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ECS Southeast, LLP
Geotechnical Engineering Report
Project Wheel
Salisbury, Rowan County, North Carolina
ECS Project Number 08:4796‐A
January 12, 2018
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ECS Project No. 08:4796‐A Page 1
TABLE OF CONTENTS
EXECUTIVE SUMMARY ............................................................................................................... 3
1.0 INTRODUCTION .................................................................................................................... 4
1.1 General ................................................................................................................................... 4
1.2 Scope of Services .................................................................................................................... 4
2.0 PROJECT INFORMATION ....................................................................................................... 5
2.1 Project Location...................................................................................................................... 5
2.2 current/Past Site History/Uses ............................................................................................... 5
2.3 Proposed Construction ........................................................................................................... 5
2.3.1 Structural Information/Loads ....................................................................................... 6
3.0 FIELD EXPLORATION ............................................................................................................. 7
3.1 Field Exploration Program ...................................................................................................... 7
3.1.1 Test Borings .................................................................................................................. 7
3.2 Regional/Site Geology ............................................................................................................ 7
3.3 Subsurface Characterization .................................................................................................. 8
3.4 Groundwater Observations .................................................................................................... 8
4.0 LABORATORY SERVICES ........................................................................................................ 9
4.1 Laboratory Testing ................................................................................................................. 9
5.0 DESIGN RECOMMENDATIONS ............................................................................................ 10
5.1 Building Design ..................................................................................................................... 10
5.1.1 Foundations ................................................................................................................ 10
5.1.2 Floor Slabs ................................................................................................................... 10
5.1.3 Seismic Design Considerations ................................................................................... 11
5.1.4 Site Retaining Walls .................................................................................................... 12
5.1.4.1 Lateral Earth Pressures ............................................................................................ 12
5.1.4.2 Below Grade Basement Retaining Walls ................................................................. 13
5.2 Site Design Considerations ................................................................................................... 14
5.2.1 Cut and Fill Slopes ....................................................................................................... 14
5.2.2 Pavement Considerations ........................................................................................... 14
6.0 SITE CONSTRUCTION RECOMMENDATIONS ........................................................................ 17
6.1 Subgrade Preparation .......................................................................................................... 17
6.1.1 Stripping ...................................................................................................................... 17
6.1.2 Proofrolling ................................................................................................................. 17
6.1.3 Subgrade Stabilization ................................................................................................ 17
6.2 Earthwork Operations .......................................................................................................... 17
6.2.1 High Plasticity Soils ..................................................................................................... 17
6.2.2 Existing Man‐Placed Fill .............................................................................................. 18
6.2.3 Below Grade Excavation ............................................................................................. 19
6.2.4 Structural Fill Materials............................................................................................... 19
6.2.5 Compaction ................................................................................................................. 20
6.3 Foundation and Slab Observations ...................................................................................... 21
6.4 Utility Installations ............................................................................................................... 22
6.5 General Construction Considerations .................................................................................. 22
7.0 CLOSING ............................................................................................................................. 24
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APPENDICES
Appendix A – Drawings & Reports
Site Location Diagram
Boring Location Diagram
Appendix B – Field Operations
Reference Notes for Boring Logs
Boring Logs
Appendix C – Laboratory Testing
Laboratory Summary
Appendix D – SHWT Report
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EXECUTIVE SUMMARY
This report contains the results of our subsurface exploration and geotechnical engineering
evaluation for the proposed structure to be located in Salisbury, Rowan County, North Carolina.
ECS has assumed that the maximum column loads will not exceed 200 kips per column, and
continuous wall loads will not exceed 4 kips per linear foot for individual structures. Construction
is expected to include an industrial building with a footprint of approximately 100,000 SF, with a
50,000 SF Phase 2 expansion area to the east, associated truck court and parking/drive areas, and
a stormwater pond to the south of the proposed building.
Moisture sensitive soils were encountered at several boring locations at depths ranging from 3 to
8 feet below the existing ground surface. Based on the assumed cut and fill depths we anticipate
that MH/CH soils will be present at finished grades in isolated areas and will require limited
remediation.
Our findings indicate that the proposed structure can be supported on conventional shallow
foundations bearing on low plasticity residual soils or new engineered fill. Provided that the site
and subgrades are properly prepared, shallow foundations may be proportioned for a net
allowable design bearing pressure of 2,000 psf. Concrete slabs‐on‐grade supported by approved
residual soils or properly prepared engineered fills can be designed using a modulus of subgrade
reaction of 90 pounds per cubic inch (pci). A Seismic Site Class “D” is recommended for the site.
Specific information regarding the subsurface exploration procedures, the site and subsurface
conditions at the time of our exploration, and our conclusions and recommendations concerning
the geotechnical design and construction aspects of the project are discussed in detail in the
subsequent sections of this report. Please note this Executive Summary is an important part of
this report but should be considered a “summary” only. The subsequent sections of this report
constitute our findings, conclusions, and recommendations in their entirety. Furthermore, ECS
should review our findings and recommendations in their entirety once the final project criteria
have been established.
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1.0 INTRODUCTION
1.1 GENERAL
The purpose of this study was to provide general subsurface conditions at the site and to evaluate
those conditions with regard to foundation and floor slab support, along with general site
development. The project will include the construction of a new industrial building with a
footprint of approximately 100,000 square feet (SF) with a 50,000 SF Phase 2 expansion area to
the east, associated truck court and parking/drive areas, and a stormwater pond to the south of
the proposed building.
The recommendations developed for this report are based on the provided project information.
This report contains the results of our subsurface explorations, site characterization, engineering
analyses, and recommendations for the design and construction of the proposed structures.
ECS previously performed borings at the site as part of the initial feasibility study. The findings
were presented in our ‘Report of Subsurface Exploration’ (ECS Project No. 08‐4796) dated August
31, 2007.
1.2 SCOPE OF SERVICES
To obtain the necessary geotechnical information required for design of the proposed industrial
building, eleven (11) additional soil test borings were performed at locations selected by ECS. This
report discusses our exploratory and testing procedures, presents our findings and evaluations
and includes the following.
Information on site conditions including geologic information and special site features.
Description of the field exploration and laboratory tests performed.
Final logs of the soil borings and records of the field exploration and laboratory tests in
accordance with the standard practice of geotechnical engineers, including a boring location
diagram and vicinity map.
Measurement of the surficial materials at each boring location and notation of this
information on the boring logs and in the text of the report.
Seismic site classification using the average N‐method.
Recommendations regarding foundation options for the structure and settlement potential.
Settlement potential is provided based on assumed loading and structure details from the
project information obtained at the time of the analysis.
Recommendations regarding slab‐on‐grade construction and design.
Recommended light and heavy duty pavement sections.
Lateral earth pressure coefficients for below grade loading dock walls.
Depth of groundwater and seasonal high water table (SHWT).
Evaluation of the on‐site soil characteristics encountered in the soil borings.
Recommendations for minimum soil cover during frost heaving, compaction requirements for
fill and backfill areas, and slab‐on‐grade construction.
Recommendations regarding site preparation and construction observations and testing.
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2.0 PROJECT INFORMATION
2.1 PROJECT LOCATION
The project site is located along Summit Park Drive, southwest of its intersection with Julian Road
in Salisbury, Rowan County, North Carolina, as shown in the Site Vicinity Map (Figure 2.1.1) below,
and included in the Appendix.
Figure 2.1.1 Site Location
2.2 CURRENT/PAST SITE HISTORY/USES
Based on our review of available aerial photography from Google Earth, the site appears to have
been moderately to heavily wooded since 1993. The southern portion of the site appears to have
been disturbed between 1995 and 1998 when Summit Park Drive was developed. Based on our
review of the provided site plan, the site has a high elevation of approximately 786 feet at the
south eastern portion of the site and a low elevation of approximately 756 feet at the north
western portion of the site.
2.3 PROPOSED CONSTRUCTION
We understand that plans are to develop the site with a new industrial building with associated
truck court and parking/drive areas. Construction is expected to include a commercial/industrial
building with an approximately 100,000 SF footprint with an approximate 50,000 SF expansion
area to the east, associated parking and drive lanes, and a stormwater pond. The anticipated
finished floor elevation is 775 feet, therefore cut/fill depths are likely on the order of 5 to 10 feet.
No additional information has been provided to us at this time.
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2.3.1 Structural Information/Loads
The following information explains our understanding of the structure and their loads:
Table 2.3.1.1 Design Values
SUBJECT DESIGN INFORMATION / EXPECTATIONS
Building Footprint 100,000 SF
Usage Industrial/Single‐Story
Framing Steel Framed with Tilt‐Panels.
Column Loads 200 kips (estimated)
Wall Loads 4 kips per linear foot (klf) maximum (estimated)
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3.0 FIELD EXPLORATION
3.1 FIELD EXPLORATION PROGRAM
The field exploration was planned with the objective of characterizing the project site in general
geotechnical and geological terms and to evaluate subsequent field data to assist in the
determination of geotechnical recommendations.
3.1.1 Test Borings
2007 Borings
The subsurface conditions were explored by seventeen (17) soil test borings. A B‐57 drill rig was
utilized to drill the soil test borings. Borings were generally advanced to depths ranging from
approximately 10 to 25 feet below the current ground surface.
2018 Borings
The subsurface conditions were explored by drilling eleven (11) additional soil test borings. A
CME‐55 drill rig was utilized to drill the soil test borings. Borings were generally advanced to
depths ranging from approximately 15 to 30 feet below the current ground surface.
Boring locations were identified in the field by ECS personnel using handheld GPS techniques and
existing landmarks as reference prior to mobilization of our drilling equipment. The approximate
as‐drilled boring locations are shown on the Boring Location Diagram in Appendix A. Ground
surface elevations noted on our boring logs were estimated from the provided site plan and
should be considered accurate only to the degree implied by the method used to obtain them.
Standard penetration tests (SPTs) were conducted in the borings at regular intervals in general
accordance with ASTM D 1586. Small representative samples were obtained during these tests
and were used to classify the soils encountered. The standard penetration resistances obtained
provide a general indication of soil shear strength and compressibility
3.2 REGIONAL/SITE GEOLOGY
The site is located in the Piedmont Physiographic Province of North Carolina. The native soils in
the Piedmont Province consist mainly of residuum with underlying saprolites weathered from the
parent bedrock, which can be found in both weathered and unweathered states. Although the
surficial materials normally retain the structure of the original parent bedrock, they typically have
a much lower density and exhibit strengths and other engineering properties typical of soil. In a
mature weathering profile of the Piedmont Province, the soils are generally found to be finer
grained at the surface where more extensive weathering has occurred. The particle size of the
soils generally becomes more granular with increasing depth and gradually changes first to
weathered and finally to unweathered parent bedrock. The mineral composition of the parent
rock and the environment in which weathering occurs largely control the resulting soil's
engineering characteristics. The residual soils are the product of the weathering of the parent
bedrock.
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3.3 SUBSURFACE CHARACTERIZATION
The following sections provide generalized characterizations of the soil and rock strata
encountered during our subsurface exploration. For subsurface information at a specific location,
refer to the Boring Logs in Appendix B.
Table 3.3.1 Subsurface Stratigraphy
Approximate
Depth Range
(ft)
Stratum Description Ranges of
SPT(1) N‐values
(bpf)
0 to 0.5
(Surface
cover)
n/a Varying amounts of topsoil was present at the
ground surface at each boring location. N/A
0.5 to 30 I
RESIDUAL – Elastic SILT (MH),Plastic CLAY (CH),
Sandy CLAY (CL), Clayey SAND (SC), Silty SAND (SM),
and Sandy SILT (ML)
4 to 62
12 to 15 II Partially Weathered Rock (PWR) (2)(3) 100+
Notes: (1) Standard Penetration Test
(2) PWR was encountered at Borings B‐101, B‐105, B‐110, and B‐111 at depths ranging from approximately 12 to
16 feet.
(3) Auger Refusal was encountered below PWR at Borings B‐101, B‐105, B‐110, and B‐111 at depths ranging from
approximately 15 to 16 feet.
3.4 GROUNDWATER OBSERVATIONS
Groundwater measurements were attempted at the termination of drilling and prior to
demobilization from the site. Each of the boring locations was dry at the time of drilling and to
the depths explored. Cave‐in depths were attempted to be measured at each of the boring
locations with cave‐in depths ranging from approximately 7.5 to 17 feet. Cave‐in of a soil test
boring can be caused by groundwater hydrostatic pressure, weak soil layers, and/or drilling
activities (i.e. drilling fluid circulation or advancement of bit).
Fluctuations in the groundwater elevation should be expected depending on precipitation, run‐
off, utility leaks, and other factors not evident at the time of our evaluation. Normally, highest
groundwater levels occur in late winter and spring and the lowest levels occur in late summer and
fall. Depending on time of construction, groundwater may be encountered at shallower depths
and locations not explored during this study. If encountered during construction, engineering
personnel from our office should be notified immediately.
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4.0 LABORATORY SERVICES
The laboratory testing performed by ECS for this project consisted of selected tests performed on
samples obtained during our field exploration operations. The following paragraphs briefly
discuss the results of the completed laboratory testing program.
An experienced geotechnical staff professional visually classified each soil sample from the test
borings on the basis of texture and plasticity in accordance with the Unified Soil Classification
System (USCS) and ASTM D‐2488 (Description and Identification of Soils‐Visual/Manual
Procedures). After classification, the staff professional then grouped the various soil types into
the major zones noted on the boring logs in Appendix B. The group symbols for each soil type are
indicated in parentheses following the soil descriptions on the boring logs. The stratification lines
designating the interfaces between earth materials on the boring logs are approximate; in situ,
the transitions may be gradual.
4.1 LABORATORY TESTING
In addition to visual classification, ECS performed five (5) natural moisture content tests, and two
(2) Atterberg limits tests on selected soil samples obtained from within the borings. The
laboratory testing was performed in general accordance with the applicable ASTM standards. The
results of the laboratory testing are presented on the respective Boring Logs included in the
Appendix.
0
5
10
15
20
25
30
780
775
770
765
760
755
750
S-1
S-2
S-3
S-4
S-5
S-6
SS
SS
SS
SS
SS
SS
18
18
18
18
18
10
18
18
18
14
18
10
(SM RESIDUAL) SILTY FINE TO MEDIUM
SAND, grayish brown, moist, medium dense
PARTIALLY WEATHERED ROCK SAMPLED
AS SILTY FINE TO MEDIUM SAND, grayish
brown
AUGER REFUSAL @ 15.0'
3
5
6
6
9
17
6
9
12
3
8
9
12
17
24
21
50/4
11
26
21
17
41
100+
CLIENT
The Keith Corporation
Job #:
08:4796-A
BORING #
B-111
SHEET
PROJECT NAME
Project Wheel - GEO
ARCHITECT-ENGINEER
The Keith Corporation
SITE LOCATION
Summit Park Drive, Salisbury, Rowan County, NC
NORTHING EASTING STATION
THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL.
WL WS WD BORING STARTED 12/27/17 CAVE IN DEPTH @ 7.5'
WL(SHW)WL(ACR) BORING COMPLETED 12/27/17 HAMMER TYPE Auto
WL RIG CME 55 FOREMAN Louis Everhart DRILLING METHOD 2.25 HSADRILLING METHOD 2.25 HSADEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION
DESCRIPTION OF MATERIAL
WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+
20% 40% 60% 80% 100%
1 2 3 4 5+
ENGLISH UNITS
BOTTOM OF CASING LOSS OF CIRCULATION
CALIBRATED PENETROMETER TONS/FT2
PLASTIC
LIMIT %
WATER
CONTENT %
LIQUID
LIMIT %
ROCK QUALITY DESIGNATION & RECOVERY
RQD% REC.%
STANDARD PENETRATION
BLOWS/FT780
1 OF 1
APPENDIX C – Laboratory Testing
Laboratory Summary
B-101B-102S-1 1.00 - 2.50 26.6B-103B-104S-1 1.00 - 2.50 18.0B-105S-1 1.00 - 2.50 13.2 CL 33 18 15B-106S-1 1.00 - 2.50 24.1B-107S-1 1.00 - 2.50 36.5 MH 75 50 25B-108B-109B-110B-111Laboratory Testing SummaryNotes:1. ASTM D 2216, 2. ASTM D 2487, 3. ASTM D 4318, 4. ASTM D 1140, 5. See test reports for test method, 6. See test reports for test methodDefinitions:MC: Moisture Content, Soil Type: USCS (Unified Soil Classification System), LL: Liquid Limit, PL: Plastic Limit, PI: Plasticity Index, CBR: California Bearing Ratio, OC: Organic Content (ASTM D 2974)Project No. 08:4796-AProject Name: Project Wheel - GEOPM: Josh BradshawPE: Lee J. McGuinnessPrinted On: Thursday, January 11, 2018SampleSourceSampleNumberDepth(feet)MC1(%)SoilType2LLAtterberg Limits3PL PIPercentPassingNo. 200Sieve4MaximumDensity(pcf)Moisture - Density (Corr.)5OptimumMoisture(%)CBRValue6OtherPage 1 of 1
APPENDIX D – SHWT Report
SOURCE:
GOOGLE EARTH
2017
NOT TO SCALE
FIGURE 1
SEASONAL HIGH WATER TABLE BORING MAP
PROJECT WHEEL
SUMMIT PARK DRIVE
SALISBURY, NORTH CAROLINA
ECS PROJECT NO. 49:5896
LEGEND
= Boring Location
SHWT Boring - 18
SHWT B-111