AM1 - Twin Sisters Special Conditions.pdf
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- Attached to
- PKAA, Twin Sisters Mine Closure Project
- Solicitation number
- DQ1 PKAA 2026000289 2
- Issued by
- Boulder County, Colorado
About this file
This file is an amendment to bid documents for the Twin Sisters Mine Closure Project issued by the Colorado Department of Natural Resources, Division of Reclamation, Mining and Safety (DRMS). The amendment, dated May 19, 2026, incorporates clarifications and updates resulting from a pre-bid meeting and modifies the original bid schedule and project specifications. Key changes include revised quantities for sediment control materials (675 linear feet of wattle), updates to mine feature closure methods for three identified features (BC9, KR01, and KR02), removal of Items 8.0 and 9.0 (Additional Concrete and Additional Grate), and addition of Item 11.0 for up to 5 cubic yards of additional imported fill. The bid submittal deadline has been extended to Monday, June 1, 2026, at 4:00 p.m. Mountain Time, with the bid opening scheduled for Tuesday, June 2, 2026.
The amendment maintains all original terms and conditions of the Documented Quote except as explicitly modified. Specific work scope revisions include: Feature BC9 requiring 600 cubic yards of imported machine backfill with 50 linear feet of biodegradable waddles and sediment control measures; Feature KR01 deletion due to self-reclamation; and Feature KR02 requiring machine backfill with onsite material and 25 linear feet of biodegradable waddles. Contractor acknowledgment of receipt and acceptance is required through notation on the revised bid schedule.
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Physical Address: 1313 Sherman Street, Room 215, Denver, CO 80203 P 303.866.3567 F 303.832.8106 Mailing Address: DRMS Room 215, 1001 E 62nd Ave, Denver, CO 80216 https://drms.colorado.gov
Jared S. Polis, Governor | Dan Gibbs, Executive Director | Michael A. Cunningham, Director
Special Conditions
Twin Sisters Mine Closure Project
Amendment No. 1 DQ1 PKAA 2026*0289
5/19/2026
Thank you for attending the Pre-Bid Meeting. The following clarifications and amendments should be noted and incorporated into the bid documents:
1. The Bid Schedule attached to the original bid has been replaced with a Revised Bid Schedule named “Am#1 Revised (5/19/2026) Bid Schedule”.
2. Item 3.0 – Sediment Control: Updated quantity of wattle to 675 LF.
3. Item 4.0 – Safeguarding Hazardous Mine Features.
The following mine features listed in Attachment 1 have been changed/updated:
Feature ID Type
Description of Mine Opening
Closure Method
General Bid Specifications and Drawings Work Description / Notes
BC9
Eligible Feature Stope
Eroded: 80ft by 8-20ft
Depth: 15-25 ft Lining: Rock
Drainage: No
Machine Backfill
SWS 2
Exclude for Bats. Machine Backfill with six-hundred (600) CY imported fill. No rockfill is required.
Storm water sediment control measures shall be implemented prior to work on the closure. Fifty (50) linear feet of biodegradable waddles shall be installed on the downstream side of the working area under the direction of the PROJECT MANAGER.
KR01
Eligible Feature Adit
Excavated: 6ft by 4ft
Eroded: 7ft by 8ft
Depth: >500 ft Lining: Rock
Drainage: Yes
Grated Corrugated Steel Pipe w/ Bat Ladder
SWS 10, 13
Drawing(s) 5, 6.2
Feature has self-reclaimed. This item has been deleted from the bid.
KR02 Shaft
Eroded: 10ft by 10ft
Depth: 400 ft Lining: Rock Drainage: No
Machine Backfill
SWS 2
Machine Backfill with onsite material from the west of the shaft. One (1) CY of onsite Rockfill will be placed prior to backfilling.
Storm water sediment control measures shall be implemented prior to work on the closure. Twenty-five (25) linear feet of biodegradable waddles shall be installed on the downstream side of the working area under the direction of the PROJECT MANAGER.
1. Item 8.0 Additional Concrete has been removed from the project.
2. Item 9.0 Additional Grate has been removed from the project.
3. Item 11.0 – Additional Imported Fill (Not Guaranteed) has been added to the project. Provide and install five cubic yards (5 CY) of additional imported fill, per specifications, if required.
4. The Bid Submittal deadline will be on Monday June 1, 2026 at 4:00 p.m. MT. The Bid Opening will be on Tuesday June 2, 2026, in an effort to provide contractors with additional time to adjust costs and account for the change(s) above.
All terms and conditions of the Documented Quote other than as changed by this amendment remain the same.
Receipt and acceptance of this amendment shall be acknowledged on the bid schedule where noted and by submitting the Am#1 Revised (5/19/2026) Bid Schedule.
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