Culvert - How should i design it?

[benperry]

Hello,

I need some help in designing a culvert over a ditch to give access from the road to my building plot. Unmade ground on both sides of the ditch at present but will be putting down a 4m wide driveway over it and running services under the drive. The drive to be used just for car & foot traffic in the long term but will need take the weight of fully laden delivery lorries, concrete mixers etc over the next couple of months and before the drive is laid.

The ditch is the standard \_/ shape. The span at the top is about 2000mm and 500mm at the bottom. The bottom of the ditch is about 1500mm below the finished level.

Looking at the neighbouring driveways, they all seem to use a 300mm pipe so I was looking at the same diameter using a twinwall pipe.

My question is what materials should I bed the pipe on, surround it with and what backfill material should i use to bring it up to the desired level, ready for the sub-base?

And what about retaining sides? Will a 45 degree slope be fine or should I be using concrete bags or a retaining wall?

All advice welcome!!!

Thanks.

[Tony McC]

The agency responsible for your local watercourses (usually the water board) will have a selection of standard designs that they have pre-approved for culverting and headwalls.

[benperry]

Thanks Tony.

I've already tried the local authority and the environment agency and neither were much help

I'll try the water co and see what they can come up with...

[remus]

It may be you have a drainage board that will be responsible for you ditch.
I am on a farm the ditches on the marsh come under the Lower Medway Drainage Board. Once the water gets to the river wall then The Environment Agency take over.
It took me a long time and visits from both before I found out who to blame for the a sluice not working.
kevin