SW3230303_Soils/Geotechnical Report_20230803

Appendix H
Geotechnical Report

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r&R FRDEHLING & ROBERTSON , INC .
Report of Subsurface Exploration
And Geotechnical Engineering Services
Twelve Mile Creek WRF 9.0 MGD Expansion
Union County, North Carolina
Prepared for:
Hazen & Sawyer, Inc.
9101 Southern Pine Boulevard, Suite 250
Charlotte, North Carolina 28273
Prepared by:
Froehling & Robertson, Inc.
3300 International Airport Drive, Suite 600
Charlotte, North Carolina 28208
16 September 2022
F&R Project No. 63A-0012
Corporate HQ: 3015 Dumbarton Road Richmond,Virginia 23228 T 804.264.2701 F 804.264.1202 www.fandr.com
VIRGINIA • NORTH CAROLINA • MARYLAND • DISTRICT OF COLUMBIA
A Minority-Owned Business

r8cRFROEHLING
ROBERTSON
Engineering Stability Since 1881
NC License No. F-0266
F&R Project No.:63A-0012 16 September 2022
Mr. Michael D. Parker, PE
Hazen and Sawyer
9101 Southern Pine Boulevard, Suite 250
Charlotte, North Carolina 28273
Re: Report of Subsurface Exploration and Geotechnical Evaluation
Twelve Mile Creek WRF 9.0 MGD Expansion
Union County, North Carolina
Mr. Parker:
The enclosed report presents the results of the subsurface exploration and geotechnical evaluation
undertaken by Froehling & Robertson, Inc. (F&R) in connection with the above referenced project. Our
services were performed in general accordance with the scope of work included in the Subcontract
Agreement for Professional Services, between Hazen and Sawyer and F&R, dated 27 January 2022. This
report presents our understanding of the project, reviews our exploration procedures, describes general
subsurface conditions at the boring locations, and presents our geotechnical evaluations and
recommendations.
Sincerely,
FROEHLING & ROBERTSON, INC.
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Alexander T. Kuczero, P.E. ',,, R T.• .�`,, 6EiVew R. Frank, P.E.
Geotechnical Engineer Regional Senior Geotechnical Engineer
Email Distribution: [e-mail]; [e-mail];
F:\Projects 63A\63A-0012(Hazen and Sawyer-12-Mile Creek WRF 9.0 MGD Expansion)\Report\63A-0012(Hazen and Sawyer-12-Mile Creek WRF 9.0 MGD Expansion)GEO.RPT.docx
704.596.2889 3300 International Airport Drive A Minority-Owned Business
Suite 600
Charlotte, NC 28208

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TABLE OF CONTENTS
SECTION PAGE
EXECUTIVE SUMMARY V
1.0 INTRODUCTION 1
1.1 SITE DESCRIPTION AND PROJECT INFORMATION 1
1.2 SCOPE OF SERVICES 3
2.0 EXPLORATION PROCEDURES 4
2.1 SUBSURFACE EXPLORATION 4
2.2 LABORATORY TESTING 6
3.0 REGIONAL GEOLOGY&SUBSURFACE CONDITIONS 7
3.1 REGIONAL GEOLOGY 7
3.2 SUBSURFACE CONDITIONS 7
3.2.1 GENERAL 7
3.2.2 SURFICIAL MATERIALS 8
3.2.3 FILL MATERIALS 8
3.2.4 RESIDUAL SOILS 8
3.2.5 PARTIALLY WEATHERED ROCK 8
3.2.6 AUGER REFUSAL MATERIALS 9
3.2.7 ROCK 10
3.2.8 GROUNDWATER CONDITIONS 10
3.3 LABORATORY TEST RESULTS 11
4.0 DESIGN RECOMMENDATIONS 12
4.1 GENERAL 12
4.2 FOUNDATION RECOMMENDATIONS 12
4.2.1 INFLUENT PUMP STATION 2 12
4.2.2 ODOR CONTROL—INFLUENT 13
4.2.3 SECONDARY CLARIFIERS 14
4.2.4 RAS PUMP STATION 3 15
4.2.5 CHEMICAL FACILITY 16
4.2.6 GENERAL SHALLOW FOUNDATION DESIGN RECOMMENDATIONS 16
4.3 CONCRETE SLABS-ON-GRADE 16
4.4 SEISMIC DESIGN CRITERIA 17
4.5 LATERAL EARTH PRESSURES 17
4.6 TEMPORARY EXCAVATION SUPPORT/SHORING 19
5.0 CONSTRUCTION RECOMMENDATIONS 20
5.1 GENERAL 20
5.2 SITE PREPARATION 20
5.3 SHALLOW FOUNDATION CONSTRUCTION 20
5.4 CONTROLLED STRUCTURAL FILL 21
5.5 SURFACE WATER CONTROL 22
5.6 GROUNDWATER CONDITIONS 22
5.7 EXCAVATION CHARACTERISTICS 23
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5.8 EXCAVATION GUIDELINES 24
5.9 TEMPORARY SLOPES 25
6.0 CONTINUATION OF SERVICES 26
7.0 LIMITATIONS 27
APPENDIX I
Site Vicinity Map (Drawing No. 1)
Boring Location Plan (Drawing No. 2)
APPENDIX II
Key to Soil Classification
Key to Boring Log Rock Classification
Soil Classification Chart
Subsurface Profiles (A and B)
Boring Logs (B-1 through B-14, B-1A, and B-7A)
Rock Core Summary and Photograph (B-1A and B-7A)
APPENDIX III
Material Test Reports
Proctor Reports
APPENDIX IV
Extent of Select Backfill for Retaining Walls (Drawing No.3)
APPENDIX V
GBA Publication "Important Information about This Geotechnical Engineering Report"
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EXECUTIVE SUMMARY
This Executive Summary is provided as a brief overview of our geotechnical engineering
evaluation for the project and is not intended to replace more detailed information contained
elsewhere in this report. As an overview, this summary inherently omits details that could be
very important to the proper application of the provided geotechnical design recommendations.
This report should be read in its entirety prior to implementation into design and construction.
The Project Information section of this report should be particularly reviewed by project
designers to confirm that the geotechnical engineer's understanding of the project concurs with
the current project parameters at the time of project design.
• The subsurface exploration consisted of fourteen (14) test borings (designated as B-1
through B-14)and rock coring in two offset borings(designated B-1A and B-7A)that were
performed between 5 and 25 July 2022. Site subsurface conditions generally consisted of
surficial soils underlain by existing fill, residual soils, partially weathered rock (PWR), and
auger refusal materials.
• The planned structures may be supported on shallow foundation systems based on the
anticipated settlements and our understanding of settlement tolerances for each
structure.
o To limit the anticipated settlement below the valve vault portions of the Influent
Pump Station 2 and RAS Pump Station 3, we recommend that ABC stone be
utilized to backfill from any temporary slopes excavated in PWR or rock to the
valve subgrade.
• PWR was encountered in each of the borings below the fill soils or residual soils at depths
of approximately 2 to 17 feet below existing site grades. Auger refusal materials were
encountered in 9 of the 15 borings at depths ranging from 14.3 to 28.4 feet below the
existing ground surface, as indicated in the table above. We anticipate that difficult
excavation techniques will be needed in areas where PWR or auger refusal materials were
encountered.
• Based on the boring SPT N-values, a seismic Site Classification of"C" was determined for
each of the planned structures, except for the Chemical Facility. The boring data further
indicates that a seismic Site Classification of"D" should be used for the Chemical Facility.
• Water was also noted on the split spoon samples recovered from borings B-1 and B-3 at
depths of 23.5 feet and 23 feet below existing grade (approximate elevations of 478 feet
and 485 feet), respectively. In each of these borings the wet sampler was about 2 feet
above auger refusal. The encountered water could have been perched over the auger
refusal materials / rock and may not represent sustained groundwater levels at those
locations. However, based on the planned Influent Pump Station 2 wetwell subgrade
elevation of 468.50 feet, some groundwater or perched water may be encountered
during excavation and construction.
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1.0 INTRODUCTION
1.1 Site Description and Project Information
Project information was provided to F&R by Hazen and Sawyer (H&S) via email and phone
correspondence. F&R was provided with new or refined project information as our services were
being performed on this project such that our project understanding evolved over the course of
our services. The following plans and information, prepared by H&S unless noted otherwise,
were also provided:
• 30%Drawings—Markups v2.pdf—Twelve Mile Creek WRF 9.0 MGD Expansion
• 30831-061 — Grading Plans.pdf— 30% Drawings Sheets C30 through C34 with some
sketched revisions
• Structural loads were provided in an email from Mr. Colby Whiteley, PE on 22 July 2022
F&R understands that the project will consist of a 9.0 MGD (Million Gallons per Day) expansion
of the existing 12-Mile Creek Water Reclamation Facility (WRF) at 3104 Providence Road South
in Waxhaw, Union County, North Carolina (Union County Parcel No. 06162001). The planned
expansion will include the addition of an influent pump station, odor control, two secondary
clarifiers (one future), an RAS pump station, a chemical facility, and multiple piping additions.
The areas of the proposed structures are adjacent-to or between existing structures and were
generally grass or brush covered at the time of this study.
The following is our understanding of each of the planned structures, including structure type,
resulting gross foundation bearing contact pressures, and required grading and excavation
depths:
• Influent Pump Station: Influent Pump Station 2 (IPS2) is planned on the southwest side of
the facility,to the west of the existing Influent Electrical Building. We understand that IPS2
will be a cast-in-place concrete structure consisting of a deeper wetwell connected to a
shallower valve vault. F&R was provided with average gross bearing pressures of 4,500
pounds per square foot (psf) and 1,500 psf for the wetwell and valve vault, respectively.
Existing grades in the footprint of IPS2 range from approximately 500 to 507 feet for the
wetwell and 507 to 510 feet for the valve vault. Planned subgrade elevations are 468.50 and
498.00 for the wetwell and valve vault, respectively. Based on these elevations, the
maximum excavation depths of approximately 38 feet and 13 feet will be required for the
wetwell and valve vault, respectively,to reach planned subgrade elevations. We understand
that excavation for construction of the IPS2 will require a temporary excavation support
system due to the proximity of existing facilities to the east of the area.
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• Odor Control —Influent: An Activated Carbon Scrubber, to provide odor control, is planned
to the south of Influent Pump Station 2. We understand the Activated Carbon Scrubber will
be constructed on top of an equipment pad further supported by a 12-inch thick concrete
slab. We were provided with an approximate gross contact pressure of 1,500 psf. Existing
grades in the slab footprint range from about 509 to 510 feet. Based on a provided subgrade
elevation of 510.00 feet, up to about 1 foot of fill will be required to prepare the subgarde
elevation.
• Secondary Clarifiers: Secondary Clarifier 3 and Future Secondary Clarifier 4 are currently
planned in the area in between the four existing secondary clarifiers. We understand the
secondary clarifiers will be approximate 100-foot diameter cast-in-place concrete structures.
The tanks will have a shallow conical bottom with a height of approximately 20 feet and 15
feet at the tank center and walls,respectively. F&R was provided with average gross contact
pressure of 2,000 to 2,500 psf. Existing grades in the footprints of the secondary clarifiers
range from approximately 550 to 551.5 feet for Secondary Clarifier 3 and 548 to 550 feet for
Future Secondary Clarifier 4. F&R was provided with subgrade elevations of 523.67 feet (in
the middle) to 535.50 feet (at the edges). Excavation depths ranging from about 13 to 29
feet from existing grades will be required in the footprints of the secondary clarifiers.
• RAS Pump Station: RAS Pump Station 3 is planned for the area adjacent to the southwest
side of Secondary Clarifier 3 and the northwest side of Future Secondary Clarifier 4. We
understand that the RAS pump station will be a cast-in-place concrete structure consisting
of a deeper wetwell connected to a shallower valve vault. F&R was provided with average
gross bearing pressures of 3,500 psf and 1,500 psf as well as planned subgrade elevations of
523.50 feet and 540.50 feet for the wetwell and valve vault, respectively. Based on an
existing grade of about 550 feet, maximum excavation depths of approximately 27 feet and
10 feet will be required to reach planned subgrade elevations for the wetwell and valve
vault, respectively.
• Chemical Facility: The Chemical Facility will be located to the northeast of existing Secondary
Clarifier 1. We understand the Chemical Facility will have a cast-in-place concrete
foundation and slab with a steel canopy superstructure. F&R was provided with an average
bearing pressure of 2,500 psf. Existing grades in the footprint of the chemical facility range
from approximately 552 to 555 feet. Planned subgrade elevations range from 551.00 to
554.00 feet. Cuts and fills up to about 4 feet and 2 feet, respectively, will be required in the
chemical facility footprint.
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1.2 Scope of Services
The purposes of our involvement on this project were to 1) conduct a subsurface exploration
program, 2) provide the geotechnical evaluations and analyses described below, and 3) prepare
this geotechnical report summarizing our work on the project, providing descriptions of the
subsurface conditions encountered, providing the results and recommendations of our
geotechnical evaluations, and discussing geotechnical related aspects of the proposed
construction. In order to accomplish the above objectives, we undertook the following scope of
services:
1) Reviewed readily available geologic information relative to the project site.
2) Coordinated utility clearance with NC-811.
3) Visited the site to observe existing surface conditions and features.
4) Executed a subsurface exploration program, performed between 5 and 25 July
2022, consisting of fourteen (14) standard penetration test (SPT) borings
(designated as B-1 through B-14) as well as rock coring in two offset borings
(designated as B-1A and B-7A). These borings were drilled to depths ranging
from 14.3 to 45 feet below the existing ground surface.
5) Performed laboratory testing on twelve (12) selected samples from the SPT
borings and three (3) bulk soil samples.
6) Prepared this report summarizing our work on the project, providing
descriptions of the subsurface conditions encountered, presenting the results
of field and laboratory testing, and discussing the results and
recommendations from our geotechnical engineering evaluations and
analyses.
By the nature of the work performed, our field exploration activities resulted in disturbances to
the site. Reasonable efforts were made to lessen potential impacts of the field exploration.
Following groundwater measurements, borings were backfilled with auger cuttings (soil).
Borings performed in paved areas were topped with asphalt cold-patch after backfilling. F&R
assumes no responsibility for borehole subsidence after demobilizing from the site and
recommends that others occasionally observe the boring locations and provide any additional
infill that may be needed.
F&R's geotechnical services did not include topographic or field surveying, development of
quantity estimates, preparation of plans and specifications, or the identification and evaluation
of wetlands or other environmental aspects of the project site.
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2.0 EXPLORATION PROCEDURES
2.1 Subsurface Exploration
The subsurface exploration program, performed between 5 and 25 July 2022, consisted of
fourteen (14)test borings (designated as B-1 through B-14) and rock coring in two offset borings
(designated as B-1A and B-7A). The requested test borings were performed at the approximate
locations provided by the design team and as shown on the attached Boring Location Plan
(Drawing No. 2).
F&R personnel marked test locations in the field by measuring from existing site features. The
test locations should be considered approximate, as they were not surveyed. Boring elevations
were interpolated from the provided grading plans. In consideration of the methods used in their
determination, the test boring locations shown on the attached Boring Location Plans and
elevations shown on the attached Subsurface Profiles and Boring Logs should be considered
approximate.
The test borings were performed in accordance with generally accepted practice using a CME
550X ATV-mounted drill rig equipped with an automatic hammer. Hollow-stem augers were
advanced to pre-selected depths and representative soil samples were recovered with a standard
split-spoon sampler(13/8 in. ID,2 in. OD) in general accordance with ASTM D 1586,the Standard
Penetration Test. Utilizing an automatic hammer, a weight of 140 pounds is freely dropped from
a height of 30 inches to drive the split-spoon sampler into the soil. The number of blows required
to drive the split-spoon sampler three consecutive 6-inch increments is recorded, and the blows
of the last two increments are summed to obtain the Standard Penetration Resistance (N-value).
In some of the Standard Penetration Tests, the blow count is recorded as "0" or weight of
hammer (WOH). In these cases, the static weight of the hammer, rods, and sampler penetrated
into the soft subsurface soil with no hammer blows. The N-value provides a general indication
of in-situ soil conditions and has been correlated with certain engineering properties of soils.
In some soils, it is not always practical to drive a split-spoon sampler the full three consecutive
6-inch increments. Whenever more than 50 blows are required to drive the sampler over a 6-inch
increment, or the sampler is observed not to penetrate after 50 blows, the condition is called
split-spoon refusal. Split-spoon refusal conditions may occur because of obstructions or because
the earth materials being tested, are very dense or very hard. When split-spoon refusal occurs,
often little or no sample is recovered. The SPT N-value for split-spoon refusal conditions is
typically estimated as greater than 100 blows per foot (bpf). Where the sampler is observed not
to penetrate after 50 blows,the N-value is reported as 50/0. Otherwise,the depth of penetration
after 50 blows is reported in inches, i.e. 50/5, etc.
Rock coring was performed in two(2) offset borings (designated as B-1A and B-7A)to explore the
auger refusal materials initially encountered in borings B-1 and B-7. The offset borings were
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advanced beyond auger refusal using rock-coring techniques generally following the procedures
outlined in ASTM D 2113. The rock cores were logged by a member of our professional staff and
relative hardness, rock type, percent recovery, and rock quality designation (RQD) were
measured. The percent recovery is the ratio of the sample length obtained to the total length of
the core run, expressed as a percent. The RQD is the percentage of the length of the core
recovered in segments 4 or more inches long, compared to the total length of the core run. Care
is taken during observation of the core to see that breaks in the core length caused by drilling or
handling are ignored in the RQD determination. The percent recovery and RQD are related to
rock soundness and continuity. The percent recovery and RQD values are shown on the attached
boring logs.
Groundwater level readings were taken in each of the borings immediately upon completion of
the soil drilling process. Temporary piezometers, consisting of slotted PVC pipe, were installed
at the completion of drilling at selected locations to aid in obtaining stabilized groundwater
measurements approximately 24 hours after drilling. Following groundwater readings, the
temporary piezometers were removed and all boreholes were backfilled with auger cuttings
(soil). Periodic observation and maintenance of the boreholes should be performed due to
potential subsidence at the ground surface, as the borehole backfill could settle over time.
Representative portions of the split-spoon soil samples obtained throughout the exploration
program were sealed in air-tight containers and transported to our laboratory. The collected
samples were classified by a member of our professional staff in general accordance with
techniques outlined in the visual-manual identification procedure (ASTM D 2488) and the Unified
Soil Classification System. The soil descriptions and classifications discussed in this report and
shown on the attached Boring Logs are generally based on visual observation and should be
considered approximate. Copies of the boring logs are provided and classification procedures
are further explained in the attached Appendix II.
Split-spoon soil and rock core samples recovered on this project will be stored at F&R's office for
a period of sixty days. After sixty days, the samples will be discarded unless prior notification is
provided to us in writing.
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2.2 Laboratory Testing
Twelve(12) split-spoon soil samples were selected for additional laboratory classification testing.
This testing included water content determination (ASTM D2216), Atterberg limits tests (ASTM
D4318), and percent passing#200 sieve (ASTM D 1140). Based on the results of these tests, the
soils from these selected samples were then classified in general accordance with Unified Soil
Classification System (ASTM D2487).
Laboratory Standard Proctor moisture density relationship (ASTM D698) tests and classification
testing were also performed on three (3) bulk samples.
The results of the laboratory testing program are summarized in tables in Section 3.3 of this
report and presented on the Material Test Reports and Proctor Reports included as Appendix Ill.
Unconfined compressive strength (UCS) testing was performed on portions of intact rock
selected from the core samples in general accordance with ASTM D7012 — Method C. The UCS
testing results are presented in Section 3.2.7 and as shown on the boring logs.
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3.0 REGIONAL GEOLOGY&SUBSURFACE CONDITIONS
3.1 Regional Geology
The project site is located in the Charlotte Belt of the Piedmont Physiographic Province.
According to the Geologic Map of North Carolina (1985), the site is underlain by metamorphic
rock, primarily consisting of phyllite and schist. The topography of the Piedmont Plateau consists
of well-rounded hills and long-rolling ridges with a northeast-southwest trend.
The soils resulting from in-situ weathering of the parent rock, without significant transportation,
are called residual soils and may retain some of the structure of the rock from which they
weathered. The residual soil profile generally grades downward gradually from fine-grained
plastic soils near the ground surface to coarser-grained soils at greater depth. A transitional zone
of"partially weathered rock" of varying thickness can occur between the coarser-grained residual
soils and the underlying bedrock. Partially weathered rock is defined, for engineering purposes,
as residual material with standard penetration resistances in excess of 100 blows per foot.
Weathering of the parent bedrock is generally more rapid near fracture zones and therefore,the
bedrock surface may be irregular. Irregular patterns of differential weathering may also result in
zones of rock and partially weathered rock embedded within the more completely weathered
coarse-grained soils.
3.2 Subsurface Conditions
3.2.1 General
The subsurface conditions discussed in the following paragraphs, and those shown on the
attached Boring Logs, represent an estimate of the subsurface conditions based on interpretation
of the field and laboratory data using normally accepted geotechnical engineering judgments. In
addition, subsurface profiles are presented in Appendix II. These profiles serve to conceptually
illustrate potential subsurface conditions in cross-sections of the project site. It should be noted
that the profiles do not necessarily reflect the actual relative distance changes between the
respective boring locations.
The strata breaks designated on the Boring Logs and Subsurface Profiles represent approximate
boundaries between soil types. Actual transitions between soil strata are generally less distinct
than the immediate transitions depicted on the Boring Logs and Subsurface Profiles. Although
individual soil test borings are representative of the subsurface conditions encountered at the
boring locations on the dates shown,they are not necessarily indicative of subsurface conditions
at other locations or at other times. Below the existing ground surface, the borings generally
encountered surficial soils or asphalt underlain by existing fill materials, residual soils, partially
weathered rock, auger refusal materials, and rock. These materials are discussed further below:
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3.2.2 Surficial Materials
Surficial soils were encountered in each of the borings to depths of approximately 1/2 to 4 inches.
Surficial soils are typically a dark-colored soil material containing roots, fibrous matter, and/or
other organic components,and are generally unsuitable for engineering purposes. We note that
no laboratory testing has been performed to determine the organic content or horticultural
properties of the observed surficial soil materials. Therefore, the term "surficial soils" is not
intended to indicate suitability for landscaping and/or other purposes. The surficial soil depths
provided in this report are based on driller observations and should be considered approximate.
The transition from surficial soils to underlying materials may be gradual and therefore the
observation and measurement of surficial soil depths is subjective. Actual surficial soils depths
should be expected to vary across the site.
3.2.3 Fill Materials
Existing fill materials include those materials deposited by man. Materials identified as existing
fill were encountered in 9 of 14 borings and extended to approximate depths ranging from 2 to
17 feet below existing grade. In general,the sampled fill materials were described as clayey sand
(SC), silty or sandy clay (CL), and clayey silt (MH). Standard penetration resistances (N-values)
within the sampled fill materials ranged from 4 to 43 blows per foot (bpf).
3.2.4 Residual Soils
Residual soils, formed by the in-place weathering of the parent rock, were encountered in each
of the borings below the surficial soils or fill soils. Sampled residual soils were generally described
as sandy or silty clay (CL), clayey silt (ML), clayey sand (SC), or silty sand (SM). Standard
penetration resistances in the sampled residuum ranged from 10 to 80 bpf.
3.2.5 Partially Weathered Rock
Partially weathered rock (PWR) is a transitional material between soil and rock,which retains the
relic structure of the rock and has very hard or very dense consistencies. PWR was encountered
in each of the borings below the fill or residual soils at depths of approximately 2 to 17 feet below
existing site grades.
Sampled partially weathered rock was generally described as sandy silt (ML) and silty sand (SM)
with penetration resistances ranging from 50 blows per 6 inches(50/6)of split-spoon penetration
to 50 blows per 0 inches (50/0) of split-spoon penetration. For the boring locations where PWR
was encountered, the depths of encountered PWR as well as the termination condition at the
bottom of the boring (i.e. Boring Termination or Auger Refusal) are summarized in the table
below.
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Table of PWR and Terminations
Approximate Approximate
Proposed
Boring No. Depth to top of PWR Termination Depth
Structure
(ft.) (ft.)/(ft-MSL+/-)
B-1 12 AR 25.4/476
Influent Pump B-2 12 AR 14.3/496
Station 2 B-3 12 AR 25.4/483
B-4 8 AR 23.1/486
B-5 17 BT 29.5 /521
Secondary B-6 3.5 AR 28.4/523
Clarifier 3
B-7 6 AR 23.5/527
RAS Pump B-8 3.5 AR 16.6/533
Station B-9 2 BT 15 /535
Future B-10 17 BT 45 /504
Secondary B-11 2 BT 18.7/530
Clarifier 4 B-12 6 AR 22.5/526
Chemical B-13 17 AR 23.3/530
Facility B-14 17 BT 28.7/525
BT= Boring Termination
AR=Auger Refusal
3.2.6 Auger Refusal Materials
Auger refusal occurs when materials are encountered that cannot be penetrated by the soil auger
and is normally indicative of a very hard or very dense material, such as boulders, rock lenses,
pinnacles, impenetrable debris within fill, or the upper surface of bedrock. Auger refusal
materials were encountered in 9 of the 15 borings at depths ranging from 14.3 to 28.4 feet below
the existing ground surface, as indicated in the table above.
Auger refusal discussed herein is based on conditions impenetrable to our drilling equipment
(CME-550X). Auger refusal conditions with a CME-550X do not necessarily indicate conditions
impenetrable to other equipment. Auger refusal conditions may exist intermediate of the boring
locations or in unexplored areas of the site.
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3.2.7 Rock
Rock coring was performed in borings B-1A and B-7A to further explore the auger refusal
materials encountered in their respective original borings (B-1 and B-7). Rock recovered during
the coring operations was generally described as greenish gray slate. Specific descriptions of
recovered rock are provided on the respective boring logs as well as an accompanying Rock Core
Summary and Photograph Log.
The following table summarizes Percent Recovery, Rock Quality Designation (RQD), and
unconfined compressive strength (UCS) of the rock core samples.
Boring Rock Core REC(%) RQD (%) UCS (psi) Generalized Description
Depth (ft)
22.2 to 25.2 94 94 -
B-1A 25.2 to 30.2 100 100 9,350 Greenish gray SLATE
30.2 to 32.2 100 100 -
22.3 to 25.8 100 100 -
B-7A 25.8 to 30.8 100 100 7,130 Greenish gray SLATE
30.8 to 32.3 100 100 -
3.2.8 Groundwater Conditions
Groundwater level readings were taken in each of the borings immediately upon completion of
the soil drilling process. Groundwater was encountered in boring B-10 at an approximate depth
of 39 feet below the existing ground surface (approximate elevation of 510 feet).
Water was also noted on the split spoon samples recovered from borings B-1 and B-3 at depths
of 23.5 feet and 23 feet below existing grade (approximate elevations of 478 feet and 485 feet),
respectively.
It should be noted that the groundwater levels fluctuate depending upon seasonal factors such
as precipitation and temperature. Additionally, several of the borings are likely in designated
flood plains. As such, soil moisture and groundwater conditions at other times may vary from
those described in this report.
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3.3 Laboratory Test Results
As outlined in Section 2.2, Laboratory Testing, selected split-spoon samples obtained during the
field exploration were tested in general accordance with applicable ASTM standards. The results
of the laboratory-testing program are summarized the following tables and additionally provided
as the Material Test Reports included in Appendix III.
Standard Proctor Test Summary
Boring Bulk Sample Natural Moisture Optimum Moisture Maximum Dry
No. Depth (ft.) Content(%) Content(%) Density(pcf)
B-2 2-8 14.2 14.0 113.6
B-6 2-8 11.8 11.5 124.5
B-12 2 -8 11.8 13.4 118.2
Soil Classification Test Summary
BoringSample Water % Finer [ Atterberg Limits USCS
Depth Content than No.
No. (ft) (%) LL PL PI Classification
200 Sieve [
B-1 3.5-5 14.3 49 43 26 17 SC
B-1 13.5-15 8.6 28 30 23 7 SC
B-2 3.5-5 19.3 57 41 26 15 CL
B-3 2-3.5 16.1 47 40 24 16 SC
B-3 18.5-20 12.7 29 31 22 9 SC
B-7 3.5-5 9.9 30 33 23 10 SC
B-10 8.5-10 10.5 23 38 22 16 SC
B-12 2-3.5 8.0 57 41 25 16 CL
B-13 3.5-5 8.6 43 33 23 10 SC
B-13 8.5-10 9.9 30 36 24 12 SC
B-14 6.5-8 10.8 44 36 21 15 SC
B-14 13.5 - 15 11.2 30 32 24 8 SC-SM
B-2 2-8 (Bulk) 14.2 52 36 19 17 CL
B-6 2-8 (Bulk) 11.8 59 35 11 24 CL
B-12 2-8 (Bulk) 11.8 55 37 21 16 CL
Notes: LL-Liquid Limit, PL-Plastic Limit, PI - Plastic Index, NV-Non-Viscous, NP- Non-Plastic
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4.0 DESIGN RECOMMENDATIONS
4.1 General
The following evaluations and recommendations are based on interpretation of the field and
laboratory data obtained during this and previous explorations as well as our experience with
similar subsurface conditions and projects. Soil penetration data has been used to consider
allowable foundation capacities and estimate associated settlements using established
correlations. Subsurface conditions in unexplored locations may vary from those encountered.
If structure locations, loadings, or elevations are changed, we should be notified and requested
to confirm and, if necessary, re-evaluate our recommendations.
Determination of an appropriate foundation system for a given structure is dependent on the
proposed structural loads, soil and/or rock conditions, and construction constraints such as
proximity to other structures, etc. The subsurface exploration aids the geotechnical engineer in
determining the soil/rock stratum appropriate for structural support. This determination
includes considerations with regard to both allowable bearing/frictional capacities and
compressibility of the soil/rock strata. In addition, since the method of construction greatly
affects the soil intended for structural support, consideration must be given to the
implementation of suitable methods of site preparation, fill compaction, and other aspects of
construction.
4.2 Foundation Recommendations
Structure-specific evaluations and foundation recommendations are presented in the following
Sections 4.2.1 through 4.2.5. General direct support on shallow foundation recommendations
are presented in Section 4.2.6.
4.2.1 Influent Pump Station 2
We understand that IPS2 will be a cast-in-place concrete structure consisting of a deeper wetwell
connected to a shallower valve vault. F&R was provided with average gross bearing pressures of
4,500 psf and 1,500 psf for the wetwell and valve vault, respectively. Existing grades in the footprint
of IPS2 range from approximately 500 to 507 feet for the wetwell and 507 to 510 feet for the valve
vault. Planned subgrade elevations are 468.50 and 498.00 for the wetwell and valve vault,
respectively. Maximum excavation depths of approximately 38 feet and 13 feet for the wetwell and
valve vault, respectively,will be required to reach planned subgrade elevations.
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Wetwell:
Based on the subsurface conditions encountered in borings B-1 and B-3,and offset boring B-1A,the
wetwell portion of IPS2 will bear in/on rock. Excavation of up to approximately 15 feet of rock will
be required to reach to the planned subgrade elevation of 468.50 feet. Removal of the rock will
likely require blasting. See Section 5.8 Excavation Characteristics for more information.
Excavation of rock will likely cause an uneven surface which will need to be leveled prior to
construction of the wetwell. We recommend the placement of lean concrete to level the rock
surface in the wetwell footprint.
From a settlement point of view, the provided gross 4,500 psf bearing pressure is tempered by the
depth of excavation required for the wetwell (net bearing pressure of approximately 500 psf or less
due to the deep excavation). Considering the reduced net bearing and presuming that the structure
is fully bearing on a lean concrete leveling surface directly underlain by mass rock, anticipated
settlements should be nominal (i.e. less than%-inch).
Valve Vault:
We understand that the valve vault and wetwell will be connected with rigid piping and the
settlement tolerance between the two portions of the structure is very tight.
We further understand that the excavation to construct the wetwell will utilize a temporary sloped
excavation to meet subgrade levels including the area below the valve vault. Based on the
surrounding boring data, we anticipate that the entire temporary slope below the valve vault
footprint will likely be excavated into PWR. Following construction of the wetwell below-grade
walls, up to approximately 30 feet of backfill will be placed against the east wall of the wetwell to
the valve vault subgrade elevation of 498.00 feet.
If the area below the valve vault is backfilled with compacted Aggregate Base Course (ABC) stone
(98% of Modified Proctor Maximum Dry Density) from the temporary slope excavated in PWR to
the valve vault subgrade,we anticipate a total settlement on the order of%-inch for the valve vault.
The ABC stone backfill should extend beyond the valve vault footprint a horizontal distance equal to
the backfill depth at that location (to provide a 1H:1V slope from the edge of the footprint to meet
the temporary slope). If the%-inch of anticipated differential settlement between the wetwell and
valve vault would be detrimental, or if the volume of ABC stone required is deemed too costly, a
system of deep foundations could be utilized.
4.2.2 Odor Control —Influent
We were provided with an approximate gross contact pressure of 1,500 psf. Existing grades in the
slab footprint range from about 509 to 510 feet. Based on a provided subgrade elevation of 510.00
feet, up to about 1 foot of fill will be required below the structure.
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Based on the subsurface conditions encountered in the area of the proposed odor control pad
and a bearing pressure of 1,500 psf across a mat type foundation, total and differential
settlements of about %-inch and %-inch are anticipated, respectively.
We note that existing fill was encountered in boring B-3 to a depth of 8 feet below existing grade.
While the encountered fill appeared to have been placed with some compactive effort, bearing on
existing fill materials has inherent risks. In general, construction on existing fill materials requires
the project owner to accept some risks due to unforeseen conditions within the fill material.
Associated risks may be additional support related cost (i.e. undercutting, etc.) and excessive
foundation settlement. In order to eliminate the risks associated with supporting the odor
control pad on existing fill, the existing materials would need to be completely removed and
replaced with new controlled structural fill. However, provided the recommended engineering
evaluations are performed and the owner is willing to accept some risk, we believe that support
of the odor control pad on the existing fill is feasible with some subgrade modifications (to be
determined at the time of construction), if required.
4.2.3 Secondary Clarifiers
F&R was provided with average gross contact pressure of 2,000 to 2,500 psf. Existing grades in the
footprints of the secondary clarifiers range from approximately 550 to 551.5 feet for Secondary
Clarifier 3 and 548 to 550 feet for Future Secondary Clarifier 4. F&R was provided with subgrade
elevations of 523.67 feet (in the middle) to 535.50 feet (at the edges). Excavations ranging from
about 13 to 29 feet in depth from existing grades will be required in the footprints of the secondary
clarifiers.
Due to the deep cut/excavation depths, the net bearing pressure is anticipated to be on the order
of 1,000 psf or less. Further, based on the subsurface conditions encountered in the area, we
anticipate the majority of each of the secondary clarifiers will bear on PWR. Portions of the clarifiers
may also bear in dense soils underlain by PWR. While the boring data does indicate the definitive
presence of rock to the planned depths of clarifier excavation, rock and auger refusal materials were
encountered close to the clarifier bearing elevations and therefore, some rock requiring the use of
difficult excavation techniques may be encountered.
Support of the secondary clarifiers on the provided mat foundation is anticipated to yield a
maximum total settlement of about %-inch based on borings in the area. Therefore, shallow
foundation support for this structure appears feasible. Further recommendations on direct shallow
foundation support are presented in Section 4.2.6.
Based on the anticipated settlement of about %-inch, an initial modulus of subgrade reaction of 50
pci has been estimated. Modulus of subgrade reaction was approximated for the secondary
clarifiers using the provided gross contact pressure and the estimated maximum settlement.
Although a single modulus value is being provided, values can vary greatly across large mat
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foundations, as the mat is not completely rigid and actual contact pressures will vary. We note
that modulus of subgrade reaction is an iterative parameter, as the initial value is typically input
into software such as STAAD for structural modeling. Feedback from the structural engineer is
typically necessary to arrive at a reasonable range of moduli across a large mat.
4.2.4 RAS Pump Station 3
We understand that the RAS pump station will be a cast-in-place concrete structure consisting of a
deeper wetwell connected to a shallower valve vault. F&R was provided with average gross bearing
pressures of 3,500 psf and 1,500 psf with planned subgrade elevations of 523.50 feet and 540.50
feet for the wetwell and valve vault, respectively. Based on an existing grade of about 550 feet,
maximum excavation depths of approximately 27 feet and 10 feet will be required to reach planned
subgrade elevations for the wetwell and valve vault, respectively.
Wetwell:
Based on the subsurface conditions encountered in boring B-8, at least some portion of the wetwell
will bear on rock. In the area of boring B-8, it is envisioned that excavation of up to approximately
10 feet of rock will be required to reach to the planned subgrade elevation of 523.50. Removal of
the rock will likely require blasting. See Section 5.8 Excavation Characteristics for more information.
Excavation of rock will likely cause an uneven surface which will need to be leveled prior to
construction of the wetwell. We recommend the placement of lean concrete to level the rock
surface in the wetwell footprint.
The gross bearing pressure of 3,500 psf(net bearing pressure of approximately 500 psf or less due
to the deep excavation) is anticipated to incur nominal (i.e. less than 1A-inch) settlement if the
structure is fully bearing on rock and lean concrete is used to level the rock surface. Settlement on
the order of %-inch or less is anticipated for any portion of the structure bearing in PWR, if
encountered.
Valve Vault:
We understand that the valve vault and wetwell will be connected with rigid piping and the
settlement tolerance between the two portions of the structure is very tight.
We further understand that the excavation to construct the wetwell will utilize a temporary sloped
excavation to meet subgrade levels including the area below the valve vault. Based on borings B-8
and B-9, we anticipate that the entire temporary slope below the valve vault footprint will likely be
excavated into PWR. Following construction of the wetwell below-grade walls, approximately 17
feet of backfill will be placed against the west wall of the wetwell to the valve vault subgrade
elevation of 540.50 feet.
If the area below the valve vault is backfilled with compacted Aggregate Base Course (ABC) stone
(98% of Modified Proctor Maximum Dry Density) from the temporary slope excavated in PWR to
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the valve vault subgrade, we anticipate a total settlement on the order of%-inch for the valve vault.
The ABC stone backfill should extend beyond the valve vault footprint a horizontal distance equal to
the backfill depth at that location (to provide a 1H:1V slope from the edge of the footprint to meet
the temporary slope). If the%-inch of anticipated differential settlement between the wetwell and
valve vault would be detrimental, or if the volume of ABC stone required is deemed too costly, a
system of deep foundations could be utilized.
4.2.5 Chemical Facility
F&R was provided with an average bearing pressure of 2,500 psf. Existing grades in the footprint of
the chemical facility range from approximately 552 to 555 feet. Planned subgrade elevations range
from 551.00 to 554.00 feet. Cuts and fills of up to about 4 feet and 2 feet, respectively, will be
required in the chemical facility footprint.
Based on the subsurface conditions encountered in the area of the proposed Chemical Facility
and a bearing pressure of 2,500 psf across a mat type foundation, total settlements of 1 to
11/4-inch and differential settlements of up to about%-inch are anticipated.
4.2.6 General Shallow Foundation Design Recommendations
To reduce the possibility of localized shear failures, spread and strip footings should be a
minimum of 3 feet and 18 inches wide, respectively. Exterior footing bottoms should be
constructed a minimum of 12 inches below adjacent exterior grades in order to bear below
normal frost depth.
4.3 Concrete Slabs-On-Grade
For structures designed with a conventional concrete slab-on-grade (not mat foundations), slabs
may be placed on properly compacted controlled structural fill over an approved soil subgrade
following subgrade preparation as discussed in Section 5.2 of this report.
A minimum 6-inch thick layer of Aggregate Base Course (ABC) stone or open-graded coarse
aggregate, such as No. 57 stone, should be placed beneath the floor slab. This granular base
would function as a leveling and load distributing material as well as a capillary break beneath
the slab. Proper jointing of the concrete slabs-on-grade is essential to reduce cracking. ACI
suggests that unreinforced, plain concrete slabs may be jointed at spacing of 24 to 36 times the
slab thickness, up to a maximum spacing of 15 feet. Slab construction should incorporate
isolation joints along walls and column locations to allow minor movements to occur without
damage. Utility or other construction excavations in the prepared subgrade should be backfilled
to a controlled fill criterion to provide uniform support.
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4.4 Seismic Design Criteria
The following seismic site class recommendations are based on American Society of Civil
Engineers (ASCE) 7-10 per Section 1613.3.2 as referenced by the International Building Code
(IBC), as adopted by the 2018 North Carolina Building Code.
The subsurface data from the areas of the proposed structures to the depths explored,as well as
a presumed N-value of 100+below the depths explored in borings terminated in PWR or at Auger
Refusal, were used to develop the seismic criteria. Based on the boring data,our experience with
similar conditions, and in general accordance with 1613.3.2 of the IBC, seismic Site Class was
determined for the structures.
The table below provides the seismic Site Class assigned for each of the planned structures.
SEISMIC SITE CLASS
Structure Seismic Site Class
Influent Pump Station 2 C
Odor Control — Influent C _
Secondary Clarifier 3 C
Future Secondary Clarifier 4 C
RAS Pump Station C
Chemical Facility D
We note that the above provided Site Classifications are based on boring SPT N-values. Should
the project team deem an improved Site Class for the Chemical Facility advantageous, F&R can
perform a geophysical study to obtain subsurface shear velocity profiles. Based on the
subsurface conditions encountered in the area of the Chemical Facility, there is a high likelihood
that an improved Site Class can be achieved with shear wave velocity testing. This additional
testing would be beyond the currently authorized scope of services for this project.
4.5 Lateral Earth Pressures
The following information is provided to aid in analysis of soil loads on below grade walls. Earth
pressures on walls below-grade are influenced by structural design of the walls, conditions of
wall restraint, methods of construction and/or compaction, and the strength of the materials
being restrained. The most common conditions assumed for earth retaining wall design are the
active and at-rest conditions. Active conditions apply to relatively flexible earth retention
structures, such as freestanding walls, where some movement and rotation may occur to
mobilize soil shear strength. Walls that are rigidly restrained, such as basement, pit, and tunnel
walls, require design using at-rest earth pressures. A third condition, the passive state,
represents the maximum possible pressure when a structure is pushed against the soil, and is
used in wall foundation design to help resist active or at-rest pressures. Because significant wall
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movements are required to develop the passive pressure, the total calculated passive pressure
should be reduced by one-half to two-thirds for design purposes.
Based on the subsurface exploration, we envision that the near-surface site soils which might be
involved with the majority of the below-grade walls will predominately consist of silty clay (CL),
clayey silt (ML), and clayey sand (SC). If encountered during construction or if an off-site source
for material is required, we do not recommend the use of highly-plastic clays and silts (CH and
MH) behind below grade walls.
As previously stated in Sections 4.2.1 and 4.2.4,we recommend that ABC stone backfill be utilized
under the valve vault portions of the Influent Pump Station 2 and RAS Pump Station 3. Lateral
earth pressure parameters for ABC stone are provided below, but in order to utilize these, the
full theoretical failure wedge must consist of ABC stone backfill. Therefore, the ABC stone should
be extended laterally from back heel of the wall footing, a minimum distance of 0.5 times the
wall height at the top of the wall (see Extent of Select Backfill for Retaining Walls, Drawing No. 3,
Appendix IV). The ABC stone backfill below the valve vaults should exceed the required lateral
distance from the back of the wall.
The following tables provide lateral earth pressure parameters for both the onsite soils mixture
as well as ABC Stone.
ON-SITE SOILS MIXTURE (CL/ML/SC)
Earth Pressure Conditions Coefficient Recommended Equivalent
Fluid Pressure (pcf)
Active (Ka) 0.36 45
At-Rest (Ko) 0.53 66
Passive (Kr) 2.77 ---
*A compacted moist soil unit weight of 125 pounds per cubic foot should be used for design calculations.
ABC STONE
Earth Pressure Conditions Coefficient Recommended Equivalent
Fluid Pressure (pcf)
Active (Ka) 0.17 _ 25
At-Rest (Ko) 0.29 42
*A compacted moist unit weight of 145 pounds per cubic foot should be used for design calculations based
on ABC Stone compacted to 98%of Modified Proctor Max Dry Density.
For design calculations of resistance to sliding (regardless of selected backfill materials), a value
of 0.34 should be used as the coefficient of friction between concrete surfaces and the underlying
on-site soils. Increased frictional resistance can be attained by replacing the foundation soils with
compacted crushed stone to a depth of up to % the footing width. If needed, additional
recommendations regarding a potential increase in frictional resistance can be provided.
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Our recommendations assume that the ground surface above the wall is level. The
recommended equivalent fluid pressures assume that constantly functioning drainage systems
are installed between walls and soil backfill to prevent the accidental buildup of hydrostatic
pressures and lateral stresses in excess of those stated. In the event that a functioning drainage
system is not installed, the lateral earth pressures should be determined using the buoyant
weight of the soil and the appropriate above provided coefficient of earth pressure. Hydrostatic
pressures calculated with the unit weight of water (62.4 pcf)should then be added to these earth
pressures to obtain the total stresses for design.
Heavy equipment should not operate within 5 feet of below-grade walls to prevent lateral
pressures in excess of those cited. If footings or other surcharge loads are located a short
distance outside below-grade walls,they may also exert appreciable additional lateral pressures.
Surcharge loads should be evaluated using the appropriate active or at-rest pressure coefficients
provided above. The effect of surcharge loads should be added to the recommended earth
pressures to determine total lateral stresses.
These retaining/below grade wall recommendations should not be correlated for use in the
design of mechanically stabilized earth (MSE) walls. We recommend that soil parameters for any
MSE wall design be established through appropriate laboratory testing directed by the wall
designer.
4.6 Temporary Excavation Support/Shoring
As previously stated, temporary excavation support will be required for the construction of
Influent Pump Station 2 due to the proximity to existing facilities. Design of temporary excavation
support is typically handled by a specialty geotechnical contractor; however, we envision a
system of soil nails would work well to support the existing facilities to the east of the IPS2.
Locations of individual soil nails should be designed to avoid conflicts with any existing
underground obstructions.
Based on auger refusal in boring B-2 at an approximate elevation of 496 feet and existing grade
of about 510 feet in the area of the proposed temporary excavation support, we envision the
temporary excavation will be less than about 20 feet at the support. Therefore, soil nails will
likely need to be on the order of 20 feet in length or less.
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5.0 CONSTRUCTION RECOMMENDATIONS
5.1 General
The principal purpose of this section is to comment in general on the items related to earthwork
and associated geotechnical engineering aspects of construction that should be expected for this
project. It is recommended that F&R be retained to provide soil engineering services during the
construction phases of the project and perform appropriate evaluations to help confirm that
conditions encountered during construction are similar to conditions observed in the borings.
The geotechnical engineer can also assist in interpretation of differing subsurface conditions that
may be encountered and recommend remedial work, if needed.
5.2 Site Preparation
Before proceeding with construction, any surficial soils, roots, and any other deleterious non-soil
materials should be stripped or removed from proposed construction areas. During the clearing
and stripping operations, positive surface drainage should be maintained to prevent the
accumulation of water.
After stripping, areas intended to support new fill, pavements, and foundations should be
carefully evaluated by a representative of the geotechnical engineer. At that time, the engineer
may require proofrolling of the subgrade with a 20-to 30-ton loaded truck or other pneumatic-
tired vehicle of similar size and weight. Proofrolling should be performed during a time of good
weather and not while the site is wet, frozen, or severely desiccated. The purpose of the
proofrolling is to locate soft, weak, or excessively wet soils present at the time of construction
and provides an opportunity for the geotechnical engineer to locate inconsistencies intermediate
of the boring locations.
Undercutting or additional in-place compaction may be necessary if the exposed subgrade soils
become unstable during construction. Any fill materials, aggregate, and or pavement should be
placed as soon as possible over the approved subgrade in order to reduce exposure of the
subgrade to weather and construction activity. It is important to stress that if site preparation or
construction are performed during the winter months, additional undercutting of the subgrade
soils may be required if the subgrade is not properly prepared or protected.
5.3 Shallow Foundation Construction
All foundation subgrades should be observed, evaluated, and verified for the design bearing
pressure by a representative of the geotechnical engineer after excavation and prior to base
stone or reinforcement steel placement. If low consistency soils are encountered during
foundation construction, localized undercutting and/or in-place stabilization of foundation
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subgrades may be required. The actual need for, and extent of, undercutting or in-place
stabilization should be based on field observations made by a representative of the geotechnical
engineer at the time of construction.
Excavations for footings should be made in such a way as to provide bearing surfaces that are
firm and free of loose, soft, wet, or otherwise disturbed soils. Foundation concrete should not
be placed on frozen or saturated subgrades. If such materials are allowed to remain below
foundations, settlements will increase. Foundation excavations should be concreted as soon as
practical after they are excavated. If an excavation is left open for an extended period, a thin
mat of lean concrete should be placed over the bottom to minimize damage to the bearing
surface from weather or construction activities. Water should not be allowed to pond in any
excavation.
5.4 Controlled Structural Fill
The majority of the soil encountered in the borings consisted of silty clay (CL), clayey silt (ML),
and clayey sand (SC). Based on the boring data, controlled structural fill may be constructed
using the non-organic on-site soils, with some exclusions for the use of elastic silt (MH) soils. If
an off-site borrow source is required to balance the site, the imported materials should have a
classification of CL, ML, SC, or SM as defined by the Unified Soil Classification System. Other
materials may be suitable for use as controlled structural fill material and should be individually
evaluated by the geotechnical engineer. If encountered, CH soils should not be used for retaining
wall backfill or be placed within 2 feet of subgrade elevations in structural areas. Controlled
structural fill should be free of boulders, organic matter, debris, or other deleterious materials
and should have a maximum particle size no greater than 3 inches. In addition, we recommend
a minimum standard Proctor (ASTM D 698) maximum dry density of approximately 90 pounds
per cubic feet for fill materials.
Fill materials should be placed in horizontal lifts with maximum height of 8 inches loose measure.
New fill should be adequately keyed into stripped and scarified subgrade soils and should,where
applicable, be benched into the existing slopes. During fill operations, positive surface drainage
should be maintained to prevent the accumulation of water. We recommend that structural fill
be compacted to at least 95 percent of the standard Proctor maximum dry density. In confined
areas such as utility trenches, portable compaction equipment and thin lifts of 3 to 4 inches may
be required to achieve specified degrees of compaction. Each lift of fill should be tested in order
to confirm that the recommended degree of compaction is attained.
In general,we recommend that the moisture content of fill materials be maintained within three
percentage points of the optimum moisture content as determined from the standard Proctor
density test. We recommend that the contractor have equipment on site during earthwork for
both drying and wetting of fill soils. Moisture control may be especially difficult during winter
months or extended periods of rain. Attempts to work the soils when wet can be expected to
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result in deterioration of otherwise suitable soil conditions or of previously placed and properly
compacted fill. Where construction traffic or weather has disturbed the subgrade, the upper 8
inches of soils (or more if warranted) intended for structural support should be scarified and re-
compacted. Each lift of fill should be tested in order to confirm that the recommended degree
of compaction is attained.
5.5 Surface Water Control
If free water is allowed to stand on stable subgrade soils, the in-situ silty and clayey soils can
absorb water, swell, and experience a reduction in their support capability. As a result, we
recommend that the subgrade surface be graded to provide positive drainage away from the
construction areas and towards suitable drainage handling areas, such as a perimeter ditch,
French drain, culvert, or retention pond. Where pockets of silty and clayey soils exist,trapped or
perched water conditions could develop during periods of inclement weather and during
seasonally wet periods. Such conditions could cause seepage into excavations and deeper cuts.
In addition, if site grading is performed during the seasonally wet months or after extended
periods of inclement weather, wet and water softened near-surface soil conditions should be
expected across the site.
5.6 Groundwater Conditions
Groundwater was encountered in boring B-10 at an approximate depth of 39 feet below the
existing ground surface (approximate elevation of 510 feet). The lowest planned subgrade
elevation in the area of the proposed secondary clarifiers and RAS Pump Station 3 is 523.50 feet.
Therefore,we do not anticipate groundwater will be encountered in the area of these structures.
Water was also noted on the split spoon samples recovered from borings B-1 and B-3 at depths
of 23.5 feet and 23 feet below existing grade (approximate elevations of 478 feet and 485 feet),
respectively. In each of these borings the wet sampler was about 2 feet above auger refusal. The
encountered water could have been perched over the auger refusal materials/rock and may not
represent sustained groundwater levels at those locations. However, based on the planned
Influent Pump Station 2 wetwell subgrade elevation of 468.50 feet, some groundwater or
perched water may be encountered during excavation and construction.
Due to the presence of silty and clayey soils,which generally have very low hydraulic conductivity,
trapped or perched water conditions may be encountered at some point during project
development, especially during periods of inclement weather and seasonally wet periods.
Groundwater levels tend to fluctuate with seasonal and climatic variations as well as with some
types of construction operations. Generally, the highest subsurface water levels occur in late
winter and early spring and the lowest levels occur in late summer and early fall. If encountered
during construction, engineering personnel from our office should be notified immediately.
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5.7 Excavation Characteristics
PWR was encountered in each of the borings below the fill soils or residual soils at depths of
approximately 2 to 17 feet below existing site grades. Auger refusal materials were encountered
in 9 of the 15 borings at depths ranging from 14.3 to 28.4 feet below the existing ground surface,
as indicated in the table above
Rock coring was performed in borings B-1A and B-7A to further explore the auger refusal
materials encountered in borings B-1 and B-7, respectively. Rock recovered during the coring
operations was generally described as greenish gray slate. Laboratory Unconfined Compressive
Strength of 9,350 psi and 7,130 psi was measured for the tested samples of rock recovered from
borings B-1A and B-7A, respectively.
Based on the provided structure subgrade elevations as well as the locations and approximate
elevations where auger refusal and rock were encountered in the borings,we anticipate that rock
will be encountered in excavations for the wetwell portions of Influent Pump Station 2 and RAS
Pump Station 3. Excavation of up to approximately 15 feet of rock will be required at IPS2 to reach
to the planned subgrade elevation of 468.50. Removal of large quantities of rock is typically
achieved through blasting; however, due to the proximity of the proposed wetwells to existing
facilities, mechanical (non-explosive) rock fracturing utilizing an expanding chemical agent may be
prudent. Rock may also be encountered in the deeper portions of the excavations for the
Secondary Clarifiers.
Further, we anticipate PWR will be encountered during excavation for the construction of
Influent Pump Station 2, RAS Pump Station 3, and the Secondary Clarifiers.
Typically, material with a penetration resistance of 50 blows per 3 to 6 inches of penetration can
be excavated with moderate to heavy effort using appropriately sized equipment, such as a large
track-hoe (e.g., Caterpillar 330 with rock teeth). In confined excavations such as foundations,
utility trenches, elevator pits, etc., removal of partially weathered rock typically requires use of
large backhoes, pneumatic spades, or light blasting. Refusal materials will normally require
blasting for removal in all types of excavations. As previously stated,the use of mechanical (non-
explosive) rock fracturing in lieu of blasting may be required to avoid damage to existing facilities.
Any blasting in footing excavations must be done carefully to prevent damage to the bearing
materials.
Hazen and Sawyer Twelve Mile Creek WRF 9.0 MGD Expansion
F&R Project No. 63A-0012 23 16 September 2022

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The definition of rock can be a source of conflict during construction. The following definitions
have been incorporated into specifications on other projects and are provided for your general
guidance:
GENERAL EXCAVATION:
Rip Rock- Any material that cannot be removed by scrapers, loaders, pans, dozers, or
graders; and requires the use of a single-tooth ripper mounted on a crawler
tractor having a minimum draw bar pull rated at not less than 56,000 pounds.
Blast Rock - Any material which cannot be excavated with a single-tooth ripper mounted
on a crawler tractor having a minimum draw bar pull rated at not less than
56,000 pounds (Caterpillar D-8K or equivalent) or by a Caterpillar 977
front-end loader or equivalent; and occupying an original volume of at least
one (1) cubic yard.
TRENCH EXCAVATION:
Blast Rock - Any material which cannot be excavated with a backhoe having a bucket
curling force rated at not less than 25,700 pounds (Caterpillar Model 330 or
equivalent, with rock teeth ), and occupying an original volume of at least
one-half(1/2) cubic yard.
5.8 Excavation Guidelines
Mass excavations and other excavations required for this project must be performed in
accordance with the United States Department of Labor, Occupational Safety and Health
Administration (OSHA) guidelines (29 CFR 1926, Subpart P, Excavations) or other applicable
jurisdictional codes for permissible temporary side-slope ratios and or shoring requirements. The
OSHA guidelines require daily inspections of excavations, adjacent areas and protective systems
by a "competent person" for evidence of situations that could result in cave-ins, indications of
failure of a protective system, or other hazardous conditions.
Excavated soils, equipment, building supplies, etc., should be placed away from the edges of the
excavation at a distance equaling or exceeding the depth of the excavation. F&R cautions that
the actual excavation slopes will need to be evaluated frequently each day by the "competent
person" and flatter slopes or the use of shoring may be required to maintain a safe excavation
depending upon excavation specific circumstances. The contractor is responsible for providing
the "competent person" and all aspects of site excavation safety.
Hazen and Sawyer Twelve Mile Creek WRF 9.0 MGD Expansion
F&R Project No. 63A-0012 24 16 September 2022

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5.9 Temporary Slopes
Our exploration did not include a detailed analysis of slope stability for any temporary or
permanent condition. However, we generally recommend temporary slopes no steeper than
1.5(H):1(V) up to a maximum height of 20 feet, for construction in undisturbed residual soils or
compacted soil fill placed in accordance with our recommendations. For temporary slopes in
existing fill materials, flatter slopes of 2.0(H):1(V) or flatter may be required depending on the
conditions observed at the time of construction. Accordingly and due to the variability of soil
conditions inherent to fill materials, temporary slopes in fill materials should be regularly
observed for signs of instability during construction.
These general excavation slope recommendations are appropriate for slopes underlain by
competent materials. However, the provided recommendations should not be used to deviate
from OSHA regulations. Construction should be performed in accordance with applicable OSHA
regulations. During construction, temporary slopes should be regularly evaluated for signs of
movement or unsafe conditions. Soil slopes should be covered for protection from rain, and
surface runoff should be diverted away from the slopes.
Hazen and Sawyer Twelve Mile Creek WRF 9.0 MGD Expansion
F&R Project No. 63A-0012 25 16 September 2022

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6.0 CONTINUATION OF SERVICES
F&R recommends that we be retained for professional and construction materials testing services
during construction of the project. Our continued involvement on the project helps provide
continuity for proper implementation of the recommendations discussed herein.
Additionally, we request the opportunity to review the plans and project specifications when these
construction documents approach completion. This review evaluates whether the
recommendations and comments provided herein have been understood and properly
implemented. The above listed services are not part of the currently authorized scope of services.
Hazen and Sawyer Twelve Mile Creek WRF 9.0 MGD Expansion
F&R Project No. 63A-0012 26 16 September 2022

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7.0 LIMITATIONS
There are important limitations to this and all geotechnical studies. Some of these limitations are discussed
in the information prepared by the Geoprofessional Business Association (GBA), which is included in
Appendix V. We recommend that you review the GBA information.
This report has been prepared for the exclusive use of Hazen and Sawyer for the specific application to the
proposed Twelve Mile Creek WRF 9.0 MGD Expansion project located in Union County, North Carolina, in
accordance with generally accepted soil and foundation engineering practices. No other warranty,express
or implied, is made. Our recommendations are based on design information furnished to us at the time
the work was performed; the data obtained from the previously described subsurface exploration
program, and generally accepted geotechnical engineering practice. The findings and recommendations
do not reflect variations in subsurface conditions,which could exist in unexplored areas of the site. In areas
where variations from the available subsurface data become apparent during construction, it will be
necessary to re-evaluate our recommendations based upon on-site observations of the conditions.
Regardless of the thoroughness of a subsurface exploration,there is the possibility that conditions in other
areas will differ from those at the boring locations,that conditions are not as anticipated by the designers,
or that the construction process has altered the soil conditions. Therefore, our experienced geotechnical
engineers should evaluate foundation construction to verify that the conditions anticipated in design
actually exist. Otherwise, we assume no responsibility for construction compliance with the design
concepts,specifications,or recommendations. In the event that changes are made in the design or location
of the proposed structures, the recommendations presented in this report shall not be considered valid
unless the changes are reviewed by our firm and recommendations of this report modified or verified in
writing. If this report is copied or transmitted to a third party, it must be copied or transmitted in its
entirety, including text, attachments, and enclosures. Interpretations based on only a part of this report
may not be valid.
Hazen and Sawyer Twelve Mile Creek WRF 9.0 MGD Expansion
F&R Project No. 63A-0012 27 16 September 2022

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APPENDIX I
Site Vicinity Map (Drawing No.1)
Boring Location Plan (Drawing No.2)

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r&R
APPENDIX II
Key to Soil Classification
Key to Boring Log Rock Classification
Soil Classification Chart
Subsurface Profiles (A and B)
Boring Logs (B-1 through B-14, B-1A, and B-7A)
Rock Core Summary and Photograph (B-1A and B-7A)

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KEY TO BORING LOG SOIL CLASSIFICATION
Particle Size and Proportion
Visual descriptions are assigned to each soil sample or stratum based on estimates of the
particle size of each component of the soil and the percentage of each component of the soil.
Particle Size Proportion
Descriptive Terms Descriptive Terms
Soil Component Particle Size Component Term Percentage
Boulder > 12 inch Major Uppercase Letters > 50%
Cobble 3 - 12 inch (e.g., SAND, CLAY)
Gravel-Coarse 3/4 -3 inch
-Fine #4 -3/4 inch Secondary Adjective 20% - 50%
Sand-Coarse #10 -#4 (e.g., sandy, clayey)
-Medium #40 -#10
-Fine #200 -#40 Minor Some 15% -25%
Silt(non-cohesive) <#200 Little 5% - 15%
Clay(cohesive) <#200 Trace 0% -5%
Notes:
1. Particle size is designated by U.S. Standard Sieve Sizes
2. Because of the small size of the split-spoon sampler relative to the size of gravel,the true percentage of gravel
may not be accurately estimated.
Density or Consistency
The standard penetration resistance values (N-values) are used to describe the density of
coarse-grained soils (GRAVEL, SAND) or the consistency of fine-grained soils (SILT, CLAY).
Sandy silts of very low plasticity may be assigned a density instead of a consistency.
DENSITY I CONSISTENCY
Term N-Value Term N-Value
Very Loose 0-4 Very Soft 0- 1
Loose 5 - 10 Soft 2 -4
Medium Dense 11 -30 Firm 5 - 8
Dense 31 -50 Stiff 9 - 15
Very Dense >50 Very Stiff 16-30
Hard >30
Notes:
1. The N-value is the number of blows of a 140 lb.Hammer freely falling 30 inches required to drive a standard
split-spoon sampler(2.0 in. O.D., 1-3/8 in. I.D.) 12 inches into the soil after properly seating the sampler 6
inches.
2. When encountered,gravel may increase the N-value of the standard penetration test and may not accurately
represent the in-situ density or consistency of the soil sampled.
F:\Branch 62\GEOWORD\REPORTS\keyblsc.enc.doc

SINCE
F&R
,NN,
KEY TO BORING LOG ROCK CLASSIFICATION (PAGE 1 OF 2)
Classification of rock is based on the following characteristics: Weathering, Discontinuities, Color and
Grain Size, Hardness,Voids, Geologic Lithology, and Rock Quality Designation (RQD).
WEATHERING
TERM SYMBOL DESCRIPTION
Fresh F No visible sign of decomposition or discoloration. Crystals are bright
Slightly Weathered WS _ Slight discoloration inward from open fractures.
Moderately Weathered WM Discoloration throughout. Weaker minerals decomposed. Strength
somewhat less than fresh rock, but cores cannot be broken by hand or
scraped by knife. Texture preserved. Joints may contain clay.
Highly Weathered WH Most minerals somewhat decomposed. Specimens can be broken by hand
with effort or shaved with knife. Core stones present in rock mass. Texture
becoming indistinct but fabric preserved.
Completely Weathered WC Minerals decomposed to soil but fabric and structure preserved (saprolite).
Specimens easily crumbled or penetrated.
Residual Soil RS Advanced state of decomposition resulting in plastic soils. Rock fabric and
structure completely destroyed.
DISCONTINUITIES
SPACING * BANDING, BEDDING, FOLIATION FAULTS,JOINTS,and other
FRACTURES
Greater than 6.0 feet Very Thick Very Wide
2.0—6.0 feet Thick Wide
8-24 inches Medium Medium
2.5—8 inches Thin Close
3 to 2.5 inches Very Thin Very Close
SPACING* LAMINATION, FOLIATION,or FAULTS,JOINTS,and other
CLEAVAGE _ FRACTURES
-3 inch Intense
Less than%inch Very Intense Extremely Close
*—Spacing is the perpendicular distance between discontinuities.
TYPE of DISCONTINUITY ATTITUDE(DIP)
TERM CONDITION TERM EXISTING
_ ANGLE
0-5
A fracture along which no movement has Horizontal
Joint occurred.
Low Angle 5-35
Bedding A natural plane dividing sedimentary rock layers Moderate Angle 35-55
Plane
Shear Plane A fracture along which some movement has High Angle 55-85
occurred.
Fault A zone of fractured rock containing one or more Vertical 95-90
shear plane and areas of gouge

SINCE
F&R
KEY TO BORING LOG ROCK CLASSIFICATION (PAGE 2 OF 2)
ROCK GRAIN SIZE
IGNEOUS AND METAMORPHIC ROCKS SEDIMENTARY ROCKS
Coarse Grained Diameter>5 mm (3/16 in) Coarse Grained Diameter>2 mm (1/16 in)
Medium Grained 1 mm (1/32 in)-5 mm (3/16 in) Medium Grained 0.06 mm-2 mm (1/16 in)
Fine Grained < 1 mm (1/32 in) Fine Grained 0.002 mm—0.06 mm
Glassy Grains not visible with unaided eye. Very Fine Grained Grains not visible with unaided eye.
VOIDS
TERM SIZE OF VOID
Pit <6 mm(1/4 inch)
Vug 6 mm—50 mm(2 inches)
Cavity 50 m—0.6 m (2 feet)
Cave >0.6 m
ROCK HARDNESS
CLASS HARDNESS FIELD TEST
II Extremely Hard Many blows with a geologic hammer required to break intact specimen.
II Very Hard Hand-held specimen breaks with hammer end of pick under more than one
blow.
III Hard Cannot be scraped or peeled with knife, hand-held specimen can be broken
with single moderate blow with pick.
IV Soft Can just be scraped or peeled with knife.
V Very Soft Material crumbles under moderate blow with sharp end of pick and can be
peeled with a knife.
ROCK QUALITY DESIGNATION ** (RQD)
ROCK QUALITY DESIGNATION **, % ROCK MASS DESCRIPTION
90-100 Excellent
75-90 Good
50-75 Fair
25-50 Poor
<25 Very Poor
** - RQD is the ratio of the cumulative length of all pieces of rock greater than or equal to four inches to
the total length drilled, expressed as a percentage

SOIL CLASSIFICATION CHART
MAJOR DIVISIONS SYMBOLS TYPICAL
GRAPH LETTER DESCRIPTIONS
•w-w .w go
CLEAN .6. iv WELL-GRADED GRAVELS,OR
-
GRAVEL GRAVELS P. aft• ./ GW SAND MIXTURES,LITTLE R NO
AND ••s ,.s FINES
+�- •+�
GRAVELLY .'. ..'. POORLY-GRADED GRAVELS,
SOILS (LITTLE OR NO FINES) lie b•• ./ Gp GRAVEL-SAND MIXTURES,LITTLE
00 111 •0 111 OR NO FINES
COARSE
•+1i • in
GRAINED GRAVELS WITH •1 4 e/ GM SILTY GRAVELS, GRAVEL-SAND-
SOILS MORE THAN 50% FINES SILT MIXTURES
OF COARSE •*411 • 411
FRACTION •
RETAINED ON NO. 'Or
4 SIEVE (APPRECIABLE GC
r+ CLAYEY GRAVELS,GRAVEL-SAND-
AMOUNT OF FINES) ` � CLAY MIXTURES
v
WELL-GRADED SANDS,GRAVELLY
CLEAN SANDS
MORE THAN 50% SAND SW SANDS, LITTLE OR NO FINES
OF MATERIAL IS AND
eeeeee
LARGER THAN SANDY NO.200 SIEVE SOILS POORLY-GRADED SANDS,
SIZE (LITTLE OR NO FINES) Sp GRAVELLY SAND,LITTLE OR NO
FINES
SANDS WITH - - SM
SANDS,SAND-SILT
MORE THAN 50% FINES _ M MIXTURES
OF COARSE —
FRACTION
PASSING ON NO.
4 SIEVE (APPRECIABLE SC MIXTURES
CLAYEY
ANDS,SAND-CLAY
AMOUNT OF FINES) —
INORGANIC SILTS AND VERY FINE
ML SANDS, ROCK FLOUR,SILTY OR
CLAYEY FINE SANDS OR CLAYEY
SILTS WITH SLIGHT PLASTICITY
SILTS r INORGANIC CLAYS OF LOW TO
FINE AND LIQUID LIMIT MEDIUM PLASTICITY,GRAVELLY
GRAINED CLAYS LESS THAN 50 / CL CLAYS,SANDY CLAYS,SILTY
SOILS _ _ _ _ CLAYS,LEAN CLAYS
OL ORGANIC SILTS AND ORGANIC
SILTY CLAYS OF LOW PLASTICITY
MORE THAN 50% INORGANIC SILTS, MICACEOUS OR
OF MATERIAL IS MH DIATOMACEOUS FINE SAND OR
SMALLER THAN SILTY SOILS
NO.200 SIEVE
SIZE SILTS
AND 1)7
LIQUID LIMIT INORGANIC CLAYS OF HIGH
CLAYS GREATER THAN 50 / CH PLASTICITY
^^^^^^^^^ OH ORGANIC CLAYS OF MEDIUM TO
HIGH PLASTICITY,ORGANIC SILTS
0 I, 0 I, \0 I,
0,, 0,, 0,, ' PEAT,HUMUS,SWAMP SOILS WITH
HIGHLY ORGANIC SOILS PT HIGH ORGANIC CONTENTS
NOTE: DUAL SYMBOLS ARE USED TO INDICATE BORDERLINE SOIL CLASSIFICATIONS

Elevation(ft) ,' B. F B.
A A A A A A A Ul In In cn LA ID ;'! co
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BORING LOG
r8,RFROEHLING : ROBERTSON Boring: B-1 (1 of 1)
Project No:63A-0012 Elevation:501± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth:25.4' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location:See boring location plan Date Drilled:7/7/22
City/State:Waxhaw, NC Driller: HPC/Z.K.
Description of Materials *Sample Sample N-Value
Elevation Depth Depth blowsue Remarks
(Classification) Blows (feet) ( )
500.7 - 0.3 �� \ SURFICIAL SOILS:4-inches r 3-2-5 0.0Groundwater not
♦♦ 7 encountered above
1 FILL:Sampled as loose, brown and orange, cave-in at 18.3 feet
clayey fine SAND(SC)with little silt and trace 12.0 following drilling
I rock fragments and organics, moist 2-3-4 7 completion.
1
i
3-5-5 3.5
1 10
1 5.0
495.0 - 6.0 "
e RESIDUUM:Very stiff, orange-brown and gray, 5 15 7 6.5
fine to medium sandy CLAY(CL)with little rock
fragments, moist 22
8.0
4-5-24 8.5
29
10.0
489.0 - 12.0 I PARTIALLY WEATHERED ROCK:Sampled as very
f dense,white, red,and gray,clayey fine SAND
� (SC)with Quartz fragments,moist 13.5
44-50/3
1' 14.3 100+
II�
484.0 - 17.0 -
Sampled as very dense,gray-brown,silty fine to
medium SAND(SM)with little clay and rock
� fragments, moist 50/6 18.5
1 19.0 100+
11
1
479.0 - 22.0 -
Sampled
SAND as very(SM)densewith,some gray-brrock own,silty fine to
fragments and
\ little clay, moist to wet 18-50/5 23.5 Wet spoon at 23.5 feet
24.4 100+
475.6 - 25.4 11 50/0 25.4
Auger refusal at 25.4 feet.
100+
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6"increments.
The sum of the second and third increments of penetration is termed the standard penetration resistance,N-Value.

BORING LOG
r8,RFROEHLING : ROBERTSON Boring: B-1A (1 of 1)
Project No:63A-0012 Elevation:501± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth:32.2' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location:See boring location plan Date Drilled:7/25/22
City/State:Waxhaw, NC Driller: HPC/J.Cain
Description of Materials *Sample Sample N-Value
Elevation Depth Depth Remarks
(Classification) Blows (feet) (blows/ft)
_ ) Auger only to 22.2 feet
1
—
-1
_1
478.8 22.2 REC=94% 22.2 refusal at 22.2 feet.
ROCK: Moderately weathered to fresh,closelyAuger
to medium fractured (moderate to high angle), RQD=49% Rock coring started at 22.2
- fine grained, hard to very hard,fair to excellent, feet.
- greenish gray,SLATE
REC=100% 25.2
RQD=100% UCS(26.3-26.6'):9,350 psi
REC=100% 30.2
RQD=100%
- „
468.8 - 32.2 32.2
Coring terminated at 32.2 feet.
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6"increments.
The sum of the second and third increments of penetration is termed the standard penetration resistance,N-Value.

Rock Core Summary and Photograph
Boring B-1A: 22.2 to 25.2' — Rec = 94%, RQD = 49%
25.2 to 30.2' — Rec = 100%, RQD = 100%
30.2 to 32.2' — Rec = 100%, RQD = 100%
1 if I 1 -- - W ....,
i
r l ' ;1 4 22.2'
Hi
1 I i AI
- faa
111
302 al 32.2
03
i
, II a ,
' : \
0
J
J _ r f
i- 25.2'
it • 1\ b .... �.
ea
I'
i. w i 4
I! 4b
J I
{ 4.4 t' ,I
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,, _,
t
' �
.i V COI
1 CO
ID`
r. * L N
p
a r r_
{ N ,, N
i ru ei La
.....
'1'
:,.,
„.
.7 : a „
`fir , `If
!. ii,j b "'a - -ate L�
-ram. - N, N
m
DATE: August 2022
r&R FROEHLING tV. ROBERTSONSCALE: As Shown
Engineering Stability Since 1881
DRAWN: DJM 63A-0012
Hazen and Sawyer BORING NO.
12-Mile Creek WRF Expansion ROCK CORE SUMMARY
Waxhaw, North Carolina AND PHOTOGRAPH B-1A

BORING LOG
r8,RFROEHLING : ROBERTSON Boring: B-2 (1 of 1)
Project No:63A-0012 Elevation:510± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth: 14.3' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location: See boring location plan Date Drilled:7/7/22
City/State:Waxhaw, NC Driller: HPC/Z.K.
Description of Materials *Sample Sample N-Value
Elevation Depth Depth Remarks
(Classification) Blows (feet) (blows/ft)
509.8 - 0.3 " \ SURFICIAL SOILS:3-inches ` 3-5-8 0.0Groundwater not
RESIDUUM:Stiff,tan and brown,fine to 13 encountered
medium sandy CLAY(CL), moist 1.5
5-4-6 2.0
10
2-5-6 3.5
11
5.0
504.0 - 6.0 d -
Very stiff to hard, light gray-brown,clayey SILT 6.5
(ML)with some fine to coarse sand,dry 7-7-16
8.0
34-47-26 8.5
10.0 23
73
498.0 - 12.0 1PARTIALLY WEATHERED ROCK:Sampled as very
` dense dark olive-gray ROCK FRAGMENTS(at
� i 13.5') 50/0.25 13.5
495.7 -, 14.3 ' 100+
Auger refusal at 14.3 feet.
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6"increments.
The sum of the second and third increments of penetration is termed the standard penetration resistance,N-Value.

BORING LOG
r8,RFROEHLING : ROBERTSON Boring: B-3 (1 of 1)
Project No:63A-0012 Elevation:508± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth:25.4' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location:See boring location plan Date Drilled:7/7/22
City/State:Waxhaw, NC Driller: HPC/Z.K.
Description of Materials *Sample Sample N-Value
Elevation Depth Depth Remarks
(Classification) Blows (feet (blows/ft)
507.8 - 0.2 • '
1 \ SURFICIAL SOILS:2-inches
1-3-5 0• Groundwater not
8 encountered above
1 FILL:Sampled as loose,orange-brown and tan, cave-in at 21.2 feet
1 clayey fine to medium SAND(SC)with little silt 1.5
and rock fragments, moist 3-3-4 2.0 following drilling
- completion.
3-5-5 3.5
10
II 5.0
502.0 - 6.0 s -
I I Sampled as medium dense,orange-brown and 6.5
: 1 gray-brown, clayey fine to coarse SAND(SC)with 6-8-10
little rock fragments, moist 18
500.0 8.0 • .0
RESIDUUM: Hard,tan and light brown, clayey 88.5
SILT(ML)with some fine to medium sand,dry 18-21-15
36
10.0
496.0 12.0 IPARTIALLY WEATHERED ROCK:Sampled as
` hard, ,light gray-brown clayey SILT(ML)with
� little fine sand, dry 33-50/3 13.5
1' 14.3 100+
II�
491.0 - 17.0 -
Sampled as very dense, brown and gray,clayey
1 fine SAND(SC)with little rock fragments,dry
ilk 24-50/4 18.5
19.3 100+
I�
i
486.0 - 22.0 ,i -
Sampledtocoarse asr verySAND dense(SC), browithwn and some grayrock,clayey
� fine fragments, moist 50/2 i 23.5 Wet spoon at 23 feet
100+
482.6 - 25.4 50/0 25.4
Auger refusal at 25.4 feet.
100+
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6"increments.
The sum of the second and third increments of penetration is termed the standard penetration resistance,N-Value.

BORING LOG
r8,RFROEHLING : ROBERTSON Boring: B-4 (1 of 1)
Project No:63A-0012 Elevation:509± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth:23.1' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location:See boring location plan Date Drilled:7/7/22
City/State:Waxhaw, NC Driller: HPC/Z.K.
Description of Materials *Sample Sample N-Value
Elevation Depth De(Classification) Blows (feet (blows/ft) Remarks
508.7 - 0.3 s. \ SURFICIAL SOILS:4-inches r 3-5-7 0.0Groundwater not
RESIDUUM:Stiff,tan and brown,silty CLAY(CL) 12 encountered
with little fine sand and rock fragments,dry 2.5
6-8-5 13
No Recovery 3.5 to 5' 8-6-4 3.5
10
5.0
No Recovery 6.5 to 8'-Very stiff 7-10-14 6.5
24
501.0 - 8.0 i( 8.0
PARTIALLY WEATHERED ROCK:Sampled as 8.5
` hard,tan and brown, clayey SILT(ML)with some 23-50/6
� fine to medium sand, dry 9.5 100+
II�
-
497.0 12.0 Sampled as very dense,tan and brown,clayey
fine to coarse SAND(SC)with some rock
� fragments,dry 13.5
50/3
ll 100+
IlI �
50/3 i
18.5
100+
II �
11�
i
485.9 - 23.1 - 23.1
Auger refusal at 23.1 feet. 50/0
100+
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6"increments.
The sum of the second and third increments of penetration is termed the standard penetration resistance,N-Value.

BORING LOG
r8,RFROEHLING ROBERTSON Boring: B-5 (1 of 1)
0
Project No: 63A-0012 Elevation: 550± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth: 29.5' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location:See boring location plan Date Drilled: 7/5/22
City/State:Waxhaw, NC Driller: HPC/Z.K.
Description of Materials *Sample Sample N-Value
Elevation Depth D(Classification) Blows (feeth (blows/ft) Remarks
549.9 - 0.1 i 1 SURFICIAL SOILS: 1-inch [ 6-12-18 0. Groundwater not
FILL:Sampled as hard, orange-brown and 30 encountered
brown,silty CLAY (CL) with little fine to coarse 1.5
548.0 - 2.0 I sand and rock fragments, moist / 14-35-50/5 2'0
PARTIALLY WEATHERED ROCK LENS:Sampled 100+
546.5 3.5 fine to medium sand and rock fragments, dry / 26-20-34
RESIDUUM: Hard,gray-brown, clayey SILT 54
5.0
(ML) with little fine sand, dry
544.0 6.0 I I PARTIALLY WEATHERED ROCK LENS:Sampled 26 50/5 6.5
as hard,gray-brown, clayey SILT(ML) with little
542.0 - 8.0 11fine to medium sand and rock fragments, dry 7.4 100+
RESIDUUM: Hard,gray- brown, silty CLAY(CL) 8.5
with some fine to medium sand, moist 9-42-38
80
10.0
8-27-27 13.5
54
15.0
533.0 - 17.0 i rl Wp
I hardPARTIALLY, light olive-gray-brownEATHERED ROCK:, clayeySam SILTled(M asL)
with some fine to medium sand, dry 31 50/3 18.5
193 100+
42-50/5 23.5
24.4 100+
ii
28-50/6 28.5
520.5 - 29.5 I i 29.5 100+
Boring terminated at 29.5 feet.
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6" increments. The
sum of the second and third increments of penetration is termed the standard penetration resistance, N-Value.

BORING LOG
r8,RFROEHLING : ROBERTSON Boring: B-6 (1 of 1)
Project No:63A-0012 Elevation:551± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth:28.4' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location:See boring location plan Date Drilled:7/6/22
City/State:Waxhaw, NC Driller: HPC/Z.K.
Description of Materials *Sample Sample N-Value
Depth
Elevation Depth (Classification) Blows (feet) (blows/ft) Remarks
550.9 - 0.1 \ SURFICIAL SOILS: 1-inch [ 5-5-8 0.0 Groundwater not
FILL:Sampled as stiff, brown, orange,and gray,
�i� 13 encountered
fine to medium sandy CLAY(CL)with some rock 1.5
549.0 2.0 % \fragments, moist
g , / 11 19 20 2.0
RESIDUUM: Hard,gray-brown and 39
547.5 - 3.5 orange-brown,silty CLAY(CL)with some fine to 3.5
' ,medium sand, moist / 18-15-50/4
PARTIALLY WEATHERED ROCK:Sampled as 4.8 100+
i' hard, brown-gray,silty CLAY(CL)with some fine
I ( to medium sand, dry
I� 50/3 6.5
100+
543.0 8.0 i' Sampled as very dense Rock Fragments(about 50 4 8.5
50%)and brown-gray,silty CLAY(CL)with some / ,
`� fine to medium sand, dry 100+
II�
539.0 12.0 lil Sampled as very dense Rock Fragments with
-
some gray clayey fine to medium sand, dry
`� 13.5
i 50/4 ,
ll 100+
ill.,
50/1 i
18.5
100+
ill.
II �
`1� 23.5
50/2 i
100+
11�
I �11i,
522.6 - 28.4 'i ' S0/0 28.4
Auger refusal at 28.4 feet.
100+
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6"increments.
The sum of the second and third increments of penetration is termed the standard penetration resistance,N-Value.

BORING LOG
r8,RFROEHLING : ROBERTSON Boring: B-7 (1 of 1)
Project No:63A-0012 Elevation:550± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth:23.5' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location:See boring location plan Date Drilled:7/6/22
City/State:Waxhaw, NC Driller: HPC/Z.K.
Description of Materials *Sample Sample N-Value
Elevation Depth Depth blows/ft Remarks
(Classification) Blows (fee ( )
549.8 - 0.2 _' \ SURFICIAL SOILS:2-inches ` 4-8-10 0.0Groundwater not
RESIDUUM:Very stiff,tan-brown-gray,fine to 18 encountered
medium sandy CLAY(CL), moist 1.5
14-13-11 2.0
24
546.5 - 3.5 041 g y y Y 11-12-11 3.5
Medium dense,tan-brown ra ,cla a fine to
ors medium SAND(SC), dry 23
5.0
544.0 6.0 1 '` PARTIALLY WEATHERED ROCK:Sampled as 6.5
` hard, olive gray brown,fine to medium sandy 27-50/5
� CLAY(CL)with little rock fragments,dry 7.4 100+
542.0 8.0 i Sampled as very dense,gray-brown,clayey fine 8.5
to medium SAND(SC)with some rock fragments, 23-35-50/4
`� dry 100+
9.8
11i
Ili
13.5
18-50/5
14.4 100+
1111
II�
533.0 - 17.0 -
Sampled as very dense, light gray-brown,clayey
fine to medium SAND(SC)with some rock
`� fragments and little silt,dry 50 3 18.5
/ i
100+
11�
I �11i,
526.5 - 23.5 - 11 50/0 23.5
Auger refusal at 23.5 feet.
100+
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6"increments.
The sum of the second and third increments of penetration is termed the standard penetration resistance,N-Value.

BORING LOG
r8,RFROEHLING : ROBERTSON Boring: B-7A (1 of 1)
Project No:63A-0012 Elevation:550± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth:32.3' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location:Offset 7 feet S of B-7 Date Drilled:7/25/22
City/State:Waxhaw, NC Driller: HPC/J.Cain
Description of Materials *Sample Sample N-Value
Elevation Depth Depth Remarks
(Classification) Blows (feet) (blows/ft)
_ ) Auger only to 22.3 feet
1
_1
_1
—1
527.7 22.3 100% 22.3 er refusal at 22.3 feet.
ROCK: Moderately weathered to fresh,closely REC=
g
to medium fractured (moderate to high angle), RQD=10% AuRock coring started at 22.3
- fine grained, hard to very hard,very poor to feet.
- excellent RQD,greenish gray,SLATE
REC=100% 25.8 UCS(26.3-26.6'):7,130 psi
RQD=100%
REC=100% 30.8
RQD=100%
517.7 - 32.3 32.3
Coring terminated at 32.3 feet.
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6"increments.
The sum of the second and third increments of penetration is termed the standard penetration resistance,N-Value.

Rock Core Summary and Photograph
Boring B-7A: 22.3 to 25.8' — Rec = 100%, RQD = 10%
25.8 to 30.8' — Rec = 100%, RQD = 100%
30.8 to 32.3' — Rec = 100%, RQD = 100%
y 22.3'
i 4, itt
1
, : o
' w-
( ,
1 ....4
1,3
4
C
) N::
,i4 gr25.8
i ' '`i.
I .
di
y t e t+�
'A' �l
a_
'" 3 2.3' ' ,
N .
A
DATE: August 2022
r&R FROEHLING t'. ROBERTSON
SCALE: As Shown
Engineering Stability Since 1881
DRAWN: DJM 63A-0012
Hazen and Sawyer BORING NO.
12-Mile Creek WRF Expansion ROCK CORE SUMMARY
Waxhaw, North Carolina AND PHOTOGRAPH B-7A

BORING LOG
r8,RFROEHLING ROBERTSON Boring: B-8 (1 of 1)
0
Project No: 63A-0012 Elevation: 550± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth: 16.6' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location:See boring location plan Date Drilled: 7/6/22
City/State:Waxhaw, NC Driller: HPC/Z.K.
Description of Materials *Sample Sample N-Value
Elevation Depth Depth Remarks
(Classification) Blows (feet (blows/ft)
549.9 - 0.1 \ SURFICIAL SOILS:0.5-inch r 7-11-14 0• Groundwater not
RESIDUUM:Very stiff, orange-brown,fine to 25 encountered
0 coarse sandy CLAY(CL)with little rock 1.5
548.0 - 2.0 'fragments, moist j 10-14-18 2.0
Hard, orange-brown and gray-brown,silty CLAY 32
546.5 - 3.5 (CL) with some fine to medium sand and little 3.5
`rock fragments, moist / 32 50/4
lj PARTIALLY WEATHERED ROCK:Sampled as 4.3 100+
I very dense,gray-brown,silty CLAY(CL) with
544.0 - 6.0 I some fine to medium sand and little rock
fragments, dry 50/3 6.5
li Sampled as very dense, light gray-brown, clayey 100+
fine to coarse SAND (SC) with some rock
'i ‘ fragments, dry11
8 5
50/0.5 I
100+
538.0 - 12.0 -
Sampled as very dense, light gray, clayey fine to
coarse SAND (SC) with rock fragments (about
50% of sample), dry 50/2 13.5
100+
I7
533.4 16.6 I 50/0 16.6
Auger refusal at 16.6 feet.
100+
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"0.D.,1.375"I.D.sampler a total of 18 inches in three 6" increments. The
sum of the second and third increments of penetration is termed the standard penetration resistance, N-Value.

BORING LOG
r8,RFROEHLING ROBERTSON Boring: B-9 (1 of 1)
0
Project No: 63A-0012 Elevation: 550± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth: 15.0' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location:See boring location plan Date Drilled: 7/5/22
City/State:Waxhaw, NC Driller: HPC/Z.K.
Description of Materials *Sample Sample N-Value
Elevation Depth Depth Remarks
(Classification) Blows (feet (blows/ft
)
549.9 - 0.1 ' ' \ SURFICIAL SOILS: 1-inch [ 6-12-11 O. Groundwater not
RESIDUUM:Very stiff, brown,silty CLAY(CL) 23 encountered
with little fine to medium sand and rock 1.5
548.0 2.0 '1 \fragments, dry / 16-50/2 2.0
547.0 3.0 ' I I PARTIALLY WEATHERED ROCK:Sampled as 2.7 100+
11 hard,gray-brown,silty CLAY(CL) with little fine / 50/2 3.5
\sand, dry
Sampled as hard, light gray-brown,silty CLAY 100+
'll ‘ (CL) with little fine to medium sand and some
rock fragments, dry
50/1 i 6.5
100+
50/4 8.5
100+1i I ill , 50/5 13.5
100+
535.0 15.0
Boring terminated at 15 feet.
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6" increments. The
sum of the second and third increments of penetration is termed the standard penetration resistance, N-Value.

BORING LOG
r8,RFROEHLING ROBERTSON Boring: B-10 (1 of 2)
0
Project No: 63A-0012 Elevation: 549± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth:45.0' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location:See boring location plan Date Drilled: 7/5/22
City/State:Waxhaw, NC Driller: HPC/Z.K.
Description of Materials *Sample Sample N-Value
Elevation Depth Depth Remarks
(Classification) Blows (feet) (blows/ft)
548.9 - 0.1 pq \ SURFICIAL SOILS:4 inches [ 3-8-7 0• Groundwater
FILL:Sampled as stiff,gray-orange-brown, silty 15 encountered at
approximately 39 feet
CLAY(CL)with some fine to medium sand and 1.5 immediatelyafter
547.0 2.0 i little rock fragments, moist 5 6 10 2'0 completion of drilling.
Sampled as very stiff, red-brown, clayey SILT 16
545.5 - 3.5 r (MH), moist / 579 3.5
RESIDUUM:Very stiff to stiff, orange-brown 16
and gray-brown, silty CLAY(CL), moist 5.0
2-7-7 6.5
14
541.0 - 8.0 IrA 1 8.0
FrAp Medium dense, orange-brown and tan, clayey 8.5
0 fine SAND (SC), dry 9-11-11
0940 22
0,0, 10.0
F I
0,0,
F I
0,0,
F I FI11-14-16 13.5
0,0, 30
0,0, 15.0
F I
pi
532.0 17.0 i I PARTIALLY WEATHERED ROCK:Sampled as
i. hard,tan and light brown, clayey SILT(ML)with
little fine sand, dry 20-50/5
18.5
19.4 100+
15-32-50/6 23.5
100+
II25.0
522.0 27.0 �'
RESIDUUM: Hard, brown and tan, fine to
medium sandy CLAY(CL) with some silt, moist
14-25-31 28.5
56
30.0
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"0.D.,1.375"I.D.sampler a total of 18 inches in three 6" increments. The
sum of the second and third increments of penetration is termed the standard penetration resistance, N-Value.

BORING LOG
r8,RFROEHLING : ROBERTSON Boring: B-10 (2 of 2)
Project No:63A-0012 Elevation:549± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth:45.0' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location:See boring location plan Date Drilled:7/5/22
City/State:Waxhaw, NC Driller: HPC/Z.K.
Description of Materials *Sample Sample N-Value
Elevation Depth Depth Remarks
(Classification) Blows (feet) (blows/ft)
517.0 32.0 II PARTIALLY WEATHERED ROCK:Sampled as very
�1 dense, brown and gray, clayey fine to coarse
SAND(SC)with some rock fragments and little 42 50/4 33.5
`
i silt, moist 34.3 100+
it
111�
a 50/3 i
38.5
100+
Iii
11�
l'i
505.5 - 43.5 ii 50/0.5 43.5
11 Sampled as very dense gray rock fragments, dry I
100+
504.0 - 45.0
Boring terminated at 45 feet.
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6"increments.
The sum of the second and third increments of penetration is termed the standard penetration resistance,N-Value.

BORING LOG
r8,RFROEHLING : ROBERTSON Boring: B-11 (1 of 1)
Project No:63A-0012 Elevation:549± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth: 18.7' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location: See boring location plan Date Drilled:7/5/22
City/State:Waxhaw, NC Driller: HPC/Z.K.
Description of Materials *Sample Sample N-Value
Depth
Elevation Depth (Classification) Blows fet) (blows/ft) Remarks
548.9 - 0.1 * \ SURFICIAL SOILS: 1-inch [ 9-13-20 0.0 Groundwater not
�� 33 encountered
: 1 FILL:Sampled as hard,orange-brown,silty CLAY
Lid (CL)with little fine to medium sand and rock 1.5
547.0 - 2.0 111 \fragments, moist / 18-40-50/5 2.0
PARTIALLY WEATHERED ROCK:Sampled as 100+
lk hard,tan and brown, clayey SILT(ML)with some 50/4
3.5
/
Ili,.
fine to medium sand and rock fragments,dry i
100+
11
i
50/5 6.5
100+
541.0 - 8.0 itSampled as hard,tan and brown,silty CLAY(CL) 8.5
with some fine to medium sand and rock 50/5
`� fragments,dry 100+
II �
11�537.0 12.0 i Sampled as very dense,tan and brown,clayey
(ineabout to coarse50%of SAsampND(SC)le) withdry quartz fragments
� f -
, 13.5
50/4 i
100+
11�
II �
11�531.0 - 18.0 1 _
'� Sampled as very dense Rock Fragments with 18.5
530.3 18.7 some tan and brown,fine to coarse clayey SILT 50/2
I(ML),dry 100+
Boring terminated at 18.7 feet.
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6"increments.
The sum of the second and third increments of penetration is termed the standard penetration resistance,N-Value.

BORING LOG
r8,RFROEHLING : ROBERTSON Boring: B-12 (1 of 1)
Project No:63A-0012 Elevation:548± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth:22.5' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location:See boring location plan Date Drilled:7/6/22
City/State:Waxhaw, NC Driller: HPC/Z.K.
Description of Materials *Sample Sample Nth -Value
Elevation Depth (Classification) Blows (feet (blows/ft) Remarks
547.8 0.3 ��� \ SURFICIAL SOILS:3-inches ` 4-9-9 0• Groudwater not
� 18 encountered
; FILL:Sampled as very stiff, orange-brown,
546.0 2.0 '4 clayey SILT(MH)with some fine to medium sand 12.5
and little rock fragments, dry / 6-11-17
RESIDUUM:Very stiff, brown and tan,fine to 28
medium sandy CLAY(CL), dry 5-11-13 3.5
24
5.0
542.0 6.0 ( PARTIALLY WEATHERED ROCK:Sampled as 6.5
hard, orange brown,silty CLAY(CL)with some 8-10-50/6
\ fine to medium sand, moist 100+
540.0 - 8.0 i, 1 8.0
Sampled as hard,gray-brown, clayey SILT(ML) 50/5 8.5
` with some fine to medium sand and little rock ,
� fragments 100+
11�
II �
) 13.5
38-22-50/5
100+
(� 14.9
i
531.0 - 17.0 -
Sampled as very dense gray rock fragments with
1 some fine to coarse sandy SILT(ML),dry
ilk 50/1 18.5
100+
11'
lir�
525.5 - 22.5 I 22.5
Auger refusal at 22.5 feet. 50/0
100+
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6"increments.
The sum of the second and third increments of penetration is termed the standard penetration resistance,N-Value.

BORING LOG
r8,RFROEHLING ROBERTSON Boring: B-13 (1 of 1)
0
Project No: 63A-0012 Elevation: 553.5± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth: 23.3' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location:See boring location plan Date Drilled: 7/5/22
City/State:Waxhaw, NC Driller: HPC/Z.K.
Description of Materials *Sample Sample N-Value
Elevation Depth Depth Remarks
(Classification) Blows (feet) (blows/ft)
553.4 - 0.1 \ SURFICIAL SOILS:4 inches [ 4-11-9 0• Groundwater not
FILL:Sampled as very stiff, orange-brown and 20 encountered
tan, clayey SILT(MH) with little fine to medium 1.5
sand and rock fragments, dry 8-10-11 2.0
21
550.0 3.5 4Sampled as medium dense to loose, brown and 11-16-14 3.5
tan, clayey fine to medium SAND (SC)with little 30
rock fragments, dry 5.0
4-4-4 6.5
8
8.0
3-2-2 8.5
4
10.0
541.5 12.0 RESIDUUM:Very dense, brown and gray,silty
— . fine to coarse SAND (SM) with little rock
— fragments and clay, moist 15 26 14 13.5
• 40
15.0
•
536.5 - 17.0 ' PARTIALLY WEATHERED ROCK:Sampled as
very dense, brown and gray, silty fine to coarse
11 SAND (SM)with some rock fragments and little 27-50/3 18.5
clay, dry 193 100+
I
II
530.2 - 23.3 1 50/0 23.3
Auger refusal at 23.3 feet.
100+
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"0.D.,1.375"I.D.sampler a total of 18 inches in three 6" increments. The
sum of the second and third increments of penetration is termed the standard penetration resistance, N-Value.

BORING LOG
r8,RFROEHLING : ROBERTSON Boring: B-14 (1 of 1)
Project No:63A-0012 Elevation:554± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth:28.7' Hammer Type:Automatic
Project: 12-Mile Creek WRF Boring Location:See boring location plan Date Drilled:7/6/22
City/State:Waxhaw, NC Driller: HPC/Z.K.
Description of Materials *Sample Sample N-Value
Elevation Depth Depth (blows
Remarks
(Classification) Blows (feet) ( )
553.8 - 0.3 , \ SURFICIAL SOILS:3-inches ` 3-5-13 0• Groundwater not
18 encountered
FILL:Sampled as very stiff, orange-brown and
tan,fine to coarse sandy SILT(ML)with little clay 2.5
552.0 - 2.0 44 `and rock fragments, moist j 11-13-30
4 Sampled as hard to very stiff, orange-brown and 43
1 tan,clayey SILT(MH)with some fine to medium 3.5
sand and trace rock fragments, moist 7 9 12 21
•
1 5.0
548.0 - 6.0 *4 -
�i� Sampled as medium dense,orange-brown and 6.5
tan,clayey fine to medium SAND(SC)with trace 4-9-5
4 rock fragments, moist 14
546.0 - 8.0 ;1 1 8.0
I Sampled as loose, orange-brown and tan, 8.5
4 clayey-silty fine to medium SAND(SC-SM)with 4-6-2
trace rock fragments, moist 8
41 10.0
14
542.0 - 12.0 *. -
� Sampled as loose, orange-brown and tan, clayey
4 fine to medium SAND(SC)with trace rock
1 fragments, moist 4-3-2
13.5
4 5
4 15.0
14
14
537.0 - 17.0 I PARTIALLY WEATHERED ROCK:Sampled as very
dense,orange-brown,silty fine to medium SAND
`\ (SM)with little clay and rock fragments,moist 18.5
35-50/4
19.3 100+
II�
II �
11�
23.5
50/6 , 24.0
`� 100+
II �
11�
1`11
525.3 - 28.7 50/2 28.5
Boring terminated at 28.7 feet. 100+
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6"increments.
The sum of the second and third increments of penetration is termed the standard penetration resistance,N-Value.

r&R
APPENDIX III
Material Test Reports
Proctor Reports

Froehling&Robertson,Inc.
r84R Charlotte Office
3300 International Airport Drive,Suite 600 MaterialCharlotte,NC 28208 Test Report
Phone:[phone] www.FandR.com
S
Client: Hazen and Sawyer-Charlotte CC: Report No: ASM:6322-02300
9101 Southern Pine Blvd
Charlotte, NC 28273
Project: 63A0012
12-Mile Creek WRF MGD Expansion
8299 Kensington Drive
Waxhaw, NC 28173 Review Date:
Material Details AIM
Source Sampled From
Sample Details IIIII
Sample ID 6322-02300-SO1 6322-02300-502 6322-02300-S03 6322-02300-SO4 6322-02300-S05 6322-02300-S06
Field Sample ID
Date Sampled 7/14/2022
Boring No B-1 B-1 B-2 B-3 B-3 B-7
Depth 3.5-5 13.5-15 3.5-5 2-3.5 18.5-20 3.5-5
Other Test Results
Description Method Results
Passing No.200(75 pm)(%) ASTM D1140 49 28 57 47 29 30
Procedure A A A A A A
Soaking Period(min)
Initial Dry Mass(g) 128.1 173.8 114.8 146.5 149.2 173.7
Water Content Determined No No No No No No
Water Content(%) ASTM D2216 14.3 8.6 19.3 16.1 12.7 9.9
Date Tested
Liquid Limit ASTM D4318 43 30 41 40 31 33
Plastic Limit 26 23 26 24 22 23
Plasticity Index 17 7 15 16 9 10
Tested By
Date Tested
Comments Legend
The results provided herein relate only to the items inspected and/or tested.This report shall not be reproduced,except in full,without the prior written approval of F&R.
Form No:18980,Report No:ASM:6322-02300 ©2000-2022 QESTLab by SpectraQEST.com Page 1 of 3

Froehling&Robertson,Inc.
r84R Charlotte Office
3300 International Airport Drive,Suite 600 Material Test Report
Charlotte,NC 28208
Phone:[phone] www.FandR.com
S
Client: Hazen and Sawyer-Charlotte CC: Report No: ASM:6322-02300
9101 Southern Pine Blvd
Charlotte, NC 28273
Project: 63A0012
12-Mile Creek WRF MGD Expansion
8299 Kensington Drive
Waxhaw, NC 28173 Review Date:
Material Details AIM
Source Sampled From
Sample Details
Sample ID 6322-02300-S07 6322-02300-S08 6322-02300-S09 6322-02300-S10 6322-02300-S11 6322-02300-S12
Field Sample ID
Date Sampled
Boring No B-10 B-12 B-13 B-13 B-14 B-14
Depth 8.5-10 2-3.5 3.5-5 8.5-10 6.5-8 13.5-15
Other Test Results
Description Method Results -11
Passing No.200(75 pm)(%) ASTM D1140 23 57 43 30 44 30
Procedure A A A A A A
Soaking Period(min)
Initial Dry Mass(g) 187.0 183.6 174.9 187.1 174.8 160.7
Water Content Determined No No No No No No
Water Content(%) ASTM D2216 10.5 8 8.6 9.9 10.8 11.2
Date Tested
Liquid Limit ASTM D4318 38 41 33 36 36 32
Plastic Limit 22 25 23 24 21 24
Plasticity Index 16 16 10 12 15 8
Tested By
Date Tested
Comments Legend
The results provided herein relate only to the items inspected and/or tested.This report shall not be reproduced,except in full,without the prior written approval of F&R.
Form No:18980,Report No:ASM:6322-02300 ©2000-2022 QESTLab by SpectraQEST.com Page 2 of 3

Froehling&Robertson,Inc.
r.8,1z Charlotte Office
3300 International Airport Drive,Suite 600 Material Test Report
Charlotte,NC 28208
Phone:[phone] www.FandR.com
Client: Hazen and Sawyer-Charlotte CC: Report No: ASM:6322-02300
9101 Southern Pine Blvd
Charlotte, NC 28273
Project: 63A0012
12-Mile Creek WRF MGD Expansion
8299 Kensington Drive
Waxhaw, NC 28173 Review Date:
Material Details
Source Sampled From
Sample Details
Sample ID 6322-02300-S13 6322-02300-S14 6322-02300-S15
Field Sample ID
Date Sampled
Boring No B-2 B-6 B-12
Depth 2-8 2-8 2-8
Other Test
Descriptio tMe hod Results
Passing No.200(75 pm)(%) ASTM D1140 52 59 55
Procedure A A A
Soaking Period(min)
Initial Dry Mass(g) 207.2 236.0 263.7
Water Content Determined No No No
Water Content(%) ASTM D2216 14.2 11.8 11.8
Date Tested
Liquid Limit ASTM D4318 36 35 37
Plastic Limit 19 11 21
Plasticity Index 17 24 16
Tested By
Date Tested
Std.Maximum Dry Unit Weight(Ibf/ft') ASTM D698 113.6 124.5 118.2
Std.Optimum Water Content(%) 14.0 11.5 13.4
Method C C C
Preparation Method Moist Moist Moist
Test Portion Specific Gravity Assumed
Comments Legend
The results provided herein relate only to the items inspected and/or tested.This report shall not be reproduced,except in full,without the prior written approval of F&R.
Form No:18980,Report No:ASM:6322-02300 ©2000-2022 QESTLab by SpectraQEST.com Page 3 of 3

r&R Froehling 8r Robertson,Inc.
Charlotte Office
3300 International Airport Drive,Suite 600 Proctor Report
Charlotte,NC 28208
Phone:[phone] www.FandR.com
A,
Client: Hazen and Sawyer-Charlotte CC: Report No: PTR:6322-02300-S13
9101 Southern Pine Blvd
Charlotte, NC 28273
Project: 63A0012
12-Mile Creek WRF MGD Expansion
8299 Kensington Drive
Waxhaw, NC 28173 Review Date:
Sample Details
Sample ID: 6322-02300-S13 Date Sampled:
Sampling Method:Auger Cuttings
Source: Boring B-2
Material: Bulk Sample 2 to 8 feet
Specification:
Location: Bulk
Dry Unit Weight -Water Content Relationship Test Results
ASTM D698
— Compaction Curve Std.Maximum Dry Unit Weight(Ibf/ft3): 113.6
Std.Optimum Water Content(%): 14.0
115.0 Method: C
Preparation Method: Moist
114.5 Determined By: Assumed
Tested By:
114.0 Date Tested:
ASTM D4318
Liquid Limit: 36
113.5 Plastic Limit: 19
\\ Plasticity Index: 17
c 113.0
Tested By:
Date Tested:
112.5
D 112.0
111.5
111.0
110.5
110.0
9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0
Water Content(%)
Comments
The results provided herein relate only to the items inspected and/or tested.This report shall not be reproduced,except in full,without the prior written approval of F&R.
Form No:110031,Report No:PTR:6322-02300-S13 ©2000-2022 QESTLab by SpectraQEST.com Page 1 of 1

r&R Froehling 8r Robertson,Inc.
Charlotte Office
3300 International Airport Drive,Suite 600 Proctor Report
Charlotte,NC 28208
Phone:[phone] www.FandR.com
A,
Client: Hazen and Sawyer-Charlotte CC: Report No: PTR:6322-02300-S14
9101 Southern Pine Blvd
Charlotte, NC 28273
Project: 63A0012
12-Mile Creek WRF MGD Expansion
8299 Kensington Drive
Waxhaw, NC 28173 Review Date:
Sample Details
Sample ID: 6322-02300-S14 Date Sampled:
Sampling Method:Auger Cuttings
Source: Boring B-6
Material: Bulk Sample 2 to 8 feet
Specification:
Location: Bulk
Dry Unit Weight -Water Content Relationship Test Results
ASTM D698
— Compaction Curve Std.Maximum Dry Unit Weight(Ibflft3): 124.5
Std.Optimum Water Content(%): 11.5
125.0 Method: C
Preparation Method: Moist
Determined By: Assumed
124.5
Tested By:
124.0 Date Tested:
ASTM D4318
Liquid Limit: 35
123.5 Plastic Limit: 11
Plasticity Index: 24
c 123.0
Tested By:
.csDate Tested:
122.5
D 122.0
121.5
121.0
120.5
120.0
7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0
Water Content(%)
Comments
The results provided herein relate only to the items inspected and/or tested.This report shall not be reproduced,except in full,without the prior written approval of F&R.
Form No:110031,Report No:PTR:6322-02300-S14 ©2000-2022 QESTLab by SpectraQEST.com Page 1 of 1

r&R Froehling 8r Robertson,Inc.
Charlotte Office
3300 International Airport Drive,Suite 600 Proctor Report
Charlotte,NC 28208
Phone:[phone] www.FandR.com
A,
Client: Hazen and Sawyer-Charlotte CC: Report No: PTR:6322-02300-S15
9101 Southern Pine Blvd
Charlotte, NC 28273
Project: 63A0012
12-Mile Creek WRF MGD Expansion
8299 Kensington Drive
Waxhaw, NC 28173 Review Date:
Sample Details
Sample ID: 6322-02300-S15 Date Sampled:
Sampling Method:Auger Cuttings
Source: Boring B-12
Material: Bulk Sample 2 to 8 feet
Specification:
Location: Bulk
Dry Unit Weight -Water Content Relationship Test Results
ASTM D698
— Compaction Curve Std.Maximum Dry Unit Weight(Ibf/ft3): 118.2
Std.Optimum Water Content(%): 13.4
118.5 Method: C
Preparation Method: Moist
118.0 Determined By: Assumed
Tested By:
117.5 Date Tested:
ASTM D4318
Liquid Limit: 37
117.0 Plastic Limit: 21
Plasticity Index: 16
c 116.5
Tested By:
.csDate Tested:
116.0
D 115.5
115.0
114.5
114.0
113.5
7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0
Water Content(%)
Comments
The results provided herein relate only to the items inspected and/or tested.This report shall not be reproduced,except in full,without the prior written approval of F&R.
Form No:110031,Report No:PTR:6322-02300-S15 ©2000-2022 QESTLab by SpectraQEST.com Page 1 of 1

r&R
APPENDIX IV
Extent of Select Backfill for Retaining Walls (Drawing No. 3)

•
4.
•
•
v4
Select Crushed
Stone Backfill
e •
.4 ..
•
a • ,
45°
H/2
SINCE DATE: September 2022
FROEHLING & ROBERTSON, INC.
C�n Engineering Stability Since 1881 SCALE: As Shown
r IK_ 3300 International Airport Drive,Suite 600
Charlotte, North Carolina,28208 DRAWN: AF 63A-0012
n T 704.596.2889 I F 704.596.3784
12-Mile Creek WRF 9.0 MGD Expansion EXTENT OF SELECT DRAWING NO.
Waxhaw, North Carolina BACKFILL FOR
Hazen and Sawyer RETAINING WALLS 3

r&R
APPENDIX V
GBA Publication "Important Information about This
Geotechnical Engineering Report"

Important Information about This
Geotecbnical-Engineering
Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.
While you cannot eliminate all such risks, you can manage them. The following information is provided to help.
The Geoprofessional Business Association (GBA) Typical changes that could erode the reliability of this report include
has prepared this advisory to help you—assumedly those that affect:
a client representative—interpret and apply this • the site's size or shape;
geotechnical-engineering report as effectively • the function of the proposed structure,as when it's
as possible. In that way, clients can benefit from changed from a parking garage to an office building,or
a lowered exposure to the subsurface problems from a light-industrial plant to a refrigerated warehouse;
• the elevation,configuration,location,orientation,or
that,for decades, have been a principal cause of weight of the proposed structure;
construction delays, cost overruns, claims, and • the composition of the design team;or
disputes. If you have questions or want more . project ownership.
information about any of the issues discussed below,
contact your GBA-member geotechnical engineer. As a general rule,always inform your geotechnical engineer of project
Active involvement in the Geoprofessional Business changes-even minor ones-and request an assessment of their
Association exposes geotechnical engineers to a impact.The geotechnical engineer who prepared this report cannot accept
wide array of risk-confrontation techniques that can responsibility or liability for problems that arise because the geotechnical
be of genuine benefit for everyone involved with a engineer was not informed about developments the engineer otherwise
construction project. would have considered.
This Report May Not Be Reliable
Geotechnical-Engineering Services Are Performed for Do not rely on this report if your geotechnical engineer prepared it:
Specific Purposes, Persons, and Projects • for a different client;
Geotechnical engineers structure their services to meet the specific • for a different project;
needs of their clients.A geotechnical-engineering study conducted for a different site(that may or may not include all or a
for a given civil engineer will not likely meet the needs of a civil- portion of the original site);or
works constructor or even a different civil engineer.Because each • before important events occurred at the site or adjacent
geotechnical-engineering study is unique,each geotechnical- to it;e.g.,man-made events like construction or
engineering report is unique,prepared solely for the client.Those who environmental remediation,or natural events like floods,
rely on a geotechnical-engineering report prepared for a different client droughts,earthquakes,or groundwater fluctuations.
can be seriously misled.No one except authorized client representatives
should rely on this geotechnical-engineering report without first Note,too,that it could be unwise to rely on a geotechnical-engineering
conferring with the geotechnical engineer who prepared it.And no one report whose reliability may have been affected by the passage of time,
•not even you-should apply this report for any purpose or project except because of factors like changed subsurface conditions;new or modified
the one originally contemplated. codes,standards,or regulations;or new techniques or tools.If your
geotechnical engineer has not indicated an`apply-by"date on the report,
Read this Report in Full ask what it should be,and,in general,if you are the least bit uncertain
Costly problems have occurred because those relying on a geotechnical- about the continued reliability of this report,contact your geotechnical
engineering report did not read it in its entirety.Do not rely on an engineer before applying it.A minor amount of additional testing or
executive summary.Do not read selected elements only.Read this report analysis-if any is required at all-could prevent major problems.
in full.
Most of the "Findings" Related in This Report Are
You Need to Inform Your Geotechnical Engineer Professional Opinions
about Change Before construction begins,geotechnical engineers explore a site's
Your geotechnical engineer considered unique,project-specific factors subsurface through various sampling and testing procedures.
when designing the study behind this report and developing the Geotechnical engineers can observe actual subsurface conditions only at
confirmation-dependent recommendations the report conveys.A few those specific locations where sampling and testing were performed.The
typical factors include: data derived from that sampling and testing were reviewed by your
• the client's goals,objectives,budget,schedule,and geotechnical engineer,who then applied professional judgment to
risk-management preferences; form opinions about subsurface conditions throughout the site.Actual
• the general nature of the structure involved,its size, sitewide-subsurface conditions may differ-maybe significantly-from
configuration,and performance criteria; those indicated in this report.Confront that risk by retaining your
• the structure's location and orientation on the site;and geotechnical engineer to serve on the design team from project start to
• other planned or existing site improvements,such as project finish,so the individual can provide informed guidance quickly,
retaining walls,access roads,parking lots,and whenever needed.
underground utilities.

This Report's Recommendations Are perform their own studies if they want to,and be sure to allow enough
Confirmation-Dependent time to permit them to do so.Only then might you be in a position
The recommendations included in this report-including any options to give constructors the information available to you,while requiring
or alternatives-are confirmation-dependent.In other words,they are them to at least share some of the financial responsibilities stemming
not final,because the geotechnical engineer who developed them relied from unanticipated conditions.Conducting prebid and preconstruction
heavily on judgment and opinion to do so.Your geotechnical engineer conferences can also be valuable in this respect.
can finalize the recommendations only after observing actual subsurface
conditions revealed during construction.If through observation your Read Responsibility Provisions Closely
geotechnical engineer confirms that the conditions assumed to exist Some client representatives,design professionals,and constructors do
actually do exist,the recommendations can be relied upon,assuming not realize that geotechnical engineering is far less exact than other
no other changes have occurred.The geotechnical engineer who prepared engineering disciplines.That lack of understanding has nurtured
this report cannot assume responsibility or liability for confirmation- unrealistic expectations that have resulted in disappointments,delays,
dependent recommendations if you fail to retain that engineer to perform cost overruns,claims,and disputes.To confront that risk,geotechnical
construction observation. engineers commonly include explanatory provisions in their reports.
Sometimes labeled"limitations,"many of these provisions indicate
This Report Could Be Misinterpreted where geotechnical engineers'responsibilities begin and end,to help
Other design professionals'misinterpretation of geotechnical- others recognize their own responsibilities and risks.Read these
engineering reports has resulted in costly problems.Confront that risk provisions closely.Ask questions.Your geotechnical engineer should
by having your geotechnical engineer serve as a full-time member of the respond fully and frankly.
design team,to:
• confer with other design-team members, Geoenvironmental Concerns Are Not Covered
• help develop specifications, The personnel,equipment,and techniques used to perform an
• review pertinent elements of other design professionals' environmental study-e.g.,a"phase-one"or"phase-two"environmental
plans and specifications,and site assessment-differ significantly from those used to perform
• be on hand quickly whenever geotechnical-engineering a geotechnical-engineering study.For that reason,a geotechnical-
guidance is needed. engineering report does not usually relate any environmental findings,
conclusions,or recommendations;e.g.,about the likelihood of
You should also confront the risk of constructors misinterpreting this encountering underground storage tanks or regulated contaminants.
report.Do so by retaining your geotechnical engineer to participate in Unanticipated subsurface environmental problems have led to project
prebid and preconstruction conferences and to perform construction failures.If you have not yet obtained your own environmental
observation. information,ask your geotechnical consultant for risk-management
guidance.As a general rule,do not rely on an environmental report
Give Constructors a Complete Report and Guidance prepared for a different client,site,or project,or that is more than six
Some owners and design professionals mistakenly believe they can shift months old.
unanticipated-subsurface-conditions liability to constructors by limiting
the information they provide for bid preparation.To help prevent Obtain Professional Assistance to Deal with Moisture
the costly,contentious problems this practice has caused,include the Infiltration and Mold
complete geotechnical-engineering report,along with any attachments While your geotechnical engineer may have addressed groundwater,
or appendices,with your contract documents,but be certain to note water infiltration,or similar issues in this report,none of the engineer's
conspicuously that you've included the material for informational services were designed,conducted,or intended to prevent uncontrolled
purposes only.To avoid misunderstanding,you may also want to note migration of moisture-including water vapor-from the soil through
that"informational purposes"means constructors have no right to rely building slabs and walls and into the building interior,where it can
on the interpretations,opinions,conclusions,or recommendations in cause mold growth and material-performance deficiencies.Accordingly,
the report,but they may rely on the factual data relative to the specific proper implementation of the geotechnical engineer's recommendations
times,locations,and depths/elevations referenced. Be certain that will not of itself be sufficient to prevent moisture infiltration.Confront
constructors know they may learn about specific project requirements, the risk of moisture infiltration by including building-envelope or mold
including options selected from the report,only from the design specialists on the design team.Geotechnical engineers are not building-
drawings and specifications.Remind constructors that they may envelope or mold specialists.
GEOPROFESSIONAL
GetBUSINESS
ASSOCIATION
Telephone:[phone]
e-mail:[e-mail] www.geoprofessional.org
Copyright 2016 by Geoprofessional Business Association(GBA).Duplication,reproduction,or copying of this document,in whole or in part,by any means whatsoever,is strictly
prohibited,except with GBAs specific written permission.Excerpting,quoting,or otherwise extracting wording from this document is permitted only with the express written permission
of GBA,and only for purposes of scholarly research or book review.Only members of GBA may use this document or its wording as a complement to or as an element of a report of any
kind.Any other firm,individual,or other entity that so uses this document without being a GBA member could be committing negligent

r&RFROEHLING
ROBERTSON
Engineering Stability Since 1881
NC License No. F-0266
F&R Project No.: 63A-0012 28 February 2023
Mr. Michael D. Parker, PE
Hazen and Sawyer
9101 Southern Pine Boulevard,Suite 250
Charlotte, North Carolina 28273
Re: Addendum No. 1 to Report of Subsurface Exploration and Geotechnical Evaluation
Twelve Mile Creek WRF 9.0 MGD Expansion
Union County, North Carolina
Mr. Parker:
Froehling & Robertson, Inc. (F&R) is pleased to provide this Geotechnical Report Addendum No. 1 for
the above referenced project. This letter report is an addendum to our Report of Subsurface
Exploration and Geotechnical Evaluation dated 16 September 2022 (F&R Project No. 63A-0012).
As requested, we performed two additional (supplemental) soil test borings in the area of the planned
outfall. This Addendum (No. 1) letter report reviews our understanding of the project, exploration
procedures, describes general subsurface conditions for the two supplemental test borings, and
presents our conclusions with respect to construction of the outfall. Our services were performed in
general accordance with the scope of work included in the Subcontract Agreement for Professional
Services, between Hazen and Sawyer and F&R, dated 27 January 2022 and as additionally requested by
Hazen and Sawyer via an email dated 8 November 2022. At the time of this Addendum, the findings,
previous recommendations, and limitations presented in our original report are still applicable to the
project unless specifically noted otherwise.
PROJECT INFORMATION
A new effluent outfall is planned south of the facility, on the north side of Twelve Mile Creek.
Subsurface exploration of the proposed outfall area was not included in our previous study.
Project information relative to the outfall structure was provided to F&R by the project team via email
correspondence, which included the following:
• Outfall Drawings.pdf—Sheets C24, C65, C66, CD7, and CD8 dated 12 January 2023
• Plant Outfall—Structural Drawings.pdf—Sheet S680 dated December 2022
We understand the outfall end-wall will be a cast-in-place concrete structure with a footprint of about
17 feet by 16 feet. The structure has a planned bearing elevation of 484.00 feet, a bottom of key
elevation of 482.00 feet, and an outfall invert elevation of 487.15 feet. Based on the existing grades of
about 485 to 498 feet (as shown on the provided plans), excavations up to about 14 feet below existing
grade will be required to reach the planned bearing elevation of 484.00 feet.
The provided plans show that a cofferdam is proposed around the area of the outfall structure to
facilitate dewatering for construction. The cofferdam detail (on Sheet CD7) indicates that the cofferdam
will be a constructed rip-rap embankment with a polyethylene membrane on the creek side of the coffer
dam which will be held in place by stacked sandbags.
704.596.2889 3300 International Airport Drive A Minority-Owned Business
Suite 600
Charlotte, NC 28208

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SCOPE OF SERVICES
The purposes of our involvement on this project were to 1) provide general descriptions of the
subsurface soil and rock conditions in the area of the planned outfall, and 2) provide geotechnical
recommendations for construction of the outfall. In order to accomplish the above objectives, we
undertook the following scope of services:
1) Reviewed readily available geologic information relative to the project site.
2) Coordinated utility clearance with NC-811.
3) Visited the site to observe existing surface conditions and features.
4) Executed the requested supplemental subsurface exploration consisting of two (2)
additional standard penetration test (SPT) borings. The borings were advanced below
auger refusal levels using rock coring techniques to depths of 23.6 feet and 32 feet below
the existing ground surface.
5) Evaluated the findings of the subsurface exploration and prepared this geotechnical
addendum letter report summarizing our work on the project. This report provides
descriptions of the subsurface conditions encountered and discusses possible difficult
excavation and dewatering considerations.
F&R's geotechnical services did not include topographic or field surveying, development of quantity
estimates, preparation of plans and specifications, or the identification and evaluation of wetlands or
other environmental aspects of the project site.
EXPLORATION PROCEDURES
Subsurface Exploration Methods
The supplemental subsurface exploration program was performed on 2 and 5 December 2022 and
consisted of two (2) test borings (designated as 0-1 and 0-2). The test borings were performed at the
approximate locations as shown on the attached Boring Location Plan (Drawing 1). The boring locations
were marked in the field using a handheld GPS. Boring elevations were interpolated from the provided
plans. In consideration of the methods used in their determination, the test boring locations shown on
the attached Boring Location Plan and elevations shown on the attached Boring Logs should be
considered approximate.
The test borings were performed in accordance with generally accepted practice using an ATV-mounted
CME-550X rotary drill rig equipped with an automatic hammer. Hollow-stem augers were advanced to
pre-selected depths and representative soil samples were recovered with a standard split-spoon
sampler(1 3/8 in. ID, 2 in. OD) in general accordance with ASTM D 1586, the Standard Penetration Test.
Utilizing an automatic hammer, a weight of 140 pounds is freely dropped from a height of 30 inches to
drive the split-spoon sampler into the soil. The number of blows required to drive the split-spoon
sampler three consecutive 6-inch increments is recorded, and the blows of the last two increments are
summed to obtain the Standard Penetration Resistance (N-value). The N-value provides a general
indication of in-situ soil conditions and has been correlated with certain engineering properties of soils.
Rock coring was performed in each boring to explore the auger refusal materials encountered. The
borings were advanced beyond auger refusal using rock-coring techniques generally following the
procedures outlined in ASTM D 2113. The rock cores were logged by a member of our professional staff
and relative hardness, rock type, percent recovery, and rock quality designation (RQD) were measured.
The percent recovery is the ratio of the sample length obtained to the total length of the core run,
Hazen and Sawyer Addendum No.1—Twelve Mile Creek WRF 9.0 MGD Expn.
F&R Project No. 63A-0012 2 28 February 2023

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expressed as a percent. The RQD is the percentage of the length of the core recovered in segments 4 or
more inches long, compared to the total length of the core run. Care is taken during observation of the
core to see that breaks in the core length caused by drilling or handling are ignored in the RQD
determination. The percent recovery and RQD are related to rock soundness and continuity. The
percent recovery and RQD values are shown on the attached boring logs.
Subsurface water level readings were taken in each of the borings during drilling and immediately upon
completion of the soil drilling process. By the nature of the work performed, our field exploration
activities resulted in disturbances to the site. Reasonable efforts were made to lessen potential impacts
of the field exploration. Following the completion of rock coring, the borings were backfilled with auger
cuttings. Periodic observation and maintenance of the boreholes should be performed due to potential
subsidence at the ground surface, as the borehole backfill could settle over time. F&R assumes no
responsibility for borehole subsidence after demobilizing from the site and recommends that others
occasionally observe the boring locations and provide any additional infill that may be needed.
Representative portions of the split-spoon soil samples obtained throughout the exploration program
were sealed in air-tight containers and transported to our laboratory. The collected samples were
evaluated by a member of our professional staff in general accordance with techniques outlined in the
visual-manual identification procedure (ASTM D 2488) and the Unified Soil Classification System. The
soil descriptions and classifications discussed in this report and shown on the attached Boring Logs are
generally based on visual observation and should be considered approximate. Copies of the boring logs
are provided and classification procedures are further explained in the attached appendix.
Split-spoon soil samples recovered on this project will be stored at F&R's office for a period of sixty days.
After sixty days,the samples will be discarded unless prior notification is provided to us in writing.
SUBSURFACE CONDITIONS
The subsurface conditions discussed in the following paragraphs, and those shown on the attached
Boring Logs, represent an estimate of the subsurface conditions based on interpretation of the boring
data using normally accepted geotechnical engineering judgments. The strata breaks designated on the
Boring Logs represent approximate boundaries between soil types. Actual transitions between soil
strata are generally less distinct than the immediate transitions depicted on the Boring Logs. Although
individual soil test borings are representative of the subsurface conditions encountered at the boring
locations on the dates shown, they are not necessarily indicative of subsurface conditions at other
locations or at other times.
Below the existing ground surface, the supplemental borings generally encountered existing surficial
soils underlain by residual soils, partially weathered rock, auger refusal and rock. These materials are
discussed further below:
Surficial Materials
Surficial soils were encountered in each of the borings to depths of approximately 3 to 6 inches.
Surficial soils are typically a dark-colored soil material containing roots, fibrous matter, and/or other
organic components, and are generally unsuitable for engineering purposes. We note that no
laboratory testing has been performed to determine the organic content or horticultural properties of
the observed surficial soil materials. Therefore, the term "surficial soils" is not intended to indicate
suitability for landscaping and/or other purposes. The surficial soil depths provided in this report are
based on driller observations and should be considered approximate. The transition from surficial soils
to underlying materials may be gradual and therefore the observation and measurement of surficial soil
depths is subjective. Actual surficial soils depths should be expected to vary across the site.
Hazen and Sawyer Addendum No.1—Twelve Mile Creek WRF 9.0 MGD Expn.
F&R Project No. 63A-0012 3 28 February 2023

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Residual Soils
Residual soils, formed by the in-place weathering of the parent rock, were encountered in each of the
test borings below the pavement base stone. The sampled residual soils were generally described as
sandy and clayey silt (ML) and silty clay (CL). Standard penetration resistances in the sampled residuum
ranged from 5 to 46 blows per foot(bpf).
Partially Weathered Rock
Partially weathered rock (PWR) is a transitional material between soil and rock, which retains the relic
structure of the rock and has very hard or very dense consistencies. PWR was encountered at a depth of
17 feet below existing grade in boring 0-2. A possible layer of PWR was also inferred in boring 0-1 at a
depth of 12 feet based on hard drilling at that level; however, the possible PWR was not sampled.
Sampled partially weathered rock was described as silty sand (SM) with penetration resistances of 50
blows per 5 inches (50/5) of split-spoon penetration.
Auger Refusal and Rock
Auger refusal occurs when materials are encountered that cannot be penetrated by the soil auger and is
normally indicative of a very hard or very dense material, such as boulders, rock lenses, pinnacles,
impenetrable debris within fill, or the upper surface of bedrock. Auger refusal materials were
encountered at in borings 0-1 and 0-2 at depths of 14 feet and 23.5 feet below existing grade,
respectively(approximate elevations of 484 and 477 feet, respectively).
Rock coring was performed in each boring to advance the borings beyond encountered auger refusals.
Rock recovered during the coring operations was generally described as greenish gray slate and phyllite.
Specific descriptions of recovered rock are provided on the respective boring logs as well as an
accompanying Rock Core Summary and Photograph Log. The Percent Recovery and Rock Quality
Designation (RQD) of the rock core samples ranged from 37 to 97% and 0 to 7%, respectively.
Groundwater Data
Groundwater was encountered at depths of 14.1 feet and 10.7 feet during drilling in borings 0-1 and
0-2, respectively. It should be noted that groundwater levels fluctuate depending upon seasonal factors
such as precipitation and temperature.
RECOMMENDATIONS AND CONCLUSIONS
General
The following findings and conclusions are based on our observations at the site, interpretation of the
field and laboratory data obtained during this exploration, and our experience with similar subsurface
conditions and projects. Soil penetration and rock core data has been used to develop foundation
support recommendations for the outfall end-wall structure and evaluate potential excavation
conditions based on previous experience and resulting empirical correlations. Subsurface conditions in
unexplored locations may vary from those encountered.
The subsurface exploration aids the geotechnical engineer in determining the soil stratum appropriate
for structural support. This determination includes considerations with regard to both allowable bearing
capacity and compressibility of the soil and rock strata. In addition, since the method of construction
greatly affects the soils intended for structural support, consideration must be given to the
implementation of suitable methods of site preparation, fill compaction, and other aspects of
construction.
Hazen and Sawyer Addendum No.1—Twelve Mile Creek WRF 9.0 MGD Expn.
F&R Project No. 63A-0012 4 28 February 2023

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Foundation Recommendations
As previously stated,we understand the outfall end-wall will be a cast-in-place concrete structure with a
footprint of about 17 feet by 16 feet. The structure has a planned bearing elevation of 484.00 feet and a
bottom of key elevation of 482.00 feet. Based on the existing grades of about 485 to 498 feet shown on
the provided plans, excavations up to about 14 feet below existing grade will be required to reach the
planned bearing elevation of 484.00 feet.
Borings 0-1 and 0-2 were performed at distances of about 40 feet and 25 feet from the proposed outfall
structure, respectively. The subsurface conditions encountered at the foundation bearing elevation of
484.00 feet varied between borings 0-1 and 0-2. Based on the conditions encountered in boring 0-2,
we recommend an allowable design bearing pressure of 3,000 pounds per square foot (psf) for the
outfall end-wall structure. Based in the available project information and the subsurface soils
encountered in boring 0-2, an allowable bearing pressure of up to 3,000 psf should yield less than 1/2
inch of total settlement for the outfall structure.
Rock was encountered in boring 0-1 at a depth of 14 feet below existing grade (approximate elevation
of 484 feet). Therefore, rock may be present at or above the foundation bearing elevation. The
structure may bear on rock; however, should rock and soil be present at the foundation bearing
elevation, some over-excavation of the rock may be required to mitigate potential issues with
differential settlement and uneven pressures. If soil is also present, we generally recommend that rock
is over-excavated to a depth of at least 12 inches below foundation bearing and backfilled with
compacted structural fill.
All foundation subgrades should be observed, evaluated, and verified for the design bearing pressure by
a representative of the geotechnical engineer after excavation and prior to reinforcement steel
placement. Depending on the results of the above recommended foundation subgrade verification,
some undercutting, in-place densification, and/or subgrade materials replacement may be required.
The actual need for, and extent of, undercutting or in-place stabilization or subgrade materials
replacement should be based on field observations made by a representative of the geotechnical
engineer at the time of construction.
Excavations for footings should be made in such a way as to provide bearing surfaces that are firm and
free of loose, soft, wet, or otherwise disturbed soils. Foundation concrete should not be placed on
frozen or saturated subgrades. If such materials are allowed to remain below foundations, settlements
will increase. Foundation excavations should be concreted as soon as practical after they are excavated.
If an excavation is left open for an extended period, a thin mat of lean concrete should be placed over
the bottom to minimize damage to the bearing surface from weather or construction activities. Water
should not be allowed to pond in any excavation.
Lateral Earth Pressures
See Section 4.5 in the Report of Subsurface Exploration and Geotechnical Engineering Services prepared
by F&R dated 16 September 2022 provides general commentary and recommendations on Lateral Earth
Pressures; however, the following paragraphs and table provide some structure-specific
recommendations for the outfall structure.
Based on the subsurface exploration, available on-site backfill materials for outfall end-wall will
predominately consist of silty clay (CL), sandy silt (ML) and clayey silt (ML). If encountered during
construction or if an off-site source for materials is required, we do not recommend the use of highly-
plastic clays and silts (CH and MH) behind below grade walls.
The following table provides lateral earth pressure parameters for a mixture of the onsite silty clay (CL),
sandy silt (ML) and clayey silt (ML) soils.
Hazen and Sawyer Addendum No.1—Twelve Mile Creek WRF 9.0 MGD Expn.
F&R Project No. 63A-0012 5 28 February 2023

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ON-SITE SOILS MIXTURE (CL/ML)
Earth Pressure Conditions Coefficient Recommended Equivalent Fluid
Pressure (pcf)
Active (Ka) 0.39 47
At-Rest(K.) 0.56 _ 67
Passive (Kr) 2.77 ---
*A compacted moist soil unit weight of 120 pounds per cubic foot should be used for design calculations.
Excavation Conditions
The structure has a planned bearing elevation of 484.00 feet and a bottom of key elevation of 482.00
feet. Rock was encountered in boring 0-1 at a depth of 14 feet below existing grade (approximate
elevation of 484 feet). Therefore, rock may be present in excavations for the outfall end-wall structure,
particularly the key that extends to elevation 482.00 feet.
See Section 5.7 in the Report of Subsurface Exploration and Geotechnical Engineering Services prepared
by F&R dated 16 September 2022 for further details on Excavation Characteristics.
Groundwater Conditions
Groundwater was encountered in borings 0-1 and 0-2 at depths of 14.1 feet and 10.7 feet, respectively
(approximate elevations of 484 and 483 feet, respectively). We envision that the levels that
groundwater was encountered at during this study will lower following the installation of the planned
cofferdam and water has been pumped out of the work area inside of the dam. However, some water/
groundwater and wet soils should be anticipated.
Groundwater levels fluctuate depending upon seasonal factors such as precipitation and temperature.
Additionally, groundwater measurements made in predominantly cohesive and fine-grained soils are not
necessarily indicative of the actual static subsurface water level due to the low permeability of such
soils. As such, soil moisture and groundwater conditions at other times may vary or be different from
those described in this report.
LIMITATIONS
This letter report has been prepared for the exclusive use of Hazen and Sawyer for the specific
application to the proposed Twelve Mile Creek WRF 9.0 MGD Expansion project located in Union
County, North Carolina, in accordance with generally accepted geotechnical engineering practices. No
other warranty, express or implied, is made. Our recommendations are based on design information
furnished to us at the time the work was performed; the data obtained from the previously described
subsurface exploration program, and generally accepted geotechnical engineering practice. The findings
and recommendations do not reflect variations in subsurface conditions, which could exist in
unexplored areas of the site. In areas where variations from the available subsurface data become
apparent during construction, it will be necessary to re-evaluate our recommendations based upon on-
site observations of the conditions.
Regardless of the thoroughness of a subsurface exploration, there is the possibility that conditions in
other areas will differ from those at the boring locations, that conditions are not as anticipated by the
designers, or that the construction process has altered the soil conditions. Therefore, our experienced
geotechnical engineers should evaluate foundation construction to verify that the conditions anticipated
in design actually exist. Otherwise, we assume no responsibility for construction compliance with the
design concepts, specifications, or recommendations. In the event that changes are made in the design
or location of the proposed structures, the recommendations presented in this report shall not be
Hazen and Sawyer Addendum No.1—Twelve Mile Creek WRF 9.0 MGD Expn.
F&R Project No. 63A-0012 6 28 February 2023

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considered valid unless the changes are reviewed by our firm and recommendations of this report
modified or verified in writing. If this report is copied or transmitted to a third party, it must be copied
or transmitted in its entirety, including text, attachments, and enclosures. Interpretations based on only
a part of this report may not be valid.
CLOSURE
We appreciate the opportunity to provide continued services for this project. Please contact us if you
have any questions regarding this report addendum.
Sincerely,
FROEHLING&ROBERTSON, INC. ,,,,,,,,
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AlexanderT. Kuczero, P.E. ,''',,,,,,,`,,, ndrew R Frank, P.E.
Geotechnical Engineer Regional Senior Geotechnical Engineer
Email Distribution: [e-mail]; [e-mail];
Attachments: Boring Location Plan (Drawing No. 1)
Key to Boring Log Soil Classification
Key to Boring Log Rock Classification
Soil Classification Chart
Boring Logs (0-1 and 0-2)
Rock Core Summary and Photograph (0-1 and 0-2)
F:\Projects 63A\63A-0012(Hazen and Sawyer-12-Mile Creek WRF 9.0 MGD Expansion)\Report\63A-0012(Hazen and Sawyer-12-Mile Creek WRF 9.0 MGD Expansion)Geo Report.Addendum No.1.DOC
Hazen and Sawyer Addendum No.1—Twelve Mile Creek WRF 9.0 MGD Expn.
F&R Project No. 63A-0012 7 28 February 2023

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Soil Test Boring Locations
0' 20' 40'
DATE: February 2023
Cp FROEHLING -,. ROBERTSON
I p�R Engineering Stability Since 1881 SCALE: As Shown
DRAWN: ATK 63A-0012
Hazen and Sawyer DRAWING NO.
12-Mile Creek WRF Expansion BORING LOCATION PLAN
Waxhaw, North Carolina 1
1

r&R
KEY TO BORING LOG SOIL CLASSIFICATION
Particle Size and Proportion
Visual descriptions are assigned to each soil sample or stratum based on estimates of the
particle size of each component of the soil and the percentage of each component of the soil.
Particle Size Proportion
Descriptive Terms Descriptive Terms
Soil Component Particle Size Component Term Percentage
Boulder > 12 inch Major Uppercase Letters > 50%
Cobble 3 - 12 inch (e.g., SAND, CLAY)
Gravel-Coarse 3/4 -3 inch
-Fine #4 -3/4 inch Secondary Adjective 20% - 50%
Sand-Coarse #10 -#4 (e.g., sandy, clayey)
-Medium #40 -#10
-Fine #200 -#40 Minor Some 15% -25%
Silt(non-cohesive) <#200 Little 5% - 15%
Clay(cohesive) <#200 Trace 0% -5%
Notes:
1. Particle size is designated by U.S. Standard Sieve Sizes
2. Because of the small size of the split-spoon sampler relative to the size of gravel,the true percentage of gravel
may not be accurately estimated.
Density or Consistency
The standard penetration resistance values (N-values) are used to describe the density of
coarse-grained soils (GRAVEL, SAND) or the consistency of fine-grained soils (SILT, CLAY).
Sandy silts of very low plasticity may be assigned a density instead of a consistency.
DENSITY I CONSISTENCY
Term N-Value Term N-Value
Very Loose 0-4 Very Soft 0- 1
Loose 5 - 10 Soft 2 -4
Medium Dense 11 -30 Firm 5 - 8
Dense 31 -50 Stiff 9 - 15
Very Dense >50 Very Stiff 16-30
Hard >30
Notes:
1. The N-value is the number of blows of a 140 lb.Hammer freely falling 30 inches required to drive a standard
split-spoon sampler(2.0 in. O.D., 1-3/8 in. I.D.) 12 inches into the soil after properly seating the sampler 6
inches.
2. When encountered,gravel may increase the N-value of the standard penetration test and may not accurately
represent the in-situ density or consistency of the soil sampled.
F:\Branch 62\GEOWORD\REPORTS\keyblsc.enc.doc

SOIL CLASSIFICATION CHART
MAJOR DIVISIONS SYMBOLS TYPICAL
GRAPH LETTER DESCRIPTIONS
•w-w .w go
CLEAN .6. iv WELL-GRADED GRAVELS,OR
-
GRAVEL GRAVELS P. aft• ./ GW SAND MIXTURES,LITTLE R NO
AND ••s ,.s FINES
+�- •+�
GRAVELLY .'. ..'. POORLY-GRADED GRAVELS,
SOILS (LITTLE OR NO FINES) lie b•• ./ Gp GRAVEL-SAND MIXTURES,LITTLE
00 111 •0 111 OR NO FINES
COARSE
•+1i • in
GRAINED GRAVELS WITH •1 4 e/ GM SILTY GRAVELS, GRAVEL-SAND-
SOILS MORE THAN 50% FINES SILT MIXTURES
OF COARSE •*411 • 411
FRACTION •
RETAINED ON NO. 'Or
4 SIEVE (APPRECIABLE GC
r+ CLAYEY GRAVELS,GRAVEL-SAND-
AMOUNT OF FINES) ` � CLAY MIXTURES
v
WELL-GRADED SANDS,GRAVELLY
CLEAN SANDS
MORE THAN 50% SAND SW SANDS, LITTLE OR NO FINES
OF MATERIAL IS AND
eeeeee
LARGER THAN SANDY NO.200 SIEVE SOILS POORLY-GRADED SANDS,
SIZE (LITTLE OR NO FINES) Sp GRAVELLY SAND,LITTLE OR NO
FINES
SANDS WITH - - SM
SANDS,SAND-SILT
MORE THAN 50% FINES _ M MIXTURES
OF COARSE —
FRACTION
PASSING ON NO.
4 SIEVE (APPRECIABLE SC MIXTURES
CLAYEY
ANDS,SAND-CLAY
AMOUNT OF FINES) —
INORGANIC SILTS AND VERY FINE
ML SANDS, ROCK FLOUR,SILTY OR
CLAYEY FINE SANDS OR CLAYEY
SILTS WITH SLIGHT PLASTICITY
SILTS r INORGANIC CLAYS OF LOW TO
FINE AND LIQUID LIMIT MEDIUM PLASTICITY,GRAVELLY
GRAINED CLAYS LESS THAN 50 / CL CLAYS,SANDY CLAYS,SILTY
SOILS _ _ _ _ CLAYS,LEAN CLAYS
OL ORGANIC SILTS AND ORGANIC
SILTY CLAYS OF LOW PLASTICITY
MORE THAN 50% INORGANIC SILTS, MICACEOUS OR
OF MATERIAL IS MH DIATOMACEOUS FINE SAND OR
SMALLER THAN SILTY SOILS
NO.200 SIEVE
SIZE SILTS
AND 1)7
LIQUID LIMIT INORGANIC CLAYS OF HIGH
CLAYS GREATER THAN 50 / CH PLASTICITY
^^^^^^^^^ OH ORGANIC CLAYS OF MEDIUM TO
HIGH PLASTICITY,ORGANIC SILTS
0 I, 0 I, \0 I,
0,, 0,, 0,, ' PEAT,HUMUS,SWAMP SOILS WITH
HIGHLY ORGANIC SOILS PT HIGH ORGANIC CONTENTS
NOTE: DUAL SYMBOLS ARE USED TO INDICATE BORDERLINE SOIL CLASSIFICATIONS

SINCE
F&R
,NN,
KEY TO BORING LOG ROCK CLASSIFICATION (PAGE 1 OF 2)
Classification of rock is based on the following characteristics: Weathering, Discontinuities, Color and
Grain Size, Hardness,Voids, Geologic Lithology, and Rock Quality Designation (RQD).
WEATHERING
TERM SYMBOL DESCRIPTION
Fresh F No visible sign of decomposition or discoloration. Crystals are bright
Slightly Weathered WS Slight discoloration inward from open fractures.
Moderately Weathered WM Discoloration throughout. Weaker minerals decomposed. Strength
somewhat less than fresh rock, but cores cannot be broken by hand or
scraped by knife. Texture preserved. Joints may contain clay.
Highly Weathered WH Most minerals somewhat decomposed. Specimens can be broken by hand
with effort or shaved with knife. Core stones present in rock mass. Texture
becoming indistinct but fabric preserved.
Completely Weathered WC Minerals decomposed to soil but fabric and structure preserved (saprolite).
Specimens easily crumbled or penetrated.
Residual Soil RS Advanced state of decomposition resulting in plastic soils. Rock fabric and
structure completely destroyed.
DISCONTINUITIES
SPACING * BANDING, BEDDING, FOLIATION FAULTS,JOINTS,and other
FRACTURES
Greater than 6.0 feet Very Thick Very Wide _
2.0—6.0 feet Thick Wide
8-24 inches Medium Medium
2.5—8 inches Thin Close
3 to 2.5 inches Very Thin Very Close
SPACING* LAMINATION, FOLIATION,or FAULTS,JOINTS,and other
CLEAVAGE FRACTURES
-3 inch Intense
Less than%inch Very Intense Extremely Close
*—Spacing is the perpendicular distance between discontinuities.
TYPE of DISCONTINUITY ATTITUDE (DIP)
TERM CONDITION TERM EXISTING
ANGLE
0-5
A fracture along which no movement has Horizontal
Joint occurred.
Low Angle 5-35
Bedding A natural plane dividing sedimentary rock layers Moderate Angle 35-55
Plane
Shear Plane A fracture along which some movement has High Angle 55-85
occurred.
Fault A zone of fractured rock containing one or more Vertical 95-90
shear plane and areas of gouge

SINCE
F&R
KEY TO BORING LOG ROCK CLASSIFICATION (PAGE 2 OF 2)
ROCK GRAIN SIZE
IGNEOUS AND METAMORPHIC ROCKS SEDIMENTARY ROCKS
Coarse Grained Diameter>5 mm (3/16 in) Coarse Grained Diameter>2 mm (1/16 in)
Medium Grained 1 mm (1/32 in)-5 mm (3/16 in) Medium Grained 0.06 mm-2 mm (1/16 in)
Fine Grained < 1 mm (1/32 in) Fine Grained 0.002 mm—0.06 mm
Glassy Grains not visible with unaided eye. Very Fine Grained Grains not visible with unaided eye.
VOIDS
TERM SIZE OF VOID
Pit <6 mm(1/4 inch)
Vug 6 mm—50 mm(2 inches)
Cavity 50 m—0.6 m (2 feet)
Cave >0.6 m
ROCK HARDNESS
CLASS HARDNESS FIELD TEST
II Extremely Hard Many blows with a geologic hammer required to break intact specimen.
II Very Hard Hand-held specimen breaks with hammer end of pick under more than one
blow.
III Hard Cannot be scraped or peeled with knife, hand-held specimen can be broken
with single moderate blow with pick.
IV Soft Can just be scraped or peeled with knife.
V Very Soft Material crumbles under moderate blow with sharp end of pick and can be
peeled with a knife.
ROCK QUALITY DESIGNATION ** (RQD)
ROCK QUALITY DESIGNATION **,% ROCK MASS DESCRIPTION
90-100 Excellent
75-90 Good
50-75 Fair
25-50 Poor
<25 Very Poor
** - RQD is the ratio of the cumulative length of all pieces of rock greater than or equal to four inches to
the total length drilled, expressed as a percentage

BORING LOG
r8,RFROEHLING ROBERTSON Boring: 0-1 (1 of 1)
Project No:63A-0012 Elevation:498± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth: 23.6' Hammer Type:Automatic
Project: 12-Mile Creek WRF Outfall Boring Location:See Boring Location Plan Date Drilled: 12/5/22
City/State:Waxhaw, NC Driller: HPC:J. Cain
Description of Materials *Sample Sample N-Value
Elevation Depth Depth Remarks
(Classification) Blows (feet (blows/ft)
497.8 - 0.3 _.'''1\SURFICIAL SOIL:3 inches ` 1-4-9 0• Groundwater was
- RESIDUUM:Stiff to very stiff, brown, clayey 13 encountered at 14.1 feet
- SILT(ML)with trace organics, moist 2.5 during drilling.
2.0
_ 10-12-9
- 21
494.5 - 3.5 454 3.5
- Stiff,tan,fine to medium sandy SILT(ML), moist
- 9
— 5.0
492.0 6.0 J' Firm, brown and gray, silty CLAY(CL), moist 2-2-3 6.0
5
7.5
1-2-3 8.5
5
10.0
486.0 - 12.0 1
`� PARTIALLY WEATHERED ROCK: Not Sampled Hard drilling 12 to 14 feet
�
484.0 - �14.0 REC=37% 14.0 Auger refusal at 14 feet.
ROCK: Highly weathered to fresh, closely g
fractured (high angle), hard to very hard,fine RQD=0% Rock coring started at 14
-j grained,greenish gray,SLATE feet.
--,j
J.% 18.6
REC=97%
-;/ RQD=23%
i,%
474.4 - 23.6 23.6
Coring Terminated at 23.6 feet
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6"increments.
The sum of the second and third increments of penetration is termed the standard penetration resistance,N-Value.

Rock Core Summary and Photograph
Boring 0-1: 14.0 to 18.6' — Rec = 37%, RQD = 0%
18.6 to 23.6' — Rec = 97%, RQD = 23%
• . , 14.0' '1`'
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go
111,11 rli . .:____
0
18.6' w
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u� _`__ N G
DATE: February 2023
r,R FROEHLING t-. ROBERTSONSCALE: As Shown
Engineering Stability Since 1881
DRAWN: DJM 63A-0012
Hazen and Sawyer BORING NO.
12-Mile Creek WRF Expansion ROCK CORE SUMMARY
Waxhaw, North Carolina AND PHOTOGRAPH 0-1

BORING LOG
r8,RFROEHLING ROBERTSON Boring: 0-2 (1 of 1)
Project No:63A-0012 Elevation:494± Drilling Method: HSA
Client: Hazen and Sawyer Total Depth:32.0' Hammer Type:Automatic
Project: 12-Mile Creek WRF Outfall Boring Location:See Boring Location Plan Date Drilled: 12/2/22
City/State:Waxhaw, NC Driller: HPC:J. Cain
Description of Materials *Sample Sample N-Value
Elevation Depth Depth Remarks
(Classification) Blows (feet) (blows/ft)
493.5 - 0.5 '-' \SURFICIAL SOIL:6 Inches r 2-9-2 0• Groundwater was
- RESIDUUM:Stiff, brown red,fine to medium 11 encountered at 10.7 feet
sandy SILT(ML)with trace organics and rock 1.5 during drilling
- fragments, moist 4-4-5 2.0
- 9
490.5 - 3.5 6 10 14 3.5
- Very stiff, brown and tan,fine to medium sandy
- SILT(ML), moist 24
- 5.0
-
9-10-16 6.0
- 26
- 7.5
486.0 - 8.0 -
- Hard,tan,fine to medium sandy SILT(ML), 8.5
- moist 16-23-23
- 46
- 10.0
SZ -
482.0 - 12.0 I -
- Stiff, red brown,fine to medium sandy SILT(ML) 12.7
- with some rock fragments, moist 27-8-6
14
14.2
477.0 - 17.0 PARTIALLY WEATHERED ROCK:Sampled as very
dense, brown gray, silty fine to coarse SAND
(SM), moist 50/5 18.5
20.0 100+
470.5 23.5 ! 23.5 Auger refusal at 23.5 feet.
ROCK: Moderately weathered to fresh, closely REC=96% Au g
fractured (high angle), hard,fine grained, RQD=36% Rock coring started at
greenish gray and white,SLATE 23.5 feet.
_ .
REC=94% 28.0
465.0 - 29.0 _ RQD=0%
2, Lightly weathered to fresh, closely fractured
(high angle), hard to very hard,fine grained,
greenish gray and white, PHYLLITE
462.0 - 32.0 - '' 32.0
Coring Terminated at 32.0 feet
*Number of blows required for a 140 lb hammer dropping 30"to drive 2"O.D.,1.375"I.D.sampler a total of 18 inches in three 6"increments.
The sum of the second and third increments of penetration is termed the standard penetration resistance,N-Value.

Rock Core Summary and Photograph
Boring 0-2: 23.5 to 28.0' — Rec = 96%, RQD = 36%
28.0 to 32.0' — Rec = 94%, RQD = 0%
J '
,F- _ i _ F: 23.5' a
S,, N
a
w'1 in
1 it " a
9 } • p-
L 1 m
f ,fir• -
li1 r 4 ''
I w
It
�� elI . 28.0' t`
to
Y I . / i$ is r l7 w G
c —
p I 1 is -
:i � \
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i•
l �' 1, f ', - - in -.
., J
il
in sji
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y' f x '
Al I? s 1 ci
Q J--
i. �, rY" it ) .••• r
0 . e t 4
1C32.0' fN2u=
1 , - 1 .,,, '4 1 . ' ,li.. -iii %I.:: •-
DATE: February 2023
r&R FROEHLING t-. ROBERTSONSCALE: As Shown
Engineering Stability Since 1881
DRAWN: DJM 63A-0012
Hazen and Sawyer BORING NO.
12-Mile Creek WRF Expansion ROCK CORE SUMMARY
Waxhaw, North Carolina AND PHOTOGRAPH 0-2