Lowering drainage pipeline - Horror show

[Richie]

Hi, I've created a horrow show in my folks back garden by unearthing a drainage pipeline.

The idea is to a lay a path for them alongside their extension (currently there's a mud track). As the builder laid the pipeline so close to the surface it needs lowering to make way for the path's foundation, right?

My question is, can I just replace the current connection with the downpipe (see picture) with a vertical pipe and take that end to 0.9m underground (recommended depth?) and then lower the rest of pipeline accordingly. The other end is about 2m depth attached to a drain and not that far away so gradient won't be an issue.

http://www.flickr.com/photos/37382289@N05/5058045742/

Also, can some tell if there is a risk of subsidence as I've left this trench (well, my amateur version of one) stagnant for a little while.

I'm a complete novice, and it appears I'm acting like a cowboy. Please someone, show me the light!

Rich.

[GB_Groundworks]

get rid of the cowboy bit of clay bend, on a second look it plastic but faded as pipe isnt uv stabalised, hes used and get your self a trapped gully from bco etc, thin they are about £40

position this below the downspout then unearth the pipe at the other end, ( the lowest end) then you know how low you can go, want a quarter bubble on your spirit level of fall, so then just connect from the gully to the pipe and you'll have enough cover.

you can either go really low and get the recommend cover of 900mm or cover it with a lean mix of concrete, bed the pipe on pipe bedding(10mm pea gravel) then cover in concrete etc sub base then path etc



Edited By GB_Groundworks on 1286395974

[seanandruby]

think you will be taking on to much work to drop pipeline and probably won't gain much, if any, depth. How much below dpc'is the pipe? Would'nt bother with gully as you can drain by falling away from house into garden. Get an adaptor to take you straight into top of rest bend. Put in an edging and lay on screed or concrete.

[Richie]

I really appreciate these suggestions.

GB_G: to double check my understanding on one point, there would be no concrete beneath the pipe in the method you showed. Instead, the pipe is lowered a little, laid on pipe bedding then a lean layer of concrete and then the path and its bedding. Did I get that correct?

Sean and Ruby: the dpc tops the second layer of brick on the corner. Are you suggesting I can direct the rainwater from the roof (it's only one side of the roof of a short extension) directly into the garden and negate the need for that part of the pipeline?

[lutonlagerlout]

where do you get 0.9 M recommended depth from richie?
1:80 is the fall needed for rainwater, depth is irrelevant
why have you dug that trench when there is no need?

the pipe looks like it was encased in pea shingle originally,which is correct
all you had to do was removed top soil,add some type 1 ,then lay your path
you need to get that pipe covered before the sun turns it to dust
cheers LLL

[seanandruby]

definetly no! You keep all the pipework in situ. The path itself will drain into the garden so no need for a gulley. As lll states there was no need to dig out anything, around pipe. Hope this clarifies things. Again....don't remove pipe!!!

[Richie]

The reason I wan't to lower the pipeline is because if I don't I'll be laying the path foundation directly onto the current pipeline level which is only 2 bricks below the damp proof course. And I understood going above the dpc to be a no no.

LLL: Right, I'll get the pipe covered quickly. Regarding depth, I was taking advice from documents on the web. According to this page 0.6m is the minimum for plastic pipe in a garden (not 0.9m as I put before). http://www.pavingexpert.com/drain02.htm
Do you think that is unecessary in this particular circumstance?

SeanandRuby, gotcha, I definitely won't remove the pipeline altogether.

I'm almost there. Any words of advice/encouragement to tie this up will be greatly appreciated. I have to say, I'm currently favouring the gulley option because I can't see a way of building upwards from the current level without compromising the dpc and/or damaging the piping. If you reassure me that's not going to happen I'll prefer the easier route.

[Richie]

To make it clear, the path will be laid directly above the route of the pipeline.

[lutonlagerlout]

richie we are not talking the Eiffel tower here,you would only impinge the 150 rule by maybe 20mm
and its only a rainwater pipe
if it was a shared sewer pipe i might be worried,but you do not want to overcomplicate this
LLL