We are getting busier and working in new areas where we are encountering different site conditions and installation challenges. On a recent job along the shores of Daniels Lake north of Nikiski, we encountered some very rocky soils.
The owner had requested us to install 6 or our P3 posts for a small cabin foundation. He was attracted to our system because of the low impact installation and the fact that the cabin site was quite far from the road area; making delivery of concrete almost impossible for him. Before the installation, the owner discovered a large amount of rocks present when he was doing some site work.
Upon arrival, we did a visual site inspection and were pessimistic that we would be able to complete the installation without some excavation. We were unable to install our initial post less than 2′ deep because the rock layer was so thick and compact. We have yet to encounter so many rocks. After we exhausted all of our normal installation tricks for rocky soils, we confirmed that the job required some excavation.
Enter the skidsteer. Due to the site conditions, narrow worksite and proximity to the lake we decided to use a skidsteer with a 12″ auger instead of a back hoe or mini excavator.
We started drilling the pilot holes with the skidsteer to a depth of about 4-5 feet. As you can see from the photo below, the ground was full of rocks.
After using the skidsteer to do the 6 pilot holes we were able to install our posts with much less trouble. Since we only used the skidsteer to loosen the rocks in the first 4-5 feet, we were able to install the posts another foot or so into excellent soil giving us optimal bearing capacity. After getting the posts set plumb, we backfilled the holes, compacting them as we went.