percolation area - spec & details

sandt

hi,
has anyone got a link to the actual spec and detailing of a percolation area for a septic tank system?
as in, type of pipes, size of perforations, lengths, type of stone etc....

i cant seem to find any actual spec for it on the epa website or in the homebond manual

whilst the epa manual for single houses states-

'The most important component of a conventional septic tank system is the percolation area'.......they dont have any spec or diagrams on it!!

can anyone help?

thanks.....

Quazzie

first result on google

http://www.ambill.net/BIO_CLEANER/Percolation_Area_Design.html

Jimbo

The info you need is on page 36, Table 13 of the EPA manual:
http://www.epa.ie/downloads/advice/water/wastewater/house/epa_wastewater_treatment_single_houses.pdf.

sydthebeat

sandt...

both quazzie and jimbo have posted links to relevant planning requirements.. ie 'SR 6 1991' and 'EPA guidelines'

its up to you to find out which regulation is applicable to your particular situation...

may i ask if you are preparing a planning application yourself??
or are you about to construct this perc area and septic tank??

sandt

teah thanks for the help guys...:o...if id have spent a bit more time looking i probably would have found them eventually!

to syd, im about to construct this perc area myself maybe this or next weekend....anything else i need to know??

sydthebeat

do you not have a report on the site conditions??

Builderfromhell

sandt wrote: »

teah thanks for the help guys...:o...if id have spent a bit more time looking i probably would have found them eventually!

to syd, im about to construct this perc area myself maybe this or next weekend....anything else i need to know??

With respect, if you do not have groundworks or building experioence you will have great difficulty building percolation area to meet EPA guidelines.
To do it properly, you need a site characterisation report with percolation design.
There are many different types of percolation area.
Do it wrong and you will have one of these situations;
1. Waste water does not percolate and therefore ponds on surface. This is health risk to yourself, your family and neighbours. Council may insist you re-build as causing pollution.
2. Waste water percolates too fast anbd causes groundwater pollution. This may seep into wells, streams etc.

I suggets you call a site assesor for advice. The local council should have a list.

sandt

builder , i have a friend of mine who used to do ground work years ago is gonna give me a hand.

syd, the planning for the site was got 6 years ago, at that time i dont think site assements were as common as they are now and there wasnt one done on this site.

Supertech

If you got planning for the site 6 years ago it has now lapsed and you need to apply again.

sandt

Supertech wrote: »

If you got planning for the site 6 years ago it has now lapsed and you need to apply again.

no, planning was got 6 years ago but we had 'substatial work' done before the 5 years were up. just doing the drainage work at the minute.

RKQ

sandt wrote: »

syd, the planning for the site was got 6 years ago, at that time i dont think site assements were as common as they are now and there wasnt one done on this site.

SR6:1991 was the National standard up to circa 2005. Is there not even an SR6 Soil Test Report?
Most L.A had some sort of requirement to show compliance with SR6.

Your friend may be an experienced Ground Worker, but thats not the issue. If you haven't had a soil test done then you don't really know the T-value (SR6:1991) so you can't use tables to work out required percolation area size.

How do you know the site is suitable for a Septic tank?

If planning was granted to SR6:1991 then you should comply with SR6. But if planning was granted to EPA standard then you must comply to this standard - you can not "mix and match" both standards to suit yourself!

Penn

RKQ wrote: »

SR6:1991 was the National standard up to circa 2005. Is there not even an SR6 Soil Test Report?
Most L.A had some sort of requirement to show compliance with SR6.

Your friend may be an experienced Ground Worker, but thats not the issue. If you haven't had a soil test done then you don't really know the T-value (SR6:1991) so you can't use tables to work out required percolation area size.

How do you know the site is suitable for a Septic tank?

If planning was granted to SR6:1991 then you should comply with SR6. But if planning was granted to EPA standard then you must comply to this standard - you can not "mix and match" both standards to suit yourself!

I agree with RKQ. You should really get a site characterisation test done. The problems which can be caused by improper design and construction of a percolation area are too great. Even if your planning was gotten 6 years ago, you should always work to the most current standards and regulations. Doing otherwise is just foolish

sandt

This is a quote from our planning permission:

'The septic tank plus percolation area shall be constructed in accordance with the design and details on drawings enclosed with notification. The minimum liquid capacity of the septic tank shall be 3,500 litres in accordance with the E.P.A. Wastewater Treatment Manuals: Treatment Systems for Single Houses'

RKQ the LA (donegal coco) didnt ask for any kind of soil report to be submitted to them at all, so we have no reports on the condition of the soil.
it also says on the PP that ther perc area should be 121sq.m.

sydthebeat

sandt wrote: »

This is a quote from our planning permission:

'The septic tank plus percolation area shall be constructed in accordance with the design and details on drawings enclosed with notification. The minimum liquid capacity of the septic tank shall be 3,500 litres in accordance with the E.P.A. Wastewater Treatment Manuals: Treatment Systems for Single Houses'

RKQ the LA (donegal coco) didnt ask for any kind of soil report to be submitted to them at all, so we have no reports on the condition of the soil.
it also says on the PP that ther perc area should be 121sq.m.

Sandt,

if the permissions states "The septic tank plus percolation area shall be constructed in accordance with the design and details on drawings enclosed with notification"... then there should be design and detailed drawings on the planning file.

if not then stay as close as possible to the requirements contained in jimbos post...

Penn

sandt wrote: »

This is a quote from our planning permission:

'The septic tank plus percolation area shall be constructed in accordance with the design and details on drawings enclosed with notification. The minimum liquid capacity of the septic tank shall be 3,500 litres in accordance with the E.P.A. Wastewater Treatment Manuals: Treatment Systems for Single Houses'

RKQ the LA (donegal coco) didnt ask for any kind of soil report to be submitted to them at all, so we have no reports on the condition of the soil.
it also says on the PP that ther perc area should be 121sq.m.

If they're using the EPA Manual as the guidelines for designing your septic tank, then I'm surprised a site report was never done, as its a requirement for that manual. I don't see how they gave you a size for the percolation area without knowing the T value of the site

Jimbo

If you keep closely in compliance with the EPA manual and you have someone experienced woth you, you should be fine. Also make sure that the base of the percolation trenches are at least 1200mm above the watertable level to reduce the risk of groundwater contamination

RKQ

paddyirishman85 wrote: »

If they're using the EPA Manual as the guidelines for designing your septic tank, then I'm surprised a site report was never done, as its a requirement for that manual. I don't see how they gave you a size for the percolation area without knowing the T value of the site

I agree. How did the Council know percolation area required was 121sqm?
I wonder if the EPA would be happy with Donegals laid back action 6 years ago?

Ensure you are fully compliant with your Planning Documents and to EPA manual. Also check depth of water table ( 2100mm deep trial hole left open for 48 hours - should help)

Jimbo

RKQ wrote: »

I agree. How did the Council know percolation area required was 121sqm?
I wonder if the EPA would be happy with Donegals laid back action 6 years ago?

Ensure you are fully compliant with your Planning Documents and to EPA manual. Also check depth of water table ( 2100mm deep trial hole left open for 48 hours - should help)

Make sure you cover the hole as any rainfall will raise the waterlevel

sandt

thanks for all the advice guys much appreciated.

just a couple of things i want to check-

1. the pipe perforations - do they have to be actual 8mm holes (like drilled) or can they be done makings small 'slits' using a small angle grinder? or can you buy pipes pre-perforated?

2. do the ends of the pipe runs have to be interconnected? or vented and interconnected? or just use stop ends?

3. can you buy a distribution box? or is it just made on site using blocks? i have a feeling all the water would just go down the front pipe and not go out to the pipes at the sides???

thanks....

RKQ

sandt wrote: »

1. the pipe perforations - do they have to be actual 8mm holes (like drilled) or can they be done makings small 'slits' using a small angle grinder? or can you buy pipes pre-perforated?

Do not use angle grinder! IMO slits weaken the pipe and it tends to be crushed / buckled by weight above!
Drill holes at 3, 6 and 9 o'clock about 150mm apart like manufacturers percolation pipe, or purchase proper percolation pipe..

6m Percolation pipe is available at your local building suppliers, circa €13, ordinary 6m sewer pipe circa €8. Do not use roll of yellow land drainage pipe.

sandt wrote: »

2. do the ends of the pipe runs have to be interconnected? or vented and interconnected? or just use stop ends?

See EPA manual. Vents pipes are important. Some people join ends of all pipes and bring a vent pipe up near a boundary.

sandt wrote: »

3. can you buy a distribution box? or is it just made on site using blocks? i have a feeling all the water would just go down the front pipe and not go out to the pipes at the sides???

Buy a precast distribution box from your precast septic tank supplier. Building out of blocks isn't recommended. Factory made Distrbution boxes work - don't bother trying to make one, just buy one and know it will work.

Supertech

Holes are better sandt. I'm not sure whether or not you can buy the pipes pre perforated.Join the ends of the pipe runs and vent them, and cap the vents.
You can buy precast distribution boxes, and generally you don't use the front of the box to run a pipe out for exactly the reason you mentioned.

Penn

RKQ wrote: »

Do not use angle grinder! IMO slits weaken the pipe and it tends to be crushed / buckled by weight above!
Drill holes at 3, 6 and 9 o'clock about 150mm apart like manufacturers percolation pipe, or purchase proper percolation pipe..

I may be wrong but isn't the regulations for 4, 6 and 8 o'clock, with 8mm holes? I'd have to check to be sure though

Supertech

4,6 & 8 is correct paddyirishman85.

RKQ

paddyirishman85 wrote: »

I may be wrong but isn't the regulations for 4, 6 and 8 o'clock, with 8mm holes? I'd have to check to be sure though

You could be right paddyirishman85, I'm answering the OP without reference to books, all free advice should be researched by OP and confirmed by their Certifier.

I have said "150mm apart like manufacturers percolation pipe, or purchase proper percolation pipe.."
Either way 4, 6 and 8 o'clock would be difficult to drill on site as its difficult to visualise and drill angle of 4 or 8 o'clock on a pipe between your feet!:D

My main point is Do not slit pipe with angle grinder! You won't find "Angle grinder" in the EPA Manual Recommendations.

Penn

I was thinking so. I did my thesis on percolation areas and constructed wetlands, but I've forgotten most of it now

Penn

RKQ wrote: »

You could be right paddyirishman85, I'm answering the OP without reference to books, all free advice should be researched by OP and confirmed by their Certifier.

I have said "150mm apart like manufacturers percolation pipe, or purchase proper percolation pipe.."
Either way 4, 6 and 8 o'clock would be difficult to drill on site as its difficult to visualise and drill angle of 4 or 8 o'clock on a pipe between your feet!:D

My main point is Do not slit pipe with angle grinder!

hear hear! Seriously OP, you should follow the regulations to a T, thats what they're there for. And not following them will only lead to trouble

Supertech

The idea behind the 4,6 & 8 o'clock drill holes is so that the pipe doesn't have to be half full before it starts to drain and so that you get even consistent flow from the pipe over the optimum surface area.
Paddyirishman and RKQ are correct in what they say above about the regulations - they are based on sound practical principles all geared towards making your percolation area work to its maximum potential for the maximum length of time. If you stick by them you'll prolong the life of your percolation area and prevent problems for yourself in the future.

sandt

OK update:

local buiders providers dont stock pre cut percolation pipes, they recommended a type of twin walled pipe. its like land drain on the outside but it smooth walled on the inside. but the slits a very narrow & i dont think it would work properly so il just have to drill ordinary pipes.

i cant get a distribution box anywhere! guys who suppied septic tank never heard of them! he suggested i use land drain out of a gravel pit at the end of the septic tank :eek:

so il either have to build one or use a manhole base, not sure how the manhole base would work as the main channel is lower the the distribution channels out to the sides. so maybe building a small box from blocks would be the best option??

Jimbo

sandt wrote: »

OK update:

local buiders providers dont stock pre cut percolation pipes, they recommended a type of twin walled pipe. its like land drain on the outside but it smooth walled on the inside. but the slits a very narrow & i dont think it would work properly so il just have to drill ordinary pipes.

i cant get a distribution box anywhere! guys who suppied septic tank never heard of them! he suggested i use land drain out of a gravel pit at the end of the septic tank :eek:

so il either have to build one or use a manhole base, not sure how the manhole base would work as the main channel is lower the the distribution channels out to the sides. so maybe building a small box from blocks would be the best option??

Don't use land drains with slits. As you said you'll have to use ordinary pipes and drill as described above.

You should be able to source a distribution box somewhere. I dont think a manhole base would do.

<snip>

jimbo, please do not link to specific company products. keep all recommendations to pm only.

syd

Poor Uncle Tom

sandt wrote: »

OK update:

local buiders providers dont stock pre cut percolation pipes, they recommended a type of twin walled pipe. its like land drain on the outside but it smooth walled on the inside. but the slits a very narrow & i dont think it would work properly so il just have to drill ordinary pipes.

Try some of the larger hardwares they are fairly commonplace.

sandt wrote: »

i cant get a distribution box anywhere! guys who suppied septic tank never heard of them! he suggested i use land drain out of a gravel pit at the end of the septic tank :eek:

The premade distribution boxes are available since 1991, and using land drainage pipes will get you in trouble.

sandt wrote: »

so il either have to build one or use a manhole base.....so maybe building a small box from blocks would be the best option??

Not a difficult thing to do, either way.

RKQ

I'd have to agree with Jimbo78 and Uncle Tom!
Use proper pipe - drill your own holes if necessary, do not cut slits!

Precast concrete Distribution boxes are extremely common and easy to get. Well worth getting one as they are watertight. Building a distribution box on site would be alot more time consuming and probably more expensive. (One would fit in the back of a standard hatch back car)

Its not a difficult job to install a septic tank & percolation area in full compliance with the recommendations in the EPA manual.
It can be a nightmare if done incorrectly.

Do yourself a favour and do it right. Its so important to get it right for your health, your families health and your neighbours health.

Builderfromhell

RKQ wrote: »

I'd have to agree with Jimbo78 and Uncle Tom!
Use proper pipe - drill your own holes if necessary, do not cut slits!

Precast concrete Distribution boxes are extremely common and easy to get. Well worth getting one as they are watertight. Building a distribution box on site would be alot more time consuming and probably more expensive. (One would fit in the back of a standard hatch back car)

Its not a difficult job to install a septic tank & percolation area in full compliance with the recommendations in the EPA manual.
It can be a nightmare if done incorrectly.

Do yourself a favour and do it right. Its so important to get it right for your health, your families health and your neighbours health.

With respect RKQ, installing a Septic tank and percoaltion area is not easy. I have installed many and each had it's own difficulties. I am in no doubt that this DIY installation will be a disaster and any money saved will be lost several times over in rectifying the problem.
I have seen percolation areas installed with wrong type of stone, with pipes sloping back to septic tank, with pre-drilled holes the wrong way round.
And that's only what I've seen from visiting sites.
The country is full of mal-functioning septic tank and percolation areas causing serious polution. Polluting ground or surface water is a legal offence and if neighbours complain Council will take action.

RKQ

With respect builderfromhell Its not a difficult job to install a septic tank & percolation area in full compliance with the recommendations in the EPA manual. (I too have done a number)

I think you may be misreading my post or not fully understanding my point. To clarify I am asking the OP to install the tank & percolation area to EPA Manual - do not scrimp on materials or "try" to re-invent the wheel by trying to build a Distribution box.

I agree that a DIY installation will be a disaster and any money saved will be lost several times over in rectifying the problem.

I advise the OP to retain a professional and highly experienced Groundworks Contractor. Also find a more competent Building Supplier than stocks standard percolation pipe and if necessary purchase a precast Septic tank & precast distribution box off a manufacturer that is fully familiar with EPA guidelines and the previous S.R.6:1991 recommendations.

The EPA manual clearly states the type and size of stone, the type and length of percolation pipe, pipe centres and all minimum distances. I advised the OP that Its not a difficult job to install a septic tank & percolation area in full compliance with the recommendations in the EPA.

As the Client it is very simple for the OP to retain the proper professionals and purchase the proper materials for the job. Its not a difficult job to install a septic tank & percolation area in full compliance with the recommendations in the EPA manual.

Poor Uncle Tom

I was called to inspect a septic tank and percolation area close to twenty years ago. The builder was an old lad, very slow but very detailed and proud of his work. Manholes built by hand, beautiful smooth benching, cover tracks grouted in just so, nice falls, tee sections on pipes in tank, distribution box benched and ready, pebble stones under pipes, percolation pipes laid and vent pipes individually from the ends of each. Enough stone, straw and soil left to the side to finish the job off. Only one problem - holes in the percolation pipes were facing upward.

I resisted the urge to lol, but I told him quietly why the pipes should face downwards. He was embarrassed and explained that he had only ever put in the clay pipe percolation beds. He was/is still a very good builder and finishs a job to a very good standard, but the moral I guess is that no job is as easy as we think it will be and it's always good to get someone to give you a hand, all the better if they've done a similar job before.

sandt

Thanks for all your replies lads.

i will try and source a dist. box from somwhere!
have stone ordered (25-30mm clean broken stone) for trenches.
will prob just drill the pipes i have as im having no luck sourcing 'percolation pipes'.

couple of things to check with you guys:

do the pipes along the top & bottom (if interconnected) of the percolation have to be drilled or is it just the 'main runs'?

someone told me to be sure and connect a pipe from the bottom of the percolation area or below it to a local storm drain as it will pond eventually and the water has to get away somehow
he said the water should be clean by that stage having been filtered through the stone. im not sure about this because is the whole point of a percolation area to keep contaminated water OUT of local watercourses:eek:


thanks........

RKQ

sandt wrote: »

someone told me to be sure and connect a pipe from the bottom of the percolation area or below it to a local storm drain as it will pond eventually and the water has to get away somehow

Seems to me like you have met a real possey! Was "somebody" wearing a big hat, check shirt and spurrs on his snake-skin boots?

You seem to have got alot of bad advice from "someone", your Building supplier & septic tank manufacturer.

OP your fears of polution are correct. Please construct percolation area in full compliance with EPA manual.... I really think its time you sought professional advice.

(Who is providing the drawdown of stage payments & cert of compliance? You need to discuss this issue fully with your Certifier)

Penn

Whenever a client says "A friend of mine told me to..." I'm always tempted to interrupt them and say "Whatever your friend said, do the opposite"

If your percolation area is built to the correct standards and well maintained, it should never pond. Besides, the stones in the trench are only the first step in the cleaning process, a lot of the treatment of the wastewater is done by the soil before it reaches the watertable.

Seriously OP, never mind what anyone else says, take our advice and construct it in accordance with the EPA manual.

And its only the main 20m pipes which require holes, not the run connecting them to the distribution box

sandt

thanks lads i will keep as close as i can to the epa standards.

just one final thing!!

is it ok to use builders polythene (1200guage) as the geo textile material?
again this is what local co-op are suggesting.

thanks again.....

Supertech

No. Polythene particularly the heavier guage you mention will cause ponding in the area of the percolation bed. Use Terram, or an alternative geotextile membrane.

RKQ

I agree, a geotextile is a synthetic permeable textile material used with soil. Polythene is not permeable and is lightly to rot, crack and split over time.

Jimbo

Agreed.
The geotextile membrane is there to stop silt/sand etc flowing down and blocking the holes in your pipes- it has to allow water through.


Be wary of any advice you get from a supplier.

engineer24/7

Hi,
Stumbled across youe thread, seems to me that you are going about all this the wrong way!! you need to get a certificate of compliance for your completed house and I cant understand how you will get this if you have not consulted a professional during the construction of the PA, How can anyone sign off on it once its buried underground and how can they know it has been constructed in accordance with the regs and Planning permission, seek pro help before you close it up!