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

Video Transcription

Video Summary

The presentation explores lake backfilling as a cost-effective alternative to deep foundations for developing large quarry sites in western Miami-Dade County. Because thick, compressible lake-bottom sediments can settle under backfill and warehouse loads, the speakers emphasize characterizing both sediment thickness and fill materials.<br /><br />At Site A, geophysical surveys, diver probing, and laboratory tests identified a relatively thin sediment layer and evaluated mixtures of shot rock, cyclone sand, and muck. Results showed that mixtures with more shot rock generally had higher densities and bearing values, while higher muck content reduced performance. The team recommends continued testing during the multi-year filling process.<br /><br />At Site B, construction debris had already been used to fill the lake, leaving an average 10-foot compressible layer beneath about 44 feet of fill. Deep dynamic compaction would not address this layer, so the team recommended an 18-foot preload. Monitoring recorded roughly 25–35 inches of settlement, mostly within 60 days. Preloading proved effective and economical.

Keywords

lake backfilling

deep foundations

quarry site development

compressible sediments

preload settlement

geotechnical testing