AWWA JAW58476

For the water supply company Hydron South Holland in the Netherlands, clogged wells constituted a significant problem that lowered production capacity of the well field, disrupted the purification process at the treatment plant, and decreased overall revenues. This study was undertaken to develop a better understanding of the clogging process, the nature of the clogging materials, and the exact position of these materials in the well. The Hydron South Holland wells pump anaerobic groundwater from aquifers consisting of Pleistocene, sandy, and fluvial sediments. Samples were collected from a number of wells with a reduced specific capacity. Light microscopy and electron microscopy were performed on undisturbed samples, and particle size distribution and chemical analyses were conducted on bulk samples. On the basis of study results, a new two-pronged rehabilitation procedure was developed for seriously clogged wells. Initial findings indicate that the procedure offers both good immediate results and a significantly lower clogging rate over the long term. Hydron South Holland is conducting further research to prevent initial clogging and fine-tune well drilling techniques and well design. Utilities experiencing well clogging in similar aquifer conditions can use these findings to optimize their own rehabilitation procedures or as a jumping-off point for new research on well clogging and well design. Includes 9 references, table, figures.