Palm Beach County, FL

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P&J Role

Prime Contractor

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Completion Date

October 2007

Project Description

The L-8 Reservoir is a unique, 950-acre former rock mine with a watertight geology that allows for deep, below-ground storage of water which minimizes water loss through evaporation and eliminates levee safety concerns. Initially approved in 2002, the reservoir has a storage capacity of 46,000 acre-feet of water that can be released in a controlled manner into the regional canals system for restoration under the Comprehensive Everglades Restoration Plan, for water quality buffering in Southeast Florida’s Stormwater Treatment Areas (STAs) – a vast amount of wetlands that maintain regional environmental equilibrium, and for use as a regional water supply. The reservoir will eventually become one of three Flow Equalization Basins in the State’s restoration strategies plan, providing 99,000 acre-feet of storage for delivery of water flow needed to optimize the performance of the region’s STAs. 

Project Highlights


CY Levee Foundation Preparation


LF Levee Embankment on 3:1 Slope


CY Underwater Material Dredged & Placed


LF Return Water Canals Constructed


LF Emergency RCC Spillway


LF Temporary Sheet Piling Installed


LF Inspection Roads & Stormwater Drainage


LF Bentonite Slurry Wall 75' Deep


P&J was the prime contractor on the L-8 Reservoir. P&J utilized machine-controlled grading during the project and was responsible for the coordination of utility relocations and for coordination with various federal, state, and county agencies related to permitting for and construction of the reservoir. The contract for the project also included site preparation for three adjoining land parcels which was accomplished by placing dredge material in various areas of the parcels to create a more usable property for future development. 

While P&J’s final contract amount for this project was approximately $41M, this included our Construction Manager at Risk fee and self-performance costs that generally included work associated with the embankment, dredge spoil management, and RCC mixing and placement for both the emergency spillway and flat plate along with the installation of a toe drain around the interior perimeter of the reservoir embankment. P&J was also responsible for the deployment and coordination of the owner-provided mining resources and the dredging operations. When these activities are considered, the total construction cost exceeded $125M, and the transfer price to the local water district was in excess of $20M. In association with our work performance, P&J extended contractor financing of approximately $29M. 


As the project progressed, several areas of the property were discovered to be in conflict with the typical design parameters. P&J worked with the design engineer, BCI Engineers & Scientist (BCI), to develop cost-effective alternatives to resolve the newly discovered issues. 

For example, the berm at the west end of the reservoir along Cells 4 & 5 did not have the required width to construct a typical earthen embankment. P&J and BCI developed a plan to use an RCC typical on a 2:1 slope to meet the overall design requirement that would fit in the available footprint. This alternate design actually provided an emergency spillway for the project that proved very advantageous to the operations of the reservoir. 

In order to ensure the reservoir met seepage requirements established by the South Florida Water Management District, the owner decided to construct a slurry wall around the east, south, and west sides of Cell 6. This proved to be a challenge since the wall was 75’ deep and had to penetrate the existing rock layer. P&J suggested “mining” the -200 sieve materials from the old process pit to minimize cost to the project. This material would greatly reduce the amount of bentonite required to reach the 1 x 10-5 permeability required for the slurry wall. P&J successfully mined and delivered the -200 sieve material to the slurry wall subcontractor and ultimately saved the owner $250,000 in material costs.