040036_06 Soil Mechanics Report_20230607

USDAUnited States
Department of
Agriculture
Natural Resources Conservation Service
Natural subject: ENG — Soil Mechanics Report
Resources White Rock Dairy AWMS
Conservation Anson County, NC
Service
National Design,
Construction,
and Soil
Mechanics
Center
Fort Worth Soil
Mechanics
Laboratory
501 W Felix
Fort Worth, TX
76115
Phone:
817-509-3204
To: James Kjelgaard, P.E.
State Conservation Engineer
NRCS, Raleigh, North Carolina
BACKGROUND
Date: April 20, 2023
File Code: 210-22
Job No.: 7847
The soil mechanics tests requested for the samples submitted from the subject site
have been completed and the test results are summarized on the attached reporting
form NRCS-ENG-354. Three disturbed large size samples were submitted to the
NDCSMC-Fort Worth soil mechanics laboratory for testing and analysis to determine
the material's index properties and soil classification. Tests performed on the disturbed
samples included standard index (particle size analysis and classification) and as -
received moisture content. In addition, compaction tests and permeability tests were
performed on the samples to evaluate the suitability of the soils as compacted liner
material for animal waste containment. This report summarizes the results of the tests
performed on the samples and provides some design and construction
recommendations for a compacted earthen liner based on the test results.
INTERPRETATION AND DISCUSSION OF DATA
Index Testing
Based upon the index test results, the samples submitted classified as fat clay, CH
soils, as determined by the Unified Soil Classification System (USCS). The complete
index properties of the sample are detailed on the attached reporting form NRCS-ENG-
354. The results are summarized in the table below, included here for quick reference.
Sample Number
Percent Passing
LL
PI
USCS
Class.
We
N
Lab
Field
0.002
mm
#200
sieve
#4 sieve
23-129
1
48
100
100
65
37
CH
32.1
23-130
2
43
100
100
65
36
CH
22.2
23-131
3
41
92
100
52
30
CH
21.8
Dispersion Testing
Crumb dispersion indication tests were performed according to ASTM D6572 on a small
portion of the samples. Two crumbs were tested for each sample. For Samples 23-129
and 23-130, two crumb had a reading of 1 after one hour and 1 after four hours. For
Sample 23-131, one crumb had a reading of 2 after one hour and 3 after four hours.
Fine grained soils with crumb test readings of 1 have a low potential for dispersion.
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White Rock Dairy, NC Soil Mechanics Report 2
Double hydrometer dispersion tests were then performed in accordance with ASTM
D4221, which yielded tests results of 28 percent for Sample 23-129, 19 percent for
Sample 23-130 and 35 percent for Sample 23-131.
The dispersion test results indicate that samples 23-129 and 23-130 are not dispersive,
and that sample 23-131 may be dispersive. The crumb and double hydrometer
dispersion test results are included on form NRCS-ENG-354.
Dispersion can vary in intensity within short distances in the field. Therefore, when
dispersion is detected in the lab, it is an indication that dispersive soils are present in
the area. Typically, the crumb and double hydrometer dispersion tests are both
performed in the lab to increase the opportunity for detecting the potential problem.
However, because each test is performed on a small discrete portion of the sample, it is
possible for one test to detect dispersion and another to miss it or for the two tests to
indicate different degrees of severity of the dispersion.
When evaluating the crumb test results ASTM D6572 considers soils with a crumb of 1
to be nondispersive. NRCS Soil Mechanics Note 13 (February, 1991) provides the
following guidelines for classifying dispersive soils based on the double hydrometer
dispersion test results:
• % Dispersion < 30% - The soil is not dispersive
• 30% < %Dispersion < 60% - Inconclusive, additional testing required
• % Dispersion > 60% - The soil is dispersive
Compaction Testing
Standard Proctor density compaction tests were performed on the samples according
to ASTM D698, using Method A. A fine specific gravity (Gs) test was also performed
on a portion of the samples according to ASTM D854. The Gs tests were performed to
calculate the zero air voids curves for the compaction plots as well as the saturated
water contents of the soils. Test results are plotted on the Compaction and Penetration
Resistance forms included in the attachments. The test results are also summarized
on form NRCS-ENG-354 and included in the table below.
Sample
Number
Depth
ft
Gs
Max. 'yd
Ib/ft3
WOPT
%
WREC
%
Wrec
Relative to
Wot
Lab
Field
23-129
1
1-5
2.67
95.0
24.0
32.1
+8.1
23-130
2
0-1
2.70
97.0
23.0
22.2
-0.8
23-131
3
2.5-10
1 2.70
101.5
1 20.0
21.8
+1.8
Maximum Allowable Permeability Rate
In an effort to introduce some conservatism in liner design, the August 2009 update to
the AWMFH, Appendix 1 OD, includes a recommendation for the use of a revised
seepage rate for NRCS criteria (for use on NRCS funded projects). This updated
seepage rate is 5,000 gallons per acre per day which also includes a small manure
sealing allowance.

White Rock Dairy, NC Soil Mechanics Report
The updated criteria are to be used unless state or local regulations are more restrictive,
in which cases those requirements should be followed. This seepage rate converts to a
required specific discharge rate of about 5.4x10-6 cm/sec. The maximum allowable
permeability rate for testing, based upon this required specific discharge rate, is
calculated using the following equation.
k=
vxd
H+d
Where: H (Liquid Depth) = maximum liquid storage depth
v (Specific Discharge Rate) = minimum rate required for AWMFH 1 OD
d (Liner Thickness) = minimum recommended thickness
k (Required Permeability) = maximum allowable permeability rate, unknown
Design variables (required specific discharge rate, liquid storage depth, and compacted
liner thickness) are inputted into this equation (a variation of Darcy's Law, Q = kiA) and
a maximum allowable permeability rate for testing is obtained. The proposed liner soils,
when tested for permeability, must have a permeability rate less than the calculated
maximum allowable permeability rate to meet the required specific discharge rate for a
site (provided the liquid depth and liner thickness do not change). This equation uses a
maximum liquid storage depth of 16.0 feet, as provided in the test request, along with a
requested liner thickness of 1.0 foot for the maximum allowable permeability rate
calculation.
k = vxd _ S.4x10-6x1.o = 3.18x10-7 cm/sec
H + d 16.0+1.0
Where: H (Liquid Depth) = 16 feet (proposed liquid storage depth)
v (Specific Discharge Rate) = 5.4x10-6 cm/sec (minimum rate required for 10D)
d (Liner Thickness) = 1.0-foot minimum thickness
k (Required Permeability) = unknown (maximum allowable permeability rate)
Additive Application
Due to the acceptable permeability rates of the test samples, the application of additives
to reduce permeability is not required.
Permeabilitv Testina
Flexible wall permeability testing was performed on the submitted samples as requested
in accordance with ASTM-D5084 after test specimens were back -pressure saturated to
provide a saturated hydraulic conductivity, k recorded in cm/sec.
Permeability tests were performed on remolded disturbed specimens to evaluate the
permeability of untreated soils when compacted to 95 percent of Standard Proctor
maximum dry density. The molding water contents of the test specimens at the time of
compaction varied from +2.0% to +3.0% percent above optimum water content.
Significant reductions in permeability were recorded for soil specimens when
compacted at the specified dry density and molding water content combinations.

White Rock Dairy, NC Soil Mechanics Report 4
The results for the permeability tests performed on the samples are included on form
NRCS-ENG-354 and in the following table.
Sample
Number
Compaction
Test w�
(%)
Saturation
Additive
k
Fiel
% of Max Yd
Ref. To
Lab
d
Wopt
%
Type
Rate
cm/sec
23-129
1
95
+2.0
82.1
None
--
1.22x10-7
23-130
2
95
+2.0
81.4
None
--
1.43x10-7
23-131
3
95
+3.0
83.2
None
--
1.14x10-7
CONSTRUCTION CONSIDERATIONS
Placement Water Content and Degree of Compaction
The samples tested can meet significantly reduced permeability rates through
compaction and water content control. The soils must be compacted to at least 95
percent of Standard Proctor maximum dry density to meet the permeability rates as
determined in the laboratory. Compaction primarily results from the expulsion of air
from a soil by the manipulation of the soil with compaction equipment. It is difficult to
compact soils at a dry density /molding water content combination where the degree of
saturation is greater than about 90 percent. In other words, it is often difficult to expel
the last 10 percent of the air from a soil mass in the compaction process. The
theoretical maximum molding water content for a soil, when compacted to a selected
density, can be estimated with the following equation.
W Max l%) — 0.90 ywater _ 1 X 100
%ya G,s
Where: wMax = Maximum molding water content (%)
ywater = 62.4 Ib/ft3 (density of water)
yd = (maximum dry density of the soil)
Gs = (specific gravity of the soil)
Using this equation and the permeability test data, a recommended molding water
content range to compact the liner soils can be calculated. The CH soils in the field
similar to the samples tested must be compacted to 95 percent of Standard Proctor
maximum dry density in order to meet the permeability rate. The material to be used
for the proposed compacted earthen liner will have a calculated maximum molding
water content (Max Wc) as included in the following table. The calculated maximum
molding water content is combined with the molding water content of the permeability
test specimens to provide the recommended molding water content ranges to compact
the soils in the field. The soils, when compacted to the specified dry density at water
contents within the specified ranges should have permeability rates at or below the lab
tested permeability rate. The maximum molding water contents were adjusted down to
the nearest half a percent for the recommended molding water content range. The
recommended molding water content ranges to compact the soils in the field similar to
the samples tested (Wc Range) are included in the following table.

White Rock Dairy, NC Soil Mechanics Report
The molding water content ranges in reference to optimum water content (Wc Ref to
Wopt) are also included.
Sample Number
Maxyd
Ib/ft3
% Maxyd
(%)
Gs
Wx
N
W. Range
(%)
W,, Ref To
Wt
N
Lab
I Field
23-129
1
95.0
95
2.67
28.5
26.0 — 28.5
+2.0 to +4.5
23-130
2
97.0
95
2.70
27.6
25.0 — 27.5
+2.0 to +4.5
23-131
3
101.5
95
2.70
24.9
23.0 — 25.0
+3.0 to +5.0
The water content of sample 23-129 tested as received was significantly higher than
the molding water content range, but the water contents of samples 23-130 and 23-131
tested as received were lower than the molding water content range. Some
adjustment of the water content of the liner material may be necessary, depending
upon the moisture conditions present on site at the time of construction. It will likely be
difficult to lower the water content of the soil more than a couple of percent at the time
of placement and compaction. Typically, the placement and compaction of fine-
grained soils at higher water contents will lower the permeability of the soil provided the
design density can still be obtained.
CONCLUSIONS AND RECOMMENDATIONS
Based upon the results of permeability testing, a suitable pond liner may be constructed
using the soils similar to soil samples tested. The soils tested, with proper compaction
and moisture control, would yield a permeability lower than the maximum allowable
discharge rate.
The NDCSMC-Fort Worth recommends the use of a 1-foot soil cover to protect the
compacted soil liner by minimizing cracking due to wetting/drying cycles.
The NDCSMC-Fort Worth recommends the use of a minimum 1.0-foot-thick compacted
liner, constructed in at least two lifts. The liner must be constructed in multiple lifts
using materials in the field that are similar to the soils that were tested. To meet a
similar permeability rate (hydraulic conductivity), the treated soils in the field should be
compacted to at least 95 percent of Standard Proctor maximum dry density. The water
content of the liner soil at the time of compaction should be within the recommended
molding water content ranges as included in the Placement Water Content and Degree
of Compaction section of this report. Some general construction recommendations for
this compacted liner project are included below.
1. The selected combination of compacted soil must be constructed in multiple lifts to
construct a liner. Typically, compacted six-inch thick layers (with a loose lift
thickness of about 9 inches) are used.
2. Over -excavate the soil and selectively stockpile those soils that are similar to the
CH samples that were tested.
3. Transport the liner material from the stockpile or borrow area to the placement area
and spread it to the approximate loose lift thickness.
4. Check the water content of the liner material to make sure it is within the
recommended molding water content range for this soil prior to compaction.

White Rock Dairy, NC Soil Mechanics Report 6
5. Make final adjustments to the water content of the liner material prior to compaction
by adding or removing water, as necessary.
6. Compact the liner material to at least 95 percent of Standard Proctor maximum dry
density with the necessary compaction equipment. A tamping roller may be the
best equipment to compact the fat clay soils.
7. Repeat steps 3 through 7 until the desired liner thickness is achieved.
8. Place a layer of cover material over the entire compacted liner area upon
completion and inspection of the final lift.
Further testing and analysis for this project was not requested. If you have any
questions about the test results or require any further testing or analysis for this project,
please contact the NDCSMC-Fort Worth at [phone].
Prepared by:
Concurred by:
O
Digitally signed
FAH M I Digitally signed by
by JON FRIPP
FAHMI AUASER
Date: 2023.04.21
A U A S E R Date: 2023.04.20
13:51:22 -05'00
FRIPP
12:30:05 -0500 ,
Fahmi Maser, P.E.
Geotechnical Engineer FTW-SML
NRCS, Fort Worth, TX
Reviewed by:
VICTOR Digitally by VICTOR SLOW K
SLOWIDate: 2
K 113:40307-050'000
Victor Slowik, P.E
Head FTW SML
NRCS, Fort Worth, TX
Jon Fripp, P.E.
Acting Co -Director, NDCSMC-SML
NRCS, Fort Worth, TX
Attachments:
Form NRCS-ENG-354, Soil Mechanics Laboratory Test Data, 1 sheet
Compaction and Penetration Resistance, 3 sheets
cc: (electronic distribution)
Zachary Butler, Geologist, NRCS, Raleigh, NC

NRCGENG350. U.S. Deparbnent of Agriculture Soil Mectanics labarzlory D-
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Compaction and Penetration Resistance ASTM D698
White Rock Dairy, NC Job No. 7847
Anson EQIP AWSP Field No. TP-22-4 Lab No. F23-129
Q 2000
R 1500
'
}
%
N
w 1000
i
c
o
500
iv
a
1
0
22.0 24.0 26.0 28.0 30.0 32.0 34.0 36.0
20.0
135.0
Method : A
Max. Particle Size: Minus No. 4
Ydmax= 95.0
130.0
Wopt% = 24.0
125.0
Fine Gs = 2,67
120.0
I
USCS = CH
Wet Density
LL = 65
115.0
PI = 37
110.0
As-Rec'd Moist.
CL
32.1 %
= 105.0
0
o
m
m 100.0
a
E
0
U
6 95.0
A.._.:,.
..,,_,
.,..
...
.
....
,.
, ,
.,..,,_,...
......
...
O 90.0
___
Dry Density
Zero Air Voids
85.0
80.0
75.0
20.0 22.0 24.0 26.0 28.0 30.0 32.0 34.0 36.0
Moisture Content (Percent of Dry Weight)
Prepared by Fort Worth Soil Mechanics Lab
1/12/2023

Compaction and Penetration Resistance
ASTM D698
White Rock Dairy, NC
Anson EQIP AWSP Field No. TP-22-6
Q. LUUU
d
c
o 1500
N
N
W 1000
0
500
iv
i c
m
0- 0
16.0 18.0 20.0 22.0 24.0 26.0 28.0
1350
Job No. 7847
Lab No. F23-130
0
30.0 32.0 34.0
Method : A
Max. Particle Size: Minus No. 4
Ydmax= 97.0
130.0
wopt% = 23.0
125.0
Fine Gs = 2.70
120.0
USCS = CH
Wet Density
LL = 65
115.0
PI = 36
O
As-Rec'd Moist.
110.0
Q
22.2 %
o
_.
105.0
U
Q
0
100.0
0
A
y
95.0
_
Dry Density
Zero Air Voids
90.0
85.0
800
16.0 18.0 20.0 22.0 24.0 26.0 28.0
Moisture Content (Percent of Dry Weight)
Prepared by Fort Worth Soil Mechanics Lab
1 /12/2023
30.0 32.0 34.0

Compaction and Penetration Resistance
ASTM D698
White Rock Dairy, NC
Anson EQIP AWSP Field No. TP-22-7
Q 2000
UU
R 1500
M
1000
c
500
d
d
a 0
16.0
d qG n
130.0
125.0
120.0
115.0
w
Q
0 110.0
w
V
am
E 105.0
0
U
0
N 100.0
c
m
0
95.0
Job No. 7847
Lab No. F23-131
18.0 20.0 22.0 24.0 26.0 28.0 30.0 32.0 34.0
Method : A
Max. Particle Size: Minus No. 4
YdmaX-
101.5
WOPt% =
20.0
_
.r_
Fine Gs =
2.70
n
w
USCS =
CH
Wet Density ..
_ .
..___
_ ....
LL =
52
PI =
30
-
As-Rec'd Moist.
_
21.84 %
01-
FT
I
-- --
-
Dry Density
Zero Air
Voids
90.0
85.0
16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 32.0 34.0
Moisture Content (Percent of Dry Weight)
Prepared by Fort Worth Soil Mechanics Lab
4/19/2023

White Rock Farms, LLC (Dairy)
Clay liner Design
5/18/2023
By: Samuel Bingham, PE
Soil Mechanics Report completed on April 20, 2023. See
conclusions and recommendations in the report for general
construction recommendations for the compacted liner project.
Also, see construction specification for clay liner.
Report indicates that clay liner material from pits 22-4
and 22-6 are not dispersive. Clay material from pits 22-7 may
be dispersive. Since dispersion can vary in intensity within a
short distance and possible dispersive soil was found at site,
additional depth of cover over clay liner is planned at the
site. While test results of permeability indicate that a waste
storage depth of 16 feet is possible, the waste storage depth
will be reduced to 12 feet to reduce erosion pressure on side
slopes of waste pond. Clay will be stockpiled from clay
material located in areas that tested nondispersive (i.e.,
primarily the footprint of waste storage pond).
The protective material over clay liner will be l' in the
waste pond. The NDCSMC-Fort Worth also recommends the use of a
1-foot soil cover to protect the compacted soil liner by
minimizing cracking due to wetting/drying cycles. Clay material
(CH) is prone to shrink and swell due to changing moisture
conditions. The weathered bedrock (Triassic Shale) under the
clay liner was described as easy to excavate in geology report.
With the fine texture of the weathered bedrock beneath the
liner, clay liner erosion is not anticipated to be a problem
under liner.

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