A window into the restoration of a stream and pond system: the Bedfordshire Project

Feb 27, 2018 ,

Did you know that the Department of Environmental Protection restores streams and creeks throughout Montgomery County? The Restoration Team at DEP has been working on a project to restore a stream and retrofit a stormwater pond in the Bedfordshire neighborhood, to help reverse the effects of decades of largely uncontrolled runoff in the Kilgour Branch Stream Valley Park.

Located in Potomac on a tributary to Watts Branch, over 1,000 feet of stream were restored in this project and a stormwater management pond at the end of the stream was completely rebuilt.

 

The completed project, in February 2018.

 

Why did we choose Kilgour Branch for this project?

As is the case in many streams in Montgomery County, the Bedfordshire stream was actively eroding prior to this project, leading to three- to four-foot vertical eroded banks, sedimentation, and poor habitat for aquatic life.  The stormwater management pond lacked modern design features for improving water quality, controlling small and large storm flows, and ensuring dam safety.

 

Pre-restoration, this stream’s banks were eroding rapidly.

 

The changes we made:

The restored stream now features a series of pools and cobble weirs that carry small flows, while allowing large flows to spread out on the floodplain within the park.  By reconnecting the stream to its floodplain, we are working to protect downstream waters by reducing the energy and velocity of the flow.  More nutrients and sediment are retained in the floodplain, recreating natural processes, instead of sending them downstream.

The eroded channel is now stable, with enhanced habitat for fish and amphibians.  It also improves stream health by replenishing groundwater and increasing “baseflow,” which is the normal stream flow in between storms.  Native trees and other vegetation have been planted to add habitat and ecological diversity.

Newly planted sedges were installed to create an “aquatic fringe,” providing habitat near the upstream end of the pond. The cobble cascade transitioning from the stream is visible at top left.

 

The restored stream flows into the stormwater pond, which provides water quality treatment in a newly-created “wet pool.”  The wet pool is a permanent area of ponded water, several feet deep, that retains water in between storms.  The rebuilt pond also has re-graded slopes and a safety bench to increase public safety, a fully rebuilt dam embankment, and a new riser (flow control structure) and outflow pipe.  In addition to removing pollutants from runoff, the pond now controls the outflow rate from small, frequently-occurring storms for the first time, helping to protect Kilgour Branch from further erosion.

Now substantially complete after construction in 2016 and 2017, the stream and pond treat runoff from 265 acres (0.4 square miles).  The drainage area includes neighborhoods south of Glen Road, west of Falls Road, and northwest of the Falls Road Golf Course, and includes 70 acres of impervious surfaces such as roads, driveways, roofs, and parking lots.  By restoring natural functions and improving stormwater management, the Bedfordshire project helps to ensure clean, healthy streams in the local community and downstream to the Potomac River and Chesapeake Bay.

Pictured here: DEP’s Watershed Restoration Section at Bedfordshire, February 2018. Our job is to lead the planning and design of restoration projects throughout Montgomery County, resulting in cleaner water and healthier streams.

 

To learn more about this restoration project, please visit the Bedfordshire Stormwater Pond and Stream Restoration page on the DEP website. To learn more about other projects throughout the County, take a look at the Watershed Restoration page on DEP’s website, and to learn more about projects you can do on your own property, please visit the RainScapes page.

 

We invite you to scroll through the photos below to see more images of the construction process and restoration progress!

The construction crew builds a cobble weir

The construction crew builds a cobble weir. These weirs help to keep the stream stable and carry normal stream flow. They also provide habitat for some of our smallest stream-dwellers, benthic macroinvertebrates.

 

 Restored stream in first season: Grass is starting to provide permanent stabilization. The restored stream both increases and improves the aquatic habitat in the park.

Restored stream in first season: Grass is starting to provide permanent stabilization. The restored stream both increases and improves the aquatic habitat in the park.

 

The riser takes shape: workers install the rebar and wooden forms for the new riser structure. The black corrugated pipe shown at top is used to divert flow from the work area.

 

Finishing the riser: The concrete floor is poured separately. The drain valve (bottom left) allows the pond to be emptied for maintenance. The low flow pipe (top left) conveys the flow from small storms.

 

Grading the stormwater pond: the riser is partially complete (left). The black diversion pipe conveys all flow from upstream into a temporary opening in the riser, keeping the work area dry.

 

The view six months later: The pond in February 2018, showing the permanent wet pool and new riser. Temporary fencing around the edge of the pond helps to make the pond less inviting to geese while the newly-planted vegetation is becoming established.

The view six months later: The pond in February 2018, showing the permanent wet pool and new riser. Temporary fencing around the edge of the pond helps to make the pond less inviting to geese while the newly-planted vegetation is becoming established.

(3) Comments

  1. Dan Dozier Feb 28, 2018

    This is great. Exactly whah you should be doing for every project.

  2. Michael Rae Mar 09, 2018

    Before the project began a citizens meeting was held in Silver Spring. Information on plans was sent to neighbors. Our house on Colebrook Terrace overlooks the park. The work has been completed and it is not good. A large number of mature trees across the Kilgour Branch “valley” from us were cut down for unknown reasons. They did not block construction equipment which came from our side of the valley. They were not replaced. Don Dorsey’s MoCo DEP June 10, 2016 letter promised “native planting of over 100 trees and 500 shrubs.” Several scrawny trees have been planted, not enough to obscure the view of an eyesore of a large concrete bunker that houses the “riser,” as we were told. In addition, there is now a pond with “no swimming or boating” signs on it. It appears to be an ideal breeding ground for mosquitoes which are abundantly present to begin with. It also presents a potential safety hazard to children and toddlers.
    We conveyed our views by telephone and in writing to the environmental department at MoCo, but received no response. In short, this remake has turned a lovely stream lined with trees into an impersonal bare area with minimal new trees, an unsightly concrete block house and a pond that poses its own dangers.

  3. jjones Mar 16, 2018

    Michael, thank you for taking the time to provide your view of this project. We will be reaching out to you in order to find a time to meet in person and talk about your concerns.

    We welcome feedback from all residents, whether positive or negative, because these projects are for everyone. Part of our outreach approach for every project is to hold several public meetings at a nearby location, as well as individual meetings with residents. For stream restoration projects, we also host a stream walk with the community.

    One of the most common and cost-effective ways to improve water quality, protect streams, and achieve our stormwater permit goals in Montgomery County is to convert older dry ponds to wet ponds. This results in a design similar to the more than 175 existing wet ponds throughout the County.

    Any restoration project will involve some amount of visual change. Part of that change is mitigated over time by the new trees and native vegetation that we planted both around the pond and along the restored stream. As is typical with many of our pond projects, we expanded the footprint of the Bedfordshire pond to provide water quality treatment for the large area draining to the pond. The slopes on the sides of the pond are designed to meet County and state safety guidelines.

    As part of the construction process, DEP had to remove existing vegetation in order to regrade and enlarge the pond. We are not able to replant trees or woody vegetation on, or around, the dam because it is prohibited by state dam safety regulations.

    The concrete riser structure serves as the drain for the pond. Previously, the pond had no riser, but simply drained through a large (54-inch) pipe, which is an outdated design approach that is no longer used. Because of its size, it did not provide any protection to Kilgour Branch from erosion caused by frequently-occurring storms, which would pass through the pipe unabated. The pipe also had issues with joint separation, which is a potential dam safety concern. The pipe was replaced as part of the pond retrofit project.

    With over 250 acres of land draining to this pond, the new riser has to be big enough to safely pass large events, such as the 100-year storm, as required by the County and state. Because risers can be one of the most expensive parts of any pond project, DEP does not size them to be any larger than necessary. We added a new photo to this page to highlight the location you referred to.

    Also – We frequently get questions about mosquitos. Here is the link to more info on this topic: http://montgomerycountymd.gov/mosquito/stormwater-management.html

    Thanks again for your feedback. We will be reaching out to meet with you in person and we look forward to talking more then.

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