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DEQ-CFW 00061309

QW.DuPont Fluoroproducts
22828 NC Highway 87 W
Fayetteville, NC 28306-7332
February 13, 2008
Ms. Teresa Rodriguez
NCDENR Division of Water Quality
512 N. Salisbury Street
Archdale Building — Room 925
Raleigh, North Carolina 27604 DENR. -F'RO
FEB 18 2008
SUBJECT: NPDES Permit Minor Modification Request DWO
DuPont Company — Fayetteville Works
NPDES Permit No. NC0003573
Dear Ms. Rodriguez:
The DuPont Company — Fayetteville Works requests a minor modification of the subject
NPDES Permit so that we may proceed with two Authorization to Construct applications for the
N.C. Division of Water Quality's Construction Grants and Loans Section. The two requested
modifications are described below.
ADDITION OF THIRD CLARIFIER
The first requested modification is to change the Supplement To Permit Cover Sheet to
allow for the operation of a third clarifier. This new clarifier will be sized so that it can manage
the entire flow from the site's Wastewater Treatment Plant (WWTP). However, DuPont requests
that the new language allow for continued operation of one or both of the existing clarifiers,
either independent of or with the third clarifier.
DuPont requests that the permit's Supplement To Permit Cover Sheet modification be
worded so that the site would continue to operate the two existing clarifiers until such time that
the third clarifier is constructed and operational, at which time the site would operate some or all
of the three clarifiers.
It is expected that the operation of the third clarifier will improve the solids removal from
the treated WWTP effluent. As such, DuPont is not requesting any change to the current NPDES
permit limits for Total Suspended Solids at Outfall 001.
E.I. du Pont de Namours and Company
DEQ-CFW 00061310

Ms. Teresa Rodriguez
N.C. Division of Water Quality
February 13, 2008
Page 2 of 2
RELOCATION OF EFFLUENT DISCHARGE INTO THE CAPE FEAR RIVER
The second requested modification is to change the map that follows the Supplement To
Permit Cover Sheet to allow for the relocation of site's final effluent discharge into the Cape Fear
River to a point upstream of Lock & Dam 3. The reason for this relocation is to stop the erosion
that is occurring in the current effluent channel and the ensuing discharge of soil sediment into
the river.
The December 7, 2007 letter from Mr. Gil Vinzani, N.C. Division of Water Quality, to
DuPont stated that the Division reviewed the QUAL2K modeling report and concurs that the
above relocation will not affect the dissolved oxygen levels in the Cape Fear River, and that
DuPont could proceed with a permit modification request to relocate the discharge.
For your convenience, attached is a photocopy of the NPDES Permit's map with an
indication of the approximate location of the proposed discharge point into the river.
DuPont requests that the permit's modification be worded so that the site would continue to
discharge at the existing location in the river until such time that the new effluent conveyance
system is constructed and operational, at which time the site effluent would discharge to that
location.
The relocation of the effluent discharge will not change the quality of the effluent, and as
such, DuPont is not requesting any change to the current NPDES permit limits for Outfall 001 or
Outfall 002.
Should you have any questions regarding this requested permit modification, please feel free
to call me at [phone].
Environmental Manager
Attachment
DEQ-CFW 00061311

DuPont Fayetteville Works - NC0003573 Facility
Location
USGS Quad Name: Duart Lat.: 34°49'53"
Receiving Stream: Cape Fear River Long.: 78°49'23"
Stream Class: C Not to SCALE
Subbasin: Cape Fear - 030616 North
DEQ-CFW 00061312