What has been described as the most innovative school building project in Minnesota recently took place in Grand Meadow and involved a process known as monolithic concrete dome construction.

Five imposing white domes now sit on a stretch of farmland on the edge of Grand Meadow, looking for all the world like giant mushrooms.

The education facility was constructed for Independent School District No. 495 on a 40-acre site in Grand Meadow and consists of five domes each approximately 150 feet in diameter.

The individual domes now house various related programs that are linked together to serve approximately 500 kindergarten-through-12th grade students.

The 95,900-square-foot school includes the five 150-foot-diameter concrete domes and three rectangular connecting link buildings.

Four factors drove the decision to construct the Grand Meadow Dome School, said Bruce Klaehn, the school's superintendent: (1) lower construction costs, (2) lower operating costs, (3) increased safety, and (4) improved use of space.

The domes are divided into a high school, an elementary school, a gymnasium and physical education building, an administrative/library building, and a cafeteria/special programs building, according to designer TSP Architects & Engineers, Rochester, Minn.

Both elementary and high school domes are designed with classrooms surrounding large, open, carpeted areas that can accommodate several groups involved in differing activities.

The domed school complex was designed by TSP to make use of a geothermal mechanical engineering system that has subsequently reduced operating costs for the school district.

TSP engineers estimate that construction of a "more conventional" school building with typical heating and cooling systems would have resulted in energy costs nearly double of what the district previously paid.

The unique nature of the dome school's appearance has been matched by its geothermal heating system.

Approximately 100,000 linear feet of buried piping serves to exchange heat between the ground and 19 water-to-water heat pumps.

The heat pumps generate hot or chilled water for coils in seven air-handling units. Constant volumes of fresh air are efficiently provided to each air-handling unit through energy recovery units sized for each school area served.

"The Grand Meadow school," said Karl Dirksen, head of TSP's mechanical engineering department, "serves as an important point of departure for future public school design.

"It not only addressed the concerns regarding initial construction costs but also the ongoing cost of operating educational facilities.

"The design is a unique solution to a community's needs for economical educational space and has captured the imagination of local taxpayers, students and teachers."

Serving as project construction manager was the firm of E&V Consultants and Construction Managers, Minneapolis.

"It was a interesting and intriguing project," said Randall Lutz, senior project manager at E&V. "Domes have been around for centuries, but there is an apparent economy with today's designs that make them competitive with conventional construction methods."

Simply stated, a monolithic dome is a super-insulated, steel-reinforced concrete structure. In 1979, the first patent was awarded to the monolithic dome process.

According to the Monolithic Dome Institute, the typical monolithic dome starts with a concrete ring foundation reinforced with steel rebar. Vertical steel bars embedded in the ring beam footing are attached to the steel reinforcing.

A rugged fabric known as Airform, fabricated in Italy and engineered to the appropriate shape and size, is attached to the concrete base. Using blower fans, the Airform next is inflated to create the shape of the dome. The fabric thus is both the form for construction of the dome and its outer roof membrane. (The fans run throughout the construction process.)

Next, approximately 3 inches of polyurethane foam insulation is applied to the interior surface of the Airform. Rebar is attached to the foam using hooks embedded in the foam. The rebar is placed in a specially engineered layout of horizontal and vertical rebar. Shotcrete is then sprayed onto the interior surface of the foam to embed the rebar.

After 3 inches of shotcrete is applied, the dome becomes, in effect, a steel-reinforced concrete structure.

The Airform serves to protect the domes from UV radiation and repels rain and snow. (The fabric might need to be coated with a spray-on treatment sometime during the next five years.)

The Grand Meadow domes' monolithic construction should serve to make the school virtually tornado-proof, according to Klaehn. With the exception of two skylights, the domes are windowless.

According to Dirksen, the Grand Meadow school is the largest monolithic concrete dome school in the United States.

To finance construction of the new school, Grand Meadow voters passed an $8-million bond issue by a vote of 496 (yes) to 322 (no). In 2000, the Minnesota state legislature helped out with a $3-million innovation grant.

(Renovation of the former Grand Meadow school constructed in 1916 would have cost $7 million.)

The $12.3-million school complex exceeded the $8-million bond issue and the grant for the Minnesota legislature. The remaining funding came from a $466,000 loan from Alliant Energy, $650,000 in investment interest and a transfer of funds from Grand Meadow's handicapped accessibility funds to the building budget.

The entire school project budget includes land purchase costs, professional and legal fees, school furnishings, and equipment.