PERMIT RATIONALE FOR REISSUANCE
RHHK LLC, D Iberville Car Wash
Harrison County
D'Iberville, Mississippi
Water NPDES No. MS0057738
August 18, 2026

I.	FACILITY INFORMATION

Facility Name:		RHHK LLC, D Iberville Car Wash
Facility Address:	10497 D Iberville Blvd 
	D'Iberville, MS  39540    
Gulfport, 
Permit No.:		MS0057738
SIC:			7542
Permit Writer:		Lee Barnes

II.	NATURE OF BUSINESS

RHHK LLC, D Iberville Car Wash operates an unmanned car wash facility in Harrison County. This operation currently discharges into an unnamed tributary of Back Bay of Biloxi.

III.	RECEIVING WATERS

RHHK LLC, D Iberville Car Wash discharges 10,000 gallons per day of treated carwash effluent through an existing outfall into an unnamed tributary of Back Bay of Biloxi which is located in the Coastal Streams drainage basin.

IV.	303(d) and TOTAL MAXIMUM DAILY LOADS (TMDLs) ISSUES

Back Bay of Biloxi is not listed on the Mississippi’s 2024 Section 303(d) List of Impaired Water Bodies. The permit complies with the following TMDL:

•	Fecal Coliform TMDL for the Back Bay of Biloxi and Biloxi Bay Coastal Streams Basin Harrison and Jackson Counties 

V.	DESCRIPTION OF WASTEWATER TREATMENT

Process wastewater is treated by an oil/water separator.

VI.	APPLICABLE GUIDELINES

	11 Mississippi Admin Code pt. 6, State of Mississippi Water Quality Criteria (MSWQS), 	
	Commercial Facility Guidelines (Technology)

VII.	PROPOSED FINAL LIMITATIONS 

Outfall 001
Parameter	Current Permit Limit (CPL)	Present Permit Limit (PPL)	Basis	
	Average	Maximum	Average	Maximum		
Flow	-----	0.01 MGD	-----	0.01 MGD	Design	
pH	6.0 SU (min)	9.0 SU	6.0 SU (min)	9.0 SU	MSWQS	
Oil and Grease	10 mg/L	15 mg/L	10 mg/L	15 mg/L	1/	
Total Suspended Solids 	30 mg/L	50 mg/L	30 mg/L	50 mg/L	1/	

MSWQS = Mississippi Water Quality Standards

1/Proposed permit limits for Oil and Grease and Total Suspended Solids are comparable to limits placed in permits held by existing similar commercial car wash facilities in the State of Mississippi.  

Effluent Limits have been developed such that the waste treatment system should protect water quality.  However, this permit is subject to modification if future evidence, monitoring results, or nuisance conditions indicate a higher degree of treatment is required to maintain water quality in the receiving stream.