PERMIT RATIONALE FOR REISSUANCE
Harrison County School District, Harrison Central High School
Harrison County
Gulfport, Mississippi
Water NPDES No. MS0030911
July 2019

I.	CLASSIFICATION – NPDES Commercial

II.	DESCRIPTION OF WASTEWATER – Domestic

III.	DESCRIPTION OF WASTEWATER TREATMENT – Domestic wastewater is collected and treated via a conventional lagoon followed by chlorine disinfection prior to discharge. Only one discharge to surface waters is described within the application with no increase in treated effluent flow proposed. 

IV.	RECEIVING WATERS – Unnamed ditch thence Little Biloxi River thence Biloxi River. The receiving waters are located in the Coastal Streams drainage basin and are classified as Fish and Wildlife. At the point of discharge, the receiving stream does not appear on the current State of Mississippi 303(d) List of Impaired Waterbodies. The discharge does appear on a completed Total Maximum Daily Load (TMDL) for Fecal Coliform in the Biloxi River (December 1999). The facility utilizes chlorine disinfection, which complies with the conditions of the TMDL.

V.	APPLICABLE GUIDELINES – 11 Mississippi Admin Code pt. 6, Commercial Facility Guidelines (Technology)

VI.	SUMMARY OF DISCHARGE LIMITATIONS – 

	Parameter		Value			Basis
	Flow			0.03 MGD		Design
	BOD			30 mg/l 			Technology
	TSS 			90 mg/l 			Technology
	E. coli			126 Col./100mL 		Admin Code
	pH			6.0 to 9.0 S.U.		Admin Code
	Chlorine			0.1 to 1.0 mg/l		Admin Code

VII.	CHANGES FROM PREVIOUS PERMIT – 

E. coli has replaced fecal coliform as the bacterial indicator for all freshwaters in Mississippi designated as Recreation, Fish and Wildlife Support, and/or Public Water supply.