water line under footings

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farmkid

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I'm considering building an addition to my house, but have run into something that might or might not be an issue. Two questions:

1. Building what I have in mind puts the corner of the addition close to my well, only about 4 feet from the corner. I'm not really comfortable with that, but I'm not sure what the problem would be. Is that a bad idea? Should I make it a little smaller or shift it to get more space between the house and the well?

2. Where I plan to build it puts the footing right over the water line from the well to the house. The water line is 1" copper about 5 to 6 feet down under the driveway. The current driveway slopes up ~18 inches, which I will level out as part of the project. Going down another 30" to the frost line puts the footings only 1 or 2 feet above the water line. At the current size I have in mind for the addition, the water line will be under the addition, about 1-2 feet inside the front wall. If I move it back a couple feet to get more space from the well, the water line will be right about under the footing running the full width of the addition. Should I be concerned about that?
 

Sparky617

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Not sure about the well, but your water line would be in disturbed ground (fill dirt) and you'll likely need to take your footing below the water line to reach undisturbed ground. Unless the backfill around your water line was compacted. This is highly unlikely. They probably just backfilled and let it settle. I don't think having your water line going through the foundation would be a problem, mine does, as do probably everyone's.
 

farmkid

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That ground was last disturbed over 40 years ago and has been under a driveway ever since. I kind of figured it would be pretty well settled by now. Is that a faulty assumption?

If I put the foundation there, the line wouldn't go through the foundation; it would be 1-2 feet below it.
 

Sparky617

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That ground was last disturbed over 40 years ago and has been under a driveway ever since. I kind of figured it would be pretty well settled by now. Is that a faulty assumption?

If I put the foundation there, the line wouldn't go through the foundation; it would be 1-2 feet below it.
It is hard to tell whether the ground would be compacted enough at that point. A lot will depend on the soil structure. I'd probably rather have it come through the foundation than under it. Are you doing a slab or a crawlspace?
 

ajaynejr

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In order to lay the pipe you would have to disturb the land up against the pipe.

Have a few inches of fine sand on all 4 sides of the pipe, well tamped, together with tamping any disturbed ground nearby that the foundation will rest on, and the pipe should be fine.

Then, should the foundation settle, the sand against the pipe will squish to conform to the pipe without crushing the pipe.
 

farmkid

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It is hard to tell whether the ground would be compacted enough at that point. A lot will depend on the soil structure. I'd probably rather have it come through the foundation than under it. Are you doing a slab or a crawlspace?
The bottom floor is a garage, so it's a slab. It won't go through the foundation unless I dig it up and raise it. I don't plan to touch the water line or dig down that far at all for any reason. If the foundation being above the line is a problem, I'll just move the addition to avoid it. Shifting the addition a few feet to the back and having it in a not quite as ideal spot is still preferable to digging up the water line and making changes there.
 

Sparky617

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When they test your footer holes they'll tell you. Around here the inspection for the footers checks the soil at the bottom of the footer before they are poured. The inspector takes a rod and tries to push it into the soil. If it sinks in too much you have to go deeper to undisturbed soil. Here our footers only need to be 12" down, I built screened porch and the back yard was all fill. I had to rent a Dingo with a 30" auger to put the post footers in. I went down two feet and still had fill.
 

tomtheelder2020

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That ground was last disturbed over 40 years ago and has been under a driveway ever since. I kind of figured it would be pretty well settled by now. Is that a faulty assumption?
It does not matter how old the fill is. Once it reaches a stable condition, all soil, natural or fill, MIGHT experience additional consolidation if exposed to increased load or increased moisture content. Fill soil pushed into place will consolidate only as much as necessary to support the overlying load (i.e. top of fill consolidates way less than bottom). For granular soil, the dryer it starts the less it will consolidate - until it gets wetter (the first time, after that wet/dry can cycle without effect). Expansive soils are a different story.

Consolidation happens when soil grains are pushed closer together. The more grain-to-grain contact there is the less a given amount of load is able to consolidate the soil further - that is why fill is compacted before adding a load on top and why concrete is vibrated if it will bear heavy loads.
 

68bucks

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In my location code says you have to be 10' from the well head. We are working on addition plans and have received a variance from the county to build 5' from the we'll on 2 sides. We had to submit the plans and the health department board had to review and approve it. I have not run into a water line that deep from a well before. Every place we have ever owned the line runs through the foundation not under the footer.
 
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