HomeMy WebLinkAboutCOTTONWOOD RIDGE SUBDIVISION - PRELIMINARY - 31-94 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTLOG OF BORING No. 4 Page 1 of 1
CLIENT ARCHITECT/ENGINEER
Nona and Sandy Thayer
d PROJECT
SITE
Shields Street South of Harmony Roa
Fort Collins, Colorado
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WATER LEVEL OBSERVATIONS
Empire Laboratories
Incorporated
Division of Terracon
BORING STARTED 4-28-94
BORING COMPLETED 4-28-94
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JOB N 20945089
Checked 11 Days A.B.
LOG OF BORING No. 3
Page 1 of 1
CLIENT
ARCHITECT/ENGINEER
Nona and Sandy Thayer
SITE Shields Street South of Harmony Road
PROJECT
Fort Collins, Colorado
Cottonwood Ridge
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WATER LEVEL OBSERVATIONS
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BORING STARTED 4-28-94
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LOG OF BORING No. Z Page I of 1
CLIENT
Nona and Sandy Thayer
ARCHITECTIENGINEER
sreE Shields Street South of Harmony Road PROJECT
Fort Collins, Colorado Cottonwood Ridge
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THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES
BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION MAY BE GRADUAL.
WATER LEVEL OBSERVATIONS
Empire Laboratories
Incorporated
Division of Terrecon
BORING STARTED 4-28-94
BORING COMPLETED 4-28-94
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= 59611 A.B.
RIG CME-55
FOREMAN DL
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APPROVED LRS JOB # 20945089
Checked 11 Days A.B.
LOG OF BORING No. 1
Page 1 of 1
CLIENT
ARCHITECT/ENGINEER
Nona and Sandy Thayer
SITE Shields Street South of Harmony Road
PROJECT
Fort Collins, Colorado
Cottonwood Ridge
SAMPLES
TESTS
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THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES
BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION MAY BE GRADUAL.
WATER LEVEL OBSERVATIONS
BORING STARTED 4-28-94
Empire Laboratories
Incorporated
Division of Terracon
4 None W.D
=None A.B.
BORING COMPLETED 4-28-94
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RIG CME-55
FOREMAN DL
Checked 11 Days A.B.
APPROVED LRS
JOB a 20945089
No Text
Terracon
Nona and Sandy Thayer
ELI Project No. 20945089
• Excavation and Trench Construction: Excavations into the on -site soils will encounter
caving soils and possibly groundwater, depending upon the final depth of excavation. The
individual contractor(s) should be made responsible for designing and constructing stable,
temporary excavations as required to maintain stability of both the excavation sides and
bottom. All excavations should be sloped or shored in the interest of safety following
local, and federal regulations, including current OSHA excavation and trench safety
standards.
PRELIMINARY GENERAL COMMENTS
It should be noted that this was a preliminary investigation and the bearing capacities
recommended in this report are based upon preliminary tests. Due to variations in soil conditions
encountered at the site, it is recommended that additional test borings be made prior to
construction. Samples obtained from the borings should be tested in the laboratory to provide a
basis for evaluating subsurface conditions.
The analyses and recommendations in this report are based in part upon data obtained from the
field exploration. The nature and extent of variations beyond the location of test borings may not
become evident until construction. If variations then appear evident, it may be necessary to
reevaluate the recommendations of this report.
Our professional services were performed using that degree of care and skill ordinarily exercised,
under similar circumstances, by reputable geotechnical engineers practicing in this or similar
localities. No warranty, express or implied, is made. We prepared the report as an aid in design
of the proposed project. This report is not a bidding document. Any contractor reviewing this
report must draw his own conclusions regarding site conditions and specific construction
techniques to be used on this project.
This report is for the exclusive purpose of providing geotechnical engineering and/or testing
information and recommendations. The scope of services for this project does not include, either
specifically or by implication, any environmental assessment of the site or identification of
contaminated or hazardous materials or conditions. If the owner is concerned about the potential
for such contamination, other studies should be undertaken.
11
Terracon
Nona and Sandy Thayer
ELI Project No. 20945089
• Placement and Compaction:
1. Place and compact fill in horizontal lifts, using equipment and procedures that will
produce recommended moisture contents and densities throughout the lift.
2. Uncompacted fill lifts should not exceed 10 inches loose thickness.
3. No fill should be placed over frozen ground.
4. Materials should be compacted to the following:
Material
On -site soils or approved imported fill:
Minimum Percent
Compaction (ASTM D698)
Beneath foundations ............................
yo
95
Beneath slabs ................................
95
Beneath pavement .............................
95
Utility trenches beneath construction ................
90
Utility trenches in open areas ......................
Miscellaneous backfill................................ 90
5. If a well defined maximum density curve cannot be generated by impact compaction
in the laboratory for any fill type, engineered fill should be compacted to a minimum
of 80 percent relative density as determined by ASTM D4253, D4254.
6. On -site clay soils around or beneath foundations should be compacted within a
moisture range of optimum to 2 percent above optimum. Sand soils around or
beneath foundations should be compacted within a moisture content range of 3
percent below to 3 percent above optimum.
• Compliance: Performance of slabs -on -grade, foundations and pavement elements
supported on compacted fills or prepared subgrade depends upon compliance with
"Earthwork" recommendations. To assess compliance, observation and testing should be
performed under the direction of the geotechnical engineer.
10
Terracon
Nona and Sandy Thayer
ELI Project No. 20945089
• Excavation:
1. It is anticipated that excavations into the on -site soils can be accomplished with
conventional earth -moving equipment.
2. Excavations penetrating the claystone-siltstone bedrock may require the use of
specialized heavy-duty equipment.
• Slab Subgrade Preparation:
1 . Where existing clay soils will support upper level floor slabs, the soils should be
scarified, moisture -conditioned and compacted to a minimum depth of 6 inches.
2. A minimum 4-inch layer of clean -graded gravel should be placed beneath upper level
slabs.
3. A minimum 8-inch layer of free -draining gravel should be placed beneath basement
floor slabs in conjunction with the underslab drainage system.
• Fill Materials:
1. Clean on -site soils or approved imported materials may be used as fill material for
the following:
• general site grading • exterior slab areas
• foundation areas • pavement areas
• interior floor slab areas • foundation backfill
2. On -site bedrock materials are not recommended for use beneath structural areas of
the site or as backfill. Should bedrock materials be used for general site grading,
placement in fills at non-structural locations on the site is recommended.
3. Select granular materials should be used as backfill behind retaining walls.
4. Frozen soils should not be used as fill or backfill.
�7
Terracon
Nona and Sandy Thayer
ELI Project No. 20945089
Earthwork:
• General Considerations: The conclusions contained in this report for the proposed
construction are contingent upon compliance with recommendations presented in this
section.
• Site Clearing:
1 . Strip and remove existing vegetation and other deleterious materials from proposed
building and pavement areas.
2. If unexpected fills or underground facilities are encountered during site clearing,
such features should be removed and the excavation thoroughly cleaned prior to
backf ill placement and/or construction. All excavations should be observed by the
geotechnical engineer prior to backfill placement.
3. Stripped materials consisting of vegetation and organic materials should be wasted
from the site or used to revegetate exposed slopes after completion of grading
operations.
4. Drainage blankets, consisting of free -draining gravel enclosed in filter fabric, should
be placed in any natural drainage beneath fill sections which exceed 12 feet in
height. Drainage blankets should be led to a positive gravity discharge.
5. Sloping areas steeper than 2:1 (horizontal:vertical) should be benched to reduce the
potential for slippage between existing slopes and fills. Benches should be level and
wide enough to accommodate compaction and earth moving equipment.
6. The site should be initially graded to create a relatively level surface to receive fill
and to provide for a relatively uniform thickness of fill beneath proposed building
structures.
7. All exposed areas which will receive fill, once properly cleared and benched where
necessary, should be scarified to a minimum depth of 6 inches, conditioned to near
optimum moisture content, and compacted.
L
Terracon
Nona and Sandy Thayer
ELI Project No. 20945089
Foundations and masonry walls should be reinforced as necessary to reduce the potential for
distress caused by differential foundation movement. The use of joints at openings or other
discontinuities in masonry walls is recommended.
Foundation excavations should be observed by the geotechnical engineer. If the soil conditions
encountered differ significantly from those presented in this report, supplemental recommendations
will be required.
Basement Construction: Groundwater was encountered in the northeast portion of the site at a
depth of 5'/2 feet below the surface. It is our understanding a toe drain along the east side of the
canal and/or an area drain are to be constructed to permanently lower the existing groundwater
level. In our opinion, basement construction is feasible provided the excavation extends no deeper
than 2 to 3 feet above the groundwater level and/or bedrock surface. Complete underslab
dewatering systems are recommended for basements constructed east of the canal.
In our opinion, full depth basement construction is feasible west of the canal. It is recommended
that the groundwater level in the west portion of the site be monitored for a sufficient period of
time to better determine the need for complete underslab dewatering systems in this area.
Floor Slab Design and Construction Within 3 Feet of Bedrock: The development of substantial
swelling pressures within the claystone-siltstone bedrock near approximate slab subgrade elevation
could result in differential movement of floor slab -on -grade if the potentially expansive bedrock
increases in moisture content. Use of structural floor systems, structurally supported independent
of the subgrade, is a positive means of eliminating the potentially detrimental effects of floor
movement. It is our opinion that with certain precautions and knowing that some risk is involved,
a floating floor slab may be a reasonable alternative. If the owner is willing to assume the risk of
future slab movement and related structural damage, the subgrade soils should be prepared as
outlined in the "Earthwork" section of this report.
Floor Slab Design and Construction On At Least 3 Feet of Non -Expansive Soils: Where non -
expansive, or low -swelling soils will be supporting the floor slabs, some differential movement of
a slab -on -grade floor system is possible should the subgrade soils increase in moisture content.
Such movements are considered within general tolerance for normal slab -on -grade construction.
To reduce any potential slab movements, the subgrade soils should be prepared as outlined in the
"Earthwork" section of this report.
7
Nona and Sandy Thayer Terracon
ELI Project No. 20945089
Foundation Systems - Northeast Portion of Site: Provided that the existing water table in the
northeast portion of the site is permanently lowered, it is our opinion full depth basement
construction is feasible in this area. Due to the presence of shallow and potentially expansive
claystone-siltstone bedrock in the northeast portion of the site, a grade beam and drilled pier
foundation system is recommended for support of any residences with slabs placed within 2 to
3 feet of the bedrock surface. Straight shaft piers, drilled a minimum of 5 feet into the firm
bedrock, with a minimum shaft length of 12 feet are recommended.
For axial compression loads, piers may be design for a maximum end -bearing pressure between
12,000 and 15,000 pounds per square foot (psf), and skin friction between 1,200 and 1,500 psf
for the portion of the pier in firm bedrock.
Required pier penetration should be balanced against potential uplift forces due to expansion of
the subsoils and bedrock on the site. For design purposes, the range of uplift force on each pier
can be determined on the basis of the following equation:
Up = [15to201xD
Where: up = the uplift force in kips, and
D = the pier diameter in feet
Uplift forces on piers should be resisted by a combination of dead -load and pier penetration below
a depth of 5 feet and in the bearing strata.
Drilling to design depths should be possible with conventional single flight power augers. Shafts
will probably remain open without stabilizing measures. However, pier concrete should be placed
immediately after completion of drilling and cleaning. Due to potential sloughing and raveling,
foundation concrete quantities may exceed calculated geometric volumes. Pier concrete with
slump in the range of 5 to 7 inches is recommended.
Foundation Systems - West and Southeast Portions of the Site: Due to the presence of low -
swelling soils on the west and southeast portions of the site, spread footing foundations bearing
upon undisturbed subsoils at least 2 to 3 feet above bedrock are recommended for support of the
proposed residences in these areas. The footings may be designed for a maximum bearing
pressure between 1,000 and 2,000 psf. Existing fill on the site should not be used for support
of foundations without removal and recompaction. Exterior footings should be placed a minimum
of 30 inches below finished grade for frost protection. Finished grade is the lowest adjacent grade
for perimeter footings. The design bearing capacities apply to dead loads plus design live load
conditions.
A
Terracon
Nona and Sandy Thayer
ELI Project No. 20945089
CONCLUSIONS AND RECOMMENDATIONS
Site Development Considerations: In our opinion, the proposed construction is feasible at the site.
High groundwater and potentially expansive bedrock will require particular attention in the design
and construction of the development.
Because of variations in the engineering properties of the on -site soils and bedrock, foundation
bearing levels, structural loads, and possible final grades, the following foundation systems were
evaluated for use on the site:
• grade beams and straight shaft piers drilled into bedrock; and
• spread footings bearing on undisturbed soils.
Design criteria for alternate foundation systems is subsequently outlined. Use of the alternative
foundation systems outlined in this report should be determined for individual residential structures
on the basis of supplemental geotechnical exploration of each lot prior to construction.
Slab -on -grade construction, for basement or garage areas, is considered acceptable for use when
subgrade soils consist of the on -site clays or sands with gravel, provided that design and
construction recommendations are followed. Given the expansive potential of the claystone-
siltstone bedrock, consideration should be given to the use of structural floor systems in basement
areas where the bedrock will be encountered. Evaluation of expansion tests conducted on
individual lots during supplemental geotechnical exploration is recommended to assess the need
for structural floor systems.
Due to the potential for seepage to occur along the east side of the canal and the potential for a
perched water table to form on the bedrock surface, complete underslab dewatering systems are
recommended for any basements constructed east of the canal.
The need for complete underslab dewatering systems for basements constructed west of the canal
should be determined after the groundwater level has been monitored for a sufficient period of
time in this area.
Consideration should be given to (1) constructing a toe drain along the east side of the canal
and/or (2) constructing an area drain below the proposed streets of the development. The area
drain should be properly designed and approved by the City of Fort Collins.
5
4
Nona and Sandy Thayer
ELI Project No. 20945089
Terracon
• Claystone/Siltstone Bedrock: The bedrock stratum was encountered in borings 2 and 4 at
` depths of 6 Y2 and 11 feet below the surface, respectively. The upper 1 Yz to 4 feet of
bedrock encountered is highly weathered. However, the underlying bedrock encountered
in boring 2 is hard.
Field and Laboratory Test Results: Field test results indicate that the clay soils vary from soft to
stiff in consistency. The underlying granular soils vary from medium dense to dense. The
weathered and unweathered bedrock are moderately hard and hard; respectively. The soils at
anticipated foundation bearing depths have low to moderate load bearing capabilities and the
bedrock at anticipated foundation bearing depth has moderate load bearing capability.
Preliminary laboratory test results indicate that the clay soil has low expansive potential and the
claystone-siltstone bedrock has moderate to high expansive potential.
Groundwater Conditions: Groundwater was not encountered in any test boring at the time of the
field exploration; however, when checked 11 days after drilling, groundwater was measured at
a depth of 5 Yz feet in test boring 2. These observations represent only current groundwater
conditions, and may not be indicative of other times, or at other locations. Groundwater levels
can be expected to fluctuate with varying seasonal and weather conditions and the flows in the
Trilby Lateral and Pleasant Valley and Lake Canal.
Zones of perched and/or trapped groundwater may also occur at times in the subsurface soils
overlying bedrock, on top of the bedrock surface or within permeable fractures in the bedrock
materials. The location and amount of perched water is dependent upon several factors, including
hydrologic conditions, type of site development, irrigation demands on or adjacent to the site,
fluctuations in water features, and seasonal and weather conditions.
Fluctuations in groundwater levels can best be determined by implementation of a groundwater
monitoring plan. PVC pipe was installed in each test boring at the time of drilling. Groundwater
levels should be measured periodically in the test borings over a sufficient period of time.
The possibility of groundwater fluctuations should be considered when developing design and
construction plans for the project.
4
Nona and Sandy Thayer
ELI Project No. 20945089
SITE CONDITIONS
Terracon
The site consists of approximately 34 acres of a land on the west side of South Shields Street
approximately Y< to Yz-mile south of Harmony Road, south of Fort Collins, Colorado. The majority
of the area is vegetated with low, dense grass. An existing residence with horse corrals is located
. in the southwest portion of the site. The Pleasant Valley and Lake Canal, which was dry at the
time of our investigation, runs generally north -south across the west -central portion of the site.
The Trilby Lateral extends eastward from the center of the west property line and connects into
the Pleasant Valley and Lake Canal in the west -central portion of the site. The area generally
slopes to the east and exhibits fair surface drainage in this direction. The property is bordered by
fields to the north and south, Shields Street to the east and The Ridge subdivision to the west.
SUBSURFACE CONDITIONS
Soil and Bedrock Conditions: As presented on the boring logs, the subsurface materials were
encountered in order of increasing depth as follows:
• Topsoil and Fill: A Yz-foot layer of silty topsoil was encountered at the surface of borings
1, 2 and 4. A 1-foot layer of fill was encountered at the surface of boring 3. The fill
consists of lean clay with sand. The topsoil and the upper Y2-foot of the fill have been
penetrated by root growth and organic matter.
• Lean Clay with Sand: A layer of brown clay was encountered below the topsoil in borings
1, 2 and 4 and extends to depths of 1 to 6'/z feet below the surface. This brown clay
contains moderate quantities of sand and is moist in its in -situ condition.
• Sandy Lean Clay: A layer of red clay was encountered at depths of 1 to 2 feet below the
surface in borings 1, 3 and 4 and extends to depths of 3Y2 to at least 15 feet below the
surface which was the depth explored. The red clay contains substantial quantities of sand
and is dry to moist in its in -situ condition.
• Clayey Sand with Gravel: A granular stratum was encountered below the red clay layer
in borings 1 and 4 and extends to a depth of 11 feet below the surface or to the depth
explored. The granular stratum is dry to moist in its in -situ condition.
3
Terracon
Nona and Sandy Thayer
ELI Project No. 20945089
Field Exploration: A total of four test borings were drilled on April 28, 1994 to a depth of
approximately 15 feet at the locations shown on the Site Plan, Figure 1. The borings were drilled
in areas of proposed residential construction. All borings were advanced with a truck -mounted
drilling rig, utilizing 4-inch diameter solid stem auger.
The location of borings were positioned in the field by pacing from fence corners. The accuracy
of boring locations should only be assumed to the level implied by the method used to determine
the locations.
Continuous lithologic logs of each boring were recorded by the engineering geologist during the
drilling operations. At selected intervals, samples of the subsurface materials were taken by
means of pushing thin -walled Shelby tubes, or by driving split -spoon barrel samplers.
Penetration resistance measurements were taken with each sampling with the split -spoon by
driving the sampler with a 140-pound hammer falling 30 inches. When properly interpreted, the
penetration resistance is a useful index to the consistency, relative density or hardness of the
materials encountered.
Groundwater conditions were evaluated in each boring at the time of site exploration and 11 or
14 days after drilling.
Laboratory Testing: All samples retrieved during the field exploration were returned to the
laboratory for evaluation by the project geotechnical engineer, and were classified in accordance
with the Unified Soil Classification System described in Appendix C. Samples of bedrock were
classified in accordance with the general notes for Bedrock Classification. At that time, the field
descriptions were confirmed or modified as necessary, final boring logs prepared, and an applicable
laboratory testing program was formulated to determine engineering properties of the subsurface
materials. Boring Logs for the project are presented in Appendix A.
Selected soil and bedrock samples were tested for the following engineering properties:
• Water content • Expansion
• Dry density • Plasticity
• Compressive strength
The significance and purpose of each laboratory test is described in Appendix C. Laboratory test
results are presented in Appendix B, and were used for the geotechnical engineering analyses, and
the development of preliminary foundation and earthwork recommendations. All laboratory tests
were performed in general accordance with the applicable ASTM, local or other accepted standards.
2
PRELIMINARY GEOTECHNICAL ENGINEERING REPORT Terracon
COTTONWOOD RIDGE
SHIELDS STREET SOUTH OF HARMONY ROAD
LARIMER COUNTY, SOUTH OF FORT COLLINS, COLORADO
ELI PROJECT NO. 20945089
MAY 11, 1994
INTRODUCTION
This report contains the results of our preliminary geotechnical engineering exploration for the
proposed project to be located on the west side of Shields Street approximately %a to '/z-mile
south of Harmony Road, south of Fort Collins, Colorado. The site is located in the East '/2 of the
Northeast '/4 of Section 3, Township 6 North, Range 69 West of the 6th Principal Meridian.
The purpose of these services is to provide information and preliminary geotechnical engineering
recommendations relative to:
• subsurface soil and bedrock conditions
• groundwater conditions
• foundation design and construction
• basement construction
• floor slab design and construction
• earthwork
• drainage
The conclusions and recommendations contained in this report are based upon the results of field
and laboratory testing, engineering analyses, and experience with similar soil and structural
conditions.
PROPOSED CONSTRUCTION
It is our understanding the proposed project is a single-family residential development on 34 acres
of land. Although final site grading plans were not available prior to preparation of this report,
ground floor levels are anticipated to be at or near existing site grades.
' SITE EXPLORATION
The scope of the services performed for this project included site reconnaissance by an
engineering geologist, a subsurface exploration program, laboratory testing and engineering
analyses.
Nona and Sandy Thayer
ELI Project No. 20945089
TABLE OF CONTENTS (Cont'd)
Terracon
APPENDIX A
Site Plan .............................................. Figure No. 1
Logs of Borings ..........................................
Al thru A4
APPENDIX B
Summary of Test Results .........................................
B1
APPENDIX C: GENERAL NOTES
Drilling & Exploration ............................................
C1
Unified Soil Classification .........................................
C2
Bedrock Classification, Sedimentary Bedrock
............................ C3
Laboratory Testing, Significance and Purpose
........................... C4
Report Terminology .............................................
C5
Terracon
Nona and Sandy Thayer
ELI Project No. 20945089
TABLE OF CONTENTS
Page No.
Letter of Transmittal................................................... i
INTRODUCTION..................................................... 1
PROPOSED CONSTRUCTION ........................................... 1
SITE EXPLORATION .................................................. 1
Field Exploration ...................... 2
Laboratory Testing .............................................. 2
SITECONDITIONS ................................................... 3
SUBSURFACE CONDITIONS ............................................ 3
Soil and Bedrock Conditions ....................................... 3
Field and Laboratory Test Results .................................... 4
Groundwater Conditions .......................................... 4
CONCLUSIONS AND RECOMMENDATIONS ................................. 5
Site Development Considerations .................................... 5
Foundation Systems - Northeast Portion of Site .......................... 6
Foundation Systems - West and Southeast Portions of the Site ............... 6
Basement Construction ........................................... 7
Floor Slab Design and Construction Within 3 Feet of Bedrock ................ 7
Floor Slab Design and Construction On At Least 3 Feet of Non -Expansive Soils .... 7
Earthwork.................................................... 8
General Considerations ...................................... 8
Site Clearing .............................................. 8
Excavation ................... 9
Slab Subgrade Preparation .................................... 9
Fill Materials ............................................. 9
Placement and Compaction .................................. 10
Compliance ............................................. 10
Excavation and Trench Construction ............................ 11
PRELIMINARY GENERAL COMMENTS .................................... 11
Nona and Sandy Thayer Terracon
ELI Project No. 20945089
We recommend any residences placed within 2 feet of the bedrock stratum in the northeast
portion of the site be supported on a grade beam and straight shaft pier foundation system. This
would likely entail permanently lowering the water table in this area. Given the expansive
potential of near surface bedrock which may support slabs in this area, consideration should be
given to the use of structural floor systems if no movement can be tolerated.
Other preliminary design and construction details, based upon geotechnical conditions, are
presented in the report.
We have appreciated being of service to you in the preliminary geotechnical engineering phase of
_ this project, and are prepared to assist you during the final geotechnical, design and construction
phases as well. If you have any questions concerning this report or any of our testing, inspection,
design and consulting services, please do not hesitate to contact us.
Sincerely, `\`������@�?
EMPIRE LABORATORIES, INC. N 'N, : P,SCHO�
A Division of The Terracon Companies, Inc. = co
23702
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L R. Schoenfeld, P.E. "%�``�•°°••••°°^•'
Geotechnical Engineer / 0''%A F����"`�`'
Reviewed by:
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Chester C. Smith, P.E.
Division Manager ' 4808
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Copies to: Nona and Sandy Thayer (4) \�- l CCU'
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May 11, 1994
Empire Laboratories, Inc.
A Division of The Terracon Companies, Inc.
Nona and Sandy Thayer
�. c/o Eric Thayer
31741 RCR 35
Steamboat Springs, CO 80487
Re: Preliminary Geotechnical Engineering Report, Cottonwood Ridge
Shields Street South of Harmony Road
Larimer County, South of Fort Collins, Colorado
_ ELI Project No. 20945089
P.O. Box 503 - 301 No. Howes
Fort Collins, Colorado 80522
(303)484-0359
FAX No. (303) 484-0454
Chester C. Smith, P.E.
Neil R. Sherrod, C.P.G.
Empire Laboratories, Inc. (ELI) has completed a preliminary geotechnical engineering exploration
for the proposed project to be located on the west side of Shields Street approximately 'A to '/2-
mile south of Harmony Road, south of Fort Collins, Colorado. This study was performed in general
accordance with our proposal number D2094141 dated April 18, 1994.
The results of our preliminary engineering study, including the boring location diagram, laboratory
test results, test boring records, and the preliminary geotechnical recommendations needed to aid
_ in the design and construction of foundations and other earth connected phases of this project are
attached.
The subsurface exploration indicated conditions which are typical of soils commonly found in the
_ Fort Collins area. The subsurface soils at the site generally consisted of lean clay with sand,
sandy lean clay and clayey sand with gravel overlying claystone-siltstone bedrock. The
information obtained by the results of field exploration and laboratory testing completed for this
- study indicates that clay soil at the site has low expansive potential and bedrock at the site has
_ moderate to high expansive potential. The soils at anticipated foundation bearing depths have low
to moderate load bearing capabilities. The bedrock at anticipated foundation bearing depth has
moderate bearing capability.
Based on the preliminary geotechnical engineering analyses, subsurface exploration and laboratory
test results, we recommend that the proposed residences in the majority of the site be supported
_ on spread footing foundation systems. Slab -on -grade may be utilized for the corresponding interior
- floor systems provided that care is taken in the placement and compaction of the subgrade soil.
Offices of The Terracon Companies, Inc. Geotechnical, Environmental and Materials Engineers
`- Arizona: Tucson 0 Colorado: Colorado Springs, Denver, Ft. Collins, Greeley, Longmont ■ Idaho: Boise ■ Illinois: Bloomington,
Chicago, Rock Island ■ Iowa: Cedar Falls, Cedar Rapids, Davenport, Des Moines, Storm Lake ■ Kansas: Lenexa, Topeka,
_ Wichita ■ Minnesota: St. Paul ■ Missouri: Kansas City ■ Nebraska: Lincoln, Omaha ■ Nevada: Las Vegas
■ Oklahoma: Oklahoma City, Tulsa ■ Texas: Dallas, Fort Worth ■ Utah: Salt Lake City ■ Wyoming: Cheyenne
m QUALITY ENGINEERING SINCE 1965
PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
COTTONWOOD RIDGE
SHIELDS STREET SOUTH OF HARMONY ROAD
LARIMER COUNTY, SOUTH OF FORT COLLINS, COLORADO
ELI PROJECT NO. 20945089
Prepared for.
NONA AND SANDY THAYER
C/O ERIC THAYER
31741 RCR 35
STEAMBOAT SPRINGS, COLORADO 80487
Empire Laboratories, Inc.
A Division of the Terracon Companies, Inc.
PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
COTTONWOOD RIDGE
SHIELDS STREET SOUTH OF HARMONY ROAD
LARIMER COUNTY, SOUTH OF FORT COLLINS, COLORADO
ELI PROJECT NO. 20945089
A Division of
The Terracon Companies, Inc.