Page 18 - Industrial Plants

confirmed the loads being consistently within the
calculated acceptable limits.

Conclusions

The Dry Gulch Crossing was a critical activity of the
Trans Mountain Expansion Project, and the pipeline
pullback posed a significant challenge for Bonatti/
Kiewit since their involvement in Spread 5B.
Considering the exceptional length and project
available work space, the engineering, planning, and
setting up of the Dry Gulch HDD pullback required
extraordinary effort and multidisciplinary coordination
from late-2021 to mid-2023 to match high safety and
quality standards, minimize environmental impact, and
optimize the execution schedule. In particular, feasibility
studies, detailed design, and construction engineering
was developed from Q4-2021 to Q1-2023, including
different stages of stress analysis, in static and dynamic
conditions, and 3D modelling of the rollers to size the
Figure 5 - Pullback execution equipment required for string management and pipeline
anchoring.

“Meticulous planning and design
allowed the identification of the
most reliable and efficient solution
for the Dry Gulch HDD pullback,
executed safely and smoothly in only
52 hours, with eight cranes and 17
Bonatti SAFE T-Rex sidebooms - a
major accomplishment for TMEP and
Bonatti, due to compliance, execution
and challenging schedule constraints

The engineered pullback required three pipeline
strings (1,100 metres, 380 metres, and 380 metres in
length), to traverse across 900 metres of rollers
Figures 6 and 7 - Pullback – Falls Lake Road crossing & overbreak section across rocky terrain with significant horizontal
detail direction and vertical elevation changes, while
crossing two watercourses and one road and being
eight cranes and the 17 side booms required for lifted at about 15 metres elevation for the 200 metres
pipeline string management during pullback and the long over-break section. Meanwhile, other civil works
installation of the HDPE buoyancy control pipe inside required to prepare the rollers were completed in the
the NPS 36-inch pipeline strings. second half of 2022, and the pipeline strings had
been welded, hydrotested, and positioned on the
The pullback had eventually started on October 18, rollers from Q1-2023 to Q3-2023.
2023, and was smoothly and safely completed in In conclusion, meticulous planning and design allowed
about 52 hours, 30 of which had been required for the identification of the most reliable and efficient
the two tie-ins and with an average pulling rate solution for the Dry Gulch HDD pullback. The pullback
ranging from 80 metres/hour to 120 metres/hour, was executed safely and smoothly in only 52 hours,
exceeding the best estimate scenario. The maximum with eight cranes and 17 Bonatti SAFE T-Rex
pulling force was within the expected range, and sidebooms. This was a major accomplishment for
also the continuous monitoring of the vertical and TMEP and Bonatti due to the compliance, execution
lateral loads on the cranes and side booms and challenging schedule constraints.

IndustrIal Plants - May 2024
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