In-Stream Sediment Collector under Evaluation by Streamside Technology and COE
Randall Tucker at the Dredging 2015 technical session.
Photo by Judith Powers.
Streamside Technology, LLC has introduced and is testing the Bedload Collector – a passive structure that traps coarse-grained sediment, removing it from the bedload of a river, stream or ocean current.
The Collector works using simple physical principles. As the current travels up the ramp leading to a grate, the coarse-grained sediment drops through the grate into the hopper, while the finer-grained sediment and other organic matter remain in suspension and pass over the collector. As the hopper fills, the sediment is pumped to either a disposal site or to a dewatering site for beneficial use of the harvested sediment.
In early 2011, Streamside installed a Collector in Fountain Creek near Pueblo, Colorado, working with Colorado State University, the Arkansas River Watershed, and the city of Pueblo. The technology had been tested and third-party validated by Colorado State University at Fort Collins prior to the Fountain Creek project.
The Cuyahoga River installation in progress, with the ramp on the upstream side visible. The Collector was installed about 10 feet below the water surface on the river bottom
The 30-foot-long, high capacity Collector was intended to reduce sediment deposition and lower the downstream grade in order to reduce flooding. Sand from the hopper is pumped through a six-inch discharge pipeline by a 50 hp internal pump approximately 600 feet to a spiral classifier for dewatering, and then dropped onto a radial stacking conveyor for stockpiling. The maximum production rate achieved during a high flow event to date was approximately 100 cubic yards per hour.
Tim Welp, team leader of the US Army Corps of Engineers (USACE) Dredging Operations Environmental Research (DOER) program, Dredged Material Management Focus Area, visited the Fountain Creek site to observe the Bedload Collector technology in operation, and explained that the objective was to evaluate the Bedload Collector’s potential to maintain channel depth by reducing rates of channel in-filling.
The Cuyahoga River Bedload Collector prior to installation, showing the downstream side, and holes for suction and return water.
“Then, under the USACE Navigation Systems Research Program, we did a preliminary investigation on the Mackinaw River with the Rock Island District with a four-foot-long Collector to further demo the technology and calculate potential production rate estimates of a larger Collector system. While the initial results of these investigations are promising, we are still interested in learning more about its operation, as well as other innovative operational systems, to more fully evaluate their potential use to reduce rates of channel infilling. An attractive aspect of the Bedload Collector, is that is applies Engineering with Nature (EWN) by letting nature move sediment to the collector, instead of having to move a dredge into the sediment. ” Welp said.
A four-foot collector was also deployed for a limited time in the surf zone at the Engineer Research and Development Centers (ERDC) Field Research Facility in Duck North Carolina to gain insight on potential coastal applications.
On the Kurtz Bros. site, the processing installation is about 200 feet from the Collector. Slurry is delivered by a pump in a nearby well pit into the dewatering screw. Overflow water is delivered back to the Collector. The system produces clean sand with 10 to 20 percent moisture content.
PAPER PRESENTED AT DREDGING 2015
Welp presented a technical paper on the Bedload Collector and his group’s analysis at Dredging 2015.
He listed lessons learned and summarized investigations of this technology into other possible applications, along with general guidance for applying collector technology at other sites. Additional information on the Fountain Creek investigation is available at the Dredging Operations Technical Support (DOTS) website http://el.erdc.usace.army.mil/dots/doer/pubs. cfm?Topic=TechNote&Code=doer.
Randall Tucker, CEO of Streamside and developer of the Bedload Collector also attended the conference and was available to talk to attendees.
The collected material discharging onto stockpiles at Kurtz Bros., ready for sale or use.
He said the design of the Bedload Collector for coastal applications would involve the use of a slightly modified version of the standard installation. It has two ramps of equal length to accommodate a bi-directional flow, where the standard design has only one ramp, upstream direction of flow. A pumping station would be placed onshore, and in a beach replenishment project, the discharge would be pumped onto the beach and broadcast using a traveling sprayer. The engineering allows for purging of the hoppers with the addition of a screen waterjetting system to reduce clogging.
All designs and patents are held solely by Streamside
Another ongoing test is on the Cuyahoga River near Independence, Ohio, led by the Cleveland-Cuyahoga County Port Authority and Streamside, with funding from the state of Ohio. Kurtz Bros., Inc., a material management company in Independence, is operating the system on its property and managing the harvested material, rounding out collaborations of a successful P3 (Public/Private Partnership), Brian Halm, operations manager of Streamside, said.
“The purpose of the location … on the Cuyahoga River is to intercept the sediment far enough upstream of the river where contributing tributaries affect the river,” he said. “This would allow the Bedload Collector to capture sediment at its natural transport rate before it migrates to the main shipping channel, and over time possibly reduce the overall amount needing to be dredged, or to delay dredging to conserve budget. This is a model we are pushing to different ports and marinas to keep sediment from entering the main channels.
The internal pump in the Fountain Creek Collector delivers the slurry to this processing plant 600 feet away. Overflow water is returned to the Collector.
“Testing and evaluation of the system during different flow stages is being conducted, and more information on the performance of the system will be released late spring/summer 2016. The system can run automatically, based on river height and flow as it is calibrated to the USGS gauging station upstream of the collector system,” Halm said.
KUTZ RETAINS OWNERSHIP OF PRODUCT
Kurtz Bros., Inc. is in charge of the operating and monitoring of the Bedload Collector with assistance from Streamside as needed. It is retaining ownership of the sand removed with the Bedload Collector, and has a partnership with the Port Authority to offset operating costs and other costs of handling.
The Collector is 10 to 12 feet below the water surface on the bottom of the Cuyahoga River. Slurry is pulled from the hoppers by a submersible dredge pump, placed in a well on the bank and discharged through HDPE pipe to the feed box on top of the screw auger, about 200 feet from the Collector. The slurry drops onto the auger, and sediment works its way up the auger and discharges at a 10 to20 percent moisture content onto a stacker to be piled for beneficial reuse. In the screw auger, oversized overflow weirs allow the fine material to settle longer in the screw to retain as much material as possible. Water from the screw auger then overflows into a tank behind the auger, where level sensors allow the water to be pumped back into the sediment collector for refluidizing sediment and purging the system, and not directly back to the river.
“We have built Bedload Collectors in sizes from four feet up to 30 feet, and have designs for up to 200 feet,” Halm said. “The bi-directional Collector is similar to our standard Bedload Collector with a modification to the downstream ramp length, and as with the standard system we have designs for the bi-directional in sizes up to 200 feet,” he said.
Cranes prepare to lift the Fountain Creek Collector into place at the designed grade in the foreground. The view is of the downstream side of the 30-foot-long Collector. A 50 hp pump is installed in the raised section, next to the discharge (with blue cover). Slurry is delivered to a processing plant 600 feet away. The hole to the left of the discharge is the return water pipe.
He explained that the various Bedload Collectors are designed and developed by Streamside. Engineering companies and contractors are used during the engineering and construction phase to determine project specific information for installation. There are various options for the discharge of the removed material, which can be designed to accommodate pumping the material extended distances using booster pumps.
Streamside Technology, LLC has been in business since 2002, and develops and patents environmentally friendly technologies to address excess sedimentation in lakes and rivers. Besides the Bedload Collector, Streamside has developed a Sand Wand™ to selectively remove fine sediments from the surface and subsurface of gravel and cobble streams; and an aeration system that dramatically increases dissolved oxygen and circulation in lakes. The products are licensed to the company’s subsidiaries Streamside Environmental and Streamside Manufacturing.