HomeMy WebLinkAboutReport of Geotechnical ExplorationGFA INTERNATIONAL
FLORIDA'S LEADING ENGINEERING SOURCE
Report of Geotechnical Exploration
Proposed Three -Story Residence
7928 S Ocean Drive (Lot 8 Diamond Sands)
St. Lucie County, Florida
September 28, 2018
GFA Project No. 18-8332.00
For: Phoenix Realty Homes
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' Florida's Leading Engineering Source
Environmental - Geotechnical - Construction Materials Testing - Threshold and Special Inspections - Plan Review & Code Compliance
September 28, 2018
Phoenix Realty Homes
Attn: Mr. Alan Tarpell
1760 N Jog Road, Suite 120
West Palm Beach, Florida 33411
Subject: Report of Geotechnical Exploration
Proposed Three -Story Residence
7928 S Ocean Drive (Lot 8 Diamond Sands)
St. Lucie County, Florida
GFA Project No. 18-8332.00
Dear Mr. Tarpell:
GFA International, Inc. (GFA) has completed the subsurface exploration and geotechnical
engineering evaluation for the above referenced project in accordance with the geotechnical
and engineering service agreement for this project. The scope of services was completed in
accordance with our Geotechnical Engineering Proposal (18-8332.00), planned in conjunction
with and authorized by you.
EXECUTIVE SUMMARY
The purpose of our subsurface exploration was to classify the nature of the subsurface soils and
general geomorphic conditions at the site and evaluate their impact upon the proposed
construction. This report contains the results of our subsurface exploration and our engineering
interpretations of these with respect to the project characteristics described to us, including
providing recommendations for site preparation and design of the foundation system.
Based on conversations with the client, we understand the project consists of constructing a
three -level residence. Since the residential structure (or a portion thereof) will be located east of
the Coastal Construction Control Line (CCCL), a pile supported foundation is required. The
main residence will be elevated above a lower level garage that may have walls and ground
floor slab of frangible breakaway design. We assume the structure will utilize conventional
design and construction and be supported by columns founded upon the pile foundations.
Project -specific structural design loads have not been provided to us. For the foundation
recommendations presented in this report, we assumed the maximum column load will be 50
kips and the maximum wall loading (if applicable) will be 3 kips per linear foot. Based on current
site grades, we estimate that up to 2 feet of fill will be required to achieve final grade.
The recommendations provided herein are based upon the above considerations. If the stated
conditions are incorrect or if project description is revised, please inform GFA so that we may
review our recommendations with respect to any modifications.
607 NW Commodity Cove - Port St. Lucie, Florida 34986 - (772) 924.3575 - (772) 924.3580 (fax) - www.teamgfa.com
OFFICES THROUGHOUT FLORIDA
Proposed Three -Story Residence Geotechnica/ Exploration Report
7928 S Ocean Drive, St. Lucie County, Florida September 28, 2018
GFA Project No. 18-8332.00 Page 2 of 12
Two (2) standard penetration test (SPT) borings, advanced to a depth of approximately 40 feet
below the existing ground surface, were completed for this study. The subsurface soil conditions
encountered at the boring locations generally consisted of medium dense to very dense fine
sand (SP) to an approximate depth of 33.5 feet, then very loose to loose silt (ML) to a depth of
38.5 feet, and then medium dense silty fine sand and dense fine sand (SP) to the boring
termination depths of approximately 40 feet below the existing ground surface. Please refer to
Appendix D - Record of Test Borings for a detailed account of each boring.
GFA recommends that the .proposed residence be supported by a deep foundation system
consisting of augered cast -in -place (ACIP) piles. Based on our analysis, GFA estimates that a
16-inch diameter ACIP pile installed to a depth of 20 feet below the existing ground surface can
provide a maximum allowable axial compressive capacity 'of 40 tons and a maximum tension
capacity of 3.5 tons. GFA estimates that a 16-inch-diameter ACIP pile installed'to a depth of 30
feet below the existing ground surface can provide a'maximum allowable axial compressive
capacity of 27 tons and a maximum tension capacity of 7.5 tons.
For the ground supported frangible walls and on -grade concrete floor slabs, a maximum
allowable bearing capacity of 2,500 psf may be used for shallow foundation design. The
subgrade soils should be improved (densified) with compaction from the stripped grade prior to
constructing the foundation pads and performing the footing excavations. The top 2 feet below
stripped grade should be compacted to a minimum of 95 percent density prior to placing fill to
achieve final grade. Fill (including stem wall backfill) should be placed in 12-inch lifts and
compacted to achieve a minimum 95 percent density. After completing the footing excavations,
the subgrade to a depth of 2 feet below bottom of footings should be compacted to achieve a
minimum 95 percent density.
Scour elevations used in pile capacity calculations are those provided by the Florida DEP for
coastal construction but may not be adequate for actual scour elevations exceeding the DEP
assumptions that may occur in hurricane events. Therefore, our analysis is limited to the DEP
scour elevation criteria. Additional scour analysis was not included in our scope of work.
GF
Proposed Three -Story Residence
7928 S Ocean Drive, St. Lucie County, Florida
GFA Project No. 18-8332.00
Geotechnical Exploration Report
September 28, 2018
Page 3 of 12
We appreciate the opportunity to be of service to you on this project and look forward to a
continued association. Please do not hesitate to contact us if you have any questions or
comments, or if we may further assist you as your plans proceed.
Respectfully Submitted,
GFA International, Inc.
Florida C�VtiN61616f #ythorization No. 4930
�oMN•
cENSF '
3218
i/O�• STATE
RIDP cl —Z Y-19
Senior P.r9�i1 iel
Florida Registftl No. 63218
Distribution: Mr. Alan Tarpell — Phoenix Realty Homes
Craig Van Collie, E.I.
Project Manager
1 pdf
Proposed Three -Story Residence
Geotechnical Exploration Report
7928 S
Ocean Drive, St Lucie County, Florida
September 28, 2018
GFA Project No. 18-8332.00
Page 4 of 12
TABLE OF CONTENTS
1.0 INTRODUCTION.................................................................................................................5
1.1
Scope of Services............................................................................................................5
1.2
Project Description...........................................................................................................5
2.0 OBSERVATIONS.................................................................................................................5
2.1
Site Description................................................................................................................5
2.2
Field Exploration..............................................................................................................6
2.3
Visual Classification.........................................................................................................6
2.4
Geomorphic Conditions....................................................................................................6
2.5
Hydrogeological Conditions..............................................................................................7
3.0 ENGINEERING EVALUATION AND RECOMMENDATIONS
..............................................7
3.1
General............................................................................................................................7
3.2
Pile Foundation Design....................................................................................................7
3.3
Pile Installation..................................................................................................................9
3.4
Foundations for Ground Level Frangible Walls...............................................................10
3.5
Ground Level Floor Slabs (Frangible).............................................................................10
3.6
Site Preparation.............................................................................................................10
3.7
Vibration Monitoring.......................................................................................................11
4.0 REPORT LIMITATIONS.....................................................................................................12
5.0 BASIS FOR RECOMMENDATIONS..................................................................................12
Appendix A - Vicinity Map
Appendix B - Test Location Plan
Appendix C - Notes Related to Borings
Appendix D - Record of Test Borings
Appendix E - Pile Capacity Graphs
Appendix F - Discussion of Soil Groups
GF
Proposed Three -Story Residence Geotechnical Exploration Report
7928 S Ocean Drive, St. Lucie County, Florida September 28, 2018
GFA Project No. 18-8332.00 Page 5 of 12
1.0 INTRODUCTION
1.1 Scope of Services
The objective of our geotechnical services was to collect subsurface data for the subject project,
summarize the test results, and -discuss any apparent site conditions that may have
geotechnical significance for building construction. The following scope of services are provided
within this report:
1. Prepare boring logs depicting the subsurface soil conditions encountered during our field
exploration.
2. Review the soil samples obtained during our field exploration for classification and additional
testing if necessary.
3. Evaluate the existing soil conditions found during our exploration with respect to foundation
support for the proposed structure.
4. Provide recommendations with respect to foundation support of the structure, including
allowable soil bearing capacity, bearing elevations, and foundation design parameters.
5. Provide site preparation procedures for the proposed construction.
1.2 Project Description
Based on conversations with the client, we understand the project consists of constructing a
three -level residence. Since the residential structure (or a portion thereof) will be located east of
the Coastal Construction Control Line (CCCL), a pile supported foundation is required. The
main residence will be elevated above a lower level garage that may have walls and ground
floor slab of frangible breakaway design. We assume the structure will utilize conventional
design and construction and be supported by columns founded upon pile foundations. Structural
design loads have not been provided to us. For the foundation recommendations presented in
this report, we assumed the maximum column load will be 50 kips and the maximum wall
loading (if applicable) will be 3 kips per linear foot. Based on current site grades, we estimate
that up to 2 feet of fill will be required to achieve final grade.
The recommendations provided herein are based -upon the above considerations. If the stated
conditions are incorrect or if project description is revised, please inform GFA so that we may
review our recommendations with respect to any modifications.
2.0 OBSERVATIONS
2.1 Site Description
The project site was heavily wooded with trees and shrubs. Limited clearing by the client was
necessary for GFA to access the boring locations. The grade at the site was estimated to be
even to slightly below the adjacent roadway at the time of drilling. The Atlantic Ocean bordered
the eastern side of the property.
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Proposed Three -Story Residence Geotechnica/ Exploration Report
7928 S Ocean Drive, St. Lucie County, Florida September 28, 2018
GFA Project No. 18-8332.00 Page 6 of 12
2.2 Field Exploration
Two (2) standard penetration test (SPT) borings, advanced to depths of approximately 40 feet
below the existing ground surface, were completed for this study. The locations of the borings
are illustrated on the Test Location Plan in in Appendix B.
The Standard Penetration Test (SPT) method was used as the investigative tool within the
borings. The SPT tests were performed in substantial accordance with ASTM D 1586,
"Penetration Test and Split -Barrel Sampling of Soils." The SPT test procedure consists of
driving a 1.4-inch I.D. split -barrel sampler into the soil profile using a 140-pound hammer falling
30 inches. The number of blows per foot, for the second and third 6-inch increment, is referred
to as the N-value. The N-value has been empirically correlated with various soil properties and
provides an indication of soil strength.
The soil samples recovered from the borings were visually classified and their stratification is
illustrated on the boring logs in Appendix D. It is noted that soil conditions may vary between
the strata interfaces indicated on the logs. The soil boring data reflect information from the
specific test locations only. The boring depths were established based upon our knowledge of
vicinity soils and confined to the zone of soil likely to be influenced by the proposed
construction.
Site specific survey staking for the borings was not provided for our field exploration. The
indicated depth and location of the borings were approximated based upon existing grade and
estimated distances and relationships to existing site features and other landmarks.
2.3 Visual Classification
Soil samples recovered from our field exploration were returned to our laboratory where they
were visually classified by a geotechnical engineer in general accordance with the Unified Soil
Classification System (ASTM D 2487). After reviewing the recovered soil samples, no laboratory
testing was deemed necessary. Samples of the soils encountered during our field exploration
will be held in our laboratory for 30 days and then discarded unless we are notified otherwise in
writing.
The recovered samples were not evaluated, either visually or analytically, for chemical
composition or environmental hazards. GFA would be pleased to perform these services for an
additional fee, if required.
2.4 Geomorphic Conditions
The geology of the site as mapped on the USDA Soil Survey website consists of Canaveral fine
sand, 0 to 5 percent slopes (8). These are sandy soils and organic soils are not indicated. It
should be noted that the Soil Survey generally extends to a maximum depth of 80 inches below
ground surface and is not indicative of deeper soil conditions.
The boring logs resulting from our field exploration are presented in Appendix D - Record of
Test Borings. The logs contain the soil descriptions and the penetration resistance (N-values)
logged during the drilling and sampling activities. The classifications and descriptions shown on
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Proposed Three -Story Residence Geotechnical Exploration Report
7928 S Ocean Drive, St Lucie County, Florida September 28, 2018
GFA Project No. 18-8332.00 Page 7 of 12
the logs are generally based upon visual characterizations of the recovered soil samples using
the Unified Soil Classification System, modified as necessary to describe typical Florida
conditions. -See Appendix F - Discussion of Soil Groups, for a detailed description of various
soil groups.
The subsurface soil conditions encountered at the boring locations generally consisted of
medium dense to very dense fine sand (SP) to an approximate depth of 33.5 feet, then very
loose to loose silt (ML) to a depth of 38.5 feet, and then medium dense silty fine sand and
dense fine sand (SP) to the boring termination depths of approximately 40 feet below the
existing ground surface.
2.5 Hydrogeological Conditions
On the date of our field exploration, the groundwater table was encountered at depths of
approximately 5.0 and 6.7 feet below the existing ground surface. The groundwater table will
fluctuate seasonally depending upon local rainfall and other site specific and/or local influences,
including the water level in the nearby Atlantic Ocean with tidal influences. Brief ponding of
stormwater may occur across the site after heavy or extended rainfall events.
No additional evaluation was included in our scope of work in relation to the wet seasonal high
groundwater table or any existing well fields in the vicinity. Well fields may influence water table
levels and cause significant fluctuations. If a more comprehensive water table analysis is
necessary, please contact our office for additional guidance.
3.0 ENGINEERING EVALUATION AND RECOMMENDATIONS
3.1 General
Our geotechnical engineering evaluation of the site and subsurface conditions at the property,
with respect to the planned construction, and our recommendations for site preparation and
foundation support, are based upon (1) our site observations, (2) the field data obtained, and (3)
our understanding of the project information and structural conditions as presented in this
report. If the stated conditions are incorrect, or if the project description is revised, please
inform GFA so that we may review our recommendations with respect to any modifications.
We note that the applicability of geotechnical recommendations is very dependent upon project
characteristics, specifically (1) improvement locations, (2) grade alterations, (3) and actual
applied structural loads. For that reason, GFA must be provided with and review the preliminary
and final site and grading plans, and structural design loads to validate all recommendations
provided in this report. Without performing this review, our recommendations should not be
relied upon for final design or construction of any site improvements.
3.2 Pile Foundation Design
Since the residential structure (or portions thereof) will be located east of the Coastal
Construction Control Line (CCCL), a pile supported foundation is required. Frangible ground
Proposed Three -Story Residence Geotechnical Exploration Report
7928 S Ocean Drive, St Lucie County, Florida September 28, 2018
GFA Project No. 18-8332.00 Page 8 of 12
level floor slabs and garage walls may be either pile supported or supported upon spread
footings (final design to be determined by others).
GFA considered the following design criteria to develop pile foundation recommendations for
the proposed structure:
1. For CCCL construction, the FDEP has established a 100-year storm elevation (bottom of
lowest structural member) of +17.0 or +17.9 feet NGVD (depends on location) -for
structures within St. Lucie County.
2. For CCCL construction, the FDEP has established a 100-year storm erosion elevation
(design scour elevation) of +2.7 feet NGVD for all of St. Lucie County.
3. A loss of soil support between the bottom of lowest structural member and design scour
elevation (+2.7 feet NGVD) was considered in the pile capacity analyses.
4. The residence will utilize conventional construction and be supported by columns
terminating on pile caps slightly below the ground floor level. Fill will be placed to
achieve final (or near final) grade before installing the pile foundations, and top of piles
(bottom of pile caps) would be about +8 feet NGVD/+6.5 feet NAVD.
Considering the subsurface conditions encountered at the boring locations, GFA recommends
that a deep foundation system consisting of augered cast -in -place (ACIP) piles be used for
support _ of the proposed residence. ACIP pile design should be in accordance with the
applicable sections of the Florida Building Code (2017), Sixth Edition, the latest edition of the
Deep Foundations Institute's Augered Cast -In -Place Piles Manual, and other applicable federal,
state, and local requirements.
The results of our ACIP pile capacity evaluations are summarized in the table below. The lateral
capacity and pile top deflection were calculated using the commercially available ALLPILE 7.0
software.
ACIP Pile Recommendations for Pile Supported Structures
Nominal
Maximum
Pile
Pile
Pile Top
Recommended
Pile
Allowable Pile
Allowable
Grout
Diameter
Elevation
Pile Tip
Length
Compression
Tension
Pile Lateral
Strength
in
NGVD
Elevation
ft
Capacity*
Ca aci
Capacity"(psi)
1.75 Tons
16
Unknown
Unknown
20
40 tons
3.5 tons
(Free Head)
12.5 Tons
5,000
Fixed Head
1.75 Tons
16
Unknown
Unknown
30
27 tons
7.5 tons
(Free Head)
12.5 Tons
5,000
Fixed Head
* Pile Capacity Graphs shown in Appendix E.
** For calculated pile top deflection of % inches at top of pile elevation.
Proposed Three -Story Residence
7928 S Ocean Drive, St. Lucie County, Florida
GFA Project No. 18-8332.00
Geotechnical Exploration Report
September 28, 2018
Page 9 of 12
The pile design curves resulting from our analysis are presented in Appendix E. If piles having
either lesser or greater capacities are required other than those presented in the above table,
GFA would be pleased to provide further recommendations upon request.
The following notes are also applicable to the ACIP pile design:
GFA assumed that the piles will have a minimum of 1 percent steel reinforcement for the
analysis. ACIP piles should be reinforced over their entire length for tension capacity.
The reinforcement shall be as designed by the project Structural Engineer.
2. Structural stresses in the piles may impose a more severe limitation on the design
capacity. Therefore, we recommend the allowable stresses be verified for the selected
pile section by the project Structural Engineer.
3. The pile reinforcement should be sufficiently embedded in the pile cap to afford a fixed
end connection, as required.
3.3 Pile Installation
Pile design and installation should be in accordance with the applicable sections of the Florida
Building Code and other applicable federal, state and local requirements. In addition, piles
should be installed in accordance with the following:
Pile Length - The proposed piles should be installed as determined by the inspecting
Geotechnical Engineer.
2. Spacing - Piles installed in groups should be spaced at a center -to -center distance of not
less than 3 pile diameters.
3. Plan Location - The center of the top of any pile at cut-off should, be displaced laterally
no more than 3 inches from the position shown on the plans. This applies to both single
piles and piles installed in groups.
4. Vertical Alignment - The vertical alignment of the piles should not deviate from the plumb
by more than 1/4 inch per foot of length.
5. Reinforcing Cage Positioning - The top of the reinforcing cages installed in the piles
should not be more than 6 inches above and no more than 3 inches below the positions
shown in the plans. The reinforcing cages should be positioned concentrically within the
grouted pile shaft. The grout cover over longitudinal reinforcing bars should not be less
than 3 inches. Reinforcing centralizers should be placed at maximum spacing of 15 feet
at the lower portion of the pile and at 5 feet from the top of the cage.
6. Adiacent Piles - A minimum elapsed time of 12 hours should be specified for the
installation of piles located within 5 feet, center -to -center, of each other.
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Proposed Three -Story Residence Geotechnical Exploration Report
7928 S Ocean Drive, St. Lucie County, Florida September 28, 2018
GFA Project No. 18-8332.00 Page 10 of 12
7. Grout Factor - The minimum acceptable grout factor (i.e. actual grout volume divided by
theoretical grout volume) should be 1.1.
3.4 Foundations for Ground Level Frangible Walls
The footings may be designed using a maximum allowable soil bearing pressure of 2,500 psf.
Shallow foundations should be embedded a minimum of 12 inches below final grade. The
embedment should be measured from- the lowest adjacent grade. Isolated column footings
should be at least 24 inches in width. Continuous strip footings should have a width of at least
18 inches regardless of contact pressure.
Once site preparation has been performed in accordance with the recommendations outlined in
Section 3.6 of this report, the soils should readily support any structures bearing upon shallow
foundations. For such structures, settlements are estimated not to exceed 1-inch total and 0.5-
inch differential. Footings and columns should be structurally separated from any ground level
floor slabs, as they will be loaded differently and at different times, unless a monolithic mat
foundation is designed.
3.5 Ground Level Floor Slabs (Frangible)
Ground level floor slabs may be supported directly on the existing grade or on granular fill
following the foundation site preparation and fill placement procedures outlined in Section 3.6 of
this report. We recommend that a modulus of subgrade reaction of 150 pounds per cubic inch
(pci) be considered during design. The ground floor slabs should be structurally separated from
walls and columns to allow for differential vertical movement, unless a monolithic mat foundation
is designed.
Water vapor is likely to rise through the granular fill and condense below the base of floor slabs.
If moisture entry into the slabs is not desirable, an appropriate moisture vapor barrier should be
installed at the slab bottom - subgrade interface.
3.6 Site Preparation
Our recommendations. for preparation of the site and fill placement and compaction are
presented below. This approach to improving and maintaining site soils has been found to be
successful on projects having similar soil conditions.
1. Initial site preparation should consist of performing stripping (removing surface vegetation,
near surface roots, and other deleterious matter) and clearing operations. This should be
performed within, and to a distance of five (5) feet beyond, the perimeter of the footprint of
the planned construction. Foundations and the below grade remains of any other structures
that are within the construction area should also be removed. Similarly, utility lines within the
limits of the proposed construction should also be removed, relocated, or properly
abandoned so that they will not adversely impact overlying structures.
2. The stripped areas should be proof rolled and compacted until the upper 2 feet of soil
achieve a density of at least 95 percent of the modified Proctor maximum dry density (ASTM
D 1557). We recommend using a steel drum vibratory roller or track -mounted equipment
Proposed Three -Story Residence
7928 S Ocean Drive, St Lucie County, Florida
GFA Project No. 18-8332.00
Geotechnical Exploration Report
September 28, 2018
Page 11 of 12
having sufficient static weight to achieve the required compaction. Density tests should be
performed on the proof rolled surface at a frequency of not less than one test per 2,500
square feet, or a minimum of three (3) tests, whichever is greater. The density tests should
be performed using either the nuclear method (ASTM D 6839) or the sand cone method
(ASTM 1556). Hand Cone Penetrometer (HCP) tests may also be performed to evaluate
soil density.
3. Fill material may then be placed in the building pad area as required. The fill material should
be inorganic (classified as SP, SW, GP, GW, SP-SM, SW-SM, GW-GP, GP -GM) containing
not more than 5 percent (by weight) organic materials. Fill materials having silt/clay-size
soil fines contents of more than 12 percent should not be used. Each lift should be
compacted and tested prior to the placement of the next lift. Density tests should be
performed within the fill at a frequency of not less than one test per 2,500 square feet per lift
in the building area, or a minimum of three (3) tests per lift, whichever is greater.
4. Fill which will be compacted using full-size vibratory compaction equipment should be
placed lifts having a maximum thickness of 12 inches. If the roller is operating in the static
mode or if track -mounted equipment is used for compaction, the lift thickness should be
reduced to 8 inches. Fill that will be compacted using hand -operated or portable equipment,
such as vibratory sleds, jumping jacks, or walk -behind rollers, should have a maximum lift
thickness of 6 inches.
5. For shallow spread footings placed on either structural fill or compacted native granular
soils, the final bearing subgrade should be tested for compaction and observed by an
engineer or geologist or his/her representative to determine if the soils are free of organic
and/or deleterious materials. Density tests should be performed at a frequency of not less
than one (1) density test per each isolated column footing and one (1) test per each seventy
five (75) lineal feet of wall footings.
6. Following installation of the ACIP piles and construction of the pile caps, the areas next to
the pile caps will also require backfilling. Each lift of backfill should be compacted to at least
95 percent of the modified Proctor maximum dry density (ASTM D 1557). We anticipate that
portable equipment will be required for compaction of the backfill.
7. The contractor should consider the final design contours and grades contained in the project
plans when executing backfilling and compaction operations.
3.7 Vibration Monitoring
The proposed construction will be within proximity to nearby residential structures and roadways
that could be susceptible to damage from vibrations generated at the site during site preparation
and foundation installation. We recommend that these structures and other bordering landmarks
be monitored using a seismograph to determine the extent of vibration absorption they are
experiencing during all aspects of construction. The seismograph used for monitoring at the site
should have the capability to measure ground velocities along vertical, transverse, and
longitudinal axes. The project Structural Engineer should establish allowable ground velocities
that the bordering facilities can safely withstand without incurring damage. A proposal for GFA
personnel to provide the vibration monitoring during construction will be provided upon request.
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Proposed Three -Story Residence Geotechnical Exploration Report
7928 S Ocean Drive, St. Lucie County, Florida September 28, 2018
GFA Project No. 18-8332.00 Page 12 of 12
4.0 REPORT LIMITATIONS
This consulting report has been prepared for the exclusive use of Phoenix Realty Homes, the
current owner(s), and other members of the design team for the proposed residence located at
7928 S Ocean Drive (Lot 8 Diamond Sands) in St. Lucie County, Florida. This report has been
prepared in accordance with generally accepted local geotechnical engineering practices; no
other warranty is expressed or implied.
The evaluation submitted in this report is based in part upon the data collected during a field
exploration. However, the nature and extent of variations throughout the subsurface profile may
not become evident until construction. If variations then appear evident, it may be necessary to
reevaluate the information and professional opinions provided in this report. In the event
changes are made in the nature, design, or location of the proposed residence, the evaluation
and opinions contained in this report should not be considered valid unless the changes are
reviewed, and conclusions modified or verified in writing by GFA.
GFA should be provided the opportunity to review the final foundation plans and specifications
to determine if GFA's recommendations have been properly interpreted, communicated, and
implemented. If GFA is not afforded the opportunity to participate in construction related
aspects of foundation installation as recommended in this report or any report addendum, GFA
cannot accept responsibility for the interpretation of our recommendations made in this report or
in a report addendum for foundation performance
Scour elevations used in pile capacity calculations are those provided by the Florida DEP for
coastal construction but may not be adequate for actual scour elevations exceeding the DEP
assumptions that may occur in hurricane events. Therefore, our analysis is limited to the DEP
scour elevation criteria. Additional scour analysis was not included in our scope of work.
5.0 BASIS FOR RECOMMENDATIONS
The analysis and recommendations submitted in this report are based on the data obtained
from the borings performed at the locations indicated on the Test Location Plan in Appendix B.
This report does not reflect any variations which may occur between the borings. While the
borings are representative of the subsurface conditions at their locations and vertical reaches,
local variations characteristic of the subsurface soils within the region are anticipated and may
be encountered. The delineation between soil types shown on the boring logs is approximate
and the descriptions represent our interpretation of the subsurface conditions at the designated
boring locations on the specific date drilled.
Any third -party reliance of our geotechnical report or parts thereof is strictly prohibited without
the expressed written consent of GFA International, Inc. The applicable SPT methodology
(ASTM D 1586) used in performing our borings and for determining penetration resistance is
specific to the sampling tools utilized and does not reflect the ease or difficulty to advance other
tools or materials.
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Appendix A - Vicinity Map
60
.; M ,
Appendix B - Test Location Plan
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Test Location Plan: 7928 S Ocean Drive, St. Lucie County, FL
'M,iq',he.'lle, Fr8h'klJ'h,,,GFA-- Saint: Lucie :County PrQpe.rty. Apprai's&
,;A,p ril, 3,, 2018,
11128
0 A0075 0.015 'om -Mi
0 0L015-- :0.03 0.06-km
aid Is k0twaflabVd.
000PV09MOISSM Loot! C01,111 FMPtMfAPPM15.r.AIfrqIt tserued.
Approximate Standard Penetration Test (SPT) Boring Locations
Appendix C - Notes Related to Borings
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NOTES RELATED TO BORING RECORDS AND
GENERALIZED SUBSURFACE PROFILES
1. Groundwater levels (if encountered) were recorded either during or following the boring completion on
the date indicated. Fluctuations in groundwater levels are common - see the report text for a discussion.
2. The boring locations were identified in the field by estimated distances and offsets from existing reference
marks and/or other site landmarks.
3. The completed boreholes were backfilled to adjacent site grade using drilling spoils and patched with
asphalt cold mix in pavement areas.
4. The Log of Boring records represent our interpretation of soil conditions based on visual classification of
the soil samples recovered from the borings.
5. The Log of Boring records are subject to the limitations, conclusions, and recommendations presented in
the report text.
6. The Standard Penetration Test (SPT) N-values contained on the Log of Boring records refer to the total
blow counts of a 140-pound drop hammer falling 30 inches required to drive a split -barrel sampler a total
distance of 12 inches into soil strata at specific depth intervals.
7. The Hand Cone Penetrometer (HCP) values contained on Log of Boring records and the Cone
Penetration Test (CPT) values contained on the Cone Penetration Sounding logs refer to the cone tip
resistance recorded when pushing the cone tip into the soil strata at specific depth intervals.
8. The soil and/or rock strata interfaces shown on the Log of Boring records are approximate and may vary
from those shown on the logs. The soil and/or rock descriptions shown on the Log of Boring records refer
to conditions at the specific location tested. Soil/rock conditions may vary between test locations.
9. Relative density for coarse -grained soils (sands/gravels) and consistency for fine-grained soils (silts/clays)
are described as follows:
Coarse Grained Soils
(Sands and Gravels)
Fine Grained Soils
(Silts and
Clays)
SPT
N-Value
HCP Value
(kg/cm)
CPT Value
(tsf)
Relative
Density
SPT
N-Value
I HCP Value
(kg/cm)
CPT Value
(tsf)
Consistency
0-4
0-16
0-20
Very Loose
0-2
0-20
0-3
Very Soft
5-10
17-36
21-40
Loose
3-4
21-35
4-6
Soft
11-30
37-116
41-120
Med. Dense
5-8
>35
7-12
Firm
31-50
117-196
121-200
Dense
9-15
13-25
Stiff
>50
> 196
>200
Very Dense
16-30
26-50
Very Stiff
>30
1 >50
Hard
10. Grain size descriptions are as follows:
Description
Particle Size Limits
Boulder
Greater than 12 inches
Cobble
3 to 12 inches
Coarse Gravel
3/4 to 3 inches
Fine Gravel
No. 4 sieve to 3/4 inch
Coarse Sand
No. 10 to No. 4 sieve
Medium an
No. 40 to No. 10 sieve
Fine Sand
No. 200 to No. 40 sieve
Fines(Silt/Clay)
Smaller than No. 200 sieve
11. Definitions for modifiers used in soil/rock descriptions:
Proportion
I Modifier
Approximate Root Diameter
Modifier
<5%
Trace
Less than /32"
Fine roots
5% to 12%
Little
1/32" to 1/4"
Small roots
12% to 30%
Some
'/a" to 1"
Medium roots
30% to 50%
And
Greater than 1"
Large roots
Organic Soils: Soils containing vegetative tissue in various stages of decomposition having a fibrous to amorphous
texture. Usually having a dark brown to black color and an organic odor.
Organic Content Modifiers: <25%: Slightly to Highly Organic; 25% to 75%: Muck; >75%: Peat
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Appendix D - Record of Test Borings
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LOG OF BORING SPT-1
GFA International PAGE 1 OF 1
�,y� RNAri��py
CLIENT Phoenix Realty Homes PROJECT NAME Lot 8 Diamond Sands
PROJECT NUMBER 18-8332.00 PROJECT LOCATION 7928 S Ocean Dr., St. Lucie County
DRILLING CONTRACTOR GFA International Inc. HOLE DEPTH 40 ft HOLE DIAMETER
DRILLER PM/RM DATE STARTED 8/24/18 COMPLETED 8/24/18
DRILL RIG Simco GROUND WATER LEVEL: VAT TIME OF DRILLING 6.70 ft
METHOD SPT LATITUDE 27.31941 LONGITUDE-80.22606
NOTE: HAMMER TYPE
w
SPT N VALUE A
p
U
o
>
U
w
U
20 40 60 80
�--
o-
P: —
Q
=O
o_ O
MATERIAL DESCRIPTION
�m
w
O
�z
-
>
�z
LO
Zz
PL MC LL
w"
O
>�-
w
qQ�
(g
�
Z
m O
U
Z
�
g p
p
20 0 60 80
❑ FINES CONTENT (%) ❑
ui
O
20 40 60 80
Light brown fine sand, trace shell (SP)
1
1
2
1
3
1
3
2
13
17
14
20
5
3
17
34
20
8
Q
4
10
18
12
e
5
10
12
22
10
17
6
27
24
17
41
15
7
15
26
62
20
36
8
23
25
30
55
25
9
18
24
25
49
30
33.5
Gray silt (ML)
10
2
35
2
4
38.5
Gray fine sand with few shell fragments (SP)
11
13
zz
40.0
35
"v Bottom of borehole at 40.0 feet.
LOG OF BORING SPT-2
GFA International PAGE 1 OF 1
'RNAi1�aPv
CLIENT Phoenix Realty Homes PROJECT NAME Lot 8 Diamond Sands
PROJECT NUMBER 18-8332.00 PROJECT LOCATION 7928 S Ocean Dr., St. Lucie County
DRILLING CONTRACTOR GFA International Inc. HOLE DEPTH 40 ft HOLE DIAMETER
DRILLER PM/RM DATE STARTED 8/24/18 COMPLETED 8/24/18
DRILL RIG Simco GROUND WATER LEVEL: �ZAT TIME OF DRILLING 5.00 ft
METHOD SPT LATITUDE 27.31928 LONGITUDE-80.22624
NOTE: HAMMER TYPE
W
o,
o
o
♦ SPT N VALUE A
p
U
n i
�m
r
u)
W
C✓ ��-
U
20 40 60 80
PL MC LL
1�I
d
W"
Q
>�
=O
a 0
J
MATERIAL DESCRIPTION
g
w
>
0z
O¢
m
D
�z
W
Zz
a W
0
L
O
� Z
0
Z
O z
O z
20 40 60 80
W
W
20
0
❑ FINES CONTENT (%) ❑
20 40 60 80
Light brown fine sand, trace shell (SP)
2
1
2
2
4
2
3
2
8
14
10
5
17
3
20
az
60
38
5
4
i6
26
15
7
5
15
24
:c
10
21
13.5
o
Light brown cemented sand (GP)
6
20
22
15
o p
3z
54
O
o p
OCl
18.5
Brown fine sand with shell fragments (SP)
7
20
26
20-33
59
23.5
Gray fine sand with few shell fragments (SP)
8
28
25
2s
54
28.5
Dark gray fine sand, trace shell (SP)
9
11
30
23
42
65
33.5
Gray silt (ML)
10
2
3L14
35
3
38.5
��
Gray fine sand and silt (SM)
11
2
a
:................ ......:.......
•
40.0
Bottom of borehole at 40.0 feet.
Appendix E - Pile Design Curves
Gr
TMPOP
ALL -PILE CWReck SOM6R ua ommel= LbelSeEb
ALLOWABLE CAPACITY vs FOUNDATION DEPTH
so so
81 81
72 72
Q. 63 63
CL
} Y
M a
Or 54 v 54
U A
N
U 45 C 45
C U
O
a 36 36
n
E
27 27
18 18
9 9
01 0
0 4 8 12 16 20 24 28 32 36 40 0 4 8 12 16 20 24 28 32 36 40
Foundation Depth, L A Foundation Depth, L -ft
CiWiTech
Software Figure 1
Lateral Capacity with a Free Head Condition
ALL -PILE cklirrecieairsre wmMMCimm LCeesedb
(Zp) DEFLECTION, yt -in
p-ft -1.00
0
Lateral
Moment
Vertical
pt
Slope
Max.
No.
Load
Load
Load
at Top at Top
Moment
(kip)
(kip-ft)
(kip)
(in)
(in6n)
(kip-ft)
1
0.5
1.0
80.0
0.1
0.00
4.1
2
1.5
3.0
80.0
0.2
0.00
12.6
3
2.5
5.0
60.0
0.3
0.00
21.3
4
3.5
7.0
80.0
0.5
0.01
30.3
5
4.0
8.0
80.0
0.6
-0.01
34.7
6
4.5
9.0
80.0
0.7
-0.01
392
7
5.0
10.0
80.0
0.8
-0.01
43.6
Civiffech
Software
PILE DEFLECTION vs LOADING
Single Pile, Khead=1, Khc=1
0
+1.00
Figure 2
Depth (Zp)
from
Pile Top-ft
0�
10-
20 -
30 -
40 -
50 -
60 -
�ERYASNN�
Lateral Capacity with a Fixed Head Condition
ALL -PILE CWrreai SMare IM ICIIIMCIDOM Lbeise=
Depth (Zp) DEFLECTION, yt -in
from
Pile Top-ft -0.50
0
Lateral
Slope
Vertical
yt
Slope
Max.
No.
Load
Restraint
Load
at Top
at Top
Moment
((1p)
(inAn)
(kip)
(in)
(inAn)
(kip-ft)
1
2.5
0.0
10.0
0.0
0.00
-10.3
2
7.5
0.0
10.0
0.1
0.00
-34.3
3
12.5
0.0
10.0
0.2
0.00
-59.8
4
17.5
0.0
10.0
0.3
0.00
-85.8
5
20.0
0.0
10.0
0.4
0.00
-100.0
6
22.5
0.0
10.0
0.4
0.00
-113.3
7
25.0
0.0
10.0
0.5
0.00
-126.7
CIWITech
Software
PILE DEFLECTION vs LOADING
Single Pile, Khead=5, Kbc=2
0
+0.50
Figure 2
fromh (Zp)
Pile Top-ft
0-
10-
20 -
30 -
40 -
50 -
60 -
Appendix F - Notes Related to Borings
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DISCUSSION OF SOIL GROUPS
COARSE GRAINED SOILS
General. A soil is classified as coarse -grained if more than 50 percent of a representative
sample of the material is retained on the No. 200 sieve.
GW and SW Groups. These groups comprise well -graded gravelly and sandy soils
containing little or no plastic fines (less than 5 percent passing the No. 200 sieve). The low
fines content does not noticeably change the shear strength characteristics of these soils
and does not interfere with their free -draining characteristics.
GP and SP Groups. Poorly graded gravels and sands containing little or no plastic fines
(less than 5 percent passing the No. 200 sieve) are in the GP and SP groups. The
materials can be called uniform gravels, uniform sands, or non -uniform mixtures of very
coarse materials and very fine sand, with intermediate sizes lacking (sometimes called
skip -graded, gap -graded, or step -graded). This last group often results from borrow pit
excavation in which gravel and sand layers are mixed.
GM and SM Groups. In general, the GM and SM groups comprise gravels or sands with
fines (more than 12 percent passing the No. 200 sieve) having little or no plasticity. The
plasticity index and liquid limit of soils in these groups plot below the "A" line on the
plasticity chart. The gradation of the material is not considered significant and both well
and poorly graded materials are included.
GC and SC Groups. In general, the GC and SC groups comprise gravelly or sandy soils
containing fines (more than 12 percent passing the No, 200 sieve) having plasticity
characteristics. The plasticity index and liquid limit of soils in these groups plot above the
"A" line on the plasticity chart.
FINE GRAINED SOILS
General. A soil is classified as fine-grained if more than 50 percent of a representative
sample of the material passes the No. 200 sieve.
ML and MH Groups. These groups comprise inorganic silts (ML) and elastic silts (MH)
having either low (L) or high (H) liquid limits, respectively. ML soils have a liquid limit of
less than 50 while MH soils have a liquid limit of 50 and greater. Silts and elastic silts can
also contain varying amounts of sand and gravel. Also included in this group are loess
sediments and rock flours.
CL and CH Groups. These groups comprise low plasticity (lean) clays (CL) and medium
to high plasticity (fat) clays (CH) having either low (L) or high (H) liquid limits, respectively.
CL soils have a liquid limit of less than 50 while CH soils have a liquid limit of 50 and
greater. The low plasticity clays can also be sandy clays or silty clays. The moderate to
high plasticity clays can also be sandy clays and include some volcanic clays.
GFR
OL and OH Groups. These groups comprise organic silts and clays. The soils are
characterized by the presence of organic odor and/or dark color. The OL and OH soils
are differentiated by determining and comparing their liquid limit values before and after
oven drying representative soil samples.
HIGHLY ORGANIC SOILS
The highly organic soils are usually very soft and compressible and have undesirable
construction characteristics. Particles of leaves, grasses, branches, or other fibrous
vegetative matter are common components of these soils. They are not subdivided and
are classified into one group with the symbol PT. Peat humus and swamp soils with a
highly organic texture are typical soils of the group.
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