Size of Percolation Area!

Zxc01

I have a small problem with the septic tank/percolation area. I assumed almost to the end that I had a standard tank and perc area, until the engineer told me that a treatment system had to go in (bloody conditions didn’t mention this just quoted friggin numbers), , ,, we are at the sewer stage at the moment so it was almost left out, I wasn’t one bit happy as the treatment system meant that im now been billed an extra 2k from the builder.

That was all fine until the engineer then said that the guildlines state that 120meters of perc area needs to go in.. . . .. this is almost 3 times the size we had quoted for. + I have no room for 120meters.
That’s 18meter lengths X 7. This is massive.

What has everyone else done? Surly to god you don’t need to buy a second site next door just for the perc area. . . .

Im really stuck as to what to do.

Can I put in for 75m or 80m. . ??????

For clarification. There is only myself and the wife at the moment. Id like to think one or two small ones in time. But not a football team,
The house is not a B&B nor hotel.

clint_eastman

Has the Site Assessor who carried out the required Site Assessment (Perc Test) & Report for planning not indicated the recommended system and percolation area distribution size based on your site layout plan? I would have thought that this was your 1st port of call.
Whats the background, did you buy a site with planning or did you carry out the full planning and perc test?
Also, where are you based?

Zxc01

Based in Mayo,

Good ground,
Family plot
We got the planning and the test done.
What I have done, is taken the perc test results and sent them to the manufacturer of the treatment tank , to recommend a size. .

Builderfromhell

Agree with Clint Eastman. Site assessor would have specified treatment unit and percolation area design and details.
The number of occupants in the house may have been determined by the number of bedrooms or potential bedrooms. So, while it is only you and your wife that could change and planning would expect changes to be catered for now.

In view of the site restrictions a smaller percolation area could have been designed details of which would take a long posts to go into.

Contact your site assesorr, or whoever designed and submitted planning.

Supertech

The correct extent of percolation area should have been shown on your Site Layout Plan - if it doesn't fit now it never did. Also, the size of the percolation area is determined by the number of bedrooms in the dwelling and the resultant design population. Any alteration to the approved planning documentation will require a planning application. You should talk to your planning agent, and the site suitability assessor and confirm the specification outlined in the site specific report which would have been provided by the treatment plant manufacturer for inclusioin in your planning application.

PaleRider

Hello, I agree with other posts, go back to assessor. As stated by other posters, system would have been drawn into 1:500 site layout map, with all relevant distances marked out. The house location is now not as important as the location of the Percolation Area. However it may be worthwhile to go back to assessor to see if imported soil will help. It,s impossible to advise here as only the assessor knows the situation on the ground. Check on Assessor file 2nd last page Treatment Systems Details, (Conclusion of site Characterisation) to make sure the type of system recommended, is what you are putting in. You can have a situation where you have options, for instance a Septic Tank is recommended but you install a Treatment Plant, you go better. Also check with planners to find out what other systems installed near to you. Check other planning files, find out what soil conditions are like in near by plots etc.
What size of site do you have. You will require approx 240 metres square of site for what you are proposing. Regards

atech

It might be a possibility that when planning was granted that the engineer worked off the old SR6 guidelines for percolation size which was calculated from the "T" test results. (i.e. how fast the water in the trial holes dropped)

New guidelines came into effect this year (in Cork whatever about Mayo) which state the length of trench is calculated from the no. of people designed to live in the house.
3 doubles & a single bedroom means 7 people= 126m trench
or 18m * 7 runs (which is what your engineer said).

This is probably the reason why the perc area fitted on your site layout drawing but doesn't anymore.

If this is the case then you should still be allowed work from the old layout (don't quote me on that) but it would be in your (and your neighbours) best interest to try and make it as large as your site now allows.

Meningate

Thanks Atech, that is a great help, I have 3 beds and an old cess pit. There's a possibility we might want to add a two bed granny flat if needed later, so this new guide which I didn't know about makes planning it much simpler, 6 x 18m if we go for as is now or 8 x 18m if we think ahead which would seem the sensible thing to do given the work required. Am I right in thinking the max length of a perc pipe is still 20m ?
Thanks

rayjdav

Meningate wrote: »

Thanks Atech, that is a great help, I have 3 beds and an old cess pit. There's a possibility we might want to add a two bed granny flat if needed later, so this new guide which I didn't know about makes planning it much simpler, 6 x 18m if we go for as is now or 8 x 18m if we think ahead which would seem the sensible thing to do given the work required. Am I right in thinking the max length of a perc pipe is still 20m ?
Thanks

You will need planning to do upgrading works re treatment system. That means site assessment etc.
Max pipe length is 18m from EPA manual.