Concept designs for Mermaid Park stream realignment includes cascading waterfall, site naturalization

Whitpain Township is in the conceptual stages of planning the removal of the dam, lake and pool and naturalizing the stream at Mermaid Park, complete with a cascading waterfall, as part of an ecological and stormwater project.

Dr. Laura Craig, senior technical director of water resources for environmental engineering consultant AKRF Inc., presented the concept plans to supervisors last week. The primary focus is the improvement of stormwater management via a naturalized waterway.

“This master plan is proposing where we want the water’s edge to be. One, there will no longer be a lake, and we plan to realign the stream channel,” Craig said at the meeting.

According to the township’s e-newsletter Whitpain Wire, the project is in the very early stages and more engineering work must be completed before the township can seek grant funding for the infrastructure project.

Craig told supervisors last week that her firm has completed a pre-demolition hazardous materials study on the buildings in the park and painted areas around the pool and pool itself for asbestos and lead.

“We did find asbestos in the gatehouse building and lead paint within some smaller buildings, but luckily not at the pool deck. That was clean,” Craig said.

Her team also did a geomorphic assessment of the property to measure the shape of the stream upstream and downstream of the park property, and a longitudinal profile, or survey of the area from Jolly Road to the stream exit, in order to determine the slope of the system and how to control grade, she said.

“We went digging for bedrock. Because it is common for dams to be built where there are bedrock ledges, we knew the dam had been present for a long time, before the pool,” Craig said. “There is bedrock at the very end of the where the pool is. There is an 8-foot drop, which means that drop will continue to exist. We will not excavate bedrock.”

Craig said this bedrock area is at the end of the spillway at the park. 

The concept plan includes proposed barn, pool, camp and pickleball complexes, and a nature play area where the pool exists at the park.

“The main elements of the retoration are related to restoring the stream and restoring the floodplain, that means taking out the dam, getting it so that the stream is no longer running through a pipe under the swimming pool, taking out the huge concrete spillway that is part of dam, taking out any infrastructure in the 100-year floodplain, restoring the riparian corridor, and wetlands, creating a cascading waterfall feature where the bedrock exists, and potentially creating a mowed path walkway.”

The waterfall concept, she said, will take advantage of the natural features on the site.

“We will make sure everything around it is a nice view for everyone enjoying the park,” she said.

The next steps, Craig said, include finalizing all details to draft a construction document and then beginning the permitting process.

“We’re in the ‘pencils down’ phase until we get the approval from the township to move forward,” she said. “We still have quite a bit to do on the design. Then, we have to receive permits from the sate and federal agencies, and then we have to fund it.”

In addition, Craig said all the concrete on the site will be recycled and reused in the park improvements.

“One of the things we can do with (concrete) is use it in constructing streambanks. You crush it up, cover it with topsoil and you’ll never see it,” she said. “We can use quite a bit in the stream channel. We have a big hole created by removing the pool, so we can use that there and fill it in with what will be a play field.”

Craig said the biggest step in the project is finding the funding to complete it.

“It is not going to be an expensive project,” she said.