APPENDIX A - 1_101022_SoilsReport.pdf

This is a Report of Geotechnical Subsurface Exploration for the Hefner VA Medical Center Building 42 Additions & Renovations – Phase II project in Salisbury, North Carolina, prepared by Geoscience Group, Inc. for RPA Design, P.C. on October 20, 2010.

The report documents subsurface conditions at the proposed building addition site through comprehensive field testing including eleven soil test borings (B-1 through B-4 and B-101 through B-107), one offset boring (B-1A), eighteen soft digs (SD-1 through SD-18), and three pressuremeter tests (PM-1, PM-2, PM-3). The project involves constructing two structurally independent, two-story building additions with concrete slab-on-grade floor systems and isolated columns/load-bearing walls. Anticipated column loads range from 75 to 80 kips, with maximum wall loads less than 4 kips per linear foot. The finished floor elevation will match the existing building at 701.42 feet (MSL), requiring fill depths of 1 to 4.5 feet. Key findings indicate existing fill material (up to 14 feet deep) consisting of very silty clay and clayey silt with elevated moisture conditions and variable penetration resistance values of 2 to 14 blows per foot, making it unsuitable for direct building support. Residual sandy silt and silty sand soils underlying the fill extend to approximately 10 to 30 feet below ground surface. The report recommends three foundation alternatives: (1) shallow spread footings with complete removal and replacement of existing fill; (2) deep foundation systems using helical anchors or micro-piles; or (3) undercut floor slab systems with compacted fill placement. Design specifications include a maximum net allowable bearing pressure of 3,000 psf, minimum foundation dimensions (16-inch walls, 24-inch columns), minimum 18-inch depth below finished grade for frost protection, 4-inch ABC stone layer beneath floor slabs, and Site Class C for seismic design. Construction recommendations address site preparation, groundwater management, excavation procedures, fill material requirements (minimum 90 pcf dry density), compaction standards (95 percent Standard Proctor maximum), and shallow footing observation protocols.