Patio nearby creek question.

CK82

LawnSite Senior Member
Hey guys,

I've attached a few pics of a job that we are bidding on. The homeonwer stated when digging for footings for his porch they hit water at about 1ft. They do have a swimming pool as well, which had to be a pond in no time while excavating as well. I'm looking for some info on the steps to this process and what should be done. I have no idea what to do if I excavated and it starts filling with water. The patio and seat walls will be partially in place of the concrete near the house, extending towards the creek.

Please help with any knowledge you could spare.

Thank you,
Chris

2012-02-22 11.15.15.jpg


2012-02-22 11.15.20.jpg
 

bigslick7878

LawnSite Senior Member
Location
Towson,Maryland
How far above sea level is the property?

My father lives smack on a river at sea level and you don't hit water until about 6 feet down.

I can't imagine the water table being a foot below ground, no matter what the homeowner says.
 
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CK82

LawnSite Senior Member
The survey states elevation: 937.59ft. Its far above sea level, but it the house was built in a low lieing area with a creek behind as well.
 

DVS Hardscaper

LawnSite Fanatic
Location
County Jail
Probably not an ideal area for a patio.
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White Gardens

LawnSite Fanatic
Location
Bloomington IL
I'm not buying it, something gives.

Even if the HO dug a hole and found water, it was a freak thing. If there is that much water that close to the surface then not only would the pool have failed, but the foundation of the house also.

Or even if they have a basement, the sump would have to be running 24-7.

You need to dig your own hole to find out.

Personally though, wouldn't be surprised if it has a higher water table in that location.

I would also never have the 1st floor of my house that low next to a creek.

.....
 

bigslick7878

LawnSite Senior Member
Location
Towson,Maryland
I'm not buying it, something gives.

Even if the HO dug a hole and found water, it was a freak thing. If there is that much water that close to the surface then not only would the pool have failed, but the foundation of the house also.

Or even if they have a basement, the sump would have to be running 24-7.

You need to dig your own hole to find out.

Personally though, wouldn't be surprised if it has a higher water table in that location.

I would also never have the 1st floor of my house that low next to a creek.

.....
Pretty much.

My Dad's house has a basement, and the pump kicks on every 10 minutes or so even with the water being about 5-6 feet down.

If the water was a foot below grade there would be no house, definitely no basement. Still not clear on if this house has a basement.

When you have a house near water, there are always all types of little springs running under the ground, but that is not the water table. My guess is they just got lucky and found one of those.

I highly doubt you are going to have any issues excavating less than a foot for a patio. Grab a shovel and dig a little 2x2 hole and see what you find. My guess is a lot of dirt and no water.
 

SVA_Concrete

LawnSite Senior Member
we put pools patios and houses all on land that many times has water 1 foot below grade.

you have to use pumps and stone to de-water your excavation during construction.

we just installed footings for a garage structure down in seaford va, elevation is about 4 feet above sea level, our test pit was 1 foot deep and filled to within 3 inches of the top in about 30 minutes.

http://youtu.be/mhlmhk0MZZo

you can see how we over dig by 6 or 8 inches and then fill with clean stone. you can also see the water laying on top of the ground in the background.

the video is not a great production, just documenting the process should questions arise. Of course i had my engineer on the way out to monitor the excavating, and sign off on the footing.

for your situation, if you find water, no big deal over dig and install clean stone, a layer of fabric and then typical base etc, etc.

my guess is the pool was installed at a higher elevation to keep it above flood elevation. (common practice here) we have pools installed down at the ocean front in sand, where the water table is 1 foot or so below grade.

i installed 10 foot deep pits where the water level was 2 foot below grade, we put in well points connected to a dewatering pump (by griffin dewatering) and supressed the water table 24/7 during our construction. this same method can be done on a smaller scale with a well point and a diaphragm pump.
 
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CK82

LawnSite Senior Member
Your correct, the pool is just above the flood plain level, or so it shows on the survey.

Will I have stabilization issues if I end up hitting water at 1ft. below grade? The entire subdivision is built in a marsh basically, the golf course you can see, when you walk down the fairways if its during the rainy months you feel like your walking on a water bed. I think I should be fine excavating for the patio, but anything further I am not certain. They are looking to have a grilling station installed, in which we install on a concrete pad with 48" deep footings.

I guess I just want to be prepared if I do hit water. I do not own a pump, although I am sure I can rent one. Any additional specific detail on what I need to do, or what equipment I will need in case would be great!

Do you guys install brick over areas previously with concrete as you see, using the base that is already there? I will be able to add nearly 2" to what is there by the drop in thickness of the brick compared to the concrete.

SVA Concrete, what type and size excavator do you use? I am looking hard for a 8k-11k machine and also am open to advice.

Thanks Chris
 
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CK82

LawnSite Senior Member
So pumps and clear stone is key? I need at least 6" of crushed stone with fines compacted for my base, what do I do if the water is less than 6" from grade? Pump continuously and add the crushed stone with fines and compact?

Thank you.
 

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