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paradigm
The
sewerage engineering paradigm is firstly based on water-carriage
technology. The struggle between water-carriage technology and
dry conservancy methods of dealing with sewage took place in the
nineteenth century. Water-carriage technology triumphed on the
basis of theories, beliefs and values which were held at that
time.
The
advocates of both water carriage and dry conservancy methods relied
on scientific theories that are largely discredited today. The
water-carriage lobby argued that organic wastes had to be removed
from places of habitation as soon as possible because if they
were given time to putrefy or decompose they would give rise to
`miasmas' or disease producing gases which were responsible for
the spread of diseases such as typhoid. Water-carriage enabled
these wastes to be whisked away immediately whereas dry conservancy
methods required that the wastes be stored about the premises.
The
dry conservancy enthusiasts believed that it was the solid portion
of human wastes which caused the pollution of waterways and which
contained the major part of the nutrients. They were concerned
that these nutrients be utilised to fertilise the land rather
than pollute the waterways. This could be done more effectively
if the wastes were not diluted in water and taken to a centralised
point, but rather retained in their pure or in an improved form
that could be taken to where manure was most needed (Burke, 1873,
p21).
Water-carriage
technology, which was favoured by many, although not all engineers,
involved large scale excavation and construction of sewers as
well as the centralisation of sewage for disposal and brought
sewage disposal within the engineering domain. It was attractive
to the authorities since it made waste disposal a more automatic
procedure and a public rather than an individual responsibility.
It was felt that the individual could not be trusted. As one text
put it,
the
lower classes of people cannot be allowed to have anything to
do with their own sanitary arrangements: everything must be
managed for them.(Corfield, 1871, p118)
The
automatic nature of water carriage as opposed to the labour intensive
nature of most dry conservancy methods which required the wastes
to be regularly collected and carted away was also attractive.
Florence Nightingale observed in an 1870 report
The true key to sanitary progress in cities
is, water supply and sewerage. No city can be purified sufficiently
by mere hand-labour in fetching and carrying. As civilisation
has advanced, people have always enlisted natural forces or
machinery to supplant hand- labour, as being much less costly
and greatly more efficient. (Sewage and Health Board, 1875,
p6)
The
engineering profession, the medical profession and the authorities
made the removal of health-threatening wastes from the cities
and towns their first or at least their most public priority and
considerations of utilising those wastes as fertiliser or preventing
the pollution of waterways were quite secondary, if they were
considered at all.
Dry
conservancy methods did not reach their peak of popularity till
after many sewerage systems were constructed. Their popularity
was a result, in fact, of the pollution of waterways that was
perceived to accompany water-carriage methods. This lateness on
the scene was an immediate drawback since sewers had been installed
and had proven to achieve immediate results in decreasing the
mortality rate in areas where they were installed. Moreover, the
existence of a physical infrastructure of pipes encouraged the
continued use of pipes rather than the scrapping of an expensive
and proven system in favour of a relatively unproven one.
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References:
Burke,
Ulick Ralph, (1873) A Handbook on Sewage Utilization,
2nd ed (London: E & FN Spon).
Corfield, W.H. (1875) Sewerage and Sewage Utilization (New
York: D.Van Nostrand).
Sydney
City and Suburban Sewage and Health Board (1875) Ô2nd Progress
ReportÕ, (Sydney: Sydney City and Suburban Sewage and Health Board).
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