Roughly 1.5 million miles of buried water line exist in the United States. About one—third of these pipes are in need of replacement or repair right now, and many experts believe that by 2020 nearly half of these lines will need some type of renovation or extension.
In some parts of the country, replacing outdated water and sewer lines using traditional open—cut excavation methods is simply not an option. The village of Glen Ellyn, Illinois, is one such place.
Glen Ellyn is a beautiful community, with stately homes and revered, 100-year-old trees. But below the streets of this affluent town, located about 23 miles west of Chicago, it is not as beautiful. Like most communities across the country, Glen Ellyn has aging water and sewer lines that are straining—and often failing—to meet the water and sewer needs of today's larger populations. And, like most communities, Glen Ellyn doesn't want the replacement of this infrastructure to disrupt normal life any longer than it absolutely has to.
Fortunately, advancements in trenchless technology have made it possible to replace water and sewer lines faster and with far less impact on the landscape than ever before, as citizens in Glen Ellyn recently discovered.
An 800-foot storm drain deep beneath a residential street in Glen Ellyn was in need of replacement. After taking bids from several contractors, city officials awarded the job to Trench Rite, Inc., a construction company from nearby Elgin, Illinois, based in part on the company's intention to use trenchless technology—horizontal directional drilling (HDD) equipment and a relatively new technology: pipe bursting systems.
For this job, a pipe bursting system was the preferred option because the storm drain ran below the sewer line. Trench Rite rented a Ditch Witch PR95 pipe bursting system from Ditch Witch Midwest of Carol Stream, Illinois. The first step was to build a launch pit for the pipe bursting unit and an exit pit on the other end of the installation. The launch pit was 18-feet below the ground—well below the sewer line and other infrastructure in the vicinity. To reinforce the pit walls, the contractors used solid-steel shoring.
The pipe bursting process begins by pushing a series of threaded, one-meter steel rods through the existing pipe. When the rod string reaches the exit pit, a cracking head is attached to the rod string and then pulled back to the launch pit. (There are cracking, cutting, and splitting heads, depending on the type of pipe being replaced.) Behind the cracking head is the replacement pipe, which takes the place of the old pipe as the cracking head breaks through it.
The pipe being replaced was ten-inch VCP (vitrified clay pipe). To expand the capacity of the drain, the VCP was replaced with 16-inch IPS polyethylene pipe. With 95 tons of available pullback force, the PR95 is capable of replacing clay, steel, or iron pipe with polyethylene pipe of greater diameter.
This was Trench Rite's first time to use Ditch Witch pipe bursting equipment, and the company was impressed by the unit's ability to do the job without affecting adjacent utilities and surface obstacles like trees and sidewalks. The Trench Rite crew was also surprised by the speed at which the PR95 replaced pipe. One 209-foot section required only two hours and 15 minutes, from the time contractors hooked up the cracking head and finished pulling the new pipe to the pit wall.
With the Ditch Witch PR95, Trench Rite was able to complete the job in a fraction of the time that traditional open—cut excavation would require, helping the village of Glen Ellyn avoid weeks of traffic problems and noise pollution.
The world's water and sewer infrastructure is deteriorating; American ingenuity, fortunately, is not. And Ditch Witch pipe bursting technology is one of the innovative and economical solutions we'll need to meet the monumental challenge of modernizing our subterranean highways.
