Preliminary Geotechnical Evaluation ReportCITY OF CHANHASSEN
RECEIVED
SEP 16 2013
CHANHASSEN PLANNING DEPT
Preliminary Geotechnical Evaluation
Report
Lakes Business Park, Outlot F
Powers Boulevard and Lake Drive West
Chanhassen, Minnesota
Preporedfor
Copperwood Real Estate
Professional Certification:
I hereby certify that this plan, specification, or report
was prepared by me or under my direct supervision
and that 1 am a duly Licensed Professional Engineer
under the laws of the State of Minnesota.
Henry loo PE
rY , n; HENRY VLOO, PE 2 E
Associate — Senior Engineer
License Number: 21140 N4. 21140 t =�
February 13, 2013 �.;�A�.,__ _,dFS'�.��
Project BL -12 -07372
Braun Intertec Corporation
February 13, 2013
Mr. Mark Steingas
Copperwood Real Estate
6109 Blue Circle Drive, Suite 2100
Minnetonka, MN 55343
Re: Preliminary Geotechnical Evaluation
Lakes Business Park, Outlot F
Powers Boulevard and Lake Drive West
Chanhassen, Minnesota
Dear Mr. Steingas:
Braun Intertee Corporation
no01 Hampshire Ave S
Minneapolis, MN 55438
Project BL -12 -07372
Phone: 952.9952000
Fax: 952.995.2020
Web: braunintertec.com
We are pleased to present this Preliminary Geotechnical Evaluation Report for the proposed warehouse
building in Chanhassen, Minnesota. The purpose of our preliminary evaluation was to assist you and your
design team in evaluating the subsurface soil and groundwater conditions with regard to design and
construction of the proposed warehouse building. Please refer to the attached report for details
regarding our findings and preliminary recommendations.
Thank you for making Braun Intertec your geotechnical consultant for this project. If you have questions
about this report, or if there are other services that we can provide in support of our work to date, please
call Henry Vloo at 952.995.2238 or Greg Bialon at 952.995.2380.
Sincerely,
BRAUN INTERTEC CORPORATION
� /
Henry VI o, P
Associate — Senior Engineer
Grego 1. i to �
Vice President — Principal Engineer
Preliminary Geotechnical Evaluation Report
AA /EOE Providing engineering and environmental solutions since 1957
Table of Contents
Description Page
A. Introduction ........................................................................................................ ..............................1
A.1.
Project Description ................................................................................ ..............................1
A.2.
Purpose .................................................................................................. ..............................1
A.3.
Background Information and Reference Documents ............................ ..............................1
A.4.
Site Conditions ....................................................................................... ..............................1
A.S.
Scope of Services ................................................................................... ..............................1
B. Results
................................................................................................................ ..............................2
B.1.
Exploration Logs .................................................................................... ..............................2
B.1.a. Log of Boring Sheets ................................................................. ..............................2
B.1.b. Geologic Origins ....................................................................... ..............................3
B.2.
Geologic Profile ..................................................................................... ..............................3
B.2.a. Geologic Materials ................................................................... ..............................3
B.2.b. Groundwater ............................................................................ ..............................3
B.3.
Laboratory Test Results ......................................................................... ..............................3
C. Basis for
Recommendations ............................................................................... ..............................4
C.1.
Design Details ........................................................................................ ..............................4
C. 1. a. Building Structure Loads .......................................................... ..............................4
C.1.b. Pavements and Traffic Loads ................................................... ..............................4
C. 1. c. Anticipated Grade Changes ...................................................... ..............................4
C.1.d. Precautions Regarding Changed Information .......................... ..............................4
C.2.
Design and Construction Considerations .............................................. ..............................4
D. Preliminary
Recommendations .......................................................................... ..............................5
D.1.
Building and Pavement Subgrade Preparation ..................................... ..............................5
D.1.a. Excavations ............................................................................... ..............................5
D.1.b. Excavation Dewatering ............................................................. ..............................5
D.1.c. Selecting Excavation Backfill and Additional Required Fill ....... ..............................5
D.1.d. Placement and Compaction of Backfill and Fill ........................ ..............................6
D.2.
Spread Footings ..................................................................................... ..............................7
D.2.a. Embedment Depth ................................................................... ..............................7
D.2.b. Subgrade Improvement ........................................................... ..............................7
D.2.c. Net Allowable Bearing Pressure ............................................... ..............................7
D.2.d. Settlement ................................................................................ ..............................7
D.3.
Retaining Walls ...................................................................................... ..............................7
D.3.a. Drainage Control ...................................................................... ..............................8
D.3.b. Selection, Placement and Compaction of Backfill .................... ..............................8
D.3.c. Configuring and Resisting Lateral Loads ................................... ..............................9
Table of Contents (continued)
Description
Page
D.4.
Interior Slabs ......................................................................................... ..............................9
D.4.a. Subgrade Modulus ................................................................... ..............................9
D.4.b. Moisture Vapor Protection ..................................................... .............................10
D. 5.
Exterior Slabs ........................................................................................ .............................10
D.6.
Pavements ............................................................................................ .............................11
D.6.a. Subgrade Proof -Roll ................................................................ .............................11
D.6.b. Design Sections ....................................................................... .............................11
D.6.c. Subgrade Drainage .................................................................. .............................12
D.7.
Utilities ................................................................................................. .............................12
D.7.a. Subgrade Stabilization ............................................................. .............................12
D.7.b. Selection, Placement and Compaction of Backf ill ................... .............................12
D. 8.
Construction Quality Control ............................................................... .............................13
D.B.a. Excavation Observations ......................................................... .............................13
D.B.b. Materials Testing ..................................................................... .............................13
D.B.c. Pavement Subgrade Proof -Roll ............................................... .............................13
D.B.d. Cold Weather Precautions ...................................................... .............................13
D.9.
Additional Soil Borings ......................................................................... .............................14
E. Procedures
......................................................................................................... .............................14
E.1.
Penetration Test Borings ...................................................................... .............................14
E.2.
Material Classification and Testing ...................................................... .............................14
E.2.a. Visual and Manual Classification ............................................. .............................14
E.2.b. Laboratory Testing .................................................................. .............................14
E.3.
Groundwater Measurements ............................................................... .............................14
F. Qualifications ..................................................................................................... .............................15
F.1.
Variations in Subsurface Conditions ..................................................... .............................15
F.1.a. Material Strata ........................................................................ .............................15
F.1.b. Groundwater Levels ................................................................ .............................15
F.2.
Continuity of Professional Responsibility ............................................. .............................15
F.2.a. Plan Review ............................................................................. .............................15
F.2.b. Construction Observations and Testing .................................. .............................16
F.3.
Use of Report ........................................................................................ .............................16
F.4.
Standard of Care ................................................................................... .............................16
Appendix
Boring Location Sketch
Log of Boring Sheets, ST -1 through ST -4
Descriptive Terminology
BRAUN
INTERTEC
A. Introduction
A.1. Project Description
A new warehouse type building is planned for Outlot F within the Lakes Business Park in Chanhassen,
Minnesota. New drive areas and parking lots are also planned. The exact building location has not been
chosen yet.
A.2. Purpose
The purpose of our preliminary evaluation was to assist you and your design team in evaluating the
subsurface soil and groundwater conditions with regard to design and construction of the proposed
warehouse building.
A.3. Background Information and Reference Documents
To facilitate our evaluation, we were provided with or reviewed the following information or documents:
Topographic site map showing the site topography.
Geologic atlas showing the general soil types in the area.
A.4. Site Conditions
The site of the proposed warehouse building is an open field where the proposed building footprint and
surrounding pavements will be constructed. The site is bounded on the north by a rail line right -of way
and to the east by Powers Boulevard. The south and west sides of the proposed building site are wooded.
A.S. Scope of Services
Our scope of services for this project was originally submitted on January 15, 2013 as a Proposal to Mr.
Mark Steingas of Copperwood Real Estate. We received authorization to proceed from Mr. Steingas on
January 11, 2013. Tasks performed in accordance with our authorized scope of services included:
Staking and coordinating the clearing of exploration locations of underground utilities.
BRAUN
INTERTEC
Copperwood Real Estate
Project BL -12 -07372
February 13, 2013
Page 2
• Performing 4 penetration test.borings to nominal depths of 12 to 25 feet below grade.
Performing laboratory tests on selected penetration test samples.
• Preparing this preliminary report containing a boring location sketch, exploration logs, a
summary of the geologic materials encountered, results of laboratory tests, and preliminary
recommendations for structure subgrade preparation and the design of the proposed
project.
Exploration locations and surface elevations at the exploration locations were determined using GPS
(Global Positioning System) technology that utilizes the Minnesota Department of Transportation's
permanent GPS Virtual Reference Network (VRN). Boring ST -3 was moved about 20 feet to the
northwest because the staked location was not accessible for our equipment. Therefore the elevation at
this boring was estimated from the topographic site plan provided.
Our scope of services was performed under the terms of our June 15, 2006, General Conditions.
B. Results
B.1. Exploration Logs
B.1.a. Log of Boring Sheets
Log of Boring sheets for our penetration test borings are included in the Appendix. The logs identify and
describe the geologic materials that were penetrated, and present the results of penetration resistance
and other in -situ tests performed within them, laboratory tests performed on penetration test samples
retrieved from them, and groundwater measurements.
Strata boundaries were inferred from changes in the penetration test samples and the auger cuttings.
Because sampling was not performed continuously, the strata boundary depths are only approximate.
The boundary depths likely vary away from the boring locations, and the boundaries themselves may
also occur as gradual rather than abrupt transitions.
BRAUN
INTERTEC
Copperwood Real Estate
Project BL -12 -07372
February 13, 2013
Page 3
B.1.b. Geologic Origins
Geologic origins assigned to the materials shown on the logs and referenced within this report were
based on: (1) a review of the background information and reference documents cited above, (2) visual
classification of the various geologic material samples retrieved during the course of our subsurface
exploration, (3) penetration resistance data, (4) laboratory test results, and (5) available common
knowledge of the geologic processes and environments that have impacted the site and surrounding
area in the past.
B.2. Geologic Profile
B.2.a. Geologic Materials
The general geologic profile at the site consists (proceeding down from the ground surface) of a layer of
organic clay topsoil overlying glacially deposited clayey sand, sandy lean clay and lean clay. The topsoil
observed was from about 1/2 to 2 feet thick.
Penetration resistance values recorded in the clayey soils ranged from 9 to 27 blows per foot (BPF)
indicating consistencies of rather stiff to very stiff.
B.2.b. Groundwater
Groundwater was not observed as our borings were advanced. Based on the moisture contents of the
geologic materials encountered, it appears that groundwater was below the depths explored at the time
of this evaluation.
Seasonal and annual fluctuations of groundwater, however, should be anticipated.
B.3. Laboratory Test Results
The moisture content of the selected soil samples tested was determined to vary from approximately 13
to 20 percent, indicating that the material was likely slightly below to slightly above of its probable
optimum moisture content. The test results can be found in the right hand margin on the Log of Boring
sheets in the appendix of this report, opposite the soil sample tested.
BRAUN
INTERTEC
Copperwood Real Estate
Project BL -12 -07372
February 13, 2013
Page 4
C. Basis for Recommendations
C.1. Design Details
C.1.a. Building Structure Loads
A building size and type have not been determined yet. For the purpose of this report, we have assumed
that the building will be a one -story slab -on -grade structure. We have further assumed that bearing wall
loads associated with the perimeter walls will range from 4 to 5 kips (4,000 to 5,000 pounds) per linear
foot (klf) and column loads will range from 100 to 150 kips per column.
CA.b. Pavements and Traffic Loads
It is likely that the facility built on this site will have both light and heavy duty pavements. We have
assumed that the light -duty pavement areas will have a bituminous section and will be subjected to no
more than 50,000 equivalent 18 -kip single axle loads (ESALs) over an assumed design life of 20 years. We
have also assumed that the heavy -duty pavement areas will have a bituminous section and will be
subjected to no more than 1,000,000 ESALs over an assumed design life of 20 years.
CA.c. Anticipated Grade Changes
Since the proposed building has not been established yet, proposed grades have not been set. However,
you indicated to us that most of this site is high and will need to be cut to grade.
C.1.d. Precautions Regarding Changed Information
We have attempted to describe our understanding of the proposed construction to the extent it was
reported to us by others. Depending on the extent of available information, assumptions may have been
made based on our experience with similar projects. If we have not correctly recorded or interpreted the
project details, we should be notified. New or changed information could require additional evaluation,
analyses and /or recommendations.
C.2. Design and Construction Considerations
The geotechnical issues influencing development of this site appear to be limited. The geologic materials
present at anticipated structure subgrade elevations generally appear suitable for support of
conventional spread footings, grade - supported slabs, and pavements.
L1i[tl':il
INTERTEC
Copperwood Real Estate
Project BL -12 -07372
February 13, 2013
Page 5
Some of the clayey soils on this site may need to be dried and some of the clayey soils may need to be
wetted in order to use them for compacted fill. The amount of moisture conditioning is expected to be
less than 2 percentage points for both wet and dry soils.
The following section discusses general recommendations based on a number of future building
assumptions as stated above.
D. Preliminary Recommendations
D.1. Building and Pavement Subgrade Preparation
D.1.a. Excavations
We recommend removing the topsoil from beneath the future building and pavement areas. Based on
the borings, excavation depths are expected to range from approximately 1/2 to 2 feet.
Excavation depths will vary between the borings. Portions of the excavations may also be deeper than
indicated by the borings. Contractors should also be prepared to extend excavations in wet or fine -
grained soils to remove disturbed bottom soils.
To provide lateral support to replacement backfill, additional required fill and the structural loads they
will support, we recommend oversizing (widening) the excavations 1 foot horizontally beyond the outer
edges of the building perimeter footings, or pavement limits, for each foot the excavations extend below
bottom -of- footing or pavement subgrade elevations.
DA.b. Excavation Dewatering
Water was not observed in the soils as our borings were completed. However, in clayey soils, areas of
perched water could be encountered while grading. If encountered, we recommend removing
groundwater from the excavations such that fill and /or concrete can be placed in a dry excavation.
Sumps and pumps can be considered for excavations in low- permeability silt- and clay -rich soils.
D.1.c. Selecting Excavation Backfill and Additional Required Fill
If the bottoms of the excavations remain wet, we recommend that the initial layer of backfill over wet or
submerged excavation bottoms consist of at least 2 feet of coarse sand having less than 50 percent of the
particles by weight passing a #40 sieve, and less than 5 percent of the particles passing a #200 sieve. We
anticipate that this material will need to be imported.
BRAUN
INTERTEC
Copperwood Real Estate
Project BL -12 -07372
February 13, 2013
Page 6
On -site soils free of organic soil and debris can be considered for reuse as backfill and fill. The clayey
soils, however, being fine - grained, will be more difficult to compact if wet or allowed to become wet, or
if spread and compacted over wet surfaces. Some of the clayey soils may require additional moisture
such that they can be compacted.
We recommend that granular subbase material for pavement support consist of sand having less than 10
percent of the particles by weight passing a #200 sieve. We anticipate that this material will also need to
be imported.
As previously indicated, some of these soils may need to be exported from the site to prepare site
grades. The soils encountered by the borings appear to be suitable for use as compacted fill with some
moisture conditioning.
D.1.d. Placement and Compaction of Backfill and Fill
We recommend spreading backfill and fill in loose lifts of approximately 4 to 8 inches, depending on the
size of the compactor used. We recommend compacting backfill and fill in accordance with the criteria
presented below in Table 1. The relative compaction of utility backfill should be evaluated based on the
structure below which it is installed, and vertical proximity to that structure.
Table 1. Compaction Recommendations Summary
*Except for wall backfill. See Section D.3 of this report.
BRAUN
INTERTEC
Relative Compaction, percent
Moisture Content Variance from
Reference
(ASTM D 698 — standard Proctor)
Optimum, percentage points
Below foundations, less than
95
-1 to +3 for clay soils
10 feet of fill
± 3 for sandy soils
Below foundations, greater than
98
-1 to +2 for clay soils
10 feet of fill
± 3 for sandy soils
95
-1 to +3 for clay soils
Below slabs
± 3 for sandy soils
Below pavements, within 3 feet
100
-1 to +2 for clay soils
of top of subgrade elevations
± 3 for sandy soils
Below pavements, more than 3 feet
95
-1 to +3 for clay soils
below subgrade elevations
± 3 for sandy soils
90 *
-1 to +3 for clay soils*
Below landscaped surfaces *
± 3 for sandy soils
*Except for wall backfill. See Section D.3 of this report.
BRAUN
INTERTEC
Copperwood Real Estate
Project BL -12 -07372
February 13, 2013
Page 7
If there are areas of the site where more than 10 feet of fill is needed under buildings, a construction
delay may also be needed. This is to allow deeper clay fills to consolidate under its own weight.
Construction delays will likely range from 3 to 6 months and should be evaluated through the installation
and monitoring of settlement plates.
D.2. Spread Footings
D.2.a. Embedment Depth
For frost protection, we recommend embedding perimeter footings a minimum of 42 inches below the
lowest exterior grade. Interior footings may be placed directly below floor slabs. We recommend
embedding building footings not heated during winter construction, and other unheated footings
associated with canopies, stoops or sidewalks 60 inches below the lowest exterior grade.
D.2.b. Subgrade Improvement
The Subgrade soils are generally clayey and could be easily disturbed by construction activity. If the
footing subgrade soils become disturbed, the soils should be subcut a minimum of 6 inches and replaced
with 3/4- to 1 -inch clear rock.
D.2.c. Net Allowable Bearing Pressure
Depending on final site grading, we recommend sizing spread footings to exert a net allowable bearing
pressure of 2,000 to 4,000 pounds per square foot (psf). This value includes a safety factor of at least 3.0
with regard to bearing capacity failure. The net allowable bearing pressure can be increased by one -third
its value for occasional transient loads, but not for repetitive loads due to traffic, or for other live loads
from snow or occupancy.
D.2.d. Settlement
We estimate that total and differential settlements among the footings will amount to less than 1 inch
and 1/2 inch, respectively, under the assumed loads.
13.3. Retaining Walls
Although retaining walls on this site have not been planned for, the following section discusses the
general needs for construction of retaining walls.
BRAUN
INTERTEC
Copperwood Real Estate
Project BL -12 -07372
February 13, 2013
Page 8
D.3.a. Drainage Control
We recommend installing subdrains behind the retaining walls, adjacent to the wall footings. Preferably
the subdrains should consist of perforated pipes embedded in washed gravel, which in turn is wrapped in
filter fabric. Perforated pipes encased in a filter "sock' and embedded in washed gravel, however, may
also be considered.
We recommend routing the subdrains to a lower elevation part of the site or to a storm drain.
D.3.b. Selection, Placement and Compaction of Backfill
We recommend that backfill placed within 2 horizontal feet of any retaining walls consist of sand having
less than 50 percent of the particles by weight passing a #40 sieve and less than 5 percent of the particles
by weight passing a #200 sieve. Sand meeting this gradation will need to be imported. We recommend
that the balance of the backfill placed against retaining walls also consist of sand, though it is our opinion
that the sand may contain up to 20 percent of the particles by weight passing a #200 sieve.
If clay must be considered for used to make up the balance of the retaining wall backfill we further
recommend that:
The bottoms of the excavations required for retaining construction are wide enough to
accommodate compaction equipment.
Backfill is placed at moisture contents at least equal to, but not more than three percentage
points above, its optimum moisture content.
Backfill is placed in loose lifts no thicker than 6 inches prior to compaction.
The relative compaction of the backfill is measured through density testing at intervals not
exceeding one test per 50 horizontal feet for each vertical foot of backfill placed.
We recommend a walk behind compactor be used to compact the backfill placed within about 5 feet of
the retaining walls. Further away than that, a self - propelled compactor can be used. Compaction criteria
for below -grade walls should be determined based on the compaction recommendations provided above
in Section D.1.
The retaining wall backfill should be capped with a low- permeability soil to limit the infiltration of surface
drainage into the backfill. The finished surface should also be sloped to divert water away from the walls.
BRAUN
INTERTEC
Copperwood Real Estate
Project BL -12 -07372
February 13, 2013
Page 9
D.3.c. Configuring and Resisting Lateral Loads
Below -grade wall design can be based on active earth pressure conditions if the walls are allowed to
rotate slightly. If rotation cannot be tolerated, then design should be based on at -rest earth pressure
conditions. Rotation up to 0.002 times the wall height is generally required when walls are backfilled with
sand *. Rotation up to 0.02 times the wall height is required when walls are backfilled with clay.
To design for sand backfill, excavations required for wall construction should be wide enough and flat
enough so that sand is present within a zone that (1) extends at least two horizontal feet beyond the
bottom outer edges of the wall footings (the wall heel, not the stem) and then (2) rises up and away from
the wall at an angle no steeper than 60 degrees from horizontal. We anticipate these geometric conditions
will be met if the excavations meet OSHA requirements for the types of soils likely to be exposed in the
excavation, and the wall footings are cast against wood forms rather than any portion of the excavation.
Recommended equivalent fluid pressures forwall design based on active and at -rest earth pressure
conditions are presented below in Table 2. Assumed wet unit backfill weights, and internal friction angles
are also provided. The recommended equivalent fluid pressures in particular assume a level backfill with
no surcharge — they would need to be revised for sloping backfill or other dead or live loads that are
placed within a horizontal distance behind the walls that is equal to the height of the walls. Our design
values also assume that the walls are drained so that water cannot accumulate behind the walls.
Table 2. Recommended Below -Grade Wall Design Parameters
Resistance to lateral earth pressures will be provided by passive resistance against the retaining wall
footings, and by sliding resistance along the bottoms of the wall footings. We recommend assuming a
passive pressure equal to 300 pcf and a sliding coefficient equal to 0.30. These values are un- factored.
DA. Interior Slabs
DAa. Subgrade Modulus
We recommend using a modulus of subgrade reaction, k, of 100 pounds per square inch per inch of
deflection (pci) to design the slabs with a clayey subgrade.
BRAUN
INTERTEC
Equivalent Fluid
Equivalent Fluid
Wet Unit Weight
Friction Angle
Pressure, Active Case
Pressure, At -Rest Case
Backfill Soil
(pcf)
(deg)
(pcf)
(pcf)
Sand
120
1 33
1 35
55
Clay
120
1 26
1 50
70
Resistance to lateral earth pressures will be provided by passive resistance against the retaining wall
footings, and by sliding resistance along the bottoms of the wall footings. We recommend assuming a
passive pressure equal to 300 pcf and a sliding coefficient equal to 0.30. These values are un- factored.
DA. Interior Slabs
DAa. Subgrade Modulus
We recommend using a modulus of subgrade reaction, k, of 100 pounds per square inch per inch of
deflection (pci) to design the slabs with a clayey subgrade.
BRAUN
INTERTEC
Copperwood Real Estate
Project BL -12 -07372
February 13, 2013
Page 10
D.4.b. Moisture Vapor Protection
If floor coverings or coatings less permeable than the concrete slab will be used, we recommend that a
vapor retarder or vapor barrier be place immediately beneath the slab. Some contractors prefer to bury
the vapor retarder or barrier beneath a layer of sand to reduce curling and shrinkage, but this practice
risks trapping water between the slab and vapor retarder or barrier.
Regardless of where the vapor retarder or barrier is placed, we recommend consulting with floor
covering manufacturers regarding the appropriate type, use and installation of the vapor retarder or
barrier to preserve warranty assurances.
D.S. Exterior Slabs
It is likely that the exterior slabs could be underlain with lean clay, sandy lean clay or clayey sand, most of
which are considered to be moderately to highly frost susceptible. Soils of this type can retain moisture
and heave upon freezing. In general, this characteristic is not an issue unless these soils become
saturated due to surface runoff or infiltration or are excessively wet in -situ. Once frozen, unfavorable
amounts of general and isolated heaving of the soils and related surface features could also develop.
This type of heaving could impact design drainage patterns and the performance of the paved areas or
exterior slabs. To address most of the heave related issues, we recommend the general site grades and
grades for surface features be set to direct surface drainage away from buildings, across large paved
areas and away from walkways to limit the potential for saturation of the subgrade and any subsequent
heaving. General grades should also have enough "slope" shown to tolerate potential larger areas of
heave which may not fully settle when thawed.
Even small amounts of frost - related differential movement at walkway joints or cracks can create
tripping hazards. Several subgrade improvement options can be explored to address this condition. The
most conservative and potentially most costly subgrade improvement option to help limit the potential
for heaving, but not eliminate it, would be to remove any frost - susceptible soils present below the
exterior slabs "footprint" down to the bottom -of- footing grades or to a maximum depth of 5 feet below
subgrade elevations, whichever is less. We recommend the resulting excavation then be refilled with
sand or sandy gravel having less than 50 percent of the particles by weight passing the #40 sieve and less
than 5 percent of the particles by weight passing a #200 sieve.
INTERTEC
Copperwood Real Estate
Project BL -12 -07372
February 13, 2013
Page 11
Another subgrade improvement option would be to build in a transition zone between those soils
considered to be frost - susceptible and those that are not to somewhat control where any differential
movement may occur. Such transitions could exist between exterior slabs and pavements, between
entry way slabs and sidewalks, and along the sidewalks themselves. For this option, the frost - susceptible
soils in critical areas would be removed to a depth of at least 4 feet below grade as discussed above. The
excavation below the footprint of the sidewalks or other slabs would then be sloped upward at a
gradient no steeper than 3:1 (horizontal : vertical) toward the less critical areas. The bottom of the
excavation should then be sloped toward the center so that any water entering the excavation could be
quickly drained to the deepest area for removal. in the deepest areas of the excavation, a series of
perforated drainpipes will need to be installed to collect and dispose of surface water infiltration and /or
groundwater that could accumulate within the backfill. The piping would need to be connected to a
storm sewer or a sump to remove any accumulated water. If the water is not removed, it is our opinion
this option will not be effective in controlling heave.
Regardless of what is done to the walkway or pavement area subgrade, it will be critical the end -user
develop a detailed maintenance program to seal and /or fill any cracks and joints that may develop during
the useful life of the various surface features. Concrete and bituminous will experience episodes of
normal thermo- expansion and thermo- contraction during its useful life. During this time, cracks may
develop and joints may open up, which will expose the subgrade and allow any water flowing overland to
enter the subgrade and either saturate the subgrade soils or to become perched atop it. This occurrence
increases the potential for heave due to freezing conditions in the general vicinity of the crack orjoint.
This type of heave has the potential to become excessive if not addressed as part of a maintenance
program. Special attention should be paid to areas where dissimilar materials abut one another, where
construction joints occur and where shrinkage cracks develop.
D.6. Pavements
D.6.a. Subgrade Proof -Roll
Prior to placing aggregate base material, we recommend proof - rolling pavement subgrades to determine
if the subgrade materials are loose, soft or weak, and in need of further stabilization, compaction or sub-
excavation and re- compaction or replacement.
D.6.b. Design Sections
Laboratory tests to determine an R -value for pavement design were not included in the scope of this
project. Based on the soils present in the borings and our experience with similar projects in the area,
however, it is our opinion that an R -value of 10 can be assumed for design purposes with a clayey
subgrade.
BRAUN
INTERTEC
Copperwood Real Estate
Project BL -12 -07372
February 13, 2013
Page 12
Based upon the aforementioned traffic loads and an R -value of 10, we recommend a light -duty pavement
section that includes 3 1/2 inches of bituminous pavement (a 1 1/2 -inch surface course over a 2 -inch
base course) over 8 inches of aggregate base material. For heavy -duty areas, we recommend 4 inches of
bituminous pavement (a 11/2 -inch surface course over a 2 1/2 -inch base course) over 12 inches of
aggregate base material.
To provide better drainage and lowerfrost susceptibility for the pavements we also recommend that
both light and heavy duty pavements have at least 12 inches of select granular borrow placed below
them.
The above pavement designs are based upon a 20 -year performance life. This is the amount of time
before major reconstruction is anticipated. This performance life assumes maintenance, such as seal
coating and crack sealing, is routinely performed. The actual pavement life will vary depending on
variations in weather, traffic conditions and maintenance.
D.6.c. Subgrade Drainage
We recommend installing perforated drainpipes throughout pavement areas at low points and about
catch basins. The drainpipes should be placed in small trenches extended at least 8 inches below the
granular subbase layer — or aggregate base material where no subbase is present.
D.7. Utilities
D.7.a. Subgrade Stabilization
We anticipate that utilities can be installed per manufacturer bedding requirements. However if any soft
or unstable soils are encountered at pipe invert elevations, these soils should be subcut and replaced
with suitable bedding material.
D.7.b. Selection, Placement and Compaction of Backfill
We recommend selecting, placing and compacting utility backfill in accordance with the
recommendations provided above in Section D.1.
BRAUN
INTERTEC
Copperwood Real Estate
Project BL -12 -07372
February 13, 2013
Page 13
D.B. Construction Quality Control
D.B.a. Excavation Observations
We recommend having a geotechnical engineer observe all excavations related to subgrade preparation
and spread footing, slab -on -grade and pavement construction. The purpose of the observations is to
evaluate the competence of the geologic materials exposed in the excavations, and the adequacy of
required excavation oversizing.
D.8.11b. Materials Testing
We recommend density tests be taken in excavation backfill and additional required fill placed below
spread footings, slab -on -grade construction, beside foundation walls, behind retaining walls, and below
pavements.
We recommend Gyratory tests on bituminous mixes to evaluate strength and air voids, and density tests
to evaluate compaction.
We also recommend slump, air content and strength tests of Portland cement concrete.
D.B.c. Pavement Subgrade Proof -Roll
We recommend that proof - rolling of the pavement subgrades be observed by a geotechnical engineer to
determine if the results of the procedure meet project specifications, or delineate the extent of
additional pavement subgrade preparation work.
D.8.d. Cold Weather Precautions
If site grading and construction is anticipated during cold weather, all snow and ice should be removed
from cut and fill areas priorto additional grading. No fill should be placed on frozen subgrades. No frozen
soils should be used as fill.
Concrete delivered to the site should meet the temperature requirements of ASTM C 94. Concrete
should not be placed on frozen subgrades. Concrete should be protected from freezing until the
necessary strength is attained. Frost should not be permitted to penetrate below footings.
BRAUN
INTERTEC
Copperwood Real Estate
Project BL -12 -07372
February 13, 2013
Page 14
D.9. Additional Soil Borings
When a specific type of construction is finalized, we recommend that additional soil borings and a
geotechnical evaluation be completed. The borings and evaluation can then provide recommendations
that are specifically for the proposed construction.
E. Procedures
E.1. Penetration Test Borings
The penetration test borings were drilled on January 29, 2013 with an auger drill equipped with hollow -
stem auger. The borings were performed in accordance with ASTM D 1586. Penetration test samples
were taken at 2 1/2- or 5 -foot intervals. Actual sample intervals and corresponding depths are shown on
the boring logs.
E.2. Material Classification and Testing
E.2.a. Visual and Manual Classification
The geologic materials encountered were visually and manually classified in accordance with ASTM
Standard Practice D 2488. A chart explaining the classification system is attached. Samples were placed in
jars or bags and returned to our facility for review and storage.
E.2.b. Laboratory Testing
The results of the laboratory tests performed on geologic material samples are noted on or follow the
appropriate attached exploration logs. The tests were performed in accordance with ASTM or AASHTO
procedures.
E.3. Groundwater Measurements
The drillers checked for groundwater as the penetration test borings were advanced, and again after
auger withdrawal. The boreholes were then immediately backfilled.
BRAUN
INTERTEC
Copperwood Real Estate
Project BL -12 -07372
February 13, 2013
Page 15
F. Qualifications
F.1. Variations in Subsurface Conditions
FA.a. Material Strata
Our evaluation, analyses and recommendations were developed from a limited amount of site and
subsurface information. It is not standard engineering practice to retrieve material samples from
exploration locations continuously with depth, and therefore strata boundaries and thicknesses must be
inferred to some extent. Strata boundaries may also be gradual transitions, and can be expected to vary
in depth, elevation and thickness away from the exploration locations.
Variations in subsurface conditions present between exploration locations may not be revealed until
additional exploration work is completed, or construction commences. If any such variations are
revealed, our recommendations should be re- evaluated. Such variations could increase construction
costs, and a contingency should be provided to accommodate them.
F.1.11b. Groundwater Levels
Groundwater measurements were made under the conditions reported herein and shown on the
exploration logs, and interpreted in the text of this report. It should be noted that the observation
periods were relatively short, and groundwater can be expected to fluctuate in response to rainfall,
flooding, irrigation, seasonal freezing and thawing, surface drainage modifications and other seasonal
and annual factors.
F.2. Continuity of Professional Responsibility
F.2.a. Plan Review
This preliminary report is based on a limited amount of information, and a number of assumptions were
necessary to help us develop our recommendations. It is recommended that ourfirm review the
geotechnical aspects of the designs and specifications, and evaluate whether the design is as expected, if
any design changes have affected the validity of our recommendations, and if our recommendations
have been correctly interpreted and implemented in the designs and specifications.
BRAUN
INTERTEC
Copperwood Real Estate
Project BL -12 -07372
February 13, 2013
Page 16
F.2.11b. Construction Observations and Testing
It is recommended that we be retained to perform observations and tests during construction. This will
allow correlation of the subsurface conditions encountered during construction with those encountered
by the borings, and provide continuity of professional responsibility.
F.3. Use of Report
This report is for the exclusive use of the parties to which it has been addressed. Without written
approval, we assume no responsibility to other parties regarding this report. Our evaluation, analyses
and recommendations may not be appropriate for other parties or projects.
FA. Standard of Care
In performing its services, Braun Intertec used that degree of care and skill ordinarily exercised under
similar circumstances by reputable members of its profession currently practicing in the same locality. No
warranty, express or implied, is made.
BRAUN
INTERTEC
Appendix
U�; 13, L, C -1: CIC,
INTERTEC
�o
.�!�/
- i
r
r ,
BRAUN
INTERTEC
" h
a� -33
GI
R.
RIVO
BRAUN'
INTERTEC
LOG OF BORING
Braun Project BL -12 -07372
BORING: STA
GEOTECHNICAL EVALUATION
LOCATION: See attached sketch.
Chanhassen Lakes Business Park
Powers Boulevard and Lake Drive West
Chanhassen, Minnesota
DRILLER: J. Chermak
METHOD: 31/4" HSA, Autohammer
DATE: 1129/13
SCALE: 1" =4'
Elev.
Depth
feet
feet
Description of Materials
BPF
WL
MC
Tests or Notes
957.7
0.0
Symbol
(Soil -ASTM D2488 or D2487, Rock -USAGE EM1110 -1 -2908)
9579
nr
OL
—
ORGANIC CLAY, black, frozen.
Surface elevations
SC
—
(Topsoil)
obtained using gps,
CLAYEY SAND, trace of Gravel, brown, frozen, then
except for ST -3 which
—
dry to to moist, stiff to very stiff.
was estimated from the
topographic site plan.
14
13
20
_
24
16
27
945.7
12.0
CL
VEX
SANDY LEAN CLAY, trace of Gravel, brown, moist to
_
wet, rather stiff to very stiff.
13
(Glacial Till)
18
12
936.7
21.0
END OF BORING.
Water not observed with 19 1/2 feet of hollow -stem
—
auger in the ground.
—
Water not observed to cave -in depth of 16 1/2 feet
immediately after withdrawal of auger.
Boring immediately backfilled.
Braun lntertec Corporation ST -1 page: Toff
BRAUN'
INTERTEC
LOG OF BORING
Braun Project BL -12 -07372
BORING: ST -2
GEOTECHNICAL EVALUATION
LOCATION: See attached sketch.
Chanhassen Lakes Business Park
Powers Boulevard and Lake Drive West
Chanhassen, Minnesota
DRILLER: J. Chermak
METHOD: 31/4" HSA, Autohammer
DATE: 1129/13
SCALE: 1" =4'
Elev.
Depth
feet
feet
Description of Materials
BPF
WL
MC
Tests or Notes
953.4
0.0
Symbol
(Soil -ASTM D2488 or D2487, Rock -USACE EM1110 -1 -2908)
OL
—
ORGANIC CLAY, dark brown, frozen.
952.4
1.0
—
(Topsoil)
SC
-:-
CLAYEY SAND, trace of Gravel, brown, frozen to
-
moist, stiff.
(Glacial Till)
14
16
949.4
4.0
CL
SANDY LEAN CLAY, trace of Gravel, brown, moist to
wet, rather stiff to very stiff.
(Glacial Till)
11
-
11
18
19
No sample recovered.
_
11
11
934.4
19.0
CL
LEAN CLAY, brown, wet, rather stiff.
—
(Glacial Till)
10
930.4
23.0
CL
SANDY LEAN CLAY, trace of Gravel, gray, wet, rather
stiff.
(Glacial Till)
9
927.4
26.0
END OF BORING.
Water not observed with 24 1/2 feet of hollow -stem
-
auger in the ground.
-
Water not observed to cave -in depth of 18 1/2 feet
immediately after withdrawal of auger.
Boring immediately backfilled.
BL- 124J7372 Braun Intertec Corpomtion ST -2 page I of
0
z
a
BRAUN'
INTERTEC
LOG OF BORING
Braun Project BL -12 -07372
BORING: ST -3
GEOTECHNICAL EVALUATION
LOCATION: See attached sketch.
Chanhassen Lakes Business Park
Powers Boulevard and Lake Drive West
Chanhassen, Minnesota
DRILLER: J. Chermak
METHOD: 31/4" HSA, Autohammer
DATE: 1129113
SCALE: 1" =4'
Elev.
Depth
feet
feet
Description of Materials
BPF
WL
MC
Tests or Notes
938.0
0.0
Symbol
(Soil -ASTM D2488 or D2487, Rock -USAGE EM1110 -1 -2908)
%
OL
—
ORGANIC CLAY, dark brown, frozen.
(Topsoil)
936.0
2.0
Sc
-.
CLAYEY SAND, trace of Gravel, brown, moist, very
-:
stiff.
21
16
(Glacial Till)
934.0
4.0
CL
SANDY LEAN CLAY, trace of Gravel, brown, moist to
—
wet, rather stiff to very stiff.
(Glacial Till)
17
20
_
22
12
27
924.5
13.5
_
END OF BORING.
—
Water not observed with 12 feet of hollow -stem auger
in the ground.
Water not observed to cave -in depth of 9 1/2 feet
—
immediately after withdrawal of auger.
Boring immediately backfilled.
Braun Intertec Corporation ST -3 page 1 of 1
INTERTEC
LOG OF BORING
Braun Project BL -12 -07372
BORING: ST-4
GEOTECHNICAL EVALUATION
LOCATION: See attached sketch.
Chanhassen Lakes Business Park
Powers Boulevard and Lake Drive West
Chanhassen, Minnesota
DRILLER: J.Chermak
METHOD: 3 IA" HSA, Autohammer
DATE: 1129113
SCALE: 1 " =4'
Elev.
Depth
feet
feet
Description of Materials
BPF
WL
MC
Tests or Notes
949.0
0.0
Symbol
(Soil -ASTM D2488 or D2487, Rock -USACE EM1110 -1 -2908)
%
948.4
0.6
OL
—
ORGANIC CLAY, dark brown, frozen.
(Topsoil)
-
Sc
-.
CLAYEY SAND, trace of Gravel, brown, frozen to
-
moist, stiff to very stiff.
(Glacial Till)
13
16
20
16
_
25
940.0
9.0
CL
SANDY LEAN CLAY, trace of Gravel, brown, moist to
wet, stiff to very stiff.
(Glacial Till)
16
15
18
14
928.0
21.0
END OF BORING.
Water not observed with 17 feet of hollow -stem auger
-
in the ground.
-
Water not observed to cave -in depth of 17 feet
immediately after withdrawal of auger.
Boring immediately backfilled.
IL araun Intertm Corporation ST4 page 1 0 1
BRAUN
INTERTEC
Descriptive Terminology of Soil
Standard D 2487 - 00
Classification of Soils for Engineering Purposes
(Unified Soil Classification System)
Criteria for Assigning Group Symbols and
Soils Classification
Group
Cobbles ...............................
Group Names Using Laboratory Tests a
Gravel
Symbol
Group Name b
o
Gravels
Clean Gravels
Cu24and15C<< 3°
GW
Well - graded gravel
c'a
More than 50% of
coarse fraction
5 %or less fines`
Ca <4and /or1 >C, >3°
GP
Pootl °
y graded gravel
y 9 m
w =
retained on
Gravels with Fines
Fines classify as ML or MH
GM
Silty gravel °'s
Fines classify as CL or CH
GC
Clayey gravel °ts
c c
No. 4 sieve
More than 12% fines a
1P $ r
Sands
Clean Sands
Cu 2 6 and 1 : Cc S3 c
SW
Well- graded sand ^
Ca <6 and/or 1 >C° >3c
SP
Poorly graded sand
@r 6
50% or more of
5% or less fines
m --
coarse fraction
Sands with Fines
Fines classify as ML or MH
SM
Silty sand 's°
U o
passes
Fines classify as CL or CH
sC
Clayey sand 's^
E
No.4 sieve
More than 12%
m 5
Silts and Clays
Inorganic
PI > 7 and plots on or above "A° liner
CL
Lean cla 'I m
PI< 4 or plots below "A "fnal
ML
Silt "'m
-a
S m v
Liquid limit
Organic
Liquid limit -oven dried < 075
OL
Organic clay
to w
less than 50
C m o
Li uid limit - not dried
OL
Organic silt"
`o N
ca E
Silts and clays
Inorganic
PI plots on or above "A" line
CH
Fat clayu m
PI plots below "A" line
MH
Elastic silt" I m
d
I `o z
Liquid limit
Organic
Liquid limit -oven dried
OH
Organic Gay" m s
LL o
50 or more
< 0.76
Li uid limit - not dried
OH
Organicsilt"'m4
Highly Organic Soils
Primarily organic matter, dark in color and organic odor
PT
Peat
a Based on the material passing the 3in(75mm ) sieve
.
b. If field sample contained cobbles or boulders, or both, add "with cobbles or boulders or both" to group name.
D10x D.
d If soil condini 5% send, atltl with sand "togroup name.
e Gravels with 5 to 12% finesrequire dual symbols'
GVJ-GM well-graded gravel with silt
G W -GC well-graded gravel with clay
GP -GM Poorly graded gravel with silt
GP -GC poorly graded gravel with clay
f. If fines classify as CL -ML, use dual symbol GC-GM or SC-SM.
g. If Mes are organic, add'wkh orgamefines" togroup name.
h. If soil contains 215 %gravel, add 'wit gravel" to group name.
i. Sandswirl 12 %fines require dual symbols.
SW -SM well- graded send with sill
SVV-SC well- graded sand with clay
SP -SM poorly gradetl sand with silt
SP-SC poorly graded sand with clay
j. If Alterberg limits plot in hatched area, soil is a CL -ML, silty day.
k Ifsdl contains 10to29%plus No. 2W add with sand' or'wiN graverwhichever is predominant.
Ill wrlainskW %plus No. 2M, predominantly sand, add'sanc to group name.
m Ifsoil contain W% plus No. 200 predominantly gravel, add "gravelly"to group name.
n. PI 2 4 and plots on or above "A" line.
o. PI <4 or plots below W line.
p. PI plots on or above "A" ine.
q. PI plots below 'A" line.
60
5o
a 40
X
d
9
� 30
y 20
R
Q.
10
7
4
FA
over 12"
Cobbles ...............................
Gravel
Medium ..... ...............................
Coarse _ ....................
-.... 3/4" to 3"
Fine .. ...............................
No.4 to 3/4°
Sand
V11600
us WE
No. 4 to No. 10
0'
No. 10 to No. 40
Fine .. ...............................
No. 40 to No. 200
Silt ..... ..... ......... .._ .......
........ <No. 200, PI<4 or
below "A" line
Clay ......................
<No. 200, PI24 and
PNNE.■
on or above "A° line
0
10 16 20 30 40 50 60 70 80 90 100
Liquid Limit (LL)
Laboratory Tests
DD
Dry density, pcf
OC Organic content,%
Aj
Wet density, pcf
S
Percent of saturation,%
MC
Natural moisture content, %
SG Specific gravity
��,.■.■
Ligiuid limit, %
C
Cohesion, psf
PL
Plastic limit, %
0 Angle of internal friction
PI
Plasticity index, %
qu Unconfined compressive strength, psf
P200
% passing 200 sieve
qp Pocket penetrometer strength, isf
10
7
4
FA
over 12"
Cobbles ...............................
3" to 12..
Gravel
Medium ..... ...............................
Coarse _ ....................
-.... 3/4" to 3"
Fine .. ...............................
No.4 to 3/4°
Sand
V11600
us WE
No. 4 to No. 10
0'
No. 10 to No. 40
Fine .. ...............................
No. 40 to No. 200
Silt ..... ..... ......... .._ .......
........ <No. 200, PI<4 or
below "A" line
Clay ......................
<No. 200, PI24 and
on or above "A° line
0
10 16 20 30 40 50 60 70 80 90 100
Liquid Limit (LL)
Laboratory Tests
DD
Dry density, pcf
OC Organic content,%
WD
Wet density, pcf
S
Percent of saturation,%
MC
Natural moisture content, %
SG Specific gravity
LL
Ligiuid limit, %
C
Cohesion, psf
PL
Plastic limit, %
0 Angle of internal friction
PI
Plasticity index, %
qu Unconfined compressive strength, psf
P200
% passing 200 sieve
qp Pocket penetrometer strength, isf
110
Particle Size Identification
Boulders ...............................
over 12"
Cobbles ...............................
3" to 12..
Gravel
Medium ..... ...............................
Coarse _ ....................
-.... 3/4" to 3"
Fine .. ...............................
No.4 to 3/4°
Sand
Very stiff .... ...............................
Coarse ............................
No. 4 to No. 10
Medium ...........................
No. 10 to No. 40
Fine .. ...............................
No. 40 to No. 200
Silt ..... ..... ......... .._ .......
........ <No. 200, PI<4 or
below "A" line
Clay ......................
<No. 200, PI24 and
on or above "A° line
Relative Density of
Cohesionless Soils
Very loose . ............................... 0 to 4 BPF
Loose ........ ............................... 5 to 10 BPF
Medium dense ......................... 11 to 30 BPF
Dense ....... ............................... 31 to 50 BPF
Very dense ............................... over 50 BPF
Consistency of Cohesive Soils
Very soft .... ...............................
0 to 1 BPF
Soft - ... - . ...............................
2 to 3 SPF
Rather soft ...............................
4 to 5 BPF
Medium ..... ...............................
6 to 8 BPF
Rather stiff ...............................
9 to 12 BPF
Stiff ........ ...............................
13 to 16 BPF
Very stiff .... ...............................
17 to 30 BPF
Hard ........ ...............................
over 30 BPF
Drilling Notes
Standard penetration test borings were advanced by 3 1/4" or 6 1/4"
ID hollow -stem augers unless noted otherwise, Jetting water was used
to clean out auger prior to sampling only where indicated on logs.
Standard penetration test borings are designated by the prefix "ST"
(Split Tube). All samples were taken with the standard 2" OD split -tube
sampler, except where noted.
Power auger borings were advanced by 4" or 6" diameter continuous-
flight, solid -stem augers. Soil classifications and strata depths were in-
ferred from disturbed samples sugared to the surface and are, therefore,
somewhat approximate. Power auger borings are designated by the
pre0x"B"
Hand auger borings were advanced manually with a 1 1/2" or 3 1/4"
diameter auger and were limited to the depth from which the auger could
be manually withdrawn. Hand auger borings are indicated by the prefix
H°
BPF: Numbers indicate blows per foot recorded in standard penetration
test, also known as "N" value. The sampler was set 6" into undisturbed
soil below the hollow -stem auger. Driving resistances were then counted
for second and third fi° increments and added to get BPF. Where they
differed significantly, they are reported in the following form: 2/12 forthe
second and third 6" increments, respectively.
WH: WH indicates the sampler penetrated soil underweight of hammer
and rods alone; driving not required.
WR: WR indicates the sampler penetrated soil under weight of rods
alone; hammer weight and driving not required.
TIN indicates thin- walled (undisturbed) tube sample.
Note: All tests were run in general accordance with applicable ASTM
standards.
Rev 7N7