I’m considering helping a friend excavate a basement & driveway for his new house, and before I agree to do so I’d like to read about excavation techniques so I know when I’m extending beyond my abilities.
My experience level with heavy equipment is in landscaping and light road construction, so lots of time and experience in skid steers, and to a lesser extent time in excavators, backhoes and front-end loaders. I’ve got limited experience using laser levels and other standard surveying tools.
The soil is probably the biggest challenge; there seems to be a lot of soft sandstone all over the property, and in fact there could be a significant lense of it between 4-8 feet down. Not sure how difficult it will be to dig through that with a toothed bucket. We’re estimating an 800 yard removal of soil for the foundation, and another
700 yards for the driveway(The house will be built into a hill with a garage underneath).
The house he’d like to build has a 42′ X 32′ foundation footprint, he’ll be using an engineered prestressed foundation wall system by Superior Walls (www.superiorwalls.com) which will rest on a bed of clean crushed rock per the manufacturer’s specs.
I’d only be digging the hole. and I’m having trouble finding a good guide to excavation that would allow me to forsee problems and perhaps conclude that he should choose a different site(Because of the significant grades and sandstone), or find a pro to do it because of the difficulty and complexity of the task.
Any suggestions of guides or pitfalls would be welcome.
Thanks,
Joel
Replies
800 yds? You sure? If the house is 32' into the hill, that'd take a 100% slope hill to give up that much. And mean a 32' tall excavated back wall. That's without any slope to it, which would be incredibly dangerous.
I'm not easily frightened, but that'd do it. Take a look at the attached slope chart and go back and measure again. Generally I wouldn't recommend a novice to mess with more than 25% slope. I cut my driveway across a considerably steeper hill, but no where near that deep.
If you really have to go that deep, there's no telling what you'll find. Maybe Jimmy Hoffa! The rock you described wouldn't be much challenge for my old smallish (8 ton) track loader. Hope you're thinking truck to haul it off or reposition it.
Edit: forgot to welcome you to BT!
PAHS Designer/Builder- Bury it!
Edited 6/10/2005 3:11 pm ET by VaTom
800 yards. Yeah, that's out of whack. I'm not sure what he was thinking there. I just recalculated it some, but here's the layout: The lot is on a corner, has about a 10-12 foot vertical rise virtually straight up from the street. On one side the rise is a crumbling sandstone drop, and on the other, a steep short hill. Aside from the rise and the hill to the street, the lot is flat and relatively level on top.So, the basement of the house is basically a straight forward hole in the ground, not really built into the side of a hill, and the house plan has a basement drive-in two car garage under it, so we have to cut in a driveway to get there. There will be retaining walls on both sides of the driveway. The city code requires the grade of the driveway not exceed 11%. If we go with 10%, and nearest corner of the garage front is located 40 feet from the street(Does not face the street), then we can only have 4 feet of rise on the driveway.The foundation walls will be 10' tall panels, which I'd expect to show 12-18" above ground, but that's not my call. I'm just the buddy with equipment experience and a CDL. And yes, there will be a helluva lot of trucking, but a big house 2 blocks away is in need of 1800 yards of fill(So I'm told), so we wouldn't put many miles on a rented truck.Back to the calculation of the volume, assuming 5 feet of overdig on each side of the hole, and 10 feet of depth(maybe more to add compactible substrate) the hole would be 10 X 47 X 37, and dividing that by 27 cubic ft/yd, we get 644 yards for the basement, and for the driveway(Far harder for me to estimate), maybe 30 X 50 X 4ft average depth / 27 Cu. Ft/yd = 178 cu. yards, for a total of around 822 yards. Still, seems like a substantial job for the DIY.I was wondering about the size of the equipment he should look at obtaining. You said an 8 ton tractor(backhoe); would that be like ####416, 420 or 430 Cat?Thanks again for the response, and thanks for the welcome.
Whew! Although I am a tad disappointed that you weren't off on a huge adventure scraping away the side of a mountain. My driveway rises 400', BTW. I learned to run a track loader cutting a new driveway to replace the horrible one a "professional" sold me ($20k).
You're right. A very substantial job for DIY, but certainly not out of reach. A backhoe isn't the answer. I was talking track loader, like my 8 ton 933. My other large tractor is a Cat 944 at 23000 lbs. Odd numbers are track, even, rubber tire. Both of these are antiques, according to the Cat folks. I have little trackhoe experience, but that'd work if you got a big one. My guess is you'd do better with loader bucket controls.
You're comfortable with skid-steer so track shouldn't be much of a reach. They're also incredibly stable, especially compared to skid-steer. And now I notice Wisconsin. Which tells me nothing, unfortunately. A lot of your option is controlled by your rental possibilities, assuming you're not intending to purchase.
A 9-10' excavation shouldn't be a problem. Still a lot of dirt/stone to remove. Make sure your tractor reach matches the load height of your truck. I've got one coming up where a GC wanted me to load a standard 20 ton truck with my smallest tractor (a compact I use with a small hoe). I'd need a 4' ramp. Bad idea. You won't have the opportunity to have the tractor near the edge of the hole, which is the most dangerous place. Depending on who visits, or your soil, you may have to slope the sides considerably. Stockpiling dirt to backfill will be a bit of a problem unless you have a ramp to the flat ground.
After struggling with a too-steep driveway for years, I concluded that 15% was a little too steep (the professional road builder gave me 30%). 10% will be fine.
Obviously I know nothing about you, but I'd favorably consider the opportunity to make a few bucks and learn a new skill. Don't assume you'll be fast. I assume this isn't a bid situation. Caution can make this work out well. Notice I'm not suggesting that your involvement is necessarily cheaper than hiring it out.
Good luck. Keep us posted.PAHS Designer/Builder- Bury it!