4903_IredellCoMSWLF_July2024LFGExccedanceProgressReport_FID1894480_20240829

CEC
Carlson Environmental Consultants, pc
Landfill Gas and Solid Waste Specialists

1127 Curtis Street Ste 100 Monroe NC 28112 Phone [phone] ·Fax [phone]
Orlando, FL · Tampa, FL · Atlanta, GA · Columbia, SC · Richmond, VA · Statesville, NC
Olympia, WA · Cookeville, TN · Tullytown, PA
www.cecenv.com

August 19, 2024

Ervin Lane
Solid Waste Section
NCDEQ - Division of Waste Management
Raleigh Regional Office 1646 Mail Service Center
Raleigh, NC 27699-1646

Subject: Q1 2024 Methane Migration Monitoring Exceedances – Remediation Plan
Monthly Progress Update – July 2024
Iredell County Subtitle D Lined Landfills/Closed Unlined C&D Landfill
Statesville, North Carolina
Solid Waste Permit No. 49-03
Dear Ervin:
On behalf of Iredell County (County), Carlson Environmental Consultants, PC (CEC) is submitting
to the North Carolina Department of Environmental Quality (NCDEQ) Division of Waste
Management Solid Waste Section (SWS) the subject remediation plan progress updates for a
recent methane migration monitoring exceedance detected at the Subtitle D Lined
Landfills/Closed Unlined C&D Landfill facility that is owned and operated by the County.
As previously reported to NCDEQ in a notification letter dated March 18, 2024 and the subsequent
remediation plan dated May 14, 2024, there was one (1) perimeter gas probe location with
methane detections above the 5% lower explosive limit (LEL) during the first quarter 2024
monitoring event: MP-6A (53.1%).
Pursuant to NCAC 13B .1626(4)(c)(iii), the County has commenced implementation of the
remediation plan for explosive gas release at this location. In accordance with NCAC 13B
.1626(4)(c)(iii), the plan describes the nature and extent of the exceedance and proposed remedies. The below remediation plan progress updates are being provided to NCDEQ for the
month of July 2024:
• MP-6A was monitored weekly in July. Although monitored methane concentrations
significantly declined as of May 16, 2024, MP-6A was again monitored to be above the
5% LEL as of May 28, 2024. MP-6A was then monitored below the 5% LEL on June 20,
2024 and remained below 5% in July. As stated in the remediation plan submitted to
NCDEQ MP-6A must remain below the 5% LEL for a consecutive two (2) months.
• As noted above, monitored methane concentrations at MP-6A remained under 1% in July.
This is directly correlated with increased applied vacuum to existing LFG collection system
extraction wells and devices nearest the probe location. The County will continue to
incrementally increase vacuum to the area in August.
• Barhole punch and sampling occurred at four (4) locations between MP-6A and the
northwestern landfill perimeter on May 23, June 18, and July 17, 2024. Methane was not
detected above 5% at any barhole punch location. Monthly barhole punch and sampling
at these locations will continue in August.
Ervin Lane
August 19, 2024
Page 2
• Weekly monitoring at the ICATS office structure was completed in July, and methane was
not detected above 1.25% during any monitoring period. Methane continues to be below
5% at MP-6A, weekly monitoring of the ICATS office structure will continue in through
August 2024.
• During the month of July, the County began the project of extending the toe drain located
along the Northwestern side of Phase 4. Upon completion, it will be connected to the
active LFG collection system.
• Flare upgrades in order to assist with stabilizing system vacuum throughout the wellfield are temporarily delayed due to a parts delay.
If you have any questions regarding this remediation plan, or require additional information,
please contact the undersigned at [phone].
Sincerely,

Kathryn Fauerby
Carlson Environmental Consultants, PC
CC: Teddy Boller, Iredell County
Jeff Webster, Iredell County
Brock McNabb, PE, CEC Amanda Higgs, CEC

EXHIBIT A

Methane Monitoring Data Summary

(March 2024 – July 2024)
Permit ID Device ID Date and
Time of Day
Initial
% LEL
Stabilized
% LEL
% CH4
(volume)
% O2
(volume)
% CO2
(volume)
MP-6A IRDLMP6A 3/15/2024 13:32 >100 >100 53.10 0.00 38.10
MP-6A IRDLMP6A 3/22/2024 10:13 >100 >100 52.10 1.80 34.80
MP-6A IRDLMP6A 3/28/2024 10:54 >100 >100 57.60 0.00 38.30
MP-6A IRDLMP6A 4/5/2024 07:56 >100 >100 46.40 1.60 34.50
MP-6A IRDLMP6A 4/11/2024 14:12 >100 >100 61.80 0.10 37.80
MP-6A IRDLMP6A 4/18/2024 10:31 >100 >100 57.80 0.60 38.80
MP-6A IRDLMP6A 4/25/2024 09:59 >100 >100 43.70 1.90 36.10
MP-6A IRDLMP6A 5/2/2024 09:13 >100 >100 30.00 2.70 33.20
MP-6A IRDLMP6A 5/8/2024 13:18 >100 >100 8.00 10.40 16.40
MP-6A IRDLMP6A 5/16/2024 08:12 48.00 48.00 2.40 15.40 8.20
MP-6A IRDLMP6A 5/24/2024 07:53 14.00 14.00 0.70 15.60 6.40
MP-6A IRDLMP6A 5/28/2024 13:15 >100 >100 8.70 6.50 20.80
MP-6A IRDLMP6A 6/7/2024 12:43 >100 >100 25.00 2.80 31.10
MP-6A IRDLMP6A 6/11/2024 12:12 >100 >100 25.50 1.10 34.50
MP-6A IRDLMP6A 6/20/2024 09:56 30.00 30.00 1.50 5.30 22.60
MP-6A IRDLMP6A 6/25/2024 08:03 0.00 0.00 0.00 8.30 17.10
MP-6A IRDLMP6A 7/3/2024 13:02 2.00 2.00 0.10 15.80 10.30
MP-6A IRDLMP6A 7/11/2024 13:27 0.00 0.00 0.00 15.80 9.90
MP-6A IRDLMP6A 7/19/2024 15:14 0.00 0.00 0.00 19.70 3.80
MP-6A IRDLMP6A 7/25/2024 15:07 0.00 0.00 0.00 21.20 2.30
MP-6A IRDLMP6A 7/29/2024 14:15 0.00 0.00 0.00 20.60 1.70
GEM 5000 gas analyzers were used for all monitoring events and were calibrated appropriately prior to monitoring.
Methane Monitoring Data Summary
March 2024 - July 2024
Iredell County Subtitle D Lined Landfills/Closed Unlined C&D Landfill (Permit No. 49-03)