Gregg Eckhardt is guest blogger to The Water Voice and a Senior Resource Analyst for San Antonio Water System.
Today, attendees at NACWA’s National Clean Water Law Seminar in San Antonio, Texas glimpsed the utility of the future in a luncheon address by Steve Clouse, Senior Vice-President and Chief Operating Officer of the San Antonio Water System.
Much attention has been focused recently on how municipal clean water agencies are increasingly innovating beyond the four corners of the Clean Water Act to enhance their environmental performance, benefit their communities, and improve their financial picture. Many of these innovations are focused on new, cutting-edge practices such as energy production, water reuse, green infrastructure, and resource recovery. The San Antonio Water System is among the leaders in pursuing these “utility of the future” concepts.
Clouse outlined San Antonio’s three-step initiative to move beyond a 20th century regulatory compliance paradigm to one that focuses on resource management, where the marketplace drives quality and disposal of water recycling residuals.
In 2010, San Antonio achieved the milestone of being the first United States utility to beneficially reuse all process residuals, including water, biosolids, and gas. Clouse explained that it didn’t happen overnight; in fact, it was almost 20 years in the making.
Step 1 was to invest in large capital projects to interconnect and centralize treatment operations. Five of San Antonio’s eight treatment plants were eliminated, and biosolids processing was consolidated at a single facility.
At the same time, discharges of effluent were de-centralized, with four new discharge locations constructed to enhance baseflow in area streams for environmental improvements. The new discharges were a component of the nation’s largest direct recycled water distribution system – today, almost all the dry weather flow in the world famous San Antonio River Walk is recycled water. Along the pipeline route to the new discharges, 68 commercial users receive tertiary treated effluent for irrigation, manufacturing, and industrial processes.
Step 2 involved establishing a marketplace for other residual products and capturing unique new opportunities. SAWS built one of the largest biosolids composting operations in the nation and partnered with private contractors for further expansions to beneficially reuse up to 140,000 tons per year of biosolids that were previously landfill disposed. Up to 900,000 cubic feet per day of methane-rich digester gas is now processed and sold on the open market instead of flared off. Treatment plant buffer lands were leased for construction of Texas’ largest solar farm, now producing 20 megawatts.
Clouse noted that sustainable and environmentally responsible residual management strategies and fiscal responsibility are not mutually exclusive; in fact, they have the same end point. All of SAWS strategies resulted in reduced costs, new revenue streams, and conservation of potable water supplies.
Clouse wrapped up by explaining Step 3 – becoming the utility of the future means continuing to move toward new opportunities. SAWS is currently conducting a feasibility study for thermal hydrolysis of digester sludge to reduce solids volume and increase gas available for sale. Other strategies under consideration include injection of high-strength organics, energy capture from effluent discharges and waste heat sources, and in-line hydropower development in the water distribution system. Although Clouse focused on wastewater initiatives, SAWS has also pursued innovative water supply projects, including one of the nation’s largest Aquifer Storage and Recovery projects, and it is currently constructing a brackish water desalination plant.