Project Peak Valley Risk

Why this project exists

Public discussion of this pipeline proposal so far has been polarised. Concerns raised by residents have been labelled "misinformation". Reassurances from developers and elected representatives have leaned heavily on analogies to dissimilar systems — US CO₂ pipelines through sparsely populated rural plains, Norwegian offshore CCS — that don't apply to a 195 km route through karst, salt subsidence, flood-prone valleys, and populated terrain.

The honest answer is that no one yet has the validated science to assess this specific route. The UK Health and Safety Executive, the Department for Energy Security and Net Zero, and DNV are currently running Project Skylark — a three-year joint industry project that is still developing:

• Validated CO₂ dispersion models for varied terrain
• Emergency response best practices
• Safety guidelines for pipeline routing, risk assessment, and venting

That work will not finish in time for the planning decision. Project Peak Valley Risk fills the interim gap with the best publicly defensible analysis we can build right now.

What the project does

1. Give residents a secondary source of scientific quantification that is grounded in research methods.
2. Map the route accurately. Pipeline corridor (DEF2B project boundary, September 2026) and distance bands — all derived from publicly published developer GIS data and rendered openly.
3. Quantify population exposure. 2021 Census populations redistributed to UK Centre for Ecology & Hydrology 25 m built-up land cover (a dasymetric method), then summed within distance bands from the edge of the published project boundary.
4. Model CO₂ leak dispersion using terrain-aware heavy-gas dispersion approaches, accounting for the gravity-driven flow of dense-phase CO₂ down valleys and into low-lying ground.
5. Publish everything. Inputs, code, intermediate datasets, and conclusions — all open to challenge.

Technical methodology

• Source-term modelling in OpenFOAM. Computational fluid dynamics (CFD) simulation of the rapid depressurisation of a 24-inch DN600 dense-phase CO₂ pipeline rupture at the project's stated operating pressure (~150 bar, ~10°C), capturing the supersonic jet, Joule-Thomson cooling to −78°C, and the dry-ice/vapour two-phase plume that forms in the first seconds after release.
• Atmospheric boundary conditions from WRF. Weather Research and Forecasting model (WRF-ARW) at 1–3 km nesting over the Peak District and Cheshire Plain, tuned to representative night-time inversion, daytime convective, and high-wind storm scenarios — the meteorology that actually drives heavy-gas dispersion behaviour.
• Digital twin of the Peak District & Cheshire valleys. 2 m LIDAR DTM (DEFRA Composite) for the corridor, OS Open Greenspace and OS Open Roads for surface roughness, OS Open Buildings and OS Open UPRN for receptor locations — assembled into a meshed terrain that drives both the CFD domain boundary and the receptor exposure analysis.
• Heavy-gas dispersion downwind. Coupling of CFD source-term output to PHAST-equivalent dense-gas dispersion and validated against the COSHER and Spadeadam large-scale CO₂ release datasets (the same dataset DNV's Project Skylark is currently extending). Dose × time exposure thresholds applied per the HSE's CD/SLOD framework for CO₂.
• Receptor exposure quantification. Every UPRN within the modelled plume footprint is tagged with peak concentration, time-integrated dose, and time-to-incapacitation. Aggregated to civil parish, BUA, LSOA and LAD for community-level reporting.
• Open scripts & data. All inputs, mesh definitions, OpenFOAM cases, WRF namelists, and post-processing notebooks published openly. Parameters chosen to bracket plausible ranges rather than single point estimates, so independent reviewers can probe the assumptions.

Interactive distance map

The map below shows the pipeline corridor (the developer's updated ~100 m DEF2B project boundary, September 2026), and contoured distance bands from the edge of that corridor across Cheshire, Derbyshire and the Wirral. Hover anywhere to see the distance to the corridor edge. Use the menu (bottom-left) to inspect population exposure for specific places — including Macclesfield, Bollington, Whaley Bridge, Buxton, Wirral as a borough, and Cheshire / Derbyshire as wholes.

Headline findings (current)

Updated 22 September 2026: all figures below are now calculated against the developer's updated DEF2B project boundary (published September 2026, a corridor of roughly 100 m), which replaces the 300 m phase 1 scoping boundary used in our earlier analysis. Distances are measured from the edge of that boundary. The narrower corridor and the developer's route changes (e.g. south of Middlewich, Holmes Chapel and Huxley) reduce the headline counts relative to our earlier figures.

Cumulative population within these distances of the edge of the DEF2B project boundary (September 2026, ~100 m corridor). Population derived from the 2021 Census, redistributed to OS Open UPRN address points within each LSOA (so every house, isolated farm, and small village is captured directly):

By area

Population near the pipeline (all places with any population within 5 km)

UPRN-derived dasymetric population, civil parish (with BUA fallback for unparished urban areas). Cumulative figures. Click any column to sort. 20 rows per page.

Built-up density within 1 km of pipeline

People per km² of built-up area (residential building footprints + 25 m buffer) inside the 1 km corridor, by parish/BUA. This shows the density of the actual lived-in land exposed, not the whole rural parish area.

Overall corridor (≤ 1 km from corridor edge): 86,005 people across the full 415.3 km² 1 km buffer — 207 people/km² including non-built land; concentrated onto 37.02 km² of built-up land — 2,323 people/km² of built-up land.

What we are working on

• Heavy-gas dispersion modelling — terrain-aware simulations of plausible release scenarios at multiple points along the route, including night-time releases under temperature inversion.
• Geological hazard mapping — overlaying the route with British Geological Survey GeoSure data for karst dissolution, salt subsidence, and ground movement.
• Flood vulnerability — Environment Agency flood zones, river crossings, and the historical flood frequency record for the corridor (2019, 2020, 2021, 2023, 2024, 2025).
• Emergency response analysis — what would actually happen if a release occurred at a populated point in the corridor, given current UK fire and ambulance service capability.

Data sources

• Pipeline project boundary (DEF2B, September 2026) and phase 1 scoping boundary — developer ArcGIS Online publication
• 2021 Census TS001 — Office for National Statistics, via NOMIS
• LSOA 2021 boundaries — ONS Open Geography Portal
• UKCEH Land Cover Map 2023, 25 m — UK Centre for Ecology & Hydrology
• British Geological Survey GeoSure — BGS Open Data
• Project Skylark — DNV / HSE Science Division joint industry project
• PHMSA pipeline incident database — US Department of Transportation