The Brew Cabin

can anyone help me the answer is probably in here some where but at the minute im not taking any thing in as ive had a few tins while going through the whole internet.im converting my back yard into a garden ive got a manhole at either end and at the outside edge in the middle i have a surface water drain that leads into the sewer.under the concrete is ia very thick layer of clay that is not draining away a single drop of water,is it possible to take away all of the surface water drain which is about 1.5feet deep and dig a trench around the remaining pipe fil it with hard core and level off the rest of the area with hard corewould this be enough to drain away water from the lawn and topsoil that i want to put down.i hope this makes sence.

I can't quite follow your plans, Wossie, but it's not a good idea to remove any existing drainage unless you are 110% certain that it is redundant.

If you're worried about the clay layer impeding the drainage of the planned garden, then installing a land drainage system and connecting it to the SW system would seem to be the best solution, as far as I can see. This can then be burried beneath your topsoil and no-one need be any the wiser.

Does that help at all?

My yard is in two parts, one part is the drive the other part is the yard, where i want the garden. The drive is higher than where i want the garden. The surface drain that i want to use drains all the water away from the drive and the yard. What i meant about taking away the drain is, the part itself that i want to take away looks like a chimney pot, with a small outlet at the bottom ( house and pipes are 100 years old ). This pot is joined to a pipe about 4ft long this joins into the house sewer pipe. By digging a trench the length of the edge of the garden as thats where the drain is, filling in with hardcore then leveling the rest of the area with hardcore. Is this suitable , as i feel that is i have to leave the pot in place i will loose the depth of the top soil that i want to put in, and feel that i will not get proper drainage either. I hope this makes sense as i am trying to put my thoughts into words, so you can understand what i am trying to do.

I think what you are describing is a filter or interceptor drain, but I'm not sure why all that effort is required.

The drive is higher than the planned garden, so it could crossfall to the garden and the surface water coukld be collected by a channel which then delivers the water to a single collection point, such as a gully.

There's no need to remove the existing 'pot' as its level can be adjusted by using a raising pice or building up the pot with brickwork and then setting the grating to the new level.

the yard/drive way has been concreted over in such a manner that all rainwater/surface water falls to the centre,which is where proposed drain is. at present after taking away crazy paving ive got a step down into the lawn area i cannot give exact dephs as concreting is not to clever ie it goes from a few inches high to 1'6"in a 90 degree manner,all lawn area water drains away into this drain.concrete is approx 4"thick,so take away rest of concrete im now 4 "lower that drain cap where does pool of water drain away?.cant add hard core to this level as height of path along house/along drive way will not allow,so i must dig down,to bottom of the pot where underground pipe meets sewer pipe.this is where the thought about using this underground pipe to drain water off top of clay surface by having a trench dug the lengh of the drive way (garden/drive way are side by side) have this filled with hard core bottom being bottom of under ground pipe,then adding more hard core on to rest of clay with a slight fall to the trench so that rain water will drain through the top soil into hardcore then seep into trench then from the trench the rain water will then enter the underground pipe then flow away into the sewer system. can this be done i can only go down i cant build up,ive got the drain but i dont know if this is the correct way of doing this. i dont know about using a trap as this will give me problems as it is adding height i need to go as low as poss to the bottom of this underground pipe would be i feel enough its only about 24"deep maybe more from the top of the drive way i understand about what you say on land drains i think that this is the same principle , is this more understandable,i wish i had a scanner lol i could draw area and show you idea instead

You need an Interceptor Drain, as shown on the Land Drainage page, and it is essential you use a filter membrane, such as Terram 1000 to prevent the soil being washed into the drain.

The depth of this drain can be altered to suit your site conditions, but I'd strongly recommend the use of a 80mm dia pipe at the base of the drain. Also, I'd dress the top of the drain with a larger decorative gravel or cobbles, rather than cover it over with soil, but the final decision must be yours.

Connecting the Interceptor Drain to the existing sewer is a relatively easy job - you could use the existing branch junction that will have been used to connect to the now-redundant gully. A flexible-throat coupling is the simplest way of connecting flexible land drainage to clayware.

thankyou for your help.i had alittle difficulty in understanding terminology.but i now understand the principles of land drainage.i have only a few questions now.how much pipe do i need for an area of 22' x 8'4". how are the pipes joined together to form the herinbone pattern and how do i lay the pipes,(sewer pipe is 2' deep)do i dig down to a level surface of 18"then dig the trench`s to the deph of 2' how deep should the gravel be and how do you use the terram 1000 is it layed in 1 piece over the whole area then top soil put on top,or do you use it only around the pipes.

how much pipe do i need for an area of 22' x 8'4"?

That's roughly 6.7 x 2.5m, so you could just lay one single strip down the centre. So, a 10m length would be more than enough.

How are the pipes joined together to form the herinbone pattern?

You don't have sufficient room to form a herringbone patytern, but, if you dod, the jointing detail is given on the Land Drainage page.

how do i lay the pipes,(sewer pipe is 2' deep)do i dig down to a level surface of 18"then dig the trench`s to the deph of 2' how deep should the gravel be and how do you use the terram 1000 is it layed in 1 piece over the whole area then top soil put on top,or do you use it only around the pipes.

Again, all this is shown in the drawings on the Land Drainage page. If you intend to outfall into the sewer, then you cannot lay the perforated pipe lower than that - try as you might, water won't run uphill :)

The Terram (or similar) is used to line the trench and kep the gravel separet from the surrounding earth.

im totaly lost now ive been given so much different advice i dont know where to turn.somebody has said that i cant connect the 80 mm perforated drain straight to the sewer system because of the gases and that taking out the gully drain i would loose the trap is this right? also i have read on other gardening sites that land drainage should be put in when garden is in but ive only got a space of clay soil so what is the best way to put in the drains,can i buy a new gully drain with a back inlet with a trap built in ive got a catalogue frompoly pipe ,they only have these as seperate items i havent got the space.my thought now is to have one of these and to connect the 80mm pipe into this new gully drain.thanks from a totally lost and braindead diyer

somebody has said that i cant connect the 80 mm perforated drain straight to the sewer system because of the gases and that taking out the gully drain i would loose the trap is this right?

You can't connect directly to a Foul or Combined system without a trap, but you can connect to a surface water system. Removing the gully may well eliminate the trap, if it is a trapped gully - not all gullies are trapped.

Are you connecting to FW, to SW or to Combined?

iI have read on other gardening sites that lland drainage should be put in when garden is in but iI've only got a space of clay soil so what is the best way to put in the drains

Let the gardening sites advise on planting, and leave the construction work to those with actual site experience, not some cack-handed half-baked concept of how things are actually done. Land drainage should be done BEFORE creating your garden. The best way to lay land drainage, in my opinion, and that of more or less everyone I've ever worked with, is that detailed on the land drainage pages.

can i buy a new gully drain with a back inlet with a trap built in ive got a catalogue frompoly pipe ,they only have these as seperate items i havent got the space.my thought now is to have one of these and to connect the 80mm pipe into this new gully drain

How would this work? If the B.I.G is set higher than the land drain, how will you persuade the water to run uphill? The trap has to be at the lowest point between the perforated pipe and the sewer to which you are connecting. You could use a simple S-trap or even a P-trap laid into the line at this point, and that would prevent sewer gas and odour escaping back via the perforated pipe. Having a trap at the head or high point of a land drain system is nonsensical.

i have purchased all that i need,back inlet bottle gully,2 risers and connectors.do i have to put land drain into a trench or can i lay it on the clay surface then bury it with gravel then add top soil.also at the bottom of my yard/garden i have an inspection chamber it has an old branch leading away from which i think was from an old outside toilet.my question here is that whether or not i can bury the manhole cover with soil/turf as otherwise it shall have to be raised,i wont have a problem with rodding it as i can still get acsess to it from yhe inspection chamber which is closer to the house.also what is a cheaper alternative i can use to hardcore i have priced this and its a few quid short of 30.00 a ton,the land drain i have got has holes rihgt around the curcumference is this ok wont water drain into the ground as opposed to draining away in the gully.

The land drain should be laid in a trench, unless you cane ensure it will have at leat 300mm of cover.

You should never bury old MHs or ICs. You may well know where they are, but, if you came to sell the property, the new owners might not be aware of their existence.

You need to use a 10-20mm clean gravel around the perfoarted pipe. In full loads (20T) it costs around 12-15 quid per tonne, so 30 quid per tonne in agg bags would be about right.

lawn has been down a month now and have no probs with boggy soil even with all this rain.ended up burying man hole cover.looks great im quite exclusive now by the only 1 in a very long street of terraced houses to have a garden may of even added a bit more cash to the property.

Good to hear you got it all sorted. :)