UC Davis

In response to a growing need to address imbalanced water supplies, managed aquifer recharge (MAR) can be used to improve groundwater management. Infiltration basins are a common method for percolating surface water into an underlying unconfined aquifer, helping to meet three main water management objectives: providing storage for stormwater runoff, increasing groundwater storage, and treating wastewater through natural processes (soil aquifer treatment, SAT). Despite having been used globally for centuries, there is still a large potential for increased use and widespread global implementation of infiltration basins (IBs).Prior to initiating and operating an environmental engineering project, including an IB, a feasibility study is typically conducted to assess the project's practicality, risks, and likelihood of success. The assessment typically evaluates the project from legal, technical, and economic standpoints. The design and implementation of an IB depend on multiple physical and chemical, location-specific factors, including surface area requirements, target recharge rates, water and chemistry, and operational needs. However, knowledge gaps still exist in predictive methods and in identifying optimal conditions for IB operation. The objective of this review was to critically examine the current state of knowledge regarding criteria that should be included in a feasibility assessment for an IB project in the United States, and to identify knowledge gaps that should be addressed with future research. To address this, a literature review was conducted that included rapid IBs, stormwater IBs, and soil aquifer treatment methods. We identified key system considerations that impact the feasibility of an IB project and characterized the state of knowledge on these topics using a Knowledge Quadrant. Feasibility considerations were examined from technical, legal, and economic perspectives, including source water availability, changes to source water quality, hydrogeological characteristics, and clogging. For each feasibility consideration, we outlined major gaps in understanding, such as US-based valuation of non-market externalities of IBs, the fate of contaminants of emerging concern, determining the value of recharged water, the impact of preferential flow paths on treatment efficiency and storage, ideal hydraulic loading frequency (wetting-drying cycling), and recovery credits. The tradeoffs identified in this review generally involved the quantity of water recharged, the quality of water stored or recovered, and the cost to produce and operate the IB. By identifying areas that have been overlooked in current research and practical guidance on MAR via IBs, future feasibility and optimization studies can improve in accuracy, and risks can be better managed, ultimately enhancing the availability and effectiveness of infiltration as part of MAR practices.