[Allan]

Hi,
I recently acquired my own little smallholding of 5 acres & I'm currently trying initially to get the drains and ditches in good order.

I have a number of field drains which are really puzzling me. They're the perforated pipes which should carry water down to the ditch. As I understand it the pipes should be empty, covered over in gravel & run horizontally down the field.
I've found 3 coming up vertically in my field, 2 of which are blocked up with mud & little pebbles (presumably the gravel that should go around outside of the pipes).
You can see from the pic. They used to have little caps on them, but 2 have broken off.


Does anyone know why they'd be set up like that, coming vertically then turning horizontally underground? It's baffling me, I cn't think of a benefit to it.

I can't get drain rods into them, even the unblocked one turns horizontal at such an angle I can't use a drain rod on it. The blocked ones go down to my elbow & then turn horizontal, but still clogged.  I can't get much more out of them.
Any suggestions on how I can go about clearing them? I'm considering digging up around them so I can bend them horizontal & use drain rods.

The field drain outlets in my drainage ditch have been cleared out up to 9m (I'm getting another set of drain rods), but I don't think they're the outlets for the 3 vertical drains, as the angles are wrong. Who knows though, I'd expect them to run straight, maybe they don't.

I'm thinking of getting a CAT (Cable avoidance tool) scanner & generator to help locate where the drains run (& locate electrical cabling I know runs under the field). Anyone know if this is likely to be a good solution, or can you suggest anything else?

Please don't suggest dowsing. I know many people have anecdotal stories but I'd rather this thread not get bogged down in talk  of that option.

Much thanks

[SallyintNorth]

I wonder whether the "up" pipes are there to mark the route and/or enable testing of sections? 

Usually the routes of field drains are evident to the experienced eye, especially when the ground is particularly wet, unless covered by very thick vegetation (eg rushes.) 

And yes, digging down to reveal and then unblock blocked sections is how it's done.  My 6' ex used to be regularly out of sight digging out sections of ours!  (The sections needing attention being evident when waterlogging occurs upstream of them in winter.  Mark the spot then, do the repair in better weather...   )

[chrismahon]

I can only tell you what they do here, but the upward pipes that break the surface are the top ends of the pipe allow air to enter. This then allows the water in the pipe to full flow out, otherwise it would be air locked and just trickle out letting air in at the bottom. Like turning a full water bottle upside-down.


I'm soon to install the very same arrangement, but tidy it up a bit because here they leave a long loop sticking out a metre which, although it stops mud going into the pipe, looks an eyesore.


To clean these pipes you would have to send a high pressure hose up from the bottom end with a special nozzle on it.

[Allan]

SallyintNorth, Sadly I'm not able to identify where the drains run from the vegetation. A lot of it is covered in rushes, but even the bits that aren't don't stand out, even when there's been a frost.

I can make some educated guesses, based on where the 'up' parts are, but no more than guesses until I start digging.

Chrismahon, that's interesting, I've never seen any reference to the need to have an air vent in online reading, but I suppose it makes sense if the soil is thick and impermeable. I'll try & look into that more.

It sounds like the loop may be a better method, at least going by the trouble I've had trying to clean out the mud & stones in one of mine.
I think an alternative, at least for newly constructed ones, may be a sufficiently thick layer of clean drainage stones surrounding the pipe, which I'd think would give enough air holes to allow air to go through. I don't know if I'm right on that though, need to read & think a bit more on it.
In any case I don't know if I'm at that stage, will need to dig out the existing ones & see if I can improve the water flow first.

Sadly I may have to excavate from the protruding part as I won't be able to get high enough pressure at the drain outlet points, or power to run a pump.

In any event I'm going to make new caps & cloth filters for the protruding parts of the perforated drainage pipes & at least stop them getting more clogged till I can dig out & clean them.

[chrismahon]

If they do use gravel around the pipes here I haven't seen it done. Our soil is heavy clay which liquifies in Winter, so any gravel won't be effective for long and it certainly won't be laid up to the surface because that would either be ploughed over or trampled by livestock and wouldn't allow any air into the pipe.

[Kiran]

The vertical pipes are surface inlet connections. Usually they would extend up out of the ground with a cap but I'd guess they've been damaged. It's designed to take surface water into the drainage line below