Garden like a bog - Land drain may exist? - but is blocked?

[adacom]

house was built 5 years ago - back garden slopes up from rear of house - garden mainly turf - area of garden nearest house like a bog

was not always so - first couple of years was fine - next door neighbor has dug down and found a land drain - his was just in a trench back filled with builders rubble and clay

house is one of a row - we believe that the land drain runs along the back of all the houses and exits into a main drain lower down the estate

i am currently digging a couple of slit trenches to find the drain in my garden

assuming it is there and is in the same state as me neighbors then cleaning it and filling the trench correctly may be enough

but i am worried that the pipe may be blocked further down the run - i cannot put a soak away - well don't want to - so is it possible to connect a land drain into the sewage system - i have worked out the sewage and top water underground pipework and it is a common system

i could connect into a main manhole or break into a run with a y connector but don't know if that would be allowed

thanks in advance for any help

tony

[Pablo]

Several things could be at play here. Firstly your drain may be at fault to a certain degree. If it's been done correctly it should be easy to find as the gravel should be only 100mm below the surface. Other things to consider are that the weather over the last 5 years was 3 years of good summers and 2 years of the worst on record.The amount of rain we've had will give most lawns a hard time. If you walk on the lawn when the soil is wet then it will compact and not allow the water to pass into the subsoil. Likewise if the lawn is 5 years old it will have been installed around about the time of that heatwave which bakes the soil and makes it harder to pass the water through again. To keep a lawn draining freely you may need to fork it and topdress with sand. Core plugging isn't deep enough but does help to get oxygen into the soil. If during dry weather you can't see the yellow grass lines of a drainage trench chances are you don't have any.

[adacom]

thanks - all interesting - but i think it is just bad workmanship in the first place - as i said my neighbor has found the drain on his land and there is no gravel infill just site rubbish and clay - so i think all the small holes are blocked

add to that that as with any new house the water table is ruined - all the original topsoil and subsoil was scraped off and we have 4" of poor topsoil on clay - so the water sits on the clay - when the land drain was clear i guess it coped - but now we are growing water plants not grass in that area

i am guessing that once i find the drain and clean or replace a section and fill the trench correctly i will be ok - well certainly better - but its what happens lower down the row that is bothering me - short and long term - most of the houses are suffering the same fate - some will buy wellingtons others will cure it - but if any of them decide to dig and block the drain then all above them will be in a mess - hence my question about connecting into the 'normal' drains that are in my garden - i have at least 3 manholes i can connect into and various pipes but they are all sewage rather than topwater as there is a common system

[Pablo]

Best not to leave it your neighbours hands. Personally I would bite the bullet and install tottally new drainage run it through a slit trap and then into your storm water system. it's a fairly common procedure and I think it's covered on the main site. Would suggest you wrap the pipe in membrane that way you prolong it's working lifespan and it won't silt up. Now is the best time of year for establishing sown lawns if you get a weather window.

[adacom]

thanks - will have to do a bit of reading - not sure what a slit trap is but will be finding out

connecting into storm water system - hmmmm - do i have that - all the toilet - sink and top water outlets connect into a commom system - i have a couple of manholes in the garden - the plastic type below with blind inlets - can i just connect into one of those

[Pablo]

Unless you have a combined system you should have a separate rain water and sewage system. Open all the man holes up and pour buckets down you drains to see which pipe it uses then likewise flush the toilet and see which one that uses. If they go down different pipes then it's a separate not combined system. The pipes that take the water from the drains are your storm water and thats the one to connect to. If it's a combined then just connect to the handiest one.



Edited By Pablo on 1222284414

[adacom]

thanks - its a combined system - have already done what you suggest

i will just double check we are agreeing

there are 3 toilet outlets - each one goes into a seperate man hole - all are connected together - on 2 of the manholes the water from the roof guttering also connects - so i am saying that is a combined system - they all then go into one drain which wanders off next door for his systems to connect into and so on down the estate

so to check with you - if i have a manhole with blank inlets can i just connect a land drain into one of them or do i need to put some sort of trap in to stop any stench coming back up the land drain

sorry if all this sounds basic but i am learning as i go

[Pablo]

Go ahead and connect into the blank. If the pipes are deep then it's simpler to bust a hole into the side wall of the chamber rather than digging all the way down. Push the pipe through the hole then plug any gaps and backfill with some lean mix concrete. Don't worry about smells thats an old wives tale.

[adacom]

thanks - have dug a trench up the garden to try and find the land drain and so far have found nothing - if its much further up then it is useless anyway as the land is rising so starting again would seem a good option

assuming i do that and allowing for the fact that the ground is rubbish - 4" of topsoil on top of compacted subsoil which is about 15" deep - which is then on top of good yellow clay - how deep would you sink a new system

i think the water is just passing through the soil and sitting on the compacted soil - thats why every thing is so boggy - may well be wrong

so i would hope to just dig down to the clay and sit the drain on that - well on the black matting on top of the clay