DEQ-CFW_00034519

(MD.
DuPont Engineering
Mr. Larry Stanley
Hydrogeologist
NCDENR
1646 Mail Service Center
Raleigh, NC 27699-1646
Re: Response to Comments
RCRA Phase I Report
DuPont FMPXMVW
6324 Fairview Road
Charlotte, NC 28210
T& (704) %2-45&V
Fax (7K 3Q-VaM
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2003 V,
Received
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Enclosed for your review are DuPont's responses to the May 14, 2003 and June 5, 2003
correspondences commenting on the RCRA Phase I Report. For case of discussion the
comments �*resented in the referenced corres,:rit�ence are :insented in Italics. The rep y--tnse to
each comment follows in standard font.
1. DuPont Fayetteville should mention the analytical methods used to analyze the soil and
groundwater samples collectedfor this report. Thefacility may report this Ope of
information in the sections of the report that discuss each unit individually. In addition,
DuPont Fayetteville should list the constituents of concernfor each unit. Instead of this
list, DuPont could cite the work plan for Phase I of the R.Y. The citations should include
the section or appendix where this information can befound
Revised report Sections 4.4.1, 4.4.2, and 4.4.3 address this comment. Changes made to t
report text are present in bold font. Three copies of the replacement text as well as a revis
Table of Contents are enclosed for your insertion 11
F— DuPont -Fayetteville should update the soil and groundwater standards listed in various
tables producedfor the Phase I report. The standards for several constituents have
changed recently. In most cases, the changes are minimal and do
DEQ-CFW-00034519

Page 2 of 3
August 18, 2003
presented in the report An updated table (i. e. Appendix 3) is enclosed with these
comments.
In addition, some standards are not listed correctly. For example, the NC 2L Standardf]
bis(2-ethylhe_xy1)phthalate is 0. 003 mg1l and not, as listed in the table 3 mg1l DuPont
should checkfor these conversion discrepand
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tables accordingly. The conclusions offered in the RF1 Phase I Report have not changed
utilizing the new standards. Three copies of the revised data tables are enclosed for your
insertion.
3. Guidance titled "Guidelines for Establishing Remediation Goals at RCRA Hazardous
Waste Sites" discusses the preliminary groundwater screening process recommended by
the HWS. According to this document, afacility should petition the Groundwater Section
for an LVL4C (Interim Maximum Allowable Concentration) if a constituent does not have an
assigned 2L Standard. The guidance document cited here can be viewed or copied by
visiting the H)TSs web site (http:wastenot.enrstate.nc).
At this time, the Fayetteville Works facility is not in a remedial phase. In the Phase I Report,
when a NC 2L standard was not available, screening criteria uses was for the purpose of
identifying constituents of concern to carry forward in the investigation stage. When the
remedial phase at the site is reach, DuPont will petition for an IMAC in accordance with the
applicable guidelines, if necessary.
4. Some monitor wells not located immediately downgradientftom SWMU 6-Common Sump
detected hazardous constituents at concentrations exceeding NC 2L Standards. The HWS
understands that DuPont -Fayetteville plans to develop a groundwater monitoring program
for the Naflion Area. However, it seems unlikely that the hazardous constituents reported
for either monitor wells NAF-01 or NAF-04 originated at SWMU 6 The HWS suggests that
DuPont -Fayetteville discuss other potential sources for the hazardous constituents which
exceed the 2L Standard. This discussion can be based upon DuPont's current knowledge of
the site.
As discussed in the June 29, 2003 conference call, DuPont desires to collect and review
additional data from monitor wells and piezometers associated with SWMU 6. Upon receipt
and review of the data, DuPont will request an on -site meeting with DENR personnel to further
discuss our understanding of site conditions and constituent migration as well as possible
additional sources, if any.
5. In 1999, DuPont -Fayetteville excavated soil at theformerfire training area. Even at twelve,
feet (essentially at the water table), soils showed relatively high concentrations of diesel
range TPH. As discussed in the Phase I report, DuPont intends to sample the wells near
this unit again, and the HWS recommends that TPH be added to the list of constituents of
concern.
DEQ-CFW-00034520

NEW
direction is probably afew degrees south of monitoring point PTA-01. Eventually,
xcffy �e xo�,&Z, tf Atmdxe4f-&,--ftXm-Vrf1re I'ATiXg ftrez
source ofgroundwuter contamination,
After a May 29, 2003 conference call, DuPont received a letter dated June 5, 2003 from the
HWS agreeing with the interpretation of the subsurfitce data.
6. The HWS recommends that DuPont -Fayetteville use hand bailers during the next
groundvmter sampling event DuPont may use lou,-flow techniques during subsequent
sampling events.
Hand bailers will be utilized to collect groundwater samples during the next sampling event.
pwate I i-irfte ";Virk Tkm
-Z or cncurence with this letter. DuPont understands that low -flow sampling tecbuiques cann be
utilized in subsequent sampling events.
In summary, the June 5, 2003 correspondence requested DuPont expand the site conceptual
DuPont bas revised the site conceptual model (SCM) in Section 5.1.2 of the Phase I Report to
V 1 6"-
h"I 111W110 Mt 6
If you bave any questions regarding the response to the above comments please feel free ti
contact me at 704-362-6626.
Sincerely,
JamieV k
Project Director
cc: Michael Johnson — Fayetteville Works
File
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DEQ-CFW-00034521