7 Catchment Investigations
Once stormwater outfalls with evidence of illicit discharges have been identified, various methods can be
used to trace the source of the potential discharge within the outfall catchment area. Catchment
investigation techniques include but are not limited to review of maps, historic plans, and records;
manhole observation; dry and wet weather sampling; video inspection; smoke testing; and dye testing.
Catchment Investigations shall be completed in accordance with Part 2.3.4.8 of the MS4 Permit and the
City of Nashua Written Catchment Investigation Procedures document.
7.1 MIllicit Discharge Removal
When the specific source of an illicit discharge 1s identified, Nashua will first contact the owner of the
suspect property and will exercise its authority as necessary to require tts removal. The annual report will
include the status of IDDE investigation and removal activities including the following information for
each confirmed soutce:
e The location of the discharge and its source(s)
e Adescription of the discharge
e The method of discovery
e Date of discovery
e Date of elimination, mitigation or enforcement action OR planned corrective measures and a
schedule for completing the illicit discharge removal
e Estimate of the volume of flow removed.
Hic it Discharge Detection and Himination Plan 16
