PRETREATMENT RATIONALE FOR REISSUANCE

Entergy Mississippi LLC, Delta Blues Advanced Power Station
Washington County
Greenville, MS
Agency Interest (AI) No. 86260

	MSP094278
SIC: 4911
April 23, 2025
Permit Engineer: Thomas Kelly
Water I Branch
	
I.	FACILITY INFORMATION

A.	Nature of Business: Electric Power Generation
B.	Process Wastewater Description: Ultrafiltration reject water, reverse osmosis reject water, service water and power block contact stormwater, non-contact stormwater runoff, HRSG blowdown
C.	Proposed Flowrate: 0.383 MGD (estimated)
D.	Applicable Federal Guidelines: None. Non-categorical Industry - SIU

II.	RECEIVING POTW INFORMATION

A.	POTW and Permit Number: Greenville POTW (AI# 13154, MS0020184)
B.	POTW Treatment Type: Biological by means of activated sludge, ultraviolet disinfection or chlorine disinfection.
C.	POTW Design Flowrate: 20 MGD
D.	POTW Receiving Stream: Mississippi River
E.	POTW Receiving Stream 7Q10 (Q7/10): 120000 cfs

III.	NOTABLE SAMPLING DATA FOR PERMIT APPLICATION:  (Form 2P)

1Because this facility has not been constructed; the facility has utilized effluent characteristics from a similar facility to estimate the above pollutant concentrations. 

IV.	PROPOSED PERMIT LIMITATIONS

Outfall 001

Parameter	Monthly Avg	Daily Max	Minimum	Monthly Avg	Daily Max	Sampling Frequency	Sample Type	Basis of Decision1	
Flow	Report MGD	Report MGD	---	---	---	Continuously	Continuous Recorder	TJ	
Temperature 	---	---	---	Report ºF	Report ºF	Twice per month	Instantaneous Sampling	TJ	
pH	---	---	6.0 SU	---	9.0 SU	Twice per month	Grab sampling	TJ	
1Basis:  TJ = Technical Judgment

Other Permit Requirements

•	Submit DMRs to the City of Greenville:

The permittee shall submit the monthly Discharge Monitoring Report (DMR) to the City of Greenville via email (environmental@greenvillems.org). The DMR submission shall be done through the MDEQ NetDMR system due no later than the 28th day of the month following the completed reporting period. The DMR recipient's email address (environmental@greenvillems.org) should be added in the "DMR Submission Notification" section of NetDMR [11 Miss. Admin. Code Pt. 6, R. 1.1.4.A(4)].  This requirement is based on a stipulation requested by the City of Greenville Mayor’s Office in their letter dated June 17, 2024.

•	Application Submittal Requirement:

Within 6 months (180 days) of commencing discharge of effluent, the permittee shall submit to the MDEQ Environmental Permits Division a completed Form 2P application containing results of data collected from the facility's process wastewater discharge. The sampling data shall be representative of normal power generation activities. Based upon the results of the sampling, the permit may be reopened to address additional limits or requirements as deemed necessary to protect the POTW or water quality. Submit an application: Due within six months after permit effective date. [11 Miss. Admin. Code Pt. 6, R. 1.1.4.A(4)]

X.	STATEMENT OF BASIS 

 The discharge limitations are based on Technical Judgment (TJ) and agreed upon by the City of Greenville Mayor’s Office in their comment letter dated April 15, 2025. 
APPENDIX A

ADEQUACY OF TREATMENT