Winooski is a small city with a large vision. Northern New England’s most densely populated—and Vermont’s most diverse—municipality continually and creatively seeks ways to elevate the quality of life for its 8,300 residents living within a 1.5-square-mile area. A robust visioning process led to an ambitious downtown revitalization project and the community now anticipates the transformation of a key gateway corridor. Complex utility engineering efforts led by VHB and its project team will be instrumental in bringing to life this vision fashioned over a decade by the city.
A Reimagined Gateway
The Main Street Revitalization (MSR) project represents the city’s wholesale reimagination of one of its designated “Gateway Districts.” Garnering attention from the Federal Highway Administration and Vermont's Governor and U.S. Senators, the $18M project will be a catalyst to redevelop the city’s north end. Reconstructing a 4,000-linear-foot corridor from the New England Central rail line bridge to the Colchester town line, this transformational project will remake a constrained, outdated car-centric roadway into a vibrant public space. The safety, placemaking, and economic vitality expected as outcomes of this re-envisioned corridor will largely depend on an oft-understated aspect of any impactful project: the carefully considered relocation and replacement of vital utility infrastructure from aerial to underground locations. Funding for the project is being provided through multiple sources, including USDA Rural Development, the Vermont Clean Water and Drinking Water State Revolving Funds, the Vermont Petroleum Cleanup fund, and Northern Borders Regional Commission, as well as the City of Winooski and the Chittenden County Regional Planning Commission.
Safeguarding pedestrians—particularly the many schoolchildren who use this route—and bicyclists and making the corridor more accessible to them were some of the MSR project’s drivers. This segment of Main Street (US 2/7) connects some 15,000 cars a day to Burlington, Colchester, and I-89 but has no bicycle accommodations, few pedestrian crossings, and narrow sidewalks. Frequent vehicle crashes also made change imperative for this principal arterial and Class 1 Town Highway.
Early rendering of the proposed corridor
Utility poles along the city’s four-rod (66-foot) right-of-way (ROW) line border the problematic roadway configuration, which primarily consists of a 48-foot curb-to-curb width with two 14-foot travel lanes and on-street parking. These aerial utilities pose a barrier to the future development and redevelopment the community envisions for this Gateway District. By approving Form-Based Code (FBC) zoning for the corridor, the city hopes to fully realize the potential of properties lining Main Street; however, the FBC requires building new structures to the edge of the ROW where the utility poles are now situated. The poles also visually clutter the corridor’s viewshed, detracting from the sense of place the community hopes to create.
Undergrounding the electric and telecommunication infrastructure on Main Street would remove a significant barrier to the visionary rebalancing of the corridor with a narrower road and wider sidewalk, bulbouts, new crosswalks, a dedicated uphill bike lane, and street trees and other landscaping elements to enhance the aesthetic and treat stormwater runoff. It would also minimize the cost to developers to reconfigure their sites’ street frontage. VHB met multiple times with Green Mountain Power (GMP), the area’s electric service provider and primary utility who, along with telecom provider Consolidated Communications, owns the poles, to identify a viable relocation route. With six telecom companies—Consolidated, VTel, Burlington Telecom, Lumen, First Light, and Comcast—owning equipment on the corridor, the City’s DPW and VHB undertook an extensive coordination process. Discussions among the MSR project team, GMP, and the city considered three utility relocation alternatives.
The alternative selected by the city involves relocating the current overhead 34kV lines to Weaver Street, which runs parallel to the Main Street corridor, between West Spring Street and Tigan Street. A new 15kV underground line will be installed beneath Main Street between West Spring and Tigan Streets. The 15kV line will be buried under the roadway and sidewalks, providing service connections along the Main Street corridor. To reduce the amount of conductor needed and to make power distribution more efficient, above-ground vaults will be strategically placed along the corridor. Spare conduits will be added to the telecom duct bank to support future development on the corridor.
Compounding the complexity of the project’s utility engineering, the city’s antiquated water and wastewater lines along Main Street require upgrading. Deteriorated and insufficiently separated, the undersized 3,700-foot cast iron water main (140 years old) and 3,700-foot vitrified clay tile sewer main (130-plus years old) pose risks to the city’s drinking water and wastewater systems. To address these concerns, the project will include full replacement of the water distribution system on Main Street with 8-inch-diameter ductile iron piping and new water services from the main to the edge of the ROW. Main line valves and fire hydrants as well as a pressure-reducing valve will also be replaced. Due to the presence of soil contaminants, the ductile iron pipe will be treated with a zinc coating, installed with Viton gaskets, and wrapped in polyethylene. The water main’s location achieves the 10-foot minimum horizontal separation from the sewer main and the minimum five-foot separation from the storm drains.
Relocating utilities underground will allow new developments
to comply with the city’s Form Based Code
The sewer collection system will also be fully replaced with 8-inch and 12-inch-diameter SDR 35 PVC piping, new manholes, and new sewer services from the main to the edge of the ROW. To achieve the required vertical separation from water mains and services, the majority of the new sewer lines will be located one to two feet lower than the existing lines. As a result, the project will include constructing additional manholes at the side street interconnection locations.
Collaborating to Move Forward
Partnering with Winooski’s City Engineer, Director of Public Works, and City Manager, VHB completed a Preliminary Engineering Report and an Environmental Report in June 2018 alongside Dufresne Group. Once the reports were approved by the funding agencies, the team turned their attention to the design. Dufresne Group led the design of water and sewer infrastructure and provided guidance on the funding programs, and VHB developed the design of the roadway and streetscapes, underground utility conduits, traffic signals and lighting, stormwater facilities, and traffic control. VHB assisted the city with an 18-month ROW process, which largely focused on the location and installation of utility infrastructure, and the preparation of ROW impact plans. Harnessing technology, the VHB team completed a topographic survey on water and sewer utilities using hand-held GPS-enabled data collectors to collect field information, including sewer manhole locations and inverts and geotechnical boring locations; they then exported this data directly into CAD files. VHB also performed initial field screenings for the presence of contaminated waste with photo-ionization detectors in real time as borings were being conducted, followed by laboratory analyses to identify the extent and types of contaminants within the corridor.
The Project Team and City Council discuss the project
with the public during the planning phase
VHB worked with Dufresne Group to design the intricate underground utility network, comprising water, sewer, electric, telecom, gas, and drainage components, and LN Consulting, Inc. provided primary electrical line diagrams. Integrating roadway and streetscape improvements, the utility burial engineering involved resolving numerous conflicts—including relocation of a gas main throughout the corridor—to provide both high-voltage transmission and individual services within the public ROW while meeting utility separation requirements. The biggest challenge throughout the process was taking every planning angle into account to accommodate the city’s projected future growth without the need for rework, including close coordination with the Vermont Agency of Transportation for traffic signal upgrades associated with their adjacent, concurrent Exit 16 Diverging Diamond Interchange project. VHB submitted 90% Final Plans in December 2021.
The city’s project leadership has been instrumental in getting key stakeholders to the table as well as performing extensive outreach, which has generated project momentum and an overwhelmingly positive community reception to the MSR project. City Engineer Ryan Lambert said, "It's a great and necessary project that checks a lot of boxes for the city. Three years of Main Street under construction will be tough, but folks are thrilled to see the concept becoming reality." Following bid advertisement slated for May 2023, the first phase of construction, including utility undergrounding, will likely begin in the summer of 2023 with an anticipated 2026 project completion date. Winooski’s residents eagerly await the culmination of all these efforts in a central artery that comprehensively reinvigorates and reshapes the city’s north end into a safer, better connected, and more livable urban realm.
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