C-DRONE GUIDE · 25 AUGUST 2026
Drone and Industrial Tannery: ICPE Heading 2350, Chromium Effluent Basins and Prices
Graulhet, in the Tarn, or Millau, in the Aveyron : France still has a handful of historic hubs where tanneries and leather-dressing plants (mégisseries) settled from the 19th century onward, often on a riverbank that once served as a natural drain for rinse water. Chrome tanning, the dominant process for leather destined for leather goods and footwear, leaves an effluent loaded with chromium salts that cannot be treated or discharged without passing through dedicated basins ; the fulling, drying and finishing workshops, for their part, often sit in century-old buildings whose roof has not always kept pace with production. Here is what the drone documents at this kind of site — treatment basins, drying-shed roofs, hide stockpiles —, what it does not replace, and the prices.
Published on 25 August 2026, reviewed on 26 August 2026 — regulations in force as of August 2026.
Tanneries, leather-dressing plants: ICPE heading 2350 and classification thresholds
A tannery turning raw hides into leather, or a leather-dressing plant (mégisserie) alum-tanning finer skins (sheep, goat) for the gloving and fur trades, fall in France under the same regulatory family : ICPE heading 2350, which covers any operation for preparing hides and skins, excluding salting operations carried out as an annex to a slaughterhouse and dyeing, classified separately under heading 2351.
The applicable regime is set by the finished-leather production capacity, a notion defined under the European Industrial Emissions Directive (IED) rather than by the workshop's floor area. Below 100 kilograms a day, the facility is not classified ; between 100 kilograms and 5 tonnes a day, it falls under declaration, governed since the 2017 nomenclature reform by the generic order of 5 December 2016 that applies in the absence of a dedicated sector-specific order ; beyond 5 tonnes a day, it moves to authorisation, with an impact study and tighter requirements, notably on water discharge and volatile organic compound emissions from finishing operations (above an hourly flux of 2 kilograms, the limit value is 110 milligrams per cubic metre in total carbon). A threshold logic based on treatment capacity rather than stored volume, comparable to the one used for the industrial flour mill.
Chromium effluent treatment basins: what an overflight documents
Chrome tanning, the most widespread process for leather destined for leather goods, footwear and furniture, produces an effluent loaded with trivalent chromium salts, sulfides from the unhairing stage and dissolved organic matter — a pollutant load that most French facilities discharge only after passing through an in-house physicochemical and biological treatment plant, with one or more open-air basins (buffering, chromium precipitation, settling, aeration). A recent study by Liliana J. G. Silva and co-authors, published in 2025 in the journal Toxics, measured up to 560 micrograms of total chromium per litre in a Portuguese stream downstream of a tannery effluent treatment plant, well above expected quality thresholds (see the study on Google Scholar) — a reminder of what is at stake in keeping these basins running properly at all times.
The drone measures no chromium concentration nor any physicochemical water parameter ; it documents the visual and geometric condition of the structures, on the same principle detailed in our guide to drone inspection of a wastewater treatment plant : dike freeboard (remaining water height before overflow), visible silting, bank cracking or settling, foam or abnormal surface deposits, temperature gaps that betray an aeration fault. Drone photogrammetry has already proven its ability to track the geometry of wastewater treatment basin structures over time : a study by L. Wong and co-authors, published in 2020 in Remote Sensing, validated this method for monitoring the deformation of large lagoon covers, with centimetre-level precision reproducible from one flight to the next (see the study on Google Scholar). This reading always remains a monitoring and alert tool, complementing the operator's statutory discharge analyses, never a substitute for them.
Tanning workshop and drying-shed roofs: what an overflight checks
Many French tanneries and leather-dressing plants occupy century-old buildings, originally built on a riverbank for the process water supply : 19th-century industrial sheds, slatted drying lofts designed for natural ventilation, fulling and finishing workshops added over the decades. This architecture takes a harsh hygrometric beating : water vapour from unhairing and tanning, drying condensation, an atmosphere sometimes loaded with volatile organic compounds from finishing coatings. A photogrammetric flight produces an orthophoto and 3D model of the whole roof area — mechanical tile, fibre cement, steel decking depending on the extensions —, without stopping production or exposing a roofer to an old frame whose load-bearing capacity is not always documented. This service falls under our drone façade inspection and surveying and photogrammetry offers.
The reading is direct : a shifted or cracked tile, a gutter blocked by organic deposits, a corrosion spot on a vapour extraction duct, a damp stain revealing water ingress above a finished-leather stock. Repeated on an identical flight plan from one campaign to the next, this coverage becomes a comparable series, useful for prioritising a roof repair programme or documenting an insurance file on an old building.
Hide stockpiles, flight framework and prices
A tannery's intake yard stores raw salted hides awaiting processing — sometimes under a lean-to roof, sometimes in open bins in dry weather — whose volume follows the pace of slaughterhouse deliveries. A photogrammetric survey gives a useful order of magnitude for managing stock rotation, on the same principle as the seasonal stockpile measurement at a vegetable-processing plant — never substituting for the regulatory weighing that sets the production capacity and therefore the ICPE regime under heading 2350.
The mission runs half a day for a typical site, a full day for a multi-building site with separate treatment basins. It starts with a briefing with the QHSE manager : locating the basins and their dikes, areas where vapour from the tanning workshops can reduce visibility in the morning, equipment traffic between the intake yard and the workshops, a take-off point set clear. As with any mission on an industrial site, the prevention plan is settled before the flight ; up-to-date professional liability insurance held by the contractor is a non-negotiable prerequisite.
2026 prices (excl. VAT) : €400 to €800 for an orthophoto and photographic report of the treatment basins and roof at a typical site ; €900 to €1,800 for a full campaign combining basins, roof and intake-yard volume measurement ; €250 to €500 per visit for recurring basin monitoring (dike surveillance, silting) ; €300 to €600 for a standalone roof survey. A travel charge applies beyond a 30 to 50 km radius. Request a quote stating the number of basins, the roof area and the goal (regulatory file, repair programme or stock rotation tracking).
Frequently asked questions
Can a drone measure the chromium concentration in the effluent or the receiving watercourse?
No. The drone takes no samples and runs no physicochemical analysis ; only accredited laboratories and the operator's statutory self-monitoring measure a chromium concentration, sulfide level or chemical oxygen demand. The orthophoto and thermal pass document the visual and geometric condition of the basins — dikes, silting, foam — which can prompt closer verification, never substitute for it.
Do drone volume measurement or orthophotos replace the statutory monitoring that sets the ICPE regime under heading 2350?
No. The regime — not classified, declaration or authorisation — is set by the finished-leather production capacity as defined under the IED directive, a figure the operator itself keeps track of. The drone produces a complementary visual and volumetric inventory of hide stocks or basins, useful for internal management, but it never substitutes for that regulatory figure.
Can a drone fly over an active tanning workshop without steam disrupting the mission?
Water vapour released by unhairing, tanning and drying can reduce visibility and blur an orthophoto, especially on a cold morning. The mission is scheduled around midday or at a time when extraction units are idle, in coordination with the production manager ; the drone detects no chemical compound in the air and never replaces the fixed air-quality or VOC sensors required by the operating permit.