At the largest Lagunitas School District meeting in recent memory, trustees Tuesday heard fierce opposition to their decision to build a wastewater treatment system jointly with the French Ranch subdivision.

A new system is needed because the district's present system is failing.

Although the evening was billed as an informational hearing, nearly 250 San Geronimo Valley residents filled the Woodacre Improvement Club. Most of the throng objected - often angrily - when trustees reviewed the proposed facility.

School board president Steve Charrier gave a chronology of the trustees' wastewater deliberations. Engineers Oswald and Green presented a technical explanation of why the proposed system was chosen. And Suzanne Reed, legal counsel for the district, reviewed the district's contract with French Ranch.

However, the meeting quickly evolved into a public forum as residents lined up to ask questions about the pond-based wastewater system and formation of a community service area that will include the district and future French Ranch homeowners.

Although the district would be an equal member of the service area, its contract with the French Ranch development limits its share of the system's operating costs to $5,000 a year after reimbursing the developer for the majority of its construction costs, said Reed.

Reed noted the agreement for joint public and private ownership was breaking new legal ground and that she had only the trustees' terms to guide her. "I wrote the contract with the intent to protect the district," she said.

But the legality of the contract was immediately challenged by attorney John Sharp, who represented Mark and Duffy Warner of Forest Knolls. Sharp said Proposition 218, which requires members of a service area pay proportionate costs, could be a "fatal impediment" to the agreement.

Both Reed and Charrier conceded it may not be possible to form a service area if Proposition 218 forces them to take on greater liability for the system's expenses, which could include fines in the case of a failure. "That is an impediment," Charrier said. "We are working on that issue."

Trustee Charrier added that in negotiations over the contract, the district has worked to eliminate its liability for owning the sewer system or the land. "If we don't reach that point completely, we will abandon the process," he said. "We don't want to be the owner of this system. We don't want to be in the sewer business."

Also disputed was the size and location of the proposed sewage facility. Members of Save the Valley, a group opposed to the facility, have repeatedly objected to its site in former wetlands along Sir Francis Drake Boulevard, as well as the presence of open ponds near young school children.

Many had attended a Save the Valley meeting earlier this week where two septic engineers raised potential problems with the pond-based system and gave arguments as to why it may not be appropriate for the school.

One of the engineers, Robert Rawson of Sonoma State University, contended that the proposed system, which is designed to accommodate nearly 25,000 gallons of wastewater a day from 32 houses and the school, is too large and complicated for a campus that produces no more than 9,000 gallons a day on its own.

Rawson argued the system's clay-lined pools could be undermined by roots and burrowing animals and that open ponds are inherently problematic when it rains. He added that the system requires professional supervision and produces odors when it is not working correctly.

"You have a real easy problem, and you're building a rocket ship to the moon," he said. "It's not necessary to get this complicated for a school."

A second engineer, Jeff Loe of Lescure Engineers, argued that the school could build a sand-filter system on less land with lower construction and operating costs. However, his arguments were based on an engineering report by Questa Engineering, a firm hired by the district to explore options to the pond-based system.

At the subsequent school board meeting, Trustee Charrier said Questa had proposed a similar sand-filter system, which the district selected as a backup in case it can't come to terms with the French Ranch developer.

He said the board compared the two systems before choosing to build the pond-based system but never altogether abandoned the sand-filter system.

"The board didn't want to be in any negotiating position if we didn't know what our fall-back was," he said.

Information provided to the school district showed the sand-filter would cost the district $425,000 to build and $15,000 a year to operate, Charrier noted.

The pond-based system would cost a total of $500,000 to build (of which the district would pay $375,000 plus an $80,000 hookup). However, the district's yearly operating costs would be only $5,000 - as opposed to $15,000 for a sand-filter system, said Charrier.

Furthermore, he added, the pond-based system would provide a higher quality of irrigation water and have a much longer lifespan.

"We were trying to do something innovative, something sustainable for the community, and we got no community input," he said, adding he was "stunned" by the sudden opposition to the system.

But a vocal majority of the audience insisted that the school board was stifling debate by not allowing engineer Rawson, who had spoken to Save the Valley, to present his arguments at the trustees' meeting.

In response to their complaints, trustees agreed to schedule another meeting to hear new proposals but disputed whether the subject should come up again for a vote.

"We are not ducking a debate," Charrier said, noting it would be "very difficult" for trustees to change their course so late in preparations for the new facility.

However, Charrier said, he was not opposed to hearing new proposals: "We'd be fools not to."

Trustee Brian Dodd added: "If we are in some way prevented from following the approach we adopted, I would be willing to consider some other solution. However, if there is no practical or legal impediment, I would not. This is the course we've taken."

But Trustee Richard Sloan, who cast the only opposing vote to the pond-based system, insisted the board owes the community more information and another vote.

"How can a small little school that relies upon the support of its community get itself in a hole like this with so many questions unresolved?" he asked.