Typically a dock or boathouse rests on steel poles which are pounded into the lakes until they meet total refusal. This means a few things but often it means huge dollars to drive the poles deep enough to reach refusal.
Recently Postech Winnipeg was contacted by a cottage owner who in getting started pounding in steel driven piles found that refusal was at 80 feet!
Because a steel driven pile has to be installed to refusal to be effective, this meant a very costly foundation for the customer. So how are Postech’s helical screw piles different and more effective than a steel driven pile? Great question:
- Screw piles are made with a one or more helicals (blades set at a pitch) which create bearing capacity in any nearly any soil, including lakes. Steel driven piles, like a screw pile include smaller diameter shafts but without a helical they do not achieve much of any bearing capacity until they reach hard pan or bed rock.
- The helicals on a screw pile anchor the pile within the soil, creating a strong resting place. Steel driven piles will likely sink if not driven to total refusal. Think about hitting a nail vs. screw which are installed several inches into a piece of wood but not all the way; the nail will proceed easily and depending on the amount of force applied by the hammer, the screw may not proceed at all.
- Helical screw piles are installed using low impact equipment which does not create vibration and that operates at a low noise level. Steel driven screw piles are pounded into the ground using heavy machinery and installation creates heavy vibrations and is very loud. Obviously, when installing piles in a sensitive environment such as a lake in cottage country, low impact solutions are ideal.
The best time of the year to install piles for a dock or boathouse is in the winter when installations can be performed from a solid ice surface. The challenge of course is creating a hole in the ice large enough to allow the installation of a helical screw pile. This is where steel driven piles offer an advantage; without a helical they only require a small hole which is easily drilled with an ice auger.
To install the test screw pile with a 16 inch helical we needed a larger hole than what a typical ice auger can drill. The solution was to use an ice auger to drill 4 corner holes and then a chainsaw to essentially connect the dots. The excavator broke the pile through the last couple inches of ice without much effort. Total time to get a 16″ X 16″ hole in just over 2 feet of ice = 20 minutes.
Are you looking for an alternative foundation solution which could save you money? Perhaps you are concerned about using a loud and high impact foundation in a sensitive environment? Either way, contact Stan Higgins, Independent Owner of Postech Winnipeg for a free, no-obligation review of you project to see if helical screw piles might be an answer. Call toll-free 1-855-474-5464 or in Winnipeg 204-793-0653 or visit www.manitobascrewpiles.ca.