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Compaction question

chroniekon

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Apr 1, 2011
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357
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Albany, Or
I'm getting ready to add a shed onto the back side of my shop. Some would call it a lean-to. I had put some rock down this last spring in the same area because I had a new well drilled and it was needed for getting his equipment in and out. A base of 3" minus about 6" thick was put down after removing the top 6" or so of sod. After the well driller finished I smoothed out the ruts best I could and had another 6" or so of 3/4 minus put on.
Yesterday I went down to the County office to get a building permit and they want to see a compaction report on the fill I put in. The county official said 95% compaction. Can I just back my backhoe back and forth on the area (it weights about 13,000 lbs) or am I going to need to rent something made for this purpose? It's an area 20' by 50'. Also, how do I find out who does compaction reports and what kind of money should I expect to pay? Thanks, Chris
 
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joispoi

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Connecticut
Are you planning on building directly on top of the fill that you put in, or will you excavate for the foundation?

A soils lab will perform the density test for you. Prices will vary depending on the area, but I would expect $300-500.
 

chroniekon

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It's going to be a pole barn type structure with the poles set on a 6" concrete pad in the bottom of a 4' deep hole. The fill will only be the gravel floor of the structure. The county's reasoning is (wait for it) in case I ever sell, and the new buyer wants to build on top of it, he will be able to. At this point it seems easier to just do what he wants and move on.
 

Scrub Puller

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Yair . . . We have this sort of B/S over here too. Its not the problem of the present owner what the next owner wants to do . . . he just might have to dig it out and start again all over.

Cheers
 

buckfever

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southwest pa
Don't know what the codes are like in your area. Around here you are going to have to dig down 3 feet below finished grade. Then compact the soil in one foot lifts. The reason for this is so that you have a uniform fill that will settle equaly.

So if your final post depth is 4 feet you will have to undercut down 7 feet and fill and pack back up to inside slab finish.

I don't think your back-hoe is heavy enough, might have to rent a roller. For a building your size I would go with a 66" or there abouts size roller.
 

AustinM

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Feb 16, 2011
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wyoming
Where I live and work you can get a moisture density curve (proctor) for $175 then when they come out to take the actual test (with a nuclear guage) it's
$20/ea. That depends on how far you are from the lab though because that price includes travel time. Barring any unusual circumstance, I would say you could get the required testing for less than $300, even if they had to take several compaction tests.

Unless you have pretty wet soil that is visibly pumping or you know for some other reason it won't make 95%, I would have the tester come out and take a sample of the material for his proctor, ask him his opinion of the material and maybe try it with your backhoe (with a loaded bucket). He is going to sample the same material no matter what you roll it with and if you can get it with your backhoe, great. If not, your only out the money it cost for him to come out and take the actual compaction tests.

I hope that helps and isn't too confusing.
 

AustinM

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wyoming
The quote I received for the $20 compaction tests was on a project about 10 city blocks from the lab and it's a pretty big job so that price is based on volume of tests too, so a more accurate cost for what you are looking at is probably more like $40/each.
 

Greg

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All this for a pole building addition? They can't be serious can they? On many commerical site prep jobs I have done around here test rolling with a loaded dump truck is specified and is sufficient. Soils engineers don't get called on those jobs unless things get more complicated and we all want someone to blame if things don't come out right.
 

CM1995

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I am with Greg that seems extravagant but if the Inspector requires it, then there is no sense bitching about it.:rolleyes:

First find a local geotechnical company and discuss pricing for your proctor and testing. They will need a soil sample to determine density and optimum moisture. They need the information from the soil you will be using to determine the information to put into the nuke tester. Don't get hung up on this terminology, that's what the testing company's job is. All you really need to know is how much they are going to charge you.;)

Second, your backhoe will compact just fine, it will take more time than a compactor but personally I wouldn't rent anything. I am a firm believer in using what you have to get the job done. In fact a backhoe with a loaded bucket will find the soft spots after running over the area a few times, that a compactor or a tracked machine will float over.

How much fill did you put in again? You said you put some crushed stone down after the sod was removed. Have you placed a signification amount of fill previously? What I am getting at is if the area is virgin soil that you have just put down 6" or so of stone over, then you may not even need any compaction tests. If that is the case all it may require is a discussion with the building official and maybe a site visit. Give us a little more information about the history of the area you will be building on.
 

chroniekon

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Albany, Or
Thanks guys for all the comments. A little more history. My first visit to get a building permit was back in April. It was denied because the area has recently been declared to be in the 100 year flood plane by FEMA. (you start to see where this is going already, right?) There is a process one can go through if you dispute that you are in this flood zone. I was living here when we had our last 100 year flood in 1996 so I know where the high water mark is give or take a few inches. I hired a surveyor to come in an shoot the elevations and he filled out the proper forms to file with the county and with FEMA. Also, in late April I had to put in a new well. The well's location is such, that the rock I had to bring in to accommodate the 25 ton well drilling rig, is in the same location I'm wanting to build my shed on. So I removed the top 6" of sod down to good undisturbed soil and put back in 6" of 3" minus crushed rock. The well driller came in and did his thing, and I then added another 6" of 3/4 minus crushed rock on top of the 3" rock.
It turns out the one end of my proposed building IS in the flood plane and by adding this rock for the well drilling rig, that is considered fill. The fill I put in brings the elevation of the site above the flood zone by a couple of inches. And to add fill to a designated flood area you need a permit (which I didn't have) so now the County wants this compaction report on this portion of the fill that was put over the flood zone area, about 20' X 20'.
 
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Cat is ALL

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Canada
So if it is a 6" lift you need to test 4" deep. I'm not sure if the permit guy needs just one test or so many tests per square feet. Depending on how far away your lab is, I would dig a couple holes down to where the 3" minus starts to fill a sample bag and then drive it into the lab. It would most likely be cheaper. The first thing you should do is get a hold of a lab and tell them what you're doing and to give you some instruction. I'm not sure if your permit needs proof but on jobs that I've done you need a sieve test (to determine if you're material is in spec) and a proctor before they can do any density tests. Depending on the material and optimum moisture I doubt a backhoe would make densities but stranger things have happened. Last year I did a job and the geo-technical firms quote for density tests was $80 000 and we had to make 98%, you could lay rubber on the gravel it was that hard and it would still not pass, but on the other hand I've been on jobs where there are obvious soft spots and they'd pass 98%. I personally would rent a small packer to make sure that the ground is hard but thats just one mans opinion.

Then again if its 3/4" crushed rock good luck, the permit guys find it easy to just ask I guess.
 

buckfever

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southwest pa
All this work for a pool building is crazy. Insted of going through all this could you build a building on the virgin ground and put a shed roof over the fill area? This way when you apply for a permit you can say the whole structure is on virgin ground. Then when asked about the shed roof you can say "no thats not part of the stucture it's just a roof to keep weather off my stuff";)
 

CM1995

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Thanks guys for all the comments. A little more history. My first visit to get a building permit was back in April. It was denied because the area has recently been declared to be in the 100 year flood plane by FEMA. (you start to see where this is going already, right?) There is a process one can go through if you dispute that you are in this flood zone.

OK now I see, you have bigger issues than just the County Building Dept. I have dealt with FEMA flood zones back in the late '90's. We had a 6 unit building of town homes that were in the flood zone. Built the foundations up, hired a surveyor to certify the new elevations and IIRC, it took a good 6 months for the paperwork to go through the channels. I am sure the rules have changed since then.:rolleyes: Back then there was flood zones and flood ways. Flood zones you could fill and certify elevations with FEMA and be OK. Flood ways were off limits and you could not fill or build in them. I don't know if that has changed or not.

Have you received your paperwork back from FEMA?

Depending on the material and optimum moisture I doubt a backhoe would make densities but stranger things have happened.

It will.;) Compaction is a function of weight, the thickness of the lift, manipulation and the time it takes to reach density. You can compact it with one of those hand tampers HD sells if you have the time and patience to do it, as it would require a tremendous amount of physical labor and thin lifts.:rolleyes: The Romans used sheep to compact their roads and those roads are still here today.
 

chroniekon

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Buckfever, That's exactly what this building is going to be. The poles will be set in virgin soil. The rock that is there will be the floor of the shed. Nothing structural will be on top of the rock. It's just going to be an open shed on the back side of my shop with a gravel floor so I can get some farm equipment out of the weather. Before this is over I think it may just be cheaper to buy new farm equipment...for sure easier!
 

chroniekon

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Albany, Or
CM, Sounds like it's still the same, at least as far as flood zones and flood ways. I have both on my property, fortunately the area in question is flood zone. I took the FEMA paperwork down to the County office with me when I went to get the building permit as they have to sign off on it. And he won't sign off until he approves of the compaction report.
 

chroniekon

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Albany, Or
What's frustrating in all of this is the old county maps had the 100 year high water mark right. FEMA got involved in 2010 and changed all the datums. According to the surveyor that came out, sea level is now 3.32 feet higher than it used to be. The corresponding high water mark was supposed to be adjusted by the same amount, but wasn't. My hat's off to you guys that deal with this stuff every day.
 
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Reel hip

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I feel your pain. Are you staying there for a while? I would wait a few months. Then do it the way you feel is best and keep the inspectors out of it. The county inspectors seem to justify their job by coming up with things to keep them busy, after all it's just a lean-too. Best of luck! Doug
 

CM1995

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I feel your pain. Are you staying there for a while? I would wait a few months. Then do it the way you feel is best and keep the inspectors out of it. The county inspectors seem to justify their job by coming up with things to keep them busy, after all it's just a lean-too. Best of luck! Doug

It's easier to ask for forgiveness than ask for permission.:cool2
 

Reel hip

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It's easier to ask for forgiveness than ask for permission.:cool2
Right. If it was a jobsite then it needs to be done by the book to satisfy inspectors and customers because that is the cost of doing buisness. But my house has sheds with 220 power and water and concrete, that while it could have passed inspections, I chose to keep the county out of my backyard. Some may not agree to this and that is your right. But he said they are requiring him to do this because of the next (possable owner) may try to build on it.
 

Scrub Puller

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Gladstone Queensland Australia
Yair . . . Reel hip. I don't see your point mate . . . or the counties point. That's the next owners problem not chroniekon's

The next owner here might want to bring a ten ton load of gravel in . . . well he'll have to upgrade my bridge and culverts, I use a two ton dump or a trailer behind my ute.

Cheers.
 
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