Chemical manufacturers store and process toxic industrial chemicals in quantities that make a release a community event, not just a plant event. The plan has to answer where a cloud will go, who is in its path, and what happens if the wind changes.
The hazards
- Chlorine. CDC notes that when liquid chlorine is released it quickly turns into a gas that stays close to the ground and spreads quickly. Because it is heavier than air, it sinks to lower areas. (CDC)
- Ammonia. Ammonia vapor is lighter than air, but the CSB notes that an anhydrous ammonia release can absorb moisture and form a dense white cloud, and that 300 ppm is considered immediately dangerous to life and health. (CSB) In an April 2019 release in Lake County, Illinois, CDC reported a large, low-lying plume that lingered around nearby homes in cool, humid air and calm winds, with a shelter-in-place order covering a one-mile radius. (CDC MMWR)
- Other toxic gases and fires that create both a toxic plume and a smoke plume.
Why terrain- and structure-aware wind helps
A cloud that stays low is steered by buildings, tank rows, berms and the shape of the land. The LR-x® 3D wind field model accounts for terrain and structures and can reveal eddy currents that concentrate a plume around buildings, which helps pick safer ingress and egress routes and muster points. How the 3D wind field model works.
What LR-x® adds to the emergency plan
- Chlorine and H2S release modeling. LR-x® models chlorine and hydrogen sulfide releases, with color-coded ALOHA threat zones on the map. ALOHA (NOAA/EPA) models both neutrally buoyant and heavy gas dispersion. (NOAA)
- Any chemical ALOHA can model. ALOHA’s chemical library covers over 500 pure chemicals and some common chemical solutions, a subset of NOAA’s CAMEO Chemicals database. (NOAA ALOHA Technical Documentation)
- Three additional forecasts, about every 2 minutes, so shelter and evacuation calls can get ahead of a wind shift.
- A fixed configuration that runs continuously (24/7) and connects to atmospheric sensors placed around the plant.
- Tier II data on neighboring facilities and what they report storing, with contacts.
- KML export. LR-x® exports the real-time plume model, the real-time 3D wind field model and the three forecast models as KML files you can use in ArcGIS, with your plot plan and community layers.
- What-if scenarios for drills and LEPC exercises.
Who uses it
Plant emergency response teams and process safety staff, the local fire department and hazmat team, and the LEPC. Under EPCRA, facilities submit their Tier II inventories each year to their State Emergency Response Commission, LEPC and local fire department. (EPA)
See also: refineries, industrial facilities and all facility types.
Incidents described on this page are cited from public reports. They are examples of the hazards these sites face, not LR-x® deployments.