796_Appendix A_Cottonwood Mine Closure.pdf

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Attached to
PKAA, Cottonwood Mine Closure Project
Solicitation number
DQ1 PKAA 2026000533 2
Issued by
Clear Creek County, Colorado

About this file

This is an Appendix A document for the Cottonwood Mine Closure Project in Colorado, detailing specifications for mine opening closures and maintenance features. The project encompasses three categories of work: guaranteed mine closures (Item 4.0), non-guaranteed mine closures (Item 5.0), and non-guaranteed maintenance features (Item 6.0). Item 4.0 includes six mine closure projects across various feature types including shafts, adits, and stopes, utilizing closure methods such as machine backfill, corrugated steel pipe installations with bat grates, and grated shaft closures. Item 5.0 lists five additional non-guaranteed closures using rock bulkheads and corrugated steel pipe installations, while Item 6.0 specifies eight maintenance features involving adit door repairs, panel door repairs, and machine backfill work for crown holes and shafts. Each feature is identified by a unique ID with specific UTM coordinates and detailed work descriptions referencing applicable specification sections and standard drawings.

The document provides comprehensive technical specifications for each mine opening, including dimensions, depth, lining conditions, drainage characteristics, and closure methodologies. Work descriptions outline specific requirements such as debris clearance, material specifications (e.g., 24-inch diameter 12-gauge corrugated steel pipe), backfill procedures using onsite materials, and stormwater sediment control measures including excelsior waddle installation. Rock fill quantities are specified where required, ranging from five to twenty cubic yards for certain features. The document references multiple specification sections and standard drawings that contractors must follow, including Backfill Closure Specifications, Corrugated Steel Pipe Adit Closure Specifications, Grated Shaft Closure Specifications, and Bat Grate Alternative designs, ensuring standardized closure practices across all mine openings.

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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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