RANCHO MURIETA, CA (MPG) - The June manganese flare-up in Rancho Murieta’s drinking water has prompted the Rancho Murieta Community Services District to begin discussing what could become the community’s biggest overhaul of its water treatment system in more than a decade.

During the Improvements Committee meeting on July 8, Chief Plant Operator Travis Bohannon didn’t mince words.

“I firmly believe that we need to get rid of Plant 1,” Bohannon said. “We need to demolish it, and we need to replace it with a conventional treatment plant.”

Recognizing the significance of the proposal, he added, “So that’s my bombshell for this morning.”

No decisions were made, and committee members emphasized they are only beginning to evaluate the idea. Instead, they directed Bohannon to return to next month’s Improvements Committee meeting with additional information comparing several alternatives before deciding how to proceed.

The Improvements Committee consists of Director and Chair Bill Gere, Director Randy Jenco, Bohannon, Interim General Manager Amelia Wilder and other district staff. The committee examines infrastructure and utility issues in detail before making recommendations to the board.

(A separate story covers other meeting topics including sink holes in the golf courses.)

Action Plan Needed

The discussion stemmed from the district’s June 19 manganese event, when elevated manganese levels prompted a precautionary bottled water advisory for infants. Bohannon said operators spent more than a day adjusting chemical feeds, monitoring water quality and bringing the system back under control before the advisory was lifted.

Although the incident was resolved, Bohannon said it highlighted the need for a formal action plan whenever manganese levels spike. 

“This happens every year,” he said. “Sometimes it’s not as bad; sometimes it’s astronomically bad.”

Bohannon said he wants an engineering study completed not only to recommend improvements to the district’s treatment process but also to develop an emergency action plan that operators can follow during future manganese events.

“If I’m not available, it’s something that staff can look at and go, ‘All right. This is what we have. This is the direction we need to go,’” he said.

The proposed engineering study, which would be prepared by the engineering consultants KSN Inc. and managed by Domenichelli & Associates, the district’s contract engineer, is estimated to cost about $120,000. It would evaluate treatment alternatives, recommend operational improvements and develop emergency response procedures.

Committee members, however, said they wanted to obtain a second proposal before deciding whether to move forward with a study of that cost.

The discussion then broadened beyond the June incident to the long-term future of Water Treatment Plant 1.

Bohannon explained that when he joined the district in 2009, both treatment plants used conventional filtration, and manganese was not a concern because conventional treatment provides enough contact time for chemicals to remove manganese before filtration.

Today, Plant 2 still uses conventional treatment and consistently removes manganese to non-detectable levels. Plant 1’s membrane system, however, can’t remove manganese from water.

Bohannon said Plant 1 also has become increasingly expensive to operate. The district is preparing to spend nearly $900,000 to replace two trains of membranes because manganese stains the membranes, making repairs ineffective and forcing replacement several years before their expected 10-year lifespan. Two employees spend two days each week repairing membranes, and the cost of replacement membranes and cleaning chemicals continues to rise.

“The safety of the water that we are supplying to the residents is paramount,” Bohannon said. “The membrane plant does provide good water. I’m not saying it doesn’t, but it doesn’t remove the manganese because of the way that the plant was built. We have no pretreatment.”

Wilder asked whether the district could improve the existing membrane plant by adding pretreatment ahead of the membranes rather than replacing the entire facility.

Bohannon agreed pretreatment could improve the plant’s performance but said the district currently doesn’t have the “real estate” to construct the settling basins and other infrastructure that would be required. 

Jeff Pearson, representing Rancho North, said the developer owns undeveloped property adjacent to the treatment plant that could potentially provide room for future expansion.

Director Randy Jenco also revived an idea discussed several years ago: converting Plant 2 into a pretreatment facility before sending water through Plant 1’s membrane system.

Bohannon said that remains a viable option but cautioned it would eliminate the district’s backup conventional treatment plant if Plant 1 experienced a major failure. It also would require increasing the size of Plant 1.

By the end of the discussion, the committee agreed Bohannon should return to next month’s Improvements Committee meeting with additional information comparing three primary alternatives: replacing Plant 1 with a conventional treatment plant, adding pretreatment to the existing membrane facility, or converting Plant 2 into a pretreatment facility feeding Plant 1’s membrane system. Staff also will seek a second proposal for the manganese engineering study and further refine the questions committee members want answered before deciding whether to proceed.