• Busted drill rig effectively seals the deal on board decision to not pursue geothermal system

 

MUSCATINE, Iowa — Vic Amoroso has three ideas for improving the heating, ventilation and air-conditioning system at the county administration building and at the neighboring county attorney’s office.

None of the ideas involves connecting the building to a geothermal heat pump-based system — and for good reason: there’s too much debris beneath the building, at 414 E. Third St., to make the connection practical.

Amoroso, a mechanical engineer and president of A&J Associates of North Liberty, told the Muscatine County Board of Supervisors Monday that the drilling contractor broke his drilling rig while drilling 20-30 feet beneath the parking lot next to the building. That’s a sure sign there’s too much man-made debris beneath the buildings, Amoroso told supervisors during their regular meeting Monday.

“A&J decided not to evaluate the geothermal option further,” Amoroso wrote in his report, “because we cannot confidently assign expected costs to account for the unknown debris, extra well casings and other unknowns.”

The county’s consultant considered running lines from the courthouse, which had a geothermal system installed in 2011, to the administration building to provide geothermal loop flow, but the cooling and heating load estimates indicate there’s only enough geothermal capacity to cover the courthouse, the jail addition and the original jail’s HVAC systems.

“I’m disappointed,” said Kas Kelly, who chairs Muscatine County Board of Supervisors. “I was hoping we could accomplish this.”

What Amoroso can and will do is design a new variable refrigerant flow system, which includes energy recovery units, humidifiers and supplemental perimeter hot water heat. That option features a 3.13-year payback period. That’s how long it will take for the county to recover its cost based on the amount of energy the new system will consume and the reduction in required maintenance.

Amoroso estimates the variable refrigerant flow system will cost $498,149 to construct. Supervisors said they agreed with his recommendation and asked him to design the proposed system, then put it out to bid in January.

Amoroso’s recommendation carried the day over two other possibilities: one that would upgrade the current system to meet new state codes, and another that includes water-to-air heat pumps, heating boilers and a rooftop evaporation cooler.

Amoroso told the board the work probably won’t be undertaken until fall 2013, but it will be designed in the coming months.