pool below the required depth. The last in-situ injection treatment of the <br /> mine pool was completed in January of 2020, which included two tracers. The operator is currently analyzing <br /> the results of the in-situ treatment and tracer study, and will incorporate these analyses into the conceptual site <br /> model and final reclamation plan to be proposed in an upcoming Amendment application (anticipated to be <br /> submitted in the 3rd quarter of 2021). The operator continues to collect water quality samples from the mine <br /> pool on a quarterly basis and reports this data with other site sampling data in its quarterly monitoring reports <br /> submitted to the Division. <br /> The alluvial excavation project was active during the inspection, with excavated material being hauled up to the <br /> CV Glory Hole inside the Minnesota Mine for disposal,per the approved permit. This project was put on hold <br /> while the NWRP diversion channel project was completed this fall. At the time of the inspection, the operator <br /> estimated there to be approximately 3 weeks of hauling left before they reach capacity in the CV Glory Hole. <br /> The Division is currently reviewing an Amendment application(AM-5) submitted by the operator to include <br /> disposal of the radio-nuclide impacted alluvial valley soils into the Black Forest Mine, which has an estimated <br /> capacity of 15,000 cy. The decision date for AM-5 is currently set for January 15, 2020. <br /> In its last inspection report, signed on November 6, 2020, the Division discussed the borrow area located up the <br /> valley from the NWRP where rock and fill material was derived for the diversion channel project. The material <br /> excavated in this area was deposited in the valley during the September 2013 flood events. The borrow area is <br /> located outside of the approved mine permit area. However, the operator had indicated the area was included in <br /> their 404 permit held with the U.S. Army Corps of Engineers. The Division gave the operator two weeks from <br /> the date of its inspection report to provide a copy of the 404 permit. It should be noted, the operator did provide <br /> Page 3 of 15 <br />
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