6013_GreenwayNorthMeckCDLF_20171219_MetalsASDResponse_DIN28700

December 19, 2017

Sent Via Email – [e-mail]
Mr. Mike Griffin
Greenway Waste Solutions at North Meck, LLC
19109 West Catawba Avenue, Suite 200
Cornelius, NC 28031

Re: Demonstration Letter on Background Metals in Groundwater Samples
North Mecklenburg C&D Landfill Infill Area and Closed Phase I Area
Mecklenburg County
Solid Waste Permit Number 6013
DIN 28700

Dear Mr. Griffin:

The Solid Waste Section (Section) has completed a review of the Demonstration Letter on Background
Metals in Groundwater Samples dated August 2, 2017 (DIN 28645) and submitted on your behalf by CEC
Consultants, Inc. for the North Mecklenburg C&D Landfill (Infill Area and the Closed Phase I Area), NC Solid
Waste Permit Number 6013.

Since 2013 in response to the consistent groundwater exceedances of volatile organic compounds, the
Infill area of the landfill has been in the Assessment Monitoring program in accordance with 15A NCAC
13B .0545 and 15A NCAC 2L, and the closed Phase I area of the landfill has been conducting an assessment
in accordance with 15A NCAC 15A NCAC 13B .0503 and the 15A NCAC 2L.

The Demonstration Letter on Background Metals in Groundwater Samples was submitted in accordance
with 15A NCAC 13B .0545(b)(8) to address groundwater exceedances of the metals chromium, cobalt,
iron, manganese, thallium, and vanadium above the Interim Maximum Allowable Concentration (IMAC)
and 2L Standards established in 15A NCAC 02L .0202. These six metals were chosen to be part of this
demonstration because they have been detected in the perimeter groundwater monitoring wells at the
landfill. The other groundwater monitoring wells located at the landfill were not addressed in this
demonstration.

The Demonstration Letter on Background Metals in Groundwater Samples included a geological review
utilizing the USGS NURE Database, a 1984 USGS Open File Report, and site-specific oxidation-reduction
potential (ORP) measurements. Statistical analyses utilizing the geometric mean was also included.

Based on the information provided in the Demonstration Letter on Background Metals in Groundwater
Samples, the Section is requiring additional information to be submitted in an Alternate Source
Demonstration Addendum. Within 120 days of receipt of this letter, submit an Alternate Source
Demonstration Addendum that meets the criteria described in the Section guidance document titled NC

Solid Waste Section Guidance for Alternative Source Demonstration Submittals for Solid Waste
Management Facilities - 2017.

Greenway Waste Solutions at North Meck, LLC is required to address the following in the Alternate Source
Demonstration Addendum:
• A further clarification of the statistical methods used.
• Determine if a new or additional background monitoring well(s) should be installed at the landfill.
• 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.
• Provide baseline sampling data available prior to the beginning of waste operations for the Infill
Area of the landfill.
• Determine if seasonality plays a role.
• Provide total and dissolved metals groundwater sampling analyses.
• Review and provide turbidity data and/or measurements 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 Greenway Waste
Solutions at North Meck, LLC must establish a temporary groundwater monitoring
schedule to collect the required number of non-turbid samples from the background well
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.

Upon submittal of the requested information, the Section will evaluate the Alternate Source
Demonstration Addendum and provide a determination on Greenway Waste Solutions at North Meck,
LLC’s conclusion that the metals in the demonstration are due to their presence in the natural geology,
and that they should be removed from the contaminants of concern for the landfill at this time.

Be advised that additional information or analyses may be requested to fully evaluate and support the
demonstration to establish the landfill has not contributed to the groundwater exceedances of the metals.
Please note that if Greenway Waste Solutions at North Meck, LLC decides not to submit an ASD Addendum
within 120 days, additional assessment for the metals will be required in addition to groundwater
corrective action for the metals.

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

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

cc sent via email: Ellen Lorscheider, Division Deputy Director
Jason Watkins, Field Operations Branch Head
Deb Aja, Western District Supervisor
Teresa Bradford, Environmental Senior Specialist
Ed Mussler, Permitting Branch Head
Perry Sugg, Permitting Hydrogeologist
Larry Frost, Permitting Engineer
John Brown, Griffin Brothers
Ed Stephens, CEC, Inc.
Scott Brown, CEC, Inc.
Joe Hack, Mecklenburg County Solid Waste Management
Aaron Caudle, Mecklenburg County Solid Waste Management
Jack Simoneau, Town of Huntersville