Original Date: 04/22/1996
Revision Date: 01/18/2007
Best Practice : Economy Surplus Power for Wastewater Treatment
Because the Moccasin Bend Wastewater Treatment Plant in Chattanooga is a major user of electricity, it actively strives to cut costs and still maintain high levels of service to City residents and the immediate area. In 1989, the City entered into an agreement with the Tennessee Valley Authority (TVA) to purchase Economy Surplus Power (ESP) from the TVA that would save the City tax dollars and still meet the power requirements for operation of the Wastewater Treatment Plant.
Under this agreement, the City agreed to a baseline of 3000 KW at regular rates and 3000 KW of ESP at greatly reduced rates. Any use by the City over the accepted total usage would carry significant penalties. In addition, the City agreed that the TVA could interrupt (discontinue) the ESP at any time, requiring the treatment plant to cut back to a maximum of 3000KW within five minutes. The City has experienced only two interruptions since 1994, and both interruptions were caused by unexpectedly high demands for electricity, thereby eliminating the surplus available to the City.
The ESP agreement has prompted the wastewater treatment plant personnel to become more cognizant of power usage and install safeguards to adjust processes and monitor use. The plant has also installed two, 35-million gallon equalization basins to handle sewage for treatment during peak requirements.
The savings realized in the first year amounted to $357K to the City, and for 1995 equaled $395K. As further improvements in monitoring and control systems are made at the treatment plant, outyear savings are expected to be even greater.
For more information see the
Point of Contact for this survey.