Drains: Shallow, 110mm foul water pipe crossing a driveway - options?

[trancenotes1776]

Suggestions/advice sought....

I'd like to run a 110mm underground foul water pipe from an outhouse to my house's main drain, but it will need to cross a part of my grounds that c ould conceivably be used for vehicular access on the rare occasion. By nece ssity, this underground drain needs to be very shallow in order to achieve an acceptable gradient (it can be only about 5" deep at the shallowest poin t. I 'm hoping to avoid the prohibitive expense of making a concrete trench , capped with flagstones. So I'm wondering if there is an easier option, su ch as using some kind of toughened pipe for the section that crosses the oc casional-car-access point. An alternative possibility might be to feed the

110mm plastic pipe through some kind of concrete or GRP pipe at that sectio n. Do people do this? I even considered concrete flue liners!

Thanks for any suggestions.

Many thanks! Al_4

[Bob Minchin]

What is so prohibitively expensive about a concrete lined trench? Put a strip of chequer plate maybe with U section to stiffen over the top and bearing on the concrete or dwarf walls of engineering bricks. If the pipe run is so near to the surface, then the essential trap seal at the input end is going to be above ground. I assume you have thought of that and is OK?

[Al_4]

to my house's main drain, but it will need to cross a part of my grounds t hat could conceivably be used for vehicular access on the rare occasion. By necessity, this underground drain needs to be very shallow in order to ach ieve an acceptable gradient (it can be only about 5" deep at the shallowest point. I 'm hoping to avoid the prohibitive expense of making a concrete t rench, capped with flagstones. So I'm wondering if there is an easier optio n, such as using some kind of toughened pipe for the section that crosses t he occasional-car-access point. An alternative possibility might be to feed the 110mm plastic pipe through some kind of concrete or GRP pipe at that s ection. Do people do this? I even considered concrete flue liners!

Thanks - well, a trap access can be positioned at one side of the driveway, rather than say midway, so I don't see a problem there. Yes, it can be don e the way you suggested. But I was hoping to avoid having to lay any concre te base, which would be needed for the block walls. Access for a readymix l orry is probably not feasible. The subsrate is clayey hardcore. I'm just a DIY-er and money is tight. I could probably buy an offcut of reinforced pip e from somewhere, if that's a viable option. It seems hard to source though .

Al_4

[newshound]

What are you surfacing the "drive" with, and how wide is it?

I think I might be inclined to dig a sloping trench 18 inches wide, lay medium or high density blocks at the bottom, bed a single row "wall" of blocks on mortar along each side, lay the pipe on gravel this trench, cap the trench with something like chequer plate perhaps 3 feet wide, and top the lot with MOT/scalpings or whatever.

Having seen that written down, I suspect that a suitable length of 6 inch steel pipe would be cheaper. Not sure about concrete or GRP though.

[harry]

my house's main drain, but it will need to cross a part of my grounds that could conceivably be used for vehicular access on the rare occasion. By ne cessity, this underground drain needs to be very shallow in order to achiev e an acceptable gradient (it can be only about 5" deep at the shallowest po int. I 'm hoping to avoid the prohibitive expense of making a concrete tren ch, capped with flagstones. So I'm wondering if there is an easier option, such as using some kind of toughened pipe for the section that crosses the occasional-car-access point. An alternative possibility might be to feed th e 110mm plastic pipe through some kind of concrete or GRP pipe at that sect ion. Do people do this? I even considered concrete flue liners!

The main danger is that it sinks so causing a "backfall" which in turn caus es blockages.

It needs to be surrounded in concrete and the concrete to extend down to fi rm subsoil. There is no "easy solution".

[Al_4]

se to my house's main drain, but it will need to cross a part of my ground s that could conceivably be used for vehicular access on the rare occasion. By necessity, this underground drain needs to be very shallow in order to achieve an acceptable gradient (it can be only about 5" deep at the shallow est point. I 'm hoping to avoid the prohibitive expense of making a concret e trench, capped with flagstones. So I'm wondering if there is an easier op tion, such as using some kind of toughened pipe for the section that crosse s the occasional-car-access point. An alternative possibility might be to f eed the 110mm plastic pipe through some kind of concrete or GRP pipe at tha t section. Do people do this? I even considered concrete flue liners!

way, rather than say midway, so I don't see a problem there. Yes, it can be done the way you suggested. But I was hoping to avoid having to lay any co ncrete base, which would be needed for the block walls. Access for a readym ix lorry is probably not feasible. The subsrate is clayey hardcore. I'm jus t a DIY-er and money is tight. I could probably buy an offcut of reinforced pipe from somewhere, if that's a viable option. It seems hard to source th ough.

Hi, and thanks. I hadn't thought of 6" diameter steel. I've no plan to surf ace the drive in the near future. It is just hardcore, and pretty solid too (no real chance of subsidence, etc). The walled trench you suggested is mo re or less what I've considered. The reinforced pipe idea still sounds easi er. I guess 10mm-thick GRP would be extremely crush-proof, once buried. And durable too. I saw a piece once, but have been unable to relocate it! Al_4

[Al_4]

o my house's main drain, but it will need to cross a part of my grounds th at could conceivably be used for vehicular access on the rare occasion. By necessity, this underground drain needs to be very shallow in order to achi eve an acceptable gradient (it can be only about 5" deep at the shallowest point. I 'm hoping to avoid the prohibitive expense of making a concrete tr ench, capped with flagstones. So I'm wondering if there is an easier option , such as using some kind of toughened pipe for the section that crosses th e occasional-car-access point. An alternative possibility might be to feed the 110mm plastic pipe through some kind of concrete or GRP pipe at that se ction. Do people do this? I even considered concrete flue liners!

uses blockages.

There is no chance of my proposes outer sleeve pipe sinking as the whole ar ea is solid hardcore that is very well-bedded down.

Al_4

[Mobilohm ...]

wrote in message news: [e-mail]... Suggestions/advice sought....

I'd like to run a 110mm underground foul water pipe from an outhouse to my house's main drain, but it will need to cross a part of my grounds that could conceivably be used for vehicular access on the rare occasion. By necessity, this underground drain needs to be very shallow in order to achieve an acceptable gradient (it can be only about 5" deep at the shallowest point. I 'm hoping to avoid the prohibitive expense of making a concrete trench, capped with flagstones. So I'm wondering if there is an easier option, such as using some kind of toughened pipe for the section that crosses the occasional-car-access point. An alternative possibility might be to feed the 110mm plastic pipe through some kind of concrete or GRP pipe at that section. Do people do this? I even considered concrete flue liners!

Thanks for any suggestions.

Many thanks! Al_4

haunch the pipe in concrete .....

[Tim Lamb]

Hmm.. how about running your drain pipe through a length of twin wall drain pipe? 150mm or 225mm dia. Immensely strong stuff.

[The Natural Philosopher]

I have to say this occurred to me. Wrap the pipe loosely in chicken wire and lay dry mix of sand cement and gravel all around.

Then water it. Or let nature do that.

5" of reinforced concrete will take TONNES of pressure

[Mobilohm ...]

the only way ....

[Al_4]

Yes.. that's certainly tempting! Thanks for that. I think I had some idea that this was a bad idea, but it does sound like a relatively easy solution. Al_4

[Al_4]

Hi Tim, I had not heard of twin wall drain pipe before, but it sounds highly promising. I will look for it. Many thanks for that. Al_4

[Al_4]

Wowee! This NG has always been great, but today, it's really coming up trumps! Thanks a million for that fine brainwave. (I'm doubly happy, because I just happen to have a bunch of galvanised mesh going spare!)

Al_4

[Al_4]

Do you mean this stuff?:

Thanks again! Al_4

[newshound]

I am not sure how strong that stuff is really. I have just used a length of something which looked very similar, sold as conduit for underground electrical services (although I actually used it to repair a land drain). You can cut it (with difficulty) with a Stanley knife, you certainly can't do that with "normal" drain pipe.

[Al_4]

PS - It looks like a toss-up between Tim's twin-wall pipe suggestion and yo ur reinforced concrete jacket idea. The former is probably simpler and more easily dismantle-able in the event of unforeseen future changes... but I'm guessing the latter is probably more pick-axe proof.

Al_4

[newshound]

Yes but that won't *really* be reinforced concrete. That said, this would probably be strong enough (I wouldn't bother with the chicken wire, but you could bung in some weld mesh, which comes in varying spacings and bar thickness).

[Al_4]

Thanks for that. Somewhere in the murky mists of my memory, I think I've handled it before. What you said reminded me of my own impressions: that it seemed surprisingly malleable for something purported to have great strength. Al_4

[The Natural Philosopher]

Yep. That will do as well. Almost anything with some tensile strength will do.

Chiken wire is better than you might expect actually.