Aswaflow percolation not working any more

Manuel

Hi,
I have an Aswaflow SBR Effluent Treatment System in place for 10 years.

About two years ago I noticed that the three 60ft "prongs" of my percolation area, which had up to then always had lush dark green grass growing over them at 3 times the rate of the rest of the back lawn, had started to fade and then had yellowing, and eventually dead grass above. Meanwhile, back up at the manhole around the junction at the top of the percolation area, the grass was thriving in the same way that it used to be all along the three prongs for the previous 8 years.

Now even I can figure out that the percolation is not working any more.

Now, the plastic cover at the junction is getting lifted - presumably by gas/air pressure - unless I sit a 4 inch concrete block on top of it. I've never actually seen it lift before my eyes, but I've seen it up on a number of occasions, and that then coincides with the immediate surrounding area being soaking wet. Hence the ugly concrete block now sitting on top of it to keep it down.

I've had out to the house Molloys, my local plumber, and even the man who dug out the percolation area for the (now ex-)builder at the time .... but I still have no satisfaction regarding what I should do.

The consensus, insofar as there has been one, is that the percolation holes have become clogged and I need to get the whole system "jetted". I got a somewhat reluctant quote of 130 Euro from a man who does the jetting, who over the phone didn't even seem confident that this is what I need to do.

Now I have no problem spending 100 Euro if it fixes the problem, but I'm on here hoping that someone out there has experience of this or a similar issue, and managed to get it resolved somehow.

The Aswaflow itself is working fine, no alarms or anything, which is why Molloys haven't been much help. The guy who dug it out confirmed that it is the recommended piping, and thinks it's just that "gunk" has clogged up the holes over the years. The land is fine, no issues with drainage, level, etc and as I said it worked like a dream for the first 8 years it was in place.

Has anybody seen this issue resolved by "jetting" to free up the pipes and get the percolation back working again? I have a power-hose which I could try myself, but I'll only be able to get the nozzle barely in to the top of the 3 pipes. I'm presuming the man who would "jet" it for me has specialist equipment that could reach well down into the pipes.

Any advice appreciated.

Many thanks,
/M.

Metric Tensor

Hi,

It does sound like the percolation pipes are no longer operating effectively and may even be clogged. The lifting junction box cover especially with the surrounding area being wet could be a sign of leakage/ "percolation" occurring at that site because it is not percolating through pipes.

A few ideas and thoughts:

1. Percolation pipes are meant to be turned up at the end to allow inspection and rodding - is this the case. Can you look down the end or get a sewer rod in there? Rodding the pipes would be step number one for me but it requires a percolation system/area with access both ends - this is not always put in - but should be!

2. What type of "percolation" pipes did you use. There was a lot of soft yellow plastic land drainage pipe wrongly used for this purpose for many years - this could be part of your problem. - Not really helpful to your right now but could help identify the problem

3. Assuming you have rigid percolation pipes are they slotted or do they just have holes - also they should only have holes at the bottom. Holes tend to clog quicker than slots- Also not really helpful to you right now but could help identify the problem The general wisdom is that over time many percolation pipes clog at the holes - but this usually starts at the holes nearest the distribution box rather than furthest away as it seems in your case.

4. The percolation pipes leave a distribution box somewhere - this is probably the junction box that you see the lid lifting off. Open it up and see if the treated effluent is flowing out the percolation pipes. If the openings for the percolation pipes are completely submerged then they are blocked. This could be by build-up of organic matter on the holes/slots or ingress of debris and material from outside the pipe if the percolation area was not installed correctly.

5. If you really want to see what's going on I'd get a local mini-digger driver to go 2/3 of the way along one of the pipes and dig it up to see what's happening. If it's a proper rigid pipe you'll have to cut it open to see. Also be careful not to get clay/silt mixed in with the pea gravel for your trench.

6. Jetting the pipes might work:
a. It might not clear the pipe if the end is closed and it's completely clogged.
b. It might not reopen and clogged holes.
c. It might shoot through the holes and create preferrential flowpaths in the surrounding percolation trench.
N.B. I have never seen this done so someone with more experience than I might be able to tell you if it's realistic/OK

7. Realistically your long term solution is most likely to install a new percolation area. Do you have room on your site for this? This would involve installing new percolation pipes and trenches (get an engineer on board to make sure it's done right) and connecting them to the existing distribution box. It's not a huge job if you have the space but obviously a little costly.