PERMIT RATIONALE FOR REISSUANCE
Greenwood POTW
Leflore County
Greenwood, Mississippi
Water - NPDES No. MS0023833
October 8, 2024

FACILITY INFORMATION

Facility Name:  Greenwood POTW
Facility Address:  600 Ione Street 
            Greenwood, MS  38930    
Permit No.:  MS0023833
SIC:  4952, sewerage systems
Permit Writer:  Sandeepa Gill
EPD Branch:  Municipal and Private Facilities Branch

CLASSIFICATION - Municipal Major

DESCRIPTION OF WASTEWATER - Municipal Domestic

DESCRIPTION OF WASTEWATER TREATMENT – Wastewater is collected and treated biologically by means of an activated sludge treatment system followed by UV disinfection.  The current design capacity of the facility is 6.32 MGD.  
RECEIVING WATERS – Yazoo River. The 7Q10 of the receiving stream is 1050 cfs; this along with the facility’s design flow of 6.32 MGD (9.78 cfs) results in an Instream Waste Concentration (IWC) of 0.92%.  The receiving stream is not denoted on the State of Mississippi current List      of Waterbodies for impairment.  Total Nitrogen and Total Phosphorus limitations are included      in the permit to comply with the nutrient TMDL.   

SUMMARY AND BASIS OF DISCHARGE LIMITATIONS – 

	Parameter						Value				Basis
	Flow						6.32 MGD (Monthly Avg.)		Design
	BOD5						30 mg/l (Monthly Avg.)			WLA	
	BOD5 (Percent Removal)			85% Minimum				Technology
	TSS						30 mg/l (Monthly Avg.)			Technology
	TSS (Percent Removal)			85% Minimum				Technology
	NH3-N 						2.0 mg/l (Monthly Avg.)			WLA
	Dissolved Oxygen					> 6.0 mg/l (Monthly Avg.)		WLA
	E. Coli				       126 Col./100 ml				MSWQC
	pH						6.0 – 9.0 SU				MSWQC
	Total Nitrogen						865 lbs/day				TMDL
	Total Phosphorus					311.2 lbs/day				TMDL
	Chlorine						1.0 mg/l (Maximum)			WLA

	MS WQS = Mississippi State Water Quality Standards
	WLA = wasteload allocation for this site 

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

WHOLE EFFLEUNT TOXICITY AND CHEMICAL SPECIFIC EVALUATION

WHOLE EFFLEUNT TOXICITY EVALUATION

In accordance with State Regulation 11 Mississippi Admin Code pt. 6, VI.B.2b., Greenwood POTW 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 Acute Toxicity of Effluents and Receiving Water to Freshwater Organisms.  Short – term acute WET tests were performed on Ceriodaphnia dubia (invertebrate) and Pimephale promelas (vertebrate).  The results of the wet tests are as follows:

			February 2024
			Ceriodaphnia dubia		IC25    		>3.7 %
			Pimephales promelas		IC25   		>3.7 %

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

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

			December 2023
			Ceriodaphnia dubia		IC25     		>3.7 %
			Pimephales promelas		IC25     		>3.7 %

All of the inhibition concentrations were greater that the predicted IWC of 0.92%. Based upon the results of the WET testing, acute bioassay requirements will not be placed within the permit.

Chemical Specific Analysis

Chemical specific analysis has been performed in accordance with State Regulations 11 Mississippi Admin Code pt. 6, 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 4.  The reported values are then analyzed and compared to water quality criteria (see Attachment 5) to determine any possible toxic effect to the receiving waters.  A synopsis of these calculations is listed in Attachment 6.  A column by column description of the calculations in Attachment 6 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 results

Major municipalities shall determine the toxic characteristics of their wastewater by analyzing for toxic pollutants listed in Table III 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. 

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.

For Volatile Organics, the facility had an average daily concentration of 0.00229 mg/l for Chloroform. According to the EPA’s National Recommended: Water Quality Criteria, the Human Health criteria for Chloroform is 0.470 mg/l, Organisms Only. The average concentration, multiplied by the power of 10 (0.00229 mg/l), due to less than 12 samples, does not present a reasonable potential to violate Human Health Criteria.  

Attachments

Attachment 1	See Application
Attachment 2	See Application
Attachment 3	Waste Load Application 
Attachment 4	Tabulated Metals Results 
Attachment 5 	Synopsis of Metals Results 
Attachment 6 	MS State Water Quality Criteria 

Attachment 3 – Wasteload Allocation

Attachment 4

Attachment 5

Attachment 6