The capacity of drinking water wells, i.e. the yield for a given drawdown, is often decreasing after a certain time of operation. This effect is called well ageing and is due to different processes related to the geology and hydrochemistry at any given well site and to the construction and operation of these wells. To avoid impacts on water quantity and quality and to ensure the economic efficiency of well operation, the pump dimensioning, water quantities, operation times, and the maintenance intervals and methods must be planned according to the characteristic features of each well depending on (i) site conditions, (ii) well performance and (iii) cost-benefit analysis.Based on the evaluation of the state of the art during the preparatory phase WellMa1, the second phase of the project implies the investigation of wells in Berlin and France in terms of their ageing behaviour with the aim to determine suitable measures helping to slow down well ageing processes and optimise strategies for well operation and maintenance. Four work packages have been defined:

1. Asessment of the impacts of intermittent pumping on iron deposits in drinking water wells,

2. Assessment of the effectiveness of the preventive maintenance with H2O2,

3. Development of decision support tools providing for optimised monitoring, early warning and pre-diagnosis, and economic considerations on well maintenance,

4. Decision support and test application for regeneration technologies in order to support the selection of the most efficient regeneration method.

The investigations are supplemented by the project WellMaDNA (11/2007 – 10/2010), using advanced methods of molecular biology to characterise clogging-inducing iron bacteria. By means of microbiological analyses, the living conditions for iron bacteria in wells will be elucidated and the efficiency of H2O2 treatment to inactivate those bacteria will be tested.

© header photo: pigadi GmbH