7606_GoldHillRoadCDLF_LFG_MonitoringPlan_DIN26686_2016

Gold Hill Road CDLF (Permit 76-06)
Landfill Gas Monitoring Plan
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Landfill Gas Monitoring Plan
Gold Hill Road C&D Landfill
Solid Waste Permit 7606-CDLF-2001

Submitted to:
NCDEQ Division of Waste Management
Solid Waste Section
217 W Jones Street
Raleigh, NC 27603

Presented To:
Morton and Sewell Land Company, LLC
385 Gold Hill Road
Asheboro, North Carolina 27203

Presented By:

SCS ENGINEERS
322 Chapanoke Road, Suite 101
Raleigh, NC 27603
[phone]

March 1, 2016
File No. 02214705.00
Gold Hill Road CDLF (Permit 76-06)
Landfill Gas Monitoring Plan
i 

Table of Contents

Section Page

1.0 INTRODUCTION ........................................................................................................ 2 
1.1 Background Information ...................................................................................... 2 
1.2 Current Site Conditions ........................................................................................ 3 
1.3 Regulatory Requirements .................................................................................... 3 
1.4 Rationale for LFG Sampling Locations .................................................................. 4 
2.0 LFG MONITORING .................................................................................................... 4 
2.1 Locations and Logistics ......................................................................................... 4 
2.2 Structures and Ambient Sampling ....................................................................... 5 
2.3 Sampling Schedule ............................................................................................... 5 
3.0 LFG SAMPLING PROGRAM ....................................................................................... 6 
3.1 Equipment and Calibration .................................................................................. 6 
3.2 LFG Sampling Procedures ..................................................................................... 6 
4.0 RECORD KEEPING AND REPORTING ......................................................................... 7 
5.0 CONTINGENCY PLAN ................................................................................................ 8 
6.0 PROFESSIONAL CERTIFICATION ............................................................................... 9 

Attachments
1 Drawing M1 Monitoring Locations
2 LFG Monitoring Well Schematic
3 LFG Monitoring Form

Gold Hill Road CDLF (Permit 76-06)
Landfill Gas Monitoring Plan
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1.0 INTRODUCTION
The following plan has been prepared as a standalone document in accordance with
current NCDENR Solid Waste Section (SWS) guidance, pertaining to methane and
hydrogen sulfide (H2S) monitoring. The monitoring locations, methods, and thresholds
for action have not changed, but the 2010 guidance document requires that attention be
given specifically to well construction, equipment calibration, sampling procedures, and
data keeping, in a plan that is organized in a standardized format. Landfill staff and
monitoring personnel should view the SWS document “Landfill Gas Monitoring
Guidance,” November 2010, available online at:
http://portal.ncdenr.org/c/document_library/get_file?uuid=da699f7e-8c13-4249-9012-
16af8aefdc7b&groupId=38361.

1.1 Background Information
Monitoring of landfill gas (LFG) is required at C&D landfills by Solid Waste Rule 15A
NCAC 13B .0544. Landfill gas is a by-product from the decomposition of organic waste
in a sanitary landfill, including certain C&D wastes. Landfill gas typically comprises
about 50 percent methane, which can be explosive under certain conditions, as well as
carbon dioxide, nitrogen, water, and small amounts of hydrogen sulfide. LFG has been
known to promote the migration of contaminants into ground water. The Solid Waste
Rules typically focus on the explosive properties from a public safety standpoint.
Landfill gas migrates in soil above the ground water table and is restricted laterally by
streams. Highly porous soils that tend to occur near the soil-rock interface within the
Piedmont are considered to be a good pathway for gas migration.

Past experience suggests that up-gradient areas should be targeted for monitoring,
especially if porous soils are present. In addition, this zone typically is an aquifer, thus
fluctuations in the water table will affect the gas migration pattern or rate, as does surface
saturation, frozen soils, and variation in barometric pressure. The Guidance suggests that
the ideal time to sample for subsurface gas is during times of low barometric pressure.
Pipelines and other utility trenches can serve as pathways for gas migration, with the
potential to convey gas for considerable distances. Open landfills are not as likely to
experience subsurface gas migration, but once a low permeability cover is installed,
lateral migration into adjacent soils may be more likely if gas is present.

Gold Hill Road CDLF (Permit 76-06)
Landfill Gas Monitoring Plan
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1.2 Current Site Conditions
The subject landfill occupies the west side of a broad, north-south oriented ridge. Site
elevations vary from approximately El. 850 on a rocky knoll located near the facility
entrance to El. 740 along the banks of Penwood Branch. The property is bound to the
east by Gold Hill Road, to the south by Presnell Avenue, to the west by Penwood Branch,
to the north by undeveloped property, separated from the active disposal area by a deep
ravine containing a seasonal stream. Topographic relief near the streams is moderately
steep to very steep, with elevation changes from the footprint to the streams on the order
of 10 feet on the west side.

Ground water contours reflect the surface topography, which slopes moderately but
steadily to the west. Within the mid- to upper elevations, groundwater occurs at a depth
of approximately 15 - 25 feet beneath the surface. In the lower elevations, west of the
CDLF footprint, groundwater levels are approximately 5 – 10 feet beneath the surface.
The landfill is unlined and is mostly excavated below the original surface to the approved
base grades, except along the narrow floodplain of Penwood Branch, where embankment
heights of approximately 4 to 8 feet exist. Onsite soils are mostly clayey silt, weathered
in-situ from meta-volcanic bedrock. These soils are porous but exhibit low permeability.

The approved base grades are a minimum of 14 feet above the level of the streams and a
minimum of 4 feet above groundwater and/or bedrock. Lateral separation is 200 feet
minimum to the property lines and 50 feet minimum to the streams. Site conditions are
restrictive to offsite gas migration in all directions except the east. On the up-gradient
(east) side the topography increases approximately 20 feet between the approved
footprint and the nearest occupied structure, i.e., the scale house. The nearest dwellings
are located approximately 975 feet from the approved disposal footprint to the northeast
and 775 feet to the east. No deep utility trenches or pipelines are known in the vicinity.
No occupied structures appear to be at risk for gas migration near this facility.

1.3 Regulatory Requirements
Thresholds that trigger responsive action are methane levels of 100 percent of the LEL,
(the lower explosive limit, about 5 percent by volume) in soil-gas or air at the facility
boundary; 25 percent of the LEL within onsite structures, not limited to just buildings but
inclusive of drainage structures and utility vaults; zero in off-site structures. Solid Waste
Section guidance requires that LFG be monitored with a calibrated meter that is capable
of detecting hydrogen sulfide, whereas the action limits are 4% by volume at 100% LEL
and 1% by volume at 25% LEL.
Gold Hill Road CDLF (Permit 76-06)
Landfill Gas Monitoring Plan
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1.4 Rationale for LFG Sampling Locations
Six soil-gas monitoring points are located around the footprint at locations approved
during earlier permitting (see Drawing M1). Points LFG-1, LFG-2 and LFG-6 are
located on the up gradient side of the unlined landfill, opposite of ground water flow.
Points LFG-3 through LFG-5 are located downgradient, albeit the topography of these
locations and the water table make it unlikely that landfill gas would migrate in those
directions (at least not very far). A future point, LFG-7 is located to provide uniform
spacing in the upgradient direction, with the unlikelihood of any soil-gas migrating more
than a few 10’s of feet from the landfill perimeter. The new sampling point will be
situated within 50 feet of the waste boundary, as are the other sampling locations.
2.0 LFG MONITORING
2.1 Locations and Logistics
LFG monitoring for this facility currently consists of sampling soil-gas adjacent to the
landfill footprint via bar-hole punch test locations spaced approximately 500 foot apart
(see Drawing M1 in Attachment 1). The locations reflect the emphasis on the up
gradient side to the east, which is the only likely direction for offsite gas migration. The
LFG monitoring points are situated between the footprint and the nearest areas accessible
by the public, i.e., the scale house and the public streets, where the migration of gas (if
present) could travel off-site via shallow utility trenches and/or bedrock fractures.

The facility management’s intention is to implement the new monitoring point to the
southwest of future Phase 1B once that phase is built.

The bar-hole punch test was prescribed and approved for the facility ca. 2012, whereas
the waste is comprised of mostly inert materials and landfill gas migration potential is
limited by topography and natural barriers. The waste stream does contain paper, wood,
and other potentially combustible materials – the same kind of materials that can degrade
slowly to form landfill gas – along with sheetrock which can degrade to produce
hydrogen sulfide, so depending on future data trends, it is conceivable that at some future
time the Solid Waste Section may require permanent gas monitoring wells for this facility
(see Attachment 2). Due to the age of the waste, it is likely that reactions leading to the
production of landfill gas are becoming more active.

In anticipation of possible future requirements, this plan presents procedures for both bar-
hole punch tests and sampling of monitoring wells. A SWS-endorsed well construction
schematic is provided, which includes sealed construction and a specialized port at the
Gold Hill Road CDLF (Permit 76-06)
Landfill Gas Monitoring Plan
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top to facilitate sampling. Presumably, the monitoring wells would be located near the
same points as currently monitored with the bar-hole punch test, for the same reasoning
described above. This plan will be amended in the future to include data tables for the
LFG monitoring wells, if required. Data recording protocols will remain the same.
Landfill gas monitoring will be performed quarterly during the active life of the landfill,
estimated at 20 years, and throughout the post-closure care period, 30 years unless future
data warrant a schedule revision, which will be subject to approval by the SWS.

2.2 Structures and Ambient Sampling
Within the offices and any future buildings on-site, atmospheric sampling for methane
shall be conducted. Methane is heavier than air and tends to accumulate in the lower
zones with restricted circulations, i.e., crawlspaces, closets, and corners of rooms near the
floor, cracks in walls, floor slabs, or foundations, crawlspace vents, drainage pipes, and
utility vaults (excluding sanitary sewer manholes). Methane detection in and around the
structures, though unlikely, would signify a problem such that the site manager should be
notified – immediate action may be required – refer to the Contingency Plan (Section 5).

Ambient monitoring overlaps the building foundations and includes a “walk-around” at
the toe of covered (vegetated) slopes to survey for gas that may be seeping through the
cover. A key to potential side slope seepage includes stained soil, wetness with visible
bubbling, or distressed (or absent) vegetation. Any detection of methane in the ambient
monitoring should be noted on a site map and a special notation recorded in the
monitoring report. Follow up sampling or close attention in future sampling events might
be warranted. The site manager should be alerted to any ambient gas detection.

2.3 Sampling Schedule
Quarterly methane and hydrogen sulfide monitoring will be conducted at all subsurface
gas detection locations and in all occupied structures located on the landfill property. In
addition, enclosed structures, such as manholes, utility vaults, and buried drainage pipes
should be checked for gas prior to servicing, in addition to the routine monitoring. The
passive gas vents for the final cover, when installed, are not required to be monitored.

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. LFG monitoring should be conducted when the barometric pressure is
low and avoiding times when soils are saturated or when the ground is frozen or covered
with ice or snow.
Gold Hill Road CDLF (Permit 76-06)
Landfill Gas Monitoring Plan
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3.0 LFG SAMPLING PROGRAM
3.1 Equipment and Calibration
The Facility enlists the services of an experienced third-party firm to conduct the
monitoring. That firm utilizes a landfill gas instrument that meets the requirements of
SWS Landfill Gas Monitoring Guidance with respect to detecting methane, oxygen,
carbon dioxide, and hydrogen sulfide. Calibration shall occur prior to instrument use and
according to the manufacturer’s specifications. Should this element of the program
change, this plan will be amended accordingly.

3.2 LFG Sampling Procedures
The following procedure is recommended for conducting landfill gas monitoring well
sampling and/or bar-hole punch testing (shown in italics). The sampling equipment shall
consist of a good-quality gas meter capable of detecting methane (LEL) and oxygen
levels – most modern meters include carbon monoxide or carbon dioxide, depending on
the meter and hydrogen sulfide readings. In deference to the professionals who have
conducted the sampling for years, these procedures are guidelines; no changes to the
current sampling program are warranted.

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 2 Drive the bar into the ground to a depth of 3 feet at the sampling location
Alternate using a hammer or backhoe bucket. Heavy gauge rebar is ideal for this
task. The bar-hole needs to be near-vertical and free of obstructions.
Drilling a hole with a modified concrete drill (an extension is required to
reach the desired depth) has been demonstrated to expedite the making of a
boring with less smearing of the side walls.
Gold Hill Road CDLF (Permit 76-06)
Landfill Gas Monitoring Plan
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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 3 Cover the hole upon extraction of the drill to retain any gas present.
Alternate Without completely lifting the cover, gently insert the sampling tube beneath
the cover and obtain an initial reading. Allow time for a stabilized reading
as described above.

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 5 Backfill the hole with cuttings or native soil; tamp the backfill with a rod or
Alternate equipment handle.

Step 6 Proceed to the next landfill gas monitoring well and repeat Steps 2 – 5.

4.0 RECORD KEEPING AND REPORTING
The sampling technician shall record the date, time, location, sampling personnel,
calibration data, gas pump rate, barometric pressure (from local weather reports), ambient
temperature, general weather conditions at the time of sampling, initial and stabilized
concentrations of methane and H2S (see the Landfill Gas Monitoring Data Form in
Attachment 3). These records shall be left in the landfill office upon completion and
maintained as part of the operating record. Should methane be detected at any sampling
location, the facility manager should be notified and, depending on the concentrations, a
report to the Solid Waste Section might be warranted. In any event a qualified engineer
should be consulted.
Gold Hill Road CDLF (Permit 76-06)
Landfill Gas Monitoring Plan
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5.0 CONTINGENCY PLAN
Solid Waste Rule .0544 (d) (3) requires the following responses in the event that methane
and/or hydrogen sulfide concentrations are detected that exceed the regulatory limits:

A Immediately take all steps necessary to ensure protection of human
health and notify the Division – at a minimum, occupied structures
should be evacuated and ventilated until the methane concentrations
subside; close monitoring of structures shall be implemented; for
facility boundary violations, further evaluation is warranted, subject to
notification and approval by 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;

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.

D Based on the need for an extension demonstrated by the operator, the
Division may establish alternative schedules for demonstrating
compliance with the limits.

E "Lower explosive limit" means the lowest percent by volume of a
mixture of explosive gases in air that will propagate a flame at 25o C at
atmospheric pressure.

F Upon completion of mitigation activities, a thorough report shall be
placed in the operating record to document the incident and outcome.

Gold Hill Road CDLF (Permit 76-06)
Landfill Gas Monitoring Plan
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6.0 PROFESSIONAL CERTIFICATION
The certification statement below must be signed and sealed by a North Carolina
Professional Geologist or Professional Engineer and submitted with the Landfill Gas
Monitoring Plan.

The landfill gas monitoring plan for this facility has been prepared by a qualified
geologist or engineer 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 ___G. David Garrett, PG, PE_______

Date _____March 1, 2016_____________

Not valid unless this document bears the seal of the above mentioned licensed professional.

If wells are installed in the future, the well locations shall be shown on a topographic
map that is signed and sealed by a registered surveyor.
ATTACHMENT 1
MONITORING LOCATION MAP

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ATTACHMENT 2
LFG MONITORING WELL SCHEMATIC

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Figure 1 – Landfill Gas Monitoring Well Detail 
ATTACHMENT 3
LFG MONITORING FORM

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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:
Date of Sampling: NC Landfill Rule (.0500 or .1600):
Name and Position of Sample Collector:
Type and Serial Number of Gas Meter: Calibration Date of Gas Meter:
Date and Time of Field Calibration:
Type of Field Calibration Gas (15/15 or 35/50): Expiration Date of Field Calibration Gas Canister:
Pump Rate of Gas Meter:
Ambient Air Temperature: Barometric Pressure: General Weather Conditions:
Instructions: Under “Location or LFG Well” identify the monitoring wells or describe the location for other tests (e.g., inside
buildings). A drawing showing the location of test must be attached. Report methane readings as both % LEL and % CH4 by
volume. A reading in percent methane by volume can be converted to % LEL as follows: % methane by volume = % LEL/20

Location
or LFG
Well ID
Sample
Tube
Purge
Time
Time
Pumped
(sec)
Initial
%LEL
Stabilized
%LEL
%CH4 by
volume %O2 %CO2 %H2S Notes

If your facility has more gas monitoring locations than there is room on this form, please attach additional sheets listing the
same information as contained on this form.
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