PERMIT RATIONALE FOR REISSUANCE WITH MODIFICATION
Raymond POTW
Hinds County
Raymond, Mississippi
Water NPDES No. MS0051772
March 31, 2026

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.	PURPOSE OF MODIFICATION: On March 26, 2026, the facility requested a modification to its permit to reduce the permitted design flow from 0.15 MGD to 0.075 MGD. The effluent limitations contained in this permit have been revised and are based on the reduced design flow of 0.075 MGD. 

VI.	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)

VII.	SUMMARY OF LIMITATIONS –
Parameter				Value					Basis
Flow					0.075 MGD				Design
Ammonia Nitrogen (Phase I)		2 mg/l (Monthly Average)		WLA
Ammonia Nitrogen (Phase II)		1.37 mg/l (Monthly Average)		WLA
BOD5					12 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.

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 notes as Phase I; Phase II limitations shall not apply at this time. 

Phase II limitations shall apply as soon as the treatment system has demonstrated compliance with the Phase II limitations, but no longer than three (3) years after the issuance of the permit; Phase I limitations shall no longer apply at this time. 

The permittee shall submit an engineering report that describes how the facility will come into compliance with the Phase II limitations.