Palo Alto has a rich history of discord and disagreement when it comes to disposing of the city's organic waste, but if there is one project that brings all the sides in the debate together it's the city's plan to retire the incinerators that have been burning sludge in the Baylands for more than 40 years.
On Monday night, the City Council is expected to approve a $2.3 million contract with a firm that would design the city's new sludge-dewatering and haul-out facility. Once in place, the facility would allow the city to send its dried-out sewage sludge to another waste plant that would either compost it or process it into an agricultural product, according to a staff report.
The $12 million dewatering plant would allow the city to retire its incinerators, which are notorious for emitting high levels of greenhouse gases and producing hazardous ash that the city must export every week to Kettleman City.
Eventually, the city plans to also build an anaerobic digester near the sewage plant that would convert sludge into energy. Food waste would later be added to the materials processed at the new plant.
Palo Alto has also been exploring options for composting, though that effort became less urgent last October, when the city received several proposals from private companies and determined that its current practice of exporting local yard-trimmings would be much cheaper.
The design process for the dewatering and haul-out facility is scheduled to take about 14 months and be completed by around March 2016, according to a new Public Works report. Construction is expected to take about three years and be completed in July 2019, at which time the incinerators would be retired.
Palo Alto is currently one of only two agencies in the state that uses incinerators (Central Contra Costa Sanitary District is the only other one). The City Council in May wholeheartedly supported the retirement of the incinerators.
The new report notes that the design contract is a "key step in ... paving the way for the future anaerobic digester system that will produce local, renewable energy that can run the RWQCP (Regional Water Quality Control Plant)."
The new sewage-treatment equipment will include three large tanks known as gravity thickeners with sludge pumps; a scum concentrator (a tank with heating equipment and a pump); three 2-meter-wide belt-filter presses that will dewater the incoming sludge; and a conveyance system that will bring the dewatered sludge cake into three elevated storage bins. According to the preliminary design report for the new facility, each of these bins would have a "discharger" allowing the dewatered sludge to be removed from the bins and conveyed by a rubber chute into hauling trucks.