Drilling for an energetic approach
By JUDY SHERARD
The drilling rigs at Hays Middle School won't result in oil wells.
They're searching for energy in the form of geothermal wells.
"Geothermal is a heat source. ... If you go more than 4 or 5 feet down, you get into a constant water temperature. I assume it varies a little bit with depth, but it's constant otherwise," said Terry Ault, the architect representing USD 489 on the eight-classroom addition at the school.
The wells aren't dependent on finding water. It just works as a flow through medium pumped in a continuous loop.
Filling the system doesn't take a significant amount of water, and there's not an ongoing water usage with the process, Ault said.
"If the water from the building is warmer than that in the ground, it will tend to give off heat," he said.
"If it's cooler than that in the ground, it will pick up heat," Ault said. "That's how you transfer heat. There's always enough heat there below grade to heat and cool the building."
A total of 34 wells are being drilled on the east side of the school to heat and cool the addition.
"It's nice to keep it close to the building so it keeps heat loss down," he said.
The heating and cooling load is determined by a mechanical engineer based on the number of occupants, weather conditions and heat producing items such as computers.
The initial plan was to drill 30 wells 390 feet deep.
A test well drilled last fall showed the 34 wells 350 feet deep were needed.
The wells and connecting pipes are buried below grade, and there's no routine maintenance required.
They enter the building on the north side.
Each classroom has its own individually controlled heat pump.
If a classroom on the south side of the building is warm, it cools by discharging heat into the system. A chilly classroom on the north side can take heat from the pipe.
"They might offset each other," Ault said.
Total estimated cost of the project is estimated at $2.7 million. USD 489 received a Federal Emergency Management Agency grant to help pay for the project.
Built to FEMA specifications, the classroom addition will serve as a storm shelter for the building occupants.
The school district's share is expected to be approximately $1.4 million, with the money coming in installments from the capital outlay fund.
By the 2016-17 school year, administrators project nearly 800 students will be attending HMS in sixth, seventh and eighth grades, requiring the additional classrooms.
Initial cost of installing the geothermal system is higher, Ault said.
While FEMA doesn't pay for the entire building project, it was "willing and happy to include funding for geothermal," he said.
So the cost to the district is less than if they had paid for the entire cost of traditional roof units.
"So they pay less in construction costs, and they'll pay less operating costs," Ault said.