Treatment Plant Location

[Pasty]

We are just finalising our split level house design but have not worked out where to site the treatment plant. The topography of the site (severe slope and trees) is very challenging for the build and provides only one possible gravity fed option though it is right on the 30m limit for emptying.  We have a couple of easier options that are at a higher elevation than the house and would obviously need to be pumped.  Can anyone offer experience of using
a pumped option?  Concern is mainly noise but also reliability.

[ProDave]

This would be a raw sewage pump if I understand correctly, as it would be pumping from the house up INTO the treatment plant?

 

I would really try and avoid that if you can.

 

A pumped system needs a holding tank. Does that not have the same distance constraints as a TP?  i.e. if you can fir a pump station there, you can fit a TP there?

 

Care to post a site layout plan?  if you can get a gravity option, I would.

[joe90]

+1 for gravity if possible, pumped = more expense and maintenance/breakdowns. 

[Pasty]

Thanks both.  The pump would be required to move raw sewage from the house into the treatment plant.  Will see if we can get a viable location for a gravity setup to work.  Will report back.

[Crunchynut]

I pump into my sewage treatment plant. It’s been installed 2 years and has been faultless. It is silent in operation. In theory, in England at least, the tank should be big enough to take 24 hrs of waste in the event of a power outage, but when I discussed this with our BC they were clueless and didn’t care on the issue. My tank would take 18 hrs worth of output in normal use. I have a timer that sets it to pump for 5s every 40 minutes. It doesn’t sound much but these pumps are beasts and 5s is about 30L. That means the treatment plant receives a nice rate of input throughout the day rather than heavy flow at bath time (for example). This is a benefit to the tank. Also if cleaning agents are held in this way then they have a bit of chance to neutralise / dilute in the pumping tank.

 

So, that’s my experience. It’s better without, obviously, but don’t discount it as being too bad a thing if it simplifies the rest of the install.

[saveasteading]

22 hours ago, ProDave said:

pumped system needs a holding tank. Does that not have the same distance constraints

No, because it's purpose is entirely to hold a few days of waste until a pump or the power is fixed

But it will cost as much as the digester.

The bco not understanding or caring, and letting you omit a holding tank with duplicate pumps,  would be a very big risk to take.....and wrong because of potential  mess in your garden.

[MortarThePoint]

On 07/04/2024 at 11:22, Pasty said:

30m limit for emptying

 

Is that 30m set by regulations or looking at local emptying companies? If the later, you may just be able to buy a length of compatible hose and store it for whenever they come.

[joe90]

2 minutes ago, MortarThePoint said:

Is that 30m set by regulations

IF I remember correctly that was a regulation when I installed mine.

[Crunchynut]

59 minutes ago, saveasteading said:

The bco not understanding or caring, and letting you omit a holding tank with duplicate pumps,  would be a very big risk to take.....and wrong because of potential  mess in your garden.

 

Maybe, but the risk is low. No lives are going to be lost.

 

If there is a power outage then normal life goes on hold. No washing machine, dishwasher, shower, cooking etc etc. so our  1000L a day output would dwindle, and if it became a problem we would jump ship and squat (no pun intended) somewhere else.

 

I’m in the countryside but not anywhere remote or exposed, and in 25 years here we’ve never been without power for more than half an hour. So not ideal but very low risk in my case. 

[Kelvin]

We had holding tank at the previous house shared between 8 houses. This was due to the distance to the main sewer. It was oversized which caused us no end of grief as the tank only pumped when it was full enough. The problem arose that the top would form a crust and the pump then displayed an error and stopped pumping. We solved it by simply lowering the level that the tank would be pumped at meaning it would pump more frequently. It was quite dear as was the pump control system.
 

The other issue we ran into was lenders trying to treat it as a septic tank. This caused significant delays for some of the owners when they sold their houses. I realise your situation is different but worth being aware of some of the issues that can arise. 

Edited April 8 by Kelvin

[saveasteading]

1 hour ago, Crunchynut said:

the risk is low. No lives are going to be lost.

Agreed. But better to find a gravity solution if you can. 

Perhaps phone your local sewage pumping company to see what distance they can pump, then your bco might be happy with that.

Tell them the height it must rise as well as the distance.
The only mandatory regulations are the ones in green boxes at the front of the  document. that probably doesn't mention 30m but will say it has to be pumpable...you'll see I haven't checked.

In reality it doesn't need pumping out very often (or at all) if it's a good make.

[Crunchynut]

I agree gravity is best if possible.

 

Though if there was a long power outage the sewage treatment plant would soon be in difficulty and that’s a different world of pain. In fact, being able to store for a while in a pumping station would prevent ‘not quite treated enough’ effluent flowing out of the stp if it has been without air for a while. Everything’s a compromise at the end of the day.

[saveasteading]

57 minutes ago, Crunchynut said:

if there was a long power outage the sewage treatment plant would soon be in difficulty

Not really. Not over a few days anyway. The 3 chamber types do a pretty good job without the agitation or oxygen.

I've run one on a site for 6 months without power. I didn't get what came out tested but it ran visually clear and did not smell.

That only had site toilets going into it, no washing machines or showers but that might even have reduced the load, and certainly diluted the contents.

So if you recognised the power issue and reduced the stuff going in, then only that amount would come out, and all from the 3rd chamber which has no solids in it.

I can't comment on other types as I haven't used them and am not inclined to. 

[kandgmitchell]

6 hours ago, Crunchynut said:

when I discussed this with our BC they were clueless and didn’t care on the issue

Well it isn't difficult for them as the AD to Part H says:

 

Pumping installations
2.36 Where gravity drainage is impracticable,
or protection against flooding due to surcharge
in downstream sewers is required, a pumping
installation will be needed.
2.37 Package pumping installations are
available which are suitable for installation within
buildings. Floor mounted units may be particularly
suited for installation in basements. These should
conform to BS EN 12050. Pumping installations
for use inside buildings should be designed in
accordance with BS EN 12056-4.
2.38 Package pumping installations suitable for
installation outside buildings are also available.
Guidance on the design of pumping installations
for use outside buildings may be found in
BS EN 752-6.
2.39 Where foul water drainage from a building
is to be pumped, the effluent receiving chamber
should be sized to contain 24-hour inflow to
allow for disruption in service. The minimum daily
discharge of foul drainage should be taken as
150 litres per head per day for domestic use.
For other types of building, the capacity of the
receiving chamber should be based on the
calculated daily demand of the water intake for
the building. Where only a proportion of the foul
sewage is to be pumped, then the capacity
should be based pro-rata. In all pumped systems
the controls should be so arranged to optimise
pump operation.

[saveasteading]

11 minutes ago, kandgmitchell said:

it isn't difficult for them

What we understand is easy , what we don't is difficult. 

I've looked up 1m3 systems and they are cheaper than I thought as they don't seem to need double pumps. £1,000 ish. plus installation and a lot of pipe.

It would be much better to kick in 'little and often' than to chuck the whole contents up to the top so worth looking into that.

But i'd still try for the downhill digester.

[Pasty]

re Is that 30m set by regulations or looking at local emptying companies?

 

I also thought this was the regulation but stand corrected as Scottish Water quote 25m-40m (with up to 4m difference in level) and another company suggested 50m.