Which type of SSO typically poses the least risk to public health?

Category 4 SSOs, or Sanitary Sewer Overflows, typically pose the least risk to public health. These overflows are characterized by minor incidents that usually involve small volumes of sewage and occur in designated areas where they are unlikely to impact the general public or the environment significantly. They may happen in confined spaces or areas where there is limited human exposure.

Since Category 4 SSOs generally involve minimal quantities of sewage and are often quickly contained and cleaned up, they represent a reduced risk compared to other categories, which may involve larger volumes or occur in more public and accessible settings. The classification system for SSOs is designed to help municipalities prioritize response efforts and preventive measures based on the potential health risks associated with different types of spills.