Accepting The Challenges of A “Difficult and Risky” Trunk Sewer Rehabiltiation Project

The Joint Meeting of Essex & Union Counties (JMEUC), a Wastewater Treatment Facility located in Elizabeth, New Jersey, owns, operates, and maintains approximately 43-miles of gravity sanitary sewer trunk lines constructed of various materials ranging in size from 10-inch to 81-inches in diameter. Approximately 14 miles of the trunk sewer is vitrified clay pipe, originally constructed between 1901 – 1904. The trunk sewer line traverses through a number of municipalities situated in two counties (Essex and Union Counties, New Jersey).As a result of pending construction modifications to the Garden State Parkway/U.S. Route 78 Interchange Ramps by the New Jersey Department of Transportation (NJDOT) under a separate construction project, the rehabilitation of two (2) JMEUC trunk sewer sections of 22-inch diameter vitrified clay pipe was undertaken in order to guarantee the continued structural integrity of same. The rehabilitation included the installation of a new 30-vertical linear foot (VLF) manhole in between the installation of a 300-linear foot (LF) section of cured-in-place pipe (CIPP) liner section and the installation of a 457-LF pipe bursting section with a 24-inch HDPE pipe.Videotape inspections of the trunk sewer sections revealed them to be in poor condition with severe cracking, a depressed crown, and inflow/infiltration throughout the entire sections. Based on these conditions and observations of the trunk sewer sections, it was determined that the trunk sewer sections required rehabilitation and/or replacement to remain operational without collapsing due to the construction modifications anticipated for the interchange ramps.Design of the 760-LF trunk sewer rehabilitation project posed several challenges that needed to be addressed prior to the deadline established (June 2008) by the NJDOT. These challenges included the physical condition of the trunk sewer (i.e. depth, size, & length of sewer); the site conditions surrounding the trunk sewer (i.e. river, highways, residential area); maintenance of traffic; limitations of rehabilitation methods; and coordination among several state and local agencies.According to the International Pipe Bursting Association's ‘ Guideline Specification for theReplacement of Mainline Sewer Pipes by Pipe Bursting‘, this project was classified as ‘difficult to extremely difficult’ due to the depth of the existing pipe (>30-feet), the upsizing of the existing pipe (22-inch diameter) to a larger pipe (24-inch diameter) and the length of pipe burst (457-feet). Based on discussions with various pipe bursting equipment suppliers, this project was also classified as “very challenging” and “risky”.The sewer sections are located adjacent to the Elizabeth River within the sloped embankment area with portions that traverse under the existing interchange ramps. Open-cut excavation and installation of a replacement pipe was not an option due to the location of the sewer sections in relation to the river, as well as portions of one sewer section crossing under the interchange ramps and the other sewer section having an average pipe depth in excess of 30-feet. Additional complications were encountered as traffic on the existing interchange ramps could not be interrupted, thereby limiting access to the sewer sections and manholes.Another unique aspect of this project was the coordination involved in keeping everyone informed during the design, bidding, and construction phases. The two trunk sewer sections to be rehabilitated accept sewage from two upstream municipalities located in two counties. Due to the amount of tributary flow involved (2.50 MGD +), bypass pumping requirements also had to be coordinated in advance. In addition, this project had to be coordinated with the NJDOT and their sub consultant because of project funding and scheduling.The design was completed in late 2007 and awarded to the construction contractor in early 2008. Construction was successfully completed in accordance with the design plans and specifications by the end of May 2008. Construction was also successfully completed on time and under the construction estimate.Based on the level of difficulty associated with this project, both the JMEUC and CDM concluded that this project was an overall success that delivered and provided the rehabilitation measures to the existing trunk sewer sections to accommodate the modifications to the Garden State Parkway/U.S. Route 78 Interchange ramps performed by the NJDOT. This presentation/paper will discuss the challenges encountered, as well as the solutions which led to ultimate project success.