Static Pipe Bursting & PVC Team Up For An Industry First In Utah
Water is a highly valued commodity in Utah. The state is second only to Nevada for the dubious honor of the least amount of annual rainfall at a meager 13 inches of precipitation per year. Irrigation and water management has been an essential part of life in this section of North America for hundreds of years. Simple irrigation canals have been discovered in this area that date back to prehistoric times, well before the discovery of the “ New World .” While the practice of water management has advanced with technology, the concepts behind it remain very much the same: conserve and manage the water supply while serving the people, agriculture and industry.
That management includes providing and maintaining the proper infrastructure to handle the job. That also means replacing it when it becomes old, deteriorated or outdated. That was the situation recently in Ogden, UT.
The Weber, Box Elder Conservation District is the irrigation water supplier for Ogden City residents. Most of the district’s existing infrastructure consists of steel main lines, many over 50 years old that are in need of replacement. According to Claude H. Nix Construction/Jasco, Inc. Pipe Bursting Division Manager Jay Garrett, replacing those lines is not always easy. He said, “Often those mains run through areas that make replacement very difficult. The line that was replaced in this project was an 8-inch line running through a narrow park strip. The line was over 60 years old and less than 5 feet deep. Our job was to replace the 8-inch steel with a new 8-inch PVC line. The Weber, Box Elder Conservation District accepted our bid to replace this line using pipe bursting to see how it would perform in a tight, landscaped area.”
Garrett turned to pipe bursting specialist Jim Moore from trenchless equipment manufacturer TT Technologies, Aurora, Ill for technical support. He said, “There were important aspects to this project, one of which was the choice of product pipe. This was the first pipe bursting project that utilized CertainTeed Certa-Lok™ restrained-joint PVC. It is significant step for pipe bursting and for the product pipe industry. It expands the capabilities of both products and gives municipalities and project owners another level of choice when it comes to replacing deteriorated infrastructure.”
A Grundoburst 400G static pipe bursting system from TT Technologies was chosen to burst and replace the existing steel irrigation mains.
Over the past 30 years, Claude H. Nix Construction/Jasco, Inc. (CNC) has grown as the leader in providing solutions to difficult piping projects in Utah, Southern Idaho, and Southwestern Wyoming .
CNC President Stephanie Nix said, “We focus on investigating new technology and using the best so we have the right tool for the job. We provide our customers with fair and complete bids, and work independently and professionally once we are on the job. We are in business to provide our customers with quality installation of underground water, sewer and storm drain pipelines using the best construction technology and knowledge available.”
According to Moore, product pipe material selection can sometimes be a volatile subject. He said, “It has been a stumbling block. Many utilities are so invested in certain pipe materials that it is almost impossible for them to consider other piping materials. While there is a high level of familiarity with the application of HDPE pipe in pipe bursting, there is still considerable interest in other pipe materials by owners, engineers and contractors.
Pipe manufacturers, like CertainTeed, are working diligently with pipe bursting equipment developers and manufacturers to find real world ways to adapt their pipe products to the rigors of pipe bursting installations. It takes the extensive experience of these parties to find suitable ways to install these pipes through the pipe bursting process. It is very much a collaborative effort,
like the project in Ogden.”
Steve Gross, Director of Marketing for CertainTeed’s Pipe Group, believed Certa-Lok Yelomine was an excellent choice for this pipe bursting application. He said, “Yelomine pipe is made of modified polyvinyl chloride, which provides improved mechanical properties, higher pressure ratings and better flow performance than other thermoplastic materials. Plus, it will allow the district to stick to a proven long-lasting material that works seamlessly with existing infrastructure.” Gross also noted that Yelomine in particular is easy for contractors to work with due to its unique spline-locking system that eliminates the need for fusion equipment, saving time and money, and the need to string-out hundreds of feet of preassembled pipe, which may not fit in congested areas.
On The Job
With all of the components of the project in place, work was ready to begin on the irrigation pipeline. Because of the lack of rainfall, many areas employ a dual water system as a means of conservation. With a dual system, one system is dedicated to potable water, while the other, separate system, carries water that is used for irrigation, as well as commercial and industrial applications. Moore said, “This type of secondary non-potable water system is typical of the area. Basically residents use the system for caring for their lawn and gardens during the summer. It’s also used for agricultural irrigation. In the winter the lines are drained and shut off. This particular steel line, which was used for irrigation, was in pretty bad shape.”
Garrett said, “There were over 63 point repairs in the 1000 feet that was to be replaced. The preparation was time consuming due to the number of service connections to the homes in the area. Most were put in after the irrigation line and some were in direct contact with the old pipe. There were 4 tees that needed to be cut into the new line, so a pit was set up at these each of these locations. Approximately 1200 lineal feet of the 1300 total lineal feet was installed using pipe bursting. Two road crossings were constructed by directional drilling and 60 lineal feet was installed open cut.”
CNC crews divided the 1200-lf project into four bursting runs. Not only did crews contend with tight working conditions, but traffic was also a concern because of an elementary school a few blocks away from the work site. Because these irrigation lines are drained and shut off in the winter to prevent freezing, the lines are set only a few feet below the surface. Launch and exit pits were typically 4 feet wide by 10 feet long by 3 1/2 feet deep.
According to Garrett, crews also saved space by utilizing the PVC pipe. She said, “We used Yelomine Restrained Joint PVC pipe which meant that we didn’t have to contend with 450 feet of fused pipe crossing driveways and streets while we were bursting. That helped with space issues. We also needed to make sure to secure the potholes well because of the close proximity to the school. And we paid very close attention to the adjacent utilities.”
According to Moore, the CNC crews handled the adversity well. He said, “Probably the biggest challenge the CNC crew faced on the project was with other water lines and gas lines that in certain areas were literally sitting right on top of the steel main we were replacing. In some instances a loop was placed on the line to provide more room for bursting and in other cases we slowed the bursting process down and monitored the area closely to make sure we could make it through. This is a huge advantage to the static bursting process, the ability to manage your speed.”
Once the launch and exit pits were established and the adjacent utilities and services potholed, the Grundoburst hydraulic pulling unit was placed in the exit pit. The crew then rodded the existing line with the Grundoburst’s Quicklock bursting rods. Once at the launch pit , the roller cutting blades, bursting head, expander and first section of PVC were attached, and pullback was ready to begin.
Moore said the bladed rollers are key to pipe bursting steel. He said, “During the static bursting process, specially designed bladed rollers are pulled through an existing line by a hydraulically powered bursting unit. As the bladed rollers are pulled through, they split the host pipe. An expander attached to the rollers forces the fragmented pipe into the surrounding soil while simultaneously pulling in the new pipe.
The bladed roller configuration is an essential part of the Grundoburst’s success. The specially designed bladed rollers actually split the host pipe instead of ripping or tearing it. This is a clean process and prevents potential damage to the product pipe.”
Average bursting times for the CNC crew ranged between an hour and an hour and a half per 300- to 400-ft runs. After a bursting run was completed, crews would set to work tying back in the services to the new PVC main and restoring the launch and exit pits.
Everyone involved considered the project a great success. Moore said, “There were several challenges on this project and several successes. It was very difficult to get around those tight utilities. But it was exciting to be able to use a new product pipe in the restrained joint PVC. In the end it was great job all the way around by the Nix Construction crew.”
Underground Construction, July 2006