Rehabilitating the Sanitary Sewer Infrastructure
Abstract:In this age of technology and scientific advancement, we are coming face-to-face with a crisis that cannot be challenged by technology alone. In large cites and small towns across America, sanitary sewers are failing, and they're failing at an alarming rate. Whether they are failing because of neglect, lack of adequate funding, or sub-standard construction practices, the rate of deterioration still out-paces the resources to fix them. The facts are plainly clear in a recent report card issued by the American Society of Civil Engineers (ASCE), which ranked America's wastewater infrastructure lower than every other infrastructure except for public schools (the grade assigned was a D+, with schools receiving a D-). According to the report:
“The nation's 16,000 wastewater systems face enormous needs. Some sewers are 100 years old. Currently, there is a 12 billion annual shortfall in funding for infrastructure needs; however, federal funding has remained flat for a decade”.
The sanitary sewer system… one of the most significant public infrastructure systems that a city or the public utility operates and maintains. In the U.S. alone, this infrastructure represents approximately 1.3 billion meters of pipeline. But it is also the “ugly duckling” of the public utility enterprise. It is entirely underground, out-of-site, and deteriorating faster than it can be fixed.
In a recent survey by the Association of Metropolitan Sewerage Agencies (AMSA), 65% of those responding reported a chronic problem with sanitary sewer overflows (SSO), with many citing serious impacts to receiving streams and water quality. Most revealing in this survey, however, is the simple fact that “….most communities know very little about the condition of their collection system as it relates to the unauthorized discharge of untreated wastewater to the water body”.
Other studies have estimated that more than 80 billion is needed to restore the wastewater collection system infrastructure in the US, alone. Only a fraction of this is being re-invested into rehabilitation and restoration programs. Current estimates show that only 1-2 billion are being spent annually on sewer renewal and rehabilitation. Identifying the problem is a simple… sanitary sewer overflows, structural deterioration, uncontrolled wet-weather bypasses, and chronic back-ups. Determining the cause of these problems, however, is an enormous challenge. Since the system is below ground (except for an occasional manhole lid), it normally takes extraordinary measures to diagnose it, analyze it, and fix it through conventional and non-conventional measures.
However, there are some bright spots where community leaders have taken a pro-active position to restore the structural integrity and hydraulic reliability of their systems. Some have been quite successful. Most, however, have not. The good news is that through thoughtful planning, careful budgeting, and practical rehabilitation programs, it is possible to get this "hidden" infrastructure under control and on track. However, there are no easy solutions, no magic formulas, and no cheap fixes. Consequently, this paper will address the questions most commonly asked by public works officials:
Where do I begin?
How do I diagnose the problems?
How long will it take?
What rehabilitation options are available?
What results can I realistically expect?
How much will it cost?
Document Type: Research Article
Publication date: January 1, 2001
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