KAILUA — When Le Jardin Academy students arrived back at school yesterday to start another year, they found something more than the usual group of old friends and new teachers. The campus now includes six new classrooms and a library building that officials said will play a key role in the private school's ongoing expansion and development.

Students watched quietly yesterday as school officials dedicated the new buildings, accepted multimillion-dollar donations to help pay for them and promised even bigger things to come.

The new buildings, the first phase of a $21 million expansion that is expected to eventually include 12 more classrooms and a new gymnasium, will assure parents that "they'll always have the option of a high-quality private school on this side of the island," headmaster Adrian Allan said.

Enrollment has grown in the last six years, from 350 to 800 students on the 24-acre campus overlooking Kawai Nui Marsh.

The school was founded in 1961, and after years of moving to several temporary locations seems to have settled into its permanent facilities, community members said yesterday.

"We believe in the school and its place in the community," said Kimberly Dey, representing the Charles B. Wang Foundation, which donated $3 million toward the school expansion. "It's only fitting that Le Jardin now has the campus buildings to match the level of the education that it provides."

Mitch D'Olier, president of the Harold K.L. Castle Foundation, which also donated $3 million to the expansion drive, said the school is an important fixture in the Windward community.

"A great community like Windward O'ahu needs its own great school. It's a great thing to know that our students don't have to spend two hours a day crossing the pali to get a great education," he said. "The dream is that the kids sitting out there today will eventually grow up and have a great private school on the Windward side to send their own children to," D'Olier said.

The school's own trustees also donated about $1 million to the expansion program, Allan said.

When the second phase of the expansion is completed, the school hopes to have an enrollment of almost 1,000 students, Allan said.

While fifth-grade students immediately began using four of the new classrooms, the library was awaiting finishing touches that will make it available for use in a few months, he said.

Once that work is done, grading will begin for the new $9 million gymnasium, an administration building and other classrooms that will allow moving all of the school's students onto the main campus by next fall, he added. Currently the school is also renting space in Kailua for students in pre-kindergarten and junior kindergarten.

Officials said the new buildings also will provide excellent shelter for students waiting to be picked after school on rainy days.

Reach Mike Leidemann at mleidemann@honoluluadvertiser.com.