When municipal solid waste (MSW) disposal facilities reach the end of their lifecycle, many are re-envisioned to serve their communities in new ways. In Boca Raton, Florida, the S.W. 18th Street Landfill accepted construction, demolition and hurricane debris, and MSW from 1949 to 1969. At the turn of the millennium, the northern portion of the approximately 40-acre site was reconfigured into a community park with sports fields, restrooms, parking and other amenities. A few years later, a landfill redevelopment project on the southern parcel was initiated but ultimately stalled with the “great recession.” Recently, local community lobbying and a renewed commitment to activities along the waterfront led city officials to ask KCI to update the original design and site plan for a proposed recreational site.
Converting former landfills into public places is a common practice but presents several unique design challenges. This project required extensive coordination and collaboration between our team’s geotechnical, civil and environmental engineers, and landscape architects, to address complex soils concerns and permitting requirements.
Trash and debris decompose at different rates, leading to gradual and inconsistent settling of garbage that can cause instability in the ground over time. To safely redevelop the site, engineers performed extensive geotechnical investigations to probe for unsuitable soil. Field visits and inspections during construction facilitated soil and density testing as well as oversight of installation of stormwater facilities and site grading.
Once construction began, KCI partnered with the city’s staff to provide inspection services. This collaboration, along with weekly meetings, helped to keep the project on schedule and allowed the team to efficiently work through conflicts as they arose.
Todd Mohler, RLA, ISA, IASenior Project Manager
The cost prohibitive expense of off-site disposal of waste and contaminated soil formed the crux of the waste strategy. In order to avoid those costs, on-site waste relocation and an engineered control, capping, were employed, making it possible to build on top of the landfill. Capping is a method which involves placing a cover over the waste to isolate hazards and keep them in place to avoid the spread of contamination.
Capping at the south site was achieved in pervious areas with two feet of imported uncontaminated fill and in non-pervious areas with traditional development materials such as brick, asphalt and concrete. To ensure that the cap remains protective, a plan for long-term maintenance and monitoring of the site was put into place.
Working from the city’s previously developed concepts, our team performed a value engineering study and proposed several landfill redevelopment modifications. One major overhaul included re-designing the drainage system. Original plans called for underground piping; however, the cost and complications associated with excavating waste presented many challenges. Revisions included re-grading the site to prioritize surface drainage, eliminating more than 90 percent of the piped stormwater system. Additionally, a storm retention area was sited based on existing waste locations to eliminate the need for lining.
Changes also focused on the landscape. The new design created a more modern playground space by incorporating topography as an element. Rolling terrain enhanced the aesthetic scenery of the park and added another dimension of play. Other recommended site enhancements included adjusting the grading plan to preserve some of the area’s larger existing trees and utilizing native plants in concentrated beds to reduce maintenance.
Due to the site’s location adjacent to a wetland, a newly designed native landscape buffer will help meet setback requirements that protect the water quality and wildlife habitat along the waterway. To further support the landscape, our team tied the irrigation design into the city’s central control system, which provides precise and efficient scheduling and management of watering based on environmental variations.
Open from dawn to dusk, the 14-acre landfill redevelopment offers local and regional visitors a playground, basketball court, pickleball courts, volleyball court, tennis courts, walking paths, picnic pavilions, a soft launch area for canoes, kayaks and paddle boards into the El Rio Canal, as well as parking and restroom facilities.