Kevin McCallum, THE PRESS DEMOCRAT
Santa Rosa is buying a Petaluma pasture to make sure it has enough places to put people’s processed poop.
The city is close to acquiring a 235-acre Lakeville Highway hay ranch so it can use the property to spread a byproduct of the wastewater treatment process known as biosolids.
The approximately $2 million deal, which was advanced by the Board of Public Utilities Thursday, highlights the pressures the city faces in finding affordable ways to recycle waste in an era of increasingly stringent environmental regulations.
Santa Rosa recycles its wastewater to irrigate crops and produce geothermal energy at The Geysers, the latter solution costing the city $205 million to build while earning engineering and sustainability awards.
But less known by the general public is what happens to the 26,000 tons of thick black sludge that remains behind annually after the main treatment processes are complete.
That’s enough to “fill the entire playing field of AT&T Park eight feet deep every year,” said Mike Prinz, director of subregional operations for Santa Rosa Water.
More than a third of it is mixed with green waste like chopped up leaves and grass clippings to make high-quality compost, most of which is sold to local farms, vineyards and landscaping companies.
A far cheaper option has long been to apply the nutrient-rich material, which has the consistency of wet coffee grounds, directly to farmland as fertilizer.
Because the waste goes through an extra 21-day digestion process to capture methane to power the Llano Road treatment plant, it has far fewer pathogens and odors than the byproducts of other treatment plants.
Nevertheless, there are strict rules about how it can be applied, including that it be disked into the soil, set back from creeks and public access restricted after application.