7401_PittCounty_MSWLF_PilotStudy_FID1914358_20241118

Groundwater Management Associates, Inc.
GMA 4300 Sapphire Court, Suite 100
Greenville, North Carolina 27834
-- - - Telephone: [phone]
- www.qma-nc.com
November 18, 2024
Sent Via Email - iaclvnne.drummond(a)ncdenr.aov
Ms. Jaclynne Drummond
Hydrogeologist
NCDEQ, DWM, Solid Waste Section
2090 US Highway 70
Swannanoa, North Carolina 28778
Re: Pilot Study Update and Request for an Extension of the Pilot Study at the Pitt County Solid
Waste Municipal Landfill (Permit Numbers 7401-MSWLF- and 7401-MSWLF-1974)
Dear Ms. Drummond,
In June 2021, Pitt County completed a $1.065 million cap improvement project at the Southern
Unit of the Pitt County Landfill. These upgrades were part of an approved pilot study for
corrective action following detections of 1,4-dioxane above the 15A NCAC 02L groundwater
standard. Following completion of the construction project, the County repeated geophysical
testing of the Southern Unit to help document the extensive repairs and to evaluate hydrologic
improvements. A comparison of the pre -repair and post -repair geophysical surveys showed the
areas where cap thickness was increased and where extensive surface regrading was necessary
to ensure proper functioning of the stormwater drainage system.
GMA anticipates that the completed cap improvements will reduce infiltration of water through
the cap and better protect the groundwater from further contamination via leaching from
landfill waste at the Southern Unit. However, due to slow groundwater velocity at the site only
minor hydraulic improvements and/or reductions in contaminant levels have been observed to
date. Continued monitoring of groundwater levels and contaminant concentrations are needed
to better assess the effectiveness of the cap and stormwater system upgrades. Additionally,
groundwater flow patterns at the landfill vary seasonally, and an extended assessment will
allow the County to better evaluate how the improvements affect the large seasonal shift in
groundwater flow patterns. The assessment of these upgrades will be compiled into a
Corrective Action Evaluation Report at the end of the Pilot Study.
PFAS testing has commenced for North Carolina landfills, and continued sampling will help to
develop baselines for those constituents as part of the ongoing monitoring of the site. Expected
additional requirements over the next year for PFAS monitoring, such as a receptor survey and
development of a PFAS Study Plan, are expected to be announced by the end of the year
(2024) and will eventually lead to a corrective action plan and remediation. GMA believes
combining the results of the Pilot Study and initial results from the soon to be implemented

Ms. Jaclynne Drummond
NC Solid Waste Section
November 12, 2024 Page 2 of 2
PFAS study plan is the most comprehensive way to approach corrective action at the Pitt County
Landfill.
GMA requests that the North Carolina Solid Waste Section extend the pilot study until July 2025
to allow time for a comprehensive assessment of the Pilot Study program to be made in
conjunction with initial results from a forthcoming PFAS Study Plan. This approach will address
future corrective action and potential remediation for VOCs, 1,4-Dioxane, and PFAS
simultaneously. Pitt County understands this will be the last extension of the Pilot Study if
approved by NCDEQ.
The County continues to monitor groundwater and surface water at the Southern Unit on a
semi-annual schedule. The next semi-annual monitoring event at the Pitt County Solid Waste
Municipal Landfill is scheduled for January of 2025 and will include only Appendix I of 40 CFR
Part 258 parameters, 1,4-dioxane, and PFAS parameters. We provide full details regarding the
status of the pilot study, and the most recent monitoring event at the Southern Landfill Unit in
the report that accompanies this letter.
Please contact me if you have any questions or concerns, and thank you for your consideration
in this matter.
Sincerely,
Groundwater Management Associates, Inc.
Cody J. Shell, P.G.
Project Hydrogeologist
cc: Richard K. Spruill, Ph.D., PG (GMA)
Tim Corley, P.E. (Pitt County)
John Demary (Pitt County)
Z:\GMA\251XX-Pitt County\25101 - Landfill\2024 July\Letter Pitt Co Landfill Pilot Study Request Extension 2024.docx