APPLYING AQUIFER STORAGE RECOVERY TECHNOLOGY TO ADDRESS WATER RESOURCE CHALLENGES IN DIFFFERENT COASTAL PLAIN SETTINGS

Aquifer Storage Recovery (ASR) technology is becoming an increasingly important groundwater management tool in the southern Atlantic Coastal Plain. Groundwater in the coastal aquifers of the Carolinas is the predominant source of water supply for public, agricultural, and industrial purposes, and its sustainability is threatened by increasing demand, saltwater intrusion, and limited freshwater recharge. ASR provides the opportunity for water users to store treated drinking water and manage water resource demands that often vary seasonally. In addition, ASR has many secondary benefits, such as the potential to reduce disinfection by-products during storage, improve regional groundwater levels during seasonal to long-term storage periods, and locally reduce the effects of saltwater intrusion. The local hydrogeology is a major consideration for the implementation of ASR projects. The development of sand aquifers as storage zones, such as those contained in the Cretaceous Aquifer System, requires great care to avoid potential well-plugging issues during recharge/recovery operations. Local aquifer-matrix geochemistry can dramatically affect the condition of the recovered water after storage, and pre- or post-treatment measures may be required to make the project successful. Clays naturally occurring in aquifer-storage zones can also present problems to ASR recovery operations. Regulatory requirements can be dramatically different for ASR programs in different states and/or groundwater districts. We present several ASR projects in the Coastal Plain of North and South Carolina in different hydrogeological and regulatory settings. These projects have had their own challenges and secondary benefits, although the primary goal for each is seasonal storage. Hilton Head Public Service District, Hilton Head, South Carolina has implemented an ASR project and has gone from a feasibility study to the recovery of ASR water to the distribution system in less than 2 years time. Orangeburg Department of Public Utilities has also brought two very productive Cretaceous Aquifer System ASR wells into operation in a relatively short timeframe. We will present lessons learned from several projects and propose new ways of streamlining development and lowering costs.