Metronatural: Inventing and Taming Nature in Seattle - Politics of Urban Runoff: Nature, Technology, and the Sustainable City - page 103

Table 5.1
Total miles of sanitary sewer in Seattle, 1891-1950

Year Total miles Year Total miles

1891 14.9 1930 802.10

1900 60.45 1940 863.15

1908 212.32 1950 988.09

1924 628.63

Source : Brown and Caldwell 1958.

his proposed separated sewer plan. They solicited a second sewer design
from Chicago engineer Benezette Williams, who recommended a system
with much larger capacity but also combined the sanitary and stormwater
volumes in a single pipe. The municipality approved Williams's combined
sewer design and construction on the system began in 1890. 65
After being appointed as city engineer, Thomson assessed the Williams
plan and largely adopted it but made one signifi cant change: instead of
discharging untreated sewage volumes into Lake Union and Lake Wash-
ington, he called for deep outfalls in Puget Sound. He felt that the lakes
had insuffi cient capacity to absorb the pollutant loads from the growing
city, a far-sighted observation at the time. Under his guidance, the city
built two massive trunk sewers in the 1890s and went on to build a com-
prehensive combined sewer system that is still used today in the central
core of the city (see table 5.1). 66 However, Thomson's embrace of Wil-
liams's combined sewer design would be a costly mistake, due to future
requirements for wastewater treatment as well as signifi cant increases
in stormwater volumes from impervious surfaces in the city. Like all in-
frastructure champions of this time period, he could not anticipate the
changing material and cultural conditions of the city that would create
unintended problems in the future.

Engineering the Landscape for Economic Development

Designing and constructing water and sewer systems were enormous en-
deavors at the turn of the twentieth century and required massive amounts
of funding as well as the mastery of engineering techniques that were
changing rapidly. 67 However, the building of Seattle's water and sewer
networks would pale in comparison to Thomson's most famous engineer-
ing project. Surveying the landscape of the city, he noted a preponderance
of hills and recognized them as an impediment to growth. In his memoirs,