AWWA JAW69830

Clogging of groundwater abstraction wells is a common phenomenon, so common that it is often considered inevitable. However, by determining whether the clogging is chemical or mechanical, and by using operation procedures specific to each type of clogging phenomenon, groundwater abstraction can be significantly more reliable and cost-effective. This article examines how to diagnose and to mitigate screen slot (chemical) clogging and well bore (mechanical) clogging. Screen slot clogging is evidenced by increasing entrance resistance, the difference in head between the abstraction well and the observation well in its gravel pack. Continuous operation of the well will prevent this problem. Well bore clogging is evidenced by an entrance resistance that does not increase over time. Alternating well operation and idle periods will prevent clogging in these instances. Applying the results and recommendations of this research can help water providers avoid the extra costs associated with clogged wells, which the authors estimate can be up to $6,500 per well for monitoring, regeneration, and replacement. Includes 26 references, table, figures.