7304_UpperPiedmontMSWLF_ASDMetalsResp_DIN28427_20170911

September 11, 2017

Sent Via Email - [e-mail]
Mr. Matt Einsmann
Republic Services of North Carolina, LLC
9650 Oxford Road
Rougemount, NC 27572

Re: Alternate Source Demonstration
Upper Piedmont Regional Landfill
Solid Waste Permit Number 7304
DIN 28427

Dear Mr. Einsmann:

The Solid Waste Section (Section) has completed a review of the Alternate Source Demonstration report
(DIN 27402) submitted on behalf of Republic Services, LLC (Republic) by Joyce Engineering (Joyce) for the
Upper Piedmont Subtitle D MSW Lined Landfill, Solid Waste Permit Number 7304. The Alternate Source
Demonstration was submitted to address detections of cobalt at concentrations above the Interim
Maximum Allowable Concentration (IMAC) in addition to iron and manganese concentrations exceeding
the standards established in 15A NCAC 02L .0202 (2L Standards).

The Alternate Source Demonstration submittal included a statistical evaluation of background
concentrations, comparison to landfill leachate analytical results, and a presentation of data from the
Geological Atlas of North Carolina related to the natural occurrence of cobalt, iron, and manganese in
stream sediment. Joyce concluded the concentrations of cobalt, iron, and manganese reported in
groundwater samples are derived from the natural occurrence of those constituents in bedrock, soil,
and/or sediment. Joyce proposed to establish a background value of 31.5 g/l for cobalt in contrast to
the current IMAC of 1 g/l. Joyce also requested to cease monitoring for iron and manganese since those
parameters are not included in the Appendix I or II constituent list.

Republic agreed to analyze groundwater samples for iron and manganese in 2007 after receiving a joint
request from the Section and the Division of Water Quality (now Division of Water Resources) – Surface
Water Protection Section (DWQ-SWP). Elevated iron and manganese concentrations were reported in
surface water samples collected from Cub Creek by DWQ-SWP staff. Iron and manganese analytical
results from groundwater samples were intended to help the DWQ-SWP determine the cause of elevated
surface water sample concentrations. The DWQ-SWP was not able to establish a link between the iron
and manganese concentrations in Cub Creek and in groundwater at the facility, therefore, the Section will
not require continued iron and manganese analysis.

Based upon the information provided within Republic’s Alternate Source Demonstration, the Section is
requiring additional information to be submitted in a phased approach within an Alternate Source
Demonstration Addendum. Within 120 days of receipt of this letter, please submit an Alternate Source
Demonstration Addendum that meets the criteria described in the NC Solid Waste Section guidance
document titled NC Solid Waste Section Guidance for Alternative Source Demonstration Submittals for
Solid Waste Management Facilities - 2017.

Republic is required to address the following in the Alternate Source Demonstration Addendum:
• Review previous turbidity values for groundwater monitoring results used to calculate the
statistical background value for cobalt. Analytical data from turbid samples should not be used
to calculate background levels, since statistical background levels derived from turbid samples
may not accurately reflect background conditions. Statistical background levels should be
calculated using monitoring data from a minimum of ten groundwater samples where the
turbidity values are less than 10 Nephelometric Turbidity Units (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, Republic should establish a temporary groundwater monitoring
schedule to collect the required number of non-turbid samples from the background well within
a two-year period. Turbidity values should be recorded and submitted to the Section during the
temporary monitoring period. The temporary groundwater monitoring schedule should be
included in the ASD addendum.
• If analytical data appears to be influenced by turbidity, determine if intrawell analysis can
sufficiently account for geologic variation or if an additional background well is needed.
• If the statistical background value is re-calculated and outliers are detected, the values should be
reviewed to determine if they should be removed from the data set or are representative of
background and should be retained for statistical analysis. Technical reasons should be provided
explaining why a statistical outlier should be included or excluded from the groundwater
background data sets.
• If Republic chooses to utilize the Upper Tolerance Limits to establish new background levels for
cobalt, calculations should follow the distribution hierarchy preference.

Lastly, if Republic does not submit an Alternate Source Demonstration Addendum, the facility will be
required to initiate Assessment Monitoring in accordance with 15A NCAC 13B .1634. 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

Ed Mussler, Permitting Branch Head
Drew Hammonds, Eastern District Supervisor
Mary Whaley, Environmental Senior Specialist
Shannon Aufman, Permitting Engineer
Christine Ritter, Permitting Hydrogeologist
Van Burbach, Joyce Engineering