PERMIT RATIONALE FOR REISSUANCE
Arcola POTW
Washington County
Arcola, Mississippi
Water NPDES No. MS0037311
October 2023

I.	CLASSIFICATION –Municipal NPDES Minor 

II.	DESCRIPTION OF WASTEWATER – Domestic/ Municipal Wastewater

III.	DESCRIPTION OF WASTEWATER TREATMENT – Domestic wastewater is collected and treated via a conventional lagoon followed by chlorine disinfection.  No increase in flow is proposed within the application.  

IV.	RECEIVING WATERS – Unnamed ditch thence Black Bayou.  Black Bayou does appear on the updated 303(d) List of Impaired Waterbodies for Aquatic Life Support due to Nutrients, Organic Enrichment/Low DO, and Sediment/Siltation.  The facility is included in a completed TMDL for Black Bayou for Organic Enrichment/Low DO and Nutrients.  This waterbody is in the Yazoo River drainage basin. Black Bayou is classified as Fish and Wildlife.  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, 0.085 MGD or 0.132 cfs
		 Qr = Receiving stream 7Q10, 0 cfs.

IWC = {(0.132 cfs)/(0.132cfs + 0.00 cfs)}*100 = 100 %

V.	APPLICABLE GUIDELINES – 11 MS Admin Code pt. 6, Wasteload Allocation (WLA)

VI.	SUMMARY OF LIMITATIONS –

	Parameter						Value			Basis
	Flow						0.085 MGD			Design
	BOD5						16 mg/l (Monthly Avg.)		TMDL/WLA
	BOD5 (Percent Removal)				65% Minimum			Technology
	TSS						90 mg/l (Monthly Avg.)		Technology	
	NH3-N						2.0 mg/l (Monthly Avg.)		TMDL/WLA
	Dissolved Oxygen					> 6.0 mg/l (Monthly Avg.)		TMDL/WLA
E. Coli						126 Col./100 ml			MSWQC	
	pH						6.0 – 9.0 SU			MSWQC
	Chlorine, Total Residual					0.011/ 0.019 mg/l			MSWQC, IWC
	Total Nitrogen						Report			TMDL
	Total Phosphorus						Report			TMDL