"Un-dredging" makes Florida's Kissimmee River ecologically correct

One of the biggest environmental events of our time is beginning in a vast region of Florida - from the central Kissimmee River Basin to the Everglades farther south. Remedial efforts under way aren't conventional projects that apply the newest ecological science to preserve current conditions. Quite the opposite in this case, they comprise an enormous undertaking to restore the wetlands as they were 100 years ago. For a new millennium.

Ellicott Series 370HP "DRAGON" Dredge in Naples, Florida

For 10 weeks an Ellicott International 370 Model HP cutterhead "Dragon" dredge was in the middle of an initial project in the Kissimmee basin filling in an existing canal. Obviously, this wasn't a traditional dredging task to deepen or straighten a channel. Its purpose was to help return the area to its original state as a broad water pathway with curves, bends and side slopes.

Not only was the dredge "un-dredging" a man-made channel, but it was digging new adjacent waterways crooked, by design.

It's the Kissimmee River Backfill Project designed by the U.S. Army Corps of Engineers for recreating natural water flow through the original waterway "oxbows" that meander through an area.

"Basically," explains Hank Yuan, site engineer with IT Corp., the primary contractor for the first Kissimmee work underway, "the dredging project lets the water flood and restore the area back into a wetland." IT Corp., headquartered in Pittsburgh, is a major full-service environmental contractor.

The Kissimmee River basin comprises some 3,000 square miles stretching from below Orlando southward to Lake Okeechobee. The Kissimmee isn't really a "river" now, engineers say, but a canal built in the 1950's. Work then altered the natural characteristics of the river and shortened its run from 103 miles (166 km) to 56 miles (90 km), while adding various water control structures and locks. Corrective measures, sought since the 1970's and finally set into motion in the early 1990's, would retain flood protection objectives while regaining the environmental benefits of the basin's natural floodplain - through both headwater revitalization and restoration in the river's lower sub-basin.

Current work by the IT Corp., under a $10.7 million contract, covers 8 miles (13 km) in this lower basin. Called the Reach 1 Backfill project, it includes backfilling the canal, new channel excavation, navigation aides for the restored river channel, constructing a downstream water control "plug", and removal of tieback levees and existing structures. Contracts for work on other sectors are still to be awarded.

Waterborne phase

The Ellicott Series 370HP "Dragon" dredge, 72 feet (22 m) long by 12 feet (3.7 m) wide, was integral to the waterborne phase of the Kissimmee project performed in a half-mile-long oxbows sector by Ludlum Construction Inc. (Stuart, FL), subcontractor to IT Corp.

Operating generally in the center of the 130-foot (40 m) wide waterway, the Ellicott "Dragon" dredged out soil and silt from two oxbows' channels, dumping the soil into the old canal as part of the backfill material. Dredging to 12 feet (3.7 m) deep was easily within the "Dragon's" 20 foot (6 m) depth capability.

Ellicott's dredge worked in tandem with a barge-mounted long-reach backhoe excavator which cleared trees, roots, other vegetation and debris at or near the surface, enabling the dredge to perform its underwater tasks.

As the "Dragon's" cutter head moved back and forth, it made "box cuts" - vertical sidewall excavations, in the subsurface soil. At times the backhoe barge followed Ellicott's "Dragon" and pushed the sidecuts, helping the sandy material slush down deep to create the desired "natural" slope.

Included in Ludlum's small "fleet" was a tugboat that served the two non-self propelled vessels. Pushed into their work locations, the Ellicott dredge and barge dropped their spuds to anchor at their task positions. The tug also was used to move the barge to the water's banks where accumulated trees and other debris were dumped ashore for burning and removal.

This Ludlum Construction phase, along some 2,554 feet (778 m) of the Kissimmee, was part of the first section of work by IT Corp., according to Hank Yuan. The project area lies well south of Orlando and Lake Kissimmee, with the IT project area based at Lorida, a small town east of Sebring. From there the crews need to travel about 45 minutes to the canal site, basically a swamp full of alligators and rattlesnakes.

The essential waterborne work interfaced with the IT Corp.'s land-based activity along the Kissimmee river/canal. Yuan reports that IT's own 40-member crew is dumping a total of 11 million yds³ of backfill material into the Kissimmee canal. The sandy loam fill is moved into place by trucks, then pushed into the canal by a host of bulldozers. That total of backfill material compares with the 61,000 yds³ moved during the waterborne phase between early July and mid-September.

IT Corp. officially started this Kissimmee project in late April 1999. The work is scheduled for completion by October 2000.

Site needs and dependability

Terrain characteristics prompted Ludlum's decision to use the Ellicott 370 dredge for this project. It marked their second project in succession this year with the very same dredge.

"We had such good luck with an older model Ellicott 370 in a City of Melbourne environmental project a couple of years ago," says Ludlum president Jim Schwarz, "so when we got the project in Naples, we decided to lease another 370."

"Often our jobs have a tight time limit, and we cannot risk delays from equipment downtime," notes Schwarz. Therefore, along with equipment specifications, Schwarz said the company put faith in Ellicott's reputation for thoroughly checking leased equipment before it goes out.

The Melbourne contract entailed cleaning thick black sediment from the mouth of Crane Creek, a freshwater body that empties into the Indian River Lagoon, and Ludlum finished on time - in fact, four days early.

Ellicott Series 370HP Pumping Sand out of Clam Pass

The early 1999 project for Naples - pumping sand out of Clam Pass for Clam Bay restoration - posed a similarly short, environmentally dictated work window. At the time Ludlum completed the Clam Pass job, again early, it was negotiating to do the Kissimmee subcontract work. "So", says Schwarz, "we decided to keep the dredge available." Ludlum soon was tapped by IT Corp. and the "Dragon" went into the Kissimmee job "where it worked out well," adds Schwarz.

A key selection factor was the model's size and configuration, according to Schwarz, noting particularly that "it's a handy little dredge and easy to move." This was important, notes Schwarz, "because the project we were on was not easy to get to, in the "Everglades."

Also, he says that the dredge's thoroughly tested operating condition proved out "in very little downtime, just normal maintenance."

"It's a good, simple, economical dredge to run, "Schwarz adds. "My guys love it."

In any event, as the Kissimmee job reached completion, the same dredge was off to Puerto Rico with a Ludlum crew for another Corps of Engineer project, reported Schwarz.

Source - Ellicott 's Mud Cat in Action publication