Percolation Test

sarah88

Hi,
Recently had a percolation test done on site, The engineer told us it had failed.
Disappointing but not surprising when we visited that evening at 8pm.

One of the 300-400mm test holes had completely drained but the other two were full still full and the 3mtr one was drained too (if it was ever filled I don't know?) the spade holes also had some water left too but I did notice a pattern of the holes and the one's closer to the ditch (still outside the 3mtr clearance needed) did drain while the others had not.

Anyway we dug some more test spade holes about 10mtrs up the site from the last one's. We were asked to dig two 1ft X 1ft holes about 6ft apart and fill them up, So we did.
New holes drained 10" in 2.5hrs and the old holes that did drain managed 9" in 7hrs. My partner checked the holes at 5pm for the one's that were draining and was onsite since 3pm.

I did read on another thread that test performance values are 100mm for every 200minutes (how accurate that is I don't know but I would like to if anybody does know that would be most helpful). I have done some looking on the EPA website and my local county council for the formula but it is much harder to find then I had thought.
which is really what I would like to know!

The engineer himself came out for about 1hr 40 mins and conducted his own test with his own formula, to which I will ask him hopefully on Saturday when we do another run of the new test holes and I get to talk to him.. As my partner has been doing the dealing with him up to now.

To be clear
I am not questioning him as he seems competent and has very good communication between my partner and him, he is quite prompt in his response.
We have spoken to our architect who gave us the general guideline of 1" per hr minimum for drainage but he himself is not conducting the percolation test.
We did send the new results to the engineer and his response was "borderline at best" for the new holes.

Obviously something is off between them in the calculations they have both said. My architect is not doing test so got to believe the engineer.. Yes?
My architect also seems competent and very knowledgeable we felt that compared to others we had met on initial consultations.

Any help would be grateful

Metric Tensor

There's a range that's acceptable and holes can drain either too fast or too slowly.

You also have to average each hole over three tests.

And to complicate matters further there's T tests and P tests to carry out.

Having said all of the above it's not rocket science and it is just time vs depth at the end of the day. It's all in a document call Site Suitability Assessment:

https://www.google.ie/url?sa=t&source=web&rct=j&url=https://www.epa.ie/pubs/advice/water/wastewater/sitecharacterisationform.pdf&ved=2ahUKEwiBztXayuraAhXN6aQKHaSKASUQFjACegQIBBAB&usg=AOvVaw1-mR6Zy1fWbbKWow3-o5EQ

On the phone here but that link will hopefully work.

If the engineer is doing your tests then he's the one to listen to.