PERMIT RATIONALE FOR REISSUANCE
Walnut POTW
Tippah County
Walnut, Mississippi
Water NPDES No. MS0025925
February 2023

I.	CLASSIFICATION –NPDES Municipal 

II.	DESCRIPTION OF WASTEWATER – Domestic

III.	DESCRIPTION OF WASTEWATER TREATMENT – Municipal wastewater is collected and treated by means of a lagoon which operates as a Hydrological Controlled Release.  No increase in flow is proposed within the application. 

IV.	RECEIVING WATERS – Muddy Creek.  The receiving water is located within the Northern Independent Stream Basin and is classified as Fish and Wildlife.  Muddy Creek does not appear on the current State of Mississippi 303(d) list impaired waterbodies. The facility appears on a completed Total Maximum Daily Load (TMDL) for Organic Enrichment Also, the facility appears on a pathogen TMDL for Fecal Coliform.

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 LIMITATIONS –
Parameter		Value					Basis
Flow			0.18 MGD 				Design
BOD			30 mg/l 				WLA				
Ammonia		15 mg/l 				WLA		
TSS			90 mg/l 				Technology
pH			6.0 to 9.0 S.U.				MSWQS
Phase I Chlorine	Report, mg/l				WLA
Phase II Chlorine 	0.40 mg/l				WLA
Phase I E. Coli		Report, Col./100ml			WLA
Phase II E. Coli 	126 Col./100 ml			WLA
Total Nitrogen		Report, lbs. / day			WLA
Total Phosphorus 	Report, lbs. / day			W:A

Effluent shall not be discharged to the receiving stream when the stream flow is less than ten (10) CFS.  (Note: 10 CFS = 6.46 MGD) 
WLA limits are based on regulations for HCR discharges.

VII.	CHANGES FROM PREVIOUS PERMIT – 

Chlorine, E. Coli, Total Nitrogen, and Total Phosphorus permit limitations have been added to the proposed draft permit

The permittee shall achieve compliance with the effluent limitations specified for discharge in accordance with the following schedule:
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 noted as Phase I; Phase II limitations shall not apply at this time.

Beginning upon completion and start-up of improvements needed to comply with Phase II limitations or three (3) years after the issuance of the permit, whichever comes first, the permittee shall achieve compliance with the effluent limitations specified for the parameters without a phase designation and for the parameters noted as Phase II; Phase I limitations shall no longer apply at this time. 

The permittee shall notify our office orally at least 24 hours prior to start-up and in writing no later than 48 hours after start-up.

The Permittee shall Submit engineering report: Due once within 6 months (180 days) after effective date. Said report shall outline the improvement activities needed to upgrade the wastewater treatment facility to comply with the site's Phase II limitations and shall include a proposed schedule for those improvement activities

The Permittee shall Submit progress report: Due annually - every 1 year after effective date. Said report shall update the Permittee's progress in addressing needed upgrades to the wastewater treatment facility in order to meet the site's Phase II limitations. Said report should also include an updated schedule for completing these activities.