The Brew Cabin

This is my first post but I have been reading - here and at Paving Expert - for hours, and I cannot adequately express what a superb facility this is and how special a person, professionally and personally, AJ must be. So thank you. Now to business...

I moved into a new house 6 months ago and although its septic tank is in good order, the soakaway from it isn't working properly. There are small puddles of stagnant water standing on the lower reaches of the 'lawn' approx from 4 to 8 metres away from the final chamber of the tank. I have had an estimate for rebuilding the drain (was it 'wishbone' or 'fishbone' or herringbone'?) and it runs into several thousand pounds. But you can't really put a price on eliminating human waste from the lawn surface! But the real concern for me is that this is a really heavy clay site - the clay is rumoured to be at least 10m deep - and I have been alarmed by the warnings on your soakaway page. If it ain't going to work ever, I will keep my money dry at least.

But is there no workaround? Surely the local environment officers would want to step in if they thought that human waste was not been properly disposed of? Or if there was a risk of it seeping into land drains... Thanks for any help you can offer.

Simon

One of the great lapses in Building Control is the lackadaisical attitude to septic tank installation by the so-called inspectors. Either they can't be arsed or they don't understand the problems involved, but I have seen dozens of jobs where the leach field has been installed over inappropriate ground, or it's been too small, too shallow, or, as in one case, connected up to the back of a road gully!!

Your contractor is, ultimately responsible for calculating the leach field requirements, but these calculations should be (but often aren't) checked on site by the BCO. Too often they accept soil permeability values that have been dreamt up or culled from a text book, with no actual on-site testing.

In your case, it may be that you need a much more extensive leach field, with deeper dispersal drains (Herringbone, if you wish) and possibly a need for sand drains to bypass the clay layer and connect to lower, permeable strata.

If this a new new house, as in newly built, then get the builder/developer to come back, and start threatening them with the NHBC and Building Control. However, if it's only 'new to you', then you'll probably need to bring in a drainage consultant to investigate the site and come up with a solution that will probably run into several thousands of pounds.

I wish I could tell you there's a cheap and simple solution, but there isn't. On extensive clay sites, the only real option is usually a massive leach field with attenuation tanks - you need pockets as deep as the septic tank, I'm afraid. :(