PERMIT RATIONALE FOR REISSUANCE
Tunica County Utility District, Dundee Facility
Tunica County
Dundee, Mississippi
Water NPDES No. MS0058165
October 2023

I.	FACILITY INFORMATION

Facility Name:  Tunica County Utility District, Dundee Facility
Facility Address:  9140 Dundee Road 
Dundee, MS  38626    
Robinsonville, 
Permit No.:  MS0058165
SIC:  4952
Permit Writer:  Christiana Boren
EPD Branch:  Municipal and Private Facilities

II.	CLASSIFICATION – NPDES Minor Municipal

III.	DESCRIPTION OF WASTEWATER – Domestic Wastewater

IV.	DESCRIPTION OF WASTEWATER TREATMENT – Wastewater is collected and treated by means of an extended aeration activated sludge system followed by chlorine disinfection prior to discharge. Only one discharge to surface waters is described in the application with no increase in treated effluent flow proposed. 

V.	RECEIVING WATERS – Unnamed Tributary of Cypress Lake. The receiving waters are located in the Yazoo River drainage basin and are classified as Fish and Wildlife. At the point of discharge, the receiving waters do not appear on the current State of Mississippi 303(d) List of Impaired Waterbodies, nor does the facility appear on a completed Total Maximum Daily Load (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, 0.05 MGD or 0.078 cfs
		 Qr = Receiving stream 7Q10, 0.0 cfs.

IWC = {(0.078 cfs)/(0.078 cfs + 0.0 cfs)}*100 = 100 %

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

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			Flow			Basis
Flow				0.05 MGD		Design
BOD5				10 mg/l 		WLA
BOD (Percent Removal)	85% Minimum	Technology
Minimum DO			6 mg/l			WLA
TSS				30 mg/l 		Technology
TSS (Percent Removal)	85% Minimum	Technology
NH3-N	Phase I			2 mg/l 			WLA
NH3-N	Phase II		1.37 mg/l 		WLA
E. coli				126 Col./100 ml	Admin Code
Chlorine, Total Residual	0.011 mg/l 		WLA
pH				6.0 – 9.0 SU		Admin Code
Total Nitrogen			Report lbs/day		WLA
Total Phosphorus		Report lbs/day		WLA

The minimum and maximum values for Dissolved Oxygen in the aeration basin, 30-Minute Sludge Settleability in the aeration basin, and influent pH must be reported.