Planning for Managed Aquifer Recharge Projects

Abstract

Managed aquifer recharge (MAR) involves the intentional recharge of water to aquifers for subsequent recovery or for environmental benefits. It is an increasingly common water resources management strategy but, despite its use for many decades, is unfamiliar to many. This lack of widespread understanding makes it essential that MAR projects are developed using a systematic, comprehensive and transparent approach. This paper outlines a proven and successful approach to planning and developing MAR projects. The process includes three steps, consisting of developing project objectives, developing evaluation criteria for potential MAR projects, and, after collecting and evaluating pertinent data, ranking potential projects against those criteria. Project objectives help define the data that should be collected and the evaluation criteria that are relevant to consider. Commonly used criteria include those relating to water supply, aquifer restoration, water quality and environmental protection. Key evaluation criteria that are discussed in more detail include the availability of water that would be used for recharge, the suitability of receiving aquifers to accept and retain the recharged water, and the compatibility of recharged water with the aquifer into which it is placed. Potential MAR projects can be ranked objectively by quantifying the evaluation criteria and assigning ranking scores to them. The potential project that best meets the project objectives will score the most favorably. Using a quantitative and objective process to evaluate and rank potential projects will increase support by project stakeholders and increase the likelihood that the project will be successful.

Financing Managed Aquifer Recharge Projects

“…The main recharge methods in use are injection wells and surface infiltration basins. The principal cost components to be financed in most MAR projects include (Pyne 2005; Doremus and Job 2022; McCurry and Pyne 2022; Zheng et al 2023): Water rights/permits for water source and storage (surface water, groundwater, stormwater, and treated wastewater) Pilot or feasibility‐level investigations Design and construction phases of MAR project may include: Collection, conveyance, pipes and pumps from water source to area of use Recharge technique (injection well(s), pumps and motors, Infiltration basin/canals including channels, pumps and motors, bank filtration, and required pumps and motors) Monitoring wells for operational and regulatory management Treatment before injection/infiltration to be compatible with geologic and groundwater chemistry for addressing groundwater and recovered water quality Conventional treatment plant Advanced treatment plant Soil‐Aquifer treatment through Green Infrastructure Treatment after aquifer storage to comply with quality standards for drinking water Third‐party Effects Mitigation through Construction For Off‐site water levels or quality changes Downgradient/downstream water levels or quality changes Water Recovery Wells, Pumps, Motors, and Distribution Lines …”

“…Particular attention in design and operation of MAR projects and their costs and benefits affecting financing need is the investigation, response to and monitoring of water quality for source water, stored water, and recovered water. Addressing water quality factors should be initiated in the planning and then subsequent development phases and carried through operation of MAR projects to meet operating requirements and regulatory compliance (Doremus and Job 2022; McCurry and Pyne 2022). Sources of MAR include excess untreated or partially‐treated surface water and groundwater, stormwater, floodwater, and treated wastewater and may have variability in contaminant concentrations for both regulated and unregulated contaminants, including contaminants of emerging concern, such as per‐ and polyfluoroalkyl substances (PFAS) (Pyne 2005; McCurry and Pyne 2022; Zheng et al 2023).…”

“…Addressing water quality factors should be initiated in the planning and then subsequent development phases and carried through operation of MAR projects to meet operating requirements and regulatory compliance (Doremus and Job 2022; McCurry and Pyne 2022). Sources of MAR include excess untreated or partially‐treated surface water and groundwater, stormwater, floodwater, and treated wastewater and may have variability in contaminant concentrations for both regulated and unregulated contaminants, including contaminants of emerging concern, such as per‐ and polyfluoroalkyl substances (PFAS) (Pyne 2005; McCurry and Pyne 2022; Zheng et al 2023). Geochemical interactions with the geologic matrix and native groundwater and potential aquifer and well screen clogging comprise considerations affecting needs for engineered pretreatment and aquifer storage management that in turn can influence capital and operating costs and then future financing needs.…”