Raleigh, Wake County, North Carolina
GTA provided geotechnical and environmental services associated with the redevelopment of two adjacent parcels in downtown Raleigh, previously occupied by an abandoned warehouse and surface parking, into a new 10-story, pre-cast concrete parking structure. During project planning and design, GTA performed geotechnical services including a subsurface exploration including SPT soil borings, rock coring, deep foundation design (drilled=shaft), lateral foundation (L-Pile) analysis, and shear wave velocity testing for seismic site classification. Additionally, GTA performed environmental services for the project including a Phase I Environmental Site Assessment (ESA), Phase II ESA soil and groundwater sampling, and asbestos and lead-based paint surveys. Also, the site was accepted into the North Carolina Brownfield program, and GTA worked with the project team and NCDEQ to develop a Brownfield Work Plan, and Environmental Management Plan (EMP).
During construction, GTA performed field observations, testing, and sampling in accordance with the EMP to assist the contractor in segregating impacted soils during earthwork and deep foundation construction. GTA assisted the project team in documenting the impacted-materials hauled off-site and performed confirmation sampling of import material delivered to the site and performed waste characterization sampling for acceptance of the impacted-material to an appropriate disposal facility. GTA provided construction observation testing and Special Inspection services during deep foundation (drilled-shaft) construction and provided real-time shaft capacity evaluations during installation drilling/construction to help the contractor/owner minimize cost impacts and delays associated with a variable and fractured rock profile and thick weathered-rock layer at the site, resulting in significant cost savings to the owner. Due to the variable rock and groundwater conditions at the site, drilled-shaft installation during construction was changed from an open-hole installation method to a slurry installation method to help expedite construction. GTA monitored the properties of the slurry used in the drilled-shaft construction to determine if the slurry met the project specifications. Construction elements of the parking deck include the drilled shaft foundation system, concrete slab-on-grade lower level, and pre-cast concrete elevated construction. GTA also performed vibration monitoring during foundation construction.