Webinar Q&A: Lower Peninsula Stormwater Improvement: The City of Tampa’s nature-based solution to urban flooding that improves water quality
In this Stormwater University webinar, Chris Chandler of AtkinsRéalis, explored a recent success story of a nature-based solution to stormwater management lies within South Tampa, near MacDill Air Force Base. The project alleviates chronic widespread flooding that has plagued the Lower Peninsula Watershed for decades, while reducing pollutant and nutrient loads to Hillsborough Bay. The project design uses space within a previously unmanaged 48-acre forested site to alleviate flooding and improve water quality by storing and treating stormwater runoff from surrounding residential areas, while providing the community a beautiful passive park supporting an abundance of native wildlife. Watch the webinar on-demand to hear about this unique project from AtkinsRéalis – the design firm for this large progressive design-build project, and below, find the answers to common audience questions from the live event.
Audience: "Has there been any backflow from tidal conditions in the bay?"
Chris Chandler: In 2024, Hurricane Helene brought a significant storm surge into Tampa Bay, which did backflow into the pond. Due to frequent and heavy rainfall events shortly after, the brackish influx flushed out relatively quickly, and the freshwater ecosystem was able to recover.
Audience: "During public input/outreach, was this open to all residents or just those in the area? Was it held at the park? Did you have residents who were opposed to the project (or portions of the project)?"
CC: Public meetings were open to anybody who wanted to attend, though the outreach effort focused on the residents directly impacted by construction. One meeting was held virtually due to COVID-19 concerns, and another was held at the city’s Skyview Park, directly adjacent to the MacDill 48 site. While some residents were initially opposed to the project, there has been a tremendous amount of positive feedback from the community since the park opened in November of 2024.
Audience: "How long was the construction period?"
CC: Construction of the entire project lasted about two and a half years. The MacDill 48 Park was completed and opened to the public in less than 2 years.
Audience: "Were there any concerns or challenges installing the box culverts under the road?"
CC: Large box culvert installation beneath the roadway within residential areas required a significant amount of utility coordination, relocation and reconstruction. Construction activities used the entire roadway corridor, resulting in temporary road closures until incremental restoration could be completed behind the active construction, moving the project forward.
Audience: "What programs were used for the modelling and design of the project?"
CC: XPSWMM was used to develop the project’s hydrologic and hydraulic models. AutoCAD Civil 3D was used for formal design and plans production.
Audience: "Are the weir 'windows' designed at graduated elevation or are the invert elevations the same across all weir 'windows'?"
CC: The weir “windows” on the sides of the structure are constructed at the same elevation. Their primary function is to discharge excess runoff DURING a rainfall event. The invert of the 5-foot-wide weir within the end face of the structure was constructed one foot lower than that of the others, to control the fluctuation of water levels within the pond BETWEEN rainfall events. This single weir functions as a “bleed down” mechanism, with enough capacity to minimize the duration of potentially harmful inundation over the forested wetland mitigation areas.
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