Thursday, April 24, 2008

What to do with all of this DIRT???

How time flies! It has been another busy month, so busy that I have not been able to update this blog until now!  Here is a look at what's been happening:

After the Livingroom and cellar walls were poured, I had the waterproofing crew out again to do these new walls. It was tight work, especially around the chimney, but they did a fine job.

By the end of the day they had wrapped all the walls from the livingroom north wall,


...around the back...


...all the way around to what will be a planter outside of the cellar door.


After the waterproofing was up, we set the french drains and hauled gravel up from the street one bucket at a time. The french drain needed to have about 8" of gravel on top, then a sheet of plastic was laid to prevent the slurry from clogging the drain.


After the drain was inspected, I pumped a slurry mix of concrete behind some of the walls. Slurry is a very soupy concrete, with a lower percentage of cement in it so it can't be used as structural concrete, but it makes a very good backfill, especially when there is a "surcharged load", meaning that a footing is so close to the backfill that it is putting pressure on the backfill. It also is a very efficient way of backfilling these hard to access areas because it can be quickly pumped in with no compaction inspections required!

Here is the slurry behind the cellar that supports the kitchen footing:


This is behind the livingroom. This is not an area with a surcharged load, but it is a lot of area to fill, and the 3 feet of slurry got me started nicely! In the picture below I have already started placing dirt on top of the slurry.


Here is the first layer of compacted fill on the south side of the cellar.


Before I could backfill on the north side of the house, an HVAC duct had to be placed. This was very difficult work, involving some custom metalwork to fit into the tight space!

This duct brings the heating and AC into the back part of the livingroom. It was easier to run the duct outside than to run it under the slab and footing.


This duct runs from the 2 vent openings on the north wall, around the chimney and down through a hoile into the side of the garage where one of the HVAC units will be located.


After the duct is custom fitted into the space, all seams are sealed, and it is attached to the ground using stakes and brackets. This keeps the duct from floating up when the concrete is placed.


The process of backfilling with dirt is time consuming but important. After about 6" of dirt is placed and raked level, it is moistened and mechanically compacted, then the next 6" is added.

This process is repeated until 2 feet has been compacted, then it is tested by a representative of the Soil Engineer. Chris from Technosoil is shown below with the compaction testing device. First, a pointed rod is driven about 2' into the ground then removed, leaving a hole. Then this device is placed over the hole and a rod with a small amount of radioactive material is lowered into the hole.


Somehow, the machine is able to sense the density of the soil, and based on numbers gathered from a lab test of my soil, it gives a percentage of density. The required minimum density is 90%, and as the picture below shows, we were consistently getting between 93 and 94%!


Here's a look at the compaction process:



As the backfill got higher, a temporary dam was built to hold back the compacted fill. As soon as I build the planter wall, I will remove the dam and compact behind it.

The wall behind the livingroom now has about 4' of compacted fill. we had to maintain a 45 degree slope on the end of the fill so we could continue to walk up to the top with buckets!


The fill on the south side of the cellar is almost level with the slurry. There is now about 6 feet of compacted dirt in there!



I also took time this month to remove all of the forming and shoring. For the first time, the entire entry door opening was visible, and it's tall!


The livingroom is finally visible too, as this view shows looking toward the foyer:

Looking into the livingroom from the foyer:

Here is the arch detail over the music alcove in the livingroom:

Here is the cellar area without shoring:




Next, we get ready to pour the kitchen footings and slab!