Boston Waterfront Redevelopment: Re-Use of Existing Pier Piles to House Future Generations-Paper

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The Pier One redevelopment in East Boston will reuse 14-inch-diameter, concrete-filled steel pipe piles installed in 1955 to support four new 5- to 7-story residential buildings and parking. Because records documenting the piles’ installation and capacity were unavailable, the project team developed a staged load-testing program to determine whether they could safely support design loads of 240 kips—and potentially 300 kips per pile.<br /><br />Static load testing was ruled out because it would require costly reaction piles or heavy dead loads. Instead, the team combined statnamic testing, which provides a direct load measurement, with dynamic testing, a more economical method subject to a higher code-required safety factor. Phase 1 tested two piles at target loads of 200 and 240 kips. Favorable results justified Phase 2, which tested two piles statnamically and ten dynamically at loads targeting the higher design capacity.<br /><br />The piles extend through soft fill and marine clay into dense glacial till and weathered bedrock. Testing showed that resistance came from both shaft friction and end bearing, with end bearing contributing an estimated 50–75% of capacity. Measured movements were generally small, from 0.02 to 0.30 inches. Statnamic ultimate capacities in Phase 2 were about 600 kips; dynamic estimates ranged from 670 to 940 kips. Six piles met the 300-kip design requirement under the applicable safety factor, while several others came close. The limited movement suggests some piles’ full geotechnical resistance may not have been mobilized.<br /><br />Overall, the combined testing program provided a cost-effective basis for reusing the piles. Results indicated average allowable capacities above 300 kips, supporting the project’s feasibility and helping the design team maximize building capacity while accounting for the structural limits of the pile repairs.

Keywords

Pier One redevelopment

East Boston

steel pipe piles

load testing

statnamic testing

dynamic testing

pile capacity

reuse piles

residential buildings

geotechnical resistance