DEQ-CFW_00025379

Hazardous Waste Section
File Room Document Transmittal Sheet
M
Your Name: Larry Stanley
EPA ID: N C D 0 4 7 3 6 8 6 4 2
Facility Name: DuPont -Fayetteville
Document Group: Corrective Action (CA)
Document Type: RCRA Facility Investigation (RFI)
Description: Second Phase III RFI quarterly update
Date of Doc: 5/29/2012
Author of Doc: DuPont-CRG
File Room Use only _ CD047368642
Month I Day Year
Date Recieved by File Room: to Scanner's Initials:
Date Scanned: to Q
DEQ-CFW 00025379

DuPont Engineering
^y, 6324 Fairview Road
Charlotte, NC 0
36
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May 29, 2012
Elizabeth•
Hazardous Waste Section, Division of Waste Management
North Carolina Department of Environment and Natural Resources
•4a Mail Service Center
Raleigh, ••• 64
.kE: SECOND QUARTER PHASE
y UPDATE
k..
DUPONT FAYETTEVILLE WORKS
i NORTH 1 .. i
Due to the specificdata gaps left in the investigation,objectives of
Phase III RFI must be completed and the data -f prior toimplementing the - r
stageinvestigation for other objectives. The Phase III RFI, therefore, is being implemented
in a "staged" approach. Stage 1 of the investigation consists of further delineation of
the perimeter of the clay lens in the northern and western portions of the Site. This
of - RFI will helpto meet Objective 1 in the work• r further characterize
site • •• • •ric conditions). The main f• of objective f refine the site
conceptual model by • - • data • fill data gaps pertaining to where
groundwater occurs (both perched and aquifer) and where it flows. To meet this
objective, - lateral extent and internal continuityof - clay lens present
vadose zone above the groundwater aquifer must be determined.
February
As previously reported in the First Quarter 2012 Phase III RFI Update letter (dated
i the initial step of .•' 1 investigationto determine
which geophysical techniques,r • be - determining the extent of
(both• density of • layers (clay versus
-
s whether saturated conditions are present. -• on of
DEQ-CFW 00025380

Page 2
May 29, 2012
Ms. Elizabeth W. Cannon
of geophysical survey- • • -• at the Site in January 2012by
Geophysicalr a project determined that
ground penetrating radar (GPR) and electromagnetic induction (EM) surveys could
provide useful information to help meet the objective of Stage 1 of the Phase III RFI
r- •-• to perform these two surveys along the remaining geophysical lines
representativeidentified in the approved work plan. This path forward was discussed with the Site's
NCDENR on 1
oil
As described in Section 4.1 of the work plan, delineation of the clay lens will not be
limited to only geophysical interpretation. Lithologic logging using a Geoprobeo
direct -! direct -push rig will be performed to confirm the survey results at several locations
where the EM • GPR" surveys suggest-rr- to the clay lens. The
locations will be selected based on an evaluation of the results of the surveys as
presented in the GSI summary report. The Geoprobeo rig will also be used to
determine the clay lens thickness and whether perched water is present at these
locations and to investigate areas where the survey results were inconclusive.
Geoprobee rig will not be used at every location along the entire survey lines.
It is anticipated that the Geoprobeo activities will be conducted in June or July 2012,
as scheduling permits. Once the results of these activities have been evaluated, a
technical memorandum with recommendationsfor •e of Phase III ':
will be prepared and submitted to NCDENR for review and discussion.
If you have any questions or if I can assist you further in any way, please do not
hesitate to [e-mail] 04
362-6626. The Third Quarter 2012 Phase III RFI Update will be submitted by August
Sincerely,
6 tZ�
Jamie VanBuskirk
Project Director, DuPont Corporate Remediation Group
cc; Mr. Larry Stanley — NCDENR, Hazardous Waste Section
s. Tracy Ovbey — Parsons Environment & Infrastructure Group
r. Mike Johnson — DuPont Fayetteville Works
File
DEQ-CFW 00025381