The Problem With Heavy Rain
With rain as heavy as we are currently experiencing, the ground, already saturated, is being asked to take even more from roofs and hard standings. Before the house was built all the water that fell on each acre of land had that area to deal with the water to send by drains to ditches or by run-off. Or simply absorbing it. If water could not get away, then puddles would form. Indicating the saturated nature of the land.
We come along and cover some of the land with houses. Over time, we add sheds greenhouses, house extensions and concrete/ tarmac driveways! Everything we do covers up part of the earth.
You can find out more about how to predict the effects of heavy rain on your system in this blog: Percolation Tests/Soakaway Size Calculator.
So we have to ask… how is the land able to cope?
One of the consequences is serious flooding. This hits the headlines, but the consequences for those Sewage Treatment Plant are serious too. If the septic tank or stp is just relying on gravity to get the water into the soakaway (aka drainage field), then as the ground gets wetter and wetter, the water backs up into the unit or septic tank and then into all the manholes.
Now we have a real problem. If the manholes fill up the kitchen waste water overflows on to the path. Lavatory water fills up the pan.
Getting a septic tank desludger in to reduce the level will help for a couple of days providing it doesn’t empty it. The tanker will be taking ground water out as much as sewage, and far more than normal. The tank could be full again because of the amount of water in the ground.
If you use a desludger be sure not to empty it too far below the inlet level to prevent the tank coming out of the ground.
A Temporary Solution
Using a fishpond pump could well solve the immediate problem but won’t do the pump any good. Sewage water is corrosive over time.
Care has to be taken too with electricity and wet environments. It is a long term problem that should be resolved at a later date. Fixing a pump station in the garden down stream of the unit is probably the answer. Getting our engineer out to advise is a good step to take. Buying a small pump, lay flat hose and cable could be a good short term answer. But be careful with electrical stuff.
Placement of the pump is important. If you place it not far below the inlet pipe then there is no danger of over emptying it. The pond pump should be stood in a bucket of clean tap water and the water flushed though the pump to enhance its life!
Fishpond pumps should be used only to reduce the tank water level down to the normal outlet level. No further!
If the tank does not have a proper concrete surround then it can move upwards. Just moving an inch will affect the pipes to the tank. Just dangle the pump at outlet level. Stand and watch it, don’t leave it or it will run dry and burn out, or alternatively, invest in a pump with its own float level. Only then can you leave it.
But it still needs to be checked. It’s a makeshift temporary solution to get you out of a mess.
- Keep children away from the open tank.
- Make sure the hose is long enough. Too close and you will find the pump is pumping the same water over and over again as it circulates through the soil. These heavy rainfalls (more than a normal month’s rain in a day on top of a period of saturation) are to be expected because of climate change.
- Investigate your See where the rain water soakaways / drainage fields are in relation to the foul water one is. Does it need diverting away from the important foul soakaway?
- Get your blacksmith or garage man to make a pricker (a metre long steel bar 20 mm diameter, one end pointed like a pencil. The other with a tee handle 30 mm diameter 300 mm long). Search for pipes and listen to the noise it makes! Ping! Means old clay pipes. If it bounces, it’s plastic. Practice first.
What To Do
Re: Flooded Soakaway/ Drainage Field
We will get to you when we can but with so many suffering the same problem we can’t do it all at once. Let us know if you have sorted the problem with a pump. We will still make an appointment when we can.
Re: Floating Septic tank or STP
Get it in writing from the installer that your Septic Tank or Sewage Treatment Plant or any other underground apparatus, has been installed according to the manufacturer’s recommendations. If you have had this happened to you, send us your photos and we will have a rogues’ gallery!
FAQ
Q: What size should a soakaway be?
A: That depends on the nature of the water percolation test. 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
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!