1. 02/2005 Vallee Aurelie European class THE ORGE RIVER polluted during wet weather

2. 02/2005 Vallee Aurelie European class Situation of the basin The basin of the Orge river belongs to the parisian basin. The river is above Paris and it’s a tributary of the Seine river. It flows out for 52 km and goes through urbanized areas. The basin is a 950 km² area.

3. 02/2005 Vallee Aurelie European class Sources of pollution in this river during wet weather  Wrong connections in the treatment plant  Saturation of the waste water’s pipes  Urbanized running water carries away metals, hydrocarbons, weedkillers and others pollutants  Overloaded of purification stations

4. 02/2005 Vallee Aurelie European class Impacts on the environment Gas exchanged inhibited by hydrocarbons Destruction of ecosystems caused by toxicity Increase of the turbidity of water, flora cannot do photosynthesis any more Stop of oxygenation of the water Decrease of the biodiversity Evapotranspiration restricted by urbanization

5. 02/2005 Vallee Aurelie European class Solutions against the pollution of the Orge river Installation of decant stations 10 desanding pools and deoilers Surveillance in continue to monitor the quality of the water All the data is sent to a central database management. Each year hydrobiologists make a report In the case of accidental pollutions: Samples taken to be analyzed in labs Floating waterblocks to stop and absorb pollution Pumping trucks can be used in specific case

6. 02/2005 Vallee Aurelie European class Example of machine to clean the water http://step.ouvaton.org/tech3.htm

7. 02/2005 Vallee Aurelie European class Evolution of Orge water quality Improvement until the beginning of the 80’s Then stagnation of the quality for 10 years About flora & fauna: status quo Poor biological quality water But the downstream section where the deterioration has been curbed, shows the improvements in cleaning up rainwater and restoring the vegetation of riversides.

8. 02/2005 Vallee Aurelie European class Evolution of the basin

9. 02/2005 Vallee Aurelie European class http://www.sivoa.fr http://step.ouvaton.org/tech3.htm