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Hogan seeks proposals to remove, reuse Conowingo sediment

Conowingo Dam (File)

Conowingo Dam (File)

Gov. Larry Hogan Tuesday said the state will move forward with plans to find a solution to sediment that has built up behind the Conowingo dam and is polluting the Chesapeake Bay.

Hogan, in an announcement at the dam following a summit and tour of the facility, said the Maryland Environmental Service will issue a request for demonstration projects that offer options to dredge and potentially reuse the sediment in other ways.

“This project will allow us to get additional information, such as what markets are available for the material, and we will gain information on the companies that are available to beneficially reuse dredge material,” Hogan said. “This demonstration project will allow us to determine the cost for dredging, to compare the costs of upstream best management practices and to demonstrate that dredging and beneficial reuse are feasible options.

Hogan said the request for proposals will go out by the end of this month. Officials hope to award a contract by the end of the fall.

Hogan, who campaigned in 2014 on reducing pollution caused by the dam, made his announcement following a meeting of the Conowingo Dam Workgroup at the facility.

Hogan said decades of nutrient-laden sediment buildup that is harmful to the bay is driving the need to dredge.

“The Conowingo Dam has reached capacity and is no longer able to trap sediment which, if allowed to flow downstream, could increase pollution and negatively impact the bay,” Hogan said.

A 2015 study by the United State Geological Survey estimated that the dam was at 92 percent of its nearly 200 million pounds of sediment retention capacity. A similar study just three years earlier noted that the dam was already allowing phosphorous and nitrogen to pass downstream into the bay.

The nutrients cause algae blooms and dead zones in the bay.

“The responses to the RFI produced promising solutions that warrant further exploration,” Hogan said.

Alison Prost, Maryland Executive Director of the Chesapeake Bay Foundation, said Hogan’s plan is just one part of a solution to a larger problem.

“While dredging could be a part of the solution, results of the Army Corps of Engineers-led study indicated that the most cost-effective approach to reducing pollution coming across the dam is to implement practices that will reduce pollution upstream,” said Prost. “The dam is currently seeking a new license. Governor Hogan should require Exelon, which owns and profits from the dam, to contribute a portion of its profits to help reduce pollution coming down the Susquehanna River.”

Last month, about a dozen companies responded to the state’s call for information on how to dredge behind the dam and potentially reuse the material in other ways.

Those ideas included dumping the dredge spoils in the ocean, reusing the material for counter tops and pavers, and using microbes to eat the silt, thus reducing the amount of sediment that has to be removed, according to a report last month by The Baltimore Sun.

The hydroelectric dam, completed in 1928, sits on the Susquehanna River approximately 10 miles from where it joins the Chesapeake Bay.

The river, the longest on the East Coast, is the bay’s largest tributary and provides about half the fresh water to the estuary.

It’s also responsible for about half of the nitrogen pollution that flows into the bay.

Much of that pollution, however, comes from other states as the Susquehanna flows 464 miles through New York and Pennsylvania.

“This is not just a Maryland problem,” Hogan said.

The Associated Press contributed to this report.

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