Dam Removal & Stream Restoration

Feb 26, 2012 by Stephanie

Last November, PennDOT met with Media Borough Council members and clarified that PennDOT’s funding for 80% of the 3rd Street Bridge/Dam project will cover multiple options, including removing the dam. Borough Council is now considering dam removal and stream restoration as an option for the 3rd Street Bridge/Dam project.

The Friends of Glen Providence Park advocates learning more about dam removal and stream restoration to determine if this is right for the 3rd Street Dam.

Here is what we have learned so far:

– Dam removal is an option supported by PennDOT and the PA Department of Environmental Protection. Both PennDOT and the PADEP have funded dam removal when they find it appropriate, for various safety, environmental and economic reasons.

– Pennsylvania is the national leader in dam removal: According to Laura Craig of American Rivers, Pennsylvania has removed approximately 250 of 1,000 total dams removed so far in the United States.

– Locally, dams are being removed from Ridley, Chester and Darby Creeks: American Rivers is working with Delaware County and the PADEP to remove 4 outdated dams along Darby Creek, as part of Delaware County’s Greenway Plan for the Darby Creek Watershed. There is information on the CRC Watersheds website about the removal of the Irving Mill and Sharpless Dams on Ridley Creek, and the planned removal of two dams on Chester Creek.

Facts about dam removal:

– Costs much less than repair, saves taxpayer dollars: Dam removal generally costs 1/3 of estimated reconstruction costs. In the case of the 3rd Street Dam, the last estimate for replacement of the dam was for over $3.2 million. Laura Craig of American Rivers, a national leader in dam removal, has given an initial estimate that the dam removal and stream restoration at 3rd Street would cost under $1 milllion. This does not include the cost of a bridge, which could range from a pedestrian/bike bridge to a two-lane roadway.

– Best environmental practice for outdated dams and lakes: Dams affect water quality, fish and animal habitat, sediments and streambanks, and when dams serve no functional purpose, their negative impacts often outweigh any benefits. For more information, read the Small Dam Removal in Pennsylvania Fact Pack by the Pennsylvania Organization for Watersheds and Rivers.

– Eliminates safety risks and public liability: Safety and liability concerns are usually the primary factor influencing decisions to remove dams.

– Prevents dam maintenance costs: this is self-explanatory.

– The process includes streambank restoration and replanting of native trees and plants: Laura Craig indicated in her presentation that native shrubs, grass and trees would be planted as part of stream restoration and stream bank stabilization.

What about the 3rd Street Dam?

– Dam removal would drain Broomall’s Lake and return the area to its pre-1883 condition: We have not found any photographs of Broomall’s Run before the dam was built, so we cannot know exactly how that would look. The stream would be similar in size and appearance to the existing stream both upstream and downstream of the current dam. But there is a 30′ elevation drop from above to below the dam, so any resulting stream would have some natural falls to make that descent.

– The lake is private property with no public recreational or functional uses: The lake is the private property of Broomall’s Lake Country Club. The lake was once used for swimming, but there has been no swimming since the 1960’s when the Club’s swimming pools were installed.

– Without costly dredging, the lake will become a marsh: When the lake was formed in 1883, it was over 30′ deep, but due to sedimentation it is now approximately 8′ deep. While no one can say how long it would take, experts who have looked at the dam, including Laura Craig of American Rivers and Borough Engineer Robert Johnston, agree that Broomalls’ Lake will continue to fill in and become a marsh, in as soon as 10-15 years.

– Dam removal would be least damaging to Glen Providence Park: Schnabel Engineering indicated that the area to be filled with landfill for a new dam would extend 70′ out from the current dam wall, along a length of 300 to 400′– this is .48 to .64 acres. Beyond that area, trees will need to be cleared so that construction vehicles can access the site- according to Larson Design Group, this total area within the “limits of disturbance” is 1.11 acres. For dam removal, the base of the dam would still need to be accessed, but it should not need a larger access area than for building a dam, and there would be not be the loss of up to .64 acres to landfill. This creates an estimated “limit of disturbance” of less than 1/2 acre. Furthermore, with dam replacement, no trees would be allowed within 10′ of the base of the dam– extending the permanent impact to the park. With dam removal and stream restoration, there would be no such restriction, rather the stream banks and wetlands would be allowed to be in a natural state.

The Friends of Glen Providence Park supports an expert site assessment to determine if dam removal is right for 3rd Street.

In March, the Council-appointed Citizens Advisory Committee will mail a survey to Media Borough residents, business owners and property owners to solicit their opinions on the 3rd Street Bridge/Dam project. It is important to understand all of the options being considered for the project in order to have an informed opinion.

Do you still have questions? So do we! Join us at the Community Meeting to Address Media’s Third Street Dam Project on March 5:

– Laura Craig of American Rivers will explain dam removal and stream restoration.

– John Harrison of Schnabel Engineering will explain the proposed design for dam replacement.

– You will have an opportunity to ask questions, voice your opinion, and complete a survey- whether or not you are a Media Borough resident, business owner or property owner.