Engineering operations: when earthworks need permission

Earthworks can need planning permission even when nothing is built. Section 55 of the Town and Country Planning Act 1990 defines development to include the carrying out of "engineering operations" in, on, over or under land, and that phrase catches regrading a paddock, cutting a new farm track, forming a flood bund or digging an attenuation basin. Engineering operations planning questions usually arrive late, after a contractor has already quoted for the muck shift, so the useful thing to know is which of these works are permitted development on a farm, which need a full application, and what evidence a council asks for either way.

What an engineering operation covers

There is no statutory list. The courts have read the words broadly, so the test in practice is whether the works involve the skills of an engineer, change the physical character of the land, and are more than de minimis. Excavation, filling, levelling, terracing, forming embankments, laying a hard surface, culverting a ditch and building a retaining structure all fall inside it.

Two distinctions matter. Engineering operations are operational development, so time runs from substantial completion rather than from a change in activity. And they are separate from any change of use the works enable. Spreading hardcore to park lorries on a field is an engineering operation and a material change of use, and a council can take issue with both.

But scale alone does not decide it. A 300 mm lift across two hectares moves a lot of soil and alters drainage. Shifting the same volume into a single bund beside a watercourse raises different questions again.

The agricultural exemptions and where they stop

Using land for agriculture is not development under section 55(2)(e), but that exemption covers use, not operations. The rights that matter are in Part 6 of Schedule 2 to the Town and Country Planning (General Permitted Development) (England) Order 2015.

Class A applies to agricultural units of five hectares or more and permits excavations and engineering operations reasonably necessary for the purposes of agriculture within that unit. Class B applies to units of at least 0.4 hectares but under five, with narrower rights that centre on existing buildings, private ways, hard surfaces, waste deposit and water supply works.

Both classes carry conditions that catch people out:

• The operation must be reasonably necessary for agriculture on that holding, not for a diversified or equestrian use.
• Prior notification to the local planning authority is required for the formation or alteration of a private way, and for excavation or waste deposit where the relevant area exceeds 0.5 hectares.
• Works close to the metalled part of a trunk or classified road, and works on land in or next to a scheduled monument, are excluded.
• Part 6 rights can be withdrawn by an Article 4 direction, which some National Park authorities have made.

Equestrian use is the most common trap. Grazing horses is agriculture, keeping or exercising them is not, so a menage, a horse walker or a track formed for riding sits outside Part 6 entirely.

Regrading, bunds and attenuation

Regrading for drainage or for a better field shape is usually permitted on a Class A holding if the agricultural necessity is real and the volumes are proportionate. The argument tends to fail where imported material appears. Once soil or inert fill arrives from off site, the work starts to look like waste deposit rather than husbandry, and the local planning authority will ask where the material came from and why that volume was needed.

Attenuation basins and flood bunds built as part of a development scheme are different again. They are normally covered by the permission for the scheme and conditioned through the drainage details. Where a landowner builds one on its own, in Flood Zone 2 or 3 or on a site of one hectare or more, the application will need a Flood Risk Assessment that addresses off-site effects, because raising ground in a floodplain displaces water onto someone else.

Soil handling deserves a mention. Where best and most versatile land is involved, councils increasingly ask for an Agricultural Land Classification survey and a soil management method statement before they will accept that regrading is benign.

Access tracks and hardstanding

A new or altered private way on an agricultural unit needs prior notification under Part 6, and the authority then decides whether it wants to approve the siting and means of construction. That is a short determination, not a full application, but it is a real consent step and skipping it leaves the track unlawful.

Outside Part 6, a track or hardstanding is a straightforward engineering operation needing permission. The issues are surface water, because a sealed surface moves run-off somewhere, visual effect in open countryside, and whether the track will serve a use the council has not approved. Width, surfacing material, camber and the treatment of the junction with the public highway all get scrutinised, and the highway authority will look at visibility splays and at any need for a section 278 agreement under the Highways Act 1980.

For a dwelling, hard surfacing within the curtilage sits under Part 1 Class F, with the condition that a front surface over five square metres must be porous or drain to a porous area within the curtilage.

Where waste deposit meets environmental permitting

Section 55(3)(b) treats the deposit of refuse or waste material as a material change of use where the area is extended or the height exceeds that of adjoining land, even on a site already used for deposit. So importing fill is capable of needing permission twice over, as an operation and as a use.

Planning consent is not the whole picture. Depositing waste, including inert soil and stone, engages the Environmental Permitting (England and Wales) Regulations 2016. Many land-raising and construction uses run under a registered exemption rather than a bespoke permit, and the Environment Agency publishes which exemptions cover the use of waste in construction and which conditions attach. Registering an exemption does not grant planning permission, and holding planning permission does not remove the permitting duty. Where contamination is suspected in imported material, the chemical testing regime matters as much as the volumes.

Retrospective positions and the certificate route

Plenty of earthworks are only noticed once they are finished. Three routes exist.

1. Apply under section 73A for permission for development already carried out, which is a normal application judged on its merits.
2. Apply for a certificate of lawfulness of existing use or development under section 191, which confirms the works are immune from enforcement because of the passage of time.
3. Do nothing and wait, which leaves the land unsaleable until a solicitor asks the question.

Time limits have moved. The Levelling-up and Regeneration Act 2023 extended the immunity period for operational development in England from four years to ten years, applying to breaches occurring on or after 25 April 2024. Earlier breaches may still rely on the four-year period. Work out which period applies before advising anyone, because the two regimes now run side by side.

A certificate is the only formal way to confirm that works are lawful. An email from a planning officer saying the work "looks like permitted development" is worth very little when a buyer's solicitor reads it.

The evidence a council will want

For a Part 6 prior notification, keep it short and factual: a site plan with the holding boundary, the area of the unit in hectares, cross sections of the proposed levels, and a sentence on why the work is reasonably necessary for the agricultural operation.

For a full application, the bundle is larger. A Planning Statement setting the works against development plan policy, existing and proposed levels with cut and fill volumes, a drainage note, a landscape and visual appraisal where embankments will be visible, and ecology information if hedges, ditches or grassland will be disturbed. Where the operation supports a different activity on the land, deal with that honestly, because a council that spots an undeclared use will treat the whole submission as unreliable, and the point at which more of the same becomes a material change of use is argued more often than people expect.

Illustrative example: a farmer lowers a 1.5 hectare headland by 400 mm to improve drainage, using the spoil to form a 2 m bund along a field boundary. On a 60 hectare holding, with no imported material and the area above 0.5 hectares, that is Class A work needing prior notification of the excavation. Add 3,000 tonnes of imported subsoil from a nearby housing site and the position changes to waste deposit, with a permitting question attached.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. If you want to see which documents an earthworks application is likely to need, enter the site postcode on PlanScope.