PRETREATMENT RATIONALE FOR ISSUANCE

Attala Steel Industries LLC.
Attala County
Kosciusko, MS
Water II Branch 

Pretreatment Permit No. MSP092480
SIC Code: 3449 and 3479
July 1, 2025
Permit Engineer: Rajeev Gupta

I.	FACILITY INFORMATION

A.	Nature of Business: The facility is a manufacturer of guardrails used along roadways, highways, etc..  
B.	Process Wastewater Description: Outfall 001 will discharge a maximum 0.020 MGD of wastewater consisting of contact cooling water and washwater.   
C.	Proposed Flowrate: Outfall 001: 0.02 MGD (Daily Maximum)
D.	Applicable Federal Guidelines: 40 CFR Part 420 – Iron and Steel Manufacturing Point Source Category; Subpart G – Hot Forming Subcategory; Section Mills – Carbon; 420.76 (PSNS).  This regulation requires compliance with the general pretreatment prohibitions found in 40 CFR Part 403.

II.	RECEIVING POTW INFORMATION

A.	POTW Name, AI No., and Permit No.: Kosciusko POTW, South, AI 13213, MS0027774
B.	POTW Treatment Type: Hydrograph Controlled Release Lagoon Treatment System
C.	POTW Design Flowrate: 2.048 MGD  
D.	POTW Receiving Stream: Yockanookany River
E.	POTW Receiving Stream 7Q10 (Q7/10): 14.835 MGD  

III.	PERTINENT FLOWRATE AND LOADING DATA

A.	POTW 12-month Average Flowrate (QPOTW):1.613 MGD (May 2024-April 2025)
B.	Industrial Facilities Maximum 30-day Average Flow (QIND) for Contributing Pollutants:
(obtained from May 2024 – April 2025 DMRs):

Facility (Permit No., AI No.)	Ni	Pb	Cu	Zn	Cr	Fe	Al	
East Side Jersey Dairy Inc.
(MSP090691, 40)	-----	-----	-----	-----	-----	-----	-----	
Total, QIND (MGD)	-----	-----	-----	-----	-----	-----	-----	

C.	Industrial Facilities Permitted/Requested Flow in MGD (QW):

Facility (Permit No., AI No.)	Ni	Pb	Cu	Zn	Cr	Fe	Al	
East Side Jersey Dairy Inc.
(MSP090691, 40)	-----	-----	-----	-----	-----	-----	-----	
Attala Steel Industries LLC.
(MSP092480, 22909)	0.02	0.02	0.02	0.02	0.02	0.02	0.02	
Total, QT (MGD)	0.02	0.02	0.02	0.02	0.02	0.02	0.02	
.

IV.	
BACKGROUND/DOMESTIC LOADING CALCULATIONS

Background Loading (BGL), lb/d = 8.34 x BGC(mg/L)(1) x (QPOTW - QINDUSTRIAL(2))(MGD)

BGC = Background concentration of domestic sewage.  Actual Background concentration data was not able to calculated.  Concentrations for all pollutants with the exception of Aluminum and Iron were obtained from EPA Guidance Manual on the Development and Implementation of Local Discharge Limitations Under the Pretreatment Program: Appendix V – Domestic Pollutant Loadings.

QIND = (QW1 + QW2 + …) = Summation of maximum 30-day average flows from existing industrial dischargers (IUs) contributing a Pollutant of Concern (POC) to the POTW.

BGL (Cr) = 8.34*0.034*(1.613-0) =	0.457 lb/day
BGL (Cu) = 8.34*0.14*(1.613) =	1.88 lb/day
BGL (Lead) = 8.34*0.058*(1.613) =	0.78 lb/day
BGL (Nickel) = 8.34*0.047*(1.613) =0.632 lb/day
BGL (Zn) = 8.34*0.231*(1.613) =	3.107 lb/day
BGL (Fe) = 8.34*0.989*(1.613) =	13.3 lb/day
BGL (Al) = 8.34*0.100*(1.613) =	1.345 lb/day

Iron background concentration level based on data found in EPA’s Guidance Manual on the Development and Implementation of Local Discharge Limitations Under the Pretreatment Program.  Aluminum background concentration level based on data found in Agency for Toxic Substances and Disease Registry (ATSDR) Toxicological Profiles, Toxicological Profile for Aluminum, September 2008, Table 6-3.  The background Aluminum concentration used is based on a review of the data for the State of Louisiana Aluminum levels reported in this table and further discussion found on page 195 of this document.  
V.	ALLOWABLE HEADWORKS LOADING CALCUATIONS  

Instream Wastewater Concentration (IWC), % = [QPOTW / (QPOTW + Q7/10)] x 100

IWC % = 12.2 %  (A dilution ratio of 7.2 to 1 must be maintained at all times as per Kosciusko POTW South’s NPDES Permit.) 

Acute and Chronic screenings are performed because the IWC > 1%.  

A.	AHL, Water Quality Criteria Based (AHLWQC)

AHLWQC, lb/day = 8.34 x CCRITERIA (mg/L) x (Q7/10 + QPOTW, MGD) / (1 – RPOTW)

CCRITERIA = Water Quality Criteria; obtained from State of Mississippi Water Quality Criteria for Intrastate, Interstate, and Coastal Waters: Freshwater Acute and Chronic Values.  

RPOTW = Removal efficiency, in decimal form.  Values obtained from Appendix B.  With the exception of Cyanide, Total Recoverable Aluminum, and Total Recoverable Iron, removal efficiencies for all pollutants are based on actual influent and effluent data provided by POTW.  The removal efficiency for Cyanide is based on an MDEQ-observed study for activated sludge systems.  For Iron and Aluminum, no data is available and complete pass through is assumed

Chronic Analysis, AHLCWQC:
AHLCWQC (Cr) = 8.34*0.042*(1.613+14.835)/(1-0.83) = 33.89
AHLCWQC (Cu) = 8.34*0.005*(1.613+14.835)/(1-0.5399) = 1.491 lb/day
AHLCWQC (Lead) = 8.34*0.00118*(1.613+14.835)/(1-0.56) = 0.368 lb/day
AHLCWQC (Nickel) = 8.34*0.029*(1.613+14.835)/(1-0.32) = 5.85 lb/day
AHLCWQC (Zn) = 8.34*0.065*(1.613+14.835)/(1-0.954) = 193.8 lb/day
AHLCWQC (Al) = 8.34*0.140*(1.613+14.835)/(1-0) = 19.2 lb/day
AHLCWQC (Fe) = 8.34*1.0*(1.613+14.835)/(1-0) = 137.2 lb/day

Acute Analysis, AHLAWQC:
AHLAWQC (Cr) = 8.34*0.323*(1.613+14.835)/(1-0.83) = 260.6 lb/day
AHLAWQC (Cu) = 8.34*0.007*(1.613+14.835)/(1-0.5399) = 2.09   lb/day
AHLAWQC (Lead) = 8.34*0.030*(1.613+14.835)/(1-0.56) =9.35 lb/day 
AHLAWQC (Nickel) = 8.34*0.260*(1.613+14.835)/(1-0.32) =52.45 lb/day 
AHLAWQC (Zn) = 8.34*0.065*(1.613+14.835)/(1-0.954) = 193.8 lb/day
AHLAWQC (Al) = 8.34*0.250*(1.613+14.835)/(1-0) = 34.29 lb/day
AHLAWQC (Fe) = 8.34*N/A*(1.613+14.835)/(1-0) = No Acute Criteria

B.	AHL, POTW Inhibition Based (AHLINH)

AHLINH, lb/day = 8.34 x QPOTW (MGD) x CINH (mg/L)

CINH = Activated Sludge Inhibition Levels, from EPA Guidance Manual on the Development and Implementation of Local Discharge Limitations Under the Pretreatment Program: Appendix G - Activated Sludge Inhibition Levels.  For all parameters, 1.0 mg/L is used since this value is near the minimum side of the minimum reported range of inhibition threshold levels.  Inhibition threshold levels could not be found for Iron and Aluminum.

	AHLINH (Cr) = 8.34*1.613*1.0 = 		13.5 lb/day
	AHLINH (Cu) = 8.34*1.613*1.0 = 		13.5 lb/day
	AHLINH (Lead) = 8.34*1.613*1.0 = 		13.5 lb/day
	AHLINH (Nickel) = 8.34*1.613*1.0 = 		13.5 lb/day
	AHLINH (Zn) = 8.34*1.613*1.0 = 		13.5 lb/day

C.	AHL, POTW NPDES Permit Limit Based (AHLNPDES)

If the POTW has a limit for a specific parameter, industrial loading is limited to the amount the POTW can accept and still meet the limit.  Kosciusko POTW South’s NPDES Permit does not contain limits for any Toxic.

VI.	MAXIMUM ALLOWABLE HEADWORKS LOADINGS AND LIMITING CASE

Parameter	AHLINH (lb/day)	AHLCWQC (lb/day)	AHLAWQC (lb/day)	AHLCNPDES (lb/day)	AHLANPDES (lb/day)	MAHLC
(lb/day)	MAHLA
(lb/day)	BGL (lb/day)	LC
(lb/day)	Allocation Available
(BGL < LC)	
Chromium	13.5	33.89	260.6	None	None	13.5	13.5	0.457	13.5	Allocation	
Copper	13.5	1.491	2.09	None	None	1.491	2.09	1.88	1.491	No Allocation	
Lead	13.5	0.368	9.35	None	None	0.368	9.35	0.78	0.368	No Allocation	
Nickel	13.5	5.85	52.45	None	None	5.85	13.5	0.632	5.85	Allocation	
Zinc	13.5	193.8	193.8	None	None	13.5	13.5	3.107	13.5	Allocation	
Aluminum	---	19.2	34.29	None	None	19.2	34.29	13.3	19.2	Allocation	
Iron	---	137.2	---	None	None	137.2	---	1.345	137.2	Allocation	

VII.	DEVELOPMENT OF ALLOWABLE CONCENTRATIONS

The remaining industrial wasteload allocation will be used in calculating allowable acute and 
chronic concentrations using the “Industrial User (IU) Contributory Flow” method as 
described in EPA’s Local Limits Development Guidance (EPA 833-R-04-002A, July 2004).  
	
PAI, lb/day = (MAHL, lb/day – BGL, lb/day) x (QW, MGD / QT, MGD)

CALLOW, mg/L = (PAI, lb/day) / (8.34 x QW, MGD)

PAI =	Permit allocation for indirect discharger
CALLOW =	Allowable concentration for indirect discharger
QW	=	Applicant’s permitted/requested process discharge 
QT	=	Total industrial contributory flow for pertinent pollutants
MAHL	=	MAHLC to be used for chronic and MAHLA to be used for acute
BGL	=	Background/domestic loading  

	OUTFALL 001

	CHRONIC (Average):

	PAI (Cr) = (13.5-0.457)*(0.020/0.020) =			13.043 lb/day
	CALLOW (Al) = 13.043/(8.34*0.020) =			78.2 mg/L

	PAI (Ni) = (5.85-0.632)*(0.020/0.020) =			5.215 lb/day
	CALLOW (Al) = 5.215/(8.34*0.020) =			31.26 mg/L

	PAI (Zn) = (13.5-3.107)*(0.020/0.020) =			10.393 lb/day
	CALLOW (Al) = 10.393/(8.34*0.020) =			62.3 mg/L

	PAI (Al) = (19.2-13.3)*(0.020 /0.020) =			5.9 lb/day
	CALLOW (Al) = 5.9/(8.34*0.02) =				35.37 mg/L

	PAI (Fe) = (137.2-1.345)*(0.020 /0.020) =		135.855 lb/day
	CALLOW (Fe) = 135.855/(8.34*0.02) =			814 mg/L

	ACUTE (Maximum):

	PAI (Cr) = (13.5-0.457)*(0.020/0.020) =			13.043 lb/day
	CALLOW (Al) = 13.043/(8.34*0.020) =			78.2 mg/L

	PAI (Ni) = (13.5-0.632)*(0.020/0.020) =			12.86 lb/day
	CALLOW (Ni) = 12.86/(8.34*0.020) =			77.15 mg/L

	PAI (Zn) = (13.5-3.107)*(0.020/0.020) =			10.393 lb/day
	CALLOW (Al) = 10.393/(8.34*0.020) =			62.3 mg/L

	PAI (Al) = (34.29-13.3)*(0.020/0.020) =	20.99 lb/day
	CALLOW (Al) = 20.99/(8.34*0.020) =	125.8 mg/L

	

	
VIII.	PROPOSED PERMIT LIMITATIONS

Parameter	Allowable Concentration (ALL)	Categorical Limits (CAT)	Current Permit
Limits (CPL)	Proposed Permit 
Limits (PPL)	Basis	
	Avg. (mg/L)	Max. (mg/L)	Avg. (mg/L)	Max. (mg/L)	Avg. (mg/L)	Max. (mg/L)	Avg. (mg/L)	Max. (mg/L)		
COD	-----	-----	-----	-----	-----	-----	400	600	City	
Oil and Grease	-----	-----	-----	-----	-----	-----	15	30	City	
BOD5	-----	-----	-----	-----	-----	-----	200	300	City	
TSS							200	300	City	
Temperature	-----	-----	-----	-----	-----	-----	-----	100 deg F	City	
Chromium, TR	78.2	78.2	-----	-----	-----	-----	0.1	0.5	City	
Copper, TR	----	---	-----	-----	-----	-----	0.3	0.6	City	
Zinc, TR	62.3	62.3	-----	-----	-----	-----	0.5	1.0	City	
Flow	----	-----	-----	-----	-----	-----	Report	0.02 MGD	City	
Lead, TR	----	-----	-----	-----	-----	-----	0.05	0.1	City	
Nickel, TR	31.26	77.15	-----	-----	-----	-----	0.3	0.6	City	
pH	----	-----	-----	-----	-----	-----	6.0 SU (min)	9.0 SU	City	
Iron, TR	814	-----	-----	-----	-----	-----	3.0	5.0	City	
Aluminum, TR	35.37	125.8	-----	-----	-----	-----	0.75	1	City	
TJ = Technical Judgement
TR = Total Recoverable 
PPL is the smallest of ALL, CAT, and CPL, average and maximum, respectively 

All limits are based on correspondence from the City of Kosciusko that was received in an e-mail on June 26, 2025.  As can be seen above, it appears that no allocation exists for discharge of Total Recoverable Copper and Total Recoverable Lead into the City of Kosciusko sanitary sewer system.  However, guidance data was used in calculating background concentrations for these toxics as actual background concentrations and loadings were not able to be calculated. The requested limits for these pollutants are not expected to affect the POTW or its discharge limits as the POTW’s discharge is non-continuous and the POTW operates as a hydrographic controlled released conventional lagoon. pH, TSS, BOD, COD, and Oil and Grease shall be monitored once per discharge event with a grab sample of the effluent.  Temperature shall be monitored once per discharge event instantaneously.  Flow shall be measured continuously with a Totalizer.  All toxics shall be monitored semi-annually with a grab sample of the effluent. 
		 
APPENDIX A

KOSCIUSKO POTW SOUTH REMOVAL EFFICIENCIES

[mg/L]	03/29/22	04/12/22	04/19/22	05/03/22	06/07/22	 06/21/22	07/08/22	Removal Efficiency1	
Cr Inf.	0.004	0.004	0.004	0.004	0.004	0.004	0.004	83 %*	
Cr Eff.	0.004	0.004	0.004	0.004	0.004	0.004	0.004		
Cu Inf.	0.003	0.003	0.0172	0.00610	0.0179	0.0203	0.0101	53.99 %	
Cu Eff.	0.003	0.003	0.003	0.003	0.0105	0.0102	0.003		
Pb Inf.	0.01	0.01	0.01	0.01	0.005	0.005	0.005	56 %*	
Pb Eff.	0.01	0.01	0.01	0.01	0.005	0.005	0.005		
Ni Inf.	0.01	0.01	0.01	0.01	0.01	0.01	0.01	32 %*	
Ni Eff.	0.01	0.01	0.01	0.01	0.01	0.01	0.01		
Zn Inf.	0.0413	0.0266	0.244	0.0879	0.0680	0.0865	0.208	95.4%	
Zn Eff.	0.005	0.005	0.005	0.005	0.005	0.005	0.005		

1 Removal Efficiency = [(<inf.> - <eff.>)/<inf.>]*100, where <inf.> is the average influent value and <eff.> is the average effluent value.  
Grey-shaded values were excluded in calculating removal efficiencies because the influent < effluent for the same sample date.  
Blue values were used in “non-detect” results obtained from the POTW bench sheets in which the MQL (Method Quantitation Limit) was then divided by 2 to obtain the blue value.  *MDEQ-observed study removal efficiency for conventional lagoons was used due to inadequate data from the POTW.  

ADEQUACY OF TREATMENT

	Date:  June 13, 2025                  
Permit Writer:  Rajeev Gupta
Proposed Site:  Attala Steel Industries LLC
Pretreatment Permit No. MSP092480
Attala County  

Proposed Hydraulic Loading:  0.050 MGD 	Proposed Flowrate: 0.020 mgd	
Proposed Organic Loading: 30 mg/L (Maximum value provided on application)

0.020 MGD*8.34*30 mg/L = 5 lb/day 

Kosciusko POTW South, NPDES Permit No. MS0027774, AI No. 13213   
Permitted Flow:	2.048 MGD(Annual Average Limit)
12 Months Flow:	1.613 MGD (May 2024- April 2025)
12 Months BOD5: 	300 mg/L representative influent value 
Design BOD5:	2.048 MGD*8.34*300 mg/L = 5124 lb/day  
Average BOD5:  1.613 MGD*8.34*300 mg/L = 4035.7 lb/day

Evaluation of Flow
2.048 MGD permitted – 1.613 MGD actual = 0.435 MGD 
0.435 MGD available vs. 0.020 MGD proposed flowrate

Evaluation of BOD5
5124 lb/day Design– 4035.7 lb/day Average = 1088 lb/day
1088 lb/day available vs. 5 lb/day proposed