DEQ-CFW_00042515

DuPont Engineering
6324 Fairview Road
Charlotte. TNC28210
DuPont Engineefing
Mr. Larry Stanley I
1646 Mail Service Center
Raleigh, NC 27699-1646 1
fkle: October 6,2004 Meeting Summary and Path Forward
This letter summarizes the October 6, 2004 meeting regarding the Phase I Supplemental RC
Facility Investigation (RFI) Report comment letter (June 25, 2004) and our proposed path
forward. For ease of discussion, comments presented in the June 25, 2004 coff espondence ar
addressed below. Presented separately is a summary of the proposed path forward discussed i
the meeting. I
Comments 1, 2, 4, 5, 6, 8, and 9 are associated with text corrections and will be addressed in
the revised report.
Comment 3: Per Michael E. Johnson, Environmental Manager of the DuPont - Fayetteville
Works, ammonium perfluorooctanoate was first produced by the site's APFO Manufacturing
Facility on November 23, 2002. The final APFO product is shipped to either a DuPont facility
in West Virginia or to a Daikin America facility in Georgia. From 1989 until 1991, DuPont -
Fayetteville Works operated a Teflong AF manufacturing facility that used C-9 as the
surfactant. It is possible that the C-9 surfactant contained C-8 as an impurity, however it is
impossible to prove or disprove that possibility. Recent testing at the Fayetteville site suggests
that C-8 is being created in at least some of the Naflong Division manufacturing processes as
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an unwanted by-product in trace (parts per trillion) concentrations. If this is the case, then it i
reasonable to expect that these trace levels of C-8 have been produced by the Nafions Divisi
since its start-up in 1980. APFO has never been used as a raw material or ingredient at the
DuPont - Fayetteville Works. I
the same analytical method used for the equipment blanks. The difference in the detection
limits was due to the sediment in the collected groundwater samples causing a reduction in
sample volume thereby requiring an increase in the method detection limit. The difference in
detection limits does not effect DuPont's conclusions. Also individual compounds typically
associated with diesel were not detected above the laboratory detection limits in groundwater
samples collected from the monitor wells associated with the fire training area.
Comment 11: The historic groundwater flow in the vicinity of the former fire training area will
be evaluated and discussed in the revised Supplemental Phase I RFI Report and Phase 11 RFI
Report. If additional monitoring points are warranted, these additional points will be included
in the Phase 11 RFI Work Plan.
Comment 12: A revised figure will be included in the revised Supplemental Phase I RFI
Report. As discussed in the meeting, windows may be present in the clay layer underlying the
site. DuPont will propose monitor wells in the Nafion area to be installed beneath the clay
layer to examine groundwater quality down gradient of this area.
Comment 13: Additional monitor wells are being proposed to examine groundwater quality
downgradient of the Nafion area. The placement and number of the additional monitor wells
will be determine based the additional potentiometric surface evaluation to be conducted in
fourth quarter 2004 and placement of the additional monitor wells will be addressed in the
Phase 11 RFI Work Plan.
Work Plan.
that details additional investigative work at the site.
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Access to this area of the site is limited to a one week per year. The Naflon area is scheduled
for shut down the week of November 8, 2004. Given this narrow time window, DuPont wish
to proceed with the monitor well installation is this area before submittal of the formal RFI
Phase 11 Work Plan. The monitor wells will be installed using hollow stem auger technology i
a manner described in past RF1 Work Plans. One monitor well will be keyed in to the top of
the clay layer underlying this portion of the site (approximately 15 feet below the ground
surface). A second paired monitor well will be installed to a depth below the clay layer at
approximately 40 feet. The two new monitor wells will be sampled for the same constituents
as with previous sampling efforts. I
Additionally, three piezometers will be installed in the immediate vicinity of the river water
holding ponds (see attached figure). The piezometers will also be installed using direct push
methodology as described in past RFI Work Plans. The piezometers will be installed at a depth
corresponding to the top of the clay layer underlying this portion of the site (approximately 15
feet below the ground surface). Upon completion of the piezometers and monitor wells a full
round of water level measurements will be collected from the newly installed points as well as
existing monitoring points across the site. This new potentiometric data will help to guide
placement of monitor wells in the vicinity of the Naflon area.
If you have any questions or need ad-&-b-o—naTintiormation jiFe-as—e le-EFIFce to contact m`e--aFTfzF
362-6626.
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Project Director
cc: Mike Johnson - DuPont Fayetteville Works
File
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DRAWN; APPROVED. PRWECTNO.:
Nafion Proposed Blast Zone Monitoring Well / Piezometer Location Map
RATE REMEDIATION GROUP DuPont Fayetteville Works CHECKED. DATE: VY1164 FIGURE NO.:
An Alliance between
6324 Faurvem Road FILE
OEQ-CFVV_00042518