Istanbul municipality is planning to invite bids for a large dredging project to clean the polluted Golden Horn inlet off the mouth of the Bosporus opening to the Sea of Marmara, according to contracting sources.

The project has a total investment cost of about TL 2.5 million million ($30 million).

The work in 1997 will particularly involve dredging around 2.5 million4 million tonnes of muck estimated to have collected in the waterway, especially from human effluent. The project may also include construction of a sprinkler system to encourage biological cleaning processes, and also may include the relocation of the Valide Sultan Bridge said at present to be blocking water circulation.

Amongst foreign companies likely to be shortlisted are: China Harbour Engineering Company; the Netherlands' Ballast Nedam, Blanke Voort, Boskalis Westminster, Ham, Volker Stevin and Dragados Van Our Group; the US' Great Lakes Dredging; Italy's Dragomar; and Germany's Blifinger & Berger, according to contracting sources.

Local companies are likely to include Sezai Turkes-Feyzi Akkaya, Yuksel, Metis, Tekfen, Kiska, Enka, Idil and Mimas.