Soakaway installation in Dorset

Dorset ground that drains

The sands and gravels of the Poole Basin, running out towards Wimborne, Ferndown and Wareham, often give fast percolation results. The chalk of the Dorset Downs and Cranborne Chase usually drains well too. On those sites a soakaway returns runoff to the ground without an outfall, which is the route the 2025 national SuDS standards want tried before a sewer connection.

The clay vales in the north of the county are a different case, and so are plots close to the harbours where groundwater sits high. A percolation test on your plot, read alongside the groundwater level, tells your engineer which side of the line you're on.

What decides the price

A soakaway quote comes down to a handful of things, and the ground is the first of them. A fast result on Poole sand needs a smaller crate structure than the same roof on slower ground.

• The measured infiltration rate, which sets how much storage is needed
• The area drained, so an extension roof is a different job from a new house and drive
• Access for your groundworker's machine, which affects how the pit is dug and how long the visit takes
• The loading class: a soakaway under a drive needs stronger crates than one under a lawn
• Silt management ahead of the soakaway, as the design specifies

Driveways, extensions and new homes

Much of the soakaway work around Poole, Bournemouth and Christchurch comes from extensions, new drives and infill homes, where a new roof or hard surface has to drain somewhere. Approved Document H points to infiltration first where the ground allows, and that usually means a crate soakaway set back from the house.

On larger Dorset schemes the soakaway is often one part of a wider strategy, with some areas infiltrating and others draining through attenuation. We build to whichever parts of the design are ours, and coordinate with your groundworker on the order of work.

How we build it

The engineer's design, and the percolation figures it rests on, are what we build to. Digging the pit is your groundworker's work and the backfill is your contractor's; we don't dig. After checking the formation we lay the permeable geotextile, build the crates inside it to the designed volume, connect the inlet and catchpit, and close the wrap so soil fines stay out of the storage.

Inspection records and a handover pack come to you for building control. Supply-and-install and install-only are both on offer, with crews travelling from our Tamworth base.