How to stop water running outside of PVC pipe?

[bigbird21]

HI, I installed agi pipe to fix a boggy backyard problem that worked but unfortunately I have noticed during a downpour that some water is running along the outside of the pvc pipe connected to the grease trap and coming in around the sides of the pipe within the greasetrap.

I feel the agi pipe trench the gravel underneath is allowing the water to hit the pvc pipe and following this smooth surface to the greasetrap.

We have a clay layer about 30cm below & seems to be clay the whole way down, I think this is the problem

 

[EricL]

Hello @bigbird21 

Your agi pipe installation looks ideal. You mentioned that your agi pipe links to the PVC pipe? In what manner are they connected? Did you use a proper joiner or was it just pushed inside the PVC? If the gravel layer is lower than the PVC, then it could cause water to travel towards the PVC pipe and pass through its surroundings. Is it having a negative effect on your drainage? Is the PVC cemented in or is it just buried in soil? Was there a specific repair you wanted to apply to the drainage?

If you have any other questions we can help with, please let us know.

Eric

[bigbird21]

 

 

 

Hi Eric, the agi pipe connects to unslotted pipe that runs down the paddock, connected with the joiner supplied that pushes over the corrugations of the black pipe.

The pvc connected to the greasetrap is in close proximity to the ag pipe. This pvc runs to the septic. The water is somehow running in the vicinity of this pipe and leaching through around the pvc into the grease trap.

[MitchellMc]

Hi @bigbird21,

I’m curious about the grease trap and its role in your subsurface water collection system. Typically, grease traps are used in wastewater systems rather than stormwater drainage, so understanding how it fits into your setup might help us provide more accurate advice.

As Eric mentioned, slotted ag pipe is generally installed directly on the soil at the base of the trench, with the aggregate placed on top. If there’s gravel underneath the slotted pipe, water may be filtering through and travelling along the bottom of the trench instead of being captured by the pipe. Could this water you're seeing be following the base of the trench and finding its way to the grease trap?

If you can share more details about the grease trap's purpose and whether there's aggregate beneath the pipe, we might be able to suggest some adjustments to improve the drainage. 

Mitchell

[bigbird21]

Hi, the greasetrap is a sepeerate system but it seems since installing the agi pipe some water is some how working it's way to the around the pvc that drains the grease trap to wasterwater. 

Yes there is aggregate below and above the agi pipe. In my research I thought agi pipe had to be done this way and I'm sure the directions on the slotted pipe also suggests this

[MitchellMc]

Hi @bigbird21,

50mm of pipe underlay filter material is used to level out the surface beneath the pipe. However, if your pipe is not on the bottom of the trench, then water will sit in that 50mm layer, which could potentially be the issue with it finding its way into the grease trap. 

Are you able to seal the connection between the PVC and the grease to prevent water from entering it?

Mitchell

[bigbird21]

Yes I thought about sealing it but was worried if it would create a void of water in that area then.

Yes the agi pipe is on the bottom of the trench as had to be dug deep to get slope so it's about foot & half below ground level at that section 

[MitchellMc]

The void of water might need to be addressed separately @bigbird21. We'll need to determine why it's ending up there. Regarding sealing the grease trap, I would imagine there should be a solid connection to the pipe that takes it to waste.

Mitchell

[bigbird21]

Solid pvc 90mm sits within the precast concrete hole of the greasetrap then joins the wastewater I think its 100mm  pvc.

I had dug it up and replced it a few years ago as a rat must've worked it ways up & chewed the pipe.

I could seal where it is coming through within the trap..

[MitchellMc]

I would advise you do so with something like Sikaflex 11FC, @bigbird21. However, it would be best to also seal on the outside of the connection, if possible.

Mitchell