7601_RandolphCountyMSWLF_LFGRem_26307_20160429

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LANDFILL GAS REMEDIATION
PLAN
Closed Randolph County Municipal Solid Waste
Landfill, Permit No. 76-01
Randolph County, North Carolina

Submitted To:

Randolph County Public Works P.O. Box 4728
Asheboro, NC 27204

Submitted By: Golder Associates NC, Inc.
5B Oak Branch Drive Greensboro, NC 27407

April 2016 0739-612715.400
PL
A
N

April 2016 i 0739-612715.400

randolph co lf lfg remediation plan.docx
Table of Contents
COVER LETTER
1.0 INTRODUCTION ............................................................................................................................... 1
2.0 SITE INTRODUCTION AND BACKGROUND .................................................................................. 1
3.0 REMEDIATION STRATEGY ............................................................................................................. 2
3.1 Evaluation of Methane Monitoring Wells ....................................................................................... 2
3.2 Modification of Methane Monitoring Network ................................................................................ 3
3.3 Venting LFG Extraction Wells ....................................................................................................... 4
4.0 SUMMARY ........................................................................................................................................ 4
List of Tables
Table 1 Summary of Methane Monitoring Events
List of Figures
Figure 1 Summary of Methane Monitoring Results
List of Drawings
Drawing 1 Proposed Methane Monitoring Plan
Drawing 2 Site Map
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1.0 INTRODUCTION
This Landfill Gas (LFG) Remediation Plan has been prepared by Golder Associates NC, Inc. (Golder) for
the Closed Randolph County Municipal Solid Waste (MSW) Landfill in Randleman, North Carolina in
accordance with Title 15A of the North Carolina Administrative Code (NCAC) Subchapter 13B.1626 (4)(c).
The Randolph County Landfill is maintained by the County and Waste Management of Carolinas, Inc.
(Waste Management) under Permit No. 76-01 issued by the North Carolina Department of Environmental
Quality (NC DEQ).
This LFG Remediation Plan has been prepared in response to detections of methane at concentrations
above the lower explosive limit (LEL) at compliance methane monitoring well GM-5 during the first and
second quarterly methane monitoring events of 2016, performed on February 29, 2016, and April 5, 2016,
respectively. NC DEQ was notified of the exceedences by letter on March 7, 2016, and April 11, 2016.
This LFG Remediation Plan describes the steps to protect human health and the environment, and reduce
LFG migration.
2.0 SITE INTRODUCTION AND BACKGROUND
The location of the facility is shown on the inlay on Drawing 1. As presented, the Randolph County Landfill
is located approximately 3 miles northeast of the City of Asheboro, near the town of Central Falls in
Randolph County, NC, off County Land Road. Randolph County operated a sanitary landfill from 1973 to
1985, and a second sanitary landfill for MSW, construction and demolition (C&D) debris, and land clearing
and inert debris (LCID) from 1985 to December 31, 1997. The total facility comprises approximately
600 acres, about half of which contain waste or are associated with activities for the active solid waste
transfer station, currently operated by Waste Management. The transfer station was built before final landfill
closure in 1997, and remains in operation. Because the landfill operated past October 9, 1993, the landfill
is subject to Title 15A NCAC 13B.1630 37 of the NC Solid Waste Management Regulations (SWMR).
As shown on Drawing 1, the landfill is accessible by County Land Road to the southwest. The landfill is
bounded to the north by the Deep River and to the west, south, and east by residential and undeveloped
wooded properties. Topographic relief at the landfill ranges from approximately 580 to 725 feet above
mean sea level. Surface drainage from the facility is toward a perennial stream to the west and a valley to
the east. Both of these features drain into the Deep River to the northeast of the landfill (H&S, 1994).
Randolph County (the County) currently monitors methane on a quarterly schedule at five methane
monitoring wells (GM-1, GM-2, GM-3, GM-4, and GM-5) around the MSW landfill. Additionally, the County
monitors a maintenance building on County property in close proximity to the closed MSW landfill.
Additionally, there are 15 passive gas vents installed in the waste unit of the closed MSW landfill.
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3.0 REMEDIATION STRATEGY
Immediately after confirming the initial LEL exceedance from GM-5, steps were taken to ensure human
health and safety. A continuous methane monitoring device was installed in the maintenance building,
which is located approximately 160 feet from GM-5. “No Smoking” signs were installed in the vicinity of
GM-5, and County employees were given proper safety training for working in the vicinity of GM-5. As part
of the remedial strategy, an evaluation of the current methane monitoring network and LFG passive venting
system was conducted, and a plan of action was developed. Each of these activities is described in the
sections below.
3.1 Evaluation of Methane Monitoring Wells
An evaluation of the current methane monitoring network was conducted to determine if the existing
methane monitoring wells are adequately located to be protective of human health and the environment,
and to detect methane migration. A summary of methane monitoring results since the third quarter of 2012
is provided in Table 1 and graphically in Figure 1.
It was determined that three of the facility’s five methane monitoring wells (GM-1, GM-3, and GM-4) are
located within 20 feet or less from the limits of waste. Of these three wells, GM-1 and GM-3 regularly have
detections of methane approaching the LEL. Well GM-2 is located approximately 160 feet from waste and
has not had any recorded measurements of methane historically. Well GM-5 is located approximately
120 feet from waste and has only had sporadic detections of methane at concentrations well below the LEL
until the first quarterly methane monitoring event of 2016.
Title 15A NCAC 13B.1626 (4)(a)(ii) states that all MSW landfill units must ensure that the concentration of
methane does not exceed the LEL at the facility property boundary. The Closed Randolph County Landfill’s
methane monitoring wells are located in close proximity to the waste unit and at some distance from the
facility property boundary. Drawing 2 shows the location of the monitoring points in relation to the waste
unit and property boundary. Well GM-1 is located the closest to the facility boundary. Located less than
20 feet from the waste unit, GM-1 is located approximately 140 feet from the facility boundary. The facility
boundary in this area approximately follows a stream channel. The adjacent property is owned by the
County.
Well GM-2 is located approximately 160 feet from the waste unit and 180 feet from the property boundary.
The property boundary is located at the Deep River. Well GM-3 is located less than 20 feet from the waste
unit, and is approximately 650 feet from the facility boundary, which is the Deep River. Well GM-4 is also
less than 20 feet from the waste unit, and is located approximately 1,200 feet from the closest facility
boundary. Both GM-3 and GM-4 are located less than 100 feet from a tributary of the Deep River that
separates the waste unit from the facility boundary. Well GM-5 is located approximately 120 feet from the
waste unit, and approximately 750 feet from the closest facility boundary. The adjacent property is owned
by the County.
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As described above, all of the methane monitoring wells are located significantly closer to the waste unit
than to the facility boundary. Further, most of the monitoring wells are separated from adjacent properties
by streams or the Deep River, which serve as barriers to subsurface LFG migration. Lastly, two of the wells
are located along the eastern facility boundary, which is adjacent to additional property owned by the County
(currently permitted for a new disposal facility). Based on the above information, methane exceedances in
any of the facility’s methane monitoring wells do not indicate that methane has migrated to or past the
facility boundary.
3.2 Modification of Methane Monitoring Network
As stated in Section 3.1, three of the facility’s methane monitoring wells are located less than 20 feet from
the waste unit and all of the methane monitoring wells are located closer to the waste unit than to the facility
boundary. Therefore, the County requests that the NC DEQ allow the compliance methane monitoring
network to be revised. Methane monitoring wells GM-1, GM-3, GM-4, and GM-5 are proposed to be
replaced with bar-hole probes BH-1, BH-3, BH-4, and BH-5, respectively. The locations of the bar-hole
probes can be seen on Drawings 1 and 2. Each of these bar-hole probe locations will be placed further
from the waste unit than the methane monitoring wells. Bar-hole probe location BH-1 will be located close
to the facility boundary. Bar-hole probes BH-3 and BH-4 will be located closer to a stream that separates
the waste unit from the rest of the facility. The probes are not proposed to be installed closer to the western
facility boundary because the monitoring results could be impacted from pre-regulatory waste units.
Probe BH-5 will be located closer to the maintenance building. Though this probe is not located near the
facility boundary, its placement is to detect methane migration toward the maintenance building. The
maintenance building will continue to use a continuous explosive gas monitor inside the building, and will
continue to be monitored during routine quarterly methane monitoring events. Methane monitoring well
GM-2 will continue to be monitored as part of the compliance network because the well is located at a
sufficient distance from the waste unit.
Methane will be measured at the bar-hole probe locations utilizing the following technique. Gas monitoring
with bar-hole probes will consist of punching a hole with a 2-foot probe. Open-ended tubing should be
placed at the mid-point of the hole, taking care not to plug the bottom of the tubing with soil. An explosive
gas meter will be allowed to purge the hole for a minimum of 2 minutes, and the peak and the stabilized
reading shall be recorded. Subsequent testing shall be conducted in close proximity to the original location;
therefore, the bar-hole locations will be marked in the field.
Methane monitoring wells GM-1, GM-3, GM-4, and GM-5 will continue to be monitored quarterly as
assessment methane monitoring wells, but will not be considered points of compliance. The methodology
for monitoring the wells will be revised as discussed in Section 3.3.
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3.3 Venting LFG Extraction Wells
In order to reduce LFG migration in the area of GM-5, the County will replace the ‘candy cane’ gas vent
completions with turbine vents for the three LFG vents located the closest to GM-5. The location of the
converted gas vents is shown on Drawing 1. A turbine vent will also be placed on GM-5. This modification
will increase the efficiency of each LFG vent to passively vent and prevent the buildup of LFG in the waste
unit, which could increase the migration of LFG. Allowing GM-5 to passively vent will reduce the likelihood
of methane migration towards the maintenance building.
Turbine vents will also be installed on LFG monitoring wells GM-1, GM-3, and GM-4. Each of these wells
is installed within 20 feet of the waste unit. Methane has been detected in GM-1 and GM-3 at
concentrations below the LEL during previous quarterly monitoring events. Allowing GM-1, GM-3, and
GM-4 to passively vent will reduce the potential of methane migration away from the waste unit.
As discussed in Section 3.2, LFG monitoring wells GM-1, GM-3, GM-4, and GM-5 will no longer be part of
the LFG compliance network, but will continue to be monitored as LFG assessment monitoring wells.
Because of the installation of the turbine vents, the procedure for monitoring these wells will be modified.
Upon arrival at the site to perform quarterly methane monitoring, plastic bags will be placed over the turbine
vents and sealed at the standpipe with tape. Each well will remain covered for at least 1 hour before being
monitored. To monitor each of these wells, a small incision will be made in the plastic bag. Tubing will be
inserted through the incision and directed through the turbine vent and into the well standpipe. The
explosive gas meter will be allowed to purge the well for a minimum of 2 minutes. Peak and stabilized
methane readings will be recorded. After monitoring, the plastic bag will be removed to allow continued
operation of the turbine vents.
4.0 SUMMARY
This LFG Remediation Plan has been prepared in response to detections of methane at concentrations
above the LEL in compliance monitoring well GM-5 during the first and second quarterly methane
monitoring events of 2016. Immediately after confirming the initial LEL exceedance from GM-5, steps were
taken to ensure human health and safety. A continuous methane monitoring device was installed in the
maintenance building. “No Smoking” signs were installed in the vicinity of GM-5, and County employees
were given proper safety training for working in the vicinity of GM-5.
Based on an evaluation of the current methane monitoring network and LFG passive venting system, the
following remediation plan is proposed. The LFG remediation strategy consists of three activities:
 Modify the compliance monitoring network because most of the current LFG monitoring wells are
too close to the waste unit
 Replace ‘candy cane’ LFG vent completions with turbine vents for the three vents closest to GM-5
 Add turbine vents to four of the LFG monitoring wells and re-purpose them as assessment
monitoring points
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These activities will ensure continued protection of human health and safety, and provide methane data
representative of conditions near the facility property boundary, in accordance with Title 15A NCAC
13B.1630 37 of the NC SWMR.

TABLE

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\\greensboro\DATA\Projects\Randolph County\Methane\2016 LFG Remediation Plan\Randolph Methane Summary.xlsx
GW-1 GM-2 GM-3 GM-4 GM-5
Maintenance
Building
09/26/12 0.1 0.0 0.6 0.0 0.0 0.0
10/22/12 0.3 0.0 1.6 0.0 0.1 0.0
01/08/13 0.2 0.0 0.9 0.0 0.0 0.0
04/09/13 4.2 0.0 4.1 0.0 0.0 0.0
06/18/13 3.8 0.0 2.6 0.0 0.6 0.0
10/08/13 0.3 0.0 2.1 0.0 0.0 0.0
01/17/14 4.9 0.0 1.6 0.0 0.0 0.0
04/22/14 1.0 0.0 0.8 0.0 1.3 0.0
08/26/14 0.0 0.0 0.6 0.0 0.0 0.0
10/08/14 0.0 0.0 3.2 0.0 0.1 0.0
03/09/15 4.7 0.0 1.1 0.0 0.5 0.0
05/26/15 0.4 0.0 0.3 0.0 0.7 0.0
07/08/15 0.0 0.0 0.5 0.0 0.0 0.0
11/17/15 3.8 0.0 0.8 0.0 0.0 0.0
02/29/16 0.0 0.0 0.2 0.0 6.8 0.0
04/05/15 0.0 0.0 0.4 0.0 5.8 0.0
Notes:
1. Methane is measured in percent methane
2. Bold values exceed the lower explosive limit of 5 percent methane
TABLE 1
SUMMARY OF METHANE MONITORING EVENTS
CLOSED RANDOLPH COUNTY LANDFILL, PERMIT NO. 76-01

FIGURE

Figure
1

Title:
SUMMARY OF METHANE MONITORING RESULTS Closed Randolph County Landfill
Permit No. 76-01 Reviewed By: RPK
Prepared By: DYR
Project# 0739612715
DATE: 04/25/16

DRAWINGS

Caption Text Caption Text Caption Text
SITE LOCATION
CONSULTANT
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RANDOLPH COUNTY LANDFILL
PERMIT NO.76-01
RANDOLPH COUNTY
PROPOSED METHANE MONITORING PLAN
0
FEET
120 240
SCALE
EXISTING 10 FT GROUND SURFACE CONTOUR
EXISTING 2 FT GROUND SURFACE CONTOUR
APPROXIMATE LIMITS OF WASTE
EXISTING ROAD
MONITORING WELL AND IDENTIFICATION
SURFACE WATER MONITORING POINT
COMPLIANCE LANDFILL GAS MONITORING PROBE
ASSESSMENT LANDFILL GAS MONITORING PROBE WITH
TURBINE VENT
LANDFILL GAS VENT
LANDFILL GAS VENT WITH TURBINE VENT
LANDFILL GAS BAR-HOLE MONITORING PROBE
LEGEND
NOTES
SITE LOCATION MAP
NOT TO SCALE
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PHASE
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DRAWING
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2016-04-21
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1. BASE MAP PROVIDED BY HAZEN AND SAWYER, INC. OVERALL GROUND SURFACE
TOPOGRAPHY OBTAINED FROM AERIAL SURVEY CONDUCTED BY KUCERA
INTERNATIONAL INC., WILLOUGHBY, OHIO ON 8/2/93.
2. COORDINATE SYSTEM IS N.C. STATE PLANE GRID.
3. AERIAL PHOTO IS FROM GOOGLE EARTH ON 2-12-2012.
NOTE(S)
LEGEND
APPROXIMATE PROPERTY BOUNDARY
ADJACENT COUNTY OWNED PROPERTY
COMPLIANCE MONITORING WELL
NON-COMPLIANCE MONITORING WELL
SURFACE WATER MONITORING LOCATION
APPROXIMATE LIMITS OF WASTE
RANDOLPH COUNTY LANDFILL
PERMIT NO.76-01
RANDOLPH COUNTY
SITE MAP
COMPLIANCE LANDFILL GAS MONITORING PROBE
ASSESSMENT LANDFILL GAS MONITORING PROBE WITH TURBINE VENT
LANDFILL GAS BAR-HOLE MONITORING PROBE

Golder Associates NC, Inc.
5B Oak Branch Drive
Greensboro, NC 27407 USA
[phone] - Phone
[phone] - Fax