5
applicable in communities where hardness levels are elevated in groundwater
due to karst or limestone terrain. In these regions, hardness can help
distinguish natural groundwater
fl
ows present in outfalls from tap water and
other
fl
ow types.
pH
Most discharge
fl
ow types are neutral, having a pH value around 7, although
groundwater concentrations can be somewhat variable. pH is a reasonably
good indicator for liquid wastes from industries, which can have very high or
low pH (ranging from 3 to 12). The pH of residential wash water tends to be
rather basic (pH of 8 or 9).
The pH of a discharge is very simple to monitor in the
fi
eld with low cost test
strips or probes. Although pH data is often not conclusive by itself, it can
identify problem outfalls that merit follow-up investigations using more effective
indicators. Normal rainwater has a pH of approximately 5.6
Potassium
Potassium is found at relatively high concentrations in sewage, and extremely
high concentrations in many industrial process waters. Consequently,
potassium can act as a good
fi
rst screen for industrial wastes, and can also be
used in combination with ammonia to distinguish wash waters from sanitary
wastes.
Turbidity
Turbidity is a quantitative measure of cloudiness in water, and is normally
measured with a simple
fi
eld meter. While turbidity itself cannot always
distinguish between contaminated
fl
ow types, it is a potentially useful screening
indicator to determine if the discharge is contaminated (i.e., not composed of
tap water or groundwater).
