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Posted: Tue Oct 26, 2010 5:54 pm
by bikerman
The formula for soakaway design divides the rainfall and area by 3000. The 1000 changes the dimensions to metres but from where is the factor of '3' derived and what does it represent?
The formula calculates a significantly smaller soakaway than the BRE Digest method so is it tried and tested?
Posted: Tue Oct 26, 2010 6:09 pm
by Tony McC
That equation is one of the oldest parts of the website. I remember writing that up shortly after I was first injured back in 1997 and I never understood the 3000 part, but that was the equation used at the time for 'back-of-a-nenvelope' calculations.
I've known for yonks that it needs revising, but things have changed so much and so fast in the past decade and our attitude to SUDS that whenever I sat down to re-draft the page, it was out-of-date again by the time I got to the end, especially the components used to build soakaways.
So, earlier this year I did a deal with a major manufacturer and they have sponsored me to re-write the advice and use one of their key products to illustrate the calculations and theories involved. As I type this, they are reviewing what has been produced to date and, hopefully, we'll get summat online before the end of the year. Mind you, when we started this process, the plan was to have summat online by the end of June, so don't hold yer breff!
Posted: Tue Oct 26, 2010 7:14 pm
by shtu
As I'm in the middle of trying to sort out my soakaways, sooner the better!
Does it involve a water-and-gravel-filled hole 2ft from the foundations? No? Pity. 
Posted: Tue Oct 26, 2010 10:10 pm
by lutonlagerlout
for most 2-3 bedroom houses in the uk 1m3 at the front and 1m3 at the rear are enough
however in certain exceptional conditions no soakaway can take all the rain that is chucked at it
we had 18mm in 1 hour last week
thats a lot of rain
LLL
Posted: Thu Nov 25, 2010 9:59 am
by Tony McC
I've been wracking my brains over the design methodology in BRE65 for the past 3 days and it is driving me insane. The design examples use maths that makes no sense; you can't determine the size of the soakaway required unless you know at least two dimensions of the soakaway; the whole procedure seems designed to persuade you to buy the software package.
Does anyone have any experience of using BRE65 and if so, would you be willing to talk me through it?