A year from now, Petaluma?s sewage will begin a transformative journey ? through a new treatment plant and back into town as a new water source for summertime irrigation of parks, playing fields and landscaping.

After almost three years, the facility needed to make that possible is 90 percent finished, with the bulk of heavy construction over and start-up operations on the horizon.

Workers are being hired for the Ellis Creek Water Recycling Facility ? the Lakeville Highway plant?s official name ? and this fall the city will connect the existing sewer system to the site.

Once operational, the plant will begin pumping out recycled water that can be used to irrigate crops, lawns and parks, saving drinking water.

?The exciting part of this facility is that it is providing a new water supply for the city,? said Margaret Orr, the city?s project manager for the new plant. ?Tertiary water is the only form of new water in California.?

Petaluma?s plant will clean sewage to the highest level called for in state health codes ? tertiary water ? allowed to be used for all kinds of activities, except human consumption.

Like Santa Rosa?s sub-regional sewer treatment plant and hundreds of others throughout the state, Petaluma?s plant will make wastewater clean enough for different uses. In addition to being used at city parks, Petaluma?s recycled water will be sold to farmers, golf courses and business parks, and released into the Petaluma River during the winter months.

Even the treatment plant itself will tap into the recycled water produced there for firefighting, irrigation and other non-drinking uses.

Once online, the plant will produce 464 million gallons of recycled water a year ? enough to offset the water use of 1,400 single-family homes and expand the current distribution of recycled water beyond Rooster Run Golf Course and some south Sonoma County farms.

And although the plant was designed to accommodate Petaluma?s growth through 2025 ? the horizon year of the new General Plan ? officials see it as a long-term staple of the sewer system.

?Hopefully, this is a hundred-year site for the city,? Orr said.

She has overseen construction since work began in October 2005, capping a 17-year decision-making process by city leaders about how to replace the aging Hopper Street plant. When debate about a new plant began in 1988, the Hopper Street site was 50 years old; today it is 70.

But when the current plant design was approved, progress came quickly. The $110 million plant is running only 3 percent over the original budget ? about $3.3 million ? and two months behind the original April 2009 completion date.

The City Council reviews the budget and schedule changes for the plant each month and has signed off on the work so far. The schedule delay is due primarily to the heavy winter and spring rains in 2006, inundating the site just a few months after grading work began.

Since then, two consecutive dry years have allowed the contractor to play catch-up and keep to the June 2009 completion date, said Mike Ban, the city?s director of water resources and conservation.

?We spent a lot of time getting ready for this project, and I think that planning has paid off,? Ban said. ?We try to be prepared for anything.?

The current plant is often plagued by equipment and odor problems, something officials are looking forward to avoiding with the operation of the new plant.

More advanced odor controls are in place where sewage first enters the Ellis Creek plant ? but as a precaution, designers located that headworks building as far as possible from office buildings bordering the site.

After debris and grit are removed there, the wastewater flows to two massive, three-million-gallon oxidation ditches and a series of ponds and basins for treatment. Nutrients, metals and toxics are removed during the process ? which includes disinfection by ultraviolet rays ? making the wastewater clean enough for re-use.

State regulations prevent disposal of treated wastewater into the Petaluma River during the summer due to fish habitat concerns, so using that recycled water to offset high water demand during the summer season was a logical step, Orr said.

In the winter, when water demand is low, recycled water can be released into the river.

?It?s a great balance for us,? she said.

The bulk of plant construction is taking place on the Lakeville Highway side of the 262-acre site, leaving enough room between the large concrete formations and the river for a wetlands area and trails that will connect to the existing Shollenberger Park pathways.

When viewed from above, the trails and wetlands ponds will form the image of the native salt marsh harvest mouse, a feature designed by artist Patricia Johanson.

(Contact Corey Young at corey.young@arguscourier.com)


What: A public tour of the sewer plant, followed by a Q&A and refreshments.

When: 9 a.m. Saturday, Aug. 2.

Where: Entrance to site is through the cul-de-sac at 3890 Cypress Drive.

More info: Call Michelle Ortiz at 776-3682.