Santa Rosa buying Petaluma hay ranch as treated waste disposal site

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.

In recent years, due in part to increasing regulations aimed at protecting endangered tiger salamander habitat in the Santa Rosa Plain, the city has 600 fewer acres available to it than it once did for its land application program, which also utilizes several sites in southern Sonoma County.

The restrictions are expected to tighten further.

Farmers switching to organic crops are not allowed to fertilize with biosolids because of USDA organic guidelines. Prinz calls that an unfortunate and unscientific prohibition that unnecessarily restricts the use of a valuable natural resource and makes organic products less sustainable.

The search for lands to lease or purchase comes amid increasing competition among Bay Area cities for suitable agricultural properties where solid waste from sewage treatment can be disposed. Landfills, which currently accept about 6 percent of biosolids annually, will no longer accept such organic material by 2025, eliminating another disposal option. The city has studied other potential solutions, including expanded compost operations and turbocharging its digesters to break down the biosolids further. But those are far more expensive options, Prinz said.

Earlier this year, the city approached Tom Atwood, a Glen Ellen horseman, about purchasing his Lakeville Avenue property, which is located just north of Sonoma Horse Park, a posh equestrian center along the Petaluma River.

Atwood has owned the property for about four years and had hoped to move his Red Bluff horse operation to the site, but his plans changed, he said. He leases most of the property to a farmer who raises high quality oat hay.

Biosolids from other communities have been applied to the land since about 1998, he said, noting that he’s told they increase hay production by 25 percent. The sale is expected to close escrow next month. If completed, the city says it expects to continue hay farming operations on the property.

“I’m happy that it’s going to stay in agriculture,” Atwood said.

You can reach Staff Writer Kevin McCallum at 707-521-5207 or kevin.mccallum@pressdemocrat.com. On Twitter @srcitybeat.