Septic tank flooding with rainwater - advice please

Kashkai

Hi all,

Our septic tank is full of rainwater due to the manhole next to it being below the surface of the garden and thus the surface water (of which we've had a lot lately :mad: ) has seeped into the septic tank through this manhole (which is currently submerged). Therefore, our drains are backed up as they have nowhere to flow to. This arrangement was in place before we bought the house and its the one thing we never touched during the extension to our house. It hasn't given trouble before but we haven't had rain like this before either. Now I went into our to the garden today in the hope I could dig a large hole around the manhole and hope it would either help keep the water below the level of the manhole or else help it to flow away. The opposite happened, i.e. I made a little soakpit which just encouraged more water to flow in.

Now the question is, is this fixable? Can I buy some kind of pvc extension pipe that I could attach between the main sewer pipe leading into the septic tank and the manhole cover - the purpose would be to keep the manhole above ground level. This extension piece would obviously have to be sealed to keep the water out. Is this possible/feasible before I walk into Chadwicks/Brooks and make an ass of myself?

Advice appreciated.

David

djmc

try the outlet pipe from the septic tank to the soakpit sometimes it can get blocked . you could try to free it with a long plastic pipe and a pair of gloves
Otherwise you could get someone to empty it with a vacum tank or truck etc
and build up with blocks above ground level

Sonnenblumen

I think you have a compounded problem now septic tank overflow mixing with surface water which I think you'll need to separate by firts draining tank (expensive). Secondly you'll need to install a land drain to take surface water and build up around manhole away from area. This is best done by installing a soak pit or other way of storing surface water away from area which could be re-used as irrigation water fro garden etc.

Urgency is to alleviate pressure build up within waste system which is obviously a much greater health risk.

Hiring a tank to drain is expensive upwards of € 600 + VAT.

Kashkai

I've got a puraflo system, i.e. the water from the septic tank gets pumped to a separate peat based tank for final treatment. This water is being pumped away so the septic tank isn't blocked. The problem is surface water is flooding the tank. I had 3 land drains installed by a builder but they obviously aren't doing the job.

So will my original suggestion work or not, i.e. try to extend the manhole above surface level to keep the rain water out???

Toilets are all backed up now and its getting smelly:eek:

Sonnenblumen

Prosperous Dave wrote:

I've got a puraflo system, i.e. the water from the septic tank gets pumped to a separate peat based tank for final treatment. This water is being pumped away so the septic tank isn't blocked. The problem is surface water is flooding the tank. I had 3 land drains installed by a builder but they obviously aren't doing the job.

So will my original suggestion work or not, i.e. try to extend the manhole above surface level to keep the rain water out???

Toilets are all backed up now and its getting smelly:eek:

It would relatively easy to raise the manhole, all you'll need to increase the chamber height is mortar and 4" solid blocks and re-set the frame+lid on top. This will be an immediate remedy but you'll need to determine a more permanent long term solution. Apart from assessing why 3 land drains are failing to cope, it does suggest that perhaps there is a high water table at near the position of manhole etc or more worryingly, it might be a natural flood plain.

bauderline

To address the immediate issue of the drains backed up you can call one of the local waste disposal firms that empty septic tanks. It is Clearway up North but look in your local yellow pages for a local firm. They will drive up with a tanker and hoover your tank(s) which should cost no more than 150 euro.

This will solve the issue for the moment but as said earlier you will need to address three things.

1. Raise the manhole cover.
2. Investigate the perculation / soakaway track to ensure its installed properly / well drained and is away from any areas that might flood. Its position should be indicated on the original planning permission.
3. By the sounds of it you will likely need to put in additional land drains that have sufficient volume to cope with the extreme weather we have had recently.

I would get comfortable with the fact that you may well be ripping up a large part of your garden to fix this issue properly and are not plagued with this for years to come.

Having said that my mother has dodged this issue for the best part of 20 years by calling out clearway twice a year.....

Also note, if you are on good terms with any local farmers they can use a slurry tanker to hoover out your tank and then dispose of the contents....... cough ... cough....

baud.

Kashkai

I spent the best part of the bank holiday digging out a soak pit - 8 ft wide, 6 feet long by 4 feet deep. This filled up immediately with water - its unbelievable how saturated the ground is. I then resorted to manually scooping the sewage out of the flooded AJ and emptying it into the septic tank (YUCK:eek: )which is still marginally above the surface water. The tank then pumped this excess sewage to the puraflo system down the end of the garden so this part of the system is working fine.

However, when I came back an hour later, the AJ was submerged again. There was also a lot of muck and stones in the AJ due to infiltration. I once again scooped these out and then tried to use a length of qualplex pipe to free the blockage between the AJ and the tank itself but no joy. There appears to be something stopping the sewage flowing into the tank, even after I've manually emptied the AJ and sewers myself.

I kinda resent paying someone to empty my tank of rainwater (it was only emptied 6 months ago) as this won't clear the blockage between the AJ and the tank. I've bought a collar for the AJ to at least keep it up above the water line. I'll try to dig out the soil between the AJ and the tank to see if the pipe is damaged and/or leaking and thus causing the ground to be so saturated around the septic tank/AJ. After that, I'm kinda stumped about what to do. A friend (who also has a septic tank) suggested that I get down into the tank and inspect the inlet pipe to see if its blocked. Now that thought does not appeal:(

hobie

I'm inclined to think you really have to do something about all the ground water ...

How to do this? ....... well a suitable sump complete with a float controlled submersible pump and a pipe to allow discharge of the ground water to a suitable area/drain would be my starting point ....

I would set up a 45 gallon plastic drum ..... lots of 1" holes drilled in the wall ...... top cut off to allow access ...... place in a suitable hole in the ground and up to its neck ..... lots of rocks around the outside wall of the drum ..... a layer of plastic on top of the rocks and then soil/turf to finish off ..... a 5,000 / 10,000 ltr/hr submersible pump with built in float switch can be set up to empty the drum automatically at any preset level you wish ..... a 1" or similar outlet hose will direct the water to your final discharge point ....
(in a more complex setup this sump could be fed by a series of land drains in your garden but I suspect a sump close to the problem area would do a lot to ease the problem)

Remember if you can get rid of the ground water before it gets anywhere near your tank it is essentially clean water that can be safely discharged ....

Sonnenblumen

Prosperous Dave wrote:

I spent the best part of the bank holiday digging out a soak pit - 8 ft wide, 6 feet long by 4 feet deep. This filled up immediately with water - its unbelievable how saturated the ground is. I then resorted to manually scooping the sewage out of the flooded AJ and emptying it into the septic tank (YUCK:eek: )which is still marginally above the surface water. The tank then pumped this excess sewage to the puraflo system down the end of the garden so this part of the system is working fine.

However, when I came back an hour later, the AJ was submerged again. There was also a lot of muck and stones in the AJ due to infiltration. I once again scooped these out and then tried to use a length of qualplex pipe to free the blockage between the AJ and the tank itself but no joy. There appears to be something stopping the sewage flowing into the tank, even after I've manually emptied the AJ and sewers myself.

I kinda resent paying someone to empty my tank of rainwater (it was only emptied 6 months ago) as this won't clear the blockage between the AJ and the tank. I've bought a collar for the AJ to at least keep it up above the water line. I'll try to dig out the soil between the AJ and the tank to see if the pipe is damaged and/or leaking and thus causing the ground to be so saturated around the septic tank/AJ. After that, I'm kinda stumped about what to do. A friend (who also has a septic tank) suggested that I get down into the tank and inspect the inlet pipe to see if its blocked. Now that thought does not appeal:(

You spend the whole bank hol digging and problem isn't solved, ouch. You resent paying someone may be as little as € 150.00 (I'll reckon it will cost more) but at least you would have drained the area.

You'd be mad to get into the tank but........

ircoha

U have a serious problem with the level of ground water so u need to see how far away th u will need to pump the water from the sump. If u are living in a hollow then it will be tough.

Where does the out flow from the second tank go?

In relation to getting into the tank, they can contain gases that may kill you so make sure the life cover is up to date: is your friend crazy or just lusting after ur missus: given how u spent ur weekend she will hardly be lusting after u:D

a few pics [ of the site, not ur missus] would make the discussion easier

Kashkai

It costs €400 to empty a septic tank in the North Kildare area - I paid this 6 months ago and am loath to pay it again as it won't solve the problem and I'll just end up with a septic tank full of rainwater again.

My friend suggested I get into the tank to inspect the inlet pipe from the Business end. Of course, the tank would be drained first and any gases let escape. Still its sounds revolting :eek:

The collar I bought for the AJ to keep it above water wouldn't fit even though they are all supposed to be a standard size.

So does anyone know of someone who will do a repair job on the tank, or more specifically, a repair job on the pipe from the AJ to the tank. I've tried the Golden pages but no luck. I don't want to spend an hour each evening shovelling sh!te LITERALLY!!!!!

prospect

Can you not increase the amount of time your pump is running from the house? this will empty the surface water from the tank quicker..