Title: PERMIT RATIONALE
Author: Preferred Customer
Last saved by: Christiana Boren
Company: Dell Computer Corporation

PERMIT RATIONALE FOR REISSUANCE
Tutwiler POTW
Tallahatchie County
Tutwiler, Mississippi
Water NPDES No. MS0025054
March 2024

I.	FACILITY INFORMATION

Facility Name:  Tutwiler POTW
Facility Address:  Highway 49 East 
Tutwiler, MS  38963    
Tutwiler, 
Permit No.:  MS0025054
SIC:  4952
Permit Writer:  Christiana Boren
EPD Branch:  Municipal and Private Facilities

II.	CLASSIFICATION – NPDES Minor Municipal

III.	DESCRIPTION OF WASTEWATER – Domestic/Municipal

IV.	DESCRIPTION OF WASTEWATER TREATMENT – Wastewater is biologically treated by means of an oxidation ditch followed by chlorine disinfection, dechlorination, and post-aeration prior to discharge. The current design capacity of the facility is 0.75 MGD. Only one discharge to surface waters is described in the application with no increase in treated effluent flow proposed. 

V.	RECEIVING WATERS – Hopson Bayou. The receiving stream is located in the Yazoo River drainage basin and is classified as Fish & Wildlife. At the point of discharge, the receiving stream does not appear on the current State of Mississippi 303(d) List of Impaired Waterbodies. The facility is listed in a completed Total Maximum Daily Load (TMDL) for Fecal Coliform in Cassidy Bayou (March 2008). The facility disinfects, which complies with the conditions of the TMDL. The facility is also listed in a completed TMDL for Nutrients and Organic Enrichment/Low Dissolved Oxygen in Hopson Bayou (June 2008). The draft permit contains nutrient limitations prescribed by the TMDL.

At the point of discharge, the 7Q10 for the receiving stream is 0.0 cfs.  The instream wastewater concentration at the point of discharge can be determined by the following calculation:
IWC = {(Qw)/(Qw + Qr)}*100

Where, Qw = Design flow of the wastewater treatment facility, 0.75 MGD or 1.16 cfs
       Qr = Receiving stream 7Q10, 0.0 cfs.

IWC = {(1.16 cfs)/(1.16 cfs + 0.0 cfs)}*100 = 100 %

VI.	APPLICABLE GUIDELINES – 11 Mississippi Admin Code pt. 6, Municipal Facility Guidelines (Technology), Wasteload Allocation (WLA), TMDL

VII.	CHANGES FROM PREVIOUS PERMIT – 

The discharge limit for Total Ammonia Nitrogen has been changed from 2 mg/L to 1.37 mg/L based on the results of a Waste Load Allocation. 

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 without a phase designation and for the parameters noted as Phase I; Phase II limitations shall not apply at this time.

Beginning upon completion and start-up of improvements needed to comply with Phase II limitations or three (3) years after the issuance of the permit, whichever comes first, the permittee shall achieve compliance with the effluent limitations specified for the parameters without a phase designation and for the parameters noted as Phase II; Phase I limitations shall no longer apply at this time. 

The permittee shall notify our office orally at least 24 hours prior to start-up and in writing no later than 48 hours after start-up.

VIII.	SUMMARY OF DISCHARGE LIMITATIONS – 
Parameter				Value		Basis
Flow					0.75 MGD		Design
BOD_5					10 mg/l 		WLA
TSS					30 mg/l 		Technology
Ammonia Nitrogen (Phase I)		2 mg/l 		WLA
Ammonia Nitrogen (Phase II)		1.37 mg/l 		WLA
E. coli					126 col/100 ml		Admin Code
Chlorine, Total Residual		0.011 mg/l		WLA
Dissolved Oxygen			6.0 mg/l (Minimum)	WLA
pH					6.0 – 9.0 SU		Admin Code
Total Nitrogen				71.98 lbs/day		TMDL
Total Phosphorus			32.55 lbs/day		TMDL
TSS % Removal			85%		Technology
BOD_5 % Removal			85%		Technology

13423 PER20240001