Presentations 2016

Summary of Managed Aquifer Recharge Concepts and Planning Methods

Kleinfelder Inc

https://www.youtube.com/watch?v=A3p6fhz8y20&index=3&list=PLZC-5vj9_JAYLqpKMAUN0py-DvCwpslyC

Managed aquifer recharge (MAR), also known as water banking, consists of water management methods and techniques - using treated or non-treated water - to recharge an aquifer, or water bearing zone of sediments, using either surface or subsurface (i.e., via wells) recharge methods. The stored water is available for use in dry years when surface water supplies may be low. Other possible benefits of a properly managed water bank may include making water available for sale, lease, or exchange with other water users for regional water supply sustainability and/or mutual benefit.Surface recharge systems are more likely to work in situations where soils are permeable from the ground surface to the water table, and where adequate land area is available at reasonable cost to accommodate the recharge facilities. Solids that accumulate at the surface are periodically removed following a series of wet-dry cycles to maintain the long-term infiltration rate. Where low permeability soils are present between ground surface and the water table, or where land availability at reasonable cost is limited, surface recharge may not be viable (Pyne, 2005). It must be realized that a MAR system is an engineered system requiring technical inputs from multiple disciplines. Mechanical and process engineering is just as important as water quality modeling and hydrogeologic conceptual modeling inputs for successful design and operations of MAR technology. MAR technology has evolved and supported projects in California for over 40 years, with several long-running projects still in existence and serving as industry standards. Several examples of these long-running successful projects are the Water Replenishment District of Southern California, Orange County Water District, Kern County facilities, and the Santa Clara Valley Water District operations. These successful projects are presented in this paper as examples of surface water-applied aquifer recharge and groundwater-applied aquifer recharge methods as the mechanisms to deliver, store or bank, and extract applied water using a groundwater system. When developing a MAR project, experience has proven that well-researched and planned projects that have well-defined objectives, a solid conceptual model, and proper levels of pilot testing have the best chance of achieving a successful, long-term operation. A project’s conceptual model should include at a minimum a thorough understanding of the site’s hydrology, hydrogeology, mixing water geochemistry, and engineering geologic factors such as soil mechanics and land surface expressions of aquifer response to inflation or deflation. Other technical issues involve the above-ground water delivery system, and logic control systems that run the designed system, including flow control valve technologies that regulate injection and extraction rates. Plugging or clogging is a reality of any system, but a well-defined and executed asset management program can alleviate the severity and frequency of these realities and protect the asset’s investments.Regulatory issues must be confronted and incorporated into project planning. Historical experience has provided some key lessons learned, which are worth incorporating in pre-project planning and design to ensure successful MAR operations. A well-planned public outreach program that informs and engages the community to be served by the MAR project is necessary to the success of such projects; economic considerations can be part of this effort to show the long-term benefit to the community. Recent legislation in California has moved the State toward a more strict and comprehensive policy regarding groundwater management. These new regulations and laws will have particular impact on groundwater basins that have been defined by the California Department of Water Resources as medium or high priority basins. The legislation, signed into law in 2014, creates a framework for sustainable local groundwater management, and allows local agencies to modify groundwater plans to their regional needs. As more counties and local agencies have to comprehensively manage large multi-jurisdictional groundwater basins, more opportunities for MAR/groundwater banking projects should emerge. These projects will have to be planned, designed, and operated by well-trained, experienced, multi-disciplinary teams of professionals.