The NRA's investigation is focussed on Higher Kiln landfill, near Tiverton. The site is operated by Haul-Waste, a subsidiary of English China Clays. It is unlined and has been run as a "dilute and disperse" operation since the 1940s. The local geology is a complex series of porous limestones and shales.
Devon County Council believes that the site accepted oils and chrome wastes from the tanning industry in its early years. Oil was detected in the aquifer as long ago as 1978, when the council refused to grant it a licence following objections from the South West Water Authority. The decision was overturned on appeal after expert witnesses agreed that the site was licensable for certain wastes.
Since then, the landfill has accepted a limited range of liquid wastes at a rate of seven million gallons per year. Recent inputs have included residues from a pharmaceutical aerosol manufacturer, aqueous wastes from asbestos cutting, food processing and brewing firms, and leachates from domestic waste landfills.
Last year, the NRA asked Haul-Waste to drill seven monitoring boreholes, to complement 11 already in use. It has now analysed samples from some of these wells by gas chromatography-mass spectrometry and found a variety of organic compounds.
Boreholes to the east and west of the site show the highest levels of contamination. To the west, trimethylcyclohexanol was found at 300 ppb, trimethylcyclohexenone and naphthalene at 200ppb, 1,4-dioxane at 150ppb, and methyl phenol at 125ppb, together with weathered fuel oil and paraffin.
The NRA told ENDS that it regards all seven compounds as falling in List 1 of the 1980 EC groundwater Directive. In 1990, following a controversy over another "dilute and disperse" landfill which threatened to land the UK in the European Court of Justice, the Department of the Environment issued revised guidance on the Directive which said that inputs of List I substances to groundwater should be prohibited unless they were in such small amounts as to enable unimpaired use of an aquifer (ENDS Report 190, pp 34-5). The NRA says that the List I substances found around Higher Kiln "should not be there at all."
The NRA also found 1,4-dioxane at 20ppb in a spring used as a private water supply some 600 metres from the landfill. The owners have been advised not to drink the water by the local environmental health department, and other wells in the area are being analysed. Traces of the compound, which is widely used as an industrial solvent, have also been detected up to 1.5 miles away in the river Batherm.
Haul-Waste has suspended operations while the inquiry proceeds. The company told ENDS that "to its knowledge" no wastes received at the site contained any of the substances detected by the NRA, which have not been detected by its own analyses. The firm regards the evidence as inconclusive, although there are no other industrial sources in the vicinity.