An Bord Pleanála has vetoed a proposal by a developer to build a hotel and spa in the foothills of the Dublin Mountains.

Hotelier Tom Moran's Caspian Country Investments Ltd was refused planning permission for Sandyford Spa resort because it would have "an adverse impact on the visual and landscape amenity of this upland area".

The board also said it has concerns about the impact on public health of the excavation of an unauthorised landfill on the site.

This overturns a previous decision by Dun Laoghaire-Rathdown County Council to grant permission for the venture. An Taisce appealed the planning permission saying the location is "wrong" and the development fails to meet the requirements of a High Amenity Zone.

It contended that no development should be allowed on the mountain side of the zoning border because, once permitted, it would set a precedent and encourage other developers to take advantage of scenic sites.

Another appellant, Ruth Blackith, said the hill on the south-west side of Woodside and Blackglen Roads should be preserved as a foothill of the Dublin and Wicklow Mountains and no further development should be allowed.

Located behind Lamb Doyle's pub, off the Blackglen Road on a 55-acre site formerly known as Jennings lands, the proposal was for 14 spa treatment rooms, hydrotherapy facilities, a 25-metre pool, a recreational pool, a 250-bedroom hotel, 35 apart-hotel suites, a conference and banqueting centre, restaurant, cafe, bars, seven meeting rooms and 443 car-parking spaces.

An Bord Pleanála said that in the absence of detailed information regarding the types of wastes in an unauthorised landfill on the site, it is not satisfied that the development "would not have an adverse impact upon public health" following the planned excavation of parts of the site, "particularly in terms of potential toxicity and contamination , and site stability".

This was a second attempt by Caspian Country Investments to secure planning permission for this project on these lands, the first being withdrawn following the public reaction to the size and form of the proposal.

Tom Moran is best known as the owner of the Red Cow complex on the Naas Road. He also owns hotels in Cork and Dublin. In 2004 he sold off a number of pubs, including the Playwright in Blackrock and The Baroque in Clondalkin.