PERMIT RATIONALE FOR REISSUANCE
Utica POTW, South
Hinds County
Utica,, Mississippi
Water NPDES No. MS0020613
June 5, 2019

I.	CLASSIFICATION –Municipal NPDES Minor 

II.	DESCRIPTION OF WASTEWATER – Municipal Wastewater

III.	DESCRIPTION OF WASTEWATER TREATMENT – Wastewater is collected and treated by means of a conventional lagoon followed by disinfection.  No increase in flow is proposed within the application.  

IV.	RECEIVING WATERS – Unnamed Tributary of White Oak Creek.  The receiving waters are located within the South Independent Streams Basin and are classified as Fish and Wildlife.  White Oak Creek appears on the current State of Mississippi 303(d) list of impaired waterbodies for aquatic life support due to biological impairment. A Fecal Coliform TMDL has been conducted for the Pearl River Basin. The discharge is limited to protect water quality in the receiving stream. The town of Utica diverted all flows from its north lagoon to south lagoon. The north lagoon has been used for an equalization basin, therefore, Utica POTW, North has been terminated from our system. 

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, 0.18 MGD or 0.28 cfs
		 Qr = Receiving stream 7Q10, 0.0 cfs.
IWC = {(0.28 cfs)/(0.28 cfs + 0.0 cfs)}*100 = 100 %

V.	APPLICABLE GUIDELINES – 11 MS admin code part 6, Municipal Facility Guidelines (Technology), Wasteload Allocation (WLA)

VI.	SUMMARY OF LIMITATIONS –
Parameter			Flow				Basis
Flow				0.18 MGD			Design
BOD5				15 mg/l (Monthly Average)	WLA
BOD (Percent Removal)		85% Minimum			Technology
TSS				30 mg/l (Monthly Average)	Technology
TSS (Percent Removal)		85% Minimum			Technology
E. Coli				126 Col./100 ml			11 MS admin code part 6
Chlorine, Total Residual		0.011 mg/l / 0.019 mg/l		11 MS admin code part 6
Dissolved Oxygen 		6.0 Minimum			WLA
pH				6.0 – 9.0 SU			11 MS admin code part 6
NH3-N				2.48 (Monthly Average)		WLA, Toxicity
Total Nitrogen			Report (lbs/day)			WLA
Total Phosphorus		Report (lbs/day)			WLA

E. Coli will now be the bacterial indicator used for all freshwaters in MS designated as Recreation, Fish and Wildlife Support, and /or Public Water supply (replacing the use of fecal coliform).