Ohlone Community College District
Geothermal Ground Loop Design and Installation – Phase I

Geothermal Ground Loop Design and Installation – Phase I

Fremont, California

Project Start: April 2015

Project End: November 2017

Ground Loop Size: 288 vertical loops x 400 ft. deep

Meline Engineering provided an engineered design for a phased Geothermal Ground Loop System of which Phase I will be connected to the new Academic Core Buildings and Central Utilities Plant (CUP) in the summer of 2018. The CUP is designed for a nominal 600-ton chiller/heat pump load. Phase I provides 360 tons of cooling and heating for the Academic Core which will be the first group of buildings to be connected to the CUP.

To ensure that CUP would be operational as planned mid-2018, the design team worked closely with the District which currently has multiple construction projects underway. The challenges associated with this design included finding a place to put the ground loop that did not impede other construction projects nor disrupt the normal business of education which is year-round at this campus. The final ground loop design for Phase 1 resulted in five separate ground loop fields connected to a common two-pipe distribution system that has been routed from the lower campus parking lots to a pair of 12-inch isolation valves ready for connection to the CUP.

The total equivalent length of pipe for the ground loop and distribution piping system is 228,330 feet or 43.2 miles. Phase I of the ground loop included 12 circuits of 24-loops each. As with most commercial systems at this latitude, the central plant is cooling-dominated resulting in a vertical loop system drilled to 400 feet and spaced at 25 ft. centers. The project was closely monitored by the Alameda County Water District and is the first vertical loop system to be successful installed in the county.