A+E Presents Stormwater Project at GMWEA Spring Show
May 25, 2023
Merrick Gilles presented on A+E’s ongoing collaborative work to evaluate stormwater treatment alternatives for the St. Albans Lower Weldon site. This innovative study seeks to meet the City of St. Albans required flow targets and potentially provide treatment opportunities for several private 3-Acre parcels within the City limits.
The site, an abandoned cooling pond, provides a rare opportunity to incorporate a large stormwater BMP in a well-developed downtown City area. Due to the history of the site, various recognized environmental conditions (RECs) were discovered and characterized during this phase of the study. Identified historic waste and urban background soils suggest that the recommended alternative limit site disturbance.
The existing hydraulic conditions were updated during the study period. Initial modeled results of expected flows didn’t agree with field verifications. Monitoring units were deployed to adjust the hydraulic model and better characterize expected flows at the proposed practice location. The determined WQv, CPv, 10-yr, and 100-yr storm flows were then used for design of the stormwater practice.
A variety of stormwater practices were evaluated including below ground storage, a open stormwater pond, and a gravel wetland. The pros and cons of each practice were discussed followed by a presentation of the proposed treatment practice, which includes a upstream bypass system, gravel wetland, hydrodynamic separators, and design of a stormwater pumping station.
The presentation concluded with a discussion of the opportunities/challenges presented by the proposed Public/Private partnership including ownership concerns, construction cost sharing, and level of engineering required prior to the City offering any capacity to private land owners. Following Merrick’s presentation, he fielded a variety of questions regarding multiple aspects of the project.
A+E has been assisted by Waite-Heindel Environmental Management and Watershed Consulting Associates, LLC on this project to date.
