Cooling Tower Nutrient Monitoring Frequently Asked Questions
(revised November 21, 2012)
Q c1 What is considered to be a Cooling Tower under Regulation #85?
A c1 Cooling towers provide evaporative cooling. Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere. The process waste heat is transferred in a condenser to noncontact cooling water. The heated noncontact cooling water is circulated to the cooling tower structure and sprayed into the airstream. Heat is lost through evaporation. The cooling towers we are interested in handle noncontact cooling water, consistent with the definition in CDPS General Permit for Non-Contact Cooling Water (Permit No. COG-605000). Additional regulatory definitions for noncontact cooling water are found at 40 CFR 401.11 and 423.11. Noncontact cooling water includes the addition of chemical additives to control biological growths, scale or corrosion and does not alter the water's character as "noncontact cooling water." This is distinguished from "once through cooling." The term once through cooling water means water passed through the main cooling condensers in one or two passes for the purpose of removing waste heat." Q c2 A c2
If my facility has a cooling tower, what do I do? Cooling towers have a special two-year monitoring requirement. Existing cooling towers must monitor monthly from November 1, 2012 through October 31, 2014, with a report due on February 28, 2015. New cooling towers would have the same two-year requirement that begins on the date of permit issuance.
Q c3 A c3
If my facility has a cooling tower and has a SIC Group code of 20, what do I do? You must meet the requirements for both the cooling tower (beginning on November 1, 2012) and the general monitoring requirements for your industrial facility (beginning on March 1, 2013).
Q c4
My facility has a cooling tower, and I am required to monitor “inflow, discharge and any added nutrients” of the cooling tower. It is complicated since the outflow from the cooling tower is mixed with outflow from other parts of the facility (e.g. blowdown, circulating water system, low volume waste waters). Where do I sample in this case?
A c4
The intent of this part of the regulation is to determine whether or not discharges from cooling towers are significant sources of increased nutrient loading to the hydrologic system. In order to determine that, the most important locations to monitor are the inflow and the outflow from the cooling tower, before it is mixed with other waste streams. If, because of the layout of the facility, sampling of the cooling tower discharge before it is mixed with other waste streams is not possible, the following data and explanation should be submitted:
Cooling Tower Monitoring Q&A
revised November 21, 2012
o a description of the physical layout and the selected sampling points, including why is was not possible to sample the cooling tower discharge before it is mixed with other waste streams, o a description of the other waste streams that are combined with the cooling tower discharge. o an estimate of the percent of the final treated effluent that originates as cooling tower discharge. o the TN, TIN, TP of the raw water supply o the flow, TN TIN and TP of the final treated effluent Q c5
My facility has a cooling tower, and I am required to monitor “inflow, discharge and any added nutrients” of the cooling tower. Do I have to sample the added nutrients?
A c5
Not necessarily. The requirement to monitor the “added chemical” is meant to get at how much of the increase in concentration was caused by evaporation of pure water and how much was due to “added nutrients”. A calculation (of the added nutrients) based on information from the MSDS can be substituted for the requirement to sample “any added nutrients”, as long as enough information is gathered to quantify the net loading of the facility to the hydrologic system.
Q c6
My facility has a cooling tower, and I am required to monitor “inflow, discharge and any added nutrients.” How often do I have to sample?
A c6
Major facilities must monitor monthly. Minor facilities must monitor bimonthly, unless the frequency that is required for your CDPS permit is quarterly, in which case quarterly is sufficient.
Q c7
If facilities with cooling towers are subject to the monitoring in 85.6(2)(a)[cooling tower two-year requirement] are they still be subject to the requirements in Section 85.6(2)(b) [general nutrient monitoring requirements]
A c7
You may still have to monitor depending on your discharge. If the cooling tower is part of a facility in SIC 20, part of a Domestic WWTF, or if the Division designated the facility, that facility would need to have an ongoing monitoring program as required in 85.6(2)(b).
Q c8. Is the data (nutrient concentration) collected in the river at the intake representative of the water prior to entering the cooling tower? A c8
As long as no other substances are added, concentration at the intake would be adequate.
Q c9
Are pretreatment facilities with cooling towers (i.e. power plants with cooling towers that do not discharge to state waters, but rather discharge to a POTW) subject to this monitoring requirement? The wastewater treatment facility (POTW) has monitoring requirements under Section 85.6(2)(b) already.
Cooling Tower Monitoring Q&A
revised November 21, 2012
A c10 No, the monitoring requirement applies only to direct discharges, so indirect discharges are not subject to monitoring requirements of Regulation #85. Your POTW may have monitoring and reporting requirements that you are subject to. Q c11 My facility has a discharge permit and uses water for cooling (a once-through cooling plant) but does not have a recirculating cooling system. Do I still need to monitor? A c11 No. The monitoring requirement in 85.6(2)(a) applies to discharges from cooling towers(see Qc1 above). However, you may be subject to other monitoring requirements if the facility is in SIC code 20, a Domestic WWTF or if the Division has designated the facility. Q c12 My facility has a discharge permit and has a closed loop cooling system that is not connected to the system that discharges. It does not have a “cooling tower,” per se. Do I still need to monitor? A c12 No, the special two-year monitoring requirement for cooling towers would not apply in this situation. The monitoring requirement in 85.6(2)(a) applies to discharges from cooling towers. However, you may be subject to other monitoring requirements if the facility is in SIC code 20, a Domestic WWTF or if the Division has designated the facility.
Cooling Tower Monitoring Q&A
revised November 21, 2012
