PITTSBURGH (KDKA) — Cities around the country are boring underground to build tunnels like the ones underneath Washington DC, but they’re not for new subways.

Like Washington DC, Pittsburgh, Allegheny County and other cities are under federal orders to fix their deteriorating sewage systems. The tunnels are designed to trap overflow sewage before it flows into their rivers and streams.

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The feds want us to build tunnels here in Pittsburgh, but Mayor Bill Peduto hates the idea.

“What we’re looking at is the most expensive, most archaic way of being able to solve the problem,” said Mayor Peduto.

In an effort to derail the tunnels, Mayor Peduto and Allegheny County Executive Rich Fitzgerald petitioned the federal Environmental Protection Agency, of EPA, for a 10-year extension in planning for and building the tunnels.

In response, the EPA has now offered a compromise, telling the city and county to get started on their planning in three years and start tunnel construction in six.

“I think the EPA is basically saying, ‘We’re going to be flexible. You’ve got to do things; we’re not going to just let you delay,’” said Fitzgerald.

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Every time it rains, the sewage system gets overloaded and raw sewage spills into our rivers and streams, 10 billion gallons a year.

The tunnels, which are designed to trap that overflow, are a so-called grey solution. But the mayor and county executive have joined environmentalists in favoring green solutions like rain gardens and green roofs that soak up the water before it gets into the system.

“We’re all on the same page. We’re all working together toward a green solution,” said Fitzgerald.

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But now all seem to agree that some length of tunnels will be necessary once those green solutions have reached their limits. In a letter to Fitzgerald and Peduto, the EPA tells the city and county to get started:

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“After over two years of negotiation, it is time for EPA and ALCOSAN to bring to closure these discussions… We believe it is time to implement a plan to address the billions of gallons of raw sewage discharges that pollute the water of Allegheny County.”