Two months late, but I finally got the building pad cleared, filled, and packed! The weather had not helped me the last two months.
Per the recommendation of The Owner-Builder Book, I sent emails to 10 different companies to get multiple quotes. Two responded, and I had one quote from a friend of a neighbor. One was for $2,300, one for $3,000, and one for $4,300. Obviously, I went with the cheapest quote. The middle bid wasn't planning on using a dozer, so I preferred the lower one anyway.
I staked it out myself, as mine is pretty simple with a near-perfect circle for the foundation. I used spray paint to mark the soil where I wanted the actual foundation, and then placed stakes 4.5' from each corner (11 corners on my circle). This accounts for the load bearing of the sand and allows for a little error in the process. I think I was told 4-5' and I just went with the middle of that.
I bought the cheapest laser level and tripod from Lowe's and shot my own levels. First I figured out how high my laser beam was by comparing it the pin placed on a telephone pole by my surveyors (my reference point). Next I verified my level by shooting some points on my driveway and comparing it with my survey map. With my children holding the stakes and a yardstick (with their back to me to avoid hurting their eyes with the laser) I marked off the final height of the fill I wanted. Then I held a sheet of paper and spray-painted red above that. That allowed a clearly visible red marker for each of 11 stakes. Then I did the same for a stake at the center of the plot. Then I measured from the red down to the soil and added 4" for the amount of expected topsoil (a neighbor showed me how to dig a test hole to check the amount). Then I computed an average of all those points, which gave me just under two feet.
Since my foundation is a circle, I used the area of a circle (pi*radius squared) times the depth of 2' which resulted in 4,578 cubic feet, which, when divided by 27, gives the value of 170 cubic yards. You also have to figure 15% compaction which gives a final need of just over 195 cubic yards. My excavation crew can deliver just over 12 cubic yards of sand in one dump truck, so I needed 16 truckloads. I figured we would place 14 and then recheck.
It turns out we needed exactly 16, so I was happy with my math. My excavator also seemed happy with my red stakes, as it was easily visible from his dozer. Next time I think I'll spraypaint all sides of the stakes instead of just the front, so I can see them from the back as well as the front.
First we pulled up one small Christmas-tree-sized cedar tree, scraped the topsoil, and made a berm (he could do this without moving the stakes). Since part of the circle was only about 4" above grade and the other side was almost 2', the deeper side got the majority of the topsoil for the berm. Actually the bulldozer did an okay job and I used a shovel and wheelbarrow to place it closer/more accurately.
When finished I put grass seed on the berm, raked it in, watered it well, and then put four bales of straw over it to hopefully encourage some grass growth to prevent erosion.
The hope is that the weather over the next five months will compact the sand really well, hopefully minimizing cracks in the slab, which will be the finished floor (the plan anyway, as my wife may not like acid-etched concrete). This should be much cheaper than carpet or wood flooring and will help me get my Certificate of Occupancy earlier (so far my construction plan is money-limited instead of time-limited, but that may change also). I also wanted the rain to weather the pad and avoid paying for a compacting roller. The sand looked very high quality and had been tested to be excellent as structural fill.
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