Hercules CAP Response Letter 02-02-21

ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
S. DANIEL SMITH
Director
NORTH CAROLINA
Environmental Quality
February 2, 2021
Chrissy Piechoski, Remediation Project Manager
Ashland Hercules Research Center
500 Hercules Road
Wilmington, DE 19808
Re Corrective Action Plan Report (CAP)
Former Cape Industries Waste Injection Facility (Hercules)
Wilmington, New Hanover County, North Carolina
Sent via Email as Attachment
Dear Ms. Piechoski:
The Division of Water Resources (DWR) received the Corrective Action Plan (CAP) for the
Former Cape Industries Waste Injection Facility (Hercules). Thank you. Staff has reviewed the
CAP and have the following few comments/requests.
Section 6 Numerical Model (MODFLOW, MT31))
It appears that there are incorrect references to sections in the CAP. In some cases, these references
pertain to sections in the previously submitted 2018 Site Assessment Report (SAR). For example,
in Section 6.3 of the CAP is the following:
In order to model the vertical transport, the MODFLOW domain included layers individually
representing the aquifers and aquicludes described in Section 3.3 and shown in Figure 31.
Section 3.3 in the CAP concerns analytical parameters. Section 3.3 in the SAR includes the
hydrogeologic layers. Please double check all references to sections and figures in the CAP and
correct where needed.
Section 8 Proposed Correction Actions
Section 8.3.4(9) states the following:
(9) that public notice of the request has been provided in accordance with Rule. 0114(b) of this
Section; and
• Public notice of this CAP submittal to the NCDEQ will be published for public notice per
Rule .0114(b) of this Section.
Please provide documentation that the requirements of 15A NCAC 02L .0114(b) have been met.
DNorth Carolina Department of Environmental Quality Division of Water Resources
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_ 512 North Salisbury Street 1 1636 Mail Service Center I Raleigh, North Carolina 27699-1636
NORTH CAROLINA
Department of Emimnmental Quality /`� 919.707.9000

NCDEQ Division of Water Resources
Groundwater Resources Section
3/22/2021
Page 2 of 2
Section 9 Corrective Action Performance Monitoring
The proposed 5-year monitoring frequency is inappropriate. The next sampling event should be
in 2022, which would be the scheduled time under the current 2-year monitoring cycle for this site.
After review of laboratory analytical results in 2022, staff may recommend a modification to a 3-
year monitoring frequency. Therefore, please provide a Monitoring Plan Table listing the wells,
parameters, and proposed frequency with the next sampling event occurring in 2022, and then
every 3 years thereafter.
Section 10 Summary
The third check mark item states the following:
Abandon wells once gas generation is negligible allowing for safe abandonment of the wells (or
sooner if a well is in imminent risk of failure).
Please include a Well Inspection Plan on how and when the wells will be inspected (i.e., visually
inspect, remotely or visually monitor pressure, how often, etc.). In addition to inspection methods,
the plan should also have in place contingency steps to take in the event a well is determined to be
in imminent risk of failure.
Conclusion
Please submit a revised CAP titled Corrective Action Plan (Revised) reflecting changes to the
items above. For the ease of the reviewer/reader, somewhere in the CAP please list those pages
that have been modified or sections where new pages have been inserted. This could be in the
cover or transmittal letter.
If you have any questions regarding this letter please contact me at Michael.Rogers(kncdenr.gov
or Rick Bolich at rick.bolich(kncdenr.gov
Sincerely,
Michael Rogers, PG (NC & FL)
UIC Program Manager - Hydrogeologist
NC Division of Water Resources
cc Morella Sanchez King, Wilmington Regional Office
Scott Andresini, GESOnline