@article{martinez_widdowson_2024, title={Evaluation of groundwater travel time through a multilayered aquifer using multiple tracers and a novel transport approximation}, url={https://doi.org/10.1007/s10040-024-02846-3}, DOI={10.1007/s10040-024-02846-3}, abstractNote={Abstract Aquifer long-term replenishment (ALTR) is a managed aquifer recharge (MAR) strategy by which reclaimed water is continuously delivered by injection wells to depleted, confined aquifer systems to increase groundwater storage and increase the potentiometric surface over space and time. One implication of large-scale continuous recharge is a large radial impact and the need to quantify transport in radially extensive strata. The use of an artificial tracer can be cost-prohibitive as the radial front moves further from the injection well. This investigation employs a novel approximation for radial transport to track the radial front of recharge, injectate constituents and simulation of tracer breakthrough concentrations under transient recharge rates, variable depth-dependent flow distributions over time, and variable influent concentrations. Six constituents—sulfate, chloride, total organic carbon (TOC), fluoride, 1,4-dioxane and N-nitrosodimethylamine (NDMA)—were chosen to evaluate conservative transport and semiqualitatively assess attenuation of nonconservative constituents relative to conservative tracers. Results indicate that sulfate acted as the most effective conservative tracer for characterization of transport and travel times at the study site. The analytical model was modified to account for variable operations at the MAR demonstration facility and was effective in simulating breakthrough curves over the period of performance, particularly sulfate concentrations at a monitoring well located 104 m from the injection well. The behavior of the remaining constituents is discussed, and the qualities of an effective intrinsic tracer for future ALTR projects are identified.}, journal={Hydrogeology Journal}, author={Martinez, Meredith B. and Widdowson, Mark A.}, year={2024}, month={Nov} }
 @article{martinez_widdowson_2024, title={Evaluating Flow Distribution in a Multiaquifer Recharge Well Using an In Situ Flowmeter}, url={https://doi.org/10.1111/gwat.13379}, DOI={10.1111/gwat.13379}, abstractNote={Quantifying the flow rate distribution in a multiple-screen recharge well is relevant to understanding groundwater flow and solute transport behavior in managed aquifer recharge (MAR) operations. In this study, an impeller flowmeter was deployed to measure flow rate distribution in a multiple-screen MAR well under both recharge and pumping conditions screened in the multiple-strata of the Virginia Coastal Plain aquifer system. Preferential flow distribution in the well was observed through the uppermost screens during recharge while flow distribution was more evenly distributed along all screens under pumping conditions. Analysis of flow along individual screens also indicates preferential flow to the upper part of the screen during both recharge and pumping. Comparison of flowmeter results under both recharge and pumping conditions to previous site-specific measurements suggests that the distribution of flow may vary with time, depending on well screen condition and well rehabilitation efforts, and should be monitored over the duration of an MAR project. These results have implications for groundwater quality given that flow distribution in a multiscreen recharge well has profound impact on travel time and on transport modeling if flow is assumed to be steady and consistent under a range of operational conditions.}, journal={Groundwater}, author={Martinez, Meredith B. and Widdowson, Mark A.}, year={2024}, month={Jul} }
 @article{martinez_widdowson_bott_holloway_heisig‐mitchell_wilson_2022, title={Demonstration of Managed Aquifer Recharge in a Coastal Plain Aquifer: Lessons Learned}, volume={4}, url={https://doi.org/10.1111/gwat.13197}, DOI={10.1111/gwat.13197}, abstractNote={Abstract The sustainable water initiative for tomorrow (SWIFT) is a 378,000 m 3 /day (100 MGD) managed aquifer recharge (MAR) program designed by the Hampton Roads Sanitation District (HRSD) to rehabilitate the Potomac Aquifer System (PAS) in the Coastal Plain of Eastern Virginia. Groundwater is a primary water source in Eastern Virginia with over 93% of reported use derived from the PAS. Starting in May 2018, HRSD has operated a 3780 m 3 /day (1.0 MGD) MAR demonstration facility at the SWIFT Research Center (SWIFT‐RC) in Suffolk, Virginia. The primary aim of the SWIFT‐RC is to demonstrate, at a meaningful scale, the feasibility of MAR using deep well recharge into confined PAS hydrostratigraphic unit. The SWIFT‐RC employs advanced water treatment technology to bring secondary effluent from an HRSD wastewater treatment plant to drinking water standards. Lessons learned include the evaluation and selection of a multiple barrier carbon‐based treatment system to ensure water quality and maintain geochemical compatibility between MAR water and native groundwater, and the evaluation and selection of aluminum chlorohydrate for stabilizing aquifer clays immediately around the well to accept the fresher recharge water. The distribution of flow in the SWIFT‐RC multiscreen recharge well and associated well injectivity were variable with time resulting from changing conditions in the well. Dynamic recharge well performance was quantified through the combined analysis of intrinsic and artificial tracer transport, in situ flowmeter testing, and water level analysis. Monitoring well nests and a depth‐discrete sampling system supported a robust sampling plan to analyze chemical transport and attenuation in SWIFT‐RC groundwater.}, journal={Groundwater}, publisher={Wiley}, author={Martinez, Meredith B. and Widdowson, Mark A. and Bott, Charles and Holloway, Dan and Heisig‐Mitchell, Jamie and Wilson, Christopher}, year={2022}, month={Sep} }
 @inproceedings{bullard_widdowson_salazar-benites_heisig-mitchell_nelson_bott_2019, title={Managed Aquifer Recharge: Transport and Attenuation in a Coastal Plain Aquifer}, url={http://dx.doi.org/10.1061/9780784482346.011}, DOI={10.1061/9780784482346.011}, abstractNote={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.}, booktitle={World Environmental and Water Resources Congress 2019}, publisher={American Society of Civil Engineers}, author={Bullard, Meredith G. and Widdowson, Mark and Salazar-Benites, Germano and Heisig-Mitchell, Jamie and Nelson, Andy and Bott, Charles}, year={2019}, month={May} }