This is a DIY guide to install Polypropylene soakwells.
1.0 - INTRODUCTION
Soakwells are a requirement in Perth. By law in WA, homeowners must have soakwells installed to dispose of all their rainwater, and stormwater.
A soakwell is an innovation whereby rain water travels to a designated area and seeps into the surrounding soil. Soakwells are found near downpipes leading from gutters on practically most outdoor habitations.
Typically soakwells are made of cement, PVC, or plastic and may be found with or without concrete pavers or lids which resist pressure from above.
Soakwells are important in maintaining the integrity of a building’s foundation.
PVC Soakwell = You'll be doing the job twice
Concrete Soakwell = crap
Ag Drain = good
Poly drainage tanks = bloody fantastic. These are the very best and most effective means to leach water back into the soil. They handle enormous pressures from both cars and internal water pressure.
2.0 - DIY POLY SOAKWELL SUPPLIER
I found a company in Perth that sells DIY Poly Soakwell kits at a pretty reasonable price.
http://www.soakwellsolutions.com.au/diy.html
They sell soakwell in Kits, 1 Kit is required per downpipe.
Each Kit Contains:
1 x 135L Polypropylene Soakwell (400W x 740L x 450H) pre-wrapped in geo-textile fabric
1 x s Square Grate
2 x 90 degree Bends
~2.5m x 90mm PVC Stormwater Pipe
Cost of each kit is $65.
e.g. for 9 soakwells i received 9 kits @ 65 each = $585
3.0 - WHAT YOU NEED
01. 135L Poly Soakwell
135L (450H x 400W x 750L) units by Ausdrain
http://www.ausdrain.com/downloads/ausdr ... _tanks.pdf
02. 90mm Stormwater Pipe
Pipes come in 6m lengths
03. 500ml PVC Pipe Cement
More than enough. I used about 200ml for 9 soakwells.
04. Square Grate
05. 90 degree bend
06. 45 degree bend
Optional, based on your routing requirements
07. T Joint
Optional, based on your routing requirements
08. Coupling Joint
Optional, to join two pipes together to lengthen pipe
09. Shovel
For digging soakwell hole
10. Trenching Shovel
You guessed it, for trenching from soakwell to downpipe
11. Hacksaw with spare blade
For cutting Stormwater pipe to length
12. Tape Measure
To help workout pipework lengths and measurements
13. Pair of scissors
To cut hole in geofabric for pipe insertion.
14. Pair of gloves
Handy for digging, which you will be doing plenty of.
15. Lots of food and beer for helpers
4.0 - PLANNING
Plan it out. Do a quick sketch of the house and plan your soakwell locations. It would be handy to note where you place them for future landscaping works etc. Dont mind my fancy piping work, i was restricted by space (stacks of bricks on the front etc).
Try and place soakwells at least 1.5m away from the house slab and away from any other walls If you are restricted by space, you can run the PVC pipe to an area where there is more space.
1 x Poly soakwell is adequate per downpipe, but if a downpipe typically expells more water than others, 2 soakwells can be used by spacing them apart and connecting via. a T Joint. Example shown further down.
5.0 - PROCEDURE
Once you have planned all locations for soakwells and determined number of soakwell kits required, purchase all materials. Get a few mates together and pick a good day for installation.
When soakwells are delivered, the guys at Soakwell Solutions will spend 20 mins showing you how its done.
Pick the first location for soakwell installation. The best time for digging is after a good rainfall because the ground is nice and moist which means that sand wont keep falling back into the hole when you're digging. You can always run the hose over the digging area for a bit to moisten up the area.
Dig your hole. If you can, try and install soakwell at least 1500mm away from any walls. The bottom of the soakwell should be at least 850-900mm below surface to allow for 400mm of soil cover over soakwells. The trench for piping does not need to be as deep, 350-400mm is sufficient.
Level out base of hole so that the soakwell can sit nice and flat, the flatter the better. Be careful and watch where you stand. we had many freshly dug holes accidentally collapse. Digging the same hole 3 times is not fun!!!
Place the soakwell in the hole carefully.
Once the soakwell is in place, start piping. As shown in the diagram, you want to install the 'square grate' as high as possible (50mm below downpipe) so that the paving installer has freedom to choose floor levels.
I found it easiest to measure to centrelines and then fabricate the pipe to suit, intermediately checking if its fits before gluing it all together.
Make a 'X' incision into the geofabric surrounding the soakwell and insert the pipe into place.
Once you are happy with it all, start filling up the hole and compacting as you go!
Enjoy!
Top Tips
1. Do not connect soakwells directly the the downpipe.
By separating them at the base with a grate, when the soakwell fills (and it will) you don't get a build up of water pressure forcing out sand through your paving and you don't have your eves flooded.
2. Allow at least 400mm of soil cover over soakwells
3. If possible, install soakwells as far away from house as possible, 1.5m is enough.
4. Ask some good mates to help and provide lots of beer for reward (after its finished)