PERMIT RATIONALE FOR REISSUANCE
Booneville POTW
Prentiss County
Booneville, Mississippi
Water NPDES No. MS0042030
December 5, 2022

I.	CLASSIFICATION – Major Municipal 

II.	DESCRIPTION OF WASTEWATER – Domestic/Municipal Wastewater

III.	DESCRIPTION OF WASTEWATER TREATMENT – Wastewater is biologically treated by means of an oxidation ditch followed by chlorine disinfection then dechlorination. Prior to discharge, the wastewater goes through post-aeration. See Attachment No. 1 for flow diagram. The design capacity of the facility is 2.0 MGD. Only one discharge to surface waters is described in the application with no increase in treated effluent flow proposed.

IV.	RECEIVING WATERS – An unnamed tributary of Tuscumbia River Canal. See Attachment No. 2 for discharge location map. The receiving waters are located in the North Independent Streams Basin and are classified as Fish and Wildlife. The receiving waters do not appear on the current State of Mississippi 303(d) List of Impaired Waterbodies. The discharge does appear on a completed Total Maximum Daily Load (TMDL) for Nutrients and Organic Enrichment / Low DO for Bridge and Elam Creek and Tuscumbia River Canal. The permit has incorporated limits for BOD5, Ammonia Nitrogen, and Dissolved Oxygen in accordance with the WLA developed in the TMDL.  

The 7-day, 10-year minimum flow (7Q10) of the receiving stream is 0.0 cubic feet per second (cfs). The Instream Wastewater Concentration (IWC) at the point of the discharge is 100%, due to the receiving stream having a 7Q10 of 0.0 cfs.

V.	SUMMARY OF LIMITATIONS – 
Parameter			Value		Basis
Flow				2.0 MGD		Design
BOD5				8.5 mg/l		WLA/TMDL
Ammonia Nitrogen		1.0 mg/l		WLA/TMDL
Dissolved Oxygen		6.0 mg/l (Minimum)		WLA
BOD5 % Removal		85 % (Minimum)		Technology
TSS, % Removal		85 % (Minimum)		Technology
E. coli				126 Col./100ml		Admin Code
TSS				30 mg/l 		Technology
Chlorine			0.011 mg/l		WLA
Total Phosphorus		42.0 lbs/day		WLA
Total Nitrogen			192 lbs/day		WLA			
pH 				6.0-9.0 S.U		Admin Code
Copper, Total Recoverable	0.027 mg/l		Application Data
Ceriodaphnia dubia		IC25 ≥ 100% 		Admin Code
Pimephales promelas		IC25 ≥ 100% 		Admin Code

VI.	APPLICABLE GUIDELINES – 11 Mississippi Admin Code pt. 6, Municipal Facility Guidelines (Technology), Wasteload Allocation (WLA, Attachment No. 3),

BIOASSAY AND CHEMICAL SPECIFIC EVALUATION

BIOASSAY

In accordance to State Regulation 11 Mississippi Admin Code pt. 6, VI.B.2b., Booneville 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 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:

August 2021
	Ceriodaphnia dubia		IC25 		>100%
	Pimephales promelas		IC25		>100%

	December 2021
	Ceriodaphnia dubia		IC25 		>100%
	Pimephales promelas		IC25		N/A

	November 2021
	Ceriodaphnia dubia		IC25      	29.23%
	Pimephales promelas		IC25		>100%

	January 2022
	Ceriodaphnia dubia		IC25 		>100%
	Pimephales promelas		IC25		>100%

The above submitted bioassays demonstrated a reasonable potential to violate Whole Effluent Toxicity during a period of four and half years prior to the submittal of the application. Based on the results of the WET testing, chronic bioassay requirements will be placed within the permit.
	
CHEMICAL SPECIFIC ANALYSIS

Chemical specific analysis has been performed in accordance with State Regulations 11Mississippi 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 No. 4.  The reported values are then analyzed and compared to water quality criteria (see Attachment No. 5) to determine any possible toxic effect to the receiving waters.  A synopsis of these calculations is listed in Attachment No. 6.  A column by column description of the calculations in Attachment No. 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 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).
	
For Booneville POTW, the chemical specific data results submitted with the reapplication indicated a reasonable potential for violation of the one of the appropriate criteria (Copper - acute, chronic) in Table III of Appendix D of CFR 122.  See Attachment No. 6 for Chemical Specific Screening sheet and results.

Booneville POTW’s current permitted Total Recoverable Copper limit of 0.024 mg/l was developed from a 2022 chemical translator method for dissolved copper based on a 15th percentile value for Total Suspended Solids (TSS) of 1.6 mg/l and an average hardness of 128mg/l. From the reapplication data and the previous two (2) years of DMR data, the current 15th percentile TSS value and average hardness were found to be 3 mg/l and 132 mg/l, respectively. Using these values to re-confirm the chemical translator study, the average monthly Total Recoverable Copper limit of 0.027 mg/l was confirmed to be protective of the receiving stream. See Attachment No. 7 for copper translator study. 

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

For Volatile Organic Compounds, the permittee had an average daily concentration for the following compounds: 

	Chloroform - Average Daily Concentration: 3.69 µg/L
	Dichlorobromo-methane - Average Daily Concentration: 2.87 µg/L
	Chlorodibromo-methane - Average Daily Concentration: 1.53 µg/L 

According to EPA’s National Recommended Water Quality Criteria, the Human Health Criteria (consumption of organism only) for the following compounds are shown below:

	Chloroform - Human Health Criteria: 2000 µg/L
Dichlorobromo-methane - Human Health Criteria: 27 µg/L
Chlorodibromo-methane - Human Health Criteria: 21 µg/L 

Multiplying the average daily concentrations above by 10 (due to a data set of less than 12 samples) determines the reasonable potential of the compound’s concentration to violate the Human Health Criteria.

Chloroform - [3.69 µg/L*10] = 36.9 µg/L < 2000 µg/L
Dichlorobromo-methane - [2.87 µg/L*10] = 28.7 µg/L > 27 µg/L
Chlorodibromo-methane - [1.53 µg/L*10] = 15.3 µg/L < 10,000 µg/L

The above results demonstrate that the average concentrations for Chloroform, and Chlorodibromo-methane do not present a reasonable potential to violate Human Health Criteria.

The results also demonstrate that the average concentrations for Dichlorobromo-methane do present a reasonable potential to violate Human Health Criteria. The permit will require a full set of twelve (12) samples of Dichlorobromo-methane be submitted to further determine the potential impacts on water quality. 

The chemical specific data results submitted had no detects for all Base-Neutral Compounds and Acid-Extractable Compounds.

ATTACHMENTS

Attachment No. 1 – Flow Diagram
Attachment No. 2 – Map of Discharge Location
Attachment No. 3 – Wasteload Allocation
Attachment No. 4 – Tabulated Metals Testing Data
Attachment No. 5 – MS State Water Quality Standards
Attachment No. 6 – Synopsis of Metals Results
Attachment No. 7 – Copper translator study

Attachment No. 1 – Flow Diagram

Attachment No. 2 – Discharge Location Map

Attachment No. 3 – Wasteload Allocation

Attachment No. 4 – Tabulated Metals Testing Data

Attachment No. 5 – MS State Water Quality Standards

Attachment No. 6 – Synopsis of Metals Results

Attachment No. 7 – Copper translator study