Malfunction of a combined sewer system is typically a combined sewerage overflow; which may be defined as sewerage flows, from a system, that exceed sewer carrying capacity, thus discharging before treatment and flowing into a water source, or an area in the treatment plant containing treated wastewater.  Causes of such an overflow usually occur during rainfall or snowmelt (EPA, 1995).  Since combined sewer overflows contain a combination of domestic, commercial and industrial wastes, and surface runoff, the contaminants found are myriad, but their effects are all detrimental to the greater overflow area.  Contaminants include, but are not limited to pathogens, toxics, floatables, and pollutants that alter oxygen levels.  The effects from these are contaminated surface water, damaged aquatic habitat(s), threatened drinking water supplies, negatively impacted shellfish harvesting, fish kills, need for beach closure (Posted No Swimming Areas), and an aesthetically unpleasing environment (EPA, 1995).