2023 ACEC Vermont Engineering Excellence Awards Merit Recipient: Water Resources
The City of South Burlington has long aspired to have a city center that promotes prosperity, nurtures growth, and anchors their community. After years of planning the South Burlington City Center is now a reality. At the core of this new downtown is the recently completed municipal building that combines City offices with a library and community center. This new building provides an activity hub for the community and is designed to tie together the adjacent residential, educational, and commercial uses along the newly reconstructed Market Street.
The initial challenges presented were space limitations and unusual phasing issues. Allard Square had recently finished construction for their underground parking access, which ran directly through the library’s site. In addition, the traffic flow and circulation for the elementary school would be impeded if they weren’t given due consideration. This required working with adjacent property owners and the Market Street team to find solutions and make adjustments in real time. For Allard Square, we were able to work with their staff and the City to route a new connection to the garage level.
Similarly, the primary access drive to Marcotte Central School ran through the building footprint, requiring a new route. The project also required parking and stormwater treatment on school property to the north. This required parking lot changes and replacement of an existing stormwater system. Working with the school district and City staff we were able to reconfigure parking and driveways to maintain the same number of parking spaces and to improve circulation for the school. We were also able to design stormwater systems that exceeded requirements of both the City and State while bringing the school site close to compliance with the upcoming 3 AC stormwater requirements.
Systems for stormwater treatment and flow control were challenging for this project due to these tight site constraints as well as the need to replace existing storm systems and manage both pre and post construction discharge to Market Street. Although soils on site were sandy, groundwater depths prevented the use of infiltration-based systems for water quality treatment. To tackle this impediment with minimal impact on the adjacent elementary schools’ operations we designed and implemented five high-rate biofiltration systems. These treated surface runoff and allowed stormwater to be fully treated above the seasonal high-water table. The treated runoff then flowed to one of two large underground storage galleries. This new system enabled us to provide groundwater recharge without relying on filtration in the underlying soils.
Coordination of the project design with adjacent stakeholders required ongoing communication and working with their project teams. Our solutions were designed to satisfy the needs of these neighbors while also meeting the project’s objectives. This level of communication and collaboration made our typically invisible role as site engineers central to the discussion, enhancing everyone’s understanding of how these elements are interrelated. In addition, the project location – central to the new downtown and elementary school makes these stormwater systems highly visible to city residents.
This project demonstrates a way to fit and retrofit high value stormwater treatment and groundwater recharge onto a site with a minimal surface footprint while also providing a high level of storage and flow control. The project location – at the new city center and next to a library and elementary school makes these systems highly visible to a large portion of City residents, including overviews from the new building. The proximity to the school itself offers educational opportunities.
In July of 2021, this facility opened to the public. The original RFQ indicated that this was to be a “catalyst project”, and to provide a central gathering place for residents. Given the rate of construction on Market Street and the amount of use seen by this new building, those goals have been achieved.