Permeable paving - Advice

[matty brock]

Hello lads, got to give a quote on a 60m2 drive in permeable block. I have havent done one yet so I was looking for a bit of advice on the following-
Time scale compared to normal block
Depth of dig
Overall opinion

Thanks alot

[lutonlagerlout]

is the ground permeable?
will the water go to a suds system?
LLL ???

[matty brock]

Is that the 1st step ? havnt tried it yet.

What do you reckon ? dig a trial hole, fill with water and see how long it takes to drain ?

or just give him the quote and if he gets back in touch then do it and weigh it up after ?

Nice one LLL :;):

[Tony McC]

Depth to formation level will be around 400mm, giving a 300mm sub-base, 50mm of laying course and then 50mm blocks.

You need to know whether the ground is permeable, slightly permeable, or impermeable. If it's the latter, you will need an 'overflow' to the SW system, which would need to be factored into you cost. So, dig a hole to 400mm deep, fill with water and see if it disappears overnight (12 hours).

Construction time isn't that much different. Obviously, you have around twice as much muck to cart away and then three times as much sub-base, so for 60m² you might need to allow and extra day or day and a half.

Overall opinion is that the permeable block paving route for residential driveways is not always the best option. If you have a permeable sub-grade, then using a standard construction with a good soakaway fed from a linear channel is usually cheaper, faster and simpler to construct.

[matty brock]

Thank you Tony for the advice, I didnt suggest the permeable block, it was the customer. I will have a word and explain things to him, now I know a bit more about it.

The other problem that I can see with that depth of excavation on a domestic drive apart from the spoil removal cost is the fact that you will almost certainly expose or 'rip out' ha the services........

[seanandruby]

You have to dig with extreme caution. Don,t assume you are... " going to rip out services" because you will, if you don,t go slowly. you need to hand dig slit trenches across the drive, 300 deep as you go. It,s not just dangerous, it can take away your profit if you "rip" any out ???

[Dave_L]

I know a machine driver called "The Vicar"

Never known to miss a service!

[Mikey_C]

i got the hatrick when I did my drive, water, gas and electric.

[matty brock]

sean, I said you will almost certainly expose the services not almost certainly rip them out. The thing with them is they are not always level, dig a trench and expose it at say 300mm in one place, could be 200mm in another, going that depth just increases the chances of coming across them by alot like.

I have been doing domestic drives since I was 15 and have had 18 years on it now, we have a slow and steady machine driver and have only riped out 1 water main.....not bad eh ! ha

'Hatrick' haha in for a penny and all that

[mickg]

its always wise to locate both ends of any services by hand first before you start to excavate with a machine

you should never hit water at 300mm - 400mm deep unless its an older property and its still the old lead pipe

cable TV should of been 14 inches deep but seeing as the guys got £25 per house to connect the cable including digging from the road to the house most of them I come across are just under the turf, soil or flag, it means digging by hand to expose all the cable and to bury it after you have excavated the driveway to the correct depth

electric and gas should also be 14 - 18 inches deep and if the gas pipe or electric cable is not there is no charge to re connect

[matty brock]

Nearly every house in South Liverpool where I live is a 1930,s semi so the chances of finding the water when doing a 400mm dig a very high. Yeh those cable wires are a joke, they are usually just under the surface.