July 17, 2024
Lake Marion Project Update
Restoration of Lake Marion is well underway! Along with our partners at Anne Arundel County, Provinces Civic Association, and the Severn River Association, the year-long effort to restore and enhance Lake Marion has made quite a bit of progress since work began in March 2024. The early phases of the project have focused on two key areas: removing the existing embankment and installing a massive concrete weir wall.
To ensure long-term integrity and stability of a pond, a properly constructed embankment wall is key to retaining water. Over time, the embankment that dams up Lake Marion fell out of compliance. As the lake filled with sediment, trees and other vegetation spread over the embankment. While trees are excellent in so many ways, they are not suitable for embankments as the roots break up the compaction of the embankment wall making it more vulnerable to failure. This first phase of construction focused on building a smaller, temporary embankment to secure the lake during construction. Once that was complete, the existing embankment was deconstructed. The embankment will be rebuilt to ensure proper soil compaction for long-term stability and functionality. Once completed, the embankment will be stabilized with grasses and need to remain free of larger vegetation with more damaging roots.
The most complex part of the project also occurred during the initial phases of construction. A massive concrete weir wall was installed to guide overflow from the lake into the eventual habitat step pools. However, installing this massive structure isn’t as simple as ordering a prefabricated wall and dropping it in place. The area around the wall location had to be drained with a specialized system of pumps and wells over a number of weeks. This is done to ensure that the wall sits firmly on compacted earth. Installing on unstable, wet soils could cause the structure to sink or settle unevenly. Once the lake bottom in that area was properly dried out, the crews had to build a massive frame in place using specialized materials not frequently used on restoration projects. Once the frame was in place, concrete was brought in and poured into the frame using a series of concrete trucks and a specialized truck with pumps capable of moving and pouring concrete down into the frame. The temperature of the cement had to be continuously monitored to ensure it remained at an appropriate temperature for correct settling compaction. If the temperature got too high, ice had to be used to bring temperatures back down.
Moving forward, construction will begin to focus on removing the long, broken concrete channel that winds down into Severn Run. As this is removed, large habitat step pools will be installed in its place creating new habitat where there has been nothing more than concrete for over 50 years. The final phase of the project will dredge the middle of the lake restoring depths suitable for more habitat. The perimeter of the pond will be a 25 foot wide wetland complex to further enhance the habitat value of the site and provide additional water quality treatment.