San Diego is approaching a critical juncture. It is the only remaining California city that does not treat wastewater to secondary standards before discharging into the Pacific Ocean, and its five-year waiver – allowing the Point Loma Treatment Plant to discharge up to 240 MGD (908,400 m3/d) of advanced primary treated municipal wastewater into the ocean – is set to expire on 31 July 2015. An application for a new permit waiver takes about one year to prepare and must be submitted by January 2015.

According to this schedule, the preparation process should start this coming January. However, most observers, including the California Coastal Commission and the state’s environmental community, object to the city being granted another waiver.

The city’s 2012 Recycled Water Study found that direct or indirect potable water reuse could avoid the estimated $3.5 billion capital and financing cost to upgrade the treatment plant to meet secondary discharge standards while providing a competitive new water supply option. The Study outlined a concept that would divert 100 MGD (378,500 m3/d) of wastewater flow upstream of the Point Loma Plant for advanced treatment and potable reuse.

San Diego has a history of having stakeholder groups fill the leadership void with regard to potable reuse. When former Mayor Jerry Sanders was unsupportive of potable reuse, environmental, business and labor groups formed the Water Reliability Coalition and successfully advocated to keep potable reuse studies and a demonstration MF/RO/UV reuse project moving forward.

Now, as the city struggles without a Mayor or Public Utilities Director, the environmental community and the Metro Wastewater Joint Powers Authority – a coalition of municipalities and districts representing about 35 percent of Point Loma’s wastewater flow – have joined forces to advocate for the development of a 100 MGD regional potable reuse program to create a new local, diversified water supply and maximize the flow offloaded at Point Loma.

GHD’s Dawn Guendert, a long-time participant in the stakeholder process, told WDR, “Rather than planning for one wastewater or water project at a time, the alternative concept calls for the region’s wastewater treatment and water supply needs to be planned together, programmatically, over a longer period of time. We believe that by considering combined water supply and wastewater treatment needs, there is an opportunity to minimize ratepayer impact by reducing capital, financing, operating and energy costs, while mitigating environmental impacts.”

Indications are that a water reuse scheme may produce the region’s most cost-effective water supply over the next ten years. The city must soon decide whether it will continue to remain heavily dependent on imported water, with its significantly rising costs, or fund the capital and operating costs of a new, local water supply for the region. It may be now or never.

原文链接：http://www.desalination.com/wdr/49/37/reuse-decision-time-san-diego