Week5-6C: Foundations

We've got "mud in the hole"!!!!

Yesterday we poured 21 cubic yards of concrete (that’s two full trucks and 1 yard from a third) and marked the end of the pile phase of our foundations. From start to finish it took us 1 week of prep, inspections, and hard work. Next we’ll be working on the grade beams which will support the retaining walls of the house.

You can see the steel pipe sticking out of the fresh concrete. This is supporting the entire weight of the cage as the concrete cures. It will be removed after the pour is complete.

On Wednesday we had our inspection of the cages with our building inspector. The process of pouring a concrete foundation involves several inspections from three different entities other than the contractor. They are:

1) The soils engineer approves the bottoms of the borings and prepares a field report that shows the depths.

2) A LA City licensed deputy inspector continuously checks the rebar ties and cages during their fabrication to insure they are correct size and configuration.

3) The Structural engineer checks the cages when they are out of the ground to insure they are correct size and configuration.

4) The building inspector checks the cages in the ground to make sure that the steel is not touching the soils and that the other three entities have signed off on the work.

5) Pour concrete and collect samples to be tested by the deputy inspector.

We flew through all of our inspections thanks to the hard work of Garcia Masonry. They’re work is exemplary and it got us off on the right foot with the city inspector.

A rebar cage being lifted into position.
Prepping the rebar cage for installation.

I showed up on Monday morning to find a crane in the middle of the street. Since the piles are so large, we had to arrange for a crane service to lower them in. The operator from Garcia Crane Service (no relation to Garcia Masonry) nimbly maneuvered his boom in between the temporary power pole line and the main high-voltage line above the street, clearing the latter by a hair. The whole operation took about 2 hours with a crew of 4 on the ground to guide the pile cages into place. Since the borings are not perfectly straight the cages have to be pushed and pulled in order to get them into position. Before the crane releases the pile a 3’ length of 4” steel pipe is tucked into the area where the cage “daylights”. This is in order to hang the cage. Normally you would use 3” blocks of concrete called “dobies” that keep the steel off of the dirt. However, because of the extreme weight we had to hang them instead.

A team of workers ties the rebar on a stand at the top of the hill.

The cages are then rolled down the hill into position.

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.

Week 3C-4C: Grading

It’s hard to tell in the photos but he is carving a giant “Z” down the hillside. If the road is too steep then the drill rig could slide down and fall over the debris barrier and into the street below.

Mark made the whole thing look flawless, and after hearing some of his stories this job is one of the less dangerous ones he’s worked on. He used to be a logger in Montana and worked the sides of Mountains. Most of his stories contain the phrase “…one mistake and you’re over the side of a 100’-0” cliff…”. It was great to have him on the job. His experience made the severity of the hillside seem much less dangerous than it is. We couldn’t have done it without him.

Week 2C-3C: Grading

If you’ve been wondering why there have been no updates as of late it’s because we’ve been moving at a breakneck pace over at the jobsite.

Since the last entry almost a month ago the dirt has been flying and we’ve managed to smoothly excavate the hillside in order to provide the pad for the house. We had some small delays in the beginning, but we’re still ahead of schedule and are now into the foundation phase of the project.

The first week began with a delay because our grading inspector wanted an OSHA (Occupational Safety and Health Administration) permit for the job since our excavations were over 5’-0” in height and our grading sub found out that you can no longer pull job-specific excavation permits so he had file for his annual permit. OSHA regulates excavations like the one on our job in order to insure worker safety. While safety is most certainly a critical part of any project CAL OSHA is notoriously slow (glacial to be exact) in issuing permits and they are equally notorious for being indecisive at what is required for a specific job. It’s true bureaucracy in action and it’s probably why so many projects ignore the permit requirement. Our delays with OSHA killed about a week, but our inspector came back and we happily handed him the annual permit. Moral of the story: If your project has excavations over 5’-0” or the permit requirement comes up in plan check, my advice is to make sure your grading sub has the annual permit in place to avoid delays.

The debris barrier is constructed of 3” dia. ½” steel pipe driven into the bedrock. The cribbing as it’s known is just sheets of ¾” plywood. As you’ll see we managed to make this temporary shoring work for us and it supported our spoils from grading with no problems.