Managed Aquifer Recharge: Transport and Attenuation in a Coastal Plain Aquifer

The Sustainable Water Initiative for Tomorrow (SWIFT) program is an initiative to replenish the Potomac aquifer system (PAS) using managed aquifer recharge (MAR). The SWIFT Research Center is a 1 MGD advanced water treatment facility producing reuse water suitable for MAR. In order to characterize flow distribution through a multiscreen recharge well and solute travel time, we analyzed tracer breakthrough curves using solute transport models modified using the method of superposition. Distinct breakthrough was observed in the upper and middle Potomac aquifers with travel time varying from approximately 2-37 days over a 50-ft radial distance. Approximately 73% of the recharge was delivered to 3 of the 11 well screens. Recharge flow to the lower Potomac aquifer was negligible as indicated by relatively slow breakthrough. Breakthrough curves were affected by recharge stoppages during the initial evaluation period with some screening locations exhibiting abrupt changes in specific conductivity during stoppages. Results of the initial groundwater recharge efforts are presented, including implications for full-scale implementation of SWIFT.