21-0364 Erhart Property GEO Bundle Final
May 22, 2021 HGTS Project Number: 21-0364
Mr. Dan Blake
Black Cherry Development, LLC
14500 Martin Drive #3000
Eden Prairie, MN 55344
Re: Geotechnical Exploration Report, Proposed Erhart Property Residential
Development, Chanhassen, Minnesota
Dear Mr. Blake:
We have completed the geotechnical exploration report for the proposed Erhart Property
residential development located in Chanhassen, Minnesota. A brief summary of our results
and recommendations is presented below. Specific details regarding our procedures, results
and recommendations follow in the attached geotechnical exploration report.
Six (6) soil borings were completed for this project that encountered about ½ to 2 feet of topsoil
at the surface. The topsoil was underlain by clayey native glacial till soils that extended to the
termination depths of the soil borings. Groundwater was encountered in two of the soil
borings at depths ranging from about 3 ½ to 11 feet below the ground surface.
The vegetation and topsoil are not suitable for foundation, roadway or utility support and will
need to be removed and replaced with suitable compacted engineered fill. In our opinion, the
underlying native glacial till soils are generally suitable for the construction of the proposed
residential development. However, portions of the clayey glacial till soils had a soft
consistency and some soil corrections to remove the clayey soils will be required and should
be anticipated.
With the building pads prepared as recommended, it is our opinion that the foundations for
the proposed buildings can be designed for a net allowable soil bearing capacity up to 2,000
pounds per square foot.
Thank you for the opportunity to assist you on this project. If you have any questions or need
additional information, please contact Paul Gionfriddo at 612-271-8185.
Sincerely,
Haugo GeoTechnical Services
Nic Alfonso, G.I.T. Paul Gionfriddo, P.E.
Project Geologist Senior Engineer
GEOTECHNICAL EXPLORATION REPORT
PROJECT:
Proposed Erhart Property Residential Development
Chanhassen, Minnesota
PREPARED FOR:
Black Cherry Development, LLC
14500 Martin Drive #3000
Eden Prairie, Minnesota 55344
PREPARED BY:
Haugo GeoTechnical Services
2825 Cedar Avenue South
Minneapolis, Minnesota 55407
Haugo GeoTechnical Services Project: 21-0364
May 22, 2021
I hereby certify that this plan, specification, or report was prepared by me or under my
direct supervision and that I am a duly Registered Professional Engineer under the laws of
the State of Minnesota.
Paul Gionfriddo, P.E.
Senior Engineer
License Number: 23093
Table of Contents
1.0 INTRODUCTION 1
1.1 Project Description 1
1.2 Purpose 1
1.3 Site Description 1
1.4 Scope of Services 1
1.5 Documents Provided 2
1.6 Locations and Elevations 2
2.0 FIELD PROCEDURES 2
3.0 RESULTS 3
3.1 Soil Conditions 3
3.2 Groundwater 3
3.3 Laboratory Testing 4
3.4 OSHA Soil Classification 4
4.0 DISCUSSION AND RECOMMENDATIONS 4
4.1 Proposed Construction 4
4.2 Discussion 5
4.3 Site Grading Recommendations 5
4.4 Dewatering 7
4.5 Interior Slabs 7
4.6 Below Grade Walls 7
4.7 Exterior Slabs 9
4.8 Site Grading and Drainage 9
4.9 Utilities 10
4.10 Bituminous Pavements 10
4.11 Materials and Compaction 11
4.12 Stormwater Ponds/Infiltration Basins 11
5.0 CONSTRUCTION CONSIDERATIONS 12
5.1 Excavation 12
5.2 Observations 12
5.3 Backfill and Fills 12
5.4 Testing 12
5.5 Winter Construction 12
6.0 PROCEDURES 13
6.1 Soil Classification 13
6.2 Groundwater Observations 13
7.0 GENERAL 13
7.1 Subsurface Variations 13
7.2 Review of Design 13
7.3 Groundwater Fluctuations 13
7.4 Use of Report 14
7.5 Level of Care 14
APPENDIX
Boring Location Sketch, Figure 1
GPS Boring Locations, Figure 2
Soil Boring Logs, SB-1 thru SB-6
Descriptive Terminology
1
1.0 INTRODUCTION
1.1 Project Description
Black Cherry Development, LLC is preparing to construct Phase 1 of the Erhart Property
residential development located north of W 96th Street between Great Plains Boulevard and
Powers Boulevard in Chanhassen, Minnesota and retained Haugo GeoTechnical Services
(HGTS) to perform a geotechnical exploration to evaluate the suitability of site soil conditions
to support the proposed development.
We understand the project will include preparing house pads for 22 single-family homes along
with the associated streets, underground utilities and infiltration ponds.
1.2 Purpose
The purpose of this geotechnical exploration was to characterize subsurface soil and
groundwater conditions and provide recommendations for site grading and foundation
design and construction.
1.3 Site Description
The project site is located north of W 96th Street between Great Plains Boulevard and Powers
Boulevard in Chanhassen, Minnesota. At the time of this exploration, the overall property
existed as a single parcel approximately 114 ½ acres in size. The project site is located in the
eastern portion of the overall parcel and generally consisted of wooded land with a
wetland/pond located at the eastern portion of the project site.
The site topography was generally sloped downward to the east with the elevations at the soil
boring locations ranging from about 879 to 909 ½ feet above mean sea level (MSL).
1.4 Scope of Services
Our services were performed in accordance with the Haugo GeoTechnical Services proposal
21-0364 dated March 26, 2021. Our scope of services was performed under the terms of our
General Conditions and limited to the following tasks:
Completing six (6) standard penetration test soil borings and extending each to
nominal depths of 14 ½ feet.
Obtaining GPS coordinates and ground surface elevations at the soil boring locations.
Visually/manually classifying samples recovered from the soil borings.
Performing laboratory tests on selected samples.
Preparing soil boring logs describing the materials encountered and the results of
groundwater level measurements.
Preparing an engineering report describing current soil and groundwater conditions
and providing recommendations for foundation design and construction.
2
1.5 Documents Provided
To aid in our evaluation, we were provided a site plan that was prepared by Alliant
Engineering, Inc. and was dated March 17, 2021. The site plan provided a layout of Phase 1 of
the proposed development including the locations of the proposed house lots, streets and
infiltration ponds. The site plan also showed the proposed soil boring locations.
Additionally, we were provided a site plan that was undated and unauthored which showed
the proposed layout of the overall development.
Except for these provided plans, specific architectural, structural or civil plans were not
available at the time of this geotechnical evaluation.
1.6 Locations and Elevations
The soil boring locations were selected by Black Cherry Development, LLC and/or Alliant
Engineering, Inc. The approximate locations of the soil borings are shown on Figure 1, “Soil
Boring Location Sketch,” in the Appendix. The sketch was prepared by HGTS using an aerial
image from Google Earth as a base.
HGTS obtained the GPS coordinates and ground surface elevations at the soil boring locations
using GPS technology based on the MN County Coordinate System (Carver County). GPS
coordinates and ground surface elevations are shown on Figure 2 in the Appendix.
2.0 FIELD PROCEDURES
Six (6) standard penetration test borings were advanced on April 14, 2021 by HGTS with a
rotary drilling rig, using continuous flight augers to advance the boreholes. Representative
samples were obtained from the borings, using the split-barrel sampling procedures in general
accordance with ASTM Specification D-1586. In the split-barrel sampling procedure, a 2-inch
O.D. split-barrel spoon is driven into the ground with a 140-pound hammer falling 30 inches.
The number of blows required to drive the sampling spoon the last 12 inches of an 18-inch
penetration is recorded as the standard penetration resistance value, or "N" value. The results
of the standard penetration tests are indicated on the boring logs. The samples were sealed in
containers and provided to HGTS for testing and soil classification.
A field log of each boring was prepared by HGTS. The logs contain visual classifications of the
soil materials encountered during drilling, as well as the driller's interpretation of the
subsurface conditions between samples and water observation notes. The final boring logs
included with this report represents an interpretation of the field logs and include
modifications based on visual/manual method observation of the samples.
The soil boring logs, general terminology for soil description and identification, and
classification of soils for engineering purposes are also included in the appendix. The soil
boring log identify and describe the materials encountered, the relative density or consistency
based on the Standard Penetration resistance (N-value, “blows per foot”) and groundwater
observations.
3
The strata changes were inferred from the changes in the samples and auger cuttings. The
depths shown as changes between strata are only approximate. The changes are likely
transitions, variations can occur beyond the location of the boring.
3.0 RESULTS
3.1 Soil Conditions
At the surface, the soil borings encountered about ½ to 2 feet of topsoil consisting of sandy
lean clay and silty clay that was black or dark brown and contained traces of roots.
Below the topsoil, the soil borings encountered native glacial till soils that extended to the
termination depths of the borings. The glacial till soils consisted of lean clay, sandy lean clay,
silty clay, clayey sand, silty clayey sand, and silty sand that was brown and grey in color.
Penetration resistance values (N-Values), shown as blows per foot (bpf) on the boring logs,
within the clayey glacial till soils (lean clay, sandy lean clay, silty clay) ranged from 2 to 22
bpf. These values indicate the clayey soils had a soft to very stiff consistency.
N-Values within the sandy glacial till soils (clayey sand, silty clayey sand, silty sand) ranged
from 2 to 30 bpf indicating a very loose to medium dense relative density.
3.2 Groundwater
Groundwater was encountered in two (2) of the six (6) soil borings while drilling and sampling
at depths ranging from about 3 ½ to 11 feet below the ground surface, corresponding to
elevations of about 868 to 876 ½ feet above mean sea level. The observed water levels are
summarized in Table 1.
Table 1. Summary of Groundwater Levels
Boring
Number
Measured Surface
Elevation (feet)
Approximate Depth
to Groundwater
(feet)*
Approximate
Groundwater Elevation
(feet)*
SB-1 879.8 3 ½ 876 ½
SB-2 909.4 NE -
SB-3 903.4 NE -
SB-4 895.5 NE -
SB-5 878.9 11 868
SB-6 896.5 NE -
* = Depths and elevations were rounded to the nearest ½ foot. NE = Not Encountered
Water levels were measured on the dates as noted on the boring logs and the period of water
level observations was relatively short. Given the cohesive nature of the soil encountered, it is
possible that insufficient time was available for groundwater to seep into the borings and rise
to its hydrostatic level. Groundwater monitoring wells or piezometers would be required to
more accurately determine water levels. Seasonal and annual fluctuations in the groundwater
levels should be expected.
4
3.3 Laboratory Testing
Laboratory moisture content and percent passing the #200 sieve (P-200) content tests were
performed on selected samples recovered from the soil borings. Table 2 below summarizes
the results of the laboratory tests. Results of the laboratory tests are also shown on the boring
logs adjacent to the sample tested.
Table 2. Summary of Laboratory Tests
Boring Number Sample
Number
Depth
(feet)
Moisture Content
(%) *
P-200 Content
(%) *
SB-1 SS-4 7 ½ 21 43 ½
SB-2 SS-9 2 ½ 22 -
SB-3 SS-22 20 16 ½ 38
SB-4 SS-24 2 ½ 15 ½ -
SB-5 SS-32 5 22 -
SB-6 SS-39 5 26 -
*Moisture content and P-200 content values rounded to the nearest ½ percent.
3.4 OSHA Soil Classification
The soils encountered in the borings at the anticipated excavation depths consisted of lean
clay, sandy lean clay, clayey sand and silty clayey sand generally meeting the ASTM
Classifications of CL, SC and SC-SM. Soils corresponding to the ASTM Classification of CL
will generally be Type B soil under Department of Labor Occupational Safety and Health
Administration (OSHA) guidelines, while soils corresponding to the ASTM classifications of
SC and SC-SM will generally be Type C soils under OSHA guidelines.
An OSHA-approved qualified person should review the soil classification in the field.
Excavations must comply with the requirements of OSHA 29 CFR, Part 1926, Subpart P,
“Excavations and Trenches.” This document states excavation safety is the responsibility of
the contractor. The project specifications should reference these OSHA requirements.
4.0 DISCUSSION AND RECOMMENDATIONS
4.1 Proposed Construction
We understand the proposed development will include preparing lots and house pads for 22
single-family homes along with the associated streets, underground utilities and infiltration
ponds. We were not provided specific information regarding the proposed structures, but we
assume they will include one or two stories above grade with partial or full basements. We
anticipate below grade construction consisting of cast-in-place concrete or masonry block
foundation walls supported on concrete spread footings. We further anticipate the above
grade construction will consist of wood framing, a pitched roof and asphalt shingles.
Based on the assumed construction we estimate wall loadings will range from about 2 to 3
kips (2,000 to 3,000 pounds) per lineal foot and column loads, if any will be less than 75 kips
(75,000 pounds).
5
We anticipate that the buildings will generally be constructed at or near existing site grades
so that cuts or fills for permanent grade changes will be on the order of 5 feet or less.
If the proposed loads exceed these values or if the design or location of the proposed
development changes, we should be informed. Additional analyses and revised
recommendations may be necessary.
4.2 Discussion
The vegetation and topsoil are compressible and are not suitable for foundation, roadway or
utility support and will need to be removed from below these areas and oversize areas and
replaced, as needed, with suitable compacted engineered fill. If the new homes will have
basement levels, then removal of some or all of these materials could be incidental to
construction.
It is our opinion that the underlying native glacial till soils are generally suitable for
foundation, pavement and utility support. However, portions of the clayey soils had a soft
consistency and in their current condition are not suitable for foundation support. The soft
soils will either need to be removed and replaced with suitable compacted engineered fill or
excavated, dried and recompacted.
Groundwater was encountered in two (2) of the six (6) soil borings while drilling and sampling
at depths ranging from about 3 ½ to 11 feet below the ground surface, corresponding to
elevations of about 868 to 876 ½ feet above mean sea level. Groundwater appears to be
perched above or within more permeable soils within the clayey glacial till. We anticipate that
groundwater could be encountered during grading activities or foundation construction.
Groundwater in clayey soils can likely be controlled with sumps and pumps.
With the building pads prepared as recommended, it is our opinion the footings can be
designed for a net allowable bearing pressure up to 2,000 pounds per square foot (psf).
The following sections provide recommendations for site grading and foundation design and
construction.
4.3 Site Grading Recommendations
Excavation We recommend that all vegetation, topsoil, and any soft or otherwise unsuitable
soils, if encountered, be removed from below the proposed building and oversize areas. Table
3 below summarizes the anticipated excavation depths at the soil boring locations. Excavation
depths may vary and could be deeper.
6
Table 3. Anticipated Excavation Depths
Boring
Number
Measured
Surface
Elevation
(feet)
Anticipated
Excavation
Depth (feet)*
Anticipated
Excavation
Elevation (feet)*
Approximate
Groundwater
Elevation (feet)*
SB-1 879.8 1 (Pond) 879 876 ½
SB-2 909.4 ½ 909 NE
SB-3 903.4 ½ (Pond) 903 NE
SB-4 895.5 ½ 895 NE
SB-5 878.9 4 875 868
SB-6 896.5 ½ 896 NE
* = Excavation and groundwater elevations were rounded to nearest ½ foot. NE = Not Encountered
Oversizing In areas where the excavations extend below the proposed footing elevations, the
excavations require oversizing. We recommend the perimeter of the excavation be extended
a foot outside the proposed footprint for every foot below footing grade (1H:1V oversizing).
The purpose of the oversizing is to provide lateral support of the foundation.
Fill Material Fill required to attain site grades may consist of any debris-free, non-organic
mineral soils. The exception being within 2 feet of the groundwater table where granular soil
(sand) with less than 5 percent passing the number 200 sieve and at least 50 percent retained
on the number 40 sieve should be used.
The on-site native glacial till soils appear to be generally suitable for reuse as fill or backfill
provided they are free of organic matter or other deleterious materials. Laboratory moisture
contents of the clayey soils ranged from about 15 ½ to 26 percent indicating they were likely
above their estimated optimum soil moisture content based on the standard Proctor test.
Clayey soil that will be reused ad fill or backfill will likely require moisture conditioning
(drying) to meet the recommended compaction levels. Summer months are typically more
favorable for drying wet clays.
Topsoil or soils that are black in color are not suitable for reuse as structural fill or backfill.
Backfilling We recommend that backfill placed to attain site grades be compacted to a
minimum of 95 percent of its standard Proctor density (ASTM D 698). Granular fill classified
as SP or SP-SM should be placed within 65 percent to 105 percent of its optimum moisture
content as determined by the standard Proctor. Other fill soils should be placed within 3
percentage points above and 1 percentage point below its optimum moisture content as
determined by the standard Proctor. All fill should be placed in thin lifts and be compacted
with a large self-propelled vibratory compactor operating in vibratory mode.
In areas where fill depths will exceed 10 feet, if any, we recommend that compaction levels be
increased to a minimum of 98 percent of standard Proctor density. Even with the increased
compacted levels a construction delay may be required to allow for post settlement of the fill
mass.
Fill and backfill placed on slopes, if any, must be “benched” into the underlying suitable soils
to reduce the potential for slip planes to develop between the fill and underlying soil. We
7
recommend “benching” or excavating into the slope at 5 feet vertical intervals to key the fill
into the slope. We recommend each bench be a minimum of 10 feet wide.
Foundations We recommend the perimeter footings bear a minimum of 42 inches below the
exterior grade for frost protection. Interior footings may be placed immediately below the
slab provided construction does not occur during below freezing weather conditions.
Foundation elements in unheated areas (i.e. deck or porch footings) should bear at least 5 feet
below exterior grade for frost protection.
We anticipate the foundations and floor slabs will bear on compacted engineered fill or native
glacial till soils. With the building pads prepared as recommended, it is our opinion the
footings can be designed for a net allowable bearing pressure up to 2,000 pounds per square
foot (psf).
We anticipate total and differential settlement of the foundations will be less than 1 inch and
½ inch, respectively, across a 30-foot span.
4.4 Dewatering
Groundwater was encountered in two of the six soil borings at depths of about 3 ½ to 11 feet
below the ground surface. Groundwater appears to be perched above or within more
permeable soils within the clayey glacial till. We anticipate that groundwater could be
encountered during grading activities or foundation construction. Groundwater in clayey
soils can likely be controlled with sumps and pumps. In sandy soil more aggressive
dewatering techniques could be required.
4.5 Interior Slabs
The anticipated floor subgrade will consist of compacted engineered fill or clayey glacial till
soils. It is our opinion a modulus of subgrade reaction, k, of 100 pounds per square inch of
deflection (psi) may be used to design the floor.
If floor coverings or coatings less permeable than the concrete slab will be used, we
recommend that a vapor retarder or vapor barrier be placed immediately beneath the slab.
Some contractors prefer to bury the vapor barrier or vapor retarder beneath a layer of sand to
reduce curling and shrinkage, but this practice often traps water between the slab and vapor
retarder or barrier. Regardless of where the vapor retarder or vapor barrier is placed, we
recommend consulting the floor covering manufacturer regarding the appropriate type, use
and installation of the vapor retarder or vapor barrier to preserve the warranty.
We recommend following all state and local building codes with regards to a radon mitigation
plan beneath interior slabs.
4.6 Below Grade Walls
We recommend general waterproofing of the below grade walls. We recommend either
placing drainage composite against the backs of the exterior walls or backfilling adjacent to
the walls with sand 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 the #200 sieve. The sand backfill
8
should be placed within 2 feet horizontally of the wall. We recommend the balance of the
backfill for the walls consist of sand however the sand may contain up to 20 percent of the
particles by weight passing the #200 sieve.
We recommend installing drain tile behind the below grade walls, adjacent to the wall footing
and below the slab elevation. Preferably the drain tile should consist of perforated pipe
embedded in gravel. A geotextile filter fabric should encase the pipe and gravel. The drain
tile should be routed to a storm sewer, sump pump or other suitable disposal site.
Foundation walls or below grade (basement) walls will have lateral loads from the
surrounding soil transmitted to them. Active earth pressures can be used to design the below
grade walls if the walls are allowed to rotate slightly. If wall rotation cannot be tolerated, then
below grade wall design should be based on at-rest earth pressures. It is our opinion that the
estimated soil parameters presented in Table 4 can be used for below grade wall design. These
design parameters are based on the assumptions that the walls are drained, there are no
surcharge loads within a horizontal distance equal to the height of the wall and the backfill is
level.
Table 4. Estimated Soil Parameters
Soil Type
Estimated
Unit
Weight
(pcf)
Estimated
Friction
Angle
(degrees)
At-Rest
Pressure
(pcf)
Active
Soil
Pressure
(pcf)
Passive Soil
Pressure
(pcf)
Sand
(SP & SP-SM) 120 32 55 35 390
Other Soils
(CL, SC, SC-SM,
SM)
135 28 70 50 375
Resistance to lateral earth pressures will be provided by passive resistance against the wall
footings and by sliding resistance along the bottom of the wall footings. We recommend a
sliding coefficient of 0.35. This value does not include a factor of safety.
4.7 Retaining Walls
Based on the plans provided it does not appear that any retaining walls will be constructed as
part of this project and we are not aware of any proposed retaining walls. Retaining wall
designers and/or installers should be aware that soil borings for any retaining walls were not
completed as part of this evaluation. Because of that, additional geotechnical exploration (soil
borings) will be required to determine and evaluate the suitability and/or stability of site soil
conditions to support their design(s). Retaining wall designers and/or installers will be solely
responsible to conduct additional geotechnical evaluation(s) as needed.
In addition, HGTS does not practice in retaining wall design. Retaining wall designers will be
solely responsible for retaining wall design and construction.
9
4.8 Exterior Slabs
Exterior slabs will likely be underlain clayey soils which are considered moderately to highly
frost susceptible. If these soils become saturated and freeze, frost heave may occur. This heave
can be a nuisance in front of doors and at other critical grade areas. One way to help reduce
the potential for heaving is to remove the frost-susceptible soils below the slabs down to
bottom of footing grades and replace them with non-frost-susceptible backfill consisting of
sand having less than 5 percent of the particles by weight passing the number 200 sieve.
If this approach is used and the excavation bottoms terminate in non-free draining granular
soil, we recommend a drain tile be installed along the bottom outer edges of the excavation to
collect and remove any water that may accumulate within the sand. The bottom of the
excavation should be graded away from the building.
If the banks of the excavations to remove the frost-susceptible soils are not sloped, abrupt
transitions between the frost-susceptible and non-frost-susceptible backfill will exist along
which unfavorable amounts of differential heaving may occur. Such transitions could exist
between exterior slabs and sidewalks, between exterior slabs and pavements and along the
slabs themselves if the excavations are confined to only the building entrances. To address
this issue, we recommend sloping the excavations to remove frost-susceptible soils at a
minimum 3:1 (horizontal:vertical) gradient.
An alternative method of reducing frost heave is to place a minimum of 2 inches of extruded
polystyrene foam insulation beneath the slabs and extending it about 4 feet beyond the slabs.
The insulation will reduce frost penetration into the underlying soil and reduce heave. Six to
twelve inches of granular soil is typically placed over the insulation to protect it during
construction.
Another alternative for reducing frost heave is to support the slabs on frost depth footings. A
void space of at least 4 inches should be provided between the slab and the underlying soil to
allow the soil to heave without affecting the slabs.
4.9 Site Grading and Drainage
We recommend the site be graded to provide positive run-off away from the proposed
buildings. We recommend landscaped areas be sloped a minimum of 6 inches within 10 feet
of the building and slabs be sloped a minimum of 2 inches. In addition, we recommend
downspouts with long splash blocks or extensions.
We recommend the lowest floor grades be constructed to meet City of Chanhassen
requirements with respect to groundwater separation distances. In the absence of city
requirements, we recommend maintaining at least a 4-foot separation between the lowest floor
slab and the observed groundwater levels and at least a 2-foot separation between the lowest
floor slab and the 100-year flood level of nearby wetlands, storm water ponds or other surface
water features.
10
4.10 Utilities
We anticipate that new utilities could be installed as part of this project. We further anticipate
that new utilities will bear at depths ranging from about 7 to 10 feet below the ground surface.
At these depths, we anticipate that the pipes will bear on compacted engineered fill or native
glacial till soils which in our opinion are generally suitable for pipe support. We recommend
removal all vegetation, topsoil, and any soft or otherwise unsuitable soils, if encountered,
beneath utilities prior to placement.
We recommend bedding material be thoroughly compacted around the pipes. We
recommend trench backfill above the pipes be compacted to a minimum of 95 percent beneath
slabs and pavements, the exception being within 3 feet of the proposed pavement subgrade,
where 100 percent of standard Proctor density is required. In landscaped areas, we
recommend a minimum compaction of 90 percent.
Groundwater was encountered in the soil borings depths of about 3 ½ to 11 feet below the
ground surface. See section 4.4 for dewatering considerations.
4.11 Bituminous Pavements
General The City of Chanhassen may have standard plates that dictate pavement design. If
so, we recommend that the pavements be designed and constructed in accordance with the
City of Chanhassen standard plates. The following paragraphs provide general pavement
recommendations in the absence of City of Chanhassen standard plates.
Traffic We were not provided any information regarding traffic volumes, such as Average
Annual Daily Traffic (AADT) or vehicle distribution. We anticipate the streets will be used
predominantly by automobiles, light trucks, school busses, garbage trucks and delivery vans
(FEDEX, UPS etc.). Based on the anticipated number of homes in the development and
assumed traffic types we estimate the roadways will be subjected to maximum Equivalent
Single Axle Loads (ESAL’s) ranging from about 50,000 to 75,000 over a 20-year design life.
This does not account for any future growth.
Subgrade Preparation We recommend removing all vegetation, topsoil and any soft or
otherwise unsuitable soil from beneath the pavement subgrade. Prior to placing the aggregate
base, we recommend compacting and/or test rolling the subgrade soils to identify soft, weak,
loose, or unstable areas that may require additional subcuts.
Backfill to attain pavement subgrade elevations can consist of any mineral soil provided it is
free of organic material or other deleterious materials. We recommend placing and
compacting fill and/or backfill as described in Section 4.3 except in paved areas where the
upper 3 feet of fill and backfill should be compacted to a minimum of 100 percent of its
standard Proctor maximum dry density.
R-Value R-Value testing was beyond the scope of this project. The near surface soils
encountered in the soil borings consisted predominantly of clayey soils consisting of lean clay,
sandy lean clay and clayey sand corresponding to the ASTM Classifications of CL and SC. It
is our opinion an assumed R-Value of 10 can be used for pavement design.
11
Pavement Section Based on an estimated R-value of 10 and a maximum of 75,000 ESAL’s we
recommend pavement section consisting of a minimum of 4 inches of bituminous (2 inches of
wear course and 2 inches of base course) underlain by a minimum of 9 inches of aggregate
base.
4.11 Materials and Compaction
We recommend aggregate base meeting MN/DOT specification 3138 for Class 5 aggregate
base. We recommend the aggregate base be compacted to 100 percent of its maximum
standard Proctor dry density.
We recommend that the bituminous wear and base courses meet the requirement of MN/DOT
specification 2360. We recommend the bituminous pavements be compacted to at least 92%
of the maximum theoretical density.
We assume the streets/roadways will include concrete curb and gutter. We recommend
specifying concrete that has a minimum 28-day compressive strength of 4,000 psi, and a
modulus of rupture of at least 600 psi. We recommend Type I cement meeting the
requirements of ASTM C150. We recommend specifying 5 to 7 percent entrained air for
exposed concrete to provide resistance to freeze-thaw deterioration. We also recommend
using a water/cement ratio of 0.45 or less for concrete exposed to deicers.
4.12 Stormwater Ponds/Infiltration Basins
Based on the plans provided it appears the project will likely include constructing several
stormwater ponds/infiltration basins throughout the project site. Borings SB-1 and SB-3 were
completed within the proposed ponds/basins. At the proposed pond bottom elevations, the
soil borings encountered sandy lean clay and clayey sand corresponding to the ASTM
Classifications of CL and SC. For stormwater pond/infiltration basin design it is our opinion
that the infiltration rates presented in Table 5 below can be used. These values were obtained
from tables included in the “Minnesota Storm Water Manual”.
Table 5. Design Infiltration Rates
In-situ soils Soil Description
Hydrologic Soil
Group
Design
Infiltration Rate
(in/hr)
CL Sandy Lean Clay D 0.06
SC Clayey Sand D 0.06
Field tests (double ring infiltrometer) can be performed within the proposed infiltration basin
area to verify infiltration rates of the in-situ soils. We would be pleased to provide these
services if required or requested.
12
5.0 CONSTRUCTION CONSIDERATIONS
5.1 Excavation
The soils encountered in the borings at the anticipated excavation depths consisted of lean
clay, sandy lean clay, clayey sand and silty clayey sand generally meeting the ASTM
Classifications of CL, SC and SC-SM. Soils corresponding to the ASTM Classification of CL
will generally be Type B soil under Department of Labor Occupational Safety and Health
Administration (OSHA) guidelines, while soils corresponding to the ASTM classifications of
SC and SC-SM will generally be Type C soils under OSHA guidelines.
Temporary excavations in Type B soils should be constructed at a minimum of 1 foot
horizontal to every 1 foot vertical within excavations. Temporary excavations in Type C soils
should be constructed at a minimum of 1 ½ foot horizontal to every 1 foot vertical within
excavations.
Slopes constructed in this manner may still exhibit surface sloughing. If site constraints do
not allow the construction of slopes with these dimensions, then temporary shoring may be
required.
5.2 Observations
A geotechnical engineer or a qualified engineering technician should observe the excavation
subgrade to evaluate if the subgrade soils are similar to those encountered in the borings and
adequate to support the proposed construction.
5.3 Backfill and Fills
We recommend moisture conditioning all soils that will be used as fill or backfill in accordance
with Section 4.3 above. We recommend that fill and backfill be placed in lifts not exceeding 4
to 12 inches, depending on the size of the compactor and materials used.
5.4 Testing
We recommend density tests of backfill and fills placed for the proposed foundations. Samples
of the proposed materials should be submitted to our laboratory prior to placement for
evaluation of their suitability and to determine their optimum moisture content and maximum
dry density (Standard Proctor).
5.5 Winter Construction
If site grading and construction is anticipated to proceed during cold weather, all snow and
ice should be removed from cut and fill areas prior to additional grading and placement of
fill. No fill should be placed on frozen soil and no frozen soil should be used as fill or backfill.
Concrete delivered to the site should meet the temperature requirements of ASTM and/or
ACI. Concrete should not be placed on frozen soil. Concrete should be protected from
freezing until the necessary strength is obtained. Frost should not be permitted to penetrate
below the footings.
13
6.0 PROCEDURES
6.1 Soil Classification
The drill crew chief visually and manually classified the soils encountered in the borings in
general accordance with ASTM D 2488, “Description and Identification of Soils (Visual-
Manual Procedure).” Soil terminology notes are included in the Appendix. The samples were
returned to our laboratory for review of the field classification by a soils engineer. Samples
will be retained for a period of 30 days.
6.2 Groundwater Observations
Immediately after taking the final samples in the bottom of the boring, the hole was checked
for the presence of groundwater. Immediately after removing the augers from the borehole
the hole was once again checked and the depth to water and cave-in depths were noted.
7.0 GENERAL
7.1 Subsurface Variations
The analyses and recommendations presented in this report are based on data obtained from
a limited number of soil borings. Variations can occur away from the boring, the nature of
which may not become apparent until additional exploration work is completed, or
construction is conducted. A reevaluation of the recommendations in this report should be
made after performing on-site observations during construction to note the characteristics of
any variations. The variations may result in additional foundation costs and it is suggested
that a contingency be provided for this purpose.
It is recommended that we be retained to perform the observation and testing program during
construction to 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, specifications and construction methods. This
will allow correlation of the soil conditions encountered during construction to the soil borings
and will provide continuity of professional responsibility.
7.2 Review of Design
This report is based on the design of the proposed structures as related to us for preparation
of this report. It is recommended that we be retained to review the geotechnical aspects of the
design and specifications. With the review, we will evaluate whether any changes have
affected the validity of the recommendations and whether our recommendations have been
correctly interpreted and implemented in the design and specifications.
7.3 Groundwater Fluctuations
We made water level measurements in the borings at the times and under the conditions stated
on the boring log. The data was interpreted in the text of this report. The period of observation
was relatively short and fluctuations in the groundwater level may occur due to rainfall,
14
flooding, irrigation, spring thaw, drainage, and other seasonal and annual factors not evident
at the time the observations were made. Design drawings and specifications and construction
planning should recognize the possibility of fluctuations.
7.4 Use of Report
This report is for the exclusive use of Black Cherry Development, LLC and their design team
to use to design the proposed structures and prepare construction documents. In the absence
of our written approval, we make no representation and assume no responsibility to other
parties regarding this report. The data, analysis and recommendations may not be
appropriate for other structures or purposes. We recommend that parties contemplating other
structures or purposes contact us.
7.5 Level of Care
Haugo GeoTechnical Services has used the degree of skill and care ordinarily exercised under
similar circumstance by members of the profession currently practicing in this locality. No
warranty expressed or implied is made.
APPENDIX
SB-3
Haugo GeoTechnical Services
2825 Cedar Avenue South
Minneapolis, MN 55407
Figure #: 1
Drawn By: NA
Date: 5/12/2021
Scale: None
Project #: 21-0364
Soil Boring Location Sketch
Erhart Property
Chanhassen, Minnesota
SB-2
SB-4
SB-5
SB-6
SB-1
Legend
Approximate Soil Boring Location
Disclaimer: Map and parcel data are believed to be accurate, but accuracy is not guaranteed. This is not a legal document and should not be substituted for a title search, appraisal, survey, or for zoning verification.
HGTS# 21-0364
Figure 2: GPS Boring Locations
Referencing Minnesota County Coordinates Basis – Carver County
Boring Number Elevation
(US Survey Feet)
Northing
Coordinate
Easting
Coordinate
SB-1 879.8 169871.939 558784.102
SB-2 909.4 170790.608 558840.498
SB-3 903.4 170710.096 558778.512
SB-4 895.5 170330.988 558759.472
SB-5 878.9 170108.476 558574.178
SB-6 896.5 169801.079 558426.041
Sandy Lean Clay, trace Roots, black, wet. (Topsoil)
(SC-SM) Silty Clayey Sand, fine to coarse grained, trace Gravel,
gray, waterbearing, very loose to loose. (Glacial Till)
(SC) Clayey Sand, trace Gravel, brown and gray, wet, very loose
to medium dense. (Glacial Till)
P-200 = 43.5%
Bottom of borehole at 14.5 feet.
AU
1
SS
2
SS
3
SS
4
SS
5
SS
6
SS
7
1-1-1
(2)
2-2-2
(4)
3-3-4
(7)
2-2-8
(10)
2-3-8
(11)
2-2-6
(8)
21
NOTES
GROUND ELEVATION 879.8 ft
LOGGED BY
DRILLING METHOD Hollow Stem Auger/Split Spoon
DRILLING CONTRACTOR HGTS - 750 GROUND WATER LEVELS:
CHECKED BY PG
DATE STARTED 4/14/21 COMPLETED 4/14/21
AT TIME OF DRILLING 3.30 ft / Elev 876.50 ft
AT END OF DRILLING ---
AFTER DRILLING ---
HOLE SIZE 3 1/4 inches
FINES CONTENT (%)
20 40 60 80
20 40 60 80
PL LLMC
DEPTH(ft)0
5
10 GRAPHICLOGMATERIAL DESCRIPTION
SAMPLE TYPENUMBERRECOVERY %(RQD)BLOWCOUNTS(N VALUE) SPT N VALUE
20 40 60 80
MOISTURE CONT.(%)NOTESPAGE 1 OF 1
BORING NUMBER SB-1
CLIENT Black Cherry Development LLC
PROJECT NUMBER 21-0364
PROJECT NAME Erhart Property
PROJECT LOCATION Chanhassen, MN
GEOTECH BH PLOTS - GINT STD US LAB.GDT - 5/22/21 21:14 - C:\USERS\HGTS 3\DROPBOX (HGTS)\HAUGO GEOTECHNICAL SERVICES\GINT PROJECT BACKUP\PROJECTS\21-0364 ERHART PROPERTY.GPJHaugo GeoTechnical Services
2825 Cedar Ave South
Minneapolis, MN 55407
Telephone: 612-729-2959
Fax: 763-445-2238
Sandy Lean Clay, trace Roots, dark brown, wet. (Topsoil)
(CL) Sandy Lean Clay, trace Gravel, brown, wet, rather stiff.
(Glacial Till)
(SC) Clayey Sand, fine to medium grained, trace Gravel, brown,
moist, medium dense. (Glacial Till)
Bottom of borehole at 14.5 feet.
AU
8
SS
9
SS
10
SS
11
SS
12
SS
13
SS
14
2-4-6
(10)
6-18-12
(30)
7-7-7
(14)
6-6-8
(14)
6-9-11
(20)
5-8-12
(20)
22
NOTES
GROUND ELEVATION 909.4 ft
LOGGED BY
DRILLING METHOD Hollow Stem Auger/Split Spoon
DRILLING CONTRACTOR HGTS - 750 GROUND WATER LEVELS:
CHECKED BY PG
DATE STARTED 4/14/21 COMPLETED 4/14/21
AT TIME OF DRILLING --- Not Encountered
AT END OF DRILLING --- Not Encountered
AFTER DRILLING --- Not Encountered
HOLE SIZE 3 1/4 inches
FINES CONTENT (%)
20 40 60 80
20 40 60 80
PL LLMC
DEPTH(ft)0
5
10 GRAPHICLOGMATERIAL DESCRIPTION
SAMPLE TYPENUMBERRECOVERY %(RQD)BLOWCOUNTS(N VALUE) SPT N VALUE
20 40 60 80
MOISTURE CONT.(%)NOTESPAGE 1 OF 1
BORING NUMBER SB-2
CLIENT Black Cherry Development LLC
PROJECT NUMBER 21-0364
PROJECT NAME Erhart Property
PROJECT LOCATION Chanhassen, MN
GEOTECH BH PLOTS - GINT STD US LAB.GDT - 5/22/21 21:14 - C:\USERS\HGTS 3\DROPBOX (HGTS)\HAUGO GEOTECHNICAL SERVICES\GINT PROJECT BACKUP\PROJECTS\21-0364 ERHART PROPERTY.GPJHaugo GeoTechnical Services
2825 Cedar Ave South
Minneapolis, MN 55407
Telephone: 612-729-2959
Fax: 763-445-2238
Silty Clay, trace Roots, black, wet. (Topsoil)
(CL) Lean Clay, brown, wet, stiff to very stiff. (Glacial Till)
(SM) Silty Sand, brown, moist, medium dense. (Glacial Till)
(SC) Clayey Sand, fine to medium grained, trace Gravel, brown,
medium dense. (Glacial Till)
P-200 = 38%
Bottom of borehole at 21.0 feet.
AU
15
SS
16
SS
17
SS
18
SS
19
SS
20
SS
21
SS
22
6-8-10
(18)
2-6-8
(14)
8-12-11
(23)
8-10-12
(22)
4-8-11
(19)
1-8-11
(19)
7-10-11
(21)16.5
NOTES Borehole Grouted Uopn Completion
GROUND ELEVATION 903.4 ft
LOGGED BY
DRILLING METHOD Hollow Stem Auger/Split Spoon
DRILLING CONTRACTOR HGTS - 750 GROUND WATER LEVELS:
CHECKED BY PG
DATE STARTED 4/14/21 COMPLETED 4/14/21
AT TIME OF DRILLING --- Not Encountered
AT END OF DRILLING --- Not Encountered
AFTER DRILLING --- Not Encountered
HOLE SIZE 3 1/4 inches
FINES CONTENT (%)
20 40 60 80
20 40 60 80
PL LLMC
DEPTH(ft)0
5
10
15
20 GRAPHICLOGMATERIAL DESCRIPTION
SAMPLE TYPENUMBERRECOVERY %(RQD)BLOWCOUNTS(N VALUE) SPT N VALUE
20 40 60 80
MOISTURE CONT.(%)NOTESPAGE 1 OF 1
BORING NUMBER SB-3
CLIENT Black Cherry Development LLC
PROJECT NUMBER 21-0364
PROJECT NAME Erhart Property
PROJECT LOCATION Chanhassen, MN
GEOTECH BH PLOTS - GINT STD US LAB.GDT - 5/22/21 21:14 - C:\USERS\HGTS 3\DROPBOX (HGTS)\HAUGO GEOTECHNICAL SERVICES\GINT PROJECT BACKUP\PROJECTS\21-0364 ERHART PROPERTY.GPJHaugo GeoTechnical Services
2825 Cedar Ave South
Minneapolis, MN 55407
Telephone: 612-729-2959
Fax: 763-445-2238
Sandy Lean Clay, trace Roots, black, wet. (Topsoil)
(SC) Clayey Sand, fine to medium grained, trace Gravel, loose to
medium dense. (Glacial Till)
(CL) Sandy Lean Clay, trace Gravel, brown and gray, wet, stiff.
(Glacial Till)
Bottom of borehole at 14.5 feet.
AU
23
SS
24
SS
25
SS
26
SS
27
SS
28
SS
29
3-3-5
(8)
2-8-8
(16)
6-7-9
(16)
4-5-8
(13)
4-7-8
(15)
6-6-8
(14)
15.5
NOTES
GROUND ELEVATION 895.5 ft
LOGGED BY
DRILLING METHOD Hollow Stem Auger/Split Spoon
DRILLING CONTRACTOR HGTS - 750 GROUND WATER LEVELS:
CHECKED BY PG
DATE STARTED 4/14/21 COMPLETED 4/14/21
AT TIME OF DRILLING --- Not Encountered
AT END OF DRILLING --- Not Encountered
AFTER DRILLING --- Not Encountered
HOLE SIZE 3 1/4 inches
FINES CONTENT (%)
20 40 60 80
20 40 60 80
PL LLMC
DEPTH(ft)0
5
10 GRAPHICLOGMATERIAL DESCRIPTION
SAMPLE TYPENUMBERRECOVERY %(RQD)BLOWCOUNTS(N VALUE) SPT N VALUE
20 40 60 80
MOISTURE CONT.(%)NOTESPAGE 1 OF 1
BORING NUMBER SB-4
CLIENT Black Cherry Development LLC
PROJECT NUMBER 21-0364
PROJECT NAME Erhart Property
PROJECT LOCATION Chanhassen, MN
GEOTECH BH PLOTS - GINT STD US LAB.GDT - 5/22/21 21:14 - C:\USERS\HGTS 3\DROPBOX (HGTS)\HAUGO GEOTECHNICAL SERVICES\GINT PROJECT BACKUP\PROJECTS\21-0364 ERHART PROPERTY.GPJHaugo GeoTechnical Services
2825 Cedar Ave South
Minneapolis, MN 55407
Telephone: 612-729-2959
Fax: 763-445-2238
Silty Clay, black, wet. (Topsoil)
(CL) Sandy Lean Clay, trace Gravel, brown and gray, wet, soft to
medium. (Glacial Till)
(SC) Clayey Sand, fine to medium grained, trace Gravel, Sand
Seam at 10 feet, brown and gray, waterbearing, medium dense.
(Glacial Till)
(CL) Sandy Lean Clay, trace Gravel, gray, wet, rather stiff. (Glacial
Till)
Bottom of borehole at 14.5 feet.
AU
30
SS
31
SS
32
SS
33
SS
34
SS
35
SS
36
1-1-1
(2)
1-3-3
(6)
3-5-6
(11)
3-5-7
(12)
3-5-7
(12)
3-5-6
(11)
22
NOTES
GROUND ELEVATION 878.9 ft
LOGGED BY
DRILLING METHOD Hollow Stem Auger/Split Spoon
DRILLING CONTRACTOR HGTS - 750 GROUND WATER LEVELS:
CHECKED BY PG
DATE STARTED 4/14/21 COMPLETED 4/14/21
AT TIME OF DRILLING 10.80 ft / Elev 868.10 ft
AT END OF DRILLING ---
AFTER DRILLING ---
HOLE SIZE 3 1/4 inches
FINES CONTENT (%)
20 40 60 80
20 40 60 80
PL LLMC
DEPTH(ft)0
5
10 GRAPHICLOGMATERIAL DESCRIPTION
SAMPLE TYPENUMBERRECOVERY %(RQD)BLOWCOUNTS(N VALUE) SPT N VALUE
20 40 60 80
MOISTURE CONT.(%)NOTESPAGE 1 OF 1
BORING NUMBER SB-5
CLIENT Black Cherry Development LLC
PROJECT NUMBER 21-0364
PROJECT NAME Erhart Property
PROJECT LOCATION Chanhassen, MN
GEOTECH BH PLOTS - GINT STD US LAB.GDT - 5/22/21 21:14 - C:\USERS\HGTS 3\DROPBOX (HGTS)\HAUGO GEOTECHNICAL SERVICES\GINT PROJECT BACKUP\PROJECTS\21-0364 ERHART PROPERTY.GPJHaugo GeoTechnical Services
2825 Cedar Ave South
Minneapolis, MN 55407
Telephone: 612-729-2959
Fax: 763-445-2238
Sandy Lean Clay, trace Roots, dark brown, wet. (Topsoil)
(CL) Sandy Lean Clay, trace Gravel, brown, wet, rather soft to
rather stiff. (Glacial Till)
(SC) Clay Sand, fine to medium grained, trace gravel, brown,
moist, loose. (Glacial Till)
(CL) Sandy Lean Clay, brown, wet, rather stiff. (Glacil Till)
Bottom of borehole at 14.5 feet.
AU
37
SS
38
SS
39
SS
40
SS
41
SS
42
SS
43
2-2-4
(6)
2-2-3
(5)
3-4-5
(9)
2-4-5
(9)
3-5-6
(11)
3-6-6
(12)
26
NOTES
GROUND ELEVATION 896.5 ft
LOGGED BY
DRILLING METHOD Hollow Stem Auger/Split Spoon
DRILLING CONTRACTOR HGTS - 750 GROUND WATER LEVELS:
CHECKED BY PG
DATE STARTED 4/14/21 COMPLETED 4/14/21
AT TIME OF DRILLING --- Not Encountered
AT END OF DRILLING --- Not Encountered
AFTER DRILLING --- Not Encountered
HOLE SIZE 3 1/4 inches
FINES CONTENT (%)
20 40 60 80
20 40 60 80
PL LLMC
DEPTH(ft)0
5
10 GRAPHICLOGMATERIAL DESCRIPTION
SAMPLE TYPENUMBERRECOVERY %(RQD)BLOWCOUNTS(N VALUE) SPT N VALUE
20 40 60 80
MOISTURE CONT.(%)NOTESPAGE 1 OF 1
BORING NUMBER SB-6
CLIENT Black Cherry Development LLC
PROJECT NUMBER 21-0364
PROJECT NAME Erhart Property
PROJECT LOCATION Chanhassen, MN
GEOTECH BH PLOTS - GINT STD US LAB.GDT - 5/22/21 21:14 - C:\USERS\HGTS 3\DROPBOX (HGTS)\HAUGO GEOTECHNICAL SERVICES\GINT PROJECT BACKUP\PROJECTS\21-0364 ERHART PROPERTY.GPJHaugo GeoTechnical Services
2825 Cedar Ave South
Minneapolis, MN 55407
Telephone: 612-729-2959
Fax: 763-445-2238