In November 2022, Brownline Canada provided its steering services to successfully complete an HDD crossing under the Kiskatinaw River in British Columbia. The length of the crossing and the variety in soil conditions made this a highly challenging project.
The aim of the crossing was to install a 42” gas pipeline as part of the Groundbirch Mainline Loop (Sunrise Section), a 24 km / 15 mi long pipeline route in British Columbia. Trenchless installation was required to cross the winding Kiskatinaw River, and a 1197 m / 3927 ft horizontal directional drill was designed to accomplish this.
The crossing was carried out by The Crossing Group using the intersect technique with casings installed at both entry holes. The intersect was planned at the southwest side of the river, roughly 60 m / 200 ft below the surface of the valley.
Challenging soil conditions
Soil investigations revealed a considerable variety in soil types, including clay, silt, sand, gravel and shale. This variation added to the complexity of the project. The Drillguide Gyro Steering Tool was used to survey the progress of the pilot bore with the highest accuracy in all soil layers.
The intersect method greatly reduced the risk of inadvertent fluid releases, but it was still an important risk factor. This is why Brownline Canada used the Pressure-While-Drilling module inside the Drillguide GST to monitor the downhole pressures. Constant monitoring further reduced the risk of frac-outs.
Radar used to complete the intersect
Inside the planned intersect zone, the Radar add-on was activated to measure the separation between the two boreholes: 1.33 m (4.36 ft) vertically and only 2 cm (just under an inch) laterally. With these accurate measurements, a plan could be made to connect the two holes smoothly to ensure that reaming and pullback would be successful.
After the intersect was completed, our client The Crossing Group was able to continue with the rest of their operations, knowing that they could rely on the accuracy of the pilot hole surveys.
In 2023, an article covering this HDD crossing was featured in Trenchless Technology magazine, available through the link below.