Dead Run Restoration Gives New Life to Chesapeake Waterway

The need to protect the Chesapeake Bay watershed and its vast ecosystem has been a top priority of government officials and watershed advocacy groups, leading to extensive efforts to restore multiple tributaries that feed into the bay.

One such waterway is Dead Run, a stream network in Catonsville, Maryland that was identified by the Baltimore County Department of Environmental Protection and Sustainability (DEPS) as a priority project. This designation was due to severe stream bank erosion, limited floodplain interaction, persistent tree falls clogging the stream, exposed sanitary sewer pipes and damaged storm drainage outfall protection.

Without intervention, the Dead Run system would continue to deteriorate, during which time substantial quantities of fine sediment, nitrogen and phosphorous from the erosion would flow into the Chesapeake Bay. These three contaminants are known detriments to the biological quality of bay as they drive turbidity and algal blooms that hinder submerged aquatic vegetation growth and the biological species dependent on that vegetation for food and shelter.

To reverse the deteriorating trends in Dead Run, WSP USA was contracted by DEPS to provide environmental design services for the rehabilitation of the stream. The firm was responsible for assessing the level of impairment within the stream, defining project limits for construction, development of proposed treatment concepts, preferred alternative design and consultation services during construction.

“Reduction of pollutants and the development of a healthy and sustainable stream system was the primary goal of this environmental restoration program,” said Justin Lennon, project manager and hydraulic structures/flood control national practice lead for WSP. “We developed a design for Dead Run using a hybrid approach that incorporates natural channel design methods combined with stream process-based metrics to produce an appropriate treatment for the system.”

Project goals included stabilization of the stream to reduce erosion and associated water quality pollution, development of a sustainable stream design, providing uplift to support aquatic habitat, reconnection of the groundwater levels to the riparian root zones to promote healthier buffers and aquatic habitat, and reconnection of floodplains to allow for high flows to spread outside of the channel.

Work began in 2012 when WSP performed an upland watershed investigation and a full geomorphic investigation of the stream network. The team’s primary discovery from the investigation was that flashy uncontrolled stormflows from the urbanized watershed were being confined to the stream channel and driving the severe impairments to the stream.

The Dead Run design used natural materials for all aspects of the stream reconstruction. The stream bed was designed to use a combination of quarry rock native to the area, mixed with salvaged gravels from the channel.

The stream banks were designed using salvaged subsoil, with a topsoil overlay and biodegradable coconut fiber matting to provide short-term stabilization of the soils.

While removing trees is generally counterproductive to the long-term project goals of an environmental restoration project, in this case the removal of some trees was necessary for stream grading and construction considerations. But Lennon and his team found a way to turn this reality into an opportunity to enhance the environmental integrity of the project.

“Wood removed during the construction was incorporated back into the stream design to minimize waste, provide sustainable material sourcing, and provide habitat enhancements,” Lennon said. “These wood structures are naturally sustainable, provide hardened protection of key stream banks, and provide fish and macroinvertebrate habitat.”

Overall, the design relies on bioengineering for long-term sustainability. Bioengineering aspects of the design included use of native riparian grasses along the channel banks and in the newly graded riparian benches, planting of willow and dogwood stakes along the stream banks to provide well rooted woody vegetation for stabilization of the soils, and tree/shrub plantings.

“Within five years, the dense vegetative growth and integration of natural materials will make it difficult to discern that these segments of the Dead Run were actually engineered” Lennon said.

The design included an innovative off-line stormwater pond designed to capture low-flow stormwater from a storm drain outfall pipe at the head of a small tributary. The team developed a splitter box retrofit at the outfall to siphon off low to moderate stormwater flow conditions for treatment, while keeping both baseflows and high flows in the stream.

“This design element was important and challenging because we needed to split the flows such that baseflow stayed in the stream to maintain the aquatic ecosystem,” Lennon said. “Smaller stormflows were diverted to the stormwater facility for treatment, as they provided the maximum water quality benefit when treated. The largest flow events were routed directly to the stream since the stormwater facility could not be cost-effectively sized to handle the largest flow events.”

The resilience of the stream restoration project was put to the test before its completion in 2018 when a catastrophic storm struck the project area and nearby Ellicott City over Memorial Day weekend. The storm dumped more than 10 inches of rain on the area in four hours, causing significant flooding and damage.

After the storm subsided Lennon, who lives in Catonsville, three miles from the Dead Run project, was concerned how well the stream held up in the barrage.

“The storm was so intense that we had places flooding in our town that had never even had the slightest flooding concerns,” Lennon said. “My first thoughts in the aftermath of that storm was that the Dead Run project could have been a complete loss. The relief that I felt the next day seeing that the project survived the storm was palpable.”

There was damage – about a third of the tree plantings were swept away in the flood, as well as some displacement of riprap at the storm drain outfalls. But in the final analysis, considering that the storm greatly exceeded the 100-year event, the damage was minor and by November 2018, was fully repaired and completed.

“In place of failure, the storm response of the project demonstrated validation of the design and construction performed along the system,” Lennon said.

Today, the stream restoration and the best management practices implemented there are thriving. The stream system has met all project goals and the shrubs, grasses and live tree stakes are densely vegetating the new floodplain areas.

Wetland habitats are forming within the floodplains and will drive water quality improvements for years to come. Biological uplift is visibly notable with significant communities of crayfish and black nose dace returning to the stream.

There is no definitive guidebook that lays out the precise approach to be used in the design of stream restoration projects, as each stream requires an individualized approach based on multiple environmental factors and improved techniques.

“Stream restoration designs are constantly evolving and every project that we do has variations and improvements from lessons learned on prior projects,” Lennon said. “The Dead Run design was no different in that regard.”

The eye-opening performance of the Dead Run channel during the 2018 Memorial Day flood has led to further expansion of its utilization on similar stream restoration projects across the U.S.

“Personally, this project means a lot as it validated the Future Ready™ approaches that we have been developing at WSP for stream restoration design,” Lennon said.