Palm Beach Co.'s System 3

$36.5 million project one of biggest of its type in Florida

By Debra Wood

To enhance the quantity and quality of available drinking water, Palm Beach County Water Utilities Department has contracted with Poole & Kent Co. of Miami to construct a $36.5 million facility at its System 3 Water Treatment Plant west of Delray Beach.

The new structures will replace existing water-treatment facilities and enable the county to increase production to 30 million gallons of drinking water per day. The plant will use nanofiltration technology, which uses a partially permeable membrane to remove organic compounds and soften the water.

"Because it's an expansion of an existing facility, we're constructing the plant in phases while the existing plant continues to run," said Larry Johnson, project manager for the county. "We are going to be converting the existing membrane-softening plant to house our pumping equipment. We will be demolishing the interior of the existing process plant and installing the pumping systems for the new plant in that existing building."

Poole & Kent began construction in June 2002, with final completion of the four-phase project scheduled for June 2005. The company is part of the EMCOR Group of Norwalk, Conn., as is the electrical subcontractor Dynalectric of Miami.

Camp Dresser & McKee Engineers of Maitland, Fla., is the engineer of record. About 60 people are working onsite.

The project includes six cast-in-place concrete and block structures, 10 new membrane softening units, upgrades on the chemical systems, two new 2,000-kw diesel generators for emergency backup power supply, a second clearwell, a transfer pump station and a 5-million-gallon storage tank.

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With the water table about 2 ft. below grade and the yard piping, duct banks and foundation under water, Poole & Kent installed an extensive dewatering system. Company officials had considered open pumping or well pointing but decided to use a deep-well system that Mike Brown, Poole & Kent's project manager, had used on a previous job in central Florida.

Crews strategically placed 15 40-ft.-deep, 6-in.-diameter wells connected to 5-hp pumps. The combination of wells drew the water table down 10 ft. This is the first time Poole & Kent has employed the deep-well technique in South Florida and is pleased with the results.

During the first phase, crews built the nanofiltration membranes building and installed pipes to the existing pumps, which will power the plant on a temporary basis.

Poole & Kent built the currently operating membrane plant in the 1990s. On the current project, during the second phase of construction, the contractor will demolish the interior and change its function to a pump building.

"We were literally working inside the existing building, and the contract design called for us to go in the building and drive sheet piling, remove all the existing slabs in certain areas, redo the piping and pour new slabs," said Pat Carr, executive vice president for Poole & Kent. "It was very unusual."

Brown sought to expedite work in the first phase to give the company more time to complete the more intricate second phase. He consulted with the structural engineers about ways to protect the existing structure while starting to demolish portions of the plant before the water supply is switched to the new nanofiltration units.

His concerns included the affect of vibration on the existing filtration units, the danger of undermining the foundation and risks associated with moving equipment around in the enclosed plant.

"We did some revision [on the plans]," Brown added. "For instance, the pipes were spread apart and deep. We moved the pipes up to a higher elevation and compressed them [the pipes] a little bit, so they can stay farther away from the building foundation."

The plan also minimized the need for driving sheet piles. The company installed half of the underground 42-in. and 54-in. pipe before shutting the plant down in January. Later the company put in 15 new 200-hp and 400-hp pumps.

Poole & Kent completed eight major tie-ins during regular working hours, but two additional tie-ins took place during off-peak water consumption hours.

"The contractor worked well with our operating personnel in coordinating the shutdowns that were required for installation of underground piping and being able to do this large project while still maintaining the operation of the existing plant," Johnson said.

Phases three and four involve installing a membrane clean system and final site work. Carr and Brown consider both later phases minor components of the job.

Carr said the new membrane plant "will be one of the biggest in the state."

System 3 Water Treatment Plant Project Team:

Owner: Palm Beach County Water Utilities Department, West Palm Beach
General Contractor: Poole & Kent, Miami
Engineer: Camp Dresser & McKee Engineers, Maitland, Fla.
Electrical Contractor: Dynalectric, Miami.