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327ft Guyed Tower Converted From Concrete Foundation to Helical Piles
Saves client big on time, budget, and CO2 emissions
Client
Bell MTS
Project
327ft Guyed Communication Tower
Pile Details
● 219mm [8-5/8"] Ø shaft, 8.2mm [0.322"] thick wall, 660mm [26"] double helix at 25mm [1"] thickness● 219mm [8-5/8"] Ø shaft, 13mm [0.5"] thick wall, 660mm [26"] double helix at 32mm [1-1/4"] thickness
Foundation Loads
● 14kN [3.1kips] Shear ● 1,846.6kN [415kips] Axial
Anchor Loads
● 563.3kN [126.6kips] Uplift● 609.4kN [137kips] Axial
Problem
VersaPile was engaged prior to construction by Bell MTS to support a 99.8m [327ft] communications guyed tower to bring 5G cellular voice and data service to the surrounding community of Lac Du Bonnet, Manitoba.
The geotechnical investigation conducted by Wood encountered auger refusal at 11.4m [37'-6"ft] depth in till consisting of N values in excess of 30 with sloughing and seepage observed from 2.6m to 3.1m as well as 10.4m to 10.7m.
The original foundation solution was a concrete foundation consisting of a 6ft x 38ft caisson for the centre tower and three massive deadman anchor blocks with 26ft anchor channels.
The project was to be completed in the summer of 2022 following record breaking levels of precipitation in the area. This meant that the site, which already experienced sloughing and seepage, was very saturated.
To complete the project with concrete meant additional site preparation, rig matting as well as major de-watering efforts. In addition to these potentially significant price escalations, concrete foundation contractors in the area were behind in scheduling due to the consistent rain and already saturated soils in the area.
Bell MTS, who had never built a 100m (327ft) guyed tower on anything but a concrete foundation, brought the project to VersaPile Inc. to consider helical piles.
Solution
VersaPile engaged Cory Goulet P.Eng. of Pilisk Geostructural to analyze soils and tower design to engineer an alternative foundation solution using helical piles.
The solution was to replace the large concrete caisson under the tower with a 4 pile grouping of helical piles installed on opposing 10 degree batters. The massive concrete deadmen anchors were replaced each with a single helical pile installed on a 42.8 degree batter.
VersaPile, with a team of project engineers, installed 7 helical piles with pile caps site welded by Reg Dumont of DC Custom Welding. The project was completed successfully despite the challenging marsh like conditions.
The centre piles were installed using VersaPile's CASE CX350 with a Digga UD300 anchor drive. More difficult guy-anchor locations were accessed by the lighter John Deere 290G with an Eskridge D1400 anchor drive.
Conclusion
The Client was very satisfied with the results and would no longer be reluctant to construct tall guyed towers on helical piles.
They realized savings in excess of $225,000 to the budget and avoided many potential cost escalations related to digging, drilling and working in sloughing and seeping soils.
The timeline for the project was reduced by at least 2 weeks (and likely longer) as water would have surely slowed down typical production times.
There was also a huge savings in carbon emissions on the project.
The conversion of a concrete foundation to a helical pile foundation resulted in a 98.3% reduction in CO2 emissions. This means that 60 helical pile foundations could be installed to equal the same amount of GHG emissions as the originally proposed concrete foundation.
Contact Us
Address
2046 Van Gorp Road
Ile Des Chenes, MBCanada R0A 0T0
Hours
Monday - Friday8:00 - 17:00
Contact
(234) 567-8900moc.elipasrev%40olleh