Path Drainage Ditches / Pipe Culverts

Date published: 17 February, 2022

For recent changes to this guidance, please see the bottom of the page.

Aim

Effective drainage is essential for paths to be comfortable to use and to avoid erosion and deterioration. Drainage capacity should allow for severe weather flows. The open drainage ditches will generally run beside and parallel to the path to intercept, channel and divert water, and culverts cross below paths to take water from one side to the other.

Eligibility

Any land is eligible.

Drainage ditches and piped culverts are only eligible if selected in conjunction with the IPA “new path” or “upgraded path” capital items.

Requirements

Open ditch – V or U-shaped section

Excavate ditch by machine.
A verge of no less than 300mm between the path edge and the side ditching.
200mm – 300mm deep channel, with a smooth base.
300mm – 450mm wide at top.
Sides angled slightly for stability.
Spoil and turf should be landscaped evenly and neatly on the lower side of ditch or along the path verges.

Piped culverts:

Excavate trench by machine, to a sufficient depth and length to fully intercept drainage water and for construction of the path with verges over the top of the pipe.
Lay compacted sub-base material in bottom of trench.
Place twin-wall plastic pipe on sub-base, with a run top to bottom.
Cover pipe fully and back fill trench with sub-base material.
Build solid thick natural stone headwalls, with a splash plate around both pipe ends, and landscape using spoil and turf.
You must keep a photographic record of the pipe-culvert installation showing works below ground level.

Payment

You can claim:

Open ditch: £1.88 per metre.
Piped culverts: 300mm diameter pipe: £143 each.
Piped culverts: 450mm diameter pipe: £395 each.

Additionally:

All drainage features must allow water to flow and fall easily along its length, from top to bottom, and not channel water back onto the path.

Inspections

The Inspector will check:

The location and extent of the work as is detailed in the contract schedule of works and contract map
That the capital item requirements have been met as detailed above
That photographic evidence has been provided as detailed above