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Hi everyone, we just moved into a house, surrounded by neigbors' properties on higher ground:
This causes occasional stormwater runoff to our backyard and we are planning to make a swale to carry all those water away from our house to the street:
Why not to use underground drainage system?
Because the system is pretty old and partially compressed by underground rocks , reducing the water flow. We consulted two plumbers, both inspected and said so far the system doesn't have any blockage. It can accomodate the water flow from 4 downpipes without any backflow problems, but the compressed system is already at full capacity , so it wont work to install drainage pits in backyard and connect them to the existing system. Unless we spent $2000 to relay all those underground pipe!
How about AG drain?
Yes, it seems very common, though both plumbers said its not suggested because the soil is mostly clay soil and makes it difficult for the water to get soaked into the AG drain pipe. Another reason is, the rainfall can be so heavy pooling on the surface that AG drain wont be effective enough. And they said we need to focus on surface drainage such as installing drainage channel
What about other solutions?
After some research, its seems SWALE is another good surface drainage solution. We already dug a small trench, and had some success in divert the water from the left (area with most water) to the right side of our backyard.
Some google picture ideas:
What do we need to do?
To turn a Trench -> a Swale
We need to dig wider and deeper.
What are the challenges ?
1) Even we dug a small trench, the weed spreaded like wild fire and often invades our trench , they are so dense and impede the water flow.
2) The soil can be loose and crumble a little bit blocking the trench
Questions:
1) What type and size of gravels do we need to get from Bunnings to put into the swale?
Type: Ideally it can interlock with each other, so probably need something angular, not round pebbles, and this way we can "walk on" the swale.
Size: Seems we need smaller rocks to "support" the swale and prevent soil erosion? But if we its too small , not sure if this can impede the water flow. But if its too big, we cant walk on them stably. We will lay turf around the swale in future.
2) Do we need to lay weed mat or some mulch in the swale first? Or the rocks will be enough to block the sunlight and prevent those weed from growing.
Video showing the direction we want the water move:
https://www.youtube.com/watch?v=dpLj6qWIFx8
(Looks like a mess. We just moved in. But hopefully we will overcome all these challenges and turn it into a nice backyard without water pooling. You might also notice an old concrete slab, we will remove it with our impact driver.)
Thank you so much for any ideas and advice.
Good Morning @Ben2065
Must admit I do like stormwater issues and how to solve them / use it to your advantage.
I have had similar issues with my stormwtare and my neighbours stormwater, to the point I have redone 30m of stormwater piping, my gutters replaced and then the most important part re-landscaping my yard.
There are a lot more projects that all tie in with the landscaping if you troll through my bookmarks.
This one tho is where it should start as in capturing surface water and redirecting it. Side path rebuild from recyled pavers
I had put in stormwater drainage underneath the ground (yeah there is a project for that as well ) The surface water I knew I had a bit to worry about but not as much as actually came down the path...
Channeling the surface water and giving it time to slow and soak was my answer to teh quantity of water that falls. The water these projects refer to is from 2 years plus ago.
I will try and post some updated pictures on how the berms/culvets and holding ponds held up ovetr last weekend. They worked, and worked extremlly well
French drains I find are more for subsurface water drainage to dry soggy areas, Drains can work but will eat away at soil and create their own paths.
The first step I would suggest is to grab a sketch pad and sit down at your lowest point in the yard and then sketch your yard, just teh outside part first and then the large things in the yard, adding in the things you do not want to shift (trees, brick walls) Once you have done that draw some flow lines on the sketch in a lighter pencil, it really solidifys where the water has travelled and what areas you want to modify.
For the second sketch, the modified one that you want to do to fix the problem think of things that can slow water runnoff. Berms, holding ponds and even culverts/bridges that you can incorporate into your yard, These will stay dry and unused for 95% of the time and only come into play for things like last weekends rain instance. In fact I had started considering removing my berms around 3 weeks ago as they hadnt been activly used for 2 years 
Lucky I didnt.
Will try and put a project together later today that will explain better. Also will go through yoru photos a little more as I find it interesting to put into place things that will work no matter what The path you have that is paved with paver stones already has my interest as there is a low side and a high side, dish drains, funnel drains all come to mind.
Dave
Dave
Afternoon @Ben2065
Ive just posted the stormwater update for you Stormwater Update April 2024 It shows what I did by using berms and holding ponds around my yard to mitigate the water pouring through the yard.
Have a read and then maybe add some of the ideas to the sketch of your yard. Gabion Walls are also handy as they allow water to travel through and at the same time form lines within the yard. Can even be used as benchseats
Id start with say the laneway beween the yards. There is a high side and low side. Id actually deliminate the two, either place the path exclusivly on the low side with a hard edge to funnel the water towards the lower end or put some long kinks in it to slow and alow the water to bank up instead of power pushing through fences. Id move the bins to the high side of teh path so theer is no chance to allow them to become blockages.
Whats on the other side of the lower fence?
The yard with the corner brickwork looks promising to put something garden wise in to steer the water and disperse it across the yard. The more water that soaks into the lawn area the longer it will last in the summer.
That photo with the arrows looks like it goes to a public channel? if so you could really factor it in but instead of a straight run to it with a drain, maybe a few curvey berms to slow the rush?
Dave
Hi @Ben2065
I was thinking of what else you can do to direct the flow of water, have you considered building a custom concrete channel to catch all the water? You can follow the natural contour of the land, and have it exit out to the front as it always has. In this manner the water will not soak into the soil and at the same time prevent it from carrying away all the surface soil.
Any soil caught in the channel can be shovelled back to the garden and it will be almost maintenance free. Plus, any blockage can easily be dealt with.
I've drawn up a sample image below. Let me know what you think.
If you need further assistance, please let us know.
Eric
Hi @EricL @Dave-1 @MitchellMc ,
I have been considering the vast range of options to manage the lane. To start with I have measured out and considered using the everhard channel drain however the line of the current waterflow is not directly linear (nor is path) and the bulk of the water is rushing into the lane at the top end of the path with all the concrete pavers. Furthermore a 15m run of everhard channel drain with elbows etc will be rather expensive. I am now considering installing a stormwater drainage system with a large stormwater pit (450 or 600mm square pit) in place of the 4 concrete pavers with 2 other pits along the lane (likely more 300-450 sizes). This way the discharge water pipe can be in solid 100 or 150mm pvc under the soil and can have the pits branched off to reach the low points in the natural run off of the water. I have an embankment outside the lower end of lane that I can safely discharge the water to. I am also really hopeful that once this is set up and the rate of water flow down the natural swale is dramatically reduced I may have sufficient water control to get turf to be happy in the lane as well which will improve the appearance and also help with preventing soil erosion. Finally I plan to install besser blocks (https://www.bunnings.com.au/brighton-masonry-390-x-190-x-90mm-full-besser-block-100mm-series_p345047...) along the side of the colour bond fence to avoid water ingress under the metal fence as well as providing a raised step to the gate to funnel water run off to the pit.
Morning @Ben2065
I like the sound of your plan, it sounds like it will collect the stormwater nicely. With the exit of the water to the embankment you mention are you going to disperse the runoff or it of let it pool?
Actually envious of the problem and really hoping you take a bunch of photos of the project and post the project in here
Dave
I looked at my lane tonight and found it has huge fall (about 7% gradient down hill - 1m fall over a 13m horizontal run). I am reluctant to do the pits as it involves so much excavation for plumbing, lifting all the pavers, reshaping the topography etc...whilst the lane has functioned reasonably well without any storm water drainage for the last 40 years I have seen it. The everhard drainage system looks nice but on a 15m run (a few 90 degree bends for better coverage) it adds up to about $550 and it also needs a large trench cut with concreting around it. I have considered an alternative option which is closer to the spoon drain idea but using PVC pipe. I have considered cutting 100mm or 150mm PVC pipe down the centre as well as a few Female-Female 100mm or 150mm (depending on pipe gauge chosen) 90 degree bends and gluing it all up with pvc glue on a shallow concrete or gravel bed. That way the water can exit the run at ground level happily, there is no serious extensive excavation required and being pvc it will happily allow bins the ride over it etc. Also means that I don't have to get creative in shaping 15m of concrete spoon drains. This guy is using a half width pvc pipe as a goat feeding trough but essentially it shows what I am considering. Let me know if you think its a crazy idea but as I have some spare 100mm and 150mm pvc, spare pvc glue and wouldn't require lots of concrete I suspect I could do the whole 15m run in about $100-150 budget. Only main difficulty will be cutting the pvc down the centre with a hacksaw but sure I can manage it. Also being an open top spoon type drain would theoretically be easy to keep clean of debris and allow grass to grow up to it. https://www.youtube.com/watch?v=SE71LgdjW1c I would appreciate your thoughts. Maybe I'm just better to go with the everhard drainage system? Many thanks for your ongoing guidance. I have also attached a plan for everhard drainage install for an alternative approach. For the water exit point it is out onto a steep tall sandstone clad embankment so I could exit this way to the street in a safe fashion as other stormwater pipes exit in the same way from my place.
That's certainly an idea @Ben2065. I'd try to avoid as many corners as possible, so perhaps consider a straight attack across the path instead of the zigzag.
As with any plumbing-related project, it's best to speak with a licensed tradesperson to ensure compliance with local regulations and that what you've proposed will function adequately.
Mitchell
Good Morning @Ben2065
Your laneway is pretty much the same slope as my front yard. I do like the idea of a dish drain of some kind but think the idea of using the PVC pipe cut in half may not work so well. As in "effort involbed = poor return"
The paver drain would be a possibility but will still require some digging. Its an open top drainwhere you have the center run of pavers lower then the pavers for the rest of the area. So profile wise paver then a step down to a lower paver and then step up to the same level paver as the first. This will give a chanel for the excess water to follow and not scour the land.
At the moment your pathway looks like the low point is down the center in line with your pavers, this is why digging either side out may have to happen. This drain should really be on the side and not in the main foot traffic area as the pavers either side of the drain are not fixed, but placed insitu.
When I say paving dish drain I mean you use pretty much only 3 pavers wide. The two topmost pavers overlap the bottom paver to give a channel for water to run down. The drain needs to be the lowest point across the path.
The funny blue shape is the profile of the step drain. Flat, then one paver lower then back up and one paver (With the top pavers overlapping the bottom one). The long blue twin lines are where Id suggest to place the drain. The bins can sit over it and still the drain will do its job, The digging will be lowest as its mainly shift the large pavers to the right and you will need to level that.
If you go with the cut PVC pipe id go for straight runs as more corners will proberly cause issues. One thing your idea did make me think of is instead of PVC pipe (I know you have some already ) you could go down the track of using a wide metal gutter or old channeled roofing, as long as it has the same chanel ability it should work.
Dave
Dave
