Percolation Test Clarification

Luuca

Have been applying for PP since last August on half-acre site with 3 quarters road frontage. The council decided to change the entrance onto the main road and want the Percolation Test done again for clarification purposes. The last time they passed was June 2000. At the moment the holes and the land is full of water, the site is on the side of a large hill. The due date for the Percolation application to the council is the 1st of March. Are there any machines I can use to drain the holes? Can you re-apply if they fail? I would appreciate any suggestions you may have. (I’m in Offaly by the way)

Best thing to do would be to dig fresh holes & cover to prevent rainwater from entering.

Do they need a retest because the percolation area has been moved to accommodate the change of site enterance?

sydthebeat

firstly, new holes are a must!!... cover in the old ones...

dig them as high up the hill as possible to make sure the invert of the test holes are over the water table level. plus, if the water table comes to withim 1.0 m of the top of the water table test hole, it could mean an automatic fail and an automatic refusal of permission.

Luuca

The Council wanted a new test carried out because the new site entrance is located where the holes were orginally tested. After 18 queries they sent out this is the only one that came back for clarification. These holes are only new holes dug before Christmas, getting them pumped on Thursday and covering them, hopefully the council will test them next week - I think the water table is very high on the site, there is quiet alot of water running down the hill through my site at the moment.

How many times can apply for a Percolation Test on the site

sydthebeat

do you realise what you are trying to do is fundementally wrong.

what do you do if you get permission, install an ETS and in the first wet winter your back garden is flooded with your excrement???

if a site is unsuitable for the safe disposal of effluent then its unsuitable.

can you not move the location of the holes to an area of the site that will pass???

and also take note, as i posted above, if the water table is within 1.0 m of the ground level, which would mean the test holes are flooded as well, the test is an automatic failure and probably will result in an application being automatically refused.

Schooby

what ever the source of the water filling the holes (surface or ground water) you need to figure that out and the solution to it out before you design whatever wastewater system you are going to use.

the water filling the holes will fill your proposed percoaltion area and cause it to fail unless you design in a solution to it before you construct.

if the water ingress is seasonal as seems to be implied by your reference to the dates, maybe you need to consider using the toilet in work/neighbours etc for the winter each year or face having a poo pond garden every winter.

this is worth getting right at this stage, it will come back to haunt you if you don't.

do the test in the area where the percoaltion area is proposed otherwise you are not necessarily designing a system to suit your site.

employ someone who can carry out a site assessment to the EPA 2000 standard and design a system based on the site assessment, if this is done right the council can't argue with it.

harrovian

Still reeling 8 months on with Offaly Council as we lost over a €2000 in a failed bid to get a passed percolation test from their engineers (for those of you not offay with Offaly's procedures you apply for a percolation & they send one of their engineers within 6 weeks & they usually arrive at the latter part of the 6 wks) anyway long story short site .75 acre sites either side had passed tests. site had advantage as it was sloping, good & dry until we dug holes & we then had a non-existent summer and within 6 weeks had 2 very large water full holes!!! (they were covered but the rain kept coming!). Naturally enough it failed so applied again another €200 to Offaly + other associated costs more holes dug another 6 week wait another partially water filled set of holes another fail. What annoyed us most was the fact the engineer actually noted ; no obvious sign of vegetation to suggest poor drainage but unsuitable for a dwelling. So we wrote site off and located a new one but found out in Dec that the land owner in Offaly got planning on the site with percolation holes in same place as our number 1 test!!!! so get a pump going quick!!!

sorry where are my manners! Obtained planning last wk for 3500sq ft half dormer! newbie to the board but not a newbie to selfbuilding about to start selfbuild number 3 in Westmeath:D bring it on!

loughdergjunkie

Luuca wrote: »

The Council wanted a new test carried out because the new site entrance is located where the holes were orginally tested. After 18 queries they sent out this is the only one that came back for clarification. These holes are only new holes dug before Christmas, getting them pumped on Thursday and covering them, hopefully the council will test them next week - I think the water table is very high on the site, there is quiet alot of water running down the hill through my site at the moment.

How many times can apply for a Percolation Test on the site

Syd is correct. Aside from being disengenuous, it will be very obvious to the inspector. Wouldn't really paint you in a very good light for a future application. The more times you carry out unsuccessful tests on a site, the more you are proving that it won't work. Relocation to higher ground sounds like a possible option. But if there's that much water running through the site,you might have to reconsider. Did you say the site had permission in 2000?

Luuca

The percolation test passed in 2000, but the farm was sold and im purchasing the site from him pending PP. Anyway - the holes were drained and well covered. The Percolation test application is going to the council tomorrow so keep you all posted. Thanks for the advice and by the way - its raining socks here at the moment.

mariaWright

hi
we have just started to dig our percolation holes as part of the planning application with offaly co co. we are wondering what is the actual failure height/measure for the water level. we dont want to waste money if it will automatically fail. Our site is at a slope so we could move the location of the test area to the front of the site. any help would be greatful - thanks

The percolation tests need to be carried out where the percolation area is going, you can't test one area and put the system elsewhere.
There are systems that can pump the effluant to a raised area it that helps.

mariaWright

we know where we test the unit must go, we are just afraid at the moment that the site will fail due to the water table levels. if we move the test site to the higher ground at the front of the site and put our unit there would that be a possible solution to our possible problem. the site is sloped slightly and very peaty.

Depends on drainage in the local area really, are you near the bottom of a hill or something.

muffler

mariaWright wrote: »

hi
we have just started to dig our percolation holes as part of the planning application with offaly co co. we are wondering what is the actual failure height/measure for the water level. we dont want to waste money if it will automatically fail. Our site is at a slope so we could move the location of the test area to the front of the site. any help would be greatful - thanks

Is the assessment being carried out by the Council or privately?

mariaWright

its not a hill its a slight slope in the land

mariaWright

it will be carried out by Offaly co co

Villain

I know someone who got planning with a site water table at 30cm

sydthebeat

mariaWright wrote: »

hi
we have just started to dig our percolation holes as part of the planning application with offaly co co. we are wondering what is the actual failure height/measure for the water level. we dont want to waste money if it will automatically fail. Our site is at a slope so we could move the location of the test area to the front of the site. any help would be greatful - thanks

maria, generally a water table of 1.0m or less is not a good sign.

With Offaly co co they attach a copy of the site layout plan with the percolation test results. Therefore the planner can see if the location of the treatment system matches the location where the test was done... therefore i would only do the test where the treatment system is going.

The percolation test results will state whether the site i ssuitable for the safe disposal of effluent.... ie you WILL KNOW by the percolation test results whether you should proceed and get plans drawn up... therefore the most you will be speculating is €300 council fee + digger fee + fee for agent to prepare perc test application (or do it yourself).

If you want any clarification dont hesitate to ask....

Quazzie

I think what Maria wants to know is what is the actual flow rate as in cm/hour or so that is required for passing the test. I know there is an optimal performance rate but what exactly is it.? I've recently failed in Offaly for the flow being too quick so they recommended raising the level of the land which is now nearly done, at great expence. So I know I'd really prefer not to have to faila dn reapply again. So can anyone state the optimal flow rate required by the council?

sydthebeat

Quazzie2002 wrote: »

I think what Maria wants to know is what is the actual flow rate as in cm/hour or so that is required for passing the test. I know there is an optimal performance rate but what exactly is it.? I've recently failed in Offaly for the flow being too quick so they recommended raising the level of the land which is now nearly done, at great expence. So I know I'd really prefer not to have to faila dn reapply again. So can anyone state the optimal flow rate required by the council?

a pass rate is generally a T value between 5 and 60 (or 50 in some cases)

5 equates to a 100mm drop in 20 mins
60 equates to a 100mm drop in 4 hours
(its the time in minutes divided by 4)

anything between is generally a pass............ however..

there are conditions in which there are automatic fails... ie either the water table level or rock level is too high...

mariaWright

thanks so much for everyones advice: we had an engineer out on site today and he said we are looking at a long expensive road of raising the level of the land and a raft foundation, thats if we were lucky enough to pass percolation, which we were told is unlikely!! so it looks like its baks to land searches to find a new site. any waythanks to you all for your advice.

Quazzie

Syd. based on your figures does that mean that the best T value is 30. thus equating to 100mm in 2 hours or do they generally prefer it towards the quick side.? Does the inspector wait for the two hours or does he pour the water and come back?

sydthebeat

Quazzie2002 wrote: »

Syd. based on your figures does that mean that the best T value is 30. thus equating to 100mm in 2 hours or do they generally prefer it towards the quick side.? Does the inspector wait for the two hours or does he pour the water and come back?

yes a T value around 30 is best.

Different inspectors do it differently.... some would measure it say 3 times, perhaps every 10 minutes.. this will give an average fall for a 10 minute period and this can be extrapolated to work out how long it would take 100mm to fall....
others might measure how ong it takes say 25mm to fall and multiply by 4....
i dont know for certain, but i dont suspect many would stay on site for longer than 1 hour.

Quazzie

There goes my dastardly plan to add or remove a cupful as required in his absence

sydthebeat

Quazzie2002 wrote: »

There goes my dastardly plan to add or remove a cupful as required in his absence

i hope there was a tongue in cheek there.......

messing with the holes doesnt serve anyone any good, worst case scenario your kids could be playing football in a lawn covered in effluent.