Alcosan project will leave sewage tunnels flush with cleanness
The rushing sound that more than a half-century's worth of grit makes as it's pumped from a 5-foot-wide sewage tunnel 80 feet below the Allegheny River brings a smile to Timothy Prevost's face.
“The guys like to say that's the sound of money,” said Prevost, manager of wet-weather programs for the Allegheny County Sanitary Authority.
It really is.
ALCOSAN is paying Detroit-based contractor Doetsch Environmental Services a $270 performance bonus for each ton of debris workers blast out of the line, using 60,000 gallons of highly pressurized river water each day.
Submersible pumps bring the grime to the surface, where it's shipped to a landfill in sealed, truck-size orange containers situated next to the Confluence Building and the Morgan at North Shore Apartments.
Prevost said workers shut down noisy generators and engines by 7 p.m. so they don't disturb residents. Neighbors said they aren't bothered by noise and haven't noticed an odor.
Doetsch built a long, plywood conduit to contain the pipes so the North Shore Riverfront Trail could remain open to pedestrians without the need for a detour.
In January, the firm extracted about 100 tons. Work on a 1,200-foot-long section of the sewage tunnel began in December and is expected to wrap up this week. Doetsch won a $712,000 contract to do the work last year.
Prevost, a civil engineer, is overseeing the progress. It's the first time since ALCOSAN was formed in 1946 that the high-density concrete tunnel is being cleaned. Workers encountered bricks and large rocks that slowed progress because they can't fit through the pumps.
“It's a very difficult operation, so it's not something that's typical,” Prevost said.
Sonar inspections of the deep tunnel indicated a significant amount of debris. He said some of the debris, grit and rocks flows into the system from a stream that runs through the Spring Garden neighborhood of the North Side and from drainage through the East Street corridor along the Parkway North.
“We knew what was in the line; we just needed to figure out how to get it out,” he said.
Removing the debris will increase the sewer line's capacity and help ALCOSAN comply with a Environmental Protection Agency consent decree to reduce the sewage overflows into waterways during storms. On a dry day, the line handles about 16 million gallons, but in wet weather, that amount can spike.
Construction costs to upgrade the system could top $2 billion, making it the largest public works project in Allegheny County history.
“We're required to address the situation of debris coming into the lines,” Prevost said. “If I have a pipe that's half full of something, that means I only have half of that pipe to have water and sewage flow through it. I'd rather have full capacity.”
Jeremy Boren is a staff writer for Trib Total Media. He can be reached at 412-320-7935 or email@example.com.
Show commenting policy
TribLive commenting policy
You are solely responsible for your comments and by using TribLive.com you agree to our Terms of Service.
We moderate comments. Our goal is to provide substantive commentary for a general readership. By screening submissions, we provide a space where readers can share intelligent and informed commentary that enhances the quality of our news and information.
While most comments will be posted if they are on-topic and not abusive, moderating decisions are subjective. We will make them as carefully and consistently as we can. Because of the volume of reader comments, we cannot review individual moderation decisions with readers.
We value thoughtful comments representing a range of views that make their point quickly and politely. We make an effort to protect discussions from repeated comments either by the same reader or different readers.
We follow the same standards for taste as the daily newspaper. A few things we won't tolerate: personal attacks, obscenity, vulgarity, profanity (including expletives and letters followed by dashes), commercial promotion, impersonations, incoherence, proselytizing and SHOUTING. Don't include URLs to Web sites.
We do not edit comments. They are either approved or deleted. We reserve the right to edit a comment that is quoted or excerpted in an article. In this case, we may fix spelling and punctuation.
We welcome strong opinions and criticism of our work, but we don't want comments to become bogged down with discussions of our policies and we will moderate accordingly.
We appreciate it when readers and people quoted in articles or blog posts point out errors of fact or emphasis and will investigate all assertions. But these suggestions should be sent via e-mail. To avoid distracting other readers, we won't publish comments that suggest a correction. Instead, corrections will be made in a blog post or in an article.
- City’s plan for Strip flummoxes vendors
- Orders for Pittsburgh police hats soar with new uniform policy
- City of Pittsburgh detective, 2 boys finalize adoption before judge
- Local groups hope NFL lends support
- $5M grant sought for trade center site near Pittsburgh airport
- Marshall land parcel along Route 910 eyed as park site
- Judge denies request to lift gag order in Ford case
- CDC backlog means W.Pa, likely won’t get respiratory virus diagnoses quickly
- Club for ‘good’ hackers formed at IUP
- Google grants teachers’ school supply wishes
- Newsmaker: Ron Rohall