Maryland selects companies for dredging test project at Conowingo Dam

Maryland has selected a pair of companies to dredge a small amount of the sediment that’s built up in the Susquehanna River behind the Conowingo Dam as part of a pilot program officials hope could lead to a larger solution.

At an August press conference along the banks of the Susquehanna, Gov. Larry Hogan announced the state’s intention to tackle the problem of built-up sediment behind the dam.

The test project, to be conducted by Northgate-Dutra Joint Venture, will help officials decide whether large-scale dredging is a good idea. But officials said Friday they could not offer specific details of the pilot project — including its cost, scope or schedule — because the contract has not been finalized.

The dam stretching across the river between Harford and Cecil counties was opened in 1928 to generate hydroelectric power. It also holds back the sediment that washes into the river and would otherwise flow into the Chesapeake Bay.

Sediment can cloud the water, and smother underwater grasses, oysters and other bottom-dwelling life when it settles. Pollutants such as nutrients are often bound to the tiny bits of dirt, sometimes contributing to algae blooms that suck oxygen out of the water.

The area behind the dam has run out of room to hold back that sediment, leading government officials, the dam’s owner Exelon and environmentalists to look for ways to address the Susquehanna’s sediment pollution.

“It is absolutely vital that we find real solutions for the problem,” Hogan said when he announced the test dredging project.

This initial dredging is expected to be small. The state asked companies for bids to dredge 25,000 cubic yards of material. Officials estimate there’s about 31 million cubic yards of sediment lodged behind the dam.

That’s enough to cover a football field with a pile the height of Baltimore’s Transamerica Tower 35 times.

The request for bids also directed companies to come up with “innovative reuse” options for the material dredged from the river.

When Hogan previously asked companies to submit ideas for creative ways to deal with the Conowingo sediment, a dozen companies responded with ideas ranging from using the sediment as fertilizer on farm fields to turning it into concrete or pavers.

Environmentalists have offered mixed reviews of the dredging idea, with some saying it’s a good idea to challenge companies to come up with new ideas and others cautioning that the state shouldn’t lose sight of the need to address why sediment is washing off the land and into the river.

Just two companies ended up bidding on the contract for the test dredging project, according to the Maryland Environmental Service, an independent state agency that’s overseeing the project.

Northgate-Dutra Joint Venture was selected as the winner over Pennsylvania-based Mobile Dredging and Video Pipe, according to Sharon Merkel, a spokeswoman for MES. A committee that reviewed the bids ranked Northgate-Dutra higher on the technical aspects and cost of its proposal.

Merkel said she could not answer specific questions about either company’s proposal because “the procurement is still active.” She could not say when the procurement process would be complete.

Northgate-Dutra Joint Venture appears to be a combined effort of the Dutra Group, headquartered in San Rafael, Calif., and Northgate Environmental Services, with offices in Frederick and California.

An official at the Dutra Group said he couldn’t discuss the Conowingo project until the contract is finalized. No one could be reached at Northgate’s offices in Frederick, Oakland or Laguna Hills.

pwood@baltsun.com

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