9 December 2019
These signs announcing the closure of Schenley Park’s Bridle Trail and some tree removals are actually good news. Here’s why.
Pittsburghers are among the 40 million people in the U.S. who use combined sewer systems that carry both rainwater and sewage. Built between the 1860s and 1920s the pipes dumped directly into our rivers until the 1950s when Allegheny County opened a sewage treatment plant. (Fortunately, Pittsburgh has been disinfecting drinking water since 1911.)
By now our sewers are over 100 years old and too small to handle heavy rain. In some places it takes only a 1/4 inch to cause a sewer overflow, sending toilet paper to the rivers. Meanwhile climate change has brought frequent heavy downpours that flood some valleys with sewage, including the neighborhood below Schenley Park.
That neighborhood, called The Run, is located at the base of Four Mile Run’s watershed where all the old sewers converge before reaching the Monongahela River (highlighted in red on the 3D map below).
The Run bears the brunt of heavy downpours when the sewers back up into basements and streets. The Greenfield Community Association’s website has video plus photos of a manhole spouting 20 feet under the Parkway bridge.
People are sometimes trapped by the floods in The Run. On 28 August 2016 a father and son had to crawl through the sunroof when their car was swamped on Saline Street. Click here for photos of the flood and rescue.
The less rainwater that enters the sewer system the better it is for The Run. Toward that end the Pittsburgh Water and Sewer Authority (PGH2O) is working in Schenley Park for the next several months, building detention swales along Overlook Drive and the Bridle Trail to channel stormwater away from the sewer system.
When the project is done they’ll plant more trees than they removed.
Schenley Park will help stop the flood.
For more information, see Channeling The Energy of Fast Moving Rain
(photos of signs by Kate St. John, photos of flood by Justin Macey, maps from 4mr.org)