Marin Independent Journal

Water district looks at pilot facility
By Mark Prado
IJ reporter

Monday, July 12, 2004 - Board expects feasibility report on desalination by July 21

Marin Municipal Water District officials may try to build a mini-desalination plant before doing the real thing.

Water officials are considering pulling water from the bay in order to meet Marin's future water demands and to protect the county against a drought. Earlier plans to take more water from the Russian River have been put aside because of uncertainty over how much water from that source will be available.

But before desalination moves forward, the water district's board of directors wants to see how the technology might work. When it meets in a couple of weeks, the board will get details on a pilot plant, including how much it would cost and how it would work.

"It is essential that we do this to determine costs and water quality," MMWDboard member Charles McGlashan said. "It will help us understand the impacts of this type of operation."

The pilot could also produce other important information, such as how the water would taste.

If all goes to plan, a test plant could be up and running later this year. McGlashan said the idea is to test water when there is the least amount of fresh water in the bay at the end of the summer, and again in the winter when there is the most.

The "plant" is likely to be nothing more than a set of pipes that could be fenced off, district officials said. The district hopes to have a water intake at the Marin Rod and Gun Club. Water officials are discussing the idea with Marin Rod and Gun Club representatives.

"The board will get a full report on the plan July 21," said Libby Pischel, an MMWD spokeswoman.

A similar test plant was built in 1990 by the district. Although that test demonstrated that desalinated water tasted normal and was free of contamination, concerns still persist about its purity.

A real plant would be built on district-owned land at Pelican Way in San Rafael, with San Rafael Bay water being pulled in at the end of a rebuilt Marin Rod and Gun Club pier near the west end of the Richmond-San Rafael Bridge.

The bay water would be piped west along existing roads to the plant. The salt pulled from the water would be piped to the Central Marin Sanitation Agency's wastewater treatment plant and sent back into the bay. Sludge captured by filters in the process would be trucked to the Redwood Landfill north of Novato.

The plant could be built in increments - with each segment able to produce 5 million gallons of water a day - and could ultimately deliver 15 million gallons of water daily. The desalination process would convert about half of the volume of raw water taken from the bay into drinking water.

Blending of brine with treated wastewater from the Central Marin Sanitation Agency could reduce the concentration of salt going back into the bay.