ABSTRACT
The main aquifer of the Llobregat delta (Barcelona, Spain) has been affected by seawater intrusion since the 1960s. The Catalan Water Agency (ACA) has sponsored the construction of a positive hydraulic barrier in order to stop and redress seawater intrusion advance due to intensive aquifer development. The hydraulic barrier consists of 15 wells into which highly treated reclaimed water from the wastewater treatment plant of the Baix Llobregat is injected, with salinity reduction through reverse osmosis. A preliminary pilot phase of the project started in late 2007, with highly positive results. Hydrogeological and hydrochemical monitoring data indicate an efficient performance. Quantitative evaluation of such efficiency and operational costs has been analysed. The second phase started in mid 2010 and the full injection barrier is now in operation.
