City of Gladstone Project LA1BTFM7PNQ6 Flora Park (Phase II) Geotechnical Report.

GEOTECHNICAL ENGINEERING REPORT
FLORA PARK UPGRADES
5940 N. FLORA AVE.
GLADSTONE, MO 64118
(AOG 260169 E)
Date: March 25, 2026
Submitted to: Westwood Professional Services
Katherine Lewis Mitchell
1165 Scenic Drive, Ste. A
Modesto, CA 95350
3/25/2026
Submitted by: ALPHA-OMEGA GEOTECH, INC.

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March 25, 2026 Pag e | 2
TABLE OF CONTENTS
1.0 PROJECT DESCRIPTION ................................................................................................................................................... 4
2.0 SUBSURFACE INVESTIGATION ........................................................................................................................................ 4
3.0 LABORATORY TESTING PROGRAM ................................................................................................................................. 5
4.0 GROUNDWATER ............................................................................................................................................................. 6
5.0 GEOTECHNICAL CONSIDERATIONS ................................................................................................................................. 6
6.0 SITE DEVELOPMENT ........................................................................................................................................................ 6
6.1 Site Preparation .......................................................................................................................................................... 6
6.2 Undocumented Fill ..................................................................................................................................................... 7
6.3 Engineered Fill Placement .......................................................................................................................................... 7
6.4 Drainage Considerations ............................................................................................................................................ 8
6.5 General ....................................................................................................................................................................... 8
7.0 FOUNDATIONS ................................................................................................................................................................ 9
7.1 Spread Footings Foundations ..................................................................................................................................... 9
7.2 Allowable Bearing Pressure ........................................................................................................................................ 9
7.3 Anticipated Settlement .............................................................................................................................................. 9
7.4 General ..................................................................................................................................................................... 10
8.0 SLABS ON GRADE .......................................................................................................................................................... 10
8.1 Slab Thicknesses ....................................................................................................................................................... 10
8.2 Low Volume Change (LVC) ....................................................................................................................................... 10
9.0 EARTH PRESSURE COEFICIENTS .................................................................................................................................... 12
10.0 PAVEMENTS ................................................................................................................................................................ 12
10.1 Subgrade Preparation ............................................................................................................................................ 12
9.2 Pavement Sections ................................................................................................................................................... 13
10.3 Recompacted Subgrade Sections ........................................................................................................................... 14
10.3.1 Flexible Pavements Sections ........................................................................................................................... 14
10.3.2 Rigid Pavement Sections ................................................................................................................................. 14
10.4 Subgrade Stabilization Sections ............................................................................................................................. 15
9.4.1 Flyash/Cement .................................................................................................................................................. 15
10.4.2 Geogrid Reinforcement & Base Rock .............................................................................................................. 15
10.5 General ................................................................................................................................................................... 16
11.0 TESTING AND INSPECTION RECOMMENDATIONS ...................................................................................................... 17
12.0 LIMITATIONS ............................................................................................................................................................... 18
Appendix Section A - SITE AND BORING LOCATION PLANS
Appendix Section B - LABORATORY TEST RESULTS
Appendix Section C - BORING LOGS

March 25, 2026
Westwood Professional Services
Katherine Lewis Mitchell
1165 Scenic Drive, Ste. A
Modesto, CA 95350
FLORA PARK UPGRADES
5940 N. FLORA AVE.
GLADSTONE, MO 64118
(AOG 260169 E)
Katherine,
Alpha Omega Geotech, Inc. (AOG) has completed its geotechnical engineering
investigation for the above-referenced project.
Attached are the following items that were utilized in the analysis and evaluation of the
subsurface conditions at this site: a sketch giving the approximate location of the three
(3) auger borings completed during this investigation with reference to the existing site
features; detailed laboratory results of two (2) moisture contents (ASTM D2216 one (1)
dry density (ASTM D7263), two (2) sets of Atterberg limits (ASTM D4318), and one (1)
unconfined compression (ASTM D2166) test attempted, two (2) calibrated pocket
penetrometer readings, and three (3) auger boring (ASTM D1452) logs that describe the
materials encountered, their approximate thicknesses, and the sampling depths where
Standard Penetration (ASTM D1586) tests were performed.
Representatives of AOG located each of the selected borings by measuring from the
existing site features, and these measurements should be considered accurate only to the
extent implied by the method of measurement. Elevations were not determined in the
field at the time of drilling. Each of the borings was completed by AOG using a CME 55
high-torque drill rig.

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1.0 PROJECT DESCRIPTION
The site is currently a city park, and the construction area covers approximately 0.7 acres and is relatively flat with a
grade change of approximately 7 feet across the site.
Based on provided information AOG understands that there will be a new restroom facility constructed. The site
location is shown on the embedded site/boring plan. The building will be single story with an approximate footprint
of 220 sqft. with assumed wood or CMU block slab on grade construction. The finished floor elevation and foundation
loads were not provided. AOG will assume finished floor elevation will be close to existing grade and the foundation
loads will be relatively light. There will be a new paved parking and drives covering approximately 10,725 sqft.
A grading plan has not been provided, AOG will assume cuts and fills will be in the range of one (1) to three (3) feet
to reach final design grade.
2.0 SUBSURFACE INVESTIGATION
Based on the information provided, AOG drilled three (3) auger borings at the proposed site. The borings were
advanced to their planned depths or auger refusal, whichever occurred first. Refusal depths are shown on the
following table:
Table 1: Auger Refusal Depths
ROCK REFUSAL TABLE (FT)
Depth to Top of Weathered
Boring # Boring Location Practical Refusal Depth
Rock
B1 See Site Sketch ~ 8.5 9.1
B2 See Site Sketch N/A N/A (10.0)
B3 See Site Sketch N/A N/A (15.0)
(*) Very hard, weathered limestone and shale that was penetrable using our high-torque drilling equipment was encountered
above the auger refusal depths shown above (see the boring logs enclosed in Appendix Section 1 of this report).
It should be understood that the depth of boring, split-spoon refusal or auger refusal reported herein applies to the
type of drilling equipment that was used. As such, it might be possible to extend some of these borings deeper using
different drilling equipment and/or techniques. Conversely, residual sandstone, shale and limestone materials
through which AOG's drill rig penetrated, without achieving refusal, may be difficult to excavate depending upon the
equipment being used. As such, Alpha-Omega Geotech, Inc. shall not be responsible for the determination of Others,
regarding the rippability, or ease of excavation, of the in-situ subgrade, bedrock and/or geo-intermediate materials.
Above the depth, at which boring termination occurred, predominantly clay soils were encountered in the borings.
Standard Penetration tests (SPT) (ASTM D1586) were also used to sample and evaluate the consistency of the in-situ
subgrade materials encountered in these test borings. Standard Penetration Tests are conducted by advancing a
hollow, split spoon sampler into the base of the auger hole by means of dropping a 140-pound hammer a distance

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of 30 inches onto the drill rods. Each drop of the hammer is one blow, and these blow counts are recorded for each
of three, 6-inch advances of the sampler. The first 6-inch advance is the seating drive, and the summation of the
blow counts of the final two, 6-inch advances is taken as the standard penetration resistance. The standard
penetration resistance, or N-value, as it is known, along with the soil classification, can be used to estimate the
density, shear strength and other engineering properties of the materials encountered.
The N-values obtained from each of the SPT's completed in these borings using a CME automatic hammer are
included on the boring logs and summarized in the Summary of Laboratory Testing sheet found in Appendix B.
Samples retrieved during drilling efforts were returned to AOG's laboratory for testing and evaluation.
3.0 LABORATORY TESTING PROGRAM
Laboratory testing on materials collected during drilling was performed on samples selected by AOG. Results from
these tests can be found in Appendix B and on the boring logs in Appendix C. The following laboratory tests were
performed by qualified AOG personnel in accordance with ASTM specifications to determine pertinent engineering
properties of the soils:
* Visual classification (ASTM D2488)
* Moisture content tests (ASTM D2216)
* Atterberg limits tests (ASTM D4318)
* Dry Unit Weight (ASTM D7263)
The dry unit weight of the specimen cut from the Shelby tube sample was found to be moderate at 97.5 pounds per
cubic foot (pcf). Depending upon the material composition and depth below existing grade, the moisture content of
the specimens cut from these tube samples ranged from 15.5 to 16.9 percent. The unconfined compressive strength
specimen cut from the Shelby tube sample fractured during testing. Calibrated pocket penetrometer readings
ranging from 1.00 tons per square foot (tsf) (2000 psf) to 2.25 tsf (4500 psf) were obtained on the recovered Shelby
tube samples. However, it should be noted that the pocket penetrometer values tend to over-estimate the strength
of in-situ subgrade materials relative to the actual unconfined compressive strength test.
The Atterberg consistency limits were determined for two (2), generally, representative sample taken at relatively
shallow depth from within the proposed structures' footprints. Based on the Atterberg limits, the samples were
classified in accordance with the Unified Soil Classification System (USCS) as Lean Clay (CL) classification materials.
The results of these laboratory analyses are presented in the following table:
Table 2: Atterberg Limits Results
ATTERBERG LIMITS TESTS
Liquid Plastic Plasticity
Sample Depth (ft) USCS Classification
Limit Limit Index
B1, ST-2 3.0-5.0 40 20 20 Lean Clay (CL)
B2, SS-2 3.5-5.0 45 21 24 Lean Clay (CL)

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Based on the Atterberg limits, it is anticipated that the majority of the onsite soil materials generally possess a
moderate swelling potential. The swelling potential of a clay soil is an indication of the volume changes that may
take place with variations in the soil moisture content.
Except for the samples for which the Atterberg limits were determined, all of the other soil classifications given
throughout the laboratory test data, as well as the boring logs, were made using the visual and tactile techniques
described in ASTM D2488. As a result, additional analyses could reveal other soil types of different classification and
potentially higher plasticity and swelling potential both onsite and within the nearby vicinity.
4.0 GROUNDWATER
Free water was not encountered in any of the borings at the time of drilling. However, a twenty-four-hour water
level was not established in these borings due to time restrictions, as well as potential safety hazards associated with
open bore holes.
Although the ground water levels given on the boring logs reflect the conditions observed at the time the borings
were made, they should not be construed to represent an accurate or permanent condition. There is uncertainty
involved with short-term water level observations in bore holes especially in clay soils of relatively low permeability.
The groundwater level should be expected to fluctuate with variations in precipitation, site grading and drainage
conditions. In addition, it is also possible that seasonal perched ground water may be encountered within these soil
deposits and bedrock formations at different depths during other times of the year based on drainage conditions,
seasonal snowmelt, and rainwater infiltration.
5.0 GEOTECHNICAL CONSIDERATIONS
The following considerations are given based on observations made by AOG at the time of drilling, during
reconnaissance trips, and based on the project requirements and description as stated above:
Compressible Soils: The soils encountered during this exploration are, generally lean, and, as such, can be
unstable and compressible, in nature. Any soft, compressible areas identified on the proposed project site
must be corrected in accordance with Section 6.1, Site Preparation of this report.
6.0 SITE DEVELOPMENT
6.1 Site Preparation
Based on the information provided, AOG anticipates cut and fill amounts of about one (1) to three (3) feet (+/-) from
the existing ground surface elevation, within the proposed project limits, will be required to achieve design grades.
It is possible that additional cuts and fills may be required to obtain improved surface drainage.
Appropriate erosion control measures, such as proper site contouring during grading activities, as well as silt fences,
should be maintained to help keep any eroded materials onsite.
Within the footprint of the proposed new structure, it is recommended that any topsoil, vegetation, utility backfill,
and other deleterious material (i.e., concrete slabs, relic foundations, utilities, etc.) or pavements should be stripped

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and removed prior to the placement of any fill required to achieve the finished floor elevation. In accordance with
the local building code, this should be verified by a representative of Alpha-Omega Geotech, Inc. prior to the
placement of fill.
Once initial site stripping operations have been completed and prior to the placement of any engineered fill in this
area, it is recommended that the exposed subgrade be moisture conditioned and recompacted, as needed, and be
thoroughly evaluated by means of a proof-roll with a fully loaded, tandem-axle dump truck to locate any soft,
compressible areas within the proposed project site. Any soft, compressible areas identified on the proposed
project site must be corrected by over-excavation to a suitable subgrade and replaced with an acceptable material.
Although it is not anticipated that any extensive removal and replacement would be necessary, it is possible that
some effort may be required to develop a stable platform on which to place the necessary fill material and address
any other existing site conditions that become known during construction. It is generally anticipated that the extent
of these efforts would strongly depend upon the ground moisture conditions at the time the site work begins. In
the event that the ground is generally dry, it is possible that only a minimal amount of stabilization would be
required, which may be possible to accomplish by simple moisture conditioning and re-compaction efforts.
Nevertheless, it is recommended that a representative of Alpha-Omega Geotech, Inc. should be onsite to witness this
proof-rolling and offer recommendations, as needed, to correct any problem areas identified.
6.2 Undocumented Fill
Undocumented fill is a foreign material, of which no records of testing or evaluation by a qualified professional
during the time of placement exist. Undocumented fill is, generally, unsuitable beneath structures, and if
encountered during development, should be fully removed, and replaced with engineered fill in accordance with
this report. Undocumented fill beneath pavements should be undercut to a minimum depth of two (2) feet, and
the exposed subgrade should be thoroughly evaluated by a registered professional engineer.
6.3 Engineered Fill Placement
It is assumed that any fill material needed will come from cut areas and, if necessary, on-site, or nearby borrow
sources of similar material. It is recommended that un-weathered shales should NOT be used to construct any of
the necessary fill within either the new building or paved portions of the site. Assuming they are properly moisture
conditioned and compacted, it generally appears that the clean clay soils encountered in the borings that are free
of rubble, trash, concrete, asphalt, and other debris would be acceptable for use as controlled fill. However, due to
their very high swelling potential, detailed recommendations for the placement of a non-expansive subbase are
provided in Section 8.0, SLABS ON GRADE of this report.
Any imported fill materials for use as structural fill should be tested by Alpha-Omega Geotech, Inc. to determine if
they are acceptable for the intended use. Any ground water seeps that are encountered must be diverted prior to
placing fill.
In addition, no compaction of soil fill material should be performed during freezing weather. Nevertheless, as
weather conditions dictate, it may be possible to substitute crusher-run limestone in lieu of soil fill to allow
placement of engineered controlled fill material to continue during the cold fall and winter months. However, any
frozen fill material must be stripped prior to placing subsequent lifts.

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All general fill within the area of the new building (except for the upper 24-inches, as discussed in Section 8.0, SLABS
ON GRADE of this report, should be placed in lifts not exceeding 6 inches in thickness, and compacted to a minimum
density of 95 percent of the Standard Proctor (ASTM D698) maximum dry density at a moisture content within 3
percent of the optimum moisture content.
As required by the local building code, the compaction of any structural fill beneath the new buildings, pavements,
and any other areas where settlement control is necessary, as well as any slopes that are steeper than 4:1 (H:V)
should be tested lift-by-lift by a representative of Alpha-Omega Geotech, Inc.
6.4 Drainage Considerations
Fluctuations of the ground water level can occur due to seasonal variations in the amount of rainfall and other
climatic factors that were not evident at the time the borings were made. The possibility of ground water level
fluctuations should be considered when developing the design and construction plans for the project. In spring and
late fall, soil moisture contents may be abnormally high and drying of the soils that are exposed and/or undercutting
may be required to develop a suitable base for the placement and compaction of engineered fill. Disking and
aeration of the exposed soils may be sufficient to develop a stable base. However, if site grading begins during the
summer or early fall, moisture contents may be abnormally low and the plastic clay soils encountered during this
exploration may undergo significant volume changes with subsequent increases in their moisture content.
Therefore, when these conditions exist, disking and moisture conditioning of the exposed subgrade soils may be
required.
It is important to consider drainage and construction elements that will help to inhibit future slab on grade
problems, foundation cracks, as well as intolerable settlements due to volume changes of the onsite soils. The
surface drainage must be designed to prevent ponding and effectively move water away from both the new and
existing buildings, pavements, and other structures. It is also very important to place all materials under carefully
controlled conditions of moisture and density to inhibit significant soil volume changes. Shrubs and trees with deep
root systems and requiring large quantities of water should not be planted within 20 feet of the building lines. Any
planters located near the building should have impermeable bases with weep holes to discharge water away from
the wall lines. Down spouts should be connected to subsurface drains to carry the water to safe exits beyond the
building lines, retaining walls, pavements, slopes and other site features or structures that could be adversely
affected by water seepage.
6.5 General
Permanent slopes should not be steeper than 3:1 (H:V) to help ensure their future stability and accommodate
normal mowing equipment. The responsibility for excavation safety and stability of temporary construction slopes
should lie solely with the contractor and should follow the OSHA regulations given in 29 CFR Part 1926.650 - .652,
Subpart P. The stability of open excavations is dependent upon a number of factors including but not limited to the
presence of gravel, sand and/or silt seams, ground water seepage, strength characteristics of the soil layers,
slickensides and other unique geological features, the slope and height of the cut, surcharge loading and vibrations
during construction, weather conditions, as well as the length of time the excavation is left open. Alpha-Omega
Geotech, Inc. does not assume any responsibility for construction site safety or the contractor's or other parties'

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compliance with all local, state and federal safety or other regulations including imprudent excavating practices that
results in any damage to nearby structures, roadways, utilities, as well as onsite or offsite improvements.
7.0 FOUNDATIONS
7.1 Spread Footings Foundations
Based on the laboratory test data, the available subsurface information that has been obtained and our
understanding of the project requirements, it is our opinion that a shallow foundation system consisting of either
earth-formed trench or spread footings may be used for this structure as economical foundation elements.
Perimeter footings, and any footings in unheated areas, should be placed at least 3 feet below final exterior grade
to provide adequate frost protection and place them in a more stable moisture environment. Under heated areas,
the interior footings can be found at shallower depths of at least 18 inches below the finished floor elevation. The
footing excavations should be carried to undisturbed, inorganic soil or engineered fill.
7.2 Allowable Bearing Pressure
Provided all design and inspection recommendations as given in this report are closely followed and good
construction practices are exercised, it is recommended an allowable bearing value of 1,500 psf may be used for
design purposes to proportion the spread/wall footings and pedestal foundations. A twenty-percent increase, i.e.,
1,800 psf, may be used for individual column footings. These allowable bearing capacity values, which are based on
shear strength alone and not on settlement, incorporate a factor of safety of 3.0. The actual bearing capacity of all
subgrade supporting the foundation elements must be confirmed by a representative of Alpha-Omega Geotech, Inc.
as the excavations for the load-bearing wall and column footings are completed and prior to placement of reinforcing
steel and concrete. For transient loading conditions, such as un-sustained wind and earthquake, a 33 percent
increase may be applied to the above-referenced allowable bearing capacity values.
Based on the subsurface conditions that have been identified, Site Class D conditions (IBC 2018) may be assumed
for seismic considerations.
7.3 Anticipated Settlement
Uniform bearing conditions should be provided beneath the footings to minimize differential settlements. If any
soft or otherwise unsuitable material is encountered in the footing excavations, it will have to be removed and
replaced with engineered controlled fill. Recommendations for the over-excavation and replacement with
engineered controlled fill (MoDOT Type 5) can be made when the footing excavations are inspected during
construction, if needed. A representative of Alpha-Omega Geotech, Inc. should inspect all of the footing excavations
to verify that uniform and competent bearing material is present beneath all of the foundation elements prior to the
placement of any reinforcing steel and concrete.
For spread footings designed and constructed in accordance with this report, it is anticipated that settlements will
be limited to 0.75 inches of differential and 1.0 inches in total.

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7.4 General
Except for the moisture conditioning discussed in the "Slab On Grade" section of this report, it is recommended that
all fill within the new building and paved areas of the site should be constructed as engineered controlled fill placed
in lifts not exceeding 6 inches in thickness and compacted to a minimum density of 95 percent of the Standard
Proctor (ASTM D698) maximum dry density at a moisture content within 3 percent of the optimum moisture
content. In accordance with the local building code, a representative of Alpha-Omega Geotech, Inc. should be onsite
during placement of all engineered controlled fill within the new building and paved areas to confirm lift thickness
and test the compaction of the engineered controlled fill lift-by-lift as it is being placed.
If possible, the over-excavated footings should not be left open for more than 24 hours. The base of the footing
excavations should be free of water and loose soil prior to placing reinforcing steel and concrete. No ground water
is expected in the footing excavations since ground water was not encountered in any of the borings that were
made at the time of drilling. However, if ground water is encountered within the expected depth of excavation for
the footings, it is generally anticipated that it can be removed by the use of sumps and pumps. Based on the
subsurface conditions that have been identified, it is anticipated that earth-formed trench footing excavations may
be used effectively on this project. However, due to the possible presence of existing rocky fill material, it may
become necessary to utilize formed footings. A minimum width of 12 inches should be used for trenched wall
footings to allow for steel placement and inspection. Minimum widths of 16 and 24 inches should be used for
formed wall and column footings, respectively.
8.0 SLABS ON GRADE
8.1 Slab Thicknesses
Slabs on grade that will be subjected to repeated wheel loads, such as passenger vehicles, should be at least 6 inches
in thickness. Slabs that are not exposed to repeated wheel loads, should be at least 4 inches in thickness. Slabs in
storage areas may need to be thicker due to shelving post and other concentrated floor loads. Actual slab
thicknesses should be determined by the project structural engineer.
8.2 Low Volume Change (LVC)
The following recommendations provided to help protect the slabs from damage caused by volume changes within
the underlying subgrade, and should be implemented in conjunction with Section 7.0, FOUNDATIONS of this report:
1) Cut the subgrade to a minimum of 24-inches beneath the base of slab elevation to allow placement of a
20-inch subbase and a 4-inch base course beneath the slab-on-grade.
2) Scarify and recompact the upper 9 inches of exposed subgrade to within 95 to 100 percent of the Standard
Proctor (ASTM D698) maximum dry density at a moisture content wet of the optimum moisture content
0 to 3 percent.
3) For the 24-inch granular subbase, place crusher-run limestone or rock dust in three (3) approximately
equal lifts and compact to a minimum density of 95 percent of the Standard Proctor (ASTM D698)