Environmental Engineering Reference
In-Depth Information
and dependable water system. As Washington outgrew the dimensions of a
simple country town, local water sources proved inadequate and, more
often than not, unsafe. To remedy this situation, the Army Corps of Engi-
neers developed an elaborate supply system that drew water from the
Potomac above Great Falls, diverted it to a purifying reservoir near Little
Falls, then conveyed it through a large conduit to Georgetown, where it was
piped to subsidiary reservoirs located in various sections of the city. The
system was improved and expanded repeatedly over the ensuing decades to
keep pace with the city's growing population and geographic expansion.
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The Army Corps of Engineers' most striking environmental intervention
was the radical transformation of the city's relationship with the Potomac,
which involved reconfiguring the depth and breadth of the stream, con-
structing the self-scouring Tidal Basin, and creating extensive expanses of
filled land that are now taken for granted as natural elements of Washing-
ton's topography. By the middle of the nineteenth century, the siltation
problems that had plagued the bend of the Potomac near Washington since
the city's founding had grown intolerable. The decreased water flow and
increased siltation brought on by deforestation and development had
reduced the once-imposing stream into a shallow sheet of water that
expanded and retracted with the tide, exposing hundreds of acres of nox-
ious and intractable mud flats. In addition to drastically curtailing the util-
ity of local harbors, the waterfront morass of swamps and mud flats was
unsightly and unwholesome. The combination of stagnant waters and raw
sewage discharged from the city's rudimentary sanitation system posed sig-
nificant public health hazards. It was frequently pointed out that the exec-
utive mansion was located scarcely more than a stone's throw from this
pestilent slough, posing a constant threat to the president and his family. In
1881 a particularly severe spring flood inundated low-lying reaches of the
city, backing sewage-laden water as far inland as the Botanical Gardens and
convincing Congress that something had to be done to discipline the
unruly river.
During the 1880s the Army Corps of Engineers embarked on an ambi-
tious construction campaign aimed at confining the main flow of the river
to a single clearly defined and navigable channel, draining and filling in the
marshes and tidal flats, and establishing a solid and permanent shoreline.
Steam-operated dredges excavated thousands of tons of sedimentary mate-
rial from the river bottom, transforming the Potomac into a much deeper
but narrower river (figure 6). The dredged material was deposited on the
