Lot grading, water percolation & french drain on the property line along the fence..How2 drain t 5

[MiniMe4Eng]

I am now trying to understand if the current water drainage on my lot is wrong. The previous owner excavated the soil around the house and he probably spread the soil around the house in the backyard

Also my neighbor's property is on a higher grounds and I suspect his drainage is not 100% fair.

Below you have a representation of the rear side of the house, the left side house is mine.!

**The purple line** is the general slope of the terrain, as mentioned my neighbor's house is on grounds slightly higher than mine.

**The blue and brown lines** show the backyard general grading. The 8' strip that you see along my patio is not sloped correctly and I intend to fix that.

**The patio** drains toward the red spot where I intend to install a catch basin and I plan to drain that to a dry well south east of that corner

**Problems**

-the yellow line on my neighbors garage is a gutter that he extended on the soil and that currently drains on his property on the paved walkway that you see there

-by design both properties seem to drain the water toward the property line and that should at least affect the fence. As a matter of fact one of the poles is completely cut (rotten) at he base

-I believe that under the soil (subgrade) the water moves toward my house anyway due to the general slope of the terrain

**Questions:**

1. Looking at the measurements of the space between the garages **do you think that the water that the water that comes out his gutter (yellow on the figure) will infiltrate the soil and move laterally toward my property and my garage?** Just next to the garage the former owner built a small parking lot, paved with precast concrete blocks and I suspect that the base of that parking spot will suck all the water that makes it to it. Am I too worried about this?

2. Looking over the fence at my neighbor's patio one can easily see that when he built that he accentuated the slope and that now all that water drains toward the fence. I think that the only remedy here is to build a french drain along the fence which I should drain in the dry well that is in the plans for the patio. Is this a correct plan? **Will this french drain affect the fence in any way?**

3. **Is the distance between the fence and my house long enough to keep my house safe from that water which probably collects underground on the property line?** (not sure where it goes from there)

 

[MiniMe4Eng]

And here is some extrapolated info regarding the topo of my area
I leave below the 140 m level but quite far from the river
Is to so happens that the profile shown below is near a big street that is close to my house (see the marks on the picture, Lawrence Ave)

Bigger picture can be seen here

http://i.imgur.com/NRpi5BO.png

 

[cvg]

so, as I suggested previously, your property may be near a spring. it appears you may have artesian conditions. not much you can do about that except for to waterproof your basement walls and install a weeping tile system with a sump pump to remove the water.

 

[MiniMe4Eng]

How can that happen only on one specific corner right under the patio and for a specific length of the wall with no signs of water or humidity at floor level in basement in that corner ?

 

[MiniMe4Eng]

Let me ask you guys this again: if you suppress the water source for a wet wall like the one that I have, what is a quick an average and a slow time for the wall to get dry again ? Have you come across situations when a wall got back to dry after the source of humiditty was suppressed ? I bed you have not...

 

[oldestguy]

Assuming your term "supressed" means the water table next to that wall has been lowered to below the floor elevation, as with an exterior perimeter perforated pipe drain enclosed in a filter zone, yes it works. The time for the wall to show drying effect varies, but usually the effect starts right away with no weeping water into basement, followed by gradual drying depending on venting there, etc. In the long run these are dry basements, without the moist smell you note. If the perimeter drain is inside the wall (some guys do this to avoid having to dig outside) you can get drainage affecting outside, but in may not work at all in some soils. That's where test pits or test borings come in.

This improvement also applies to cases where surface water infiltration seeps down and saturates soil alongside the wall (no free water inside) , but then the outside surface is treated to prevent that downward infiltration next to the building (and within the backfill to the wall) which could be an extensive zone. This is not a ground water situation, but effects of surface water that show up as damp wall on inside. Once that flow does not happen, gradual drying results, taking days if it has gone on for some time before. Depends on venting, etc.

The work has to take into consideration lots of factors, not just locally next to the wall. That's where the whole area picture knowledge comes in, not just knowing details next to the problem. Your geology section and that rough note about discharge helps, but just scratches the surface.

If your basement floor has any non-finished areas, consider drilling a hole and then exploring more with a wood auger to see if ground water is near the floor. Don't cut into any pipes!!! It may help a little.

 

[beej67]

You're making this too complicated.

This is almost assuredly a surface drainage issue.

Get a surveyor to shoot grades with 1 ft or 0.5 ft contour intervals, extending into the neighboring parcel, with FFEs on both buidlings, and post an image of that here. The solution will be self evident immediately.



Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[MiniMe4Eng]

I am not sure about that.
There is no visible water flow from one property to the other
There is no visible water pooling anywhere on both properties

I am still supecting my patio because it has no gravel base (all built on limestone screening)
I don't buy what oldguy said above, my wall should need more than weeks to get dry. I think that humidity is still trapped either in the limestone layer or in the soil and it will take time till it gets out

One think that I could try is to remove the baseboard in the basement and do something like this

 

[oldestguy]

OG is talking about non-finished walls where you can see the concrete. Who knows with finished walls, possibly having insulation that holds water. Where seepage was bad, those walls required a full interior replacement after things dry out. Yours look good.

 

[oldestguy]

Once more. This is my guess as to where the water is coming from. Sorry, no cad system here any more.

 

[MiniMe4Eng]

If that is the case the source should be eliminated
I regraded the patio and I eliminated the settled areas

 

[cvg]

you said you regraded the patio, but was that done adequately? It should be at least 2% grade for about 10 feet away from the house at a minimum. in fact, you should have that slope on all sides of the house. Roof leads should all extend out and away from the house also. If grading and roof leads are not up to snuff, than I would suggest doing that first. If that does not fix the smell, than at least you have positive surface drainage away from the structure. If this is done correctly, than it will not matter much whether your patio is built on gravel or screening because the water will all drain away from the house. By the way, gravel and screenings both will allow water through to the subgrade. Screening might actually be better base material since it is finer grained and perhaps somewhat less pervious than gravel.

now if you still have water coming in, than do you have a leaking water / sewer pipe within about 20 feet from the house? perhaps even below the basement slab?

 

[MiniMe4Eng]

BTW it is really interesting that they say that the runoff coefficient for a brick patio is close to 1
TO me that means that no water is getting through. How is this possible? I could see the water falling on the patio and simply vanishing without actually flowing toward the edge of the patio
If I cover the patio with a tarp the slope is good enough to send the water away from the walls, I think that the slope is acceptable.
I am still unclear on how much water a patio absorbs in normal conditions. I n heavy rain it is probably closer to the 1 runoff value because there is much more water than it can absorb in that short time but..if it rains slowly and long term but low volume everything seems to get through

 

[oldestguy]

Maybe a description of what is meant by "regrading" will help. Then did your "regrading" change this action? "I could see the water falling on the patio and simply vanishing without actually flowing toward the edge of the patio". Sounds like water running through a sieve. Even on a slope that still will occur.

Did that work change this action described by CVG?

"By the way, gravel and screenings both will allow water through to the subgrade. Screening might actually be better base material since it is finer grained and perhaps somewhat less pervious than gravel."

The quantity of water required to cause the wall efflorescence and moist smell is very little. Likely less much than a quart a week reaching the wall

Do the folks that bag up screenings ever provide a grain size analysis? If they come from quarries in the Niagara formation, likely very little silt and clay content. Produce that and it will answer some of these questions.

In Wisconsin I use those dolomite rock screenings as the filter around perforated footing drain pipes. It's porous. The Niagara is here also.

Also, note the sloping lines on the sketch of wall section. Most wall backfill is shoved in in sloping layers and that directs downward seeping water to the wall also.

This (these) discussions sure use up a lot of memory space somewhere.

 

[cvg]

water absorption of the patio is inter-related to several things:

first - does water sit on the bricks and slowly soak in, or run off
second - how much water can be stored in the void space in the gravel or sand base
third - how pervious is the subgrade material (the soil below the screenings)

replacing the gravel or screenings with a concrete base would eliminate most of the infiltration. that is the typical method for commercial grade pavers around here.

 

[MiniMe4Eng]

One of you said that there might be pipes cracked under the slab or something like that
Here is a vie of the nearest pipes. It is the drain for the two toilets.
I am not sure why of if these go under the slab ...I would rather say they must be hidden in the walls
Whatever the case is, I should see no change in the humidity level in the basement if I do not run the dehumidifier.
Recently I started running it regularly amd the smell is mostly gone.
I tested, if I do not run the DH the humidity does not go above acertain level
I do not open the windows in the basement and I keep the door closed in order to see where the smell comes from and if the humidity changes inside by itself
I am seeing a slow increase (2%) but that seems to be all.The weather here in Toronto has been dry and stable.
I think that these would not be possible if the source of humidity is inside the house
On top of this last winter it went away when the temperatures outside stayed very low for a long time
If the source would have been inside then I suspect I should have continued to have smell in basement.

A source located underground on the near by property is excluded, I can't imagine the water traveling such a long distance

 

[oldestguy]

Here we go again. A few questions scratched on your drawing.

 

[oldestguy]

OG again, trying to keep the discussion here.

In reviewing one of your other posts, I see you say no footing drains.

Reviewing some of your statements and questions, we can be pretty sure the screenings are sufficiently porous to conduct water either by gravity of by capillary attraction.
Chances are the soil below also has some degree of transmitting water from one area to another by capillary action, more or less like a sponge, full depth of wall.

That's where positive cut off of capillary action may have to extend quite deep.

Your questions on one posting:

A couple of questions if I may:
1) is it normal to build a patio the way my patio was built? That is with a 6" of limestone screening and bedding in an all in one layer?
2) is there anything that I can do to improve the drainage of this patio?
3) let's assume that I put the bricks back with the subbase still wet. Is that a good idea/ Will that water ever drain? (remeber there is clay below it)
4) Do I need to remove the massive stones used as edges?
5) My assumption is that the wall got wet because there was excessive moisture in that corner AND because it was in permanent contact with the adjacent subbase which is wet limestone screening. Is this correct assumption?
6) I am now planning to build a buffer or to break the capillarity effect between the wall and the subbase by digging a trench next to the wall and by adding there some insulation. The
trench will be filled with gravel or will be left empty ( I am thinking about some cement blocks.

1) Very common, 2) Looks like the best bet is dealing with the infiltration. One member suggests using a concrete slab. I gave my method, which got a sassy comment.
3) The wet conditi0ns are of no consequence as long as that water can't migrate past a barrier. There is a minor chance of frozen water heaving slightly in winter, That "clay below" likely is somewhat pervious, especially having been shoved back against the basement wall, not compacted. See the sloping lines on the sketch. 4)Probably not. 5) That sounds like the right explanation, but soil below also can be in the picture of moving water in its pores by both gravity and capillary effect..
6) That trench will be another collection zone for water from the surface, snow in winter. It likely will aggravate the problem.

Applying a plastic sheet to the exterior of the basement wall is a way to create a barrier, but it has to be as deep as possible (best all the way to and over the footing.)

If you want to explore the mechanism of capillary action in soil, there is plenty written, especially dealing with plant growth and words like "suction", or "moisture tension". might be looked up. There is a term used for these "Pf" It's been years since my study of that stuff for my Master's, so the label may be wrong.

 

[oldestguy]

I did a little for you. I see my term was backwards for case.

Here is a U tube video, part of some course.

https://www.youtube.com/watch?v=tcsbqYQr8Vs

 

[oldestguy]

This is a shot next to my front door. The house is built for full handicap accessibility,so there is no step at the door.

That means this area has earth fill at that entry grade against the brick wall. The brick sits on a concrete foundation about 12 inches down.
That's 12 inches of earth against the brick, a questionable thing at best.
The plans call for a galvanized sheet metal moisture barrier in the open space between the brick and the interior wood floor framing system behind that.
The house is 13 years old (I have been here 5 yrs) and the engineer developer remarked to me about the barrier. "That's assuming they installed it".

While I can detect no moisture transfer to the wood framing, I decided to do a few things. I dug away all along the wall as deep as the insulation that is against
the concrete. Painted that brick surface with a waterproofing paint. Applied some mastic glue and stuck a sheet of black plastic to the brick.
Painted it where exposed.. Replaced the backfill. Never noticed any exterior efflorescence, but the conditions were right for that to happen.

The earth out in front has been treated out the full area of backfill with the bentonite treatment I have remarked on before, mainly to provide a surface barrier
for any rainfall or snow melt. The site is on a shallow water table, only a foot or so below basement level.

 

[beej67]

I am not sure about that.
There is no visible water flow from one property to the other
There is no visible water pooling anywhere on both properties

...which wouldn't matter if it's leaking into the ground, which is exactly what you don't want. You want to be able to see it flow away from your house.

If you refuse to have someone go out there and shoot grade, get your smartphone and video the land between you and your neighbor's houses, as well as the patio, during a half inch storm. You should notice water flowing towards the street or towards the back of your back yard, ideally both. If you do not see water flowing along the ground in at least one of those two directions, then your problem is surface drainage.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com