PDCA STEEL MEMBER – STEEL PROJECT
Low Vibration Ductile Iron Piles
Provide a Driven Pile Solution for Urban Sites
IBy Brendan Fitzpatrick, P.E., DuroTerra, LLC n our nation’s capital, only blocks from the White House,
urban redevelopment is taking shape. While many of the new
mixed-use developments show off modern appearances, the
developer of The Adele at 1108 16th Street N.W. was focused on preserving
two stories of the original building façade while expanding
to an eight-story mixed-use (office/luxury condo) development.
Construction of the project was complicated due to the limited
5,025 square foot site bordered immediately by property lines on
three sides and the historic façade at the street. PDCA members
DuroTerra, LLC and design/build contractor GeoStructures, Inc.
provided a unique driven pile solution using TRM’s ductile iron
piles to support the building loads while working in a limited area
where vibration sensitivity was of utmost importance.
Soil conditions at the site investigated by Schnabel Engineering,
Inc. consisted of up to 8.5 feet of mixed fill (sand, silt, gravel, clay
and debris including glass, brick and concrete fragments). The fill
was underlain by terrace deposits ranging from loose to medium
dense sand with varying amounts of fines (SP, SM, SC) and firm
to stiff lean to fat clay (CL, CH) to depths up to 35 feet. In limited
areas, a thin organic silt layer was encountered within the terrace
deposit layers. Loose to very dense residual silty sand and silt was
encountered to depths of 35 to 40 feet followed by weathered rock.
The geotechnical engineer considered numerous deep foundation
options including caissons extending to bedrock, augercast
piles and low vibration driven ductile iron piles. Equipment
access on the tight site and the ability to provide a low vibration
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