Manteca is working to extend its string of five straight years without an increase in sewer rates.

The latest strategy is to upgrade existing blowers with high-efficiency turbine blowers used in the treatment process of wastewater at the city’s plant along with other energy efficiency projects.

When completed, the city will be able to recoup the $426,256 and then some over the coming years as energy use will decrease significantly. The city currently spends nearly $1.2 million a year on electricity to run the wastewater treatment plant.

The savings potential was indentified during an audit under the California Wastewater Optimization Program sponsored by PG&E.

The council on Tuesday is expected to approve an agreement with Hewitt Engineering to provide engineering services for the project. The council meets at 7 p.m. at the Civic Center, 1001 W. Center St.

Staff is also exploring the possible establishment of a solar energy farm to further reduce the use of electricity at the wastewater treatment plant. That plan could see solar panels placed over the adjoining Big League Dreams sports complex’s 500-space parking lot as shade structures.

Original residential sewer rates were supposed to go up from $39.50 a month at the end of 2009 to $43.30 in 2010. That adopted increase was based on ongoing operations and maintenance where the biggest cost factors are labor, pipeline replacement, and electricity.

A move to reduce staffing as well as the compensation of existing city employees by roughly 20 percent on average  in response to a big retreat in property taxes caused by nearly a 60 percent drop in property values triggered by the foreclosure crisis has allowed the city to delay scheduled rate hikes for five straight years.

Even with the postponement of rate hikes the city has been able to undertake a number of capital improvement projects designed to replace aging infrastructure due to their conservative approach to building and managing reserves for such purposes.

While water and sewer are enterprise funds supported by fees and not general taxes, city leadership extended its cost-cutting and efficiency efforts to all operations. They also needed to absorb losses triggered by people being unable to pay utility bills.

Postponing rate hikes has resulted in the average Manteca residential sewer user avoiding more than $600 in sewer charges since 2009.