KUSP Reports: Environment

Recharging Wells With Purified Wastewater

James Dix

Operations plant manager James Dix at the site of the pilot plant, north of Marina, CA. Photo: Wes Sims

By Wes Sims | KUSP News

In addition to the Carmel River, the Monterey Peninsula gets 30 percent of its water from wells drawing from an enormous layer of rock beneath Seaside and Marina. The Seaside Aquifer can’t provide enough water to replace the Carmel River. This is why CalAm has proposed to build a desalination plant. It may be possible, though, to add more water to the Seaside Aquifer.

Groundwater recharge is the process of replenishing natural underground freshwater aquifers to provide a continuous supply of drinking water, as described by Andy Fisher; a professor of hydrology at U.C. Santa Cruz.

“Groundwater recharge is the movement of surface water through the soil and into an aquifer.” Fisher says. “And that typically means that the water moves downward through the soil some distance.  It might be five feet in some areas. It may be a hundred feet in other areas.”

Giving Nature a Helping Hand

Engineer Brad Reisinger inside the pilot plant.

Engineer Brad Reisinger inside the pilot plant.

During the rainy season, groundwater recharge occurs as rain percolates through the soil. But when rain-water is less plentiful, a one-million dollar joint project between the Monterey Regional Water Pollution Control Agency and the Monterey Peninsula Water Management District would give Mother Nature a helping hand: backwards wells, called injector wells, would pump water into the aquifer. The hope is a significant increase in well water and perhaps reduced need for desalinated water. The source would be the peninsula’s wastewater. But first it needs to be highly refined.

Brad Reisinger heads up the six-month pilot project inside an old chlorine treatment building at the wastewater treatment plant, north of Marina. In this phase, he hopes to establish the process for refining the water that would be pumping into the ground.

“So what we’re doing with this pilot is, we’re taking water that’s gone through the wastewater process here and putting it through a whole new treatment train, in what we refer to as an advanced water treatment,” Resinger says. “That’s generally how these are referred to. So it’s a whole separate treatment after it’s already been treated through the wastewater.”

Purifying Waste to Drinking Water Quality

That means water that goes down the drain receives ozone treatment, micro-filtration, reverse osmosis, and advanced oxidation all designed to get rid of contaminants. Operations plant manager James Dix says by the time it would go into the ground, it would be essentially safe to drink.

“You have membranes that remove any organics and salts that are still in the wastewater to the point where the water that comes out of the other end of the filters, the membranes, is potable water and can be injected into an aquifer, in this case, the Seaside aquifer,” Dix says.

Additional purification occurs naturally within the underground basin. But Recycled Water Program Assistant Mike McCullough says water going through this pilot process already exceeds potable standards.

“Any time you drink a bottle of water, if you look on the fine print, you know, it says, ‘treated by ozonation or reverse osmosis, you just saw it down there. So it’s the same technology that we’d be using. So essentially, we are going to be producing bottled water to be put into the basin.”

If it goes online, as anticipated, the water produced by this pilot Groundwater Replenishment Project would become part of the peninsula’s supply, in 2014.

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