HomeMy WebLinkAboutPOLESTAR VILLAGE - PDP220010 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORT400 North Link Lane | Fort Collins, Colorado 80524
Telephone: 970-206-9455 Fax: 970-206-9441
PRELIMINARY
GEOTECHNICAL INVESTIGATION
POLESTAR VILLAGE
FORT COLLINS, COLORADO
Prepared For:
J.R. ENGINEERING, LLC
2900 South College Avenue, Ste 3D
Fort Collins, Colorado 80525
Attention: Joey Frank
Project No. FC10101-115
November 18, 2021
TABLE OF CONTENTS
SCOPE .................................................................................................................. 1
SUMMARY OF CONCLUSIONS ........................................................................... 1
SITE DESCRIPTION ............................................................................................. 2
PROPOSED DEVELOPMENT ............................................................................... 3
SITE GEOLOGY .................................................................................................... 3
Alluvium ............................................................................................................. 3
Pierre Shale ....................................................................................................... 4
GEOLOGIC HAZARDS .......................................................................................... 4
Shallow Groundwater ......................................................................................... 4
Expansive Soils and Bedrock ............................................................................. 5
Existing Fill ......................................................................................................... 5
Seismicity ........................................................................................................... 6
Radioactivity ....................................................................................................... 6
FIELD AND LABORATORY INVESTIGATIONS .................................................... 7
SUBSURFACE CONDITIONS ............................................................................... 7
Existing Fill ......................................................................................................... 8
ESTIMATED POTENTIAL HEAVE ........................................................................ 8
DEVELOPMENT RECOMMENDATIONS .............................................................. 8
Over-Excavation................................................................................................. 8
Site Grading ....................................................................................................... 9
Utility Construction ........................................................................................... 10
Underdrain System .......................................................................................... 10
Pavements ....................................................................................................... 12
PRELIMINARY RECOMMENDATIONS FOR STRUCTURES ............................. 12
Foundations ..................................................................................................... 12
Slabs-on-Grade Floor Construction .................................................................. 13
Below-Grade Construction ............................................................................... 13
Surface Drainage ............................................................................................. 13
Water Soluble Sulfates ..................................................................................... 14
RECOMMENDED FUTURE INVESTIGATIONS .................................................. 14
LIMITATIONS ...................................................................................................... 15
FIGURE 1 – LOCATIONS OF EXPLORATORY BORINGS
FIGURE 2 – ESTIMATED GROUNDWATER DEPTH AND ELEVATION
FIGURE 3 – ESTIMATED BEDROCK DEPTH AND ELEVATION
FIGURE 4 – SUMMARY LOGS OF EXPLORATORY BORINGS
FIGURE 5 – CONCEPTUAL UNDERDRAIN DET AIL
APPENDIX A – LABORATORY TEST RESULTS
APPENDIX B – GUIDELINE SITE GRADING SPECIFICATIONS
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SCOPE
This report presents the results of our Preliminary Geotechnical Investigation for the
proposed Polestar Village Subdivision in Fort Collins, Colorado. The purpose of our
investigation was to ident ify geologic hazards that may exist at the site and to evaluate the
subs urface conditions to assist in planning and budgeting for the proposed development. The
report includes descriptions of site geology, our analysis of the impact of geologic conditions on
site development, a description of su bsoil, bedrock and ground water conditions found in
exploratory borings, and discussions of site development as influenced by geotechnical
considerations. The scope was described in a Service Agreement (CTL Project No. FC-21-
0445) dated August 12, 2021.
This report was prepared based upon our understanding of the development plans. The
recommendations are considered preliminary and can be used as guidelines for further
planning of development and design of gradi ng. We should be provided development and
grading plans for review to determine if additional inves tigation is merited, or if we need to
revise our recommendatio ns. Additional investigations will be required to evaluate depth of
over-excavation in a portion of the site and t o design building foundations and p avements. A
summary of our findings and recommendations is presented below. More detailed discussions
of the data, analysis, and r ecommendations are pres ented in the report.
SUMMARY OF CONCLUSIONS
1. The site contains geologic hazards that should be mitigated during planning and
development. No geologic or geotechnic al conditions were identified which
would preclude development of this site. Shallow groundwater, expansive
bedrock, undocumented fill, and regional issues of seismicity and radioactivity
are the primary geologic and geotechnical concerns pertaining to the
development of the site .
2. The soils encountered in the borings generally consisted of 8 to 11 feet of silty,
sandy clay or clayey sand. The upper 5 to 7 feet of soil in five borings was
judged to be fill. Weathered to competent claystone bedrock was encountered
below the overburden in all the borings extending to the depths explored.
3. The existing fill is of unknown age and origin, and presents risk of heave or
settlement. The fill could exist in areas not explored by the borings. We
recommend complete removal of the fill below structures.
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4. Groundwater was encountered in all the borings at depths of 4 to 22 feet.
Groundwater will likely affect planned development in much of the site.
Basements are not recommended without groundwater mitigation. Groundwater
will likely be encountered in deeper utility excavations. Dewatering should be
considered.
5. Samples of the sandy clay swelled nil to 3.7 percent when wetted. Claystone
samples swelled 1.9 to 7.8 percent. Drilled piers bottomed in bedrock are
generally recommended f or sites with high-swelling soil and bedrock. An option
that carries more risk but is often considered for such sites is over-excavation.
Over-excavation of at least 7 feet below current grade, or 4-feet below
crawlspace footings, can be considered if footing or pad-type foundations are
desired. Complete removal, moisture treatment and re-compaction of existing fill
is recommended where fill is encountered below structures . Further evaluation
of over-excavation depths is recommended when grading plans are available.
6. Pavement subgrade may be comprised of undocumented fill, sandy clay or
clayey sand and will need to be characterized through further exploration.
Mitigation for swell may be necessary in portions of the site. Typical mitigation
consists of moisture and/or chemical treatment of the subgrade soils. A
minimum of 12 inches of chemical treat ment (fly ash or lime) should be
expected. Pavement sections on the order of 4 to 6 inches of hot mix asphalt
over 8 inches of aggregate base course are anticipated for West Plum Street,
the parking areas and access drives . Portland cement concrete sections, if
planned, will likely need to be at least 6 inches thick.
SITE D ESCRIPTION
The 21.7-acre site is located between Orchard Place and West Elizabeth Street, east of
Overland Trail in Fort Collins, Colorado (Picture 1 and Figure 1). The Saddle Ridge Commons
PUD is to the west and residential s ubdivisions are to the north, east and south. The land is
currently and historically has been agricultural with crop land and grazing pasture. The
Pleasant Valley Lake Canal borders the property at the north, west, and south boundaries. The
Saddle Ridge retention pond is adjacent to the northwest corner of the site. Groundcover
consists of native grasses, weeds, and trees. The eastern third of the prop erty had irrigated
crops and the remaining two thirds were vacant and fallow.
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Picture 1: Google Earth Aerial November 2019
PROPOSED DEVELOPMENT
Conceptual s ite plans indicated a mixed-use site with single-family and multi-family
residences, a temple/place of worship, agricultural buildings, and a c ommunity center, all
served by buried utilities. There will be a local street, alleyways, and paved bike paths. A water
quality pond and a regional detention pond are planned at the north portion of the site.
SITE GEOLOGY
The geology of the site was investigated through review of mapping by Roger B. Colton
(Geologic Map of the Boulder-Fort Collins-Greeley Area, 1978). Geology was further evaluated
through review of conditions found in explorator y borings, and our experience in the area.
According to the referenced mappin g, the site is underlain by Slocum alluvium (Qs) and the
upper Pierre Shale (Kp).
Alluvium
Alluvium is deposited by moving water such as streams and rivers, typically containing
varying fractions of gravel, cobble, clay, silt, and fine sand. The Slocum alluvium often contains
calcium c arbonate-enriched soils and calcareous silt with pieces of limestone. Some of this
material is ev ident in the fill encountered in the borings.
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Pierre Shale
The overburden soils are underlain by the upper Pierre Shale unit consisting of sandy
shales separating sever al fine-grained sandstone members with gypsiferous seams. The Pierre
Shale is generally expansive claystone. Our borings generally confirm the mapped conditions.
GEOLOGIC HAZARDS
Our investigation identified several geologic and/or geotechnical hazards that must be
considered during the planning and development. None of the hazards identified will preclude
development of t he property. Development plans are preliminary.
Planning should consider the geologic and geotechnical hazards discussed below. The
hazards include shallow groundw ater, expansive soils and bedrock, undocumented fill, and
regional issues of seismicity and radioactivity . The hazards require mitigation which could
include avoidance, non-conflicting use or engineered design and construction during site
development. The following sections discuss each of the geologic hazards and associated
development concerns. Mitigation concepts are discussed below and in the DEVELOPMENT
RECOMMENDATIONS section of the report.
Shallow Groundwater
Groundwater was measured in all the borings at depths of 4 to 22 feet. A groundwater
monitoring study with monthly readings is currently underway. Depth to groundwater and
groundwater elevations are presented in F igure 2. Shallow groundwater will likely preclude
basement level construction for the site and should be expected in utility excavations.
Groundwater fluctuates seasonally and will be affected by the water level in the Pleasant Valley
Lake Canal, local precipitation, and the nearby retention pond. There may be other unknown
contributing sources to the groundwater levels on th e site.
Site grades should be adjusted, where possible, to avoid shallow groundwater. We
recommend 3 feet of separation (preferably 5 feet) between foundation elements and
groundwater . Subsurface drainage systems (e.g. underdrains and interceptor drains) can be
used to control shallow groundwater. Foundation drains should be a nticipated around
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crawlspace areas and should connect to a sump pit and pump or a grav ity outlet. Gr avity
outlets typically consist of pipes placed below sewer mains (i.e. underdrains) that lead to an
outfall. If a gravity outfall is not possible, pumping may be required.
Shallow gr oundwater will likely complicate site development activities such as utility
excavations. Contractors should be prepared to deal with soft, wet soils, shallow excavation
slopes below groundwater and dewatering. If drilled piers are considered, they will likely require
underwater concrete placement by pumped metho ds and/or casing.
Expansive Soils and Bedr ock
Colorado is a challenging loc ation to practice geotechnical engineering. The climate is
relatively dry, and the near-surface soils are typically dry and relatively stiff. These soils and
related sedimentary bedrock formations tend to react to changes in moisture conditions. Some
of the soils and bedrock swell as they increase in moisture and are called expansive soils.
Other soils can settle significantly upon wetting and are referred to as collapsing soils. Most of
the land available for d evelopment east of the Front Range is underlain by expansive clay or
claystone bedrock near the surface. The soils that exhibit collapse are more likely west of the
continental divide; however, both types of soils occur all over the state.
Covering the ground with houses, streets, driv eways, patios, etc., coupled with lawn
irrigation and changing drainage patterns, leads to an increase in subsurface moisture
conditions. As a result, some soil movement is inevitable. It is critical that precautions are
taken to increase the chances that the foundations, slabs-on-grade, flatwork, and pavements
will perform satisfactorily. Engineered planning, design and construction of the improvements
and drainage can mit igate, but not eliminate, the effects of expansive soils and bedrock.
The soils and bedrock at this site include sandy clay and claystone bedrock . Each of
these materials is expansive. The impact of expansive soils is typically reduc ed by using deep
foundations or ground modification (over -excavation).
Existing F ill
Existing fill of unknown age and origin was encountered in five of the borings to depths
of 5 to 7 feet. The fill is not considered suitable for structural support and should be removed.
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Seismicity
This area, like most of central Colorado, is subjec t to a low degree of seismic risk. No
indications of recent movements of any of the faults in the Larimer County area have been
reported in the available geologic literature. As in most areas of recognized low seismicity, the
record of the past earthquak e activity in Colorado is somewhat incomplete.
Based on the subsurface conditions encountered in the borings and our understanding
of the geology, the site class ifies as a Seismic Site Class C (2018 International Building Code).
Only minor damage to re latively new, properly designed and built buildings would be expected.
Wind loads, not seismic considerations, ty pically govern dynamic structural design in this area.
If it is determined that seismic site class is critical to the design, we can provide a proposal for
services to determine the site class based on a ge ophysical study.
Radioactivity
It is normal in the Front Range of Colorado and nearby eastern plains to measure radon
gas in poorly ventilated spaces in contact with soil or bedrock. Rad on 222 gas is considered a
health hazard and is one of several radi oactive products in the chain of the natura l decay of
uranium into stable lead. Radioactive nuclides are common in the soils and sedimentary rocks
underlying the subject site. Because these sources exist on most sites, there is potential for
radon gas accumulation in poorly ventilated spaces. The amount of soil gas that can
accumulate is a function of many factors, including the radio-nuclide activity of the soil and
bedrock, construction methods and materials, pathways for soil gas and existence of poor ly
ventilated accumulation areas. It is dif ficult to predict the concentration of radon gas in finished
construction.
We recommend testing to evaluate radon levels after construction is completed. If
required, typical mitigation methods for residential construction consist of sealing soil gas entry
areas and ventilation of below-grade spaces and perimeter drain systems. It is relatively
economical to provide for ventilation of perimeter drain systems or underslab grav el layers at
the time of construction, compared to retrofitting a structure after construction.
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FIELD AND LABORATORY INVESTIGATIONS
Subsurface conditions were investigated by drilling eight exploratory borings (six of
which were converted to temporary piezometers) at the locations shown on Figure 1. The drill
locations were surveyed by the client. The borings were drilled using a truck-mounted drill rig
and with 4-inch diameter continuous-flight auger. Our field representative observed drilling,
logged the soils found in the bor ings, and obtained samples. Summary logs of the soils found
in the borings and field penetration r esistance values are presented on Figure 4.
Samples of soil and bedrock were obtained during drilling by driving a modified
California-type sampler (2.5-inch O.D.) into the subsoils and bedrock using a 140-pound
hammer falling 30 inches. Samples recovered from the test holes were returned to our
laboratory and visually classified by the geotechnical engineer. Laboratory testing included
determination of moisture content and dry density, swell-consolidation characteristics, Atterberg
limits, particle-size analysis, unconfined compressive strength, and water-soluble sulfate
content. Laboratory test results are presented in Appendix A.
SUBSURFACE CONDITIONS
The soils encountered in the borings generally consisted of 8 to 11 feet of silty, sandy
clay or clayey sand. The upper 5 to 7 feet of soil in five borings was judged to be fill.
Weathered to com petent claystone b edrock was encountered below the overburden in all the
borings extending to the depths explored. Depth to bedrock and bedrock elevations are
presented in F igure 3. The sandy clay was stiff, and the claystone was medium hard to hard
according to standard penetration tests. Samples of the clay tested for swell-consolidation
exhibited nil to 3.7 percent swell potential when wetted under approximate overburden
pressures . The claystone exhibited 1.9 to 7.8 percent swell potential.
Groundwater was measured in all the borings at depths of 4 to 22 feet. A groundwater
monitoring study with monthly readings is currently underway. Depth to groundwater and
groundwater elevations are presented in F igure 2. Groundwater fluctuates seasonally and will
be affected by the water level in the Pleas ant Valley Lake Canal, local precipitation, and the
nearby retention pond.
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Existing Fill
Existing fill was encountered in five borings to depths of 5 to 7 feet. The fill generally
consisted of silt, sand, clay, grav el, and miscellaneous debris. Deeper fill may be encountered
in areas not explored by our borings. The fill was predominantly granular material and
considered non-expansive but may pose a risk of settlement under structure loads.
ESTIMATED POTENTIAL HEA VE
Based on the subsurface profiles, swell-consolidation test results, and our experience,
we calculated potential heave at the ground surface. Heave at the ground surface was
estimated at 4.7 inches to 7.9 inches. These are estimates based on sparsely coll ected data;
more or less heave c ould occur. A depth of wetting of 24 feet below the ground surface was
consider ed for the heave evaluations. Research by Walsh, Colby, Houston and Houston 1
indicates there is a 90 percent probability that the wetting depth will not exceed 24 feet for this
region, suggesting the risk of ground heave exceeding the estimated values is l ow.
DEVELOPMENT RECOMMENDATIONS
Appropriate planning, design and construction will be necessary to address the
aforementioned hazards. Adjust ing site grades, use of non-basement residences and
installation of active underdrain systems could mitigate shallow groundwater issues. Removal,
moisture tr eatment and re-compaction (over-excavation) of expansive soils and undocumented
fill should lower r isk of damage to improvements. The following sections discuss site
development considering the current developm ent plan.
Over-Excavation
Expansive soils and bedrock were encountered in the investigation. Swelling soils and
undocumented fill pose a risk to the performance of improvements built at the site. Drilled pier
foundations and structural floors are generally recomme nded for residences constructed over
high swelling soils and bedrock where bedrock is relatively shallow. Over-excavation, moisture
1”Method for Evaluation of Depth of Wetting in Residential Areas” by Walsh, Colby, Houston and Houston, Journal of Geotechnical
and Geoenvironmental Engineering, ASCE February 2009.
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treatment and compaction may reduce the risk of poor foundation and floor slab performance
and allow use of footing foundations and slab-on-grade basement floors. Over-excavation does
not guarantee a non-expansive site, but if done correctly, it can reduce the magnitude of
potential movements and risk of damage created by expansive soil. We estimate over-
excav ation should extend to a minimum depth of 7 feet below current grade or 4 feet below
crawlspace level footings and slabs. Additional evaluation is recommended when grading
plans are available and to assess over-excavation depths .
A representative of our firm should observe and test compaction of the fill on a nearly
full-time basis. Design-level geotechnical investigations for individual lots should include swell
testing of t he fill placed during over-excavation. The over-excavation limits and depth should
be surveyed by a surveyor and “as -built” plans should be prepared. The “as-built” over-
excavation plans should be provided to sales and construction staff for proper selection of
models and siting houses inside the over-excavation limits.
Over-excavation does not produce a non-swelling site. The degree of success is
dependent on contrac tor procedures in processing and moisture conditioning the soils. The
process is slower than “normal” cut/fill operations and requires an experienced contractor and
nearly full-time observation/testing. If the fill dries excessively prior to building and pavement
construction, it m ay be necessary to rework the drier materials just prior to paving and/or
installing foundations.
Site Grading
Site grading plans were not availa ble for review in conjunction with this subsurface
exploration program. Fill compacted in accordance with the compaction recommendations in
this report may settle about 1 percent of its depth under its own weight. Most of this settlement
usually occurs during and soon after construction. Some additional settlement is possible after
development and landscape irrigation increases soil moisture. We recommend delaying the
construction of buildings underlain by deep f ills as long as possible to allow for this settlement
to occur.
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The exis ting on-site soils are suitable for re-use as fill mater ial provided debris or
deleterious organic materials are removed. Guideline moisture and compaction
recommendations are provided in Appendix B.
Utility Construction
We believe excavations for utility installation can be performed with conventional heavy-
duty trenchers or large backhoes. If groundwater is encountered dur ing construction,
dewatering may be accomplished by sl oping excavations to occasional sumps where water can
be removed by pumping.
Utility trenches should be sloped or shored to meet local, State, and federal safety
regulations. Based on o ur investigation, we believe the native clay may classify Type B, the fill
as Type C soil based on OSHA standards. Claystone bedrock, if encountered, may classifies
as Type A or B where weathered. Excavation slopes specified by OSHA are dependent upon
soil types and groundwater conditions encountered. Seepage and groundwater conditions in
trenches may downgrade the soil type . Contractors’ “qualified person” should identify the soils
encountered in the excavations and refer to OSHA standards to determine appropriate slopes.
Exc avations deeper than 20 feet should be designed by a professional engineer.
Water and sewer lin es are usually c onstructed beneath paved roads. Compaction of
trench backfill can have significant effect on the life and s erviceability of pavements. We
believe trench backfill should be placed in thin, loose lifts, and moisture conditioned to between
optimum and 3 percent above optimum content for clay soils and within 2 percent of optimum
moisture content for sand. Trench backfill should be compacted to at least 95 percent of
maximum dry density (ASTM D 698). The placement and compaction of fill and backfill should
be observed and tested by our firm during construction. If deep excavations are necessary for
planned utilities, the compaction requirements provided in Appendix D should be considered.
Underdrain System
The use of underdrain systems b elow sewer mains and services is a common method to
control ground water. We generally advocate an underdrain system be incorporated into
sanitary sewer and sewer collection systems where a gravity outlet is possible. If underdrains
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are installed, they should also be extended below sewer service lines to each r esidence to
allow connection to residence foundation drains .
The underdrains s hould consist of free-draining gravel surrounding a rigid PVC pipe.
The pipe should be sized for anticipated flow. Guidelines for underdrain sizing are shown i n
Table 1. T he line should consist of smooth, perforated or slotted rigid PVC pipe laid at a grade
of at least 0.5 percent. A gravel cross-section of at least 2 square feet should be placed around
the pipe. A positive cutoff collar (concrete) should be constructed around the sewer pipe and
underdrain pipe im mediately downstream of the point the underdrain pipe leaves the sewer
trench. Solid pipe should be used down gradient of this collar to the daylight point. Clean-outs
should be provided along the system. The entity responsible for maintenance should be
identified and guidelines d eveloped for maintenance. The underdrain should be designed to
discharge to a gravity outfall provided with a permanent concrete headwall and trash rack, or to
a storm sewer with a check valve to control water backing up into t he underdrain system. The
underdrain system should be designed by a professional engineer that is licensed in the State
of Colorado. We have provided a conceptual underdrain detail on Figure 5.
TABLE 1
UNDERDRAIN SIZING
Slope = 0.005 (0.5 percent)
Pipe Size (inches) 4 6 8
Maximum Number of Residences 50 100 200
Slope = 0.01 (1.0 percent)
Pipe Size (inches) 4 6 8
Maximum Number of Residences 75 150 300
Slope = 0.02 (2.0 percent)
Pipe Size (inches) 4 6 -
Maximum Number of Residences 100 300 -
Note: Minimum slopes of the underdrains will g overn pipe sizes and maximum number of residences serviced.
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Pavements
Pavement subgrade may be comprised of undocumented fill, sandy clay or clayey sand
and will need to be characterized through further exploration. Recommendations will be guided
by Larimer County Urban Area Street Standards (LCUASS) for minimum pavement
requirements. Clay soils are considered to have relatively poor support characteristics. Soft
subgrade may necessitat e chemical (lime or cement) or mechanical stabilization. Mitigation for
swelling soils may be required. We anticipate minimum pavement sections of 4 to 6 inches of
hot mix asphalt (HMA) over 8 inches of aggregate base course (ABC) will likely be necessary
for the local residential street , access drives and alleyways.
Portland cement concrete (PCC) pavement is recommended in areas subject to heavy
truck traffic such as garbage pickup and/or dumpster trucks and any heavy delivery trucks. A
minimum 6-inch thick section is anticipated in main drives and any areas subject to some
moderately heavy truck tr affic. Any areas subject to frequent heavy trucks should be designed
bas ed on frequency and wheel loads. A design-level subgrade investigation should be
performed prior t o paving and when the subgrade is within 6 inches of final grade.
PRELIMINARY RECOMMENDATIONS FOR STRUCTURES
The property is currently planned for single-family and multi-family residential
construction with some light commercial constructi on. Because of the shallow groundwater, we
do not recommend basem ent construction. The following discussions are preliminary and are
not intended for design or construction. After gr ading is completed, a detailed soils and
foundation investigation should be performed.
Foundations
Drilled pier foundations are typically recommended for sites where high-swelling,
shallow be drock exists. Shallow groundwater will likely make drilled piers difficult to install and
cost prohibitive to development. Over-excavation can be considered to allow use of footings or
pads.
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Slabs-on-Grade Floor Construction
The use of slab-on-grade floors should be limited to areas where the risk of poor
performance is low or moderate, or where over-excavation has been performed. Slab
performance risk should be more t horoughly defined during the design level soils and
foundation investigations .
Below-Grade Construction
Groundwater was encountered during this investigation at depths of 4 to 22 feet. We do
not rec ommend basement construction for this site unless ro bust drainage systems, such as
interc eptor drains and under drains, are incorporated into the development. To reduce the risk
of hydrostatic pressure developing on foundation walls, foundation drains will be necessary
around all below-grade areas. We suggest foundation drains be tied to the sewer underdrain
system (if installed). They may also discharge to sumps where water can be removed by
pumping. In our opinion, underdrain systems offer more comprehensive control of ground water
and better mitigate impacts of groundwater and swelling soils on foundations, slabs and
pavements. Foundation walls and grade beams should be designed to withstand lateral earth
pressures. The design pressure should be established during design-level soils investigations.
Surface Drainage
The performance of foundations will be influenced by surface drainage. Th e ground
surface ar ound proposed structures should be shaped to provide runoff of surface water away
from the structure and off of pavements. We generally recommend slopes of at least 12 inches
in the first 10 feet where practical in the landscaping areas surrounding residences. There are
practical limitations on achieving these slopes. Irrigation should be minimized to control
wetting. Roof downspouts should discharge beyon d the limits of backfill. Water should not be
allowed to pond on or adjacent to pavements. Proper control of surface runoff is also important
to limit the erosion of surface soils. Sheet flow should not be directed over unprotected slopes.
Water should not be allowed to pond at the crest of slopes. Permanent slopes should be re-
vegetated to r educe erosion.
Water can flow though poorly compacted fill behind curb and gutter and in utility
trenches. This water can soften fill and undermine the performance of the roadways, flatwork
and foundations. We recom mend compactive effort during placement of all fill.
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Water Soluble Sulfates
Concrete that comes into contact with soils can be subject to sulfate attack. We
measured water-soluble sulfate concentrations in three samples from this site. Concentrations
were measured between below measurable limits and 0.17 percent, with one sample having
sulfate concentration between 0.1 and 0.2 percent. For this level of sulfate concentration, ACI
332-08 Code Requirements for Residential Concrete indicates concrete shall be made with
ASTM C150 Type II cement, or an ASTM C595 or C1157 hydraulic cement meeting moderate
sulfate-resistant hydraulic cement (MS) designation.
Superficial damage may occur to the exposed surfaces of highly perm eable concrete.
To control this risk and to resist freeze-thaw deterioration, the water-to-cementitious materials
ratio should not exceed 0.50 for concrete in contact with soils that are likely to stay moist due to
surface drainage or high-water tables. Concrete should have a total air content of 6 percent ±
1.5 percent. We advocate all foundation walls and grade beams in contact with the soils
(including the inside and outside faces of garage and crawlspace grade beams) be damp -
proofed.
RECOMMENDED FUTURE INVESTIGATIONS
Based on the results of this investigation and the prop osed development, we
recommend the following investigations be performed:
1. Review of site grading plans by our firm;
2. Additional ev aluation of over-excavation depths;
3. Evaluation of potential subs urface drainage systems;
4. Construction testing and observation during site development including
compaction testing of grading fill and/or fill placed for over-excavation, utility
trench backfill and pavements;
5. Subgrade investigation and pavement design after site grading is complete;
6. Design-level s oils and foundation investigations after grading; and
7. Observation of foundation drain and foundation construction.
J.R. ENGINEERING, LLC 15
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
LIMITATIONS
The exploratory borings were located to obtain preliminary subsoil data indicative of
conditions on this site. Variations in the subs oils not indicated by the borings are possible. We
believe this investigation was conducted in a manner consistent with that level of skill and care
ordinarily used by members of the profession currently practicing under similar conditions in the
locality of this project. No warranty, express or implied, is made.
This report was prepared from data developed during our field exploration, laboratory
testing, engineering analysis and experience with similar conditions. The recommendations
contained in this report were based upon our und erstanding of the planned construction. If
plans change or differ from the assumptions presented herein, we should be contacted to
review our recommendations.
If we can be of further service in discussing the contents of this report or in the analysis
of the project development from the geotechnical point of view, pleas e call.
Very truly yours,
CTL | THOMPSON, INC.
Trace Krausse, EIT R.B. ”Chip” Leadbetter III, P.E.
Project Geotechnical Engineer Senior Geotechnical Engineer
TSK:RBL
P-1
P-2 P-3
P-4
P-5
P-6
TH-1
TH-2
W. Elizabeth Street
W. Plum Street
Orchard Place
Kimball RoadOVERLAND TRAILTAFT HILL RD.W. MULBERRY ST.
W. ELIZABETH ST.
SITE
LEGEND:
INDICATES APPROXIMATE
LOCATION OF TEMPORARY
PIEZOMETER
INDICATES APPROXIMATE
LOCATION OF EXPLORATORY
BORING
P-1
TH-1
J.R.ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL I T PROJECT NO. FC10101-115 FIGURE 1
Locations of
Exploratory Borings
VICINITY MAP
FORT COLLINS, COLORADO
NOT TO SCALE
300'
APPROXIMATE
SCALE: 1" = 300'
150'0'
P-1
P-2 P-3
P-4
P-5
P-6
TH-1
TH-2
W. Elizabeth Street
W. Plum Street
Orchard Place
Kimball Road(18.5)
(4.5)
(22)(10)
(21.5)
(3.5)
(20.5)
(22.5)
[5097.8]
[5106.7]
[5089.8][5096.0]
[5115.1]
[5091.0]
[5088.3]
[5095.0]
LEGEND:
INDICATES APPROXIMATE
LOCATION OF TEMPORARY
PIEZOMETER
INDICATES APPROXIMATE
LOCATION OF EXPLORATORY
BORING
INDICATES ESTIMATED DEPTH TO
GROUNDWATER IN FEET
INDICATES ESTIMATED GROUND
WATER SURFACE ELEVATION
P-1
(10)
TH-1
[5096]
J.R.ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL I T PROJECT NO. FC10101-115 FIGURE 2
Groundwater Depth
and Elevation
300'
APPROXIMATE
SCALE: 1" = 300'
150'0'
P-1
P-2 P-3
P-4
P-5
P-6
TH-1
TH-2
W. Elizabeth Street
W. Plum Street
Orchard Place
Kimball Road(7)
[5109.3]
(11)
[5100.8]
(5.5)
[5100.5]
(11)
[5099.8]
(12)
[5103.5]
(10.5)
[5108.1]
(8)
[5103.2]
(12)
[5100.5]
LEGEND:
INDICATES APPROXIMATE
LOCATION OF TEMPORARY
PIEZOMETER
INDICATES APPROXIMATE
LOCATION OF EXPLORATORY
BORING
INDICATES ESTIMATED DEPTH TO
BEDROCK IN FEET
INDICATES ESTIMATED GROUND
BEDROCK ELEVATION
P-1
TH-1
J.R.ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL I T PROJECT NO. FC10101-115 FIGURE 3
Bedrock Depth and
Elevation
300'
APPROXIMATE
SCALE: 1" = 300'
150'0'
[5103.2]
(8)
5,075
5,080
5,085
5,090
5,095
5,100
5,105
5,110
5,115
5,120
5,075
5,080
5,085
5,090
5,095
5,100
5,105
5,110
5,115
5,120
40/12
38/12
50/12
50/8
50/7
WC=14.1DD=121SW=4.4
WC=13.6DD=124SW=1.9
SS=0.170
P-1
El. 5116.3
39/12
42/12
50/10
50/9
50/9
WC=15.5DD=120SW=7.3
WC=13.1DD=124SW=2.8
WC=13.9DD=121-200=99UC=20,800
WC=14.3DD=124SW=2.1
P-2
El. 5111.8
14/12
44/12
39/12
32/12
50/9
WC=14.2DD=124SW=7.8
WC=15.3DD=118SW=4.5
P-3
El. 5106.0
50/10
20/12
50/8
50/11
50/7
WC=2.2-200=23SS=<0.01
WC=14.5DD=119SW=3.7
WC=13.3DD=126SW=3.9
WC=16.1DD=117SW=2.3
WC=14.8DD=125SW=3.3
P-4
El. 5110.8
25/12
35/12
50/9
50/9
50/8
WC=13.5DD=122SW=6.1
WC=13.9DD=121-200=100UC=17,250
WC=13.9DD=122SW=2.1
P-5
El. 5115.5
8/12
22/12
50/6
50/6
50/5
WC=17.0
-200=61
WC=13.1DD=120SW=0.0
LL=34 PI=18
P-6
El. 5118.6
11/12
50/12
50/12
50/9
50/7
WC=15.1
-200=44
WC=13.7DD=124SW=4.3SS=0.050
WC=15.3DD=120SW=2.0
LL=30 PI=14
TH-1
El. 5111.2
29/12
38/12
50/10
50/9
50/9
WC=14.8DD=122SW=3.1
WC=14.7DD=122
WC=14.6DD=124SW=3.3
WC=14.8DD=123SW=4.4
TH-2
El. 5112.5
ELEVATION - FEETFIGURE 4
DRIVE SAMPLE. THE SYMBOL 40/12 INDICATES 40 BLOWS OF A 140-POUND HAMMER FALLING
30 INCHES WERE REQUIRED TO DRIVE A 2.5-INCH O.D. SAMPLER 12 INCHES.ELEVATION - FEETWATER LEVEL MEASURED ON SEPTEMBER 24, 2021.
SAND, CLAYEY, MOIST, MEDIUM DENSE TO DENSE, RED-BROWN (SC)
2.
3.
FILL, GRAVEL, SAND, CLAY, SILT, MISC. DEBRIS, WHITE, PINK, GRAY, TAN
THE BORINGS WERE DRILLED ON SEPTEMBER 22, 2021, USING 4-INCH DIAMETER
CONTINUOUS-FLIGHT AUGERS AND A TRUCK-MOUNTED DRILL RIG.
1.
LEGEND:
NOTES:
CLAY, SANDY, MOIST, STIFF TO VERY STIFF, RED-BROWN, TAN (CL)
WEATHERED CLAYSTONE, SANDY, MOIST, FIRM TO MEDIUM HARD, RED-BROWN, TAN, GRAY
CLAYSTONE, SANDY, MOIST, MEDIUM HARD TO HARD, BROWN, GRAY, OLIVE
WATER LEVEL MEASURED AT TIME OF DRILLING.
BORING ELEVATIONS WERE SURVEYED BY A REPRESENTATIVE OF OUR FIRM REFERENCING
THE TEMPORARY BENCHMARK SHOWN ON FIGURE 1.
THESE LOGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND CONCLUSIONS IN THIS
REPORT.
4.
Summary Logs of
Exploratory Borings
WC
DD
SW
-200
LL
PI
UC
SS
-
-
-
-
-
-
-
-
INDICATES MOISTURE CONTENT (%).
INDICATES DRY DENSITY (PCF).
INDICATES SWELL WHEN WETTED UNDER OVERBURDEN PRESSURE (%).
INDICATES PASSING NO. 200 SIEVE (%).
INDICATES LIQUID LIMIT.
INDICATES PLASTICITY INDEX.
INDICATES UNCONFINED COMPRESSIVE STRENGTH (PSF).
INDICATES SOLUBLE SULFATE CONTENT (%).
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
SW=3.8
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
Conceptual Underdrain
Detail
FIGURE 5
APPENDIX A
LABORATORY TEST RESULTS
TABLE A-1: SUMMARY OF LABORATORY TEST RESULTS
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=121 PCF
From P - 1 AT 9 FEET MOISTURE CONTENT=14.1 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-1
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=124 PCF
From P - 1 AT 19 FEET MOISTURE CONTENT=13.6 %
J.R. ENGINEERING, LLC
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CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-2
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=120 PCF
From P - 2 AT 9 FEET MOISTURE CONTENT=15.5 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-3
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
8
9
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=124 PCF
From P - 2 AT 14 FEET MOISTURE CONTENT=13.1 %
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=124 PCF
From P - 2 AT 24 FEET MOISTURE CONTENT=14.3 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSF
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-4COMPRESSION % EXPANSION-4
-3
-2
-1
0
1
2
3
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
-4
-3
-2
-1
0
1
2
3
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
0.1 1.0 10 100
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=124 PCF
From P - 3 AT 9 FEET MOISTURE CONTENT=14.2 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-5
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
8
9
10
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=118 PCF
From P - 3 AT 14 FEET MOISTURE CONTENT=15.3 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-6
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=119 PCF
From P - 4 AT 9 FEET MOISTURE CONTENT=14.5 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-7
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=126 PCF
From P - 4 AT 14 FEET MOISTURE CONTENT=13.3 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-8
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=117 PCF
From P - 4 AT 19 FEET MOISTURE CONTENT=16.1 %
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=125 PCF
From P - 4 AT 24 FEET MOISTURE CONTENT=14.8 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSF
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-9COMPRESSION % EXPANSION-4
-3
-2
-1
0
1
2
3
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
-4
-3
-2
-1
0
1
2
3
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
0.1 1.0 10 100
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=122 PCF
From P - 5 AT 9 FEET MOISTURE CONTENT=13.5 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-10
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=122 PCF
From P - 5 AT 19 FEET MOISTURE CONTENT=13.9 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-11
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=120 PCF
From P - 6 AT 14 FEET MOISTURE CONTENT=13.1 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-12
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
NO MOVEMENT DUE TO WETTING
0.1 1.0 10 100
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=124 PCF
From TH - 1 AT 9 FEET MOISTURE CONTENT=13.7 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-13
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=120 PCF
From TH - 1 AT 14 FEET MOISTURE CONTENT=15.3 %
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=122 PCF
From TH - 2 AT 9 FEET MOISTURE CONTENT=14.8 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSF
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-14COMPRESSION % EXPANSION-4
-3
-2
-1
0
1
2
3
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
-3
-2
-1
0
1
2
3
4
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
0.1 1.0 10 100
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=122 PCF
From TH - 2 AT 14 FEET MOISTURE CONTENT=14.7 %
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=124 PCF
From TH - 2 AT 19 FEET MOISTURE CONTENT=14.6 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSF
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-15COMPRESSION % EXPANSION-3
-2
-1
0
1
2
3
4
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
-4
-3
-2
-1
0
1
2
3
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
0.1 1.0 10 100
Sample of CLAYSTONE, SANDY DRY UNIT WEIGHT=123 PCF
From TH - 2 AT 24 FEET MOISTURE CONTENT=14.8 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation
Test Results FIGURE A-16
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
Sample of SAND, CLAYEY (SC)GRAVEL 10 %SAND 67 %
From P - 4 AT 4 FEET SILT & CLAY 23 %LIQUID LIMIT %
PLASTICITY INDEX %
Sample of CLAY, SANDY (CL)GRAVEL 5 %SAND 42 %
From S - 1 AT 0-4 FEET SILT & CLAY 53 %LIQUID LIMIT 50 %
PLASTICITY INDEX 28 %
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
FIGURE A-17
Gradation
Test Results
0.002
15 MIN.
.005
60 MIN.
.009
19 MIN.
.019
4 MIN.
.037
1 MIN.
.074
*200
.149
*100
.297
*50
0.42
*40
.590
*30
1.19
*16
2.0
*10
2.38
*8
4.76
*4
9.52
3/8"
19.1
3/4"
36.1
1½"
76.2
3"
127
5"
152
6"
200
8"
.001
45 MIN.
0
10
20
30
40
50
60
70
80
90
100
CLAY (PLASTIC) TO SILT (NON-PLASTIC)SANDS
FINE MEDIUM COARSE
GRAVEL
FINE COARSE COBBLES
DIAMETER OF PARTICLE IN MILLIMETERS
25 HR.7 HR.
HYDROMETER ANALYSIS SIEVE ANALYSIS
TIME READINGS U.S. STANDARD SERIES CLEAR SQUARE OPENINGS
PERCENT PASSING0
10
20
30
50
60
70
80
90
100 PERCENT RETAINED40
0.002
15 MIN.
.005
60 MIN.
.009
19 MIN.
.019
4 MIN.
.037
1 MIN.
.074
*200
.149
*100
.297
*50
0.42
*40
.590
*30
1.19
*16
2.0
*10
2.38
*8
4.76
*4
9.52
3/8"
19.1
3/4"
36.1
1½"
76.2
3"
127
5"
152
6"
200
8"
.001
45 MIN.
0
10
20
30
40
50
60
70
80
90
100
CLAY (PLASTIC) TO SILT (NON-PLASTIC)SANDS
FINE MEDIUM COARSE
GRAVEL
FINE COARSE COBBLES
DIAMETER OF PARTICLE IN MILLIMETERS
25 HR.7 HR.
HYDROMETER ANALYSIS SIEVE ANALYSIS
TIME READINGS U.S. STANDARD SERIES CLEAR SQUARE OPENINGS
PERCENT PASSINGPERCENT RETAINED0
10
20
30
40
50
60
70
80
90
100
UNCONFINED PASSING WATER-
MOISTURE DRY LIQUID PLASTICITY APPLIED COMPRESSIVE NO. 200 SOLUBLE MAXIMUM OPTIMUM
DEPTH CONTENT DENSITY LIMIT INDEX SWELL*PRESSURE STRENGTH SIEVE SULFATES DENSITY MOISTURE
BORING (FEET)(%)(PCF)(%)(PSF)(PSF)(%)(%)(PCF)(%)DESCRIPTION
P-1 9 14.1 121 4.4 1,100 0.17 CLAYSTONE, SANDY
P-1 19 13.6 124 1.9 2,400 CLAYSTONE, SANDY
P-2 9 15.5 120 7.3 1,100 CLAYSTONE, SANDY
P-2 14 13.1 124 2.8 1,800 CLAYSTONE, SANDY
P-2 19 13.9 121 20,800 99 CLAYSTONE, SANDY
P-2 24 14.3 124 2.1 3,000 CLAYSTONE, SANDY
P-3 9 14.2 124 7.8 1,100 CLAYSTONE, SANDY
P-3 14 15.3 118 4.5 1,800 CLAYSTONE, SANDY
P-4 4 2.2 23 <0.01 SAND, CLAYEY (SC)
P-4 9 14.5 119 3.7 1,100 CLAY, SANDY (CL)
P-4 14 13.3 126 3.9 1,800 CLAYSTONE, SANDY
P-4 19 16.1 117 2.3 2,400 CLAYSTONE, SANDY
P-4 24 14.8 125 3.3 3,000 CLAYSTONE, SANDY
P-5 9 13.5 122 6.1 1,100 CLAYSTONE, SANDY
P-5 14 13.9 121 17,250 100 CLAYSTONE, SANDY
P-5 19 13.9 122 2.1 2,400 CLAYSTONE, SANDY
P-6 4 17.0 34 18 61 CLAY, SANDY (CL)
P-6 14 13.1 120 0.0 1,800 CLAY, SANDY (CL)
S-1 0-4 11.2 50 28 53 105.0 16.5 CLAY, SANDY (CL)
TH-1 4 15.1 30 14 44 SAND, CLAYEY (SC)
TH-1 9 13.7 124 4.3 1,100 0.05 CLAYSTONE, SANDY
TH-1 14 15.3 120 2.0 1,800 CLAYSTONE, SANDY
TH-2 9 14.8 122 3.1 1,100 CLAYSTONE, SANDY
TH-2 14 14.7 122 1,800 CLAYSTONE, SANDY
TH-2 19 14.6 124 3.3 2,400 CLAYSTONE, SANDY
TH-2 24 14.8 123 4.4 3,000 CLAYSTONE, SANDY
SWELL TEST RESULTS*
TABLE A-I
SUMMARY OF LABORATORY TESTING
ATTERBERG LIMITS STD. PROCTOR (ASTM D698)
Page 1 of 1
J.R. ENGINEERING, LLC
POLESTAR VILLAGE PRELIM
CTL|T PROJECT NO. FC10101-115
APPENDIX B
GUIDELINE SITE GRADING SPECIFICATIONS
J.R. ENGINEERING, LLC.
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
Appendix B-1
GUIDELINE SITE GRADING SPECIFICATIONS
1. DESCRIPTION
This item shall consist of the excavation, transportation, placement and
compaction of materials from locations indicated on the plans, or staked by the
Engineer, as necessary to achieve preliminary street and overlot elevations.
These specifications shall also apply to compaction of excess cut materials
that may be placed outside of the development boundaries.
2. GENERAL
The Soils Engineer shall be the Owner's representative. The Soils Engineer
shall approve fill materials, method of placement, moisture contents and
percent compaction, and shall give written approval of the completed fill.
3. CLEARING JOB SITE
The Contractor shall remove all vegetation and debris before excavation or fill
placement is begun. The Contractor shall dispose of the cleared material to
provide the Owner with a clean, neat appearing job site. Cleared material
shall not be placed in areas to receive fill or where the materi al will support
structures of any kind.
4. SCARIFYING AREA TO BE FILLED
All topsoil and vegetable matter shall be removed from the ground surface
upon which fill is to be placed. The surface shall then be plowed or scarified
until the surface is free from ruts, hummocks or other uneven features, which
would prevent uniform compaction.
5. COMPACTING AREA TO BE FILLED
After the foundation for the fill has been cleared and scarified, it shall be
disked or bladed until it is free from large clods, brought to the proper moisture
content (0 to 3 percent above optimum moisture content for clays and within 2
percent of optimum moisture content for sands) and compacted to not less
than 95 percent of maximum dry density as determined in accordance with
ASTM D698.
6. FILL MATERIALS
Fill soils shall be free from organics, debris or other deleterious substances,
and shall not contain rocks or lumps having a diameter greater than six (6)
inches. Fill materials shall be obtained from cut areas shown on the plans or
staked in the field by the Engineer.
J.R. ENGINEERING, LLC.
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
Appendix B-2
On-site materials classifying as CL, CH, SC, SM, SW, SP, GP, GC, and GM
are acceptable. Concrete, asphalt, organic matter and other deleterious
materials or debris shall not be used as fill.
7. MOISTURE CONTENT AND DENSITY
Fill material shall be moisture conditioned and compacted to the criteria in the
table, below. Maximum density and optimum moisture content shall be
determined from the appropriate Proctor compaction tests. Sufficient
laboratory compaction tests shall be made to determine the optimum moisture
content for the various soils encountered in borrow areas.
FILL COMPACTION AND MOISTURE REQUIREMENTS
Soil
Type
Depth from
Overlot Grade
(feet)
Moisture Requirement
(% from optimum) Density Requirement
Clay 0 to 20 feet +1 to +4 95% of ASTM D 698
Sand -2 to +2 95% of ASTM D 698
Clay Greater than
20 feet
-2 to +1 98% of ASTM D 698
Sand -2 to +1 95% of ASTM D 1557
The Contractor may be required to add moisture to the excavation materials in
the borrow area if, in the opinion of the So ils Engineer, it is not possible to
obtain uniform moisture content by adding water on the fill surface. The
Contractor may be required to r ake or disc the fill soils to provide uniform
moisture content through the soils.
The application of water to embankment materials shall be made with any type
of watering equipment approved by the Soils Engineer, which will give the
desired results. Water jets from the spreader shall not be directed at the
embankment with such force that fill materials are washed out.
Should too much water be added to any part of the fill, such that the material is
too wet to permit the desired compaction from being obtained, rolling and all
work on that section of the fill shall be de layed until the material has been
allowed to dry to the required moisture content. The Contractor will be
permitted to rework wet material in an approved manner to hasten its drying.
J.R. ENGINEERING, LLC.
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
Appendix B-3
8. COMPACTION OF FILL AREAS
Selected fill material shall be placed and mixed in evenly spread layers. After
each fill layer has been placed, it shall be uniformly compacted to not less than
the specified percentage of maximum density. Fill shall be compacted to the
criteria above. At the option of the Soils Engineer, soils classifying as SW,
GP, GC, or GM may be compacted to 95 percent of maximum density as
determined in accordance with ASTM D 1557 or 70 percent relative density for
cohesionless sand soils. Fill materials shall be placed such that the thickness
of loose materials does not exceed 12 inches and the compacted lift thickness
does not exceed 6 inches.
Compaction as specified above, shall be obtained by the use of sheepsfoot
rollers, multiple-wheel pneumatic-tired rollers, or other equipment approved by
the Engineer for soils classifying as CL, CH, or SC. Gr anular fill shall be
compacted using vibratory equipment or other equipment approved by the
Soils Engineer. Compaction shall be accomplished while the fill material is at
the specified moisture content. Compaction of each layer shall be continuous
over the entire area. Compaction equipment shall make sufficient trips to
ensure that the required density is obtained.
9. COMPACTION OF SLOPES
Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable
equipment. Compaction operations shall be continued until slopes are stable,
but not too dense for planting, and there is not appreciable amount of loose
soils on the slopes. Compaction of slopes may be done progressively in
increments of three to five feet (3' to 5') in height or after the fill is brought to its
total height. Permanent fill slopes shall not exceed 3:1 (horizontal to vertical).
10. PLACEMENT OF FILL ON NATURAL SLOPES
Where natural slopes are steeper than 20 percent in grade and the placement
of fill is required, benches shall be cut at the rate of one bench for each 5 feet
in height (minimum of two benches). Benches shall be at least 10 feet in
width. Larger bench widths may be required by the Engineer. Fill shall be
placed on completed benches as outlined within this specification.
11. DENSITY TESTS
Field density tests shall be made by the Soils Engineer at locations and depths
of his choosing. Where sheepsfoot rollers are used, the soil may be disturbed
to a depth of several inches. Density tests shall be taken in compacted
material below the disturbed surface. When density tests indicate that the
density or moisture content of any layer of fill or portion thereof is not within
specification, the particular layer or portion shall be reworked until the required
density or moisture content has been achieved.
J.R. ENGINEERING, LLC.
POLESTAR VILLAGE PRELIM
CTL | T PROJECT NO. FC10101-115
Appendix B-4
12. SEASONAL LIMITS
No fill material shall be placed, spread or rolled while it is frozen, thawing, or
during unfavorable weather conditions. When work is int errupted by heavy
precipitation, fill operations shall not be resumed until the Soils Engineer
indicates that the moisture content and density of previously placed materials
are as specified.
13. NOTICE REGARDING START OF GRADING
The Contractor shall submit notification to the Soils Engineer and Owner
advising them of the start of grading operations at least three (3) days in
advance of the starting date. Notification shall also be submitted at least 3
days in advance of any resumption dates when grading operations have been
stopped for any reason other than adverse weather conditions.
14. REPORTING OF FIELD DENSITY TESTS
Density tests made by the Soils Engineer, as specified under "Density Tests"
above, shall be submitted progressively to the Owner. Dry density, moisture
content, and percentage compaction shall be reported for each test taken.
15. DECLARATION REGARDING COMPLETED FILL
The Soils Engineer shall provide a written declaration stating that the site was
filled with acceptable materials and was placed in general accordance with the
specifications.