SW6211203_Soils/Geotechnical Report_20211227

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
September 21, 2021
Re: Seasonal High -Water Table Identification and Soil Infiltration Rates: Proposed McCain Gas Station;
Hoke County NC Parcel (Altpamo) 19186 (6797 Aberdeen Road, Raeford, NC)
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 (redox) features with a chroma of 2 or less (in Munsell color
notation) in mottles or the horizon matrix. 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).
The SHWT for this project was not observed within 15' of the ground surface. Soil conditions
evaluated to elevation 4221.
SATURATED HYDRAULIC CONDUCTIVITY (Ksat)
Soils evaluated across most of this property are typical of those within the Blaney Loamy Sand series (BaB).
These are deep, well drained, moderately permeable soils often found on side slopes and narrow ridges.
Infiltration rates were measured to determine if soil conditions were suitable for the installation of
stormwater infiltration trenches. Infiltration rates were measured using a Johnson Constant Head
Permeameter. Measurements were recorded at varying intervals until equilibrium was reached.
A summary of observations within the proposed Stormwater BMP Device is shown in the table below.
BMP Device Site
Test Location
SHWT
(feet below
Munsell Color
Notation
Ksat #1
Ksat #2
round surface
1
Not Observed
N/A
04'
4'-15'
within 15' of
Loamy Sand /
Loamy Sand /
ground surface
Sand
Sandy Loam
18" / hour
10" / hour

Scott Cole, NCLSS
312 Copples Road Ext
Asheboro, NC 27205
[phone]
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 your convenience should you have any
questions concerning information within this report.
Thank ou,
Scott Cole
North Carolina Licensed Soil Scientist
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BMP Site
SHWT: Not Observed within 15' of surface
Ksat 0-4' Loamy Sand / Sand: 25" / hour
Ksat 4-15' Loamy Sand / Sandy Loam: 10" / hour
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