796_Appendix A_Cottonwood Mine Closure.pdf
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- Attached to
- PKAA, Cottonwood Mine Closure Project
- Solicitation number
- DQ1 PKAA 2026000533 1
- Issued by
- Colorado
About this file
This document is Appendix A from a mine closure project specification, detailing closure requirements for abandoned mine openings across multiple sites. The appendix presents three tables outlining guaranteed and non-guaranteed closure work items, along with maintenance features requiring attention. Table 1 (Item 4.0) lists six guaranteed mine closures including one shaft and five adits/stopes, with closure methods ranging from machine backfill to grated shaft closures with bat grate alternatives. Table 2 (Item 5.0) identifies five non-guaranteed closure items consisting of four adits and one shaft using rock bulkhead closures and machine backfill methods. Table 3 (Item 6.0) encompasses seven maintenance features addressing repairs and backfill work on existing adit doors, crown holes, and shafts. Each feature entry includes specific details such as opening dimensions, depth, closure method, applicable specification sections, UTM coordinates in NAD83 format, and detailed work descriptions with material and sediment control requirements.
The project specifications prescribe standardized closure methodologies with references to detailed bid specifications and standard drawings numbered 2.0 through 14. Work requirements emphasize environmental protection through stormwater sediment control measures, including installation of excelsior waddles ranging from 20 to 50 feet along downgradient areas. Materials specified include corrugated steel pipe in 24-inch and 36-inch diameters, concrete footers, plywood protection sheets, and onsite fill materials. The document provides precise geolocation data for each feature enabling accurate field identification and project management. All work descriptions reference compliance with detailed specifications and drawings, ensuring standardized execution across the multiple closure features distributed across the project area.
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Appendix A
Table 1 – Item 4.0: Install Mine Closures
Table 2 – Item 5.0: Install Mine Closures (Not Guaranteed)
Table 3 – Item 6.0: Maintenance Features (Not Guaranteed)
Table 1 Item 4.0 – Install Mine Closures
Feature ID Type Description of Mine Opening
Closure Method
General Bid Specifications and
Drawings
UTM
(X,Y) NAD83 Work Description / Notes
CCC139 Shaft
Present: 10ft by 12ft Depth: 14 ft
Lining:
Drainage: No
Machine Backfill
Section 2.0–Backfill Closure
449127.097, 4398113.171
Machine backfill in accordance with Backfill Closure Specifications with onsite materials. No rock fill required. Storm water sediment control measures shall be implemented prior to work on the closure.
Twenty-five (25) feet of excelsior waddles shall be installed on the downgradient side of the working area.
CCC140 Adit
Present: 1ft by 1ft Depth: >50 ft
Lining:
Drainage: No
Grated Corrugated Steel Pipe with Bat Grate
Alternative
Section 10–Corrugated Steel Pipe Adit Closure Section 13–Bat Grate Alternative Std. Drawing #s 5 & 6.2
449076.158, 4397826.473
After clearing all loose debris, install a twenty four
(24) inch diameter ten (10) foot length of twelve (12) gauge corrugated steel pipe (CSP) with bat ladder in accordance with Corrugated Steel Pipe Adit Specifications and Bat Grate Alternative. Access door is not required. Drainpipe is not required. Rock grouting around the CSP is required. The CONTRACTOR shall cover the CSP with onsite soil bedding prior to backfill and to reduce the likelihood of damage to the CSP by falling rock from the brow.
In addition, the exterior of the CSP shall be backfilled using onsite material.
Feature ID Type Description of Mine Opening
Closure Method
General Bid Specifications and
Drawings
UTM
(X,Y) NAD83 Work Description / Notes
CCC141 Adit
Present: 1ft by 1ft Depth: >25 ft Lining: Rock Drainage: No
Grated Corrugated Steel Pipe with Bat Grate
Alternative
Section 10–Corrugated Steel Pipe Adit Closure Section 13–Bat Grate Alternative Std. Drawing #s 5 & 6.2
448993.355, 4397796.808
After clearing all loose debris, install a twenty four
(24) inch diameter ten (10) foot length of twelve (12) gauge corrugated steel pipe (CSP) with bat ladder in accordance with Corrugated Steel Pipe Adit Specifications and Bat Grate Alternative. Access door is not required. Drainpipe is not required. Rock grouting around the CSP is required. The CONTRACTOR shall cover the CSP with onsite soil bedding prior to backfill and to reduce the likelihood of damage to the CSP by falling rock from the brow.
In addition, the exterior of the CSP shall be backfilled using onsite material.
CCC143 Stope
Present: 21ft by 26ft Depth: 60 ft
Lining: Other Drainage: No
Shaft Grate with Bat Grate
Alternative
Section 8–Grated Shaft Closure Section 13–Bat Grate Alternative Std. Drawing #s 4 & 6.2 and Attachment 3
449066.179, 4398080.585
Construct a grated shaft closure with a Bat Cupola in accordance with Grated Shaft Closure Specifications.
Poor rock condition at the collar will require six (6) concrete footers. Excavate two by two foot (2 x 2 ft) pockets with the outside edge of each pocket a minimum of four (4) feet from the edge of the opening.
The modified bat grate will be a raised four (4) sided ‘cupola’ consisting of one (1) six (6) inch high by twenty-four (24) inch wide bat slot on each side.
An access door is not required.
GC050 Shaft
Present: 3ft by 4ft Depth: ft
Lining: Other Drainage: No
Machine Backfill
Section 2.0–Backfill Closure
453305.638, 4416493.989
Machine backfill in accordance with Backfill Closure Specifications with onsite materials. No rock fill required. Storm water sediment control measures shall be implemented prior to work on the closure.
Fifty (50) feet of excelsior waddles shall be installed on the downgradient side of the working area.
Feature ID Type Description of Mine Opening
Closure Method
General Bid Specifications and
Drawings
UTM
(X,Y) NAD83 Work Description / Notes
GC051 Shaft
Present: 2ft by 3ft Depth: 70 ft
Lining: Other Drainage: No
Grated Corrugated Steel Pipe with Bat Grate
Alternative
Section 10–Corrugated Steel Pipe Adit Closure Section 13–Bat Grate Alternative Std. Drawing #s 5 & 6.2
455008.871, 4413061.06
Insert CSP then backfill with on-site material against exposed cribbing to stabilize. After clearing all loose debris, install a twenty four (24) inch diameter eight
(8) foot length of twelve (12) gauge corrugated steel pipe (CSP) with bat ladder in accordance with Corrugated Steel Pipe Adit Specifications and Bat Grate Alternative. Access door is not required.
Drainpipe is not required. Rock grouting around the CSP is required. The CONTRACTOR shall cover the CSP with onsite soil bedding prior to backfill and to reduce the likelihood of damage to the CSP by falling rock from the brow. In addition, the exterior of the CSP shall be backfilled using onsite material.
LAR009 Adit
Present: 3ft by 4ft Depth: 35 ft Lining: Rock Drainage: No
Rock Bulkhead with Bat Grate
Alternative
Section 14–Rock Bulkhead Closure Section 13-Bat Grate Alternative Std. Drawing #s 6.2 & 10
470576.084, 4476590.895
Construct a Rock Bulkhead closure with a bat ladder.
Utilize a minimum three foot (3 ft) length of thirty six inch (36in), 12-guage CSP.
Neither an access door nor drain pipe are required.
Table 2 Item 5.0 – Install Mine Closures - Not Guaranteed
Feature ID Type Description of Mine
Opening Closure Method
General Bid Specifications and
Drawings
UTM
(X,Y) NAD83 Work Description / Notes
CCC136 Adit
Present: 5ft by 6ft Depth: 15 ft Lining: Rock Drainage: No
Rock Bulkhead with Bat Grate
Alternative
Section 14–Rock Bulkhead Closure Section 13-Bat Grate Alternative Std. Drawing #s 6.2 & 10
452209.38, 4402900.61
Construct a Rock Bulkhead closure with a bat ladder.
Utilize a minimum three foot (3 ft) length of thirty six inch (36in), 12-guage CSP.
Neither an access door nor drain pipe are required.
CCC137 Adit
Present: 4ft by 5ft Depth: 15 ft Lining: Rock Drainage: No
Rock Bulkhead with Bat Grate
Alternative
Section 14–Rock Bulkhead Closure Section 13-Bat Grate Alternative Std. Drawing #s 6.2 & 10
452626.959, 4400594.240
Construct a Rock Bulkhead closure with a bat ladder.
Utilize a minimum three foot (3 ft) length of thirty six inch (36in), 12-guage CSP.
Neither an access door nor drain pipe are required..
CCC142 Adit
Present: 2ft by 3ft Depth: >25 ft Lining: Rock Drainage: No
Grated Corrugated Steel Pipe with Bat Grate
Alternative
Section 10–Corrugated Steel Pipe Adit Closure Section 13–Bat Grate Alternative Std. Drawing #s 5 & 6.2
448972.968, 4398024.784
After clearing all loose debris, install a twenty four
(24) inch diameter ten (10) foot length of twelve (12) gauge corrugated steel pipe (CSP) with bat ladder in accordance with Corrugated Steel Pipe Adit Specifications and Bat Grate Alternative. Access door is not required. Drainpipe is not required. Rock grouting around the CSP is required. The CONTRACTOR shall cover the CSP with onsite soil bedding prior to backfill and to reduce the likelihood of damage to the CSP by falling rock from the brow.
In addition, the exterior of the CSP shall be backfilled using onsite material.
GC053 Shaft
Present: 5ft by 6ft Depth: 4 ft
Lining:
Drainage: No
Machine Backfill
Section 2.0–Backfill Closure
455879.939, 4405577.21
Machine backfill in accordance with Backfill Closure Specifications with onsite materials. No rock fill required. Storm water sediment control measures shall be implemented prior to work on the closure.
Fifty (50) feet of excelsior waddles shall be installed on the downgradient side of the working area.
Table 3 Item 6.0 – Maintenance Features - Not Guaranteed
Feature ID Type Description of Mine
Opening Closure Method
General Bid Specifications and
Drawings
UTM
(X,Y) NAD83 Work Description / Notes
143-061 Adit
Present: N/A Depth: 200 ft
Lining:
Drainage: No
Adit Door Repair
Section 12–Adit Door Closure
454788.866, 4397068.986
Replace the vandalized two by two (2 x 2) foot adit door with a new bat accessible adit door.
161-D-32 Crown Hole
Present: 1ft by 2ft Depth: 6ft
Lining: Soil Drainage: No
Machine Backfill
Section 2.0–Backfill Closure
456825. 919, 44 5897.625
Machine backfill in accordance with Backfill Closure Specifications with onsite materials. Five (5) cubic yards of rock fill are required. Six (6) four foot by eight foot (4ft x 8ft) sheets of plywood will be required to protect the resident’s lawn. Storm water sediment control measures shall be implemented prior to work on the closure. Twenty five (25) feet of excelsior waddles shall be installed on the downgradient side of the working area.
224-104 Shaft
Present: 6ft by 8ft Depth: 5ft
Lining: Soil Drainage: No
Machine Backfill
Section 2.0–Backfill Closure
447030.51, 4398218.21
Machine backfill in accordance with Backfill Closure Specifications with onsite materials. Five (5) cubic yards of rock fill are required. Storm water sediment control measures shall be implemented prior to work on the closure. Twenty five (25) feet of excelsior waddles shall be installed on the downgradient side of the working area.
224-119 Adit
Present: N/A Depth: N/A
Lining: Rock Drainage: ~1.5 gmp
Adit Door Repair
Section 12–Adit Door Closure
450333.0926, 4396572.374
Remove and properly dispose of trash within and around the portal. Replace the lock hasp and protective plate so that the adit door may be securely locked.
Table 3 Item 6.0 – Maintenance Features - Not Guaranteed
Feature ID Type Description of Mine
Opening Closure Method
General Bid Specifications and
Drawings
UTM
(X,Y) NAD83 Work Description / Notes
245-113 Adit
Present: N/A Depth: 200 ft
Lining:
Drainage: No
Adit Door Repair
Section 12–Adit Door Closure
454788.866, 4397068.986
Remove and replace the vandalized two by two (2 x
2) foot adit door with a new bat accessible adit door.
247-P-75 Shaft
Present: 6ft by 13ft Depth: >100 ft
Lining:
Drainage: No
Panel Door Repair
Section 4–Precast Concrete Panel Closure
455406.395, 4407660.644
Remove and replace the vandalized two by two (2 x
2) foot adit door with a new bat accessible adit door.
Door frame is in good condition.
258-114 Shaft
Present: 10ft by 17ft Depth: UNK Lining: Rock Drainage: No
Machine Backfill
Section 2.0–Backfill Closure
449136.4969, 4403444.708
Machine backfill in accordance with Backfill Closure Specifications with onsite materials. Twenty (20) cubic yards of rock fill are required. Storm water sediment control measures shall be implemented prior to work on the closure. Twenty five (25) feet of excelsior waddles shall be installed on the downgradient side of the working area.
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