9204_Wake_Sorrell_MSWLF_LFCoverMaint_FID1636792_20220118

January 17, 2022
Division of Waste Management
217 West Jones Street
Raleigh, North Carolina 27603
Attn: Ms. Jackie Drummond via email: [e-mail]
Reference: Landfill Cover Inspection — December 2021
Sorrell Landfill (Permit #92-04)
Apex, Wake County, North Carolina
S&ME Project No. 1054-07-251
Dear Ms. Drummond:
On December 6, 2021, representatives from S&ME, Inc. (S&ME) performed a visual inspection of the landfill cover
and the storm water/surface water conveyance features at the closed Sorrell Landfill located in Apex, North
Carolina. This letter report is provided to document the findings of our inspection. Services conducted by S&ME
were performed in general accordance with S&ME Proposal No. P4258-07V, dated April 25, 2007, S&ME's
memorandum 2021 Landfill Cover Maintenance Cost Estimate, dated March 18, 2021, and the NCDEQ
memorandum Authorization to Conduct the Spring 2027 and Fall 2027 Landfill Cover Maintenance Activities Closed
Sorrell MSW Landfill, dated March 15, 2021.
BACKGROUND INFORMATION
Sorrell Grading Company initially operated a construction and demolition (C&D) landfill at this site, which
subsequently also accepted municipal solid wastes (MSW) and similar waste materials. A Closure Plan and a Post -
Closure Plan for the landfill were prepared by Stuart Jones Consulting Engineering, dated June 20, 1996 and
submitted to the Section on behalf of Sorrell Grading Company. The Closure Plan provided criteria for the
construction of a landfill cover consisting of a clay cap over the top 24 acres of the landfill and a vegetative layer
of the top and side slopes of the landfill. The Closure Plan indicated that the side slopes were already largely
constructed at that time and that the cap construction was underway.
A Closure Report, dated September 7, 2001, was prepared by S&ME and submitted to the Section on behalf of
Sorrell. The report detailed S&ME's evaluation of the landfill cover after the landfill had been closed and the clay
cap had been placed on top of the landfill. The Closure Report described testing of the cover on the top and the
side slopes of the landfill, verifying the placement and thickness of the infiltration layer and the erosion layer.
Locations on the side slopes and the top of the landfill were tested. Most of the locations were found to contain
adequate thicknesses of cap material. Where the thickness of the cap was insufficient, these locations were
identified, and repairs were to be made by the owner. Additional information on the construction and condition of
the landfill cover system was described in S&ME's letter report Response to Notice of Violations, submitted to
NCDENR-DWM on January 26, 2009.
S&ME, Inc. 13201 Spring Forest Road I Raleigh, NC 276161 p 919.872.2660 1 www.smeinc.com

=0
Landfill Cover Inspection — December 2021
Sorrell Landfill (Permit #92-04)
Apex, Wake County, North Carolina
S&ME Project No. 1054-07-251
The December 6, 2021, landfill cover inspection was limited to an evaluation of one area of compliance:
A visual inspection of the landfill cap over the top 24 acres of the landfill and the storm water/surface
water conveyance features. Cutting and maintenance was performed October 26-28, 2021, by Carolina
Outdoor Services, LLC, subcontractor to S&ME, under a separate task.
S&ME personnel did not inspect the landfill side slopes which are covered by growths of pine trees, hardwoods
and underbrush.
OBSERVATIONS
Overall, the cap and stormwater conveyance features appear to be in good condition with adequate vegetation.
Four deficiencies that are in need of corrective measures were observed. The following features were visually
identified as 1) deficient and in need of corrective measures, 2) as minor functional issues requiring monitoring or
3) as functional and not in need of corrective measures. The numbered items below correspond to the numbers
on Figure 1 and to the numbered photos in the photographic log.
Deficiencies
A slope failure was observed on the upper portion of the steep slope on northwestern portion of the
landfill property (photograph 1). The slope failure was reported in the last seven cover inspections S&ME
performed for the site.
The flexible slope pipe draining the stormwater from slope drain No. 1 inlet to the southern access road
is disconnected at a joint (photo 2).
A depression with standing water was observed along the east side of the base of the access road on the
southwestern portion of the landfill cap, where the southern access road connects the landfill cap to the
along the southern border of the landfill. Evidence of this standing water was previously observed
during S&ME's November of 2018, June 2020, and October 2020 inspections. During the May 2021
maintenance, soil and gravel was placed in the depression to promote water drainage. When S&ME
inspected the area in June 2021 and December 6, 2021, some standing water was again observed within
the depression and adjacent access road (photographs 3a and 3b).
Vegetation is becoming overgrown on the access roads to MW-6 and MW-9 (photograph 4).
Minor Functional Issues
The stormwater outfall for the pipe draining the stormwater ditch parallel to the southern access road
appears to be functioning based on evidence of water flow. There was evidence of erosion around the
inlet of the pipe. Evidence of scouring was visible below the culvert, and there appears to be an area
where the pipe joints have become disconnected under the road. The outfall appears to be stable
despite several significant rain events since the last inspection (photographs 5a, 5b).
A small slope subsidence was noted along the southern slope. The subsidence was approximately 1.5
feet deep and 2 feet wide. No trash is visible. No photo was taken due to gunfire on the adjacent
property.
January 17, 2021

=0
Landfill Cover Inspection — December 2021
Sorrell Landfill (Permit #92-04)
Apex, Wake County, North Carolina
S&ME Project No. 1054-07-251
Scouring was observed in the outfall ditch below the slope drains at Diversion Ditches/ Diagonal Water
Bars No. 1. The mesh and rebar for the screen of Diagonal Ditch/ Water Bar No. 1 has been damaged.
(photographs 7a and 7b).
Functional Items
An area within the access road to monitor well MW-7 was observed to have a small hole the cavity was
repaired and is now functional (photograph 8).
Gravel on the southern access road just west of diversion ditch / diagonal water bar no. 2 was repaired
and is now functional. (photograph 9)
The inlet of the culvert conveying an unnamed stream across the access road just east of MW-6 has been
cleared and is now functional (photograph 10).
A depression between landfill gas vents GV-2 and GV-3 that was repaired during the fall of 2017 appears
to be subsiding and some ponded water was observed during the June and October 2021 inspections
(photograph 11).
A depression on the landfill cap adjacent to landfill gas vents GV-13 and VT-13 in the northeastern
portion of the landfill was repaired during the May 2019 maintenance event. Some ponded water was
observed during the June 2020 inspection. During the June 2021 inspection this depression was repaired,
no ponding water was observed (photographs 12a and 12b).
A depression on the southeast corner of the landfill was observed during this inspection (photograph
13). This depression was first identified during the June 2020 monitoring event and was repaired in the
spring of 2021.
14. Grass and vegetation across the landfill cap and roads have been mowed. This maintenance item has
been completed twice a year over the past several years, substantially improving the vegetative cover at
the site. The grass and vegetation are currently an acceptable height (photos 14a and 14b)
The vegetation growing on the western hill slope of the landfill cap has been mowed and removed from
the slope (photographs 15a to 15b).
16. The vegetation previously growing in and clogging the headwall structures at the entrance of the slope
drains on the south slope has been cut and removed (photos 16a and 16b).
17. The vegetation growing in and clogging the drainage ditch running parallel to the landfill along the
southern access road has been removed (photographs 17a and 17b).
18_ The vegetation previously growing in and clogging the entrance of the slope drains at water diversion
bars No. 1 and 2 has been cut and removed (photograph 18).
The approximate location of each of the above items is labeled on the attached Site Plan drawing (Figure 1).
RECOMMENDED CORRECTIVE MEASURES
S&ME recommends the following corrective measures for each observed item:
January 17, 2021

Landfill Cover Inspection — December 2021
a Sorrell Landfill (Permit #92-04)
I Apex, Wake County, North Carolina
IIa
S&ME Project No. 1054-07-251
Deficiencies
The slope failure should be evaluated by a qualified professional to determine the cause of the failure
and repaired according to their recommendations to prevent further damage to the landfill cap, soil
erosion, or exposure of waste.
The flexible slope pipe draining the stormwater from slope drain No. 1 inlet to the southern access road
appears to be disconnected at a joint. The plastic flexible slope pipe should be repaired to promote
surface water draining off the landfill cap.
The area of subsidence collecting surface water at the base of the landfill adjacent to the access road
which connects the southwestern portion of the landfill cap to the southern access road has consistently
been observed to have standing water in consecutive inspections. During the May 2021 maintenance,
soil and gravel was placed in the depression to promote water drainage. When S&ME inspected the area
in June 2021 and December 6, 2021, some standing water was again observed within the depression and
adjacent access road. This area should be repaired to continue to promote drainage.
Vegetation should be cleared to allow access to monitor wells MW-6 and MW-9.
Minor Functional Issues:
Rip rap had previously been installed within the stormwater outfall where scouring was occurring. While
the previous inspections indicated that the rip rap was being relocated within the outfall during high flow
events, there has been no additional scour or rip rap relocation in the outfall since the last inspection.
The outfall should continue to be monitored for any further rip rap displacement or scour below the
outfall. If further damage is observed, larger rip rap should be installed to prevent further degradation of
the outfall and to prevent relocation of the newly installed rip rap during high flow periods. The joints in
the pipe should be monitored for evidence of erosion between the joints. Should the level of erosion or
scouring impact the integrity of the road, the pipe should be repaired or replaced.
The small slope subsidence should be monitored for an increase in depth or size. If the area increases in
size, it should be filled, graded, and stabilized with vegetation. The subsidence has not increased in size
since the last inspection.
The scouring below the outfalls for the slope drains in the Diversion Ditches/ Diagonal Water Bar Nos. 1
and 2 should be monitored for further erosion. Should further erosion be observed, efforts should be
undertaken to stabilize the eroded areas. No further erosion has been observed since the last inspection.
Functional Issues:
S&ME recommends that the landfill cap continue to receive regular, bi-annual mowing of the landfill cap in the
spring and fall to promote the health of the vegetative cover. Areas of settlement, and depressions, holding water
should continue to be identified, monitored, and repaired to promote water draining off the landfill cap and
minimize standing water above waste.
January 17, 2021 4

Landfill Cover Inspection — December 2021
a Sorrell Landfill (Permit #92-04)
I Apex, Wake County, North Carolina
IIa
S&ME Project No. 1054-07-251
CLOSING
S&ME appreciates the opportunity to provide these services and hopes that you find this report to be complete
and informative. We would appreciate an opportunity to discuss our findings and recommendations with you.
Please call us at [phone] if you have any questions or comments, or if we can be of further assistance.
Sincerely,
S&ME, Inc.
ldj� L/D -
Ashley Bentz, P.W.S.
Environmental Project Professional
[e-mail]
Attachments: Photographic Log
Figure 1 — Cover Inspection Site Map
Samuel P. Watts, P.G.
Senior Project Manager
[e-mail]
cc: Mr. James Easthom - Kennon, Craver, Belo, Craig & McKee, PLLC (ieasthom@ken noncraver.com)
Mrs. Teresa Sorrell Atkins ([e-mail])
January 17, 2021 5

Attachments

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of branches overhanging the access road to MW-6 and
9.
ew of minor erosion above the culvert pipe in the ditch that
ns parallel to the southern access road.
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5a
View of pipe connecting the ditch north of the southern access
road to the ditch south of the access road along the southern
orooertv boundary facin west).
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Diversional Ditch/ Diagonal Water Bar No. 1 (looking
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Mesh is pulled away into the road and rebar is bent
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Site Photographs S&ME Project No. 1054-07-251
Sorrell Landfill Taken by: J. Martin Date Taken: 12/6/2021
Apex, Wake County, North Carolina

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7b
View of scouring at outfall of slope drains installed within
Diversion Ditch/ Diagonal Water Bar no. 1.
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9
View of gravel within the southern access road on slope west of
diversion ditch / diagonal water bar
no. 2. Taken from top of
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iew access road to monitoring well MW-7.
1 O of culvert east of MW-6. Water was flowing through
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ulvert and pipe.
0 Site Photographs S&ME Project No. 1054-07-251
III _= Sorrell Landfill Taken by: J. Martin Date Taken: 12/6/2021
Apex, Wake County, North Carolina

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11View
of landfill gas vents GV-2 and GV-3 looking north., no
ponding water was observed.
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12b
View of depression forming on the landfill cap adjacent to
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landfill gas vents GV-13 and VT-13. No ponding water was
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12 a
View of depression forming on the landfill cap adjacent to
landfill gas vents GV-13 and VT-13. No ponding water was
observed.
13 iew of depression on southeastern edge of the landfill. Ground
as dry, with small areas of mud, no ponding water observed.
Site Photographs S&ME Project No. 1054-07-251
Sorrell Landfill Taken by: J. Martin Date Taken: 12/6/2021
Apex, Wake County, North Carolina

1
14a
Overall view of grassed area across the landfill cap (looking
east).
15a
View of the recently mowed back (western) slope of the landfill
cap looking uphill from the access road.
14b View of the access road to monitor well MW-4, looking west.
Vegetation that had been encroaching onto the access road was
of the recently mowed back (western) slope of the landfill
15 b riew
ap looking uphill from the access road.
0 Site Photographs S&ME Project No. 1054-07-251
III _ Sorrell Landfill Taken by: J. Martin Date Taken: 12/6/2021
Apex, Wake County, North Carolina

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16a
View of Slope Drain #2 Inlet/ Headwall, (looking south).
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17
View of the drainage ditch running parallel to the southern
landfill boundary.
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16b
View of Slope Drain #1 Inlet/ Headwall, (looking west).
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18
iew of Diversional
Ditch/ Diagonal Water Bar #2 (looking
southwest).
0 Site Photographs S&ME Project No. 1054-07-251
III _ Sorrell Landfill Taken by: J. Martin Date Taken: 12/6/2021
Apex, Wake County, North Carolina

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