PERMIT RATIONALE FOR MODIFICATION
Sand Creek Wastewater Authority, Sand Creek POTW
Lee County
Saltillo, Mississippi
Water NPDES No. MS0021733
August 2023

I.	FACILITY INFORMATION

Facility Name:  		Sand Creek POTW
Facility Address:  	179 Fellowship Road 
	Saltillo, MS  38866    
Permit No.: 		MS0021733
SIC:  			4952
Permit Writer:  		Dmitriy Asanov
EPD Branch:  		Municipal and Private Facilities

II.	DESCRIPTION OF WASTEWATER –Municipal/Domestic Wastewater

III.	PURPOSE FOR MODIFICATION—Permittee has requested a flow expansion to 3.2 MGD in order to accommodate continued growth in the region & to incorporate flows from the City of Baldwyn. An antidegradation report was submitted with the modification request.

IV.	DESCRIPTION OF WASTEWATER TREATMENT – Domestic wastewater is collected and treated biologically by means of an oxidation ditch followed by disinfection by chlorination.  No increase in flow is proposed within the application.

V.	RECEIVING WATERS – Sand Creek. The receiving stream is located within the Tombigbee River Basin and is classified as Fish and Wildlife.  At the point of discharge, Sand Creek (MS ISD 804811) appears on the current State of Mississippi 303(d) List of Impaired Waterbodies for Biological Impairment. The discharge appears on a Nutrients TMDL for Town Creek, which the facility complies with via numeric limitations. At the point of discharge, the 7Q10 for the receiving stream is 0.06 cfs.  The instream wastewater concentration at the point of discharge is determined to be 99% at 3.2 MGD.

VI.	APPLICABLE GUIDELINES – 11 MS Admin Code pt. 6, 2023 Wasteload Allocation (WLA), Modification Request, 2023 Antidegradation Report

VII.	SUMMARY OF LIMITATIONS – 

Parameter				Value			Basis
Flow	
	Phase I				1.5 MGD			Design
	Phase II				3.2 MGD			Design
BOD5					6 mg/l (Monthly Avg.)		WLA
TSS					30 mg/l (Monthly Avg.)		Admin Code
Ammonia Nitrogen 			2 mg/l (Monthly Avg.)		WLA
E. Coli					126 Col./100ml			Admin Code
Dissolved Oxygen			6.0 mg/l (Minimum)			Admin Code
Chlorine, Residual			0.011 mg/l (Monthly Avg.)		WLA
Total Phosphorus			56.12 lbs/day			TMDL
Total Nitrogen				130.43 lbs/day			TMDL
Copper, Total Recoverable		0.00682 mg/l			Chemical Specific Calcs
Zinc, Total Recoverable			0.065 mg/l			Chemical Specific Calcs
Mercury, Total Recoverable		Report mg/l			Chemical Specific Calcs
pH 					6.0 – 9.0 S.U.			MSWQS
Ceriodaphnia dubia 			97.48% min 			Admin Code
Pimephales promelas 			97.48% min 			Admin Code

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 parameters shall not apply at this time.  Beginning upon completion and start-up of improvements needed to comply with the Phase II parameters, the facility shall comply with the parameters noted as Phase II ; Phase I parameters shall not 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 of the needed improvements.