The Industrial Waste Survey (IWS) is the effort made to ensure that the POTW's list of Industrial Users and the pollutants in their wastestreams are current, and to determine which, if any, of the Users have the potential to adversely affect the WWTP and its receiving environments and should become Significant Industrial Users (SIU), or otherwise might need regulation as a non-SIU. The Significant Industrial User criteria are found in 15A NCAC 02H .0903(b)(33) and are listed below.
The IWS includes procedures for on-going IWS activities to identify new and changed Users between IWS submissions to the NPDES Municipal Permitting Unit. NC POTWs must submit a summary of their IWS activities to NPDES Municipal Permitting Unitat least every 5 years. An Industrial User is a SIU if the facility:
- Discharges an average of 25,000 gallons or more per day of process wastewater to the POTW (excluding sanitary, noncontact cooling and boiler blowdown wastewaters) or;
- Contributes more than 5 percent of the NPDES or non-discharge permitted flow limit or organic capacity of the POTW treatment plant (In this context, organic capacity refers to BOD, TSS and ammonia), or;
- Is subject to categorical standards under 40 CFR Part 403.6 and 40 CFR Parts 405-471, or;
- Is, regardless of Parts (1), (2), and (3) above, otherwise determined by the control authority to have a reasonable potential for adversely affecting the POTW's operation or for violating any pretreatment standard or requirement or POTW's receiving stream standard, or to limit the POTW's sludge disposal options.
**Call your pretreatment contact for copies of NC Manufacturers Register pages pertaining to your POTW and any satellite communities served.**
- Chapter 3: Industrial Waste Survey of the Comprehensive Guidance for North Carolina Pretreatment Programs (Comprehensive Guide) (Chapter 3 last updated April 2005).
- Categorical User Webpage for more information on Federal Categorical Regulations and determining if a given User is subject to them.