How far from the vehicle track should drainage ditch be to not risk collapsing side of track?

GervisLooper

I was making ditch on the side of the access track yesterday but later on I suddenly thought I may have done it too close! I didn't think of the possibility of them falling in at the time.

In parts it is only probably 4-8 inches from the gravel/hardcore track.

This I am guessing would risk caving at the sides when the van drove over close to the edge? I REALLY wouldn't want that and possibly have one wheel in the air unable to get a grip. Not sure how I would get out of such a pickle without help which I really don't want to have to ask for. Is it practical to get unstuck in such a case or are options limited to none for self-reliant solutions if that happens? With spinning in mud you just have to put some grippy stuff under the parts where they are stuck but if falling to the side in a ditch I think I would have had it without calling for assistance which must be avoided at all costs!

I know I could backfill with gravel to shore them up but I don't have any spare now and would prefer not buy more at the moment. I would rather have open ditches and fill the parts I made too close back in with mud again.

So what is a safe distance at a guess to have them open and not risk compromising the integrity of the track?

MikeJXE

It depends on the depth of the trench and type of soil 

Without going to the extremes of testing the soil I would use 45 degrees as acceptable in normal circumstances 

Emmia

How wide and heavy are the vehicles using the track? You'll need a wider (& more solid) track for lorries than motorcycles... And if you're concerned about weight then electric vehicles are heavier than ICE equivalents. 

Do you get 2 way traffic? Are there passing places... And what is the current track made from?

GervisLooper

MikeJXE said:

It depends on the depth of the trench and type of soil 

Without going to the extremes of testing the soil I would use 45 degrees as acceptable in normal circumstances 

I think you are not following what I was asking? I am not asking for the angle/pitch of the ditch but how far away from the track to dig to not risk the ditch falling in and collapsing the track side.

I am on very heavy clay soil so I guess that would be in my favour for once in this case to make it more structurally sound? Dug the trenchs 1ft max probably a bit less and they are only about 20cm wide of what I have done so far.

I will tell you what they they aren't half collecting some water! Several gallons after only a couple of days so must be doing something!

GervisLooper

Emmia said:

How wide and heavy are the vehicles using the track? You'll need a wider (& more solid) track for lorries than motorcycles... And if you're concerned about weight then electric vehicles are heavier than ICE equivalents. 

Do you get 2 way traffic? Are there passing places... And what is the current track made from?

It is just a single track I have made on a field for my van which weighs shy of 2 ton. No other vehicles on it. I only made it 7ft or so wide and the ditches are only a few inches off in parts. As mentioned above the soil is heavy clay so rather compacted which may lend well to the ditches being closer?

I don't want to take a chance though and get the van stuck. Would prefer fill them in and redig from further away if it could be an issue at all. It was only a day's work yesterday so can easily redo it.

I guess what I wonder is how far away from the ditch does the land around it benefit?

Hmm this image shows it being very close to the track, almost right against it so seems safe: https://roadsforwater.org/wp-content/uploads/2019/11/image099.jpg

That image is from an article which is a guide on ditches so I would imagine the example could be trusted. Oh it does look like gravel forms the track base though which is a different story to soil!

MikeJXE

GervisLooper said:

MikeJXE said:

It depends on the depth of the trench and type of soil 

Without going to the extremes of testing the soil I would use 45 degrees as acceptable in normal circumstances 

I think you are not following what I was asking? I am not asking for the angle/pitch of the ditch but how far away from the track to dig to not risk the ditch falling in and collapsing the track side.

I am on very heavy clay soil so I guess that would be in my favour for once in this case to make it more structurally sound? Dug the trenchs 1ft max probably a bit less and they are only about 20cm wide of what I have done so far.

I will tell you what they they aren't half collecting some water! Several gallons after only a couple of days so must be doing something!

Ok to explain further

If your vertical sided trench is 1 foot deep it needs to be 1 foot away, if 2 feet deep it needs to be 2 feet away 

Being in heavy clay you can reduce the distance 

Section62

GervisLooper said:

MikeJXE said:

It depends on the depth of the trench and type of soil 

Without going to the extremes of testing the soil I would use 45 degrees as acceptable in normal circumstances 

I think you are not following what I was asking? I am not asking for the angle/pitch of the ditch but how far away from the track to dig to not risk the ditch falling in and collapsing the track side.

...

45 degrees is a basic rule of thumb in groundworks (and masonry) - if you dig a trench 1 foot deep then don't apply a load within 1 foot of the edge.  If it is 2 feet deep then keep 2 feet away.

In your case you'd want to leave a much larger margin than that - I'd suggest the 45 degree rule plus 2 feet.  Allow that over time the trench/ditch will probably get deeper/wider, especially if you are already getting a lot of water in it..

Also bear in mind the work you are doing sounds like 'engineering' and therefore likely fits the definition of work for which planning consent is needed.

GervisLooper

Section62 said:

GervisLooper said:

MikeJXE said:

It depends on the depth of the trench and type of soil 

Without going to the extremes of testing the soil I would use 45 degrees as acceptable in normal circumstances 

I think you are not following what I was asking? I am not asking for the angle/pitch of the ditch but how far away from the track to dig to not risk the ditch falling in and collapsing the track side.

...

45 degrees is a basic rule of thumb in groundworks (and masonry) - if you dig a trench 1 foot deep then don't apply a load within 1 foot of the edge.  If it is 2 feet deep then keep 2 feet away.

In your case you'd want to leave a much larger margin than that - I'd suggest the 45 degree rule plus 2 feet.  Allow that over time the trench/ditch will probably get deeper/wider, especially if you are already getting a lot of water in it..

Also bear in mind the work you are doing sounds like 'engineering' and therefore likely fits the definition of work for which planning consent is needed.

That is good to know where the rule of thumb comes from as I did wonder where the other poster got those figures - not that I doubted but good to know they are general knowledge in those circles.

I will just fill them in then no bother. Better to err on the side of caution and I noticed this morning that the parts closes t to the track have least water.

MikeJXE

This might interest you, something I learned many years ago 

https://en.wikipedia.org/wiki/Angle_of_repose#Of_various_materials

GervisLooper

I filled most in yesterday and the remaining one is 4ft away now. Should be plenty eh?

Eldi_Dos

If you get a dash mounted inclinometer it could be useful in working out angle/ pitch and expected rate of fall.