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Old 08-19-2019, 04:50 PM   #1
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This is where a driveway will be one day. This is the current water table level. I have had a soil engineer suggest to get someone to add fill to the front and work their way back, pushing the water with them. I have had grading companies say they want to wait for the area to dry. Problem is, I don't know that it will dry unless it stops raining for several weeks, and right now it rains every day.


I can pump the water to get it drier temporarily, but it will just fill back up by the next day. If I add fill, it will turn in to mud, at least until enough fill is added that the fill is above the water table permanently. And even then, the bottom layers of fill will be saturated and the whole thing probably won't be very stable long-term.


I see no other option than to just keep adding fill until some of it stays dry.
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Old 08-19-2019, 05:59 PM   #2
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Re: Add fill on top of groundwater?


Sure, you can do that, no problem. It's going to take an awful long time though because anything heavier than a single guy and a wheelbarrow is going to sink in there and get stuck and you will have an expensive tow bill to get it out again. Much better to follow the advice of the grading companies.
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Old 08-19-2019, 06:04 PM   #3
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Originally Posted by tmittelstaedt View Post
Sure, you can do that, no problem. It's going to take an awful long time though because anything heavier than a single guy and a wheelbarrow is going to sink in there and get stuck and you will have an expensive tow bill to get it out again. Much better to follow the advice of the grading companies.
I might be waiting forever since it rains every day.
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Old 08-19-2019, 06:35 PM   #4
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Re: Add fill on top of groundwater?


Ayuh,...... It needs to be graded to a lower spot, a hole dug there, then pump it out,.....

Dependin' on the lot, 'n size, a perimeter ditch might lower the water table, inside the perimeter ditch,....
It'll probably have to be fairly deep, to de-water the whole area,.....

Personally, like the guy lookin' at a house in a flood plain, I'd find somewhere else to build,.....
Yer lookin' at a life long misery,....
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Old 08-19-2019, 06:47 PM   #5
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Ayuh,...... It needs to be graded to a lower spot, a hole dug there, then pump it out,.....

Dependin' on the lot, 'n size, a perimeter ditch might lower the water table, inside the perimeter ditch,....
It'll probably have to be fairly deep, to de-water the whole area,.....

Personally, like the guy lookin' at a house in a flood plain, I'd find somewhere else to build,.....
Yer lookin' at a life long misery,....
There is a County stormwater ditch. I pumped some in there today, but I'm not sure if that's legal without a permit.

There are 100s of houses in this neighborhood already, including one just 300 feet west. The house pad location is higher than this, and has no standing water. Plus, I have to raise it another 3.5' to comply with the County lot grading plan. The wet area you see is the future driveway. What you're saying makes sense, but since there's 100s of other houses here, I think it should be possible.

This is not in a flood zone. There is a 100-year flood zone about a mile to the west, and there are even lots of houses built in that.
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Old 08-19-2019, 07:04 PM   #6
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Re: Add fill on top of groundwater?


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I might be waiting forever since it rains every day.
I could have sworn those are pines in the background, it didn't look like rainforest to me. You might need to wait until next year. Where is this?

I would not try putting dirt fill down on water. But you can drop scrap concrete and gravel on there. You will have to start from the road and work your way back and it will require a LOT of fill but eventually it will stabilize. Unless you have running water under it like a stream. If that's the case that area will never be stable unless you put a culvert in. What your soil engineer told you was basically the same thing. You could just try contacting the rock quarry in the area directly and buying the gravel and concrete scrap directly from them and using a little tiny rented dozer and doing it yourself. They won't want to take their trucks on that but they will dump at the side of the road where the driveway connects and you will have to push it down the driveway.

I am not surprised the grading companies don't want to touch it. There's no way they can estimate a job like this because you basically just have to keep throwing gravel and concrete scrap at it until it stops sinking.

There's lots of old-timey roads out there that run through swamps that were built like that. I live in Oregon and US26 West of the Tillamook turnoff is like that. It took them years and a heck of a lot of persistence throwing anything they could find that was hard scrap - rocks, gravel, concrete blocks, etc. etc. - into the swamp but eventually they got a causeway built that stopped sinking that the road runs on today. Ironically today if they tried that they wouldn't be allowed to do it since the greenies would scream wetlands destruction.

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Old 08-19-2019, 07:16 PM   #7
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Re: Add fill on top of groundwater?


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I could have sworn those are pines in the background, it didn't look like rainforest to me. You might need to wait until next year. Where is this?

I would not try putting dirt fill down on water. But you can drop scrap concrete and gravel on there. You will have to start from the road and work your way back and it will require a LOT of fill but eventually it will stabilize. Unless you have running water under it like a stream. If that's the case that area will never be stable unless you put a culvert in. What your soil engineer told you was basically the same thing. You could just try contacting the rock quarry in the area directly and buying the gravel and concrete scrap directly from them and using a little tiny rented dozer and doing it yourself. They won't want to take their trucks on that but they will dump at the side of the road where the driveway connects and you will have to push it down the driveway.

I am not surprised the grading companies don't want to touch it. There's no way they can estimate a job like this because you basically just have to keep throwing gravel and concrete scrap at it until it stops sinking.

There's lots of old-timey roads out there that run through swamps that were built like that. I live in Oregon and US26 West of the Tillamook turnoff is like that. It took them years and a heck of a lot of persistence throwing anything they could find that was hard scrap - rocks, gravel, concrete blocks, etc. etc. - into the swamp but eventually they got a causeway built that stopped sinking that the road runs on today. Ironically today if they tried that they wouldn't be allowed to do it since the greenies would scream wetlands destruction.

Ted

Okay so any kind of crushed rock is an option? This is a neighborhood just east of Orlando. There are $500,000+ houses all over this neighborhood.


And, yes, there is a culvert that will be installed about 250' onto the property. This is a very long driveway (310').


There is a river less than 2 miles to the west, and the 100-year flood zone is about a mile to the west.
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Old 08-19-2019, 08:02 PM   #8
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Re: Add fill on top of groundwater?


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Okay so any kind of crushed rock is an option? This is a neighborhood just east of Orlando. There are $500,000+ houses all over this neighborhood.

And, yes, there is a culvert that will be installed about 250' onto the property. This is a very long driveway (310').
Orlando is a special case. The entire state of Florida is barely a foot above the ocean it seems. If you ever fly over it and look down there is almost more water than dirt exposed. I don't believe that anyone has successfully figured out how to build a road in the soil there that's not the brute-force method of just dumping tons of gravel down.

This is where you need to contact the local quarry. (of course, there's no quarries in Florida, har har, but there's crushed rock dealers that buy from far away quarries) Certain sizes of crushed rock are used for different jobs. What you want is intended to lock together when it's compacted. You don't want the kind that is intended for drainage because that won't lock. The local dealer that has been supplying gravel for these kinds of projects is going to know what will work best in your area. There are also other quarry products such as gravel mixed with lime that when used will lock together in the presence of water. It's kind of like a concrete but not exactly concrete. Your local gravel dealers will know all this. Gravel isn't just little rocks it is pretty specific to an area and you need to get this info from the right local people not from the Internet. The locals also will be able to tell you how thick each layer needs to be for the best compaction and likely can point you to a place you can rent a small dozer and a gravel compactor from.

Scrap concrete is good but only if it's dropped down at the bottom layer. The problem is that it's not easy to get in quantity. Quarries want it so they can make crushed rock products from it. Scrap asphalt is also a problem because a lot of government jobs are now mandating a percentage be recycled asphalt and so the asphalt makers all want it. My gut feel is your going to have little choice but to go with compacted gravel or a gravel/lime product or both, one on top of the other.

I think that dirt fill would be a complete waste of time there. After a few years it would just flatten out and become the same level as all the rest of the dirt.
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Old 08-19-2019, 08:43 PM   #9
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Re: Add fill on top of groundwater?


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I think that dirt fill would be a complete waste of time there. After a few years it would just flatten out and become the same level as all the rest of the dirt.

What if there's a concrete driveway poured on top of it? What would happen to it over time?


All the grading companies have told me to wait until it stops raining every day (maybe October?) so that the water table lowers.


This kind of has me worried about the strength of the soil under the house, but there are 100s of houses already built here. So I guess it's possible.
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Old 08-19-2019, 09:50 PM   #10
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Re: Add fill on top of groundwater?


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What if there's a concrete driveway poured on top of it? What would happen to it over time?


All the grading companies have told me to wait until it stops raining every day (maybe October?) so that the water table lowers.


This kind of has me worried about the strength of the soil under the house, but there are 100s of houses already built here. So I guess it's possible.
If the concrete is poured WITHOUT rebar or other reinforcement you need at least 4 likely 6 feet of compacted gravel or it will crack. It is common to pour residential concrete driveways without any rebar or reinforcement with shallow 6" gravel bases (if you even get a gravel base many of them just pour right on to dirt) to save money because if it cracks most of the time it won't impact the functionality of the driveway. Same thing with sidewalks.

The FL building codes seem to require that if you put a concrete foundation on more than 12 inches of compacted gravel you have to have a geotechnical survey. My guess is that to avoid this expense most homebuilders there use a 12" compacted gravel base with concrete foundation poured on top of that and reinforcement mesh embedded in it. In my opinion this is asking for a crack later. That won't matter for leaks if they put in a raised area for the house pad because then the water in the soil won't flow up and into the house. But it might matter a lot if a corner of the slab cracks and has a weight bearing column on it. I don't know how much control you have over what your building there but if I were you I would push the contractor for a full rebar system maybe even epoxy coated if they aren't planning on doing that. It will be more costly but 30 years from now a corner of the garage won't be sinking and you won't have to get a foundation person to come out and jack it back up.

The key here is to spread out the load. A house may weigh 200,000 pounds but if it is on a 40x40 slab then it's only 125 pounds of weight on each square foot of soil. But that 200000 pounds is resting on maybe a dozen 4"x4" spots on that slab so if the soil is weak in any area, you get a large shear force on the concrete and it will crack and once it cracks if there is no rebar in it, it's disconnected from the rest of the slab and it will sink.

The mesh is good for keeping cracked concrete from separating but it will bend. Rebar will bend also but not unless you put a lot more force on it.
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Old 08-19-2019, 10:26 PM   #11
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Originally Posted by farmerjohn1324 View Post
What if there's a concrete driveway poured on top of it? What would happen to it over time?


All the grading companies have told me to wait until it stops raining every day (maybe October?) so that the water table lowers.


This kind of has me worried about the strength of the soil under the house, but there are 100s of houses already built here. So I guess it's possible.
If the concrete is poured WITHOUT rebar or other reinforcement you need at least 4 likely 6 feet of compacted gravel or it will crack. It is common to pour residential concrete driveways without any rebar or reinforcement with shallow 6" gravel bases (if you even get a gravel base many of them just pour right on to dirt) to save money because if it cracks most of the time it won't impact the functionality of the driveway. Same thing with sidewalks.

The FL building codes seem to require that if you put a concrete foundation on more than 12 inches of compacted gravel you have to have a geotechnical survey. My guess is that to avoid this expense most homebuilders there use a 12" compacted gravel base with concrete foundation poured on top of that and reinforcement mesh embedded in it. In my opinion this is asking for a crack later. That won't matter for leaks if they put in a raised area for the house pad because then the water in the soil won't flow up and into the house. But it might matter a lot if a corner of the slab cracks and has a weight bearing column on it. I don't know how much control you have over what your building there but if I were you I would push the contractor for a full rebar system maybe even epoxy coated if they aren't planning on doing that. It will be more costly but 30 years from now a corner of the garage won't be sinking and you won't have to get a foundation person to come out and jack it back up.

The key here is to spread out the load. A house may weigh 200,000 pounds but if it is on a 40x40 slab then it's only 125 pounds of weight on each square foot of soil. But that 200000 pounds is resting on maybe a dozen 4"x4" spots on that slab so if the soil is weak in any area, you get a large shear force on the concrete and it will crack and once it cracks if there is no rebar in it, it's disconnected from the rest of the slab and it will sink.

The mesh is good for keeping cracked concrete from separating but it will bend. Rebar will bend also but not unless you put a lot more force on it.
The house foundation will definitely have reinforcement. As for the driveway, I hadn't decided yet, but now I will sure to have reinforcement there as well.

But since the water table here gets so high, I was worried about the ability to compact it or anything on top of it. But I suppose I'll take the advice of the soil engineer and the fact that there 100s of other houses already built in this location as evidence that it will be okay.

The foundation won't be on gravel. It will be on compacted subsoil. The home foundation and driveway will not be poured at the same time.
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Old 08-20-2019, 09:54 AM   #12
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Re: Add fill on top of groundwater?


If you just fill on top of that crap you're just gonna get the fill material pumping. Any surface you put in will crack, whether it's concrete or asphalt. The only thing I could suggest that might work would be to put in a bridging layer of stone, wrapped in geotextile.

I don't know how you're gonna get compacted subsoil for your house foundation, though, if the soil there is anything like this.
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Old 08-20-2019, 10:39 AM   #13
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I don't know how you're gonna get compacted subsoil for your house foundation, though, if the soil there is anything like this.
Do you mean that you don't know if I could locate any? Or do you mean that if I used it, my house would sink?
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Old 08-20-2019, 01:24 PM   #14
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Re: Add fill on top of groundwater?


As your soil Engineer to check on using a Polymer for stabilization of your drive way area. Also look at the use of Lime stone & Lime mixed into the soil.
In my area they use a lot of what is called ROC ( product for making cement ) I used it on my back drive in a very wet area worked great.
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Old 08-21-2019, 09:00 AM   #15
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Re: Add fill on top of groundwater?


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Do you mean that you don't know if I could locate any? Or do you mean that if I used it, my house would sink?
I mean, given the apparent saturation of your site, I doubt you'd find any stable ground. At least not without doing a massive amount of work.
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