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Posted: Fri Nov 14, 2008 4:59 pm
by privacy121
1st time user so bear with me............??
And I'll probably waffle on my way to my point!!
Have read, read and re-read site (incidentally it's awesome - wife is convinced having an online affair as always on lappy come evenings instead of checking out the box!!) and am getting gist that the main man and everyone else with any knowledge is getting sick & tired of repeating the mantra about clay=hole is not a "soakaway" apart from in name as its a hole.
Accept this fact BUT when I dug soakaway, under advice from brickie (who is also a builder by trade but he's only doing brickwork as I'm doing/done foundation dig and concreting) AND building control, I dug 1.5 by 1.5 by 2m deep ensuring I cracked on through clay "cap" and I could see & feel sandy, gritty stuff. I remember every bit of it as the blasted dried out clay was so tough I could only use excavator to get to 1m deep and the 2nd metre was by hand using a kango with a clay spade and using excavator to just scoop out!!!
They both advised me to line sides with poly (i.e. the stuff used for damp proof membrane) to presumeably prevent infilltration of silt and other fine particles, etc. Fill bottom 1.5m with pea shingle and then last .5m with scalpings as I'd be eventually re-laying a patio back over it.
So after much waffle that's what I've done. BUT and its a big BUT - I'm getting worried that I should have popped a proper "chamber" or similar in there.
I can "understand" a builder perhaps advocating a quick fix i.e. pea shingle (& PLEASE if you're a builder don't take offence) but the Building Inspector? Especially as he's been so totally stringent on everything else i.e. insisiting foundations dug to 2.3m AND lined with claymaster board AND putting in a reinforced slab over the whole floor area!
Can anyone please help and advise as I'm well confused.............??
Any advice gratefully received.
Cheers
Dominic
Posted: Mon Nov 17, 2008 9:52 am
by privacy121
i KNOW this is a boring topic, covered and re-covered again and again but no posts/advice or criticisms.........................??????!!!!!!!!
Posted: Tue Nov 18, 2008 10:11 am
by GB_Groundworks
for years people have been getting away with that kind of dodgy advice as in some cases it works in really free draining material,
most building inspectors know feck all about what they're talking about and quote verbatim out the book, especially this raft of still wet behind the ears fresh out of college lot that are appearing on sites these days. gone are the days of the old boys who where engineers/builders first then inspectors btw i'm only 26 but been on sites for years, anyway should stop ranting
so having said that you have read the main site
soakaways page main site
you will have read that correct way to start with a soakaway is to excavate a test pit and check the porosity of the soil.
once establishing that the water will drain away you then need to excavate a suitable sized hole depending on the area you are draining. then line with geotextile, not visquine or poly then construct your soakaway out of a system such as aqua cell to give you the greatest surface area.
come up to near ground level cover with geotextile then finish off with soil and turf or sub base for patio
alternative you can use perforated concrete rings
or rainwater storage systems say from klargester if its just for downspout run off.
reading what you said about digging through the clay, either you where using the wrong bucket or the wrong technique. with smaller machines it can be hard but we have a clay bucket on our 1.2 ton mini and can keep going till we run out of reach. might be an idea to get a professional in.
clay bucket
giles
Posted: Tue Nov 18, 2008 10:05 pm
by Tony McC
Sadly, there's still too many people in this trade, both practitioners and inspectors, who labour under the misapprehension that a hole filled with rubble or gravel constitutes the latest thinking in soakaway design. Well, it certainly did back when Vespasian was commissioning the drainage for his holiday villa on the outskirts of Herculaneum, but we've moved on a bit since then.
Ignoring the fact that rubble/aggregate filled soakaways *always* experience settlement, they are so inefficient in terms of void space compared to the modern storm cells, which reduce the volume of excavation necessary and provide a stable, traffickable structure on completion.
Remind your builder and Methuselah from the BCO that this is the 21st century!
Posted: Tue Nov 18, 2008 10:08 pm
by Dave_L
Those clay buckets are excellent, saw ETM, local utils contractor digging up through the road and round services with one today!
Posted: Wed Nov 19, 2008 11:27 am
by privacy121
what can i say - many thanks for all the replies
however.................what should I do now??
should i re-dig gravel out and fit a proper chamber or what!!??
in a roundabout and very unscientific way i did check soil "drainage" by running a hose into hole once i was sure i was through clay cap/level and left it running - water wouldn't even sit in hole after it had been on for half an hour as it was obviously draining away - somewhere!?!?
in response to giles; don't need a professional in on machine as i'm a legend!! seriously i did half and half use a digger-driver but he was only free weekends so i did some digging during the week myself. obviously guy i used cant have been that clued up as he never mentioned clay bucket and neither did hire co. when i called them halfway through and said the clay was proving a nightmare...............irrespective i still wondered if it would have worked - you had to see and feel the condition of the clay especially for soakaway right next door to a long established tree - only way to make any inroads into it was with a clay spade on a breaker!! saying all that i've no doubt you guys HAVE seen it all as you've been in the game some considerable time longer than i have..........!!
an addition to all of above and previous posts i may get another chance to "get it right" with a new soakaway to front soon; the drainage for new extension won't *work* cos of 200mm over-bloody-specified reinforced ground slab so i'm having to dig a complete new drainage run round side of house( digging up marshalls block paving laid between, relaying it all, etc, bloody etc). at the same time i may put a soakaway in and some gullies/french drains at edges of drive as currently there is no drainage to front drive so water pools off into neighbours when it rains or just sits there, problem also exists if I wash cars, etc
and whilst i've got the digger................???
(having dug up a text area yet but believe drive is currently tarmac overlaid with loose pea shingle)
Posted: Tue Jan 13, 2009 7:03 pm
by privacy121
Hi - back again after faffing, faffing and faffing up to and over Xmas!
Two questions...............
1) Had to dig a new drain run round other side of house and connect into last IC/manhole at boundary before it all flows off to water utility co. Got the fall right and broke through precast concrete manhole at right invert level, etc. Had to carefully chip out benching and brought pipe in at angle so it joins at the "right angle" with a straight pipe. Am happy with what I've done but can I just check what anyone would recomend to "re-bench" around and over the pipe I've brought in i.e. in idiots terms; 3 soft sand, 1 part cement, etc. Do I need a specialist mortar, buy pre-bagged, etc, etc????
2. I only went and hit the bloody front of house soakaway as I dug out my drain run!!!! I'm 99% sure it was that as it was a shit-load of old bricks (and even some half bricks!!!!) encased in some crappy plastic. I've backfilled the trench as needed to access the drive for car-parking etc and have also had 2-3" of settlement above the soakaway but its obvious I've hit some luddites version of a soakaway which winds all you guys up!? So; help me in IDIOT's terms. I'll dig out old soakaway, I'll do a soil test, etc as per guidance on this site, etc, etc. But exactly what product should I be using - I've seem aqua cell mentioned and I've looked on polypipe's website. What you guys recomend - website link?
As ever grateful for advice
Cheers
Posted: Wed Jan 14, 2009 7:31 pm
by Tony McC
Benching is best done using a granolithic mortar which is much, much more durable than a building mortar. I'd certainly recommend re-benching over the new connection: the aim is to eliminate any potential snags for 'waste products'; to ensure liquid drains into the channel; and to eliminate resting/nesting spots for rodents.
As for the soakaway storm cells: use whichever you can get at a reasonable price. They are all much or a muchness - after all, they're only glorified milk crates - so see what's available at your local BM.
Installation guidance here