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Indiana Department of Environmental Management

Indiana Department of Environmental Management


Table of Contents: Water Quality

Cooling Water

Anyone discharging once through non-contact cooling water—water which is used for the sole purpose of removing unwanted heat—only makes one (1) pass through a unit that exchanges heat between the process and the cooling water (generally a heat exchanger); and does not come into contact with industrial processes and materials and is not co-mingled with other wastewater—from a point source into the waters of the state must first obtain a National Pollution Discharge Elimination System (NPDES) permit. Non-contact cooling water discharges are usually permitted under Rule 8 general NPDES permit-by-rule (327 IAC 15-8) although, in some instances the applicant may instead be required to seek an individual NPDES permit (NPDES Form 2E [PDF]).

There are no limitations on the amount of water eligible for discharge under a Rule 8 permit, except that steam electric power generating stations may not discharge under Rule 8. Even a facility operating under an individual NPDES permit may apply to discharge its non-contact cooling water under a Rule 8 permit if that discharge qualifies for a general permit.

Some of the things a discharger must do to comply with requirements for Rule 8 non-contact cooling water discharge include (but are not limited to):

  • Those seeking to discharge under the Rule 8 NPDES General Permit must submit to IDEM a Notice of Intent (NOI) (available on the IDEM Forms page), up to 15 days before the discharge is to commence;
  • Publish a public notice of the intent to comply with the rule in a local newspaper of general circulation, and send a copy of that notice to IDEM along with the NOI;
  • Provide a list of affected parties;
  • Name the receiving stream;
  • Identify the discharge type and location;
  • List all water treatment additives;
  • Include a $50 application fee with the NOI;
  • Monitor, sample, and submit monthly reports regarding discharges made under the Rule 8 permit;
  • Ensure that the mixed receiving stream temperature does not exceed specified maximum limits for more than 1-percent of any 12 month period and never by more than 3 degrees Fahrenheit (which may require holding ponds); and,
  • Apply to renew the permit every five years, 90 days prior to the expiration of permit coverage. The permit is non-transferable.

What to Expect

Upon receipt of the NOI, IDEM will review it for applicability, which takes an average of 50 days, but can take up to 150 days. If the discharge is determined to be eligible under Rule 8, the issuance of an approval letter which contains the permit identification number will be sent to the facility.

However, if chemical additives are used, a determination may be made during IDEM's applicability review that the additives used could cause the cooling water to pose a toxic threat to aquatic life. If such a determination is made, the discharger will instead be required to apply for an individual National Pollution Discharge Elimination System permit. The discharger will then have 120 days to file that application (NPDES form 2E [PDF]), and IDEM will have 180 days, including a 30 day public comment period, to review the application and issue a permit.

Changing Ownership/Transferring

IDEM-issued general NPDES (National Pollutant Discharge Elimination System) permits are not transferable. Therefore, if there is an ownership/operator change at a facility operating under a general NPDES permit-by-rule, the existing permit becomes invalid on the date of the transfer. To avoid being without permit coverage after the transfer, the new owner/operator should plan ahead by submitting an application, known as a NOI (Notice of Intent), for a new permit at least 30 days in advance of the transfer. NOI's should be sent to the mailing address provided below.

For Additional Information:

Similarly, non-contact cooling water discharged into a receiving stream classified as an outstanding state resource or exceptional use water is not eligible for a Rule 8 permit. In that case, the applicant must apply for an individual National Pollutant Discharge Elimination Systems Permit. Obtain a list of outstanding state resource waters (327 IAC 2-1-2(3)) and  exceptional use waters (327 IAC 2-1-11), to secure additional information regarding discharging non-contact cooling water, obtain a Rule 8 NPDES Permit-by-Rule Notice of Intent form or a copy of a NPDES individual permit application NPDES form 2E form for non-contact cooling water discharges.

Questions may be directed to IDEM's OWQ Wastewater Permits staff at (800) 451-6027, ext. 2-8703.

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