Effect of Wastewater Injection on Ground Water Quality

Effluents from the treatment plant of Saint Jean de Monts and Saint Hilaire de Riez have been injected into a confined ground water for twelve years. This ground water is connected with the sea. Effluent floats on the surface of the aquifer and it disperses by dilution at the freshwater/salt water interface. The aquifer acts as a direct overflow pipe. The injection of effluent has preserved the quality of waters in the coastal area and in the Breton Marsh.