A major stormwater treatment project in Burlington is nearing completion, marking a significant step in protecting Lake Champlain from pollution. The Pomerleau Real Estate and Champlain Housing Trust – Gravel Wetland Stormwater Project has completed its final design stage, with all necessary permits approved. This public-private partnership, supported by the Chittenden County Regional Planning Commission, aims to improve stormwater management at 555 Shelburne Road and the Champlain Housing Trust’s South Meadow Drive property. Together, these sites cover 18.68 acres of impervious surface, triggering Vermont’s 3-Acre Rule and requiring a shared stormwater treatment system.

Innovative Design Tackles Runoff Challenges
At the heart of the project, in collaboration with Watershed Consulting, Hoyle Tanner provided engineering and design services for a gravel wetland, which will collect and treat runoff from 16.26 acres of pavement and rooftops. This includes the entire 555 Shelburne Road shopping plaza and a large portion of the South Meadow Apartments. To ensure effective treatment, two Hydro International First Defense vortex separators will provide pre-treatment, removing sediment and pollutants before stormwater enters the wetland. Due to site constraints and dense soils, traditional pre-treatment methods were not feasible, making these separators the best solution. Once treated, the water will be released into Potash Brook through a controlled outlet structure.

Construction Moves Toward 2025 Completion
Construction on the gravel wetland began in summer 2024, with Hoyle Tanner overseeing key project tasks, including contractor coordination, material inspections, and field observations. Crews have been working through the complexities of an already-developed site to implement the stormwater system effectively. A substantial completion review was scheduled for early February 2025, ensuring all components meet design standards. A final site visit in the spring will confirm full project completion.

"Construction site with workers installing a retaining wall using large concrete blocks. An excavator and a compact roller are in use, while workers in safety gear handle geotextile fabric. Stacks of materials and construction vehicles are visible in the background near residential houses.
Concrete Masonry Units (CMUs) are being laid to form the retaining wall separating the wetland from Pomerleau Real Estate’s parking lot. To the right of the wall, crushed stone is used as backfill with layers of geotextile in between, which increases the friction between the layers of backfill and stabilizes the material.
Construction site featuring a large retaining wall and a partially frozen stormwater retention pond. A worker in safety gear stands near a concrete drainage structure labeled 'SD Ireland.' Residential houses and construction equipment are visible in the background under an overcast sky.
The retaining wall is complete, so focus shifts to the hydraulic aspects of the project. The wetland has been excavated and shaped to provide the necessary amount of stormwater storage, and the structure allowing treated water to discharge to Potash Brook has been installed.

 

The slopes of the wetland have been stabilized with rock to prevent erosion, and the treatment area of the practice is being installed. Stormwater is treated by filtering through ¾” gravel, which is covered with layers of pea stone and soil in which phosphorous absorbing plants will grow.

A Major Step in Protecting Lake Champlain
Stormwater runoff is a leading cause of phosphorus pollution in Lake Champlain, contributing to harmful algae blooms and water quality issues. By filtering and treating the runoff before it reaches Potash Brook, this project will play a crucial role in reducing pollution.

Once fully operational, the gravel wetland will treat runoff from 16.26 acres and remove an estimated 9.94 kilograms of phosphorus annually. With the ability to manage approximately 821,000 gallons of stormwater for every two inches of rainfall, it stands as one of the largest stormwater treatment systems in Vermont’s history.

This project highlights the power of collaboration in tackling environmental challenges, demonstrating the feasibility of partnerships between municipalities and private landowners to manage stormwater to meet the requirements of the 3-acre rule. As construction nears completion, Burlington moves one step closer to a cleaner and healthier Lake Champlain.

Our Stormwater Experience
We have consulted with numerous communities on stormwater planning and funding initiatives and implementation of stormwater utilities. Our professionals have vast knowledge of existing local, state, and federal rules and regulations that affect this dynamic discipline. Reach out to me if you have stormwater needs in your area!