Every year, Napa County produces 11.3 million gallons of a liquid not nearly as cherished as its wines – and with no nearby place to dispose of it.
Local sanitation officials say nearly 43,000 gallons of wash water, wine lees, grape skins and other detritus from Napa-area wineries end up in tanker trucks, on average six or seven each working day. Bypassing the local wastewater treatment centers, the trucks make the 42-mile run to Oakland, where a single sewage plant processes the wastewater from winemakers across the Bay Area – and a broad swath of California extending to the North and Central coasts.
In a report published last month, the Napa Sanitation District has begun grappling with how it might begin handling winery by-products at its own plant in south Napa – and deal with the higher costs officials admit nearly any alternative would pass on locally.
“If cost weren’t an issue, you would want to reduce the environmental cost of trucking that waste,” Jeff Tucker, the sanitation district’s director of administrative services, told board members Wednesday. “But cost is a factor, and we need the best solution that meets wineries’ environmental and economic needs.”
Since the early 2000s, the expedient path for wineries in Napa and much of Northern California has been to the Oakland treatment center, where the East Bay Municipal Utility District has long used excess capacity to soak up waste from wineries in the Bay Area and beyond. Much of the East Bay district’s plant’s capacity originally was built in the 1970s to handle wastewater from fruit and vegetable packers, only to fall into disuse with the Bay Area’s increasing urbanization.
The wastewater produced by winemaking falls into an awkward middle ground of treatment. Too thin to be broken down alongside fats and oils, yet too dense to be mixed with ordinary wastewater, it does not easily fit the normal processes for removing or breaking down contaminants, officials say.
Any plan to treat winery waste within the county, Tucker said, must conquer the East Bay district’s heretofore unbeatable price advantage. Customers hauling such waste to the Oakland plant –which handles winery by-products separately from other waste products – pay fees totaling 12 cents per gallon, a price Napa Sanitation staff admits is nearly impossible for any local facility to match.
The Napa Sanitation report floats several options for processing local winery waste. Possibilities include setting up a pretreatment center to reduce its strength, building new digesters especially for winery by-products, or channeling wastewater into its own plant’s oxidation ponds (and adding more aerators) to speed processing.
However, district staff warned many of the alternatives would require multimillion-dollar upgrades, require land for new digesters or other additions, and require charging higher rates than the Oakland plant. Adding enough digester space for all Napa’s winery wastewater, for example, could cost Napa Sanitation more than $25 million, the study suggested.
Moreover, too small an increase in local sewer capacity could leave the district struggling to process winery waste and serve other customers at the same time – especially during the fall crush season, when the volume of winery waste products can double.
“We cannot afford to take up a substantial amount of our own capacity just for our wineries, or else we’ll need substantial space to build up capacity,” board member Charles Gravett said at the Wednesday meeting.
In the report, district officials predicted wineries would need to make a long-term financial commitment to deliver their wastewater to Napa Sanitation for any upgrade plan to succeed – perhaps by creating a property assessment district to pay for debt service, in exchange for cheaper per-load fees.
The sanitation district may take up the issue again with local winery leaders present, but not before year’s end, Tucker said after the meeting.
Regardless of the district’s timetable, though, Jason Holley, the public works director of nearby American Canyon, said that city would offer it support for any proposal that can cut heavy-vehicle use on its main route.
“We have our own concerns in American Canyon: more trucks leaving the county with a product generated in the county, and all those trucks taking Highway 29,” said Holley.