Dr. Tom Ryan:

I thank Deputy Ó Broin for his question. I will refer to the current technologies for treating domestic wastewater and those that are incorporated into the revised code that we have just consulted on that allow greater flexibility in areas of low permeability soil. Once one goes above a certain soil permeability level where the soil is compacted there is nowhere for effluent water to be discharged. Therefore, dangerous pathogens and E. coli accumulate on the property in ponds and gives rise to significant health risks for the people in the dwelling, the children, the neighbours and water in wells. That is the difficulty with low permeability soils. The code extends flexibility because of the new technologies. Therefore, we can push the limit somewhat and, as has been signalled, that may allow some permissions to be granted in the right circumstances. Planners will consider that.

Looking to the future, the willow bed evapo-transpiration systems are promising. We have been happy to support the research but more work needs to be done. For certain elements of the discharge willow beds are quite effective but it does not allow for zero discharge. That means there are some liquids. More important, it also means that the system is not quite effective at removing the more hazardous pathogens, in particular E. coli. It is not a case that there is no impact. There could be a significant impact with the accumulation of residual waters with E. coli. The technology looks promising because it is effective at removing some of the other elements but this is a stumbling block worthy of pursuing further research. In terms of a timeframe for research, it could take a couple of seasons to establish but there are ideas being contemplated as to how these systems might be more effective. It is an area that is well worth pursuing and the EPA would be happy to support such work.