EQSs are a central plank of UK policy for protecting the water environment from toxic chemicals such as those on the EC's black and grey lists and the UK's own "red list".
Under section 28(3) of the 1990 Act, HMIP must not authorise a process under IPC if the National Rivers Authority (NRA) certifies that it "will result in or contribute to" a breach of a statutory water quality standard. The section means that dischargers in this position may fail to obtain IPC permits, or at least face more onerous conditions than those conforming to the "best available techniques not entailing excessive cost".
Well publicised breaches of several EQSs have been occurring on the Weston canal and river Weaver, Merseyside. The river receives discharges from ICI's chloromethanes plant in Runcorn, and in 1991 these caused breaches of the EQSs for chloroform, hexachlorobenzene, hexachlorobutadiene and carbon tetrachloride. However, the closure of a carbon tetra-chloride plant in February 1992 has left only chloroform concentrations above the EQS.
Chloroform levels in the river have been falling as ICI has diverted effluents to evaporation lagoons before discharge. In 1991, the annual mean concentration in the Weaver downstream of the site was 55µg/l. Last year it was down to 16.9µg/l. However, the EQS for chloroform is an annual average of 12µg/l.
According to ICI's Environment Advisor, Dr Nick Pumphrey, compliance with the EQS should be achieved by the time HMIP determines its IPC application. This must be submitted by next January, but the company expects HMIP's consideration of the application to take at least four months.
ICI is diverting drains and improving its housekeeping in an effort to curb its chloroform discharges. But further improvements will require planning permission and board approval for an effluent treatment plant and incinerator costing about £40 million. A planning decision from Halton Borough Council is expected in November.
Further breaches of EQSs in the Weaver are caused by discharges from the former ICI Lostock Gralam site, now operated by its sister company Zeneca. Carbon tetrachloride from the works' Alloprene rubber plant caused breaches of the EQS in 1991 and 1992, but the plant closed in November 1992. The chemical is no longer used at the works, but is still discharging to the river from an old effluent lagoon.
By next July, Zeneca must apply for an IPC authorisation for a process manufacturing Winnofil, an inorganic filler. It is expected to argue that this has no connection with the lagoon and should not be implicated in any continuing breach of the EQS.
Perhaps the most intractable problem is at Hays Chemical Distribution's Sandbach site, which operates a chlor-alkali process using mercury cell technology. Effluent from the works is discharged to the Trent and Mersey Canal, which affords only a 15-fold dilution. The EQS for mercury is regularly breached in the canal.
In the early 1980s, in the aftermath of an EC Directive on mercury discharges, the Department of the Environment agreed to treat the plant as a special case. Instead of requiring compliance with the EQS, it adopted the alternative allowed in the Directive of setting a discharge limit value for mercury. This was something of an embarrassment for the Government because in EC negotiations on this and other "black list" Directives it was isolated for many years in insisting that the EQS approach was the superior method of control.
Hays' plant discharges about 17µg of mercury per litre of effluent, according to a spokesman. This is well within its consent limit of 50µg/l, but not low enough to secure compliance with the EQS of 1µg/l. Resuspension of mercury from sediments during periodic dredging operations may also contribute to breaches of the EQS.
The plant's IPC application is due by next February, but Hays has no clear idea of how its situation will be reconciled with the 1990 Act. It appears to be expecting another bureaucratic fix, and would say only that it had "no concerns for the long-term future of the site".
Other firms may soon face similar difficulties. Long-awaited regulations giving statutory force to existing advisory EQSs for red list substances are expected by the end of the year (ENDS Report 202, pp 29-30). The new rules are also expected to give legal backing to advisory EQSs for grey list substances such as zinc, chromium, copper and several pesticides used in industry.
Exceedances of some of these EQSs are more common than for black list substances. In the North West region alone, the NRA says there are ten cases where EQSs for grey list substances are being breached due to industrial discharges, compared with only three for black list EQSs.