In the summer of 2006, the City of Livonia contracted Hubbell, Roth & Clark, Inc. (HRC) to design, bid and administer a construction project that would involve the replacement of approximately 23,000 feet of undersized and deteriorated main and the installation of about 4,000 feet of new main for looping purposes. As part of the design process a number of discussions regarding pipe material and construction methodologies were conducted with City staff. Historically, the City of Livonia specifications for water main required the use of poly-wrapped, cement lined, ductile iron (DI) pipe. However, more recent projects allowed high-density polyethylene (HDPE) pipe in support of the continued growth of various trenchless technologies in the construction industry. In an effort to get the most cost effective method to complete the project as determined through the bidding process, it was determined that HRC would develop a bid package that allows the various technologies to bid against one another. Ultimately, a form of trenchless technology that originated in Europe called pre-chlorinated pipe bursting proved to be the most cost effective method for replacement of the existing undersized and deteriorated mains.
Pre-chlorinated pipe bursting utilizes HDPE pipe and entails the pre-assembly and testing of approximately 300 ft. to 500 ft. lengths of pipe above grade at a nearby staging location. Once the pipe is proven to be sound by the pressure and disinfection testing, a series of small excavations are made and the new pipe is pulled into place by bursting the existing main. A post chlorination and flushing of the main is then performed and the new line is connected into the distribution system. Ultimately, all services are connected into the new main and the surface area is backfilled to preconstruction grade. The entire process is completed within a single day (7-10 hours), thereby minimizing the disruption to area residents.
Although the process was approved by the Michigan Department of Environmental Quality (MDEQ) in May 2005, this is the first municipal pre-chlorinated water main construction project in Michigan. Prior to allowing this method for the Livonia project, HRC discussed the process with City staff, the Detroit Water and Sewer Department, MDEQ and a number of other agencies/municipalities from Florida and Indiana where the contractor had completed previous projects.