ENMAX NE Stoney Trail trenchless crossing
Innovative Pipeline Crossings was selected by ENMAX to install 180m of 48” continuously welded steel pipe underneath Stoney Trail N.E. with general contractor,
RB Sommerville. This pipeline would bring additional electrical power onto the Calgary grid from an outlying Enmax power plant. The project marked IPC’s first-ever application of the direct pipe trenchless technology, and the first use of this technology in Calgary.
Direct pipe was chosen as the ideal method of installation for this project for a number of reasons. There were several on-site obstacles present including overhead
power lines and limited Transportation Utility Corridor access which made it not as cost effective or as feasible for other trenchless techniques, such as the HDD method.
Many challenges were encountered throughout the project, including unfamiliar soil conditions, extreme weather fluctuation, and difficulty keeping fluid lines and equipment from freezing in extreme cold and wind. These obstacles made for very challenging ground and working conditions, however, the project was completed successfully, safely, and in a shorter time frame than the more common HDD method.
Due to the time of year, unique ground conditions on the site, and the first-time application of this technology, a number of challenges were encountered during installation.
- On-site obstacles – In and around the drilling site there were many power lines. Close proximity to the Stoney Trail high traffic roadway meant there was limited Transportation Utility Corridor access.
- Fluids and heating – Cold weather meant additional precautions needed to be taken to keep fluid lines and equipment from freezing. At one point, the
site had to be shut down for safety due to extreme winter weather.
- Weather – The project was completed under extreme wind and white-out weather conditions, with a swing of over 50° in temperature, from plus 10°C to minus 42°C
- Soil and ground conditions – Heavy clay presented unique drilling challenges
To reduce the impact of the given obstacles, several precautions were taken:
Surrounding power lines and traffic were avoided by using the direct pipe method which had a shorter pipe crossing length and depth as well as no necessary use of boom cranes. A back-up generator was brought on-site to ensure that the pumps and heating systems remained running in the cold weather (500 kW of power).
Overall, IPC completed the project successfully with several observable benefits compared to the traditional HDD method. The Direct Pipe method provided a shorter pipe crossing length (155m vs. 450m) and a shallower pipe depth (5m vs. 25m). The method used less bentonite, fuel and water and exhibited a minimal impact on surrounding environment and traffic. Lastly, there were no need for buoyancy systems, or boom cranes when IPC installed the pipeline.
The end results were reduced costs, minimal environmental impact, and an improved project schedule compared to conventional methods.