HomeMy WebLinkAboutFAIRWAY APARTMENTS - FDP210023 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORT
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TABLE OF CONTENTS
SUMMARY .................................................................................................................................... 1
PURPOSE AND SCOPE OF STUDY ........................................................................................... 2
PROPOSED DEVELOPMENT ..................................................................................................... 2
SITE CONDITIONS ...................................................................................................................... 3
SUBSURFACE CONDITIONS ...................................................................................................... 3
LABORATORY TESTING ............................................................................................................. 4
WATER-SOLUBLE SULFATES .................................................................................................... 5
GEOTECHNICAL ENGINEERING CONSIDERATIONS .............................................................. 5
SITE GRADING AND EARTHWORK ........................................................................................... 6
PRELIMINARY FOUNDATION CONSIDERATIONS.................................................................... 8
FLOOR SLABS ............................................................................................................................. 8
SURFACE DRAINAGE ................................................................................................................. 9
PRELIMINARY PAVEMENT DESIGN .......................................................................................... 9
DESIGN AND CONSTRUCTION SUPPORT SERVICES .......................................................... 12
LIMITATIONS ............................................................................................................................. 12
FIG. 1 – LOCATION OF EXPLORATORY BORINGS
FIG. 2 – LOGS OF EXPLORATORY BORINGS
FIGS. 3 through 6 – SWELL-CONSOLIDATION TEST RESULTS
FIG. 7 – GRADATION TEST RESULTS
TABLE I – SUMMARY OF LABORATORY TEST RESULTS
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SUMMARY
1. The field exploration program for the project was performed on March 3, 2020. Five (5)
widely-spaced exploratory borings were drilled to depths ranging from about 10 to 35 feet.
All of the exploratory borings encountered a thin layer of topsoil at the ground surface.
Boring 1 encountered approximately 1.5 feet of natural lean clay overburden soils
overlying sandstone bedrock. The bedrock was moderately to strongly cemented and
resulted in practical auger refusal at a depth of about 9.5 feet. Borings 2 through 5
encountered approximately 16.5 to 22.5 feet of natural overburden, which was in turn
underlain by sandstone bedrock. The sandstone bedrock continued to the explored
depths ranging from about 30 to 35 feet. Borings 2 and 3 encountered an approximate 6-
foot thick lens of clayey gravel immediately above the sandstone bedrock.
Groundwater was encountered in three of the borings at the time of drilling at depths
ranging from about 12 to 20 feet below the ground surface. Stabilized groundwater level
measurements were taken 14 days subsequent to drilling in four of the borings. Those
measurements indicated water was present at depths ranging from about 15.5 to 21.5 feet
below the ground surface.
2. Expansive native clay materials were encountered in some of the borings within the
anticipated building footprint areas extending to depths as great as about 24 feet below
existing grades. Mitigation measures to lower the risk of post-construction heave-related
distress due to expansive soils are recommended herein.
3. With proper subgrade preparation, shallow spread footing foundations and slab on grade
floors should be feasible provided they are supported as recommended herein. Allowable
soil bearing pressures ranging from 2,000 to 3,000 psf should be feasible depending on
foundation subgrade conditions and settlement considerations. Post-tensioned
foundations are also a feasible alternative.
4. Preliminary pavement thickness design for the proposed pavements at the site are
provided herein.
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PURPOSE AND SCOPE OF STUDY
This report presents the results of a preliminary geotechnical engineering study performed for the
proposed Maverick Apartments development to be constructed north of West Fairway Lane and
west of College Avenue in Fort Collins, Colorado. The project site is shown on Fig. 1. The study
was conducted to characterize general subsurface conditions and to provide preliminary
geotechnical engineering recommendations to be used for planning purposes. The study was
conducted in general accordance with the scope of work in our Proposal No. P3-20-146 to Jensen
LaPlante Development dated February 25, 2020.
A field exploration program consisting of five (5) exploratory borings was conducted to obtain
information on general subsurface conditions. Samples of the soils obtained from the exploratory
borings were tested in the laboratory to determine their swell-consolidation potential,
classification, and general engineering characteristics. The results of the field exploration and
laboratory testing programs were used to evaluate site geotechnical conditions and develop
preliminary geotechnical engineering recommendations.
This report has been prepared to summarize the data obtained during this study and to present
our conclusions and preliminary recommendations based on our understanding of the proposed
construction and the subsurface conditions encountered. Preliminary geotechnical design
parameters and a discussion of geotechnical engineeri ng considerations related to construction
of the proposed development of the site are presented herein.
PROPOSED DEVELOPMENT
We have been provided with a site plan showing a conceptual layout for the site development. In
general, we understand that a series of 2- to 3-story apartment structures will be constructed on
the site with a network of private roadways in and around the structures. The conceptual site plan
indicates that a clubhouse and below ground swimming pool will also be constructed near the
center of the site.
If the proposed construction varies significantly from that described above or depicted in this
report, we should be notified to reevaluate the recommendations provided in this report.
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SITE CONDITIONS
The project site is an approximately 10-acre, nearly rectangular-shaped undeveloped property.
The site is bounded on the north by the existing Spradley Barr Ford Motors dealership, on the
west by Fossil Boulevard, on the east by College Avenue, and on the south by West Fairway
Lane. Although no structures were present at the time of our field investigation, historical imagery
research indicates a farm house with several outbuildings once occupied portions of the site as
recently as the year 1999.
The site was vegetated with native grasses with a number of mature evergreen and deciduous
trees. The site slopes gently down to the south and east with a maximum elevation difference
across the site of about 20 feet.
SUBSURFACE CONDITIONS
The field exploration program for the project was performed on March 3, 2020. Five (5) widely-
spaced exploratory borings were drilled to depths ranging from about 10 to 35 feet. The
approximate locations of the exploratory borings are shown on Fig. 1. The elevations of the
exploratory borings were not determined. Logs of the exploratory borings are presented on Fig.
2 along with an associated legend and explanatory notes.
The borings were advanced with 4-inch-diameter, continuous-flight, solid-stem augers and were
logged by a representative of Kumar & Associates, Inc. (K+A). Samples of the overburden soils
were obtained with a 2-inch I.D. California-liner sampler driven into the various strata with blows
from a 140-pound hammer falling 30 inches. Sampling with the California-liner sampler is
generally similar to the standard penetration test procedure described by ASTM Method D1586.
Penetration resistance values, when properly evaluated, indicate the relative density or
consistency of the soils. Depths at which the samples were obtained and the associated
penetration resistance values are shown adjacent to the boring logs on Fig. 2.
Subsurface Soil Conditions: All of the exploratory borings encountered a thin layer of topsoil at
the ground surface. Boring 1 encountered approximately 1.5 feet of natural lean clay overburden
soils overlying sandstone bedrock. The bedrock was moderately to strongly cemented and
resulted in practical auger refusal at a depth of about 9.5 feet. Borings 2 through 5 encount ered
approximately 16.5 to 22.5 feet of natural overburden, which was in turn underlain by sandstone
bedrock. The sandstone bedrock continued to the explored depths ranging from about 30 to 35
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feet. Borings 2 and 3 encountered an approximate 6-foot thick lens of clayey gravel immediately
above the sandstone bedrock.
The natural overburden soils generally consisted of lean clay to sandy lean clay to clayey sand
with variable fine- to coarse-grained sand content, and were calcareous in places, moist to very
moist, and light brown to brown. Gravel up to about 2 inches were noted with increasing frequency
with increased depth below the ground surface. Based on standard penetration resistance
values, the overburden soils had consistencies ranging from very stiff to hard.
Sandstone bedrock encountered in the borings had a fine- to medium-grained sand fraction.
Based on standard penetration resistance values taken in the borings, the bedrock ranged from
hard to very hard. As noted earlier, the sandstone ranged from weak to strong cementation.
Groundwater was encountered in three of the borings at the time of drilling at depths ranging from
about 12 to 20 feet below the ground surface. Stabilized groundwater level measurements were
taken 14 days subsequent to drilling in four of the borings. Those measurements indicated water
was present at depths ranging from about 15.5 to 21.5 feet below the ground surface.
LABORATORY TESTING
Samples obtained from the exploratory borings were visually classified in the laboratory by the
project engineer. Laboratory testing was performed on selected samples, including evaluation of
in-situ moisture content and dry unit weight, grain size, liquid and plastic limits, swell-consolidation
behavior, and remolded swell-consolidation behavior. Moisture density relationships (standard
Proctors) were also performed on composite bulk samples. The above tests were performed in
accordance with the corresponding ASTM International standard test procedures. The
percentage of water-soluble sulfates was determined in general accordance with the CDOT CP -
L2103 test procedure. The results of the laboratory tests are shown to the right of the logs on
Fig. 2, plotted graphically on Figs. 3 through 7, and summarized in Table I.
Swell-Consolidation: Swell-consolidation tests were conducted on samples of the native clay in
order to determine their compressibility and swell characteristics under loading and when
submerged in water. Each sample was prepared and placed in a confining ring between porous
discs, subjected to a surcharge pressure of 200 psf or 1,000 psf, and allowed to consolidate
before being submerged in water. The samples were then inundated with water, and the change
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in sample height was measured with a dial gauge. Samples were then loaded incrementally to
maximum surcharge pressures ranging from 3,000 to 10,000 psf. The sample height was
monitored until deformation practically ceased under each load increment.
Results of the swell-consolidation tests are presented on Figs. 3 through 6 as plots of the curve
of the final strain at each increment of pressure against the log of the pressure. Based on the
results of the laboratory swell-consolidation testing, the samples of native clay generally exhibited
low to high swell potential.
Index Properties: Samples were classified into categories of similar engineering properties in
general accordance with the Unified Soil Classification System. This system is based on index
properties, including liquid limit and plasticity index and grain size distribution. Values for moisture
content and dry unit weight, liquid limit and plasticity index, and the percent of soil retained on the
U.S. No. 4 sieve and percent of soil passing No. 200 sieve are presented in Table I and adjacent
to the corresponding sample on the boring logs. Gradation tests results are presented on Fig.7.
WATER-SOLUBLE SULFATES
Concentrations of water-soluble sulfates measured in two samples of the native clay overburden
soils was 0%. These concentrations represent a Class S0 exposure to sulfate attack on concrete
exposed to these materials. The degree of attack is based on a range of Class S0 (not
applicable), Class S1 (moderate), Class S2 (severe), and Class S3 (very severe) severity of
exposure as presented in ACI 201.2R-16.
Based on the laboratory test results, we believe special sulfate resistant cement will generally not
be required for concrete exposed to the natural on-site soils.
GEOTECHNICAL ENGINEERING CONSIDERATIONS
Expansive Soil Considerations: Expansive native clay materials were encountered in most of the
borings within the anticipated building footprint areas extending to depths as great as about 23
feet below existing grades. Additionally, bedrock is relatively deep across the site, with the
exception of the area located near Boring 1. Groundwater was also relatively deep. While the
risk of significant movement due to swelling soils is anticipated to be relatively low, there is still a
risk for heave-related movements. The recommendations provided herein address this potential
risk.
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Shallow foundations and slabs-on-grade placed on or near the expansive soils will be prone to
heave from post-construction increases in the moisture content of these materials, potentially
resulting in movement in excess of normally accepted tolerances and associated architectural
and structural distress. The safest foundation system for the buildings ordinarily would be drilled
piers bearing in the bedrock, with structurally-supported floor systems above a crawl space.
However, due to the anticipated size of the proposed buildings, and the depth to bedrock,
construction of drilled piers and structurally-supported floor systems above a crawl space would
likely be cost prohibitive.
Based on our experience, we believe that a combination of shallow foundations and slab-on-
grade floor systems or post-tensioned slabs supported on a zone of moisture-conditioned fill
should be a feasible and cost-effective alternative to deep foundation and structural floor systems.
Acceptable performance of shallow foundations and slab-on-grade floors will rely on minimizing
water infiltration into the underlying expansive soils by providing good surface and subsurface
drainage, and using prudent landscaping and irrigation practices. In choosing shallow foundations
and slab-on-grade floor systems, the owner should understand and accept the risk of pot ential
distress resulting from some foundation and slab movement due to ground heave even though
mitigation measures are used to reduce that risk.
The amount of risk and associated potential heave if the expansive soils should become wetted
should be evaluated during the design-level geotechnical engineering study of the individual
buildings/lots.
SITE GRADING AND EARTHWORK
Temporary Excavations: Temporary excavations should be constructed in accordance with
OSHA requirements, as well as state, local and other applicable requirements. All excavations
greater than 4 feet and less than 20 feet in depth should be constructed in accordance with the
applicable OSHA guidelines. OSHA requires excavations or trenching over 20 feet deep be
designed by a registered professional engineer.
Site excavations will generally encounter native clayey soils. The clay soils should classify as
OSHA Type B soils although some granular lenses may classify as OSHA Type C soils. Bedrock
could classify as Type A soil, although fractured and weathered bedrock, and weakly- to
moderately-cemented sandstone bedrock, will classify as Type B and, in some cases, Type C
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soils. Excavations encountering loose granular soils could require much shallower side slopes
than those allowed by OSHA and/or temporary shoring. Although not anticipated, excavations
below groundwater, or where perched water exists and seeps into the excavation, could also
require much flatter side slopes than those allowed by OSHA.
Excavated slopes in the native soils may loosen or soften due to construction traffic and erode
from surface runoff. Measures to keep surface runoff from excavation slopes, including diversion
berms, should be considered.
Structural Fill Materials: Structural fill placed beneath buildings, pavements, and movement-
sensitive flatwork should consist of on-site overburden soils or low plasticity fill materials imported
to the site. Fill imported to the site should consist of non-expansive to low-swelling materials with
a maximum of 75 percent passing the No. 200 sieve, a maximum liquid limit of 35, and a maximum
plasticity index of 15. Also, the swell potential of imported fill materials, when remolded to 95%
of the standard Proctor (ASTM D698) maximum dry density at optimum moisture content, should
be less than 1/2% when wetted under a 200 psf surcharge pressure. Structural fill material should
also be free of claystone bedrock fragments. Based on laboratory testing, the majority of the on-
site soils are generally expected meet the requirements for non-expansive to low-swelling fill when
moisture conditioned and compacted according to the criteria recommended herein.
Prior to fill placement, the ground surface underlying all new fills should be cleared of all
vegetation, scarified and moisture conditioned to a depth of 12 inches and recompacted to provide
a uniform base for fill placement.
The design-level geotechnical study should provide detailed recommendations for fill placement,
including the evaluation of the suitability of the on-site native soils or imported fill materials as
structural fill beneath foundations and slab-on-grade.
Compaction Requirements: Structural fill materials placed at the site should generally be
compacted to at least 95 percent of the standard Pr octor (ASTM D698) maximum dry density.
Structural fill placed beneath footings should be compacted to at least 98 percent of the standard
Proctor (ASTM D698) maximum dry density. Fill materials should be compacted at moisture
contents within 2 percentage points of optimum for granular soils and between 0 and +3
percentage points of optimum for clay soils.
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Additional fill compaction requirements may be necessary depending on the final site grading and
building layout, and for any below-ground structures. The design-level geotechnical study should
include detailed recommendations for fill placement if extensive grading and/or deep replacement
fills are planned.
PRELIMINARY FOUNDATION CONSIDERATIONS
Spread Footing Foundations: Provided the risk of some foundation movement due to swelling of
the potentially expansive soil is acceptable to the owner, as discussed in the “Geotechnical
Engineering Considerations” section of this report, spread footing foundation systems should be
feasible suitable to support the proposed building(s). Spread footings should be supported on a
minimum of 4 feet of structural fill satisfying the material and placement requirements presented
in the “Site Grading and Earthwork” section of this report. Areas of loose native soils within a few
feet of the anticipated bottom of footing elevation may need to be removed and replaced with
structural fill. A final subsurface exploration program and geotechnical engineering study should
be performed to provide recommendations for swell potential mitigation. With proper subgrade
preparation, allowable net soil bearing pressures ranging from about 2,000 to 3,000 psf should
be feasible depending on subgrade conditions and settlement considerations. The amount
structural fill required below the foundation may increase or decrease upon the completion of a
design level geotechnical engineer study for specific buildings/lots.
Post tensioned slab foundations are also possible for the project site. Detailed analyses will need
to be performed during the design level study to provide the necessary design parameters.
FLOOR SLABS
As discussed in the “Geotechnical Engineering Considerations” section of this report, use of slab-
on-grade floors instead of structural floors will require a zone of structural fill beneath the slab,
which will require sub-excavation to depths dependent on planned site grading. Similar subgrade
preparation would be required for movement-sensitive exterior flatwork.
Preliminarily, floor slabs should be placed on a subslab fill zone consisting of minimum of 6 feet
of structural fill meeting the material and placement requirements presented in the “Site Grading
and Earthwork” section of this report. The amount of structural fill required below the floor slabs
may increase or decrease upon the completion of a design level geotechnical engineer study for
specific buildings/lots. Slab-supported elements of the buildings should be provided with slip
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joints and separated by expansion joints from foundation elements. Design of slab-on-grade
floors may need to consider inclusion of a sub-slab capillary break consisting possibly of free-
draining gravel, and a vapor barrier may need to be considered depending on building use.
SURFACE DRAINAGE
The ground surface surrounding the exterior of the buildings and movement-sensitive exterior
flatwork areas should be sloped to drain away from the structures and flatwork in all directions.
We recommend a minimum slope of 12 inches in the first 10 feet in unpaved areas. Site drainage
beyond the 10-foot zone should be designed to promote runoff and reduce infiltration. A minimum
slope of 6 inches in the first 10 feet is recommended in paved or flatwork areas. These slopes
may be changed as required for handicap access points in accordance with the Americans with
Disabilities Act. The probability of obtaining foundations and slab-on-grade floors that remain
stable for the life of the building will be significantly increased by planning a well -drained site
without excessive irrigation or storm water accumulation adjacent to buildings.
PRELIMINARY PAVEMENT DESIGN
A pavement section is a layered system designed to distribute concentrated traffic loads to the
subgrade. Performance of the pavement structure is directly related to the physical properties of
the subgrade soils and traffic loadings. Soils are represented for pavement design purposes by
means of a resilient modulus for flexible pavements and a modulus of subgrade reaction for rigid
pavements.
Subgrade Materials: Based on the results of the field exploration and laboratory testing programs,
the soils anticipated to be at or near the pavement subgrade are anticipated to generally classify
as A-6 and A-7-6 with group indices ranging between 5 and 23 in accordance with the AASHTO
soil classification system. Soils classifying as A-6 and A-7-6 are generally considered to provide
poor subgrade support. For preliminary design purposes a resilient modulus value of 3,025 psi
was selected for flexible pavements, and a modulus of subgrade reaction of 34 pci was selected
for rigid pavements.
Design Traffic: Since anticipated traffic loading information was not available at the time of report
preparation, we assume traffic will be similar to traffic values used on similar projects. Based on
those values, an equivalent 18-kip daily load application (EDLA) of 10 was assumed for combined
automobile and heavier truck traffic areas including parking areas and fire lanes (light -duty
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pavement), an EDLA of 70 was assumed for truck traffic areas (medium-duty pavement) such as
loading docks and trash truck routes. The designer should verify which traffic loads are valid for
the project. If higher EDLA values are anticipated, the pavement sections presented in this rep ort
will have to be reevaluated.
Preliminary Pavement Thickness Design: Preliminary pavement thicknesses were determined in
accordance with the 1993 AASHTO pavement design procedures. For flexible pavement design,
initial and terminal serviceability indices of 4.5 and 2.0, respectively, were selected, with a
reliability of 85 percent. If other design parameters are preferred, we should be contacted in order
to reevaluate the recommendations presented herein . A preliminary pavement thickness design
was completed for both a 10- and a 20-year pavement design life.
Preliminary 10-Year Design Life Minimum Pavement Thickness Recommendations
Pavement Type
Composite HMA/ABC
Pavement Section
(in)
Full-depth HMA
Pavement Section
(in) PCCP Section (in)
Light-duty 4.0 / 8.0 6.0 6.0
Medium-duty 5.5 / 9.0 8.0 7.0
20-Year Design Life Minimum Pavement Thickness Recommendations
Pavement Type
Composite HMA/ABC
Pavement Section
(in)
Full-depth HMA
Pavement Section
(in) PCCP Section (in)
Light-duty 4.5/8.0 7.0 6.0
Medium-duty 5.5/12.0 9.0 8.0
HMA = Hot Mix Asphalt; ABC = Aggregate Base Course, PCCP = Portland Cement
Concrete Pavement
Pavement Materials: HMA and PCCP should meet the latest applicable requirements, including
the CDOT Standard Specifications for Road and Bridge Construction. We recommend HMA
placed for the project is designed in accordance with the SuperPave gyratory mix design method.
The mix should generally meet Grading S or SX requirements with a SuperPave gyratory design
revolution (NDESIGN) of 75. Asphalt mixes should have a PG 64-22 asphalt binder. PCCP should
meet CDOT Class P specifications and requirements, including matching the coarse aggregate
size to the presence of dowels, if used.
The concrete sections presented above are assumed to be un -reinforced. Providing dowels at
construction joints would help reduce the risk of differential movements between panel sections.
Providing a grid mat of deformed rebar within the concrete pavement section would assist in
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mitigating corner breaks and differential panel movements. If a rebar mat is installed, we
recommend the bars be placed in the lower half of the pavement section. On projects electing to
install rebar mats, we have commonly seen No. 4 rebar placed at 24 inch centers in each direction,
however we recommend a structural engineer evaluate the placement and spacing of rebar if
needed.
ABC materials should meet CDOT requirements for Class 6 aggregate base course
Subgrade Preparation: Pavement subgrade conditions are projected to include potentially
expansive native clays, which are a problem where present beneath pavements. Expansive soils
could result in potentially excessive heave when subjected to increases in moistur e.
The undisturbed native clay soils primarily exhibited low to high swell potential upon wetting. In
areas where the native clay soils are exposed at pavement subgrade, the subgrade soils should
be over-excavated to a depth of at least 2 feet, moisture-conditioned to a moisture content by
soils type as previously recommended herein, and recompacted to at least 95% of the standard
Proctor (ASTM D698) maximum dry density. Care should be taken to place the top 1 foot of
subgrade backfill at moisture contents that are not too moist, which could result in an unstable
subgrade.
Prior to placement of moisture-conditioned fill, the exposed fill subgrade should be thoroughly
scarified and well-mixed to a depth of 12 inches, adjusted to a moisture content within 2
percentage points of optimum, and compacted to 95% of the standard Proctor (ASTM D698)
maximum dry density. This will result in a total prepared subgrade thickness of at least 3 feet.
The pavement subgrade should also be proofrolled with a heavily-loaded pneumatic-tired vehicle.
Pavement design procedures assume a stable subgrade. Areas that deform excessively under
heavy wheel loads are not stable and should be removed and replaced to achieve a stable
subgrade prior to paving.
The native soils are relatively dry and will likely require significant amounts of water to raise the
moisture contents to within the recommended compaction moisture band.
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The owner should be aware that subexcavation and replacement will reduce but not eliminate
potential movement of pavements should moisture levels increase within the expansive soils
beneath the replacement fill.
Drainage: The collection and diversion of surface drainage away from paved areas is extremely
important to the satisfactory performance of pavement. Drainage design should provide for the
removal of water from paved areas and prevent the wetting of the subgrade soils. Joints should
be routinely inspected, and joints and cracks that develop after construction should be sealed to
reduce the potential for water to migrate through the pavement.
DESIGN AND CONSTRUCTION SUPPORT SERVICES
We recommend K+A be retained to provide observation and testing services to document the
intent of this report and the requirements of the grading plans are being followed during earthwork
operations, and to identify possible variations in subsurface conditions from those encountered in
this study so that we can re-evaluate our recommendations, if needed.
LIMITATIONS
The preliminary conclusions and recommendations submitted in this report are based upon the
data obtained from the widely-spaced exploratory borings drilled at the locations indicated on the
exploratory boring plan. Additional investigation must be conducted once building locations and
floor and site elevations have been determined to provide final recommendations. We
recommend on-site observation of site grading by a representative of the geotechnical engineer.
Swelling soils are present at the site. Such soils are stable at their natural moisture content but
will undergo high volume changes with changes in moisture content. The extent and amount of
perched water beneath the building site as a result of area irrigation and inadequate surface
drainage is difficult, if not impossible, to foresee.
The recommendations presented in this report are based on current theories and experience of
our engineers on the behavior of swelling soil in this area. The owner should be aware there is a
risk in constructing in an expansive soil area. Following the recommendations given by a
geotechnical engineer, careful construction practice and prudent maintenance by the owner can,
however, decrease the risk of foundation movement due to expansive soils.
JLB/as
cc: file, book
Kumar & Associates
Project No.: 20-3-128Project Name: Maverick Apartments PreliminaryDate Sampled: Date Received: Boring Depth (Feet)Gravel (%) Sand (%)Liquid Limit (%)Plasticity (%)1 1 3/6/20 13.7 112.5 1 32 67 34 23 0 A-6 (12) Sandy Lean Clay (CL)2 9 3/6/20 10.4 111.8 13 40 47 32 19 A-6 (5) Clayey Sand with Gravel (SC)3 1 3/6/20 15.6 96.7 82 48 28 A-7-6 (23) Lean Clay with Sand (CL)3 4 3/6/20 10.9 100.7 1 36 63 36 15 A-6 (7) Sandy Lean Clay (CL)4 4 3/6/20 12.3 101.0 83 35 21 A-6 (16) Lean Clay with Sand (CL)5 4 3/6/20 8.9 99.6 1 20 79 35 18 0 A-6 (13) Lean Clay with Sand (CL)Table ISample Location Gradation Atterberg LimitsDate TestedNatural Moisture Content (%)Natural Dry Density (pcf)Percent Passing No. 200 SieveMarch 3, 2020March 4, 2020Water Soluble Sulfates (%)AASHTO Classification (Group Index) Soil or Bedrock TypeSummary of Laboratory Test Results