Week 4C: Pile Excavation

This week concluded our grading operations for the time being. We’re still on schedule and actually finished our piles early!

The rig operators from Roy Brothers were wonderful to work with. As with any job having an experienced crew makes things go smoother. These guys brought in a “tight-access” hillside rig in order to get down our 5’-0” road.

5’-0” sounds like a lot, but it’s not when the rig is 4’-0” wide and needs a huge turnaround area.

During the drilling operations the engineer from Technosoils, our Soils Engineering firm on the project, came out to do routine inspections of our depths. Due to depth of bedrock we had some piles that were 10’-0” over what we expected, thus increasing the cost. According to the pile schedule (see attached) our deepest pile is 28’-0” into the ground with a minimum of 18’-0” of embedment into solid bedrock! It’s the kind of hole that gives you the creeps just looking at it.

The rig operators have a routine for each hole. First they set up the rig with a 24” auger bit and start drilling. Every few feet they pull the auger out and throw a piece of plywood over the hole to keep the spoils from going back in and then spin the auger as one guy pulls the dirt off with a shovel. It’s backbreaking work and it is amazing at how efficient the workers are at keeping things moving quickly-especially in such tight quarters. After they hit bedrock the operators have to attach a rock coring bit to the rig in order to break through the solid bedrock. This takes a long time and they have to switch over to the auger every so often to clean out the hole.

After the pile is done, the engineer checks and approves the depth based on the start of bedrock and then the rig is moved to the next hole. To give you an idea of the timetable this is how we did.

Day 1: 3 piles dug with an average depth of 24’-0”.

Day 2: 2 piles dug with an average depth of 20’-0” . We hit a boulder field on the 5^th boring and it took all day to finish it. The machine was pulling out chunks of boulders the size of beach balls.

Day 3: 3 piles dug with an average depth of 20’-0”. Things went pretty quick and we wrapped up at 2pm- still ahead of schedule.

Mark, the grading operator, had to keep redoing the road in order to allow the drill rig room to move. It was a good thing we had him there because the time we saved was worth the extra cost. If you have access to machines, there is no point in having guys hand dig things- it takes forever and can be dangerous.

Finally after the last pile was done we moved the rig off the site and Mark moved some more dirt around to set things up for the concrete sub and we called it quits for the day. Things are going smoothly and were going to spend the next week bending rebar and prepping our pile cages for inspection and insertion late next week.