Winter 2019

Wastewater Treatment Plant News

In 2012, the Edmonds Wastewater Treatment Plant (WWTP) began a series of projects and initiatives to conserve energy and reduce operating costs. As a result, overall energy consumption and demand use has been trending downward since 2012. By 2017, the overall annual electric consumption was cut by 37%, and overall costs were cut by 41%.
wwtp electrical consumption

Figure 1. Overall electric consumption at the Edmonds Waste Water Treatment Plant has been trending downward since 2012 due to the many energy conservations projects.

Despite the early success of the energy reduction projects, plant operators are now seeing increases in operating costs for the first time since the retrofits. The cost increases are directly related to higher electric rates and a new Redundant Distribution Capacity (RDC) charge. This new RDC charge was put in place in August, 2017 and provides the plant with a second electrical service, which insures the plant always has electricity and can process waste water. The charge is to be phased in over four years to an eventual added cost of $22,140 annually.

While cost increases have raised questions as to the effectiveness of the energy projects, in fact, the projects have lessened the impact of the recent rate increases. The contractor assisting the plant on the projects provided a “Do Nothing Case” estimate, demonstrating that the rate increases would have pushed costs much higher if the energy saving improvements had not been completed. Overall costs would have increased approximately 25%, or around $100,000, per year.

While nobody likes to pay for more service, electrical utilities must increase their generating and transmission capabilities in order to meet growing demand during peak periods. The utility applies a demand charge to help customers support the infrastructure for short-term energy use, such as equipment, wiring, substations, etc. The monthly kW demand rate has increased 21.2% since 2014, from $4.23 to $5.12, and is likely to be a growing expense for the plant moving forward.
energy usage demand costs

Figure 2: The “Do Nothing Case” chart shows that energy costs for the plant would have increased 25%, or $100,000 per year, had energy savings improvements not been completed. The “RDC” costs (blue), “kW costs” (light orange) and “kWh costs” (orange) together add up to the total actual costs to the plant, which were declining with energy use (gray), but began to increase in 2018 due to electric rate increases. Overall, the energy conservation efforts have largely offset the electric rate increases.

The City and WWTP have made efforts to keep rates down by adjusting to these added operational costs. In fact, Edmonds currently enjoys some of the lowest sewer rates in the Puget Sound area, ending up 34th out of 36 cities in a recent survey (LOTT Improvement Plan). These rates are approximately 39% lower than the average Puget Sound area residential customer.
Residential wastewater rate comparisons 
Figure 3. Edmonds enjoys some of the lowest sewer rates in the Puget Sound area, with cities shown in the table for comparison.

Energy-saving projects have been successful in reducing operational costs, enabling the City to keep wastewater rates lower for our utility customers, even as electric rates are increasing for the plant. Additional energy and operational improvement projects are planned, and the City and WWTP are continuously looking into ways to save energy, improve environmental performance and keep costs low.