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Wilmington’s Riverfront Park

Wilmington’s Riverfront Park

Along the Cape Fear River, Riverfront Park, previously a lumber yard mill and cargo weigh station for the Port of Wilmington, has been transformed into 6.6 acres of newly accessible, versatile, waterfront open-space as well as a 7,000-capacity performance venue. As a new cultural destination for the City of Wilmington, the site goes above and beyond a singular purpose as a concert venue. The design enhances physical connections to nature and the water by mimicking the natural shoreline and drawing coastal marshes into the site. The design also seeks to encourage stewardship activities and reflection upon the City’s past with waterfront gardens that immerse visitors into the native riparian landscape, interpretive signage, and an interactive water fountain evoking a tidal spray.

In late 2020, it achieved verification through the WEDG® (Waterfront Edge Design Guidelines) program, making it the tenth WEDG Verified project and first project outside of New York City to meet the standard for excellence in resilient waterfront design. The project goes above and beyond the goals of a restoration to celebrate the native coastal ecology and illuminate the site’s history as a working waterfront.

Beginning in 2014, the design was shaped by an extensive community-driven master planning process led by the City of Wilmington. The City Council approved the master plan in 2015 and issued a publicly funded bond in 2016 to support the development of the park. In 2018, the project’s resilience was put to the test when Hurricane Florence struck the City of Wilmington during the park design process. 

The park’s sculpted waterfront edge deeply engages the river, replacing decaying riprap with a living shoreline that extends the native coastal ecology into the site, while lifted lawns and plazas offer spectacular views to the stage and Cape Fear. A diverse palette of native and adapted plant communities soften the shoreline, while a broad, urban tree canopy brings shade to the currently treeless and intensely sunny site. Urban gardens, creative children’s play, outdoor grass “rooms”, a park support building, and an interactive water feature are integrated along an arcing promenade, which traces the site’s historic train tracks and reaches out to the river. New boardwalks link the park to Wilmington’s signature Riverwalk, and connections for a future dock will allow for direct boat access to the park.

Photo: Hargreaves Jones

Hargreaves Jones led the design and engineering team for the project, working in close collaboration with the City of Wilmington, Live Nation, and contractor Clancy & Theys Construction Company to address the unique challenges of designing a waterfront park and event venue on an historic brownfield site. Stewart, an interdisciplinary design, engineering, and planning firm located in the Carolinas, led the civil, structural and geotechnical engineering for the project, and also served as advisory landscape architects.  The project maximizes re-use of brownfield soils on site, diverse opportunities for on-site stormwater infiltration, and landscape soils designed for resiliency within the context of the site’s dynamic coastal hydrology. We met with Stewart project manager Natalie Carmen, PE who led the civil engineering team on the project, to dive into the dynamic hydrology and how that impacted the final design: 

What features of the site’s hydrology did you take into consideration in designing the project for resiliency?

The Riverfront Park project offered a blank slate when we first visited the site. From east-to-west, there was a natural vegetation slope, large field, and of course the river. We found the entire site was covered with a two-foot-deep clean soil cap as part of the State’s brownfield agreement and the available environmental reports indicated the subsurface soil to be contaminated, including debris from a wide range of historical industrial uses. From the beginning, we prioritized reusing existing soil on site and separately considered the uses and placement for the clean cap soil and the brownfield soil. Proposed excavations for below-ground stormwater treatment and building foundations were part of the grading calculations. Given the proximity to the Cape Fear River and the known flood plain elevation, the finished floor of all buildings, including the open-air stage, were set above the 100-year flood elevation.

The next consideration is the water table, which varies with the topography across the site and fluctuates up and down with the tides. When designing the hydrology on site, we needed to take all facets of water movement into consideration: the surface flow, surface infiltration, as well as the groundwater flow and how to control that.

Our leading challenge was how do we design and engineer stormwater solutions to best serve the property with these considerations in mind.

What stormwater solutions did you implement?

The final Riverfront Park design has a suite of stormwater control measures to detain and treat the water-quality on-site and provide protection for the Cape Fear River. 

The site features seven state-regulated stormwater control measures: two infiltration systems and five permeable pavement systems. The infiltration system in the loading dock includes a subterranean sand trench under the stage building that hydrologically connects directly to the river. We worked closely with Eagle Resources to make sure the water was able to infiltrate between storm events. For both infiltration systems, an open-bottom vault stores the water on site allowing it to infiltrate through the native soils, with consideration for how that’s related to the river and the fluctuating nature of the hydrology on site.

From the beginning, the project’s goal was to respect the hydrology on site and go above and beyond the minimum requirements. The infiltration gallery in the main lawn is a good example of how we were able to both infiltrate the water as much as possible for the site’s ecology and maximize the functionality of the site, helping to ensure it drains well from a venue perspective.

I understand there are a lot of passive solutions in play. Can you elaborate on those?

The site’s natural ability to infiltrate water was prioritized during the design. Planned programmatic elements were married with the stormwater design approach to maximize the public’s use of the site, and go beyond minimum regulatory requirements, to incorporate many passive stormwater treatment elements that support the overall narrative of the park serving the broader community.

There is a significant amount of passive runoff where the soil itself was designed to infiltrate and detain that water quality volume of water. There are also five permeable pavement systems, three along Front Street and two on Nutt Street promenade.

These soil systems designed by Landis, LLC will serve the project perpetually by being paired with native plants that will maintain surface infiltration rates as the park ages and matures. 

It sounds like having a strong understanding of local topologies and native plants can play a large role in these projects. Can you tell me more about that?

Landscape architects at Hargreaves Jones counseled with our landscape architecture team at Stewart to understand the ecoregions of the Carolinas in the selection of plantings. The team identified what would work well in an urban evolving riverfront condition for the topologies and ecosystems of the riparian riverfront all the way up into the uplands gardens, ultimately including more than 200 trees of 20 different species and understory plants. 

Using native species is an approach indelible to the Stewart design process, as well as meeting WEDG standards, that creates sustainable projects that are easily maintained but also display the beauty of the natural environment that is occasionally overlooked.  

You mentioned one of the infiltration systems included elements that go under a building, and I understand you worked closely with your firm’s structural engineers. Can you share how the below-grade water systems impacted the structures on site?

Riverfront Park features three buildings and a performance stage, as well as monolithic stairs and walls, all designed by our structural engineering team at Stewart led by Tom McLane, PE, project manager, in collaboration with Sage and Coombe Architects. Based on information gathered by Stewart’s geotechnical engineers through a comprehensive exploration program consisting of cone penetration testing (CPT) and test pits, the amount of debris and variations in the existing soil was discovered to vary greatly, even over short distances. Using this information, our structural team designed the buildings, and several of the cast-in-place concrete retaining walls to be supported by 8-inch diameter timber piles that were driven an average of 45 feet into the ground to develop the required capacity. 

The interior floor and stage slabs were also designed as reinforced structural slabs due to the potential of settlement to reduce the potential for cracking. The buildings are also elevated at least two feet above the base flood elevation, meaning the park and its facilities will be a valuable community resource for years to come.

Beyond the stormwater solutions, another piece of the complexity is there are two public sanitary force mains that were installed under the Cape Fear River and through the property during the park design process. The utility provider shared the intended location of these under-construction force mains and the structural team developed creative structural solutions spanning the stage structure over the force main. 

Helical piles were used near and battered away from the force main to allow for 12 feet of clearance on each side at the same elevation. The helical piles made the battering of the piles easier and removed the impact and vibrations that the driving of the timber piles would have caused, which could have damaged the force main. A similar approach was used at the Cowen Street retaining wall. This 9-foot-tall cantilevered and tapered board-formed face retaining wall is a feature at the entrance to the park that also spans 40 feet over the force main. 

This allowed for the park to seamlessly function on the surface while the structural design solutions respected below-grade utilities through a horizontally spanning foundation system.

Throughout our conversation, the features of the existing soil as identified by Stewart’s geotechnical team continue to arise. Can you touch on the importance? 

Without the experience and perspective that our geotechnical engineers brought to the table, many of the site challenges would have been insurmountable to develop on, and the contaminated land would remain dormant. This site required an inherent knowledge of the physical properties of soils, so intimate that when a soil departs significantly from its natural state the engineer can reasonably estimate its anticipated performance under different states of compaction and loading conditions. 

Other design professionals, including myself, brought their expertise to the design and treatment of the near-surface soils, to the utilities that carve through the site at shallow and deeper depths, to the structures that rise out of the ground and provide an entertainment venue to the public. But the geotechnical engineers provided design recommendations to support all the remaining design elements. The result is a civic amenity that will serve the City of Wilmington and the greater community for generations to come. 

Land that had been sculpted into a harbor, a railyard, and an industrial storage facility could once more be re-imagined and sculpted into a marsh at the river to restore native ecology and a dramatic slope at the heart of the park to both elevate concertgoers on the west face and provide natural retreat for the city dwellers on the eastern slope.

Future of Waterfront Spaces

Riverfront Park serves as a valuable case study for how waterfront open space can flexibly accommodate diverse uses—from daily respite and recreation to large-scale concerts and civic festivals—while also prioritizing urban connectivity, enhanced ecologies, coastal resilience, and a renewed focus on water resources.