PERMIT RATIONALE FOR REISSUANCE
Marshall Utility Services LLC, Chickasaw Trail Wastewater Treatment Plant
Marshall County
Byhalia, Mississippi
Water NPDES No. MS0060046
September 29, 2025

I.	CLASSIFICATION - Municipal Major

II.	DESCRIPTION OF WASTEWATER - Domestic

III.	DESCRIPTION OF WASTEWATER TREATMENT - Wastewater is to be biologically treated by means of an activated sludge wastewater treatment facility followed by UV disinfection prior to discharge.  

IV.	RECEIVING WATERS - Nonconnah Creek thence into the Coldwater River.  Nonconnah Creek is in the Yazoo River Basin.  Nonconnah Creek is classified as Fish and Wildlife.  At the point of discharge the receiving stream does not appear on the most recent state of Mississippi 303(d) list of evaluated or impaired waterbodies.  The 7Q10 of the receiving stream at the point of discharge is 1.3 cfs.  The instream wastewater concentration (IWC) 7Q10 at the point of discharge is determined by the following calculation:
		
		IWC 7Q10 = 
Qw = Design flow of the wastewater treatment facility
Qr = Receiving stream 7Q10

IWC calculation for the Marshall Utility Services LLC, Chickasaw Trail Wastewater Treatment Plant is as follows:
Qr = 1.3 cfs
•	Phase I: 
	Qw= 0.45 MGD or 0.70 cfs
		IWC=34.89%
•	Phase II:
	Qw= 1 MGD or 1.54 cfs 
		IWC=54.35%

V.	APPLICABLE GUIDELINES – 

MS Admin Code pt. 6, Municipal Guidelines, Wasteload Allocations (WLAs)

VI.	SUMMARY AND BASIS OF DISCHARGE LIMITATIONS:
The following limitations have been developed through empirical modeling:

	
	Phase I:
	Parameter			Value					Basis
Flow				0.45 MGD (Mo. Avg.)		Design
	BOD5				12 mg/l (Mo. Avg.)	  		WLA
	TSS				30 mg/l (Mo.. Avg.)			11 MS Admin Code
	Ammonia Nitrogen		4 mg/l (Mo. Avg.)			WLA
	E. Coli				126/410 #col/100ml			11 MS Admin Code
	pH				6.0 to 9.0 S.U.				11 MS Admin Code
	Chlorine			0.032 mg/l (Mo. Avg.)	   	WLA
	BOD5  % Removal		85%, Minimum		     	11 MS Admin Code
	TSS % Removal		85%, Minimum		     	11 MS Admin Code
Dissolved Oxygen		6.0 mg/l, Minimum			WLA
D.O., aeration basin		Report					Municipal Guidelines
30-Minute Settleability	Report					Municipal Guidelines
Total Nitrogen			Report					WLA
Total Phosphorus		Report					WLA
	
Phase II:
	Parameter			Value					Basis
Flow				1.0 MGD (Mo. Avg.)			Design
	BOD5				10 mg/l (Mo. Avg.)	  		WLA
	TSS				30 mg/l (Mo.. Avg.)			11 MS Admin Code
	Ammonia Nitrogen		2 mg/l (Mo. Avg.)			WLA
	E. Coli				126/410 #col/100ml			11 MS Admin Code
	pH				6.0 to 9.0 S.U.				11 MS Admin Code
	Chlorine			0.020 mg/l (Mo. Avg.)	   	WLA
	BOD5  % Removal		85%, Minimum		     	11 MS Admin Code
	TSS % Removal		85%, Minimum		     	11 MS Admin Code
Dissolved Oxygen		6.0 mg/l, Minimum			WLA
D.O., aeration basin		Report					Municipal Guidelines
30-Minute Settleability	Report					Municipal Guidelines
Total Nitrogen			Report					WLA
Total Phosphorus		Report					WLA

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

The permittee shall achieve compliance with the effluent limitations specified for discharge in accordance with the following schedule: 

Upon issuance of this permit, the permittee shall achieve compliance with the effluent limitations specified for the parameters noted as Phase I and the ones not noted as phase-specific; Phase II limitations shall not apply at this time.

Beginning upon completion and start-up of improvements to increase the wastewater treatment facility's design flow rate to 1.0 MGD, the permittee shall achieve compliance with the effluent limitations specified for the parameters noted as Phase II and the ones not noted as phase-specific; Phase I limitations shall not apply at this time.  The permittee shall notify our office orally at least 24 hours prior to start-up of the expanded facility and in writing no later than 48 hours after start-up.

Total Residual Chlorine limitations shall only apply when the facility is utilizing Chlorine for disinfection in lieu of UV. If UV disinfection is utilized the permittee shall state NODI = 9 in the discharge monitoring report (DMR).

	The permittee will be required to submit the results from at least three effluent samples of all 	of the pollutants listed in Section D, Expanded Effluent Testing Data, of the Form 2A 	application.  In addition to these three effluent samples, Mississippi Wastewater Regulations  	requires that the influent to and the effluent from the wastewater treatment facility must be 	analyzed twice per month for a 6 month period for the chemicals listed below. Monitoring 	shall begin 90 days after the facility has been discharging for a period of one year at or above 	one (1) MGD, and performed monthly until all samples have been obtained for each 	parameter.  Monitoring results shall be compiled and submitted to Mississippi Environmental 	Quality Board, POSTMARKED NO LATER THAN THE 28TH DAY OF THE MONTH 	FOLLOWING THE SIXTH MONTH OF THIS MONITORING. Please be aware that the 	chemical specific analysis must be performed by a method listed in 40 CFR 136 and with a 	Method Minimum Level (ML) at or below the level of the applicable water criterion for the 	measured pollutant parameter or the method has the lowest ML of the EPA approved 	analytical for the measured pollutant parameter.
Total Recoverable Antimony	
Total Recoverable Arsenic	
Total Recoverable Beryllium	
Total Recoverable Cadmium	
Total Recoverable Chromium	
Chromium (Hex)	
Total Recoverable Copper	
Total Recoverable Lead	
Total Recoverable Mercury	
Total Recoverable Nickel (Freshwater)	
Total Recoverable Selenium	
Total Recoverable Silver	
Total Recoverable Thallium	
Total Recoverable Zinc	
Free Cyanide	
Phenol	
Pentachlorophenol	
Hardness (in mg/l as CaCO3)	

In order to complete the requirements of Section E, Toxicity Testing Data, of the Form 2A application the permittee shall perform the monitoring described in Condition No. M-1 through M-6 of the permit. The toxicity of the effluent as the chronic value (IC25) shall be greater than or equal to 100%. Chronic Bioassay evaluations shall begin 90 days after the facility has been discharging for a period of one year at or above (1) MGD. The chronic bioassay evaluations shall be conducted once per quarter for a period of one year. Monitoring results shall be compiled and submitted to Mississippi Environmental Quality Board, POSTMARKED NO LATER THAN THE 28TH DAY OF THE MONTH FOLLOWING THE COMPLETION OF THIS MONITORING

Attachments

Attachment No. 1 – Wastewater treatment plant flow diagram – See Application
Attachment No. 2 – Discharge location map – See Application
	Attachment No. 3 – Wasteload Allocation (WLA)

Attachment No. 3: Wasteload Allocation (WLA)