HomeMy WebLinkAboutBRICK STONE APARTMENTS ON HARMONY - Filed SEPD-SURFACE EXPLORATION/PAVEMENT DESIGN REPORT - 2018-01-05Responsive ■ Resourceful ■ Reliable
REPORT TOPICS
REPORT TOPICS
INTRODUCTION ............................................................................................................. 1
SITE CONDITIONS ......................................................................................................... 2
PROJECT DESCRIPTION .............................................................................................. 2
GEOTECHNICAL CHARACTERIZATION ...................................................................... 3
GEOTECHNICAL OVERVIEW ....................................................................................... 3
EARTHWORK................................................................................................................. 4
PAVEMENTS .................................................................................................................. 8
GENERAL COMMENTS ............................................................................................... 12
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ATTACHMENTS
EXPLORATION AND TESTING PROCEDURES
SITE LOCATION AND EXPLORATION PLAN
EXPLORATION RESULTS (Boring Logs and Laboratory Data)
SUPPORTING INFORMATION (General Notes, UCSC Classifications)
Geotechnical Engineering Report
Right Turn Lane at Brick Stone Apartments ■ Fort Collins, Colorado
December 13, 2017 ■ Terracon Project No. 20175093
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REPORT SUMMARY
Topic
1
Overview Statement
2
Project
Description
Plans indicate eastbound Harmony Road will be widened to the south to include an
acceleration and deceleration lane providing access to the proposed apartment
complex. The widening will include one lane and reconfiguration of the bike lane.
Geotechnical
Characterization
Subsurface conditions encountered in our exploratory boring generally consisted of
clayey sand with varying amounts of silt and gravel extending to the maximum
depths of exploration of about 10 feet below existing site grades. In some areas
about 6 feet of undocumented sandy lean clay fill was encountered above the clayey
sands.
Earthwork
On-site soils typically appear suitable for use as general engineered fill on the site
provided they are placed and compacted as described in this report. We anticipate
up to about 5 feet of fill will likely be required to construct the embankment for the
roadway widening. We have specified certain properties of fill materials in this report
to be used to construct the roadway embankment to develop our recommended
pavement thickness alternatives.
Pavements
Recommended pavement thickness for this project include 7 inches of asphalt over
18 inches of aggregate base course. Additional pavement section alternatives and
discussion are presented in the report.
General
Comments
This section contains important information about the limitations of this geotechnical
engineering report.
1. If the reader is reviewing this report as a pdf, the topics above can be used to access the appropriate section
of the report by simply clicking on the topic itself.
2. This summary is for convenience only. It should be used in conjunction with the entire report for design
purposes.
Geotechnical Engineering Report
Right Turn Lane at Brick Stone Apartments ■ Fort Collins, Colorado
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INTRODUCTION
Geotechnical Engineering Report
Right Turn Lane at Brick Stone Apartments
Eastbound East Harmony Road, East of South College Avenue
Fort Collins, Colorado
Terracon Project No. 20175093
December 13, 2017
INTRODUCTION
This report presents the results of our subsurface exploration and geotechnical engineering
services performed for the proposed right-hand turn lane to be located along the eastbound lane
of East Harmony Road, east of South College Avenue in Fort Collins, Colorado. The purpose of
these services is to provide information and geotechnical engineering recommendations relative
to:
■ Subsurface soil conditions ■ Site preparation and earthwork
■ Excavation considerations ■ Pavement design and construction
The geotechnical engineering scope of services for this project included the advancement of two
test borings to depths of approximately 10 feet below existing site grades.
We submitted this report in draft form to the City of Fort Collins for review of recommendations
and input. The City has requested that one additional boring be performed at the site once the
subgrade is at finished elevation. The additional boring will be completed to a depth of
approximately 10 feet below existing site grades. Samples will be tested for swell, R-value and
soil classification in order to confirm soil properties and design parameters presented in this report
are followed. By following recommendations in this report for fill properties, we believe this
additional boring will confirm conditions achieved during construction. It is of high importance that
quality control of material properties and proper construction of the embankment is achieved in
order to reduce risk of soils not meeting or exceeding expected properties.
Maps showing the site and boring locations are provided in the Site Location and Exploration
Plan sections, respectively. The results of the laboratory testing performed on soil samples
obtained from the site during the field exploration are included on the boring logs and as separate
graphs in the Exploration Results section of this report.
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SITE CONDITIONS
The following description of site conditions is derived from our site visit in association with the
field exploration and our review of publicly available geologic and topographic maps.
Item Description
Parcel Information
The proposed roadway widening is planned along eastbound East Harmony
Road, east of South College Avenue in Fort Collins, Colorado. The
approximate Latitude/Longitude of the center of the roadway widening is
40.42340°N/105.07456°W. See Site Location.
Existing
Improvements
East Harmony Road is a four-lane, major arterial with some areas of center
turn lanes and landscape islands. The area planned for widening is vacant
land planned for the Brick Stone Apartments development.
Current Ground
Cover
The ground surface outside of the existing concrete curb and gutter is
covered with native grasses and weeds.
Existing Topography The site is relatively flat with a downward slope along the south side of the
site toward the proposed Brick Stone Apartment site.
PROJECT DESCRIPTION
Our initial understanding of the project was provided in our proposal and was discussed in the
project planning stage. A period of collaboration has transpired since the project was initiated,
and our final understanding of the project conditions is as follows:
Item Description
Information Provided
We were provided with civil drawings for the project prepared by Northern
Engineering (Project No. 1229-001; plans dates August 29, 2017)
Project Description
Plans indicate eastbound East Harmony Road will be widened to the south
to include an acceleration and deceleration lane providing access to the
proposed apartment complex. The widening will include on lane and
reconfiguration of the bike lane.
Grading/Slopes
Cuts and fills will be necessary for the widening. Our observation of current
site grades suggests possibly up to 5 feet of fill placement may be
necessary to achieve final grades.
Pavements
Upon submittal of this report in draft form to the City of Fort Collins for
review and approval, we were provided with the following EDAL/ESALS for
the proposed right-hand turn lane.
EDAL/ESAL: 300/2,190,000
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GEOTECHNICAL CHARACTERIZATION
Subsurface Profile
Specific conditions encountered at each boring location are indicated on the individual boring logs.
Stratification boundaries on the boring logs represent the approximate location of changes in soil
types; in situ, the transition between materials may be gradual. Details for each of the borings can
be found in Exploration Results. A discussion of field sampling and laboratory testing procedures
and test results are presented in Exploration and Testing Procedures. Based on the results of
the borings, subsurface conditions on the project site can be generalized as follows:
Stratum Approximate Depth to
Bottom of Stratum (feet) Material Description Consistency/Density
Surface 0.4 Topsoil --
1
About 6 feet below existing
side grades, only
encountered in boring
number two.
Fill: Sandy lean clay --
2 To the maximum depths of
exploration of about 10 feet.
Clayey sand with varying amounts of
silt and gravel
Medium dense
Conditions encountered at each boring location are indicated on the individual boring logs shown
in the Exploration Results section and are attached to this report. Stratification boundaries on
the boring logs represent the approximate location of changes in native soil types; in situ, the
transition between materials may be gradual.
Groundwater Conditions
The boreholes were observed while drilling and after completion for the presence and level of
groundwater. Groundwater was not observed in the borings while drilling, or for the short duration
the borings could remain open. Groundwater level fluctuations occur due to seasonal variations in
the amount of rainfall, runoff and other factors not evident at the time the borings were performed.
Therefore, groundwater levels during construction or at other times in the life of the pavements
may be higher or lower than the levels indicated on the boring logs. However, we do not believe
groundwater will significantly impact this project.
GEOTECHNICAL OVERVIEW
Based on subsurface conditions encountered in the borings, the site appears suitable for the
proposed construction from a geotechnical point of view provided certain precautions and design
and construction recommendations described in this report are followed. We have identified
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geotechnical conditions that could impact design, construction and performance of the proposed
turn lane. These included existing, undocumented fill, and potentially loose, low strength soils.
These conditions will require particular attention in project planning, design and during
construction and discussed in greater detail in the following sections.
Existing, Undocumented Fill
Existing, undocumented fill was encountered in the upper 6 feet of Boring No. 2. Support of
pavements on or above existing fill materials is discussed in this report. However, even with the
recommended construction procedures, there is an inherent risk for the owner that compressible
fill or unsuitable material within or buried by the fill will not be discovered. This risk of unforeseen
conditions cannot be eliminated without completely removing the existing fill, but can be reduced
by following the recommendations contained in this report. At a minimum, we recommend
thoroughly proof rolling the exposed subgrade after stripping to assist with delineating any soft or
loose areas that will require repair prior to embankment and roadway construction.
Low Strength Soils
Loose clayey sand soils were encountered within the borings completed at this site. These
materials can be susceptible to disturbance and loss of strength under repeated construction
traffic loads and unstable conditions could develop. Stabilization of soft soils may be required at
some locations to provide adequate support for construction equipment and final conditions for
embankment construction. Terracon should be contacted if these conditions are encountered to
observe the conditions exposed and to provide guidance regarding stabilization (if needed).
EARTHWORK
Earthwork will include clearing and grading, excavations and fill placement. The following sections
provide recommendations for use in the preparation of specifications for the work.
Site Preparation
Prior to placing fill, existing vegetation and root mat should be removed. Complete stripping of the
topsoil should be performed in the proposed pavement areas.
The subgrade should be proof-rolled with an adequately loaded vehicle such as a fully loaded
tandem axle dump truck. The proof-rolling should be performed under the direction of the
Geotechnical Engineer. Areas excessively deflecting under the proof-roll should be delineated
and subsequently addressed by the Geotechnical Engineer. Such areas should either be removed
or modified by stabilizing with fly ash or geotextiles could also be considered as a stabilization
technique. Laboratory evaluation is recommended to determine the effect of chemical
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stabilization on subgrade soils prior to construction. Excessively wet or dry material should either
be removed or moisture conditioned and recompacted.
Excavation
It is anticipated that excavations for the proposed construction can be accomplished with
conventional earthmoving equipment. Excavations into the on-site soils will encounter weak and/or
saturated soil conditions with possible caving conditions.
The soils to be excavated can vary significantly across the site as their classifications are based
solely on the materials encountered in widely-spaced exploratory test borings. The contractor
should verify that similar conditions exist throughout the proposed area of excavation. If different
subsurface conditions are encountered at the time of construction, the actual conditions should be
evaluated to determine any excavation modifications necessary to maintain safe conditions.
If unexpected fills or underground facilities are encountered, such features should be removed and
the excavation thoroughly cleaned prior to backfill placement and/or construction.
Depending upon depth of excavation and seasonal conditions, surface water infiltration and/or
groundwater may be encountered in excavations on the site. It is anticipated that pumping from
sumps may be utilized to control water within excavations.
The subgrade soil conditions should be evaluated during the excavation process and the stability
of the soils determined at that time by the contractors’ Competent Person. Slope inclinations flatter
than the OSHA maximum values may have to be used. 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.
As a safety measure, it is recommended that all vehicles and soil piles be kept a minimum lateral
distance from the crest of the slope equal to the slope height. The exposed slope face should be
protected against the elements
Subgrade Preparation
After the vegetative layer has been removed from the construction area, the top 8 inches of the
exposed ground surface should be scarified, moisture conditioned, and recompacted to at least
95 percent of the maximum dry unit weight as determined by ASTM D698 before any new fill or
pavement is placed.
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After the bottom of the excavation has been compacted, engineered fill can be placed to bring the
pavement subgrade to the desired grade. Engineered fill should be placed in accordance with
the recommendations presented in subsequent sections of this report.
The stability of the subgrade may be affected by precipitation, repetitive construction traffic or
other factors. If unstable conditions develop, workability may be improved by scarifying and
drying. Alternatively, over-excavation of wet zones and replacement with granular materials may
be used, or crushed gravel and/or rock can be tracked or “crowded” into the unstable surface soil
until a stable working surface is attained. Lightweight excavation equipment may also be used to
reduce subgrade pumping.
Fill Material Types
Originally we understood that the Larimer County Urban Area Street Standards (LCUASS)
requirement of soil borings be completed after completion of grading was not being enforced for
this project. We based our calculations and analysis to develop recommended pavement
thickness on assumed values for fill to be placed as embankment fills for the proposed turn lane.
We submitted this report in draft form to the City of Fort Collins for review of recommendations
and input. The City has requested that one additional boring be performed at the site once the
subgrade is at finished elevation. The additional boring will be completed to a depth of
approximately 10 feet below existing site grades. Samples will be tested for swell, R-value and
soil classification in order to confirm soil properties and design parameters presented in this report
are followed. By following recommendations in this report for fill properties, we believe this
additional boring will confirm conditions achieved during construction. It is of high importance that
quality control of material properties and proper construction of the embankment is achieved in
order to reduce risk of soils not meeting or exceeding expected properties.
We recommend the following properties for fill:
Gradation Percent finer by weight (ASTM C136)
4” 100
3” 70-100
No. 4 Sieve 50-100
No. 200 Sieve 50 (max.)
Soil Properties Values
R-Value 20 (minimum)
Liquid Limit 30 (max.)
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Soil Properties Values
Plastic Limit 6 (max.)
Non-expansive
Less than 1.0% expansive when remolded to
97% of the maximum dry unit weight as
determined by ASTM D698 and at 1% below
optimum moisture content.
Terracon should also be retained to provided field density compaction testing during embankment
construction. Test results should indicate the earthwork contractor has achieved the required
moisture content and percent compaction prior to placement of aggregate base course or
pavement materials. We will also obtain samples of the embankment fill for laboratory testing to
confirm soil properties are within the recommended limits presented in the table above.
Fill Compaction Requirements
Engineered fill should be placed and compacted in horizontal lifts, using equipment and procedures
that will produce recommended moisture contents and densities throughout the lift.
Item Description
Fill lift thickness
9 inches or less in loose thickness when heavy, self-
propelled compaction equipment is used
4 to 6 inches in loose thickness when hand-guided
equipment (i.e. jumping jack or plate compactor) is used
Minimum compaction requirements 95 percent of the maximum dry unit weight as determined by
ASTM D698.
Moisture content cohesive soil (clay) -1 to +3 % of the optimum moisture content
Moisture content cohesionless soil
(sand) -3 to +3 % of the optimum moisture content
1. We recommend engineered fill be tested for moisture content and compaction during placement.
Should the results of the in-place density tests indicate the specified moisture or compaction limits
have not been met, the area represented by the test should be reworked and retested as required
until the specified moisture and compaction requirements are achieved.
2. Specifically, moisture levels should be maintained low enough to allow for satisfactory compaction to
be achieved without the fill material pumping when proofrolled.
3. Moisture conditioned clayey materials should not be allowed to dry out. A loss of moisture within these
materials could result in an increase in the material’s expansive potential. Subsequent wetting of these
materials could result in undesirable movement.
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Grading and Drainage
All grades must be adjusted to provide effective drainage away from the proposed pavements
and existing pavements and buildings during construction and maintained throughout the life of
the proposed project. Infiltration of water into pavement excavations must be prevented during
construction. Landscape irrigation adjacent to pavements should be minimized or eliminated.
Water permitted to pond near or adjacent to the perimeter of the pavements (either during or post-
construction) can result in significantly higher soil movements than those discussed in this report.
As a result, any estimations of potential movement described in this report cannot be relied upon
if positive drainage is not obtained and maintained, and water is allowed to infiltrate the fill and/or
subgrade.
Flatwork and pavements will be subject to post-construction movement. Maximum grades
practical should be used for paving and flatwork to prevent areas where water can pond. In
addition, allowances in final grades should take into consideration post-construction movement
of flatwork, particularly if such movement would be critical.
Exterior Slab Design and Construction
Exterior slabs on-grade, exterior architectural features, and utilities founded on, or in backfill or
the site soils will likely experience some movement due to the volume change of the material.
Potential movement could be reduced by:
n Minimizing moisture increases in the backfill;
n Controlling moisture-density during placement of the backfill;
n Using designs which allow vertical movement between the exterior features and
adjoining structural elements; and
n Placing control joints on relatively close centers.
PAVEMENTS
Pavements – Subgrade Preparation
Originally, we understood that the Larimer County Urban Area Street Standards (LCUASS)
requirement of soil borings be completed after completion of grading was not being enforced for
this project. We based our calculations and analysis to develop recommended pavement
thickness on assumed values for fill to be placed as embankment fills for the proposed turn lane.
We submitted this report in draft form to the City of Fort Collins for review of recommendations
and input. The City has requested that one additional boring be performed at the site once the
subgrade is at finished elevation. The additional boring will be completed to a depth of
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approximately 10 feet below existing site grades. Samples will be tested for swell, R-value and
soil classification in order to confirm soil properties and design parameters presented in this report
are followed. By following recommendations in this report for fill properties, we believe this
additional boring will confirm conditions achieved during construction. It is of high importance that
quality control of material properties and proper construction of the embankment is achieved in
order to reduce risk of soils not meeting or exceeding expected properties. Fill for embankments
and pavements should meet fill requirements presented in the Earthwork section of this report.
Once acceptable fill that meets all fill requirements has been placed below pavement areas, the
subgrade should be carefully evaluated at the time of pavement construction for signs of
disturbance or instability. We recommend the pavement subgrade be thoroughly proofrolled with
a loaded tandem-axle dump truck prior to final grading and paving. All pavement areas should
be moisture conditioned and properly compacted to the recommendations in this report
immediately prior to paving.
Pavements – Design Recommendations
Design of pavements for the project have been based on the procedures outlined in the 1993
Guideline for Design of Pavement Structures prepared by the American Association of State
Highway and Transportation Officials (AASHTO) and the Larimer County Urban Area Street
Standards (LCUASS).
Samples of the on-site materials selected for swell-consolidation testing exhibited no movement to
0.5 percent swell when wetted under an applied pressure of 150 psf which is less than the maximum
2 percent criteria established for determining if swell-mitigation procedures in the pavement sections
are required per LCUASS standards. Our recommendations for embankment fill also require the
fill to be non-expansive to low swelling. Therefore, swell-mitigation of the subgrade materials prior
to pavement operations is not required.
Upon submittal of this report in draft form to the City of Fort Collins for review and approval, we
were provided with the following an EDLA of 300 and ESALS of 2,190,000 for the proposed right-
hand turn lane.
For flexible pavement design, a terminal serviceability index of 2.5 was utilized along with an inherent
reliability of 90 percent and a design life of 20 years. Using the correlated design R-value of 20,
appropriate ESAL, environmental criteria and other factors, the structural numbers (SN) of the
pavement sections were determined on the basis of the 1993 AASHTO design equation.
In addition to the flexible pavement design analyses, a rigid pavement design analysis was
completed based upon AASHTO design procedures. Rigid pavement design is based on an
evaluation of the Modulus of Subgrade Reaction of the soils (k-value), the Modulus of Rupture of
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the concrete, and other factors previously outlined. The design k-value of 100 for the subgrade
soil was determined by correlation to the laboratory test results. A modulus of rupture of 600 psi
(working stress 450 psi) was used for pavement concrete. The rigid pavement thickness for each
traffic category was determined on the basis of the AASHTO design equation.
Recommended minimum pavement sections are provided in the table below.
Alternative
Recommended Pavement Thicknesses (Inches)
Asphaltic
Concrete
Surface
Aggregate
Base Course
Portland
Cement
Concrete
Total
A 7 18 - 25
B 9 10 - 19
C - - 9 9
Aggregate base course (if used on the site) should consist of a blend of sand and gravel which
meets strict specifications for quality and gradation. Use of materials meeting Colorado
Department of Transportation (CDOT) Class 5 or 6 specifications is recommended for aggregate
base course. Aggregate base course should be placed in lifts not exceeding 6 inches and
compacted to a minimum of 95 percent of the maximum dry unit weight as determined by ASTM
D698.
Asphaltic concrete should be composed of a mixture of aggregate, filler and additives (if required)
and approved bituminous material. The asphalt concrete should conform to approved mix
designs stating the Superpave properties, optimum asphalt content, job mix formula and
recommended mixing and placing temperatures. Aggregate used in asphalt concrete should
meet particular gradations. Material meeting CDOT Grading S specifications or equivalent is
recommended for asphalt concrete. Mix designs should be submitted prior to construction to
verify their adequacy. Asphalt material should be placed in maximum 3-inch lifts and compacted
within a range of 92 to 96 percent of the theoretical maximum (Rice) density (ASTM D2041).
Where rigid pavements are used, the concrete should be produced from an approved mix design
with the following minimum properties:
Properties Value
Compressive strength 4,000 psi
Cement type Type I or II portland cement
Entrained air content (%) 5 to 8
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Properties Value
Concrete aggregate ASTM C33 and CDOT section 703
Concrete should be deposited by truck mixers or agitators and placed a maximum of 90 minutes
from the time the water is added to the mix. Longitudinal and transverse joints should be provided
as needed in concrete pavements for expansion/contraction and isolation per ACI 325. The
location and extent of joints should be based upon the final pavement geometry. Joints should
be sealed to prevent entry of foreign material and doweled where necessary for load transfer.
Pavement performance is affected by its surroundings. In addition to providing preventive
maintenance, the civil engineer should consider the following recommendations in the design and
layout of pavements:
n Site grades should slope a minimum of 2 percent away from the pavements;
n The subgrade and the pavement surface have a minimum 2 percent slope to promote proper
surface drainage;
n Consider appropriate edge drainage and pavement under drain systems;
n Install pavement drainage surrounding areas anticipated for frequent wetting;
n Install joint sealant and seal cracks immediately;
n Seal all landscaped areas in, or adjacent to pavements to reduce moisture migration to
subgrade soils; and
n Placing compacted, low permeability backfill against the exterior side of curb and gutter.
Pavements – Construction Considerations
Openings in pavement, such as landscape islands, are sources for water infiltration into
surrounding pavements. Water collects in the islands and migrates into the surrounding subgrade
soils thereby degrading support of the pavement. This is especially applicable for islands with
raised concrete curbs, irrigated foliage, and low permeability near-surface soils. The civil design
for the pavements with these conditions should include features to restrict or to collect and
discharge excess water from the islands. Examples of features are edge drains connected to the
storm water collection system or other suitable outlet and impermeable barriers preventing lateral
migration of water such as a cutoff wall installed to a depth below the pavement structure.
Pavements – Maintenance
Preventative maintenance should be planned and provided for an ongoing pavement
management program in order to enhance future pavement performance. Preventive
maintenance consists of both localized maintenance (e.g. crack and joint sealing and patching)
and global maintenance (e.g. surface sealing). Preventative maintenance is usually the first
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priority when implementing a planned pavement maintenance program and provides the highest
return on investment for pavements.
GENERAL COMMENTS
Our services are conducted with the understanding of the project as described in the proposal,
and will incorporate collaboration with the design team as we complete our services to verify
assumptions. Revision of our understanding to reflect actual conditions important to our services
will be based on these verifications and will be reflected in the final report. The design team should
collaborate with Terracon to confirm these assumptions and to prepare the final design plans and
specifications. This facilitates the incorporation of our opinions related to implementation of our
geotechnical recommendations. Any information conveyed prior to the final report is for
informational purposes only and should not be considered or used for decision-making purposes.
Our analysis and opinions are based upon our understanding of the geotechnical conditions in
the area, the data obtained from our site exploration and from our understanding of the project.
Variations will occur between exploration point locations, across the site, or due to the modifying
effects of construction or weather. The nature and extent of such variations may not become
evident until during or after construction. Terracon should be retained as the Geotechnical
Engineer, where noted in the final report, to provide observation and testing services during
grading, excavation, foundation construction and other earth-related construction phases of the
project. If variations appear, we can provide further evaluation and supplemental
recommendations. If variations are noted in the absence of our observation and testing services
on-site, we should be immediately notified so that we can provide evaluation and supplemental
recommendations.
Our scope of services does not include either specifically or by implication any environmental or
biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of
pollutants, hazardous materials or conditions. If the owner is concerned about the potential for
such contamination or pollution, other studies should be undertaken.
Our services and any correspondence are intended for the sole benefit and exclusive use of our
client for specific application to the project discussed and are accomplished in accordance with
generally accepted geotechnical engineering practices with no third party beneficiaries intended.
Any third party access to services or correspondence is solely for information purposes only.
Reliance upon the services and any work product is limited to our client, and is not intended for
third parties. Any use or reliance of the provided information by third parties is done solely at their
own risk. No warranties, either express or implied, are intended or made.
Site characteristics as provided are for design purposes and not to estimate excavation cost. Any
use of our report in that regard is done at the sole risk of the excavating cost estimator as there
may be variations on the site that are not apparent in the data that could significantly impact
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excavation cost. Any parties charged with estimating excavation costs should seek their own site
characterization for specific purposes to obtain the specific level of detail necessary for costing.
Site safety, and cost estimating including, excavation support, and dewatering
requirements/design are the responsibility of others. If changes in the nature, design, or location
of the project are planned, our conclusions and recommendations shall not be considered valid
unless we review the changes and either verify or modify our conclusions in writing.
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EXPLORATION AND TESTING PROCEDURES
Field Exploration
The field exploration program consists of the following:
Number of Borings Planned Boring Depth (feet)
1 Planned Location
2 10 or auger refusal Roadway widening areas
1. Below ground surface
Boring Layout and Elevations: We use handheld GPS equipment to locate borings with an
estimated horizontal accuracy of +/-20 feet. Field measurements from existing site features may
be utilized. If available, approximate elevations are obtained by interpolation from a site specific,
surveyed topographic map.
Subsurface Exploration Procedures: We advance the borings with a truck-mounted, track-
mounted, ATV-mounted rotary drill rig using continuous-flight augers (solid-stem and/or hollow-
stem as necessary depending on soil conditions). Three samples are obtained in the upper 10 feet
of each boring. In the thin-walled tube sampling procedure, a thin-walled, seamless steel tube with
a sharp cutting edge is pushed hydraulically into the soil to obtain a relatively undisturbed sample. In
the split-barrel sampling procedure, a standard 2-inch outer diameter split-barrel sampling spoon is
driven into the ground by a 140-pound automatic hammer falling a distance of 30 inches. The number
of blows required to advance the sampling spoon the last 12 inches of a normal 18-inch penetration
is recorded as the Standard Penetration Test (SPT) resistance value. The SPT resistance values,
also referred to as N-values, are indicated on the boring logs at the test depths. A 3-inch O.D. split-
barrel sampling spoon with 2.5-inch I.D. ring lined sampler may be used where appropriate. Ring-
lined, split-barrel sampling procedures are similar to standard split spoon sampling procedure;
however, blow counts are typically recorded for 6-inch intervals for a total of 12 inches of
penetration. We observe and record groundwater levels during drilling and sampling. For safety
purposes, all borings are backfilled with flowable fill after their completion.
Our exploration team prepares field boring logs as part of standard drilling operations including
sampling depths, penetration distances, and other relevant sampling information. Field logs include
visual classifications of materials encountered during drilling, and our interpretation of subsurface
conditions between samples. Final boring logs, prepared from field logs, represent the
geotechnical engineer's interpretation, and include modifications based on observations and
laboratory tests.
Geotechnical Engineering Report
Right Turn Lane at Brick Stone Apartments ■ Fort Collins, Colorado
December 13, 2017 ■ Terracon Project No. 20175093
Responsive ■ Resourceful ■ Reliable
Property Disturbance: We backfill borings with flowable fill after completion. Our services do not
include repair of the site beyond backfilling our boreholes. Excess auger cuttings are dispersed
in the general vicinity of the boreholes.
Laboratory Testing
The project engineer reviews field data and assigns various laboratory tests to better understand
the engineering properties of various soil and rock strata. Exact types and number of tests cannot
be defined until completion of field work. Testing will be performed under the direction of a
geotechnical engineer and may include the following.
■ Visual classification
■ Water content
■ Dry density
■ Atterberg limits
■ Grain-size analysis
■ One-dimensional swell
Our laboratory testing program often includes examination of soil samples by an engineer. Based
on the material’s texture and plasticity, we describe and classify soil samples in accordance with
the Unified Soil Classification System (USCS).
If bedrock samples are obtained, rock classification is conducted using locally accepted practices
for engineering purposes; petrographic analysis (if performed) may reveal other rock types. Boring
log rock classification is determined using the Description of Rock Properties.
SITE LOCATION AND EXPLORATION PLANS
SITE LOCATION AND EXPLORATION PLANS
SITE LOCATION
Right Turn Lane at Brick Stone Apartments on Harmony ■ Fort Collins, CO
December 5, 2017 ■ Terracon Project No. 20175093
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT
INTENDED FOR CONSTRUCTION PURPOSES
TOPOGRAPHIC MAP IMAGE COURTESY OF THE U.S. GEOLOGICAL SURVEY
QUADRANGLES INCLUDE: FORT COLLINS, CO (1984).
SITE
EXPLORATION PLAN
Right Turn Lane at Brick Stone Apartments on Harmony ■ Fort Collins, CO
December 5, 2017 ■ Terracon Project No. 20175093
AERIAL PHOTOGRAPHY PROVIDED BY
MICROSOFT BING MAPS
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT
INTENDED FOR CONSTRUCTION PURPOSES
EXPLORATION RESULTS
EXPLORATION RESULTS
48
9
7
12
92
36-18-18
9-12
10-9-7
N=16
6-6-5
N=11
+0.5/150
0.4
10.5
TOPSOIL
CLAYEY SAND WITH GRAVEL (SC), brown, tan, medium dense
Boring Terminated at 10.5 Feet
GRAPHIC LOG
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20175093 RIGHT TURN LANE A.GPJ TERRACON_DATATEMPLATE.GDT 12/5/17
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
LL-PL-PI
ATTERBERG
LIMITS
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
SAMPLE TYPE
FIELD TEST
RESULTS
SWELL - CONSOL
/LOAD
(%/psf)
DEPTH
LOCATION
Latitude: 40.5233° Longitude: -105.0751°
See Exploration Plan
Page 1 of 1
Advancement Method:
4" continous flight auger
Abandonment Method:
Boring backfilled with auger cuttings upon completion.
1901 Sharp Point Dr Ste C
Fort Collins, CO
Notes:
Project No.: 20175093
Drill Rig: CME 75
Boring Started: 11-07-2017
BORING LOG NO. 1
CLIENT: SEEC Enterprises, LLC
Boulder, CO
Driller: Drilling Engineers, Inc.
Boring Completed: 11-07-2017
PROJECT: Right Turn Lane at Brick Stone Apartments
49
18
13
14
101
107 26-19-7
5-9
2-4-4
N=8
7-10
0.4
6.0
10.0
TOPSOIL
FILL - SANDY LEAN CLAY , with gravel, light brown, tan, trace
gravel
SILTY CLAYEY SAND (SC-SM), light brown, tan, medium dense,
trace gravel
Boring Terminated at 10 Feet
GRAPHIC LOG
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20175093 RIGHT TURN LANE A.GPJ TERRACON_DATATEMPLATE.GDT 12/5/17
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
LL-PL-PI
ATTERBERG
LIMITS
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
SAMPLE TYPE
FIELD TEST
RESULTS
SWELL - CONSOL
/LOAD
(%/psf)
DEPTH
LOCATION
Latitude: 40.5234° Longitude: -105.0746°
See Exploration Plan
Page 1 of 1
Advancement Method:
4" continous flight auger
Abandonment Method:
Boring backfilled with auger cuttings upon completion.
1901 Sharp Point Dr Ste C
Fort Collins, CO
Notes:
Project No.: 20175093
Drill Rig: CME 75
Boring Started: 11-07-2017
BORING LOG NO. 2
CLIENT: SEEC Enterprises, LLC
Boulder, CO
Driller: Drilling Engineers, Inc.
0
10
20
30
40
50
60
0 20 40 60 80 100
CL or OL CH or OH
ML or OL
MH or OH
"U" Line
"A" Line
ATTERBERG LIMITS RESULTS
ASTM D4318
P
L
A
S
T
I
C
I
T
Y
I
N
D
E
X
LIQUID LIMIT
1901 Sharp Point Dr Ste C
Fort Collins, CO
PROJECT NUMBER: 20175093
SITE: Eastbound E Harmony Rd and S College
Ave
Fort Collins, Colorado
CLIENT: SEEC Enterprises, LLC
Boulder, CO
PROJECT: Right Turn Lane at Brick Stone
Apartments on Harmony
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. ATTERBERG LIMITS 20175093 RIGHT TURN LANE A.GPJ TERRACON_DATATEMPLATE.GDT 11/29/17
4 - 5.5
9 - 10
36
26
18
19
18
7
48
49
SC
SC-SM
CLAYEY SAND with GRAVEL
SILTY, CLAYEY SAND
Boring ID Depth LL PL PI Fines USCS Description
1
2
CL-ML
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
100 10 1 0.1 0.01 0.001
30 40
1.5 50
6 8 200
4 10 14
1 3/4
1/2 60
GRAIN SIZE IN MILLIMETERS
PERCENT FINER BY WEIGHT
U.HYDROMETERS. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
4 3/8
3 3 100 140
2
GRAIN SIZE DISTRIBUTION
ASTM D422 / ASTM C136
6 16
20
1901 Sharp Point Dr Ste C
Fort Collins, CO
PROJECT NUMBER: 20175093
SITE: Eastbound E Harmony Rd and S College
Ave
Fort Collins, Colorado
CLIENT: SEEC Enterprises, LLC
Boulder, CO
PROJECT: Right Turn Lane at Brick Stone
Apartments on Harmony
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS-2 20175093 RIGHT TURN LANE A.GPJ TERRACON_DATATEMPLATE.GDT 11/29/17
CLAYEY SAND with GRAVEL (SC)
SILTY, CLAYEY SAND (SC-SM)
0.189
0.098
25
12.5
36
26
47.8
49.5
24.9
-10
-8
-6
-4
-2
0
2
4
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited 0.5 percent swell upon wetting under an applied pressure of 150 psf.
PROJECT NUMBER: 20175093
SITE: Eastbound E Harmony Rd and
S College Ave
Fort Collins, Colorado
CLIENT: SEEC Enterprises, LLC
Boulder, CO
1901 Sharp Point Dr Ste C
Fort Collins, CO
Specimen Identification Classification , pcf
1 92 9
WC, %
2 - 3 ft CLAYEY SAND with GRAVEL
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20175093 RIGHT TURN LANE A.GPJ TERRACON_DATATEMPLATE.GDT 11/29/17
PROJECT: Right Turn Lane at Brick
Stone Apartments
-10
-8
-6
-4
-2
0
2
4
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited no movement upon wetting under an applied pressure of 150 psf.
PROJECT NUMBER: 20175093
SITE: Eastbound E Harmony Rd and
S College Ave
Fort Collins, Colorado
CLIENT: SEEC Enterprises, LLC
Boulder, CO
1901 Sharp Point Dr Ste C
Fort Collins, CO
Specimen Identification Classification , pcf
2 101 19
WC, %
2 - 3 ft SANDY LEAN CLAY
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20175093 RIGHT TURN LANE A.GPJ TERRACON_DATATEMPLATE.GDT 11/29/17
PROJECT: Right Turn Lane at Brick
Stone Apartments
SUPPORTING INFORMATION
SUPPORTING INFORMATION
Right Turn Lane at Brick Stone Apartments on Harmony Fort Collins, Colorado
12/05/2017 Terracon Project No. 20175093
500 to 1,000
> 8,000
4,000 to 8,000
2,000 to 4,000
1,000 to 2,000
less than 500
Unconfined Compressive Strength
Qu, (psf)
Modified
Dames &
Moore Ring
Sampler
Standard
Penetration
Test
Trace
PLASTICITY DESCRIPTION
Water levels indicated on the soil boring logs are
the levels measured in the borehole at the times
indicated. Groundwater level variations will occur
over time. In low permeability soils, accurate
determination of groundwater levels is not possible
with short term water level observations.
DESCRIPTION OF SYMBOLS AND ABBREVIATIONS
GENERAL NOTES
> 30
11 - 30
Low 1 - 10
Non-plastic
Plasticity Index
#4 to #200 sieve (4.75mm to 0.075mm
Boulders
Cobbles 12 in. to 3 in. (300mm to 75mm)
Gravel 3 in. to #4 sieve (75mm to 4.75 mm)
Sand
Silt or Clay Passing #200 sieve (0.075mm)
Particle Size
Water Level After
a Specified Period of Time
Water Level After a
Specified Period of Time
Water Initially
Encountered
Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dry
weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less
than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they
are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be added
according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined on the basis
of their in-place relative density and fine-grained soils on the basis of their consistency.
GRAIN SIZE TERMINOLOGY
RELATIVEFINES PROPORTIONS OF SAND AND GRAVEL RELATIVE PROPORTIONS OF
DESCRIPTIVE SOIL CLASSIFICATION
LOCATION AND ELEVATION NOTES
SAMPLING WATER LEVEL FIELD TESTS
N
(HP)
(T)
(DCP)
UNIFIED SOIL CLASSIFICATION SYSTEM
Right Turn Lane at Brick Stone Apartments ■ Fort Collins, Colorado
December 5, 2017 ■ Terracon Project No. 20175093
UNIFIED SOIL CLASSI FICATI ON SYSTEM
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A
Soil Classification
Group
Symbol Group Name
B
Coarse-Grained Soils:
More than 50% retained
on No. 200 sieve
Gravels:
More than 50% of
coarse fraction
retained on No. 4 sieve
Clean Gravels:
Less than 5% fines C
Cu ‡ 4 and 1 £ Cc £ 3 E GW Well-graded gravel
F
Cu < 4 and/or 1 > Cc > 3 E GP Poorly graded gravel
F
Gravels with Fines:
More than 12% fines C
Fines classify as ML or MH GM Silty gravel F,G,H
Fines classify as CL or CH GC Clayey gravel F,G,H
Sands:
50% or more of coarse
fraction passes No. 4
sieve
Clean Sands:
Less than 5% fines D
Cu ‡ 6 and 1 £ Cc £ 3 E SW Well-graded sand
I
Cu < 6 and/or 1 > Cc > 3 E SP Poorly graded sand
I
Sands with Fines:
More than 12% fines D
Fines classify as ML or MH SM Silty sandG,H,I
Fines classify as CL or CH SC Clayey sandG,H,I
Fine-Grained Soils:
50% or more passes the
No. 200 sieve
Silts and Clays:
Liquid limit less than 50
Inorganic:
PI > 7 and plots on or above “A”
line J
CL Lean clayK,L,M
PI < 4 or plots below “A” lineJ ML Silt
K,L,M
Organic:
Liquid limit - oven dried
< 0.75 OL Organic clay
K,L,M,N
Liquid limit - not dried Organic silt K,L,M,O
Silts and Clays:
Liquid limit 50 or more
Inorganic:
PI plots on or above “A” line CH Fat clayK,L,M
PI plots below “A” line MH Elastic Silt K,L,M
Organic:
Liquid limit - oven dried
< 0.75 OH Organic clay
K,L,M,P
Liquid limit - not dried Organic silt K,L,M,Q
Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat
A Based on the material passing the 3-inch (75-mm) sieve
B If field sample contained cobbles or boulders, or both, add “with cobbles
or boulders, or both” to group name.
C Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded
gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly
graded gravel with silt, GP-GC poorly graded gravel with clay.
D Sands with 5 to 12% fines require dual symbols: SW-SM well-graded
sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded
sand with silt, SP-SC poorly graded sand with clay
E Cu = D60/D10 Cc =
10 60
2
30
D x D
(D )
F If soil contains ‡ 15% sand, add “with sand” to group name.
G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.
H If fines are organic, add “with organic fines” to group name.
I If soil contains ‡ 15% gravel, add “with gravel” to group name.
J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.
K If soil contains 15 to 29% plus No. 200, add “with sand” or “with
gravel,” whichever is predominant.
L If soil contains ‡ 30% plus No. 200 predominantly sand, add
“sandy” to group name.
MIf soil contains ‡ 30% plus No. 200, predominantly gravel, add
“gravelly” to group name.
NPI‡ 4 and plots on or above “A” line.
OPI< 4 or plots below “A” line.
P PI plots on or above “A” line.
QPI plots below “A” line.
UC
(PID)
(OVA)
Standard Penetration Test
Resistance (Blows/Ft.)
Hand Penetrometer
Torvane
Dynamic Cone Penetrometer
Unconfined Compressive
Strength
Photo-Ionization Detector
Organic Vapor Analyzer
Medium
Over 12 in. (300 mm) 0
>12
5-12
<5
Percent of
Dry Weight
Major Component of Sample Term
Modifier
With
Trace
Descriptive Term(s) of
other constituents
Modifier >30
<15
Percent of
Dry Weight
Descriptive Term(s) of
other constituents
With 15-29
High
Unless otherwise noted, Latitude and Longitude are approximately determined using a hand-held GPS device. The accuracy of
such devices is variable. Surface elevation data annotated with +/- indicates that no actual topographical survey was conducted
to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic maps of the
area.
Standard Penetration or
N-Value
Blows/Ft.
Descriptive Term
(Density)
CONSISTENCY OF FINE-GRAINED SOILS
Hard
Very Dense > 50 Very Stiff 15 - 30
Dense 30 - 50 Stiff 8 - 15
Medium Dense 10 - 29 Medium Stiff 4 - 8
Loose 4 - 9 Soft 2 - 4
Very Loose 0 - 3 Very Soft 0 - 1
(50% or more passing the No. 200 sieve.)
Consistency determined by laboratory shear strength testing, field visual-manual
procedures or standard penetration resistance
STRENGTH TERMS
> 30
Descriptive Term
(Consistency)
Standard Penetration or
N-Value
Blows/Ft.
RELATIVE DENSITY OF COARSE-GRAINED SOILS
(More than 50% retained on No. 200 sieve.)
Density determined by Standard Penetration Resistance
1.6
7
14
27.2
48.9
4 - 5.5
9 - 10
4 - 5.5
9 - 10
WC (%) LL
D30 D10 %Gravel %Fines %Clay
1
2
18
7
18
19
Boring ID Depth USCS Classification PL PI Cc Cu
Boring ID Depth D100 D60 %Sand %Silt
medium
1
2
coarse fine coarse fine
COBBLES GRAVEL SAND
SILT OR CLAY
Boring Completed: 11-07-2017
PROJECT: Right Turn Lane at Brick Stone Apartments
on Harmony
See Supporting Information for explanation of
symbols and abbreviations.
Eastbound E Harmony Rd and S College Ave
Fort Collins, Colorado
SITE:
Not encountered
WATER LEVEL OBSERVATIONS
on Harmony
See Supporting Information for explanation of
symbols and abbreviations.
Eastbound E Harmony Rd and S College Ave
Fort Collins, Colorado
SITE:
Not encountered
WATER LEVEL OBSERVATIONS