HomeMy WebLinkAboutSoil Testing Allterra reports 9.8.2021Geotechnical Services – 3-Level Custom Home 8024 South Ocean Drive, Jensen Beach, FL
20 August 2021 21 - 179
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20 August 2021
Phoenix Custom Homes
1760 Jog Road, Suite 120
West Palm Beach, FL 33411
Subject: Report of Geotechnical Services – 3-Level Custom Home
8024 South Ocean Drive, Diamond Sands Lot 17, Jensen Beach, Florida
Allterra Engineering & Testing respectfully submits this report of geotechnical services for the
subject project. Allterra’s services have been performed to meet certain requirements of chapter
18 of the 2020 Florida Building Code and local amendments. This report is Allterra’s instrument-of-
service provided for sole reliance and use by Phoenix Custom Homes. Third parties may read this
report for information purposes only.
Project and Scope
Project Information. The project is a 3-level custom home and its associated swimming pool
proposed for construction upon the subject property. The property is bounded on the west by
South Ocean Drive, on the east by the Atlantic Ocean, and on the north and south by other
residential properties. The project is designed for supported upon a foundation of grade beams
and piles.
Scope and Constraints. Allterra was tasked with performing soil-test borings to characterize
subsurface conditions and providing recommendations for foundation design (pile length, diameter,
and capacity). Specific information on design storm parameters have not been provided at this
time. These parameters are provided by the project coastal engineer and typically include
information such as breaking wave-crest elevations, eroded-grad elevation, wave impact force and
elevation of force resultant, debris impact force and elevation of force resultant, etc.
Field Work
Allterra mobilized personnel and equipment to the project site on 1 July 2021. At that time access
paths across the site had been cleared by Client. Allterra performed two soil-test borings at
locations marked by Client. Penetration testing was performed in the soil-test borings by driving a
2-inch diameter steel sampler with blows of a 140-pound hammer free-falling 30 inches. Copies of
the boring logs are attached to this report for the reader’s reference.
Findings
Subsurface Profile. Allterra encountered similar conditions at each boring location. The
conceptual subsurface profile is described as:
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Geotechnical Services – 3-Level Custom Home 8024 South Ocean Drive, Jensen Beach, FL
20 August 2021 21 - 179
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• Stratum 1a – loose to firm, brown, fine sand from surface grade to approximately 3 to 4
feet below grade underlain by
• Stratum 1b – very-firm, tan, sand-and-shell to approximately 9 feet below grade,
underlain by
• Stratum 1c – dense to very-dense, tan to gray, sand-and-shell to approximately 32 feet
below grade
• Stratum 2 – soft, silt with trace of shell to approximately 37 feet below grade, underlain by
• Stratum 3 – very-dense, gray, fine sand to approximately 41 feet below grade, underlain
by
• Stratum 4-- soft, silt to approximately 47 feet below grade, underlain by
• Stratum 5 – very-firm, gray, fine sand with trace of silt and shell to 50 feet below grade.
Groundwater. Groundwater was encountered at approximately 5½ feet below surface grade at the
time of the borings at the time of Allterra’s borings. The depth to groundwater may vary at other
times due to changes in hydrologic conditions.
Conclusions
For ocean-front properties, the design of piles (material strength, embedment length, diameter) is
primarily a function of allowable lateral displacement, and wave-impact and debris-impact forces,
and grade erosion and scour due to the design storm event. The estimated characteristics of the
design storm event have not been provided to Allterra. The following soil properties are
presented for reference by other designers who may have the design-storm information.
Stratum ϒ’ Φ SU ka kp
1a 55 PCF 30° 0 0.33 3.00
1b 60 PCF 35° 0 0.27 3.69
1c 70 PCF 40° 0 0.22 4.60
2 58 PCF 0 1.88 psi (270 PSF) γsatz – Su γsatz + Su
3 80 PCF 45° 0.17 5.82
4 58 PCF 0 1.88 psi (270 PSF) γsatz – Su γsatz + Su
5 60 PCF 35° 0 0.27 3.69
Notes: ϒ’ = effective unit weight. Φ = angle of internal friction. SU = undrained shear resistance.
Lateral earth pressure coefficients, ka = active, kp = passive.
PCF = pounds per cubic foot. PSF = pounds per square foot.
Lateral earth pressure for cohesive soil, pa = γsatz – Su, pp= γsatz + Su
Recommendations
Building-Pad Preparation. The building pad is defined as the footprint of construction plus 5 feet in
all accessible directions. Allterra recommends:
1. Strip topsoil and vegetation (including roots) from building pad and properly waste.
2. Thoroughly wet the exposed surface and allow it to drain to optimum moisture.
3. Mechanically compact exposed surface to at-least 95 percent of maximum-dry-density as
determined by the Modified-Proctor compaction test (ASTM D-1557 / AASHTO T-180).
4. Engage Allterra to perform probe-rod and field density tests on the prepared subgrade
to verify compaction standards are achieved.
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Geotechnical Services – 3-Level Custom Home 8024 South Ocean Drive, Jensen Beach, FL
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5. Place fill, where needed to achieve construction-ready grades, in thin lifts and compact (at or
near optimum moisture) to at-least 95 percent of maximum-dry-density as determined by the
Modified-Proctor compaction test (ASTM D-1557 / AASHTO T-180). Lift thickness will depend
upon methods and equipment employed to achieve the target densities.
6. Engage Allterra to perform probe-rod and field density tests on each 2-foot rise in fill
height to verify compaction standards are achieved.
7. Once the building pad is prepared, the contractor shall maintain its condition to prevent erosion
or other degradation through the placement of subsequent work.
Pile Installation and Materials. Piles shall be formed with minimum 4000 PSI grout placed under
pressure as the auger is progressively withdrawn from the borehole. Piles shall be reinforced with
five and seven full-depth number-5 steel bars, respectively, for 14- and 16-inch-diameter auger-
cast piles. Ties shall be formed with number-3 bars spaced 16 inches. The structural engineer
shall determine the number and distribution of piles considering structural loads and geometry.
Piles shall be spaced at-least 3 diameters center-to-center to avoid group effect on stress
distribution in the bearing stratum.
Pile-Installation Monitoring. Engage Allterra to monitor installation of piles. For auger-cast piles,
monitoring shall include:
1. Check pile layout for conformance to design foundation plan.
2. Observe field trial and calculate gout-pump factor.
3. Observe drilling of pile to verify target depths are achieved.
4. Observe grouting of pile bore to verify acceptable grout return.
5. Sample grout for compressive-strength testing.
6. Observe installation of reinforcing steel to verify full-depth penetration.
7. Test grout specimens to verify design compressive strength is achieved.
8. Calculate grout factors and summarize installation data for each pile.
9. Prepare report of work acceptance signed and sealed by Professional Engineer.
Qualification
Allterra has based its conclusions and recommendations upon certain client-provided information
and interpretation of data obtained at discrete points within the limits of exploration. It is possible
that conditions may vary between boring locations or beyond the limits of the boring array. Project
designs may also change. If additional information about the project or site is discovered that does
not appear to conform to the conditions presented in this report, Allterra reserves the right to
review the new information and modify its conclusions and/or recommendations where warranted.
Yours truly,
Allterra Engineering & Testing
Certificate of Authorization 9139
Wendell K. Rodgers, PE 55960
Principal Engineer
This item has been digitally signed
and sealed by Wendell K. Rodgers,
P.E. on the date adjacent to the seal.
Printed copies of this document are
not considered signed and sealed and
the signature must be verified on
electronic copies.
DocuSign Envelope ID: F02D1DC4-DD2E-4E46-9CEE-DDA92B5671F9
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PROJECT Diamond Sands - Plat No. 2 - LOT #17 - 8024 SOUTH OCEAN DRIVE - Jensen Beach, Fl
LOCATION B-1 (Approximate)
PROPOSED THREE-STORY CUSTOM RESIDENCE
BORING NO. 1
0'-4' Brown Fine Sand
4'-15' Tan Fine Sand, and shell (fragmented)
18'-20' Tan Fine Sand, trace of shell (fragmented)
23'-25' Grey Fine Sand, some shell (fragmented)
28'-30' Tan Fine Sand, and shell (fragmented)
33'-35' Silt, some shell
38'-39' Grey Fine Sand
39'- Refusal
43'-45' Silt
48'-50' Grey Fine Sand, trace of silt
CLIENT Phoenix Custom Homes JOB NO. 21-179
DRILLER TM/ZS/KG/MS WATER TABLE 5.5' 7/1/21
TEST DATA In general accordance with ASTM D-1586
DEPTH DESCRIPTION OF MATERIAL Sampl e
Blows
Per Foot
No
.
D E P T H
DATE
These Soil Boring Tests are Representative of and Apply to the Exact Location and Depth of the Boring.
AUTHORIZATION FOR PUBLICATION OF STATEMENTS, CONCLUSIONS OR EXTRACTS FROM
OR REGARDING OUR REPORTS IS RESERVED PENDING OUR WRITTEN APPROVAL.
A L L T E R R A
E N G I N E E R I N G & T E S T I N G
ENGIN 3 8 6 6 P R O S P E C T A V E N U E • S U I T E 9 • W E S T P A L M B E A C H , F L O R I D A 3 3 4 0 4 • ( 5 6 1 ) 8 8 1 -1 9 3 9
DocuSign Envelope ID: F02D1DC4-DD2E-4E46-9CEE-DDA92B5671F9
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PROJECT Diamond Sands - Plat No. 2 - LOT #17 - 8024 SOUTH OCEAN DRIVE - Jensen Beach, Fl
LOCATION B-2 (Approximate)
PROPOSED THREE-STORY CUSTOM RESIDENCE
BORING NO. 2
0'-3' Brown Fine Sand
3'-15' Tan Fine Sand, and shell (fragmented)
18'-20' Tan Fine Sand, trace of shell (fragmented)
23'-25' Grey Fine Sand, trace of shell (fragmented)
28'-30' Tan Fine Sand, and shell (fragmented)
33'-35' Silt, trace of shell
38'-40' Grey Fine Sand
43'-45' Silt
48'-50' Grey Fine Sand, trace of silt to Grey Fine Sand, trace of shell
(fragmented)
CLIENT Phoenix Custom Homes JOB NO. 21-179
DRILLER TM/ZS/KG/MS WATER TABLE 5' 7/1/21
TEST DATA In general accordance with ASTM D-1586
DEPTH DESCRIPTION OF MATERIAL Sampl e
Blows
Per Foot
No
.
D E P T H
DATE
These Soil Boring Tests are Representative of and Apply to the Exact Location and Depth of the Boring.
AUTHORIZATION FOR PUBLICATION OF STATEMENTS, CONCLUSIONS OR EXTRACTS FROM
OR REGARDING OUR REPORTS IS RESERVED PENDING OUR WRITTEN APPROVAL.
A L L T E R R A
E N G I N E E R I N G & T E S T I N G
ENGIN 3 8 6 6 P R O S P E C T A V E N U E • S U I T E 9 • W E S T P A L M B E A C H , F L O R I D A 3 3 4 0 4 • ( 5 6 1 ) 8 8 1 -1 9 3 9
DocuSign Envelope ID: F02D1DC4-DD2E-4E46-9CEE-DDA92B5671F9