problems, including limited (or no) access to the points of entry of
wastewater into the storm sewer systems; multiple sources of
wastewater contamination within the system; and, (iii) detection
programme related limitations, including insufficient manpower,
lack of expertise, limited financial resources, long turn-around
times of sample analyses, poor accuracy and availability of sewer
systems documentation, unreliable equipment or methods used,
etc. (NPDES, 2008). Most of these limitations apply not just to the
wastewater sources, but to the analyses of stormwater as well. To
facilitate the selection of methods for detecting wastewater in
stormwater systems, advantages and limitations of individual
methods are summarized in Table 2.
The limitations of the methods reviewed relate primarily to: a)
the characteristics of the chosen indicator parameters; b) ratio of
the wastewater flow rate to the stormwater flow, (c) the procedure
for detecting the indicator (sensory assessment, grab sampling or
online monitoring); and, (d) practical aspects (resources available).
Further discussion of these limitations follows.