Using a mole to lay pipes

[The Ruminant]

We've a 150m run of pipes to lay and are planning to hire a mole to pass under a concrete yard.

At what intervals would we need to dig an inspection pit to keep the mole on course? We're fairly stony ground so it's likely to veer off when it hits a stone

 

[Selectamatic]

I'm not sure that you would?

The pipe follows the mole, the mole follows the tractor?

 

[Steevo]

We've a 150m run of pipes to lay and are planning to hire a mole to pass under a concrete yard.

At what intervals would we need to dig an inspection pit to keep the mole on course? We're fairly stony ground so it's likely to veer off when it hits a stone

Depends how long a pipe the mole man has I think. Best ask the contractors.

They can trace from above ground I think to check the course.

 

[The Ruminant]

Depends how long a pipe the mole man has I think. Best ask the contractors.

They can trace from above ground I think to check the course.

We were planning to hire the mole and do it ourselves so we are the contractors! If it's traceable from above that would give some reassurance. Are they traceable?

 

[The Ruminant]

I'm not sure that you would?

The pipe follows the mole, the mole follows the tractor?

I'm talking about a mole that runs on its own, and can pass under a concrete yard, not one pulled by a tractor

eg http://www.molingsolutions.co.uk/

 

[Selectamatic]

I'm talking about a mole that runs on its own, and can pass under a concrete yard, not one pulled by a tractor

eg http://www.molingsolutions.co.uk/

Oh! Sorry!

 

[milkloss]

I think the answer is that you dig a hole where you have to! I guess you’ll get a cat and genny with the tool.

 

[phillipe]

The kne we used were grundomat moles,about 30 metres ,cat a genny easy to trace ,you stand above it and you feel where it is.

 

[The Ruminant]

The kne we used were grundomat moles,about 30 metres ,cat a genny easy to trace ,you stand above it and you feel where it is.

Interesting, thanks. What depth was it working at when you could feel it? How accurately could you tell where it was? Within a foot? A yard? Ten feet? My worry is that it goes wildly astray and we have to keep withdrawing it and starting again

 

[Suffolk Serf]

I've seen a contractor with a Vermeer mole do it over a hell of a distance for a new water main. Under rivers and roads too.

 

[phillipe]

Interesting, thanks. What depth was it working at when you could feel it? How accurately could you tell where it was? Within a foot? A yard? Ten feet? My worry is that it goes wildly astray and we have to keep withdrawing it and starting again

Within 3 inches,we dug a hole either end put the mole in and it appeared in other hole at arond 2ft 6 .there are much better mole that can be steered ,we were in clay

 

[Badshot]

I went about 40 feet with one. Came out within inches of the intended destination.
We do have some sandstone there, didn't seem to affect it at all, or I just got very lucky.

 

[The Ruminant]

All sounds good. Unfortunately we've flinty ground. Apparently if you hit a large flint it can disappear, next to be seen in Stevenage....

 

[Badshot]

Make sure you mark the pipe at the length it should appear in your exit hole. If you get far beyond that mark (electrical tape is good) then you need to try again, or dig for it.

 

[Matt]

What would it cost to get a contractor to do it for you vs hiring it?

 

[Blue.]

If your on Flint I'd be digging it in and bedding with sand.

 

[RockyKildare]

I’ve been moling for 20 years with all different sized moles. If flinty ground I’d put a pit every 15-20ft. If you use a 75mm mole you can tow through a 50mm solid duct by reversing it out of the hole, attaching it to the head with wire. Then just push your water pipe up that. No chance of damage to the water pipe then.

Benefits of a 75mm over a 50mm is that it’s more accurate. The longer the mole the more accurate. The larger the diameter of mole, the longer the mole A 75mm mole won’t cost much more to hire than a 50mm.

I’d be atleast 600mm deep with my mole. In virgin ground ideally. If you can’t get to virgin ground remember to put a bit of fall on your mole. (Just a bit though, that’s where experience comes in!!!) If the ground isn’t solid around the mole it tends to work it’s way up to the surface, where there is less resistance. Hope that helps
Oh, and remember to check for electric, gas and sewage locations.

 

[Matt L]

As above. Can be a bit nerve racking but if you make the pipe with insulation tape every metre you can judge how far you have gone into the ground. They will sometimes dive and then come back up again if you hit a lot of stone but the bigger the mole the more stable. 75mm mole should push most stone aside or shatter them.
Just check you wont be overly charged for score damage if in really stoney ground.

 

[Matt]

I’ve been moling for 20 years with all different sized moles. If flinty ground I’d put a pit every 15-20ft. If you use a 75mm mole you can tow through a 50mm solid duct by reversing it out of the hole, attaching it to the head with wire. Then just push your water pipe up that. No chance of damage to the water pipe then.

Benefits of a 75mm over a 50mm is that it’s more accurate. The longer the mole the more accurate. The larger the diameter of mole, the longer the mole A 75mm mole won’t cost much more to hire than a 50mm.

I’d be atleast 600mm deep with my mole. In virgin ground ideally. If you can’t get to virgin ground remember to put a bit of fall on your mole. (Just a bit though, that’s where experience comes in!!!) If the ground isn’t solid around the mole it tends to work it’s way up to the surface, where there is less resistance. Hope that helps
Oh, and remember to check for electric, gas and sewage locations.

how big a mole can you get?

 

[Matt L]

Once you get above a certain size it becomes a thrustbore but they can be up to 2500mm diameter. Uses a steel tube which effectively cores the ground.