Ducted Water Main

[sako243]

I can understand the benefits of ducting a water main under a building, can’t see the sense in it outside. In the highly unlikely event of a new mdpe main outside leaking it soon shows where it is.

Bob

If it is in a duct the leak will not show where it actually is, it will show wherever the duct ends.
Another reason not to use it!

I'm fairly sure Welsh Water now mandate (or very strongly advise) new pipes are installed inside ducting with pea gravel or sand around it because most of the ground here is shale and cuts through the pipes fairly easily and they've got enough leaks in the system as it is.

 

[Pete.]

Had one done under a trunk road this year for a water pipe. They put an post one side and used a kind of site to aim it in the correct direction and set it off. The bloke doing it said our soft sandy ground with flints in it was the worst for them going off course but this one came out within a foot of the post.

I saw some guys in Chatham years ago had to dig one of with a JCB. It hit a big lump of something then went almost straight down

 

[8ob]

I saw some guys in Chatham years ago had to dig one of with a JCB. It hit a big lump of something then went almost straight down

I have six of them ranging from 40mm to 135mm od and never lost one in thirty years. They are a displacement hammer so as long as the ground will displace and its stable enough to keep a grip on the machine it will get there, best accuracy I have achieved in one run was 50mts with 6mm of deviation on a 135mm machine. 99% of the time its within an inch over 25mts. Chalk is the best ground for keeping the machine stable, big flints etc just get smashed out of the way. They will smash through a hidden brick built manhole, in one side and straight out of the other with no bother. Loose soils, soakaways or made up ground are the hardest to deal with, these things ideally need to be in undug ground at a minimum depth of 10x the machines diameter. Its the meathead service layers that have got these machines a bad reputation, if they had to buy them it would be a different story.

Bob

Any budget jobs are done with our chain trenchers, better than an excavator because the spoils are ground out and being fines they always go back in the trench.

 

[Onoff]

I'm fairly sure Welsh Water now mandate (or very strongly advise) new pipes are installed inside ducting with pea gravel or sand around it because most of the ground here is shale and cuts through the pipes fairly easily and they've got enough leaks in the system as it is.

Both the water pipe duct and electric duct will be encased in pea shingle.

 

[8ob]

Both the water pipe duct and electric duct will be encased in pea shingle.

We use as dug soft sand from the quarry to cover any services in boney ground, its less than £10 a ton.

Bob

 

[Onoff]

We use as dug soft sand from the quarry to cover any services in boney ground, its less than £10 a ton.

Bob

Tbh I did consider just using the soil that came out of the trench but sieved. Ah well, I should have built that trommel I was going to.

 

[8ob]

Tbh I did consider just using the soil that came out of the trench but sieved. Ah well, I should have built that trommel I was going to.

The as dug sand is so cheap its probably not worth the effort, that said if you did recycle what you have you wouldn’t need to skip any excess away.

Bob