ABSTRACT
The Drinking Water Company for the Dutch province of Overijssel (WMO) is investigating well recharge of semi-purified surface water at a future production plant Leeuwterveld. At a nearby existing conventional well field an injection experiment was carried out using one of the pumping wells for injection and another, at a distance of 85 m, as a recovery well. Two observation wells were placed between these two wells, each with 3 observation screens. For a period of 1.5 years oxic drinking water was injected into the anoxic aquifer. Chemical analysis of water samples shows that the injected water underwent reduction due to the oxidation of pyrite. The sequence of the release of heavy metals from pyrite, adsorption processes and cation exchange is demonstrated in graphs. The retardation of several parameters was calculated using natural tracers.
