PERMIT RATIONALE FOR REISSUANCE
Clinton POTW, Southside
Hinds County
Clinton, Mississippi
Water NPDES No. MS0054992
March 26, 2019

CLASSIFICATION

Municipal Major

DESCRIPTION OF WASTEWATER

Domestic/ Municipal Wastewater

DESCRIPTION OF WASTEWATER TREATMENT  

Wastewater is collected and treated by means of an oxidation ditch followed by UV disinfection. 

RECEIVING WATERS

Bakers Creek. The receiving waters, at the point of discharge, are classified as Fish and Wildlife, and are in the Big Black River Basin. This discharge is listed in the TMDL for Pathogens.  The facility utilizes UV disinfection, which complies with the conditions of the TMDL. The discharge is included in a draft TMDL for Fourteen Mile Creek. Nutrient limitations are included in the draft permit to comply with the TMDL. Bakers Creek appears on the current Section 303(d) List of Impaired Water Bodies, for biological impairment.  

The instream wastewater concentration (IWC) 7Q10   at the point of discharge is determined by the following calculation:

IWC calculation for the Clinton POTW, Southside is as follows:

Qw = Design flow of the wastewater treatment facility = 3.5 MGD or 5.42 cfs
Qr =  Receiving stream 7Q10 = 0 cfs
IWC = (Qw/ (Qw + Qr)) * 100 =  (5.42/ 5.42 + 30) =  100 %

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 , Water Quality Criteria (MSWQC), Water Quality Certification” applicable. Wasteload Allocation (WLA), Total Maximum Daily Load (TMDL)

SUMMARY OF LIMITATIONS –

	Parameter						Value				Basis
	Flow						3.5 MGD				Design
	BOD5 						8 MGD				TMDL
	BOD5 (Percent Removal)				85% Minimum				Technology
	TSS						30 mg/l (Monthly Avg.)			Technology
	TSS (Percent Removal)					85% Minimum				Technology
	NH3-N						2 mg/l (Monthly Avg.)			TMDL
	Dissolved Oxygen					> 6.0 mg/l (Monthly Avg.)			WLA
	E. Coli						126 mg/l (Monthly Avg.)			MSWQC
	pH						6.0 – 9.0 SU				MSWQC
	Copper, Total Recoverable			0.024 / 0.033 mg/l 				*
	Zinc, Total Recoverable					0.128 / 0.128 mg/l				Translator Study
	Total Nitrogen						396.9 lbs/day (Monthly Avg.)			TMDL
	Total Phosphorus 					103.4 lbs/day (Monthly Avg.)			TMDL
	Pimephale promelas					100% Minimum				WPC-1
Ceriodaphnia dubia	100% Minimum				WPC-1

The minimum and maximum values for Dissolved Oxygen in aeration unit and 30-Minute Sludge Settleability in aeration unit must be reported

	See attached modeling data results attachment no. 1.

E. Coli will now be the bacterial indicator used for all freshwaters in MS designated as Recreation, Fish and Wildlife Support, and /or Public Water supply (replacing the use of fecal coliform).

*Total Recoverable Copper and limitations are based on the hardness/ chemical translator in which was addressed in the 2005 permit modification. At the request of the permittee the data was also used to recalculate the Total Recoverable Zinc limitations in a 2009 reapplication. In further establishing the Copper criteria the permittee developed a site specific biological translator that relates the existing water quality standard to a specific permit limit using the water effects ratio (WER), as described in EPA guidance (No. 823-B-94-001), and Mississippi Wastewater Regulations (WPC-1,Chpt.2.VI.C.2.a). The study demonstrated that a WER of 24 would protect the designated use of the receiving stream. A WER of 24 gives Total Recoverable Copper monthly average of 0.12 mg/l and maximum weekly average of 0.17 mg/l. It was the determination of MDEQ and EPA to cap the existing Copper load at 0.024 mg/l and 0.033 mg/l based on the facilities previously submitted data. As required by EPA guidance the permittee will be required to perform chronic whole effluent monitoring. The WER study was reconfirmed in 2015, and the facility will be required to reconfirm the study prior to the next reapplication.	

Zinc passed according to the renewal Chemical Specific data submitted with the renewal application, but failed according to the last 2 years of DMR data. Since there is still potential to violate the Zinc, Zinc limits will not be removed from the permit. The hardness/ chemical translator limitation will be reapplied, but adjusted to reflect the data available in the application and the last two years discharge monitoring reports. 	

	

WHOLE EFFLEUNT TOXICITY AND CHEMICAL SPECIFIC EVALUATION

WHOLE EFFLEUNT TOXICITY EVALUATION

In accordance to State Regulation WPC – 1 VI.B.2b, Clinton POTW, Southside is required to perform Whole Effluent Toxicity (WET) tests as part of the renewal application.  The applicant should test in accordance with Short – Term Methods for estimating the Chronic Toxicity of Effluents and Receiving Water to Freshwater Organisms.  Short-term chronic WET tests should be performed on Ceriodaphnia dubia (invertebrate) and Pimephales promelas (vertebrate).

August 2017
Ceriodaphnia dubia					IC25	100%
Pimephales promelas				IC25	100%

January 2018
Ceriodaphnia dubia					IC25	100%
Pimephales promelas				IC25	100%

May 2018
Ceriodaphnia dubia					IC25	100%
Pimephales promelas				IC25	100%

August 2018
Ceriodaphnia dubia					IC25	100%
Pimephales promelas				IC25	100%

All of the inhibition concentrations were greater that the predicted IWC of 100%. WET limitations will be applied to the permit as a condition of the Copper WER. 

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 except for Total Recoverable Copper and Total Recoverable Zinc which addressed above. 
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 Volatile Organics Compounds, Acid-Extractable Compounds, Base-Neutral 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 3
Attachment 5 	Hardness/ Chemical Translator Study Results

Attachment 1

Attachment 2

Attachment3

Attachment 4

Attachment 5