To: Honorable Mayor and Members of Town Council
From: H. Keith Johnston, Public Works Project Manager
Title
Discussion/Direction: Plum Creek Parkway Intersection Improvement - Construction Phasing
Body
________________________________________________________________________________
Executive Summary
The purpose of this memorandum is to present the construction phasing alternatives for the proposed improvements to the Plum Creek Parkway and Wilcox Street intersection. Staff will request Town Council direction for which of the phasing alternatives should be selected.
The Town has contracted with PLM Asphalt and Concrete, Inc. (PLM) to construct the Plum Creek Intersection Improvement Project. The approved construction plans include the “Alternate 1 Construction Phasing Plan” to complete the Plum Creek Parkway and Wilcox Street intersection. The objective of the Alternate 1 Plan is to construct the intersection in the least amount of time possible, while maintaining primary traffic flows to and from Interstate-25 along Plum Creek Parkway. The Alternate 1 Plan requires closure of various traffic movements within the Wilcox intersection during certain phases of the construction, with detour routes provided. See (Attachment A) for general depiction of the Alternate 1 Plan. The Alternate 1 Plan is estimated to take 35 calendar days and will be built in 3 phases.
As part of the construction contract, PLM has developed an “Alternate 2 Construction Phasing Plan”. The objective of the Alternate 2 Plan is to provide more traffic movements through the Wilcox intersection. The Alternate 2 Plan may require more phases of construction and consequently more time and expense to complete. The Alternate 2 Plan will be presented at the Town Council meeting.
Town staff and PLM has presented both of the construction phasing plans at an Open House meeting on May 12th. Town residents and business owners have been asked for feedback regarding the two phasing alternatives. Information regarding the public’s feedback will be discussed at the Town Council meeting.
Staff will provide an overview of the public feedback received on the options and recommend a preferred construction phasing plan at the Town Council meeting.
Notification and Outreach Efforts
At the time of the May 17th Town Council meeting, Town staff and PLM will have hosted an Open House scheduled for May 12th. Both construction phasing plans, Alternate 1 and Alternate 2, will be presented to the public for review and feedback. Town staff will provide the feedback information at the Town Council meeting.
History of Past Town Council, Boards & Commissions, or Other Discussions
• August 3, 2015, Public Works Commission was provided a project update detailing the scope of the project.
• February 16, 2016 Town Council was provided a project update detailing the scope of the project.
• March 15, 2016 Town Council approved a temporary variance to the Town’s noise ordinance to enable night work on the project (RES 2016-028).
• May 2, 2016 Public Works Commission provided a recommendation to Town Council to award the construction contract to PLM Asphalt & Concrete, Inc.
• May 3, 2016, Town Council approved a resolution awarding the construction contract to PLM Asphalt & Concrete, Inc.
Discussion
A primary objective of the Plum Creek Parkway Intersection Project is to remove the drainage crosspan or “dip” from the east side of the Plum Creek Parkway and Wilcox intersection. In the area of the “dip”, the street will be raised approximately 1 foot to provide a smooth east-west profile through the intersection. The function of the “dip” was to convey stormwater from the south to north through the intersection. Without the “dip” additional stormwater inlets are required on the south side of the intersection and consequently the stormwater pipe infrastructure must be extended through the intersection to serve the new inlets. Due to the amount of construction involved to reconstruct the east-west profile of the street and extend the stormwater infrastructure, it is necessary to reroute traffic as necessary to avoid the phases of construction.
Reconstruction of the intersection in the least amount of time possible would require a total closure of the intersection, although this is unfeasible due to the importance of this corridor and access to and from Interstate 25. To solve the problem of necessary access and long construction time, Town staff directed the design engineer to propose a phasing plan design that meets the primary demand of the travelling public and the businesses, while completing the intersection in the least amount of time possible. The main idea being to shorten the duration of negative impact to drivers and businesses. This phasing plan design is “Alternate 1 Construction Phasing Plan”. The Alternate 1 Plan is estimated to take 35 calendar days and will be built in 3 phases. A shorter timeframe was originally requested, but the Town received no construction bids. Upon discussion with a few contractors, they deemed the original time schedule to be impractical. The Alternate 1 Plan is the least expensive option and the cost is included in the approved contract amount.
Town staff has requested PLM to develop a second construction phasing plan. Staff is relying upon the contractor to know how the project can be constructed and the best way to phase the construction. The contractor will develop “Alternate 2 Construction Phasing Plan”. The Alternate 2 plan will provide more access north and south through the Wilcox-Plum Creek Parkway intersection. Although, because the entire intersection must be removed and rebuilt, there will be construction phases where lanes must be closed.
The Alternate 2 Plan will likely require more phases of construction and consequently more time and expense to complete. Alternate 2 will likely be the more expensive option and the additional cost must be agreed upon by the Town and the contractor. The Alternate 2 Plan will be presented at the Town Council meeting.
Budget Impact
If Alternate 1 Phasing Plan is selected, there are no additional costs for construction and the work will be completed under the existing construction contract.
If Alternate 2 Phasing Plan is selected, the Town and the contractor must agree upon the additional time and cost to amend the contract accordingly. Additional cost may be addressed by using the contingency fund, however, a budget amendment may be required if the additional costs exceed the contingency or leave insufficient funds in the contingency to address unforeseen contract revisions.
Staff will provide an estimate of any additional costs at the Town Council meeting.
Staff Recommendation
At the time of this writing, the feedback from the scheduled Open House is not available. Town Staff will provide a recommendation at the Town Council meeting.
Proposed Motion
There are three possible motions for Town Council to consider:
“I move to…
1) direct staff to implement the Alternate 1 Construction Phasing Plan.”
Or,
2) direct staff to implement the Alternate 2 Construction Phasing Plan using existing project funding.”
Or,
3) direct staff to implement the Alternate 2 Construction Phasing Plan and request a budget amendment to address the additional funding required for the amended contract.”
Attachments
Attachment A: Alternate Phasing Plan 1 Illustration