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The South Florida Water Management District's recently completed Stormwater Treatment Area 3/4 project represents some good news coming from the Everglades restoration project.
Since Congress first approved an $8 billion restoration of the famed Everglades National Park and the state of Florida approved the Everglades Forever Act in 1994, the news surrounding the restoration of the Florida Everglades has slowly become more negative than positive.
Funding issues and criticism from environmentalists and other groups - including even the U.S. Army Corps of Engineers, the stewards of the federal program - have combined to often give the general impression that the project is making little or no progress.
Earlier this year, for example, after Engineering News-Record ran a series of articles about the Corps' displeasure with the project's progress to date, the Construction.com Web site ran a national survey question asking, "The Everglades cleanup may be in trouble. What should Congress do©"
Twenty-one percent of respondents said Congress should open an investigation, and 35 percent said the Corps should be taken off the job and the state of Florida put in charge. Another 35 percent answered "Give the Corps more latitude," while the remaining 8 percent chose "Do nothing."
Earlier this year, a group of independent judges found that one of the more recently completed projects that is part of the $700 million Everglades Construction Project - a precursor to the $8 billion Comprehensive Everglades Restoration Plan - was the top engineering achievement in the nation.
Stormwater Treatment Area 3/4, a $160 million project conceptualized and engineered by Burns & McDonnell of Kansas City, Mo., took the American Council of Engineering Companies' top "Grand Conceptor" award as "the most significant U.S. engineering achievement" in the past year.
STA 3/4 beat out approximately 175 other projects by U.S. firms, including the new Rion-Antirion Bridge in Greece, Chicago's Millennium Park and the Seattle Central Library.
STA 3/4 is a man-made wetlands area measuring more than 26 square mi. and 16,500 acres in size, and it's the largest of the wetlands that have yet been constructed as part of the ECP and the largest constructed wetlands in the world.
For STA 3/4, Burns & McDonnell served as the design engineer and also provided engineering services during construction, consisting of job administration, drawing review and compliance, as well as onsite resident representation.
The firm started design work on the STA 3/4 contract in 1998, but had actually started design and master planning work for the South Florida Water Management District in 1993 when it prepared the conceptual design for the Everglades Construction Project. The firm first got involved with Everglades restoration work as far back as 1989.
The first construction contract for STA 3/4 began in March 2001.
Man-made Wetlands The basic goal of the project was to improve the quality of water entering the Everglades. This would be done by converting existing agricultural land into wetlands and reducing the level of phosphorous in the water resulting from stormwater runoff.
Galen Miller, associate vice president and project manager with Burns & McDonnell, explained that the concept behind creating the wetlands was actually a pretty simple one.
"Of course, this is South Florida, where the topography is pretty flat," he said. "Once you get an area down there wet, you've got wetlands."
Actually achieving that end was more complicated. Much of the land had previously been used for agricultural purposes, primarily sugar cane but also sod farms and other applications. Prior to the start of the STA 3/4 project, much of these agricultural lands had been cleared by SFWMD through previous contracts.
Miller said the basic approach to developing these man-made wetlands was to construct new levees and canals for control of water, as well as two pumping stations that could lift water out of existing primary conveyance canals onto the land surface. That was achieved through the construction of a series of automated water-control structures.
Once the area was flooded, the intent was for the vegetation to be entirely emergent, but was expected to be primarily cattails.
"Whatever grows there, and whatever likes that particular regime is what would take over," Miller said.
Again, the primary driver for the project was to reduce the amount of phosphorous in the Everglades waters. When compared to other waters around the country, the phosphorous levels were not that high. However, Miller said, "They were much higher than native Everglades species could accommodate."
One species of plant that could thrive in that environment is cattails. The growth of the cattails would enable the STA to minimize the phosphorous levels.
"The cattails take up phosphorous as they grow, so the basic sink for the phosphorous is the death of the cattails that grow," Miller said. "As the plants die and partially decompose, they create a peat that binds the phosphorous, thus preventing it from entering the Everglades."
The original, or interim, target for the concentration of phosphorous in the water was 50 parts per billion. To date, that concentration level has been approximately 20-25 parts per billion.
"That's a tremendous accomplishment," Miller said, elaborating that the Everglades projects were basically tests of whether this type of constructed natural wetlands could sufficiently reduce these phosphorous levels.
Since then, project authorities have determined a more stringent criteria should be adopted, and now the target for phosphorous concentration levels is 10 parts per billion. Burns & McDonnell completed a study in 2003 - two years after this STA 3/4 project started - that reviewed additional ways of further reducing the nutrient levels.
The firm is currently working with SFWMD to achieve these goals.
Multiple Contracts STA 3/4 was divided up into a series of five separate general contracts, including three covering primary earthworks and water-control structures, one for construction of two pumping stations and one for new bridges on U.S. Highway 27.
Another $18 million contract covered equipment supply-and-delivery for the large pumps, engines and transmissions needed for the pumping stations. This was handled by Ingersoll Dresser Pump.
One contract, valued at about $15 million, covered construction of about 12 mi. of supply canals and levee on new alignment and leading to the stormwater treatment area. A $10 million contract called for the expansion of about 8 mi. of existing canal to serve as an outflow conduit. A roughly $50 million contract included construction of the levees and the internal works for the STA itself.
All of these contracts were initially awarded by competitive-bid process to IT Corp. When that firm went bankrupt during construction, around the end of 2002, all three of those contracts were eventually assumed by Shaw Environmental of Baton Rouge.
Canal expansion included both widening and deepening, and required blasting to get through the roughly 3 ft. to 12 ft. of limestone "cap rock" located in this area of the project.
A roughly $4 million U.S. 27 bridge contract was awarded to Aztec Construction, a relatively small contractor based in South Florida. The $22 million pumping-station contract was originally awarded to Beers Construction, which eventually became Atlantic Skanska.
Miller said the STA 3/4 project was originally scoped, budgeted and scheduled in 1993. Work was completed in April, within three months of the original schedule and 10 percent below the original budget.
Final Results A statement from SFWMD officials Frank R. Finch, executive director, and Joseph A. Schweigart, director of the ECP, said the $700 million ECP "sets the cornerstone for the largest ecosystem restoration program in the history of Florida" and the STAs "are the key components of the project."
They added: "These constructed wetlands use biological processes to reduce the level of phosphorous entering the Everglades. This effort has been recognized as the best approach for achieving interim water quality goals."
Miller said the project is a major step toward protecting and restoring a unique ecosystem.
"The fact that it was completed, that it is a cornerstone for the overall ECP and is a building block for the federal Comprehensive Everglades Restoration plan really elevates its importance to the restoration of the Everglades," he added.
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