9204_Sorrell_MSWLF_TopographicSurveyCoverThicknessEvaluationReport_DIN26739_20160902

S&ME, Inc. | 3201 Spring Forest Road | Raleigh, NC 27616 | p 919.872.2660 | f 919.876.3958 | www.smeinc.com
September 2, 2016
c/o Ms. Jackie Drummond via email:[e-mail]
Division of Waste Management
217 West Jones Street
Raleigh, North Carolina 27717
c/o Mr. James Easthom via email:[e-mail]
Kennon, Craver, Belo, Craig & McKee, PLLC
P.O. Box 51579
Durham, North Carolina 27717
Reference:Topographic Survey and Cover Thickness Evaluation Report
Sorrell Landfill (Permit No. 92-04)
8000 Smith Road, Apex, North Carolina
S&ME Project No. 1054-07-251
Dear Ms. Drummond and Mr. Easthom:
This letter report is provided to document the findings of our topographic survey and cover thickness
evaluation at the closed Sorrell Landfill located in Apex, North Carolina. This report was prepared, and the
services described herein were performed, in accordance with S&ME Proposal No. P4258-07V, dated April
7, 2007, S&ME’s memo Cost Estimate for Topographic Survey & Cover Thickness Evaluation, dated July 15,
2016, and the NCDEQ authorization memo, dated July 20, 2016.
BACKGROUND INFORMATION
On June 2, 2016, 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 landfill. An apparent slope failure
was observed on the upper portion of steep slope on the northwestern portion of the landfill. On June
13, 2016, Sam Watts, P.G. and Brian Ladd, P.E. (S&ME) returned to the site for a closer look at the slope
failure. A shallow slope failure was observed on an exterior slope of the western/northwestern end of the
landfill. A scarp about 18 to 24 inches in height was present near the top of the slope, about 10 feet
below a diversion swale/berm at the crest of the slope. Exposed soils in the scarp were dry and no
seepage was noted in the slope face. No formation of a significant toe berm, typically indicative of mass
rotational movement, was observed. The area from the scarp to about 25 feet downslope was slightly
flatter than the remainder of the downslope face. It appeared that the flattened slope section is a result
of the movement of the failed material downslope. It appeared that the failure was relatively shallow, with
the failure surface between the soil cover and the waste, and that the movement is a shallow translational
movement. The depth of the failure was not evaluated during the site visit.
On July 7, 2016, Messrs. Watts and Ladd discussed their observations with Ms. Jackie Drummond and Mr.
Jason Watkins (DWM) via teleconference. At the request of Ms. Drummond and Mr. Watkins, S&ME
prepared a cost estimate to assess the thickness of the soil landfill cover and to survey the topographic
Topographic Survey & Cover Thickness Evaluation Report
Sorrell Landfill (Permit No. 92-04)
8000 Smith Road, Apex, North Carolina
S&ME Project No. 1054-07-251
September 2, 2016 2
surface of the landfill in the area of the slope failure and above (up slope of) the slope failure. The
following information describes the completed work that was performed in association with the requested
cost estimate.
DESCRIPTION OF SERVICES
Evaluation of Landfill Cover Thickeness
S&ME personnel mobilized to the site on August 5, 2016 to advance hand auger borings in the area of
the slope failure and immediately above the slope failure. A total of 15 hand auger borings were
advanced in these areas until waste was encountered or hand auger refusal occurred. Boring logs
depicting lithology for each boring location are included in Attachment I. Boring locations and IDs are
shown on Figure 1.
Three hand auger borings were advanced in the area of the slope failure (B-1, B-2 and B-3) to depths
ranging from 5 feet below ground surface (ft. bgs.) to 12 ft. bgs. The thickest soil cover in the area of the
slope failure was observed in borings B-1 and B-2 with a thickness greater than 12 ft. At these borings, a
light brown sandy silt was observed from 0 to 5 ft. bgs., and a reddish brown clay was observed from 5 to
12 ft. bgs. Borings B-1 and B-2 were not advanced to waste due to encountering water/muck in the
borings from 11 ft. bgs to 12 ft bgs., causing the bore hole to collapse. Hand auger boring B-3 was
advanced to 5 ft. bgs. and was not advanced further due to refusal caused by rocky conditions.
Hand auger borings in the area above (southeast) the slope failure (B-4 to B-15) were advanced to depths
ranging from 1 ft. bgs. to 9 ft. bgs. Borings in this area contained soil cover ranging in thickness from 3 ft.
to 9 ft. The thickest soil cover in the area above the slope failure was observed in boring B-5 with a
thickness of 9 ft. A soil cover thickness of 4.5 ft. and 5 ft. was observed in borings B-12 and B-13,
respectively. Borings B-14 and B-15 had a soil cover thickness of 3 ft. Several borings in the area above
the slope failure could not be advanced to waste due to hand auger refusal on large rocks in the cover
soil.
Survey of Ground Surface Topography
S&ME subcontracted Bateman Civil Surveying Co. (BCSC) to survey the hand auger boring locations and
ground surface elevation in the area of the slope failure and immediately above (southeast) the slope
failure.
BCSC personnel mobilized to the site on August 17, 2016 to survey the area as requested by S&ME. A
figure depicting boring locations and area topography is included as Figure 2. As depicted by the figure,
the slope in the area of the slope failure ranges from approximately 410 ft. above mean sea level (AMSL)
to 475 ft. AMSL, an elevation change of 65 ft. The figure also depicts a mounded area in the area
immediately above (southeast) the slope failure.
Topographic Survey & Cover Thickness Evaluation Report
Sorrell Landfill (Permit No. 92-04)
8000 Smith Road, Apex, North Carolina
S&ME Project No. 1054-07-251
September 2, 2016 3
SUMMARY OF FINDINGS
Based on the cover thickness evaluation and topographic survey, it appears that the soil cover on the
slope is approximately 12 feet thick. It also appears that water is infiltrating behind the soil cover on the
slope. The weight of the relatively thick soil cover and the apparent water observed between the waste
and the soil cover on the slope (B-1 and B-2) are likely contributing to the observed slope failure. This
was most evident in borings B-1 and B-2 located on the slope where water/muck was observed from 11-
12 ft. bgs., causing the borings to collapse. Additionally, several locations were unable to be advanced to
waste due to auger refusal. Silty, rocky soils were observed in several of the borings which could promote
the infiltration of water in the area immediately above the slope failure. The topographic elevations and
cover thickness included in the report may be used to prepare a grading plan to reduce the thickness of
the soil on the slope and to minimize surface water infiltration.
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.
Bryan S. Wence Samuel P. Watts, P.G.
Environmental Staff Professional Senior Project Manager
[e-mail] [e-mail]
Attachments:
Figure 1 - Boring Locations and Area Topography
Boring Logs - August 5, 2016 Hand Augers
Attachments
CHECKED BY:DRAWN BY:
APPROVED BY:DESIGNED BY:
PROJECT NUMBER:
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BORING LOG
Project Name:Sorrel Landfill
Project No.1054-07-251, Phase 22
Sampling Personnel:Bryan Wence and Justin Ahn
Date Drilled:8/5/2016
Total Depth:
Drilling Method:Hand Auger
Boring ID:B-1
From To
0.0 1.0 Sandy silt-light brown
1.0 1.5 Sandy silt-brown with gray/white gravel
1.5 3.0 Silty clay-brown
3.0 5.0 Silty sand-gray with orange; moist
5.0 7.0 Clay-brown/orange; moist
7.0 9.0 Clay-red; moist
9.0 11.0 Clay-red; wet
11.0 12.0 Clay-red; saturated
Boring terminated at 12 feet due to
water/muck causing boring collapse
Boring ID:B-2
From To
0.0 1.0 Sandy silt-light brown
1.0 4.0 Silty clay-light brown
4.0 5.0 Clay- brown; moist
5.0 6.0 Brown clay and gray gravel
6.0 7.0 Clay-gray/brown with red; moist
7.0 8.0 Clay- red/brown; moist
8.0 10.0 Clay-gray/brown; moist
10.0 12.0 Clay-gray/brown; saturated
Boring terminated at 12 feet due to
water/muck causing boring collapse
Notes:
ft-bgs= Depth in feet below ground surface
Depth (ft-bgs)Soil Description
Depth (ft-bgs)Soil Description
BORING LOG
Project Name:Sorrel Landfill
Project No.1054-07-251, Phase 22
Sampling Personnel:Bryan Wence and Justin Ahn
Date Drilled:8/5/2016
Total Depth:
Drilling Method:Hand Auger
Boring ID:B-3
From To
0.0 0.5 Sandy clay-gray/brown
0.5 1.0 Sandy silt- brown with white fragments
1.0 2.0 Sandy silt- red/brown
2.0 3.0 Sandy silt- brown/gray
3.0 4.5 Sandy silt- dark gray
4.5 5.0 Sandy silt-dark gray/brown,
with black gravel
Augar refusal at 5 feet
Boring ID:B-4
From To
0.0 1.0 Sandy silt- light brown
1.0 5.0 Clay-Red
5.0 9.0 Clay-Red
Boring terminated at 9 feet
Notes:
ft-bgs= Depth in feet below ground surface
Depth (ft-bgs)Soil Description
Depth (ft-bgs)Soil Description
BORING LOG
Project Name:Sorrel Landfill
Project No.1054-07-251, Phase 22
Sampling Personnel:Bryan Wence and Justin Ahn
Date Drilled:8/5/2016
Total Depth:
Drilling Method:Hand Auger
Boring ID:B-5
From To
0.0 3.0 Sandy silt-light tan/brown; dry, loose
3.0 5.0 Clayey silt- reddish brown; dry,firm
5.0 6.0 Silty clay-reddish brown; moist, firm
6.0 9.0 Silty clay-grayish brown; moist, firm
9.0 -Waste
Boring ID:B-6
From To
0.0 3.0 Sandy silt-light tan; dry, loose
3.0 4.5 Silty sand-white; tight with rocks
Auger refusal at 4.5' due to rocks in
2 different locations
Notes:
ft-bgs= Depth in feet below ground surface
Depth (ft-bgs)Soil Description
Depth (ft-bgs)Soil Description
BORING LOG
Project Name:Sorrel Landfill
Project No.1054-07-251, Phase 22
Sampling Personnel:Bryan Wence and Justin Ahn
Date Drilled:8/5/2016
Total Depth:
Drilling Method:Hand Auger
Boring ID:B-7
From To
0.0 3.0 Sandy silt-light tan/brown; dry
3.0 4.0 Silty sand- white; tight with rocks
Auger refusal at 4' due to rocks
Boring ID:B-8
From To
0.0 4.0 Sandy silt- light tan/brown; dry, loose
Auger refusal at 4' due to rocks at
3 different locations
Notes:
ft-bgs= Depth in feet below ground surface
Depth (ft-bgs)Soil Description
Depth (ft-bgs)Soil Description
BORING LOG
Project Name:Sorrel Landfill
Project No.1054-07-251, Phase 22
Sampling Personnel:Bryan Wence and Justin Ahn
Date Drilled:8/5/2016
Total Depth:
Drilling Method:Hand Auger
Boring ID:B-9
From To
0.0 3.0 Clayey silt-brownish red; dry, firm
3.0 6.0 Silty clay-brown/gray; moist, firm
6.0 8.0 Silty clay-reddish brown; moist firm
Auger refusal at 8' due to tree debris
Boring ID:B-10
From To
0.0 1.0 Silty sand- tan/brown with gravel
Auger refusal at 1'
Notes:
ft-bgs= Depth in feet below ground surface
Depth (ft-bgs)Soil Description
Depth (ft-bgs)Soil Description
BORING LOG
Project Name:Sorrel Landfill
Project No.1054-07-251, Phase 22
Sampling Personnel:Bryan Wence and Justin Ahn
Date Drilled:8/5/2016
Total Depth:
Drilling Method:Hand Auger
Boring ID:B-11
From To
0.0 2.0 Sandy silt-orangish; loose, dry
2.0 3.0 Silty sand-white; tight with rocks
Auger refusal at 3' due to rocks
Boring ID:B-12
From To
0.0 1.0 Sandy silt-light tan/brown; loose, dry
1.0 3.0 Sandy silt-light tan/white; very loose, coarse
3.0 4.5 Clayey silt-reddish brown; firm moist
4.5 -Waste
Depth (ft-bgs)Soil Description
Depth (ft-bgs)Soil Description
BORING LOG
Project Name:Sorrel Landfill
Project No.1054-07-251, Phase 22
Sampling Personnel:Bryan Wence and Justin Ahn
Date Drilled:8/5/2016
Total Depth:
Drilling Method:Hand Auger
Boring ID:B-13
From To
0.0 1.0 Silty sand-tan/white; tight with rocks
1.0 3.0 Sandy silt-reddish brown; moist
3.0 5.0 Clayey silt-tan/brown; moist, firm
5.0 -Waste
Boring ID:B-14
From To
0.0 1.0 Sandy silt-light tan/brown; loose, dry
1.0 2.5 Clayey silt-reddish brown; firm, moist
2.5 3.0 Clayey silt-olive/tan; firm, moist
3.0 -Waste
Notes:
ft-bgs= Depth in feet below ground surface
Depth (ft-bgs)Soil Description
Depth (ft-bgs)Soil Description
BORING LOG
Project Name:Sorrel Landfill
Project No.1054-07-251, Phase 22
Sampling Personnel:Bryan Wence and Justin Ahn
Date Drilled:8/5/2016
Total Depth:
Drilling Method:Hand Auger
Boring ID:B-15
From To
0.0 2.0 Sandy silt-light tan/brown; loose, dry
2.0 3.0 Clayey silt-reddish brown;
somewhat firm, moist
3.0 -Waste
Notes:
ft-bgs= Depth in feet below ground surface
Depth (ft-bgs)Soil Description