Landscape drainage problem

Miller-man

Hi all,

The houses in my California neighborhood back up to an unbuilt upon natural slope. An open, concrete, V-shaped drainage ditch runs the entire length of the hill and empties into a County-owned drain that empties into the flood control system. While this ditch runs outside almost all of the properties, it runs within mine, above which is a wrought iron fence.

The problem is that when we have heavy rains, all of the landscaping I have done above the drainage ditch washes away as the water runs through the wrought-iron fence and down into the ditch.

I would like to build a short, supplemental ditch just beyond my fence that will collect water run-off and divert it into the ditch in a way that it does not wash away my landscaping.

So, is this a good idea? What is the easiest way to accomplish this? Instead of building a concrete ditch, can I bury a half-pipe into the ground as a ready-made collection system?

Any help that can be provided would be of great help.

Thanks.

Randell Tarin

Water is going to go where water wants to go. BUT, it will follow the path of least resistance, so a diversion might be feasible. You have to be careful though so you don't create an errosion situation and make your problem worse.

You can actually create some drainage solutions that will enhance your landscaping. If you can afford large rock, then you could create a dry creekbed with plants around it to hold the soil. Another solution would to create a berm in front of the drainage ditch on the down side. This would keep the water at bay and you could plant the berm to enhance your landscaping.

downunder

Re: RT
Ditto. Excellent suggestions. I'll just hush.
Richard
Georgia Certified Landscape Professional

Miller-man

So, instead of constucting another drainage ditch, construct this dry river bed along the wrought iron fence? How deep should I go? Would it act like a French drain?

downunder

Miller-man
Any possibility you could post some photos for us? Is this county ditch perpendicular to the w/i fence, parallel to it, etc? About how far from the fence is the ditch or about how big of an area are you trying to work with? You gave good information so far, but I'm not visualizing it just yet.
Sounds like an interesting project.

Miller-man

The county ditch is parallel to the back fence of the yard. The back fence is about 10-15 feet from the ditch and the entire length of the fence is about 75 feet.

I have three pictures of this area in photo album...

Picture 1 is looking along the county ditch from within my property; the house is to the left and the backyard fence is to the right. The landscaping to the left of the ditch is what gets disturbed when there are heavy rains.

Picture 2 is a look at the backyard fence from outside my property. The supplemental ditch that I am proposing to construct would parallel the green, metal fence along the back and side of the yard and would dump into the county ditch.

Picture 3 is a view directly behind my property toward the house which shows the direction of water through the fence and toward the county ditch.

Thanks for looking.

Randell Tarin

Does this sketch approximate your conditions?

If the top of the drawing for discussion purposes is North, then which direction does the water flow down the slope into the drainage ditch?

Which direction is it flowing in the ditch?

Is the entire length affected or only a portion? If so, which part?

Attached Images

 

Miller-man

Your drawing is accurate.

The flow of water is both South and East. So the water flows downhill from the Northerly direction and the ditch slopes downhill to the East.

The areas affected then are within the West side and North side fences.

I hope this is clear.

Randell Tarin

If it were me. I would start your new ditch in the northwest corner and possibly even higher than the corner of the fence and run it diagonally in a southwesternly direction to the concrete drainage ditch outside of your property.

This will divert the water away from the high side and take to the drain below your property.

I would get the largest rock you can find to go in your ditch. The small stuff will simply was away. Make sure you don't require any permits or permissions before you proceed.

Attached Images

 

Miller-man

Your idea is excellent except for the fact that I share the Eastern fence with a neighbor. The trench I would like to build is shown in red. It would go under the fence and to the trench so that I don't accidentally pass my problem onto my neighbor.

You mentioned gravel in the trench, but what about burying a half-pipe or attempting to build a concrete lining? Or even a French drain?

Attached Images

 

Randell Tarin

Your main concern with lining the trench is to prevent erosion. I wouldn't recommend a half-pipe because this would do nothing to slow the velocity of the water. A french drain would not accomodate the large amount of water that is currently the cause of your concern. As mentioned before, a dry creek bed would be your best bet. And, I didn't say GRAVEL. I said large rocks, softball size or bigger.

What I have done for with drains such as these is place the rocks then sprinkle dry concrete mix over the lot. This will eventually lock them into place. To prevent erosion, you HAVE to slow the velocity of the water.

Miller-man

Thanks, I believe I understand what you are saying. I was trying to divert the entire volume of water away from my property where you are proposing that I slow the water down to limit the erosion.

Thanks for your help.

downunder

Miller-man
Looked at your photos the other day but haven't had time to compare them with your text until now. Looks like you don't have a terribly steep slope there to deal with or particularly long. Not like 100 yds! I can see where you got the idea to just divert the excess water away and into the county ditch. On one hand, I kind of agree with you.

RT
I see your thinking in slowing down the water and in most cases I would agree if the runoff was continuing into other landscaping after being diverted, somewhat like into a rain garden, although that analogy might not be the most appropriate. Not sure I'm seeing where it would hurt though in this case to let it run as fast as it wanted to- as long as the erosion issue would be addressed by a concrete/pipe/whatever lined ditch that definitely emptied into the county ditch and not into any other area.

Each of these ideas has its merits. I suppose it comes down to what MM is able to do and what blends with the landscaping theme over all. If you think about it, RT's creek bed is a ditch, just with slow water. Actually, from the aesthetics perspective I lean that way. So- fast ditch or slow ditch? I don't know what the cost difference would be there between the material choices. To me, landscaping is a matter of taste similar to one's wardrobe.

PS
I'm really impressed with those graphics as well as the thought given in this thread. Lots of other forums have self-serving idiots who, like my daddy used to say- "Better to be thought a fool than to open one's mouth and remove all doubt!"

MM
Maybe a follow-up on this after you decide? Couldn't help myself on the fast ditch/slow ditch thing!

Miller-man

Thank you Downunder for your thoughtful reply and RT in all your help to visualize this procedure. I have never posted to something like this before and I am grateful for being able to talk this out with you.

I am beginning to like the dry river bed solution more and more; I'm just not thrilled with the idea of moving 300 cu ft. (preliminary estimate) of stone.

I am currently building a patio and planning on working on the ditch when I have some time off in August . When I do finish it, I will definitely post pictures of the results.