Know of a n london drainage consultant? - Looking for advice for drainage issues

[Thehandmadegarden]

Landscaped a garden in North London earlier this year and from breaking ground we have had problems with flooding in the garden. Neither myself nor the garden designer were made aware of any previous issues. The problem is that every time we have had prolonged or torrential rain water enters the site from an adjacent playing field gets picked up by the newly installed gravel paths and is directed down the garden. We have installed catch drains at the bottom of the garden and due to levels, in to a raising main. The client still has problems with flooding and maintains the design is contributory factor and looks to ourselves for a solution.

My approach now is for the client to get an indipenent drainage consultant to advise him so he can be advised the design is a symptom and not the problem. Can anyone recommend a consultant?

I'll post links to pics and video so you guys have an idea what I'm on about this evening

In the mean time thanks in advance

Clive

[lutonlagerlout]

just my 2p
we did a job next to school playing fields and every time it rained they got flooded
because it is ground water there is nothing can be done down making them do it?

we installed a ground beam and 215mm wall with a land drain behind it ,we then wrapped terram around the slotted pipe and encased in 10mm stone
first big down pour the water came out of the pipe like a fire hose,once we knew it worked, we directed this down the street (it was an end house on a hill) and so far no probs,soakaway would have been no good as the amount of water from a 3 acre field was massive
think when they built the fields they probably flatted the clay into a sloping pan which didnt help
LLL

[GB_Groundworks]

it needs catching at the boundary in a big french drain and directing into the top water through a silt trap

maybe a bit far south for Dave aka flow joe but he does work down that way

[Thehandmadegarden]

Thanks for the comments. I've got ideas on how to put it right, but I dont want to put the client to further expense without knowing we will have it nailed. My thinking is that by bringing in a consultant the the client is reassured that we are doing the best by him.

LLL Thats what I thought re the liability of the water running off the playing field. I'll try and get the council involved but wont hold out much hope.

Water in the garden
Water in the playing field

Pictures of the site

Clive

[lutonlagerlout]

I cant see the last link clive
that looks a wet site indeed
surely they had similar issues before you guys got there?
obviously you need someone qualified to give a written report,but my understanding was that if it is softscaping then surface water can run off
but any hardscaping the water must be disposed of via SUDS on their own property
flowjoe may know someone who can do this or even tony the gaffer
cheers LLL

[Pablo]

The water coming out of the ground like that in the second video suggests to me that there's possibly a blocked culvert under there somewhere causing all that surface water. I thought that the ground water thing only applied to agricultural and unmanaged land where as a playing field with paths etc is managed and the owner has responsibility for run off problems. Your hardscaping isn't a contributing factor if the ground on one side of a fence isn't dealing with the water then the ground on the other won't either it's the same soil type. The tennis court could maybe do with some drainage too but overall once you get it all sorted the place will look great. A house like that in London must be worth at least 50 quid.

[Al Jardin]

Good old london clay by the looks of it. Water unable to get through it but instead moves throught the more permeable top soil and comes up under pressure. Are there slopes?

Al

[Tony McC]

Clive - sent you a PM with 'likely suspects' in and around that London......

[Edgar]

I'm butting in here not because I'm any kind of authority on this kind of thing but just out of interest.

I noticed a mention of Hatch End and see from the OS map that Grimm's Ditch runs through that area and through a large playing field a bit south of Oxheylane Farm. I wonder if ancient earthworks could be affecting the situation!

Have you looked at the Environment flooding maps? I find them quite interesting in giving an idea of where water courses run. Further to the west from that playing field and across the railway are two areas marked as flooding. I'd guess that flood water might be coming from the direction of the playing field. What's more the contour lines seem to indicate there could be a damp bit to the south west of the field.

Whether that playing field is the one near your garden works I don't know. I'm just guessing.

It felt quite sad to see all that water in your garden works. Good luck in getting it sorted.

Edgar

[Edgar]

Further to the above. Google for "Hatch End flooding".
I think www.harrow.gov.uk/download/9250/flood_d ... t_register
might prove interesting.

[Thehandmadegarden]

Thanks guys for the input. The client has got a consultant in via the designer, so Ill wait to see what happens.
Yep its on that lovely London Clay I'm missing some good old Yorkshire clay