Pinnacle at Spear

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 an engineering consultant 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.

Best Management Practices

Gravel Wetlands, Sand Filter, Detention Basin, Swirl Separator.

Pond B – Sand Filter

Pond B – Sand Filter

Pond M07 – Detention Basin

Pond M05 – Prior to upgrade

Timeline

The City is currently under contract with Munson Earth Moving, Corp. for the upgrade of these four (4) stormwater systems. The work has been largely completed on three of the four systems (Pond B, Pond M05, and Pond M07). The gravel wetland to the north of Pinnacle Drive (Pond A) is scheduled for construction in 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: 11/14/2018