Applications, Observations, and Lessons Learned From Earthen Fill and RCC Embankment Construction With Cut-Off Wall in South Florida-Paper

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The C-51 Reservoir in Palm Beach County, Florida, is a regional water-storage project designed to capture wet-season stormwater that would otherwise flow into Lake Worth Lagoon. Phase I provides about 14,000 acre-feet of storage and is intended to supply 35 million gallons of raw water daily to seven utilities, while also supporting flood control and Everglades restoration.<br /><br />The reservoir perimeter includes earthen and roller-compacted concrete (RCC) embankments, protected by a roughly 20,400-foot seepage barrier extending through limestone into underlying sand. Most of the barrier is a soil-bentonite (SB) wall; a soil-cement-bentonite (SCB) section accommodates two large conveyance pipes. The wall was tied into the RCC embankment using vinyl sheet piles and grout-enriched RCC, with specially designed transitions between RCC and earthen sections.<br /><br />Variable-strength weathered limestone made conventional trench excavation impractical. Contractors fractured the rock using controlled drilling and blasting where permitted, and used rock trenching or perforated drilling near utility corridors where blasting was prohibited. Laboratory trials helped adapt SB and SCB mixtures to site water and locally available materials while meeting permeability and strength requirements. Construction also required careful trench stability management, fill quality control, and temperature controls; RCC production was conducted at night during hot periods.<br /><br />Key lessons included conducting preconstruction investigations and vibration analyses to select suitable rock-treatment methods; anticipating that approved borrow sources may not provide sufficient material and that excavated soils may exceed particle-size limits; and using digital data systems to improve real-time quality tracking and reduce manual reporting. The project’s success depended on locally optimized materials, tailored solutions for embankment transitions, and close coordination between contractor and quality-assurance teams.

Keywords

C-51 Reservoir

Palm Beach County

Florida water-storage project

wet-season stormwater

Lake Worth Lagoon

soil-bentonite wall

soil-cement-bentonite

roller-compacted concrete

seepage barrier

flood control