Screw Piles in Cochrane, AB

Below the surface in Cochrane

In Cochrane, forget what you know about Calgary clay. The town lies in the Bow valley at the foot of Big Hill, and climbing west toward the foothills the soft lake-bed clay is replaced by dense glacial till full of gravel and cobbles, with bedrock getting nearer the surface the further you go. For a structure that is a good thing — this is strong soil that carries load well. The catch is that driving a screw pile into it takes a lot more effort.

That effort is what really matters on a Cochrane job. Tight till calls for more installation torque than an equal load would in Calgary, frequently a stouter shaft as well, and it brings a real chance of refusal — the helix hits a cobble or boulder and cannot advance before reaching design depth. In this soil that is an ordinary event, not a botched install. What we do about it is honest and limited: shift the pile within the allowed tolerance, switch to a different pile setup, or tell you plainly that a screw pile does not belong at that location.

Cochrane also climbs a long way from bottom to top, so no single ground condition covers it. Near the Bow there is river alluvium and water closer to the surface; higher up the slope it is till and cobble. Two homes in the same town can pose entirely different challenges, so before we offer any specifics we want to know how far up the hill the property is.

The projects we see locally

Slopes shape nearly every project. On walkout and side-hill lots the far end of a deck frame can stand two or three storeys above the ground, pile lengths differ a lot within one structure, and there are sideways loads a deck on flat ground never has to handle. Just getting a machine into a steep back yard is a challenge, and the rig small enough to fit is not necessarily able to deliver the torque this till demands — both are checked before a quote goes out.

Heading toward Highway 22 and the acreages, the work shifts to cabins, shops and post-frame buildings on open, exposed land. West of town, wind becomes a design load in itself: a tall, light building on a bare foothills site needs recorded uplift resistance, and helical screw piles take tension directly instead of relying on a heavy block of concrete to keep the structure down.