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Big Burst in the Sunshine State
PUCC Takes On 36-inch Force Main In Tallahassee
Portland Utilities Construction Company (PUCC), Portland, TN, is one of the most experienced pipebursting contractors in the United States. They have completed 600,000 liner feet of pipebursting, 30,000 feet of which was in the range of 18-inch diameter or larger. With over a decade of bursting experience, the family owned company continues to set the bar for pipe bursting projects in North America. A recent force main project in Tallahassee, FL, was no exception.
Following tropical storm Fay in 2008, the city’s 36-inch fiberglass resin force main, originally installed in 1985, failed in three places after 14-inches of rain fell within a 24-hour period. The three breaks occurred within a two-mile section of the force main that runs beneath the Capital Circle Roadway, a Florida Department of Transportation (FDOT) roadway that is one of the most heavily traveled in Tallahassee.
The city approached multifaceted engineering and design firm MWH, Atlanta, GA, in March 2009 to assist in the development of a feasible trenchless rehabilitation and replacement project for the force main failure. The question at hand was whether or not a pipebursting technique could be utilized to replace the pipe in order to preserve its carrying capacity. MWH proposed a pilot project to prove the bursting technique to the city of Tallahassee, as well as the Florida DOT. This idea was adopted and performed in August 2009.
Pipebursting was selected as the principal trenchless replacement method to expedite construction, minimize disruption to the existing roadway, and maximize the internal diameter of the renewed pipe. Because this type of fiberglass resin pipe had not previously been burst plus concerns regarding road heave, a pilot project was proposed.
Once selected, the bursting contractor, PUCC opted to utilize a pneumatic pipebursting system from trenchless equipment manufacturer TT Technologies, Aurora, IL.
Pilot burst project
For the pilot project, a 280 linear foot segment at the southern end of the pipe was selected. It was estimated that typical pipebursting lengths for the 36-inch diameter pipe would be in the range of 200 to 400 feet, so 280 feet was used as a pilot length to confirm that those lengths were feasible. The location was chosen because it best represented typical conditions of the project in total. Also, this section was selected as it had a minimal amount of cover, making it a worst case scenario. With road heave being a concern, if the bursting went smoothly here, it was assumed that heave would not be a concern in other areas.