Period Drainage

[DJH]

of course deer... 8)

 

[Penners]

:wink:

 

[malcolm]

I decided to go DIY in the end as the biggest bit of work was excavation and I needed to do that before I could figure out what to do. Would you believe I found a third drain running parallel to the first two? Fortunately two were spare and could be removed and blocked with concrete.

The inspection chamber base went in this morning (I forgot to look at the weather forecast before starting and couldn't really leave the foul drain open so I'm cold and wet now). I think I will use hoppers or gulleys so I can retain the funny shaped metal downpipes on the outside of the building.

The downpipes are spaced about 250mm apart so I can't use a single hopper. I could probably connect a hopper to a bottle gully and take that down to the inspection chamber allowing rodding from both ends which would leave a spare connection on that side should I later want to re-route internal drains and remove a nearby inspection chamber inside an extension.

Alternatively I could have two hoppers with two separate connections to the inspection chamber so if one blocks the water would flow down the other. Though they won't be visible so I'll probably only know about it when both block.

I have probably answered my own question, but any thoughts appreciated. Building regs are due a visit and want to have a look before it is backfilled.

 

[Flyfisher]

I'm sure I've read somewhere that hoppers for foul drainage (e.g. Sinks, baths, etc) are not allowed by current building regs. Having said that, I'm also pretty sure the regs are not retrospective so if hoppers were previously used then it'll probably be ok, but if hoppers are being moved or refurbished then I don't know how a BC inspector will react.

Since you say you have a BC visit soon I'm assuming the work must be signed off, I'm which case it might be worth a chat with them before committing to a particular arrangement.

 

[Penners]

I'm sure I've read somewhere that hoppers for foul drainage (e.g. Sinks, baths, etc) are not allowed by current building regs.

FF - do sinks and baths count as "foul" drainage? I'm pretty sure you're correct that hoppers are not permissable for lavatory outflows, but I've never been sure whether grey water is regarded as foul or not.

 

[malcolm]

I've had a good read through part H. They like to see a trap so you don't smell the sewer but it still seems OK to use hoppers for kirchen and other less smelly waste.

Unless I have misread. If current regs were applied to my drainage it would fail - not enough slope. Hopefully building regs will be content if it works.

 

[Flyfisher]

I'm sure I've read somewhere that hoppers for foul drainage (e.g. Sinks, baths, etc) are not allowed by current building regs.

FF - do sinks and baths count as "foul" drainage? I'm pretty sure you're correct that hoppers are not permissable for lavatory outflows, but I've never been sure whether grey water is regarded as foul or not.

I'm not completely certain, but I've always thought of grey water as being part of the foul drainage system. I certainly agree that hoppers would be impractical for lavatory outflows (!!) and that grey water is not always as foul as foul can be, but it can be highly contaminated with all manner of stuff not really applicable to be sent to a soakaway like other surface water. An example would be a kitchen sink fitted with a waste disposal unit, which might not be entirely 'hopper friendly'.

 

[Flyfisher]

I've had a good read through part H. They like to see a trap so you don't smell the sewer but it still seems OK to use hoppers for kirchen and other less smelly waste.

Unless I have misread. If current regs were applied to my drainage it would fail - not enough slope. Hopefully building regs will be content if it works.

Fair enough and good luck the the BC inspection.

 

[mattice]

I think you've figured it but we've just had hoppers signed off for all of our grey waste. They were also very flexible on the gradient for a 50m run of pipe from the back of the house. I'm not sure we would have got away with it if there had been solids down the pipe, but they seemed happy with a washing machine, flashed out by the occasional rainwater.

 

[malcolm]

I don't have it figured out at all, though if I got someone in to do the job I'm sure it would have ended up not how I want it so I'm still working on it. It is really annoying that manufacturers websites are terrible and nobody gives dimensions for drainage bits. Also annoying the week has mostly involved cat and vets and progress is really slow.

I have less height than I thought. I had hoped to have the top of the gully/hopper below kitchen floor level. The trench is the photo is about 90mm below kitchen floor level so at the bottom of that seemed sensible.

The problem is the bottom of the trench is only 190mm above the invert level (bottom of the pipe) that goes into the inspection chamber, so allowing 30mm for a 1 in 40 slope I only have 160mm between the top of the hopper and the bottom of the trap exit pipe. I can do that with a small hopper and P trap but not with the trapped bottle gully I have.

I'm back to using 2 hoppers again and taking up both inspection chamber connections on that side or removing the cast iron downpipe and replacing it with plastic for side entry and using a single hopper. Or finding a low profile gully and setting drain levels about 50mm higher. I'm keen to use hoppers though am starting to wonder if the great big plastic pipe up the side of the building would be a better solution after all.

 

[Penners]

I have less height than I thought.

Me too. I reckon I'm about an inch shorter than I was 10 years ago.

a 1 in 40 slope

You'd need to check this with your building inspector, but although 1 in 40 is regarded as the optimum I believe the regs allow between 1 in 10 and 1 in 80 for 100mm underground soil pipe, so you might be able to reduce your slope a bit - if that's any help.

 

[DJH]

You can get adaptors from cast iron to pvc....http://www.polypipe.com/building-products/products/below-ground-drainage/underground-drainage-adaptors They are at the top of the page.

If you follow my earlier suggestion of connecting your waste pipes direct to a waste adaptor (see the link above at the bottom of the page) you can omit any trapped gulleys and connect direct to a bend with a short length of pipe to give you the required height from ground level to the inspection chamber.

In my experience water trapped gulleys can be a maintenance nightmare especially if a waste disposal unit is connected to it as sludge builds up in the trap and grease will congeal quickly because of the cold water in the trap In fact that's true of any trapped gulley used by a kitchen sink only. It's a smelly job to clear a blocked trap...been there and done it...

Doug

Just read your post Penners. I was taught that a fall 'should allow a self cleansing velocity'.

 

[Penners]

I was taught that a fall 'should allow a self cleansing velocity'.

Quite so, Doug. I was taught that the range I mentioned above allows the solids to be carried along by the liquids. Any steeper incline and liquids flow too fast, leaving the solids behind. Any shallower and the flow of liquid isn't enough to carry the solids along.

:x :x

I hope you're enjoying your tea!

 

[DJH]

Yes I am...beef sandwiches with English mustard and Irish butter. Kerrygold naturally...

Doug

PS You are quite right as always...the puddywuddys send their love. 8) 8)

 

[malcolm]

Avoiding gullys is probably a good idea. I have 4 pipes at the moment and one is a fluted aluminium rainwater downpipe which might be difficult to connect to a stub.

Even if I went for a full height vented soil pipe I would presumably risk a flood inside ftom other entries if there were ever a blockage at the bottom of the pipe and I can't see how it might be sealed to the gutter.

Possibly back to two connections again. I can always put a soakaway in for rainwater if I ever want to use the second connection for the loo.

 

[Feltwell]

In my experience water trapped gulleys can be a maintenance nightmare especially if a waste disposal unit is connected to it as sludge builds up in the trap and grease will congeal quickly because of the cold water in the trap In fact that's true of any trapped gulley used by a kitchen sink only. It's a smelly job to clear a blocked trap...been there and done it...

Yep - me too, very unpleasant job, especially when it's not even your trap :evil:

I've ended up cleaning out a trap that services a neighbour's kitchen sink a few times, it's on my land but only serves their kitchen, another odd arrangement not untypical in an older house! When it's smelling and overflowing it's quicker to just sort it than try to get them to do it. In fairness with our current neighbours it's not been much of a problem, but with a previous set who seemed to put a lot of fat and oil down the drain it was a right pain.

 

[Penners]

I've ended up cleaning out a trap that services a neighbour's kitchen sink a few times, it's on my land but only serves their kitchen

I reckon the law probably regards the contents of the trap as your neighbours' property, rather than yours. So I do hope that you do your legal duty and return it to them.

 

[malcolm]

I'm back to looking at gullys. Rainwater into a vented pipe isn't easy as the guttering would create a vent in the wrong place so I would need to add traps in inaccessible places. Also the vented pipes are really ugly warty things with lots of spare connectors where you don't want them.

Popped into Buildbase with a tape measure this morning and might have a plan to do everything with a single gully using the side entries for some of the pipes.

 

[Flyfisher]

Just to clarify, what's the difference between a gully and a hopper? I've always thought of a hopper being something mounted high up on a wall and a gully as being at ground level. My earlier comment about current regs not allowing grey water into a hopper was based on that understanding, I.e. Sink and bath water not allowed into a hopper at first floor level.

I'm quite happy to be corrected but am wondering if this might be a cause of confusion?

 

[malcolm]

In the photo of shiny plastic bits above the one on the left is a bottle gully with an inbuilt trap removable for rodding, and the one to the right is a hopper which needs to be connected to the P trap gully in he middle if a trap is needed.

I've got a sink and bath draining into a hopper at first floor level. I even have a gully inside but will put something on top of it when building regs visit. I know that modern practice isn't keen on running rainwater into foul drains, but hoppers and gullys do seem to be commonly used for grey water, but do need to be trapped at the connection to a foul drain so a hopper would need to be trapped if it went into a soil pipe.