Help with water / french footing drain issue

[IGOR]

I am building my 36x44 shop in Boring, Oregon.

I have been ready to pour concrete since September, but have an issue with water in my 3/4 minus gravel base. I have dug several trenches inside the shop (in the gravel base) and when it rains they fill with water.



The shop is built into a hill, with the stem wall being approximately 4' tall on the back side. Water proofing was sprayed on the stem wall and a 4" socked corrugated perf pipe was laid around the perimeter of the shop, draining on both ends. On top of the perf pipe was dumped approximately 6" deep x 12" wide of 1.5" drain river rock, with filter fabric laid on top of the river rock before back filling with dirt.







Last week, I had a contractor come and install American Wick sheet drain around two sides of the shop.

http://www.americanwick.com/products/product_cat_detail.cfm?prod_cat_id=26

They dug a 4' deep trench on two sides, and installed the sheet drain completely around the two sides - with a perf pipe at the bottom to drain.





It rained again yesterday, and again the trench has water in it.

Here is a rough overview of the area... Note that all of the drains are sloped toward the lower left corner of the diagram



I am thinking about installing an interior footing drain at this point, but would very much prefer that the water not enter the shop.

Any of you drainage gurus have any thoughts?

 

[dirttracker18]

I think you might just be overthinking this. Once the roof is on and concrete on the floor you will not see the water, nor should it come in on top of the concrete floor.

You have an open area with a low point inside that is water proofed on the outside with footings to contain said water. Where is the water suppose to go when it rains on the ground inside of your current stem wall?

 

[IGOR]

Sorry, should have clarified - the roof is on (as well as gutters) and has been since August - the stem wall only pics were to show overview.



The water is coming from outside or under...

 

[larry4406]

Drain tile and stone crates a void and provides water a pathway.

That said, it does not look like your drain tile is exposed to day light anywhere so the water cannot get out. Have you shot the grade on your french drain to ensure that it provides positive slope and an outfall (exit)?

If your drain tile is the low point with no way out, you have created a bath tub for the water to collect. Similar to a fully buried basement, except in those cases, a sump pump with sump crock lower than the basement slab is used to dewater the foundation.

I have had to use pumps to dewater foundations to allow concrete pours.

 

[IGOR]

All of the drains go to a low point (in the lower left corner of my awesome paint drawing) and then drain into an open drainage ditch.

I have not shot grade on the drain, but the newest drain (with the sheet drain) (when dug) had water flowing out of it before the perf pipe was installed (and back filled)

 

[JoeFin]

I'm thinking your in an area that has an abundance of "Artesian Wells" and your just lucky enough to have one coming up under your slab or close to it.

If so were getting into Soils Geologist territory

Right off the bat I would give the old French Drain just behind the water barrier some where to go other then percolate into the ground. I see from your photos your on a slight slope in a residential density of 1 acre (I'm guessing)

Worse part is you probably don't know where your neighbors leach field is located either. But there should be a plot plan located down at the county

 

[theoldwizard1]

Where do the sheet drain and footing drain go to ? I would think they should run along the right side to the front.

I am thinking about installing an interior footing drain at this point, but would very much prefer that the water not enter the shop.

The water is coming from outside or under...

I think the water is coming UP because your drain are not pitched correctly. That old French drain could be adding a lot of water to the ground.

I don't like the corrugated drain pipe. Use the PVC pipe with a sock installed the same way. Run it all the way around the interior. Pitch is critical.

Also think what will happen if the water at the exit point is higher than the floor !

 

[IGOR]

Where do the sheet drain and footing drain go to ? I would think they should run along the right side to the front.

Why is that?

I think the water is coming UP because your drain are not pitched correctly. That old French drain could be adding a lot of water to the ground.

Also think what will happen if the water at the exit point is higher than the floor !

The top old french drain is definitely adding water - the bottom one is not adding much, as the top one catches most of the water. The exit point on the drain is lower than the floor - as can be seen in this picture



Day-lighting out to street...

 

[flat350]

Is it possible that the old french drain at the lower right is carrying water thru the garage?

 

[IGOR]

Yes, that is possible for some water, but it is most dry section of garage. Most of the water coming into yard is caught by upper French drain.

I'm wondering if I should preemptively install an interior footing drain...

 

[flat350]

Might as well if it's all exposed and easy to get to.

 

[Clik]

40 years in the Drain Business. I am not a fan of socks. I would rather see perforated schedule 40 PVC with no 90 degree turns. use two 45 degree fittings instead. bury in round stone. If pipe clogs it can be jetted with portable power washer and appropriate jet nozzle. Water seeks its own level. Always keep that in mind. Drain well below the slab to avoid wicking moisture. Grade lanscaping away from the building and don't depend on building drain as a primary. If you have an artesian spring, excavate it and develope it as if you needed the water and then drain it away. I hope you put plastic under that slab.

 

[Clik]

If you didn't insulate that wall that's against the dirt it's going to sweat on hot humid days. That cool wall will be like a glass of ice tea. I've investigated alot of ground water complaints only to find the wall sweating.