8003_RowanCounty_MSWLF_RevertDetectionResponse_DIN28735_20180202

February 2, 2018

Sent Via Email - [e-mail]
Mr. Caleb Sinclair
Rowan County
1102 N. Long Street Extension
Salisbury, NC 28144

Re: Request to Revert to Detection Monitoring
Rowan County Landfill
Rowan County
Solid Waste Permit Number 8003-MSWLF-1988
DIN 28735

Dear Mr. Sinclair:

The Department of Environmental Quality’s Solid Waste Section (Section) has completed a review of the
Request to Revert to Detection Monitoring dated December 1, 2017 (DIN 28734) and submitted on behalf
of Rowan County by Golder Associates for the Rowan County Landfill, Solid Waste Permit Number 8003-
MSWLF-1988. The landfill entered into the Assessment Monitoring Program in accordance with 15A NCAC
13B .1634 in 2017. Assessment Monitoring was initiated in response to the presence of the volatile
organic compounds Tetrachloroethene (PCE) and Trichlorofluoromethane (TCFM) within groundwater
monitoring well MW-28.

Rowan County installed a new groundwater monitoring well, MW-28R, to replace MW-28 that monitors
Phase IV of the landfill, and conducted two Appendix II monitoring events in 2017. No organics exceeded
the NC regulatory standards for two consecutive groundwater monitoring events. Therefore, Rowan
County is requesting for the landfill to revert to the Detection Monitoring Program in accordance with
15A NCAC .1634(e).

Based upon the information provided within the Request to Revert to Detection Monitoring and the 2017
monitoring reports, the request to revert to the Detection Monitoring Program is conditionally approved
at this time. Rowan County may return to analyzing for the Appendix I constituents, however, Rowan
County is required to address the inorganic exceedances at the landfill.

The Section is aware that an Alternate Source Demonstration dated July 14, 2008 (DIN 5234) was approved
on September 12, 2008 (DIN 5804) for thallium and vanadium. This Alternate Source Demonstration was
approved after assessment activities were completed related to the leachate release that occurred at the
landfill. Rowan County received a Compliance Order for that leachate release on June 11, 2007, and at
that time, thallium and vanadium were detected in the now abandoned piezometers PZ-1 and PZ-2. These
two piezometers were installed specifically for the assessment activities related to the leachate release.
Even though this Alternate Source Demonstration related to the leachate release was approved in 2008,

ten years have lapsed and site conditions may have changed. In addition, inorganics are consistently being
detected in the landfill’s leachate sample, L-1. Therefore, the 2008 Alternate Source Demonstration is
required to be reevaluated.

The Section has reviewed the following documents submitted regarding the inorganic exceedances at the
landfill: the 14 Day Notification and Alternate Source Demonstration for Barium and Cobalt in MW-28
dated October 13, 2016 (DIN 28049), and the 14 Day Notification and Alternate Source Demonstration
dated March 13, 2017 (DIN 28633). Based upon a review of those two documents and historical
monitoring reports, the Section is requiring additional information to be submitted, in a phased approach
if applicable, in an ASD Addendum. The Section is requesting Rowan County to address the following in
the ASD Addendum:

• A further clarification of the statistical methods used.
• Review the turbidity data for groundwater monitoring data used to calculate the statistical
background values. Analytical data from turbid samples cannot be used to calculate background
levels because background levels derived from turbid samples do not accurately represent
background conditions. The purpose of collecting and analyzing groundwater samples is to obtain
a representation of constituents that are mobile in groundwater. This can usually be achieved
when clear samples are collected from wells that have been properly constructed and developed
so that sediment in the water is minimal. However, for samples that are not clear, it is difficult to
differentiate between sediment that represents formational material versus mobile particulates
or precipitates (excerpted from May 13, 2013 Aquifer Protection Section Memorandum, Subject:
Aquifer Protection Section, Division of Water Resources, Policy for Metals Determinations
Required by Title 15A, NCAC, Subchapter 2L).
o Provide evidence the groundwater data used to calculate the new background levels were
from non-turbid samples. If the samples used were turbid, then Rowan County must
establish a temporary groundwater monitoring schedule to collect the required number
of non-turbid samples from the background well. This may be accomplished within a two-
year period. Include the temporary groundwater monitoring schedule in the Alternate
Source Demonstration Addendum. Turbidity values must be recorded and submitted to
the Section during the temporary monitoring period.
o In calculating background levels, groundwater sample data with documented or
suspected turbidity measured at greater than 10 NTUs should be removed from the
dataset and calculations rerun.
o Statistical background levels must be calculated using monitoring data from a minimum
of ten groundwater samples where the turbidity is less than 10 NTUs.
• Determine if the groundwater monitoring wells at the landfill should be periodically developed to
reduce the impact of suspended sediment.
• Determine if the sampling methodology should be modified.
• Determine if seasonality plays a role.
• Reevaluate the 2008 Alternate Source Demonstration for thallium and vanadium.

Within 120 days of receipt of this letter, please submit an ASD Addendum that addresses Section
comments above and meets the criteria described in the guidance document titled NC Solid Waste Section
Guidance for Alternative Source Demonstration Submittals for Solid Waste Management Facilities - 2017.
Upon submittal of the requested information, the Section will evaluate the ASD Addendum. Be advised
that additional information or analyses may be requested. Additional requirements consistent with the
ASD Guidance document may include, but are not limited to, collection of valid background samples to

establish site background levels, statistical analyses, trend analyses, review of sampling procedures, or
other means necessary to establish the landfill has not contributed to groundwater standards
exceedances.

Please note that if Rowan County decides not to submit an ASD Addendum within 120 days, the landfill
will be required to reinitiate Assessment Monitoring.

If you have any questions, please contact me by email at [e-mail] or by phone
at 828.296.4706.

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

cc sent via email: Greg Greene, Rowan County
Jeff Boyd, Rowan County
Ed Mussler, Section Chief
Adam Ulishney, Environmental Compliance Branch Head
Jason Watkins, Field Operations Branch Head
Deb Aja, Western District Supervisor
Kim Sue, Senior Environmental Specialist
Ming Chao, Permitting Engineer
Ben Draper, Golder Associates
Rachel Kirkman, Golder Associates
Michael Plummer, HDR