Greenhouse tours showcase progress
The public got its first chance to step inside Fairfield’s farm-to-school greenhouse during a ribbon-cutting ceremony and a series of tours Friday.
Those in attendance learned about how the greenhouse is warmed through excess heat from the neighboring Schaus-Vorhies Manufacturing near the intersection of Stone Avenue and Ninth Street. Several of the people involved in the greenhouse’s creation were on hand to speak about their contributions. Bryan Hancock, who designed and installed the plumbing necessary to heat the greenhouse, even wrote a song for the occasion, which he sang with David Burns and John Lutz.
One of the main sources of heat for the greenhouse is a 17,000 storage tank underground and adjacent to the greenhouse. It is filled with water that is heated by hot air from the manufacturing plant. Water is pumped into tubes a few feet below the soil. The hot water is able to maintain the soil temperature at 70 degrees, which is comfortable for the plants.
Hancock said the water can’t go directly from the storage tank into the ground because it’s too hot. The water in the storage tank can get up to 150 degrees. To cool the water slightly, the water goes into a smaller, 75-gallon tank above ground, and then back into the soil. Hancock installed sensors in the soil that tell the water pump to shut off if the soil becomes too hot.
“If we heat the soil to 80 degrees it will cook the roots,” he said.
Hancock was one of a few people who worked on the greenhouse throughout the winter. He said he spent nearly every weekend since November trying to get the greenhouse up and running, despite the frigid temperatures.
Larry Larson played a significant role in the greenhouse’s development as well. Larson designed a system for regulating the surface temperature of the greenhouse through a series of tubes that bring heat up from 6 feet under ground. The air tubes have the effect of heating the greenhouse in the winter when the soil deep underground is much warmer than the surface temperature, and cooling the greenhouse in the summer, when the soil is cooler.
Larson said the air tubes were the first thing to go below the greenhouse because they are the deepest of the tubes, resting at 6 feet below ground. A fan circulates air from the soil into the greenhouse. Larson said his air tubes are not connected to the large storage tank at all and are a separate means of heating the greenhouse.
The air tubes can cool the greenhouse in the summer, although Larson said their principal purpose is to heat it during the winter.
“We’re focusing primarily on wintertime heat,” he said. “We have plenty of vents and side curtains to cool the greenhouse in the summer. We have a lot of ways of keeping the greenhouse cooled off.”
The air tubes worked very well during the winter, Larson said. Even when the exterior temperature was minus 10, the greenhouse was just below freezing at 31 degrees.
Many people donated time and effort to build the greenhouse. Randy Bales helped weld on a few weekends. Phil D’Agostino helped set up the computer for the greenhouse, and Dean Goodale lent a hand during construction as well.
Jan Swinton, local food coordinator at Hometown Harvest of Southeast Iowa and one of the chief architects of the greenhouse, said she’s happy the greenhouse is up and running, but added there is still work to do. She is looking for volunteers who can plant and harvest this year. Planting began March 1 because January and February proved to be far too cold.
“We didn’t want to plant a crop and let it freeze,” she said. “We were confident that by March 1, it would be warm enough to plant.”
Swinton said two-thirds of the first crop has already been harvested, consisting mostly of salad greens and pea shoots.
“We’re replanting about as fast as the crop comes out,” she said.
A few big projects remain before the greenhouse can be considered “done.” One of those is the installation of a hanging strawberry bed, which Swinton said is a $5,000 project. A system that controls water and air movements, as well as the vents, will cost another $5,000. Swinton said she is raising money for those projects and for a scale and salad spinner.