ECS – FLORIDA, LLC
Geotechnical  Construction Materials  Environmental  Facilities
January 26, 2009
Mr. Rich Armstrong
St. Joseph’s Women’s Hospital
c/o Mr. Chet Emmett
HKS, Inc.
1919 McKinney Avenue
Dallas, Texas 75201
ECS Job No.: 25-3110
Reference:
Report of Subsurface Exploration and Geotechnical Engineering Analysis, St.
Joseph’s Women’s Hospital Bed Tower Addition, Florida
Dear Mr. Armstrong:
As authorized by acceptance of our proposal ECS 24-5826-GP, dated December 2, 2008, ECSFlorida, LLC (ECS) has completed the subsurface exploration and conducted geotechnical
engineering analyses for the proposed St. Joseph’s Women’s Hospital Bed Tower Addition,
located in Tampa, Florida. Our attached report includes the results of our subsurface exploration
program, laboratory testing program, and geotechnical engineering analysis.
We understand the project will consist of a 5-story, 115,000 square feet hospital bed tower
addition with no allowance for future floors. Maximum column loads for the bed tower are
estimated to be 960 kips, with 80 percent of the load from dead load. Allowable differential
settlement between the proposed and existing buildings will be 0.5 inch. The planned final
ground floor elevation for the hospital is 33.65 feet above mean sea level.
This report provides recommendations on soil bearing pressures, foundation settlement estimates,
placement and compaction of new fills, drainage, construction procedures, and other factors that
may influence design and construction at the site.
This geotechnical engineering study includes an evaluation of the subsurface soils and
groundwater conditions of the site and general area, as described in the scope of services
identified in our proposal. No other considerations or additional issues were investigated,
requested or proposed during this evaluation.
The conclusions and recommendations presented within this report are based upon a reasonable
level of investigation within normal bounds and standards of professional practice for a site in
this particular geographic and geologic setting. This report has been prepared to aid in the
evaluation of this site and to assist the Owner and Engineer in the implementation of the project.
The report scope is limited to the specific project and location described, and the project
description represents our understanding of the significant aspects relevant to soil and foundation
2000 Avenue P, Suite 3, West Palm Beach, FL 33404 (561) 840-3667 FAX (561) 840-3668
www.ecslimited.com
ECS Carolinas, LLP  ECS Florida, LLC  ECS Illinois, LLC  ECS Mid-Atlantic, LLC  ECS Southeast, LLC  ECS Texas, LLP
St. Joseph’s Women’s Hospital Bed Tower Addition
ECS Job No.: 24-3110
Cover Letter
January 26, 2009
Page 2
characteristics.
Observations, conclusions and recommendations pertaining to geotechnical conditions at the
subject site are necessarily limited to conditions observed, and/or materials reviewed at the time
this study was undertaken. No warranty, express or implied, is made with regard to the
conclusions and recommendations presented within this report. This report is provided for the
exclusive use of HKS, Inc, and their successors or assigns. This report is not intended to be used
or relied upon in connection with other projects or by other unidentified third parties. The use of
this report by any undesignated third party or parties will be at such party's sole risk and ECS
disclaims liability for any such third party use or reliance.
We appreciate this opportunity to be of service to HKS, Inc, on this project. If you have any
questions regarding the information and recommendations contained in the accompanying report,
or if we may be of further assistance to you in any way during planning or construction of this
project, please contact us.
Respectfully,
ECS-FLORIDA, LLC
Florida Certificate of Authorization No. 26152
Sunil Sundaram
Project Manager
Anthony J. Fiorillo, P.E.
Principal Engineer
P.E. 58405
I:\Projects\3000-3999\3100-3199\3110 St. Joseph's Women's Hospital GEO\GEOTECH REPORT.doc
TABLE OF CONTENTS
PAGE
PROJECT OVERVIEW
Project Location and Proposed Construction
Scope of Work
Purposes of Exploration
EXPLORATION PROCEDURES
Subsurface Exploration Procedures
Laboratory Testing Program
Particle Size Analysis, Modified Proctor and LBR
1
1
1
2
3
3
4
4
EXPLORATION RESULTS
5
Current Site Conditions
Regional Geology
Soil Conditions
Groundwater Observations
5
5
5
6
ANALYSES AND RECOMMENDATIONS
Shallow Foundations
Mat Foundations
Deep Foundations
Floor Slab Design
Earthwork Operations
Fill Placement
Retaining Walls
Pavement Considerations
General
Asphalt (Flexible) Pavements
Layer Components
Stabilized Subgrade
Base Course
Surface Course
Effects of Groundwater
Landscape Drains
Construction Traffic
Concrete (Rigid) Pavements
Construction Considerations
Closing
APPENDIX
7
7
7
8
9
9
11
12
13
13
14
14
15
15
16
16
16
16
17
18
18
20
St. Joseph’s Women’s Hospital Bed Tower Addition
ECS Job No.: 24-3110
January 26, 2009
Page 1 of 19
PROJECT OVERVIEW
Project Location and Proposed Construction
The proposed St. Joseph’s Women’s Hospital Bed Tower site is located on the southeast corner
of the intersection of Martin Luther King Boulevard and N. MacDill Avenue in Tampa, Florida.
We understand the project will consist of a 5-story, 115,000 square feet hospital bed tower
addition with no allowance for future floors. Maximum column loads for the bed tower are
estimated to be 960 kips, with 85 percent of the load from dead load. Allowable differential
settlement between the proposed and existing buildings will be 0.5 inches. The planned final
ground floor elevation for the hospital is 33.65 feet above mean sea level.
Scope of Work
The conclusions and recommendations contained in this report are based on our field subsurface
explorations, laboratory testing, and review of available geologic and/or geotechnical data. The
recent subsurface exploration program included 5 soil borings, extended to depths of 6 to 75 feet
below existing land surface (bls). Pressuremeter testing was performed at various depths in 2
borings using a CPT (Cone Penetration Test) rig. Additionally two (2) CPT borings were
performed to depths of 25 to 30 feet in proximity to the pressuremeter tests. Laboratory tests
were performed on selected soil samples to identify the soils and to assist in determination of the
soil properties. We have also visited the site to conduct a site reconnaissance.
The boring locations for the proposed St. Joseph’s Women’s Hospital Bed Tower were selected
and located in the field by ECS. Consider the indicated locations and depths to be approximate.
Our layout crew located the borings based upon the site plan provided, along with measuring
distances and relationships to obvious landmarks. The Boring Location Plan is included in the
Appendix.
Our investigation was confined to the zone of soil likely to be stressed by the proposed
construction. Our work did not address the potential for surface expression of deep geological
conditions, such as sinkhole development related to karst activity. This evaluation requires a
more extensive range of field services than performed in this study. We will be pleased to
conduct an investigation to evaluate the probable effect of the regional geology upon the
proposed construction, if you desire.
This report presents an evaluation of site conditions on the basis of traditional geotechnical
procedures for site characterization. The recovered samples were not examined, either visually
or analytically, for chemical composition or environmental hazards. If requested, ECS would be
pleased to perform these services.
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January 26, 2009
Page 2 of 19
Purposes of Exploration
The purposes of the exploration were to explore the soil and groundwater conditions at the site
and to develop engineering recommendations to guide the Geotechnical design and construction
of the current project. We accomplished these purposes by:
1.
Drilling borings to explore the subsurface soil and groundwater conditions,
2.
Performing laboratory tests on selected representative soil samples from the test
borings to evaluate pertinent engineering properties and,
3.
Evaluating the field and laboratory test results to develop appropriate engineering
recommendations.
St. Joseph’s Women’s Hospital Bed Tower Addition
ECS Job No.: 24-3110
January 26, 2009
Page 3 of 19
EXPLORATION PROCEDURES
Subsurface Exploration Procedures
The soil borings were performed with a truck-mounted drill rig utilizing mud rotary drilling
methods to advance the boreholes. Drilling fluid was used in this process.
Representative soil samples were obtained by means of the split-barrel sampling procedure. The
number of blows required to drive the sampler through a 12-inch interval with a 140 pound
manual drop safety hammer is termed the Standard Penetration Test (SPT) value, or "N" value,
and is indicated for each sample on the boring logs. This value can be used as a quanitative
indication of the in-place relative density of non-cohesive soils. In a less reliable way, it also
indicates the consistency of cohesive soils. This indication is qualitative, since many factors can
significantly affect the standard penetration resistance value and prevent a direct correlation
between drill crews, drill rigs, drilling procedures, and hammer-rod-sampler assemblies.
A field log of the soils encountered in each boring was maintained by the drill crew. After
recovery, each sample was removed from the sampler and visually classified. Representative
portions of each sample were then sealed and delivered to ECS’ laboratory for further visual
examination and laboratory testing.
Pressuremeter testing was also performed, which is used to provide a direct measurement of the
relative strength of the soil lying at and below the planned bottom of footing elevations at this
site. The pressuremeter is a down borehole, stress volumetric strain device. Because it is
performed in-situ, it provides a direct measurement of the soil.
The pressuremeter provides two values that are fundamental in evaluating bearing capacity and
settlement. First, it develops a modulus of elasticity, commonly referred to as the “pressuremeter
modulus”. It also allows us to develop a limit pressure, which gives an indication as to the
ultimate strength of the soil. More detailed pressuremeter data collected onsite is included in the
Pressuremeter Logs within the Attachments of this report.
Cone penetrometer testing (CPT) is performed by advancing a standard friction mantle cone into
the soil. The pressure required to advance the cone is measured by a pressure cell attached to the
"proving ring" to determine the tip resistance. The tip resistance is referred to as the Qc-value in
units of kilograms per square centimeter. The tip resistance is an index of soil strength and
density.
St. Joseph’s Women’s Hospital Bed Tower Addition
ECS Job No.: 24-3110
January 26, 2009
Page 4 of 19
Laboratory Testing Program
Representative soil samples were selected and tested in our laboratory to confirm the field
classifications and to determine pertinent engineering properties. The laboratory testing program
included visual sample classifications, moisture content tests, washed sieve gradation tests, pH,
resistivity and organic tests. Data obtained from the laboratory tests are included on the
respective boring logs in the Appendix.
A member of ECS’ Geotechnical staff classified each soil sample on the basis of texture and
plasticity in accordance with the Unified Soil Classification System (USCS). The group symbols
for each soil type are indicated in parentheses following the soil descriptions on the boring logs.
A brief explanation of the USCS is included with this report. The Geotechnical Engineer
grouped the various soil types into the major zones noted on the boring logs. The stratification
lines designating the interfaces between earth materials on the boring logs and profiles are
approximate; in the field, the transitions may be gradual.
Particle Size Analysis, Modified Proctor and LBR
Off-site borrow material samples were not evaluated because the general contractor has not
chosen a supplier at this time. Please notify us when a borrow pit has been chosen, and ECS will
perform these services.
St. Joseph’s Women’s Hospital Bed Tower Addition
ECS Job No.: 24-3110
January 26, 2009
Page 5 of 19
EXPLORATION RESULTS
Current Site Conditions
A site visit was conducted by ECS during the drilling operation to observe existing site
conditions. The proposed site is currently used as driveway and parking areas. The boring
locations were located in the existing asphalt parking lot east of the existing four-story building.
Associated landscaped areas and curbing are present within the proposed addition area.
Regional Geology
The general hydrogeology of Hillsborough County includes the unconfined surficial aquifer of
Pleistocene to recent age. This 50 to 150 feet thick sequence of sand and clay overlies the
Miocene Hawthorne Formation, which measures approximately 0 to 250 feet in thickness in
Hillsborough County. Small quantities of water are pumped from this artesian aquifer. Below
the Hawthorn Formation are the Tampa and Suwannee Limestone. The majority of Hillsborough
County’s municipal and commercial water supply is pumped from these limestone formations.
Within the geological province including this portion of Hillsborough County, the surface of the
water table approximately conforms to the ground surface topography with groundwater drainage
in a down-slope direction towards the nearest surface water body. Surface streams typically
drain in a direction that is in accordance with the regional surface slope. Perturbations in the
surface drainage are usually due to man-induced changes in the surface topography.
Soil Conditions
Subsurface conditions within the project site were evaluated with 5 soil test borings. Borings S-1
through S-3 were drilled to depths of 75 feet below grade in the building areas; A-1 and A-2 were
drilled to 6 feet below grade in the parking areas. Additionally 2 Pressuremeter test borings (P-1
and P-2) and 2 Cone Penetration Test borings (C-1 and C-2) were performed to evaluate the
strength of the soil. The approximate boring locations are shown on the Boring Location Plan in
the Appendix. Ground surface elevations were not available at the time of drilling or submittal
of the report.
In general, borings performed encountered alternate layers of fine sand (SP), fine sand with silt
(SP-SM) and silty fine sand (SM) from the existing grade to a depth of 40 feet below grade,
followed by very dense limerock to the termination depth of 75 feet below grade. For details at
the individual boring locations, refer to the logs attached in the Appendix.
St. Joseph’s Women’s Hospital Bed Tower Addition
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January 26, 2009
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Groundwater Observations
On the basis of depth to water measurements made in the open boreholes, we estimate that the
groundwater level was about 7.5 feet below existing grade at the time of drilling. The
groundwater will fluctuate seasonally depending upon local rainfall. The rainy season in Central
Florida is normally between June and September. Based upon our site specific field data, our
review of the USDA Soils Survey of Hillsborough County, the USGS topographic map of the
area, the expected regional hydrogeology and our experience in the area, we estimate the seasonal
high groundwater levels could be on the order of 5 feet below the existing grade at the boring
locations. Variations in the location of the long-term groundwater table may occur as a result of
changes in precipitation, evaporation, surface water runoff, and other factors not immediately
apparent at the time of this exploration.
St. Joseph’s Women’s Hospital Bed Tower Addition
ECS Job No.: 24-3110
January 26, 2009
Page 7 of 19
ANALYSES AND RECOMMENDATIONS
Based on the soil conditions encountered at the anticipated foundation elevation, the results of
our pressuremeter testing program, and the anticipated maximum loading conditions (960 kips
column load), ECS recommends the following three foundation options:
Shallow Foundation
Mat Foundation
Deep Foundation
Considering all three foundation alternatives, shallow foundation is the most cost effective
option, considering our experience and understanding of the risk tolerances. Detailed discussions
of the foundation options are provided below.
Shallow Foundations
The most economical option is to use shallow foundations to support the five-story structure.
The geotechnical analyses of the field data indicate the soils expected at subgrade levels should
be suitable for a net allowable bearing pressure of 3,000 pounds per square foot (psf). The net
allowable soil bearing pressure refers to that pressure which may be transmitted to the foundation
bearing soils in excess of the final minimum surrounding overburdened pressure.
Settlement of individual footings designed in accordance to recommendations outlined above is
expected to be small and within tolerable limits for the proposed structure. Within the proposed
building addition, total allowable and differential post-construction settlements of less than ½
inch are anticipated. These settlement estimates are based on our engineering experience with
these soils and are provided to guide the structural engineer with their design.
In order to prevent disproportionately small footing sizes, we recommend that continuous
footings have a minimum width of 1½ feet and that isolated column footings have a minimum
lateral dimension of 2½ feet. The minimum dimensions recommended above help reduce the
possibility of foundation bearing failure and excessive settlement due to local shear or
"punching" action. Embedment depths should be a minimum of 24 inches.
Mat Foundations
The second option is using a mat foundation to support the five-story structure. We recommend
that the mat foundation be designed using a modulus subgrade reaction of k=125 tcf. This
modulus of subgrade reaction is based upon an equivalent 12 inch square plate load test. Caution
St. Joseph’s Women’s Hospital Bed Tower Addition
ECS Job No.: 24-3110
January 26, 2009
Page 8 of 19
should be used in determining the proper modulus of subgrade reaction to be input into any
computerized solution to determine the thickness of the mat. Specifically, the modulus of
subgrade reaction is a function of the size of the plate on which the test is based, and variations
are a direct function of the size of the plate. The equivalent modulus of subgrade reaction for the
entire mat would be significantly less than 125 tcf. However, the recommended value of 125 tsf
should be used as the design input into the mat design computer program unless the program
specifically includes assumptions different from those outlined above.
We also recommend that the mat be designed for a maximum average contact stress of 2500 psf
and maximum local contact pressure of 4,500 psf.
During the mat foundation design, there may be areas where the maximum bearing pressure
exceeds the recommended 4,500 psf. Where these conditions occur, they should be brought to
the attention of ECS. Please note that some overstress across the mat footprint may be
acceptable. We will specifically evaluate the bearing conditions based on the soil conditions in
those areas of the mat. Depending on the localized soil conditions, a higher bearing pressure may
be feasible. We recommend that the structural engineer provide us with a copy of the bearing
pressure contour plan of the mat foundation for our review. Additionally, an allowable stress
increase factor can be applied to the recommended bearing pressure for short term (wind)
loading.
The bearing capacity of the subgrade soils should be confirmed immediately prior to placement
of a gravel or concrete working mat. The soils should be observed by an experienced soils
technician working under the direct supervision of a registered professional geotechnical
engineer. Any soils which are soft or which become loosened by construction activities or water
intrusion should be removed and replaced with a gravel backfill or “lean” concrete. Proper
dewatering of the subgrade soils may be required during construction to reduce difficulties during
foundation installation. A detailed discussion of construction dewatering is included in a
subsequent section of this report.
During excavation operations, we recommend that large excavation equipment be permitted to
excavate no deeper than 1 foot above the proposed subgrade elevations. Below this level,
smaller excavation equipment or a GRADALL should be utilized for final grading which will
reduce disturbance of the subgrade. Upon completion of the excavation, an 8 inch gravel mat or
a 4 inch lean concrete mud mat should be placed as a working surface.
Deep Foundations
The third option is to support the five-story structure on a deep foundation system. Once
structural load and foundation configurations are finalized, a pile type should be chosen based
upon cost, ease, timing of construction, and quality control assurances. Based on these criteria
the three options for piles are Driven Precast Concrete Piles, Auger Displacement Piles, and
Auger Cast Piles. Based on the loading conditions, settlement criteria, and economics, ECS
St. Joseph’s Women’s Hospital Bed Tower Addition
ECS Job No.: 24-3110
January 26, 2009
Page 9 of 19
recommends using a shallow foundation system (with bearing capacity of 3,000 psf). ECS will
be glad to provide you with all the deep foundation recommendations if you decide to choose a
deep foundation option.
Floor Slab Design
According to the test borings and recommendations included in this report, soils at the lowest
floor slab subgrade should consist of medium dense sand (SP) soils, which should be suitable for
floor slab support. The subgrade should be prepared in accordance with our recommendations
outlined in the sections entitled “Earthwork Operations” and “Fill Placement”. The lowest
slabs can then be designed as slab on grade with a modulus of subgrade reaction of 200 pounds
per cubic inch (pci).
The Florida Building Code 2007 requires the use of a 6-mil (0.006 inch) polyethylene vapor
retarder, with joints lapped not less than 6 inches, beneath the floor slab to control moisture.
This will help to minimize floor dampness and moisture intrusion into the structure through the
slab. Care should be exercised during construction to prevent tearing or punching of the vapor
retarder prior to slab placement. Any tears must be repaired immediately.
Special attention should be given to the surface curing of the slabs to minimize uneven drying of
the slabs, associated cracking, and/or slab curling. Please refer to ACI 302.1R96 Guide for
Concrete Floor and Slab Construction and ASTM E 1643 Standard Practice for Installation of
Water Vapor Retarders Used in Contact with Earth or Granular Fill Under Concrete Slabs for
additional guidance on this issue.
In order to minimize the crack width of any shrinkage cracks that may develop near the surface
of the slab, we recommend mesh reinforcement, as a minimum, be included in the design of the
floor slab. For maximum effectiveness, temperature and shrinkage reinforcements in slabs on
ground should be positioned in the upper third of the slab thickness. The Wire Reinforcement
Institute recommends the mesh reinforcement be placed 2 inches below the slab surface or upper
one-third of slab thickness, whichever is closer to the surface. Adequate construction joints,
contraction joints and isolation joints should also be provided in the slab to reduce the impacts of
cracking and shrinkage. Please refer to ACI 302.1R96 Guide for Concrete Floor and Slab
Construction for additional information regarding concrete slab joint design.
Earthwork Operations
We recommend normal, good practice site preparation procedures. These procedures include
stripping the site of existing asphalt, concrete, construction debris, vegetation, topsoil, and any
other soft or unsuitable material from the proposed building areas; proofrolling the subgrade; and
backfilling to grade with engineered fill. Stripping depths on the order of 2 inches in the asphalt
St. Joseph’s Women’s Hospital Bed Tower Addition
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pavement areas and 6 to 12 inches in the landscaped areas should be anticipated. The underlying
limerock base may be left in place. Asphalt should either be recycled on/off site or disposed of
properly. As per Florida Building Code 2007 Section 1803.3 Site Grading, stripping within the
proposed structural areas should be extended at least 10 feet beyond the planned limits. A more
detailed synopsis of this work is as follows:
1.
Prior to construction, the location of existing underground utility lines within the
construction area should be established. Provisions should be made to relocate
interfering utilities to appropriate locations. It should be noted that if underground pipes
are not properly removed or plugged, they might serve as conduits for subsurface erosion
which may subsequently lead to excessive settlement of overlying structures.
2.
Strip the proposed construction limits of existing asphalt, concrete, construction debris,
vegetation, topsoil, and any other soft or unsuitable material from the proposed building
areas within and 10 feet beyond the perimeter of the proposed building and paved areas.
Expect stripping on the order of 2 inches in the asphalt pavement areas and 6 to 12 inches
in the existing landscaped areas. Somewhat deeper stripping or undercutting may be
required in isolated areas to the root system of trees. The underlying limerock base may
be left in place and the topsoil may be reused in landscaped areas.
3.
The groundwater level was encountered at a depth of 7.5 feet below existing land surface
(bls). Seasonal high groundwater levels could occur at a depth of 5 feet bls over most of
the site. The need for groundwater control is therefore not anticipated for the initial site
stripping and fill placement. For deeper excavations where sustained, positive
groundwater control is needed, a system of vacuum well points may be required. The
groundwater level should be maintained at least one foot below the bottom of any
excavations during construction and two feet below the surface of any vibratory
compaction operations. Vibratory compaction efforts should only be perform
beyond 30 feet from existing structures. Within 30 feet of existing structures
equipment should be used in static mode.
4.
Proofroll the compacted subgrade with a heavily loaded, rubber-tired vehicle under the
observation of ECS’ geotechnical engineer or his representative. Proofrolling will help
locate any zones of especially loose or soft soils not encountered in the soil test borings.
Then undercut, or otherwise treat these zones as recommended by the engineer.
5.
Place structural fill material, as required, in accordance with the “Fill Placement” section
of this report, below.
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Fill Placement
Any off-site borrow material to be placed on site should consist of soils classified SP per ASTM
D-2487 and have less than 10 percent passing the No. 200 sieve. The near surface on-site soils
should be suitable for reuse as compacted fill, provided that the moisture content is within an
acceptable range to obtain compaction.
Prior to the commencement of fill operations and/or utilization of any off-site borrow materials,
the contractor should provide representative samples of the soil materials to the geotechnical
engineer. The geotechnical engineer will determine the material’s suitability for use as an
engineered fill and develop moisture-density relationships in accordance with the
recommendations provided herein. Samples should be provided to the geotechnical engineer at
least 3 to 5 days prior to their use in the field to allow for the appropriate laboratory testing to be
performed.
The footprint of the proposed building area should be well defined during fill placement. Grade
controls should also be maintained throughout the filling operations. All filling operations
should be observed on a full-time basis by the Geotechnical Engineer’s representative to
determine that the required degrees of compaction are being achieved. Compliance tests should
be performed at a rate of 1 test per 2,500 square feet per lift in the structure areas, 1 test per
10,000 square feet per lift in paved areas; or two tests, which ever is greater. The elevation and
location of the tests should be accurately identified at the time of fill placement. Areas which fail
to achieve the required degree of compaction should be re-compacted and re-tested until
minimum compaction is achieved. Failing test areas may require moisture adjustments or other
suitable remedial activities in order to achieve the required compaction.
All fill materials placed within the building and pavement areas should be placed in lifts not
exceeding 8 to 12 inch thick loose lifts, moisture conditioned to within 3 percent of the optimum
moisture content, and compacted to a minimum of 95 percent of the Modified Proctor maximum
dry density as determined in accordance with ASTM D 1557.
The upper 1 foot of soils supporting slabs on grade, pavements or sidewalks should be
compacted to 98 percent of the Modified Proctor maximum dry density. In parking areas the
upper 1 foot of fill should consist of a stabilized subgrade with a Limerock Bearing Ratio (LBR)
value of 40. Stabilize this zone with limerock if needed, unless laboratory testing indicates a soil
with LBR value of 40 is present.
In the building areas, test all footing cuts for compaction to a depth of 1 foot below bottom of
footing elevation. We recommend testing every column footing, and conduct a minimum 1 test
for every 100 lineal feet of wall footing. Footing bottoms must be compacted to a minimum of
95 percent of the Modified Proctor maximum dry density as determined in accordance with
ASTM D 1557.
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Fill placed in non-structural areas (i.e. grassed areas) should be compacted to at least 90 percent
of the maximum dry density according to ASTM D-1557, in order to avoid significant
subsidence.
If problems are encountered during the site grading operations, or if the actual site conditions
differ from those encountered during our subsurface exploration, the ECS geotechnical engineer
should be notified immediately.
Retaining Walls
We assume the retaining walls will be constructed of smooth concrete. We recommend using the
parameters stated in the below table for retaining wall design utilizing the in-situ sand and
crushed well-graded limestone as wall backfill. These backfill materials should be compacted to
a minimum of 95% of the maximum dry density obtained in accordance with ASTM
Specification D-1557, Modified Proctor Method. Behind the retaining wall, materials should be
carefully placed and compacted so as not to damage the structure by the use of hand-operated
compaction equipment. All fill operations should be observed on a full-time basis by a qualified
soil technician to determine that minimum compaction requirements are being met. A minimum
of one compaction test should be tested in each lift placed. The elevation and location of the
tests should be clearly identified at the time of fill placement. Laboratory testing in accordance
with ASTM D-1557, Modified Proctor Method, should be performed on a representative sample
of the on-site soils in order to obtain the theoretical maximum dry density for use during
backfilling operations.
A uniform frictional resistance coefficient of 0.30 (tan) can be utilized for sliding resistance
design for the site’s retaining walls. Based on the anticipated soil strength parameters for the insitu sand and crushed well-graded limestone, the following lateral earth pressure coefficients are
provided for horizontal backfill.
Soil Parameters and Lateral Earth Pressure (LEP) Coefficients
Soil Type
Moist
Unit
Weigh
t
(γtotal,
pcf)
Submerged
Unit
Weight
(γ, pcf)
Internal
Angle of
Friction
(φ,º)
Coefficient
of Friction,

Fine Sand
120
58
30
0.30
0
0.33
3.00
0.5
Crushed
Limestone
145
80
36
0.30
0
0.26
3.85
0.4
Cohesion
Intercept
(c, psf)
Active
LEP
Passive LEP
Coefficien Coefficient
t
(Kp)
(Ka)
The table above does not include a factor of safety. Therefore, an appropriate factor of safety
should be incorporated by the designer. Additionally, the recommendations contained above
At-rest
LEP
Coeffici
ent (Ko)
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assume that the backfill behind the retaining walls is horizontal ( = 0 degrees), is properly
drained and will not permit the buildup of hydrostatic pressures behind the wall. Retaining walls
with adjacent sloping earth embankments, sloping backfill or structural loadings require special
considerations. Similarly, the design should also account for any surcharge loads that are within
a 45° slope from the base of the wall. In areas of the wall near corners where rigidity is required,
at-rest equivalent fluid pressures should be utilized.
Pavement Considerations
General
All pavement subgrades should be prepared in accordance with the recommendations in the
sections entitled “Earthwork Operations” and “Fill Placement”. An important consideration
with the design and construction of pavements is surface and subsurface drainage. Where
standing water develops, either on the pavement surface or within the base course layer,
softening of the subgrades and other problems related to the deterioration of the pavement can be
expected. Furthermore, good drainage should reduce the possibility of the subgrade materials
becoming saturated during the normal service period of the pavement.
Regardless of the pavement type, a minimum separation of 18 inches should be maintained
between the pavement base and the season high groundwater levels. No full depth asphalt
or concrete sections are allowed.
We recommend that drains be installed around the landscaped sections adjacent to the parking
lots and driveways to protect the asphalt pavement from excess rainfall and over irrigation.
Migration of irrigation water from the landscape areas to the interface between the asphalt and
the base usually occurs unless landscape drains are installed. This migration often causes
separation of the wearing surface from the base and subsequent rippling and pavement
deterioration. The underdrains or strip drains should be routed to a positive outfall at the
pavement area catch basins.
Light duty roadways and incomplete pavement sections will not perform satisfactorily under
construction traffic loadings. We recommend that construction traffic (construction equipment,
concrete trucks, sod trucks, garbage trucks, moving vans, dump trucks, etc.) be re-routed away
from these roadways or that the pavement section is designed for these loadings.
Flexible pavement combines the strength and durability of several layer components to produce
an appropriate and cost-effective combination of available construction materials. Rigid concrete
pavement has the advantage of the ability to “bridge” over isolated soft areas, it requires less
lighting, and it typically has a longer service life than asphalt pavement. Disadvantages of rigid
pavement include an initial higher cost and more difficult patching of distressed areas than
occurs with flexible pavement.
St. Joseph’s Women’s Hospital Bed Tower Addition
ECS Job No.: 24-3110
January 26, 2009
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Asphalt (Flexible) Pavements
Layer Components
As a reference Hillsborough County has divided their pavement requirements into four types of
services: 1. Local Roads, 2. Subdivision Collector Roads, 3. Major Collector Roads, and 4.
Industrial/Commercial Roads.
We believe that the minimum county requirements may lead to more than normal periodic
maintenance and may not meet typical life expectancies for some pavements. If projected traffic
loads become available, we recommend that an appropriate pavement design be used and the
component thicknesses be adjusted accordingly.
Because traffic loadings are commonly unavailable, we have generalized our pavement design
into the four groups as divided by Hillsborough County. The group descriptions and the
recommended component thicknesses are presented in following table. For loading conditions
greater than those presented in the following table, we recommend that you have a complete
pavement design performed based on projected traffic data.
Pavement Component Recommendations
Component Thickness
Traffic Group
Stabilized
Subgrade**
Local Roads
6”
40 LBR
Subdivision Collector Roads
8”
40 LBR
Major Collector Roads
12”
40 LBR
Base
Course
6" Limerock
6" Soil Cement
6” Crushed Concrete
4” Asphalt (ABC III)
or
6” Shell
8" Limerock
8" Soil Cement
8” Crushed Concrete
5” Asphalt (ABC III)
or
8” Shell
8" Limerock
8" Soil Cement
8” Crushed Concrete
5” Asphalt (ABC III)
or
8” Shell
Surface Course***
1¾”
1¾”
2”
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January 26, 2009
Page 15 of 19
Industrial Commercial Roads
12”
40 LBR
8" Limerock*
8" Soil Cement*
8” Crushed Concrete*
5” Asphalt (ABC III)*
or
8” Shell *
Local Roads 2¼”
Collector Roads 2½“
Arterial Road 2½”
* Base course can be reduced to 6 inches with design calculations
** Stabilized subgrade can be reduced to LBR 20 for 12 inches when using soil cement
*** Add FC-3 friction course if speeds are greater than 45 mph
Stabilized Subgrade
We recommend that subgrade materials be compacted in place according to the requirements in
the "Earthwork Operations" section of this report. Further, stabilize the subgrade materials
should have a minimum Limerock Bearing Ratio (LBR) of 40 percent. All stabilized subgrade
materials should be compacted to 98 percent of the Modified Proctor (AASHTO T-180)
maximum dry density and meet specification requirements for Type B or Stabilized Subgrade by
Florida Department of Transportation (FDOT).
Further, the stabilized subgrade can be imported material or a blend of on-site soils and imported
materials. If a blend is proposed, we recommend that the contractor perform a mix design to find
the optimum mix proportions.
Base Course
We recommend that the base course be limerock, soil cement, crushed concrete, asphalt, or shell.
If limerock is used it should have a minimum LBR of 100 percent and should be mined from an
FDOT approved source. Place limerock in maximum 6-inch lifts and compact each lift to a
minimum density of 98 percent of the Modified Proctor (AASHTO T-180) maximum dry
density.
For a soil-cement base, we recommend that the contractor perform a soil-cement design with a
minimum seven-day strength of 300 pounds per square inch (psi) on the materials he intends to
use. Place soil-cement in maximum 6-inch lifts and compact in place to a minimum density of
95 percent of the Standard Proctor maximum dry density according to specifications in ASTM D558.
Place and finish the soil-cement according to Portland Cement Association requirements. Final
review of the soil-cement base course should include manual "chaining" and/or "soundings"
seven days after placement. Shrinkage cracks will form in the soil-cement mixture and you
should expect reflection cracking on the surface course.
Crushed concrete, asphalt base, or shell should follow the appropriate FDOT specifications.
Perform compliance testing for the base course at a frequency of one test per 500 lineal feet of
St. Joseph’s Women’s Hospital Bed Tower Addition
ECS Job No.: 24-3110
January 26, 2009
Page 16 of 19
roadway alternating between lanes, every 5,000 square feet of pavement, or at a minimum of two
test locations, whichever is greater.
Surface Course
In residential light duty areas where there is occasional truck traffic, but primarily passenger cars,
we recommend using an asphaltic concrete, FDOT Type S. A minimum of two lifts are required
for pavement thickness greater than 2 inches.
Asphaltic concrete mixes should be a current FDOT approved design of the materials actually
used. Test samples of the materials delivered to the project should be checked to verify that the
aggregate gradation and asphalt content satisfies the mix design requirements. Compact the
asphalt to a minimum of 95 percent of the Marshall design density.
After placement and field compaction, core the wearing surface to evaluate material thickness
and to perform laboratory densities. Obtain cores at frequencies of at least one core per 500
lineal feet of placed pavement or a minimum of two cores per day's production.
Effects of Groundwater
One of the most critical influences on the pavement performance in Central Florida is the
relationship between the pavement subgrade and the seasonal high groundwater level.
Many roadways and parking areas have been destroyed as a result of deterioration of the base and
the base/surface course bond. Regardless of the type of base selected, we recommend that the
seasonal high groundwater and the bottom of the base course be separated by at least 18 inches.
To maintain this separation, either raise the roadway grades or artificially lower the groundwater
level with underdrains.
Landscape Drains
We recommend that drains be installed around the landscaped sections adjacent to the parking
lots and driveways to protect the asphalt pavement from excess rainfall and over irrigation.
Migration of irrigation water from the landscape areas to the interface between the asphalt and
the base usually occurs unless landscape drains are installed. This migration often causes
separation of the wearing surface from the base and subsequent rippling and pavement
deterioration. The underdrains or strip drains should be routed to a positive outfall at the
pavement area catch basins.
Construction Traffic
Light duty roadways and incomplete pavement sections will not perform satisfactorily under
St. Joseph’s Women’s Hospital Bed Tower Addition
ECS Job No.: 24-3110
January 26, 2009
Page 17 of 19
construction traffic loadings. We recommend that construction traffic (construction equipment,
concrete trucks, sod trucks, garbage trucks, moving vans, dump trucks, etc.) be re-routed away
from these roadways or that the pavement section be designed for these loadings.
Concrete (Rigid) Pavements
Concrete pavement is a rigid pavement that transfers much lighter wheel loads to the subgrade
soils than a flexible asphalt pavement. For a concrete pavement subgrade, a minimum 4 inch
thick limerock base course should be placed beneath the concrete atop a 4 inch thick stabilized
subgrade. The limerock base and stabilized subgrade should be densified to at least 98 percent of
Modified Proctor test maximum dry density (ASTM D 1557).

The surface of the subgrade soils must be smooth, and any disturbances or wheel rutting
corrected prior to placement of concrete.

The subgrade soils must be moistened prior to placement of concrete.

Concrete pavement thickness should be uniform throughout, with exception to thickened
edges (curb or footing).

The bottom of the pavement should be separated from the estimated typical wet season
groundwater level by at least 18 inches.
Our recommendations for slab thickness for heavy-duty concrete pavements are based on the
same factors as above. We recommend using concrete of unreinforced Portland cement concrete
(Type I) providing a minimum 28-day compressive strength of 4,000 pounds per square inch
(psi). In addition, the concrete should provide a minimum 28-day flexural strength (modulus of
rupture) of 600 psi, based on the third point loading of concrete beam samples.
Front-loading trash dumpsters frequently impose concentrated front-wheel loads on pavements
during loading. This type of loading typically results in rutting of bituminous pavements and
ultimately pavement failures and costly repairs. Therefore, we suggest that the pavements in
trash pickup areas utilize a heavy duty Portland Cement Concrete (PCC) pavement section. Such
a PCC section would typically consist of 6 inches of 4,000 psi concrete over a 6 inch thick
compacted aggregate base course. Appropriate steel reinforcing and jointing should also be
incorporated into the design of all PCC pavements.
Concrete pavement is a rigid pavement that transfers reduced wheel pressures to the underlying
subgrade soils. Control joints for crack control should be a maximum of 12 feet apart and 1.5
inches deep. Control joints should be provided in a uniform square or rectangular pattern. The
joints should be submitted for review and approved prior to construction. Control joints should
be sawed as soon as the concrete can withstand traffic, and concrete surface and aggregate
raveling can be prevented.
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One of the most critical influences on the pavement performance in South Florida is the
relationship between the pavement subgrade and the seasonal high groundwater level. It is
recommended that the seasonal high groundwater and the bottom of the stabilized subgrade be
separated by at least 18 inches.
Construction Considerations
Exposure to the environment may weaken the soils at the footing bearing level if the foundation
excavations remain open for too long a time. Therefore, foundation concrete should be placed
the same day that excavations are excavated during the rainy season or if rain is anticipated. If
the bearing soils are softened by surface water intrusion or exposure, the softened soils must be
removed from the foundation excavation bottom immediately prior to placement of concrete. If
the excavation must remain open overnight, or if rainfall becomes imminent while the bearing
soils are exposed, the geotechnical engineer should be contacted immediately.
The soils at the proposed bearing elevations are moisture and disturbance sensitive. When wet,
these soils will degrade quickly and create a soft condition that is not suitable to support the
building loads without detrimental settlement. The contractor may need to dewater (sump pits
and trenching) the site to two feet below the groundwater level at the time of construction,
depending on foundation depth and time of year. Without dewatering the site soils prior to
excavating footings, we anticipate that the foundations will need to be excavated and placed
within two to three hours. If aggressive dewatering is not undertaken, then the footings will need
to be excavated to within six inches of subgrade to maintain an overburden confinement. Once
the footing excavations are tested by ECS, concrete placed in no more than two hours. If final
concrete cannot be placed within that timeframe, then we recommend the use of a 2 to 3 inch
thick concrete mudmat used with the same placement limitations. The contractor may elect to
place the foundations in sections in order to limit the softening of soils, which should be removed
The surficial soils are considered moderately erodible. The Contractor should provide and
maintain good site drainage during earthwork operations to help maintain the integrity of the
surface soils. The surface of the site should be kept properly graded in order to enhance drainage
of the surface water away from the proposed construction areas during the earthwork phase. We
recommend that surface drainage be diverted around the proposed building area without
significantly interrupting its pattern. All erosion and sedimentation shall be controlled in
accordance with sound engineering practice and current state and local requirements.
Closing
This report has been prepared to aid in the evaluation of this site and to assist the design team
with the design of the proposed facility. The report scope is limited to this specific project and
the location described. The project description represents our current understanding of the
significant aspects of the proposed improvements relevant to the geotechnical considerations.
St. Joseph’s Women’s Hospital Bed Tower Addition
ECS Job No.: 24-3110
January 26, 2009
Page 19 of 19
The analysis and recommendations are, of necessity, based on the information made available to us
at the time of the actual writing of the report and the on-site conditions, surface and subsurface that
existed at the time the exploratory borings were drilled. Further assumptions have been made that
the limited exploratory borings, in relation both to the aerial extent of the site and to depth, are
representative of conditions across the site. If subsurface conditions are encountered which differ
significantly from those reported herein, such as muck or silt, this office should be notified
immediately so that the analyses and recommendations can be reviewed for validity.
The earthwork and foundation construction operations for the site will be a primary consideration
during development of this project. The placement of any new engineered fill will require
adequate monitoring during construction in order to assure that the fill mass is installed properly
to avoid future settlements. Because of our in-depth knowledge of the subsurface conditions at
the site, we recommend that ECS observe all earthwork and construction operations to assure
that the work is being performed in accordance with the project specifications. It is also
recommended that ECS be allowed to prepare or at least review the project specifications with
regard to the earthwork for this site.
We would appreciate the opportunity to continue our involvement on the project during
construction. ECS-Florida, LLC is capable of providing all Construction Materials Testing,
Private Provider Inspections (mechanical, electrical, plumbing and building), Threshold
Inspections and Resident Inspections; and we would be glad to prepare proposals to offer our
services.
APPENDIX
Unified Soil Classification System
Reference Notes for Boring Logs
Boring Location Plan
Boring Logs S-1 through S-3; A-1 and A-2: C-1 and C-2;
Pressuremeter Tests P-1 (Sounding 1) and P-2 (Sounding 2)
REFERENCE NOTES FOR BORING LOGS
I.
Drilling Sampling Symbols:
SS
Split Spoon Sampler
RC
Rock Core, NX, BX, AX
DC
Dutch Cone Penetrometer
BS
Bulk Sample of Cuttings
HAS Hollow Stem Auger
II.
ST
PM
RD
PA
WS
Shelby Tube Sampler
Pressuremeter
Rock Bit Drilling
Power Auger (no sample)
Wash Sample
Correlation of Penetration Resistances to Soil Properties:
Standard Penetration (Blows/Ft) refers to the blows per foot of a 140 lb. Hammer falling 30 inches
on a 2-inch OD split spoon sampler, as specified in ASTM D-1586. The blow count is commonly
referred to as the N value.
A.
Non-Cohesive Soils (Silt, Sand, Gravel and Combinations)
Density
Under 4 blows/ft
Very Loose
4 to 10 blows/ft
Loose
11 to 30 blows/ft
Medium Dense
31 to 50 blows/ft
Dense
Over 51 blows/ft
Very Dense
Particle Size Identification
8 inches or larger
3 to 8 inches
1 to 3 inches
½ to 1 inch
¼ to ½ inch
2.00 mm to ¼ inch (dia. of lead pencil)
0.42 to 2.00 mm (dia. of broom straw)
0.074 to 0.42 mm (dia. of human hair)
0.0 to 0.074 mm (particles cannot be seen)
Boulders
Cobbles
Gravel
Coarse
Medium
Fine
Sand
Coarse
Medium
Fine
Silt and Clay
B.
III.
Relative Properties
Adjective Form
12% to 49%
With
5% to 12%
Cohesive Soils (Clay, Silt, and Combinations)
Blows/ft
Consistency
Unconfined
Comp. Strength
Qp (tsf)
Under 2
2 to 4
4 to 8
9 to 15
16 to 30
Over 30
Very Soft
Soft
Med. Stiff
Stiff
Very Stiff
Hard
Under 0.25
0.25-0.49
0.50-0.99
1.00-1.99
2.00-3.00
Over 4.00
Degree of
Plasticity
Plasticity
Index
None to Slight
Slight
Medium
High to Very High
0–4
5 -7
8 - 22
Over 22
Water Level Measurement Symbols:
WL Water Level
WS While Sampling
WD While Drilling
BCR Before Casing Removal
DCI Dry Cave-In
ACR After Casing Removal
WCI Wet Cave-In
Existing Groundwater Level ●
Est. Seasonal High GWT
The water levels are those water levels actually measured in the borehole at the times indicated by the
symbol. The measurements are relatively reliable when augering, without adding fluids, in a granular
soil. In clay and plastic silts, the accurate determination of water levels may require several days for
the water level to stabilize. In such cases, additional methods of measurement are generally applied.
REPORT OF
SUBSURFACE EXPLORATION AND
GEOTECHNICAL ANALYSIS
ST. JOSEPH’S WOMEN’S HOSPITAL
BED TOWER ADDITION
TAMPA, FLORIDA
FOR
HKS, INC
JANUARY 26, 2009