Yup, that does seem a bit excessive...
Some of the bigger walk behind trenchers can get down to ~1m with a 5 -
6" trench.e.g:
The Romanian builders on a nearby site watered their backfill! Presumably as an aid to compaction.
That works reasonably. Some soil can be compacted to a greater extent than it was before it was dug out.
If you don't compact it, it will do so on its own in time. Leaving a depression.
If you've got it all ready? depending on access, a man & machine £300/day, a day to dig, lay backfill? Where does excess spoil go?
Last trench I did across a lawn, I cut down both sides to full depth of a spade, then prised out chunks of turf and clay with a mattock (so not "de-compacting" those much). Then dug a bit further with the mattock, gave the bottom of the trench some blinding with soft sand, laid my SWA, part filled with the loose spoil, laid a cable warning tape, then put the lumps back and any pother spoil. Rammed it down with an elephant's foot style flat weight on a stick. It all went back level with no left over spoil. You can't see where it was now.
(that was only 12" or so deep - probably harder to get it all back in a deeper trench)
Your trusty building knowledge coming to the fore again Duhve?
All down to cost I suspect.. how much is a moling operation for a day? Must be more than aman&adigger?
From what little I've seen of the ditch witch I wasn't impressed. A digger did much better.
NT
Over 15m distances? I bet a tractor up to that will be 4m long itself...?
Oop north lad.! I don't need a digger&man to lay flags do you? I asked about spoil already.
How many metres going does it take to get the mole down to 1m, & back out again?
Wet clay is "better insulation"??
Thank Google you caught up Duhve!
Perhaps we'll find an opening for your cough "waterproof" mortar in the thread :-what with your knowledge & experience etc etc.... :-D:-D
How deep?
Hmm OP was after a metre.
So in the 15m run how much would be "at 60cm depth" versus your "down & up gradients"? (assuming there's room to run in & out)
If you dug the trench you could go "straight down" then turn horizontal dependent on the bending radius of the pipes & cables which from the sounds of it will be quite tight...
Pipes & cables don't need a gradient but your mole plough does...
(Except drainage but that's not relevant here).
I don't drink Duhve.
Yet more of your armchair expertise coming through?
Did you believe mortar was waterproof when you rebuilt your roof parapet? Oopsy!
Er... How do you know none was taken away?
You mean Duhve Duhve? Just my invention - it suits you don't you think? Duh?
Any advice from you, has zero value for me, Duhve :-D
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