Dean Wickoren ENVIROTUBE Technical Director Industrial Fabrics, Inc. dean@envirotubes.com 913-221-5345 (mobile) Resume and Accomplishments (over 40 years experience) Frequently Asked Questions

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Case Studies

North Star Marina is a medium-sized marina located in Elberta, Michigan. Situated on Betsie Bay, the marina connects to the Great Lakes via the Betsie River. For several years, the bay area had been plagued with problems associated with the Great Lakes dropping water levels and increased sediment loads.

The Problem

In June of 2000, the water level was down three feet in the bay. North Star Marina was dealing with this low water level and an accumulation of 3,400 cubic yards of mud and sediment - preventing boats from getting in or out of the marina. When the owners couldn't get a permit to finish their dredging project, they had to find an alternate solution fast. Typical solutions would have been constructing an on site upland containment area or pumping the dredged material over a long distance. Complicating the case, a neighboring marina had just been shut down by the Michigan Department of Environmental Quality (DEQ) for 10 days, due to excess sediment-laden runoff entering the bay from its containment cell.

When North Star Marina proposed a containment cell for its dredging applications, the regulatory agency was apprehensive. The proposed site was a small paved parking lot having dimensions of about 40 ft. X 100 ft. This site was rejected for a variety of reasons including: close proximity to the water, gas tanks located under the pavement and the potential of having to repave the whole site. "We couldn't find a place to put a settling pond", said North Star Marina owner Bob Danek. "We couldn't even find a place close by to pump to. We couldn't even find a trucker to haul the stuff off."

The Solution

Matt Hagernauer of CSI/Geoturf, presented Propex® Geotex® 4x6 geotextile ENVIROTUBES as a quick and cost-effective containment solution in a relatively small area. ENVIROTUBES are an ideal solution for dredged material management. They greatly reduce dewatering time and disposal costs, and provide opportunities for the beneficial reuse of dredged material. Dewatering operations are cleaner because geotextile tubes dewater dredged material faster and retain fine-grained solids better than when the material is placed in lagoons or detention basins. Once the dewatering process is completed, usually only a matter of days, the dredged material has reduced weight and volume and is more cost-effectively transported to a permanent disposal site.

Permission was granted to let North Star use the old railroad right-of-way that ran along the road in front of the marina for the tube placement. This was ideal because it was relatively level and had drainage back to the bay. The ballast and gravel used on the railroad grades is an ideal drainage medium, the base is firm and non-erodable, and a plastic underlayment sheet was not needed. Two 200 ft. long by 45 ft. wide Propex® Geotex® 4x6 ENVIROTUBES and one 100 ft. long by 45 ft. diameter ENVIROTUBE were rolled out and the drains underneath were established.

The marina sediment contained saw mill waste that included some large slab wood and boards. The dredging operation chewed up some of this material and pumped it into the tube, but the rest had to be picked out of the pump by hand. Because of the wood, the contractor decided to do the job with a hard pan cutter on the dredge instead of the soft material option. This caused a great deal of water to be pumped in with the mud. Dean Wickoren, a consultant and manufacturer of dredging equipment, recommended chemical conditioning of the dredged material to aid in the dewatering process. A 10 inch HDPE (high density polyethylene) pipeline was installed to receive the polyamine cationic coagulant polymer injection.

The Results

"Everyone was very pleased," said Hagenauer. "We introduced this system to the area and the State of Michigan. The DEQ group that came and inspected our tube operation remarked: 'It's nice for a change to show up at a job site and be pleasantly surprised.'" The ENVIROTUBES proved to be cost-effective and saved the marina owners the potential problems associated with the alternative of a containment area. The addition of the polymer made the solids flock together in the tube, accelerating the release of water through the fabrics, allowing for faster dewatering. This also helped produce cleaner run-off. (Run-off from ENVIROTUBES is normally less than 30 ppm suspended solids, resulting in better water quality.) The tubes were cut open and the material was hauled off 11 days after the dredging was finished. The material was the texture of soft clay. The area where the tubes were placed was not disturbed and the grass was greener than it had been prior. The DEQ was very impressed with the cleanliness of the effluent.

The Conclusion

ENVIROTUBES successfully and quickly solved the marina's problem, where traditional methods were not possible. "This was the only way we could have done it," said Danek. "And we did not create any mess at all." The tubes allowed 3,400 cubic yards of sludge to be pumped and contained in a small area - saving time and money. The tubes, with the aid of the polymer injections, were so successful in dewatering the sludge that there was a 66 percent shrinkage factor, resulting in only 1,100 CY of material being hauled off. From the start of dredging, the marina was able to return to normal operations in just two weeks.

Great Lakes Marina Case Study (PDF)