1304_Cabarrus_CharlotteMotorSpeedwayV_MSWLF_SoilGasExtractionAssessment_FID1811983_20230725

Environmental Consultants & Contractors
July 25, 2023
File No. 02222314.16
Jackie Drummond
North Carolina Department of Environmental Quality
Division of Solid Waste, Asheville Regional Office
2090 U.S. Highway 70
Swannanoa, North Carolina 28778
Subject: Soil Gas Extraction Probes and Assessment Update
Charlotte Motor Speedway Landfill V
SW Permit No. 1304-MSWLF-1992
Dear Ms. Drummond:
On behalf of the BFI Waste Systems of North America, Inc. and the Charlotte Motor Speedway
Landfill V, SCS Engineers, PC presents an update on the status on the installed soil gas extraction
system and migration assessment efforts at the Landfill near groundwater monitoring wells MW-17,
MW-17A, MW32A, MW-33, and MW-34. The soil gas extraction system and migration assessment
activities were documented in a March 11, 2019 report titled "Soil Gas Extraction Wells and
Migration Assessment Report" [FID 1294929], prepared by SCS Engineers, PC.
BACKGROUND
Concentrations of volatile organic compounds (VOCs) have been detected in groundwater wells
located west of Landfill phases 2E through 2H. The groundwater wells in this area (referred to herein
as the Area of Concern "AOC") are illustrated on Figure 1, in Attachment A. A proposition that a
contributing source for the VOCs may be landfill gas (LFG) in the subsurface.
In June of 2018, four soil gas probes were installed outside the waste disposal area in the southwest
corner of the Landfill property. The four soil probes were drilled and constructed to assess the
presence of subsurface LFG. Locations for the probes is depicted on Figure 1, in Attachment A. To
enhance the assessment, in October 2018, vacuum was applied to the four probes by connection to
the active landfill gas collection and control system (GCCS). This was done in an effort to extract LFG
from the subsurface.
2023 ASSESSMENT ACTIVITIES
Our assessment activities focused on the following:
• Review of historical and current soil gas probe data.
• Review of existing GCCS landfill gas extraction wells monitoring data near the AOC.
• Review of groundwater analytical data for MW-17, MW-17A, MW32A, MW-33, and MW-
34.
2520 Whitehall Park Drive, Suite 450, Charlotte, NC 28273 1 704-504-3107 0

Jackie Drummond
July 25, 2023
Page 2
• Provide recommendations for further actions.
Existing Soil Gas Probes
The four soil gas extraction probes, designated as GP-01, GP-02, GP-03, and GP-04, were connected
to the active GCCS in October of 2018. The soil gas probes were monitored for methane, oxygen,
carbon dioxide, and static pressure by the Landfill's operation and maintenance (0&M) contractor.
For construction of Landfill Phase IV, GP-03 was removed in 2022. GP-04 is damaged and currently
not connected to the GCCS.
We reviewed available soil gas probe monitoring data provided by the Landfill's 0&M contractor to
assess the status of subsurface LFG in the AOC. We also monitored GP-01, GP-02, and GP-04 using
a GEM5000 on July 17, 2023. The soil gas probes monitoring methane gas concentrations recorded
since 2018 are graphically presented as Exhibit 1.
Based on our review, we offer the following observations:
• Methane gas concentrations were highest in 2018 and early 2019.
• Methane gas concentrations declined later in 2019 and in 2020.
• Methane concentration in GP-01 have been below 5 percent by volume since mid-2021.
• Methane gas is still detected in low levels in GP-02 and GP-04 based on our July 2023
monitoring event.

Jackie Drummond
July 25, 2023
Page 3
Exhibit 1. Gas Probe Methane Concentrations
Probe Monitoring Data - Active
tGP-01 tGP-02 -0--GP-03 tGP-04
55
50
45
40
35
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U 25
20
15
10
5
0
00 Ol 01 Q1 Ol O O O O c-I c-I ri a --I N N N N rn n9
C-I c-I C-I N C-I N N N N N N N N N N N N N N
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \
1--I N L!1 00 rl N lf1 00 r-I N V1 00 rl N lf1 00 rl N L
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Date
Existing Landfill Gas Extraction Wells
The GCCS infrastructure adjacent to the AOC used for LFG extraction from the Landfill includes
vertical extraction wells, leachate cleanout pipes, and horizontal collectors (HC). These components
were designed, installed, and operated in accordance with solid waste and air regulations. We
tabulated and reviewed the wellhead data for ten (10) vertical extraction wells, one leachate
cleanout, and three HC located near the AOC. We also reviewed recent liquid level data for each of
the ten wells. The data was reviewed to establish it the GCCS components are operating efficiently.
A Site Plan depicting the GCCS components assessed is provided in Attachment A.

Jackie Drummond
July 25, 2023
Page 4
Based on our review, we offer the following observations:
• EW-150 was redrilled in June 2023. It is designated as EW-150A.
• EW-540 was redrilled in April 2022. It is designated as EW-540A.
• The applied vacuum to HC-17, HC-18, and HC-19 is widely variable. We recommend a
more steady-state vacuum be applied in the minus 10 to minus 20-inch range.
• EW-153 is pinched thereby reducing its effectiveness.
• The liquid levels in EW-152 and EW-159A are high thereby reducing the effectiveness of
the wells.
Groundwater Monitoring Data Review
We reviewed the "Groundwater Statistical Analysis Report, Second Semi -Annual 2022" for the CMS
Landfill, prepared by Jett Environmental Consultants, dated February 2023. Copies of the Time
Series groundwater monitoring graphs for Benzene; 1,2 Dichloroethane; and Vinyl Chloride in MW-
32A, MW-33, and MW-34 are provided in Attachment B.
Based on our review of the Time Series graphs, we offer the following observations:
• Benzene concentrations were stable until 2013 for MW-34, 2015 for MW-32R; 2017 for
MW-33; and 2019 for MW-31.
• Vinyl chloride concentrations were stable until 2014 for MW-34, 2015 for MW-32R; and
2016 for MW-33. Vinyl Chloride concentrations remain stable for MW-31 through 2022.
• 1,2 DCA concentrations were stable until 2017 for MW-34 and 2021 for MW-33. 1,2
DCA concentrations remain stable for MW-31 and MW-32R through 2022.
Recommendations
We offer the following recommendations to enhance the monitoring and removal of LFG from the
subsurface:
1. Install one new soil gas probe and connect it to the GCCS to replace GP-03.
2. Repair GP-04 and connect it to the GCCS.
3. Continue extracting soil gas from the four probes and monitor on a monthly basis.
4. To increase the extraction of LFG from the Landfill near the AOC:
a. Install de -watering pumps in vertical extraction wells EW-152 and EW-159A.
b. Operate the HCs more consistently with a target vacuum in the minus 10 to minus
20" we range.

Jackie Drummond
July 25, 2023
Page 5
c. Re -drill EW-153 during the next GCCS construction project.
5. Prepare and submit an assessment update in 12 months.
CLOSING
If you have any questions, or require any additional information, please contact Mike Gurley at 704-
400-6557, or Steve Lamb at 704-576-4731.
Sincerely,
AZJA'4"'�-
Albert D. Glenn, PE
Project Director
SCS Engineers, PC
SCL/adg
Enclosures
Steven C. Lamb, PE
Project Director/Vice President
SCS Engineers, PC
cc: Mike Gurley, Environmental Manager, CMS Landfill
M:\PROJECT FILES\02222314.16\Deliverables\CMS Migration Assessment Update_final_7-25-23.docx

Soil Gas Extraction Wells and
Migration Assessment Update
Charlotte Motor Speedway Landfill V
Attachment A
Figure 1
www.scsengineers.com
Attachment A

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Attachment B
Time Series Groundwater Monitoring Graphs
Soil Gas Extraction Wells and
Migration Assessment Update
Charlotte Motor Speedway Landfill V
www.scsengineers.com
Attachment B

Sanitas" v.9.6.36 Software licensed to Jett Environmental Consulting. UG
Hollow symbols indicate censored values.
5
4
3
J
7
2
1 ;
0--
6/11 /07
Time Series
7/8/10 8/4/13 9/1/16 9/29/19 10/27/22
0 MW-31
♦ MW-33
♦ MW-34
■ MW-32R
Constituent: 12-Dichloroethane Analysis Run 12/22/2022 8:33 AM View: TS Org Detects Tbl 2
Charlotte Motor Speedway Client: RSI Data: CMS

Sanitas" v.9.6.36 Software licensed to Jett Environmental Consulting. UG
Hollow symbols indicate censored values.
10
8
6
J
7
4
2
0 4-
6/11 /07
Time Series
7/8/10 8/4/13 9/1/16 9/29/19 10/27/22
MW-31
♦ MW-33
♦ MW-34
■ MW-32R
Constituent: Benzene Analysis Run 12/22/2022 8:33 AM View: TS Org Detects Tbl 2
Charlotte Motor Speedway Client: RSI Data: CMS

Sanitas" v.9.6.36 Software licensed to Jett Environmental Consulting. UG
Hollow symbols indicate censored values.
20
16
12
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8
4
0 L!
6/11 /07
Time Series
7/8/10 8/4/13 9/1/16 9/29/19 10/27/22
MW-31
® MW-33
♦ MW-34
■ MW-32R
Constituent: cis-12-Dichloroethylene Analysis Run 12/22/2022 8:33 AM View: TS Org Detects Tbl 2
Charlotte Motor Speedway Client: RSI Data: CMS

Sanitas" v.9.6.36 Software licensed to Jett Environmental Consulting. UG
Hollow symbols indicate censored values.
7
5.6
4.2
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6/11 /07
Time Series
7/8/10 8/4/13 9/1/16 9/29/19 10/27/22
MW-31
® MW-33
♦ MW-34
■ MW-32R
Constituent: Vinyl chloride Analysis Run 12/22/2022 8:33 AM View: TS Org Detects Tbl 2
Charlotte Motor Speedway Client: RSI Data: CMS