Zoning: separation distances, wind, river and flood
Every parcel has a published zone, every odour, dust or major-hazard works stands at least its separation distance from homes and downwind and downstream of them, no home stands in the functional floodplain, and no hazardous-substance store stands in the 1 % flood zone.
The Berezina in spring flood near Uhlata, Belarus (2023): water covers the whole floodplain, and the village stands on the higher ground beyond it.Berezina River near Uhlata village during spring flood (aerial view) · 2023-05-07 10:03:39 · Budgawl · CC BY-SA 4.0 · Commons ↗
At about 01:00 on 3 December 1984, more than 40 tonnes of methyl isocyanate leaked from a pesticide plant in Bhopal, India. More than 500,000 people were exposed; about 3,800 died at once, "mostly in the poor slum colony adjacent to the UCC plant", and estimates of deaths in the first few days run as high as 10,000 (Broughton, 2005). Distance from a works costs nothing while the land around it is empty, and is almost impossible to buy back once people live there.
The distances are published. EPA Victoria's 2024 guideline recommends 250 m between a tannery and the nearest home, 500 m for a large abattoir and 2,000 m for an oil refinery (EPA Victoria, publication 1949). The opposite fault is separating everything: UN-Habitat holds single-function blocks to under 10 % of any neighbourhood, because zoning every use apart breeds congestion, segregation and car dependency (UN-Habitat).
The shape of it
Record the wind for at least a year before siting anything: US EPA requires 1 year of site data for dispersion modelling.
List every trade by what it emits — odour, dust, noise, toxic or flammable stores — and give each its separation distance: 250 m for a tannery, 500–1,000 m for a sand-casting foundry, 1,000 m for service rendering, 2,000 m for a refinery (EPA Victoria, 2024).
Site every works so that nobody lives downwind, downstream or down-valley of it: homes upwind on the wind rose, the water intake upstream.
Zone inward: light works next to homes, heavy works at the far side of the industrial area, each holding 50 dB(A) by day at 50 m (VNG, 2024).
Keep homes out of the functional floodplain (3.3 % or greater annual chance) and hazardous works out of the 1 % flood zone (NPPF, 2026).
Mix every compatible use: at least 40 % of floor space for work in each neighbourhood, single-function blocks under 10 % (UN-Habitat).
Publish the map and decide every permit against it; whoever arrives second, works or homes, must prove the distance.
Let lawful earlier uses continue but not grow; the right ends after 2 years stopped (Victoria, clause 63).
A town zoned by wind, river and flood, in planFig 1
Masonry / brickWater
Homes and the mixed-use centre upwind and upstream, the water intake above everyone; the industrial zone downwind and downstream, light works nearest the homes and heavy works furthest. Separation rings from EPA Victoria (2024): tannery 250 m, abattoir 500 m, rendering 1,000 m, measured from the edge of each works. Along the river, Zone 3b (3.3 % a year or more) holds only parks, and Zone 3a (1 %) no homes without an exception test and no chemical store. Drawn to the scale bar.
Doing it, step by step
The summary above says what has to happen. This says how, with the numbers that decide whether it works.
1 · Record the wind for a year and draw the wind rose
Set a wind vane on an open mast, clear of buildings and trees, and log the direction at fixed hours every day for at least a year. One season misleads: winds that blow towards the town in winter can blow away from it in summer. US EPA's air-quality modelling guideline requires at least 1 year of site-specific weather data, or 5 years from a national weather station (40 CFR 51, Appendix W).
Tally the readings by compass point and draw them as a wind rose: one spoke per direction, its length the share of readings from that direction, with calms counted separately.
Read the ground too. Plumes follow valleys: EPA Victoria flags homes down a valley from a works as a site where the standard distance may not be enough, and the same for homes that the prevailing wind blows towards.
The anemometer and wind vane of the Met Office weather station at Charterhall, Scotland (2012), on an open mast well clear of buildings and trees.Charterhall Met Office Weather Station Anemometer ^ Wind Vane - geograph.org.uk - 2754881 · 2012-01-07 · James T M Towill · CC BY-SA 2.0 · Commons ↗
✓ Check: A wind rose from at least a year of readings is on the plan, and the industrial zone sits on the side the wind blows towards least often from the homes.
2 · List every trade by what it emits
Write down each works and its outputs before giving it a zone:
Odour: abattoirs, rendering, tanneries, fish processing, sewage works, composting.
Dust: quarries, cement and lime grinding, coal handling, sawmills.
Noise: forges, mills, sawmills, anything working at night.
Major-accident hazard: bulk stores of toxic, flammable or explosive chemicals, which can kill beyond the fence in one event.
A works can be in more than one group; it takes the largest distance of any of them (EPA Victoria).
✓ Check: Every works in the settlement, and every one applied for, is on the list with its outputs and its distance.
3 · Give each trade its separation distance
Recommended distances to the nearest home, from EPA Victoria's 2024 guideline:
Tannery over 250 t a year: 250 m.
Galvanising: 400 m.
Abattoir over 500 standard animal units a day, sawmill, quarry: 500 m.
Sand-casting foundry: 500 m below 500 kg a cycle, 1,000 m above.
Service rendering (knackery), inorganic fertiliser over 2,000 t a year: 1,000 m.
Oil refinery, open-cut coal mine: 2,000 m.
Sewage works: case by case, growing with the population served.
Measure from the edge of the activity — buildings, stockpiles, ponds — to the property boundary of the nearest home in a town, or to the house and its yard on rural lots of 4,000 m² or more. A shorter distance needs a risk assessment before any permit.
Major-accident sites get no fixed figure: the EU's Seveso III Directive (Article 13) requires "appropriate safety distances" from homes, public buildings, recreation areas and major transport routes, and sets no figure itself, so the distance comes from national rules for what the site stores.
Never let homes be built against the fence of a toxic-gas store, whatever the permit date: about 3,800 people died at once at Bhopal, mostly in the colony next to the plant.
✓ Check: Each listed works has its distance drawn as a ring on the plan, and no home lies inside any ring.
4 · Place the works downwind, downstream and inward
Put the industrial zone downwind of the homes on the wind rose, downstream of the water intake, and not up-valley of anyone. The intake and outfall rules are in city water and sewerage and the planning guide.
Zone inward, from the homes outward (VNG, 2024): light works on the edge facing the houses, medium works beyond, heavy works at the far side. The Dutch base rule gives each works a noise budget at 50 m from its boundary of 50 dB(A) from 07:00 to 19:00, 45 dB(A) to 23:00 and 40 dB(A) at night; works that need more go deeper into the zone.
✓ Check: On the plan, the heaviest works is the furthest from the homes, all works are downstream of the intake, and a walk on a day of prevailing wind finds no works smell at the nearest house.
5 · Keep homes and hazardous works off the floodplain
Map the flood zones from flood marks and river records (England's NPPF, Annex F, September 2026):
Zone 1: less than 0.1 % chance of flooding a year — build here first.
Zone 2:0.1–1 % from rivers.
Zone 3a:1 % or more from rivers, 0.5 % or more from the sea.
Zone 3b, functional floodplain:3.3 % or more, or land designed to flood.
Homes are refused in Zone 3b and need an exception test in 3a. Installations that need hazardous-substances consent are refused in Zones 3a and 3b, and shops, offices and general industry are refused in 3b. Floors go above the design flood with freeboard, as in choosing the site.
The Cuckmere valley in flood in November 2023, seen from Litlington, Sussex: the river has spread across its functional floodplain, which is kept free of buildings.Cuckmere River floods november 2023 @ Litlington White Horse 01 · 2023-11-14 09:58:34 · Rémih · CC BY-SA 4.0 · Commons ↗
A flooded chemical store spreads its contents into every home and well the water reaches.
✓ Check: The zoning map shows the flood zones, no dwelling or works stands in Zone 3b, and no hazardous-substance store stands in Zone 3a or 3b.
6 · Mix every compatible use
Separate only what emits; mix the rest. VNG's rule is mixing where it can be done, separation where it must. UN-Habitat's neighbourhood targets:
At least 40 % of floor space in economic use in any neighbourhood.
Single-function blocks under 10 % of any neighbourhood.
Shops, offices, schools, clinics and quiet workshops belong among the homes; only the listed works in entry 3 go to the industrial zone.
✓ Check: Every neighbourhood has shops and work within it, and no block outside the industrial zone is reserved for one use alone.
7 · Publish the map and decide every permit against it
Give every parcel in the land register one zone, and publish the map and its rules where anyone can read them. Change a zone only by a published amendment.
Decide each permit by measurement: compare the measured distance to the nearest home with the recommended one. Met: the distance test passes. Not met: the applicant brings a risk assessment, or the permit is refused. A change of process, or moving an activity within the site, reopens the test (EPA Victoria).
The agent of change pays. Whoever arrives second — a new works near homes, or new homes near a works — must show the decision maker that the distance is met or that the risk has been minimised (EPA Victoria).
✓ Check: Every permit on file records the measured distance, the recommended distance and the decision, and no home permit inside a buffer was granted without an assessment.
8 · Let lawful earlier uses continue, but not grow
A use that was lawful before the zone was drawn may continue; Victoria's planning scheme also accepts proof of 15 years of continuous use (clause 63).
No new buildings or works for it without a permit.
No change of activity that makes the nuisance worse.
The right ends if the use stops for 2 years in a row, or for 2 years in total within any 3; a seasonal use ends after 2 seasons missed.
When it ends, the parcel takes its zone.
✓ Check: Every non-conforming use is on a register with its start date, its permitted extent and the date it was last seen operating.
The better path
What the record shows was done at this step, what to do instead at this tier, and the evidence. All of them: the better path.
Do not repeat
Zoning every use apart
What was done
Homes, shops, offices and workshops each given separate zones, whether or not they emit anything.
Do instead
Separate only works that emit odour, dust, noise or major-accident risk; mix every compatible use.
Evidence
UN-Habitat's neighbourhood principles: at least 40 % of floor space in economic use, single-function blocks under 10 % of any neighbourhood; single-function neighbourhoods are named as a source of congestion, segregation and car dependency.
Homes allowed up to the fence of a hazardous plant after it was built: Bhopal, 1984.
A buffer drawn on the map but not enforced on newcomers, so housing fills it and the works is then blamed for the nuisance.
Wind direction taken from one season, so the works is sited upwind of the town for half the year.
Chemical stores on the floodplain, so the first large flood carries their contents into homes and wells.
Single-function zoning everywhere, so homes, shops and work end up kilometres apart for no hazard reason.
A non-conforming works allowed to expand step by step until it is a new works without ever needing a permit.
How you know it worked
VerificationThe published map gives every parcel a zone; every listed works measures at least its separation distance to the nearest home, lies downwind of homes on the year's wind rose and downstream of the water intake; no dwelling stands in the functional floodplain, and no hazardous-substance store in the 1 % flood zone.