Page 19 - ArchDC_Summer 2020

Much of the building runs along the site’s riverfront side,
Main staircase connecting the lobby
to the second floor, which includes
conference facilities.
Seating area in main lobby.
which faces south, allowing for ample daylighting and river views.
On the eastern side, the building’s siting and shape preserve
a significant line of sight running down Canal Street, SE, to
the river. Windows in that wing of the building provide views
toward another DC Water building located just to the northeast,
on the other side of Canal Street: the Main Street Pumping
Station, a beautiful 1907 Beaux Arts-style structure. The design
for the site reestablishes a long-lost stretch of Canal Street
between the new headquarters building and the 1907 building.
“While the DC Water headquarters stands in stark visual
contrast to the historic Beaux-Arts building, that aesthetic
counterpoint ultimately enhances each,” the firm said. “The
presence of the newer structure, which is diagonally offset
from its older neighbor, actually gives the historic building
greater presence.”
Although it’s not apparent from the boardwalk, the
1960s-era O Street Pumping Station is still there: The new
headquarters building is built directly over the pumping
station’s southern and eastern parts, effectively encapsulating
much of the bland older building and shielding it from view.
“Although the two structures partially overlap, the new
headquarters had to be structurally isolated from the existing
pumping station—both for building code reasons and to
facilitate future modifications to the station without affecting
the headquarters,” SmithGroup said. A five-story, 200-foot-long
steel truss enables the new building to cross over the top of the
shorter existing structure, while the new building’s structural
system “carefully weaves its foundations between the delicate
web of pipes and tunnels below,” the firm said. The older
building’s northwest portion, with its important loading dock,
extends free of the new building.
“Peoples’ jaws drop when they learn there’s a ’60s-era pump
station under the new building,” said Don Posson, PE, CCP,
CPD, LEED AP, GGP, the lead engineer for the project.
Extensive computer modeling was used to refine the new
building’s form, with an eye toward managing solar heat gain.
“SmithGroup used a variety of digital tools, allowing the
firm to explore an unusually wide range of design options,”
the firm said. “The process involved upwards of 20 different
pieces of software, including familiar architectural programs
such as Revit and Rhino, as well as state-of-the-art parametric
workflows that facilitated precise geometrical manipulation
and data-sharing across applications in real time. This heavy
reliance on digital media afforded the designers a high degree
of creative flexibility without compromising constructability.”
As one result of the computer modeling, each floor on the
building’s south-facing riverfront side projects out two feet more
than the floor underneath, providing some shading for interior
spaces in summer while admitting the sun’s rays in winter.
Window tinting further reduces summer heat gain. At two
points on the riverfront side where the façade bends outward,
computer modeling predicted particularly strong heat gain. To
address that issue, those two locations feature an additional
layer of protective glass that is suspended in the open air three
feet in front of the main curtain wall, with the gap sized to
permit access by window washers. The glass in this second layer
“is tinted in three different shades of green to provide subtle
variation, and is also fritted [with a ceramic coating] to further
reduce solar gain,” the firm said.
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