Getting Tough on Turbidity

Oct. 24, 2014

Meeting federal antipollution requirements to ensure clean water has become a routine part of erosion control work. For projects that take place around waterways, that often means the use of turbidity curtains or coffer dams.

In business since 2005, Tampa Bay Marine in Riverview, FL, specializes in the installation and repair of commercial and residential structures in or near water. Docks, boat ramps, boat lifts, retaining walls, and sea walls are among the company’s most common projects.

For turbidity barriers to use on jobs, Tampa Bay Marine relies on Aer-Flo’s Tough Guy curtains. These curtains are manufactured by Aer-Flo of Oneco, FL, and distributed by erosion control products suppliers nationwide, including R.H. Moore and Associates of Tampa, FL.

“They’re the only brand we sell,” says Larry Larson of R.H. Moore and Associates.

Aer-Flo manufactures its Tough Guy turbidity curtains in stand lengths of 50 feet and standard depths of 3, 5, and 10 feet. Custom curtains can be made that are up to 100 feet in length and range in depth from 2 to 100 feet.

“We use them on just about every project we do,” says J.J. Smiarowski, operations supervisor at Tampa Bay Marine. “They’re economical, and on any marine job we have to have turbidity barriers.”

One such project was the installation of a new boat ramp for the city of St. Petersburg, FL. The ramp measured about 80 by 15 feet and the installation work required 600 feet of boom, or turbidity curtain.

Work on the project was done in March and April 2014. The curtains used were in a standard 5-foot by 50-foot size.

Tampa Bay Marine’s crew of five installed the new boat ramp over water that was 7 to 8 feet deep.

Because the project was done in the spring, weather was not a factor. Smiarowski says that during summer, heavy rain and thunderstorms frequently reduce suitable work hours, sometimes by as much as half.

At the end of the ramp, a Presto Geoweb cellular confinement system was installed and filled with rock. This erosion control and soil stabilization product provided a solid foundation from which to launch boats from boat trailers. Using this strategy saved pouring concrete.

Another Tampa Bay Marine job was the installation of ship berth 151 for the Tampa Port Authority. The Port of Tampa is Florida’s largest in terms of both cargo tonnage and acreage. It handles cruise ships-with more than one million passengers a year-as well as cargo ships.

The turbidity curtains used for the Tampa Port Authority job had to be of a custom size. They were 28 feet height. The job required 2,500 feet of curtains or boom. Water depth at the site was 35 feet.

Work on the berth 151 project took about three months to complete, lasting from January to April 2014. The weather caused no problems. The current, however, is very strong in the area, so foundation piles were installed to anchor the ship berth.

“We put in 55-foot-high piles, clustered in a dolphin,” Smiarowski explains. “The piles were bolted and welded together.”

Installing Pipeline
Ceco Pipeline was hired to install a new pipeline on the edge of Arcadia Lake in Edmond, OK. Ceco’s client was Southern Star Central Gas Pipeline Company. The job took about six weeks, from the beginning of April to mid-May of last year.

“The Army Corps of Engineers said the job couldn’t be done, but we did it,” says Grant Scott of Ceco.

The new pipeline was installed 8 feet below ground. The working area was about 200 feet by 80 feet; water depth ranged from 3 to 4 feet. Neither weather nor steepness of the surrounding land posed any problems.

“It took two days to go from wet to dry [so the digging could begin],” says J. J. Johnson, project manager for Ceco.

To remove the lake water from the work site, Ceco’s crew used coffer dams made by Dam-It Dams of Grand Blanc, MI. This company has been involved with dams and solving water problems for various types of construction work since 1928. In fact, the first person to go safely over Niagara Falls used an inflatable device created by Keith Nichols, father of Jack Nichols, the founder of Dam-It Dams. Jack Nichols started Dam-It Dams in 2001 to provide his patented, environmentally friendly portable coffer dams for various types of projects that require water to be kept out of a site temporarily.

The portable coffer dams are made of a heavy-duty woven polypropylene outer casing. This outer casting contains two side-by-side inner tubes, which act as stabilizers to keep the coffer dam from rolling due to outside water pressure and other forces.

Dam-It Dams come in eight different heights: 1, 2, 3, 4, 6, 8, 10, and 12 feet. To work properly, the dam should be at least 25% higher than the depth of surrounding water.

Johnson says the biggest challenge on the project was “keeping the lake water pumped out. We were working below the water table. We had to put a trench box around the pipe because the soil caves in and water seeps back [up from below].”

Although Ceco has used Dam-It Dams on other projects, this job was Johnson’s first direct experience with them. Asked if the Dam-It Dams performed as expected, Johnson says, “Absolutely. It’s an excellent product. It’s a lot more secure than an earthen dam.” He adds, “It’s environmentally friendly. You don’t leave any footprint after you’re finished.”

Compared to using the Dam-It Dam, he notes, “An earthen dam takes longer. You’re at the mercy of the dirt contractor and when he can deliver the dirt.”

He notes, “Percentage-wise, you probably get a 60% to 70% savings in dollars and many hours of labor. And that’s including the cost of the coffer dam.”

The silt fence installed around the entire project delivered additional erosion control protection. “It’s standard practice,” Johnson explains.

Removing Sediment
General contractor JND Thomas of Riverdale, CA, and Daytona Beach, FL, completed an interesting dewatering and dredging project in Wilde Lake, located in Columbia, MD. The contractor was responsible for safe disposal of the 15,000 cubic yards of sediment that crew members had removed.

The engineering firm Anchor QEA of Columbia, MD, did the engineering and design part of the project. Walter Dinicola, P.E., of Anchor’s Columbia office was onsite.

The 22-acre manmade Wilde Lake was created on a grassy meadow that had a small stream. Residential properties and open recreational space surround the lake.

The $1.7 million project was funded by the Columbia Association, the private, nonprofit service association responsible for the upkeep of the Columbia community. Work on the Wilde Lake project lasted from May to July 2012.

Wilde Lake is fed by a tributary to its north. A 15-foot-high concrete dam stands at the lake’s outfall channel. About 1,200 acres, primarily residential, drain into Wilde Lake. It flows through another manmade lake, Lake Kittamaqundi, and eventually into the Little Patuxent River.

Dinicola says one challenge of working on this project was “working in close proximity to residences.” The homes surrounding Wilde Lake have residents who naturally would be concerned about noise and damage to their community caused by machinery and workers. The Columbia Association kept residents informed about the various stages of the project and what they could expect in the near future.

Working in the residential community meant extra planning by the design and contracting teams on such matters as how and where to deploy dredging and dewatering equipment. The site deemed best for the dewatering plant because it would not be so obvious to residents turned out to have an active spring flowing beneath it. The crew had to take the extra step of installing underdrains before moving in equipment.

Fortunately, the lake is shallow, ranging from 7 to 13 feet, though it’s deeper near the dam. The dredging crew of JND Thomas could use a Moray dredging machine that requires only 4 feet of water depth. The Moray is moved by spuds instead of cables, which makes it easy to use in tight areas.

“Wilde Lake had been dredged before, in the early ’90s,” says Dinicola. “It was completely drained, and they built roads inside the lake. We never had access to the location where the roads are, and so as our dredge encountered some of the roads, we had to adjust the dredging as it was being done.”

At the mouth of Wilde Lake, the dredge “worked its way from deep water into a shallow 6 inches of water,” Dinicola says, adding that the dredge’s ladder extends out 40 to 50 feet and the dredging itself keeps the water deep enough for the machine to operate.

Other challenges, Dinicola says, included “meeting a restrictive schedule and some geotechnical issues. We had to be out by July because sailing classes were scheduled.”

Walking paths around Wilde Lake and Lake Elkhorn (another Columbia Association developed and owned lake that was dredged after the work on Wilde Lake was finished) were still accessible to residents.

“We built bridges over pipes and installed fences for safety,” Dinicola says. To lower noise levels, “we put hospital-grade mufflers on the equipment. We monitored for noise quality and water quality.”

Another accommodation to the nearby residents was reduced operating hours. That meant that both projects took longer than normal to finish.

The turbidity curtain was installed 150 feet in front of the outfall dam where the lake is deeper. The SiltMax type 1 curtain, 20 feet in length, came from Elastec/American Marine. The company has manufacturing and warehouse facilities in southern Illinois.

SiltMax turbidity curtains meet federal and state department of transportation standards of types 1, 2, and 3 for installation in calm waters or those with currents. Standard sizes are 50 and 100 feet, with various lengths. Custom sizes can be manufactured.

“There were minimal currents within the lake,” explains Dinicola. “The lake water surface is controlled by the dam structure.”

The JND Thomas dredging crew also installed Elastec/American Marine’s SiltMax turbidity curtains in Lake Elkhorn. With its headquarters in Carmi, Illinois, Elastec/American Marine specializes in pollution containment and recovery products.

Of the company’s durable turbidity curtains, Dinicola says, “We’ve been on projects where they were used before.”

Dredging on Lake Elkhorn began after the work on Wilde Lake was completed. This second project ran from July 2012 to January 2013.

The dredging project on Lake Elkhorn was more complicated. “It lasted considerably longer,” Dinicola says. “We had weather delays because of Superstorm Sandy and Hurricane Irene.”

He adds that “a lot more vegetation” presented another challenge to the project. It was met by using an aqua mower to harvest the underwater vegetation prior to dredging and the cutter on the hydraulic dredger that, as it was submerged in the lakebed, also cut vegetation.

At Lake Elkhorn the dredge operated for two weeks in an isolated cove area. The turbidity curtain needed for this section of the project was about 100 feet long. At the top of the lake the crew installed about 350 feet of curtain.

With the shallow water depth of 10 feet, the curtain “sat in the water at 8 feet, 2 feet above the lake bed. We like to leave that space so the curtain doesn’t pick up debris, so it won’t scrape the bottom as it is moved by the wind,” explains Dinicola.

Dinicola says that the goal for dredging both Wilde Lake and Lake Elkhorn was not for navigation, but for increasing irrigation capacity and returning to the original design of the two manmade lakes.

Bass Lake
Tidal Marine Construction in Concord, CA, is a professional commercial diving company. Project managers Shawn Stambaugh and Steve Ackart lead crews that perform underwater jobs, including welding and maintenance of dams, ships, trash racks, and outfalls.

One of their most interesting projects was the seismic retrofit of the Crane Valley Dam in Bass Lake, CA. Bass Lake is the reservoir formed by the dam.

Owned by Pacific Gas and Electric, the Crane Valley Dam supplies hydroelectric power for the utility’s customers. The dam was built in phases from 1902 to 1911. Before the retrofit, it was 145 feet high and 1,880 feet in length.

The entire retrofitting project cost $125 million. The dam was reinforced to better withstand earthquakes. Its crest was raised 7 feet.

Trees had to be cut to establish an 8-acre rock quarry on adjoining land, a half mile downstream, to supply rock for the project. After the project was finished, new trees were planted so that the forested area was restored to its original appearance.

The area’s rugged terrain and winter snow made for challenging working conditions. The California Department of Fish and Game had strict turbidity restrictions for the reservoir and requirements for placement of the dredging equipment and rocks.

Tidal Marine Construction’s part of the project began with installing turbidity curtains in December 2012. The company maintained these curtains during all of 2013 and removed them in January 2014.

Stambaugh and Ackart installed Siltmaster type 2 turbidity curtains manufactured by Parker Systems of Chesapeake, VA. In business since 1970, Parker Systems supplies environmental products and systems for cleaning and protecting oceans and other waterways.

Protecting Bass Lake required 6,000 linear feet of the Siltmaster turbidity curtains. The custom-sized curtains tapered out from one beach side to 90 feet in length and then gradually back to zero on the other side of the lake.

Specifications called for the 3,000 linear feet of curtain to be installed in two parallel lines, 6 feet apart. Stambaugh says that this was because the engineers were concerned that with the water level fluctuating, one line of curtains would balloon out, allowing sediment to pass through.

With two lines of curtain, “the first layer would catch some of the dirt and the second would catch the rest,” he adds.

The curtains had to be installed in a serpentine design so they would go around structures and land and the dredging barge’s dumping area. They were placed in 50-foot-long sections.

Stambaugh notes, “The water elevation changed throughout the year, so the bottom of the curtain came up.” Readjusting the curtain required going out in a boat and pulling up lines that were placed every 6 feet.

He says that getting the curtain installed was challenging. “There was an intake tower at one point and that’s why we used the serpentine design. To maintain that separation [from the intake tower] during changes in the water depth wasn’t easy.”

He adds, “If too much curtain was in the water, it could be sucked into the intake tower, but the curtain had to be at a certain distance so the barges could get into place.”

In a letter complimenting the Tidal Marine Construction crew for its work on the Crane Valley Dam project, John Parker of Parker Systems wrote, “Turbidity curtain this size is not easy to manufacture or even handle. I must admit it is not easy to properly install these deep curtains!”

Protecting Iowa Rivers
Ed Miner, general manager at GreenTech of Iowa, is a fan of Tough Guy turbidity curtains by Aer-Flo. “We have them on 20 jobs right now,” Miner says.

One job on which GreenTech used them was for the Iowa Department of Transportation. The widening of Interstate 35 involved work on the bridge that carries I-35 over the North River, south of Des Moines. Work on the bridge section of the project took place during the spring and summer of 2013. The work area covered about 15 acres.

“We used Tough Guy type II. One hundred and thirty-five feet were called for, but we ended up using 400 feet,” Miner says. “Several times we had to take out the curtains and repair them or put new ones in.”

That’s because of sudden flash floods that occurred during the spring rain season. The water in the area was only 3 feet deep, but the frequent heavy rains caused it to swell to 15 feet. When the water receded, the turbidity curtains were left on the bank, sometimes battered and damaged.

The turbidity curtains were installed “so that sediment would settle out before the water reached the main river,” says Miner.

He adds, “Last year was the first year we started doing this type of work. We had some problems getting the curtains anchored. But once the anchors were in good, you didn’t have much trouble.”

Other erosion control best management practices used on the project included straw wattles and logs and an Iowa DOT silt fence. The land was seeded with Iowa DOT rural seed mix.

Another GreenTech project done for the state DOT took place near Sioux City, along Interstate 29. Bacon Creek flows into the Missouri River there. Miner says 400 feet of type 2 Tough Guy 3-foot turbidity curtain was installed to keep sediment out of the river. Water from the city of Sioux City drains into Bacon Creek.
About the Author

Margaret Buranen

Margaret Buranen writes on the environment and business.