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New Pipeline Construction Product Allows for Simple Installation of Standard PVC Pipe in Houston HDD Project
One of the challenges facing municipalities in the replacement of failing pipelines is that many of these pipelines are located in developed and populated areas.
Open-cut replacement can disrupt or damage other existing utilities and surrounding property. Horizontal directional drilling (HDD) techniques have offered ways to avoid some of these issues but these require special pipe and/or joining methods. Still, HDD is becoming more and more common because of the reduced damage to property, decreased inconveniences for local property owners and avoidance of other installed utilities.
A recent project for the city of Houston required replacement of failing eight-inch and 12-inch asbestos-cement pipes utilizing trenchless installation methods. There were a number of fitting connections that were required along the route and the contractor for the project chose to make use of standard AWWA C900 PVC pipe with a new product – the Mega-Stop bell protection system from EBAA Iron Inc. This product enables the installer to push standard bell and spigot PVC pipe through bored or cased holes without the danger associated with over-belling the joints. The device attaches very simply to the spigot of each piece of pipe and is comprised of a fixed stop ring and an expansion retention spring to maintain joint flexibility.
Utilizing the Mega-Stop product with standard PVC pipe enabled the contractor to save as much as 40 percent in material costs and provided a simple installation process.
The bid for this project, designed by Lockwood, Andrews & Newnam Inc. of Houston, was awarded to BRH-Garver, a Houston based contracting firm. This contractor specializes in complex civil projects for public and private clients.
The primary focus of this project involved the relocation of a large diameter water line and updating of a treatment plant facility. However, in the process, 2,500 feet of failing eight-inch and 580-feet of failing12-inch asbestos cement distribution lines in the vicinity were to be replaced as well. Because this project took place in a fully developed and mature residential neighborhood, the replacement of the distribution lines was designed to be performed with trenchless pipe installation. Currently there are several items listed in the city of Houston Approved Water Products List that are advertised for use in HDD projects. Included in this list is spline and groove PVC pipe, restrained integral bell PVC pipe and restrained integral bell ductile iron pipe.