PERMIT RATIONALE FOR REISSUANCE
Jackson County Utility Authority, POTW 1C
Jackson County
Ocean Springs, Mississippi
Water NPDES No. MS0045446
November 18, 2024

CLASSIFICATION - Municipal Major

DESCRIPTION OF WASTEWATER - Domestic/ Municipal Wastewater

DESCRIPTION OF WASTEWATER TREATMENT   - Wastewater is collected and treated biologically via aerated lagoons followed by constructed wetlands, chlorine disinfection, and dechlorination.  See application for flow diagram.

RECEIVING WATERS - Costophia Bayou.  The receiving stream is located within the Coastal Stream Basin, and is classified as Fish and Wildlife. Costophia Bayou does not appear in the current State of Mississippi’s 303(d) list for impaired waterbodies. The discharge is listed in a pathogen TMDL. The facility disinfects the effluent in order to comply with State criteria for pathogens, which complies with the TMDL. See application for discharge location map.

APPLICABLE GUIDELINES - Mississippi Wastewater Regulations (11 MS admin code part 6), State of Mississippi Water Quality Criteria & “Wastewater Regulations for National Pollutant Discharge Elimination System Permits, Underground Injection Control Permits, State Permits, Water Quality Based Effluent Limitations , Wasteload Allocation (WLA), Total Maximum Daily Load (TMDL), Jackson County Utility Authority Translator Study (JCUA TS)

SUMMARY OF LIMITATIONS –

Parameters				Value				Basis
Flow				7 MGD				Design
BOD5				10 mg/l				WLA
BOD5 (Percent Removal)		85% Minimum			Technology
TSS				30 mg/l				Technology 
TSS (Percent Removal)		85% Minimum			Technology
NH3-N (Phase I)			5.25 mg/l 			WLA/Toxicity
NH3-N (Phase II)			1.39 mg/l 			WLA/Toxicity
E. Coli				126 Col./100 ml	 		Admin code
Dissolved Oxygen			6.0 mg/l (Minimum)		WLA
Total Residual Chlorine		0.011/0.019 mg/l		Admin code
pH					6.0 - 9.0 SU			Admin code
Total Nitrogen			Report				*
Total Phosphorus			Report				*
Total Recoverable Copper		0.009 mg/l (Avg. monthly)	Translator Study
	       Ceriodaphnia dubia				     100 % Minimum		Admin. code
	       Pimephale promelas		          100 % Minimum		Admin. code

BOD5, NH3-N and DO limits are based on the Wasteload Allocation and modeled for oxygen depletion in the receiving stream, and the toxicity limit for NH3-N and Cl2 were determined for the parameters that are potentially acutely and chronically toxic. The more stringent of the modeled limit and the toxicity limit (for NH3-N) is what is given in the Wasteload Allocation, to meet Water Quality Based Effluent Limitations (WQBELs).

Permit application data for Total recoverable copper was taken and placed into the Chemical Specific Screening Calculations. It did not exceed the water quality standards. The Copper Translator Study that was also performed during this current reissuance (see attachment no. 5). We also reviewed the DMR/Historic Data from the previous two years. Total Recoverable copper meets with their current 0.009/0.012 mg/l limitation and therefore, the previous limit will remain in the current permit. 

This current permit also contains the phased limitations for Ammonia Nitrogen based on ammonia toxicity. Upon issuance of this permit, the permittee shall achieve compliance with the effluent limitations specified for the parameters without a phase designation and for the parameters notes as Phase I; Phase II limitations shall not apply at this time. Phase II limitations shall apply as soon as the treatment system has demonstrated compliance with the Phase II limitations, but no longer than five (5) years after the issuance of the permit; Phase I limitations shall no longer apply at this time. 

The permittee shall submit an engineering report that describes how the facility will come into compliance with the Phase II limitations.

All previously permitted parameters have remained the same in the reissuance.

WHOLE EFFLEUNT TOXICITY AND CHEMICAL SPECIFIC EVALUATION

WHOLE EFFLEUNT TOXICITY EVALUATION

In accordance to State Regulation 11 Mississippi Admin Code pt. 6, VI.B.2b., Jackson County Utility Authority, POTW 1C is required to perform a Whole Effluent Toxicity (WET) evaluation as part of the renewal application. The applicant was to have tested in accordance with Short – Term Methods for estimating the Chronic Toxicity of Effluents and Receiving Water to Freshwater Organisms. Short–term chronic WET tests were performed on Ceriodaphnia dubia (invertebrate) and Pimephale promelas (vertebrate). The results of the wet tests are as follows:

March 2023
	Ceriodaphnia dubia					IC25	>100%
	Pimephales promelas					IC25	>100%

August 2023
	Ceriodaphnia dubia					IC25	>100%
	Pimephales promelas					IC25	>100%

November 2023
	Ceriodaphnia dubia					IC25	4.51%
	Pimephales promelas					IC25	>100%

January 2023
	Ceriodaphnia Dubia					IC25   >100%

March 2024
	Ceriodaphnia dubia					IC25	>100%
	Pimephales promelas					IC25	>100%

Based on the results of the WET testing, all inhibition concentrations were not greater that the predicted IWC of 100%.  Chronic bioassay requirements will be placed within the permit.

Chemical Specific Analysis

Chemical specific analysis has been performed in accordance with State Regulations WPC-1 V1.B1.  Municipalities shall determine the toxic characteristics of their wastewater by analyzing for the toxic pollutant listed in Table III of appendix D of 40 CFR 122.  The results are tabulated in attachment No. 2.  The reported values are then analyzed and compared to water quality criteria (attachment No. 4) to determine any possible toxic effect to the receiving waters.  A synopsis of these calculations is listed in attachment No. 3.  A column by column description of the calculations in attachment No. 5 is hereby provided:

Column No. 1 – Maximum concentration.  The highest effluent reading of the parameter

Column No. 2 – The maximum concentration mixed with the receiving water IWC.  This     is calculated by the following equation:

{Maximum Concentration (Column 1) * IWC %} / 100

Column No. 3 – Acute allowable – Chemical Specific State Water Quality Criteria                                   
	Column No. 4 – Pass or Fail. If column 2 > column 3 water quality criteria is exceeded                              and failure occurs.

Column No. 5 – Long term average (LTA) of all tests.  The summation of the 12 samples divided by 12.

Column No. 6 – The long term average concentration mixed with the receiving water                                  IWC.  This is calculated by the following equation:

{LTA Concentration (Column 5) * IWC%} / 100

Column No. 7 – Chronic allowable – Chemical Specific State Water Quality Criteria                                   
Column No. 8 – Pass or Fail. If column 6 > column 7 water quality criteria is exceeded                                and failure occurs.

Column No. 9 – Human health determination.  Long term average (Column 5) is mixed                with the mean annual flow IWCMA .  This is calculated by the following                            equation:

{LTA Concentration (Column 5) * IWCMA %} / 100

Column No. 10 – Human health allowable – State Water Quality Criteria   Note: Organisms only column is used if receiving waters are not drinking water supply. 

	Column No. 11 – Pass or Fail.  If column 9 > column 10 water quality criteria is exceeded                        and failure occurs.

Chemical Specific Analysis for Metals and Results

Major municipalities shall determine the toxic characteristics of their wastewater by analyzing for toxic pollutants listed in Table II of Appendix D of 40 CFR 122.  Metal analysis shall be for total recoverable metals.  Municipalities shall submit twelve influent and effluent samples collected.  Chemical specific limits shall be placed in a permittee’s permit if any of the parameters evaluated in the toxic screening procedure indicate the reasonable potential for violation of the appropriate criteria (acute, chronic, and human health).
	
The chemical specific data results submitted did not indicate the reasonable potential for violation of the appropriate criteria in Table III of Appendix D of CFR 122. Total Recoverable Copper will remain in the permit due to copper translator study. 

Chemical specific analysis for Volatile Organics Compounds, Acid-Extractable Compounds, and Base-Neutral Compounds and Results

The chemical specific data results submitted had no detects for Acid-Extractable Compounds.

Attachments
Attachment 1	Waste Load Application 
Attachment 2	Tabulated Metals Results 
Attachment 3 	Synopsis of Metals Results 
Attachment 4 	MS State Water Quality Criteria 
Attachment 5	Copper Translator Study

Attachment 1

Attachment 2

Attachment3

Attachment 4

Attachment 5