SW6230104_Soils/Geotechnical Report_20230126

PIEDMONT
4: ENVIRONMENTAL
ASSOC I A T E S, P. A.
1/4/2023
Intertek PSI
c/o: Andrew Steege
5021-A West W.T. Harris Blvd
Charlotte, NC 28269
Project # 3904
This report details the findings of a seasonally high-water table evaluation and soil
conductivity test at the Petco site located at 2400 W Cumberland St., Dunn NC. Your
office gave the location of the proposed storm water control measure (SCM). G.
Christopher Murray, Licensed Soil Scientist 91284, conducted the evaluation in January,
2022. The results were as follows:
Seasonally High -Water Table Soil Borings
Soil borings were conducted at the locations specified on the attached map, and the depth
to the seasonally high-water table (SHWT) was determined by observing soil indicators,
also known as redoximorphic features.
The soil boring location is shown on the attached map. Redoximorphic features were
observed from 86 inches below the ground surface to the cessation of this boring at
108 inches below ground surface. Fill material was observed from the surface to 108
inches below ground surface. The native elevation in this area was approximately 172'.
Boring ID
SHWT Depth inches
SHWT Elevation feet
1
86-108
164-163
Infiltration Testing
Infiltration tests were also conducted within the proposed SCM. Saturated hydraulic
conductivity (ksat) testing was utilized to predict infiltration. This test was conducted
approximately 9 feet below ground surface at the boring location referenced above.
The constant head well permeameter technique (also known as shallow well pump -in
technique and borehole permeameter method) was utilized to complete the ksat tests.
This procedure is described in Methods of Soil Analysis, Part 1., Chapter 29 — Hydraulic
Conductivity of Saturated Soils: Field Methods, 29 — 3.2 Shallow Well Pump In Method,
pp. 758-763 and in the Soil Science Society of America Journal, Vol. 53, no. 5, Sept. —
Oct. 1989, "A Constant -head Permeameter for Measuring Saturated Hydraulic
Conductivity of the Vadose Zone" and "Comparison of the Glover Solution with the
Simultaneous — Equations Approach for Measuring Hydraulic Conductivity." A volume
of water was applied and measured with time until a steady state of water flow was
216 S. Swing Rd., Suite 1 Greensboro, NC 27409 336-662-5487

achieved. This volume/time with steady state was used to calculate the saturated
hydraulic conductivity of the subsoil by the Glover equation.
The ksat rate calculated for this test is given below:
Intertek PSI, Proposed Stormwater Device Testing Ksat Data
Site Soil Horizon Depth(") Ksat (in/hr)
Test 1 Various/Fill 108 0.019
Geometric Mean Ksat: 0.019
Piedmont Environmental Associates, PA is pleased to perform this work for you. If you
have any questions, please feel free to call [phone].
Sincerely,
G. Christopher Murray
N.C. Licensed Soil Scientist 91284

Layout Diagram/Site Plan - West Cumberland St.
PIEDMONT Job#3904
ENVIRONMENTAL 216 S. Swing Rd. Suite 1 Date: 12/21/2022
ASS OCI A r E s, P. A. Greensboro, NC 27409 Client: Intertek PSI
pied montsoil.com County: Harnett
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