Billions of dollars are spent annually to clear ports and shipping channels of sediment using a variety of dredging vessels.
The Port of Cleveland said 250,000 cubic yards of sediment must be dredged each year from the Cuyahoga River to make it deep enough for large commercial ships — enough material to fill a major league ballpark like Progressive Field where the Cleveland Indians play — to a depth of about 30 feet.
A breakthrough device called a bed load interceptor, invented by Randall Tucker of Streamside Technology, is expected to reduce the amount of material that has to be removed from the Cuyahoga with conventional dredgers by about 20 percent.
And the material the interceptor removes can be done at a vastly reduced cost, according to the port citing $2 per cubic yard compared to $17 per cubic yard today.
One of the reasons for the high cost of dredging today, the port explained, is “traditionally, all of that sediment had to be placed in contained disposal facilities (CDFs) due to concerns about sections of the river still compromised by contamination.”
But it said the new interceptor “is installed in Independence, five miles upstream of the shipping channel, and collects sediment before it can encounter downstream contamination. Thus, the material is clean enough to be sold for a number of market uses, including structural fill, custom soil blends, and restoration of stream banks.”
A company called Kurz Bros. will use the material collected by the interceptor in soil blends and structural fill.
The bed load interceptor is a wing-shaped device that extends partly across the width of the river.
Sand and sediment that tumbles along the bottom of the river—so-called “bed load” (as opposed to sediment suspended in the water)—makes up about 45 percent of the total sediment in the river. After the bed load sediments move up a ramp, they fall into a hopper, and then are pumped ashore. A screw auger removes the sand, and the water is recycled.
The device’s location was strategically chosen in part to take best advantage of the natural flow of the Cuyahoga, using the river’s energy in a faster moving section (4.5 miles per hour vs. only 0.25 in the shipping channel) and also because Kurz has operations adjacent to the river.
Of course, the flow of the river varies throughout the year, and the Streamside system adjusts itself, even turning off during dry weather when there is little water.
The system was funded largely by a $1.2 million grant from the Ohio Healthy Lake Erie Fund.
The interceptor has been deployed on some other streams, including Fountain Creek which originates near Pikes Peak in Colorado and flows into the Arkansas River. The device helps reduce the amount of dredging on the Arkansas River.
Brian Halm, operations manager at Streamside, said the company is working with Kurz on possible use of the technology at other locations in Ohio and the Great Lakes.
The Army Corps of Engineers is looking at its possible use to reduce sediment from various tributaries on the Mississippi River.
The device could also be potentially used for wetland restoration, beach replenishment and in reservoirs where silting can reduce capacity.
This column was published in the September 2015 issue of American Shipper.
