Great River Energy Headquarters
Geothermal Lake Loop System Overview
The installation of the core water lake-loop system at Great River Energy's new corporate headquarters in Maple Grove, Minn., is the largest system of its kind in the upper Midwest. The system includes over 540 tons for heating and cooling the building. Special considerations were undertaken in the design and detailed scheduling and plans were followed throughout the Lake Loop system's installation. Provided below is a brief overview of the installation process completed by Doody Mechanical and a general overview of some of the key components and systems provided.
We had to excavate a trench for the supply and return lines into the lake to ensure lines were below the freezing line. Special considerations for erosion control were taken to ensure we followed Sedimentation Control Plan as specified by LEED.
A vault containing a header with 26-3” supply and return water lines was installed to link the heat pump system within the building to the lake loop coils.
An excavated avenue of two (2) 10” lines were installed to link the building with the header located within the vault.
The 10” lines connecting the building with the vault were subsequently backfilled and buried 8 feet below grade.
26-3” supply and return lines were installed to link the header with the 39 pods located in the lake.
Each pod contained 14 coils. Each coil represents 1 ton of cooling. The coil pods sit on top of a PVC frame and concrete blocks are located on the bottom to ensure stability on the lake bed floor.
The coils are pressurized and filled with air during the installation process. We used a boat and GPS to precisely locate each pod position to ensure each pod is situated at the designed location chosen for proper heat transfer.
Connecting to each 3” line supplied at the header are 2” lines connecting a set of 3 pods as seen in the picture at right. A total of 78 lines connected the 39 pods.
Final installation of the lake loop system prior to filling with the propylene-glycol water and sinking to its operational position.If you have any additional questions regarding this installation or more specific questions regarding the system please feel free to contact us.
Project Overview Video
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