The Du Pont spill attracted widespread publicity in Northern Ireland, and did not reflect well on the firm's emergency procedures.
According to Mr Hanley's account, the spill occurred from a neoprene unit at the Maydown site. An alarm first signalled a fault in the early hours of 6 October, but was misinterpreted by an employee as having been caused by fumes from a vat containing chlorobutadiene which had just been cleaned. At 7.00, it was discovered that a pump had failed and was allowing the chemical to escape into the site's effluent stream and on into Lough Foyle. A second alarm failed to go off because it had been blocked by the chemical.
It was not until the afternoon of 8 October that Du Pont realised that 2-3 tonnes of chlorobutadiene may have been spilled. And the company only informed the Department of the Environment of the incident just before lunchtime the following day.
An immediate official warning was issued against consumption of fish and shellfish from Lough Foyle. Sampling of the environment was also instituted.
Mr Hanley's statement was not precise about what the sampling programme found. There was, he said, an initial increase in concentrations of chlorobutadiene "above normal background levels", but from 12 October these had fallen to the analytical detection limit, whatever that may have been. The warning against fish and shellfish consumption was withdrawn on 14 October.
According to Mr Hanley, the "levels detected in samples were of the order of 10,000 times lower" than the concentration at which chlorobutadiene has killed 50% of the blue gill sunfish in toxicity tests.
Monitoring of the area affected by the spill will continue, but no damage is expected because chlorobutadiene is not known to bioaccumulate, Mr Hanley added. Meanwhile, Du Pont has "reviewed its alarm systems and has instructed its staff, if there is any suspicion whatsoever of a spillage, to stop processing immediately and divert the waste stream to an emergency holding tank."
The incident has prompted questions about the Government's intentions to extend the Environmental Protection Act to Northern Ireland. The matter was examined by the House of Commons Environment Committee in 1990, which urged the Government to reduce a substantial and growing legislative backlog in the province.
In its response, the Government promised to introduce various provisions of the 1990 Act, including those dealing with integrated pollution control, statutory nuisance and waste management, in 1993 (ENDS Report 195, pp 25-27).
However, another recent parliamentary reply by Northern Ireland Minister Robert Atkins suggests that those promises will not be kept. Legislation similar to the 1990 Act, he said, will be introduced in Northern Ireland "in due course."2