Bartlett Brook is one of five stormwater impaired waterbodies in South Burlington. The City is in the process of designing and constructing projects with the potential to reduce flows in Bartlett Brook, restore the Brook to health, and satisfy requirements in the City’s MS4 permit. One of the projects identified in the Bartlett Brook Flow Restoration Plan (FRP) included constructing stormwater detention in the upper field of the Horticulture Farm at UVM.
Tributary 7 of Potash Brook flows through the Butler Farms and Oak Creek Village neighborhoods. The brook passes beneath City streets via culverts in four locations before flowing into the Wheeler Nature Park located to the north of the neighborhood. Two of the four culverts were replaced as part of the Oak Creek Village Culvert Replacement project, which involved replacing the two downstream culverts under Moss Glen Lane in the OCV neighborhood.
When the culverts the neighborhood were originally designed, permitted and constructed they met the current requirements for culvert sizing. However, over time these standards have evolved and the original culverts are considered undersized relative to the standards in use today. Under current standards, new culverts must have sufficient capacity to pass stream flow during a 25-year storm event (4.0 inches of rain in a 24 hour period).
This project will include replacing the existing corrugated metal pipe culverts in both locations under Butler Drive with precast concrete box culverts. The new culverts will provide sufficient capacity to allow the stream to pass under the road without overtopping during the 25-year storm event. This project improves stream health and reduces the chance of flooding in the neighborhood during large storm events. It also improves the ability of aquatic organisms to move in the stream.
Replacement of undersized and aging drainage infrastructure with new appropriately sized drainage infrastructure.
This project has received grant funding support from VTrans. The remaining project costs will be paid using stormwater utility capital project funding.
As part of the Centennial Brook Flow Restoration Plan, a project was identified to retrofit an existing stormwater pond located on private property and divert runoff from a portion of Williston Road and East Terrace into the upgraded stormwater treatment practice.
Under current conditions, the existing stormwater treatment practice is not designed to modern standards and does not maximize phosphorus removal for the area draining to it. Additionally, the section of Williston Road and East Terrace in this area discharges directly to the stream with no treatment. By working together through a public-private partnership with UVM and Burlington, the untreated runoff can be routed to the upgraded pond, where phosphorus removal can be achieved and stream channel flows reduced.
The City of South Burlington Stormwater Utility received a grant from the Vermont Agency of Transportation to install two underground Stormwater infiltration practices in vacant lots adjacent to Airport Drive. The project includes the design and construction of two stormwater infiltration basins and drainage infrastructure to allow for the treatment of stormwater runoff form 0.825 acres of impervious surfaces and 0.614 impervious acres, for a total of 1.44 acres of impervious surfaces.
Previously untreated stormwater runoff generated from 1.44 acres of impervious surfaces discharged directly to the impaired Potash Brook near the intersection of Williston Road and Kennedy Drive. This project was identified as part of the Potash Brook Flow Restoration Plan (FRP), prepared by the City of South Burlington, in an effort to reduce flows to the impaired Potash Brook and improve water quality in the Lake Champlain drainage area.
The project reduces the peak flow of the 1-year, 24-hour storm event by 100%, from 2.06 cubic feet per second (cfs) to 0 cfs and infiltrates the water quality volume from 1.44 acres of impervious surfaces, reducing the amount of phosphorous going to Lake Champlain by 2.56 kg/year.
This project received funding from the Transportation Alternatives Grant Program administered by VTrans. The remaining project costs were paid using stormwater utility capital project funding.
