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GEOLOGIC AND PRELIMINARY
GEOTECHNICAL INVESTIGATION
300-500 EAST VINE DRIVE
FORT COLLINS, COLORADO
Prepared For:
FORT COLLINS REAL ESTATE
1220 South College Avenue
Fort Collins, Colorado 80524
Attention: Mr. Mike Jensen and Mr. Mike Bello
Project No. FC04631-115 September 15,
2008 351 Linden
Street I Suite 140 1 Fort Collins, Colorado 80524 Telephone:970-
206-9455 Fax:970-206-9441
I a
TABLE OF CONTENTS
SCOPE.......................................................................................................................1
SUMMARY OF CONCLUSIONS...............................................................................1
SITEDESCRIPTION.................................................................................................2
PROPOSED DEVELOPMENT..................................................................................2
PREVIOUS STUDIES................................................................................................2
FIELD AND LABORATORY INVESTIGATIONS.......................................................3
SUBSURFACE CONDITIONS...................................................................................3
SITEGEOLOGY........................................................................................................4
GEOLOGIC HAZARDS & CONSTRAINTS...............................................................4
Erosion...................................................................................................................4
Potentially Unstable Slopes...................................................................................5
DifficultExcavation.................................................................................................5
GroundWater.........................................................................................................5
SurfaceDrainage...................................................................................................6
ExpansiveSoils......................................................................................................6
FrostHeave............................................................................................................6
Seismicity................................................................................................................7
Radioactivity...........................................................................................................7
Subsurface and Surface Mining.............................................................................8
DEVELOPMENT RECOMMENDATIONS.................................................................8
ExistingFill.............................................................................................................8
SiteGrading......................................................................:.....................................8
ImportedFill............................................................................................................9
Permanent Cut and Fill Slopes..............................................................................9
UtilityConstruction................................................................................................10
UnderdrainSystem...............................................................................................11
PRELIMINARY PAVEMENT RECOMMENDATIONS.............................................11
SubgradePreparation..........................................................................................12
Preliminary Pavement Thickness Design............................................................12
PRELIMINARY RECOMMENDATIONS FOR STRUCTURES...............................13
Foundations..........................................................................................................13
Slabs -on -Grade and Floor Construction..............................................................13
SurfaceDrainage.................................................................................................13
WATER-SOLUBLE SULFATES..............................................................................14
RECOMMENDED FUTURE INVESTIGATIONS.....................................................14
LIMITATIONS...........................................................................................................15
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TABLE OF CONTENTS cont'd
FIGURE 1 — LOCATIONS OF EXPLORATORY BORINGS AND TEST PITS
FIGURE 2 — MEASURED DEPTH TO BEDROCK SURFACE
FIGURE 3 — MEASURED DEPTH TO GROUNDWATER
FIGURE 4 — GEOLOGIC MAP OF SITE AND SURROUNDING AREAS
APPENDIX A — SUMMARY LOGS OF EXPLORATORY BORINGS
APPENDIX B — LABORATORY TEST RESULTS
APPENDIX C — EXAMPLE SITE GRADING SPECIFICATIONS
SCOPE
This report presents the results of our Geologic and Preliminary Geotechnical
Investigation for the planned development at 300-500 East Vine Drive in Fort Collins,
Colorado. The purpose of our investigation was to identify geologic hazards and constraints
that may exist on the site and to evaluate the subsurface conditions to assist in planning for
development. The report includes descriptions of site geology, our analysis of the impact of
geologic conditions on site development, a description of soil, bedrock, and groundwater
conditions found in our exploratory borings, and discussions of site development as
influenced by geotechnical considerations.
This report was prepared based upon our understanding of the planned
development. The recommendations are considered preliminary and can be used as
guidelines for further planning of the development and design of grading. We should review
final development and grading plans to determine if additional investigation is merited, or if
we need to revise our recommendations. Additional investigations will be required to design
building foundations and pavements. A summary of our findings and recommendations is
presented below. More detailed discussions of the data, analysis and recommendations are
presented in the report.
SUMMARY OF CONCLUSIONS
1. Our investigation did not reveal any geologic or geotechnical conditions
which would preclude the proposed site development. Shallow ground water
is the primary concern for site development. We believe proper engineering
design and construction practices can substantially mitigate effects of the
geologic and geotechnical constraints that were identified.
2. The subsurface conditions encountered in our borings were variable across
the site. In general, the soils and bedrock encountered in our borings
consisted of approximately 9 to 21 feet of clays, silts, sands, gravels and
occasional cobbles and boulders over interbedded claystone and sandstone
bedrock. Up to two feet of existing fill was encountered in several of the
borings. Bedrock was encountered at depths ranging from approximately 14
to 21 feet belowthe existing ground surface. Ground waterwas encountered
at depths ranging from approximately 2 to 8 feet below the existing ground
surface. Groundwater levels will likely affect planned development at this
site.
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE
CTL I T PROJECT NO. FC04631-115 1
3. We measured very minor consolidation and low swell in several samples of
clay, silt, and sand. The bedrock is at depths not likely to influence shallow
foundations. We anticipate shallow foundations such as spread footings or
mat foundations will be appropriate for most structures at this site.
4. Asphaltic pavement sections on the order of 5 to 6 inches and portland
cement pavement sections on the order of 5 inches for streets, parking areas
and access drives are anticipated for preliminary planning purposes. Higher
volume pavement will likely require thicker sections, on the order of 6 to 8
inches for asphaltic pavement sections and 6 inches for Portland cement
pavements.
SITE DESCRIPTION
The site is located on the north and south sides of East Vine Drive between Linden
Street and Jerome Street in Fort Collins, Colorado. The site is generally in the plains and is
sparsely vegetated with grasses, weeds, and mature trees. At the time of our exploration,
the site was developed with utilities and paved roads on the east portion and dirt and gravel
parking areas on the remaining areas. The approximately 9-acre parcel is relativelyflat, with
a gentle slope to the east and has an irrigation ditch near the northern border. The Cache
La Poudre River is located approximately 500-feet southwest of the site with ponds situated
about 150-feet southwest. Several single -story, light commercial structures were observed
throughout the site.
PROPOSED DEVELOPMENT
We understand the parcel is planned for development of four new buildings and
associated paved areas. Paved areas may include parking areas and access drives. Storm
water management will consist of pervious pavement sections and an infiltration or detention
pond. Discussions with Apex Engineering (Civil Engineer) indicate the site may be elevated
with 1 to 3 feet of fill to realize desired grades. As we understand it, two of the buildings will
be one-story structures and two will be four-story structures. No below grade construction is
planned.
PREVIOUS STUDIES
CTL I Thompson, Inc. recently provided a letter summarizing the results of three
Double Ring Infiltrometer tests at the subject site (CTLIT Project No. FC04631-115, dated FORT COLLINS
REAL ESTATE 300-500
EAST VINE DRIVE 2 CTL ITPROJECTNO. FC04631-115
August 4, 2008). The infiltration testing was conducted in order to provide estimated
infiltration rates across the site. These test results were used to evaluate the potential for an
infiltration pond and pervious pavement sections at the site.
FIELD AND LABORATORY INVESTIGATIONS
Subsurface conditions were investigated by drilling eight exploratory borings and
excavating one test pit at the approximate locations shown on Figure 1. The test holes were
drilled using a truck -mounted drill rig with a 4-inch diameter, continuous -flight auger. The
test pit was excavated using a mini -excavator. Our field representative observed drilling,
logged the soils and bedrock found and obtained samples. Summary logs of the soils found
and field penetration resistance values are presented in Appendix A. Figures 2 and 3
present measured depths to bedrock and ground water.
Samples of soil and bedrock were obtained during drilling by driving a modified
California -type sampler (2.5 inch O.D.) into the soils and bedrock using a 140-pound
hammer falling 30 inches. Bulk samples were also collected from the test holes and test pit.
Samples were returned to our laboratory and visually classified by the engineering geologist
for the project. Laboratory testing included moisture content and dry density, swell -
consolidation characteristics, Atterberg limits, particle -size analysis, standard Proctor
compaction, and water-soluble sulfate content. Laboratory test results are presented in
Appendix B.
SUBSURFACE CONDITIONS
Subsurface conditions encountered in the borings included approximately 9 to 21
feet of clays, silts, sands, gravels, cobbles and boulders over interbedded claystone and
sandstone bedrock. Up to two feet of existing fill was encountered in several borings.
Bedrock was encountered at depths ranging from 14 to 21 feet below the existing ground
surface. Groundwater was encountered at depths ranging from approximately 2 to 7 feet
below the existing ground surface during drilling. Water levels were measured between 2
and 8 feet when checked several days after drilling. Groundwater levels will affect the
planned development at this site.
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE 3
CTL IT PROJECT NO. FC04631.115
SITE GEOLOGY
The geology of the site was investigated through review of mapping (Geologic Map
of the Boulder -Fort Collins -Greeley Area, Colton, R.B., 1978). Our engineering geologist
visited the site to assess whether field conditions are consistent with the geologic mapping
and reports, evaluate specific site features, and look for other geologic concerns. The
geology was further evaluated through review of conditions found in exploratory borings, and
our experience in the area.
The site is mapped as Post -Piney Creek Alluvium (Upper Holocene) overlying the
Pierre Shale (Upper Cretaceous). Typically in this area, the alluvial deposits consist of clays,
silts, sands, and gravels. The Pierre Shale at the site consists of two members: the Upper
Shale Member, consisting of shale and claystone, and the Richard Sandstone Member,
consisting of sandstone, lesser shale, and claystone. Our subsurface investigation generally
confirms our understanding of the site geology.
GEOLOGIC HAZARDS & CONSTRAINTS
No geologic hazards or constraints were indentified during our investigation that
could preclude the proposed development. No economically valuable extractable minerals
are known to occur in the immediate area of the site. Planning should consider the geologic
hazards and constraints discussed below. The following sections discuss each of these
geologic hazards, constraints and associated development concerns. Mitigation concepts
are discussed below and in the DEVELOPMENT RECOMMENDATIONS section of the
report.
Erosion
We believe the erosion potential is low for this site. The erosion potential can be
expected to increase during construction, but should return to pre -construction rates or less
if proper grading practices, surface drainage design and re -vegetation efforts are
implemented.
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300-500 EAST VINE DRIVE 4
CTL I T PROJECT NO. FC04631-115
Potentially Unstable Slopes
We did not observe evidence of slope instability on the parcel. Slopes on the
property are typically less than 2 percent. We believe it is prudent to design cut and fill
slopes to be as gentle as practical, to enhance stability, and decrease erosion potential.
Guidelines for placement of fill on slopes are presented in the DEVELOPMENT
RECOMMENDATIONS section below.
Difficult Excavation
Our borings encountered areas of gravels, cobbles, and boulders. These alluvial
deposits will be relatively difficult to excavate. While not considered a geologic hazard,
difficult excavation should be considered in planning for this development. Cuts should be
minimized where possible. Excavation methods can likely be completed with heavy-duty
excavation equipment. Depending upon the excavation procedures, some oversize
material, not suitable for reuse in trench backfill, may be generated.
Ground Water
Ground water was encountered during drilling at depths between 2 and 7 feet and
was measured between 2 and 8 feet from existing ground surface when checked several
days after drilling. These findings are consistent with previous investigations and experience
in the area. We expect current groundwater levels to affect site development. Groundwater
may rise due to site development, seasonal fluctuations, and water levels in the adjacent
ditches.
The depth to ground water should be evaluated during a future design level
geotechnical investigation at the site. In general, grading should be designed to raise the
elevations in areas of shallow ground water. Construction of underdrain systems with the
sanitary sewer trenches is a commonly employed method to mitigate the accumulation of
shallow ground water after construction. A minimum separation of 3 feet is recommended
between the groundwater elevations and the lowest elevation of any structure.
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE 5CTLiTPROJECTNO. FC04631-115
Surface Drainage
The civil engineer should evaluate and quantify the potential flow in each drainage
during peak precipitation events and design surface drainage and storm collection systems
to accommodate the water. Active drainage ways should be avoided for development.
Structures should not be located within a lateral distance from the crest equivalent to twice
the depth of the drainage way where slopes are steeper than about 2:1. Storm drainage
should be collected in detention or infiltration basins and released at historic rates or less.
Development in the steeper areas should be carefully situated and engineered so as not to
contribute to or become damaged by erosion. Evaluation of flood potential was not included
in our scope of work. The civil engineer should evaluate whether the site is flood prone.
Expansive Soils
The soils at this site include clays, silts, sands, gravels, cobbles, and boulders. The
overburden soils at this site are considered to be non -expansive. Much of the bedrock
formation below the site consists of expansive interbedded claystone and sandstone
bedrock; however, bedrock depths will likely buffer the influence on the proposed
construction.
Frost Heave
Our borings indicate shallow ground water is present and the overburden soils atthe
site consist of materials that are susceptible to frost heave. Based on our experience and
local construction practice in the area, the minimum depth of cover for frost protection is 30
inches. We recommend foundations have a minimum cover of 30 inches. If the foundations
are constructed with the appropriate frost protection, we do not believe frost heave will affect
the proposed structures. Slabs -on -grade may experience some movement due to frost
heave. If the buildings are insulated or heated, the potential for slab movement due to frost
heave is minimal. If the buildings are not insulated or heated, slabs -on -grade should be
constructed with frost protection.
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE
6CTLITPROJECTNO. FC04631-115
Seismicity
This area, like most of central Colorado, is subject 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 earthquake activity in Colorado is somewhat incomplete.
According to the 2006 International Building Code and the subsurface conditions
encountered in our borings, this site classifies as a Site Class D. Only minor damage to
relatively new, properly designed and built buildings would be expected. Wind loads, not
seismic considerations, typically govern dynamic structural design in this area. A Remi
Survey can be used to determine the shear wave velocities at the sites. A survey of this type
may result in a lower seismic site class (Site Class C). However, in our experience this is
unlikely.
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. Radon 222 gas is
considered a health hazard and is one of several radioactive products in the chain of the
natural 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 poorly -ventilated accumulation areas. It is difficult to predict the concentration
of radon gas in finished construction.
During our investigation, we did not detect any radiation levels above normal
background levels for the area. We recommend testing to evaluate radon levels after
construction is completed. If required, typical mitigation methods for residential construction
may consist of sealing soil gas entry areas and periodic ventilation of below -grade spaces
and perimeter drain systems. It is relatively economical to provide for ventilation of perimeter
drain systems or underslab gravel layers at the time of construction, compared to retrofitting
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE
7CTLITPROJECTNO. FC04631-115
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a structure after construction. Radon rarely accumulates to significant levels in above -
grade, heated and ventilated spaces.
Subsurface and Surface Mininq
No subsurface mining is known in the area. We do not anticipate the site is
underlain by any economic mineral resources.
DEVELOPMENT RECOMMENDATIONS
Existing Fill
Existing fill was encountered in four borings to depths of up to two feet. Deeper fill
areas may be encountered during site development. The fill is of unknown origin and age.
The fill presents a risk of movement to improvements supported by the fill. We recommend
the fill be removed and recompacted in planned building areas. Foundations and other
improvements should not be supported by existing fill.
The existing fill can also affect pavements and exterior flatwork. The lowest risk
alternative for exterior pavement and flatwork would also be complete removal and
recompaction. The cost could be significant. If some movement and distress in these areas
is acceptable, then partial depth removal is an alternative. We suggest removal of the
existing fill to a depth of 1 to 2 feet below existing grade, proof rolling the exposed subgrade,
and additional removal or stabilization of areas where soft, yielding, or organic soils or debris
is encountered. After this, fill placement can proceed to construction grades.
Site Grading
Due to the preliminary nature of this project, site grading plans have not been
prepared, and therefore not available for review in conjunction with this subsurface
exploration program. Therefore, recommendations provided here are general and for
planning purposes only.
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE 8CTLITPROJECTNO. FC04631-115
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Site grading will affect the proposed development. We understand fills of between 1
and 3 feet are expected on portions of the site. The existing on -site soils are suitable for re-
use as fill material provided debris or deleterious organic materials are removed.
Overburden soils may also include boulders that could require additional effort for removal.
We believe grading can be accomplished using conventional construction techniques and
heavy-duty equipment. Prior to fill placement, all trash and debris should be removed from
fill areas and properly disposed. The ground surface in areas to be filled should be stripped
of vegetation, topsoil and other deleterious materials, scarified to a depth of at least 8
inches, moisture conditioned and compacted as recommended below. Site soils should be
expected to reduce volume by up to 5% with compaction.
Site grading fill should be placed in thin, loose lifts, moisture conditioned and
compacted. In areas of deep fill, we recommend higher compaction criteria to help reduce
settlement of the fill. Compaction and moisture requirements are presented in Table B-1.
The placement and compaction of fill should be observed and density tested during
construction. Guideline site grading specifications are presented in Appendix C.
Imported Fill
If import material is required, samples from each source should be provided for our
review. The material used beneath planned structures should be a sandy clay or clayey
sand with a liquid limit of less than 35 and a plasticity index between 4 and 15. A minimum
of 25 percent of the soil should pass the No. 200 sieve. The material should be spread in
loose horizontal lifts, less than 12-inches thick, and be uniformly compacted to a minimum of
95 percent of the maximum Standard Proctor Density between minus 1 and plus 3 percent
above optimum moisture content as determined by ASTM D 698.
Permanent Cut and Fill Slopes
We recommend permanent cut and fill slopes be designed with a maximum
inclination of 3:1 (horizontal to vertical). Where fills will be placed on slopes exceeding 20
percent (5:1) the slope should be benched. Structures should be setback from the top or
bottom of cut and fill slopes. If site constraints (property boundaries and streets) do not
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE 9CTLITPROJECTNO. FC04631-115
permit construction with recommended slopes, we should be contacted to evaluate the
subsurface soils and steeper slopes.
Utility Construction
We believe excavations for utility installation in the overburden soils can be
performed with conventional heavy-duty trenchers or large backhoes. Boulders are likely in
the overburden soils. Ground water is anticipated in excavations. For excavations
extending less than a few feet below ground water, dewatering may be accomplished by
sloping excavations to occasional sumps where water can be removed by pumping. Deeper
excavations will likely need a dewatering system to maintain constructible conditions.
Utility trenches should be sloped or shored to meet local, State, and federal safety
regulations. Based on our investigation, we believe the overburden soils classify as Type C
soil and the bedrock as Type B soil based on OSHA standards. Excavation slopes specified
by OSHA are dependent upon soil types and groundwater conditions encountered.
Seepage and ground water conditions in trenches may downgrade the soil type. Contractors
should identify the soils encountered in the excavation and refer to OSHA standards to
determine appropriate slopes. Excavations deeper than 20 feet should be designed by a
professional engineer.
The width of the top of an excavation may be limited in some areas. Bracing or
trench box" construction may be necessary. Bracing systems include sheet piling, braced
sheeting, and others. Lateral loads on bracing depend on the depth of excavation, slope of
excavation above the bracing, surface loads, hydrostatic pressures, and allowable
movement. For trench boxes and bracing allowed to move enough to mobilize the strength
of the soils, with associated cracking of the ground surface, the "active" earth pressure
conditions are appropriate for design. We have assumed the lateral material will consist of
sand and gravel for the purposed of design. If movement is not tolerable, the "at rest' earth
pressures are appropriate. We suggest an equivalent fluid density of 35 pcf for the "active"
earth pressure condition and 50 pcf for the "at rest" earth pressure condition, assuming level
backfill. These pressures do not include allowances for surcharge loading or for hydrostatic
conditions. We are available to assist further with bracing design if desired.
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE 1 OCTLITPROJECTNO. Fc04631-115
Water and sewer lines are usually constructed beneath paved roads. Compaction of
trench backfill can have significant effect on the life and serviceability 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 guidelines are provided in the EXAMPLE
SITE GRADING SPECIFICATIONS presented in Appendix C of this report.
Underdrain System
The use of underdrain systems below sewer mains and services is a common
method to control shallow groundwater in response to development. We recommend an
underdrain system be incorporated into sanitary sewer and sewer collection systems.
Underdrains should also be installed below sewer service lines.
If installed, the underdrain should consist of free -draining gravel surrounding a rigid
PVC pipe. The pipe should be sized for anticipated flow. The 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 immediately
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
developed 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 the underdrain system.
PRELIMINARY PAVEMENT RECOMMENDATIONS
Due to the preliminary nature of this exploration, pavement section recommendations
cannot be finalized until additional testing is performed. This section is provided for planning
purposes only.
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE
CTL I T PROJECT NO. FC04631-115
Subgrade Preparation
Based on the borings, the near surface soils on this site will consist of clays, silts,
and sands. Up to 2 feet of fill was encountered in four of our borings. If encountered, fill
should be removed and replaced as described in the Site Grading section of this report. If
soft or yielding soils are encountered, chemical or mechanical stabilization of these soils will
improve their subgrade support characteristics, in addition to enhancing the workability of the
clays and reducing water infiltration into the underlying subgrade and the potential
movements under the pavements.
Preliminary Pavement Thickness Design
Preliminary guidelines for pavement systems on this site are provided. Final
pavement sections should be determined based on the anticipated frequency of truck load
applications and other traffic on the pavement during the desired design life. Flexible hot
mixed asphaltic concrete pavement (HMAC) or rigid portland cement concrete (PCC)
pavements can be used at this site for automobile and light truck traffic use. Rigid
pavements are recommended in any areas subject to heavy truck traffic. We anticipate
asphalt pavement sections for local residential streets will be on the order of 5 to 6 inches
thick. Collectors and other higher volume pavement will likely require thicker pavement
sections, estimated on the order 6 to 8 inches.
Portland cement concrete (PCC) pavement is recommended in areas subject to any
heavy truck traffic such as garbage pickup and/or dumpster trucks and any heavy delivery
trucks. We recommend the use of 5 inches of portland cement concrete for general area
pavements which are not subject to truck traffic. A minimum 6 inch thick section is
recommended in main drives and any areas subject to some moderately heavy truck traffic.
Any areas subject to frequent heavy trucks should be designed based on frequency and
wheel loads. PCC pavements in this area are typically reinforced. Properly designed control
joints and other joints systems are required to control cracking and allow pavement
movement.
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE 12CTLITPROJECTNO. FC04631-115
PRELIMINARY RECOMMENDATIONS FOR STRUCTURES
The field and laboratory data indicate the soil conditions vary across the site. The
following discussions are preliminary and are not intended for design or construction. After
grading is completed, a design level soils and foundation investigation should be performed.
Due to the preliminary nature of this project, site grading plans have not been
prepared, and therefore are not available for review in conjunction with this subsurface
exploration program. Therefore, recommendations provided are general and for planning
purposes only.
Foundations
Our investigation for this site indicates the anticipated structures may be founded on
shallow foundations such as spread footings or mat foundations bearing on the native soil or
engineered fill. A design level geotechnical investigation may identify conditions not
indicated by our borings which may require a need for a deeper foundation system. Deep
foundations may be required in areas of shallow bedrock, cuts that extend into bedrock and
for structures with heavy column loads.
Slabs -on -Grade and Floor Construction
The soils at this site include clays, silts, sands, gravels, cobbles, and boulders. The
overburden soils at this site are considered to be non -expansive; therefore we anticipate
most of the site will be rated as low slab performance. Slab movement of 1 to 3 inches is
considered "normal' for this level of risk. Slab performance risk should be more thoroughly
defined during the design level geotechnical investigation.
Surface Drainage
The performance of foundations will be influenced by surface drainage. The ground
surface around 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 unpaved landscaping areas surrounding
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE 13CTLITPROJECTNO. FC04631-115
structures. There are practical limitations on achieving these slopes but they should be
achieved wherever possible. Irrigation should be minimized to control wetting. Roof
downspouts should discharge beyond 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 reduce erosion.
WATER-SOLUBLE SULFATES
Concrete that comes into contact with soils can be subject to sulfate attack. We
measured water-soluble sulfate concentrations in two samples from this site.
Concentrations were below measurable limits in one sample and 0.02 percent in the second
sample. Sulfate concentrations less than 0.1 percent indicate Class 0 exposure to sulfate
attack for concrete that comes into contact with the subsoils, according to the American
Concrete Institute (ACI). For this level of sulfate concentration, ACI indicates any type of
cement can be used for concrete that comes into contact with the subsoils. In our
experience, superficial damage may occur to the exposed surfaces of highly permeable
concrete, even though sulfate levels are relatively low. To control this risk and to resist
freeze -thaw deterioration, the water-to-cementitious material 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 be air entrained.
RECOMMENDED FUTURE INVESTIGATIONS
Based on the results of this investigation and the proposed development, we
recommend the following investigations be performed by our firm:
1. Review of final site grading plans;
2. Design and sizing of the underdrain systems;
3. Subgrade investigation and pavement design after grading;
4. Design -level soils and foundation investigations after grading; and
5. Construction testing and observation for site development and building
construction.
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE 14CTLITPROJECTNO. FC04631-115
LIMITATIONS
Our exploratory borings were located to obtain preliminary subsurface data indicative
of conditions on this site. Although our borings were spaced to obtain a reasonably
accurate picture of subsurface conditions, variations not indicated in our borings are always
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 understanding 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 planned development from the geotechnical point of view, please contact the
undersigned.
Very truly yours,
CTL I THOMPSON, INC.
B'.x•01—
Benny I. Lujan
Staff Engineer
Reviewed by:
R.B. "Chip" Leadbetter III,
Geotechnical Department
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE
CTL IT PROJECT NO. FC04631-115
i
Robin Dourest, P.G.
Project Manager
4-51,
F
s/ON ALA V f
15
APPROX. SCALB: + - jW
ar
FORT COL1INS - ESTATE 300.
500 EAST VINE DRIVE CTL
I T PROJECT NO. FCC 31-115 LEGEND:
TH-
1 INDICATES APPROXIMATE LOCATION
OF EXPLORATORY BORING.
TP-
5 INDICATES APPROXIMATE LOCATION
OF TEST PIT. DR-
1 INDICATES APPROXIMATE LOCATION
OF DOUBLE RING INFILTROMETER
TEST. Locations
of Exploratory
Borings
and Test
Pits FIGURE
1
APPROX. SCALE: 1'= 100'
0 50' 100,
r+ s
n
TH-6
DR-2 i
IF
LEGEND:
TH-1 INDICATES APPROXIMATE
DR-1 (2'1 O) 0 LOCATION OF EXPLORATORY
BORING.
TP-5 INDICATES APPROXIMATE
LOCATION OF TEST PIT.
DR-1 INDICATES APPROXIMATE
LOCATION OF DOUBLE RING
INFILTROMETER TEST.
e
17,0) INDICATES APPROXIMATE DEPTHIm• TO BEDROCK.
Measured Depth
to Bedrock
Surface
FORT COLLINS REAL ESTATE
ON CTL
ICTPR PROJECTNO. FC0034-115 FIGURE 2
APPROX. SCALE: 1— 100'
0 50, too'
F
rr.+ TH- I
6)
v, i
DR-2
THE
4
m.w tm c.a• riw um
T CG1i e1S R— ESTA.
300-500 EAST —E OR VE
Cn I T PRO ECI-1 F-631115
THA
DR-4 TP-5
TI1-T (5)
M DR-3 (5)
TH•1
DR-1 (•
TH 3
7)
LEGEND:
TH-1 INDICATES APPROXIMATE
LOCATION OF EXPLORATORY
BORING.
TP-5 INDICATES APPROXIMATE
LOCATION OF TEST PIT.
DR-1 INDICATES APPROXIMATE
LOCATION OF DOUBLE RING
INFILTROMETER TEST.
6) INDICATES APPROXIMATE DEPTH
TO GROUNDWATER.
Measured
Depth to
Groundwater
FIGURE 3
APPROX. SCALE: V= 20001
D?ODO
0 V lI 1 .J %-
Q'E
FORT COLLWS REAL ESTATE
3W-600 EAST VINE DRW
CTL I T PROJECT NO. FOU631-115
LEGEND:
Qpp POST -PINEY CREEK ALLUVIUM -
Clay, silt, sand, gravel, and cobbles
Qs SLOCUM ALLUVIUM - Clay, silt,
sand, gravel, and cobbles
Kprl PIERRE SHALE, RICHARD
SANDSTONE MEMBER - Sandstone
with shale and daystone
Kpu PIERRE SHALE, UPPER SHALE
MEMBER - Shale and daystone
Kpm PIERRE SHALE, MIDDLE SHALE
MEMBER - Claystone, shale and
siltstone
Geologic Map
of Site and
Surrounding
Areas
FIGURE 4
APPENDIX A
LOGS OF EXPLORATORY BORINGS
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE
CTL I T PROJECT NO. FC04631-115
0
5
10
15
TH-1
ON
i
2s/12
O
b-
a
0=
0=
L; Q
wLL
20
0DFawn
25
30
35
L40
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE
CTL I T PROJECT NO. FC04631-115
i r
TH-2 TH-3 TH-4
0
9/12 26/12 17/12
5
a ' 46/12 23/12 30/12
a C o
0• 4&-
a-
D0=
0=
fl 15
I- w
50/3 w
20
I - awn
25 —
30
35
40
SUMMARY LOGS OF EXPLORATORY BORINGS
FIGURE A-1
TH-5 TH-6 TH-7 TH-6 TP-5
0 0 0
G: v
D, i
d'
Q 4:
5 -
C 8112 29f12 4112
5aa
p: C'• 40/12
AA e• Y
10/12
ii
10 a. 10
15016 a 25112
w ® A'
20 r 20
w0
50/2
25 25
30
35
40
FORT COLLINS REN. ESTATE
300-50) EAST NNE DRIVE
CTL IT PROJECT NO. FCORl91-115
LEGEND:
ASPHALTIC CONCRETE AND BASE COURSE
FILL, GRAVEL, SANDY, MOIST, BROWN, RED
SILT, SANDY, GRAVELLY TO SAND, SILTY AND CLAY. SILTY, MOIST, LOOSE TO DENSE,
SOFT TO VERY STIFF, BROWN (ML, SM. CL)
GRAVEL, SANDY WITH OCCASIONAL COBBLES AND BOULDERS, MOIST TO WET, MEDIUM
jd. DENSE TO DENSE, BROWN, REDDISH BROWN (GP, GW)
INTERBEDDED CLAYSTONElSANDSTONE, MOIST TO WET, HARD TO VERY HARD,
GRAYISH -BROWN, OLIVE -BROWN
DRIVE SAMPLE. THE SYMBOL INDICATES BLOWS OF A 140-POUND HAMMER FALLING 30
INCHES WERE REQUIRED TO DRIVE A 2.54NCH O.D. SAMPLER INCHES.
FDRIVE SAMPLE. THE SYMBOL INDICATES BLOWS OF A 140-POUND HAMMER FALLING 30
INCHES WERE REQUIRED TO DRIVE A 2.0-INCH O.D. SAMPLER INCHES.
BULK SAMPLE FROM AUGER CUTTINGS.
WATER LEVEL MEASURED AT TIME OF DRILLING.
WATER LEVEL MEASURED AUGUST 12, 2008.
1
PRACTICAL DRILL REFUSAL.
NOTES:
1. THE BORINGS WERE DRILLED ON AUGUST 1, 2008 USING 4-INCH DIAMETER
CONTINUOUS FLIGHT AUGERS AND A TRUCK -MOUNTED DRILL RIG.
2. THESE LOGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND CONCLUSIONS IN
THIS REPORT.
3. THE APPROXIMATE LOCATIONS OF THE BORINGS ARE INDICATED ON FIGURE 1
SUMMARY LOGS OF EXPLORATORY BORINGS
FIGURE A-2
APPENDIX B
LABORATORY TEST RESULTS
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE
CTL I T PROJECT NO. FC04631-115
3
2
1
z 0
O
rn
z
a _
1a
x
W
z -2
O
W
M -3
a
2
O
U
a
Li
ADDITIONAL COMPRESSION UNDER
CONSTANT PRESSURE DUE TO
WETTING
ram-•-- - - - - - - --- ------ ---'1-7- ---T--------- ------r-4
r------- ____,_
1_____________________
f _---- ---------------- --------- 1
r -
I
T--------- - - - - -- ------ - - - -- -- „
0.1 1.0
APPLIED PRESSURE - KSF
Sample of SILT, SANDY (ML)
From TH -1 AT 4 FEET
3
2
1
z
O 0
Z
Q
a
X -1
W
0
z
O -2
N
N
W
IM
AL -3
2
O
v
10 100
DRY UNIT WEIGHT= 105 PCF
MOISTURE CONTENT= 22.5 %
ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE DUE
I---------.-------------------------T WETTING
y - _ _ _ - - -I_ _ 1 _ _ 1 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ - - - _
J_-_______________________,___---
r
r------,----,-----,---r, _-r--.---.-------
r--------------------- ---a
F------I------- --;----------- - - - - ------------------- - - - - ------ - - -- -i
r------------------------------------------------------------=---------- =-1
0.1
APPLIED PRESSURE - KSF
Sample of SAND, SILTY (SM)
From TH - 2 AT 4 FEET
FORT COLLINS REAL ESTATE
300.500 EAST VINE DRIVE
CTL I T PROJECT NO. FC04631-115
1.0 10 100
DRY UNIT W EIGHT= 11 PCF
MOISTURE CONTENT= 16.9 %
Swell Consolidation
Test Results
FIGURE B-1
Z
O
rn
Z
a
a
W -
5
OR
Z
O -6
N
N
W
W
d -7
2
O
0
8
ADDITIONAL COMPRESSION UNDER
CONSTANT PRESSURE DUE TO WETTING
r--,---:---------.-----------------
I -------- I, - ------- I ------------------
I - - -- - a
L - ------------..----------- -------
I
r _ _ _ _ - - - _ - _ - _ _ _ _ _ - _ _ _ _ - - - - r _ _ - - - - _ _ _ - _ _ - _ _ _ _
r _ - _ _,
1 '
I
I I
I i i I
a.—i---—__ — — — _I—--_y_____--.
I 1
i I
I ' 1
I _ _ _ _ _ _ _ _ _
r — _ _ _ _ _ _ _ _ — _ _ _I— _ _ — — _ _ - _ - — _ _ _ _ _ _ _
L — — — — — — — — — — —
1 — — — — — — — — — — — — — — — — — - — — — — — — — — —— — —
r _ _ _ - _ _ _ _ _ r _ - - - _ _
r----------- I ------- I --------------------------------------------------- -
1-i
I--------------------------------------------- —
0.1
APPLIED PRESSURE - KSF
Sample of SILT, SANDY (ML)
From TH - 4 AT 4 FEET
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE
CTL I T PROJECT NO. FC04631-115
1.0 10 100
DRY UNIT WEIGHT= 102 PCF
MOISTURE CONTENT= 24.2 %
Swell Consolidation
Test Results
FIGURE B-2
Z
O
W
Z
Q
a -sx
W
O
z
O -6
N
W
X
IL -7
2
O
v
6
L---------------------=------------------------------
I
I_ - _ _ - _ _ 1 _ _ _ _ _ _ _ _. _ _ _ _ _ _ _ - _ 1 _ _ _ _ _ - - _ _ _ _ L _ _ - - - - - - - - - - - - - - _ _ _ - - - _ - - -
I
i
I
r_,_--- ________________--- _-_
I
I
a _ _ _ _I_ _ _ a _ - - _ _ _ _ - _ a - - _ - _ - _ _ _ - - - _ _ _ - - - _ _ _ _ 1 - - - _ _ - _
I
I
I
a - _ _ _ - -I_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
I
i _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ y _
1 _ _ - _ - - _ _ _ _ _ 1
a--*-- - - - - - - - - - - - - - - J - _ _ _ _ - _ _ _ _ _ - - - - _ _ - - _ - - _ _ -
I
I
t----------------------`------------------------- ----------------------j!
r-------------------.------.--------------------------------------------- ---.I
0.1 1.0
APPLIED PRESSURE - KSF
Sample of CLAY, SANDY (CL)
From TH -SAT 4 FEET
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE
CTL I T PROJECT NO. FC04631-115
10 100
DRY UNIT WEIGHT= 101 PCF
MOISTURE CONTENT= 26.2 %
Swell Consolidation
Test Results
FIGURE B-3
IF
HYDROMETER -
11 1 11 11 11' I . •I 1 „
CLAY PLASTIC) TO SILT (NON -PLASTIC)
Sample of GRAVEL, SANDY (GW) GRAVEL 55 % SAND 41 %
From TH - 1 AT 9 FEET SILT & CLAY 4 % LIQUID LIMIT %
PLASTICITY INDEX %
HYDROMETER ANALYSIS SIEVE ANALYSIS
25 HR. 7 HR. TIME READINGS U.S. STANDARD SERIES CLEAR SQUARE OPENINGS
45 MIN. 15 MIN. 60 MIN. 19 MIN. 4 MIN. 1 MIN. '200 -100 '50 -40 -30 116 110 -8 -4 3/8' W4' W 3' 516, B'
100 _—. _. — _. 0
T
t.
T 20
30
z -- wz
a 60 40 ti
w '-- ---t--------
a --- IrwCL60
30 70
20
10 90
0
001 0.002 .005 .009 .019 .037 .074 149 .297
0•
590 1.19 2.0 2.38 4.76 9.52 19.1 36.1 76.2 127 200
152
DIAMETER OF PARTICLE IN MILLIMETERS
CLAY (PLASTIC) TO SILT (NON -PLASTIC)
SANDS GRAVEL
FINE I MEDIUM ICOARSEI FINE I COARSE I COBBLES
Sample Of GRAVEL, SANDY (GP) GRAVEL 57 % SAND 39 %
From TH - 7 AT 4 FEET SILT & CLAY 4 % LIQUID LIMIT %
PLASTICITY INDEX %
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE
PROJECT NO. FC04631-115
Gradation
Test Results
FIGURE B-4
140
r-----t--- ------r-{----------T---------
I---------------
L-=---- ---------- =---- '----------------
TP-5
135 T
CURVE
MAXIMUM DRY DENSITY
1-------------------
112.5 PCF
I OPTIMUM MOISTURE CONTENT
r--------r----------- r-------------------- --- 14.0 %
130 - -- --
J - - - - - - - - - - - - - - - - - - - - - - - - - - L _ _ _ _ _ _ - - L - 1
i _ _ _ _ _ -.- - .. _ _ _ - _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ - _ 1 _ _ _ i_ _ - - _ _ _ _ -
r------,--r-------------- T-------------------__------
r--•------F---------------r-------- I - - -- ^-- --------
r-------- -------
125
L- ---------------------I-'
I------=--------=
r - r r
ZERO AIR VOIDS SPECIFIC GRAVITY = 2.71
120
LL
V--------------------------------- ------ --,-
a------- --------- - -
r - --
N 115 a ...._._._
W---- - - - - -----------------------I------',--.--I------ ------l---------- I--
r----- - -.
L-
r--- --r-T----.--!------'I ---i -r----r----I--f -r- ------- ---r-T---
i___ r__-_r_Y---._,__--r---.--•-_----r_-_
a - 4-4-
I I
110
I ;
r------,--r-r-;--------------
L-r------- --- - - --
r-.- r ---- - - - -I- - - -- ----- -,--- -r- T --
I- -- ---- -- --- - - - - - -I- - -- -- --
1 _ _ _ _ - - _ L - - _ - _ _ _ -- - - - - - - - - - - - - - - - -
105
r-'----!--r---,--.--,----r----,-
r-------1'__----_-:--
r- --'------ ---- --- -- -----r----- --- r----i------ ^ - -- --
a - - - - - - - - - - - - - - - - - - - - 4 _ 1 - - - - - - - - - - - - - - _ _ _ _ - _ - - - -
7-
4 - - - i - - - - - _ - - - -
I
100
r- ------ --- ^- --- - - --- ----- - - -
I -----
T---
1-1------r-L-1------i----'-L------- -"- -- 1-J--i----a-1--
I_ I_ _ _ _ - - _ _ - - - - - -
i - - -
95
0 5 10 15 20 25 30 35
MOISTURE CONTENT - %
Unified Soil Classification System(USCS) SILT, GRAVELLY, SANDY (ML) LIQUID LIMIT NP %
AASHTO Soil Classification A-4 (0) PLASTICITY INDEX NC —%
Location TP-5 @ V to 5' GRAVEL (USCS) 30 %
300-500 E. Vine SAND (USCS) 22 pie
Compaction Test Procedure ASTM D 698-91 SILT AND CLAY 48 %
METHOD C
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE Compaction
CTL I T PROJECT NO. FC04631-115
Test Results FIGURE B-5
TABLE B-1
SUMMARY OF LABORATORY TESTING lit
BORING
DEPTH
FEET)
MOISTURE
CONTENT
DRY
DENSITY
PCF
ATTERBERG LIMITS SWELL TEST RESULTS' PASSING
NO.200
SIEVE
SOLUBLE
SULFATES
DESCRIPTION
LIQUID
LIMIT
PLASTICITY
INDEX SWELL`
APPLIED
PRESSURE
PSF)
SWELL
PRESSURE
PSF
TH-1 4 22.5 105 0.1 1,000 SILT, SANDY ML
TH-1 9 6.0 4 GRAVEL, SANDY GW
TH-2 4 16.9 111 NL NP 0.1 1,000 17 SAND, SILTY SM
TH-2 9 8.9 5 GRAVEL, SANDY GP
TH-3 4 0.020 GRAVEL, SANDY GP
TH-3 9 7.6 4 GRAVEL, SANDY GP
TH-3 19 20.8 21 SANDSTONE
TH-4 4 24.2 102 0.1 1,000 SILT, SANDY ML
TH-4 9 6.8 4 GRAVEL, SANDY GP
TH-6 4 11.6 12 SAND, SILTY SM
TH-7 4 7.7 4 GRAVEL, SANDY GP
TH-7 14 15.5 38 SANDSTONE
TH-8 4 26.2 101 0.1 1,000 0.002 CLAY, SILTY CL
TH-8 24 19.9 100 33 ISANDSTONE
TP-5 1-5 7.0 NL NP 48 ISILT, GRAVELLY, SANDY ML
NEGATIVE VALUE INDICATES COMPRESSION.
FORT COLLINS REAL ESTATE
300.500 EAST VINE DRIVE
CTLIT PROJECT NO. FC04631-115 Page 1 of 1
APPENDIX C
EXAMPLE SITE GRADING SPECIFICATIONS
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE
CTL I T PROJECT NO. FC04631-115
EXAMPLE SITE GRADING SPECIFICATIONS
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 material 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 D 698.
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 greaterthan six (6) inches. Fill materials
shall be obtained from cut areas shown on the plans or staked in the field by the
Engineer.
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.
FORT COLLINS REAL ESTATE Appendix C-1300-500 EAST VINE DRIVE pp
CTL IT PROJECT NO. FC04631-115
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
Depth from
Soil Moisture Requirement
Final Grade Density Requirement
Type from optimum)
feet)
Clay 0 to +3 95% of ASTM D 698
0 to 15 feet
Sand 2 to +2 95% of ASTM D 698
Clay Greater than 15
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 Soils Engineer, it is not possible to obtain uniform
moisture content by adding water on the fill surface. The Contractor may be required
to rake 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 delayed 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.
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.
FORT COLLINS REAL ESTATE Appendix C-2
300-500 EAST VINE DRIVE
CTL I T PROJECT NO. FC04631-115
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. Granular 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.
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 interrupted 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.
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE
CTL IT PROJECT NO. FC04631-115
Appendix C-3
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.
FORT COLLINS REAL ESTATE
300-500 EAST VINE DRIVE
CTL I T PROJECT NO. FC04631-115
Appendix C-4