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Posted: Tue Aug 19, 2008 8:56 am
by mattpaint
I have just started a block driveway. I am using a contractor to dig out the excess soil and they have uncovered a gas pipe (yellow plastic) that feeds our house. The pipe is only 200 mm below the original soil layer (in places) and I really need to go down 250 mm to make sure I get a decent layer of sub base.
With a bit of careful spade work I am sure I dig beneath the pipe to lower it down by say 100mm, but what material should I use to back fill over / around the pipe. I am concerned that if I use sand it may produce a soft area that will sink in the future. Using Type 1 will result in sharp edges touching the pipe.
What is the normal approach when services are encountered?
Posted: Tue Aug 19, 2008 3:24 pm
by Tony McC
If you call the gas company and tell them you've uncovered the "gas pipe" in your driveway and that it's awfully shallow, they will often arrange to 'drop' the service pipe to protect it, and all at no cost to yourself.
However, if there's a delay or they won't play ball, the best course of action is to surround the service with 100mm or so of sand as a cushion and cover it with warning tape. Sheeting over the pipe with a good quality geo-textile is also a good idea.
Posted: Tue Aug 19, 2008 7:18 pm
by msh paving
british gas code off practice states gas service depth should be between 375 to 450mm
i found this out when they tried to take me to court for a service i damaged at 100mm deep
Posted: Tue Aug 19, 2008 7:37 pm
by Dave_L
If the dig is easy enough, I'd just dig them in deeper myself rather than get Transo/Wales & West Utilities/whoever is your local carrier involved - think of all that red tape and bullshit!!
Posted: Tue Aug 19, 2008 8:16 pm
by msh paving
GOOD IDEA,dont forget the sand bed and cover,take it steady pushing them down :O
Posted: Tue Aug 19, 2008 8:47 pm
by Dave_L
But plastic pipe should be easy.
I wouldn't advise such action if it was a steel pipe.
Posted: Wed Aug 20, 2008 11:31 am
by mattpaint
Thanks for all your replies. Luckily it is plastic and has some slack - I should be able to drop it down fairly easily.
I did give National Grid a call and got passed from pillar to post between departments - none of whom would give me an answer.
The only helpful comment was the pipe should be at least one foot down. But they are installed with a mole and if it hits a stone en-route it can go anywhere. Their guide was to look at the pavement for any sign of a hole been dug in the past and draw a line to the gas pipe on the side of the house, mark a metre either side of this line and the pipe could be anywhere in that area. Great - that covers half of the driveway!
I will drop its level and surround it with a good layer of sand.
Posted: Sat Aug 30, 2008 2:37 pm
by crack
msh paving wrote:british gas code off practice states gas service depth should be between 375 to 450mm
i found this out when they tried to take me to court for a service i damaged at 100mm deep
intresting, i didnt know that 
planning to dig my drive out and was wooried about this
Posted: Sat Aug 30, 2008 8:06 pm
by lutonlagerlout
we applied to have an iron main moved and we are looking at 6-8 weeks wait
i accidentally ruptured the pipe near to where it had to be capped and transco were out within an hour and had it sorted
we will have to pay for the repair but better than having to lay 4 blokes off for a month waiting
LLL
Posted: Mon Sep 08, 2008 12:34 am
by matt h
crack wrote:msh paving wrote:british gas code off practice states gas service depth should be between 375 to 450mm
i found this out when they tried to take me to court for a service i damaged at 100mm deep
intresting, i didnt know that
planning to dig my drive out and was wooried about this
british gas will say that these depths are guidelines, and not legislation, hence if you rupture one which they have laid at 100mm below ground(all their digging teams are subcontracted) then they cannot be held to blame.. a load of cods if you ask me. we were working on a site at wool and noticed smell of gas after concrete lorry had delivered a load to the rear of the property.I located the source of the leak...ruptured plastic pipe about 4 inches under main drive way. called transco, and in the mean time managedto stop the leak with gas tape. they tried tocharge me for the callout, but i refused to pay as i had neither caused the leak or had any control of the traffic running over the site. they threatened me with court action but i counterclaimed that as they were the gas pipe supplier theyhad failed to adhereto their own guidelines and therefore could be considered negligent in their installation and weretherefore putting the public at risk...it never went any further funnily enough..
Posted: Mon Sep 08, 2008 12:37 am
by matt h
ps compact ground under pipe and bed in pea shingle or sharp sand
Posted: Mon Sep 08, 2008 1:32 pm
by mattpaint
After a week of hard work the drive is finally complete – thanks for the various gems of information.
For the ground work I contracted in a JCB and driver for a couple of days to dig out the soil and lay the road stone. The driver exposed the gas pipe all the way back to the pavement but shortly after he had finished a slight smell of gas could be detected. I called out National Grid who found that the plastic pipe had split underneath the pavement.
After much digging the pipe was replaced and the supply restored. The National Grid lads thought the pipe must have been snagged by the digger, but I suspect it was more likely to be the digger driving over a concrete plug left in the ground where a gate post use to be. The pipe ran directly under (if not through) the concrete. The weight of the digger pushed the concrete plug down into the ground fracturing the old imperial plastic pipe. Half of the concrete plug lay on the footpath side and the other half lay on the drive side.
I am waiting to see if N. Grid will bill me for the work (I am sure they will). I will certainly argue that their pipe was only 250 mm down where the driveway meets the footpath if it comes to it.
Regarding the pipe, the N.Grid lads asked me to dig a six inch deep trench, lay 4 inches of sharp sand, compact with a pummel, lay the pipe and cover with 4 inches of sharp sand.
Posted: Wed Sep 10, 2008 8:26 am
by astro
Hi,
i've got Corgi registration, the regulations regarding buried pipework suggest that any pipe upto 50mm diameter should be at least 375mm below ground, over 50mm then it should be at least 750mm below if buried under a roadway or grass verge and at least 600m if under paving. There is a getout that if the backfill is reinforced (whatever that means) then in certain circumstancies (whatever they are!) the depths may be reduced.
Hope this helps.
Posted: Sat Sep 20, 2008 3:15 am
by matt h
also corgi registered, and you will find that the depths are only recommended...they are not legislated
Posted: Mon Sep 22, 2008 10:08 am
by astro
You are correct in that these are 'recomended' depths, however, should you manage to damage a pipe that was substatially out of this recomended depth, then any court would rule in your favour and not transco. You could easily argue that you kept your works above the BS depth so that you would not damage any buried pipes. In doing this you would have taken all reasonably practicable steps to avoid damage.The one for electrical cables is better in that it states that they should be buried so that any forseeable future works will not uncover them. so if you do dig any up, any solicitor worth his salt could get you off paying for the remedial works.