9204_Wake_Sorrell_MSWLF_Fall2020LFCoverMaint_FID1516999_20201211

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December 10, 2020
Division of Waste Management
217 West Jones Street
Raleigh, North Carolina 27603
Attn: Ms. Jackie Drummond via email: [e-mail]
Reference: Landfill Cover Inspection — October 2020
Sorrell Landfill (Permit #92-04)
Apex, Wake County, North Carolina
S&ME Project No. 1054-07-251
Dear Ms. Drummond:
On October 19, 2020, 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 2020 — Landfill Cover Maintenance Cost Estimate, dated March 13, 2020, and the NCDEQ
memorandum Authorization to Conduct the Spring 2020 and Fall 2020 Landfill Cover Maintenance Activities Closed
Sorrell MSW Landfill, dated March 18, 2020.
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

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Landfill Cover Inspection — October 2020
Sorrell Landfill (Permit #92-04)
Apex, Wake County, North Carolina
S&ME Project No. 1054-07-251
The October 19, 2020 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 16 to 18, 2020 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.
Five deficiencies 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 five cover inspections S&ME
performed for the site.
An area within the access road to monitor well MW-7 was observed to have a small hole. It appears
surface water has been flowing into the hole. The soil inside the hole is being washed away and is
creating a cavity (photographs 2a and 2b).
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 first observed during
S&ME's November of 2018 inspection. No evidence of standing water was observed during the 2019
inspections. During the June and October 2020 inspections, standing water was again observed within
the depression and adjacent access road (photographs 3a and 3b).
Gravel on the southern access road just west of diversion ditch / diagonal water bar no. 2 has begun to
erode and gullies are beginning to form within the access road on the steep slope (photograph 4).
5. The inlet of the culvert conveying an unnamed stream across the access road just east of MW-6 has
become partially clogged (photograph 5).
6 Vegetation is becoming overgrown on the southern access roads along the southern edge of the landfill
(photograph 6).
Minor Functional Issues
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. This depression appears to
have subsided further and some ponded water was observed during the June 2020 inspection
(photographs 7a and 7b).
December 10, 2020

--a
Landfill Cover Inspection — October 2020
Sorrell Landfill (Permit #92-04)
Apex, Wake County, North Carolina
S&ME Project No. 1054-07-251
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 2020 inspections
(photograph 8).
A depression on the southeast corner of the landfill was observed containing standing water during this
inspection (photograph 9). This depression was first identified during the June 2020 monitoring event.
Scouring below the stormwater outfall for the culvert draining the stormwater ditch parallel to the
southern access road has been observed in previous inspection reports. While a previous inspection
indicated that the outfall itself had experienced erosion, the outfall appears to be stable despite several
significant rain events since the last inspection (photograph 10).
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 appears to be an area where the pipe
joints have become disconnected under the road (photograph 11).
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 (photograph 12).
Scouring was observed in the outfall ditch below the newly installed slope drains at Diversion Ditches/
Diagonal Water Bars Nos. 1 and 2 (photographs 13a and 13b).
Evidence of vehicular traffic has been observed on the landfill. These vehicles appear to be accessing the
landfill via an access road from an adjacent natural gas easement to the west (photographs 14a and 14b).
Water appears to be bypassing and undermining the pipe draining the stormwater ditch parallel to the
southern access road at the inlet (photograph 15).
Functional Items
A small depression that had formed on the landfill cap adjacent to the berm on the southeastern side of
the landfill where the landfill cap is accessed (photograph 16) was repaired and is now functional.
A small depression has formed in diagonal water bar no. 1 (photograph 17) was repaired and is now
functional.
The landfill cap and access roads have been mowed to remove excess grass and vegetation. 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
(photographs 18a through18d).
The vegetation growing on the western hill slope of the landfill cap has been mowed and removed from
the slope (photographs 19a and 19b).
The vegetation growing in and clogging slope drain inlets 1 and 2 and their associated headwalls has
been cut and removed. The slope drain inlets and their associated headwalls are functioning as designed
(photographs 20a through 20d).
21. The vegetation previously growing in and clogging the headwall structures at the entrance of the slope
drains at water diversion bars No. 1 and 2 has been cut and removed (photographs 21 a and 21 b).
22. The vegetation growing in and clogging the drainage ditch running parallel to the landfill along the
southern access road has been removed and treated (photographs 22a and 22b).
The approximate location of each of the above items is labeled on the attached Site Plan drawing (Figure 1).
December 10, 2020 3

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RECOMMENDED CORRECTIVE MEASURES
Landfill Cover Inspection — October 2020
Sorrell Landfill (Permit #92-04)
Apex, Wake County, North Carolina
S&ME Project No. 1054-07-251
S&ME recommends the following corrective measures for each observed item:
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.
2. The cavity beneath the access road to monitor well MW-7 should be filled, graded, and stabilized with
vegetation.
3. 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. To minimize water ponding on the
landfill cap above the buried waste, this area should be filled and regraded to promote water drainage
off the landfill cap and stabilized with vegetation.
The gravel on the southern access road on the steep slope just west of diagonal water bar / diversion
ditch no. 2 should be refreshed and the gullies forming within the road should be repaired.
5. The culvert should be cleared of debris.
6. Vegetation along the southern access road should be trimmed to allow for continued access.
Minor Functional Issues:
The depression should be monitored to determine whether standing water is a regular occurrence in this
area. Should the standing of water continue to be observed on the cap, these areas should be graded to
promote surface water draining off the landfill cap.
The depression should be monitored to determine whether standing water is a regular occurrence in this
area. Should the standing of water continue to be observed on the cap, these areas should be graded to
promote surface water draining off the landfill cap.
The depression should be monitored to determine whether standing water is a regular occurrence in this
area. Should the standing of water continue to be observed on the cap, these areas should be graded to
promote surface water draining off the landfill cap.
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 disconnected joint in the pipe should be monitored for evidence of scouring or erosion between the
joints. Should the level of erosion or scouring reach levels where it could impact the integrity of the road,
the pipe should be repaired or replaced.
12. 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.
December 10, 2020 4

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Landfill Cover Inspection — October 2020
Sorrell Landfill (Permit #92-04)
Apex, Wake County, North Carolina
S&ME Project No. 1054-07-251
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.
Measures should be taken to prevent vehicular traffic from accessing the landfill via the adjacent natural
gas easement, to the west.
The pipe should be monitored for continued erosion around the entrance of the pipe. If further erosion
or damage is observed, the pipe inlet should be repaired and stabilized.
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. In June 2020, S&ME personnel purchased and installed a new chain and a
new lock with a shrouded shackle, on the gated entrance to the east off Smith Road.
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.
Ashley Bentz, P.W.S Samuel P. Watts, P.G.
Project Scientist Senior Project Manager
[e-mail] [e-mail]
Attachments: Photographic Log
Figure 1 — Cover Inspection Site Map
cc: Mr. James Easthom - Kennon, Craver, Belo, Craig & McKee, PLLC ([e-mail])
Mrs. Teresa Sorrell Atkins ([e-mail])
December 10, 2020

Attachments

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f
iew of small hole at entrance of cavity in the access road to
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monitoring well MW-7.
a iew of water ponding in a small depression east of the base of
he access road connecting the southwestern portion of the
landfill to the southern access road.
Site Photographs S&ME Project No. 1054-07-251
Sorrell Landfill Taken by: A. Bentz Date Taken: 10/19/2020
Apex, Wake County, North Carolina

3 b View of water ponding in the access road beside a small
depression east of the base of the access road connecting the
southwesterp Wortion of the landfill to the southern access road.
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of partially clogged inlet of culvert east of MW-6.
Site Photographs S&ME Project No. 1054-07-251
Sorrell Landfill Taken by: A. Bentz Date Taken: 10/19/2020
Apex, Wake County, North Carolina

a of depression forming on the landfill cap adjacent to
�iew
ndfill gas vents GV-13 and VT-13. The repair appears to have
w of water ponding in depression between landfill gas vents
-2 and GV-3 looking north.
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7b
View of depression forming on the landfill cap adjacent to
landfill gas vents GV-13 and VT-13. The repair appears to have
settled slightly and is ponding water.
9
View of water ponding in depression on southeastern edge of
he landfill.
0 Site Photographs S&ME Project No. 1054-07-251
III _= Sorrell Landfill Taken by: A. Bentz Date Taken: 10/19/2020
Apex, Wake County, North Carolina

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11
iew of the pipe connecting the ditch north of the southern
access road to the ditch south of the access road along the
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13a
View of scouring at outfall of slope drains installed within
Diversion Ditch/ Diagonal Water Bar no. 1.
Site Photographs S&ME Project No. 1054-07-251
Sorrell Landfill Taken by: A. Bentz Date Taken: 10/19/2020
Apex, Wake County, North Carolina

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14a View of access road where vehicles appear to be entering the
perimeter road and landfill footprint from an adjacent natural
gas easement.
J.
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iew of evidence water is bypassing and undermining the pipe
draining the stormwater ditch parallel to the southern access
Site Photographs S&ME Project No. 1054-07-251
Sorrell Landfill Taken by: A. Bentz Date Taken: 10/19/2020
Apex, Wake County, North Carolina

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16 iew of depression adjacent to the berm on the southeastern
side of the landfill where the landfill cap is accessed which has
been reDaired.
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18a Overall view of recently mowed grass and vegetation across the
landfill cap (looking west).
0 Site Photographs S&ME Project No. 1054-07-251
III _= Sorrell Landfill Taken by: A. Bentz Date Taken: 10/19/2020
Apex, Wake County, North Carolina

0 Site Photographs S&ME Project No. 1054-07-251
III _= Sorrell Landfill Taken by: A. Bentz Date Taken: 10/19/2020
Apex, Wake County, North Carolina

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20a (View of flexible slope drains from Slope Drain Inlet #1 (looking
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20c iew of Slope Drain #2 Inlet/ Headwall, which has recently had
he woody vegetation removed (looking west).
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View of flexible slope drains from Slope Drain Inlet #1 (looking
south).
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of flexible slope drains from Slope Drain Inlet #2 (looking
South).
Site Photographs S&ME Project No. 1054-07-251
Sorrell Landfill Taken by: A. Bentz Date Taken: 10/19/2020
Apex, Wake County, North Carolina

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21 b View of Diversional Ditch/ Diagonal Water Bar #2 (looking
southwest).
View of the drainage ditch running parallel to the southern
ZZb landfill boundary.
Site Photographs S&ME Project No. 1054-07-251
Sorrell Landfill Taken by: A. Bentz Date Taken: 10/19/2020
Apex, Wake County, North Carolina