Geothermal drilling makes for a big mess at the courthouse

The Jasper County Courthouse lawn is normally a well-trimmed, immaculately-landscaped piece of real estate. It will be quite a while before it's that way again.

The Carey Drilling Company of Winterset knows how to make a mess. The east side of the courthouse lawn is a conglomeration of drilling rigs, hoses, tank trucks and large, gray mud puddles. It's all in the name of progress, however, as the men drill a series of holes to accommodate the geothermal heating and cooling system for the courthouse.

James Carey, his brother Jason and Josh Easley will be working for the next month or so, drilling a series of 20 holes, two rows of 10 holes each. James Carey said the landscape below the courthouse lawn is making for rather difficult drilling conditions.

"It's not really good drilling," Carey said. "There's a lot of sand, and we hit rock at 210 feet."

When their drill hits rock, a new drill bit, one with industrial-strength diamonds, is used, and the process slows down. The process uses water and bentonite pumped into the hole during the drilling, and a slurry comes out into a holding pan, where it is allowed to settle through a series of baffles. Eventually, the slurry is disposed of at a special dump site provided by the city.

Drilling for each hole will extend to 300 feet, where Carey said the temperature is a constant 52 degrees. The holes will be filled with a 1-inch diameter polyethelene pipe, that has been pressure tested to ensure there will be no leaks. The areas surrounding the pipe will be filled in with dirt, and eventually the pipes will be filled with an 80/20 mixture of propylene glycol and water.

Carey said the geothermal system is like a big radiator. It always begins with the mixture at 52 degrees. During the summer, it can be used to cool the courthouse, using the internal systems that will be taking the place of the old boiler systems. During the winter, the mixture will be heated approximately 20 degrees to keep everyone in the courthouse warm and toasty.

Carey anticipated work to be completed in another month.

John Jennings can be contacted at (641) 792-3121, or by email at jjennings@newtondailynews.com.