Waste and surface water treatment

[pauldoc]

I back!

hopefully someone out there can help me

so I have done the percolation tests and have a Vp number of 28

On the basis I have a 7 person capacity treatment plant the calculation is

28x7x0.2 (0.2 is the figure used for treatment plants)

so roughly an area of 40m2 is required for drainage field.

my question is how do I calculate the linear metre of pipe needed?

the info I have found states you can have a trench 300-900 wide and that is what is used to calculate linear metres.

so am I right in thinking 40m  divided by 0.3 (300 trench) = 133 linear metres!
and 40m divided by 0.6 = 66m is this correct?

I have also seen differing info on how far apart the pipes should be- either 1m or 2m

this sounds like a huge space needed to me

i have spoked to Graf about their tunnel system.

This only takes up an area 3x4.5m using 6 ‘crates’

however they say that a permit from the EA would be required as they are not approved?

this system looks a lot cheaper and quicker though. 
My issue if I go with this route is that they need to be installed now before a permit is issued so a certain amount of risk

thanks in advance

paul

 

[Oxbow16]

6 hours ago, pauldoc said:

my question is how do I calculate the linear metre of pipe needed?

the info I have found states you can have a trench 300-900 wide and that is what is used to calculate linear metres.

so am I right in thinking 40m  divided by 0.3 (300 trench) = 133 linear metres!
and 40m divided by 0.6 = 66m is this correct?

 

 

That's all correct

 

6 hours ago, pauldoc said:

I have also seen differing info on how far apart the pipes should be- either 1m or 2m

 

 

I think it's 2m.  Where have you seen 1m?

[pauldoc]

I have seen it on ‘specialist’ websites. I have done so many searches I can’t remember which ones now! But will try and find one.

also when I have spoken to companies who sell the drainage products they tend to all have differing answers as well.

one company who I actually felt were very knowledgable said you can infact install specialist fowl water crates. (He sold them) and his reason was that the info in the regs was ‘guidance’ which I have to agree that is exactly the word they use in the regs text
In building regs it states 2m distance. 

 

[Oxbow16]

1 hour ago, pauldoc said:

when I have spoken to companies who sell the drainage products they tend to all have differing answers as well.

 

 

 

I found the same.  Not necessarily with your specific questions, but with other questions I had RE septic tanks, drainage fields, what pipe to use, etc etc.  Answers were very contradictory.  Seems this happens more and more in all walks of life the older I get!

 

1 hour ago, pauldoc said:

one company who I actually felt were very knowledgable said you can infact install specialist fowl water crates. (He sold them)

 

"He recommended + He sold them" = Well, I'm sure you can work that equation out   

 

Are you talking about:  

 

https://www.septictank.co.uk/

 

Avoid if so and disregard anything he tells you!  Just look through his site and you'll see how spurious many of his claims are.  

[pauldoc]

Yes that was one of the sites!
Although I did actually speak to him and he was helpful and didn’t try to sell me anything at all.

he was quite sympathetic to my cause with all the different info out there 

I have also seen ezy drain pipes on a number of sites and these replace the need for gravel bedding and covering. Look easy to use but again not what the regs suggest.

I just want something to last a lifetime so to speak and be problem free.

If you find the calculation for pipe length required it would be much appreciated. And if I find out in the mean I’ll be sure to post answer on here

[Oxbow16]

It's good to hear he was helpful.  And I have found some of his videos informative.  But some of his info is plain wrong.  

 

Calculation for pipe length...  You were right in what you said earlier: 

 

18 hours ago, pauldoc said:

the info I have found states you can have a trench 300-900 wide and that is what is used to calculate linear metres.

so am I right in thinking 40m  divided by 0.3 (300 trench) = 133 linear metres!
and 40m divided by 0.6 = 66m is this correct?

 

That's how to do it.  

 

10 minutes ago, pauldoc said:

I just want something to last a lifetime so to speak and be problem free.

 

 

They say that all drainage fields have a shelf life.  So I guess whether it will last a lifetime depends on how old you are  

 

One of the things I read about with interest was having two drainfields with a means to switch between the two.  Have one running for 5 years or so, then switch to the other for 5 years or so.  Any biofilm build up in field one is then broken down and consumed whilst it is in the rest phase.  Downsides...  Twice the amount of space needed, twice the amount of work and materials needed, and - depending on how old you are and how long you intend to stay in a place, it might be just as easy to do one and replace when it fails...

[pauldoc]

1 hour ago, Oxbow16 said:

Calculation for pipe length...  You were right in what you said earlier: 

That's how to do it.  

I’m just having trouble how big it will need to be

On the flip side the Graf system is so much smaller. 

this would also allow for putting in 2 field as I think I will have a problem putting in just one on the calculations I have !
when I say lifetime I know what you mean but the existing one that was on the site had to be 40 years old and had no issues at all and was much smaller

Quote

 

 

They say that all drainage fields have a shelf life.  So I guess whether it will last a lifetime depends on how old you are  

 

One of the things I read about with interest was having two drainfields with a means to switch between the two.  Have one running for 5 years or so, then switch to the other for 5 years or so.  Any biofilm build up in field one is then broken down and consumed whilst it is in the rest phase.  Downsides...  Twice the amount of space needed, twice the amount of work and materials needed, and - depending on how old you are and how long you intend to stay in a place, it might be just as easy to do one and replace when it fails...