PERMIT RATIONALE FOR REISSUANCE
Hancock County Water and Sewer District, Port Bienville Industrial Park
Hancock County
Bay St. Louis, Mississippi
Water NPDES No. MS0059501
June 2026

I.	CLASSIFICATION – NPDES Minor Industrial

II.	DESCRIPTION OF WASTEWATER – Domestic/Industrial Wastewater

III.	DESCRIPTION OF WASTEWATER TREATMENT – Port Bienville Industrial Park collects and treats industrial wastewater from Alpek Polyester Mississippi Inc. (MSP091316) biologically by means of an activated sludge process, and discharges from Outfall 002.   Outfall 001 is no longer in use and was decommissioned around July 2023 as described in submitted application. This rationale and permit refer the active outfall as Outfall 001.

I.	RECEIVING WATERS – The Pearl River.  The receiving waters are classified as fish and wildlife on the 2024 State of Mississippi 303(d) list of impaired waterbodies.  The receiving waters are tidally influenced.  State Regulations allow for receiving waters that are oceans, bays, estuaries or lakes, and a mixing zone evaluation has not been performed to determine the dilution factor to calculate the instream wastewater concentration (IWC), that a dilution ratio shall be assumed to be one part effluent to six parts receiving waterbody.  The specific waterbody ID is MSLPRLRE. This facility appears on a Nutrient TMDL for Organic Enrichment/Low DO (June 2009). The TMDL did not require a reduction in nutrient loading for this point source. The facility also appears on a TMDL for Fecal Coliform (December 2009) and the March 2009 TMDL for Total Toxics for the Mulatto Bayou.

IV.	APPLICABLE GUIDELINES – 11 MS Admin Code Pt 6, Commercial/Municipal Facility Guidelines (Technology), MS Water Quality Standards, Wasteload Allocation (WLA), TMDL

V.	CHANGES FROM PREVIOUS PERMIT – Antimony and Iron monitoring have been added to the proposed draft permit. Permit will be modified after receipt of necessary samples. Outfall 001 has been decommissioned, and the previously permitted Outfall 002 is now Outfall 001.

VI.	SUMMARY OF LIMITATIONS –
	
Outfall 001 (Changed from Outfall 002)
Parameter				Value			Basis
Flow					0.183 MGD		Design
BOD5					24 mg/l / 36 mg/l	WLA
TSS					30 mg/l / 45 mg/l	Technology
Ammonia Nitrogen 			Report			WLA
pH					6.0 – 9.0 SU		MS WQS
Enterococci				35 (col/100ml)		MS WQS
Sludge Settleability			Report			Technology
DO					Report			Technology
Total Nitrogen				Report			WLA
Total Phosphorous			Report			WLA
Antimony				Report			Calculations
Iron					Report			Calculations

CHEMICAL SPECIFIC ANALYSIS

Chemical specific analysis for Metals and Results

Industrial dischargers shall determine the toxic characteristics of their wastewater by analyzing for toxic pollutants listed in Table III of Appendix D of 40 CFR 122.  Metal analysis shall be for total recoverable metals.  Industrial dischargers shall submit one influent and effluent samples collected.  Chemical specific limits shall be placed in a permittee’s permit if any of the parameters evaluated in the toxic screening procedure indicate the reasonable potential for violation of the appropriate criteria (acute, chronic, and human health).

For Port Bienville Industrial Park, the chemical specific data results submitted with the reapplication indicated the reasonable potential for violation of Antimony in Table III of Appendix D of 40 CFR 122.  See chemical specific analyses that follow.

The following Toxic Metals, Cyanide, and Total Phenols compounds were detected and evaluated for a potential to violate Human Health Criteria: 

Antimony
Avg. Daily Concentration = 260 μg/L 

According to EPA’s National Recommended Water Quality Criteria, the Human Health Criteria (consumption of organism only) for the following compound(s) are shown below: 

Antimony
Recommended Water Quality Criteria = 640 μg/L
 
Multiplying the average daily concentration above by 10 (due to a data set of less than 12 samples) determines the reasonable potential of the compound’s concentration to violate the Human Health Criteria. 
[260 μg/L * 10] = 2600 μg/L 
2600 μg/L > 640 μg/L 

The above results demonstrate that the average concentration(s) for Antimony do present a potential to violate Human Health Criteria. The following condition has been added to the permit:

“The Permittee shall submit results of 11 effluent samples of the Antimony pollutant listed in Section 1 of Table B of the Form 2C application. Sampling of the wastewater treatment facility's effluent shall be performed once per month for a total of 11 samples. Sampling shall begin 10 days after the issuance date of permit and continuing for 11 consecutive months. Sample results shall be submitted by the 28th day of the month following completion of sampling.”

Zinc
Avg. Daily Concentration = 48.8 μg/L 

According to EPA’s National Recommended Water Quality Criteria, the Human Health Criteria (consumption of organism only) for the following compound(s) are shown below: 

Zinc
Recommended Water Quality Criteria = 26,000 μg/L
 
Multiplying the average daily concentration above by 10 (due to a data set of less than 12 samples) determines the reasonable potential of the compound’s concentration to violate the Human Health Criteria. 
[48.8 μg/L * 10] = 488 μg/L 
488 μg/L < 26,000 μg/L 

The above results demonstrate that the average concentration(s) for Zinc do not present a potential to violate Human Health Criteria. 

“The Permittee shall submit results of 1 effluent sample of the Arsenic, Beryllium, Cadmium, Chromium, Copper, Lead, Mercury, Nickel, Selenium, Silver, Thallium, Cyanide, and Phenols pollutants listed in Section 1 of Table B of the Form 2C application. Sampling of the wastewater treatment facility's effluent shall be performed once for a total of 1 sample. Sample results shall be submitted by the 28th day of the month following completion of sampling.”

Chemical specific analysis for Volatile Organic Compounds and Results

“The Permittee shall submit results of 1 effluent sample of  all pollutants listed in Section 2 of Table B of the Form 2C application. Sampling of the wastewater treatment facility's effluent shall be performed once for a total of 1 sample. Sample results shall be submitted by the 28th day of the month following completion of sampling.						

Chemical specific analysis for Certain Conventional and Non-Conventional Pollutants

The following Conventional and Non-Conventional compounds were detected and evaluated for a potential to violate Human Health Criteria: 

Manganese
Avg. Daily Concentration = 2.62 μg/L 

According to EPA’s National Recommended Water Quality Criteria, the Human Health Criteria (consumption of organism only) for the following compound(s) are shown below: 

Manganese
Recommended Water Quality Criteria = 100 μg/L
 
Multiplying the average daily concentration above by 10 (due to a data set of less than 12 samples) determines the reasonable potential of the compound’s concentration to violate the Human Health Criteria. 
[2.62 μg/L * 10] = 26.2 μg/L 
26.2 μg/L < 100 μg/L 

The above results demonstrate that the average concentration(s) for Manganese do not present a potential to violate Human Health Criteria. 

Iron
Avg. Daily Concentration = 256 μg/L

According to EPA’s National Recommended Water Quality Criteria, the Human Health Criteria (consumption of organism only) for the following compound(s) are shown below: 

Iron
Recommended Water Quality Criteria = 1000 μg/L
 
Multiplying the average daily concentration above by 10 (due to a data set of less than 12 samples) determines the reasonable potential of the compound’s concentration to violate the Human Health Criteria. 
[256 μg/L * 10] = 2560 μg/L 
2560 μg/L > 1000 μg/L 

The above results demonstrate that the average concentration(s) for Iron do present a potential to violate Human Health Criteria. The following condition has been added to the permit:

“The Permittee shall submit results of 11 effluent samples of the Iron pollutant listed in Section 1 of Table B of the Form 2C application. Sampling of the wastewater treatment facility's effluent shall be performed once per month for a total of 11 samples. Sampling shall begin 10 days after the issuance date of permit and continuing for 11 consecutive months. Sample results shall be submitted by the 28th day of the month following completion of sampling.”

Attachment 1. Waste Load Allocation for Outfall 002 (Permit denoted Outfall 001)