A pipeline burst around 2 pm at a plant devoted to the transformation and conservation of potatoes; 11 of the 13.5 m³ of the 32% hydrochloric acid (HCl) from a 30-m³ tank leaked, to a point of filling the retention basin.

An on-duty watchman noticed a strong irritating odour around 10 pm and sounded the alert. HCl was discovered shortly thereafter in a gutter running parallel to a suppressor room located near the tank. A 20-m safety perimeter, demarcated by ribbons and metal containers, was set up around the installations. The stormwater basin outlet was plugged by an impermeable ball. Personnel working in the site’s packaging zone were evacuated as a result of odours emanating from the stormwater drain pipes.

At 10:40 pm, two equipped individuals observed that the tank’s retention basin was not well sealed and moreover that HCl began spreading on the ground along the suppressor utility room, over the adjacent lawn and onto the pavement. The tank leak was brought under control around 11 pm by successfully closing the bottom valve. The polluted stormwater remained confined while awaiting a decision regarding its disposal; this decision was made the following afternoon, in consultation with the Classified Facilities inspectors.

Also on the next day, pollution measurements at 3 points, conducted with fire-fighter assistance, showed no anomalies. The wind blew in a way that favoured dispersion of the emitted acid vapours, and fortunately the plant was located in the middle of a field with no dwellings within 1 km of the installation. The pH of effluent contained in the basin could be verified, as was the absence of chlorine gas in both the pipes and packaging sector. The Classified Facilities Inspectorate and local gendarmerie also made visits to the site.

The packaging zone was fully ventilated before personnel were allowed to return to work inside. The operator decontaminated the site by recovering a maximum quantity of HCl on the ground for tank storage. The bituminous pavement and utility room were both cleaned. The stormwater collector pipes were rinsed for 4 hours with abundant quantities of water.

The pipe break was due to frost (-4°C at the time of the incident); moreover, the basin was not impermeable around the bottom slab / lower wall intersection. By undergoing maintenance, the tank was missing its antacid protective liner; HCl was thus spread over the pavement and adjoining land, before spilling into the collector connected to the stormwater drainage basin.

A piping system made with more efficient material was installed. The basin was restored to good working order. The alarm warning of an abnormal drop in HCl inside the tank was upgraded. The damaged stormwater pipeline was placed under camera supervision, and the internal emergency plan was revised.