Kingswood Regional School Closed Loop Geothermal System Installation

Cushing & Sons drilled the test boreholes at Kingswood Regional School in the Summer of 2009. We were part of the design team for the geothermal project, working with Yeaton and Associates of Littleton, NH.

Cushing and Sons was the selected installer for the Kingswood Regional School Project geothermal drilling in Wolfeboro, NH. This project, utilizing 320 boreholes at 400 ft. each, is the largest closed loop geothermal project to-date in New Hampshire.

The project was started in the Winter of 2010. We completed our work in April of that year, and the system was commissioned and fully operational in 2012. Cold temperatures, record precipitation, challenging drilling and grouting requirements were overcome by our experienced crews.

Some impressive numbers resulted in a job of this size, among them was 132,000 lineal feet of drilling and Utubing were installed; and the usage of 1.2 million pounds of sorted silica sand that was pumped into the boreholes.

Normal residential geothermal projects usually involve two to six boreholes, but the methods we employ in these jobs are similar. We bring this type of expertise to every project we do - be it large or small. Our people are very proud to have been a part of this accomplishment.

Cushing and Sons has the people, experience, and machinery required to properly install these systems; our first one was installed in 1983. Geothermal drilling is now a major offering of our company. We have plenty of references throughout New Hampshire, Vermont, Maine & Massachusetts. Cushing and Sons is fully insured, bondable, and most importantly - we have a prven track record of successful job completions.

The Kingswood Project is the largest closed loop geothermal installation in New Hampshire. The project was done during the Winter and early Spring. The drilling of the bore holes (pictured here) can be completed almost any time of the year.
This project utilized eight truck loads of 1.25" x 810' black poly Utubes. They arrive on the job site factory sealed and wrapped.
Drilling bore holes to a depth of 400' requires an experienced crew. Cushing & Sons set the bore holes at 20' intervals.
Note the pink color of the Conway granite encountered at the site.
It is an impressive site to see four drilling rigs working at a project of this scale. Prior to drilling, the site was excavated down to pipe height. On a job of this magnitude, preliminary excavating to prepare the drilling field is the most economical and time-saving method.
After the Utubes were set in the bore holes, the holes were grouted with a bentonite/silica heavyweight grout mix to fill the annular space between the Utube and the native formation. Here, we see sand being added to the bentonite mixture in the mixing tube. The idea is to have the grout fill the void to mimic transfer of the native formation to the tubes through materials that are similar to the native formation.
The water shown discharging from the well head is being displaced by the grout going down the pipe in the well. The pipe delivers the grout from the grouter to the bottom of the bore hole, and is lifted as the grout is being placed.
The individual bore holes are connected to the poly pipes. This picture shows the pipes being prepared for hook up. All joints are fusion joints, essentially the plastic is melted together for a permanent connection. On this project, ten bore holes were connected per circuit.
After the pipes are connected, tests are conducted to ensure the integrity of the joining process prior to backfilling. After testing, the lines are run to the vault for delivery of the fluid to the building.