ACCEPTING THE CHALLENGES OF A DIFFICULT AND RISKY TRUNK SEWER REHABILITATION PROJECT

摘要

The Joint Meeting of Essex & Union Counties (JMEUC) owns, operates, and maintains an existing 13.9-mile long trunk sewer constructed of vitrified clay tile pipe. Originally constructed from 1901 - 1904, the sewer line traverses through several municipalities from two counties (Essex and Union Counties, New Jersey). In order to accommodate the modifications to the Garden State Parkway/U.S. Route 78, Interchange ramps performed by the New Jersey Department of Transportation (NJDOT) under a separate construction project, the rehabilitation of two (2) sections of 22-inch diameter vitrified clay pipe was undertaken. 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. Based on videotape inspections, the trunk sewer sections were determined to be in overall poor condition with severe cracking, a depressed crown, and inflow/infiltration throughout the entire sections. Based on the condition of the existing trunk sewer sections, it was determined that the trunk sewer sections would require rehabilitation and/or replacement in order to remain operational without a chance of collapse as a result of the construction modifications to the Garden State Parkway/U.S. Route 78 Interchange ramps performed by the NJDOT. Design of the 760-LF trunk sewer rehabilitation project posed several challenges and needed to be completed prior to the deadline established by the NJDOT. Challenges included the existing physical conditions of the trunk sewer (i.e. depth, size, & length of sewer); the site conditions surrounding the existing trunk sewer (i.e. river, highways, residential area); the maintenance of traffic; the limitations of rehabilitation methods; and the needed coordination among several state and local agencies. According to the International Pipe Bursting Association's 'Guideline Specification for the Replacement of Mainline Sewer Pipes By Pipe Bursting', this project was classified as "difficult to extremely difficult". The sewer sections are located adjacent to an existing 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 existing river as well as portions of one sewer section crossing under the interchange ramps and the other sewer section having an average depth of pipe 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 aspect of this project that was unique was the coordination involved to keep everyone informed of the design, bidding, and construction. The two trunk sewer sections to be rehabilitated accept sewage from two municipalities from two counties and bypass requirements had to be coordinated in advance. In addition, this project had to be coordinated with the NJDOT and their sub consultant because of the overall project funding and overall project schedule. The design was completed in late 2007 and awarded to the construction contractor in early 2008. Construction was successfully completed on time and within budget in accordance with the design plans and specifications by the end of May 2008. This presentation/paper will discuss the challenges encountered, as well as the solutions which led to ultimate project success.