Reclaiming Deep Quarry Lakes in South Florida – A Geotechnical Perspective-PPT Presentation

PPT Presentation

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The presentation examines the geotechnical challenges of redeveloping deep quarry lakes in Miami-Dade County, South Florida. Quarrying of near-surface Miami Limestone created large lakes that are now attractive development sites, but reclamation must account for lake-bottom sediments and the strength and compressibility of backfill to limit future construction risks.

<strong>Site A</strong> is a roughly 200-acre lake, 40–60 feet deep, in the feasibility stage. Filling to the water level would require about 15 million cubic yards of material, with an additional approximately 2 million cubic yards needed to reach finished floor elevation. Sediment samples contained 29.4–76.6% fines, were non-plastic, and had 0.2–3.5% organic content. Laboratory testing evaluated quarry byproducts as backfill. Results indicated that mixes with 20% “muck” performed poorly in strength, density, and compressibility; further testing and a field test section were recommended to confirm mix designs and ground-improvement methods.

<strong>Site B</strong> is a roughly 110-acre lake reclaimed with construction debris and developed for industrial warehouses. Because deep dynamic compaction would not reach a silt layer approximately 25–30 feet below ground, preloading was selected as the most technically viable and cost-effective improvement method. The project used staged filling and preload planning to manage settlement and reduce excess fill. Measured settlements within warehouse pad areas reached approximately 30–35 inches.

Overall, the presentation emphasizes that reclamation design requires detailed evaluation of subsurface conditions, backfill properties, bearing capacity, and settlement. Selecting appropriate improvement methods and carefully managing preload are essential to reduce post-construction settlement risks.

Keywords

geotechnical challenges

quarry lake redevelopment

Miami-Dade County

Miami Limestone

lake reclamation

backfill properties

settlement control

preloading method

dynamic compaction

subsurface conditions