Problem
The Pinnacle at Spear neighborhood is situated within two stormwater impaired streams (Bartlett Brook and Munroe Brook). The medium density residential neighborhood’s existing stormwater system consists of a stormdrain and drainage pipe network that empties into one of four separate detention basins. These basins were constructed prior to the State of Vermont’s adoption of modern requirements related to the detention and treatment of stormwater.
Description
In 2017, the Lake Champlain Basin Program (LCBP) awarded the City a grant to evaluate the neighborhood and prepare an engineering design for retrofit of the existing detention basins. The City, Pinnacle at Spear Homeowners Association, and Aldrich + Elliott developed designs to retrofit two detention basins into subsurface gravel wetlands, retrofit one linear detention basin into a sand filter with added detention, and upgrading one linear detention basin to eliminate short-circuiting, provide pre-treatment, and reduce peak discharge rates.
Benefit
Retrofit of the Pinnacle at Spear Detention Basins will provide improved treatment for 36.42 acres, including 12.23 acres of impervious surface.
In addition, these stormwater treatment practices detain excess volumes of stormwater runoff and slowly release water to the brook. This helps prevent erosion of stream banks and reduce the risk of downstream flooding.
Stormwater Treatment Practices
Pond B – Sand Filter
Pond B – Sand Filter Construction
Pond M07 – Detention Basin Berm Extension
Pond M07 Upgrade
Pond M05 – Prior to upgrade
M05 Gravel Wetland Upgrade – Placing Stone
M05 Gravel Wetland Upgrade – Installing Piping
M05 Gravel Wetland Upgrade – Placing Pea-stone
M05 Gravel Wetland Upgrade – Gravel Wetland Soil Installed
M05 Gravel Wetland – In action
M05 Gravel Wetland
Pond A Gravel Wetland Upgrade
Pond A Gravel Wetland – In action
Pond A Gravel Wetland
Timeline
The City worked with Munson Earth Moving, Corp. for the upgrade of these four (4) stormwater systems. The work began in the fall of 2018 and was completed in June of 2019.
Total Project Value
$500,000
Funding Sources
The Lake Champlain Basin Program, Ecosystem Restoration Program, Clean Water Block Grant Program, the Pinnacle at Spear Homeowners Associations, and the South Burlington Stormwater Utility.
Last Updated: 7/3/2019