Ingress of Water into Inspection Chambers

[Arrenite]

I have a problem with groundwater ingress into an inspection chamber that links to a septic tank, obviously a problem. The site is pretty saturated and flat, and water I think is coming in through the extension turret on the chamber, which extends down one metre.There is a high  water table when it rains a lot. Does anyone know how to fix this problem - the septic tank is not viable with load of ground water going into it. 

many thanks

 

 

Simon

 

[nod]

Pictures 

[Gone West]

15 minutes ago, Arrenite said:

I have a problem with groundwater ingress into an inspection chamber that links to a septic tank, obviously a problem. The site is pretty saturated and flat, and water I think is coming in through the extension turret on the chamber, which extends down one metre.There is a high  water table when it rains a lot. Does anyone know how to fix this problem - the septic tank is not viable with load of ground water going into it. 

We had a similar problem with the high water table forcing water past the pipe seals into our treatment plant. I dug around the seals, when the water table was lower, and packed in around 200mm of bentonite granules. It seemed to seal very well.

[ProDave]

gI presume you have a number of risers stacked?  did you forget the bit O ring that should seal them?  I am still surprised the amount of water ingress is enough to trouble a TP.

[Arrenite]

Yes the seals went in ok. But will check to see if they are damaged when I try to rectify.

[Arrenite]

Not sure what a TP is @ProDave

[ProDave]

Just now, Arrenite said:

Not sure what a TP is @ProDave

Treatment Plant but equally just how much ground water is leaking in to bother a septic tank?

[saveasteading]

Plastic rings are supposedly formers for a concrete surround  but that is seldom done on private projects.

The seals may have distorted during backfilling.

Is it a big job to expose and reset the chamber,  and concrete it in? Wrapping it in a bentonite or similar  membrane would be belt and braces and worth considering.

 

If the volume leaking in  is signigicant then it is, indeed, an issue as the contents will flush through too quickly and mucky stuff go to the soakaway/ drainage field.

[Arrenite]

My builder is suggesting concreting in the inspection chambers to prevent water ingress. Does that sound reasonable? Thanks for your suggestions so far.

[BadgerBodger]

Typically minimum 200mm  concrete, wet cast with jacket. Or mass fill the hole. Well pokered. 
 

I suppose on a smaller ring you could use something like peckafil or even heavy duty correx.
 

Should be effective enough. If it were a concrete ring with torching that were leaking this would reduce it to damp patches in most scenarios. 

[saveasteading]

5 hours ago, Arrenite said:

concreting in the inspection chambers

Yes i do agree, thats what i was saying, maybe worded unclearly.

[crooksey]

Just get a drainage company to seal the pipes from the inside with a patch liner.