Within this project, waste water flowing into the existing streams of Tuzla basin and subsequently into the Marmara Sea; were collected by laying new mains and collector lines with diameters ranging from 200 mm to 1600 mm. Connections to the existing tunnel and collector have been made and transferred to the Biological Waste water Treatment Plant in Tuzla. In this way, all of the waste water flowing from the Tuzla Basin into the Marmara Sea has been taken under control, and partially pollution of the Marmara Sea has been prevented.