DIY drainage query?

[ABCwarrior]

Our house is built on essentially river/glacial till, no soil around it just gravel/sand/stones. Bizarrely though there seems to be a strata of clay within it somewhere, and water pools near the DDA compliant ramp at the entrance when it rains heavily. I've put a fencing bar in to a metre and haven't broken through it.
We've just spread 30 tonnes of topsoil at that side of the house and seeded it, hopefully the vegetation may take up some of the water next time it rains heavily. The gap between the house and the soil is about 1.5m. The seeded area has a border of boulders(have to put them somewhere!) and we plan to put down gravel between the border and house. If We find it still pools there it will waterlog one corner of the grassed area. I've looked at the drains and there's an oval rodding eye adjacent to the front door(pipe runs parallel to house draining the other way), about 3-4m from the problem area. If I dig this up, can I remove this end, dig a trench to the problem area, excavate a small pit, put a 3-4m pipe on the end and ensure it's running downhill to the rest of the pipework, cover the end of the pipe in a filter of some sort(terram?) and bury the lot under gravel?
It removes the rodding eye but hopefully water then wouldn't pool, it would be easy enough to access if it needed cleaned/renewed and would hopefully move the water to the proper soakaway they installed when the place was built which does work properly.
If I dug a small pit surely this would fill, then enter the pipe and all be below current ground level?

Hope this isn't confusing, any advice appreciated!

 

[RedHerring2]

I'm sure this site will help you immensley:
http://www.pavingexpert.com/drainage.htm

Are you sure this rodding eye goes to the soakaway for surface water and is not part of the foul water system?
If so, I think, there's no reason that you can't direct additional surface water to the soakaway, other than you might exceed the designed capacity for the soakaway.
Bear in mind that:
a) soakaways have a definitive lifespan.
b) If you direct additional water, you could effectively reduce that lifespan.
c) Any particles in that water will reduce the percolation capacity of the soakaway.
d) you can retain the rodding eye by adding a 'y' junction.
e) If you don't retain that rodding eye consider adding one further up the run.

 

[ABCwarrior]

Ta for the reply- it's definitely just run-off from the roof, the pipes are easy to trace and the septic tank is at the other side, 2m from the patio(well, micro patio 3x1m), we have the plans for the house services and the septic tank effluent goes down the slope at the front of the house through a switchback pipe system to presumably a soakaway(I was digging a hole at the boundary for a tree and discovered terram with what felt like just gravel below).
There seems to be 2 manholes for some reason on the runoff network- one is at the corner of the house and is the main junction where the drainage from both sides meets- this then goes to another manhole which is where the contractor told us the soakaway was. Only one brown pipe can be seem leaving manhole 1 to manhole 2, and there are no pipes leaving manhole 2 so I'm wondering whether it's sitting directly on top of the soakaway and just leaks out of all the pipe entrance points into the soakaway( By Manhole I mean one of those covers over a network of channels that meet just below the surface)
Given the shoddy workmanship all over the place including broken covers to the septic tank done when the roof trusses were installed I doubt whether they'll have stuck to some rigid design of the soakaway. As long as they've got the water away from the house and below this clay layer(if it's even at that end) I doubt that drainage will be a problem given the underlying material.
Will the rodding eye as it is be on a y fitting (saw in screwfix they're at 45 degrees, presumably the y on it's side gives the 135 degrees to make the 180 and keep the lower pipe level?). If it has a Y on it I'll just retain it as it is and extend the lower part.
Might be better to do this before we get any more heavy rain. I doubt if that flexible field drainage woud interconnect with this pipework but another consideration would be to properly cap the end of a new section of pipe(or add a rodding eye as you suggest), and drill the pipe along it's upper half to act like a field drain, maybe wrap the drilled section in terram and jubilee clip it at each end?

 

[RedHerring2]

I'm not sure I follow your last paragraph.
Yes, you've got the idea for the 'y' junction for rodding eye. You can get what is called 'a rodding point' which is a rodding eye combined with a bend. This will bring your rodding eye cover horizontal after coming off the upstand of the 'y'. No problem if you need to extend it with a bit of pipe.

I thought you mentioned just 3-4 metres, so just use a piece of rigid perforated pipe. You might need to order it from your BM. It's the same dimensions as normal underground pipe so fittings are the same.
I suppose you could drill a load of holes in a normal pipe. Typical underground drainage pipe in France has slots cut into the pipe up to nearly half way through, but this makes the pipe inherently fragile.

If you are going to add a rodding eye on the extension, you may not need the original. I think 25 metres between rodding eyes is OK. So on the extension, just add a bend and a rodding point to the end of your pipe.
Or re-use the original.

Edit;
Just worked out your last paragraph, I think. The geotex material doesn't go that close to the pipe. Geotex material in the bottom, gravel in next, lay the pipe, surround with gravel, fold geotex around gravel.

Make sure you follow the instruction for installing the geotex fabric. In the UK I've bought it as a large sheet, something like 4 metres X 8 metres, but in France it was available on a roll, something like 50 metres long.
It's a bit of a pain to use in the trench, especially on windy days. Use a long timber batten each side of the trench to hold it in position while you're working in the trench.

 

[ABCwarrior]

Ok getting it now! Think I could remove the rodding assembly, add a perforated pipe to the prob area and add the rodding eye to the end as the total length will not exceed 13m. The perforated pipe sits in a trench lined with terram and the pipe is surrounded by gravel and wrapped up over the top in terram again to stop the gravel clogging over time with fines.

I have a 3m length of pipe which is why I thought drilling it could work, it's not deep underground and won't have any traffic on it bar humans so as long as I don't get carried away it should stay structurally sound?

 

[RedHerring2]

You've got it. Don't put that clay soil back on top though. I can't remember how much gravel the paving expert site suggests, but there should only be top soil going on top.

 

[ABCwarrior]

It'll just be gravel where it will be so drainage should be as good as it gets!