PERMIT RATIONALE FOR REISSUANCE
Denbury Onshore LLC, Brookhaven Central Processing Facility
Lincoln County
Brookhaven, Mississippi
Water NPDES No. MS0059722
August 15, 2016
I.	FACILITY INFORMATION

Facility Name:  Denbury Onshore LLC, Brookhaven Central Processing Facility
Facility Address:  1030 California Road 
 Brookhaven, MS  39601    
Plano, 
Permit No.:  MS0059722
SIC:  1311
Permit Writer:  Thomas Kelly
EPD Branch:  Energy and Transportation Branch

II.	NATURE OF BUSINESS

Denbury Onshore LLC, Brookhaven Central Processing Facility is a tertiary oil recovery processing facility.  The application is for the discharge of cooling tower blowdown, wastewater from a bulk storage secondary containment area and storm water runoff from the main yard.  

III.	EFFLUENT AND RECEIVING STREAM FLOW DATA

Outfall 001 (External Outfall):	This discharge consists of cooling tower blowdown, storm water from the secondary containment area, and facility storm water runoff.  This outfall has a maximum 30-day discharge flow is 0.46 MGD and discharges to an unnamed ditch (7Q10=0) of West Bogue Chitto River located in the Pearl River Basin. 

IV.	303(d) ISSUES

None.

V.	TYPE OF WASTEWATER TREATMENT:

Outfall 001 – Disinfection.

VI.	EPA APPLICABLE CATEGORICAL GUIDELINES

None.

VII.	STATE APPLICABLE GUIDELINES

The Mississippi environmental regulations have been renumbered and reformatted
pursuant to the amended Administrative Procedures Act passed by the state legislature.
While the numbering and citation of the regulations have changed, the content of the
regulations have not.

1. Mississippi Commission on Environmental Quality National Pollutant Discharge
Elimination System (NPDES) Permits, Underground Injection Control (UIC) Permits,
State Permits, Water Quality Based Effluent Limitations, and Water Quality
Certification [11 Miss. Admin Code Pt. 6, Ch.1].

2. Mississippi Commission on Environmental Quality Regulations for Intrastate,
Interstate, and Coastal Waters [11 Miss. Admin Code Pt. 6. Ch. 2].

VII.	DATA FROM APPLICATION FORM (2C):

Parameter	Maximum Daily Value	
Biochemical Oxygen Demand	 3.0  mg/L	
Chemical Oxygen Demand	25  mg/L	
Total Organic Carbon	5.7  mg/L	
Total Suspended Solids	4.0  mg/L	
Ammonia (as N)	0.21 mg/L	
Temperature (winter) 	29.44 ºC 	
Temperature (summer)	30 ºC	
Bromide	9.03 mg/L	
Oil and Grease	3.30 mg/L	
pH	8.94 s.u.	
Flow	3.33 MGD	

VIII. 	WATER QUALITY LIMITATIONS BASED ON WASTELOAD ALLOCATION 

	None.

IX.	CATEGORICAL GUIDELINE LIMITATIONS CALCULATIONS

None.

X.	TOXICITY SCREENING

Not Applicable

XI.	PROPOSED FINAL LIMITATIONS 

1.	Average Permit Limitations

Outfall	Parameter	Categorical Limitation	Water Quality Limitation	Present Permit Limitation	Proposed Permit Limitation	Basis	
MS0059722-001	Flow	--	--	Report	Report	Technical Judgement	
Outfall	Parameter	Categorical Limitation	Water Quality Limitation	Present Permit Limitation	Proposed Permit Limitation	Basis	
MS0059722-001	Oil & Grease	--	--	10 mg/L	10 mg/L	Technical Judgment	
MS0059722-001	pH (min.)	--	6.0 s.u.	6.0 s.u.	6.0 s.u.	WLA, 11 Miss. Admin
Code Pt. 6, Ch.1	

2.	Maximum Permit Limitations

Outfall	Parameter	Categorical Limitation	Water Quality Limitation	Present Permit Limitation	Proposed Permit Limitation	Basis	
MS0059722-001	Flow 	--	--	Report 	Report 	Technical Judgment	
MS0059722-001	Oil & Grease	--	--	15 mg/L	15 mg/L	Technical Judgment	
MS0059722-001	pH (max.)	--	9.0 s.u.	9.0 s.u.	9.0 s.u.	WLA, 11 Miss. Admin
Code Pt. 6, Ch.1	
MS0059722-001	Temperature (˚F)	--	90 (Deg. F)	90 (Deg. F)	90 (Deg. F)	WLA, 11 Miss. Admin
Code Pt. 6, Ch.1	

MONITORING TYPE AND FREQUENCY

·     ”Flow” shall be monitored twice per month utilizing instantaneous sampling and reported on a monthly basis. 

•	“pH” shall be monitored twice per month utilizing grab sampling and reported on a monthly basis.   

•	“Oil & grease” shall be monitored twice per month utilizing grab sampling and reported on a monthly basis. Oil & grease shall be monitored only when the discharge contains storm water runoff from the secondary containment structure. If oil and grease is not monitored, the permittee shall indicate conditional monitoring (not required this period) by including the No Data Indicator Code (NODI) = 9 on the monthly discharge monitoring report. 

•	“Temperature (Deg. F)” shall be monitored twice per month utilizing grab sampling and reported on a monthly basis.

XII.	BASIS FOR PROPOSED PERMIT LIMITATIONS: 

Flow

The average and maximum flow limits of “Report” are based on technical judgment.

Oil & Grease  

The average and maximum effluent limit of 10 mg/l and 15 mg/l are technology based limits, which reflect the ability of simple oil/water separation equipment to easily remove oil & grease from the discharge.  

pH

The minimum and maximum pH effluent limits of 6.0 s.u. and 9.0 s.u. are water quality based effluent limits (WQBELs) that reflect the 11 Miss. Admin Code Pt. 6, Ch.2 requirement for the normal pH of waters to be in the range of 6.0 to 9.0 s.u.

Bromine and Bromide  

Monitoring for Bromine and Bromide are being removed from the permit because there is currently no state or federal water quality criteria for these pollutants.

Total Residual Chlorine (Submittal Requirement)

A narrative condition has been added to the permit requiring the permittee to monitor Outfall 001 for total residual chlorine once per month until twelve (12) samples have been collected and submit a report.  The report shall contain the pollutant analytical result, the discharge flow rate, and the pollutant analytical result of each monitoring event. The report is due within two (2) years after the permit effective date. Monitoring for chlorine shall be conducted only when the discharge contains cooling tower blowdown. If this data indicates a violation of water quality standards, the NPDES permit may be reopened and modified.