The Runcorn site is the heart of ICI Chemicals and Polymers' chlorine chemicals business. Three years ago, the company began studies which were expected to result in a multi-million pound investment to improve its effluent management facilities (ENDS Report 170, pp 10-12). But the expenditures have yet to materialise.
Meanwhile, the need for action has become urgent. ICI has been prosecuted four times by the NRA in the last six months for breaches of its discharge consents. Three of the cases involved "black list" chlorocarbon solvents (ENDS Reports 201, pp 37-38 and 204, p 37 ). The NRA is now considering another prosecution relating to chlorocarbon discharges from the site last winter.
The Runcorn site is the largest point source of chlorocarbon effluents in the UK. These discharge via some 40 outfalls to the Weston Canal, which is classified as a grossly polluted class 4 watercourse. Last year, the canal failed to comply with EQSs for carbon tetrachloride, chloroform, hexachlorobenzene and hexachlorobutadiene laid down by EC legislation.
ICI says it is considering spending "tens of millions" of pounds to improve the site's ageing drainage system and install new effluent treatment facilities. An implementation timetable stretching to 1996 has been mooted by the company, but it has been unable to give the NRA a firm programme because investment plans have not been sanctioned by senior management. Without such a timetable, the NRA cannot predict when the canal will meet the EQSs.
Next January, EC rules laying down EQSs for three more chlorocarbons - 1,2-dichloroethane, trichloroethylene and tetrachloroethylene - come into force. The NRA believes that the canal will fail the EQS at least for 1,2-dichloroethane, and possibly the other two compounds. It has informed the DoE of past breaches and the high probability that these will recur.
The warning has given the DoE the opportunity to direct the NRA to impose tighter discharge limits to ensure that the EQSs are met. However, in ICI's case the breaches have generally been caused by incidents rather than routine discharges. Even if zero discharge limits were imposed on the company, the NRA believes that this would not guarantee compliance with the EQSs.
As an example, the NRA quotes the case of carbon tetrachloride. Last year, monitoring showed that levels in the canal were occasionally within the EQS of 12µg/l. But compliance for any 12-month period depends on the average of 12 samples, and two of last year's samples were grossly in breach of the EQS due to spillages. In February and September, the NRA detected carbon tetrachloride at 126µg/l and 209µg/l, respectively, in the canal.
Just one such incident, the NRA points out, is likely to result in a breach of the EQS. The NRA believes that even if ICI's routine effluent performance improves, it is unlikely to prevent incidents affecting the canal because of the site's poor infrastructure. Investment in better containment and effluent treatment is needed, it maintains.
ICI, however, claims that it is capable of ensuring compliance with the EQSs without major investment. Improved management and training have brought its compliance rate for routine discharges to 97%.
Plant closures will also help to reduce the pollution loading. A carbon tetrachloride plant at Runcorn was closed in February. ICI says this will reduce its discharges of carbon tetrachloride, hexachlorobenzene and hexachloro-butadiene. Closure of a CFC plant will follow next spring.
ICI has had to face tougher regulation from the NRA than from the former North West Water Authority. At Runcorn, it was permitted a mixing zone within which it was not required to comply with EQSs which extended for 30 kilometres along the Weston Canal, into the Manchester Ship Canal and then into the Mersey estuary.
The NRA has now moved the mixing zone to Sutton Weir, 1.5 kilometres downstream of the site boundary. Even this allows for volatile chlorine compounds to be removed from the canal by evaporation, because the site itself extends for several kilometres along the canal. Dilution is also provided by the river Weaver, which joins the canal just above the weir.
The NRA believes that monitoring any closer would be impractical because the canal is poorly mixed and the heavier chlorocarbons tend to flow along the bottom. Routine monitoring would involve taking several samples through the water column.
ICI's discharge consents came up for review last year and are currently under discussion. The NRA says it is pressing for the tightest standards it believes the company can meet.
The company's failure to come forward with an improvement programme reflects the growing environmental squeeze on the chlorine chemicals business. The looming phase-out of CFCs, which consume one-sixth of ICI's chlorine production, is making a major impact on its cash flows. These chemicals, as well as methyl chloroform, will be banned by the end of 1995.
John Smith, Operations Development Manager at Runcorn, admits that these developments "will downsize a substantial proportion of the assets at Runcorn and impact on our effluent project plans. The challenge is to identify a solution in time to support our on-going businesses."