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Manteca is green leader for treating wastewater

The most eco-friendly wastewater treatment plant in the Northern San Joaquin Valley will be Manteca’s by the time 2020 rolls around.

Not only is the treated water returned to the San Joaquin River meeting the latest standards established by the state for water quality, but within six months or so methane gas — a major byproduct of the treatment process that typically has to be burned  — will no longer contribute to valley air quality issues. That’s because the food waste to fuel project that combines commercial food waste collected by the city with methane gas will be producing compressed liquidized gas to fuel the city’s fleet of two dozen solid waste trucks will be up and running.

That in its self would set Manteca apart from the crowd as it is the only such undertaking in California. It is attracting so much attention through the western states that a gathering of wastewater engineer professionals expected to exceed 60 will be touring the facility later this year. It was declared the California Water Environment Association Engineering Achievement of the Year Award winner for 2018.

Last week the city went a step further. The City Council awarded a design-build contract with Borrego Solar Systems to constrict a solar field project not to exceed $5.5 million in cost. That will result in a fixed-tilt solar photovoltaic system on a 15-acre site that will operate between 1.5 and 3.1 kWp (the peak kilowatt performance of the panels.)

It will end up generating 1 megawatt worth of power. Over the 25-year rated lifetime of the system based on current PG&E electric rates, after recovering the cost of the system through the avoidance of power purchases the city will reduce the wastewater treatment plant’s cost to operate enough to save between $1.5 million and $3.8 million over a quarter of a century. Given that PG&E typically has annual rate increases the actual savings will be substantially more.

Even though the system could easily save several more times than what has been projected over 25 years, the conservative analysis to assure used only current power consumption and assumed PG&E rates would flat line for the next 25 years.

The treatment plant is the city’s biggest energy consumer with an electric bill surpassing $1.5 million a year.

While the food waste to fuel and solar project are cutting edge green projects, both also will save ratepayers green. 

The solar project should allow the city to stabilize power costs to essentially minimize electricity’s impact on future rate increases. The food waste to fuel will ultimately allow for longer life expectancy for the solid waste fleet and eliminate the need for the city to purchase fuel.

The solar field will be installed along the southern fence line and will be the largest such installation in the South County.

To contact Dennis Wyatt, email