The fence went up around the block last week, and the drilling rig is on its way.
Soon, a crew will begin plumbing a parking lot east of the Capitol, sinking pipes into 225 holes, each 670 feet deep — more than 25 miles of tunnels total.
And by this time next year, the state’s new geothermal well field should be supplying the Capitol all of its cool air and some of its heat.
The well field is just one piece of the first phase of the 10-year, $106 million Capitol renovation project, which also includes window repair, fire alarm upgrades and a new emergency electrical generator. But it’s likely the most visible.
The state emptied the parking lot, a full city block between K and L and 17th and 18th streets, closing it off with chain link. And once they’re done drilling wells, they’ll have to route a pair of large carrier pipes beneath K Street and into the Capitol’s basement.
The closed-loop system will keep a liquid solution flowing between the well field and the Capitol, absorbing and shedding heat from the building.
“We’re simply using the temperature of the ground to cool the solution within the pipes,” said Capitol Administrator Bob Ripley said. “We’re giving off the heat from the building into the ground; by the time it comes back up to the top, it will be cool again.”
Construction should last about a year, and because the well heads will be below the surface, the lot will reopen as a parking lot.
But it might not stay that way. The state is also installing footings to support a future building. If workers don’t do that during the geothermal construction, it would be impossible to build on that site in the future, Ripley said.
“If the state wants a chance to ever put something on top of this well field, footings to support it must be put in while the wells are being installed,” he said.
There’s nothing planned yet, he said. But a future likely project would be an office building with parking on the first two levels.
A first-floor parking lot would give workers better access to the underground wells if they needed repair, he said.