DSRSD: Recycled water plant expansion complete, residential fill station not reopening

The $18.8 million expansion of the Tri-Valley’s largest water recycling plant is complete, allowing for millions of more gallons of nonpotable recycled water to flow through purple pipes for large-scale irrigation customers in the region.

But though construction has wound down, the once-popular residential fill station, which allowed residents to take free recycled water to use for personal irrigation purposes, won’t be reopening for the foreseeable future, according to Sue Stephenson, community affairs supervisor for Dublin San Ramon Services District (DSRSD).

Stephenson expects, though, that decision will be revisited “when” (not “if”) California experiences extreme drought conditions again — like conditions were in 2014, when DSRSD opened the first-of-its-kind residential station before closing it in late 2016 amid the plant expansion project and as the drought subsided.

For now, Tri-Valley leaders are commending the completion of work at the Jeffrey G. Hansen Water Recycling Plant in Pleasanton, with about 70 water service engineers, operators and local officials marking the occasion at a ceremony there on Aug. 15.

The purpose of the expansion has been to increase the plant’s recycled water production from 9.7 million gallons a day to ultimately reach 16.2 million gallons a day, keeping pace with the growing demand.

“Moving forward, we are excited to offset more potable water use than ever before,” said Pat Howard, board member for DSRSD, which provides wastewater treatment services for the city of Pleasanton by contract.

The expansion project has been a collaboration between three entities: DSRSD, the East Bay Municipal Utility District and the city of Pleasanton. The trio split the nearly $19 million price-tag according to the proportion of the increased water supply each agency would receive: 46% for DSRSD and 27% for EBMUD and Pleasanton, respectively.

DSRSD and EBMUD jointly opened the plant in 2006, in order to operate their San Ramon Valley Recycled Water Program. The city of Pleasanton joined the recycled water effort in 2014.

The recycled water from the plant primarily services large customers in the Tri-Valley, and is delivered through purple piping to irrigate schoolyards, parks, roadway medians and golf courses. In Pleasanton, the recycled water is distributed to the Hacienda Business Park and city parks including Ken Mercer Sports Park, Tennis and Community Park, Val Vista Park, Creekside Park, Owens Park and Harding Park, along with Hart Middle School.

Pleasanton also purchases water from the Livermore Water Reclamation Plant to serve some customers in eastern Pleasanton — including Pacific Pearl, CarMax, Stoneridge Chrysler Jeep Dodge and Stoneridge Creek Park — but about 95% of its recycled water comes from the Jeffrey G. Hansen plant.

By increasing the capacity, officials say, the plant is able to save drinking water from being used for these large-scale irrigation purposes.

Residents hoping to access free recycled water for their own personal use, however, will have to look elsewhere.

The residential fill station, which operated from June 2014 through December 2016 and was the first of its kind in the state, won’t be online again at least for now, due to high cost and diminished need — California is no longer experiencing the same drought conditions as when it was established, Stephenson said.

The expansion and improvement project specifically revolves around the installation of the new ACTIFLO process, along with new ultraviolet modules and increased pumping capacities.

The ACTIFLO Turbo system is a pretreatment process, activated as water enters the water recycling facility. (The wastewater entering the facility, or “secondary effluent,” has already undergone primary and secondary treatment at the wastewater treatment plant, which removes up to 95% of suspended solids. Secondary effluent meets the requirements to be released into the San Francisco Bay.)

ACTIFLO increases the water recycling capacity by removing additional particulates and improving the secondary effluent’s turbidity — or cloudiness of the water. The clearer and cleaner water can then move through the subsequent sand filtration step at a faster pace.

“As the number of particles in the water increases, the treatment ability of the sand filters decreases,” said Levi Fuller, an operations supervisor at the plant. “The ACTIFLO process unit pretreats the incoming water by removing additional particulate matter. Therefore, the ACTIFLO pretreatment unit allows the operators to treat a large volume of water resulting in a recycled water plant with a higher production capacity.”

Additionally, the project added 10 new ultraviolet modules to the existing 60, in order to handle the increased flow of recycled water. The modules are used for the final stage of the water filtration, in which the ultraviolet lights kill any lingering bacteria and viruses, simulating the disinfecting powers of sunlight.

And the increased pumping capacities are designed to match the new recycling capacity rates.

Since the project’s completion, the plant now has a permit to produce 12.3 million gallons a day. In the upcoming year, DSRSD will be testing the plant’s sand filters in the upcoming year, in order to receive Regional Board approval to increase the capacity further to 16.2 million gallons a day.

While 16 million gallons is certainly an increase over the previous 9.7 million, it still may not be enough in the long term. Todd Millison, a DSRSD senior wastewater treatment operator who gave attendees a tour of the recycled water plant at the celebration, said that at maximum buildout, the recycled water demand in the area could be as high as 21 million gallons a day. And the wastewater supply doesn’t equal the demand.

“We’re in a little bit of a pickle because we only have about 10 or 11 million gallons a day coming into the plant,” Millison said. “So we’re in the unusual situation of going around, trying to beg neighboring districts for some of their wastewater.”

Water supplies and allocations remain thorny issues statewide, and local water agencies continue seeking to diversify their water sources, particularly in preparation for the increased water demand of the summer.

The Zone 7 Water Agency, which serves as a water wholesaler for water service providers in the Tri-Valley, including DSRSD, recently announced that they were able to meet customers’ July water demands of 5,360 acre-feet (AF) of water — with surplus.

About 80% of Zone 7’s water supply comes from the State Water Project. The rest of the supply comes from other sources, such as through special transfer agreements and purchases from other agencies and farmers.

In July, the agency received 3,760 AF from the State Water Project and 1,000 AF of its allocated water from the Yuba Accord, a partnership aiming to provide a long-term water supply for fish and wildlife and supplemental water supplies for cities and farms. Zone 7 has also set up a transfer of 800 AF of water from River Garden Farms in Knights Landing, part of which came through in July.

Zone 7 also has 104,100 AF of water stored in groundwater banks in Kern County, but the agency does not plan on drawing from them this year.

For the rest of the year, the supply appears well-equipped to meet demand — the water agency estimates a demand of 17,200 AF for the remainder of 2018, with a total estimated available supply of 251,000 AF, including both incoming sources and water storage.