PERMIT RATIONALE FOR REISSUANCE
Duck Hill POTW
Montgomery County
Duck Hill, Mississippi
Water NPDES No. MS0020133
February 2024

I.	CLASSIFICATION – Municipal Minor

II.	DESCRIPTION OF WASTEWATER – Domestic wastewater is generated from the Town of Duck Hill

III.	DESCRIPTION OF WASTEWATER TREATMENT – Wastewater is biologically treated by means of a two-cell lagoon followed by disinfection by chlorination and then by dechlorination prior to discharge. 

IV.	RECEIVING WATERS – Big Bogue Creek. The receiving stream is not listed on the current State of Mississippi 303(d) List of Impaired Waterbodies. The facility is mentioned in a Yalobusha River TMDL for pathogens. The Mississippi Water Quality Standards for E.Coli has been incorporated into the proposed permit and, therefore, should not further impair the receiving waters for pathogens. The receiving stream is located in the Yazoo River drainage basin, and is classified as Fish & Wildlife. At the point of discharge the receiving streams 7Q10 is 4.415 cfs. The instream wastewater concentration at the point of discharge is determined by the following calculation:

IWC = {(QW)/(QW + Qr)}*100

Where, QW = Design flow of the wastewater treatment facility, 0.10 MGD or 0.15 cfs
                  Qr = Receiving stream 7Q10, 4.415 cfs.

IWC = {(0.15 cfs)/(0.15 cfs + 4.415 cfs)}*100 = 3.40%

V.	APPLICABLE GUIDELINES – 11 Mississippi Admin Code pt. 6, Municipal Facility Guidelines (Technology), State of Mississippi Water Quality Criteria (MSWQS), Wasteload Allocation (WLA)

VI.	SUMMARY OF DISCHARGE LIMITATIONS – 
Parameter				Value			Basis
Flow					0.1 MGD			Design
BOD5					30 mg/l (Monthly Average)		WLA
Ammonia Nitrogen			10 mg/l (Monthly Average)		WLA
TSS					90 mg/l (Monthly Average)		Technology
E. Coli				   126 Col./ 100ml			WLA
Chlorine, T.R.				0.011 mg/l			Previous Permit
Dissolved Oxygen, min.		6.0 mg/l			WLA
	pH					6.0 – 9.0 S.U.			WLA
	TSS, % Removal			85 %			Technology
	BOD5, % Removal			85 %			Technology
	Total Nitrogen 		   Report (lbs/day)			WLA
	Total Phosphorus		   Report (lbs/day)			WLA