EFFECT OF FLOW RATE ON BIOLOGICAL AND CHEMICAL CLOGGING PROCESSES IN SMALL-DIAMETER AQUIFER STORAGE AND RECOVERY INJECTION WELLS

As groundwater levels and municipal budgets decrease, creative solutions for supplementing water resources are necessary. An ongoing project at the Kansas Geologic Survey (KGS) is investigating a low-cost alternative to traditional aquifer storage and recovery (ASR) systems, by utilizing gravity-induced recharge and small-diameter wells installed with direct-push technology to recharge and store groundwater in a Lower Republican River Valley aquifer. Clogging in recharge wells is a major concern for ASR systems. Many of the current methods used to predict clogging assume a rapid rate of injection. The KGS ASR system will have significantly slower injection rates due to increased frictional losses in small-diameter wells and the absence of injection pumps.

This study investigates clogging at slower injection rates through laboratory column experiments and geochemical analyses. Laboratory columns packed with sand and gravel sediment cores taken from the Pleistocene Belleville Formation during direct-push well installation at the field site are used in clogging experiments. Changes in hydraulic conductivity are monitored in three column sets running at rates of 1 m/d, 3 m/day, and 6 m/day. Each column set contains three columns circulating either sterilized surface water, native aquifer water, or treated surface water to differentiate the influence of physical, chemical, and biological clogging factors at different flow rates. Further understanding of clogging factors at slow flow rates will aid in the selection of the most beneficial redevelopment and pretreatment methods for small-diameter wells in similar ASR projects.