Municipal Decarbonization: Groton Town Hall & Public Library Complex
In Groton, Massachusetts, the Town Building Committee undertook a comprehensive civic modernization program encompassing Groton Town Hall and the historic Groton Public Library. The municipality aimed to achieve LEED green building certification, reduce municipal operating budgets, and eliminate fossil fuel combustion in prominent public facilities.
Because the project site sits within proximity to sensitive Nashoba Valley drinking water recharge zones, groundwater protection was paramount. GDNE engineered a failsafe vertical closed-loop borefield positioned beneath municipal lawn areas and paved parking lots, ensuring zero exterior mechanical footprint and absolute aquifer isolation.
Nashoba Terrane Geology & Impervious Bentonite Seals
The subsurface geology consists of Nashoba Formation gneiss with granitic intrusions, delivering exceptional thermal conductivity (1.5 to 1.8 BTU/hr-ft-°F). GDNE drilled vertical 450-foot boreholes, seated heavy steel casing into competent bedrock, and installed continuous IGSHPA HDPE 4710 U-bends.
To guarantee zero environmental risk to Groton's municipal drinking water supply, the closed loop circulates biodegradable, non-toxic food-grade USP propylene glycol with organic corrosion inhibitors. Each borehole was sealed from base to surface with high-solids bentonite grout, creating an impermeable geological barrier preventing surface runoff from entering deeper bedrock fractures.
Documented Civic Results & LEED Optimization Credits
- Energy & Atmosphere Credits: Contributed essential points securing Town of Groton LEED Municipal Green Building certification.
- Operating Cost Reduction: Modeled HVAC engineering design estimate of over 50–55% operating expenditure reduction compared to baseline oil/gas equipment.
- Historic Preservation: Zero visible rooftop chillers or ground-level condensing units, preserving the historic aesthetics of Groton Town Center.
- Subsurface Longevity: HDPE 4710 closed loops backed by a 50+ year service life rating.
Specialized Service Capabilities Across New England
- Standing Column Well (SCW) Drilling: Deep open-loop bedrock boreholes maximizing thermal exchange density for compact urban lots and university campuses.
- Vertical Closed-Loop Borefields: Multi-borehole arrays with continuous IGSHPA-certified HDPE 4710 U-tubes and thermally enhanced bentonite grout.
- Formation Thermal Conductivity (TRT) Testing: Mobile 48-hour ASHRAE-compliant in-situ testing to optimize mechanical engineering loop design.
- Commercial Subcontracting: Turnkey exterior drilling partnering with mechanical HVAC engineers and general contractors.
- 2026 Clean Heat Incentive Support: Assisting clients in securing Mass Save grants ($13,500 standard / up to $25,000 enhanced), 0% HEAT Loans, and commercial clean energy tax credits.