Almost four million animals have been slaughtered and disposed of during the foot and mouth crisis, and the number is still growing. Under official procedures, each burial site taking more than eight tonnes must be authorised under the 1998 groundwater regulations (ENDS Report 316, pp 6-7 ). Such authorisations are required by the 1980 EU groundwater Directive.
The Department for Environment, Food and Rural Affairs (DEFRA) has estimated that there are some 900 burial sites dotted around the UK. This does not tally with the 642 groundwater authorisations issued by the Agency, leaving a potentially large number of unauthorised sites - though some sites on DEFRA's list appear to be farms on which animals were slaughtered but buried elsewhere.
The true number is unlikely to be known for some time. In May, DEFRA's predecessor, MAFF, began a review to establish the location and content of burial sites and their risks to groundwater. But the review is still ongoing, hamstrung by the continuing crisis in the north of England.
A DEFRA spokesman said: "There are possibly quite a number of burial sites not covered by a groundwater authorisation. This was most likely the case in the early days of the crisis when a lot of work was done quickly and not in a way we would have preferred if there had been more time." DEFRA declined to say when the review will be completed.
Paul Tempany, head of the Environment Agency's foot and mouth task force, said that, as a stopgap, the Agency will implement its own regional monitoring exercise through the autumn covering 150 sites across England and Wales. But the exercise cannot begin in areas still subject to movement restrictions, such as Cumbria, Northumberland and Durham - counties where water pollution risks may be greatest, particularly to private water supplies.
The latest report on the threats to public health posed by action to eradicate the disease, published by the Department of Health,1 claims that the on-farm burial sites are "secure" and that "results so far indicate that private water supplies have not been affected by foot and mouth disposals."
But groundwater contamination takes time to come to light. The Agency is already aware of at least six cases caused by MAFF burying carcasses in the wrong place - three of which were in the north-east. These only came to light after surface waters were contaminated.
In April at a farm near Low Westerhouse in County Durham, MAFF constructed a pit for 1,600 carcasses without an authorisation. The field was notorious for flooding and above a public water main.
According to the Agency, diggers cut through field drains leading to the river Deerness and only narrowly missed the water main. Disinfectants and other fluids from the carcasses entered the Deerness, causing a serious "category two" pollution incident. The main was taken off-line as a precaution. MAFF was forced to move the carcasses two days later.
Mr Tempany said there had also been 420 air pollution incidents to date as a result of the crisis, of which the majority were related to odour problems from landfills and mass burial sites in the north-west. There have also been 150 water pollution incidents - not 250 as the Agency incorrectly told ENDS in May.
But the statistics need to be treated with caution. There may have been considerable over-reporting, especially of odour, in some areas and very little in others. Neither has the Agency been able to categorise many of the incidents, partly because of the difficulty of investigating in restricted areas.
The Agency is preparing a "lessons learned" report into its handling of the crisis. But despite its central role in dealing with the environmental impacts of foot and mouth disease, Mr Tempany said that it has no plans to make the report publicly available.