On December 9, Phase I of the geothermal drilling began in the Glessner House courtyard. The 4,700-square-foot grass courtyard is enclosed by three sides of the building plus an ivy-covered brick wall to the south. This is the same courtyard where weddings are held during the summer, the same courtyard that the Glessners once looked out on from their parlor 100 years ago, the courtyard that was paved over in the 1940’s for use as parking when the house became a printing research facility, and the courtyard that was lovingly restored in 2000 back to Glessner-era conditions. Phase I of the project will provide geothermal heating and cooling to part of the building’s first floor.
The first morning, Great Lakes Geothermal arrived on site and set up their compact drill rig. Over the next few days, they proceeded to drill two boreholes, spaced about 25 feet apart, through topsoil, clay, sand, and limestone. Drill cuttings were channeled into a dumpster on the street in front of the museum.
After boring down to the top of the limestone, the three-man drill crew inserted 10-foot sections of steel casing to stabilize the borehole. Every few minutes, one driller literally changed hats—from hardhat for operating the rig, to welder’s helmet—in order to fuse the steel cylinders together. Then they bored the rest of the way through the casing to a depth of 500 feet.
On December 17, the drillers were ready to install two nesting layers of tubing in each borehole. By this time the rig was replaced by a truck-mounted hoist from which dangled a section of fiberglass tubing. The fiberglass tubing is the outer shell of Rygan Corp.’s high performance geoexchange (HPGX) system. It is through this tubing that the crucial heat exchange with the earth takes place. Project engineers selected the HPGX system over a traditional “loop” wellfield design because its concentric tubing is much more capable of transferring heat back and forth from the ground in a small space like the Glessner courtyard.
For the outer tubing, the crew lowered one 20-foot section of fiberglass tube at a time through the casing, screwing it end to end to the next section, and sealing them together. Then, for the inner tubing, the drillers unwrapped a roll of synthetic rubber hose and fed it down through the fiberglass shell.
By Christmas, the two boreholes were complete. Behind the building, beside a big mound of dirt, stood a Bobcat backhoe. The crew carved out a four-foot-deep trench in the courtyard connecting the boreholes to each other and to the museum’s back wall. Inside, in the basement, they jack hammered out a square of concrete floor and excavated down three feet. They then went back outside and cored eight holes through the museum’s thick stone foundation. The trench leading to the building and the hole in the floor will be covered back up once the piping is installed that will carry the earth’s heat into the first floor.
Throughout the drilling, coring, and digging, which lasted about a fortnight (as the Glessners might have said), house tours and other museum activities continued indoors despite all the hubbub outdoors and in the basement. Unfazed by the trucks and heavy equipment in front of the house, neighbors walking their dogs and pushing baby strollers just made their way around the caution tape.
Next: Connecting the knee joint to the hip joint, i.e. connecting the exterior fluid-filled geothermal lines through the holes in the foundation to heat pumps inside the building, just in time to provide a new source of heat for the winter!