SD15 - The Feasibility of Using Desalination to Supplement Drinking Water Supplies in Eastern Virginia
The 2003 Virginia General Assembly Session passed the Senate Joint Resolution No. 381 that requested the Virginia Water Resources Research Center at Virginia Polytechnic Institute and State University to study desalination issues as part of a strategy to meet the Commonwealth's future drinking water needs.
The major goal of this report was to investigate the feasibility of implementing desalination technologies in Virginia to supplement drinking water supplies. For the purposes of this report, desalination (or desalinization) is defined as removing salts from brackish water and/or seawater to produce potable water. Issues critical to implementing desalination technologies are: type of desalination technology, environmental concerns and regulations, energy availability and cost, availability of water source for desalination, and cost to the customer. This report provides an overview of those issues in six chapters. The synopsis for each chapter, the rationale for implementing desalination technologies in eastern Virginia, and the report’s recommendations are provided below.
Chapter 1 is an introductory chapter. It describes several options for meeting future water demand, defines salinity and desalination, and provides a synopsis of chapters that follow. The objective of Chapter 2 is to introduce the available desalination technologies. The chapter presents an overview of current and futuristic desalination technologies to treat brackish and saltwater to produce potable water. It also discusses the applicability and the limitations of the technologies.
The objective of Chapter 3 is to provide an overview of environmental issues related to desalination. Environmental concerns are a major factor in the design and implementation of cost-effective desalination technologies. Major environmental concerns include issues related to brackish groundwater withdrawal, surface water intake, disposal of brine and other water treatment residuals (called concentrate), and ecosystem effects.
Desalination is energy-intensive, because energy is needed in various stages of desalination. Energy consumption directly affects the cost-effectiveness of using desalination technologies. Chapter 4 presents energy types, use, methods of conservation, and the potential use of renewable energy resources for desalination. Some of the information provided in this chapter may not be applicable to today’s Virginia energy issues. However, the chapter provides a comparison between costs associated with various energy sources as applied to desalination worldwide, and can be used as a reference for future energy development and use in Virginia.
Chapter 5 focuses on issues that relate to the feasibility of implementing desalination in eastern Virginia. A major assumption of this study is that the greatest potential for implementing desalination exists in the counties and cities in eastern Virginia within close proximity of the Chesapeake Bay and the Atlantic Ocean. Many localities in eastern Virginia project significant population growth that will affect future water demand. Estimates from this study show that projected population increases (using 2000 population data as a reference) will translate to an additional drinking water demand of approximately 20 MGD (2010), 50 MGD (2020), and 75 MGD (2030) in eastern Virginia. Chapter 5 discusses feasibility issues including potential water resources for desalination, environmental effects of desalination, required permits and regulations, availability of energy resources, and potential costs. The chapter also presents a description of existing desalination plants in eastern Virginia and the rationale for future desalination plants.
Chapter 6 contains major conclusions and recommendations of the report. A comprehensive database of water resource inventory for eastern Virginia is not available. Based on available information, a significant need exists for using desalination in eastern Virginia:
1. The Hampton Roads area is the home of one of the largest port facilities in the country and hosts a major military complex. As a result, the area has experienced rapid population growth that has strained local water supplies. Because of the population growth and the difficulty in developing new water sources locally, water shortages in the region have become commonplace over the last two decades. Water restrictions resulting from water shortages have occurred in every dry period since 1976.
2. Because of withdrawals from Coastal Plain aquifers, groundwater levels have declined in the region as deep as 160 feet below the sea level near major pumping centers. Groundwater levels in the interior portions of the Middle Potomac (Southampton County), in the Yorktown-Eastover aquifer (Southampton County), and Chickahominy-Piney Point (King William, Caroline, King and Queen counties) are approaching critical condition.
3. Because of withdrawals from Coastal Plain aquifers, groundwater levels have declined in the region as deep as 160 feet below the sea level near major pumping centers. Groundwater levels in the interior portions of the Middle Potomac (Southampton County), in the Yorktown-Eastover aquifer (Southampton County), and Chickahominy-Piney Point (King William, Caroline, King and Queen counties) are approaching critical condition.
4. Major cities in eastern Virginia (Chesapeake, Virginia Beach, Norfolk, Newport News, Portsmouth and Suffolk) are within the Groundwater Management Area. From a regulatory standpoint, the stress on the aquifer system is such that the DEQ may have to start denying permit issuance in some areas of the Ground Water Management Area.
5. Virginia Beach, the largest city in the area has very little fresh groundwater available to meet current or future needs. Virginia Beach relies on interbasin transfer from the Lake Gaston pipeline. If the pipeline is disrupted for any reason, it will have major consequences for Virginia Beach and the region.
6. The Virginia Department of Health has advised the City of Newport News (Newport News Water Works) and James City County for the need to develop additional sources of supply, as the current demands have exceeded the “trigger level” contained in the Commonwealth of Virginia Waterworks Regulations for such action. To meet future demand, brackish groundwater or other saline waters will be the only available local resources.
7. Portsmouth and Norfolk, the older cities in the area, developed the limited surface water supplies before the newer cities of Chesapeake, Suffolk, and Virginia Beach came into existence. Portsmouth and Norfolk have sufficient water supplies to meet their current needs and supply their surplus water to Virginia Beach and Chesapeake. However, the surplus is not adequate to meet the needs of these cities where much of the population growth is occurring.
8. The proposed King William Reservoir project will supply only up to 60% of the lower Peninsula’s future water needs. Desalination of brackish groundwater is considered as potential way to supplement a portion of the additional demand.
9. Construction of additional reservoirs in eastern Virginia is less likely because of environmental concerns, high cost, and difficulty in purchasing the needed land.
10. Parts of New Kent, Charles City, Hanover, Henrico, and Petersburg are situated within the Eastern Virginia Ground Water Management Area. These localities will compete with Hampton Roads area and Middle Peninsula for available water resources in the region.
11. Accomack and Northampton counties rely solely on groundwater to meet drinking water needs. Future economic growth in the area depends of availability of alternative source of water.
Desalination cannot be considered as a stand-alone measure to meet increased water demand for public water supplies. Desalination should be considered as a viable component of an overall water supply management that includes all available sources of water (fresh and impure) and all uses of water (public water supplies, agricultural, industrial, etc.). Technologies are available for desalination of brackish and seawater. These technologies are implemented worldwide, and further research and development of more cost-effective desalination technologies are underway. Advanced brackish water desalination technologies are already implemented in the Hampton Roads area with acceptable cost to the public. Therefore, technology is not a factor in implementing desalination in eastern Virginia. However, there are issues related to availability of water sources, institutional needs, and ecosystem impacts that need to be addressed.
Water Resource Inventory Need
At present, a comprehensive and reliable database of surface and groundwater resources in eastern Virginia is not available. It is important to understand that brackish and saline groundwater resources are not disconnected from fresh surface and groundwater resources. Extraction of brackish water will have effects on adjacent fresh groundwater reservoirs, and ultimately surface water resources as well. A better inventory of surface and groundwater resources is needed for optimal site selection of desalination plants.
Recommendation. Legislative guidance and state government leadership is needed to develop a comprehensive database of available water resources in eastern Virginia to be followed by a viable regional water supply and allocation plan based on the scientific evaluation of existing water resources and the potential for developing impure water sources such as saline water.
There is a significant need for regional collaboration for successful implementation of desalination and to meet future water demand.
Recommendation. Legislative guidance and state government leadership is needed to form a regional utility task force that will coordinate activities of numerous utilities in the region and to develop a strategic plan for future use of large-scale desalination technologies in eastern Virginia. The task force should determine where the needs are and identify potential sites to locate desalination facilities.
Recommendation. Legislative guidance is needed to form an inter-governmental task force that will coordinate and expedite permit reviews between various federal and state agencies for the implementation of future desalination plants.
Recommendation. Energy costs are a major factor in the production cost for desalination plants, particularly when using high salinity waters such as tidal and seawater. There is a need to develop a mechanism for enhanced cooperation between water utilities and power companies to make existing and future desalination plants more cost-competitive.
Research Needs for Ecosystem Management
Less is known about various effects of desalination plants on receiving waters and coastal ecosystems. Research is needed to provide science-based information that can facilitate science based permitting and developing regulatory guidelines.
Recommendation. Legislative action is needed to provide funds that can support research for developing environmentally sound desalination practices. Research is needed to address ecosystem impacts such as effects of water withdrawal, water intake structure and brine disposal; and cost effectiveness of various brine disposal and management technologies, such as Zero Liquid Discharge and brine reuse potential.