5.10.
CC Regular Session
- Meeting Date:
- 05/26/2020
- By:
- Bruce Westby, Engineering/Public Works
Information
Title
Adopt Resolution #20-107 Authorizing Alternate Bid B for Variolite Street Reconstruction, Improvement Project #20-01
Purpose/Background:
Purpose:
The purpose of this case is to adopt Resolution #20-107 authorizing Alternate Bid B to replace all ductile iron pipe (DIP) watermain with high-density polyethylene (HDPE) watermain for Variolite Street Reconstruction, Improvement Project #20-01.
Background:
Pursuant to Resolution #20-089 adopted May 12, 2020, the City Council approved plans and specifications and authorized the advertisement of bids for Improvement Project #20-01, which proposes to reconstruct Variolite Street between Alpine Drive and 173rd Avenue.
Included with this project is the extension of 12-inch trunk watermain from 166th Avenue to 173rd Avenue in support of the 2040 City of Ramsey Comprehensive Plan. The plans currently out for bids include 3,341 lineal feet of 12” DIP class 52 watermain, which is installed by digging a trench 8-plus feet deep and roughly 20 feet wide at the surface. For reasons noted later in this case, Staff would like to receive an alternate bid to replace the 12” DIP watermain with 3,341 lineal feet of 12” HDPE watermain. If Council approves this alternate bid request an addendum to the plans will be issued calling for Alternate Bid B (the signalized RRFB pedestrian crossing signs are Alternate Bid A).
The watermain design in the plans out for bids already includes 1,204 linear feet of 12” directionally drilled high-density polyethylene (HDPE) watermain for use in crossing under the Trott Brook culvert. This design is necessary to prevent wetland impacts that would result from jacking a steel carrier pipe under the culvert as needed to convey the 12” DIP watermain. Jacking a carrier pipe requires large pits to be dug on each end of the carrier pipe, which would impact the adjacent wetlands due to their close proximity to the street. Directional drilling the HDPE pipe will allow watermain to be bored under the road and culvert at a prescribed line and grade, meaning the pipe is gradually bent as it is bored allowing for long runs and preventing the need to dig pits near the wetlands.
As currently designed, the HDPE watermain connects to DIP watermain about 500 feet on either side of Trott Brook. If HDPE watermain is installed in place of DIP watermain, open trenching would not be required and the watermain could be installed faster, resulting in fewer impacts to the traveling public and abutting property owners.
Staff has estimated the construction cost savings associated with Alternate Bid B at just under $30,000 due to a reduction in disturbed area requiring less restoration, less dewatering, and less hauling, stockpiling and loading of reclaimed pavement materials. This amount does not factor in other benefits such as a shorter construction schedule, and safer working conditions.
The purpose of this case is to adopt Resolution #20-107 authorizing Alternate Bid B to replace all ductile iron pipe (DIP) watermain with high-density polyethylene (HDPE) watermain for Variolite Street Reconstruction, Improvement Project #20-01.
Background:
Pursuant to Resolution #20-089 adopted May 12, 2020, the City Council approved plans and specifications and authorized the advertisement of bids for Improvement Project #20-01, which proposes to reconstruct Variolite Street between Alpine Drive and 173rd Avenue.
Included with this project is the extension of 12-inch trunk watermain from 166th Avenue to 173rd Avenue in support of the 2040 City of Ramsey Comprehensive Plan. The plans currently out for bids include 3,341 lineal feet of 12” DIP class 52 watermain, which is installed by digging a trench 8-plus feet deep and roughly 20 feet wide at the surface. For reasons noted later in this case, Staff would like to receive an alternate bid to replace the 12” DIP watermain with 3,341 lineal feet of 12” HDPE watermain. If Council approves this alternate bid request an addendum to the plans will be issued calling for Alternate Bid B (the signalized RRFB pedestrian crossing signs are Alternate Bid A).
The watermain design in the plans out for bids already includes 1,204 linear feet of 12” directionally drilled high-density polyethylene (HDPE) watermain for use in crossing under the Trott Brook culvert. This design is necessary to prevent wetland impacts that would result from jacking a steel carrier pipe under the culvert as needed to convey the 12” DIP watermain. Jacking a carrier pipe requires large pits to be dug on each end of the carrier pipe, which would impact the adjacent wetlands due to their close proximity to the street. Directional drilling the HDPE pipe will allow watermain to be bored under the road and culvert at a prescribed line and grade, meaning the pipe is gradually bent as it is bored allowing for long runs and preventing the need to dig pits near the wetlands.
As currently designed, the HDPE watermain connects to DIP watermain about 500 feet on either side of Trott Brook. If HDPE watermain is installed in place of DIP watermain, open trenching would not be required and the watermain could be installed faster, resulting in fewer impacts to the traveling public and abutting property owners.
Staff has estimated the construction cost savings associated with Alternate Bid B at just under $30,000 due to a reduction in disturbed area requiring less restoration, less dewatering, and less hauling, stockpiling and loading of reclaimed pavement materials. This amount does not factor in other benefits such as a shorter construction schedule, and safer working conditions.
Notification:
Upon Council approval, plans will be revised and an addendum will be issued including Alternate Bid B.
Observations/Alternatives:
Observations:
The City has very minimal experience with HDPE pipe but based on feedback from other cities and industry experts, the anticipated life of HDPE pipe can generally be expected to be about the same as DIP, and field connections can be made as easy or easier than with DIP pipe. The main difference is that a tracer wire must be run with HDPE pipe.
Alternatives:
Alternative #1 – Adopt Resolution #20-107 authorizing Alternate Bid B to replace all ductile iron pipe (DIP) watermain with high-density polyethylene (HDPE) watermain for Variolite Street Reconstruction, Improvement Project #20-01.
The City has very minimal experience with HDPE pipe but based on feedback from other cities and industry experts, the anticipated life of HDPE pipe can generally be expected to be about the same as DIP, and field connections can be made as easy or easier than with DIP pipe. The main difference is that a tracer wire must be run with HDPE pipe.
Alternatives:
Alternative #1 – Adopt Resolution #20-107 authorizing Alternate Bid B to replace all ductile iron pipe (DIP) watermain with high-density polyethylene (HDPE) watermain for Variolite Street Reconstruction, Improvement Project #20-01.
Funding Source:
All costs associated with Alternate Bid B will be paid from the Water Fund, though it is anticipated that this will save nearly $30,000 in construction costs. Approving this request will allow Council to have firm numbers to base their final decision on regarding whether to use DIP or HDPE watermain at the time bids are presented.
Recommendation:
Staff recommends Alternative #1.
Action:
Adopt Resolution #20-107 authorizing Alternate Bid B to replace all ductile iron pipe (DIP) watermain with high-density polyethylene (HDPE) watermain for Variolite Street Reconstruction, Improvement Project #20-01.
Attachments
Form Review
| Inbox | Reviewed By | Date |
|---|---|---|
| Kurt Ulrich | Kurt Ulrich | 05/21/2020 04:52 PM |
- Form Started By:
- Bruce Westby
- Started On:
- 05/20/2020 02:33 PM
- Final Approval Date:
- 05/21/2020