C-DRONE GUIDE · 10 AUGUST 2026
Drone Monitoring of Ammonium Nitrate Fertiliser Storage: ICPE Heading 4702 and Price
A stock of ammonium nitrate fertiliser is not a stock like any other: past a certain tonnage, regulations require strict compartmentalisation into storage cells, precisely to limit the consequences of a localised hot spot degenerating into self-sustaining decomposition. The Toulouse disaster of 2001 and the Beirut explosion of 2020 have left a lasting mark on the profession, even though their respective causes — an accidental mix of incompatible products, and prolonged, non-compliant storage — differ from the routine monitoring described here. In France, these storage sites fall under heading 4702 of the classified-installations (ICPE) nomenclature, with a regime that scales from simple declaration up to Seveso authorisation depending on the product's quantity and composition. A regular aerial thermal survey of the pile or storage cells, combined with a visual check of compartmentalisation and building structure, complements the operator's routine monitoring without exposing anyone to direct contact with the product. Here is what this regulatory framework covers, what a drone flight can verify, and what it costs in 2026.
Published on 10 August 2026, reviewed on 10 August 2026 — regulations in force as of August 2026.
ICPE heading 4702: thresholds that scale up to Seveso authorisation
Heading 4702 of the French classified-installations nomenclature covers solid simple and compound fertilisers based on ammonium nitrate that comply with EU regulation No 2003/2003 on fertilisers or the equivalent French standard NF U 42-001-1. It splits into several sub-categories depending on nitrogen content and how prone the product is to self-sustaining decomposition: a moderate-grade compound fertiliser does not trigger the same regime as a high-nitrogen straight ammonium nitrate. Below a first tonnage threshold, the site falls under simple declaration, governed by the order of 6 July 2006; above it, the site moves to the authorisation regime, governed by the order of 13 April 2010 as amended by the order of 2 September 2016, which requires a hazard study, compartmentalisation rules and emergency resources sized to the site.
For the largest sites, the Seveso directive adds a further layer on top of this national framework: past a lower and then an upper stored-tonnage threshold, the operator becomes a lower-tier or upper-tier Seveso establishment, with stricter obligations to inform the authorities and, for upper-tier sites, nearby residents. In practice, this scale concerns agricultural cooperatives, fertiliser trading firms and logistics platforms storing bulk or big-bag volumes large enough to cross the first regulatory threshold — a very different case from a grain silo, which falls under an entirely different heading (2160) and a different type of hazard: explosive organic dust rather than the chemical decomposition of an oxidiser.
A local hot spot: what drives the risk
Ammonium nitrate is a stable oxidiser under normal storage conditions, but its thermal decomposition speeds up with temperature and can become self-sustaining past a threshold specific to each formulation — what industry calls the self-accelerating decomposition temperature (SADT). A study by Yang, Chen, Wang, Yuan, Niu, Zhang, Liao and Zhang published in 2017 in the Journal of Hazardous Materials compared the thermal behaviour of powdered ammonium nitrate under different atmospheres and gas flow rates: the authors show that the self-accelerating decomposition temperature drops markedly in the presence of air compared with an inert atmosphere, and that the surrounding gas flow rate also affects the product's stability (see the study on Google Scholar). Insufficient ventilation, prolonged contact with an external hot spot — a faulty electrical duct, sunlight concentrated on a dark roof — or an accidental mix with a combustible or incompatible material can therefore trigger this mechanism locally, well before it becomes visible at the surface of the pile.
Hence the value of monitoring that goes beyond a visual check of bag or big-bag condition: catching a surface temperature drift, even a modest one, before it settles in and grows. This early-detection logic mirrors what we describe for other materials prone to self-heating, as detailed in our guide on thermal monitoring of a waste-sorting centre, where the principle — spotting an isolated hot spot early to act before it worsens — is the same, even though the nature of the hazard differs.
What a drone flight adds: thermography, compartmentalisation, structure
A thermal survey of the storage area, flown early in the morning when the gap with ambient temperature is clearest, sweeps across the surface of the pile or stacked big-bags and reveals any localised deviation from the batch's average temperature. The method rests on a principle already validated on other piled materials prone to self-heating: a study by He, Yang, Luo and Guan published in 2020 in Scientific Reports used drone thermal infrared remote sensing to precisely delineate the underground combustion zones of a Chinese coal mine, a method the authors consider transposable to other cases of surface thermal-anomaly detection (see the study on Google Scholar). Applied to fertiliser storage, the same aerial sweep can quickly map a whole site, storage cell by storage cell, at a frequency no walking round can match.
Beyond thermography, the flight documents what the regulations require on compartmentalisation: the height and volume of each storage cell, the width of circulation aisles between cells — sized to allow emergency services in and limit a hot spot spreading from one cell to the next — and compliance with separation distances from incompatible materials stored on the same site. A wide aerial image objectively captures in minutes what a ground check struggles to reconstruct as a whole. The flight finally covers the building's structure — roof, cladding, condition of smoke vents —, a complement detailed in our industrial silo and building drone inspection guide, along with the accessibility of fire hydrants and access routes for emergency vehicles, seen from above.
Flight framework and 2026 pricing
On the aviation side, these sites — cooperatives, trading firms, logistics platforms — mostly sit in rural areas or on the edge of a built-up area: the flight generally falls under the open category, after checking the Géoportail restricted-zone map. Unlike a grain silo, ammonium nitrate fertiliser storage is not subject to ATEX zoning in the combustible-dust sense; the flight is nonetheless always organised in coordination with the site's HSE manager: traffic plan, site-specific rules for Seveso establishments where applicable, and authorised take-off and landing points. As for any mission on an industrial site, all-risk drone insurance and, for operators flying several missions a year, a LUC certificate make it easier to fold the provider into the site's prevention plan.
Ranges observed in 2026 (excl. VAT), depending on site area and chosen frequency:
| Service | Observed price (excl. VAT) |
|---|---|
| One-off thermal survey (site up to 10 storage cells, report with located hot spots) | €400 to €900 |
| Compartmentalisation and structure check (photos + report) | €250 to €500 on top of the thermal survey |
| Seasonal monitoring subscription (several passes) | lower per-pass rate, quoted |
| Multi-site campaign (several depots of the same group) | 10 to 20% discount per site |
Set against the cost of an incident or a resulting shutdown, this monitoring remains a modest expense given what is at stake. Request a quote stating the number of storage cells, the area covered and the desired monitoring frequency.
Does the drone replace the hazard study required by the order of 13 April 2010? No: it feeds into the operator's routine monitoring; it replaces neither the hazard study nor periodic regulatory inspections.
Does the pilot need to enter the Seveso site? They must be briefed and escorted under the site's procedures, but the flight itself is carried out without any contact with the stored product.
Can thermography detect a deep hot spot at the core of a storage cell? No: as with any exterior survey, only the surface is read; a deep-seated hot spot stays out of reach and remains the job of existing internal monitoring systems.
Does this service also apply to small agricultural depots? The principle stays relevant as soon as the volume justifies a professional service; below the first declaration threshold, a standard visual check is often still enough.