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Landfill Gas Monitoring Plan December 20, 2017
Buncombe County Landfill -- Alexander, North Carolina BLE Project Number J17-9378-11
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TABLE OF CONTENTS
PAGE
1.0 INTRODUCTION ................................................................................................. 1
2.0 GEOLOGIC CONDITIONS .................................................................................... 2
3.0 LANDFILL GAS MONITORING PLAN ............................................................... 3
3.1 Monitoring Network Design and Phasing of Installation ............................ 3
3.2 Monitoring Well Design and Construction ................................................... 4
3.3 Monitoring Schedule ....................................................................................... 5
3.4 Quality Assurance and Quality Control Procedures ................................... 5
3.5 Monitoring Procedures for Structures .......................................................... 5
3.6 Monitoring Procedures for Wells ................................................................... 6
3.7 Landfill Gas Safety Guidelines ....................................................................... 6
3.8 Reporting ................................................................................................. 7
3.8.1 Landfill Gas Monitoring Well Installation Reports ........................ 7
3.8.2 Evaluation and Reporting of Landfill Gas Monitoring Results ..... 7
4.0 REFERENCES ................................................................................................. 9
TABLES
Table 1 Landfill Gas Monitoring Well and Point Data
FIGURES
Figure 1 Site Location Map
Figure 2 Water Quality and Landfill Gas Environmental Monitoring Systems
Figure 3 Landfill Gas Monitoring Well Detail
APPENDICES
Appendix A Landfill Gas Monitoring Guidance (November 2010)
Appendix B Well Construction Records
Appendix C Environmental Monitoring Reporting Form
Landfill Gas Monitoring Plan December 20, 2017 Buncombe County Landfill -- Alexander, North Carolina BLE Project Number J17-9378-11
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1.0 INTRODUCTION
The subject 654-acre landfill site is located in Buncombe County, North Carolina, approximately
nine miles north of the city of Asheville with a physical address of 81 Panther Branch Road in Alexander, North Carolina (Figure 1). Buncombe County owns and operates a Subtitle D MSWLF
which includes Cell 1 through Cell 6 and a CDLF consisting of Phase 1 through Phase 5. Currently
Cell 6 of the MSWLF and Phase 5 of the CDLF are the active waste units. MSWLF Cell 7 has been permitted for construction and MSWLF Cells 8 through 10 are planned (but not permitted) for future
expansion.
The county intends to expand the existing CDLF facility by constructing the next planned expansion
area designated Phase 6 which is approximately 11.9 acres and is located west of CDLF Phase 5. McGill Associates, PA (McGill) has been retained by the EIC to prepare an application for a permit to construct for Phase 6. BLE has been retained by EIC to conduct a design hydrogeologic investigation
required under North Carolina’s Solid Waste Management Rules, Title 15A Section 13B .0538(b)(1-2) for a Design Hydrogeologic Report (DHR). That work is reported under separate cover.
The facility includes a network of landfill gas compliance monitoring wells and structures which are monitored quarterly in accordance with the facility permit. EIC has requested that BLE prepare a comprehensive LFGMP for submittal to the North Carolina Division of Waste Management, Solid
Waste Section (SWS), which consolidates the monitoring plans for the operational and permitted expansion areas of the MSWLF with the operational and expansion areas of the CDLF. We
understand that this LFGMP will be included as part of the application for a permit to construct
CDLF Phase 6 which will be prepared by McGill.
The objective of this project is to prepare a LFGMP which will include procedures and locations for
landfill gas monitoring as required by the following North Carolina Department of Environmental Quality (DEQ) Solid Waste Management Rules (Rules) for gas control:
• Title 15A NCAC 13B .1626(4) for the Municipal Solid Waste Landfills (MSWLF)
• Title 15A NCAC 13B .0544(d) for the Construction and Demolition Landfills (CDLF)
The landfill gas monitoring network for this site will be designed to provide monitoring of landfill gas
concentrations at the facility boundaries and within facility structures. The locations of the landfill gas monitoring points are indicated on the attached Figure 2 titled Water Quality and Landfill Gas
Environmental Monitoring Systems.
Landfill Gas Monitoring Plan December 20, 2017 Buncombe County Landfill -- Alexander, North Carolina BLE Project Number J17-9378-11
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2.0 GEOLOGIC CONDITIONS
The subject site is located within the Blue Ridge geologic belt. The geology of the Blue Ridge Belt
consists of metamorphic Precambrian basement rock overlain with unconformable younger Precambrian metamorphosed sedimentary and igneous rocks. The Blue Ridge belt is bordered to the
southeast by the Brevard belt and to the northwest by the Valley and Ridge. The Precambrian
basement has undergone several episodes of uplift, deformation, faulting, intrusion, metamorphism, and erosion. Locally, the site is geologically underlain by Middle Proterozoic biotite granitic gneiss
and migmatitic biotite hornblende gneiss interlayered with amphibolite and calc-silicate rocks
(Rhodes and Conrad, 1985; CDM, 2009).
The typical residual soil profile consists of clayey and silty soils near the surface, where soil weathering is more advanced, underlain by micaceous sandy silts and silty sands. Residual soil zones develop by the in situ chemical weathering of bedrock, and are commonly referred to as “saprolite.”
Saprolite usually consists of micaceous sand with large rock fragments and lesser amounts of clay and silt. The boundary between soil and rock is not sharply defined.
A transitional zone of partially weathered rock (PWR) is normally found overlying the parent bedrock. Partially weathered rock is defined, for engineering purposes, as residual material with standard penetration resistance (ASTM D 1586) in excess of 100 blows per foot (bpf). Fractures,
joints, and the presence of less resistant rock types facilitate weathering. Consequently, the profile of the partially weathered rock and hard rock is quite irregular and erratic, even over short horizontal
distances. Also, it is not unusual to find lenses and boulders of hard rock and zones of partially
weathered rock within the soil mantle, well above the general bedrock level.
Landfill Gas Monitoring Plan December 20, 2017 Buncombe County Landfill -- Alexander, North Carolina BLE Project Number J17-9378-11
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3.0 LANDFILL GAS MONITORING PLAN
The objective of the Landfill Gas Monitoring Plan (LFGMP) is to detect the lateral movement of potentially explosive gases in the subsoil and along man-made migration pathways toward on-site and off-site structures in accordance with Title 15A NCAC 13B .1626(4), Title 15A NCAC 13B
.0544(d), and in general accordance with the SWS’s Landfill Gas Monitoring Guidance, dated November 2010 (Appendix A). The information gathered from landfill gas monitoring stations will be used to evaluate the potential explosive hazard of methane gas accumulations within the explosive
limits of 5 - 15 percent by volume.
3.1 Monitoring Network Design and Phasing of Installation
Landfill gas monitoring points have been (or will be) established on-site between the landfill disposal
areas and the facility boundary and have been (or will be) established in on-site structures.
The following criteria were used in selecting locations for landfill gas monitoring:
• On-site structures such as office/maintenance building and the scale house will be monitored;
• Buried utilities at the site are (or will be) constructed with compacted soil backfill rather than gravel backfill, and will not require monitoring.
• Vertical migration of landfill gas is limited to the depth of groundwater; therefore, perennial streams (where groundwater meets the ground surface) will serve as natural lateral barriers for landfill gas migration in the subsurface. Therefore, locations along the site’s property
boundary where there is not a perennial stream between the waste disposal areas and the
property boundary will be monitored.
The landfill gas monitoring network for the Buncombe County Landfill is summarized on Table 1. The existing network consists of four (4) compliance monitoring wells (M-1 through M-4) in use for
the MSWLF and two (2) compliance monitoring wells (M-10 and M-11) in use for the CDLF. A construction diagram for existing landfill gas monitoring wells (M-3, M-4, M10, and M-11) are
included in Appendix B. The network includes permitted locations for five (5) future compliance
monitoring wells (M-5 through M-9) for planned expansion of the MSWLF (Cells 7 through 10) [Figure 2]. Those five (5) landfill gas monitoring wells have not been installed.
There are nine (9) existing structures which are currently monitored for landfill gas. They include the Scale House, the Landfill Office Building, the Convenience Center, the Well House, Block
Building, HHW Building, the Radio Tower, the Garage, and the Employee Trailer. (Figure 2). No structures are planned to be added to the facility as part of the Phase 6 CDLF expansion.
One (1) compliance well (M-12) is proposed for the Phase 6 CDLF expansion (Table 1 and Figure
2).
The locations of the six (6) existing landfill gas compliance monitoring wells, five (5) permitted future landfill gas compliance monitoring well locations, one (1) proposed landfill gas compliance monitoring well, and nine (9) existing structures are indicated on attached Figure 2 titled Water Quality and Landfill Gas Environmental Monitoring Systems.
Landfill Gas Monitoring Plan December 20, 2017 Buncombe County Landfill -- Alexander, North Carolina BLE Project Number J17-9378-11
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3.2 Monitoring Well Design and Construction
The landfill gas monitoring wells will be constructed in accordance with North Carolina Well Construction Standards 15A NCAC Subchapter 2C, Section .0100.
The top of the screened section of each well will begin at approximately 5 feet below ground surface. The bottom of the screened section of each well will be controlled by the following site-specific field conditions at the time of installation:
• The depth to 5 feet above the stabilized groundwater level; or
• The depth to bedrock (auger refusal), whichever is shallower.
It should be noted in cases where a shallow groundwater or bedrock conditions exists, it will be
necessary to install landfill gas monitoring wells with shortened screen intervals with screen top less than 5 feet from ground surface and screen bottom less than 5 feet from stabilized groundwater level
or bedrock. We estimate that proposed landfill gas monitoring well M-12 will be approximately 6
feet deep with the top of screen 4 feet from ground surface and bottom of screen 4 feet from stabilized groundwater. A 2-foot long screen length will be necessary in proposed landfill gas monitoring well
M-12. Actual well construction will be controlled by the subsurface conditions encountered at the time of installation.
In general, landfill gas monitoring wells will consist of 2-inch diameter PVC (Schedule 40 ASTM 480, NSF-rated) casing with flush-threaded joints inserted into a 5.0-inch diameter (or larger)
borehole. The bottom section of each well will consist of manufactured well screen with 0.010-inch
wide slots. In the well, silica filter sand backfill will be placed around the outside of the pipe to 0.5 feet above the top of the well screen. A 2.5-foot thick hydrated bentonite seal will then be placed on
top of the sand backfill to seal the monitoring well at the desired level. The remaining 2.0-foot well
annulus will then be grouted to the surface with a cement/bentonite grout mixture.
The surface completion of each well will consist of a valve placed on top of the pipe casing (so that undiluted samples are collected), and a lockable 4" x 4" x 5' standup protective steel cover, with a 2-foot by 2-foot square concrete pad at the base of the steel cover. Each well will be constructed with
a weep hole near the base of the outer protective steel cover. An identification plate will be fastened
to the protective steel cover that specifies the well identification number, drilling contractor, date installed, total depth, and construction details. A typical landfill gas monitoring well construction
detail is attached as Figure 3. A geologist or engineer will oversee drilling activities and prepare boring and well construction logs
for each newly installed well. As-built locations of new wells will be located by a surveyor licensed in North Carolina to within +0.1 foot on the horizontal plane and +0.01 foot vertically in reference to existing survey points. A boring log, well construction log, a monitoring well network map, and
well installation certification will be submitted to the SWS upon completion.
Landfill Gas Monitoring Plan December 20, 2017 Buncombe County Landfill -- Alexander, North Carolina BLE Project Number J17-9378-11
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3.3 Monitoring Schedule
For the purpose of detecting migration of potentially explosive gas from the landfill, the following monitoring schedule was implemented:
1. Upon commencement of active operations and quarterly prior-to-closure. 2. Quarterly for at least 30 years during the post-closure care period or until demonstration is
made to the SWS that methane gas no longer presents a threat to the environment. 3. Each monitoring event is to include observations for stressed vegetation due to landfill gas
movement. If present, areas around and beyond stressed vegetation will be monitored with a bar punch to determine if landfill gas is moving off site.
4. Monitoring in, beneath, and around site structures (as appropriate) will be a part of each monitoring event.
3.4 Quality Assurance and Quality Control Procedures
Landfill gas will be analyzed using a combustible gas indicator, such as a LANDTECH GEM 2000 Gas Meter (or equivalent). The combustible gas indicator will be calibrated according to the manufacture’s specifications prior to the landfill gas survey.
Air samples from the wells will be withdrawn and analyzed with the combustible gas indicator. The combustible gas indicator will provide direct readings of methane concentrations (0-100% methane
and 0-100% lower explosive limit [LEL]). Percent of methane and percent of LEL will be recorded, along with pertinent data such as ambient air temperatures, barometric pressure, subsurface pressure, weather conditions, and soil moisture conditions for a permanent record.
3.5 Monitoring Procedures for Structures
Each landfill gas survey will include screening at on-site structures. Recommended sampling locations within structures include: basements, crawl spaces, and ceiling areas. Each quarterly
monitoring event includes an internal sweep of structures with the designated gas meter collecting
continuous readings while moving through the entire structure and/or at accessible sampling locations. Readings of percent methane, percent LEL, percent oxygen, ambient air temperatures,
barometric pressure, and weather conditions will be recorded on the Landfill Gas Monitoring Data Form (Appendix A) or equivalent form prepared for the facility.
Landfill Gas Monitoring Plan December 20, 2017 Buncombe County Landfill -- Alexander, North Carolina BLE Project Number J17-9378-11
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3.6 Monitoring Procedures for Wells
The following procedures should be followed for landfill gas monitoring wells: 1. Remove the locking cap;
2. Connect the combustible gas meter tubing to the to the quick-connect valve located on the well head;
3. Purge the well for a minimum of 1 minute and until stabilized readings (percent methane by volume, percent LEL, percent oxygen) are observed;
4. Record the stabilized readings (percent methane by volume, percent LEL, percent oxygen) in a
field book or on a field form;
5. Disconnect the combustible gas meter from the well head;
6. Replace the locking cap;
7. Survey the area for stressed vegetation; and 8. Move to the next well.
Reading of percent methane, percent LEL, percent oxygen, percent carbon dioxide, undisturbed pressure/vacuum, ambient air temperatures, barometric pressure, and weather conditions will be
recorded on the Landfill Gas Monitoring Data Form (Appendix A) or equivalent form prepared for the facility. Readings of concentration of hydrogen sulfide will be recorded for landfill gas wells monitoring the CDLF waste unit.
3.7 Landfill Gas Safety Guidelines
The following guidelines should be followed when at a landfill in the presence of potentially dangerous gases:
1. No person should enter a vault or a trench on a landfill without first checking for the presence of methane gas. The person should also wear a safety harness with a second person standing by to
pull him or her to safety. 2. Anyone installing large diameter wells in the landfill waste should wear a safety rope to prevent
falling in the borehole. Open holes should be covered when they are left unattended.
Landfill Gas Monitoring Plan December 20, 2017 Buncombe County Landfill -- Alexander, North Carolina BLE Project Number J17-9378-11
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3. Smoking should be prohibited on the landfill where drilling, excavating, or installation of equipment is taking place or where methane gas is venting from the landfill.
4. Collected methane gas from a mechanically evacuated system should always be cleared to minimize air pollution and any potential explosion or fire hazard.
5. Methane gas in a concentration of 5 to 15 percent is an explosive mixture. Methane gas accumulations should be monitored inside enclosed structures to avoid explosive conditions and
properly ventilate dangerous areas when needed. Personnel working on a landfill must be provided training regarding the danger posed by landfill
gases. Personnel operating safety equipment around the landfill must be thoroughly trained in its use and have a clear understanding of the meaning of observations made with the monitoring
equipment. Monitoring equipment must also be periodically calibrated to ensure continued accuracy
in the results.
3.8 Reporting
3.8.1 Monitoring Well Installation Reports A landfill gas monitoring well installation report will be prepared upon completion of well
installation and prior to waste disposal into any newly constructed waste units. The well installation report will include documentation of boring logs, well diagrams, and field procedures. The landfill gas monitoring well installation report will be submitted in electronic format in accordance with
applicable guidance and if physical copies are required by the SWS they will be sent to the following mailing address:
North Carolina Department of Environmental Quality Division of Waste Management -- Solid Waste Section
1646 Mail Service Center
Raleigh, North Carolina 27699-1646
Additionally, copies of all installation reports will be kept at the landfill as part of the facility’s
operating record.
3.8.2 Evaluation and Reporting of Landfill Gas Monitoring Results Interpretation of quarterly sampling for landfill gas will be as follows:
1. Methane gas concentrations shall not exceed 25 percent of the lower explosive limit (LEL). (1.25%) for gases in facility structures.
2. Methane gas concentrations shall not exceed the lower explosive limit for methane facility boundaries (5%).
3. Hydrogen sulfide (H2S) gas concentrations shall not exceed 1% inside structures and 4% by volume at facility boundaries. Note that H2S monitoring is required for the CDLF only.
Landfill Gas Monitoring Plan December 20, 2017 Buncombe County Landfill -- Alexander, North Carolina BLE Project Number J17-9378-11
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If no landfill gas exceedances are recorded, then a copy of the monitoring results (Landfill Gas Monitoring Data Form, Appendix A, or equivalent form prepared for the facility) will be retained
by the landfill operator and the results will be filed in the facility’s operating record. Upon findings of landfill gas concentrations which exceed limits, the following will be implemented:
1. Verification of explosive gas and/or hydrogen sulfide concentrations by immediate retesting. 2. Upon verifications of readings of explosive gas above 25 percent of the LEL in facility structures
or above the LEL at the facility boundaries, or hydrogen sulfide exceeding 1% by volume in structures or 4% at the facility boundaries, immediate notifications to the SWS and appropriate local public safety authorities such as the local health district, fire department, and police
department will be given. Structures with verified exceedances should be vented in accordance with fire department directives and all occupants should be evacuated from the area immediately.
3. Within seven days of the detection, place in the operating record the landfill gas measurements and a description of the steps taken to protect human health.
4. Within 60 days of detection, implement a remediation plan for the landfill gas releases, place a copy of the plan in the operating record, and notify the SWS that the plan has been implemented.
The plan shall describe the nature and extent of the problem and the proposed remedy. 5. Based on the need for an extension demonstrated by the operator, the Division may establish
alternative schedules for demonstrating compliance with (4)(c)(ii) and (iii) of this Rule. 6. Results of landfill gas monitoring exceedances will include an Environmental Monitoring
Reporting Form (Appendix C) and Landfill Gas Monitoring Data Form (Appendix A) or equivalent form prepared for the facility. The reports will be kept at the landfill as part of the facility’s operating record and will be submitted electronically to the appropriate SWS
Hydrogeologist and if physical copies are requested, to the SWS at their current mailing address.
Copies of all monitoring reports will be kept at the landfill as part of the facility’s operating record.
Landfill Gas Monitoring Plan December 20, 2017 Buncombe County Landfill -- Alexander, North Carolina BLE Project Number J17-9378-11
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4.0 REFERENCES
Bunnell-Lammons Engineering, Inc., 2017. Design Hydrogeologic Report, Phase 6 C&D, Buncombe County Landfill.
Camp, Dresser, and McKee, Inc.; April 2009; C&D Landfill Expansion, Part 2: Site Hydrogeological Investigation, Buncombe County Solid Waste Facility.
Horton, J.W. and Zullo, V.A., 1991, The Geology of the Carolinas: Carolina Geological Society fifteenth anniversary volume: The University of Tennessee Press, Knoxville, TN.
North Carolina Dept. Environment and Natural Resources (NCDENR). 2010. N.C. Division of Waste Management, Solid Waste Section, Landfill Gas Monitoring Guidance Document.
North Carolina Dept. Environment and Natural Resources (NCDENR). 2014. Division of Waste Management, Solid Waste Section, Groundwater, Surface Water, Soil, Sediment, and Landfill Gas
Electronic Document Submittal.
Rhodes, Thomas S., and Conrad, Stephen G., 1985, Geologic Map of North Carolina: Department
of Natural Resources and Community Development, Division of Land Resources, and the NC Geological Survey, 1:500,000-scale, compiled by Brown, Philip M., et al, and Parker, John M. III, and in association with the State Geologic Map Advisory Committee.
TABLE
Table 1
Landfill Gas Monitoring Well and Point Data
Buncombe County Landfill
Permit No. 1107-CDLF-1998
Permit No. 1107-MSWLF-1996
Alexander, North Carolina
BLE Project Number J17-9378-11
Monitoring Wells and Points
Installation
Date Geology Monitored MSW or C&D
Waste Unit
Monitored1
Well
Status/Purpose
Well Diameter
(in)Northing Easting
TOC
Elevation (ft)
Ground Surface
Elevation (ft)Well Depth (ft)
M-1 DNA DNA MSW Cell 5 Compliance DNA DNA DNA DNA DNA DNA DNA -DNA
M-2 DNA DNA MSW Cells 1 and 2 Compliance DNA DNA DNA DNA DNA DNA DNA -DNA
M-3 10/28/2009 Saprolite MSW Cell 1 Compliance 2.0 DNA DNA DNA DNA 35.0 5.0 -35.0
M-4 10/28/2009 Saprolite/PWR MSW Cells 1 and 3 Compliance 2.0 DNA DNA DNA DNA 9.0 4.0 -9.0
M-5 Pending MSW Cell 7 Compliance
M-6 Pending MSW Cell 7 Compliance
M-7 Pending MSW Cell 8 Compliance
M-8 Pending MSW Cell 9 Compliance
M-9 Pending MSW Cell 10 Compliance
M-10 10/27/2009 Saprolite/PWR C&D Phases 1-5 Compliance 2.0 DNA DNA DNA DNA 15.0 5.0 -15.0
M-11 10/27/2009 Saprolite/PWR C&D Phases 1-5 Compliance 2.0 DNA DNA DNA DNA 10.0 5.0 -10.0
M-12 Proposed C&D Phase 6 Compliance
Scale House Existing Structure Enclosed Structure Facility Facility Compliance NA NA NA NA NA NA NA
Landfill Office Building Existing Structure Enclosed Structure Facility Facility Compliance NA NA NA NA NA NA NA
Convenience Center Existing Structure Enclosed Structure Facility Facility Compliance NA NA NA NA NA NA NA
Well House Existing Structure Enclosed Structure Facility Facility Compliance NA NA NA NA NA NA NA
Block Building Existing Structure Enclosed Structure Facility Facility Compliance NA NA NA NA NA NA NA
HHW Building Existing Structure Enclosed Structure Facility Facility Compliance NA NA NA NA NA NA NA
Radio Tower Existing Structure Enclosed Structure Facility Facility Compliance NA NA NA NA NA NA NA
Garage (Maintenance Building)Existing Structure Enclosed Structure Facility Facility Compliance NA NA NA NA NA NA NA
Employee Trailer Existing Structure Enclosed Structure Facility Facility Compliance NA NA NA NA NA NA NA
1 - Based on visual observation of Sheet No 1 Groundwater and Methane Monitoring Well Locations by CDM Smith dated August 2014.
M - Landfill Gas Monitoring Well.
All depth measurments in feet -- All elevations in feet above an arbitrary site datum.
TOC - Top of Casing.
GS - Ground Surface.
DNA - Data Not Available.
NA - Not Applicable.
Pending - Wells have been approved by the DEQ for installation when the waste units are constructed.
Screen Depth
(below GS)
S:\02 AWA Projects\McGill\Buncombe County Landfill\9378-11 BCLF Phase 6 CnD EMP\LFGMP\BCLF 9378-11 LFGMP Tables.xlsx
Prepared by: AWA
Checked by: MSP
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APPENDICES
APPENDIX A
LANDFILL GAS MONITORING GUIDANCE (NOVEMBER 2010)
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NORTH CAROLINA DEPARTMENT OF
ENVIRONMENT AND NATURAL RESOURCES
DIVISION OF WASTE MANAGEMENT
SOLID WASTE SECTION
LANDFILL GAS MONITORING GUIDANCE
NOVEMBER 2010
TABLE OF CONTENTS
Section 1 – Introduction ………………………………………………………...............................Page 2
Section 2 – Factors Influencing Landfill Gas Generation and Migration …………………………Page 3
Section 3 - Current Solid Waste Section Rules Pertaining to Landfill Gas Monitoring ……….….Page 5
Section 4 – Landfill Gas Incidents and Explosions ………………………………………………..Page 9
Section 5 – Landfill Gas Monitoring Wells……………..………………………………………….Page 11
Section 6 – Landfill Gas Monitoring Instrumentation ……………………………………………..Page 14
Section 7 – References ……………………………………………………………………………..Page 17
Section 8 – Suggested Outline for a Landfill Gas Monitoring Plan ………………………………..Page 18
Section 9 – Checklist of Items to be Included in a Landfill Gas Monitoring Plan ………………....Page 19
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SECTION 1 - Introduction
North Carolina Solid Waste Management Rules 15A NCAC 13B require quarterly monitoring of methane
gas (at MSW landfills) and quarterly monitoring of methane and other explosive landfill gases (LFG) (at
C&D and other landfills) to ensure that landfill gas does not exceed the lower explosive limit (LEL) at the facility property boundary or 25 percent of the lower explosive limit in facility structures. If the
concentration exceeds the specified limits, steps must be taken to ensure the protection of public health
and a remediation plan must be implemented immediately. A landfill gas monitoring plan is necessary to
ensure that these performance standards are met and this guidance document was developed to assist in
establishing a standardized procedure for the monitoring of landfill gas.
Background Organic matter in landfills begins to decompose almost immediately after being placed in a disposal site.
Putrescible wastes such as food products and sewage sludges begin to break down by biological processes
very rapidly whereas paper, cardboard or cellulose based materials are slower to decompose. However,
when conditions become favorable, most organic matter will decompose. The decomposition process typically goes through several stages that depend on conditions such as pH, temperature, and moisture
content. The final stage results in the production of methane and although the rate of production may
vary, most landfills produce methane.
Landfill Gas Generation
Landfill gas is a natural by-product of the anaerobic decomposition of organic waste in a landfill. The composition, quantity and rate of landfill gas generation are dependent on the types of waste that are
decomposing and the level of microbial activity within the wastes. The decomposition of biodegradable
waste begins with aerobic decomposition which lasts until the oxygen in the landfill is depleted. The
anaerobic phase then begins, resulting in landfill gas production.
There are four stages of landfill gas composition: the first stage is characterized by elevated nitrogen levels and occurs when the landfill is new. The second stage is characterized by elevated carbon dioxide
levels and occurs for a relatively short period of time after the initial stage is complete. The third and
fourth stages are characterized by elevated methane concentrations and represent the active life of a
landfill and the post-closure time frame.
Landfill gas is generally composed of 50-55% methane (CH4); 45-50% carbon dioxide (CO2); less than 5% nitrogen (N2); and less than 1% non-methane organic compounds. These individual gases generally
remain co-mingled and do not naturally separate. The Solid Waste Section (SWS) Rules typically focus
on methane (CH4) and its explosive properties due to public safety issues. Hydrogen sulfide (H2S) is
also of particular concern in landfills and is typically recognized by its rotten egg odor. H2S is
immediately dangerous to life and health at concentrations of 100 parts per million (ppm).
Landfill Gas Migration The production of landfill gas creates a positive pressure within the landfill that forces the gas to migrate.
Landfill gas migrates from place to place by diffusion and pressure gradient and will follow the path of
least resistance. Subsurface gas typically migrates above the groundwater table and is restricted laterally
by streams. Porous soils lying above the bedrock can serve as pathways to transmit large volumes of gas. Underground off-site migration is common and can be facilitated by the presence of pipelines, buried
utility corridors or trenches located within or adjacent to the landfill boundaries. Movement depends on
soil type and moisture, and migration distances of 1,500 feet have been observed. Barometric pressure
also influences movement. Falling barometric pressure allows methane to migrate out of the landfill and into surrounding areas.
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SECTION 2 - Factors Influencing Landfill Gas Generation and Migration
Factors that affect landfill gas generation and migration through the subsurface include the following:
Waste Composition
The production of landfill gas is directly related to the amount of organic matter present in waste. The
bacteria that break down the waste require small amounts of specific minerals such as calcium, potassium, magnesium and other micronutrients. Bacteria are able to thrive and produce landfill gas if the
minerals/micronutrients are present. If the minerals/micronutrients are not present or if substances that
inhibit bacterial growth exist, landfill gas production will occur at a reduced rate. Some forms of organic
matter such as cellulose break down quickly whereas matter such as lignin breaks down more slowly.
The rate at which landfill gas is produced depends on the proportions of each type of organic matter present in the waste.
Moisture Content
Landfills with higher moisture content generate higher concentrations of landfill gas in earlier stages of
development (such as during leachate recirculation). Moisture accelerates the methanogenic process.
Temperature
Landfill bacteria are temperature dependant. They are able to survive and function below the freezing
point, but they also function well at temperatures up to 65°C. Anaerobic bacteria produce small amounts
of heat and may not be able to maintain the temperature of a shallow landfill when external temperatures decrease, so LFG generation may exhibit seasonal variations. Saturated landfills may not achieve ideal
temperatures because the bacteria do not generate sufficient heat to raise the temperature of the excess
water. Higher temperatures promote volatilization and chemical reactions with the waste so the trace gas
component of landfill gas tends to increase with higher landfill temperatures.
Age of Landfill Typically, landfills have an increasing generation of landfill gas for a number of years until closure at
which time landfill gas generation reaches a peak and begins to subside. An evaluation of the age of the
landfill and use of a landfill gas generation curve can be helpful in determining the likelihood of
significant landfill gas concentrations from the landfill.
Landfill Cap
The type or presence of landfill cover can influence landfill gas generation and migration. Although a low
permeability cap will reduce moisture and landfill gas generation over the longer term, initially, the
installation of a landfill cap could drive landfill gas migration further from the landfill in the subsurface without proper ventilation (either passive or active). This is especially true in the case of unlined
(unvented) landfills.
Water Table Landfill gas movement in unlined landfills may be influenced by groundwater table variations. A rising water table could cause displacement and force upward movement of landfill gas.
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Man-made and Natural Conduits
Structures such as drains, trenches, and buried utility corridors can act as conduits for landfill gas migration. Geologic features including fractured bedrock, porous soil, and permeable strata also provide conduits for landfill gas migration
Landfill Liner Conditions
The presence of a Subtitle-D (or equivalent) landfill liner has the capability to limit the lateral migration of landfill gas in the subsurface. Unlined landfills have no barrier to prevent lateral landfill gas migration in the subsurface.
Weather Conditions
Barometric pressure and precipitation have significant effects on landfill gas migration. Increased barometric pressure yields decreased landfill gas venting from the subsurface, until the pressure within the subsurface is greater than the atmospheric (barometric) pressure. Conversely, as the barometric pressure
decreases, the landfill will vent the stored gas until pressure equilibrium is reached. Capping of a landfill
can influence the effect of barometric pressure on landfill gas migration. Generally, a more permeable
landfill cap will allow greater influence by barometric pressure than a less permeable landfill cap.
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SECTION 3 – Current Solid Waste Section Rules Pertaining to Landfill Gas
Monitoring
Web link to the 15A NCAC 13B rules - http://portal.ncdenr.org/web/wm/sw/rules
15A NCAC 13B
.0101- DEFINITIONS .0101 (14) "Explosive gas" means Methane (CH4)
.0101(25) "Lower explosive limit" (LEL) means the lowest percent by volume of a mixture of explosive
gases which will propagate a flame in air at 25 degrees Celsius and atmospheric pressure.
.0503 - SITING AND DESIGN REQUIREMENTS FOR DISPOSAL FACILITIES .0503(2) A site shall meet the following design requirements:
(a) The concentration of explosive gases generated by the site shall not exceed:
(i) twenty-five percent of the limit for the gases in site structures (excluding gas control or
recovery system components); and (ii) the lower explosive limit for the gases at the property boundary;
.0543 - CLOSURE AND POST-CLOSURE REQUIREMENTS FOR C&DLF FACILITIES
.0543(e) Post-closure criteria.
(1) Following closure of each C&DLF unit, the owner and operator must conduct post-closure care. Postclosure care must be conducted for 30 years, except as provided under Subparagraph (2)
of this Paragraph, and consist of at least the following:
(C) maintaining and operating the gas monitoring system in accordance with the
requirements of Rule .0544 of this Section; and
(2) The length of the post-closure care period may be: (A) decreased by the Division if the owner or operator demonstrates that
the reduced period is sufficient to protect human health and the environment and this
demonstration is approved by the Division; or
(B) increased by the Division if the Division determines that the lengthened period is necessary to protect human health and the environment.
.0544 - MONITORING PLANS AND REQUIREMENTS FOR C&DLF FACILITIES
.0544(d) Gas Control Plan
(1) Owners and operators of all C&DLF units must ensure that: (A) the concentration of methane gas or other explosive gases generated by the facility does not exceed 25 percent of the lower explosive limit in on-site facility structures
(excluding gas control or recovery system components);
(B) the concentration of methane gas or other explosive gases does not exceed the lower
explosive limit for methane or other explosive gases at the facility property boundary; and (C) the facility does not release methane gas or other explosive gases in any concentration that can be detected in offsite structures.
(2) Owners and operators of all C&DLF units must implement a routine methane monitoring
program to ensure that the standards of this Paragraph are met.
(A) The type of monitoring must be determined based on soil conditions, the Hydrogeologic conditions under and surrounding the facility, hydraulic conditions on and surrounding the facility, the location of facility structures and property boundaries, and the
location of all offsite structures adjacent to property boundaries.
6
(B) The frequency of monitoring shall be quarterly or as approved by the Division.
(3) If methane or explosive gas levels exceeding the limits specified in Subparagraph (d)(1) of this Rule are detected, the owner and operator must: (A) immediately take all steps necessary to ensure protection of human health and notify
the Division;
(B) within seven days of detection, place in the operating record the methane or explosive
gas levels detected and a description of the steps taken to protect human health; and (C) within 60 days of detection, implement a remediation plan for the methane or explosive gas releases, place a copy of the plan in the operating record, and notify the
Division that the plan has been implemented. The plan must describe the nature and extent
of the problem and the proposed remedy.
(4) Based on the need for an extension demonstrated by the operator, the Division may establish alternative schedules for demonstrating compliance with Parts (3)(B) and (3)(C) of this Paragraph. (5) For purposes of this Item, "lower explosive limit" means the lowest percent by volume of a
mixture of explosive gases in air that will propagate a flame at 25 C and atmospheric pressure.
.0566 - OPERATIONAL REQUIREMENTS FOR LAND CLEARING/INERT DEBRIS (LCID)
LANDFILLS .0566(13) The concentration of explosive gases generated by the facility shall not exceed:
(a) Twenty-five percent of the lower explosive limit for the gases in facility structures.
(b) The lower explosive limit for the gases at the property boundary.
.1626 – OPERATIONAL REQUIREMENTS FOR MSWLF FACILITIES .1626(4) Explosive gases control.
(a) Owners or operators of all MSWLF units must ensure that:
(i) The concentration of methane gas generated by the facility does not exceed 25 percent
of the lower explosive limit for methane in facility structures (excluding gas control or recovery system components); and
(ii) The concentration of methane gas does not exceed the lower explosive limit for
methane at the facility property boundary.
(b) Owners or operators of all MSWLF units must implement a routine methane monitoring
program to ensure that the standards of (4)(a) are met. A permanent monitoring system shall be constructed on or before October 9, 1994. A temporary monitoring system shall be used prior to
construction of the permanent system.
(i) The type and frequency of monitoring must be determined based on the following
factors:
(A) Soil conditions; (B) The hydrogeologic conditions surrounding the facility;
(C) The hydraulic conditions surrounding the facility; and
(D) The location of facility structures and property boundaries.
(ii) The minimum frequency of monitoring shall be quarterly.
(c) If methane gas levels exceeding the limits specified in (4)(a) are detected, the owner or operator must:
(i) Immediately take all necessary steps to ensure protection of human health and notify the
Division;
(ii) Within seven days of detection, place in the operating record the methane gas levels
detected and a description of the steps taken to protect human health; and (iii) Within 60 days of detection, implement a remediation plan for the methane gas
releases, place a copy of the plan in the operating record, and notify the Division that the
7
plan has been implemented. The plan shall describe the nature and extent of the problem
and the proposed remedy. (iv) Based on the need for an extension demonstrated by the operator, the Division may establish alternative schedules for demonstrating compliance with (4)(c)(ii) and (iii) of this
Rule.
(d) For purposes of this Item, "lower explosive limit" means the lowest percent by volume of a
mixture of explosive gases in air that will propagate a flame at 25°C and atmospheric pressure. .1626(10) Recordkeeping requirements. (a) The owner or operator of a MSWLF unit must record and retain at the facility, or an alternative
location near the facility approved by the Division, in an operating record the following
information as it becomes available:
(iii) Gas monitoring results and any remediation plans required by Item (4) of this Rule;
.1627 – CLOSURE AND POST CLOSURE REQUIREMENTS FOR MSWLF ACTIVITES
.1627(d) Post-Closure Criteria
(1) Following closure of each MSWLF unit, the owner or operator shall conduct post-closure care.
Post-closure care shall be conducted for 30 years, except as provided under Subparagraph (2) of this Paragraph, and consist of at least the following: (D)-Maintaining and operating the gas monitoring system in accordance with the
requirements of Rule .1626 of this Section.
(2) The length of the post-closure care period may be:
(A) Decreased by the Division if the owner or operator demonstrates that the reduced period is sufficient to protect human health and the environment and this demonstration is approved by the Division; or
(B) Increased by the Division if the Division determines that the lengthened period is
necessary to protect human health and the environment.
(3) Following completion of the post-closure care period for each MSWLF unit, the owner or operator shall notify the Division that a certification, signed by a registered professional engineer,
verifying that post-closure care has been completed in accordance with the post-closure plan, has
been placed in the operating record.
NOTES:
Based on the referenced rules above, the following words / phrases are presently in the Solid Waste
Section rules pertaining to methane and explosive landfill gas.
Rule .0101(14) states: “Explosive gas means Methane (CH)”. Rule .0503 (2)(a) refers to “explosive gases”.
Rule .0544(d) refers to “Gas Control Plan”
Rule .0544(d)(1) refers to “methane or other explosive gases”.
Rule .0544(d)(2) refers to “methane monitoring program”
Rule .0544(d)(3) refers to “methane or explosive gas levels” Rule .0566 (13) refers to “explosive gases”.
Rule .1626 (4) refers to “explosive gases control”
Rule .1626(4)(a-b) refers to “methane monitoring” and “methane monitoring program”.
8
Monitoring Goals
Landfill design and landfill gas monitoring regulations in North Carolina require that there not be an exceedance of 100% of the Lower Explosion Limit (LEL) (equivalent to 5% methane) at the property boundary, or 25% LEL in on-site structures. These regulations were developed over time to protect the
health and safety of the citizens of North Carolina and the U.S. from the asphyxiation and explosive
hazards of landfill gas.
NC Rule History A review of NC landfill guidance documents and regulations from 1972 to the present indicates that from 1972 through 1982, there was no mention of design requirements regarding the control of landfill gas, nor
were there any landfill monitoring requirements for landfill gas. In 1982, the regulations were changed to
require that sanitary landfill design prevent landfill gas concentrations of 100% LEL at the property
boundary line and 25% inside on-site structures. Although a design requirement was added, no design requirement was established to determine if the design requirement was being met. In 1993 with the
establishment of .1600 rules, requirements for designs to limit landfill gas levels to below 100% at the
property boundary line and 25% in on-site structures and monitoring of landfill gas concentrations around
the perimeter of the landfill and inside on-site structures were adopted.
9
SECTION 4 – Landfill Gas Incidents and Explosions
Hazards Involving Landfill Gas
Landfill fires may or may not be directly caused by landfill gas. The primary concern with these fires is
air contamination from the resulting smoke; however they also present a variety of additional problems. In addition to concerns with containing and extinguishing landfill fires, potential reactions involving
unknown chemicals in the landfill can cause uncertain hazards. Discarded consumer products in a
landfill, such as pesticides, paints, solvents, cleaners, and other material can be the source of chemical
releases. Heat from the fire can cause chemicals to volatilize, breakdown, and enter the environment. Also
to be considered is the presence of other combustible gases in addition to methane. Whenever an environmental investigation of a landfill is prompted by odorous compounds or explosive gases, the
presence of toxic substances should also be investigated. One example is hydrogen sulfide (H2S) that can
cause asphyxiation and is flammable. An analysis should include alkyl benzenes, sulfur compounds, vinyl
chloride, and methane, and other products associated with industrial wastes, construction and debris
waste, and normal organic and inorganic waste.
Fires and explosion hazards become a concern when gases collect in confined spaces. Buildings,
basements, and pits are typically regarded as confined spaces. However, landfill gases also collect in and
migrate to cracks in the landfill cover, leachate “springs”, cracks in adjacent structures, paved parking
areas, etc. Fires can occur on the surface and underground. Surface fires involve recently buried waste near the surface in an aerobic decomposing layer, typically 1 to 4 feet below ground. These fires can be
intensified by subsurface landfill gas and spread throughout the landfill. Subsurface fires occur deeper
within the landfill, involve material buried for months or years, and can burn for days and months.
The following is a brief summary of some incidents involving landfill gas migration from landfills:
2007 Four employees died as a result of exposure to high concentrations of hydrogen sulfide while
attempting to repair a leachate pump at a C&D landfill in Superior, Wisconsin (Journal of
Environmental Heath 2008).
1999 An 8-year old girl was burned on her arms and legs when playing in an Atlanta, Georgia
playground. The area was reportedly used as an illegal dumping ground many years ago (Atlanta
Journal-Constitution 1999).
1994 While playing soccer in a park built over an old landfill in Charlotte, North Carolina, a woman was seriously burned by a methane explosion (Charlotte Observer 1994).
1987 Offsite landfill gas migration is suspected to have caused a house to explode in Pittsburgh,
Pennsylvania (EPA 1991).
1984 Landfill gas migrated to and destroyed one house near a landfill in Akron, Ohio. Ten houses were
temporarily evacuated (EPA 1991).
1983 An explosion destroyed a residence across the street from a landfill in Cincinnati, Ohio. Minor
injuries were reported (EPA 1991).
1975 In Sheridan, Colorado, landfill gas accumulated in a storm drain pipe that ran through a landfill. An
explosion occurred when several children playing in the pipe lit a candle, resulting in serious
injury.
10
1969 Methane gas migrated from an adjacent landfill into the basement of an armory in Winston-Salem, North Carolina. A lit cigarette caused the gas to explode, killing three men and seriously injuring five others (USACE 1984).
11
SECTION 5 - Landfill Gas Monitoring Wells
Locations Landfill gas monitoring well locations will be site specific depending upon site geology, depth to
groundwater, surface water features, on-site and off-site structures and sensitive receptors. The landfill
gas monitoring wells must be spaced no more than 500 feet apart depending upon site specifics. A readily
accessible, unobstructed path must be maintained so that landfill gas monitoring wells are always accessible using four-wheel drive vehicles. Regardless of site specifics, the permittee must obtain
approval from the Solid Waste Section for the design and installation of any landfill gas monitoring well
system.
Well Construction and Installation Landfill gas monitoring wells are the same as groundwater monitoring wells with two exceptions. Landfill
gas monitoring wells are installed just above the water table within the unsaturated zone and are equipped
with a stopcock valve or a quick connect coupling on the cap, which allows for accurate landfill gas
measurements. The stopcock valve must be equipped with flexible tubing and a barb connection that will
fit the gas meter’s inlet tube. The stopcock valve or a quick connect coupling must be closed between monitoring events. The landfill gas monitoring well must also be capped, locked, and labeled with a
permanently affixed identification plate stating the well contractor name and certification number, date of
well competition, total depth of well, screen length and well ID number. See detailed schematics of a
landfill gas monitoring well (Figure 1).
The depth of each landfill gas monitoring well will be site specific depending upon depth to groundwater.
Landfill gas monitoring wells must be constructed the same as groundwater monitoring wells as described
in 15A NCAC Subchapter 2C. Typically landfill gas monitoring wells must be installed using 2” PVC
piping and screen. The screen length, also site specific, must span the majority of the unsaturated zone
while still allowing for proper well construction. A North Carolina Licensed/Professional Geologist must be present to supervise the installation of all landfill gas monitoring wells. The exact locations, screened
intervals, and nesting of the wells must be approved by the Solid Waste Section Hydrogeologist prior to
landfill gas monitoring well installation. Each landfill gas monitoring well must be surveyed for location
and elevation by a North Carolina Registered Land Surveyor. Within thirty (30) days of the completed
construction of each new landfill gas monitoring well, the well construction record (Division of Water Quality form GW-1b) and the boring log/well detail diagram of each well must be submitted to the Solid
Waste Section. The submittal must also include a scaled topographic map showing the location and
identification of new, existing and abandoned landfill gas monitoring wells.
Nested and Clustered Landfill Gas Monitoring Wells Nested and/or clustered landfill gas monitoring wells may be required in unsaturated zones of 45 feet or
more to measure specific depths of the unsaturated zone. Initially, the installation of one long screen shall
be sufficient. If a monitoring event shows an exceedance of the lower explosive limit, then the Solid
Waste Section may require the installation of nested and/or clustered landfill gas monitoring wells.
Abandonment of Wells
An abandonment record must be submitted to the Solid Waste Section within 30 (thirty) days of the
abandonment of a landfill gas monitoring well. The landfill gas monitoring well(s) must be overdrilled
and sealed with grout in accordance with 15A NCAC 2C .0113(d) and certified by a North Carolina Licensed/Professional Geologist.
12
Professional Certification
The certification statement below must be signed and sealed by a Professional Geologist and submitted
with the Landfill Gas Monitoring Plan.
The landfill gas monitoring plan for this facility has been prepared by a qualified geologist who is
licensed to practice in the State of North Carolina. The plan has been prepared based on first-hand
knowledge of site conditions and familiarity with North Carolina solid waste rules and industry
standard protocol. This certification is made in accordance with North Carolina Solid Waste
Regulations, indicating this Landfill Gas Monitoring Plan should provide early detection of any
release of hazardous constituents to the uppermost aquifer, so as to be protective of public health
and the environment. No other warranties, expressed or implied, are made.
Signed _______________________________
Printed _______________________________
Date _________________________________
Not valid unless this document bears the seal of the above mentioned licensed professional.
13
Figure 1 – Landfill Gas Monitoring Well Detail
14
SECTION 6 – Landfill Gas Monitoring Instrumentation
The person using the landfill gas monitoring instrument must understand the principles of operation and
follow the manufacturer's instructions. This includes calibrating the instrument according to the
manufacturer’s specifications. Include the following on the top portion of the landfill gas monitoring
form (See example below) : facility name, permit number, type and serial number of gas monitoring
instrument, calibration date of the instrument, date and time of field calibration, type of gas used for field calibration (15/15 or 35/50), expiration date of field calibration gas canister, date of landfill gas
monitoring event, name and position of sample collector, pump rate of instrument being used, ambient air
temperature, and general weather conditions. Verification that the equipment was calibrated in
accordance with the manufacturer’s specifications is also required. When determining which field
calibration gas to use, take into consideration the expected levels of methane in the landfill gas monitoring wells. If the methane levels are expected to be low, use the 15/15 gas canister (15% CO2/15% CH4). If
the methane levels are expected to be high, use the 35/50 gas canister (35% CO2/50% CH4).
For every landfill gas monitoring well, please include the following: verification of sample tube purge
prior to each sample taken (should be one minute), the time pumped in seconds (should be at least one
minute), barometric pressure, time stabilized reading collected, percent lower explosive limit, percent
methane by volume, percent oxygen, percent carbon dioxide, and any observations or comments. Most
modern gas monitoring instruments will measure percent oxygen and carbon dioxide in addition to the
methane and display the results on the same instrument. Recording the levels of percent oxygen and
carbon dioxide should require little or no extra effort.
The landfill gas monitoring data form (See example below) and results should be retained in the facility’s
operating record unless an exceedance has occurred and/or is requested by the Solid Waste Section. Landfill gas monitoring readings from non-calibrated or inaccurately calibrated instruments are not
reliable, and will therefore be rejected by the Solid Waste Section. Landfill gas monitoring readings
collected with monitoring equipment that was not designed for landfill gas monitoring will also be
rejected by the Solid Waste Section. There are several different landfill gas monitoring instruments on the market which may be used in order to obtain all of the information required by the Solid Waste Section.
Monitoring Times
Monitoring times are also important when conducting landfill gas monitoring. Proper landfill gas monitoring should include sampling during times when landfill gas is most likely to migrate. Landfill gas can migrate and accumulate not only in landfill gas monitoring wells; it can also migrate and accumulate
in buildings and other structures. Because subsurface gas pressures are considered to be at a maximum
during the afternoon hours, monitoring should be conducted in the afternoon or whenever the barometric
pressure is low. Scientific evidence also indicates that weather and soil conditions influence the migration of landfill gas.
Barometric pressure and precipitation have significant effects on landfill gas migration. Increased
barometric pressure generates decreased landfill gas venting from the subsurface, until the pressure within
the subsurface is greater than the atmospheric (barometric) pressure. On the other hand, when the barometric pressure decreases, the landfill will vent the stored gas until a pressure equilibrium is reached. Capping of a landfill can influence the effect of barometric pressure on landfill gas migration. Generally,
a more permeable landfill cap will allow greater influence by barometric pressure than a less permeable
15
landfill cap. As a result, landfill gas monitoring should be conducted when the barometric pressure is low
and soils are saturated. During the winter season when snow cover is just beginning to melt or when the ground is frozen or ice covered, landfill gas monitoring should be conducted when the barometric pressure is low.
Landfill Gas Sampling Procedures
Any accumulation of landfill gas in the landfill gas monitoring wells is the result of landfill gas migration. The following procedure is a recommended example for conducting landfill gas monitoring well sampling, but always read and follow the manufacturer’s instructions because each instrument will be
different.
Step 1 – Calibrate the instrument according to the manufacturer’s specifications. In addition, prepare the instrument for monitoring by allowing it to properly warm up as directed by the manufacturer. Make sure the static pressure shows a reading of zero on the instrument prior to taking the first sample.
Step 2 – Purge sample tube for at least one minute prior to taking reading. Connect the instrument tubing
to the landfill gas monitoring well cap fitted with a stopcock valve or quick connect coupling.
Step 3 – Open the valve and record the initial reading and then the stabilized reading. A stable reading is one that does not vary more than 0.5 percent by volume on the instrument’s scale.
Step 4 - Record the stabilized reading including the oxygen concentration and barometric pressure. A
proper reading should have two percent oxygen by volume or less. If levels of oxygen are higher, it may
indicate that air is being drawn into the system giving a false reading.
Step 5 – Turn the stopcock valve to the off position and disconnect the tubing.
Step 6 – Proceed to the next landfill gas monitoring well and repeat Steps 2 – 5.
Landfill Gas Constituent Sampling and Analysis
Sampling of landfill gas to determine volume percentages/concentrations of each constituent can be
accomplished through the use of canisters which are specifically designed for landfill gas analysis. Several analytical methods are available to determine the concentrations of a variety of constituents. Typically, landfill gas analysis of this type is performed to determine the non-methane organic
compounds emission rate for Tier 2 testing under the Clean Air Act (Title V Subpart WWW 60.754).
Isotropic identification of landfill methane can be accomplished to identify one source of methane from
another. In this case, isotopes of carbon and hydrogen in the methane are analyzed to determine the methane source.
17
SECTION 7 - References
Agency for Toxic Substances & Disease Registry. “Landfill Gas Primer- An Overview for Environmental
Health Professionals. 2001.” http://www.atsdr.cdc.gov/HAC/landfill/html/toc.html (accessed February 24.
2010).
California Environmental Protection Agency. “Landfill Gas Monitoring Well Functionality at 20 California Landfills, 2008”. http://www.calrecycle.ca.gov/Publications/Organics/2008022.pdf (accessed
February 24 2010).
Florida Department of Environmental Protection. Gas Management Systems, under Rule 62-701.530.
http://www.dep.state.fl.us/waste/quick_topics/rules/default.htm (accessed February 24, 2010).
Missouri Department of Natural Resources, Flood Grant Team. “An Analysis of Landfill Gas Monitoring
Well Design and Construction, 2007”. http://www.clu-
in.org/conf/itrc/directpush/prez/Missouri_Study.pdf (accessed February 24, 2010).
Missouri Department of Natural Resources. “Design and Construction of Landfill Gas Monitoring Wells”.
http://www.dnr.missouri.gov/pubs/pub2054.pdf (accessed February 24. 2010).
Wisconsin Department of Natural Resources. Environmental Monitoring for Landfills, under Chapter NR
507.22. http://www.dnr.state.wi.us/org/aw/wm/information/wiacsss.htm (accessed February 24, 2010).
“Landfill Gas-an Overview” Landfill-gas.com. Web, 22, Feb. 2010
http://www.landfill-gas.com/webpage -LFG-overview.doc
18
SECTION 8 – Suggested Outline for a Landfill Gas Monitoring Plan
1. Introduction
1.1. Background (project overview, site observations, NCDENR rules referenced)
1.2. Site Geology with discussion of groundwater depth and flow (potentiometric surface map)
1.3. Regulatory Limits
2. Landfill Gas Monitoring
2.1. Landfill Gas Monitoring Well Locations (discussion of reasoning behind proposed locations,
discussion of well construction, reference map showing proposed locations, reference table
displaying well ID, well depth, screen interval and depth to groundwater)
2.2. Structure and Ambient Sampling
2.3. Landfill Gas Monitoring Frequency
3. Landfill Gas Sampling Procedures
3.1. Detection Equipment Used (discussion of calibration procedures)
3.2. Landfill Gas Sampling Procedure
4. Record Keeping and Reporting
4.1. Landfill Gas Monitoring Data Form
4.2. Sampling Reports
4.3. Permanent Record Keeping
5. Contingency Plan
6. Certification of Professional Geologist
7. Certification of Registered Land Surveyor
Figures
Map displaying proposed landfill gas monitoring well locations
Potentiometric Surface Map
Diagram showing construction of stopcock valve or quick connect coupling on well cap
Diagram showing well construction of each landfill gas monitoring well
Table
Table displaying well ID, well depth, screen interval, depth to groundwater
Example of landfill gas monitoring data form
19
SECTION 9 – Checklist of Items to be Included in a Landfill Gas Monitoring Plan
1. Depth to groundwater discussion
2. Well locations
a. Number of wells
b. Well spacing
3. Instrumentation being used
a. Calibration procedures
4. Sampling procedures as per the manufacture’s instructions
5. Map of well locations
6. Table describing each well location
a. Well ID
b. Well depth
c. Screen interval
d. Depth to groundwater
e. Subsurface lithology
7. Diagram of cap construction w/ stopcock valve or quick connect coupling
8. Diagram of well construction
9. Potentiometric surface map
10. Professional Geologist certification
11. Registered Land Surveyor certification
Revised – March 6, 2017
NC Division of Waste Management - Solid Waste Section
Landfill Gas Monitoring Data Form
Notice: This form and any information attached to it are "Public Records" as defined in NC General Statute 132-1. As such, these documents are
available for inspection and examination by any person upon request (NC General Statute 132-6).
Facility Name: Permit Number:
Sampling Date: NC Landfill Rule (.0500 or .1600):
Sample Collector Name & Position:
Gas Meter Type & Serial Number: Gas Meter Calibration Date:
Field Calibration Date & Time:
Field Calibration Gas Type (15/15 or 35/50): Field Calibration Gas Canister Expiration Date:
Gas Meter Pump Rate:
Ambient Air Temperature: Barometric Pressure (in. or mm Hg): Weather Conditions:
Instructions: Under “Location or LFG Well”, list monitoring well # or describe monitoring location (e.g., inside field office). Attach a test location map or drawing. Report methane readings as both % LEL and % CH4 by volume.
Convert % CH4 (by volume) to % LEL as follows: % methane (by volume)/20 = % LEL. *Hydrogen Sulfide (H2S) gas monitoring may be required for Construction & Demolition Landfills (CDLFs). See
individual permit conditions and/or Facility LFG monitoring plan.
Location or
LFG Well ID
Sample
Tube
Purge
Time of Day
Time
Pumped
(sec)
Initial % LEL Stabilized % LEL % CH4 (volume)
% O2 (volume)
% CO2 (volume)
% H2S* (volume)
NOTES
NOTE: If needed, attach additional data forms to include additional LFG monitoring data locations for the facility.
ACTION LEVELS: Methane: >1.25% by volume (inside structures) AND >5% by volume (at facility boundary)
Hydrogen Sulfide: >1% by volume (inside structures) AND >4% by volume (at facility boundary)
Certification
To the best of my knowledge, the information reported and statements made on this data submittal and attachments
are true and correct. I am aware that there are significant penalties for making any false statement, representation,
or certification including the possibility of a fine and imprisonment.
SIGNATURE TITLE
APPENDIX B
WELL CONSTRUCTION RECORDS
0
-5
-10
-15
FIELD BOREHOLE LOG
BOREHOLE NO.:
TOTAL DEPTH:
PROJECT INFORMATION DRILLING INFORMATION
PROJECT:
SITE LOCATION:
JOB NO:
GEOLOGIST:
DATE DRILLED:
DRILLING CO:
DRILLER:
RIG TYPE:
METHOD OF DRILLING:
SAMPLING METHODS:
Depth Soil
Symbol Soil Description Sample Blows/6" (Recovery)Well
Construction
Well
Description
A
Page 1 of 2Notes:
Bentonite
2-inch Schedule 40
PVC Riser
Locking, Above
Grade Protective
Cover
Cement Grout
#2 Silica Sand Filter
Pack
Schedule 40 PVC
Screen, 0.010" Slot,
from 5' to 35' bls
SILTY SAND: SAPROLITE, granular
weathered rock from 4.5-5, 9.25-9.75,
and 12-17 feet, brown with a little
orangish brown, fine-grained,
micaceous, loose to dense, moist
SILT: some fine-grained SAND, trace
weathered rock, brown with a little
orangish brown, micaceous, loose to
medium dense, moist
S1 (3-5)
S2 (8-10)
S3 (13-15)
S4 (18-20)
2-2-4-7 (24")
21-19-17-13 (20")
2-4-5-5 (24")
1-3-4-5 (24")
Buncombe County Methane Well Installation
85 Panther Branch Road, Alexander, NC
6447-73768
Dan Forbes
10/28/09
SAEDACCO
Stefan Smith
Diedrich D-50
8.25" Hollow-Stem Auger
Split-Spoon
140 lb., 30 in.
M-3
35'
HAMMER WT./DROP:
-20
-25
-30
-35
FIELD BOREHOLE LOG
BOREHOLE NO.:
TOTAL DEPTH:
PROJECT INFORMATION DRILLING INFORMATION
PROJECT:
SITE LOCATION:
JOB NO:
GEOLOGIST:
DATE DRILLED:
DRILLING CO:
DRILLER:
RIG TYPE:
METHOD OF DRILLING:
SAMPLING METHODS:
Depth Soil
Symbol Soil Description Sample Blows/6" (Recovery)Well
Construction
Well
Description
A
Page 2 of 2Notes:
#2 Silica Sand Filter
Pack
Schedule 40 PVC
Screen, 0.010" Slot,
from 5' to 35' blsSILTY SAND: trace weathered rock,
brown with a little orangish brown, fine-
grained, micaceous, medium dense,
moist
S5 (23-25)
S6 (28-30)
S7 (33-35)
1-3-5-9 (24")
2-4-6-8 (22")
5-7-6-13 (20")
Buncombe County Methane Well Installation
85 Panther Branch Road, Alexander, NC
6447-73768
Dan Forbes
10/28/09
SAEDACCO
Stefan Smith
Diedrich D-50
8.25" Hollow-Stem Auger
Split-Spoon
140 lb., 30 in.
M-3
35'
HAMMER WT./DROP:
0
-5
-10
FIELD BOREHOLE LOG
BOREHOLE NO.:
TOTAL DEPTH:
PROJECT INFORMATION DRILLING INFORMATION
PROJECT:
SITE LOCATION:
JOB NO:
GEOLOGIST:
DATE DRILLED:
DRILLING CO:
DRILLER:
RIG TYPE:
METHOD OF DRILLING:
SAMPLING METHODS:
Depth Soil
Symbol Soil Description Sample Blows/6" (Recovery)Well
Construction
Well
Description
A
Page 1 of 1Notes:
Bentonite
#2 Silica Sand Filter
Pack
Schedule 40 PVC
Screen, 0.010" Slot,
from 4' to 9' bls
2-inch Schedule 40
PVC Riser
Locking, Above
Grade Protective
Cover
Cement Grout
SILT: some fine-grained SAND,
SAPROLITE transitioining to
PARTIALLY WEATHERED ROCK at 7
feet, very light brown to brown,
micaceous, medium dense to dense, dry
to moist
(Assumed lithology from 7 to 9 feet due
to poor recovery)
S1 (4-6)
S2 (9-11)
8-10-18-25 (24")
50/2 (2")
Buncombe County Methane Well Installation
85 Panther Branch Road, Alexander, NC
6447-73768
Dan Forbes
10/28/09
SAEDACCO
Stefan Smith
Diedrich D-50
8.25" Hollow-Stem Auger
Split-Spoon
140 lb., 30 in.
M-4
9'
HAMMER WT./DROP:
0
-5
-10
-15
FIELD BOREHOLE LOG
BOREHOLE NO.:
TOTAL DEPTH:
PROJECT INFORMATION DRILLING INFORMATION
PROJECT:
SITE LOCATION:
JOB NO:
GEOLOGIST:
DATE DRILLED:
DRILLING CO:
DRILLER:
RIG TYPE:
METHOD OF DRILLING:
SAMPLING METHODS:
Depth Soil
Symbol Soil Description Sample Blows/6" (Recovery)Well
Construction
Well
Description
A
Page 1 of 1Notes:
Bentonite
#2 Silica Sand Filter
Pack
Schedule 40 PVC
Screen, 0.010" Slot,
from 5' to 15' bls
2-inch Schedule 40
PVC Riser
Locking, Above
Grade Protective
Cover
Cement GroutSAND: some SILT, SAPROLITE
transitioining to PARTIALLY
WEATHERED ROCK at 5.5 feet, brown
with some orangish brown, fine-grained,
trace of weathered rock, dense, moist to
wet
(Assumed lithology from 7 to 15 feet
due to poor recovery)
S1 (4-6)
S2 (9-11)
S3 (14-16)
4-18-25-50/5 (20")
50/5 (2")
50/5 (2")
Buncombe County Methane Well Installation
85 Panther Branch Road, Alexander, NC
6447-73768
Dan Forbes
10/27/09
SAEDACCO
Stefan Smith
Diedrich D-50
8.25" Hollow-Stem Auger
Split-Spoon
140 lb., 30 in.
M-10
15'
Light to Heavy Rain during Installation
HAMMER WT./DROP:
0
-5
-10
FIELD BOREHOLE LOG
BOREHOLE NO.:
TOTAL DEPTH:
PROJECT INFORMATION DRILLING INFORMATION
PROJECT:
SITE LOCATION:
JOB NO:
GEOLOGIST:
DATE DRILLED:
DRILLING CO:
DRILLER:
RIG TYPE:
METHOD OF DRILLING:
SAMPLING METHODS:
Depth Soil
Symbol Soil Description Sample Blows/6" (Recovery)Well
Construction
Well
Description
A
Page 1 of 1Notes:
Bentonite
#2 Silica Sand Filter
Pack
Schedule 40 PVC
Screen, 0.010" Slot,
from 5' to 10' bls
2-inch Schedule 40
PVC Riser
Locking, Above
Grade Protective
Cover
Cement Grout
SILT: some fine-grained SAND,
SAPROLITE transitioining to
PARTIALLY WEATHERED ROCK at 5.5
feet, brown, dense, moist to wet
(Assumed lithology from 7 to 10 feet
due to poor recovery)
S1 (4-6)
S2 (9-11)
11-17-27-50/5 (17")
50/3 (2")
Buncombe County Methane Well Installation
85 Panther Branch Road, Alexander, NC
6447-73768
Dan Forbes
10/27/09
SAEDACCO
Stefan Smith
Diedrich D-50
8.25" Hollow-Stem Auger
Split-Spoon
140 lb., 30 in.
M-11
10'
Light to Heavy Rain during Installation
HAMMER WT./DROP:
APPENDIX C
ENVIRONMENTAL MONITORING REPORTING FORM
DENR USE ONLY: Paper Report Electronic Data - Email CD (data loaded: Yes / No ) Doc/Event #:
NC DENR
Division of Waste Management - Solid Waste
Environmental Monitoring
Reporting Form
Notice: This form and any information attached to it are "Public Records" as defined in NC General Statute 132-1. As such, these documents are
available for inspection and examination by any person upon request (NC General Statute 132-6).
Instructions:
Prepare one form for each individually monitored unit.
Please type or print legibly.
Attach a notification table with values that attain or exceed NC 2L groundwater standards or NC 2B surface water standards. The notification
must include a preliminary analysis of the cause and significance of each value. (e.g. naturally occurring, off-site source, pre-existing
condition, etc.).
Attach a notification table of any groundwater or surface water values that equal or exceed the reporting limits.
Attach a notification table of any methane gas values that attain or exceed explosive gas levels. This includes any structures on or nearby the
facility (NCAC 13B .1629 (4)(a)(i).
Send the original signed and sealed form, any tables, and Electronic Data Deliverable to: Compliance Unit, NCDENR-DWM, Solid Waste
Section, 1646 Mail Service Center, Raleigh, NC 27699-1646.
Solid Waste Monitoring Data Submittal Information
Name of entity submitting data (laboratory, consultant, facility owner):
Contact for questions about data formatting. Include data preparer's name, telephone number and E-mail address:
Name: Phone:
E-mail:
Facility name: Facility Address: Facility Permit #
NC Landfill Rule:
(.0500 or .1600)
Actual sampling dates (e.g.,
October 20-24, 2006)
Environmental Status: (Check all that apply)
Initial/Background Monitoring Detection Monitoring Assessment Monitoring Corrective Action
Type of data submitted: (Check all that apply)
Groundwater monitoring data from monitoring wells Methane gas monitoring data
Groundwater monitoring data from private water supply wells Corrective action data (specify)
Leachate monitoring data Other(specify) Surface water monitoring data
Notification attached?
No. No groundwater or surface water standards were exceeded.
Yes, a notification of values exceeding a groundwater or surface water standard is attached. It includes a list of groundwater and surface water
monitoring points, dates, analytical values, NC 2L groundwater standard, NC 2B surface water standard or NC Solid Waste GWPS and
preliminary analysis of the cause and significance of any concentration.
Yes, a notification of values exceeding an explosive methane gas limit is attached. It includes the methane monitoring points, dates, sample
values and explosive methane gas limits.
Certification
To the best of my knowledge, the information reported and statements made on this data submittal and attachments are true and correct.
Furthermore, I have attached complete notification of any sampling values meeting or exceeding groundwater standards or explosive gas
levels, and a preliminary analysis of the cause and significance of concentrations exceeding groundwater standards. I am aware that there
are significant penalties for making any false statement, representation, or certification including the possibility of a fine and imprisonment.
Affix NC Licensed/ Professional Geologist Seal
Revised 6/2009
Date
Facility Representative Address
NC PE Firm License Number (if applicable effective May 1, 2009