Environmental

Maryland Environmental Service begins pilot dredging project at Conowingo Dam

Maryland Environmental Service begins pilot dredging project at Conowingo Dam

To help understand the role dredging can play in mitigating the effects of upstream discharges and the lost trapping capacity of Conowingo Dam, the Maryland Environmental Service (MES), in coordination with the Maryland Department of the Environment (MDE), is beginning the dredging portion of the Conowingo Dredging and Innovative and Beneficial Reuse Pilot Project.

Conowingo Dam impounds water for a hydroelectric powerhouse with a capacity of 570.15 MW.

The contractor will dredge about 1,000 cubic yards of sediment, equivalent to 100 dump truck loads, from Conowingo Reservoir, providing dredged material for various reuse testing programs, including concrete and asphalt manufacturing, cement clinker, soil blending for sport horticulture, engineered highway soil, and/or supplemental cementitious materials.

“The initiation of dredging at the Conowingo Dam is an exciting move forward for the Conowingo Dredging and Innovative and Beneficial Reuse Pilot Project,” said Dr. Charles Glass, executive director of MES. “The removal and dewatering, and subsequent testing of the dredged material, allows us to explore new options for long term solutions for improving the overall health of the Chesapeake Bay and will provide greater insight into beneficial reuse of dredge materials.”

The Conowingo Hydroelectric Dam, constructed in 1928 and owned and operated by Exelon Generation Company LLC, has trapped sediment and nutrients that enter the Susquehanna River upstream of the dam. Scientific reports confirm that Conowingo Dam has reached full capacity and can no longer trap sediment and nutrients, meaning upstream pollution is now entering Chesapeake Bay.

The Conowingo Dredging and Innovative and Beneficial Reuse Pilot Project is part of a multi-pronged approach to improve the health of Chesapeake Bay. The state’s strategy includes conditions relating to Federal Energy Regulatory Commission relicensing of the dam and hydro project and an agreement between MDE and Exelon that requires the company to invest more than $200 million in ecological and environmental projects and services, and operational enhancements to improve water quality in the Susquehanna River and Chesapeake Bay. It also includes a multi-state Conowingo Watershed Implementation Plan designed to address the additional pollution that is moving into Chesapeake Bay as a result of the lost trapping capacity of Conowingo Dam.

“Maryland is taking a holistic and aggressive approach to restoring the Chesapeake Bay, working with states, the federal government, and many others to reduce pollution upstream and behind the Conowingo Dam so we can clean the water, increase climate resiliency, and put sediment to productive use,” said Maryland Environment Secretary Ben Grumbles.

The dredging work should be completed in October 2021. Upon completion of the innovative reuse portion of the project, a report summarizing the findings of the demonstration projects will be issued by summer 2022.