Att. 17 Geotechnical Evaluation Report.pdf

Table of Contents

Description Page

A. Introduction

A.1. Project Description A.2. Site Conditions and History A.3. Purpose A.4. Background Information and Reference Documents A.5. Scope of Services

B. Results B.1. Geologic Overview B.2. Boring Results B.3. Groundwater B.4. Laboratory Test Results

C. Recommendations C.1. Design and Construction Discussion C.2. Rammed Aggregate Piers C.3. Site Grading and Subgrade Preparation

C.3.a. Site Grading C.3.b. Exterior Slab Subgrade Preparation C.3.c. Engineered Fill Materials and Compaction C.3.d. Special Inspection of Soils

C.4. Spread Footings C.5. Interior Slabs

C.5.a. Subgrade Modulus C.5.b. Moisture Vapor Protection

C.6. Exterior Slabs C.7. Utilities

C.7.a. Subgrade Stabilization C.7.b. Trench Backfill C.7.c. Corrosion Potential

C.8. Equipment Support D. Procedures

D.1. Penetration Test Borings D.2. Exploration Logs

D.2.a. Log of Boring Sheets D.2.b. Geologic Origins

D.3. Material Classification and Testing D.3.a. Visual and Manual Classification D.3.b. Laboratory Testing

D.4. Groundwater Measurements E. Qualifications

E.1. Variations in Subsurface Conditions E.1.a. Material Strata E.1.b. Groundwater Levels

E.2. Continuity of Professional Responsibility E.2.a. Plan Review E.2.b. Construction Observations and Testing

Table of Contents (continued)

Description Page

E.3. Use of Report E.4. Standard of Care

Appendix Soil Boring Location Sketch Log of Boring Sheets ST-1 to ST-2 (3 pages) Descriptive Terminology of Soil

A. Introduction

A.1. Project Description

This Geotechnical Evaluation Report addresses the design and construction of the proposed Minneapolis

VA Hospital Addition, located in Minneapolis, Minnesota. The project will include the construction of a single-story building addition with a concrete slab-on-grade, concrete masonry unit (CMU) walls, and steel framing. Table 1 provides project details.

Table 1. Building Description

Aspect Description

Above grade levels 1

Finished floor elevation (MSL) 840 (Assumed)

Column loads (kips) 50 (Assumed)

Wall loads (kips) 3-4 (Assumed)

Nature of construction

Concrete slab-on-grade, CMU walls, and steel framing.

Conventional spread footings will be utilized following subgrade improvement. Footprint of about 1,000 square feet.

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.

A.2. Site Conditions and History

Currently, the site exists as a landscaped area adjacent to the east side of the existing hospital’s south entrance. Current grades are relatively flat at an elevation of about 839 1/2 feet above mean sea level

(MSL).

Anderson Engineering of Minnesota, LLC Project B1710194 February 9, 2018

Based on previous information obtained at this site, including soil borings obtained during the design and construction of the existing hospital, subgrade conditions at this site will generally consist of surficial existing fill overlying native granular soils with limestone bedrock present with about 50 feet of existing grade.

We also note that the existing hospital has 1 to 2 to levels of below grade basements. These underground levels associated with the adjacent building would also contribute to the quantity of existing fill material present at this site.

A.3. Purpose

The purpose of this geotechnical evaluation was to characterize subsurface geologic conditions at select exploration locations, evaluate their impact, and provide geotechnical recommendations for use in the design and construction of the proposed building addition.

A.4. Background Information and Reference Documents

We reviewed the following information:

A previous Geotechnical Evaluation Report prepared by Braun Intertec dated June 10, 1982 performed during the design and construction of the existing hospital.

Aerial images of the site retrieved from Google Earth.

Communications with the design team regarding site history.

The Surficial Geology Map for Hennepin County prepared by the University of Minnesota.

The map is denoted as Atlas C-04, Plate 3, Surficial Geology, and is dated 1989.

A.5. Scope of Services

We performed our scope of services for the project in accordance with our Proposal QTB06443, dated

September 19, 2017. 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. We staked the new exploration locations and acquired the 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 2 standard penetration test (SPT) borings, denoted as ST-1 to ST-2. The proposed depth of these borings was altered, one of which was extended to a depth of 30 feet and the other to terminate on bedrock.

Performing laboratory testing on select samples to aid in soil classification and engineering analysis.

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 subgrade preparation and for use in the design and construction of foundations, floor slabs, exterior slabs, and utilities.

Our scope of services did not include environmental services or testing, and we did not train the personnel performing this evaluation to provide environmental services or testing. We can provide these services or testing at your request.

B. Results

B.1. Geologic Overview

We based the geologic origins used in this report on the soil types, 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 geologic history for the site.

B.2. Boring Results

Table 2 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. Bedrock was encountered at the termination of both borings. No samples of the bedrock were retrieved. The Descriptive

Terminology sheet in the Appendix includes definitions of abbreviations used in Table 2.

Table 2. Subsurface Profile Summary

Strata

Soil Type -

ASTM

Classification

Range of Penetration Resistances

(Blows per Foot) Commentary and Details

Topsoil fill SM, OL N/A Generally dark brown in color.

Thicknesses at boring locations were about 1 foot.

Moisture condition generally moist to wet.

Fill SP-SM, SM 10 to 36 BPF

Generally light brown to brown in color.

Thicknesses at boring locations varied from about 9 to 23 feet.

Existing fills are primarily sandy soils with varying amounts of silt.

Moisture condition generally moist.

Glacial deposits

SP, SM 8 to 45 BPF General penetration resistance of 10 to 30 BPF.

Generally brown in color.

Variable amounts of gravel; may contain cobbles and boulders.

Moisture condition generally moist to wet.

SC 2 to 11 BPF

Refusal to auger advancement was encountered in Boring ST-2 at a depth of about 45 feet below grade.

We anticipate that refusal was caused by apparent weathered limestone bedrock; however, rock coring was beyond our scope of services. Thus, the actual composition of refusal materials was not determined.

For simplicity in this report, we define existing fill to mean existing, uncontrolled, or undocumented fill.

B.3. Groundwater

We did not observe groundwater while performing our borings, thus, it is our opinion that static groundwater is present below the anticipated excavation depths at this site. However, groundwater may take days or longer to reach equilibrium in the boreholes and we immediately backfilled the boreholes, in accordance with our scope of work. If the project team identifies a need for more accurate determination of groundwater depth, we can install piezometers. Project planning should anticipate seasonal and annual fluctuations of groundwater.

B.4. Laboratory Test Results

We performed laboratory testing on select soil samples obtained from the borings. The moisture content of the fill soils varied from approximately 7 to 11 percent, indicating that the material was near to above its probable optimum moisture content. Our mechanical analyses indicated that the silty sands contained

16 to 21 percent silt and clay particles by weight.

The Log of Boring sheets in the Appendix show the results of the laboratory testing we performed, next to the tested sample depth.

C. Recommendations

C.1. Design and Construction Discussion

Two borings were drilled for this site, one was drilled to a depth of 30 feet and the other was drilled to bedrock. Both borings showed existing fill soils in place, while Boring ST-2 had a deep fill zone of approximately 23 feet. The placement of this fill is undocumented. As such, there is uncertainty as to the manner in which it was placed as well as the consistency of the materials. Thus, we do not recommend supporting foundations directly on this material without additional subgrade improvement.

For a building of this size, a subgrade soil correction of this magnitude (20+ feet deep+) would likely be cost-prohibitive. As an alternate approach, we recommend that rammed aggregate piers be installed to improve the existing subgrade. Rammed aggregate piers will densify and improve subgrade conditions, allow for the existing deep fills to be left in place (avoiding deep soil corrections) and support the building on conventional spread footings.

C.2. Rammed Aggregate Piers

A subgrade improved with rammed aggregate piers will reduce the potential for detrimental settlement of the fill, increase the bearing capacity, and eliminate the need for deep excavation at this site.

Subgrade improvements consisting of installing rammed aggregate piers is performed prior to foundation construction, and, following the installation of the rammed aggregate piers, the proposed building could be supported upon conventional spread footing foundations.

Rammed aggregate piers are constructed by auguring a hole, removing the volume of soil from the hole, and building a column of clean, open graded aggregate. The column is constructed with aggregate placed in lifts using a compactor from the bottom up. The vibratory energy and ramming action causes the aggregate to interlock, forming a stiff pier that provides soil reinforcement and increases shear resistance. Installation of rammed aggregate piers is typically performed relatively quickly by a qualified contractor.

We recommend that rammed aggregate piers be installed under foundations for the proposed building.

The existing fill soils also pose some threat to the building’s floor slabs; however, consideration could be given to not installing rammed aggregate piers under the floor slabs. The project would realize a cost savings by not improving the subgrade below the floor slab. If this risk is not acceptable, rammed aggregate piers would be needed under the floor slabs as well.

The rammed aggregate piers should extend through any existing fills into the underlying glacial-deposited soils. Thus, we anticipate that the piers will extend to a depth of between 20 to 25 feet. Any fill needed to reach finished grades should be placed prior to the installation of the piers.

We recommend that rammed aggregate piers be designed by a licensed engineer and installed by a specialty contractor with proven experience with this type of construction in this region.

Rammed aggregate pier installations do emit ground vibrations at varying levels and intensities. The adjacent building should be evaluated for any potential impacts to the anticipated ground produced vibrations. Additional preconstruction condition assessments of the existing structure should be performed to further determine the building’s susceptibility to these vibrations and establish limits for this project.

C.3. Site Grading and Subgrade Preparation

C.3.a. Site Grading

Rough grading to site hold down elevations should be established prior to the installation of rammed aggregate piers.

C.3.b. Exterior Slab Subgrade Preparation

We recommend the following steps for exterior slab subgrade preparation. Note that project planning may need to require additional subcuts to limit frost heave.

Strip unsuitable soils consisting of topsoil, organic soils, vegetation, and pavements from the area, within 2 feet of the surface of the proposed slab subgrade.

Have a geotechnical representative observe the excavated subgrade to evaluate if additional subgrade improvements are necessary.

Slope subgrade soils to areas of sand or drain tile to allow the removal of accumulating water.

Scarify, moisture condition and surface compact the subgrade with at least 3 passes of a large roller with a minimum drum diameter of 3 feet.

Place engineered fill to grade and compact in accordance with Section C.3.b to bottom of exterior slab section. See Section C.8 for additional considerations related to frost heave.

C.3.c. Engineered Fill Materials and Compaction

Table 3 below contains our recommendations for engineered fill materials.

Table 3. 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 100% passing 2-inch sieve <25% passing #200 sieve

< 3% Organic Content (OC)

Drainage layer Non-frost-susceptible Clean sand SP

100% passing 1-inch sieve < 50% passing #40 sieve < 5% passing #200 sieve

< 2% OC

Below landscaped surfaces, where subsidence is not a concern

Non-structural fill Any 100% passing 6-inch sieve < 10% OC

We anticipate that the non-organic, on site existing fill or native soils will generally be suitable for reuse as structural fill. Some separation of organics and moisture conditioning should be anticipated prior to reuse. Clean sands, as needed, will need to be imported. Any materials to be used as engineered fill should be tested and approved by the engineer prior to placement.

We recommend spreading engineered fill in loose lifts of approximately 8 inches thick. We recommend compacting engineered fill in accordance with the criteria presented below in Table 4. 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 4. Compaction Recommendations Summary

Reference

Relative Compaction, percent

(ASTM D698 –

Standard Proctor)

Moisture Content Variance from Optimum, percentage points

Sands (typically SP, SP-SM, SM)

Silty Sands

(SM)

Below foundations 98 ±3 -1 to +3

Below interior slabs 95 ±3 -1 to +3

Below landscaped surfaces

90 ±5 ±4

The project documents should not allow the contractor to use frozen materials 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.

C.3.d. Special Inspection 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 type of 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.

C.4. Spread Footings

Table 5 below contains our recommended parameters for use in foundation design and construction for footings bearing on a subgrade improved with rammed aggregate piers.

Table 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) 36 – Columns

24 - Walls

Minimum embedment below final exterior grade for heated structures (inches)

Minimum embedment below final exterior grade for unheated structures or for footings not protected from freezing temperatures during construction (inches)

Total estimated settlement (inches) < 1

Differential settlement Typically about 2/3 of total settlement

We note that the allowable soil bearing pressure for foundations bearing on a subgrade improved with rammed aggregate piers would be determined by the specialty designer.

C.5. Interior Slabs

C.5.a. Subgrade Modulus

The anticipated floor slab subgrade will consist of silty sand fill. We recommend using a modulus of subgrade reaction, k, of 100 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.

If rammed aggregate piers are installed below the floor slab, the modulus of subgrade reaction could likely be increased to 200 pci. We note that the modulus of subgrade reaction for a subgrade improved with rammed aggregate piers would be determined by the specialty designer.

The Log of Boring sheets show the results of the laboratory testing we performed, next to the tested sample depth. The Appendix contains these sheets.

C.5.b. 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.

C.6. Exterior Slabs

We consider the sandy fill soils to be slightly frost susceptible and unfavorable amounts of heaving could occur if these soils become saturated and freeze. Grading to direct surface drainage away from buildings helps limit the potential for saturation and subsequent heaving to occur. Still, even limited amounts of movement can create tripping hazards.

One method to help limit the potential for heaving to occur is to remove frost-susceptible soils present below the overlying slab or pavement area down to bottom-of-footing grades, and replace the excavated material with non-frost-susceptible, engineered fill. We recommend providing drainage at the base of the subcut, as well as gradual transitions from this subcut (3H:1V or flatter gradient).

Figure 1 shows an illustration summarizing some of the recommendations above.

Figure 1. Frost Protection Geometry Illustration

An alternative method to reduce the risk of heaving is to support the slabs on frost-depth footings, and suspend the slabs at least 4 inches above the underlying subgrade soils. With this alternative, we recommend making accommodations for differential frost heave at transition areas.

Over the life of the pavement or slab, cracks may develop and joints may open up, which will expose the subgrade and allow water to enter the subgrade. This water entering the subgrade increases the likelihood of heave. It will be critical that the owner develop a detailed maintenance program to repair any cracks and joints that may develop during the useful life of the various surface features. The maintenance program should pay special attention to areas where dissimilar materials abut one another, where construction joints occur and where shrinkage cracks develop.

C.7. Utilities

C.7.a. Subgrade Stabilization

Earthwork activities associated with utility installations located inside the building area should adhere to the recommendations in Section C.3.b.

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.

C.7.b. Trench Backfill

We recommend that utility trench backfill adhere to the recommendations of C.3.3 depending on what overlies the trench.

C.7.c. Corrosion Potential

A majority of the soil borings indicated the site predominantly consists of sandy soils. We consider these soils non- to slightly-corrosive to metallic conduits. If utilities extend through clay soils, we recommend bedding the utilities in sandy soil free of any clay lumps or constructing the utilities with non-corrosive materials.

C.8. 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, etc. We can assist you in this evaluation.

D. Procedures

D.1. Penetration Test Borings

We drilled the penetration test borings with a truck-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 to ASTM D1586. The Log of Boring sheets 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 forwarded a sealing record for those boreholes to the Minnesota Department of Health Well Management Section.

D.2. Exploration Logs

D.2.a. 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 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.

D.2.b. 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 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.

D.3. Material Classification and Testing

D.3.a. 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.

D.3.b. Laboratory Testing

The Log of Boring sheets 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.

D.4. Groundwater Measurements

The drillers checked for groundwater while advancing the penetration test borings, and again after auger withdrawal. We then sealed the boreholes as noted on the Log of Boring sheets.

E. Qualifications

E.1. Variations in Subsurface Conditions

E.1.a. 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 boring 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.

E.1.b. Groundwater Levels

We made groundwater measurements under the conditions reported herein and shown on the Log of

Borings sheets, and interpreted in the text of this report. Note that the observation periods were relatively short, and 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.

E.2. Continuity of Professional Responsibility

E.2.a. 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.

E.2.b. 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.

E.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.

E.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

Project No:

B1710194

Drawn By:

Date Drawn:

Checked By:

Last Modified: 12/29/17

Drawing No:

F:\2017\B1710194.dwg,Geotech,12/29/2017 5:30:40 AM

B1710194

BJB

12/14/17

BMT

Minneapolis VA Hospital Addition

1 Veterans Drive

Minneapolis, Minnesota

Soil Boring Location Sketch braunintertec.com 952.995.2000

Minneapolis, MN 55438 11001 Hampshire Avenue S

DENOTES APPROXIMATE LOCATION OF

STANDARD PENETRATION TEST BORING

SCALE: 1" = 50'

50'25'

N

Auger chatter from 12 to 18 feet.

Auger chatter from 27 to 30 feet.

** Water not observed while drilling.

Boring then grouted.

FILL

FILL

FILL

FILL

SM

SP

SM

SC

FILL: Organic Clay, dark brown, wet.

(Topsoil Fill)

FILL: Silty Sand, fine-grained, with Gravel, dark brown, moist.

FILL: Poorly Graded Sand with Silt, fine-grained, trace Gravel, brown, moist.

FILL: Silty Sand, fine-grained, trace Gravel and organics, black, moist.

SILTY SAND, fine-grained, trace Gravel, brown, moist, medium dense to loose.

(Glacial Till)

POORLY GRADED SAND, fine- to medium-grained, trace Gravel, light brown, moist, medium dense.

(Glacial Till)

SILTY SAND, fine- to medium-grained, trace Gravel, brown, moist, medium dense.

(Glacial Till)

CLAYEY SAND, with Gravel, brown, moist, rather stiff.

(Glacial Till)

Weathered Limestone at 30 feet.

END OF BORING. **

838.8

835.6

832.6

830.6

825.6

821.6

816.6

808.6

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4.0

7.0

9.0

14.0

18.0

23.0

31.0

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LOCATION: See attached sketch.

(Soil-ASTM D2488 or D2487, Rock-USACE EM1110-1-2908)

Description of Materials

ST-1

METHOD:

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Braun Project B1710194

GEOTECHNICAL EVALUATION

Minneapolis VA Hospital Addition 1 Veterans Drive Minneapolis, Minnesota

P200

MC

%Symbol

Elev.

feet 839.6

Depth feet

0.0

16 Auger chatter from 5 to 15 feet.

No recovery.

FILL

FILL

FILL

FILL

FILL

SC

SM

FILL: Silty Sand, fine-grained, dark brown, moist.

(Topsoil Fill)

FILL: Silty Sand, fine-grained, dark brown, moist.

FILL: Silty Sand, fine- to medium-grained, with Gravel, with balls of Clay, brown, moist.

FILL: Poorly Graded Sand with Silt, fine-grained, brown, moist.

FILL: Silty Sand, fine-grained, with Gravel, brown, moist.

CLAYEY SAND, trace Gravel, brown, wet.

(Glacial Till)

SILTY SAND, fine-grained, with Gravel, brown, moist, dense to very dense.

(Glacial Till)

838.7

835.6

832.6

827.6

816.6

812.6

0.9

4.0

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27.0

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LOCATION: See attached sketch.

(Soil-ASTM D2488 or D2487, Rock-USACE EM1110-1-2908)

Description of Materials

ST-2

METHOD:

BORING:

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Braun Project B1710194

GEOTECHNICAL EVALUATION

Minneapolis VA Hospital Addition 1 Veterans Drive Minneapolis, Minnesota

P200

MC

%Symbol

Elev.

feet 839.6

Depth

0.0

50/6"

Auger chatter from 30 to 35 feet.

SILTY SAND, fine-grained, with Gravel, brown, moist, dense to very dense.

(Glacial Till) (continued)

END OF BORING.

Refusal on apparent weathered Limestone bedrock at 45 feet.

Water not observed while drilling.

Boring then grouted.

794.6 45.0

12/20/17 1" = 4'DATE: SCALE:DRILLER:

Tests or NotesWL

ST-2 page 2 of 2

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L O G O F B O R I N G (S ee D es cr ip tiv e T er m in ol og y sh ee t f or e xp la na tio n of a bb re vi at io ns

LOCATION: See attached sketch.

(Soil-ASTM D2488 or D2487, Rock-USACE EM1110-1-2908)

Description of Materials

ST-2 (cont.)

METHOD:

BORING:

BPF

Braun Intertec CorporationB1710194

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Braun Project B1710194

GEOTECHNICAL EVALUATION

Minneapolis VA Hospital Addition 1 Veterans Drive Minneapolis, Minnesota

P200

MC

%Symbol

Elev.

feet 807.6

Depth

32.0

Rev. 9/15

Descriptive Terminology of Soil Standard D 2487 Classification of Soils for Engineering Purposes (Unified Soil Classification System)

a. Based on the material passing the 3-inch (75mm) sieve.

b. If field sample contained cobbles or boulders, or both, add “with cobbles or boulders or both” to group name.

c. Cu = D60/D10 C c = (D30)2

D10 x D60

d. If soil contains ≥15% sand, add “with sand” to group name.

e. 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

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. If soil contains ≥15% gravel, add “with gravel” to group name.

i. Sand 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

j. If Atterberg limits plot in hatched area, soil is a CL-ML, silty clay.

k. If soil contains 10 to 29% plus No. 200, add “with sand” or “with gravel” whichever is predominant.

l. If soil contains ≥ 30% plus No. 200, predominantly sand, add “sandy” to group name.

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” lines.

q. PI plots below “A” line.

Laboratory Tests DD Dry density, pcf OC Organic content, % WD Wet density, pcg S Percent of saturation, % MC Natural moisture content, % SG Specific gravity LL Liquid limit, % C Cohesion, psf PL Plastic limits, % Ø Angle of internal friction PI Plasticity index, % qu Unconfined compressive strength, psf P200 % passing 200 sieve qp Pocket penetrometer strength, tsf

Particle Size Identification

Boulders................. over 12” Cobbles ................. 3” to 12” Gravel Coarse ........... 3/4” to 3” Fine ................ No. 4 to 3/4” Sand Coarse ........... No. 4 to No. 10 Medium .......... No. 10 to No. 40 Fine ................ No. 40 to No. 200 Silt ......................... <No. 200, PI< 4 or below

“A” line Clay ...................... <No. 200, PI > 4 and on or about “A” line

Relative Density of Cohesionless Soils

Very Loose ............. 0 to 4 BPF Loose ..................... 5 to 10 BPF Medium dense ....... 11 to 30 PPF Dense .................... 31 to 50 BPF Very dense ............. over 50 BPF

Consistency of Cohesive Soils

Very soft................. 0 to 1 BPF Soft ........................ 2 to 3 BPF Rather soft ............. 4 to 5 BPF Medium .................. 6 to 8 BPF Rather stiff ............. 9 to 12 BPF Stiff ........................ 13 to 16 BPF Very stiff ................. 17 to 30 BPF Hard ....................... over 30 BPF

Drilling Notes

Standard penetration test borings were advanced by 3 1/4” or 6 1/4” ID hollow-stem augers, unless noted otherwise.

Jetting water was used to clean out auger prior to sampling only where indicated on logs. All samples were taken with the standard 2” OD split-tube samples, except where noted.

Power auger borings were advanced by 4” or 6” diameter continuous flight, solid-stern augers. Soil classifications and strata depths were inferred from disturbed samples augered to the surface, and are therefore, somewhat approximate.

Hand auger borings were advanced manually with a 1 1/2” or 3 1/4” diameter auger and were limited to the depth from which the auger could be manually withdrawn.

BPF: Numbers indicate blows per foot recorded in standard penetration test, also known as “N” value. The sampler was set 6” into undisturbed soil below the hollow-stem auger.

Driving resistances were then counted for second and third 6” increments, and added to get BPF. Where they differed significantly, they are reported in the following form: 2/12 for the second and third 6” increments, respectively.

WH: WH indicates the sampler penetrated soil under weight of hammer and rods alone; driving not required.

WR: WR indicates the sampler penetrated soil under weight of rods alone; hammer weight, and driving not required.

TW: TW indicates thin-walled (undisturbed) tube sample.

Note: All tests were run in general accordance with applicable ASTM standards.

ML or OL