Building Class A Development Over Landfill-Paper

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The Sole Mia development in North Miami, Florida, is being built on a 184-acre former municipal landfill closed in 1980. The landfill, typically 20–25 feet thick, had to remain in place for most of the redevelopment. The project includes residential towers, mixed-use buildings, a hospital, roads, parking, utilities, and a lagoon.<br /><br />Langan evaluated the landfill’s settlement behavior through historical monitoring and full-scale pilot tests conducted in 2004–2005 and 2015–2016. Tests compared deep dynamic compaction (DDC), preload surcharge, and combinations of the two. Results showed that two DDC passes generally provided adequate improvement; four passes offered limited additional benefit. Preloading for about three months after placement allowed most primary settlement to occur. Where preload was removed, subsequent movement was negligible during the monitored period, indicating that DDC combined with preload can substantially reduce long-term creep settlement. DDC also produced more uniform ground behavior.<br /><br />Buildings were supported on augered cast-in-place (ACIP) piles extending through the landfill into underlying limestone and cemented sand. Design addressed potential obstructions, landfill debris intruding into piles, unstable working surfaces, and negative skin friction from settling landfill. Larger piles, reinforcement, stronger grout, deeper embedment, and predrilling were used as appropriate. Load tests validated pile capacities. Ground-floor slabs were either pile-supported, with utilities suspended from the structure, or constructed on grade over improved ground.<br /><br />By June 2023, multiple buildings and infrastructure were completed or under construction, with performance meeting design expectations and no unexpected geotechnical issues reported. Monitoring in improved areas recorded worst-case settlement of about one-third of an inch over 2.5 years.

Keywords

North Miami

Sole Mia

landfill redevelopment

deep dynamic compaction

preload surcharge

augured cast-in-place piles

settlement monitoring

geotechnical engineering

negative skin friction

mixed-use development