The case concerned a pollution incident in May 1990, when the discharge from Yorkshire Water's North Bierley sewage works, Bradford, exceeded its consent limits for BOD and suspended solids. In May 1991, Dewsbury magistrates found the company guilty of breaching its consent under section 107 of the Water Act 1989.
The appeal was heard at Wakefield Crown Court, where the legal arguments focussed on sections 107 and 108 of the Act.
The offence under section 107 is to "cause or knowingly permit" the discharge of polluting matter, except outside the terms of a consent as provided in section 108.
Yorkshire Water insisted it neither caused nor knowingly permitted the offending discharge because it was the result of an illegal discharge to sewer of the solvent iso-octanol, which had disabled the filters at its sewage works. In doing so it relied on section 108(7), which provides that a sewerage undertaker cannot be convicted of an offence under section 107 if the breach in question is "attributable" to an illegal discharge to sewer and the undertaker "could not reasonably have been expected to prevent the discharge into the sewer or works."
The NRA argued that the company could have done more to protect the watercourse. The illegal discharge had been made at night, when the sewage works was unmanned. The only instrumentation at the inlet to the works was a pH meter. And the solvent-contaminated influent was not diverted to storm tanks.
The key precedent cited at the hearing was the 1972 case of Alphacell v Woodward, where a company had been convicted of a pollution offence which had resulted from the blockage of a pump by leaves. The conviction was upheld on appeal to the House of Lords, which ruled that the firm had "caused" the discharge by virtue of having an operation which had malfunctioned next to a river.
The NRA drew an analogy between that case and Yorkshire Water's sewage works, but Mr Recorder Williamson concluded that the overwhelming opinion of the Lords in the 1972 case was that "whatever else causing might or might not involve it did involve some active operation, as opposed to mere tacit standing by and looking on", which is how Yorkshire Water's operation could legitimately be characterised.
Posing the question whether there was therefore no sanction if a sewerage undertaker did nothing about pollutants entering its sewage works, Mr Williamson went on to point out that section 107(5) of the 1989 Act stipulated that the undertaker would be deemed to have caused a polluting discharge if this was caused by a trade effluent which it was bound unconditionally or subject to conditions to receive at its sewage works. "Thus Yorkshire Water Services Limited is accountable for its dealings with pollutants, but only those pollutants which it has undertaken to deal with, subject to conditions."
The appeal was allowed, but the NRA says it will appeal against the judgement. The outcome will determine whether water companies will need to make sizeable investments and alter the operating practices at many of their sewage works.