Water & Drought

Paso Robles' 'drought-proof' recycled water plant is nearly finished

Recycled wastewater will help Paso Robles Agriculture

Matt Thompson, wastewater resources manager for Paso Robles, talks about the recycled water project at the wastewater treatment plant.
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Matt Thompson, wastewater resources manager for Paso Robles, talks about the recycled water project at the wastewater treatment plant.

Paso Robles' recycled water treatment facility is starting to take shape — and officials are excited about its potential as an additional water source for thirsty North County residents.

Construction on the $14.4 million plant, also known as a tertiary treatment facility, is more than halfway complete.

It's expected to be finished in January 2019 and will eventually produce treated water to help offset agricultural groundwater pumping in east Paso Robles.

"We're treating the city's wastewater like a new, raw water supply," said Matt Thompson, the city's wastewater manager.

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Paso Robles' fourth water supply

The new plant is related to the city's $47 million overhaul of its wastewater treatment plant. That was completed in 2015, paving the way for construction on the recycled water plant to begin in 2017.

Recycled water will be produced using cloth filtration and ultraviolet light to further purify wastewater, making it suitable for irrigation and other non-potable uses, Thompson said.

The plant's UV disinfection technology means it won't need chlorine or other chemicals that add salts to the water and degrade its quality.

Unlike Pismo Beach's new recycled water project, which uses reverse osmosis to make wastewater drinkable, Paso Robles' plant won't produce water that residents can consume.

Thompson said that's because the two cities are in need of different types of water — Paso Robles needs more water for irrigation, and Pismo Beach needs more water for drinking.

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The Tertiary Treatment Facilities, which is part of the new Paso Robles Recycled Water Project, is currently under construction and expected to be complete by January 2019. Joe Johnston jjohnston@thetribunenews.com

So, instead of building a more expensive facility that produces drinking water, Paso Robles will invest an additional $17 million in a distribution system for its water that will pipe it to the east side of town, he said.

At its peak, the new plant will be able to process about 4,900 acre-feet of water, or 1.6 billion gallons, per year, according to a California Environmental Quality Act (CEQA) study checklist.

Thompson believes it will supplement the city's three other water sources: Salinas River wells, the Paso Robles groundwater basin and piped-in water from Lake Nacimiento.

He called recycled water "drought proof" because it makes use of wastewater, which residents will always produce.

"This is Paso Robles' fourth water supply," he said.

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Matt Thompson, wastewater resources manager for Paso Robles, gives a tour of the Recycled Water Project at the wastewater treatment plant. Joe Johnston jjohnston@thetribunenews.com

Distributing recycled water

Construction on the distribution portion of the project — a 5- to 6-mile pipeline — will begin in 2019.

The pipe will pump water from the treatment plant to the east side of town, with a reservoir off Union Road in Barney Schwartz Park.

Until the pipeline is finished — Thompson estimates it should be complete about 18 months after construction begins — recycled water will be pumped back into the Salinas River, as it is now.

Eventually, the city will sell the water to customers, which will help pay back the loan money used to build the pipeline over the course of 30 years, Thompson said. Low-interest financing from the state will fund the project, he said.

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Thompson expects customers will be vineyard owners and other agricultural users, although the water could also be used to irrigate golf courses, school campuses and parks.

Even before the pipe is constructed, Caltrans will likely purchase recycled water to irrigate landscaping along Highway 101, Thompson said.

He said the city will sell the water for less than its typical price of $1,900 per acre-foot as an incentive for customers.

Thompson hopes the additional water source will take pressure off the critically overdrafted Paso Robles groundwater basin, and even stabilize it.

"We're really trying to prepare for the next big drought," he said.