6301_Moore_MSWLF_CA_LFG_Trench_FID1261905_20181220

G GOLDER
December 18, 2018
Ms. Jaclynne Drummond, Compliance Hydrogeologist
North Carolina Department of Environmental Quality
Division of Waste Management - Solid Waste Section
2090 US Highway 70
Swannanoa, NC 28778
[phone]
Project No. 0739615017.503
LANDFILL GAS CUT-OFF RENCH INSTALLATION REPORT — CLOSED MOORE COUNTY MSW LANDFILL,
PERMIT NO. 6301-MSWLF-1979 — MOORE COUNTY, NORTH CAROLINA
Dear Jackie:
On behalf of Moore County, Golder Associates NC, Inc. (Golder) is pleased to submit this notification of
completion of a landfill gas cut-off trench at the closed Moore County MSW Landfill. The cut-off trench was
proposed in the Landfill Gas Remediation Plan dated January 31, 2018, in response to lower explosive limit (LEL)
exceedances in groundwater monitoring well MW-15. The Landfill Gas Remediation Plan (LGRP) was approved
by the North Carolina (NC) Department of Environmental Quality (DEQ) in a letter dated February 13, 2018.
Based on the DEQ approval letter, the installation of the trench was to be completed by September 15, 2018.
Moore County requested an extension for trench completion until December 31, 2018, and that extension was
granted by NC DEQ in a letter dated September 13, 2018.
Construction of the landfill gas cut-off trench began on October 10, 2018 and was completed on November 1,
2018. The contractor constructed the trench in general conformance with Drawings 2 and 3 of the LFRP. One
notable exception to the proposed specifications was that a geocomposite gas venting curtain was substituted for
gravel backfill due to trench widening to accommodate sandy soil conditions. Based on layout adjustments and
observations made in the field by Golder, the trench was excavated to a length of approximately 150 feet and a
depth of approximately 28 feet in the area between methane monitoring well MW-15 and the waste unit. The
back wall of the trench was lined with an impermeable barrier and the trench was backfilled with stone.
Perforated, 4-inch diameter, high density polyethylene (HDPE) pipe was installed approximately 4 feet below
ground surface along the length of the excavation. Solid, 4-inch diameter, HDPE pipe risers were attached to the
perforated pipe 50 feet from each end of the trench and extended to approximately 6 feet above ground surface to
vent intercepted landfill gas. The risers were topped with passive, wind -driven turbine vents. The upper 2 feet of
the excavation was then backfilled with soil removed from the trench. Sample photographs provided by the
contractor that document the installation are attached in Figure 1.
We appreciate your assistance with this project. If you have any questions or concerns, please contact us at 336-
852-4903.
Golder Associates NC, Inc.
5B Oak Branch Drive, Greensboro, North Carolina, USA 27407 T: [phone] F: [phone]
Engineering Lic. No. C-2862/Geology Lic. No. C-399
Golder Associates NC, Inc. is a licensed user of the Golder trademark, and an associated operating entity.
Golder and the G logo are trademarks of Golder Associates Corporation. golder.com

Ms. Jaclynne Drummond, Compliance Hydrogeologist
North Carolina Department of Environmental Quality
Sincerely,
Golder Associates NC, Inc.
Benjamin Draper, PMP Mark A. Taylor, E
Senior Project Geologist Senior Consultant
BD/MAT/mjf:
CC: Randy Gould, PE, Moore County Public Works Director, P.O. Box 1927,
Carthage, North Carolina, 28327
Chad Beane, Moore County Solid Waste Division Manager, P.O. Box 1927,
Carthage, North Carolina, 28327, 910-947-3637
J.W. Baucom, Moore County Landfill Manager, 456 Turning Leaf Way,
Aberdeen, North Carolina, 28315
Rachel Kirkman, PG, Golder Associates NC, Inc.
Attachments: Figure 1 - Photographs of Cut -Off Trench Installation
gAprojects\moore county\_pre-fy18-19\groundwater12018 corrective action\Ifg\cutoff trench installation report\moore mswlf Ifg cut-off rench installation
report - mjf 12-18-18.docx
Project No. 0739615017.503
December 18, 2018
,> GOLDER 2

Path: G:\PROJECTS\Moore County\_Pre-FY18-MG.o d—ter12018 Corrective Action\LFG\Cutoff Trench Installation Report
CLIENT
MOORE COUNTY, NORTH CAROLINA
Cs
CONSULTANT
YYYY-MM-DD
2018-12-17
PREPARED
BSD
GO L D E R
DESIGN
BSD
REVIEW
MAT
APPROVED
MAT
PROJECT
MOORE COUNTY CLOSED MSW LANDFILL
PERMIT NO. 6301-MSWLF-1979
TITLE
PHOTOGRAPHS OF LFG CUT-OFF TRENCH INSTALLATION
PROJECT No. PHASE
0739615017 503
Rev FIGURE
0 FIGURE 1