6301_Moore_MSWLF_GWCARespone_DIN28746_20180213

February 13, 2018

Sent Via Email - [e-mail]
Mr. Chad Beane
Moore County Solid Waste
P.O. Box 1927
Carthage, North Carolina 28327

Re: Groundwater Corrective Action Milestone Schedule
Closed and Unlined Moore County MSW Landfill
Moore County
Solid Waste Permit Number 6301-MSWLF-1979
DIN 28746

Dear Mr. Beane:

The Section has completed a review of the Groundwater Corrective Action Milestone Schedule dated January
31, 2018 (DIN 28745) that was submitted on your behalf by Golder Associates NC, Inc. for the closed and
unlined Moore County MSW Landfill, Permit Number 6301-MSWLF-1979.

Within the Section’s September 28, 2017 letter to the County (DIN 28498), the Section stated that the current
passive groundwater selected remedy that was implemented in 2006 does not appear to be working as
effectively as designed. The continued groundwater exceedances at the closed and unlined MSW Landfill are
a violation of the following: 15A NCAC 02L .0103, 15A NCAC 02L .0106, 15A NCAC 02L .0107, 15A NCAC 02L
.0108, 15A NCAC 02L .0202, 15A NCAC 13B .0503(2), 15A NCAC 13B .0601, NCGS 143-214.1, and the landfill’s
December 20, 1996 closure letter. In response to the letter and a subsequent meeting, the Groundwater
Corrective Action Milestone Schedule has been submitted that outlines the County’s proposed remedies to be
performed in a phased approach (Phase I, II, and III) and includes a completed NC Solid Waste Section .0500
Groundwater Corrective Action Application.

Moore County has selected the following groundwater corrective action remedy at the landfill: a methane cut
off trench, replacement of groundwater monitoring well MW-15 with MW-15R, and Monitored Natural
Attenuation (MNA). In addition, a Landfill Gas Remediation Plan dated January 31, 2018 (DIN 28747) was
submitted under a separate cover. The selected remedy is proposed to restore groundwater quality at and
beyond the MSW’s relevant point of compliance, to effectively reduce the overall groundwater contamination
at the MSW Landfill, and to control the migration of contaminated groundwater to prevent unacceptable
impacts from the MSW Landfill.

Phase I includes the following:
• Installation of the methane cut-off trench to the south of MW-15 and to a depth to encounter the top
of groundwater to be completed by September 15, 2018;
• Replacement of MW-15 with MW-15R to be completed by September 15, 2018 and as approved within
the Assessment Monitoring Plan for the active C&D landfill (DINs 28724 and 28725);

• Conversion of MW-15 to a compliance methane monitoring well and install a turbine vent to help
prevent migration of methane toward the property boundary as approved within the Assessment
Monitoring Plan for the active C&D landfill (DINs 28724 and 28725); and
• Continuation of MNA.

After the installation of the methane cut-off trench and the replacement of MW-15, the County is requesting
until November 15, 2019 to evaluate these actions as a groundwater remedy and allow the County the
opportunity to complete two semiannual water quality monitoring events on the newly installed replacement
monitoring well (MW-15R). If the methane cut-off trench remedy is successful in reducing VOC concentrations
in the replacement monitoring well MW-15R, then the remedy will be evaluated for other areas of the site
along the northern property line (e.g., MW-6).

As stated within the Groundwater Corrective Action Milestone Schedule, if the second semiannual groundwater
quality monitoring results in 2019 for replacement monitoring well MW-15R does not show a declining trend
of VOCs, then Phase II of the groundwater corrective action will be implemented. Phase II, as currently
proposed, would include the installation of an injection monitoring well south of the methane cut-off trench
near MW-15R, commencement of a pilot test for enhanced bioremediation via super-aerated water (SAW)
injections near MW-15R (as an initial pilot study), and continuation of MNA. If the SAW injections fail to reduce
VOC concentrations below the NC 2L Standards, Phase III will be initiated. Phase III, as currently proposed,
would include commencement of a microcosm study to evaluate bacteria and carbon sources in the subsurface
in MW-15R, injections of SAW and bacteria or additional carbon (e.g., lactate, etc.) in the injection well, and
continuation of MNA.

Based upon a review of the Groundwater Corrective Action Milestone Schedule and the NC Solid Waste
Section .0500 Groundwater Corrective Action Application, the selected remedy and the proposed Phase I
activities only are approved as described.

If the second semiannual groundwater quality monitoring results in 2019 for replacement monitoring well MW-
15R and for the historically VOC contaminated downgradient wells MW-6, MW-7, MW-8, and MW-9 do not
show a declining trend of VOCs, then within 90 days of November 15, 2019, the County shall submit a
completed Corrective Action Plan for the implementation of in-situ remediation via injections in accordance
with the corrective action guidance document titled NC Solid Waste Section Guidelines For Corrective Action
At Solid Waste Management Facilities.

If you have any questions or concerns regarding this letter, please feel free to contact me by email at
[e-mail] or by phone at 828.296.4706. Thank you for your cooperation with this
matter.

Sincerely,
Jaclynne Drummond
Hydrogeologist
Solid Waste Section, Division of Waste Management
NCDEQ

cc sent via email: Ed Mussler, Section Chief
Jason Watkins, Field Operations Branch Head
Adam Ulishney, Environmental Compliance Branch Head

Drew Hammonds, Eastern District Supervisor
Amanda Freeman, Senior Environmental Specialist
Donna Wilson, Permitting Branch Engineer
Wayne Vest, Moore County Manager
Randy Gould, Moore County Public Works Director
Ben Draper, Golder Associates NC, Inc.
Rachel Kirkman, Golder Associates NC, Inc.