PERMIT RATIONALE FOR REISSUANCE
Raymond POTW
Hinds County
Raymond, Mississippi
Water NPDES No. MS0051772
February 22, 2021

I.	CLASSIFICATION –Municipal NPDES Minor 

II.	DESCRIPTION OF WASTEWATER – Domestic/ Municipal Wastewater

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

IV.	RECEIVING WATERS – Fourteen Mile Creek.  The receiving water is located within the Big Black Basin, and is classified as Fish and Wildlife. Fourteen Mile Creek does not appear on the current State of Mississippi 303(d) list of impaired waterbodies, but is included in an Organic Enrichment/ Low D.O. and Nutrient TMDL. The permit is drafted to comply with allocated limits established in the TMDL.

At the point of discharge the 7Q10 for the receiving stream is 0.2 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, 0.15 MGD or 0.23 cfs
		 Qr = Receiving stream 7Q10, 0.2 cfs.

IWC = {(0.23 cfs)/(0.23 cfs + 0.2 cfs)}*100 = 53%

V.	APPLICABLE GUIDELINES – State of Mississippi Wastewater Regulations (11 MS admin code part 6),  State of Mississippi Water Quality Criteria (11 MS admin code part 6), Municipal Facility Guidelines (Technology), Wasteload Allocation (WLA), Total Maximum Daily Load (TMDL), Best Professional Judgment (BPJ)

VI.	SUMMARY OF LIMITATIONS –
Parameter			Value					Basis
Flow				0.15 MGD				Design
Ammonia Nitrogen		2 mg/l (Monthly Average)		TMDL	
BOD5				10 mg/l (Monthly Average)		TMDL
BOD (Percent Removal)	85% Minimum			Technology
Minimum DO			6 mg/l					TMDL
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		Previous Permit
pH				6.0 – 9.0 SU				11 MS admin code part 6
Total Nitrogen 		17.01 lbs/day (Monthly Average)	TMDL
Total Phosphorus		4.57 lbs/day (Monthly Average)	TMDL

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

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).