Keystone Crossroads: The state of sewer pipelines in Pennsylvania

Pennsylvania is an old state, one where people settled and built infrastructure early. That means much of the infrastructure in the Commonwealth’s cities is breaking down with age, needs expensive maintenance, retrofits, or replacement, or just doesn’t fit with contemporary ideas of urban planning. Add to that many cities’ struggling budgets, which keep sewer repairs and maintenance from being addressed in a timely manner.

Keystone Crossroads previously covered where bridges and roadsstand, but what about sewers?

What condition are pipes in? 

The short answer is it’s hard to say.

A pipe’s lifetime can range from 15 to 100 years depending on what material was used to build it and the soil it sits in, according to the American Society of Civil Engineers (ASCE). For example, about half of Philadelphia’s wastewater system has brick piping, which tends to be pretty resilient. In Pennsylvania, some of the oldest pipes came online in the 1800s and have been operating for close to 200 years.

But according to the ASCE, “there is no requirement for sewer systems to inspect and assess the condition of their pipes and to be able to quantify the total length of pipes that are [in] need of rehabilitation.” There’s also “no exact standard to identify a system as in need of rehabilitation,” said Pennsylvania Department of Environmental Protection’s (DEP) Amanda Witman. That makes it hard to say definitively how many miles of pipeline are in what condition.   

Pennsylvania’s Act 537, the Sewage Facilities Act, does require sewage systems to have management plans and these have to track how much liquid gets into the pipes from the ground, which would suggest cracked or broken pipes. The plans have to be updated when new development happens or a municipality’s sewer system needs change, like if the population grows. In many municipalities the plans are older than 40 years.   

Cracked or broken pipes aren’t the only problem, though. Some sewage systems were designed in a way that doesn’t meet today’s environmental regulations; combined sewers are a common example.

What is a combined sewer overflow (CSO) system?

Combined sewer systems collect sewage, rain and melted snow (or runoff), and industrial wastewater into one pipe. The pipe carries all of that to a wastewater treatment facility where it is cleaned and eventually discharged back into a river or other water body. Heavy rains or snowmelt can overwhelm the system, and when pipes exceed the capacity of the sewage treatment plant, the  flow — sewage and all — gets discharged into a nearby stream.

Many older communities in the Northeast and Midwest have CSOs. This type of system emerged when city planners primarily thought of waterways as industrial, utilitarian assets. Today, cities increasingly see their rivers as recreational assets, as well, with diverse ecosystems to maintain.   

An alternative system emerged after World War II. In a separate sewer system sewage runs in one pipe and any storm runoff flows in a parallel, but separate pipe. That way, when there’s a big storm, only runoff enters the streams and rivers through the outflows, a pipe terminus that lets out into a stream. (Even with a separate sewer system, sewage overflows can happen when pipes are cracked and receive inflow during a storm or are somehow improperly blocked.)   

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