1892 SEA OATS DR RES23-0008 Turner - Geotechnical Engineering Report REV 3-2-23
ECS Florida, LLC
Geotechnical Engineering Report
Sea Oats Drive Lot
1892 Sea Oats Drive
Atlantic Beach, Florida
ECS Project Number 35:32515
December 27, 2021
By Toni Gindlesperger at 11:49 am, Mar 02, 2023By Mike Jones at 2:47 pm, Mar 10, 2023
11554 Davis Creek Court, Jacksonville, FL 32256 T: 904-880-0960 F: 904-880-0970 ecslimited.com
ECS Capitol Services, PLLC ECS Florida, LLC ECS Mid-Atlantic, LLC ECS Midwest, LLC ECS Southeast, LLP ECS Southwest, LLP
December 27, 2021
Mr. Kyle Turner
1815 Kings Court
Jacksonville Beach, Florida 32250
ECS Project No. 35:32515
Client ID: TJ33
Reference: Geotechnical Engineering Report
Sea Oats Drive Lot
1892 Sea Oats Drive
Atlantic Beach, Florida
Dear Mr. Turner:
ECS Florida, LLC. (ECS) has completed the subsurface exploration and geotechnical engineering
analyses for the above-referenced project. Our services were performed in general accordance with
our agreed to scope of work. This report presents our understanding of the geotechnical aspects of
the project along with the results of the field exploration conducted, and our design and construction
recommendations.
It has been our pleasure to be of service to you during the design phase of this project. We would
appreciate the opportunity to remain involved during the continuation of the design phase, and we
would like to provide our services during construction phase operations as well to verify the
assumptions of subsurface conditions made for this report. Should you have any questions concerning
the information contained in this report, or if we can be of further assistance to you, please contact
us.
Respectfully submitted,
ECS Florida, LLC.
Chris Egan, P.E. Robert W. Clark, P.E.
Associate Principal Engineer Senior Project Engineer
Registered, Florida No. 79645 Registered Florida No. 52210
Cegan@ecslimited.com Rwclark@ecslimited.com
Robert W. Clark, State of Florida Professional
Engineer, License No. 52210 This item has been digitally signed and sealed by Robert W. Clark on the date indicated here Printed copies of this document are not considered Signed and sealed and the signature must be verified On any electronic copies
Sea Oats Drive Lot December 27, 2021
ECS Project No. 35:32515 Page i
TABLE OF CONTENTS
EXECUTIVE SUMMARY ............................................................................................................. 1
1.0 INTRODUCTION .................................................................................................................. 2
2.0 PROJECT INFORMATION ..................................................................................................... 2
2.1 Project Location/Current Site Use .......................................................................................... 2
2.2 Proposed Construction ........................................................................................................... 3
3.0 FIELD EXPLORATION ........................................................................................................... 4
3.1 Subsurface Characterization .................................................................................................. 4
3.2 Groundwater Observations .................................................................................................... 4
3.2.1 Encountered Groundwater ........................................................................................... 4
3.2.2 Estimated Seasonal High Groundwater ........................................................................ 4
3.3 Visual Classification ................................................................................................................ 5
4.0 DESIGN RECOMMENDATIONS ............................................................................................. 5
4.1 Foundations ............................................................................................................................ 5
4.2 Slabs On Grade ....................................................................................................................... 6
5.0 SITE CONSTRUCTION RECOMMENDATIONS ......................................................................... 6
5.1 Subgrade Preparation ............................................................................................................ 6
5.1.1 Stripping and Grubbing ................................................................................................. 6
5.1.2 Proofrolling ................................................................................................................... 6
5.1.3 Temporary Groundwater Control ................................................................................. 7
5.1.4 Subgrade Compaction .................................................................................................. 7
5.2 Earthwork Operations ............................................................................................................ 7
5.2.1 Structural Backfill and Fill Soils ..................................................................................... 7
5.2.2 Foundation Areas .......................................................................................................... 8
5.3 General Construction Considerations .................................................................................... 8
6.0 CLOSING ............................................................................................................................. 9
APPENDICES
Appendix A Drawings & Reports
Figure 1 - Site Location Diagram
Figure 2 - Field Exploration Diagram
Figure 3 - Generalized Subsurface Profiles
Appendix B Field Operations
Reference Notes for Boring Logs
Subsurface Exploration Procedure: Standard Penetration Testing (SPT)
Boring Logs
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ECS Project No. 35:32515 Page 1
EXECUTIVE SUMMARY
This Executive Summary is intended as a very brief overview of the primary geotechnical conditions that
are expected to affect design and construction. Information gleaned from the Executive Summary should
not be utilized in lieu of reading the entire geotechnical report.
Based on the results of our exploration, we consider the subsurface conditions at the site
adaptable for support of the proposed structures on a properly designed conventional shallow
foundation system with a maximum allowable bearing pressure of 2,500 psf. Provided the site
preparation and earthwork construction recommendations outlined in Section 5.0 of this report
are performed, the parameters presented in Section 4.0 of this report may be used for foundation
design.
The borings encountered groundwater at a depth of 5 feet below the existing ground surface at
the time of our exploration. Groundwater control will probably not be necessary in order to
compact the existing soils and install shallow foundations. However, temporary groundwater
control measures may be required for deeper excavations, such as those typically required to
install utilities.
We recommend that ECS be provided the opportunity to review the foundation plans and
earthwork specifications to verify that our recommendations have been properly interpreted and
implemented. ECS should also be retained to perform the construction materials testing and
observations required for this project, to verify that our recommendations have been
implemented.
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ECS Project No. 35:32515 Page 2
1.0 INTRODUCTION
The purpose of this study was to provide geotechnical information for the design of foundations for the
single-family residential structure. The recommendations developed for this report are based on project
information supplied by you.
Our services were provided in accordance with our Proposal No. 18670-GP, dated December 10, 2021, as
authorized by you, which includes our Terms and Conditions of Service.
This report contains the procedures and results of our subsurface exploration program, review of existing
site conditions, engineering analyses, and recommendations for the design and construction of the
project.
The report includes the following items:
A brief review and description of our field procedures and the results of testing conducted.
A review of surface topographical features and site conditions.
A review of area and site geologic conditions.
A review of subsurface soil stratigraphy with pertinent available physical properties.
Final copies of our soil boring logs.
Recommendations for foundation design.
Evaluation and recommendations relative to groundwater control.
Recommendations for site preparation and construction of compacted fills, including an
evaluation of on-site soils for use as compacted fills.
2.0 PROJECT INFORMATION
2.1 PROJECT LOCATION/CURRENT SITE USE
The project site is located west of Sea Oats Drive south of the intersection of 19th Street in Atlantic Beach,
Duval County, Florida. The site is bordered to the north, south and west by single-family residential
development, and to the east by a paved road. The general site location is shown on Figure 1 in Appendix
A.
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ECS Project No. 35:32515 Page 3
Figure 2.1.1. Site Location
At the time of our exploration, there was an existing residential structure on the site with surrounding
landscaped and hardscaped areas. A site survey was not available to our office at the time of this report
preparation. However, based on publicly available information, we understand that the site is generally
level. Surface water was not observed near planned structural areas at the time of our exploration.
2.2 PROPOSED CONSTRUCTION
The following information explains our understanding of the planned development including proposed
buildings and related infrastructure.
SUBJECT DESIGN INFORMATION / ASSUMPTIONS
# of Stories 1 to 3 stories above grade
Usage Residential
Framing Reinforced concrete block or wood with interior columns
Column Loads(1) 40 kips (Full Dead and Factored Live)
Wall Loads(1) 4 kips per linear foot (klf) maximum
Floor Loads(1) 150 pounds per square foot (psf) maximum
Fill and Cut Heights Assumed a maximum of 3 feet of fill and only minor cuts, from existing
site grades
(1) If actual structural loads differ from these assumed loads ECS must be contacted immediately in order to revise building foundation
recommendations and settlement calculations, as needed.
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ECS Project No. 35:32515 Page 4
If actual project information varies from these conditions, then the recommendations in this report may
need to be re-evaluated. We should be contacted if any of the above project information is incorrect so
that we may reevaluate our recommendations.
3.0 FIELD EXPLORATION
Our exploration procedures are explained in greater detail in Appendix B including the insert titled
Subsurface Exploration Procedures. Our scope of work included drilling two Standard Penetration Test
(SPT) borings. Our borings were located using paced measurements from existing roadways and site
features and their approximate locations are shown on the Field Exploration Diagram (Figure 2) in
Appendix A.
3.1 SUBSURFACE CHARACTERIZATION
The subsurface conditions encountered were generally consistent with published geological mapping.
The following sections provide generalized characterizations of the soil strata. Please refer to the boring
logs in Appendix B.
Typical Depth (ft) Stratum Description From To
Existing
Ground
Surface
0.5 -1 n/a Topsoil
0.5 - 1 6 I Very loose to Loose Fine SAND (SP)
6 20 II Medium Dense to Very Dense Fine SAND (SP)
A graphical presentation of the subsurface conditions is shown on the Generalized Subsurface Profiles
included in Appendix A.
3.2 GROUNDWATER OBSERVATIONS
3.2.1 Encountered Groundwater
Water levels were measured during our field exploration and are presented in our boring logs in Appendix
B. Groundwater depths measured at the time of drilling were 5 feet below the ground surface. Variations
in the long-term water table may occur as a result of changes in precipitation, evaporation, surface water
runoff, construction activities, and other factors.
3.2.2 Estimated Seasonal High Groundwater
The normal seasonal high groundwater level is affected by a number of factors. The drainage
characteristics of the soils, land surface elevation, relief points such as drainage ditches, lakes, rivers,
swamp areas, etc., and distance to relief points are some of the more important factors influencing the
seasonal high groundwater level.
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ECS Project No. 35:32515 Page 5
Based on our interpretation of the site conditions, including the boring logs and Web Soil Survey, we
estimate the normal seasonal high groundwater level at the boring locations to be approximately 2½ feet
above the groundwater levels measured at the time of our field exploration. It is possible that
groundwater levels may exceed the estimated normal seasonal high groundwater level as a result of
significant or prolonged rains.
3.3 VISUAL CLASSIFICATION
Each sample was visually classified on the basis of texture and plasticity in accordance with ASTM D2488
Standard Practice for Description and Identification of Soils (Visual-Manual Procedures) and including
USCS classification symbols. After classification, the samples were grouped in the major zones noted on
the boring logs in Appendix B. The group symbols for each soil type are indicated in parentheses along
with the soil descriptions. The stratification lines between strata on the logs are approximate; in situ, the
transitions may be gradual.
4.0 DESIGN RECOMMENDATIONS
4.1 FOUNDATIONS
Provided subgrades and structural fills are prepared as recommended in this report, the proposed
structure can be supported by shallow foundations including column footings and continuous wall
footings. We recommend the foundation design use the following parameters:
Design Parameter Column Footing Wall Footing
Minimum Width 24 inches 18 inches
Minimum Footing Embedment Depth (below
slab or finished grade) 12 inches 12 inches
Estimated Maximum Total Settlement1 1 inch 1 inch
Estimated Maximum Differential Settlement2 Less than ½ inch
between columns Less than ½ inch over 50 feet
Maximum Net Allowable Soil Bearing Pressure3 2,500 psf
Acceptable Bearing Soil Material Medium Dense Fine Sand (SP) Stratum I or
Compacted Fill
1. Based on assumed structural loads. If final loads are different, ECS must be contacted to update foundation
recommendations and settlement calculations.
2. Based on maximum column/wall loads and variability in borings. Differential settlement can be re-evaluated
once the foundation plans are more complete.
3. Net allowable bearing pressure is the applied pressure in excess of the surrounding overburden soils above
the base of the foundation.
Depending on the final floor elevations of the building, we anticipate that most of the soils at the
foundation bearing elevation are anticipated to be suitable for support of the proposed structure, after
prepared in accordance with Section 5.0 of this report. The bearing level soils, after compaction, should
exhibit densities equivalent to 95 percent of the modified Proctor maximum dry density (ASTM D 1557)
to a depth of at least one foot below foundation bearing levels.
For turn down slabs and interior wall footings the minimum width should also be 18 inches, however the
sloped transition portion of the turn-down may be included when determining the footing width. Even
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ECS Project No. 35:32515 Page 6
though the maximum allowable soil bearing pressure may not be achieved, these width recommendations
should control the size of the foundations.
4.2 SLABS ON GRADE
The floor slabs can be constructed as a slab-on-ground, provided the site is prepared as outlined in Section
5.0. A minimum clearance of 2 feet is recommended between the estimated seasonal high groundwater
table and the bottom of the floor slab. It is recommended the floor slab bearing soils be covered with an
impervious membrane to reduce moisture entry and floor dampness. A 6-mil thick plastic membrane is
commonly used for this purpose. Care should be exercised not to tear large sections of the membrane
during placement of reinforcing steel and concrete.
Subgrade Modulus: Provided the placement of structural fill per the recommendations discussed herein,
the slab may be designed assuming a modulus of subgrade reaction, k1 of 150 pci (lbs/cu. inch). The
modulus of subgrade reaction value is based on a 1 ft by 1 ft plate load test basis.
5.0 SITE CONSTRUCTION RECOMMENDATIONS
5.1 SUBGRADE PREPARATION
5.1.1 Stripping and Grubbing
We expect that the existing structure will be razed and removed. The existing foundation system should
also be removed, and provisions should then be made to relocate interfering utilities to appropriate
locations. Underground pipes that are not properly removed or plugged may serve as conduits for
subsurface erosion, which may subsequently lead to excessive settlement of overlying structures.
Site preparation should also consist of clearing the existing vegetation and near surface organic topsoil.
The clearing/stripping operations should extend within and to a distance of at least five feet beyond the
perimeter of the proposed building areas and three feet beyond pavement areas. During grubbing
operations, roots with a diameter greater than 0.5-inch, stumps, or small roots in a concentrated state,
should be grubbed and completely removed.
5.1.2 Proofrolling
After removing unsuitable surface materials, cutting to the proposed grade, and prior to the placement
of any structural fill or other construction materials, the exposed subgrade should be evaluated by an ECS
authorized representative. The exposed subgrade should be proofrolled with previously approved
construction equipment having a minimum axle load of 10 tons (e.g. fully loaded tandem-axle dump
truck). The areas subject to proofrolling should be traversed by the equipment in two perpendicular
(orthogonal) directions with overlapping passes of the vehicle under the observation of authorized
representative. This procedure is intended to assist in identifying any localized yielding materials. In the
ev
for repair prior to the placement of any subsequent structural fill or other construction materials.
Methods of repair of unstable subgrade, such as undercutting or moisture conditioning or chemical
stabilization, should be discussed with ECS to determine the appropriate procedure with regard to the
existing conditions causing the instability. A test pit(s) may be excavated to explore the shallow
subsurface materials in the area(s) of the instability to help in determined the cause of the observed
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ECS Project No. 35:32515 Page 7
unstable materials and to assist in the evaluation of the appropriate remedial action to stabilize the
subgrade.
5.1.3 Temporary Groundwater Control
Because of the need for densification of the soils within the upper 2 feet below the stripped surface,
temporary groundwater control measures may be required if the groundwater level is within 2 feet below
the stripped and grubbed surface at the time of construction. Should groundwater control measures
become necessary, dewatering methods should be determined by the contractor. We recommend the
groundwater control measures, if necessary; remain in place until compaction of the existing soils is
completed. The dewatering method should be maintained until backfilling has reached a height of 2 feet
above the groundwater level at the time of construction. The site should be graded to direct surface water
runoff from the construction area.
5.1.4 Subgrade Compaction
Subgrade Compaction: After completing the clearing and stripping operations and installing the
temporary groundwater control measures (if required), the exposed surface should be compacted with a
vibratory drum roller having a minimum static, at-drum weight, on the order of 4 tons to 6 tons. Typically,
the material should exhibit moisture contents within ±2 percentage points of the modified Proctor
optimum moisture content (ASTM D 1557) during the compaction operations. Compaction should
continue until densities of at least 95 percent of the modified Proctor maximum dry density (ASTM D
1557) have been achieved within the upper one foot of the compacted natural soils at the site.
Should the bearing level soils experience pumping and soil strength loss during the compaction
operations, compaction work should be immediately terminated, and (1) the disturbed soils should be
removed and backfilled with compacted structural fill, or (2) the excess moisture content within the
disturbed soils should be allowed to dissipate before recompacting.
Care should be exercised to avoid damaging any nearby structures while the compaction operation is
underway. Prior to commencing compaction, occupants of adjacent structures should be notified, and the
existing conditions of the structures should be documented with photographs and survey (if deemed
necessary). Compaction should cease if deemed detrimental to adjacent structures, and ECS should be
contacted immediately. We recommend the vibratory roller remain a minimum of 50 feet from existing
structures. Within this zone, use of a track-mounted bulldozer, or a vibratory roller operating in the static
mode, is recommended.
5.2 EARTHWORK OPERATIONS
5.2.1 Structural Backfill and Fill Soils
Structural fill is defined as a non-plastic, inorganic, granular soil having less than 15 percent material
passing the No. 200 mesh sieve and containing less than 4 percent organic material. The near surface fine
sands, without roots, as encountered in the borings, are suitable as fill materials and, with proper moisture
control, should densify using conventional compaction methods. Soils with more than 10 to 12 percent
passing the No. 200 sieve will be more difficult to compact, due to their nature to retain soil moisture,
and may require drying.
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ECS Project No. 35:32515 Page 8
Structural Fill Compaction Requirements: Materials satisfactory for use as structural fill should consist of
soils with the following compaction requirements.
STRUCTURAL FILL COMPACTION REQUIREMENTS
Subject Requirement
Compaction Standard Modified Proctor, ASTM D1557
Required Compaction 95% of Max. Dry Density (general structural fill)
Loose Thickness prior
to compaction
12 inches if vibratory drum roller compaction equipment is used
8 inches if vibratory drum roller is used in static mode
8 inches if track-mounted compaction equipment is used
6 inches if hand-held compaction equipment is used
Fill materials should not be placed on excessively wet soils. Excessively wet soils should be moisture
conditioned, which may include scarifying and aerating. Proper drainage should be maintained during the
earthwork phases of construction in an attempt to prevent ponding of water which has a tendency to
degrade subgrade soils. The contractor should minimize dusting or implement dust control measures, as
required.
We recommend that the grading contractor have equipment on site during earthwork for both drying and
wetting fill soils. Moisture control may be difficult during extended periods of rain. The control of
moisture content of soils containing more than 10% fines may be difficult when these soils become wet.
Further, such soils are easily degraded by construction traffic when the moisture content is elevated.
5.2.2 Foundation Areas
After satisfactory placement and compaction of the required structural fill, the foundation areas may be
excavated to the planned bearing levels. The foundation bearing level soils, after compaction, should
exhibit densities equivalent to at least 95 percent of the modified Proctor maximum dry density (ASTM D
1557) to a depth of one foot below the bearing level. For confined areas, such as the footing excavations,
any compactive effort should be provided by a lightweight vibratory sled or roller having a total weight
on the order of 500 to 2,000 pounds.
5.3 GENERAL CONSTRUCTION CONSIDERATIONS
Moisture Conditioning: We anticipate that typical moisture conditioning for soils in this area should be
anticipated. The sandy surface soils may require wetting during dry periods or periods of high heat.
Drying of soils containing more than 10% fines or excavated from below the water table may be required
to be within ±2 percentage points of the modified Proctor optimum moisture content (ASTM D 1557).
Subgrade Protection: Measures should also be taken to limit site disturbance, especially from rubber-
tired heavy construction equipment, and to control and remove surface water from development areas,
including structural and pavement areas. It would be advisable to designate a haul road and construction
staging area to limit the areas of disturbance and to prevent construction traffic from excessively
degrading sensitive subgrade soils and existing pavement areas. Haul roads and construction staging areas
could be covered with excess depths of aggregate to protect those subgrades. The aggregate can later be
removed and can likely be used in pavement areas.
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Surface Drainage: Surface drainage conditions should be properly maintained. Surface water should be
directed away from the construction area, and the work area should be sloped away from the construction
area at a gradient of at least 1 percent or greater to reduce the potential of ponding water and the
subsequent saturation of the surface soils. At the end of each work day, the subgrade soils should be
sealed by rolling the surface with a smooth drum roller to limit infiltration of surface water.
Excavation Safety: All excavations and slopes should be made and maintained in accordance with OSHA
excavation safety standards. The contractor is solely responsible for designing and constructing stable,
temporary excavations and slopes and should shore, slope, or bench the sides of the excavations and
slopes as required to maintain stability of both the excavation sides
responsible person, as defined in 29 CFR Part 1926, should evaluate the soil exposed in the excavations
excavation depth, including utility trench excavation depth, exceed those specified in local, state, and
federal safety regulations. ECS is providing this information solely as a service to our client. ECS is not
assuming responsibility for construction site safety or the cont
being implied and should not be inferred.
Erosion Control: The surface soils may be erodible. Therefore, the Contractor should provide and maintain
good site drainage during earthwork operations to maintain the integrity of the surface soils. All erosion
and sedimentation controls should be in accordance with sound engineering practices and local
requirements.
6.0 CLOSING
Our geotechnical exploration has been performed, our findings presented, and our recommendations
prepared, in accordance with generally accepted geotechnical engineering principles and practices. ECS is
not responsible for any independent conclusions, interpretation, opinions, or recommendations made by
others based on the data contained in this report.
Our scope of services was intended to evaluate the soil conditions within the zone of soil influenced by
the foundation system. Our scope of services does not address geologic conditions, such as sinkholes or
soil conditions existing below the depth of the soil borings.
If any of the project description information discussed in this report is inaccurate, either due to our
interpretation of the documents provided or site or design changes that may occur later, ECS should be
contacted immediately in order that we can review the report in light of the changes and provide
additional or alternate recommendations as may be required to reflect the proposed construction.
We recommend that ECS be retained
work so that we may ascertain consistency of those plans/specifications with the intent of the
geotechnical report.
Field observations, monitoring, and quality assurance testing during earthwork and foundation
installation are an extension of and integral to the geotechnical design recommendation. We recommend
that the owner retain these quality assurance services and that ECS be retained to continue our
involvement throughout these critical phases of construction to provide general consultation as issues
arise.
ECS is not responsible for the conclusions, opinions, or recommendations of others based on the data in
this report.
APPENDIX A Diagrams & Reports
Figure 1 - Site Location Diagram
Figure 2 - Field Exploration Diagram
Figure 3 Generalized Subsurface Profiles
APPENDIX B Field Operations
Reference Notes for Boring Logs
Subsurface Exploration Procedure: Standard Penetration Testing (SPT)
Boring Logs