An illicit discharge is defined in the federal regulations as:
...any discharge to an Municipal Separate Storm Sewer Systems (MS4) that is not composed entirely of storm water..."
There are two modes of entry: direct and indirect.
Direct:
Flows in the storm drains created by illicit/improper connections between sanitary sewer and storm drain system
Indirect:
Flows in the storm drains created by pollutants that enter the storm drain system through an inlet or through the joints of the pipe (infiltration)
|
Direct |
• | Sewage cross-connections with storm drains |
• | Straight pipe connections |
• | Industrial and commercial cross-connections with storm drains |
Indirect |
• | Groundwater seepage into the storm drain pipe |
• | Spills that enter the storm drain system at an inlet |
• | Dumping liquid into a storm drain inlet |
• | Outdoor washing activities that create flow to a storm drain inlet |
• | Non-target irrigation from landscaping or lawns that reaches the storm drain system |