9401_DomtarIndusLF_ASDMetalsRptResp_DIN28008_20170707

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July 7, 2017

Sent Via Email – [e-mail]

Ms. Diane Hardison
Domtar Paper Company, LLC
Highway 149 North
Plymouth, NC 27962

Re: Appendix I Inorganic Constituent Exceedances
Domtar Paper Company Landfill #3
Solid Waste Permit Number 9401-INDUS-2008
DIN 28008

Dear Ms. Hardison:

The Solid Waste Section (Section) has completed a review of the Appendix I Inorganic Constituent
Exceedances report (DIN 27403) submitted on behalf of Domtar Paper Company, LLC (Domtar) by TRC
Solutions (TRC) for the Domtar Paper Company Landfill #3, Solid Waste Permit Number 9401. The report
was submitted in response to correspondence from the Section titled Appendix I Inorganic Constituent
Exceedances dated August 8, 2016 (DIN 26550) and in accordance with 15A NCAC 13B .1633.

Domtar chose to address exceedances at both the active lined landfill, Landfill #3, and the closed unlined
landfill, Landfill #2. The monitoring network consists of two background wells (MW-1 and MW1A) and 12
compliance wells. Monitoring wells MW-2 through MW-6A monitor groundwater quality at Landfill #2
and Landfill #3 is monitored by wells MW-8 through MW-13. Groundwater samples have been collected
at the facility since 2000, but for the purposes of the alternate source demonstration, TRC reviewed the
laboratory analytical results from the previous five years. Based on data from the five-year period, the
constituents of concern at Landfill #2 were identified to be arsenic, beryllium, cadmium, cobalt, sulfate,
thallium, and vanadium while cobalt, nickel, sulfate, and vanadium were identified as the constituents of
concern at Landfill #3.

In addition to reviewing laboratory analytical data, TRC incorporated changes to the current sampling
methodology to reduce the influence of turbidity on monitoring results. Prior to sample collection in
October 2016, dedicated pumps and tubing housed within each well were permanently removed and the
wells were re-developed until sediment was no longer observed and water quality field parameters
stabilized. Groundwater samples were collected after the wells stabilized overnight using low flow purge
methods. Filtered and unfiltered groundwater samples were also analyzed to further evaluate the
influence of sediment on analytical results.

As a result of the monitoring well re-development, low flow sampling, and filtered vs non-filtered sample
analysis, arsenic and cobalt were the only constituents reported above regulatory standards. Cobalt was
reported above the Groundwater Protection Standard in both the filtered and unfiltered sample from
MW-1, MW-9, and MW-13. Arsenic was reported at concentrations above the standards established in
15A NCAC 02L .0202 in the unfiltered samples collected from MW-2 and MW-5. TRC cited the presence
of cobalt in the baseline samples collected from several monitoring wells prior to waste disposal and a
previous detection of arsenic in the background well as further evidence that the landfill is not impacting
groundwater at the facility.

Based on the overall reduction of inorganic concentrations following monitoring well re-development,
sampling methodology adjustment, and the results of the filtered versus nonfiltered samples; it appears
that groundwater sample analytical results have been influenced by suspended sediment. In addition,
the presence of elevated inorganic concentrations in background and baseline samples indicates the
possibility of those constituents as naturally occurring. Domtar should take precautions to ensure that
turbidity will not impact groundwater monitoring results by continuing to utilize low flow purge methods
and determining if a periodic well development schedule should be established. In addition, statistical
background concentrations should be calculated for arsenic, beryllium, cadmium, chromium, cobalt,
nickel, sulfate, thallium, and vanadium in accordance with 15A NCAC 13B .1634 (g)(5) to determine if any
future elevated concentrations are a result of landfill impact. Since it has been established that turbidity
impacted groundwater analytical results, statistical background concentrations should not be calculated
using previous monitoring data unless field notes indicate that turbidity values were less than 10
Nephelometric Turbidity Units (NTUs). Statistical background concentrations derived from turbid samples
may not accurately reflect background conditions, so Domtar should calculate statistical background
concentrations using analytical data from a minimum of ten groundwater samples with turbidity values
less than 10 NTUs. If there is an insufficient number of previous background samples with turbidity values
less than 10 NTUs or no field notes to verify the turbidity values, Domtar should establish a temporary
groundwater monitoring schedule to collect 10 or fewer samples from the background well within a two-
year period. If a temporary monitoring schedule is necessary, Domtar should submit the schedule to the
Section within 90 days of receiving this letter. Turbidity values should be recorded and submitted to the
Section during the temporary monitoring period. If Domtar declines to calculate statistical background
concentrations, additional assessment activities may be necessary.

Additional guidelines for calculating statistical background concentrations are listed below:
 If utilizing Upper Tolerance Limits, determine the new groundwater protection standards for the
metals of concern by the distribution hierarchy normal, gamma, lognormal, and nonparametric;
 Identify the outliers. Screen the data sets visually for potential outliers using the box-and-whisker
and Q-Q plots. Then screen the data sets quantitively using Dixon’s or Rosner’s Outlier tests as
specifically identified within the USEPA March 2009 Unified Guidance. If statistical outliers have
been detected, review the values to determine if they should be removed from the data set or
are representative of background and should be retained for statistical analysis. Provide technical
reasons why a statistical outlier should be included or excluded from either groundwater
background data sets;

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 919.707.8288. Thank you for your continued cooperation with this
matter.

Sincerely,

Ervin Lane
Compliance Hydrogeologist
Solid Waste Section, Division of Waste Management
NCDEQ

cc sent via email: Ellen Lorscheider, Solid Waste Section Chief
Jason Watkins, Field Operations Branch Head
Drew Hammonds, Eastern District Supervisor
Ray Williams, Environmental Senior Specialist
Ed Mussler, P.E., Permitting Branch Head
Elizabeth Werner, Permitting Hydrogeologist
Larry Frost, Permitting Engineer
Dan O. Madison, P.G., TRC Solutions