HomeMy WebLinkAboutSW3231104_Soils/Geotechnical Report_20240730 May 3, 2023 SUMMIT
Mr. Joseph Pace ENGINEERING • LABORATORY•TESTING
Roman Catholic Diocese of Charlotte A Universal Engineering Sciences Company
1123 South Church Street
Charlotte, NC 28203
Email: JAPace@rcdoc.com
Subject: Estimated Seasonal High Water Table (ESHWT) Determinations
Holy Spirit Catholic Church
537 NC-16 Business
Denver, North Carolina
SUMMIT Project No. 3944.G0579
Dear Mr. Pace:
SUMMIT Engineering, Laboratory and Testing, Inc. (SUMMIT) is pleased to submit this letter
summarizing our observations of the soil test borings as related to Estimated Seasonal High
Water Table Elevation (ESHWT) determinations in the proposed stormwater BMP ponds to be
constructed for the proposed project listed above. This report contains a brief description of the
project information provided to us, general site and subsurface conditions revealed during this
exploration.
PURPOSE OF EXPLORATION
The primary purpose of this exploration was to obtain information regarding the subsurface
conditions in the proposed stormwater BMP ponds, assess the engineering characteristics of the
subsurface materials, and determination of the estimated seasonal high water table mark (if
evident).
3575 Centre Circle Drive, Fort Mill, SC 29715 summit-companies.com
Summary of ESHWT Determinations SUMMIT Project No. 3944.G0579
Holy Spirit Catholic Church May 3, 2023
This report contains the following items:
• Site Vicinity Map and Boring Location Plan,
• Summary of Test Boring Observations, visual soil classifications and descriptions,
• A general review of the subsurface soils and estimated seasonal high water table depth
from existing ground surface (if evident),
• Groundwater level measurements.
EXPLORATION PROCEDURES
SUMMIT visited the site on April 26th, 2023 and performed two (2) soil test borings (identified as
SW-10 and SW-11) in the proposed stormwater BMP ponds. The approximate locations of the
borings are shown on Figure 2 — "Boring Location Plan" provided in Appendix 2. The client
(Roman Catholic Diocese of Charlotte) provided SUMMIT a plan sheet titled "Phase I Site Plan"
prepared by William Heyer Architect, dated March 9, 2023 that indicated the approximate
locations of the proposed stormwater BMP ponds. The borings were located by professionals
from our office using the provided plan, recreation-grade handheld GPS, existing topography,
and aerial maps as reference. Since the boring locations were not surveyed, the location of the
borings should be considered approximate. We recommend the actual boring location be
surveyed to determine the actual boring location and existing ground elevation.
The soil test borings were performed using an ATV-mounted CME 550X drill rig. Borings SW-10
and SW-11 were extended to approximate depths of 10 feet below the existing ground surface.
Hollow-stem, continuous flight auger drilling techniques were used to advance the boring into
the ground. Standard Penetration Tests (SPT) were performed within the mechanical boring
continuously to the termination depth in general accordance with ASTM D 1586. When properly
evaluated, the SPT results can be used as an index for estimating soil strength and density. In
conjunction with the penetration testing, representative soil samples were obtained from the
test location and returned to our laboratory for visual classification and potential laboratory
testing. The soil samples collected were visually examined and classified in general accordance
with ASTM D-2488. The Munsell Soil Color Charts (2009 Revision) were used to identify the hue,
value, and chroma of soil samples. Water level measurements were attempted at the
3575 Centre Circle Drive, Fort Mill, SC 29715 summit-companies.com
Summary of ESHWT Determinations SUMMIT Project No. 3944.G0579
Holy Spirit Catholic Church May 3, 2023
termination of drilling. The classification symbols are depicted on the "Boring Log" provided in
Appendix 2.
GENERALIZED SUBSURFACE STRATIGRAPHY
General subsurface conditions observed during our geotechnical exploration are described
herein. For more detailed soil descriptions and stratifications at the test location, the respective
"Boring Log" provided in Appendix 2 should be reviewed. The horizontal stratification lines
designating the interface between various strata represents approximate boundaries.
Transitions between different strata in the field may be gradual in both the horizontal and vertical
directions.
Beginning from the ground surface, a layer of topsoil (surficial organic soils) was observed in
Boring SW-11 with a thickness of approximately 3 inches. Fill (disturbed) soils were encountered
beneath the topsoil or at ground surface that consisted of Elastic Silts (MH). Beneath the fill soils,
residual (undisturbed) soils were encountered that consisted of elastic silts (MH) and sandy silts
(ML). Partially Weathered Rock (PWR) and auger refusal materials were not encountered in the
borings.
GROUNDWATER LEVEL MEASUREMENTS
At the time of drilling, groundwater was not observed in the borings. After waiting more than 24
hours, water was not observed in the borings. It should also be noted that groundwater levels
tend to fluctuate with seasonal and climatic variations, as well as with some types of construction
operations. Therefore, water may be encountered during construction at depths not indicated
in the borings performed for this exploration.
ESTIMATED SEASONAL HIGH WATER TABLE
ESHWT is defined as the shallowest depth to a wet soil layer as a result of"true" or "permanent"
groundwater at any time during the year. The ESHWT is typically identified with a change in the
color of the soil layer due to water staining (typically, gray redoximorphic depletions and
3575 Centre Circle Drive, Fort Mill, SC 29715 summit-companies.com
Summary of ESHWT Determinations SUMMIT Project No. 3944.G0579
Holy Spirit Catholic Church May 3, 2023
mottling). Spots or blotches of different color or shades of color interspersed with a dominant
color in soil, commonly referred to as mottling. Mottling is a historic indication for the presence
of groundwater caused by intermittent periods of saturation and drying, and may be indicative
of poor aeration and impeded drainage. Mottling is a "general indication of groundwater" flow
through this layer, but it is not known whether the groundwater flow was recent.
CONCLUSIONS
Based on our observations, ESHWT indicators were evident in soils sampled in Borings SW-10,
and were not evident in soils sampled in Boring SW-11. Please note that even though ESHWT
indicators were not evident in Borings SW-and SW-, perched water conditions can develop above
a low permeable material such as partially weathered rock (PWR). Perched water conditions
differ from the "true" or"permanent"water table.A perched water table is water standing above
an unsaturated zone and is often influenced by soil conditions, and occurrence of less permeable
soils. Where the ESHWT is defined as the shallowest depth to a wet soil layer as a result of"true"
or "permanent" groundwater at any time during the year. The BMP designer should take into
consideration that perched water conditions may exist above the low permeable PWR stratum.
The following table summarizes the results of the borings and our observations.
Summary Table of the Boring Results and Our Observations
Approx.
GW Depth Approx. Auger
Boring ESHWT GW Depth After PWR Refusal
Test Depth Depth ATD 24 Hours Depth Depth
Location (Feet)1 (Feet)1 (Feet)1 (Feet)1 (Feet)1 (Feet)1
SW-10 10 8 NE NE NE NE
SW-11 10 NE NE NE NE NE
1 Depths from existing ground surface.
NE — Not Encountered in boring
The analyses submitted in this report were based, in part, on data obtained from this exploration.
If the above-described project conditions are incorrect or changed after the issuing of this report,
3575 Centre Circle Drive, Fort Mill, SC 29715 summit-companies.com
Summary of ESHWT Determinations SUMMIT Project No. 3944.G0579
Holy Spirit Catholic Church May 3,2023
or subsurface conditions encountered during construction are different from those reported,
SUMMIT should be notified and these recommendations should be re-evaluated based on the
changed conditions to make appropriate revisions. We have prepared this report according to
generally accepted geotechnical engineering practices. No warranty, express or implied, is made
as to the professional advice included in this report.
CLOSING
SUMMIT appreciates the opportunity to provide our professional services for you on this project.
If you have any questions concerning the information in this proposal or if we may be of further
service, please contact us at 704.504.1717.
Sincerely,
SUMMIT ENGINEERING, LABORATORY&TESTING, INC.
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Geotechnical Dept. Manager Assistant Project Manager
LIST OF APPENDICES
Appendix 1 Figure No. 1—Site Vicinity Map
Figure No. 2— Boring Location Plan
Appendix 2 Boring Logs
3575 Centre Circle Drive, Fort Mill, SC 29715 summit-companies.com
Summary of ESHWT Determinations SUMMIT Project No. 3944.G0579
Holy Spirit Catholic Church May 3, 2023
SUMMIT
ENGINEERING • LABORATORY • TESTING
A Universal Engineering Sciences Company
APPENDIX 1
Figures
3575 Centre Circle Drive, Fort Mill, SC 29715 summit-companies.com
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Figure 1 537 NC-16 Business
Site Location Plan Denver, North Carolina SUMMIT
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3575 Centre Circle
SUMMIT Project No.: 3944.G0579 Fort Mill,South Carolina 29715
SCALE: NTS (803)504-1717
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3 SPACES BASED ON DEVELOPMENT STANDARDS 229 /r . -`" /r I e
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'DSED SPACES 291 / /r( II .PAC _ ;
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Figure 2 Holy Spirit Catholic Church /1.11
Boring Location Plan 537 NC-16 Business SUMMITDenver, North Carolina .,m.4-I.MAN.r-TC'}Tti[
Approx. Soil Test Boring Location ctl.a16IE•tf46'9 kIA9NCo.P.rV
3575 Centre Circle
SUMMIT Project No.: 3944.G0579 Fort Mill,South Carolina 29715
SCALE: NTS (803)504-1717
Summary of ESHWT Determinations SUMMIT Project No. 3944.G0579
Holy Spirit Catholic Church May 3, 2023
SUMMIT
ENGINEERING • LABORATORY • TESTING
A Universal Engineering Sciences Company
APPENDIX 2
Boring Logs
3575 Centre Circle Drive, Fort Mill, SC 29715 summit-companies.com
SUMMIT ENGINEERING KEY TO SYMBOLS
/MIK 3575 CENTRE CIRCLE
FORT MILL,SC 29715
SUMMIT 704-504-1717
.,.maiEti...E,soon..,Company CPAYNE@SUMMIT-COMPANIES.COM
CLIENT Roman Catholic Diocese of Charlotte PROJECT NAME Holy Spirit Catholic Church
PROJECT NUMBER 3944.G0579 PROJECT LOCATION Denver, North Carolina
LITHOLOGIC SYMBOLS SAMPLER SYMBOLS
(Unified Soil Classification System)
Standard Penetration Test
■ ASPHALT: Asphalt
BLANK
I FILL: Fill (made ground)
tin GW: USCS Well-graded Gravel
liffi
MH: USCS Elastic Silt
MLS: USCS Sandy Silt
TOPSOIL: Topsoil
WELL CONSTRUCTION SYMBOLS
ABBREVIATIONS
LL -LIQUID LIMIT(%) TV -TORVANE
PI -PLASTIC INDEX(%) PID -PHOTOIONIZATION DETECTOR
W -MOISTURE CONTENT(%) UC -UNCONFINED COMPRESSION
DD -DRY DENSITY(PCF) ppm -PARTS PER MILLION
NP -NON PLASTIC v, Water Level at Time
-200 -PERCENT PASSING NO. 200 SIEVE Drilling, or as Shown
PP -POCKET PENETROMETER(TSF) Water Level at End of
1 Drilling, or as Shown
w Water Level After 24
Hours, or as Shown
// SUMMIT ENGINEERING BORING NUMBER SW-10
lik 3575 CENTRE CIRCLE
FORT MILL,SC 29715 PAGE 1 OF 1
SUMMIT 704-504,1 7 1 7
<�M,.olEr,E,..Hnq �Co m CPAYNE@SUMMIT-COMPANIES.COM
CLIENT Roman Catholic Diocese of Charlotte PROJECT NAME Holy Spirit Catholic Church
PROJECT NUMBER 3944.G0579 PROJECT LOCATION Denver, North Carolina
DATE STARTED 4/26/23 COMPLETED 4/26/23 GROUND ELEVATION HOLE SIZE 6 inches
DRILLING CONTRACTOR SUMMIT GROUND WATER/CAVE-IN:
DRILLING METHOD Hollow Stem Auger AT TIME OF DRILLING ---GW NE ATD
LOGGED BY J Parrish CHECKED BY C.Payne AT END OF DRILLING ---GW NE>24 hrs
NOTES See Figure 2"Boring Location Plan"for Approx. Boring Location AFTER DRILLING ---
w o A SPT N VALUE A
0 U >-ct } cow 0 20 40 60 80 100
_ I—w EC^ Hn
It
Q ,..,1-
O MATERIAL DESCRIPTION J 2 >of �O n Q I M
" J o O. m O> 0 20 40 60 80 100
(3 2z () oz
w < ❑FINES CONTENT(%)❑
co
0 20 40 60 80 100
:.: (MH)FILL:
-$5 Firm Red(10R,4/6)Sandy Elastic SILT
_ - �_�♦_ SPT 4-2-3-5
I I 1 (5)
Firm Red(10R,4/6)Sandy Elastic SILT
(ML)Stiff Moist Red(10R,5/8)Slightly Clayey Sandy SILT
SPT 2-4-8-11
2 (12)
(ML)Firm Red(10R,5/8)Slightly Clayey Sandy SILT
s.o SPT 2-3-5-5
3 (8)
(ML)Firm Red(10R,5/8)Slightly Clayey Sandy SILT with
Manganese Stains SPT 3-4-4-5
4 (8)
(ML)Firm Red(10R,5/8)and white(7.5YR,9.5/1)Slightly Clayey
Sandy SILT with Manganese Stains SPT 2-2-3-4
5 (5)
10.0
Bottom of Boring at 10 feet bgs, Boring Terminated
15.0
20.0
// SUMMIT ENGINEERING BORING NUMBER SW-11
lik 3575 CENTRE CIRCLE
FORT MILL,SC 29715 PAGE 1 OF 1
SUMMIT 704-504-1717
<�M,.olEr,E,..Hnq ScioneasCompany CPAYNE@SUMMIT-COMPANIES.COM
CLIENT Roman Catholic Diocese of Charlotte PROJECT NAME Holy Spirit Catholic Church
PROJECT NUMBER 3944.G0579 PROJECT LOCATION Denver, North Carolina
DATE STARTED 4/26/23 COMPLETED 4/26/23 GROUND ELEVATION HOLE SIZE 6 inches
DRILLING CONTRACTOR SUMMIT GROUND WATER/CAVE-IN:
DRILLING METHOD Hollow Stem Auger AT TIME OF DRILLING ---GW NE ATD
LOGGED BY J Parrish CHECKED BY C.Payne AT END OF DRILLING ---GW NE>24 hrs
NOTES See Figure 2"Boring Location Plan"for Approx. Boring Location AFTER DRILLING ---
w o A SPT N VALUE A
0 U } ci w 0 20 40 60 80 100
I-w �^ H�
L"O MATERIAL DESCRIPTION J 2 >of �O n Q
J a O. m O> 0 20 40 60 80 100
(3 2z () oz
w < ❑FINES CONTENT(%)❑
0 20 40 60 80 100
�;\ Approx.3"of Topsoil 7
- (MH)�i�i�i
�.�.�. FILL: SPT 2-2-2-2
Soft Red(10R,4/6)Sandy Elastic SILT / 1 (4)
(MH)RESIDUUM::
Soft Red(10R,4/6)Sandy Elastic SILT
(MH)FILL:
Stiff Red(10R,4/6)Sandy Elastic SILT SPT 2-4-5-6
2 (9)
(MH)FILL:
s.o Very Stiff Red(10R,4/6)Sandy Elastic SILT with Rock SPT 2-12-12-14
Fragments
3 (24)
(ML)RESIDUUM:
Soft Moist Red(10r,5/8)Slightly Clayey Sandy SILT SPT 2-2-2-3
4 (4)
•
(ML)Firm Moist Red(10r,5/8)and White(7.5Y,9.5/1)Slightly
Clayey Sandy SILT
SPT 1-2-3-3
5 (5)
1 0.0
Bottom of Boring at 10 feet bgs, Boring Terminated
15.0
20.0