Geotechnical Report 1 of 8 A0004.pdf

This is a Geotechnical Engineering Evaluation Report prepared by R.W. Gillespie & Associates, Inc. for the West Roxbury VAMC Replace Boiler & Upgrade Controls project at the Veterans Administration Boston Healthcare System facility in West Roxbury, Massachusetts. The evaluation was conducted under Purchase Order No. RWG&A 0506-0012 #00 dated June 1, 2021, to support design and construction of a new central boiler plant building with emergency generator and substation rooms, along with demolition and replacement of portions of Building No. 8. The report documents subsurface conditions through ten test borings (B-1 through B-10) advanced to depths of 21 to 32 feet below ground surface during July 2021, supplemented by laboratory testing including particle-size distribution, moisture content determination, and rock core compressive strength analysis.

The subsurface conditions consist of topsoil and organic material (0.5 to 1.2 feet thick), bituminous concrete pavement (0.2 to 0.8 feet), and fill materials of sand with gravel (3.5 to 11.7 feet) overlying dense sand and gravel deposits (5.7 to 34 feet) with refusal surfaces encountered in borings B-6 and B-7 at depths of 14.7 and 31.3 feet respectively. Groundwater was observed at 3 to 16 feet below surface with estimated probable high water level of approximately 98.7 feet elevation. The report recommends two foundation and ground floor support alternatives: full-depth fill removal and replacement with compacted structural fill supporting spread or continuous footings and slab-on-grade floors, or micropile support in bedrock with design parameters specified for compression and tension loads. The recommendations include detailed specifications for site preparation, fill removal and replacement, foundation drainage, temporary excavations, construction vibration control, and geotechnical observation during construction, with compliance required to the 2018 International Building Code and Massachusetts State Building Code requirements.