Backyard flooding due to uphill neighbor

Old 02-26-13, 10:18 AM
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Backyard flooding due to uphill neighbor

I've found several other treads about this, but I was wondering if anyone could offer advise for my situation.

The lot that my house sits on is sloped and includes retaining walls to mitigate some of the difference in elevations. The back yard is retained at an elevation that is approximately level with the roof. The neighbors to the back of the property are slightly uphill from me. During a heavy rainstorm, water from their yard floods over the top of a small retaining wall at the back of their property, flooding my back yard. All the water from my yard then drains down to a patio that is level with my house - which only has one drain. The drain seems to handle the water from my yard's runoff...until we get the waterfall from the back neighbors causing flooding. I have contacted the city to see if their are any regulations that would cause the neighbors to correct this issue, but I fear that they will tell me I have to deal with the neighbor's water. I know that one of the options I have is increasing the size of the patio drain, but I would like to stop the water from even making it that far. I would like to deal with the water immediately when it enters the lot from the neighbor's yard. I've included a plan and site section. I'm wondering if burying a few DIY cisterns in specific locations and creating a rain garden around the perimeter would help.

Any advice is welcome. Sorry for the long explanation.
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PLAN.pdf (22.1 KB, 669 views)
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SITESECTION.pdf (7.5 KB, 634 views)
Old 02-26-13, 10:37 AM
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Welcome to the forums.

Couldn't see your plans, can you try this?
Old 02-26-13, 11:51 AM
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Ideally the drain should start on the neighbor's side of the retaining wall and if you can convince them to do so you might even get them to contribute to the cost. Then again, if they are like my neighbors you might do anything to avoid talking to them at all.

I don't know what kind of plantings you have next to the wall dividing your properties but I would dig a trench fairly close to the wall, not so close as to undermine its structural integrity, and install a perforated drain pipe. Wrap the pipe in landscape fabric to prevent fine sand from eventually plugging the pipe and have the majority of the holes upward. You may need to use solid pipe and drill your own holes if you cannot find pipe with holes mostly on one side. You do need a few holes in the lower side to allow small trickles of water to enter the pipe from below but most of the water will come in the top.

Put some pea gravel in the bottom of the trench before laying the pipe and then use crushed rock (not gravel) over the top of the pipe and all the way to the ground level. You can use colored rock the last couple of inches if desired. You don't need the pipe all that deep as you will be catching the water over the wall as fast as it comes over. You DO need a sufficiently large pipe to handle all the expected water and a bit more without filling the pipe more than half full. No less than 4 inch pipe and 6 inch is not too large.

Run the pipe downward with a fairly decent slope to avoid allowing any standing water in the pipe. It is good that you already have a decent slope to your property so you won't have to dig too deep at the outer end.

I would NOT use the corrugated flexible pipe but instead use rigid plastic drainage pipe. It costs a bit more but is far easier to lay without humps and bellies. Use solid pipe everywhere except right at the point where you want to collect the runoff water. If the pipe does not touch the bottom of the ditch throughout the run add fill below the pipe where necessary to fully support the pipe during the backfilling of the trench.
Old 03-03-13, 10:51 AM
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Agreed french drain with wrapped perforated pipe covered in gravel is your best bet
Cheapest too, but you have to drain to TO somewhere, an existing drain or connect it to a drainage pipe to take the water away
Funny thing is your retaining wall SHOULD have a drain built behind it, so water doesnt destory your wall. What you may want to do is to dig behind the wall in one spot until you reach the footings or gravel and see if there is a drainage pipe there already.
It is the best place to put it as it means thats a far as the water from your neighbors gets
I had the same issue as you the neighbors backyard is 4 ft higher than ours so when we put the RWall in the drainage pipe we put in stopped the water dead in its tracks

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