digging a trench for a new water pipe connection....

[xelaris]

I'm digging a trench for laying a duct for a new pipe connection (and get rid of old lead pipes).
The trench is about 1m deep - I'm about to complete the job which involve laying some sand on the bottom of the trench to accommodate the 100mm duct with a 25mm pipe inside the same duct.
Problem is that overnight the trench got partially filled by a couple of buckets of water....is this normal? Shall I just lay the sand and duct and wait for the inspector from United Utilities to turn up?! What will he make of the standing water? How is he going to inspect the trench? (with goggles and respirator? LOL)

Another problem is about sealing both ends of the duct....United Utilities doesn't specify if the pipe should be sealed inside the duct - at least in the duct end concerned with them....the one which ends just outside my property about 750mm below ground.

All in all I find this lack of details from United Utilities quite unnerving (I rang them but I'll have to wait till Monday for an answer)....a picture of a finished work (the sealed ends in particular) would help greatly instead we are presented with some graphics which leave a lot to interpretation....then the inspector would find all excuses to delay our works and more....

Can anyone point to a specific picture/link of similar jobs?

 

[picasso]

This should answer your questions

http://www.unitedutilities.com/documents/1344_How_20to_20lay_20new_20pipe.pdf

 

[ianmcd]

You are worrying about nothing , as long as the minimum depth has been adhered to then the inspector wont be bothered about anything else

 

[xelaris]

You are worrying about nothing , as long as the minimum depth has been adhered to then the inspector wont be bothered about anything else

Not true....there are certain requirements and it's better to comply to them as much as possible. Then, in my experience - certain water companies (don't forget these are private ones) aren't that keen on certain jobs and would find excuses to delay/avoid them....of course they are obliged by law - but as I've mentioned - if you need them in a remote area or at the end of certain roads one might have to send an extra letter or phone call to get them moving (true).

 

[xelaris]

This should answer your questions

http://www.unitedutilities.com/documents/1344_How_20to_20lay_20new_20pipe.pdf[/QUOTE]


no, it doesn't (I have that anyhow). You aren't supposed to dig under the public area (e.g. a pavement)....the graph shows this long pipe going from your home to the public area (how do interpret that?).
Then, how would you seal the end of the duct? Would you keep the pipe inside the duct (before the duct seal) or make a hole in the duct seal with the pipe hanging a few centimeters from it?
Why they don't just make it 100% clear? e.g. with a picture of a finished work of what is expected?

 

[picasso]

no, it doesn't (I have that anyhow).

Yea excuse me for trying to help, the duct is filled with insulation from where it comes through your floor to where ever you decide to end the duct, the duct has to be a minimum of 750mm deep but most people run the duct the full length of the mains pipe, (helps when replacing the pipe) be interesting to see how your going to connect the new mains without digging under the pavement

View media item 75532 drill a hole in it.

 

[MANDATE]

As I understand it, you dont need any ducting along the bottom of the trench. The 100mm ducting is to hold the insulation between entry into the property to the floor level. This ducting has to be sealed at both ends.
The purpose of the sand bed in the trench is to prevent damage to the pipe or of course you could use a smaller size ducting instead of sand and this would not need any sealing.
How do I know this?
Well I did it with the full agreement of United Utilities.
I also penitrated under the rear yard wall foundations, coming up and leaving ample pipe for UU to connect.
I do agree however some of the drawings contained errors which I pointed out at the time and that must be about 10years ago.

 

[bamber]

Dig trench 32 inches deep, lay 25mm alkathene main, only protection required is a sleeve (thermoflex) where it enters property.

 

[xelaris]

no, it doesn't (I have that anyhow).

Yea excuse me for trying to help, the duct is filled with insulation from where it comes through your floor to where ever you decide to end the duct, the duct has to be a minimum of 750mm deep but most people run the duct the full length of the mains pipe, (helps when replacing the pipe) be interesting to see how your going to connect the new mains without digging under the pavement

View media item 75532 drill a hole in it.

thanks a lot of the useful tips....
Just a point: I don't have to dig under the pavement - United Utilities is going to do that for me - and the new water mains are located about 16m from my property (you don't want to do that).

 

[Tipper]

In my experience the Water Co. never actually came to inspect!

They told me to leave the trench open for 5 days, during which time they would inspect, then I could backfill it when I chose. They never came.

Don't expect they will even bother to come.

 

[Norcon]

If your laying a duct then no sand is required though the utility companies will still probably insist on it.
Even if you take the time and ensure the water main is surrounded by sand or pea gravel its no guarantee the pipe won't be punctured during backfilling or from traffic.
Polyplumb utility ridgicoil is a good option and colour coded for the appropriate utility.

 

[xelaris]

As I've mentioned already....there's no point trying to cutting corners - the sand might not be necessary but if the inspector doesn't see it he would find excuses - they do - this is my experience with UU...

Anyone has any view about the standing water inside the trench? As I don't see replies about this particular issue I'm bound to believe this isn't normal. This morning it took 3 buckets to clear it up.....I guess this is raining water seeping from the more permeable layers around the trench....
What bothers me is that I'll have to make the duct waterproof cos' if water filters inside it will affect the insulation around the pipe. Still, I believe the problem will go once I refill the trench but I'll have to wait for the inspector to come and check and in that time the trench gets filled with rainwater!

 

[Norcon]

You could always dig another trench to keep that trench drained.

 

[MANDATE]

I don't see the water in your trench being a problem. I used about 1.5 metres of 100mm ducting with insulation as per requirements. The ends being sealed with sand /cement after wrapping the pipe with tape to prevent contamination from the cement.
The rest of the trench had 50mm ducting over about 6 metres. The ends were not sealed. Gap between 100mm and 50mm ducting did have sand in that area.

 

[xelaris]

You could always dig another trench to keep that trench drained.

When you are cramped underneath the crawling space of a suspended floor you'd better keep digging to a minimum....a real pain in the axx (and back). I'd rather use a pump to suck the water out - if there are lower levels within a suitable range.