Allerton Ground Water Tube (AGWT)
- 23 August, 2021
What is a soakaway or drainage field?
When do they become a problem?
AGWT Success
Mr Brian Jenkins, who lives near Port Talbot in South Wales, is a retired teacher and now keen gardener. He enjoys understanding what is right for his lawn and the vegetables growing in his garden. He recently had Allerton install a WPL Diamond Sewage Treatment Plant in his garden. Rather than spoil most of his plants and lawn by having almost 200 metres of trenches across his plot, he opted for a pump station down-stream of his unit, and a much smaller Drainage Field.
His garden is generally flat but levels show it to fall leaning towards the house at a downwards angle. His sewer pipe was a metre deep as it entered his plant, and almost 1100 deep at the outlet end. As drainage fields have to fall in 1 in 200 metres, this meant even deeper trenches were required, the further they went into the sloping garden. And as the percolation tests showed, more and more clay appeared the deeper the holes we dug. It was an easy decision to opt for the pumped outlet as now the Drainage Field could be pumped away from the lawn area to the vegetable area. A win, win for everyone!
The drains, though shallow, did not interfere with his row of vegetables as they were laid parallel to his plots. What did concern him though, was the fear of drawing the roots of freshly planted seedlings and seeds, particularly the rows nearest to the drains.
He would dig holes to see what the water level was, especially after a heavy rain in winter. Water might accumulate close to the pipes, but soon after it had stopped raining the holes dried out. He was still concerned though, and as keen a gardener as he was, he still dug the holes. After buying two Allerton Ground Water Tubes, he was checking the level of his water like he was checking the oil in his old car. Once they’re in there is no need to dig holes, just lift the dip stick out! Sometimes he did find water, but soon after it had stopped raining he would see the water going down hour by hour.
After a year or so he just knew what was going on down there, and so he needed to check it less often. Now he looks at it after a heavy rain reassuring himself that the water was not drowning his plants. Curiosity satisfied, and reassurance given that shallow drains are always more effective than deeper drains.
Contact us to order one now and experiment!
FAQ
Q: Can I still make use of the septic tank if the soakaway has failed?
A: If it is GRP constructed you can. If it is brick, it will depend on sizes. You can still make use of the septic tank by installing a ConSept if it’s big enough. In order to fit a ConSept, the water level below the inlet level needs to be more than 1.1m. Also the volume of water needs to be more than 2 cubic metres.
Read our page about Septic Tank Soakaway Problems for more info.
Q: Can rain water go into a septic tank?
A: NO, heavy rain can wash all the stored solids into the soakaway or ditch or block the ConSept
Q: Does shower water go into a septic tank?
A: Yes. All lavatory, showers, wash basins, sinks etc are classed as foul. These must go to the septic tank. Rain water must NOT go into the septic tank.
A: Soakaways from Septic tanks are bound to get blocked. Raw sewage has 300 parts per million (ppm). Water from a septic tank is not much better at 200 ppm. So those fine particles start to block the soakaway and the ground below and around the soakaway pipes from day one!
Q: Do soakaways need maintenance?
A: It is very hard to maintain a soakaway. Like all filters, they block!
Q: How long do soakaways last?
A: The more permeable the soil, the longer the soakaway lasts. It is important to not let the floating solids escape into the soakaway by having the septic tank emptied annually.
Q: How do I know if the soakaway is blocked?
A: The water in the outlet pipe is covering the bottom of the pipe. It should be free of water!
Q: Why do soakaways fail?
A: Soakaways have a limited life, even if the septic tank is emptied annually. It is a filter in effect. All filters get blocked eventually.
Q: How deep is a soakaway?
A: The soakaway is as deep as the outlet pipe as it leaves the septic tank. If it is in the ground too deep it may not work at all! Clay at depth is much more like Plasticine and clay is used to line reservoirs and canals! If sandy, the soakaway will work much better, but not if the table rises in a wet winter to a level near the soakaway pipe. A wet flannel is useless!
Q: How do I know when my septic tank is full?
A: It’s difficult to gauge, so have it emptied every year. This will help lengthen the life of a soakaway.
Read the section about septic tank emptying on our Septic Tank and Soakaway Problems page for more information.
Q: How deep should a soakaway be in clay soil?
A: All soakaways should be as shallow as possible.
- If you are having to pump, keep the pipe to within 100 mm from the surface.
- Water travels quickly in topsoil, both laterally and downwards.
- Dig a hole 3 feet deep in clay soil and dig a hole 1 foot deep nearby.
- Put a bucket of water in each hole and observe.
Q: What size should a soakaway be?
A: That depends on the nature of the water percolation. Rainwater at 5 ppm? Treated effluent from a sewage unit at 20 ppm? Or effluent from a septic tank at 100 ppm?
Q: Do I need building regs for a soakaway?
A: Yes