1401_CaldwellCounty_CommentsCorrectiveMeasures_DIN28749_20180205

February 5, 2018

SENT VIA EMAIL

Ms. Karen Maye
P.O. Box 2200
905 West Avenue
Lenoir, North Carolina 28645

Re: DEQ Comments on Corrective Measures Study (dated December 1, 2017)
Former CSI Landfill
1200 Dragstrip Road
Hudson, North Carolina
EPA Identification Number: NCD 086 871 282

Dear Ms. Maye:

The Hazardous Waste Section (“HWS”) has completed review of the Corrective Measures Study (“CMS
Report”). The CMS Report was submitted on your behalf by Mr. Leo Moretz of Hart and Hickman in
response to a request from the HWS in correspondence dated May 16, 2017.

Specifically, the HWS requested that a Corrective Measures Study be developed and implemented to
address remnant groundwater contamination at the Facility. This request was made pursuant to
requirements cited in the January 16, 1998, Consent Decree between the United States of America and
Caldwell County et al., Section VII, Items 16 and 17. The CMS Report partially meets those requirements.
To fully meet the requirements, Caldwell County must revise the CMS Report in accordance with the
comments contained herein and begin implementing the agreed upon corrective action.

As noted in the CMS Report, the recommended corrective action addresses remnant groundwater
contamination. Soil impacts identified on the former Caldwell Systems, Inc., property have been previously
addressed under the direction of the US Environmental Protection Agency. Correspondence confirming
that no further action is warranted as it relates to soil impacts on the former Caldwell Systems, Inc., property
will be provided by the US Environmental Protection Agency under separate cover.

The corrective action recommended to address remnant groundwater contamination at the Facility is
monitored natural attenuation (MNA) in conjunction with previously-recorded Perpetual Land Use
Restrictions (LURs). For purposes of the proposed corrective action, the Facility is defined as three property
parcels, including the former Caldwell Systems, Inc., property; the Caldwell County Landfill; and the County
Property formerly known as the Haas Property.

This recommendation has been thoroughly researched and is supported by the following points:

• A well-established environmental monitoring program;
• A robust database of constituents of concern, concentrations, and trends;

• A decrease in total constituent concentration by more than 90 percent in comparison to their
respective maximum concentrations in most monitoring wells;
• The continuance of an environmental monitoring program to ensure the sustained protection of
human health and the environment;
• The technical feasibility of treating large, dilute, remnant groundwater impacts using MNA; and
• Recordation of a Declaration of Perpetual Land Use Restrictions prohibiting the following:
o The use of groundwater located at or under the property, including for drinking, bathing,
irrigation, watering livestock, or for any other purpose that cause groundwater to come into
contact, either directly or indirectly, with people,
o The installation of new water supply wells,
o The abandonment of all existing water supply wells,
o The restricted use of the property for solely industrial purposes.

Having completed review of the CMS Report and the information/data supporting the recommendation of
MNA, the HWS concurs that MNA is the best suited corrective action for this Facility. Although the HWS
agrees with the recommendation, there are several elements in the CMS Report that require clarification or
revision.

The HWS is not asking or requiring that additional field work be conducted in response to the comments
listed below. If these comments cannot be addressed by a file review, the HWS asks that a conference call
be scheduled to discuss how best to address the comment using existing information. Comments follow.

• The statement on Page 3 that “…. no further corrective action is required for Site soils” should be
amended to indicate that correspondence from the US Environmental Project Agency as it relates
to this subject is pending.

• The CMS Report states that “Elevated metal concentrations were determined to be the result of
naturally-occurring background conditions” (page 5). The CMS Report should be revised to provide
supporting documentation that all parties were in agreement regarding background conditions and
the subsequent elimination of metals as constituents of concern.

• Although 1,4-dioxane was detected in two of six monitoring wells (page 5) and in the Former Haas
Spring (page 11), this constituent ceased to be monitored after 1999. The CMS Report proposes
to sample for 1,4-dioxane during the next scheduled monitoring event in 2018 and to include this
constituent in all future monitoring events. The HWS concurs with this recommendation.

• Groundwater impacts were assessed as part of Phase I and Phase II RFI Investigations. Although
samples were collected from groundwater, surface water, and potable wells/domestic springs, the
lateral and vertical extent of groundwater impacts was not fully delineated due to offsite property
constraints (page 5). Data compiled during the RFI investigations were used to develop a site
conceptual model. It was mutually agreed by all Parties that LURs would be recorded and that an
environmental monitoring program would be established for the protection of human health and the
environment. The CMS Report should be revised to include cross sections illustrating the lithology,
hydrogeology, and contaminant plumes in the areas assessed.

• The HWS commends Caldwell County for updating the receptor survey (page 10). Table 4
summarizes the springs/wells and their status as of 2017. Two wells (Martha McLean and
Clearview Baptist Church) are listed on Table 4 as “active” and “not connected to County water.”

Although the Former Haas Spring is routinely sampled on an annual basis, the last comprehensive
spring/well sampling events occurred in 1998/1999 and these sampling points did not include the
Clearview Baptist Church. The HWS recommends that all nine sample points presented on Table 4
be added to the monitoring regime proposed in Section 6. If analytical results indicate the absence

of contamination, or if hydrogeologic conditions are such that continued monitoring cannot be
justified, Caldwell County may petition the HWS to exclude these monitoring points with supporting
justification. This may be stipulated in Section 6 of the revised CMS Report.

• Surface water samples and seep samples were collected as part of the Phase I and Phase II RFI
Investigations. The CMS Report does not specify the seep sample locations. For purposes of this
review, the HWS assumed that seep samples were collected near SW-5. The revised CMS Report
should provide clarification.

• Because the last surface water sampling event occurred more than 15 years ago, the HWS
recommends that the seven surface water sampling locations be added to the monitoring regime
proposed in Section 6. If analytical results indicate the absence of contamination, or if
hydrogeologic conditions are such that continued monitoring cannot be justified, Caldwell County
may petition the HWS to exclude these monitoring points with supporting justification. This may be
stipulated in Section 6 of the revised CMS Report.

• The spring/well locations are illustrated on Figure 5. There are two spring locations designated by
“5” on Figure 5. There are two surface water sample locations designated as “SW-7” on Figure 6.
These two figures should be corrected.

• Biological assessments were conducted in 1991 and 1992. Both assessments indicated that
streams had been impacted to varying degrees. Reportedly, the greatest impacts were localized
to areas immediately adjacent to the landfill. The CMS Report indicates that downstream locations
were only slightly impacted and recovery in the biologic condition was evident. The CMS Report
should be revised to provide specification regarding distances and recovery.

• The CMS Report indicates that no further action related to soil impacts is required (pages 3, 16,
19). Although the HWS concurs, the revised CMS Report should clearly and concisely discuss the
potential for soil contamination at all three parcels.

• The CMS Report provides indirect evidence documenting the occurrence of degradation processes
(i.e., decreasing constituent concentrations). The Phase I RFI Report indicates that natural
attenuation processes are favorable. The revised CMS Report should include greater discussion
related to natural attenuation/degradation processes. If applicable, the text from the Phase I RFI
Report may be used in the CMS Report.

Section 6 recommends MNA in conjunction with LURs as the final remedy to treat remnant groundwater
contamination. Section 6 describes the sample locations, the sampling frequency, and the analyte list. The
HWS concurs with this recommendation; however, the HWS recommends that the 2018 monitoring event
be expanded to include historic potable wells, springs, and surface water locations. These additional
sample locations are recommended in an abundance of caution. Should analytical results or Facility
conditions support the omission of these sample locations beyond 2018, Caldwell County may petition the
HWS to exclude these monitoring points with supporting justification. The same applies to monitoring wells
FPC-MW-01, MW-3A, MW-C, GM-6, and FPC-MW-07.

Section 6 also recommends a reduction in groundwater monitoring frequency from annually in 2018 to
biennially in 2020 and 2022 to every three years beginning in 2025. Monitoring will continue until constituent
concentrations are less than regulatory standards or risk-based remediation goals. The HWS concurs with
this recommendation and does not require revision to the schedule or the text.

Finally, the CMS Report must be revised to include a contingency plan in the event monitoring conditions
or constituent concentrations change. The CMS Report should include the events that would trigger the
contingency plan and the actions that would be implemented.

Please review the above comments. If you have any questions or comments I can be reached at 919-707-
8208 or via email at [e-mail]. If you do not have any questions or comments, the
revised CMS Report is due no later than March 30, 2018.

Sincerely,

Mary Siedlecki, Project Manager
Hazardous Waste Section
Division of Waste Management

ec: Karen Maye, Caldwell County
Stan Kiser, Caldwell County
Kathy Greene, Caldwell County
Robert King, III, Brooks Pierce
David Lackey, Wilson, Lacke & Rohr
Bud McCarty, Hazardous Waste Section
Mary Siedlecki, Hazardous Waste Section
Don Burke, Hazardous Waste Section
Jackie Drummond, Solid Waste Section
Mark Harper, Flynn Environmental
Leo Moretz, Hart and Hickman
Jason Tillotson, Hart and Hickman