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November 06. 2013 7:01PM

Mark Hayward's City Matters: A sewer for the century


 


Joshua Rule of Dublin climbs down a ladder holding a bucket of concrete while patching the walls of a 26-foot-deep-access chamber to the city's main sewer line on Willow Street in Manchester on Wednesday. (DAVID LANE/UNION LEADER)


Joshua Rule of Dublin climbs a ladder holding a bucket of concrete while patching a 26-foot-deep access chamber to the city's main sewer line on Willow Street in Manchester on Wednesday. (DAVID LANE/UNION LEADER)


Construction officials and workers gather around a 26-foot deep-access chamber to the city's main sewer line on Willow Street in Manchester on Wednesday. (DAVID LANE/UNION LEADER)

SINCE MOST of us use the automobile to go about our daily tasks, we appreciate our city streets. They get us to work, to the store and to Elm Street on weekend nights.

Fred McNeill thinks of streets as rivers.

Not the blacktop, but what runs underneath it. This summer, the head of the city's sewer plant started tearing up streets on the southern edge of downtown to reach the man-made river and its hundreds of tributaries that run under our feet (or at least our automobile tires).

That river carries both good water: rainwater that runs off city lawns, parking lots and streets; and bad water: drain water that runs off and through our bodies.

Like some Neptunian god of water, McNeill and his crew of engineers and equipment operators are splicing that river in two.

"You could say that it is a piped river," McNeill said of the old system, which combined both storm water and sewage into one drainage system. "Now there will be two piped rivers, one specifically for sewage, one specifically for storm water."

Over the next 20 years, McNeill will spend an estimated $165 million on the current phase of the project. He will lay massive concrete pipes — some with a diameter of 5 feet — to channel the storm water beneath the city.

An 8-foot long section of the pipe weighs about 7 tons. Some must be placed and buried as deep as 24 feet below street level.

"It's been a good job," said Shawn Adams, foreman for R.D. Edmunds & Sons, the Franklin firm doing the work. The dirt has a lot of sand, so it's easy to dig up and can be used to refill the trenches after the work is done, he said. Also, the city streets are wide, providing room to work.

Two centuries ago, Manchester had no sewers. Five brooks ran through the city. The brooks became ditches; eventually they were closed in and piped underground as the city grew.

This 20-year phase focuses on Cemetery Brook, which starts at Stevens Pond.

You can glimpse the brook at the 17th hole of Derryfield Country Club before it goes under Hanover Street at the East Side Plaza. It resurfaces briefly on Mammoth Road beside the Marjam lumber dealer before it dives underground through the center city.

At Valley Cemetery it heads due west, passing under the shortstop area of the Fisher Cat baseball field before emptying into the Merrimack River.

This summer's $8 million project involved new piping underneath lower Chestnut Street, which flooded several years ago in a storm, McNeill said.

Sewer pipes — relatively small, 12-inch diameter PVC pipes — are laid beside the larger storm water pipes on the street that fronts the Hillsborough County courthouse, high-rise apartments for the elderly and the backside of the Verizon Wireless Arena.

The city's first sewer system lasted for a century, and some of it will remain. The oldest pipe is made of brick. Three layers thick, it was built by craftsmen who shaped it like an upside down teardrop, which allowed any volume of water to flow fast enough to scour the pipe.

Much of the brick sewer pipes remain watertight and will now carry sewage, McNeill said.

This year's work on Chestnut Street is just about complete. The storm water pipe ends at a newly installed manhole on Willow Street. It measures 8-foot in diameter and is about 37 feet deep.

Basically, it contains a waterfall. Inside the manhole, the storm water will tumble about 12 feet into the Cemetery Brook drainage culvert, which carries it out to the river.

Of course, the work is expensive, and a reason my city sewer bill tops $500 a year. Ten years of West Side work is already completed, at a cost of $58 million. Phase III will be another 20 years and $200 million.

Given those costs, Manchester city officials never embraced the work. And McNeill, an engineer, said it is not a cost-effective way to maintain the water quality of the Merrimack River. So he thinks long term.

The likelihood of sinkholes and expensive repairs will be reduced. A pedestrian/bicycle path will top the relocated Cemetery Brook outfall. And work crews leave rebuilt streets, granite curbs and sidewalks in their wake.

"This," McNeill said, "is basically a 100-year infrastructure upgrade. That's the way I look at it."

Mark Hayward's City Matters runs Thursdays in the New Hampshire Union Leader and UnionLeader.com. He can be reached at mhayward@unionleader.com


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