CHARACTERIZATION OF EXISTING BORROW PITS FOR FEASIBILITY AS INFILTRATION BASINS IN CRAIGHEAD COUNTY, ARKANSAS

The Mississippi River Valley Alluvial Aquifer is a major source of irrigation water in Arkansas. Groundwater levels west of Crowley’s Ridge in northeast Arkansas have declined long-term due to continued and unsustainable withdrawals. This groundwater decline is mainly attributed to long-term irrigation in excess of groundwater recharge. One major barrier to recharge is the existence of a soil clay layer which serves as a confining cap. Unsaturated sand below the confining clay layer could be utilized to improve water quality of infiltrated surface water while enhancing groundwater recharge. It has been suggested that highway borrow pits could be rehabilitated to act as infiltration basins, with the permission of landowners, to help offset groundwater decline locally. Currently, fourteen exposed borrow pits exist in Craighead County as unpurposed land. To determine the utility of these existing borrow pits, data must be collected to quantify their characteristics. Data will be presented from these pits and include soil type, depth to groundwater level for suitable water treatment, size, age/development, and aquifer conditions (depth to groundwater, saturated thickness, confining clay cap thickness). Aquifer conditions will be characterized using available well log data to predict infiltration rates and field capacity. These data will be used to prioritize these borrow pits for suitability as infiltration basins. This managed aquifer recharge strategy could provide an alternative to a surface water diversion for this area as a way to promote groundwater sustainability.