percolation tests and failed sites, is there hope ?

woody1

so if your site gets a t-test time of more than 90,it fails, there is nothing to be done. according to the epa manual.. and you will be refused permission if you apply at all

however
an bord pleanala has recently overturned a refusal in kilkenny on a site with a t time greater than 90 as they found that a zero discharge willow system is suitable for such a site..

basically its a big hole up to 400 sq. m. and 1.5m deep, lined with plastic to make it watertight and filled back and then willow planted in..the willow take out the nasty stuff and the liquid evapotranspirates in the summer ..
you would pump to this from a treatment system, and it would take the place of a traditional percolation area, that obviously wouldnt be effective on such a site

so does this give hope to those of us living in the countryside that a solution has at last been found for poor sites...or will the epa, councils and whoever else get together and close this loophole ...

sydthebeat

woody1 wrote: »

so if your site gets a t-test time of more than 90,it fails, there is nothing to be done. according to the epa manual.. and you will be refused permission if you apply at all

however
an bord pleanala has recently overturned a refusal in kilkenny on a site with a t time greater than 90 as they found that a zero discharge willow system is suitable for such a site..

basically its a big hole up to 400 sq. m. and 1.5m deep, lined with plastic to make it watertight and filled back and then willow planted in..the willow take out the nasty stuff and the liquid evapotranspirates in the summer ..
you would pump to this from a treatment system, and it would take the place of a traditional percolation area, that obviously wouldnt be effective on such a site

so does this give hope to those of us living in the countryside that a solution has at last been found for poor sites...or will the epa, councils and whoever else get together and close this loophole ...

1. There is no loophole. Either the system you propose is suitable for the specific site or not. The willow system is whats called tertiary treatment and is an extra process added to the usually primary an secondary treatment. The onus is on the applicant to show and prove that the treatment process proposed is suitable for the site conditions.

2. I cannot see a system such as the willow being allowed if any of the below exists:
(a) the site is being purchased
(b) there is alternative sites on the landholding
(c) the is no significant local need shown
(d) there is a significantly high water table level ie <1.0 m

Some areas of land simply are not suitable to have effluent disposed into them....

woody1

sydthebeat wrote: »

1. There is no loophole. Either the system you propose is suitable for the specific site or not. The willow system is whats called tertiary treatment and is an extra process added to the usually primary an secondary treatment. The onus is on the applicant to show and prove that the treatment process proposed is suitable for the site conditions.

2. I cannot see a system such as the willow being allowed if any of the below exists:
(a) the site is being purchased
(b) there is alternative sites on the landholding
(c) the is no significant local need shown
(d) there is a significantly high water table level ie <1.0 m

Some areas of land simply are not suitable to have effluent disposed into them....

sorry loophole is probably the wrong word...

i agree with all of the above,
i have 3 sites from this year that would satisfy the above but all have t > 90,
from dealing with my local planning section for 8 years i know its pointless to send them in with any proposal, and i dare say if i sent them in with the mentioned zero discharge willow system then theyd refuse and send it back to me, and let the applicant go to an bord pleanala if they want to..

like i say its not quite as simple as proposing a system thats suitable or not , i wish it was ! if your t time is greater than 90 you can propose all you want, the vast majority of councils will refuse you..

sydthebeat

woody1 wrote: »

sorry loophole is probably the wrong word...

i agree with all of the above,
i have 3 sites from this year that would satisfy the above but all have t > 90,
from dealing with my local planning section for 8 years i know its pointless to send them in with any proposal, and i dare say if i sent them in with the mentioned zero discharge willow system then theyd refuse and send it back to me, and let the applicant go to an bord pleanala if they want to..

like i say its not quite as simple as proposing a system thats suitable or not , i wish it was ! if your t time is greater than 90 you can propose all you want, the vast majority of councils will refuse you..

i would argue rightly too.

Again, not ever area of land is suitable for effluent treatment, no matter what is proposed. Thats a hard pill to swallow for a lot of potential homeowners, but thats the way it is.

The councils are under pressure from DOE to ensure that ground water is not polluted (further than it already is). The government is under similar pressure from Europe under penalty of fines.

I guess its your responsibility as an agent to outline all the possible scenarios and let the clients make an informed decision.

id love to read the bords agents report on that case you've referred to above. Do you have the reference?

woody1

no sorry dont have the reference, i was told about it by another techie..
meant to look for it myself.. id like to read the detail of it as well..
ive been on some seriously poor sites that id question whether a foundation should be built on them, never mind an effluent treatment system .. so i agree with you on that point,
but ive also been on some reasonable sites that have been ruled out that i think would suit a system like this..
theres no discharge of the effluent to ground ..so once the system is installed properly , ie doesnt leak, i cant see a huge problem with it.. as youve said before obviously not gonna work on sites with high water tables.. its gonna need large sites..and more than likely clients with deep pockets..

woody1

a.b.p. reference PL10 .235826

interestingly the inspector reccomended a refusal, based on the fact that there are no national standards in place for such a system, so whilst they have been seen to work in other countries it hasnt yet been proven that they could work here, and research is ongoing..

but obviously the board overruled him , it would be nice to see their reasons for that

sydthebeat

woody1 wrote: »

a.b.p. reference PL10 .235826

interestingly the inspector reccomended a refusal, based on the fact that there are no national standards in place for such a system, so whilst they have been seen to work in other countries it hasnt yet been proven that they could work here, and research is ongoing..

but obviously the board overruled him , it would be nice to see their reasons for that

well, that would be lovely, but aint gonna happen

thanks for that ref!!

No6

Thats interesting, normally if I get a failed test we either dig again or look for a new site. Its a waste of time and money bringing an application with a failed test to planning!!

FesterBeatty

Simple - go for a raised bed system. You'll need an engineer to design it..

sydthebeat

FesterBeatty wrote: »

Simple - go for a raised bed system. You'll need an engineer to design it..

where is the effluent expected to go once it reaches the bottom of the raised bed??

that wont work without some kind of remedial action taken on the existing topography.... for example draining the whole site... and even after this work is done, you will be expected to get these areas tested again to see if they pass.

the site characterisation form simply states that a t value greater than 90 is not suitable for discharge to ground.


There is a provision in the EPA manual where wetland systems like is mentioned above may be accepted.

4.9 OTHER INTERMITTENT MEDIA FILTER
SYSTEMS
Other intermittent media filter systems may from
time to time be introduced to treat wastewater. Such
filter products could include geotextile strips and
other media that can be used to attach biofilms.
Many, such as geotextile strips will operate in a
manner similar to fibrous peat filters while others
may employ novel ways to attach biofilms. Where
such products are introduced, independent
evaluation should be carried out to verify the
manufacturer’s design loadings. Other intermittent
media filters should be followed by polishing filters.

[/I

4.10 CONSTRUCTED WETLANDS
A constructed wetland system is another option used
to treat wastewater from a septic tank ( Figure 17 and
Figure 18)5. As mentioned in Chapter 1, constructed
wetlands can be characterised by the flow path of
the wastewater through the system. In horizontal
flow constructed wetlands, wastewater is introduced
at one end of a flat to gently sloping bed of reeds and
flows across the bed to the outfall end. If the surface
of the wastewater is at or above the surface of the
wetland media, the system is called a free-water
surface (FWS) hori zo n t a l - fl ow wetland. If the
surface of the wastewater is below the surface of the
wetland media, the system is called a sub-surface
(SFS) horizontal flow wetland. As it fl ow s ,
microorganisms attached to the reeds and support
media purify the wastewater. The media can consist
of soil (free-water surface), gravel or other suitable
material. In the vertical-flow wetland (Figure 18),
the wastewater is distributed uniformly over, and
intermittently onto the media, and gradually drains
vertically to a drainage network at the base of the
media; as the wastewater drains vertically, air reenters
the pores in the media. The media used in the
vertical-flow wetland can consist of a layer of sand
overlying a layer of gravel. The sand must be
protected from erosion and piping.

woody1

syd is right if youve a high t-time like that then there is no-where for the effluent to go, and you will get ponding of effluent ( be it somewhat treated,but only somewhat ) on site, do you want your kids or your dog or whatever running around in or near that... and of course it runs off the surface and into drains and streams and pollutes the water too..
there are 2 issues really
1. can you treat the effluent ( septic tank, system, reed bed, whatever)
2. can you dispose of it .. ( percolation area, percolation also provides some treatment)

the second one is where sites fall down, the system as mentioned in the an bord pleanala appeal is a zero discharge system, there is no percolation or disposal intended.. id never heard of it before this and it sounds like an interesting method for dealing with the problem of sites with high t-values..i know that trinity are doing some research into it, hopefully it works out...

galwaytt

FesterBeatty wrote: »

Simple - go for a raised bed system. You'll need an engineer to design it..

..indeed. Saw my first-ever one of those last Friday, being pressure tested. Looks impressive, and also, yes, according to the builder, 'cost a fortune' (his words.

There again it is right on the shore of a lake........

Like everything else, there is always a (technical, engineered) way out of anything. It just brings 'baggage', that's all !

sydthebeat

just to clarify for the OP... raised beds appear be acceptable in some counties...so contact either the environmental section or the planning section to clarify this before you go spending money on the design of it.

I know the 4 counties i do most of my work in do not accept raised beds for sites with T value > 90.

woody1

the counties mayo, sligo, meath and louth ( occasionally galway ), that i work in dont accept anything for a t over 90 minutes either at the moment..and neither should they seeing as thats what the epa document sets as a limit,
raised beds are more for depth to bedrock / water table issues.. ie where you dont have the required distance between the base of the trenches and bedrock / water..cant see what theyd do for a site with a t time greater than 90..but from the sounds of it some counties are allowing it..
just to be totally clear..i work at this.. doing the percolation tests..so i wasnt really asking for solutions to the problem with the original post, i just wanted to highlight that a solution may be on the horizon for particular sites that would fail under the current code of practice....

ManFromAtlantis

sorry to jump on this thread but some people seem to know about the epa perc test.
can anyone tell me what is the design PE loading rate per day.

2000 epa code was 180 litres/person/day.

2009 epa manual ....... ?

im sure its 150 litres/person/day but its not written anywhere in the manual.

it refers to 150 when sizing septic tank.
but if you work backwards from tabels for length of trenchs etc it would appear that a loading of 180 l/person/day was used

so is it 150 or 180 what ye use. thks

woody1

c=150 x p + 2000 , its on page 19 of the 2009 document.

woody1

sorry duh ! i just saw that wasnt what you were asking...yeah id still use 150 though, although i think i read something about this issue before, il have a look and if i find something il get back to you... what are you using it for..to size a polishing filter / pumped distribution system or something like that

sydthebeat

we've always used a figure of 200 litres in assessing PE when designing for LA's.

never had any issue with it being accepted.

ManFromAtlantis

thanks for the replys.

its just i cant find anywhere that it actually states 150l/p/day or even 180l/p/day.

i was convinced it was 150 l/p/day but cant find proof or otherwise. thjs

sydthebeat

the minimum acceptable capacity of septic tanks under BS 6297:2007 is
C = 180 P + 2000.
This is the same as the formulae proposed in the 1983 version.

this is where the figure of 180 comes from.

however many groups argue that the increase in use of technology such as washing machines and dishwashers has increased this PE figure.

I would advise you to use a figure of 200 litres / person in any design.

PaleRider

MFA / Check page 19 2009 COP. C= 150xP+2000.


Woody, Ground improvement work can play a part in some cases.

Drainage to-lower water table when gradient allows.