Screening a site for EIA using public datasets

EIA screening datasets do two jobs. They establish whether the site sits in a sensitive area as the Town and Country Planning (Environmental Impact Assessment) Regulations 2017 define that term, and they supply the evidence about the receiving environment that a screening request has to describe. The first of those changes the test completely. Inside a sensitive area, the floorspace and site area thresholds in column 2 of Schedule 2 do not apply, and any development of a listed description needs screening however small it is.

That is why a screening exercise starts with a map rather than a schedule of areas. Establish the designations first, then measure.

What the regulations mean by a sensitive area

Sensitive area is a defined term in the regulations, and it is narrower than the general idea of a constrained site. It picks out specific designations rather than any place that happens to be environmentally important.

The categories include land notified as a Site of Special Scientific Interest, land subject to a nature conservation order, National Parks, the Broads, World Heritage Sites, scheduled monuments and areas designated for their natural beauty, now known as National Landscapes. Read the definition in the regulations directly rather than working from a summary, including this one, because the terminology has been updated over time and the list is precise.

What is not in the definition matters as much. A conservation area is not a sensitive area for these purposes. Nor is a listed building, a registered park and garden, a Local Wildlife Site, ancient woodland, an Air Quality Management Area or a flood zone. Those are all planning constraints and several of them will drive the substance of any assessment, but they do not disapply the Schedule 2 thresholds.

So a scheme in a conservation area next to a listed building may sit comfortably below the thresholds and need no screening at all, while a much smaller scheme inside a National Landscape does.

Datasets that establish each category

Use the authoritative source for each designation, and record which one you used.

The national planning data platform is the right first stop because it publishes designation boundaries as consistent datasets with provenance, which is what you want to cite. The multi-agency mapping service is stronger for ecological layers and for seeing several designations against each other.

Habitat and species data needs care, because inventory layers describe habitat rather than designation. The distinction between the two is the subject of reading habitat inventories and classification data, and confusing an inventory polygon with a statutory designation is a common error in screening requests.

Take a dated screenshot or export of every layer you rely on. Datasets are updated in place and a screening opinion can be revisited months later.

Measuring the site against the Schedule 2 thresholds

Outside a sensitive area, the thresholds do the work. Column 1 of Schedule 2 describes the development types and column 2 sets the applicable thresholds and criteria.

For most residential and mixed-use schemes the relevant entry is urban development projects. The thresholds there are expressed in the alternative: more than one hectare of urban development that is not dwellinghouse development, or more than 150 dwellings, or an overall development area exceeding five hectares. Any one of those brings the scheme into screening.

Three measurement points cause most of the arguments.

What counts in the site area. The overall area of the development is not always the same as the red line application boundary, and including or excluding an access strip, a drainage field or a landscape buffer can move a scheme across five hectares.

How mixed schemes are treated. A development with both dwellings and commercial floorspace has to be tested against the relevant limbs, and the answer is not a proportional blend.

Whether the description matches. The Schedule 2 categories are descriptive, and a proposal can fall within more than one. Test it against each that might apply rather than picking the most convenient.

Put the measurement on a plan, with the areas annotated, and include it in the request. A screening opinion that rests on an unstated area measurement is a screening opinion someone can unpick.

Cumulative development and where to find it

Schedule 3 of the regulations sets out the selection criteria for screening, and cumulation with other existing or approved development is among them. Ignoring it is one of the more common weaknesses in a request.

Where to look:

1. The authority's own planning register, searched by area rather than by address, for approved and pending applications within a sensible radius.
2. The adopted local plan allocations covering land adjoining or near the site.
3. The brownfield land register and any strategic land availability assessment, which show sites the authority expects to come forward.
4. The neighbouring authority's register, where the site is close to a boundary.
5. The national infrastructure projects register, for anything consented or in examination that affects the same receptors.

Write the cumulative section as a short list of identified schemes with references, distances and status, followed by a judgement. An assertion that there are no cumulative effects, with nothing behind it, invites the authority to go and look for itself.

Building the screening request

The regulations set out what a request must contain: a plan sufficient to identify the land, a description of the development including its physical characteristics, and a description of the aspects of the environment likely to be affected.

A request that gets a clean answer contains rather more:

• The Schedule 1 or Schedule 2 category relied on, and why the development falls within it.
• The sensitive area analysis, designation by designation, with the dataset and the date checked for each.
• The area and quantum measurements, annotated on a plan.
• The constraints that are not sensitive areas but will shape any assessment, including flood risk, heritage assets, habitats and air quality.
• The cumulative development list.
• A reasoned conclusion against the Schedule 3 criteria.

The authority has three weeks to respond, or a longer period if agreed in writing. A thin request gets an extension request and a slower answer, so the extra pages pay for themselves.

Where flood risk or ecology are likely to feature in the assessment, the supporting work often starts before the opinion arrives. A Flood Risk Assessment and a Preliminary Ecological Appraisal have their own lead times, and ecology has survey seasons that do not move for anyone.

When the data is ambiguous

Boundaries are drawn at a scale, they are sometimes generalised, and they are occasionally wrong at the edges. Where your red line touches a designation boundary, do not resolve it by zooming in.

The practical approach is to state the ambiguity, set out both readings, and proceed on the more onerous one unless the authority agrees otherwise. Ask the relevant body for a view where the designation is theirs, because a written answer from the nature conservation body about whether a parcel is notified is worth more than any map.

Say in the request what you have assumed. A screening opinion obtained on an unstated assumption is fragile, and a negative opinion that later turns out to rest on a wrong designation reading is worse than no opinion at all.

After the opinion arrives

A negative opinion says environmental impact assessment is not required. Keep it with the application and referred to in the planning statement. A positive opinion moves you to scoping, where the regulations allow a request for a scoping opinion setting out what the environmental statement should cover.

An Environmental Statement must be prepared by competent experts, and that is a legal requirement under the 2017 Regulations rather than good practice. A drafted starting point can organise the structure and the policy context for an Environmental Impact Assessment, and it is a briefing document for those experts rather than a substitute for them.

This is general guidance, not legal advice. Check the current regulations and the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.