PERMIT RATIONALE FOR REISSUANCE
Warren County Port Commission, Ceres Industrial Interplex
Warren County
Vicksburg, Mississippi
Water NPDES No. MS0044202
July 2022

I.	CLASSIFICATION – NPDES Minor Industrial

II.	DESCRIPTION OF WASTEWATER – Pretreated food processing wastewater, sanitary sewage, and miscellaneous industrial wastewater.

III.	DESCRIPTION OF WASTEWATER TREATMENT – Wastewater is biologically treated by means of a 4-cell aerated lagoon system followed by chlorine disinfection and post aeration prior to discharge. Only one discharge to surface waters is described within the application with no increase in treated effluent flow proposed.

IV.	RECEIVING WATERS – Big Black River. The receiving water is located in the Big Black River drainage Basin and is classified as Fish and Wildlife. At the point of discharge, the receiving stream does not appear on the current State of Mississippi 303(d) List of Impaired Waterbodies, nor does the discharge appear on a completed Total Maximum Daily Load (TMDL).

At the point of discharge, the 7Q10 for the receiving stream is 85 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, 1.5 MGD or 2.32 cfs
		 Qr = Receiving stream 7Q10, 85 cfs.

IWC = {(2.32 cfs)/(2.32 cfs + 85 cfs)}*100 = 2.66 %

V.	SUMMARY OF LIMITATIONS - 

Parameter			Value		Basis
Flow				1.5 MGD 		Design
CBOD5			30 mg/l 		WLA
TSS				70 mg/l 		WLA 
Ammonia Nitrogen		18 mg/l 		WLA
E. coli				126 Col./100ml 		MSWQS
pH				6.0 to 9.0 S.U.		MSWQS
Chlorine			0.41 mg/l 		MSWQS, IWC
Dissolved Oxygen		≥ 6.0 mg/l		WLA
Oil and Grease			10 mg/l 		Pervious Permit
Total Nitrogen			Report lbs/day		WLA
Total Phosphorus		Report lbs/day		WLA

VI.	APPLICABLE GUIDELINES – 11 Mississippi Admin Code pt. 6, State of Mississippi Water Quality Criteria (MSWQS), Wasteload Allocation (WLA)

VII.	CHEMICAL SPECIFIC ANALYSIS – 

The chemical specific data results submitted had no detects for all Volatile Organic Compounds and Acid-Extractable Compounds.
	
For Base-Neutral Compounds, the permittee had an average daily concentration for the following compounds: 
	
	Bis (2-ethlyhexyl) Phthalate - Average Daily Concentration: 28 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:

		Bis (2-ethlyhexyl) Phthalate - Human Health Criteria: 0.37 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.

		Bis (2-ethlyhexyl) Phthalate - [11.8 µg/L*10] = 280 µg/L > 0.37 µg/L

Multiplying the above numbers by the IWC for the discharge at the Mean Annual Flow (4,314.5 cfs) further determines the reasonable potential of the compound’s concentration to violate the Human Health Criteria. IWCMA = 0.05 %.
	
	Bis (2-ethlyhexyl) Phthalate - [280 µg/L*0.0005] = 0.14 µg/L < 0.37 µg/L

The above results demonstrate that the average concentrations for Bis (2-ethlyhexyl) Phthalate do not present a reasonable potential to violate Human Health Criteria.

VIII.	CHANGES TO PREVIOUS PERMIT
            
1.	E. coli has replaced fecal coliform as the bacterial indicator for all freshwaters in Mississippi designated as Recreation, Fish and Wildlife Support, and/or Public Water supply. 

2.	Effluent monitoring and reporting requirements for Total Nitrogen and Total Phosphorus have been added to the draft permit.