The need for a proposed massive sewage treatment facility for the Dublin region has been questioned in a new report by consultant engineers.
The report has also highlighted concerns that despite the existence of a sewage treatment facility for Dublin at Ringsend, raw sewage is leaking into water sources in the region because of overflows and the poor state of the city's sewers in some places.
Written by English-based Pick Everard engineering consultants, the report claims that if the proposed facility is constructed at Portrane, it would lead to vast quantities of rainwater being treated needlessly.
It states that millions of litres of clean rainwater are already being processed by the sewage treatment facility in Dublin's Ringsend facility, which was completed just five years ago.
Commissioned by a group campaigning against the proposed facility for the Portrane area in Dublin, the report states that the Ringsend plant should have the capacity to deal with 90 per cent of sewage from the greater Dublin area if the rainwater was removed from the system.
The report reviewed the Greater Dublin Strategic Drainage Study, which recommended the construction of a new sewage treatment facility near Portrane of a similar size to that in Ringsend to deal with sewage from the greater Dublin area, including parts of Meath, Kildare and Wicklow.
The new report states that there is a fundamental question about the need for such a facility.
It states: "If the recommendations in the Greater Dublin Strategic Drainage Study are adopted it will result in the construction of a new waste-water treatment plant, the capacity of which will effectively equal the volume of ground and surface water entering the sewerage system."
It adds that drains which deal with storm or rain water have been incorrectly linked into foul water sewers carrying water to the treatment facility.This storm water should not require sewage treatment and should be able to flow directly into rivers or lakes.
It has also raised concerns about the seepage of untreated sewage into the river Liffey and other water sources in the Dublin region due to drainage overflows, and states that this is highlighted in the drainage study carried out by the Dublin local authorities.
This in turn has "the potential to pollute drinking water supplies taken from these aquifers, posing risks to health".
According to the new report, the Dublin local authorities should avoid the proposed Portrane plant and should instead focus investment on repairing and replacing the drainage network to address both the health risk and the issue of rainwater flowing into the foul drainage system.
Yesterday, Fairshare, the local group that commissioned the Pick Everard report and which is campaigning against the Portrane facility, said the proposed facility and the associated sewerage system, which could cost up to €1 billion, would represent a waste of public money.
Neil Dempsey of Fairshare described the report as highly significant. "In other words, half of what is going into Ringsend to be treated every day is rain or storm water," he said. "We risk making the same mistake again with Portrane."
Fingal County Council, which is responsible for the project, has consistently stated that no decision has been made to construct the proposed Portrane facility.