Environmental concerns are now central to the production process due to the protracted Galmoy mine planning row. Four environmental teams oversee operations, monitoring everything from noise levels to water and air quality.

Lorries carrying zinc are washed before they leave the plant and washed again at New Ross port to minimise dust pollution. Their cargo is sealed in strengthened containers to prevent spillage in the case of an accident.

Chief executive Mr Tony O'Reilly jnr argues: "we are now demonstrating that you can have safe mining in an area that is agriculturally based."

However, some locals still fear the long-term effects of the mine, and particularly its tailings pond where the waste material is deposited.

Ms Charlotte Colchester, a leading member of the now-defunct Galmoy Awareness Group (GAG), which represented many of the objectors, says that local people may have to live with "a toxic lake", long after the mine is closed. "We are all very worried about what's going to happen when the tailings pond is full."

Arcon has planning permission for three tailings "cells", the first of which has been built and is already filling up with the residue of its operations - a mixture of chemicals and heavy metals.

This waste pond poses two main threats. First, if it was to fail, its contents could leach into groundwater supplies or nearby watercourses; and second, if it was to dry out, strong winds could blow dust particles from the pond onto neighbouring land, causing pollution and potentially damaging health.

Mr O'Reilly dismisses these fears, claiming the tailings pond is "built to the highest specifications in the world" and constantly watered to ensure it doesn't become dry.

Mrs Frances Phelan, one of a handful of landowners who decided not to sell their lands to Arcon and whose farm borders the tailings pond, is still concerned. "We just don't know what dangers lie ahead," she says. "Our biggest worry is what would happen if the pond dried out and whether it would affect our cattle."

The Silvermines facility in Co Tipperary encountered the problem of tailings dust on several occasions, and some locals still have strong feelings about the issue.