Geo Report - Minnetonka Middle School West Improvements, B2508902Geotechnical Evaluation Report
Minnetonka Middle School West Site Improvements
6421 Hazeltine Boulevard
Excelsior, Minnesota
Prepared for
Minnetonka Public Schools (ISD#276)
Professional Certification:
I hereby certify that this plan, specification, or report was prepared by
me or under my direct supervision and that I am a duly Licensed
Professional Engineer under the laws of the State of Minnesota.
Chad Lukkarila, PE
Director, Senior Engineer
License Number: 54438
January 27, 2026
Braun Intertec Corporation
Project B2508902
January 27, 2026 Project B2508902
Mr. Paul Bourgeois
Minnetonka Public Schools (ISD#276)
5621 Country Road 101
Minnetonka, MN 55345
Re: Geotechnical Evaluation
Minnetonka Middle School West Site Improvements
6421 Hazeltine Boulevard
Excelsior, Minnesota
Dear Mr. Bourgeois:
We are pleased to present this geotechnical evaluation report for the proposed site improvements at
Minnetonka Middle School West.
Thank you for making Braun Intertec Corporation (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 contact Ben Cook at 952.378.7336 (BCook@BraunIntertec.com) or Chad Lukkarila
at 701.390.2000 (CLukkarila@BraunIntertec.com).
Sincerely,
Braun Intertec Corporation
Benjamin Cook, EIT
Staff Engineer
Chad R. Lukkarila, PE
Associate Director, Senior Engineer
c: David Maroney, ATSR
Braun Intertec Page i
Table of Contents
1.0 Introduction ........................................................................................................................... 1
1.1 Project Description ........................................................................................................... 1
1.2 Site Conditions and History .............................................................................................. 2
1.3 Purpose ........................................................................................................................... 4
1.4 Background Information and Reference Documents .......................................................... 4
1.5 Scope of Services ............................................................................................................. 5
2.0 Results .................................................................................................................................. 6
2.1 Geologic Overview ........................................................................................................... 6
2.2 Previous Geotechnical Evaluation ..................................................................................... 6
2.3 Boring Results .................................................................................................................. 6
2.4 Groundwater .................................................................................................................... 7
2.5 Laboratory Test Results .................................................................................................... 8
3.0 Recommendations ................................................................................................................. 8
3.1 Design and Construction Discussion ................................................................................. 8
3.1.1 Foundation-Type and Building Support ........................................................................ 8
3.1.2 Reuse of On-Site Soils ................................................................................................ 8
3.1.3 Groundwater .............................................................................................................. 8
3.1.4 Construction Disturbance .......................................................................................... 9
3.2 Site Grading and Subgrade Preparation ............................................................................. 9
3.2.1 Building Subgrade Excavations ................................................................................... 9
3.2.2 Excavation Oversizing ............................................................................................... 10
3.2.3 Excavated Slopes ..................................................................................................... 11
3.2.4 Excavation Dewatering ............................................................................................. 11
3.2.5 Engineered Fill Materials and Compaction ................................................................. 11
3.2.6 Special Inspections of Soils ...................................................................................... 12
3.3 Helical Piles ................................................................................................................... 13
3.4 Aggregate Piers or Stone Columns .................................................................................. 13
3.4.1 Net Allowable Bearing Pressure ................................................................................ 14
3.4.2 Settlement ............................................................................................................... 14
3.4.3 Potential Installation and Vibration Risks ................................................................... 14
3.5 Spread Footings ............................................................................................................. 15
3.6 Construction Adjacent to Existing Structures ................................................................... 15
3.6.1 Excavations ............................................................................................................. 15
3.6.2 Footing Depth .......................................................................................................... 16
3.6.3 Settlement ............................................................................................................... 16
3.7 Interior Slabs ................................................................................................................. 16
3.7.1 Subgrade Modulus ................................................................................................... 16
3.7.2 Moisture Vapor Protection ........................................................................................ 16
3.8 Site Retaining Walls ........................................................................................................ 16
3.8.1 Subgrade Preparation ............................................................................................... 16
Table of Contents (Continued)
Braun Intertec Page ii
3.8.2 Drainage .................................................................................................................. 17
3.8.3 Net Allowable Bearing Pressure ................................................................................ 17
3.8.4 Selection, Placement and Compaction of Fill ............................................................ 17
3.8.5 Design Parameters ................................................................................................... 18
3.8.6 Global Factor of Safety ............................................................................................. 18
3.9 Frost Protection ............................................................................................................. 19
3.9.1 General .................................................................................................................... 19
3.9.2 Frost Heave Mitigation .............................................................................................. 19
3.10 Pavements and Exterior Slabs ......................................................................................... 20
3.10.1 Pavement and Exterior Slab Subgrade Preparation ..................................................... 20
3.10.2 Pavement Subgrade Proofroll .................................................................................... 21
3.10.3 Design Sections ....................................................................................................... 21
3.10.4 Bituminous Pavement Materials ................................................................................ 22
3.10.5 Subgrade Drainage ................................................................................................... 22
3.10.6 Performance and Maintenance ................................................................................. 22
3.11 Utilities .......................................................................................................................... 22
3.11.1 Subgrade Stabilization .............................................................................................. 22
3.11.2 Corrosion Potential .................................................................................................. 23
3.12 Stormwater .................................................................................................................... 23
3.13 Equipment Support ........................................................................................................ 24
4.0 Procedures .......................................................................................................................... 24
4.1 Penetration Test Borings ................................................................................................. 24
4.2 Exploration Logs ............................................................................................................. 24
4.2.1 Log of Boring Sheets ................................................................................................. 24
4.2.2 Geologic Origins ....................................................................................................... 24
4.3 Material Classification and Testing .................................................................................. 25
4.3.1 Visual and Manual Classification .............................................................................. 25
4.3.2 Laboratory Testing .................................................................................................... 25
4.4 Groundwater Measurements .......................................................................................... 25
5.0 Qualifications ...................................................................................................................... 25
5.1 Variations in Subsurface Conditions ................................................................................ 25
5.1.1 Material Strata.......................................................................................................... 25
5.1.2 Groundwater Levels ................................................................................................. 25
5.2 Continuity of Professional Responsibility ......................................................................... 26
5.2.1 Plan Review ............................................................................................................. 26
5.2.2 Construction Observations and Testing ..................................................................... 26
5.3 Use of Report ................................................................................................................. 26
5.4 Standard of Care ............................................................................................................ 26
Appendix
Soil Boring Location Sketch
Log of Boring Sheets ST-1 through ST-12
Double Ring Infiltrometer Test Results
Table of Contents (Continued)
Braun Intertec Page iii
Descriptive Terminology of Soil
List of Tables
Table 1-1. Building Additions Description .................................................................................................... 1
Table 2-1. Subsurface Profile Summary* ..................................................................................................... 6
Table 2-2. Groundwater Summary .............................................................................................................. 7
Table 3-1. Building Excavation Depths ........................................................................................................ 9
Table 3-2. Engineered Fill Materials* ......................................................................................................... 11
Table 3-3. Compaction Recommendations Summary ................................................................................ 12
Table 3-4. Estimated Helical Anchor Lengths ............................................................................................ 13
Table 3-5. Recommended Spread Footing Design Parameters ................................................................... 15
Table 3-6. Recommended Retaining Wall Design Parameters - Drained Conditions ..................................... 18
Table 3-7. Recommended Bituminous Pavement Sections ........................................................................ 21
List of Figures
Figure 1-1. Preliminary Site Layout .............................................................................................................. 2
Figure 1-2. Aerial Photograph from 2025 ..................................................................................................... 3
Figure 1-3. Aerial Photograph of the Site in 1991 .......................................................................................... 4
Figure 3-1. Generalized Illustration of Oversizing ....................................................................................... 10
Figure 3-2. Frost Protection Geometry Illustration ..................................................................................... 20
Minnetonka Public Schools (ISD#276)
Minnetonka Middle School West Site Improvements
Project B2508902
January 27, 2026
Braun Intertec Page 1
1.0 Introduction
1.1 Project Description
This geotechnical evaluation report addresses the proposed design and construction of the various site
improvement proposed for the Minnetonka Middle School West site. The improvements include a one-story
building classroom addition on the west side that will also contain a storm shelter and one single-story high-
volume gymnasium/stage area located on the east side of the existing structure. Additional site
improvements include local utilities, a small retaining wall on the west side of the track field, parking, and
updated stormwater management systems. Table 1-1 summarizes the provided and assumed project details
used to prepare this report.
Table 1-1. Building Additions Description
Aspect Descriptions
Below grade levels 0
Above grade levels 1
Lowest level floor elevation Classroom – 1055 feet
Gymnasium – 1055 feet
Column loads Classroom – 125 kips
Gymnasium – 225 kips
Wall loads Classroom – 5 klf
Gymnasium – 12klf
Cuts or fills for buildings XXX (Provided/Assumed)
Tolerable building settlements 1 inch (Assumed)
Additional Site Improvements Site utilities, a small retaining wall, parking lots, and
stormwater management
The figure below shows an illustration of the proposed site layout.
Minnetonka Public Schools (ISD#276)
Minnetonka Middle School West Site Improvements
Project B2508902
January 27, 2026
Braun Intertec Page 2
Figure 1-1. Preliminary Site Layout
Figure provided by Minnetonka Public Schools, dated September 18, 2025.
1.2 Site Conditions and History
Currently, the site is occupied by the Minnetonka Middle School West facilities, accompanying parking lots,
and surrounding sport fields. An Infiltration Pond is located in the southwest corner of the property. Green
spaces border the current structure on the north and west sides, with Hazeltine Boulevard running along the
western border of the property. The east side of the building is bordered by parking lots, with the various
sports facilities located further east. Current grades range from 1035 to 1059 feet MSL. Generally, the site is
relatively level, with a gentle descending slope from East to West toward Hazeltine Boulevard. Figure 1-2
shows an aerial photograph of the site in 2025 with the areas of the planned additions outlined with a red
box.
Minnetonka Public Schools (ISD#276)
Minnetonka Middle School West Site Improvements
Project B2508902
January 27, 2026
Braun Intertec Page 3
Figure 1-2. Aerial Photograph from 2025
Figure provided by Google Earth.
Historically, the site was used as agricultural development prior to the school’s construction. The site does
not appear to have been repurposed until some point between 1960 and 1971. Figure 1-3shows a historical
aerial photograph of the site from 1991. In 2012, an addition was added to the northwest part of school just
north of the planned.
Minnetonka Public Schools (ISD#276)
Minnetonka Middle School West Site Improvements
Project B2508902
January 27, 2026
Braun Intertec Page 4
Figure 1-3. Aerial Photograph of the Site in 1991
Figure provided by Google Earth.
1.3 Purpose
The purpose of our geotechnical evaluation was to characterize subsurface geologic conditions at selected
exploration locations, evaluate their impact on the project, and provide geotechnical recommendations for
the design and construction of building additions and site improvements.
1.4 Background Information and Reference Documents
We reviewed the following information:
▪ Surficial Geology map of Carver County dated 2009.
▪ Site Layout provided by Minnetonka Public Schools.
▪ Communications with the School District and ATSR regarding project scope, building loads, and
specifications.
Minnetonka Public Schools (ISD#276)
Minnetonka Middle School West Site Improvements
Project B2508902
January 27, 2026
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In addition to the provided sources, we have used several publicly available sources of information, including
Historical Aerial Photographs provided by the University of Minnesota, and Google Earth Pro.
We have described our understanding of the proposed construction and site to the extent others reported it
to us. Depending on the extent of available information, we may have made assumptions based on our
experience with similar projects. If we have not correctly recorded or interpreted the project details, the
project team should notify us. New or changed information could require additional evaluation, analyses,
and/or recommendations.
1.5 Scope of Services
We performed our scope of services for the project in accordance with our Proposal QTB222789 to Paul
Bourgeois, dated October 1, 2025. The following list describes the geotechnical tasks completed in
accordance with our authorized scope of services.
▪ Reviewing the background information and reference documents previously cited.
▪ Staking and clearing the exploration location of underground utilities. Minnetonka Public Schools
selected, and we staked the new exploration locations. We acquired surface elevations and
locations with GPS technology using the State of Minnesota’s permanent GPS base station network.
The Soil Boring Location Sketch included in the Appendix shows the approximate locations of the
borings.
▪ Performing 12 standard penetration test (SPT) borings, denoted as ST-1 to ST-12, to nominal depths of
15 to 30 feet below grade across the site.
▪ Performing laboratory testing on select samples to aid in soil classification and engineering analysis.
▪ Performing two double ring infiltration tests below the topsoil layer, located in the current track and
field area.
▪ Perform engineering analysis including subgrade capacity and potential settlement.
▪ Preparing this report containing a boring location sketch, logs of soil borings, a summary of the soils
encountered, results of laboratory tests, and recommendations for structure and pavement
subgrade preparation and the design of foundations, floor slabs, exterior slabs, utilities, stormwater
improvements and pavements.
Our scope of services did not include environmental services or testing and our geotechnical personnel
performing this evaluation are not trained to provide environmental services or testing. We can provide
environmental services or testing at your request.
Minnetonka Public Schools (ISD#276)
Minnetonka Middle School West Site Improvements
Project B2508902
January 27, 2026
Braun Intertec Page 6
2.0 Results
2.1 Geologic Overview
Based on the surficial geology map of Carver County, dated 2009, the surficial soils at this site predominately
consist of alluvially deposited clay loam and organic soils.
We based the geologic origins used in this report on the soil types, in-situ and laboratory testing, and
available common knowledge of the geological history of the site. Because of the complex depositional
history, geologic origins can be difficult to ascertain. We did not perform a detailed investigation of the
geological history of the site.
2.2 Previous Geotechnical Evaluation
Braun Intertec performed a geotechnical evaluation (Project Number SP-11-07756) in 2012 for the building
addition on the northwest corner of the site, just north of the planned classroom addition. Three soil borings
were completed to depths of 20 feet below the existing ground surface. In general, the soil borings
encountered mixed fill soils underlain by alluvial clay soils. Groundwater was not encountered during drilling.
2.3 Boring Results
Table 2-1 provides a summary of the soil boring results, in the general order we encountered the strata.
Please refer to the Log of Boring sheets in the Appendix for additional details. The Descriptive Terminology
sheet in the Appendix includes definitions of abbreviations used in the table below.
Table 2-1. Subsurface Profile Summary*
Strata Soil Type -ASTM
Classification
Range of
Penetration
Resistances
Commentary and Details
Pavement
Section - -
▪ Only present at borings ST-5 through ST-8.
▪ Overall thickness ranges from 12 to 16 inches.
▪ Bituminous thickness 3 to 7 inches.
▪ Apparent aggregate base is 7 to 11 inches.
Topsoil/Topsoil
fill SM -
▪ Observed in borings ST-1, ST-2, ST-3, ST-4, ST-9,
ST-10, ST-11, and ST-12.
▪ Predominantly SM.
▪ Dark brown to black.
▪ Variable thickness, not present at all borings.
▪ Thicknesses at boring locations varied from 3 to
11 inches.
▪ Moisture condition generally moist.
Minnetonka Public Schools (ISD#276)
Minnetonka Middle School West Site Improvements
Project B2508902
January 27, 2026
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Strata Soil Type -ASTM
Classification
Range of
Penetration
Resistances
Commentary and Details
Fill SC, CL 4 to 20 Blows per
Foot (BPF)
▪ General penetration resistance of 4 to 8 BPF.
▪ Moisture condition generally moist.
▪ Thicknesses at boring locations varied from 3 to
10 feet.
▪ Highly variable, soils intermixed.
▪ Occasional layers of slightly organic to organic soils
throughout, but often organic or mixed with organic
soils near boundary with swamp deposited soils.
▪ Possible cobbles and boulders.
Alluvial CL, CH 3 to 16 BPF
▪ General penetration resistance of 4 to 10 BPF; soft
to stiff consistency.
▪ Moisture condition generally moist
▪ Some silt lenses present.
▪ Variable amounts of gravel and sand.
*Abbreviations are defined in the attached Descriptive Terminology sheet.
We did not perform gradation analysis on the apparent aggregate base material encountered as part of the
pavement section, in accordance with our scope of work. Therefore, we cannot conclusively determine if the
encountered material satisfies a particular specification, and it should not be assumed it is suitable for
reuse.
For simplicity in this report, we define existing fill to mean existing, uncontrolled or undocumented fill.
2.4 Groundwater
Table 2-2 summarizes the depths where we observed groundwater; the attached Log of Boring sheets in the
Appendix also include this information and additional details.
Table 2-2. Groundwater Summary
Locations Surface Elevation
(ft)
Measured or Estimated
Depth to Groundwater
(ft)
Corresponding
Groundwater Elevation
(ft)
ST-5 1052.8 28 1025
ST-6 1054.4 29 1025 1/2
ST-7 1052.3 24 1/2 1028
At the time of our observation, the groundwater surface elevation appeared to be between 1025 and 1028 feet.
Project planning should expect groundwater to fluctuate in relation to time of year and recent weather events.
Minnetonka Public Schools (ISD#276)
Minnetonka Middle School West Site Improvements
Project B2508902
January 27, 2026
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2.5 Laboratory Test Results
The boring logs show the results of the laboratory testing we performed, next to the tested sample depth. We
The Appendix contains the results of these tests.
The moisture content of the soils varied from approximately 26 to 38 percent, indicating that the material was
near or above its probable optimum moisture content.
Our mechanical analyses indicated that the soils contained 65 to 98 percent silt and clay by weight.
Liquid limits determined for the clays ranged from 48 to 79; plastic limits ranged from 23 to 29. These results
indicate that the clays ranged from lean to fat clay.
3.0 Recommendations
3.1 Design and Construction Discussion
3.1.1 Foundation-Type and Building Support
The soil profile within the proposed addition layout consists of several feet of poorly compacted clayey fill,
underlaid by alluvial lean and fat clay deposits. Based on the results of our subsurface exploration and
evaluation, it is our opinion that a spread footing foundation system bearing on engineered fill soils can
support the proposed classroom building addition with sufficient subgrade preparation. Typical subgrade
preparation includes the removal of topsoil, organic soils, existing fill, and any structures or utilizes from
within the building footprint and oversize area.
Based on our evaluation of the proposed gymnasium additions and the associated loads, it is our opinion
that up to 18 feet of fill and alluvial soils would have be excavated and replaced with engineered fill to provide
a subgrade to support the proposed building and limit settlement. The excavation of up to 18 feet of fill
adjacent to the existing building may not be feasible. Section 3.3 and Section 3.4 provided recommendations
and design and construction considerations for helical piles and aggregate piers that could be used an
alternate foundation type if a deep excavation for the gymnasium is not feasible.
3.1.2 Reuse of On-Site Soils
The existing, non-organic, debris-free, soils are suitable for reuse as engineered fill below the proposed
building pad. We do not recommend reusing existing fill that contains debris or organic material as structural
fill.
3.1.3 Groundwater
We observed limited groundwater in the borings. Where we observed groundwater, it was below the
anticipated excavation depths for construction. Some of the soils, such as silty sands, clayey sands and clay,
Minnetonka Public Schools (ISD#276)
Minnetonka Middle School West Site Improvements
Project B2508902
January 27, 2026
Braun Intertec Page 9
will collect water from precipitation or if water drains to the site. We recommend the contractor remove any
water that collects in work areas before performing further work.
Excavations for this project may encounter occasional zones of groundwater. We recommend project
planning anticipate temporary excavation dewatering during construction. Based upon the boring and
piezometer observations, we anticipate sump pumps would be suitable for temporary dewatering.
3.1.4 Construction Disturbance
The contractor should note the on-site, silty and clayey soils are highly susceptible to disturbance due to
repeated construction traffic. Disturbance of these soils may cause areas that were previously prepared, or
that were suitable for pavement or structure support, to become unstable and require moisture conditioning
and compaction. Subcutting and replacing the disturbed material with crushed, coarse gravel, free of fines is
also an alternative. The contractor should use means and methods to limit disturbance of the soils.
3.2 Site Grading and Subgrade Preparation
3.2.1 Building Subgrade Excavations
We recommend removing unsuitable materials from below the proposed building additions. We define
unsuitable materials as existing fill, frozen materials, organic soils, existing structures, existing utilities,
vegetation, and soft/loose soils. Table 3-1 shows the anticipated excavation depths and bottom elevations for
each of the borings within the building additions.
Table 3-1. Building Excavation Depths
Locations
Approximate Surface
Elevation
(Feet)
Anticipated
Excavation Depth
(Feet)
Anticipated Bottom
Elevation
(Feet)
Anticipated Depth
Below FFE
(Feet)
Classroom Addition (FFE – 1055 feet)
ST-1 1050.5 4 1046 1/2 8 1/2
ST-2 1054.4 4 1050 1/2 4 1/2
ST-3 1054.5 6 1048 1/2 6 1/2
ST-4 1054.9 6 1049 6
Gymnasium/Stage Addition (FFE – 1055 feet)
ST-5 1052.8 15 1038 17
ST-6 1054.4 18 1036 1/2 18 1/2
ST-7 1052.3 18 1034 21
ST-8 1054.9 15 1040 15
Excavation depths will vary between the borings. Portions of the excavations may also extend deeper than
indicated by the borings/soundings/test pits. A geotechnical representative should observe the excavations
to make the necessary field judgments regarding the suitability of the exposed soils.
Minnetonka Public Schools (ISD#276)
Minnetonka Middle School West Site Improvements
Project B2508902
January 27, 2026
Braun Intertec Page 10
The contractor should use equipment and techniques to minimize soil disturbance. If soils become
disturbed or wet, we recommend excavation and surface compaction.
Prior to the placement of engineered fill or footings, we recommend surface compacting the exposed soils in
the bottoms of the excavations to a minimum of 95 percent of the Standard Proctor density. Areas that yield
or pump during surface compaction may require additional subcutting.
3.2.2 Excavation Oversizing
When removing unsuitable materials below structures or pavements, we recommend the excavation extend
outward and downward at a slope of 1H:1V (horizontal: vertical) or flatter. See Figure 3-1 for an illustration of
excavation oversizing.
Figure 3-1. Generalized Illustration of Oversizing
1. Engineered fill as defined in Section 3.2.5
2. Excavation oversizing minimum of 1 to 1 (horizontal to
vertical) slope or flatter
3. Engineered fill as required to meet pavement support or
landscaping requirements as defined in Section 3.2.5
4. Backslope to OSHA requirements
Minnetonka Public Schools (ISD#276)
Minnetonka Middle School West Site Improvements
Project B2508902
January 27, 2026
Braun Intertec Page 11
3.2.3 Excavated Slopes
Based on the borings, we anticipate on-site soils in excavations will consist of clays. These soils are typically
considered Type B Soil under OSHA (Occupational Safety and Health Administration) guidelines. OSHA
guidelines indicate unsupported excavations in Type B soils should have a gradient no steeper than 1H:1V.
Slopes constructed in this manner may still exhibit surface sloughing. OSHA requires an engineer to evaluate
slopes or excavations over 20 feet in depth.
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 that excavation safety is the responsibility of the contractor. The project specifications
should reference these OSHA requirements.
3.2.4 Excavation Dewatering
We recommend removing groundwater from the excavations. Project planning should include temporary
sumps and pumps for excavations in low-permeability soils, such as clays. Dewatering of high-permeability
soils (e.g., sands) from within the excavation with conventional pumps has the potential to loosen the soils,
due to upward flow.
3.2.5 Engineered Fill Materials and Compaction
Table 3-2 below contains our recommendations for engineered fill materials.
Table 3-2. Engineered Fill Materials*
Locations To Be
Used
Engineered Fill
Classification
Possible Soil
Type Descriptions Gradation Additional
Requirements
▪ Below foundations
▪ Below interior
slabs
Structural fill SP, SP-SM, SM, CL 100% passing 2-inch sieve
< 2% Organic
Content (OC)
Plasticity Index (PI) <
20%
▪ Drainage layer
▪ Non-frost-
susceptible
▪ Free draining
▪ Non-frost-
susceptible fill
GP, GW, SP, SW
100% passing 1-inch sieve
< 50% passing #40 sieve
< 5% passing #200 sieve
< 2% OC
Behind below-grade
walls, beyond
drainage layer
Retained fill* SP, SP-SM, SM, CL 100% passing 3-inch sieve
< 20% passing #200 sieve
< 2% OC
PI < 20%
Pavements Pavement fill SP, SM, SC, CL 100% passing 3-inch sieve < 2% OC
PI < 20%
Below landscaped
surfaces, where
subsidence is not a
concern
Non-structural fill --- 100% passing 6-inch sieve < 10% OC
* More select soils comprised of coarse sands with < 5% passing #200 sieve may be needed to accommodate work occurring in
periods of wet or freezing weather.
Minnetonka Public Schools (ISD#276)
Minnetonka Middle School West Site Improvements
Project B2508902
January 27, 2026
Braun Intertec Page 12
We recommend spreading engineered fill in loose lifts of approximately 12 inches thick. We recommend
compacting engineered fill in accordance with the criteria presented below in Table 3-3. The project
documents should specify relative compaction of engineered fill, based on the structure located above the
engineered fill, and vertical proximity to that structure.
Table 3-3. Compaction Recommendations Summary
Reference
Relative Compaction,
percent
(ASTM D698 – Standard
Proctor)
Moisture Content Variance from Optimum,
percentage points
< 12% Passing #200 Sieve
(typically SP, SP-SM)
> 12% Passing #200 Sieve
(typically CL, SC, SM)
Below foundations and
oversizing zones 98 ±3 -1 to +3
Below interior slabs 98 ±3 -1 to +3
Within 3 feet of pavement
subgrade 100 ±3 -1 to +3
More than 3 feet below
pavement subgrade 95 ±3 ±3
Below landscaped surfaces 90 ±5 ±4
Adjacent to below grade
wall 95* ±3 -1 to +3
*Increase compaction requirement to meet compaction required for structure supported by this engineered fill.
The project documents should not allow the contractor to use frozen material as engineered fill or to place
engineered fill on frozen material. Frost should not penetrate under foundations during construction.
We recommend performing density tests in engineered fill to evaluate if the contractors are effectively
compacting the soil and meeting project requirements.
3.2.6 Special Inspections of Soils
We recommend including the site grading and placement of engineered fill within the building pad under the
requirements of Special Inspections, as provided in Chapter 17 of the International Building Code, which is
part of the Minnesota State Building Code. Special Inspection requires observation of soil conditions below
engineered fill or footings, evaluations to determine if excavations extend to the anticipated soils, and if
engineered fill materials meet requirements for engineered fill and compaction condition of engineered fill. A
licensed geotechnical engineer should direct the Special Inspections of site grading and engineered fill
placement. The purpose of these Special Inspections is to evaluate whether the work is in accordance with
the approved geotechnical report for the project. Special Inspections should include evaluation of the
subgrade, observing preparation of the subgrade (surface compaction or dewatering, excavation oversizing,
placement procedures and materials used for engineered fill, etc.) and compaction testing of the engineered
fill.
Minnetonka Public Schools (ISD#276)
Minnetonka Middle School West Site Improvements
Project B2508902
January 27, 2026
Braun Intertec Page 13
3.3 Helical Piles
Given the anticipated excavation depths at the gymnasium building addition, a deep foundation support
system may be more economical to support the proposed footings. One option consists of helical piles
installed into the native clay soils. We performed an analysis using the provided design loads and observed
soil conditions using HelixPro Design Software by Foundation Supportworks. For our evaluation, we used a
typical lead section with helices of 10, 12, and 14 inches. We recommend helical piles with a hollow-tube
shaft rather than a square solid tube shaft, to increase buckling resistance through soft zones. The contractor
may also need to grout the helical piles to provide additional buckling resistance. Due to the disturbance and
relatively small shaft diameter, helical pile design usually ignores drag loads but not if the pile design
incorporates grout. Table 3-4 shows anticipated helical pile resistances.
Table 3-4. Estimated Helical Anchor Lengths
Boring Location Installation Depth
(feet)
Estimated Axial Service Capacity
(kips)
ST-1 15 24.5
ST-7 20 20
Due to the many proprietary systems with some competing design approaches, we recommend using a
performance-based specification for helical piles, along with design-build contracting. We recommend
requiring the contractor to have at least 5 years of experience in performing this work, and to demonstrate
performing the proposed protection system(s) on at least three previous projects of similar size and scope.
The specifications should require the design engineer be licensed in the project state. We can assist you with
developing a list of pre-qualified contractors prior to bidding or with reviewing contractor experience as part
of the bidding process.
We recommend requiring the helical piles to extend at least 5 feet below existing fill or swamp deposits. To
facilitate installation in gravel- or debris-laden soils, the contractor may need to “open up” or “sea shelled”.
The design submittal should identify if the contractor can alter the helices in this manner. We recommend
including a contingency in the project budget to account for installation difficulty and possibly additional
piles.
Helical piles are a Special Inspection item in accordance with Chapter 17 of the IBC. The observations
should include installed length, torque, confirmation of the materials, and confirmation of installation
techniques.
3.4 Aggregate Piers or Stone Columns
Another alternative to improve subgrade capacity is aggregate piers or stone columns, commonly known by
trade names such as: Geopier, Vibro Piers, Vibro Stone Columns, etc.
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A subgrade improved with aggregate piers or stone columns will reduce the potential for detrimental
settlement associated with the existing fill to occur, provide adequate bearing capacity, eliminate the need
for deep excavations, reduce impacts to adjacent site features, and reduce the volume of subgrade soils
disturbed at this site.
Different contractors use varying techniques to construct aggregate piers but generally consist of excavating
soil from a hole with an auger or vibrating a probe into the ground, and then building a column of clean, open-
graded aggregate. The contractor constructs the pier by placing the aggregate in lifts from the bottom of the
pier and compacting each lift before placing aggregate for the subsequent lift. The vibratory energy, and
sometimes ramming action, causes the aggregate to interlock, forming a stiff pier that provides soil
reinforcement and increases shear resistance. Due to the many variations in techniques, we recommend
using performance-based specifications with design-build contracting. We recommend requiring the
contractor to have at least 5 years of experience in performing this work, and to demonstrate performing the
proposed protection system(s) on at least three previous projects of similar size and scope. The
specifications should require the design engineer be licensed in the project state. We can assist you with
developing a list of pre-qualified contractors prior to bidding or with reviewing contractor experience as part
of the bidding process.
Aggregate piers are a Special Inspection item in accordance with Chapter 17 of the IBC. The observations
should include installed length, consistency of soil profile with the geotechnical evaluation confirmation of
the materials, and confirmation of installation techniques.
If implemented, we recommend installing aggregate piers under both foundations and floor slabs for the
building. The aggregate piers should extend through the existing fill to bear on the underlying alluvial and
glacial soils.
3.4.1 Net Allowable Bearing Pressure
The aggregate pier designer will determine the allowable soil bearing capacity of footings bearing upon
aggregate piers. However, aggregate piers are typically able to support net allowable bearing pressures of
3,000 to 5,000 pounds per square foot (PSF). This value includes a safety factor of at least 3.0 with regard to
bearing capacity failure.
3.4.2 Settlement
The aggregate pier designer will determine the settlement of footings bearing upon aggregate piers. However,
aggregate piers typically limit total and differential settlement of spread footing foundations to less than
1 inch and 1/2 inch, respectively.
3.4.3 Potential Installation and Vibration Risks
With the close proximity of the existing building and soil profile, it should be noted that vibrations are likely to
be felt within the existing building. The vibrations could also result in some building movement or building
damage. For this reason, precautions should be taken to limit building damage, and the owner should be
made aware of this potential for damage to occur. The project team may want to consider using a vibration
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monitor during construction to help identify when or if vibrations are at or above levels that can result in
building damage. Furthermore, the contractor should use means and methods that limit or reduce vibrations.
3.5 Spread Footings
Table 3-5 below contains our recommended parameters for foundation design following subgrade
preparation and soil corrections discussed above. If an alternative foundation system is used, the allowable
bearing capacity may increase.
Table 3-5. Recommended Spread Footing Design Parameters
Item Description
Maximum net allowable bearing pressure (psf) 3,000
Minimum factor of safety for bearing capacity failure 3.0
Minimum width (inches) 24
Minimum embedment below final exterior grade for heated
structures (inches) 42
Minimum embedment below final exterior grade for
unheated structures or for footings not protected from
freezing temperatures during construction (inches)
60
Total estimated settlement (inches) Less than 1 inch
Differential settlement Typically about 2/3 of total settlement*
* Actual differential settlement amounts will depend on final loads and foundation layout. When tying into the existing
buildings, the total settlement of this new building will be differential to the existing building. We can evaluate differential
settlement based on final foundation plans and loadings.
3.6 Construction Adjacent to Existing Structures
3.6.1 Excavations
Excavations for the new additions extend near or below existing footing grades. To reduce the risk of
undermining the existing foundations, we recommend excavations include temporary or permanent soil
retention systems to prevent sloughing, soil settlement, or bearing capacity failure. After reaching the design
depth, a geotechnical representative should observe the excavation bottom to evaluate the suitability of the
soils near the existing foundation for support of the new floor slab and foundation. We recommend
contacting us if excavations need to extend beyond the limits described above, as this may warrant
additional construction such as ground improvement, retention, or underpinning.
During construction, the contractor should monitor the slope and structure for movement. We also
recommend protecting the slope from disturbance, such as precipitation, runoff, or sloughing. The project
team should establish threshold limits of movement and required action if the movement exceeds the limits.
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3.6.2 Footing Depth
New building foundations constructed adjacent to the foundations of the existing building may exert
additional stresses on existing foundations. In general, we recommend constructing new foundations to bear
at the same elevation as the existing foundations. We also recommend lowering or offsetting foundations so
a foundation or its oversize zone does not exert a load on adjacent structures.
3.6.3 Settlement
Due to the existing building not likely settling with the proposed addition, approximately a 1/2 inch of
differential settlement could occur between the existing building and the addition. To accommodate this
settlement, we recommend connecting the addition to the building later in the construction process after
most of the deadload is in place on the addition. We also recommend installing expansion joints between the
existing building and the addition or designing the structure to accommodate differential movement.
3.7 Interior Slabs
3.7.1 Subgrade Modulus
The anticipated top of floor subgrade elevation is 1055 feet. We recommend using a modulus of subgrade
reaction, k, of 150 pounds per square inch per inch of deflection (pci) to design the slabs. If the slab design
requires placing 6 inches of compacted crushed aggregate base immediately below the slab, the slab design
may increase the k-value by 50 pci. We recommend that the aggregate base materials be free of bituminous.
In addition to improving the modulus of subgrade reaction, an aggregate base facilitates construction
activities and is less weather sensitive.
3.7.2 Moisture Vapor Protection
Excess transmission of water vapor could cause floor dampness, certain types of floor bonding agents to
separate, or mold to form under floor coverings. If project planning includes using floor coverings or coatings,
we recommend placing a vapor retarder or vapor barrier immediately beneath the slab. We also recommend
consulting with floor covering manufacturers regarding the appropriate type, use and installation of the vapor
retarder or barrier to preserve warranty assurances.
3.8 Site Retaining Walls
The following comments and recommendations may be used in retaining wall design and construction,
however, final design responsibility will rest with the wall design engineer. Retaining wall designers should be
informed of site features and utilities that would influence their design. Our scope of services did not include
global stability analysis. If desired, we can provide global stability analysis of the proposed walls.
3.8.1 Subgrade Preparation
To prepare the area for a modular block wall, the site should be cut to grade and any organic soil or loose, soft
or debris-laden fill observed below the wall and its reinforced zone be removed and replaced. However,
further direction regarding soil correction depths and suitable subgrade soils should be provided by the
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retaining wall designer. The soil borings indicate some of the walls may bear on layers of clay or silt that are
susceptible to disturbance. Contractors should use techniques which would limit the disturbance.
Provisions to subcut and replace soils with crushed aggregate base should be anticipated to provide a stable
working platform.
We also recommend for excavations that extend below the wall elevation be extended laterally beyond the
edges of the proposed footings a minimum of 1 foot for each vertical foot below the footing at that location
(i.e., 1:1 lateral oversizing). If MSE walls are used, we recommend the lateral oversizing extend outward and
downward from the back of the lateral reinforcement behind the wall.
The wall design should expect walls placed on existing fill to have a greater amount of post-construction
settlement, both differential and total settlements, than walls placed on new fill or native soils.
3.8.2 Drainage
Drainage behind the walls is critical. Unless a drainage composite is placed against the backs of the retaining
walls, we recommend that fill placed within 2 horizontal feet of the walls consist of clean granular fill. If
“clear” gravel only is used for drainage, a fabric separator may be needed to keep sand from washing into the
gravel. Water within this zone should be removed and routed away from the wall and its foundation zone.
Wall fill not capped with slabs or pavement should be capped with low-permeability soil to limit the
infiltration of surface drainage into the fill. Grades should also be sloped to divert water away from the walls
and the reinforced zone. We recommend the wall designer be consulted if water is introduced to the area of
the wall.
3.8.3 Net Allowable Bearing Pressure
We anticipate foundations for the proposed retaining wall will bear on engineered fill soil placed for this
project, or native clay soils. For wall design purposes, we recommend foundations bearing on these
materials be designed to exert a maximum soil bearing pressure of 2,000 psf. All foundation subgrades
should be reviewed by a geotechnical engineer. We anticipate total settlement of the wall will not exceed
1 inch; however, we recommend additional settlement analysis be performed as part of final wall design.
3.8.4 Selection, Placement and Compaction of Fill
We recommend wall fill below the wall and in the reinforced zone behind the wall be selected, placed and
compacted in accordance with Section 3.2.5. We recommend fill be placed on level surfaces. Therefore, any
fill placed on or against sloping ground should begin from the bottom of the slope where a level surface can
be established and properly ‘keyed’ into the slope. Keys should consist of a level bench excavated to a
convenient width for the equipment used. This will provide a more stable fill condition and reduce the
potential for slip surface to occur along the existing soil/new fill interface.
We recommend a walk-behind compactor be used to compact the fill placed within about 5 feet of the
retaining walls. Further away than that, a self-propelled compactor can be used.
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3.8.5 Design Parameters
Retaining wall design can use active earth pressure conditions if the walls can rotate slightly. If the wall
design cannot tolerate rotation, then design should use at-rest earth pressure conditions. Rotation up to
0.002 times the wall height is generally required for walls supporting sand. Rotation up to 0.02 times the wall
height is required when wall supports clay or silt.
Table 3-6 presents our recommended lateral coefficients and equivalent fluid pressures for wall design of
active, at-rest, and passive earth pressure conditions. We have provided parameters for on-site clays and
more fine-grained silty and clayey sands. However, we note the use of sands with less than 20 percent
passing the #200 sieve will improve drainage, reduce the risk of frost heave related movement, reduce the
risk of settlement of wall backfill, and overall will improve the long-term performance of the retaining wall.
The table also provides recommended wet unit weights and internal friction angles. Designs should also
consider the slope of any engineered fill and dead or live loads placed behind the walls within a horizontal
distance that is equal to the height of the walls. Our recommended values assume the wall design provides
drainage so water cannot accumulate behind the walls.
Table 3-6. Recommended Retaining Wall Design Parameters - Drained Conditions
Retained Soil Unit Weight
(pcf)
Friction Angle
(Degrees)
Active Lateral
Pressure
Coefficient (Ka)*
At-Rest Lateral
Pressure
Coefficient (Ko)*
Passive Lateral
Pressure
Coefficient (Kp)*
SP, SP-SM, SM
(<20% passing
#200 sieve)
120 32 0.31 0.47 3.25**
CL, SC, SM
(>20% passing
#200 sieve)
120 25 0.41 0.58 2.46
*Based on Rankine model for soils in a region behind the wall extending at least 2 horizontal feet beyond the bottom outer edges of the wall
footings and then rising up and away from the wall at an angle no steeper than 60 degrees from horizontal.
**Assumes sands are used as fill in front of the wall.
The construction documents should clearly identify what soils the contractor should use for engineered fill of
walls.
Sliding resistance between the bottom of the footing and the soil can also resist lateral pressures. We
recommend assuming a sliding coefficient equal to 0.40 between the concrete and soil.
The values presented in this section are un-factored.
3.8.6 Global Factor of Safety
In addition to other applicable stability and performance demonstrations, we recommend retaining wall
design documents or submittals contain demonstrations of global stability with a minimum factor of safety
against global failure of 1.5 or greater.
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3.9 Frost Protection
3.9.1 General
Clay soils will underlie exterior slabs, as well as pavements. We consider these soils 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
the surface structures supported on them could develop. This type of heaving could affect design drainage
patterns and the performance of exterior slabs and pavements, as well as any isolated exterior footings and
piers.
Note that general runoff and infiltration from precipitation are not the only sources of water that can saturate
subgrade soils and contribute to frost heave. Roof drainage and irrigation of landscaped areas in close
proximity to exterior slabs, pavements, and isolated footings and piers, contribute as well.
3.9.2 Frost Heave Mitigation
To address most of the heave related issues, we recommend setting general site grades and grades for
exterior surface features to direct surface drainage away from buildings, across large, paved areas and away
from walkways. Such grading will limit the potential for saturation of the subgrade and subsequent heaving.
General grades should also have enough “slope” to tolerate potential larger areas of heave, which may not
fully settle after thawing.
Even small amounts of frost-related differential movement at walkway joints or cracks can create tripping
hazards. Project planning can explore several subgrade improvement options to address this condition.
One of the more conservative subgrade improvement options to mitigate potential heave is removing any
frost-susceptible soils present below the exterior slab areas down to a minimum depth of 4 feet below
subgrade elevations. We recommend filling the resulting excavation with non-frost-susceptible fill. We
recommend providing drainage at the base of the subcut, as well as gradual transitions from this subcut
(3H:1V or flatter gradient). We also recommend sloping the bottom of the excavation toward one or more
collection points to remove any water entering the engineered fill. This approach will not be effective in
controlling frost heave without removing the water.
An important geometric aspect of the excavation and replacement approach described above is sloping the
banks of the excavations to create a more gradual transition between the unexcavated soils considered frost
susceptible and the engineered fill in the excavated area, which is not frost susceptible. The slope allows
attenuation of differential movement that may occur along the excavation boundary. We recommend slopes
that are 3H:1V, or flatter, along transitions between frost-susceptible and non-frost-susceptible soils.
Figure 3-2 shows an illustration summarizing some of the recommendations.
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Figure 3-2. Frost Protection Geometry Illustration
Another option is to limit frost heave in critical areas, such as doorways and entrances, via frost-depth
footings or localized excavations with sloped transitions between frost-susceptible and non-frost-
susceptible soils, as described above.
Over the life of slabs and pavements, cracks will develop, and joints will open up, which will expose the
subgrade and allow water to enter from the surface and either saturate or perch atop the subgrade soils. This
water intrusion increases the potential for frost heave or moisture-related distress near the crack or joint.
Therefore, we recommend implementing a detailed maintenance program to seal and/or fill any cracks and
joints. The maintenance program should give special attention to areas where dissimilar materials abut one
another, where construction joints occur and where shrinkage cracks develop.
3.10 Pavements and Exterior Slabs
3.10.1 Pavement and Exterior Slab Subgrade Preparation
We recommend the following steps for pavement and exterior slab subgrade preparation, understanding the
site will have minimal grade changes. Note that project planning may require additional subcuts to limit frost
heave.
1. Strip unsuitable soils consisting of topsoil, organic soils, peat, vegetation, existing structures, and
pavements from the area, within 5 feet of the surface of the proposed pavement grade.
2. Have a geotechnical representative observe the excavated subgrade to evaluate if additional
subgrade improvements are necessary.
3. Slope subgrade soils to areas of sand or drain tile to allow the removal of accumulating water.
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4. Surface compact to at least 95 percent of Standard Proctor density.
5. Place pavement engineered fill to grade and compact in accordance with Section 3.2.5 to bottom of
pavement and exterior slab section. See Section 3.9 for additional considerations related to frost
heave.
6. Proofroll the pavement or exterior slab subgrade as described in Section 3.10.2.
To improve long-term pavement performance, we recommend incorporating 18 inches of granular
engineered fill located in paved areas, in addition to the recommendations above, as a sand subbase.
Section 3.7 provides recommended pavement design sections with and without the sand subbase. Note, we
recommend sloping subgrade soils to promote drainage and removal of accumulated water.
3.10.2 Pavement Subgrade Proofroll
After preparing the subgrade as described above and prior to the placement of the aggregate base, we
recommend proofrolling the subgrade soils with a fully loaded tandem-axle truck. We also recommend
having a geotechnical representative observe the proofroll. Areas that fail the proofroll likely indicate soft or
weak areas that will require additional soil correction work to support pavements.
The contractor should correct areas that display excessive yielding or rutting during the proofroll, as
determined by the geotechnical representative. Possible options for subgrade correction include moisture
conditioning and recompaction, subcutting and replacement with soil or crushed aggregate, chemical
stabilization, and/or geotextiles. We recommend performing a second proofroll after the aggregate base
material is in place, and prior to placing bituminous or concrete pavement.
3.10.3 Design Sections
Our scope of services for this project did not include laboratory tests on subgrade soils to determine an
R-value for pavement design. Based on our experience with similar clay soils anticipated at the pavement
subgrade elevation, we recommend pavement design assume an R-value of 20. For concrete pavement
designs, we recommend a modulus of subgrade reaction (k) value of 150 pci. Note the contractor may need
to perform limited removal of unsuitable or less suitable soils to achieve this value.
Table 3-7 provides recommended pavement sections, based on the soils support and traffic loads. We have
assumed a 20-year flexible design values of 35,000 ESALs for medium duty pavement areas (parking) and
125,000 ESALs for heavy duty pavement areas (bus areas, drive lanes, and fire lanes).
Table 3-7. Recommended Bituminous Pavement Sections
Use Medium Duty Heavy Duty
Minimum asphalt thickness (inches) 3 1/2 4
Minimum aggregate base thickness
(inches) 8 10
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3.10.4 Bituminous Pavement Materials
Appropriate mix designs are critical to the performance of flexible pavements. We can provide
recommendations for pavement material selection during final pavement design.
3.10.5 Subgrade Drainage
We recommend installing perforated drainpipes throughout pavement areas at low points, around catch
basins, and behind curb in landscaped areas. We also recommend installing drainpipes along pavement and
exterior slab edges where exterior grades promote drainage toward those edge areas. The contractor should
place drainpipes in small trenches, extended at least 8 inches below the granular subbase layer, or below the
aggregate base material where no subbase is present.
3.10.6 Performance and Maintenance
We based the above pavement designs on a 20-year performance life for bituminous. This is the amount of
time before we anticipate the pavement will require reconstruction. This performance assumes routine
maintenance, such as seal coating and crack sealing. The actual pavement life will vary depending on
variations in weather, traffic conditions and maintenance.
It is common to place the non-wear course of bituminous and then delay placement of wear course. For this
situation, we recommend evaluating if the reduced pavement section will have sufficient structure to
support construction traffic.
Many conditions affect the overall performance of the exterior slabs and pavements. Some of these
conditions include the environment, loading conditions and the level of ongoing maintenance. With regard to
bituminous pavements in particular, it is common to have thermal cracking develop within the first few years
of placement and continue throughout the life of the pavement. We recommend developing a regular
maintenance plan for filling cracks in exterior slabs and pavements to lessen the potential impacts for cold
weather distress due to frost heave or warm weather distress due to wetting and softening of the subgrade.
3.11 Utilities
3.11.1 Subgrade Stabilization
Earthwork activities associated with utility installations located inside the building area should adhere to the
recommendations in Section 3.2.
For exterior utilities, we anticipate the soils at typical invert elevations will be suitable for utility support.
However, if construction encounters unfavorable conditions such as soft clay, organic soils or perched water
at invert grades, the unsuitable soils may require some additional subcutting and replacement with sand or
crushed rock to prepare a proper subgrade for pipe support. Project design and construction should not
place utilities within the 1H:1V oversizing of foundations.
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3.11.2 Corrosion Potential
Based on our experience, the clayey soils encountered in the borings are moderately corrosive to metallic
conduits, but only marginally corrosive to concrete. We recommend specifying non-corrosive materials or
providing corrosion protection, unless project planning chooses to perform additional tests to demonstrate
the soils are not corrosive.
3.12 Stormwater
Soil boring ST-12 was completed in the area of the existing stormwater pond in the southwestern portion of
the site. Boring ST-12 encountered sandy lean clay fill soil underlain by clay alluvial soils. In general, glacial
sandy lean clay and clayey sand was encountered in the soil borings. Sandy lean clays would be Hydrologic
Soil Type D soils that have recommended infiltration rates of 0.06 inches per hour, per the Minnesota
Stormwater Manual.
This infiltration rate represent the long-term infiltration capacity of a practice and not the capacity of the soils
in their natural state. Field testing, such as with a double-ring infiltrometer (ASTM D3385), may justify the use
of higher infiltration rates. However, we recommend adjusting field test rates by the appropriate correction
factor, as provided for in the Minnesota Stormwater Manual or as allowed by the local watershed. We
recommend consulting the Minnesota Stormwater Manual for stormwater design.
A stormwater infiltration chamber system is planned in the existing field east of the school building. The
depth of the chamber was not available at the time of this report. In general, silty sand and sandy lean clay
soils were encountered in the soil borings. We completed two double-ring infiltration tests (DRIs) in general
accordance with ASTM International (ASTM) D 3385; Standard Test Method for Infiltration Rate of Soils in
Field Using a Double-Ring Infiltrometer. The DRI testing was performed in the field by Braun Intertec
personnel on October 17, 2025, at the approximate locations identified on the attached sketch. Infiltration
rates estimated from the DRIs ranged from approximately 0.1 to 0.9 inches per hour. DRI results are included
in the attachments. Soils encountered at the DRI locations were generally silty sand and clayey sand.
Minnesota Stormwater Manual recommends using a design infiltration value of half the field estimated value
to account for reduction in infiltration over time. Design should also consider this proximity to groundwater.
We recommend consulting the Minnesota Stormwater Manual for stormwater design.
Fine-grained soils (silts and clays), topsoil or organic matter that mixes into or washes onto the soil will lower
the permeability. The contractor should maintain and protect infiltration areas during construction.
Furthermore, organic matter and silt washed into the system after construction can fill the soil pores and
reduce permeability over time. Proper maintenance is important for long-term performance of infiltration
systems.
This geotechnical evaluation does not constitute a review of site suitability for stormwater infiltration or
evaluate the potential impacts, if any, from infiltration of large amounts of stormwater.
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3.13 Equipment Support
The recommendations included in the report may not be applicable to equipment used for the construction
and maintenance of this project. We recommend evaluating subgrade conditions in areas of shoring,
scaffolding, cranes, pumps, lifts, and other construction equipment prior to mobilization to determine if the
exposed materials are suitable for equipment support or require some form of subgrade improvement. We
also recommend project planning consider the effect that loads applied by such equipment may have on
structures they bear on or surcharge – including pavements, buried utilities, below-grade walls, etc. We can
assist you in this evaluation.
4.0 Procedures
4.1 Penetration Test Borings
We drilled the penetration test borings with a hollow stem-mounted core and auger drill equipped with
hollow-stem auger. We performed the borings in general accordance with ASTM D6151 taking penetration
test samples at 2 1/2- or 5-foot intervals in general accordance with ASTM D1586. The boring logs show the
actual sample intervals and corresponding depths.
We sealed penetration test boreholes meeting the Minnesota Department of Health (MDH) Environmental
Borehole criteria with an MDH-approved grout. We will forward a sealing record for those boreholes to the
MDH Well Management Section.
4.2 Exploration Logs
4.2.1 Log of Boring Sheets
The Appendix includes Log of Boring sheets for our penetration test borings. The logs identify and describe
the penetrated geologic materials and present the results of penetration resistance and other in-situ tests
performed. The logs also present the results of laboratory tests performed on penetration test samples, and
groundwater measurements.
We inferred strata boundaries from changes in the penetration test samples and the auger cuttings. Because
we did not perform continuous sampling, the strata boundary depths are only approximate. The boundary
depths likely vary away from the boring locations, and the boundaries themselves may occur as gradual
rather than abrupt transitions.
4.2.2 Geologic Origins
We assigned geologic origins to the materials shown on the logs and referenced within this report, 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
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resistance and other in-situ testing performed for the project, (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.
4.3 Material Classification and Testing
4.3.1 Visual and Manual Classification
We visually and manually classified the geologic materials encountered based on ASTM D2488. When we
performed laboratory classification tests, we used the results to classify the geologic materials in
accordance with ASTM D2487. The Appendix includes a chart explaining the classification system we used.
4.3.2 Laboratory Testing
The exploration logs in the Appendix note the results of the laboratory tests performed on geologic material
samples. We performed the tests in general accordance with ASTM procedures.
4.4 Groundwater Measurements
The drillers checked for groundwater while advancing the penetration test borings, and again after auger
withdrawal. We then filled the boreholes as noted on the boring logs.
5.0 Qualifications
5.1 Variations in Subsurface Conditions
5.1.1 Material Strata
We developed our evaluation, analyses, and recommendations 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. Therefore, we must infer strata boundaries and thicknesses to some extent. Strata
boundaries may also be gradual transitions, and project planning should expect the strata 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
performing additional exploration work or starting construction. If future activity for this project reveals any
such variations, you should notify us so that we may reevaluate our recommendations. Such variations could
increase construction costs, and we recommend including a contingency to accommodate them.
5.1.2 Groundwater Levels
We made groundwater measurements under the conditions reported herein and shown on the exploration
logs and interpreted in the text of this report. Note that the observation periods were relatively short, and
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project planning can expect groundwater levels to fluctuate in response to rainfall, flooding, irrigation,
seasonal freezing and thawing, surface drainage modifications and other seasonal and annual factors.
5.2 Continuity of Professional Responsibility
5.2.1 Plan Review
We based this report on a limited amount of information, and we made a number of assumptions to help us
develop our recommendations. We should be retained to review the geotechnical aspects of the designs and
specifications. This review will allow us to evaluate whether we anticipated the design correctly, if any design
changes affect the validity of our recommendations, and if the design and specifications correctly interpret
and implement our recommendations.
5.2.2 Construction Observations and Testing
We recommend retaining us to perform the required observations and testing during construction as part of
the ongoing geotechnical evaluation. This will allow us to correlate the subsurface conditions exposed during
construction with those encountered by the borings and provide professional continuity from the design
phase to the construction phase. If we do not perform observations and testing during construction, it
becomes the responsibility of others to validate the assumption made during the preparation of this report
and to accept the construction-related geotechnical engineer-of-record responsibilities.
5.3 Use of Report
This report is for the exclusive use of the addressed parties. 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.
5.4 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.
Appendix
Soil Boring Location Sketch
Log of Boring Sheets ST-1 through ST-12
Double Ring Infiltrometer Test Results
Descriptive Terminology of Soil
HAZELTINE BOULEVARDST-5
ST-7
ST-9
ST-8
ST-6
ST-10 ST-11
DRI-2DRI-1
ST-12
ST-4
ST-2
ST-1
ST-3
NDENOTES APPROXIMATE LOCATION OF
STANDARD PENETRATION TEST BORING
0
SCALE:1"= 80'
80'40'F:\2025\B2508902\CAD\B2508902.dwg,Geotech,10/26/2025 1:53:41 PMbraunintertec.com
952.995.2000
Minneapolis, MN 55438
11001 Hampshire Avenue S
Project No:
B2508902
Drawn By:
Date Drawn:
Checked By:
Last Modified:10/26/25
Drawing No:
Project Information
Drawing Information
B2508902
JAG
10/2/25
KZ
Minnetonka Middle
School West Site
Improvements
6421 Hazeltine
Boulevard
Excelsior, Minnesota
Soil Boring
Location Sketch
DENOTES APPROXIMATE LOCATION OF
DOUBLE RING INFILTROMETER
Elev./
Depth
ft
1050.0
0.5
1046.5
4.0
1026.5
24.0
1020.5
30.0 WaterLevelDescription of Materials
(Soil-ASTM D2488 or 2487; Rock-USACE EM
1110-1-2908)
SANDY LEAN CLAY (CL), brown, moist
(TOPSOIL FILL)
FILL: SANDY LEAN CLAY (CL), brown, moist
FAT CLAY (CH), Silt lenses, brown, moist,
medium (ALLUVIUM)
LEAN CLAY (CL), trace Sand, gray, moist, soft
to medium (ALLUVIUM)
END OF BORING
Boring then backfilled with bentonite chips
5
10
15
20
25
30 SampleBlows
(N-Value)
Recovery
3-4-7
(11)
9"
4-3-5
(8)
15"
3-4-5
(9)
24"
2-4-5
(9)
23"
2-3-4
(7)
23"
2-3-4
(7)
24"
2-2-3
(5)
24"
1-2-2
(4)
24"
1-2-4
(6)
24"
qₚ
tsf
MC
%
29
35
35
Tests or Remarks
LL=71, PL=26, PI=45
Water not observed while
drilling.
LOG OF BORING
See Descriptive Terminology sheet for explanation of abbreviations
Project Number B2508902
Geotechnical Evaluation
Minnetonka Middle School West Improvements
6421 Hazeltine Boulevard
Excelsior, Minnesota
BORING:ST-1
LOCATION: Captured with RTK GPS.
DATUM:NAD 1983 HARN Adj MN Hennepin (US Feet)
NORTHING:134943.0 EASTING:448677.2
DRILLER:B Kammermeier/C
Doquette LOGGED BY:B Cook START DATE:10/10/25 END DATE:10/10/25
SURFACE
ELEVATION:1050.5 ft RIG:7506 METHOD:3 1/4" HSA SURFACING:Grass WEATHER:
B2508902 Braun Intertec Corporation Print Date:01/23/2026 ST-1 page 1 of 1
Elev./
Depth
ft
1053.9
0.5
1050.4
4.0
1036.4
18.0
1027.4
27.0
1024.4
30.0 WaterLevelDescription of Materials
(Soil-ASTM D2488 or 2487; Rock-USACE EM
1110-1-2908)
SILTY SAND (SM), brown, moist (TOPSOIL
FILL)
FILL: CLAYEY SAND (SC), brown, moist
FAT CLAY (CH), Silt lenses, brown, moist,
medium (ALLUVIUM)
SANDY LEAN CLAY (CL), trace Gravel, brown,
moist, medium to stiff (ALLUVIUM)
LEAN CLAY (CL), gray, moist, medium
(ALLUVIUM)
END OF BORING
Boring then backfilled with bentonite chips
5
10
15
20
25
30 SampleBlows
(N-Value)
Recovery
1-2-2
(4)
7"
3-3-5
(8)
23"
2-3-8
(11)
24"
2-3-5
(8)
21"
2-4-4
(8)
24"
2-2-3
(5)
24"
2-3-5
(8)
24"
2-8-8
(16)
20"
1-2-4
(6)
22"
qₚ
tsf
MC
%
31
31
Tests or Remarks
P200=98%
Water not observed while
drilling.
LOG OF BORING
See Descriptive Terminology sheet for explanation of abbreviations
Project Number B2508902
Geotechnical Evaluation
Minnetonka Middle School West Improvements
6421 Hazeltine Boulevard
Excelsior, Minnesota
BORING:ST-2
LOCATION: Captured with RTK GPS.
DATUM:NAD 1983 HARN Adj MN Hennepin (US Feet)
NORTHING:134935.7 EASTING:448754.6
DRILLER:B Kammermeier/C
Doquette LOGGED BY:B Cook START DATE:10/10/25 END DATE:10/10/25
SURFACE
ELEVATION:1054.4 ft RIG:7506 METHOD:3 1/4" HSA SURFACING:Grass WEATHER:
B2508902 Braun Intertec Corporation Print Date:01/23/2026 ST-2 page 1 of 1
Elev./
Depth
ft
1054.3
0.3
1048.5
6.0
1040.5
14.0
1036.5
18.0
1026.5
28.0
1024.5
30.0 WaterLevelDescription of Materials
(Soil-ASTM D2488 or 2487; Rock-USACE EM
1110-1-2908)
SILTY SAND (SM), brown, moist (TOPSOIL
FILL)
FILL: SANDY LEAN CLAY (CL), brown, moist
LEAN CLAY (CL), Silt lenses, brown, moist,
medium (ALLUVIUM)
SANDY LEAN CLAY (CL), brown, moist, stiff
(ALLUVIUM)
LEAN CLAY (CL), brown, moist, medium
(ALLUVIUM)
SANDY LEAN CLAY (CL), gray, moist, medium
(ALLUVIUM)
END OF BORING
Boring then backfilled with bentonite chips
5
10
15
20
25
30 SampleBlows
(N-Value)
Recovery
1-2-4
(6)
14"
2-3-4
(7)
24"
1-3-4
(7)
24"
2-3-5
(8)
23"
2-3-5
(8)
24"
1-4-6
(10)
23"
1-2-3
(5)
24"
1-2-3
(5)
24"
3-4-4
(8)
15"
qₚ
tsf
MC
%
34
Tests or Remarks
LL=49, PL=24, PI=25
Water not observed while
drilling.
LOG OF BORING
See Descriptive Terminology sheet for explanation of abbreviations
Project Number B2508902
Geotechnical Evaluation
Minnetonka Middle School West Improvements
6421 Hazeltine Boulevard
Excelsior, Minnesota
BORING:ST-3
LOCATION: Captured with RTK GPS.
DATUM:NAD 1983 HARN Adj MN Hennepin (US Feet)
NORTHING:134843.6 EASTING:448672.5
DRILLER:B Kammermeier/C
Doquette LOGGED BY:B Cook START DATE:10/10/25 END DATE:10/10/25
SURFACE
ELEVATION:1054.5 ft RIG:7506 METHOD:3 1/4" HSA SURFACING:Grass WEATHER:
B2508902 Braun Intertec Corporation Print Date:01/23/2026 ST-3 page 1 of 1
Elev./
Depth
ft
1054.7
0.3
1048.9
6.0
1045.9
9.0
1040.9
14.0
1036.9
18.0
1024.9
30.0 WaterLevelDescription of Materials
(Soil-ASTM D2488 or 2487; Rock-USACE EM
1110-1-2908)
SILTY SAND (SM), brown, moist (TOPSOIL
FILL)
FILL: LEAN CLAY (CL), brown, moist
LEAN CLAY (CL), Silt lenses, brown, moist, stiff
(ALLUVIUM)
LEAN CLAY (CL), brown, moist, medium
(ALLUVIUM)
SANDY LEAN CLAY (CL), brown, wet, medium
(ALLUVIUM)
LEAN CLAY (CL), brown, wet, medium to stiff
(ALLUVIUM)
END OF BORING
Boring then backfilled with bentonite chips
5
10
15
20
25
30 SampleBlows
(N-Value)
Recovery
1-2-4
(6)
12"
3-3-6
(9)
24"
2-4-8
(12)
23"
2-3-4
(7)
22"
2-3-8
(11)
20"
2-2-3
(5)
23"
1-2-3
(5)
23"
3-4-4
(8)
1-3-6
(9)
21"
qₚ
tsf
MC
%
29
34
Tests or Remarks
P200=96%
Water not observed while
drilling.
LOG OF BORING
See Descriptive Terminology sheet for explanation of abbreviations
Project Number B2508902
Geotechnical Evaluation
Minnetonka Middle School West Improvements
6421 Hazeltine Boulevard
Excelsior, Minnesota
BORING:ST-4
LOCATION: Captured with RTK GPS.
DATUM:NAD 1983 HARN Adj MN Hennepin (US Feet)
NORTHING:134890.1 EASTING:448744.9
DRILLER:B Kammermeier/C
Doquette LOGGED BY:B Cook START DATE:10/10/25 END DATE:10/10/25
SURFACE
ELEVATION:1054.9 ft RIG:7506 METHOD:3 1/4" HSA SURFACING:Grass WEATHER:
B2508902 Braun Intertec Corporation Print Date:01/23/2026 ST-4 page 1 of 1
Elev./
Depth
ft
1051.8
1.0
1048.8
4.0
1041.8
11.0
1034.8
18.0
1030.8
22.0
1022.8
30.0 WaterLevelDescription of Materials
(Soil-ASTM D2488 or 2487; Rock-USACE EM
1110-1-2908)
PAVEMENT, 3 inches of bituminous over 9
inches of apparent aggregate base
FILL: SANDY LEAN CLAY (CL), brown, moist
SANDY LEAN CLAY (CL), Silt lenses, brown,
moist, medium (ALLUVIUM)
FAT CLAY (CH), gray, moist, medium
(ALLUVIUM)
SANDY LEAN CLAY (CL), gray, moist, medium
(ALLUVIUM)
LEAN CLAY (CL), gray, wet, soft to medium
(ALLUVIUM)
END OF BORING
Boring then backfilled with bentonite chips
5
10
15
20
25
30 SampleBlows
(N-Value)
Recovery
1-2-3
(5)
16"
2-2-4
(6)
18"
2-2-5
(7)
18"
1-3-4
(7)
18"
2-2-4
(6)
18"
2-3-3
(6)
18"
1-3-4
(7)
18"
1-1-2
(3)
18"
1-2-3
(5)
18"
qₚ
tsf
MC
%
35
38
Tests or Remarks
LL=48, PL=24, PI=24
LL=70, PL=27, PI=43
Water observed at 28.0 feet
while drilling.
LOG OF BORING
See Descriptive Terminology sheet for explanation of abbreviations
Project Number B2508902
Geotechnical Evaluation
Minnetonka Middle School West Improvements
6421 Hazeltine Boulevard
Excelsior, Minnesota
BORING:ST-5
LOCATION: Captured with RTK GPS.
DATUM:NAD 1983 HARN Adj MN Hennepin (US Feet)
NORTHING:134715.9 EASTING:449134.0
DRILLER:B Kammermeier/C
Doquette LOGGED BY:B Cook START DATE:10/17/25 END DATE:10/17/25
SURFACE
ELEVATION:1052.8 ft RIG:7506 METHOD:3 1/4" HSA SURFACING:Bituminous WEATHER:
B2508902 Braun Intertec Corporation Print Date:01/23/2026 ST-5 page 1 of 1
Elev./
Depth
ft
1053.2
1.2
1050.4
4.0
1047.4
7.0
1036.4
18.0
1025.4
29.0
1024.4
30.0 WaterLevelDescription of Materials
(Soil-ASTM D2488 or 2487; Rock-USACE EM
1110-1-2908)
PAVEMENT, 7 inches of bituminous over 7
inches of apparent aggregate base
FILL: SANDY LEAN CLAY (CL), gray, moist
FILL: SANDY LEAN CLAY (CL), brown, moist
LEAN CLAY (CL), Silt lenses, brown, moist,
medium (ALLUVIUM)
LEAN CLAY (CL), gray, moist, soft to medium
(ALLUVIUM)
LEAN CLAY (CL), gray, wet, medium
(ALLUVIUM)
END OF BORING
Boring then backfilled with bentonite chips
5
10
15
20
25
30 SampleBlows
(N-Value)
Recovery
3-3-3
(6)
8"
4-3-4
(7)
14"
2-2-3
(5)
18"
2-2-3
(5)
18"
2-2-4
(6)
18"
2-2-5
(7)
18"
2-2-3
(5)
18"
1-1-3
(4)
18"
12-2-4
(6)
18"
qₚ
tsf
MC
%
23
35
Tests or Remarks
P200=97%
Water observed at 29.0 feet
while drilling.
LOG OF BORING
See Descriptive Terminology sheet for explanation of abbreviations
Project Number B2508902
Geotechnical Evaluation
Minnetonka Middle School West Improvements
6421 Hazeltine Boulevard
Excelsior, Minnesota
BORING:ST-6
LOCATION: Captured with RTK GPS.
DATUM:NAD 1983 HARN Adj MN Hennepin (US Feet)
NORTHING:134721.8 EASTING:449239.0
DRILLER:B Kammermeier/C
Doquette LOGGED BY:B Cook START DATE:10/17/25 END DATE:10/17/25
SURFACE
ELEVATION:1054.4 ft RIG:7506 METHOD:3 1/4" HSA SURFACING:Bituminous WEATHER:
B2508902 Braun Intertec Corporation Print Date:01/23/2026 ST-6 page 1 of 1
Elev./
Depth
ft
1051.3
1.0
1048.3
4.0
1041.3
11.0
1034.3
18.0
1029.3
23.0
1024.3
28.0
1022.3
30.0 WaterLevelDescription of Materials
(Soil-ASTM D2488 or 2487; Rock-USACE EM
1110-1-2908)
PAVEMENT, 4 inches of bituminous over 8
inches of apparent aggregate base
FILL: SANDY LEAN CLAY (CL), brown, moist
LEAN CLAY (CL), Silt lenses, brown, moist,
medium (ALLUVIUM)
FAT CLAY (CH), gray, moist, medium
(ALLUVIUM)
SANDY LEAN CLAY (CL), gray, moist, medium
(ALLUVIUM)
FAT CLAY (CH), gray, wet, medium
(ALLUVIUM)
SANDY LEAN CLAY (CL), gray, moist, medium
(ALLUVIUM)
END OF BORING
Boring then backfilled with bentonite chips
5
10
15
20
25
30 SampleBlows
(N-Value)
Recovery
1-2-2
(4)
16"
2-3-3
(6)
18"
2-3-3
(6)
18"
2-2-3
(5)
18"
2-2-4
(6)
18"
2-3-3
(6)
18"
1-3-3
(6)
18"
1-2-3
(5)
18"
2-2-3
(5)
18"
qₚ
tsf
MC
%
34
34
48
Tests or Remarks
LL=49, PL=24, PI=25
LL=79, PL=27, PI=52
Water observed at 24.5 feet
while drilling.
LOG OF BORING
See Descriptive Terminology sheet for explanation of abbreviations
Project Number B2508902
Geotechnical Evaluation
Minnetonka Middle School West Improvements
6421 Hazeltine Boulevard
Excelsior, Minnesota
BORING:ST-7
LOCATION: Captured with RTK GPS.
DATUM:NAD 1983 HARN Adj MN Hennepin (US Feet)
NORTHING:134625.7 EASTING:449131.6
DRILLER:B Kammermeier/C
Doquette LOGGED BY:B Cook START DATE:10/13/25 END DATE:10/13/25
SURFACE
ELEVATION:1052.3 ft RIG:7506 METHOD:3 1/4" HSA SURFACING:Bituminous WEATHER:
B2508902 Braun Intertec Corporation Print Date:01/23/2026 ST-7 page 1 of 1
Elev./
Depth
ft
1053.5
1.4
1050.9
4.0
1048.9
6.0
1031.9
23.0
1024.9
30.0 WaterLevelDescription of Materials
(Soil-ASTM D2488 or 2487; Rock-USACE EM
1110-1-2908)
PAVEMENT, 5 inches of bituminous over 11
inches of apparent aggregate base
FILL: SANDY LEAN CLAY (CL), dark brown,
moist
FILL: SANDY LEAN CLAY (CL), brown, moist
LEAN CLAY (CL), Silt lenses, brown, moist,
medium to stiff (ALLUVIUM)
LEAN CLAY (CL), gray, moist, medium to stiff
(ALLUVIUM)
END OF BORING
Boring then backfilled with bentonite chips
5
10
15
20
25
30 SampleBlows
(N-Value)
Recovery
2-3-3
(6)
8"
2-4-5
(9)
18"
3-3-6
(9)
18"
2-3-4
(7)
18"
2-3-5
(8)
18"
2-3-4
(7)
18"
1-2-4
(6)
18"
1-1-3
(4)
18"
2-3-6
(9)
14"
qₚ
tsf
MC
%
29
34
Tests or Remarks
LL=48, PL=23, PI=25
Water not observed while
drilling.
LOG OF BORING
See Descriptive Terminology sheet for explanation of abbreviations
Project Number B2508902
Geotechnical Evaluation
Minnetonka Middle School West Improvements
6421 Hazeltine Boulevard
Excelsior, Minnesota
BORING:ST-8
LOCATION: Captured with RTK GPS.
DATUM:NAD 1983 HARN Adj MN Hennepin (US Feet)
NORTHING:134620.5 EASTING:449231.2
DRILLER:B Kammermeier/C
Doquette LOGGED BY:B Cook START DATE:10/16/25 END DATE:10/16/25
SURFACE
ELEVATION:1054.9 ft RIG:7506 METHOD:3 1/4" HSA SURFACING:Bituminous WEATHER:
B2508902 Braun Intertec Corporation Print Date:01/23/2026 ST-8 page 1 of 1
Elev./
Depth
ft
1049.7
1.8
1047.5
4.0
1042.5
9.0
1036.5
15.0 WaterLevelDescription of Materials
(Soil-ASTM D2488 or 2487; Rock-USACE EM
1110-1-2908)
FILL: POORLY GRADED SAND (SP), with
Gravel, brown, moist
FILL: LEAN CLAY (CL), brown, moist
SANDY LEAN CLAY (CL), Silt lenses, brown,
moist, medium to stiff (ALLUVIUM)
LEAN CLAY (CL), gray, moist, medium
(ALLUVIUM)
END OF BORING
Boring then backfilled with bentonite chips
5
10
15
20
25
30 SampleBlows
(N-Value)
Recovery
4-4-5
(9)
10"
4-3-8
(11)
12"
2-4-8
(12)
18"
3-4-5
(9)
18"
2-3-3
(6)
18"
1-2-4
(6)
18"
qₚ
tsf
MC
%
26
Tests or Remarks
P200=80%
Water not observed while
drilling.
LOG OF BORING
See Descriptive Terminology sheet for explanation of abbreviations
Project Number B2508902
Geotechnical Evaluation
Minnetonka Middle School West Improvements
6421 Hazeltine Boulevard
Excelsior, Minnesota
BORING:ST-9
LOCATION: Captured with RTK GPS.
DATUM:NAD 1983 HARN Adj MN Hennepin (US Feet)
NORTHING:134527.0 EASTING:449119.8
DRILLER:B Kammermeier/C
Doquette LOGGED BY:B Cook START DATE:10/17/25 END DATE:10/17/25
SURFACE
ELEVATION:1051.5 ft RIG:7506 METHOD:3 1/4" HSA SURFACING:Bituminous WEATHER:
B2508902 Braun Intertec Corporation Print Date:01/23/2026 ST-9 page 1 of 1
Elev./
Depth
ft
1058.3
0.8
1048.1
11.0
1044.1
15.0 WaterLevelDescription of Materials
(Soil-ASTM D2488 or 2487; Rock-USACE EM
1110-1-2908)
SILTY SAND (SM), brown, moist (TOPSOIL
FILL)
FILL: SANDY LEAN CLAY (CL), brown, moist
LEAN CLAY (CL), Silt lenses, brown, moist,
medium to stiff (ALLUVIUM)
END OF BORING
Boring then backfilled with bentonite chips
5
10
15
20
25
30 SampleBlows
(N-Value)
Recovery
9-4-6
(10)
8"
5-6-6
(12)
8"
4-8-6
(14)
12"
2-3-4
(7)
14"
2-4-5
(9)
16"
2-3-5
(8)
18"
qₚ
tsf
MC
%
19
31
Tests or Remarks
P200=65%
P200=99%
Water not observed while
drilling.
LOG OF BORING
See Descriptive Terminology sheet for explanation of abbreviations
Project Number B2508902
Geotechnical Evaluation
Minnetonka Middle School West Improvements
6421 Hazeltine Boulevard
Excelsior, Minnesota
BORING:ST-10
LOCATION: Captured with RTK GPS.
DATUM:NAD 1983 HARN Adj MN Hennepin (US Feet)
NORTHING:134616.3 EASTING:449328.5
DRILLER:B Kammermeier/C
Doquette LOGGED BY:B Cook START DATE:10/17/25 END DATE:10/17/25
SURFACE
ELEVATION:1059.1 ft RIG:7506 METHOD:3 1/4" HSA SURFACING:Grass WEATHER:
B2508902 Braun Intertec Corporation Print Date:01/23/2026 ST-10 page 1 of 1
Elev./
Depth
ft
1058.2
0.9
1048.1
11.0
1041.1
18.0 WaterLevelDescription of Materials
(Soil-ASTM D2488 or 2487; Rock-USACE EM
1110-1-2908)
SILTY SAND (SM), brown, moist (TOPSOIL
FILL)
FILL: LEAN CLAY (CL), brown, moist
SANDY LEAN CLAY (CL), brown, moist,
medium to stiff (ALLUVIUM)
END OF BORING
Boring then backfilled with bentonite chips
5
10
15
20
25
30 SampleBlows
(N-Value)
Recovery
3-6-7
(13)
10"
3-3-6
(9)
10"
6-8-12
(20)
14"
3-6-7
(13)
16"
2-2-5
(7)
18"
3-3-6
(9)
18"
qₚ
tsf
MC
%
23
Tests or Remarks
P200=76%
Water not observed while
drilling.
LOG OF BORING
See Descriptive Terminology sheet for explanation of abbreviations
Project Number B2508902
Geotechnical Evaluation
Minnetonka Middle School West Improvements
6421 Hazeltine Boulevard
Excelsior, Minnesota
BORING:ST-11
LOCATION: Captured with RTK GPS.
DATUM:NAD 1983 HARN Adj MN Hennepin (US Feet)
NORTHING:134611.9 EASTING:449428.7
DRILLER:B Kammermeier/C
Doquette LOGGED BY:B Cook START DATE:10/17/25 END DATE:10/17/25
SURFACE
ELEVATION:1059.1 ft RIG:7506 METHOD:3 1/4" HSA SURFACING:Grass WEATHER:
B2508902 Braun Intertec Corporation Print Date:01/23/2026 ST-11 page 1 of 1
Elev./
Depth
ft
1034.7
0.3
1025.0
10.0
1021.0
14.0
1020.0
15.0 WaterLevelDescription of Materials
(Soil-ASTM D2488 or 2487; Rock-USACE EM
1110-1-2908)
SILTY SAND (SM), brown, moist (TOPSOIL
FILL)
FILL: SANDY LEAN CLAY (CL), trace Gravel,
Silt lenses, brown, moist
LEAN CLAY (CL), brown, moist (ALLUVIUM)
SANDY LEAN CLAY (CL), brown, wet
(ALLUVIUM)
END OF BORING
Boring then backfilled with bentonite chips
5
10
15
20
25
30 SampleBlows
(N-Value)
Recovery
1-2-3
(5)
9"
1-3-5
(8)
17"
5-4-7
(11)
11"
5-5-6
(11)
13"
3-7-7
(14)
14"
3-5-5
(10)
13"
qₚ
tsf
MC
%
28
35
Tests or Remarks
P200=67%
Water not observed while
drilling.
LOG OF BORING
See Descriptive Terminology sheet for explanation of abbreviations
Project Number B2508902
Geotechnical Evaluation
Minnetonka Middle School West Improvements
6421 Hazeltine Boulevard
Excelsior, Minnesota
BORING:ST-12
LOCATION: Captured with RTK GPS.
DATUM:NAD 1983 HARN Adj MN Hennepin (US Feet)
NORTHING:134556.1 EASTING:448600.3
DRILLER:B Kammermeier/C
Doquette LOGGED BY:B Cook START DATE:10/10/25 END DATE:10/10/25
SURFACE
ELEVATION:1035.0 ft RIG:7506 METHOD:3 1/4" HSA SURFACING:Weeds WEATHER:
B2508902 Braun Intertec Corporation Print Date:01/23/2026 ST-12 page 1 of 1
Results of Double Ring Infiltrometer Testing (ASTM D 3385) - Gallon Meter Method
Test Number: DRI-1
Project Description: MMW Additions
Project Number: B2508902 Test Location:
Date: October 17, 2025
Liquid used:Potable water Test Elevation:12" below the top soil
Inner Ring Area: 113 square inches Ground Temperature Fo: 61
Outer Ring Area: 452 square inches Water Temperature Fo:65
Test performed by:Abhinay Pitta Moisture Content of soil at test
depth before test:11%
Weather:66 Percent Fines passing a 200 sieve
on soil at test depth:23%
Depth Soil Profile
15 0.8 0-6 inches Fine grain, Poorly graded, Moist, Black
30 1.3 6-12 inches Fine grain, Poorly graded, Moist, Black
45 0.6 12-18 inches Fine grain, Poorly graded, Moist, Brown-Black compacted, SM
60 0.5 18-24 inches Fine grain, Poorly graded, Moist, Brown-Black compacted, SM
75 0.0 24-30 inches
90 0.5 30-36 inches
105 0.0
120 0.0 Groundwater depth
0.5
0.1
Picture of Test Location
Steady State Infiltration Rate of Inner Ring Over Last 4 intervals (in/hr)
Average Infiltration Rate of Inner Ring Over Entire Test (in/hr)
Sports Field
Time Infiltration Rate
(in/hr)
Subgrade Conditions Below Tested Depth
0
5
10
15
20
25
0 15 30 45 60 75 90 105 120 135Infiltration Rate (in/hr)Time (minutes)
Inner Ring Infiltration Rate vs. Time
Test performed by Braun Intertec personnel in general accordance with test method ASTM D 3385.
Results of Double Ring Infiltrometer Testing (ASTM D 3385) - Gallon Meter Method
Test Number: DRI-2
Project Description: MMW Additions
Project Number: B2508902 Test Location:
Date: October 17, 2025
Liquid used:Potable water Test Elevation:18" below the topsoil
Inner Ring Area: 113 square inches Ground Temperature Fo: 62
Outer Ring Area: 452 square inches Water Temperature Fo:71
Test performed by:Abhinay Pitta Moisture Content of soil at test
depth before test:14%
Weather:66 Percent Fines passing a 200 sieve
on soil at test depth:40%
Depth Soil Profile
15 1.7 0-6 inches Fine Grain, Poorly Graded, Moist, Black, SM
30 1.3 6-12 inches Fine Grain, Poorly Graded, Moist, Black, SM
45 0.9 12-18 inches Fine Grain, Poorly Graded, Moist, Black-Brown, SM
60 0.3 18-24 inches Fine Grain, Poorly Graded, Moist, Brown, Compacted, SM
75 0.6 24-30 inches Compacted
90 0.3 30-36 inches Compacted
105 1.5
120 1.2 Groundwater depth
1.0
0.9
Picture of Test Location
Steady State Infiltration Rate of Inner Ring Over Last 4 intervals (in/hr)
Average Infiltration Rate of Inner Ring Over Entire Test (in/hr)
Sports Field
Time Infiltration Rate
(in/hr)
Subgrade Conditions Below Tested Depth
0
5
10
15
20
25
0 15 30 45 60 75 90 105 120 135Infiltration Rate (in/hr)Time (minutes)
Inner Ring Infiltration Rate vs. Time
Test performed by Braun Intertec personnel in general accordance with test method ASTM D 3385.
Descriptive Terminology of Soil
Based on Standards ASTM D2487/2488
(Unified Soil Classification System)
Group
Symbol Group NameB
Cu ≥ 4 and 1 ≤ Cc ≤ 3D GW Well-graded gravelE
Cu < 4 and/or (Cc < 1 or Cc > 3)D GP Poorly graded gravelE
Fines classify as ML or MH GM Silty gravelE F G
Fines Classify as CL or CH GC Clayey gravelE F G
Cu ≥ 6 and 1 ≤ Cc ≤ 3D SW Well-graded sandI
Cu < 6 and/or (Cc < 1 or Cc > 3)D SP Poorly graded sandI
Fines classify as ML or MH SM Silty sandF G I
Fines classify as CL or CH SC Clayey sandF G I
CL Lean clayK L M
PI < 4 or plots below "A" lineJ ML SiltK L M
Organic OL
CH Fat clayK L M
MH Elastic siltK L M
Organic OH
PT Peat Highly Organic Soils
Silts and Clays
(Liquid limit less than
50)
Silts and Clays
(Liquid limit 50 or
more)
Primarily organic matter, dark in color, and organic odor
Inorganic
Inorganic
PI > 7 and plots on or above "A" lineJ
PI plots on or above "A" line
PI plots below "A" line
Criteria for Assigning Group Symbols and
Group Names Using Laboratory TestsA
Soil Classification
Coarse-grained Soils (more than 50% retained on No. 200 sieve)Fine-grained Soils (50% or more passes the No. 200 sieve) Sands
(50% or more coarse
fraction passes No. 4
sieve)
Clean Gravels
(Less than 5% finesC)
Gravels with Fines
(More than 12% finesC)
Clean Sands
(Less than 5% finesH)
Sands with Fines
(More than 12% finesH)
Gravels
(More than 50% of
coarse fraction
retained on No. 4 sieve)
Liquid Limit −oven dried
Liquid Limit −not dried <0.75 Organic clay K L M N
Organic silt K L M O
Liquid Limit −oven dried
Liquid Limit −not dried <0.75 Organic clay K L M P
Organic silt K L M Q
Particle Size Identification
Boulders.............. over 12"
Cobbles................ 3" to 12"
Gravel
Coarse............. 3/4" to 3" (19.00 mm to 75.00 mm)
Fine................. No. 4 to 3/4" (4.75 mm to 19.00 mm)
Sand
Coarse.............. No. 10 to No. 4 (2.00 mm to 4.75 mm)
Medium........... No. 40 to No. 10 (0.425 mm to 2.00 mm)
Fine.................. No. 200 to No. 40 (0.075 mm to 0.425 mm)
Silt........................ No. 200 (0.075 mm) to .005 mm
Clay...................... < .005 mm
Relative ProportionsL, M
trace............................. 0 to 5%
little.............................. 6 to 14%
with.............................. ≥ 15%
Inclusion Thicknesses
lens............................... 0 to 1/8"
seam............................. 1/8" to 1"
layer.............................. over 1"
Apparent 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
A.Based on the material passing the 3-inch (75-mm) sieve.
B.If field sample contained cobbles or boulders, or both, add "with cobbles or boulders, or
both" to group name.
C. Gravels with 5 to 12% fines require dual symbols:
GW-GM well-graded gravel with silt
GW-GC well-graded gravel with clay
GP-GM poorly graded gravel with silt
GP-GC poorly graded gravel with clay
D.Cu = D60 / D10 Cc = 𝐷30 2 / (𝐷10 𝑥𝐷60)
E.If soil contains ≥ 15% sand, add "with sand" to group name.
F.If fines classify as CL-ML, use dual symbol GC-GM or SC-SM.
G. If fines are organic, add "with organic fines" to group name.
H. Sands with 5 to 12%fines require dual symbols:
SW-SM well-graded sand with silt
SW-SC well-graded sand with clay
SP-SM poorly graded sand with silt
SP-SC poorly graded sand with clay
I.If soil contains ≥ 15% gravel, add "with gravel" to group name.
J. If Atterberg limits plot in hatched area, soil is CL-ML, silty clay.
K.If soil contains 15 to < 30% plus No. 200, add "with sand" or "with gravel", whichever is
predominant.
L. If soil contains ≥ 30% plus No. 200, predominantly sand, add “sandy” to group name.
M. If soil contains ≥ 30% plus No. 200 predominantly gravel, add “gravelly” to group name.
N. PI ≥ 4 and plots on or above “A” line.
O. PI < 4 or plots below “A” line.
P. PI plots on or above “A” line.
Q.PI plots below “A” line.
Laboratory Tests
DD Dry density,pcf qp Pocket penetrometer strength, tsf
WD Wet density, pcf qU Unconfined compression test, tsf
P200 % Passing #200 sieve LL Liquid limit
MC Moisture content, %PL Plastic limit
OC Organic content, %PI Plasticity index
Consistency of Blows Approximate Unconfined
Cohesive Soils Per Foot Compressive Strength
Very soft................... 0 to 1 BPF................... < 0.25 tsf
Soft........................... 2 to 4 BPF................... 0.25 to 0.5 tsf
Medium.................... 5 to 8 BPF .................. 0.5 to 1 tsf
Stiff........................... 9 to 15 BPF................. 1 to 2 tsf
Very Stiff................... 16 to 30 BPF............... 2 to 4 tsf
Hard.......................... over 30 BPF................ > 4 tsf
Drilling Notes:
Blows/N-value: Blows indicate the driving resistance recorded
for each 6-inch interval. The reported N-value is the blows per
foot recorded by summing the second and third interval in
accordance with the Standard Penetration Test, ASTM D1586.
Partial Penetration:If the sampler could not be driven through a
full 6-inch interval, the number of blows for that partial
penetration is shown as #/x" (i.e. 50/2"). The N-value is reported
as "REF" indicating refusal.
Recovery: Indicates the inches of sample recovered from the
sampled interval. For a standard penetration test, full recovery is
18", and is 24" for a thinwall/shelby tube sample.
WOH: Indicates the sampler penetrated soil under weight of
hammer and rods alone; driving not required.
WOR: Indicates the sampler penetrated soil under weight of rods
alone; hammer weight and driving not required.
Water Level: Indicates the water level measured by the drillers
either while drilling ( ), at the end of drilling ( ), or at some
time after drilling ( ).
Moisture Content:
Dry:Absence of moisture, dusty, dry to the touch.
Moist: Damp but no visible water.
Wet: Visible free water, usually soil is below water table.
5/2021