How to improve drainage?

[Kvic]

So I have been wanting to fix a drainage problem on my friends property but I wasn't sure but today the wet weather has confirmed my suspicion.

The property is a sloping block

Slopping Block

The water runs down from the highest point on the block and is surface water that turns into 3 main streams. The heaviest of the 3 runs down the south side of the block fence line and the garden alongside the fence has been washed out many times.

The first and second water flow runs into a entertainment area making lots of mess and fortunately there is a drain that was blocked today by the abundance of garden matter, luckily we were home to unblock the drain or we may have had a flood through the house itself.

I created a little dam to stop most of the water going into the entertainment area but look at the amount of water on the path and the garden behind the Besser block wall is submerged.

So what I want to do is run a drainage from north to south or across the property backyard before it runs through the living area. I though a spoon drain would suffice but that's a lot of water and what about garden foliage blocking?

I looked at the building plans and found that the drain from the entertainment area runs underground along the south side fence line and I want to run the spoon drain into this piping system to the roadway.

The drain is the dash line from the space open private down along the south side fence to a detention basin before running onto the roadway. 

This would in my opinion take the surface water from the backyard to the roadway drainage.

Watching the drain in the entertainment area was unsettling as the garden foliage block the drain and I would like to get some opinions on which type of drainage would be better and yes I will be doing this myself and will pave the clothes line area, regain the southside fence garden by replacing all the washed away soil.  

https://www.youtube.com/watch?v=nod1fCw5tJM

[MitchellMc]

Hi @Kvic,

In order to determine the number of blocks and amount of mortar you'll need for the wall, could you please let us know the length of the wall that you'll be creating? 

It sounds like you are on the right track. Your sloped string line is throwing me a bit, though. Is that a separate one from the one you've described that is level and for establishing the level block base?

I see you have road base under the drain coil. The drain coil needs to sit on the soil, or the water will run through one wall and out the other side instead of being carried away. Also, there should be road base directly above the drain coil so the water can drop through it and into the coil. You seem to have a layer of soil above. You'll see what I mean in this helpful step-by-step guide: How to install garden drainage.

Please let me know if you have any questions.

Mitchell

[Kvic]

I was going to work out the number of materials I needed, myself, once the rain has gone and just working out my approach for this job.

Yes, you are right the string line should be straight across for a measurement to the ground.

The drain coil is in front of the wall with the limited draw ability in google draw.

Should the concrete base of the block wall be lower than the drain coil sitting on the ground? 

I will make the changes you have pointed out and show soil under the drain coil, the measurements of the string line, and approximately the materials needed, soon.

[EricL]

Hello @Kvic 

The drain coil is supposed to be lower than the concrete base. The water in theory will flow to the lowest point of the floor and from there flow into the drain coil and get carried away. In regard to your clothesline area have you considered placing a series of drain coils to divert all that water out of the area?

Here is a handy step-by-step guide on how to install Vinidex Draincoil:

If you need further assistance, please let us know. 

Eric

[Kvic]

The clothes line is at the highest point of the yard on the north fence and as this property is a duplex the water will be funneled from the north fence across to the south fence side and then continued down the property southside fence to the existing rain water underground pipe, half way down as shown on the property plan when the property was built 20 years ago.

As this existing pipe is 100mm then I will install the 100mm sock drain pipe system.

The drain pipe across the yard from the north and south fence should capture most of the water down from the backyard and any water that comes across from the neighbors property along the south fence line will be captured before it connects into the existing water pipe system.

I feel I have most of the water flow problem sorted with this solution.

The only concern I have is where and how to lay the drain pipe along the Besser block fence.

If I have the soil removed lower than the block base then water could wash out soil below the block wall, if I extend the concrete base of the block then that could help or should the drain pipe be moved away from the wall?    

[EricL]

Hi @Kvic 

Have you thought about building it like a French drain? You can remove the soil and use GRUNT 1 x 10m Non-Woven Geotextile Membrane Drain Mat Fabric so that you get full soil filtration and then place gravel on top instead of soil. I've placed an image below to give you an idea of the possible layout.

If you need further assistance, please let us know.

Eric

[Kvic]

I have measure up the yard.

I will lay a wall across the yard, 6.6m, and then at a right angle extend the wall for another 3.5m along the neighbors fence line to the existing wall.

Across the Yard

The boundary fence joins a step existing Besser block wall 3.5m

The drain line runs across the yard and down th3 boundary fence to the underlining storm water pipe.

[EricL]

Hi @Kvic

Thank you very much for the update on your plans.  My only recommendation for this project is to add two extra full blocks just in case you have accidental damage while installing the blocks.

Please keep us updated with your progress, we look forward to seeing the start of your drainage project.

If you need further assistance, please let us know.

Eric

[MitchellMc]

Hi @Kvic,

Will these walls retain soil? If so, they'd likely need engineering, especially the first 1200mm high one.

Here's a helpful step-by-step guide on How to our a concrete slab. You'll also find these calculators handy for calculating how many bags of concrete you'll need for the slab and how much mortar you need for the blocks.

Mitchell

[Kvic]

Most of these walls will be mostly uncovered but I could included rebar and filled with cement where the block height is over 3 blocks or more but I don't feel it will and may find that I could remove a couple of rows from the top, on all walls, when laying.

The north fence is the highest at 460mm which is less than 3 blocks high and then it drops away so most of the wall will be 1 or 2 blocks.

The neighbor's fence line drops very quickly from the 1.2m and most of that wall is not supporting the ground and is why it is stepped to run along the property ground level as does the old block that it will be attached to.

The same goes with the other shorter block wall that goes from the north fence to the steps.

North Side Fence

Neighbor Fence Line and the yellow post is the 1.2m

 

[Kvic]

So I checked out the weather for this weekend and saw the rain was coming next week so l started to dig out my across the yard drain pipe channel, pick and shovel style, very heavy going with rocks and roots but I did make a good mess of it and then the rain came.

 ChannelOther end

So the channel filled up with water and I hadn't open it up to the south side of the fence. I open up the south side channel to flow down the property.

South side fence line.

The water from the channel runs down in between the Besser blocks and fence. Currently or the reason for putting in a drain was to divert the water coming out from under this stairway and flooding the lower court yard with water and mud.

I decided to add a blue food dye to the water at the channel while it was raining to see where the water flows?

South side fence lineUnder stair case

 So the water flooding in the channel is seen here coming out from or still coming out from under the stairs and interestingly along the south line fence.

So I hope that when the weather dries up tomorrow to cart 2 ton of blue metal up from the front driveway  by hand or bucket attached to a step climbing trolley to start laying the drain pipe system from the north fence across to the south side fence and then down along the fence line to the underground down water pipe system.

While there is still some flooding in the entertainment area there seems to be a lot less and most of it is running down the south side fence and is a lot cleaner without the mud.

I assume once the pipe is in place the water will be carried off quickly and further reduce the flow into the entertainment area.