SW6220505_Soils/Geotechnical Report_20220607

Scott Cole, NCLSS
312 Copples Road Ext
Asheboro, NC 27205
[phone]
Double D Engineering, PLLC
Attn: Mr. Lee Humphrey
150 S. Page Street
Southern Pines, NC 28387
March 21, 2022
Re: Seasonal High -Water Table Identification and Soil Infiltration Rates: Rockfish Road site, Raeford,
NC; Hoke County NC parcel 494750301009.
Soil conditions and infiltration rates were evaluated and measured on the above -referenced property within
the proposed storm water BMP device. Work was conducted in accordance with Parts A-2 and C-1 of the
North Carolina Department of Environmental Quality Stormwater Design Manual. Soil samples were
evaluated with a hand auger.
SEASONAL HIGH WATER TABLE IDENTIFICATION
Seasonal High Water Table depth is determined by field evaluation for soil wetness conditions which are
indicated by the presence of redoximorphic (rdox) features with chroma colors of 2 or less (in Munsell
color notation) in mottles or the horizon matrix, and at times, saturated soil conditions and/or free water
within the soil profile. Colors of chroma 2 or less due to relic minerals from parent material (underlying
rock), anaerobic activity created by placement of fill material, or soil textural class transitions (perched
water) are not considered as indicators for seasonal high water. Upon determination of SHWT depth, an
additional 6" will be deducted from the observed depth to account for capillary fringe water movement
above the SHWT. Stormwater infiltration trenches are designed to ensure the lowest point is at least two
feet above the Seasonal High Water Table (SHWT).
SATURATED HYDRAULIC CONDUCTIVITY Mgt)
Soils evaluated on this property are typical of those within the Johnston and Blaney Soil series. These soils
are moderately well drained soils with varying rates of permeability. Infiltration rates are measured to
determine if soil conditions are suitable for the installation of stormwater infiltration devices. Infiltration
rates are measured using a Johnson Constant Head Permeameter. Measurements are recorded at varying
intervals until equilibrium was reached.
The SHWT and Infiltration rates for the stormwater BMP devices are reported for each proposed
location in the tables below.
BMP Device Site #1
Test Location
SHWT
Munsell Color
Ksat #1
Ksat #2
Ksat #3
(feet below
Notation
round surface
11' bgs
5Y 8/1
0-18"
18-50"
5011+
BMP Site 1
2.5Y 7/1
Sandy Loam
Sandy Clay
Exp.
Elevation 205'
8" / hour
Loam (heavy)
Clay/Heavy
2.5" / hour
Redox
Not Measured

Scott Cole, NCLSS
312 Copples Road Ext
Asheboro, NC 27205
[phone]
BMP Device Site #2
Test Location
SHWT
Munsell Color
Ksat #1
Ksat #2
Ksat #3
(feet below
Notation
round surface
10' bgs
5Y 8/1
0-24"
24-50"
5019+
BMP Site 2
2.5Y 7/1
Sandy Loam
Silty Clay
Exp.
Elevation 189'
8" / hour
2.5" / hour
Clay/Heavy
Redox
Not Measured
BMP Device Site #3
Test Location
SHWT
Munsell Color
Ksat #1
Ksat 92
Ksat #3
(feet below
Notation
round surface
9' bgs
5Y 8/1
0-36"
3659+
N/A
BMP Site 3
2.5Y 7/1
Sandy Loam
Exp.
Elevation 184'
8" / hour
Clay/Heavy
Redox
Not Measured
BMP Device Site #4
Test Location
SHWT
Munsell Color
Ksat #1
Ksat #2
Ksat #3
(feet below
Notation
round surface
9' bgs
5Y 8/1
0-24"
24-48"
4811+
BMP Site 4
2.5Y 7/1
Sandy Clay
Sandy Clay
Exp.
Elevation 197'
Loam
0.2" / hour
Clay/Heavy
2.5" / hour
Redox
Not Measured
CONCLUSION
Field evaluation of hydraulic conductivity provides estimations of soil infiltration rates; however, methods
used to measure these rates can influence the results. Side walls of the bore hole are "smeared" by the soil
auger as the hole is prepared and loose soil in the bottom of the hole is placed in suspension when water is
applied; both of these factors negatively influence water infiltration rates. To help overcome these issues,
after excavation of each infiltration trench, it is recommended the trench bottom and sidewalls be raked and
dusted with pulverized limestone. These are practices that have been in place within the on -site wastewater
industry to help loosen the soil and aid in restoration of soil structure.
I am pleased to be of service in this matter and can be contacted at
questions concerning information within this report.
Thank you,
-� a
Scott Cole
North Carolina Licensed Soil Scientist
should you have any
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Proposed Stormwater BMP #3 i
a
f' SHWT: 9' bgs
SHWT Elevation: 184'
Ksat 0-36" SL: 8" 1 hour _
- Ksat 36"+ SCL (heavy): Not Measured
Proposed Stormwater BMP #4
SHWT: 9' bgs \• «,,.. jr �/` .�' �\::,..�
SHWT Elevation: 197' �• �`° �•,
Ksat 0-24" SCL: 2.5" 1 hour
Ksat 24"-48" SC: .2" / hour
Ksat 48"+ Expansive Clay: Not Measured
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�, `, f, ;{ tiff r ;1 � . � z l � ,_ � 1•.,� `' � i
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Proposed Stormwater BMP #2 =•-�=F:•Ea
SHWT: 10' bgs
SHWT Elevation: 189" �\ 1 •��'.►
Ksat 0-24" SL: 8" / hour M£..
{ Ksat 24"-50" SCL (heavy): 2.5" / hour (�
{ i:= Ksat 50"+ Expansive Clay: Not Measured k
i
Proposed Stormwater BMP #1 '
,.._.,X orri
_r
SHWT: 11' bgs
SHWT Elevation: 205'
Ksat 0-18" SL: 8" / hour
Ksat 18"-50" SCL (heavy): 2.5" / hour
'{ Ksat 50"+ Expansive Clay: Not Measured \
1 inch = 300 feet