At a petrochemical site supplied by a neighbouring refinery, a light marine diesel spill was observed around 2 am on a storage tank; 30 m³ of fuel wound up in the retention basin. The site’s fire-fighters covered the basin with foam in order to limit VOC releases; the product was then pumped for incineration. The basin was cleaned using high-pressure water, which was subsequently channelled to the plant’s oil separation basin.
According to the plant operator, the tank’s high level alarm was tripped in the petrochemical facility control room, but technicians on duty did not notify their counterparts at the refinery in time (communication breakdown). Consequently, the transfer pump was only turned off once the spill was detected at the petrochemical site. Moreover, the tank’s high level alarm would at times activate in the petrochemical control room when transferring diesel into this tank even if the maximum filling level had not yet been reached. The refinery operator installed an automatic diesel transfer shutoff triggered once the tank reached its normal filling volume (via a flow meter), and the petrochemical operator reset its high level alarm threshold to sound only upon exceeding the normal filling height. To reduce communication errors between the 2 sites, the transfer procedure was revised so that technicians supervising the transfers at each facility exchanged names at the start of each operation. Technicians were also made more aware of the role of alarms.