However, if you do this, is there anywhere for the garden groundwater to drain to?

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?

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 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.

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?

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.

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

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?

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

I 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

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

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.

For gravel surround, use whatever is available locally at a reasonable price. A10 pipe bedding is OK or any clean (ie, no fines) gravel that is 10mm or above, up to around 30mm maximum.

For a separation membrane, you can't beat Terram 1000 which you can buy via Greenham Trading or some of the larger BMs, or even online from the Terram Website for under 1 quid per m².

Careful consideration is needed for the outfall, and to the sequence of works. You need to minimise disruption to the un-excavated sections of the field, or you'll be playing all your matches 'away' next season. Use decking sheets or similar to keep the site clean and to prevent the mini-excavator from chewing up the pitch.

It's not rocket science, but it does take some planning and thinking ahead. If you can get a local groundworker to help out, it should be a doddle.

Good luck!

While I'm thinking - it's worth checking with your local Building Control, as agents for the Water Companies, that there would not be a problem outfalling to the ditch you mentioned. Most would have no problem with such a proposal, but they sometimes have an Outfall Detail that they prefer such schemes to use. This usually involves 'dressing' the outfall with a bit of rock or summat to make it look 'decent' and not just a pipe sticking out of a bank.

The best type of cover to use on a block paving project is a Recess Tray Cover - there's a page on the site that describes their installation.

However, with a pond within the sunken garden, then the drainage point should be an overflow system, that prevents the water in the pond rising above a certain level. Again, you need to consider the outfall point.

Is the pond at the lowest point within the sunken garden, or is it, effectively, a raised pond in a sunken garden?

Have you dug a trial pit to see if you can find the water table? If you can get down to, say, 500mm below the lowest point of the planned sunken garden and there's no sign of the water table, I'd take that as a good sign.

At 30m², you need to think about where you will send the water. It all depends on the layout - a 5x6 patio, with only 5m against the open ground, could struggle to drain in heavy rain, while, at the other extreme, 18x x 2m with 18m against the garden should drain into the garden fairly simply.

Tell me what the ground is like....

Spread a bed of mortar over the reduced brickwork and then place the frame. Pack each corner of the frame to bring it to 3mm below Finished Paving Level in all directions, and then pack the 'gaps' between the corners with other hard, inert material (tile, flags etc) and fill all gaps with mortar.
Haunch the outside frame flange with concrete and then place the tray. Don't fill it with bricks for 3 days, to give the mortar/concrete a chance to set.

If you still want to do it your way, I'd like to hear how you get on....with pics, if poss.

Assuming it is suitable, why would you then want to fill it with cobbles and pea gravel? That only occupies the space and reduces the storage capacity of the hole. Besides, using large cobbles at the base and pea gravel at the top is a waste, as the pea-gravel will trickle down into the voids between the cobbles.

If you don't fancy the concrete ring soakaway depicted in the Drainage section, then there are PVC units that you can buy that perform a similar function, but are lightweight and easier to handle. Filling a hole with all sorts of rubble is not how modern soakaways are constructed.

Quantity wise, if you were daft enough to backfill the hole, you're looking at around 2.1m x 2.1m x 1.25m (metric is so much easier to use!) which is 5.5 m³ which, in turn, is around 10-12 tonnes of rubble/rock/hardcore.

Your cheapest source depends on where you live. I could tell you to go to Charlie Love's Quarry where you can get 10 tonnes of 'cobbles' for around 80 quid, but then, you might not live in the same village as me!

You say the paving is 'cobbles'. Is it really cobbles, or is it setts? I can't think of anyone over that side of Manchester that undertakes sett/cobble work, but there are umptillions of so-called Block Paving Specialists, some of whom may be able to take on this type of work.

While not being familiar with the job, I'd guess that stripping out the cobbles/setts and replacing with concrete block paving would probably work out cheaper than relaying what you have. Just how feasible it would be to DIY depends on how fit and competent you feel yourself to be, and the size of the area. DIY block laying is much easier than DIY setts/cobbles.

I'd get another builder in to have a look and see what they have to say before committing to one option or t'other. I can't say what the best option would be, without seeing the site for myself, but a cellar drain would be my last resort.

Remember that these companies are more interested in flogging their so-called solution rather than finding the best solution for your property. That's why it's important to take more than one opinion.

With the water meter cover, set it to the correct height, then haunch it with concrete to hold it in place, but make sure the haunching is (thickness of paver + depth of bedding) below the top of the unit.

Finally, don't worry about the edgings. As long as they are haunched at the rear, and bedded onto concrete, they should be fine. There's absolutely no need for concrete at the front.

If you did replace the gully, then I suppose the materials might come to 50 quid, and then the labour would be perhaps 100 quid for such a small job, but, if you don't mind getting your hands dirty and enjoy a bit of a dig, it really is very, very simple for you to DIY.

Dished channels look fine with block paving. They are mentioned and illustrated on the site on the Road Kerbs page and on the Draining a Pavement page, which also shows how a channel can be formed in the blocks themselves.

There's no trip hazard with these dished channels - they are specificall designed for use on pavements and as long as they are correctly laid, they are as safe as can be.

I can't quite visualise the problem with the KW - is the 'pipe' of which you speak the discharge pipe from the sink itself, or do you mean the pipe that connect the KW gully to the FW system? Any chance of a picture?

Assuming you mean the discharge pipe, then you could use paving bricks laid on edge on a bed of mortar, and omit the section where the pipe feeds in, then patch that up with coloured mortar or grano.

Compacting the sub-base around the gully is a delicate business. We normally use a punnel (see Tools page) but you could use a sledge hammer or even just a lump hammer to consolidate the area, a bit at a time. Once the blocks are in place, you should be able to run the wacker plate over the lot, as the sand bedding will 'cushion' the buried pipework.

It's the cover they are normally most concerned with - you'll probably be required to fit a double-sealed airtight cover. You should discuss this with your BCO.

In areas where soakaways are common, then the BCO is less likely to need convincing of their viability, but if you're in a clay spot, then it may be wise to seek the advice of the BCO - they're not there to make your life hell, despite what you might think, but are often a damned useful (and free) source of very good advice and often have years of experience with regard to local conditions.

In your situation, I would discuss your plans with the BCO and see what interpretaion they will put on it. Personally, I wouldn't be happy with the soakaway being designed to surcharge into the gully on the public highway, and the same goes for the interceptor drain you're considering around the foundations.

Have you done a percolation test yourself? How confident are you about the viability of the soakway? Given the push for Sustainable Urban Drainage Schemes (SUDS) in modern developments, it's well worth considering an extra large soakaway facility if you have the right conditions. It's much better for the environment than relying on a public SW system that dumps everything in the local river.

On new-build or extensions, the local authority may require proof of the viability of a soakaway before passing the drainage scheme as acceptable. Adding a relatively small amount of land drainage to an existing SW system is nothing to concern them.

Riparian rights are a bit of a legal minefield - not that they are always contentious, just that they can be a right abstrad to track down, just the sort of work a solicitor loves to assign to the spotty office junior and charge you 75 quid per hour for the privilege.

You'll get more sense from the BCO or the Tech Services Dept than you will from a solicitor!

LA = Local Authority
BCO = Building Control Officer
BM = Builders Merchant
BoQ = Bill of Quantities

...I'm sure there's more! Maybe a page covering all my many acronyms is required?

Step 1 - Cut ellipse shape out of main pipe using a sharp knife or junior hacksaw. The hole needs to be approx 80mm across the short axis and 150mm along the long axis...

Step 3 - Fold over the end of the branch pipe, to form taper as shown

Just confirm that you have rodded the downstream section from the permanently flooded IC, haven't you? And that's made no diff?

My first suggestion, which might not be what you want to hear, is to call in a drainage specialist to see if they can resolve the problem. As a DIY'er, you're limited in what you can acheive with rods and it might just need a blast from the jetter unit to clear the problem.

Two further Q's - have you located the next IC/MH downstream from the flooded one? And is this FW or SW?

Corners can be mitred, as shown on the Linear Drain page, although some of the more expensive makes offer angle/corner units ex-stock.

Take your time, and just ask here if you have any other queries.

To cut down on the amount of clays and silts washed out by the land drainage, use a separation membrane - Terram 1000 is fine - as this will filter out the smaller particles. In a year or so, as the ground settles after all your recent landscaping work, there will be much less clay/silt being carried by the system, so your pond should clear.

2 - rather than a short vertical run, try to 'ease' the level change a couple of metres either side of the steps. So, from the vevel of the drain 2 metres from the steps on the uphill side, dig your trench to the required level at a point  2 metres downhill from the steps - do you understand that, or do you want a quick sketch?

3 - LAs are a law unto themselves and, if you get stroppy, they can always get stroppier still. If you could show, without a doubt, that the Park was draining into your property and causing damage, then you could compel the LA to install an interceptor drain at the boundary. However, they are right when they say that there will always be some groundwater, and it's only in cases where you can prove that some change they have made to the park, such as surfacing or digging out tree stumps, has caused a worsening of the problem on your property that you would have a viable case.

It's always a more productive policy to be as nice as ninepence to the LA. They can be very, very helpful and save you a small fortune, as long as you handle them correctly. If you can make a reasonable case for them to install an interceptpor drain, 9 out of 10 LAs would do so, but, if you start stamping your feet and threatening this, that and the other, they'll just drag the whole thing out for years.

Only a couple of weeks ago, my brother dug out a H.petiolaris that had been planted about 15 years ago at the side of a garage. It had become a bit of a bind for the owner, who is elderly and not into trimming and pruning as she once was, and was finding the H.petiolaris was interfering with the garage door.

Anyway, Our Kid hacked the bugger down and dug up the rootball and, although it had sent roots down about 500-600mm into the soil and a good metre all around, not a single one had attacked the pipework for an adjacent Rainwater Pick-up.

Luvverely plants, too. I put one in on my N-Facing front wall a couple of years back. The only trouble is that Earwigs love to nibble the newly-emerged leaves, so it's worth setting a few earwig traps.

2 - Using a perforated pipe depends on the nature of the ground (how porous and thirsty it is) and the amount of water emanating from the spring. If you think you might lose a significant volume of water between the spring and the stream head, then use a solid pipe rather than a perforated one.

I'm glad you like the web site.

Seems like a lot of work, to me, but, that's the only 'cleans hands' solution I can think of. Much simpler, and much cheaper, would be to install a Y-junction (we call them 'Oblique' or 'Square') and run a pipe to emerge just above the bog garden. Put a bung/stopper in the end of the pipe (these stoppers are less than a fiver) and just release it as required. If you look at the construction of a typical stopper on the Testing Drainage page, you can see that there is a simple screw cap that cane be undone to allow water to escape, and this would be easier than releasing the entire stopper.

Of course, this second solution relies on you having adequate falls to allow the bog-feed pipe to emerge above ground level above the bog garden, or, for there to be a sufficient 'head' of water to feed it via gravity.

Brilliant idea, you'd think! And it was, until some kiddie jumped up and down on top of a grass-filled unit and the fibre-glass gave way, sending the kiddie down into the chamber, scratching legs, denting pride and incensing parents.

They were withdrawn shortly after, but you can acheive more or less the same by using a steel recess tray cover, safe in the knowledge that, as they are tested and approved to carry the weight of your average family Armoured Personnel Carrier, they are more than capable of withstanding even the most determined of kids jumping up and down.

Drill half a dozen 10-15mm holes in the tray, line the base with a membrane of some type (Plantex, Terram or an old pair of tights will do) fill with a sandy soil, and turf it! Fix the frame as described on the Recess Covers page, and, once it's set, just lift the tray into place and voilá.

A 600x450mm galvanised recces tray and frame will cost you less than 50 quid from most BMs.

Good luck!