Confronting Restoration Challenges in Urban Areas
As we have been talking about river restoration challenges this month, it is important to recognize that different challenges exist in different environments. Today, I am going to talk about some of the challenges that are often faced when doing river restoration work in an urban or suburban environment.
One of the first steps in planning a river restoration project is to take stock of what existing infrastructure—including sewer lines, gas lines, or even fiber optic cables—may be affected by conducting river restoration. It is not uncommon to encounter some type of utility line buried under or running alongside a river in an urban/suburban setting. Not all utility lines are active. Some have been abandoned as new lines are added and, depending on their location in relation to your restoration project, should be considered for removal. However, if still in use, we must figure out what the appropriate design response is. This could include everything from an option to relocate the utility line (often it is better to move them out of the river anyway to reduce storm damage) to developing a workaround in order protect it from damage. Every situation is different, and requires individual consideration.
We ran into this particular challenge when we were analyzing the feasibility of removal of the Easton and Chain Dams on the lower Lehigh River in Pennsylvania. There are two sewer lines, one water line, one natural gas line, one petroleum line, and more than 50 stormwater outfall pipes in the vicinity of these impoundments. These lines and pipes all had to be evaluated as part of the feasibility study to determine if they would be impacted by the project, and what conflicts might need to be resolved if it was decided to proceed with dam removal. Dealing with these types of structures can add time and money to the cost of the project. Modeling of changes in water flow also had to be conducted to determine the impact on area bridges (see next challenge— when it rains, it pours!).
Other elements that we encounter in urban environments are bridges, roads, culverts, levees, and other hard infrastructure associated with the river. Ideally, when we do river restoration work, we aim not only to remove a barrier, but also to restore function to the floodplain. In urban areas, you often see hard infrastructure in relatively close association with the river. Will these structures be impacted by the restoration project, and if so, how can critical infrastructure be protected or improved? In certain cases, improvements or modifications to the infrastructure itself may be the restoration project (e.g. replacing a perched culvert with a bridge).
For example, we have been working on the removal of the Centreville Dam on Gravel Run in Centreville, Maryland. This dam is in downtown Centreville, and several pieces of infrastructure are immediately downstream of the dam, including a sewer line, a water supply line, and a box culvert. Since one of the primary goals of the project is to provide river herring and other fish access to upstream habitat, a rock ramp will be used to provide passage over the elevated sewer line and through the culvert, allowing fish access habitat opened as a result of the dam’s removal.
Securing the Site
The more populated the area is for a project, the more attention it is likely to draw from the local population. Inevitably, more people milling around near a project site lead to an increased need to secure the area. This can range from locking equipment, to running security cameras, to fencing off unsafe areas, to obvious signage denoting the restricted area and risks. Most of our urban projects have to deal with this issue to some degree.
An issue that is less obvious, but still challenging to manage is public behavior around recovering sites after construction. Often project sites need some time to establish stabilizing vegetation to fortify the river banks following a restoration project. It is hard when people want to play in the area and see how everything turned out. Re-establishing grass, trees, and shrubs can take time, and that can be challenging once areas no longer have staff around to enforce restrictions on access to the area. It’s like an open wound— it takes time to heal and must be allowed to do so.
The City of Waynesboro, Virginia understands this problem all too well. The City is currently working to reduce bank erosion and improve trout habitat along the South River as part of our Potomac Highlands Implementation Grant Program. The restoration is occurring in, among other places, one of its most popular parks. They have worked to remove heavy riprap from the banks and replace it with native trees and vegetation. However, time is required for allowing vegetation to grow. It is not an easy task keeping people from travelling along the banks of the river in the parks.
These are some of the challenges that managers of urban restoration projects face. Other issues, like dealing with water quality concerns, can quickly become much more complicated. It is our responsibility as river restoration experts to find solutions to these problems, so that we can restore degraded rivers for the benefit of fish, wildlife, and people. Luckily, we are up to the challenge!