Drainage, Methods, tips, tricks etc

[sledgeit]

If money is not a problem I would go for 80 mm or 100 mm pipe 20 m spacing 19mm gravel backfill 350mm from surface moles at 450 depth if your on heavy clay to carry the mole

 

[Spencer]

If money is not a problem I would go for 80 mm or 100 mm pipe 20 m spacing 19mm gravel backfill 350mm from surface moles at 450 depth if your on heavy clay to carry the mole

If money no problem, you’d be better at 10m spacing and gravel to 200mm of surface..

 

[Dry Rot]

Running sand here with iron oxide. (What do you call that?). The only way to drain is with open ditches. I have one pipe with a sleeve -- now silted up with that oxide. Without the sleeve, I could jet it.

 

[sledgeit]

I would call that ocre terrible stuff to deal with only option would be if possible to run drains to an open ditch and jet every year, not a big fan of the filter wrapped pipe as the filter can’t be cleaned

 

[Clive]

doing drainage properly is a specialis, where ever we tried too just stick a pipe through a wet spot it has rarely really worked

getting soil structure right is every bit as important, drains wont make any difference it water cant infiltrate down to them

Stopping cultivation has made night and day difference to our drainage here as infiltration has improved through having genuine soil structure full of vertical galleries to get water away from the surface fast

 

[FarmerBruce]

If money no problem, you’d be better at 10m spacing and gravel to 200mm of surface..

If money was no problem you’d buy 18 inch of topsoil sat on top of one huge chalk drain!

 

[Dry Rot]

doing drainage properly is a specialis, where ever we tried too just stick a pipe through a wet spot it has rarely really worked

getting soil structure right is every bit as important, drains wont make any difference it water cant infiltrate down to them

Stopping cultivation has made night and day difference to our drainage here as infiltration has improved through having genuine soil structure full of vertical galleries to get water away from the surface fast

The oild boy who cleaned my ditches out soon after my moving here said it would take 12 months for them to be effective for just this reason. The soil has to recover and life needs to get back into what was previously water logged. It's the worms and bugs that make the passage ways for the water to percolate through.

 

[teslacoils]

If money was no problem you’d buy 18 inch of topsoil sat on top of one huge chalk drain!

Better off flogging wet land and buying free draining land on that basis.

 

[Spencer]

Better off flogging wet land and buying free draining land on that basis.

I think that’s what he was meaning...

Wold land in particular.

 

[Boohoo]

First thing is to figure out where the water is coming from. No point thinking about a trencher if the water is 12ft down. If there are wet spots at the moment the water is coming from the dry bit so that's where the drain needs to go to.

 

[shumungus]

A friend has drained 2500 ac himself over the last 50 years. He bought a very old trencher initially and more recently added a gps levelling system to it. He’s never used stone as he says it’s cheaper to redrain as he owns the trencher. That said he hasn’t had to redrain anything yet. He bought 100ac field this year and drained it in 5 days.

I doubt there hadn't been many wet bits in it.

 

[ste stuart]

Sounds to me like you need a decent experienced contractor to advise what is best. With the best will in the world without actually seeing the land and existing drains none of us on the end of a keyboard can give you concise enough advice worth listening too when your thinking of spending that kind of money. I will say though that by the sounds of it you do have plenty of existing drains and jetting of them may give them a new lease of life. Whatever you do don’t let some pipe buryer come in and cut through all the existing drains, you’ll end up worse off than you started, find all the existing, work with/around them and if you cut through any connect them in.
why don’t you tell us what area your in, I’m sure someone on here will be local enough to recommend a contractor they’ve had good experience of.

 

[Clive]

The oild boy who cleaned my ditches out soon after my moving here said it would take 12 months for them to be effective for just this reason. The soil has to recover and life needs to get back into what was previously water logged. It's the worms and bugs that make the passage ways for the water to percolate through.

yet once ever 12 months some farmers plough and think they are improving structure by completely destroyIng it

 

[Dry Rot]

yet once ever 12 months some farmers plough and think they are improving structure by completely destroyIng it

Hmm... "Completely" is a bit harsh! I can't see a problem with burying organic matter to where the worms can get it more easily than dragging it down from the surface, but then I am not beating a drum for either side! A gardener will dig manure in, not leave it on the surface. Presumably, they have a reason.

 

[D14]

I doubt there hadn't been many wet bits in it.

What the new 100ac?

About 40ac of it was regularly underwater which is why he got it cheap as nobody wanted it. All he did was clean the ditches out and redrain it and it’s now clear of water unlike much of the land surrounding it which is sodden and flooded.

 

[ajd132]

We have been doing a lot the last few years mainly big headland drains at 20m to mole into. Pipe and using washed granite from railway lines. Have a specialist do it but they use smaller Barth trenchers and are good friends of ours so it works well.

 

[KJM]

We are at the point now that we are needing to start some reasonable schemes instead of just patching as we go. we probably need to drain the whole of a 30 acre field and then there are other wet spots that just need a pipe ran through.
There are a few options such as getting a contractor with trencher in (better for big jobs), use an excavator (probably uses more gravel which is a pricey bit now), buy a trencher (probably the most palatable option for long term) or hire a trencher.
Looking at the cost of pipe compared to gravel we could be better putting pipes in closer on schemes and omitting gravel (maybe use pipe with filter cloth on), this is mostly on silty sands and sandy loams. if we did this and used a trencher then we could still use gravel where the subsoil was higher clay content and at more risk of sealing over. But again there are lots of options.
Does any one have experience of running their own tracked trencher, or tractor mounted version.
Any opinions welcome.

We purchased a second hand tracked trencher a couple of years ago and are slowly working round the farm at a rate of a field or two a year. Most machines available are 80’s machines or older as that is when the drainage grants stopped and new sales were much lower after. They are relatively simple machines if a bit heavy to work on. The manufacturers, Barth in our case, built the machines from standard parts so replacement parts aren’t too difficult to find. Be prepared to spend a bit of time in the workshop.



You don’t mention in your post if you have any stones, if you do you want as heavy duty machine as possible. Tractor mounted machines control the depth by holding the chain out the ground on the tractor wheels or skidplates running on the soil surface. The tracked machines control depth by pitching the boot behind the digging chain which gives a better trench bottom. If you are in a lot of soft sand look for a machine with uplift to take some weight of the boot to stop it sinking.



We use gps to control the depth. It is a very helpful system once you learn it and will calculate the depth needed to maintain the grade you set. It will also create a gps map if you ever need to find drains for Jetting etc. You want the RTK base station as close as possible, we run a mobile base in the field. I think it is a much easier system than a laser when you are starting out.



We drain at 10m spacing 900mm deep with no gravel which works well for us. I suspect if you have sand in the subsoil you won’t need gravel either.



The other big consideration is pipe sizing. Igrowdrainage.org is a good site with calculators. You can have similar sized fields with very different main sizes because of different grades. The faster you can get the water to flow down the pipe the more likely any silt will move along with it. American work I read suggested if you can keep the water above 1.4ft/s it should keep itself clear.



This has turned into a bit of an essay but hopefully is some use. It is a very satisfying job and definitely can be done in house.

 

[DanniAgro]

Thanks for showing that website, KJM, very useful.

 

[DanniAgro]

The oild boy who cleaned my ditches out soon after my moving here said it would take 12 months for them to be effective for just this reason. The soil has to recover and life needs to get back into what was previously water logged. It's the worms and bugs that make the passage ways for the water to percolate through.

My wise old drainer told me that it would take somewhere in the region of twenty years for my newly drained field to fully feel the effects of the new system.

 

[Goweresque]

Are you sure there's no drains already there? Land won't have suddenly got wet out of nowhere, there's a good chance someone else had the same idea to drain that bit decades or even centuries ago. I've noticed on my place that if you look at enough old aerial photos, ones taken in summer in dry conditions will show darker lines in the crops and grass where the old drains are. The wet spots can even be where one of the old drains have become blocked and the water is being forced upwards. I've managed to dry out some pretty damp spots by locating the old stone drains and freeing them up to run again.

This website has been very useful:

Aerial Mapping - High Resolution Aerial Imagery - Get Mapping

We deliver accurate location-based intelligence by providing access to the most comprehensive aerial imagery and geospatial data on demand.

www.getmapping.com

Just put your postcode in and click 'Buy' and you can look at aerial photos of the entire country going as far back as WW2, but mostly in the last 20 years. No need to actually buy anything.