Rehabilitation work is required to increase well productivity, which decreases with the elapsed time of pumping owing to the clogging of the water well. Clogging causes not only a reduction in the well productivity but also a deterioration of the water quality. For unclogging and rehabilitating wells, several techniques are used such as brushing, air surging, surge blocks, and gas impulse. In this study, the high-pressure air impulse technique, which effectively and economically rehabilitates wells, was applied to a riverbank filtration site in Korea for the same objective. At most of the wells, the hydraulic parameters (transmissivity, storage coefficient, and specific capacity) were increased by the application of the high-pressure air impulse technique. The well loss change values also indicate an increase in the hydraulic parameters by the air impulse implementation. Thus, the high-pressure air impulse technique can be efficiently and economically applied to water and riverbank filtration wells for rehabilitating the decreased productivity.

Abstract
1. Introduction
2. Methods
3. Study area
4. Results
    4.1. Changes in the hydraulic parameters by theair impulse technique
    4.2. Changes in the well loss by the air impulsetechnique
    4.3 Correlation between the hydraulic parameters bythe air impulse technique
5. Conclusions
References

• Hang-Tak Jeon(Department of Geological Sciences, Pusan National University)
• Se-Yeong Hamm(Department of Geological Sciences, Pusan National University) Corresponding author
• Jae-Yeol Cheong(R&D Institute, Korea Radioactive Waste Agency)
• Suk-Jong Han(Geosg)
• Sul-Min Yun(Department of Geological Sciences, Pusan National University)