Some cutting-edge changes are being considered for the city’s Materials Diversion Facility.
On Tuesday, the Napa City Council received a presentation on the Napa Renewable Resources Project to help the city reach its goal of diverting 75 percent of waste from the landfill by 2020 and meeting new regulations and standards.
In 2011, about 63 percent of the city’s waste was either recycled or composted.
Materials Diversion Administrator Kevin Miller presented five potential projects that could reduce the facility’s greenhouse gas emissions by 93 percent. “We’re trying to be proactive in all of this and not reactive,” he said.
In the next three to five years, Miller said the city will be required to have an updated stormwater treatment system at the facility, located south of the Napa County Airport, and will need to revamp open-air composting.
The cost of updating the stormwater system could range between $1.5 and $3 million, Miller said.
In the same time frame, the facility will need to change the way it composts, moving organic materials from outdoor piles to covered and contained bunkers, Miller said. That upgrade, costing between $6 million and $8 million, would not only better contain odors, but also prevent potential pollutants from seeping out.
“Using a covered bunker system for composing will help reduce the impacts of stormwater run-off by keeping rainwater isolated from the composting process itself,” Miller said. “This means less potential of pollutants entering stormwater.”
Napa Recycling and Waste is in the midst of a commercial food scraps composting program and hopes to eventually accept food waste from the public, which would increase the need to contain odors and pollutants from the composting facility, Miller said.
Miller said there are two or three other, optional upgrades the city could make to the city-owned facility to further reduce waste and increase sustainability.
One is an advanced composting process called anaerobic digestion, which composts materials at a high temperature in the absence of oxygen. The process is fully enclosed and produces methane, which is collected and converted to energy that can be used to power the facility and run waste collection vehicles.
“It’s the ultimate sustainability model if we can figure out a way to get there,” Miller said of the technology that could require an initial up-front investment of $7 million to $9 million.
Miller also suggested finding the means to establish a biomass plant, which he said has the potential to produce enough energy to not only meet current and future energy demands at the diversion and recycling facilities, but create a surplus large enough to power 200 homes annually.
A biomass plant, which could cost between $6 million and $7 million to establish, would take large wood debris and scrap construction lumber, which the city currently transports to a facility an hour away to be burned, and convert the waste to gas, Miller said. A second byproduct of the process is biochar, which can be sold by the pound as a fertilizer supplement.
In the coming years, Miller expects a steep increase in the amount of energy used at the facility because the state may require all vehicles be electric, and the new composting methods would require more energy consumption. If biomass technology were established in the south Napa facility, the energy produced would cover current and future needs.
As a “Plan B,” Miller proposed the installation of solar panels on the roofs at the materials diversion facility. This would cost between $1 million and $1.5 million.
When the facility receives a new roofing this summer, it will be made “solar ready” in the event the council chooses to go that route, he said.
Miller said there are various capital reserves in the solid waste fund that could potentially be used to get some improvements off the ground. Some rate and fee increases could also be pursued and borrowing is an option.
He said staff are pursuing grants for the upgrades.
The council is expected to review Miller’s proposals in the coming months.
“We all know we’re going to be facing some of these upgrades,” Councilman Peter Mott said. “Also, I think it’s the right thing to do. We want to have a state-of-the-art facility.”
City staff are moving forward with studies to meet the California Environmental Quality Act, which has bearing on some proposals.