The Illicit Discharge Detection and Elimination (IDDE) Plan is a component of the National Pollutant Discharge Elimination System (NPDES) program described above. This plan outlines how the City will find and eliminate pollutants that are entering the MS4 illegally to ensure that only rainwater and snowmelt go down the storm drain. Pollutants are categorized as anything other than clean rainwater or snowmelt. These ‘illicit discharges’ can enter through a storm drain on a street or parking lot, a pipe from a poorly functioning household sewage treatment system or a home or workplace drain connected to the MS4 instead of the sanitary sewer system.
The primary method that Gahanna uses to monitor pollutants entering its MS4 is dry-weather screening. Inspectors check outfalls, where storm sewer pipes empty to local waterways. If there has been no rain for a few days, and water is flowing from the pipes, where is it coming from? If it is clean, it may be from groundwater infiltration or a small stream that was enclosed in a pipe during development. Unfortunately, it is often from a poorly functioning septic system and is contributing nutrients, detergents and E. coli to a local stream. Other instances of illicit discharge might be washing machines incorrectly draining into basement sumps, car repair or other small business floor drains connected to storm sewer lines and homeowners dumping paint, automotive fluids, dead leaves, pet waste, etc down curbside storm drains.
Another important aspect of the City’s IDDE plan is encouraging residents to report when they see or smell signs of pollutants in local streams or ditches. If you see or smell signs of pollutants please contact the Department of Public Service at 614-342-4005 between 8:00 am and 5:00 pm, Monday through Friday.
For more information and an opportunity to review the IDDE Plan, click here. The City welcomes public comments on the plan. If you are interested in submitting comments, click here.