Micropiles: Key To The Renovation Of The 161 First Street Building-Video

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The renovation of 161 First Street in Cambridge converted a 1907, four-story former factory into office space. Severe foundation cracking and decayed timber piles ruled out the original helical-pile design; underpinning was also impractical because of contaminated soil and site constraints. The team instead installed 163 drill micropiles to support the interior columns and exterior walls.<br /><br />Because soil data was limited, a nearby pilot test measured bond strength across sand, clay, and glacial till. The results exceeded expectations, allowing the team to shorten the piles by 21%—saving about 2,100 linear feet of drilling and reducing costs, schedule, and spoil handling.<br /><br />Construction took place in a confined basement with low overhead, contaminated soil, groundwater, and limited access. Specialized compact electric drill rigs and a soil-separation system enabled safe drilling and management of wet, contaminated spoils. Careful sequencing and daily coordination among the contractor, engineers, and crews were key to completing the work successfully.

Keywords

micropiles

foundation renovation

underpinning

contaminated soil

Cambridge factory conversion