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-   -   Found an underground stream while digging a garage pad today. What to do? (https://www.contractortalk.com/f62/found-underground-stream-while-digging-garage-pad-today-what-do-414887/)

Sam @ PWE 01-15-2019 12:20 AM

Found an underground stream while digging a garage pad today. What to do?
 
Hey guys,

Customer of mine is planning to put up a garage in the next few months. He asked me to level out a 40x40 area to get it prepped...easy enough.

I showed up today with a skid steer and got to work stripping the sod off. As soon I got through the sod I made a 90* turn and sank the skid to it's belly :rolleyes:. The mud got worse and worse and thankfully I was able to tow the machine out with my pickup. While trying to dig myself out I dug down with the bucket realized there was water flowing through the ground about 18" below grade. It's been dry here for a few days so something tells me this underground stream will continue until it really dries up this summer. Customer's yard now looks like a war zone because I was only able to dig about 1/3rd of the pad before it was too soupy to work in. From what I can tell this underground stream seems to run right through the middle of the future garage.

Do you guys have any ideas on what to do here? He's talking about moving the garage over about 10 feet, but that'll still put part of the garage in the wet area. I'm thinking of dumping some drain rock in the mud to firm it up so I can finish grading - but I'm not sure if that's going to be solid enough to build on. I might try to consult with a civil engineer, but I know my customer wouldn't like that extra expense. The customer wants to keep the job cheap, but I want to make sure it's done right and I definitely need to fix this quagmire sooner than later.

Last thought: I'm tearing out a concrete driveway at another job this week and it crossed my mind to throw some broken up concrete in the mix to firm things up. While I know that would do the job for me, I seriously doubt it would be okay to build on.

Any help is appreciated! I didn't take any pictures because it currently looks like hell.

Jay hole 01-15-2019 01:04 AM

Hire an engineer

griz 01-15-2019 01:25 AM

This will be an expensive fix.

For liability reasons you need an engineer and likely a soils report.

Your contract cover unknown/unforseens.

Get out while you can if the owner doesn't want to do it right.

builditguy 01-15-2019 07:08 AM

Quote:

Originally Posted by griz (Post 7455231)
This will be an expensive fix.

For liability reasons you need an engineer and likely a soils report.

Your contract cover unknown/unforseens.

Get out while you can if the owner doesn't want to do it right.

This is the right path.

TimNJ 01-15-2019 07:15 AM

Trench it where the water is and lay some perforated pipe and stone and drain it away.
Farmers have been doing that in their fields here forever.

Big Johnson 01-15-2019 07:20 AM

Quote:

Originally Posted by TimNJ (Post 7455281)
Trench it where the water is and lay some perforated pipe and stone and drain it away.
Farmers have been doing that in their fields here forever.

One thing for a farm field, whole other for a garage.

Inner10 01-15-2019 08:11 AM

That's easy, hire architect Frank Lloyd Wright, he's an expert on building on top of running water.

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Big Johnson 01-15-2019 08:14 AM

Quote:

Originally Posted by Inner10 (Post 7455327)
That's easy, hire architect Frank Lloyd Wright, he's an expert on building on top of running water.

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I donít think heís available.

Mordekyle 01-15-2019 09:18 AM

Water feature


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hdavis 01-15-2019 09:51 AM

I wouldn't put a slab on grade in that location.

It can be done and get through the warrantee period. Get an engineer, peel off the loam, put in big rock, smaller rock, mix, gravel, compact as you go. Get the footer above the problem grade.

tgeb 01-15-2019 10:02 AM

A dewatering pit could be pretty handy in this situation.

I run into different unforeseen conditions all the time, and when something like this pops up, I inform the owner or GC and tell them the correct path forward is to employ an engineer to design a plan of action that will work for the long run.

I'm smart enough to make recommendations, but also smart enough to know that I don't want the liability for the building shifting on my shoulders.

TimNJ 01-15-2019 12:24 PM

Quote:

Originally Posted by Big Johnson (Post 7455283)
One thing for a farm field, whole other for a garage.

It's a garage slab, not house with a full basement.

What is the footing depth requirement?

cedarboarder 01-15-2019 12:43 PM

http://www.vancouversun.com/touch/ne...190/story.html

long story short the drilling company doing geo thermal hit a pressurized aquifer, panics and pulled the drill. Once the water started pouring out he jumped on the next flight to his home country.
the owners of the house had to give the property to the city or face even more liability

To stop the water from flooding the homes around the site the city put in a giant pump and 10 inch pipes to the river about 2 kms away.

Talk about a **** up.



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hdavis 01-15-2019 12:50 PM

That's awesome!

cedarboarder 01-15-2019 01:17 PM

https://vancouversun.com/news/local-...aquifer-breach
More updated link. total cost was 10 million to repair. I was working for the City at the time and we put up sand bags all down the block to divert the water just incase.

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SmallTownGuy 01-15-2019 05:32 PM

Quote:

The customer wants to keep the job cheap, but I want to make sure it's done right and I definitely need to fix this quagmire sooner than later.
Are garages on pontoons common there?
Just asking...

knucklehead 01-15-2019 07:58 PM

Figure out where the water is coming from.
What do you mean underground stream?
That water is coming from somewhere.

TimNJ 01-15-2019 08:33 PM

Quote:

Originally Posted by cedarboarder (Post 7455481)
http://www.vancouversun.com/touch/ne...190/story.html

long story short the drilling company doing geo thermal hit a pressurized aquifer, panics and pulled the drill. Once the water started pouring out he jumped on the next flight to his home country.
the owners of the house had to give the property to the city or face even more liability

To stop the water from flooding the homes around the site the city put in a giant pump and 10 inch pipes to the river about 2 kms away.

Talk about a **** up.



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That reminds me of a house I worked on back in the mid '80's. There was a group of houses right at the foot of the rte 72 bridge to Long Beach Island. About 5' from the bulkhead of the bay was a 1" galvanized pipe sticking up out of the ground with a 90 on it.
The fresh water flowed from that pipe 24/7 according to the lady whose house we worked on, and she had her house for 15 years and it was there when she moved in.
She told me all the houses on the street would get water from that pipe for drinking rather than the city water.

TimNJ 01-15-2019 08:38 PM

Quote:

Originally Posted by cedarboarder (Post 7455495)
https://vancouversun.com/news/local-...aquifer-breach
More updated link. total cost was 10 million to repair. I was working for the City at the time and we put up sand bags all down the block to divert the water just incase.

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They should just build a nice fancy fountain around it and make it a tourist attraction.

hdavis 01-15-2019 08:38 PM

There are springs and underground streams. Everyone knows springs.

Underground streams run through a layer that percs well, with an impermiable layer below.


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