PERMIT RATIONALE FOR REISSUANCE
Rohm and Haas Chemicals LLC
Water NPDES No. MSS059668
July 13, 2022
Samar Patel, Water I Branch

I.	FACILITY INFORMATION

Facility Address:  5724 Elder Ferry Road, Moss Point, MS  39563
Facility County:   Jackson
SIC:  2869

II.	NATURE OF BUSINESS

This is the site of a closed and dismantled industrial plant (since 2001) with contaminated groundwater from hazardous disposal operations.  The only activities on site are those associated with remediation.  The treated groundwater is discharged to the Jackson County Utility Authority’s Escatawpa Wastewater Treatment Plant in accordance with the facility’s pretreatment permit (MSP092041).  Storm water runoff from the site does not come into contact with any waste or process areas, since all process equipment has been removed and any hazardous waste management units have been closed, capped, and vegetated to prevent erosion.  

III.	EFFLUENT AND RECEIVING STREAM FLOW DATA

Outfall 001: stormwater runoff from the 110-acre site to the Escatawpa River (Pascagoula River Basin)

IV.	303(d) ISSUES

The Escatawpa River is not listed on the 2020 303(d) List of Impaired Waterbodies.  EPA finalized a TMDL in July 2001, addressing low dissolved oxygen, pathogens, pH, chlorine, and toxicity due to total toxics and nonpriority organics.  MDEQ finalized a TMDL addressing mercury in June 2000.  Process wastewater that was previously discharged from Rohm and Haas (operating as Morton as the time) was included in this TMDL. Storm water from Morton (formerly) was not specifically addressed in the TMDL.  The non-contact storm water runoff from the site should not have an adverse impact on any of the pollutants addressed by the TMDL.

V.	TYPE OF WASTEWATER TREATMENT:

None 

VI.	EPA APPLICABLE CATEGORICAL GUIDELINES

N/A

VII.	DATA FROM APPLICATION FORM 2F

Parameter	Maximum Daily Value	
Oil & Grease	2.7 mg/L	
BOD5	4.8 mg/L	
COD	49 mg/L	
TSS	27 mg/L	
Total Nitrogen	1.4 mg/L	
Total Phosphorus	<0.10 mg/L	
pH	6.7 – 7.1 S.U.	

VIII. 	WATER QUALITY LIMITATIONS BASED ON WASTELOAD ALLOCATION 

	N/A

IX.	CATEGORICAL GUIDELINE LIMITATIONS CALCULATIONS

N/A 

X.	PROPOSED FINAL LIMITATIONS 

1.	Average Permit Limitations

Outfall	Parameter	Water Quality Limitation	Present Permit Limitation	Proposed Permit Limitation	Basis1	
MSS059668-001	Flow	̶	Report Annual Average	Report Annual Average	PPL	
	Oil & Grease	̶	Report Annual Average	Report Annual Average	PPL	
	COD	̶	Report Annual Average	Report Annual Average	PPL	
	pH	6.0—9.0 S.U.	6.0—9.0 S.U.	6.0—9.0 S.U.	WQS	
	TSS	̶	Report Annual Average	Report Annual Average	PPL	

2.	Maximum Permit Limitations

Outfall	Parameter	Water Quality Limitation	Present Permit Limitation	Proposed Permit Limitation	Basis1	
MSS059668-001	Flow	̶	Report Annual Maximum	Report Annual Maximum	PPL	
	Oil & Grease	̶	Report Annual Maximum	Report Annual Maximum	PPL	
	COD	̶	Report Annual Maximum	Report Annual Maximum	PPL	
	pH	6.0—9.0 S.U.	6.0—9.0 S.U.	6.0—9.0 S.U.	WQS	
	TSS	̶	Report Annual Maximum	Report Annual Maximum	PPL	
1 PPL = Previous permit limit; WQS = Water quality standard

All parameters listed above will be monitored semiannually and submitted on an annual DMR.  Oil and grease, COD, pH, and TSS are monitored via grab sampling.  Flow is calculated using an onsite weather gauge and average runoff coefficient.

Flow, pH, oil and grease, COD, and TSS limitations will remain the same from the previous permit. Acute WET testing requirements have been removed.  

The discharge is entirely comprised of storm water and to ensure that the storm water from Outfall
 001 remains to be an unobjectionable discharge to a river with Fish Wildlife classification, storm
 water pollution prevention requirements will be carried forward and incorporated into the permit.