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Vacuuming a hole in the road

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Vacuuming a hole in the road

Postby Robert » 11 Jan 2017, 10:30

We having our gas mains replaced.

Interesting hole making technique - they break up the dirt then vacuum it out of the hole. Covering my car with dirt in the process though they have at least put a dust sheet over it to catch the worst.

Image

Image

The guy with the thin pipe has a compressed air lance that blows dirt towards the suction pipe... and over my car.

They started a week ago. this is only the 3rd day we have seen anyone working.
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Re: Vacuuming a hole in the road

Postby Tusses » 11 Jan 2017, 11:23

that sounds like a pain

you would think they could put one of them workman tents up around it or something ?
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Re: Vacuuming a hole in the road

Postby Robert » 11 Jan 2017, 12:08

They expose a length of the main pipe then drill holes into it for a camera inspection so I guess escaping gas and inside tents is not an option :)

There is some kind of clamp on gland to reseal after drilling.

Our supply will be interrupted at some point but no idea when yet.
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Re: Vacuuming a hole in the road

Postby Tusses » 11 Jan 2017, 12:42

Robert wrote:They expose a length of the main pipe then drill holes into it for a camera inspection so I guess escaping gas and inside tents is not an option :)


very true !

Robert wrote:Our supply will be interrupted at some point but no idea when yet.


When they did our street , maybe 20 yrs ago, they did it live, and used expanding foam to seal the joins
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Re: Vacuuming a hole in the road

Postby Rod » 12 Jan 2017, 01:17

Are they replacing or repairing the existing mains? They don't normally drill holes in new installations to check them out but use a pressure test. The pipes are generally joined by a special clamped on "heater" which fuses the plastic.
They should also diamond saw the edges of the surfacing to get a clean cut line.
I've never seen them use pressure hoses and suction pipes like this before - they should certainly protect surrounding areas and not blast out dust etc. Is the local highway authority keeping an eye on them? It should all be carried out under PUSWA.
Sadly the utilities never reinstate the roads properly and ruin its integrity for ever!

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Re: Vacuuming a hole in the road

Postby Robert » 12 Jan 2017, 11:25

Replacing.

They want access to the house to replace the pipe to our gas meter too but no idea when.

There are big reels of 3 inch ish yellow pipe laying around in various places. They have been camera surveying the existing mains I'd guess to check the liner pipe will pass ok.

They set up the camera and screen right outside and I had a front row seat. I'd say the pipe was 1/3rd full of debris. sometimes the screen went black as they ploughed the dust with the camera.


Image


Image



Image

Thames water have been around at the same time fitting water meters in the pavement. They cut the hole edges with the pneumatic drill. When the last guys came along to resurface at the end they diamond cut the edges clean before asphalting.
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Re: Vacuuming a hole in the road

Postby RogerS » 12 Jan 2017, 14:26

Fascinating photos, Robert. I know that if it was y car parked there I'd be going over the bodywork and windows with a fine toothcomb.
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Re: Vacuuming a hole in the road

Postby Robert » 19 Jan 2017, 23:34

Today was our new pipe to the house day.

No gas from 11am until an hour ago. It was getting a bit chilly towards the end. Been fascinating seeing how they work. The gas main is a 6" bore cast iron pipe this side of the road. The other side is 8".
Yesterday they fed what looks to be a 4" poly pipe through it without interrupting our supply. no idea how.
Today from 8am they dug access holes where (they said) 29 house supplies meet the main. Once they had all the holes just before 11 the gas went off. they then had 2 or 3 teams working down the holes and in peoples houses.
In ours they first removed the gas meter then hack sawed through our pipe in the hole in the pavement. Once the small pipe was cut they smashed the cast iron main pipe with a steel bar exposing the yellow plastic pipe inside.
With the main out of the way they then tried to push a liner pipe all the way to the meter position.... but it wouldn't turn the elbow corners. So they dug up our front drive near the house and cut a foot of pipe out. They then blew a rope down the pipe with compressed air from the meter position and connected it to a corrugated extra flexible pipe. Push and pull then got that pipe through.

Seems most houses this side were difficult to get the liner pipe through and they are still working outside on other houses now.

nice to have the heating back on :)
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Re: Vacuuming a hole in the road

Postby RogerS » 20 Jan 2017, 13:01

It really is impressive how they do these things. I remember when renovating a flat in London I needed a gas pipe removing. Chaps arrived and wrapped a plastic bag around the union in the riser having previously put inside it all the nuts, washers, sealing gunge, tools etc. Plastic bag duly sealed. It had tubes going in where they could put their arms...bit like one of those bio-hazard cabinets. They undid the pipe, there was a massive ker-thud as full mains pressure appeared inside the plastic bag expanding it like a very tight balloon.

Removed the pipe, fitted a blanking plug, sealed it all up, removed the bag and opened the window. Job done.
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Re: Vacuuming a hole in the road

Postby RogerS » 20 Jan 2017, 13:02

It really is impressive how they do these things. I remember when renovating a flat in London I needed a gas pipe removing. Chaps arrived and wrapped a plastic bag around the union in the riser having previously put inside it all the nuts, washers, sealing gunge, tools etc. Plastic bag duly sealed. It had tubes going in where they could put their arms...bit like one of those bio-hazard cabinets. They undid the pipe, there was a massive ker-thud as full mains pressure appeared inside the plastic bag expanding it like a very tight balloon.

Removed the pipe, fitted a blanking plug, sealed it all up, removed the bag and opened the window. Job done.
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Re: Vacuuming a hole in the road

Postby Rod » 20 Jan 2017, 13:18

Are they replacing the 6" & 8" with 4" ones or is the 4" just a liner?
They often line old iron mains with flexible chemical liners which expand to the internal diameter of the original pipe and then chemicals react to solidify it.
I think I've told the story before of a major job I was on, a disgruntled gas employee ( he'd been given notice) drilled tiny holes in the new plastic gas pipes being laid. Wasn't found until they did a pressure test and the whole lot had to be replaced! Delayed the scheme and cost a lot of money - they never proved who did it either.

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Re: Vacuuming a hole in the road

Postby Phil » 20 Jan 2017, 13:58

RogerS wrote:It really is impressive how they do these things. I remember when renovating a flat in London I needed a gas pipe removing. Chaps arrived and wrapped a plastic bag around the union in the riser having previously put inside it all the nuts, washers, sealing gunge, tools etc. Plastic bag duly sealed. It had tubes going in where they could put their arms...bit like one of those bio-hazard cabinets. They undid the pipe, there was a massive ker-thud as full mains pressure appeared inside the plastic bag expanding it like a very tight balloon.

Removed the pipe, fitted a blanking plug, sealed it all up, removed the bag and opened the window. Job done.



Ok, Roger, I think we got it the first time. :lol:
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Re: Vacuuming a hole in the road

Postby RogerS » 20 Jan 2017, 13:59

Phil wrote:
RogerS wrote:It really is impressive how they do these things. I remember when renovating a flat in London I needed a gas pipe removing. Chaps arrived and wrapped a plastic bag around the union in the riser having previously put inside it all the nuts, washers, sealing gunge, tools etc. Plastic bag duly sealed. It had tubes going in where they could put their arms...bit like one of those bio-hazard cabinets. They undid the pipe, there was a massive ker-thud as full mains pressure appeared inside the plastic bag expanding it like a very tight balloon.

Removed the pipe, fitted a blanking plug, sealed it all up, removed the bag and opened the window. Job done.



Ok, Roger, I think we got it the first time. :lol:


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Re: Vacuuming a hole in the road

Postby Robert » 20 Jan 2017, 16:33

Rod wrote:Are they replacing the 6" & 8" with 4" ones or is the 4" just a liner?
They often line old iron mains with flexible chemical liners which expand to the internal diameter of the original pipe and then chemicals react to solidify it.
I think I've told the story before of a major job I was on, a disgruntled gas employee ( he'd been given notice) drilled tiny holes in the new plastic gas pipes being laid. Wasn't found until they did a pressure test and the whole lot had to be replaced! Delayed the scheme and cost a lot of money - they never proved who did it either.

Rod


The main pipe is 4" now. Most of the pavement holes are now filled and surfaces.

They came along first with green half pipes (like guttering) and clamped them around the places they had smashed away the Virgin and BT cable pipes. guess it won't be too easy to pull new cables now but it is still possible. The pipes were above the gas main. cables bend out of the way, pipes don't.

before (with a plug in the camera inspection hole)
Image

and after
Image
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