Pennon's Viridor subsidiary has won a 25-year waste treatment deal with a group of five Welsh local authorities.FTSE 250-listed Pennon said the public private partnership contract will help enable Viridor's £223m energy-from-waste (EfW) facility being built at Trident Park in Cardiff to be earnings enhancing in its first full year of operation. The facility is due for completion in 2014.Viridor signed the agreement with Cardiff Council, which was acting on behalf of Prosiect Gwyrdd, a partnership of five local authorities: Cardiff, Monmouthshire, Caerphilly, Vale of Glamorgan and Newport.Prosiect Gwyrdd will deliver an average of 172,000 tonnes of waste per year with the plant also taking up to 178,000 tonnes of commercial and industrial waste from across South Wales. Operating at its full capacity of 350,000 tonnes, the facility will generate 28 MW of power by producing electricity, enough energy to provide 50,000 households entire electric needs. Viridor is also working with Cardiff Council on future plans for a district heating network, which could increase the power generation through electricity and heat to 43 MW.Viridor Chief Executive Ian McAulay said: "We are delighted to have signed this contract with Prosiect Gwyrdd. The project represents another key milestone in the development of Viridor's PPP/EfW strategy."