HDD Pipe-Bursting Works Twice as Fast

September 28, 2010

A Vermeer Navigator replaces sewer pipe along one of the airport's access roads without disrupting ground surfaces or traffic flow.

The Hammerhead Impactor (foreground) uses a barbed head for greater shattering power and pulls in the attached new pipe.

Having recently completed the unobtrusive replacement of a major fuel-oil line at the Statue of Liberty, horizontal directional drilling (HDD) contractor New York Trenchless, based in Port Washington, N.Y., was asked by New York City to bid on replacing 3,400 feet of 12-inch sewer pipe at JFK International Airport.

This seemingly routine job, however, had complications. For one, JFK is located in Jamaica Bay, a huge ecosystem complex the city is keen to protect. For another, the project had a two-week completion date. But perhaps most disconcerting for New York Trenchless, the suggested method of replacing the sewer was conventional pipe bursting, a technique the company considered outside its area of expertise.

Company principals, however, were familiar with Vermeer's new pipe-bursting system, which employs a horizontal direction drill and an innovative pneumatic tool, the Hammerhead Impactor. So, having the HDD machines and expert crews to run them, the company decided to take a leap of faith and bid the job with the new technique.

The technique involves first making a conventional bore into the back of a manhole, entering at the depth of the sewer pipe. The operator then pushes the drill string through the old line and surfaces just beyond the next manhole. There, the drill bit is removed, the Hammerhead Impactor is threaded onto the drill string and the new pipe is attached to the tool. Compressed air is then forced down the drill string, causing the Impactor to exert a shattering force on the old pipe as the HDD operator pulls back.

In just seven days, the company had completed the job, installing as much as 720 feet of new line in one day with two shots. Says the company's Bob Smith: "By my estimation, the technique is twice as fast as conventional pipe-bursting."