3404_TownofKernersville_MSWLF_LFGCAP_DIN28706_20171204

WithersRavenel
Our People. Your Success.

7011 Albert Pick Road, Suite G | Greensboro, NC 27409
t: 336.605.3009 | f: 919.467.6008 | www.withersravenel.com | License No. C-0832
Cary | Greensboro | Pittsboro | Raleigh | Wilmington

Delivered via Email - [e-mail]

December 4, 2017

Ms. Jaclynne Drummond, Compliance Hydrogeologist
NCDEQ-Asheville Regional Office
Solid Waste Section, Division of Waste Management
2090 US Highway 70
Swannanoa, NC 28778

RE: Landfill Gas Corrective Action Plan Addendum
Closed Town of Kernersville MSW Landfill
Forsyth County, NC
Solid Waste Permit #: 3404-MSWLF-1985
Reference Document: DIN 28379
Dear Ms. Drummond:
WithersRavenel (WR), on behalf of the Town of Kernersville (Town), is pleased to submit this Landfill Gas
Corrective Action Plan Addendum (CAP Addendum) for the Closed Town of Kernersville MSW Landfill (Permit
# 34-04) located in Forsyth County, NC. This CAP Addendum has been prepared in response to your letter
titled Landfill Gas Exceedances, dated August 4, 2017 (DIN 28379).
In the referenced letter, you indicated that methane gas exceedances continue to be reported at the landfill
property northern boundary, and that the Town “… is required to prevent the migration of methane gas at the
property boundary to ensure the protection of public health.” Additionally, you requested the Town submit
a Landfill Gas Corrective Action Plan Addendum to supplement the approved September 2013 Landfill Gas
Corrective Action Plan.
In 2013, Joyce Engineering (Joyce), serving as the Town’s Landfill Environmental Consultant at that time,
prepared and implemented the referenced Corrective Action Plan and installed three passive gas vents along
the northern limits of the landfill waste boundary. Afterwards, they continued to monitor landfill gas
migration around the landfill. Since July 2016, WR has been serving as the Town’s Landfill Environmental
Consultant and has continued the monthly monitoring activities.
WR has been in communication with Town representatives and, in response to your request, proposes to
install two additional passive landfill gas vents (vents) at locations illustrated on the attached Figure 1. To
resemble the existing vents (previously installed by Joyce), WR proposes to install the vents to approximately
25-30 feet below the ground surface (BGS) based on the actual depth of waste encountered at the boring
location(s). Soil borings will be advanced using a 30-inch diameter auger. Soil encountered above the waste
will be stockpiled adjacent to the borehole(s) for later re-use. Waste removed during boring excavation will
be staged on secured plastic and transported to the Waste Transfer Facility currently accepting the Town’s
waste.
The gas vents will be constructed with approximately 20 feet of 6-inch diameter PVC slotted screen with
sufficient PVC riser to extend the vent approximately four feet above the ground surface at each location.
The annular space (between the boring wall and PVC wall) will be backfilled with #57 washed aggregate up to
approximately two feet above the screen. An approximate 2-foot section of bentonite pellets will be
tremmied into the annular space and hydrated. Once the bentonite appears to have “set” substantially, the
remaining annulus will be backfilled with soil excavated from the boring. The vent pipe will be finished with
WithersRavenel
Our People. Your Success.

Landfill Gas Corrective Action Plan Addendum WR Project # 06140180.19
Closed Town of Kernersville Landfill (Permit # 34-04) December 4, 2017

Page 2 of 2

two 90° elbows and excess soil will be spread around the vent pipe surface to offset future settlement. A
typical view of the proposed vent is illustrated on Figure 1.
This activity is currently not included in this year’s budget. However, if approved, the Town will begin
installation in 2018 once the additional costs are authorized by the Town Council. In the meantime, monthly
landfill gas monitoring will continue at the site.
WithersRavenel appreciates the opportunity to submit this Landfill Gas Corrective Action Plan Addendum on
behalf of the Town of Kernersville. We look forward to a positive response and Authorization to Proceed.
Sincerely
WithersRavenel

Mark Brown, LG, PG, RSM
Senior Geologist

Attachment
Figure 1 Proposed Passive Vent Locations and Detail