Flex Your Power Case Study: South Tahoe Public Utility District

In 2001, South Tahoe Public Utility District (STPUD) initiated the Wastewater System Energy Evaluation to demonstrate how operational and process modifications could
be made to lower the demand and energy costs for various facilities within the wastewater system. The evaluation highlighted several areas for improvement, including the dissolved oxygen (DO) system and pump efficiency. For its efforts, STPUD realized total energy cost savings of $198,975, and energy usage savings of 2,888,800 kW.

The overall purpose of the energy evaluation was to demonstrate how operational and process modifications could be made to lower the demand and energy costs for various facilities within STPUD. More specifically, the goal was to reduce electrical energy consumed at the plant and to reduce SPPC billings.

South Tahoe PUD's energy conservation and efficiency programs in 2001 delivered annual energy savings of 12,710,700 kW and annual financial savings of $184,475. The estimated energy and cost savings for each program were as follows:
- Automated DO Control System:109,200 kW and $9,275.
- Limited peak discharge (not yet completed): 2,024,100 kW and $69,100.
- VFDs on pump and pump replacement: 498,600 kW and $33,100.
- VFD at A1 Tahoe Sewage lift system: 78,800 kW and $4,700.
In recognition of STPUD's success in reducing energy costs at its wastewater treatment plan, the CEC, in partnership with industry professional associations and electrical utilities, selected STPUD as a demonstration site for other plant managers under the Energy Efficiency Showcase project.