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The North Bend Eagle


 

Library construction starts with drilling

by Mary Le Arneal
Published 7/6/11

At long last, construction of North Bend’s new library has begun, and a local North Bend company is one of the first to get its hands dirty.

Contracted by Lacey Contractors to do the drilling for the geothermal heating and air conditioning for the building, Steve Dvorak of Dvorak Well, Inc. has been busy the past few weeks trying to get this done.

Steve Dvorak works on drilling 300-foot holes for the new library.Steve Dvorak pulls a grout line out of a freshly drilled hole in what will soon be the foundation of the North Bend Public Library.

Dvorak is drilling 16 holes, each 300 feet deep. The six-inch holes will contain a water-and-glycol-mix filled tube. The holes will be filled with a sand and bentonite mix (thermal grout). The tubes can be seen sticking out of the ground around the library site. Next is the waiting game.

The contractor is waiting for the ground to dry out so he can pour the footings. Once the building progresses and the water table is down, Dvorak will come back and dig a five-foot trench beside each of the lines to “header” them, which is to fuse them together and connect them to the building. Dvorak said once the rains stop and irrigation starts the water tables should go down, which is necessary since the finishing touches cannot be done under water.

Geothermal heating and cooling uses energy from the earth. Below ten feet the earth is consistently 55 degrees. Geothermal energy originates from the heat retained within the earth since the original formation of the planet, from radioactive decay of minerals, and from solar energy absorbed at the surface.

What geothermal heating does is take the cold from the building and exchange it for the warmth from the ground. Thermal efficiency is high since no energy conversion is needed since the heat is mostly needed in the winter. During the summer when the temperature of the building exceeds that of the ground, heat pumps are used to pump heat from the building in to the transfer medium (typically water with small amounts of ethanol or glycol) and is subsequently pumped through narrow pipes into the ground so that the heat can be dissipated in the earth.

“In the long run it will keep the cost of utilities down,” Library Foundation president Jana Post said. “The heat pump may be a little more costly initially, but we were fortunate to have the funds, so we went with it.”

“It’s green energy,” Dvorak said. “It’s clean.”

Grosch Irrigation, did the test well to give the engineer numbers to work with to determine conductivity, how many holes of tubing were needed for the library.
Dvorak said that the drilling has been tough because of gravel, shale and stone that is high up in the Platte Valley. He was getting one to two holes dug a day and will be done July 5.

The pipes are guaranteed for 50 years. Once the lines are in the building and connected to the heat pump installed by the air conditioning/heat contractor, Dvorak will come back to pressure test the system to check for leaks, but he does not expect any. Once that is done the system is purged, flushed out withe water to get rid of air and debris, and the glycol mix is added to the tubes going into the ground and building, to keep it from ever freezing.

Dvorak is pleased he had the opportunity to work on the library. He had to bid for contract.

“I bid it to get it,” Dvorak said. “I wanted to do something for the town. It’s been a good project for us. I knew it was gong to be tough, but it’s going good.”

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