GZA GeoEnvironmental, Inc. (GZA) was selected through a competitive bid process from six consulting firms to provide geotechnical, environmental and hazardous building materials services for the Manchester Municipal Complex currently under construction. The project involves the redevelopment of three parcels in the center of Manchester. The parcels have experienced several redevelopments dating back to the birth of the City and are currently home to the Manchester Department of Public Works and Manchester Water Works.
GZA performed a combined geotechnical and environmental investigation as well as a hazardous building materials survey to evaluate the subsurface conditions for building foundation support, identify potential soil and groundwater contamination that may be encountered during construction, and assess cost implications of hazardous building materials.
The major geotechnical, or foundation, related issue at the site was the presence of loose sands. GZA recommended densification of the loose sands by partial over excavation and re-compaction which allowed for typical shallow foundation (i.e. spread footing) construction. GZA also improved the site seismic classification by utilizing geophysical testing to perform a shear wave velocity survey. The geophysical survey typically results in a better site classification than correlations developed from test boring information. The revised seismic classification based on the geophysical testing resulted in a significant reduction of building construction costs.
Environmental issues at the site generally consisted of low level urban fill soil contamination from past site uses. GZA developed and implemented a soil and groundwater management program to reduce the amount of off-site disposal of contaminated soils during construction. The management program was submitted to the New Hampshire Department of Environmental Services (NHDES) and was approved for construction. GZA provided construction services which included implementing the soil management program, classifying contaminated soils and providing disposal services for soils that exceeded state standards. GZA was able to provide all inclusive environmental services that were cost effective and efficient.
GZA performed numerous hazardous building material surveys for the multiple building to be razed during construction. The survey included office buildings, maintenance garages, a retail store and a former waste incinerator. GZA evaluated the presence of hazardous materials as well as lead paint and asbestos. GZA also provided remediation cost estimates for budget planning purposes for the abatement and removal of the hazardous materials.
GZA was retained to address numerous issues associated with site development. GZA provided the City with comprehensive geotechnical, environmental, and hazardous building material services that allowed the project to run efficiently. GZA was able to react quickly to the City’s demands and address issues in a proactive manner to minimize surprises and construction costs.