Saturday, December 22, 2012

Mudslide Improvement Project On I-76

Over the last three months, PennDOT's been working on a project on the eastbound side of the Schuylkill Expressway just after the Conshohocken Curve to help reduce the frequency of mudslides and runoff events onto the expressway from the hillside immediately above it.

The project, which costs $1.2 million, started in September.  The goal is to improve water flow and drainage in areas that have historically been prone to high levels of runoff along the hillside.  This has lead to several mudslide events along the Schuylkill in heavy rain events over the past couple of years, some of which have shut the expressway down for several hours at a pop, including one particularly "fun" event on a Sunday morning in August 2009.

Here are a couple of PennDOT camera shots that show the work being done along the highway now -- in addition to regrading the hillside immediately above the highway, improved drainage "blocks" have been installed in key locations just above the shoulder to help divert water into underground channels that were built in during the highway's construction int he 1950's.  These channels overwhelmed in big rain events, leading to water spilling onto the roadway.  Erosion on the hillside had become an increasingly big issue as heavy rains helped bring loose soils down the hillside, clogging the channels, and also spilling over onto the roadway.

In theory, this should help mitigate the roadway flooding that had been a major issue in times of heavier rainfall.  This area, thanks to its location just above the Fall Line, has been prone to more excessive rains as the slight bit of elevation difference between the city farther southeast and areas further northwest tends to lend towards extra precipitation getting squeezed out.

The project will continue through the winter provided weather cooperates and should wrap up in April.