Drainage - p-traps and access - Drainage

[peteuk]

Hi, Please accept my thanks that you run this great, informative site (even though you say this type of phrase is becoming overused).
I am not a DIY expert so am asking for quotes to blockpave 2 drives, pathway and lay a patio. It's a large area and I am concerned I don't know enough about the subject.
Current paths etc are all concrete and drainage appears poor. Rain water, some surface drainage and household drains share the same sewer system.
I have already decided not to use 1 contractor and now have a choice of 2 (price pending):
I have 5 question areas regarding drainage, permissions and timing.
1). To solve my drainage fears 1 contactor has offered to use soakaways only. From reading your site, my feeling is that this cannot be seen as a solution without excavation to examine water tables etc. Am I correct?
2). Along the path beside the house 1 contractor has proposed the use of a channel drain connected to the sewer. Am I correct in thinking he must install a P trap and access so I can clear any silt build up? Do I need access to the P-trap as it would seem to me that the trap is an area where silt would stop? (He said I would have access but did not mention a P trap)
3). The front and back lawns will slope. The front to one of the drives, the other to the patio. The same contractor has proposed the use of a land drain at the end of the front lawn connected to the sewer, and a soakaway for the back lawn. Do I need a P-trap? He didn't mention it and he says there is no need for a silt trap because land drains do not silt up. Is this correct?
4) He has a space in his schedule for 27/03 and seems busy. Is there a time when the weather means it will be unsuitable for him to work?
5)Do I need any planning permissions to connect to the sewers?

Thanks for the support. I'm sorry if this is a repeat of old questions but I've spent many hours on the site and can't find the clarification I need for my peace of mind.

Pete

[Tony McC]

1 - almost right. The contractor may be intimately familiar with the area and know in advance that a soakaway will be fine. I know certains parts of the biggest town to where I live will always take a soakaway, while other parts, such as the village where I actually live, are not worth even digging a trial hole because the whole village sits on solid, impermeable boulder clay.

2 - you need a P-trap not just for silt arrest, but mostly because the proposal is to connect to a combined sewer, and without a P-trap, the sewer will vent, ie, it will pump out nasty sewer gases.

3 - A land drain that doesn't silt-up? That'd be a first!! Any such land drain should be wrapped in a geotextile to minimise silting, but a P-trap isn't necessary unless there is somewhere for the sewer to vent. A catch-pit, though, would be a good idea.

4 - Only exceptionally heavy rain or frost should stop work.

5 - not to those on your own property.

[peteuk]

Thank you for the reply.
I'll discuss again with each contractor when I get the quotes in.
Is there a way I can judge the right solution (soakaway or drain)? I think the contractors might be trying to keep the cost down (my obvious request) but then I still want it done right.

As someone new to this I find it difficult when the "expert" in front of me says something is or isn't necessary. I'll let you know how I get on - there seemed to be some reluctance to install drains by 1 contractor (I don't think he plans deep soak aways), and the other never mentioned P-traps or catch pits ("not necessary on a land drain" he said) although he did say I would have access to the channel drain on the path.

Pete

[Tony McC]

The "right solution" is determined by a pecking oder of options...

1 - soakaway - always right
2 - outfall to local watercourse - may need a consent
3 - connect to SW system - OK, but should only be done if 1+2 impossible
4 - connect to FW/combined system. - only if there is absolutely no other option whatsoever

[peteuk]

Hi there,
Sorry I'm back earlier than expected. Have just received a quote for the drives / patio etc. He proposes to lay the patio slabs "on 3" of wet cement to minimise movement within the patio, therefore prolonging its life". Has anyone heard of this? and is it acceptable practice?
Also, I'm hoping to widen my drive from 1 car width to 2. The Council have looked at the kerb and advise I can only extend the drive access (lower the kerb) about 3 feet which will look terrible. Does anyone know away around this? (I'm waiting for their quotation because they say they are the only ones allowed to do it).
(And this on top of my other drainage worries)
Thanks again,

Pete

[Tony McC]

The phrase "3 inches of wet cement" worries me.

Firstly, it's not cement - it's a cementi-bound material (ie: it contains cement) such as a mortar or concrete. Any so-called tradesman talking about laying onto "cement" would worry me.

Secondly - why 3 olde-worlde inches? For patios where there's no significant change in levels, 2 olde-worlde inches of laying course is more than enough. We's use 4 olde-worlde inches for a driveway. 3 olde-worlde inches seems to be straddling the fence.

Thirdly - minimising movement. If done properly, any number of olde-worlde inches of cement-bound material should eliminate movement, never mind "minimise" it. However, as the laying couse would them be the equivalent of a cement-bound slab, movement or crack control joints within the slab/laying course would become necessary. Has any provision been made for this?

Finally, your dropped crossing. Sorry, but you have to accept what the LA says, and if they say you can only have one extra kerb length, and they can justify that decision with a reasonable logic, then one extra kerb width is all you can have. If you think their being picky or unfair, you need to state why and ask them to reconsider.



Edited By Tony McC on 1142171400

[peteuk]

Thanks Tony,
Although I don't think the LA can justify their drive size restriction on a quiet cul de sac where double garages with such drives exist I am now thinking of reducing my drive requirements back to a single drive (less cost anyway).
Re: cement base for flags:
Is an additional sub base needed?
What do you mean by a movement or crack control joint? Do you mean the contractor should lay something like Flexcell between each paving slab (sorry I don't understand the instructions for this).
Thanks, Pete

[Tony McC]

Crack Control Joints - they are needed for a large slab, not between each individual flag.

Part of the reason I prefer to use the term "flag" or "flagstone" for paving units rather than "slabs" is to avoid confusion such as this. Slabs are large bays of concrete. Once you start referring to 600x600x50mm concrete units as "slabs" it opens the door for all sorts of misunderstandings.

[Suggers]

a solution without excavation to examine water tables etc.

Out of interest, we had to determine the water table level here - contacted National River Authority (now the Environmental Agency) -quoted our grid reference from the Ordinance Survey Map, and they came back with an average depth of 8 metres over the last 100 years! As I remember, this service was free - mind you, that didn't stop the newly built cellar flooding in that horrendously wet winter a few years back - even tanked properly with the marvellous Ronafix and cut into chalk. When that table rises nothing will stop her....!
Good Luck with project.

[peteuk]

Thanks Tony, Suggers
I've not been able to access the PC for a while so sorry for the delay.
The LA have confirmed I can only extend the drive by 1.2m and I have to write in if I want to appeal with no guarantee of success - the wife wants it done now so we're staying with a single drive......
Have agreed drainage and chosen a contactor so I'll let you know how it all turns out.
Thanks for all the support.
Pete

[Suggers]

Personally, I would appeal - Keep us posted.......
ps - isn't cement dust?

[peteuk]

Dear all who helped,
My drive and patio are all down and look good. It's been 3 months plus now and no obvious signs of problems apart from some water pooling when it rains - drains within 1-2 hours of stopping (not much rain since it was finished though) - I'm told this isn't a problem.
The lads who did the job had a horrendous time with the weather - everything was thrown at them from when they started.....they worked very hard in adverse conditions.
Your kind support and this brilliant site gave me the confidence to ask questions even if I only partially understood.
Thanks again to all, and yes the drinks are on me!

Pete
PS The council won re: the single drive - the wife didn't want a double drive so really the council gave her the ammo to win that one...
PPS Not visited the site since it all went down in case I read something which would make me worry about the work.

[Suggers]

Pete,
Great to hear of a positive result - so many times all posts are always down, down - the nature of the beast, I suppose - Just 'cos you're finished doesn't mean you can leave us......
Your experience is hot - post some photies.........
ps - always up for a drink, anywhere, anytime......