GZA GeoEnvironmental, Inc.

Scope Of Work

In addition to pursuing a LEED Gold rating, this 60,000 SF building is one of three demonstration projects for the Commonwealth of Massachusett’s Zero Net Energy Building (ZNEB) program. As such, the design incorporated energy efficiency strategies including a geothermal-based HVAC system. Fifty wells to a depth of 500 feet facilitate the thermal exchange with the earth.  GZA provided both geothermal and geotechnical design and construction consulting services for the project. GZA’s work is now substantially complete and the facility is scheduled to open in 2011.

Our Geothermal services included four distinct work phases:

Geothermal Feasibility Study. Based on HVAC loads, GZA reviewed site hydro-geology, required permitting, conceptual well-field layout and costs to recommend a geothermal system type. Of the two typical system types, standing column wells or closed loop vertical wells, GZA recommended closed loop wells on the basis of regulatory requirements, cost, the client’s risk tolerance and long-term operation and maintenance requirements.

Geothermal Test Well. GZA subcontracted, coordinated, observed, and documented the installation and testing of a closed loop vertical geothermal well to obtain site-specific information regarding drilling conditions, ground temperature and thermal characteristics.

Geothermal Design. With our Certified Geothermal Designer subconsultant, Alderson Engineering, GZA prepared design specifications and plans for the exterior portions of the geothermal system. The design included 50 wells to depths of 500 feet, header and manifold piping, and an approximatley10-foot by 20-foot subsurface vault.

Geothermal Construction Observation. GZA observed the construction of the well-field on a full-time basis to observe whether the contractor was adhering to the plans/specifications. Our services included review of contractor geothermal submittals; observation of the drilling and grouting of individual boreholes, down-hole piping, header and manifold piping, pressure testing and pump tests; and documentation of our installation observations and testing results in weekly field reports. Due to well installation problems, several wells were added to the well field.

Our Geotechnical services included:

Geotechnical Design Report. Based on 14 borings, previous test pits and laboratory testing, GZA prepared a geotechnical report recommending spread footing building foundations with a slab-on-grade. Subsurface conditions consisted of a thin layer of fill over sand/silt over glacial till. GZA also prepared earthwork specifications.

Geotechnical Evaluation of Stormwater Detention Structure Areas. GZA performed additional test pits and borings at 5 stormwater discharge areas, with falling head permeability testing at each boring. Gradation testing of soil samples provided correlations with field permeability testing results.

Design Review of Site Retaining Walls. GZA reviewed contractor-designed mechanically stabilized earth (MSE) site retaining walls. Subsequently, we observed the construction phase was according to the design.

Geotechnical Construction Observation. GZA observed foundation subgrade preparation and backfilling for compaction. Our observations were documented in weekly field reports, including compaction testing results and daily field sketches.

GZA’s client was the project architect, DiMella Shaffer, of Boston, Massachusetts. The Massachusetts Division of Capital Asset Management (DCAM) was the end client.

GZA is proud to have contributed to this innovative project. This project bears out our commitment to sustainable solutions to the built environment. We hope to continue to work on projects that reduce our carbon footprint and provide leadership on the kind of buildings we want for the future.