Burlington WWTP upgrade estimate rises $18.3m above bond ceiling

Burlington WWTP upgrade estimate rises $18.3m above bond ceilingBurlington Public Works Commission heard that the estimated cost of the city’s Stage 1 Main Wastewater Treatment Facility upgrade has increased to $145.45 million, versus $127.15 million authorized by voters in 2025. The principal uncertainty is ground improvement work at the Perkins Pier expansion area, while final design, value engineering and a CMAR review are intended to sharpen the figure.

The May 2026 Stage 1 estimate is $145.45 million, $19.13 million higher than the January estimate and $18.30 million above the 2025 bond total.

Ground improvements and revised structural costs account for most of the increase; further geotechnical investigation is planned.

PC Construction has been selected as CMAR and Stantec as owner’s adviser, with Wright-Pierce continuing as design engineer.

City Council approvals for design-phase contracts and an estimated $7 million-$8 million Clean Water State Revolving Fund loan amendment are expected in early fall 2026.

Stage 1 construction is preliminarily scheduled from July 2027 to July 2030, with tertiary phosphorus treatment required by around 2030 under the Lake Champlain TMDL.

Burlington’s proposed Stage 1 upgrade of its Main Wastewater Treatment Facility has moved into a critical cost-control phase after its estimate rose to $145.45 million at 30% design—$18.30 million above the $127.15 million bond authority approved by voters in 2025. The September 16 Public Works Commission meeting was informational only, but staff said they are preparing to seek City Council approval in early fall for the remaining design work, a construction manager at risk (CMAR) contract and an owner’s adviser, as well as a Clean Water State Revolving Fund (CWSRF) loan amendment. The combined design-phase approvals are currently expected to total $7 million-$8 million, subject to final scopes and fees. The May estimate increased by $19.13 million from January. Staff identified uncertain ground conditions at the Perkins Pier area, where the plant expansion is proposed, as the main cause. The cost plan shows the unburdened construction subtotal rising by $16.02 million between January and May, including $9.1 million for ground improvements and $5.1 million in other structural cost increases. Water Resources Engineering Manager Martin Lee told commissioners the range of potential cost increase was driven by soil uncertainty. Additional geotechnical work is planned, while staff said they would pursue value engineering and grants in an effort to remain within voter-authorized borrowing limits. A fifth secondary clarifier was identified as one potential item that could be deferred, although staff said it would be needed in the future and that any cuts would need to preserve required service. The city has competitively selected PC Construction as CMAR, following a process that received one statement of qualifications despite direct outreach to eight potential contractors. PC Construction is also completing Burlington’s Stage 0 headworks work. Stantec was selected from four consultant submissions to act as owner’s adviser, providing cost and schedule management, review of CMAR services and design progress, and construction-administration support. Wright-Pierce remains the engineer of record for final design. Under the CMAR model, PC Construction will work during final design on constructability, sequencing and cost efficiency before moving to a guaranteed maximum price during construction. Staff said this is particularly important because the wastewater facility must remain operational while major systems are replaced. The Vermont Agency of Natural Resources Water Investment Division approved use of CMAR and an owner’s adviser for CWSRF-supported work earlier this year. Stage 1 encompasses new enhanced biological phosphorus removal tanks, tertiary filters, pumping and clarifier upgrades, sludge handling, electrical distribution and standby generation. It is intended to renew aging assets, add capacity and enable compliance with a proposed lower annual phosphorus limit in the facility’s next NPDES permit. The preliminary schedule anticipates final design through February 2028, with early construction packages potentially beginning in July 2027 and overall construction running to July 2030. Staff said tertiary treatment must be operational by around 2030 to meet Lake Champlain total maximum daily load requirements. Separately, Stage 0 headworks improvements, including screening and grit-handling upgrades at Burlington’s three wastewater plants, remain on track to finish later in 2026 within the approved budget and contingency.