Some illicit discharges are related to the unsuitability of original infrastructure to the modern regulatory
environment. Examples of illicit discharges in this category include connected floor drains in old
buildings, as well as sanitary sewer overflows that enter the drainage system. Sump pumps legally
connected to the storm drain system may be used inappropriately, such as for the disposal of floor
washwater or old household products, in many cases due to a lack of understanding on the part of the
homeowner.
Elimination of some discharges may require substantial costs and efforts, such as funding and designing
a project to reconnect sanitary sewer laterals. Others, such as improving self-policing of dog waste
management, can be accomplished by outreach in conjunction with the minimal additional cost of dog
waste bins and the municipal commitment to disposal of collected materials on a regular basis.
Regardless of the intention, when not addressed, illicit discharges can contribute high levels of
pollutants, such as heavy metals, toxics, oil, grease, solvents, nutrients, and pathogens to surface waters.
1.3. Allowable Non-Stomwater
Disc harges
The following categories of non-storm water discharges are allowed under the MS4 Permit unless the
permittee, USEPA identifies any category or individual discharge of non-stormwater discharge as a
significant contributor of pollutants to the MS4:
e Water line flushing e Irrigation water, springs
e Landscape irrigation e Water from crawl space pumps
e Drverted stream flows e §=Footing drains
e Uncontaminated ground water e Lawn watering
infiltration (as defined at 40 CFR e = Individual resident car washing
35.2005(20)) e De-chlorinated swimming pool
e Uncontaminated pumped groundwater discharges
e Discharge from potable water sources © Street wash waters
e Foundation drains e Residential building wash waters
e Air conditioning condensation without detergents
If these discharges are identified as significant contributors to the MS4, they must be considered an
“llicit discharge” and addressed in the IDDE Plan (1.e., control these sources so they are no longer
significant contributors of pollutants, and/or eliminate them entirely).
Hic it Discharge Detection and Himination Plan 4
