1 IDDE Program Implementation Tim e line
11 MS Pogrm
This Illicit Discharge Detection and Elimination (DDE) Plan has been developed by the City of
Nashua to address the requirements of the United States Environmental Protection Agency’s (USEPA’s)
2017 National Pollutant Discharge Elimination System (NPDES) General Permit for Stormwater
Discharges from Small Municipal Separate Storm Sewer Systems (MS4) in New Hampshire, hereafter
referred to as the “2017 New Hampshire MS4 Permit” or “MS4 Permit.”
The 2017 New Hampshire MS4 Permit requires that each permittee, or regulated community, address
six Minimum Control Measures. These measures include the following:
Public Education and Outreach
Public Involvement and Participation
Illicit Discharge Detection and Elimination Program
Construction Site Stormwater Runoff Control
Stormwater Management in New Development and Redevelopment (Post Construction
Stormwater Management); and
6. Good Housekeeping and Pollution Prevention for Permittee Owned Operations.
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Under Minimum Control Measure 3, the permittee is required to implement an IDDE program to
systematically find and eliminate sources of non-stormwater discharges to 1ts municipal separate storm
sewer system and implement procedures to prevent such discharges. The IDDE program must also be
recorded in a written (hardcopy or electronic) document. This IDDE Plan has been prepared to address
this requirement.
1.2 Illicit Discharges
An “illicit discharge” 1s any discharge to a drainage system that is not composed entirely of stormwater,
with the exception of discharges pursuant to a NPDES permit (other than the NPDES permit for
discharges from the MS4) and discharges resulting from fire-fighting actrvities.
Illicit discharges may take a variety of forms. Illicit discharges may enter the drainage system through
direct or indirect connections. Direct connections may be relatively obvious, such as cross-connections
of sewer services to the storm drain system. Indirect illicit discharges may be more difficult to detect or
address, such as failing septic systems that discharge untreated sewage to a ditch within the MS4, ora
sump pump that discharges contaminated water on an intermittent basis.
Some illicit discharges are intentional, such as dumping used oil (or other pollutant) into catch basins, a
resident or contractor illegally tapping a new sewer lateral into a storm drain pipe to avoid the costs of a
sewer connection fee and service, and illegal dumping of yard wastes into surface waters.
Hic it Discharge Detection and Himination Plan 3
