Illicit Discharge Detection and Elimination – The Town of Barnstable has created a plan to systematically find and eliminate sources of non-stormwater discharges to its municipal separate storm sewer system and implement procedures to prevent such discharges. The purpose of this plan is to document the Town’s IDDE program and to assist field staff and program staff with the proper identification, reporting, and resolution of pollution problems. The goals of the IDDE program are to find and eliminate illicit discharges to the municipal separate storm sewer system and to prevent illicit discharges from happening in the future.

An “illicit discharge” is any discharge to a MS4 that is not composed entirely of stormwater except non-stormwater discharges pursuant to a NPDES permit and discharges resulting
from fire-fighting activities.

Common illicit discharges can include the following:
• Sanitary wastewater from crushed, cracked, or collapsed pipes or from surcharges;
• Sewer lines from a house, basement, or individual bathroom to a storm drain;
• Overflow or seepage from septic tanks;
• Cross connections between a sewer or combined sewer line and the storm system;
• Commercial vehicle wash wastewater; and/or
• Improper disposal of automobile and household products.
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 selfpolicing 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 dispose 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/or pathogens to surface waters. Thus, the 2016 MS4 Permit requires a program to identify, locate and remove illicit discharges.