The Commodore Level 5 Tunnel is located above Nelson Tunnel and is connected by vertical mine workings. As the water levels periodically fluctuate in the largest mine pool of the Nelson Tunnel, water flows into the Commodore Level 5 Tunnel, allowing pressure relief on the largest impoundment before water returns to the Nelson further down gradient. The stability of the Commodore Level 5 Tunnel is critical the stability of the largest Nelson Tunnel impoundment.

The Commodore Level 5 Tunnel is located above Nelson Tunnel and the two are connected by vertical mine workings. As the water levels periodically fluctuate in the largest mine pool of the Nelson Tunnel, water flows into the Commodore Level 5 Tunnel, allowing pressure relief on the largest impoundment before water returns to the Nelson further down gradient. The stability of the Commodore Level 5 Tunnel is critical the stability of the largest Nelson Tunnel impoundment.

DRMS monitored water levels and condition of the workings in 2016, 2017, and early 2018 and reported that conditions in the Commodore Level 5 Tunnel were deteriorating at an increasing rate. As the workings continue to deteriorate without intervention, further rockfall could completely block the flow path of water between the two tunnels, hindering the pressure relief that the Commodore Level 5 Tunnel currently provides. 

Completed Milestones and other items of note:

• Fluid hazard consultation with EPA HQs has been completed for:
  • Segments 1 - 4 in July 2018.
  • Segment 5A in October 2018
  • Segment 5B and Segment 6 in August 2019
• Instrumentation has been installed to monitor water levels of all three mine pools, and is accessible at Daylight Corner.
• Permanent mine phones have been installed at the Portal, Daylight corner, and Bachelor Shaft for ongoing basic communications and safety at the site. Additional temporary mine phones have been installed in the surface office and will be located near the current work areas as the project progresses.
• Direct emergency radio communications between the Site Office and the Mineral County Sheriff’s Office/Dispatch were established on September 27^th, 2018 and will continue to be available throughout the remainder of the removal action.

1. Stabilize areas of Commodore Level 5 Tunnel to prevent further deterioration. 

2. Clear muck and debris such as rock fall from the tunnel roof or walls from the floor of the tunnel to prevent water from impounding. 

3. Rehabilitate the portal gate structure and maintaining Commodore Level 5 Tunnel; walls and roof for worker access. 

1. Prevent water from impounding in the Commodore Level 5 Tunnel.
2. Preserve current conditions and prevent further pressure from building on the Nelson Tunnel impoundments.
3. Maintain and keep vertical connections from Commodore Level 5 to the Nelson Tunnel. 
4. Maintaining physical access between Commodore Level 5 Tunnel and Nelson Tunnel. 
5. Stabilize Segment 6 of the Commodore Level 5 Tunnel per current Issued For Construction design drawings.

The planned activities for this Operations Period were:

1. Improve the West Willow creek low-water-crossing and travel way to allow equipment and supplies to be brought to the Commodore portal.

2. Installation of instrumentation to measure and record the elevations of the 3 mine pools for the duration of the removal. Instruments will be installed at the Bachelor Shaft, Daylight Winze, and Del Monte Raise. This will include installing mine phone hardware at the portal and Daylight Corner.

3. Begin stabilization activities in Segment 2:

- Activities are anticipated to include damaged track removal/repair/replacement, installation of track ballast,   rock scaling, rock bolting, and mucking.

1. Design for Segment 5 from Daylight Winze to the 44 Raise was completed on 8/2.
2. Instrumentation was installed to monitor water levels of all three mine pools, accessible at Daylight Corner.
3. Mine phones installed at the Portal and Daylight corner for basic communications and safety.
4. Current progress in Segment 2, which is Portal entrance to Daylight Corner:
   - Rail removal is complete to station 1+60
   - Scaling of loose rock complete to station 7+50
   - Mucking is complete to station 1+60

The planned activities for this Operations Period were:

1. Continue stabilization activities in Segment 2
2. Replacement of rail to 1+60, continue removal/replacement as required.
3. Begin rock bolting as required by plans.
4. Continue scaling and mucking, working towards Daylight corner (station 22+10).

1. Instrumentation installed to monitor water levels of all three mine pools, accessible at Daylight Corner.

2. Mine phones installed at the Portal and Daylight corner for basic communications and safety.

3. Current progress in Segment 2 - Portal to Daylight Corner:

• Rail removal is complete to station 1+60
• Scaling of loose rock complete to station 21+00
• Mucking is complete to station 1+60 

The planned activities for this Operations Period were:

1. Continue stabilization activities in Segment 2
   1. Replacement of rail to 1+60, continue removal/replacement as required. Delayed due to rail supply delays. Anticipated to start mid-week.
   2. Spot bolting based on crew observations near station 5+50.
   3. Continue mucking, working towards Daylight corner (station 22+10).

The planned activities for this Operations Period were:

Continue stabilization activities in Segment 2

1. Replacement of rail to 1+60. Anticipated to require most of the week.
2. As time permits, continue mucking, working towards Daylight corner (station 22+10).

Stabilization activities in Segment 3 may begin towards the end of the week.

1. Scaling at Daylight Corner, spot bolting as needed for safety.

·        

1. Instrumentation was installed to monitor water levels of all three mine pools, accessible at Daylight Corner. Data is available via Map Viewer.

2. Mine phones installed at the Portal and Daylight corner for basic communications and safety. 

3. Current progress in Segment 2 - Portal to Daylight Corner:

• Rail removal is complete to station 1+60
Scaling of loose rock complete to station 22+64 -this extends into Segment 3 Mucking is complete to station 1+60
• Pattern Bolting per design is complete to 22+64 – this extends into Segment 3

Current progress in Segment 3 – Daylight Corner

• A temporary “seal” or bulkhead was established at the bottom of Daylight Winze. It will prevent anything larger than about 2” in diameter from falling down the winze.

 

The planned activities for this Operations Period were:

1. Continue stabilization activities in Segment 2
   1. Replacement of rail to 1+60.
   Stabilization/support of the stope (above the Commodore) at 22+00.
   2. As time permits, continue mucking, working towards Daylight corner (station 22+10).
2. Stabilization activities in Segment 3
   1. Begin stabilization of the Daylight Winze.

·         Current progress in Segment 2 - Portal to Daylight Corner:

• Scaling of loose rock complete to station 22+64 -this extends into Segment 3
Mucking is complete to station 3+00
• Rail rehab is complete to station 1+90
•  Additional ground support is complete (steel supports per plans): 22+00

·         Current progress in Segment 3 – Daylight Corner

• Pattern Bolting per design is complete to 22+64 – this extends into Segment 3
• Additional ground support is complete (steel supports per plans): 22+20

·      Rock bolt pull-testing occurred under the oversight of the design Engineer during this period. Selected rock bolts were loaded to 125% of the design load, or 50,000 pounds of tension. Of approximately 60 installed bolts, 19 were tested, 4 failed and will be replaced. Minor changes to installation technique are being made per the Engineer’s suggestions.

1.      The planned activities for this Operations Period were:

Continue stabilization activities in Segment 2

a.       Continue placing ballast along track as needed, working towards Daylight corner (station 22+10).

b.      Continue stabilizing the raise at 22+00 (welding, mine foam)

c.       As time permits, continue mucking, working towards Daylight corner.

2.      Stabilization activities in Segment 3

a.       Continue stabilizing the raise at 22+20 (welding, mine foam)

b.      Begin work in the Daylight Winze

3.      Stabilization activities in Segment 4

a.       As time permits, scaling/mucking/bolting into Segment 4