LATERALS AND MANHOLES: THE IMPORTANCE OF GETTING A GOOD SEAL
Beneath the streets, homes, and businesses of Newark, New Jersey, lies an underground renaissance: The rehabilitation of the City's 150-year-old brick combined sewer system.
The City of Newark, like many other Cities around the Country, has an old sewer system. Beginning in 1990, the City started to evaluate the condition of its brick sewers by internal inspection. Among other technologies, Newark has used non-invasive, structural cured-in-place pipe (CIPP) lining to rehabilitate portions of its deteriorating brick sewer system. Today, structural CIPP is a fairly common method of rehabilitation, but Newark's brick sewer rehabilitation program is unique in several ways. The size of the sewers rehabilitated via CIPP (up to 108” diameter), and the length of some inversions (approximately 1/4-mile of 71"×58” to 66"×78” sewer lined in two inversions) stretched the limits of the technology. The methodology of determining which segments needed rehabilitation was unique as well. In addition, the City and CDM have improved the “details” of CIPP work.
Newark's approach began with a desire to prioritize the repair of sewer segments throughout its brick sewer system. In 1997, under Phase III/IV of the program, CDM was selected to internally inspect and evaluate brick sewers that had not previously been evaluated or rehabilitated. Over the course of the next few years, over 21.3 miles of the City's combined, mostly egg-shaped brick sewers were videotaped. CDM reviewed the footage to determine which sewer segments were most in need of repair. Rather than focusing on one sewer size range or geographic area within the City, this method allowed CDM and the City to target first the sewers in worst condition. It also allowed for the prudent usage of available funds.
When taking the data from the evaluations into design for construction, the City was adamant that the rehabilitation should be as complete as possible because the targeted sewers are not likely to be addressed again for at least another 50 years. Structural CIPP is a good choice for long-term rehabilitation, as it is a long-lasting and cost-effective method of sewer rehabilitation.
In addition to repairing the sewers via cost-effective, long-term methods, CDM's innovative use of CIPP on the city's 105-inch and 108-inch diameter pipes stretched the limits of the technology, providing an economical solution to more costly technologies such as fiberglass plate lining and more traditional, less corrosion-resistant gunite lining. All CIPP installations in the City are presently being done by water inversion and water curing, making the installation of the 108-inch diameter, 2.6-inch thick and the 105-inch diameter, 2.81-inch thick resin-impregnated felt liners especially unique.
During the program, the City and CDM also decided to pay attention to the miscellaneous work that could be done to make the finished product more valuable to the City. The City and CDM realized that the most common areas for discontinuities in CIPP lining are at manholes and around lateral connections. The approach to these areas is discussed herein.
Document Type: Research Article
Publication date: January 1, 2005
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