PERMIT RATIONALE FOR REISSUANCE
Tylertown POTW
Walthall County
Tylertown, Mississippi
Water NPDES No. MS0020681
April 2017

I.	CLASSIFICATION – NPDES Minor Municipal
II.	DESCRIPTION OF WASTEWATER – Domestic/Municipal  
III.	DESCRIPTION OF WASTEWATER TREATMENT – Wastewater is biologically treated by means of a one-cell conventional lagoon followed by chlorine disinfection prior to discharge.  The current design capacity of the facility is 0.42 MGD.  The site is proposing modification of the treatment works to an aerated lagoon with a design capacity of 0.8 MGD. This modification was addressed in a previous permit action. 
IV.	RECEIVING WATERS – Magee’s Creek. Magee’s Creek is located within the Pearl River Basin and is classified as Recreational. Magee’s Creek is designated as a Mississippi Scenic Stream under the Mississippi Scenic Streams Stewardship Program. The discharge appears on a completed Total Maximum Daily Load (TMDL) for pathogens for Magee’s Creek.  The facility utilizes chlorine disinfection, which complies with the conditions of the TMDL.  This facility is included in a TMDL for the Bogue Chitto River for mercury.  The TMDL requires the implementation of a mercury minimization plan, which was addressed in a previous permitting action.   

V.	APPLICABLE GUIDELINES – 11 Mississippi Admin Code pt. 6, Wasteload Allocation (WLA), Municipal Facility Guidelines (Technology)

VI.	SUMMARY OF LIMITATIONS – 
Parameter				Flow		Basis
Flow						
-	Phase I				0.42 MGD		Design
-	Phase II			0.8 MGD		Design (modification)
NH3-N				15 mg/L		WLA
BOD5					30 mg/L		WLA
Dissolved Oxygen			≥6.0 mg/L		WLA
E. coli					126 colonies/100 mL		Admin Code
Chlorine (total residual)		
-	Phase I				0.65 mg/L		WLA
-	Phase II			0.36 mg/L		WLA
TSS					90 mg/L		Technology
Total Nitrogen				Report lbs/day		WLA
Total Phosphorus			Report lbs/day		WLA
pH					6.0 – 9.0 SU		Admin Code

	

VII.	PROPOSED SCHEDULE OF COMPLIANCE – the following language has been included in the schedule of compliance of 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 noted as Phase I; Phase II limitations shall not apply at this time.
Beginning upon completion and start-up of improvements to increase the wastewater treatment facility's design flow rate to 0.8 MGD, the permittee shall achieve compliance with the effluent limitations specified 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 48 hours prior to start-up of the expanded facility and in writing no later than 5 days after start-up.
VIII.	Changes From Previous Permit
1.	Fecal coliform standards have been replaced by E. coli standards.