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Power Plant Water Permit Information

Virginia Pollutant Discharge Elimination System Permit

A power plant is likely to require an individual and/or general VPDES permit. The individual permit would contain limitations for any material that is present in sufficient quantities to lead to a violation of the Virginia Water Quality Standards (9VAC25-260). In the case of power plants, the most likely materials that could do this are various metals and toxic materials contained in the chemicals used for cooling, or biocides that may be used.

A stormwater general permit would likely be needed for construction activities, and long-term stormwater requirements would likely be included in the individual VPDES permit.

Virginia Water Protection Permit

A power plant likely will need a Virginia Water Protection permit for water withdrawal. The VWP permit is Virginia's certification under Section 401 of the Clean Water Act that the applicant's activity or discharge to surface waters will not violate water quality standards or state water control laws. Federal permits also would be needed for discharge of dredge material or fill in a waterway or wetland, or for work or construction in a navigable waterway. Without the VWP permit, the federal permits will not be issued.

For example, a power plant that needs to build a new intake structure would need a Virginia Water Protection permit because of the discharge of fill material that is used to build the intake. The federal permit that is also a prerequisite is the Section 404 permit from the Army Corps of Engineers for the discharge of fill material.

Power plants need varying amounts of water, depending on the size of the plant and the thermo-mechanical processes used to generate electricity and cool the equipment. For example, an 880-megawatt coal-fired power plant may use an average of about 11 million gallons of water per day. The power plant may use cooling towers, in which waste heat is dissipated by converting liquid water into water vapor. The water vapor is "lost" to the atmosphere and does not return directly to the river from which it was taken. The term applied to the water that is converted to water vapor is "consumptive use." Power plants that use cooling towers usually have high rates of consumptive use, about 80 percent of the amount of water that is withdrawn.

Another common cooling process is called "once-through cooling." Water is taken though the power plant one time and is used to take away waste heat. This process warms up the water but returns almost the same amount to the stream as was withdrawn. With this process, consumptive use rates are low.

However, there are two main concerns with once-through cooling. It can heat up the stream that receives the discharge and harm the aquatic life - this would be a violation of the water quality standards for temperature. The second concern is that the fish eggs, fish larvae and small aquatic organisms can be damaged or destroyed if they are caught on the intake screen or drawn into the cooling system. For these reasons, new projects generally do not use once-through cooling.

Some power plants use relatively low amounts of water if they are small or use an air cooling process. Different types of fuels require different amounts of water.

To obtain a Virginia Water Protection permit, an applicant must file a joint permit application with the Virginia Marine Resources Commission. The joint permit application form serves as a permit application to DEQ, VMRC and the Army Corps of Engineers.

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Virginia Department of
Environmental Quality
P.O. Box 1105
Richmond, VA 23218
(804) 698-4000

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