Dirt Moving Trenching beneath an overhang

[ShenandoahJoe]

I have a 2-level cottage set into a hillside. I'm getting water in the basement, so it's time to put in some drainage pipe. I have to dig a trench along the wall, but that wall is under the middle of the top floor, so I can't get in there with any normal trenching equipment. (Marked with an "X" on the end view below.) There's about 18 inches of air between the floor and the top of the dirt. I have this vague idea that I could drag a bucket on some long chains, and dig out the dirt from the ends. Kind of like a 3PH dirt scoop, but turned backwards and half as big. Would this work? Have you ever heard of anyone who makes such a thing?

 

[MossRoad]

If the bucket bites in, it will act like an anchor and just start going deeper. You'll have to figure out a way to control depth of cut.

What about trenching further out and making a French drain?

 

[Everhard]

Few thoughts:
1: Where's the water originally coming from? If you can answer that can you stop it reaching that middle foundation, then you don't need to drain along that portion of the foundation.
2: Is there drainage at the footing level of the foundation. (proper weeping tile along the perimeter in particular is there any along the high side exterior wall?)
3: If there isn't I'd put in the weeping tile around the house, that along with making sure your eves are draining away and downhill from the foundation should in my mind stop the water from coming in where it is based on that little diagram.

But bear in mind I'm basing my opinion just on just that little diagram. The bigger picture would be more helpful, there might be better solutions to your problem.

E.

 

[100 td]

Fix the cause, not the symptom.
Stop the water before it gets to where it is now.
This would probably mean putting in a larger/deeper rubble drain around the house higher up, and of course upsetting all the landscaping/decking etc.
But in the long run, a far better solution.

That said, miners used winches and digging buckets on cables for following small veins, can't think what they're called, they would be suitable but there will be a lot of work in it I expect. I think (get an engineers report, not my thoughts) you really need to go down deeper than the foundation, and ensure proper piping/geotextile and removal of water as any water that gets there will be sitting and weaken the foundation material. Far better to stop the water before it gets there.
EDIT: Everhard types faster than me!

 

[skyhook]

I have to agree with the others, installing a drain system where your "X" is will only invite more water, weakening your center foundation and soil around it. You need to figure out a way to "divert" the water from the cottage. I'm guessing that your problem is not only surface water from the hill but also veins of water beneath that are finding their way in your "space" and converging on your second foundation, if thats the case, you may have to dig deep, behind the cottage and this may not be feasible for you, I don't know, how far or big of a hill do you have behind the cottage.

 

[jenkinsph]

I am working on a similar job this coming week where the water is running under the house. As the other posters have suggested it is better to divert the water before it gets to the house. I will be working on diversions that start 150 ft up the hill with the last one being about 10 ft from the house. I will have three drainage swales to divert the water away from the last French drain. That puts less water in front of the drain next to the house to deal with. Slower water speed for less erosion damage.

 

[ShenandoahJoe]

I like that answer because it'll be easier to do part of the job. The rest is complicated by a boulder that's as wide as the middle third of the cottage. It sticks up about 8" above the ground, and goes down farther than I've cared to dig. Any suggestions about how to handle that?

The reason I think he boulder doesn't go all the way to the foundation wall, so I can put a drain at the X, is that groundhogs dig burrows along there.

 

[dieselcrawler]

Hire the ground hogs.

 

[arkydog]

bucket sound good if only choose. to keep bucket from getting hung up and flying toward is to put a chain and rope opposite way you are pulling with someone pulling chain, bucket and rope back to set up for another scoop

 

[ShenandoahJoe]

Crawler, if I could figure out a way to make groundhogs useful, I'd spend all my time enjoying the adoration of my fellow Virginians and I wouldn't worry about a little water in the basement.

 

[countrybumpkin]

You could fab up a homebuilt Dragline, that you could pull under the overhang.

 

[Ed of all trades]

Not sure of your setup from the pic but I have dug a basement under an existing house with an excavator and tracked bobcat. It was not as fast as if it were just out in the open but I did do it. I agree to fix the water problem up the hill but I would also fix it where it comes into the house. Ed

 

[jenkinsph]

I like that answer because it'll be easier to do part of the job. The rest is complicated by a boulder that's as wide as the middle third of the cottage. It sticks up about 8" above the ground, and goes down farther than I've cared to dig. Any suggestions about how to handle that?

The reason I think he boulder doesn't go all the way to the foundation wall, so I can put a drain at the X, is that groundhogs dig burrows along there.

If the boulder is that big and goes into the ground far enough then tie onto each side if it with a French drain. The boulder itself can stop the water above it but you need a way to drain the water away from it.

 

[ShenandoahJoe]

"Dragline"! I knew there must be a word. Thanks!

 

[ray66v]

I have operated a dragline, and as Moss said, you need a way to control how deep the bucket goes.

A dragline has two cables, one that pulls the bucket toward the machine, and one from above that limits the depth it can reach. You need both. And, you can't do that in 18 inches of space.

Without the upper cable, the cutting edge of the bucket will turn down, and bury the bucket so deep, you won't be able to pull it through.

I am not a big fan of no dig, interior basement drainage systems. But this job may be the perfect candidate for it.

 

[jenkinsph]

I have operated a dragline, and as Moss said, you need a way to control how deep the bucket goes.

A dragline has two cables, one that pulls the bucket toward the machine, and one from above that limits the depth it can reach. You need both. And, you can't do that in 18 inches of space.

Without the upper cable, the cutting edge of the bucket will turn down, and bury the bucket so deep, you won't be able to pull it through.

I am not a big fan of no dig, interior basement drainage systems. But this job may be the perfect candidate for it.

That or hire a company to horizontal bore that can pull in a perforated pipe. There are a lot more companies available to do this type work now than in the past so it is more competitively priced than years ago.

 

[ray66v]

That or hire a company to horizontal bore that can pull in a perforated pipe. There are a lot more companies available to do this type work now than in the past so it is more competitively priced than years ago.

I would not be comfortable with that. Without a properly prepared bed of washed stone, you could still be in deep water.

I have seen the existing stone bed harden to the point that it had to be broken up with a pneumatic chipping hammer. The water was not getting through it. But, it sure found it's way into the basement.

 

[jenkinsph]

I would not be comfortable with that. Without a properly prepared bed of washed stone, you could still be in deep water.

I have seen the existing stone bed harden to the point that it had to be broken up with a pneumatic chipping hammer. The water was not getting through it. But, it sure found it's way into the basement.

A percolation test of the OP's soil would show whether it is feasible or not. Not all sols are the same and I did recommend diverting the water above the house too. In these situations you do what is feasible If the OP installs a French drain that is slightly lower in the rear of the house than the downhill side of the foundation he will stop the large portion of the water infiltration. This drain should run around the perimeter of the house and make the foundation in a manner of speaking an island. If the water is coming straight up he will still have problems. But in my experience it is a good well founded 95% solution.

 

[drizler]

Personally I would exhaust all options to route the water away from there before I got into messing around digging deep next to the foundation Where exactly is it coming in from when you have a big dumper? The hill, the house roof mainly, it all adds up. If it's surface run odd heading down the hill you can dig deep enough to bury some of that 4" field drain. It's cheap by the 50' roll. Orient it slits up and give it just enough slope to send the water elsewhere. At the end bury a 55 gallon plastic drum full OD the rocks you dug out of the ground digging. Cut a hole upp near the top where the pipe meets it and stick it in then bury. Instead of dirt you can use crushed stone or decorative rocks, tiny ones , to fill the shallow trench in. Cheaper, crushed topped with the pretty stuff.
We did that this spring for my buddies house. The town had removed a sewer years back so all the upslope water came right to him making the basement a swamp. We also dug swallow trench and shunted the roof water way out 25' To smaller dry wells . It worked like a charm.
The thing is if you can stop the water before it gets to the house you don't have to unearth the whole foundation. Oh so much easier:thumbsup:

 

[ray66v]

A percolation test of the OP's soil would show whether it is feasible or not. Not all sols are the same and I did recommend diverting the water above the house too. In these situations you do what is feasible If the OP installs a French drain that is slightly lower in the rear of the house than the downhill side of the foundation he will stop the large portion of the water infiltration. This drain should run around the perimeter of the house and make the foundation in a manner of speaking an island. If the water is coming straight up he will still have problems. But in my experience it is a good well founded 95% solution.

I would of course, be all for improving drainage around the house, and keeping the water away to start with. That goes without saying.

French drains work perfectly, when you really don't need them. But, once the ground is saturated, and it rains for a week straight, they can fill, and they become worthless.

If the drain doesn't run to daylight, I can never really sleep good.