Construction at the largest public works project in Pima County history is well under way.
The $323 million expansion and upgrade project at the county’s Ina Road Wastewater Treatment facility has begun and remains on schedule in its early stages, county officials said.
The Ina Road project is one component of the larger Regional Optimization Master Plan (ROMP), a $720 million effort to expand wastewater treatment capacity and meet higher water-quality standards.
“That’s the primary driver of this project, it’s regulatory driven,” said Jackson Jenkins, director of the Pima County Regional Wastewater Reclamation Department.
Federal and state water-quality standards mandate that county treatment facilities reduce the levels of nitrogen and other chemicals in treated water before discharging it into the Santa Cruz River or using it for irrigation.
Jenkins said the project is roughly 10 percent complete. It’s expected to be completed in October 2013.
The work would expand the treatment capacity of the Ina Road facility from 37 million gallons daily to 50 million gallons.
The project is one element to the ROMP program, which also includes upgrades to the Roger Road Treatment Facility near Prince Road and Interstate 10. Treatment capacity at the Roger Road plant would shrink from 41 million gallons a day to 32 million gallons.
The county would have an 82-million-gallon daily treatment capacity after the work concludes.
The average person produces roughly 100 gallons of wastewater each day.
A pipeline connects the two facilities allowing officials to divert sewage flows from Roger Road downstream to the Ina Road plant.
Under the ROMP program, a new wastewater facility will be constructed adjacent to the existing Roger Road facility. The existing treatment plant would be decommissioned following completion.
The improvements at Ina Road also will expand the plant’s capability to collect and burn the biogases waste produces. The facility uses the gasses to produce power that helps run the operation.
Ratepayers will pay construction costs through a series of service rate increases. County voters rejected a proposal to use bonds to pay for project.