PROJECT OVERVIEW
Phoenix Project #2512
When one of Massachusetts’s most prestigious institutions chose ground source heat pumps to meet its heating and cooling needs, Phoenix was selected as the geothermal subcontractor to deliver the project on time and within budget. The work involved installing a geothermal borefield consisting of 35 vertical boreholes to support a partial renovation of an existing 75,500-square-foot, three-story school building originally constructed in 1964. Despite strict working-hour limitations, changing weather conditions, and the challenges associated with excessive groundwater production, our team successfully performed the necessary drilling and water management needed to complete this complex project.
At each borehole location, Phoenix installed temporary steel drill casing into bedrock before advancing to the target depth of 567 feet below ground surface. Once drilling was complete, each borehole was flushed with water to remove all cuttings. After the drilling equipment was removed, a 1.50-inch single HDPE closed U-bend heat exchanger loop and tremie pipe were installed. Thermally conductive (TC) grout was then placed from the bottom up. The temporary steel casing was subsequently removed and reused at additional borehole locations. Phoenix utilized multiple water settlement and filtration systems to manage all groundwater effectively.
Following installation of the vertical boreholes, Phoenix conducted system integrity testing. This process included flushing and purging, followed by flow and hydrostatic pressure testing using clean water. All pressure testing was digitally recorded to provide the client with comprehensive documentation for the new ground source heat exchanger system.
Phoenix, as the overall construction advanced, installed lateral HDPE circuit piping from the borefield to the building’s mechanical room using a highly skilled union workforce. Prior to connection to the geothermal manifold (by others), Phoenix filled the circuit piping with deionized water to prepare the system for operation.
