36E77619R0011-007.pdf

REPORT C OVER PAGE

Geotechnical Engineering Report Oncology Addition at the VA Hospital

Milwaukee, Wisconsin

December 21, 2017

Terracon Project No. MR175338

Prepared for:

Guidon Design

Indianapolis, Indiana

Prepared by:

Terracon Consultants, Inc.

Franklin, Wisconsin

Terracon Consultants, Inc. 9856 South 57 th Street Franklin, Wisconsin 53132

P [414] 423 0255 F [414] 423 0566 terracon.com

REPORT C OVER LETTER TO SIGN

Guidon Design

905 N. Capitol Avenue, Suite 100

Indianapolis, Indiana 46204

Attn: Mr. Evan Anderson-Decina

Re: Geotechnical Engineering Report

Oncology Addition at the VA Hospital

5000 West National Avenue

Milwaukee, Wisconsin

Dear Mr. Decina:

We have completed the Geotechnical Engineering services for the above referenced project. This study was performed in general accordance with our proposal number PMR175338, dated August

23, 2017. This report presents the findings of the subsurface exploration and provides geotechnical recommendations concerning earthwork, and the design and construction of foundations and floor slabs for the proposed project.

We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report, or if we may be of further service, please contact us.

Sincerely, Terracon Consultants, Inc.

Nathan J. Liggett, E.I. Paul A. Tarvin, P.E.

Project Manager Regional Geotechnical Manager

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REPORT TOPICS

REPORT TOPICS

INTRODUCTION

SITE CONDITIONS

PROJECT DESCRIPTION

GEOTECHNICAL CHARACTERIZATION

GEOTECHNICAL OVERVIEW

EARTHWORK

SHALLOW FOUNDATIONS

SPECIALTY FOUNDATIONS

FLOOR SLABS

SEISMIC CONSIDERATIONS

GENERAL COMMENTS

Note: This report was originally delivered in a web-based format. Orange Bold text in the report indicates a referenced section heading. The PDF version also includes hyperlinks which direct the reader to that section, and clicking on the logo in the top right corner will bring you back to this page. For more interactive features, please view your project online at client.terracon.com.

ATTACHMENTS

EXPLORATION AND TESTING PROCEDURES

SITE LOCATION AND EXPLORATION PLAN

EXPLORATION RESULTS

SUPPORTING INFORMATION

http://client.terracon.com/

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INTRODUCTION

Geotechnical Engineering Report

Oncology Addition at the VA Hospital

5000 West National Avenue

Milwaukee, Wisconsin

INTRODUCTION

This report presents the results of our subsurface exploration and geotechnical engineering services performed for the proposed Oncology Addition at the VA Hospital to be located at 5000

West National Avenue in Milwaukee, Wisconsin. The purpose of these services is to provide information and geotechnical engineering recommendations relative to:

■ Subsurface soil conditions ■ Foundation design and construction

■ Groundwater conditions ■ Floor slab design and construction

■ Site preparation and earthwork ■ Seismic site classification per IBC

■ Dewatering considerations ■ Excavation considerations

The geotechnical engineering scope of services for this project included the advancement of three

(3) geotechnical borings extending to depths of approximately 20 feet below existing site grades.

Maps showing the site and boring locations are shown in the Site Location and Exploration

Plan sections, respectively. The results of the laboratory testing performed on soil samples obtained from the site during the field exploration are included in the Exploration Results section of this report.

SITE CONDITIONS

The following description of site conditions is derived from our site visit in association with the field exploration and our review of publicly available geologic and topographic maps.

Item Description

Parcel Information

The project is located at 5000 West National Avenue in Milwaukee, Wisconsin.

See Site Location

Oncology Addition at the VA Hospital ■ Milwaukee, Wisconsin

December 21, 2017 ■ Terracon Project No. MR175338

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Existing

Improvements

The new addition will be constructed to the northeast of the main entrance to the hospital. The area of the proposed addition is located within an enclosed courtyard, and is surrounded by the hospital to the west, a large retaining wall to the south and east, and a one-story building to the north.

Current Ground

Cover Concrete paved.

Existing Topography

Based upon a provided site topographic plan, the area of the proposed improvement is relatively flat with existing surface grade ranging in elevation from 647 to 649 feet.

PROJECT DESCRIPTION

Our final understanding of the project conditions is as follows:

Project Description The project will consist of the construction of a new Oncology Addition at the Milwaukee VA hospital.

Proposed Structures

The addition will be a single-story structure having a footprint of about 5,000 square feet with typical slab on grade construction. The addition will house two linear accelerators that are relatively heavily loaded, and will be encased within 3-foot thick concrete walls.

Finished Floor Elevation Not provided, but anticipated to match the elevation of the existing hospital.

Maximum Loads

(assumed by Terracon)

Anticipated structural loads were not provided to us. We have assumed the following maximum loads:

■ Columns: 50 to 100 kips

■ Walls: 4 to 6 kips per linear foot maximum

■ Floor Slabs: 150 pounds per square foot maximum

Grading/Slopes We anticipate that minor grading (2 to 3 feet) may be needed to achieve the required subgrade elevations.

Below Grade Structures None anticipated

Free-Standing Retaining Walls

None anticipated

Below Grade Areas None anticipated

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GEOTECHNICAL CHARACTERIZATION

Subsurface Profile

We have developed a general characterization of the subsurface soil and groundwater conditions based upon our review of the data and our understanding of the geologic setting. The geotechnical characterization forms the basis of our geotechnical calculations and evaluation of site preparation, foundation options and pavement options. As noted in General Comments, the characterization is based upon widely spaced exploration points across the site, and variations are likely.

Subsurface conditions at the boring locations can be generalized as follows:

Stratum

Approximate Depth to Bottom of Stratum

(feet)

Material Description Consistency/Density

Surface 1

6 to 8 inched of concrete pavement over 3 to 5 inches of aggregate base

N/A

Fill: Lean clay with sand and gravel

Very stiff

Water Content: 16% to 23%

1A

8 to 11

Fill: upper 5 feet consists of crushed stone (2-inch minus) over lean clay with sand extending to 8 feet

SPT N-value: 13 to 18 bpf

2 17 to 20 Lean clay (CL) Very stiff to hard

Water Content: 11% to 20%

2A

16 Lean to Fat Clay (CL/CH) Medium-stiff to stiff

Water content: 22% to 31%

To boring termination depth of 20 feet in borings B-1 and B-2

Silt (ML) and clayey sand to sandy clay (SC/CL)

Medium-dense moist

1. Encountered only in borings B-1 and B-2

2. Encountered only in boring B-3

Conditions encountered at each boring location are indicated on the individual boring logs shown in the Exploration Results section and are attached to this report. Stratification boundaries on the boring logs represent the approximate location of changes in native soil types; in situ, the transition between materials may be gradual.

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Groundwater Conditions

The boreholes were observed while drilling and after completion for the presence and level of groundwater. Groundwater was not observed in any of the three soil borings while drilling, or for the short duration the borings remained open. However, this does not necessarily mean the borings terminated above groundwater, or the water levels summarized above are stable groundwater levels.

Due to the low permeability of the soils encountered in the borings, a relatively long period may be necessary for a groundwater level to develop and stabilize in a borehole. Long term observations in piezometers or observation wells sealed from the influence of surface water are often required to define groundwater levels in materials of this type.

Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff and other factors not evident at the time the borings were performed. Therefore, groundwater levels during construction or at other times in the life of the structure may be higher or lower than the levels indicated on the boring logs. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project.

GEOTECHNICAL OVERVIEW

The existing near surface, native and fill lean clay could become unstable with typical earthwork and construction traffic, especially after precipitation events. If possible, the grading should be performed during the warmer and drier time of the year. If grading is performed during the wetter months, an increased risk for possible undercutting and replacement of unstable subgrade will persist. Additional site preparation recommendations including subgrade improvement and fill placement are provided in the Site Preparation section.

The Shallow Foundations section addresses support of the building(s) bearing on native very stiff to hard lean clay, or engineered fill or lean concrete. It is our opinion that the structure foundations can be supported by typical spread foundations proportioned for a net allowable bearing pressure of 3,000 psf and bearing on the native, very stiff to hard lean clay soils encountered below 3.5 feet in borings B-1 and B-2, or on engineered soil fill or lean concrete extending to suitable native bearing soils.

However, boring B-3 encountered existing fill and unsuitable native material (i.e. fat clay) to a depth of approximately 16 feet. Within this zone of poor soils, undercutting or supplemental foundation support will be necessary.

For the undercut option, the Owner would be required to assume the risk of slightly greater than typical settlement associated with supporting the foundations on existing fill. In this case, we recommend a minimum undercut of three feet below the base of the footing The materials exposed at this depth should then be thoroughly observed and tested to confirm there are no

Responsive ■ Resourceful ■ Reliable 5 excessively loose or soft soils within the upper two to three feet of the subgrade. If present, these materials should also be removed. After thoroughly evaluating the exposed subgrade, granular engineered fill should be placed in uniform compacted lifts back up to the design footing bearing elevation. For footings founded on a minimum thickness of 3 feet of granular fill, a 3,000 psf bearing pressure may also be used. The purpose of the granular engineered fill is to distribute the foundation loads through the underlying granular fill layer so that the increase in pressure at the base of the fill is at 1,500 psf or less on the underlying soils. A 2V:1H stress distribution may be assumed in checking the required depth of undercut so that the 3,000 psf bearing pressure at the footing base is adequately reduced to the 1,500 psf bearing pressure at the base of the new fill. Lean concrete should not be used as backfill for the over-excavation, unless it extends completely through the fill and native fat clay to the competent lean clay below.

Alternatively, consideration could be given to improving unsuitable sub-grade in place with aggregate piers or directly supporting the proposed foundations on a series of helical piers extending below the existing fill and unsuitable native soils observed in boring B-3.

Recommendations for these two proprietary systems is described in the Specialty Foundations section.

The floor slabs for the proposed addition can be supported on native cohesive soils, newly placed engineered fill, or existing fill materials provided these soils appear firm under proofrolling as discussed in the Earthwork section. We recommend that a minimum 6-inch thick granular leveling course be placed directly below the slab to provide uniform support.

Support of foundations and floor slabs on or above existing fill materials is discussed in this report.

However, even with the recommended construction procedures, there is an inherent risk for the owner that compressible fill or unsuitable material within or buried by the fill will not be discovered.

This risk of unforeseen conditions cannot be eliminated without completely removing the existing fill, but can be reduced by following the recommendations contained in this report. To take advantage of the cost benefit of not removing the entire amount of undocumented fill, the owner must be willing to accept the risk associated with building over the undocumented fills following the recommended reworking of the material.

The General Comments section provides an understanding of the report limitations.

EARTHWORK

Earthwork will include removal of existing pavement, excavations and fill placement. The following sections provide recommendations for use in the preparation of specifications for the work.

Recommendations include critical quality criteria as necessary to render the site in the state

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Site Preparation

Prior to placing new fill, existing pavement material should be removed. Following stripping of surface materials and prior to placing new engineered fill, the exposed soils should be observed and tested by Terracon. A Terracon representative should observe proofrolling of the exposed soils. Proofrolling can be accomplished using a loaded tandem-axle dump truck with a gross weight of at least 25 tons, or similarly loaded equipment. Areas that display excessive deflection

(pumping) or rutting during proofroll operations should be improved by scarification/compaction, or by removal and replacement with engineered fill.

All existing utilities should also be properly abandoned and/or relocated. This should include removal of all poorly compacted trench backfill extending into the proposed building area. In addition, care should be taken by contractors to protect all existing improvements to remain, such as pavements and utilities. Excavations created by demolition and removal of existing features should be backfilled with engineered fill that is placed and compacted as recommended in this report.

Fill Material Types

It is expected that most of the inorganic cohesive site soils, with the limitations discussed in this report, could be considered for use as engineered fill for the project. Engineered fill for the project should meet the follow material property requirements:

Fill Type 1, 2

USCS Classification Acceptable Locations for Placement

Cohesive

CL

, CL/ML

, ML

(LL ≤ 45 and PI ≤ 20)

Adjacent to footings

Below/adjacent to floor slabs and pavement

Granular

GW, GP, GM, GC

SW, SP, SM, SC

Below/adjacent to footings, floor slabs, and pavement

Unsuitable

CL/CH

, CH

, MH

OL, OH

, PT

non-structural locations

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Fill Type 1, 2

USCS Classification Acceptable Locations for Placement

1. Engineered fill should consist of approved materials that are free of organic matter and debris. Frozen material should not be used, and fill should not be placed on a frozen subgrade. A sample of each material type should be submitted to Terracon for evaluation prior to use on this site.

2. Any organic materials, rock fragments larger than 3 inches, and other unsuitable materials should be removed prior to use as engineered fill.

3. Highly susceptible to frost; unstable when wet, are commonly used for pavement support with the knowledge that additional maintenance and/or shorter pavement life are likely

4. High plasticity. Not recommended beneath movement sensitive features such as foundations, floor slabs, or pavements.

Fill Compaction Requirements

Engineered fill should meet the following compaction requirements.

Maximum fill lift thickness

■ 9 inches or less in loose thickness when heavy, self-propelled compaction equipment is used

■ 4 to 6 inches or less in loose thickness when hand-guided equipment (i.e. jumping jack or plate compactor) is used

Minimum compaction requirements 1, 2, 3

■ 95% of the modified Proctor (ASTM Standard D-1557) maximum dry density below foundations; the compaction effort should extend laterally beyond the foundations at least

8 inches for every foot of fill placed below the foundation elevation

■ 92% below floor slabs

Moisture content range

■ within 2% below to 4% above the modified Proctor optimum moisture content at the time of placement and compaction

■ granular materials should be compacted within workable moisture levels

1. We recommend that engineered fill be tested for moisture content and compaction during placement. Should the results of the in-place density tests indicate the specified moisture or compaction limits have not been met, the area represented by the test should be reworked and retested as required until the specified moisture and compaction requirements are achieved.

2. If the granular material is a coarse sand, crushed limestone, or gravel, is of a uniform size, or has a low fines content, compaction comparison to relative density (ASTM D 4253 and D 4254) may be more appropriate. In this case, granular materials should be compacted to at least 60% and 65% of the maximum relative density for the 92% and 95% modified Proctor recommendations, respectively.

3. Specifically, moisture levels should be maintained to achieved compaction without bulking during placement or pumping when proofrolled.

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Utility Trench Backfill

For low permeability subgrades, utility trenches are a common source of water infiltration and migration. Utility trenches penetrating beneath the building should be effectively sealed to restrict water intrusion and flow through the trenches, which could migrate below the building. The trench should provide an effective trench plug that extends at least 5 feet from the face of the building exterior. The plug material should consist of cementitious flowable fill or low permeability clay.

The trench plug material should be placed to surround the utility line. If used, the clay trench plug material should be placed and compacted to comply with the water content and compaction recommendations for engineered fill stated previously in this report.

Grading and Drainage

All grades must provide effective drainage away from the building(s) during and after construction and should be maintained throughout the life of the structure. Water retained next to the building can result in soil movements greater than those discussed in this report. Greater movements can result in unacceptable differential floor slab and/or foundation movements, cracked slabs and walls, and roof leaks. The roof should have gutters/drains with downspouts that discharge onto splash blocks away from the building.

Exposed ground should be sloped from the building. Locally, flatter grades may be necessary to transition ADA access requirements for flatwork. After building construction and landscaping, final grades should be verified to document effective drainage has been achieved. Grades around the structure should also be periodically inspected and adjusted as necessary as part of the structure’s maintenance program. Where paving or flatwork abuts the structure a maintenance program should be established to effectively seal and maintain joints and prevent surface water infiltration.

Earthwork Construction Considerations

We recommend that a Terracon geotechnical engineer or qualified representative be retained during the construction phase of the project to observe earthwork and to perform necessary tests and observations during site stripping, subgrade preparation, placement and compaction of controlled compacted fills, backfilling of excavations, and just prior to construction of building floor slabs.

Care should be taken to avoid disturbance of prepared subgrades. Unstable subgrade conditions could develop during general construction operations, particularly if the soils are wetted and/or subjected to repetitive construction traffic. New fill compacted above optimum moisture content or that accumulates water during construction can also become disturbed under construction equipment. Construction traffic over the exposed subgrade should be avoided to the extent

Responsive ■ Resourceful ■ Reliable 9 practical. If the subgrade becomes saturated, desiccated, or disturbed, the affected materials should either be scarified and compacted or be removed and replaced.

As a minimum, excavations should be performed in accordance with OSHA 29 CFR, Part 1926, Subpart P, “Excavations” and its appendices, and in accordance with any applicable local, state, and federal safety regulations. Based upon the materials encountered in the soil borings, the fill soils are classified as Type “C” soil. OSHA recommends a maximum slope inclination of 1.5H:1V for Type C soil. The native very stiff to hard cohesive soils are classified as Type “B” soil. OSHA recommends a maximum slope inclination of 1H:1V for Type B soil. The contractor should be aware that slope height, slope inclination, and excavation depth should in no instance exceed those specified by these safety regulations. Flatter slopes than those dictated by these regulations may be required depending upon the soil conditions encountered and other external factors. These regulations are strictly enforced and if they are not followed, the owner, contractor, and/or earthwork and utility subcontractor could be liable and subject to substantial penalties.

Under no circumstances should the information provided in this report be interpreted to mean that

Terracon is responsible for construction site safety or the contractor’s activities. Construction site safety and excavation safety is the sole responsibility of the contractor who shall also be solely responsible for the means, methods, and sequencing of the construction operations.

We do not anticipate that the local groundwater table will be encountered in excavations for shallow spread foundations. However, minor amounts of seepage may be encountered from perched water conditions. If seepage is encountered, the contractor is responsible for employing appropriate dewatering methods to control seepage and facilitate construction. If needed, we anticipate that excavation dewatering can be accomplished with a typical sump pit and pump system, though the contractor should determine the required number of sumps and sump locations based on the amount of water entering the excavation. The pumps should be adequately filtered to prevent pumping of fines.

SHALLOW FOUNDATIONS

It is our opinion that the structure foundations can be supported by typical spread foundations proportioned for a net allowable bearing pressure of 3,000 psf bearing on the native, very stiff to hard lean clay soils encountered below 3.5 feet in borings B-1 and B-2, or on engineered soil fill or lean concrete extending to suitable native bearing soils.

However, boring B-3 encountered existing fill and unsuitable native material (i.e. fat clay) to a depth of approximately 16 feet. Within this zone of poor soils, undercutting or supplemental foundation support will be necessary.

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For the undercut option, the Owner would be required to assume the risk of slightly greater than typical settlement associated with supporting the foundations on existing fill. In this case, we recommend a minimum undercut of three feet below the base of the footing. The materials exposed at this depth should then be thoroughly observed and tested to confirm there are no excessively loose or soft soils within the upper two to three feet of the subgrade. If present, these materials should also be removed. After thoroughly evaluating the exposed subgrade, granular engineered fill should be placed in uniform compacted lifts back up to the design footing bearing elevation. For footings founded on a minimum thickness of 3 feet of granular fill, a 3,000 psf bearing pressure may also be used. The purpose of the granular engineered fill is to distribute the foundation loads through the underlying granular fill layer so that the increase in pressure at the base of the fill is at 1,500 psf or less on the underlying soils. A 2V:1H stress distribution may be assumed in checking the required depth of undercut so that the 3,000 psf bearing pressure at the footing base is adequately reduced to the 1,500 psf bearing pressure at the base of the new fill. Lean concrete should not be used as backfill for the over-excavation, unless it extends completely through the fill and native fat clay to the competent lean clay below.

Alternatively, consideration could be given to improving unsuitable sub-grade in place with aggregate piers or directly supporting the proposed foundations on a series of helical piers extending below the existing fill and unsuitable native soils observed in boring B-3.

Recommendations for these two proprietary systems is described in the Specialty Foundations section.

Design Parameters – Compressive Loads

Maximum Net Allowable Bearing pressure

3,000 psf

Minimum Foundation Dimensions Columns: 30 inches

Continuous: 18 inches

Ultimate Coefficient of Sliding Friction

0.35 (cohesive material)

0.45 (granular material)

Minimum Embedment below

Finished Grade

4 feet

Estimated Total Settlement from Structural

Loads 2, 5

Less than about 1 inch (footings bearing directly on suitable native soils or engineered fill/lean concrete extending to suitable native soils)

Up to 1¼ inches (footings bearing on a minimum 3-foot thickness of granular engineered fill over existing fill or unsuitable native soils)

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Estimated Differential Settlement

About 2/3 of total settlement

1. The recommended net allowable bearing pressure is the pressure in excess of the minimum surrounding overburden pressure at the footing base elevation. This pressure assumes that any lower strength soils, existing fill, or other unsuitable materials, if encountered, will be undercut and replaced with engineered fill or lean concrete. The design bearing pressure will be dependent on the final building location, elevation, and structural loading. Foundations proportioned for a net allowable soil bearing pressure of 3,000 psf should be supported on native clay soils having a minimum unconfined compressive strength of 1.5 tsf. If soils at the proposed bearing elevation do not meet this criteria or are found to be existing fill soils, the footing excavation should be undercut and backfilled with compacted granular engineered fill, as detailed in the preceding paragraphs.

2. Assumed final site grade is not raised more than 2 feet from existing conditions.

3. Can be used to compute sliding resistance where foundations are placed on suitable soil/materials. Should be neglected for foundations subject to net uplift conditions.

4. Embedment necessary to minimize the effects of frost and/or seasonal water content variations. For sloping ground, maintain depth below the lowest adjacent exterior grade within 5 horizontal feet of the structure.

5. Foundation settlements will depend upon the variations within the subsurface soil profile, the structural loading conditions, the embedment depth of the footings, the thickness of engineered fill, and the quality of the earthwork operations and footing construction, frequent control joints should be provided for walls.

Uplift resistance of spread footings can be developed from the effective weight of the footing and the overlying soils. The maximum allowable uplift capacity should be taken as a sum of the effective weight of soil plus the dead weight of the foundation, divided by an appropriate factor of safety. A maximum total unit weight of 120 pcf should be used for the backfill.

Foundation Construction Considerations

The soils at the base of each foundation excavation should be observed and tested by Terracon to evaluate whether they meet the requirements for suitable bearing soils as defined in this report.

The excavations should be probed or otherwise sampled at regular intervals.

The base of each foundation excavation should be free of water and loose materials prior to placing concrete. Concrete should be placed as soon after excavating as possible to reduce bearing soil disturbance. If the soils at the bearing level become excessively dry, disturbed, saturated, or frozen, the affected soil should be removed prior to placing concrete. Placement of a lean concrete mud-mat over the bearing soils should be considered if the excavations must remain open overnight or for an extended period of time.

Footings should bear directly on tested and approved native lean clay soils or on new engineered granular fill extending a minimum of three feet below the proposed footing bearing elevation. If unsuitable soils are encountered at the design footing level, the footing excavations should be extended deeper to reach suitable bearing materials. Footings may also bear on lean concrete, assuming that the lean concrete extends below any fill or fat clay to the native, very stiff to hard lean clay.

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Where engineered fill will be placed to support the footings, the excavations should be widened at least 8 inches beyond each footing edge for every foot of new fill placed below the design footing base elevation. The over-excavated depth should then be backfilled up to the foundation base elevation with an approved fill material that is placed in lifts and compacted to at least 95% of the modified Proctor maximum dry density. We recommend that backfill materials consist of those materials identified in the Earthwork section. The recommended extents of the over-excavation and backfill procedure are illustrated in the following figures. Lean concrete is only recommended to be used in undercuts that extend down to native very stiff to hard lean clay, as it does not serve the purpose of distributing the foundation loads with depth.

SPECIALTY FOUNDATIONS

If slightly larger than typical settlement of foundations cannot be accepted in the areas where existing fill and/or unsuitable soils extend to a substantial depth (i.e. boring B-3), the footings could also be supported on shallow foundations bearing over a system of aggregate piers or helical piers. A discussion regarding these two types of foundation support are discussed in the following sections.

Aggregate Piers

Aggregate piers are an intermediate design-build soil reinforcement system that is commonly used to support structures as an alternative to soil over-excavation. The system allows the use of conventional spread footings or large mat slabs bearing at typical frost depth, and typically provides settlement control to within 1-inch or less.

Aggregate piers are installed by densifying lifts of aggregate into a cavity that is created by either drilling or displacement methods. The use of the displacement or drilling method is at the discretion of a design-build aggregate pier contractor. Densification takes place with a high-

Responsive ■ Resourceful ■ Reliable 13 energy beveled tamper or vibratory probe that both densifies the aggregate and forces the aggregate laterally into the sidewalls of the hole. This action increases the lateral stress in surrounding soil, thereby further stiffening the stabilized composite soil mass. The result of aggregate pier installation is a significant strengthening and stiffening of subsurface soils that then support the mat slabs or conventional shallow spread footings. We recommend that the individual aggregate pier elements extend through the existing fill and fat clay soils encountered in the upper

16 feet of the soil profile around boring B-3 and terminate in the underlying very stiff to hard native clay.

Aggregate pier designs are based on a two-layer settlement analysis. Settlements within the

“upper zone” (zone of soil that is reinforced with aggregate pier elements) are computed using a weighted modulus method that accounts for the stiffness of the aggregate pier elements, the stiffness of the matrix soil, and the area coverage of aggregate pier elements below supported footings. Settlements within the “lower zone” (zone of soils beneath the upper zone which receives lower intensity footing stresses) are computed using conventional geotechnical settlement methods.

After reinforcement with the aggregate pier system, the building foundations may be designed as a conventional spread footing, sized for an allowable bearing pressure on the order of 3,000 to

4,000 psf. The above estimate should be considered preliminary and is based on our past experience with aggregate pier systems in similar soils. The allowable bearing pressure will vary depending on the size, installation methods and spacing of the individual piers. Thus, the actual allowable bearing pressure used in footing design should be developed by an experienced design-build aggregate pier contractor based on the actual pier geometry to be used for construction. We are able to provide a list of qualified aggregate pier design-build contractors at your request.

If the aggregate pier system is selected, quality assurance testing should be performed during installation, including documentation of the soil conditions encountered, the shaft lengths, amount of aggregate used, and tests on the completed aggregate pier elements. Terracon can provide these services if requested.

Helical Piers

Alternatively, helical piers could be used to directly support the foundations. Helical piers function as an intermediate design-build foundation system and would distribute the building loads in end bearing to a competent bearing strata below the existing fill and underlying soft to medium-stiff lean clay. Grade beams could then be constructed above the helical piers to support the column and wall loads for the proposed structure. We are able to provide a list of qualified helical pier design-build contractors at your request.

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Helical piers consist of helical-shaped circular steel plates welded to a steel bar at a pre-determined spacing. The piers are turned into the ground using standard truck or trailer mounted augering equipment until suitable bearing strata is reached. Threaded extension bars can be connected to the lead anchor bar in order to reach greater depths. An eye or suitable termination device is attached to the top end of the final extension bar to provide an attachment point for the axial load. Depending on the soil conditions, helical piers can be a cost effective means of providing both tension and compression anchorage for foundations subjected to uplift and overturning loads.

Based on the subsurface profile encountered in the borings, we recommend that the helical pier foundations be designed to bear within the native very stiff to hard lean clay soils encountered below 16 feet in boring B-3. The design capacity should be determined by the helical pier installer based on the anticipated soil profile and torque to install the helices. The designer should check that the manufacturer rated structural capacity of the individual helices and anchor bar is not exceeded. Additionally, the designer should check that the installation torque required to penetrate a specific soil stratum does not exceed the manufacturer recommended installation torque for a given helix and anchor bar type.

Helical pier systems can be installed with one or multiple helices. The bearing capacity of an individual foundation pier is equal to the sum of the capacities of the individual helices. The individual helix capacity is estimated by calculating the unit bearing capacity of the soil and applying it to the individual helix areas. Friction along the lead bar should not be used when determining the ultimate capacity of the foundation pier. Friction or adhesion on the extension bars may be included if the bars are round and at least 3.5 inches in diameter. Friction may be used with square bar extensions, provided the shaft length is grouted. The helices should be spaced far enough apart to avoid overlapping of the stress zones at each helix. Most helical pier manufacturers produce piers with a minimum three-helix-diameter spacing, which has historically been sufficient to prevent one helix from significantly affecting the performance of another. A maximum of six helices is recommended for an individual anchor.

We recommend that the top helix project a minimum distance of three helix diameters into the prescribed bearing layer. A minimum factor of safety of 2.0 should be used to calculate the allowable bearing resistances for the individual helices, assuming that the actual capacities of the anchors will be verified in the field using torque measurement methods or load tests.

The minimum center to center spacing between individual helical piers should not be less than three times the maximum helix diameter, or three feet, whichever is greater, in order to avoid group effects. The anchor bars should also be checked for buckling.

Exterior pier caps or grade beams should be supported at a minimum depth of 4 feet below grade for frost considerations. Interior pier caps or grade beams in heated structures can be supported

Responsive ■ Resourceful ■ Reliable 15 above frost depth. The helical pier connections to the grade beam or pier cap should be designed by a licensed Structural Engineer in the State of Illinois.

FLOOR SLABS

The floor slabs for the proposed addition can be supported on native cohesive soils, newly placed engineered fill, or existing fill materials provided these soils appear firm under proofrolling as discussed in the Earthwork section. We recommend that a minimum 6-inch thick granular leveling course be placed directly below the slab to provide uniform support.

Design parameters for floor slabs assume the requirements for Earthwork have been followed.

Specific attention should be given to positive drainage away from the structure and. positive drainage of the aggregate base out from beneath the floor slab. Additional floor slab recommendations are provided below

Floor Slab Design Parameters

Floor Slab Support

Minimum 6 inches of free-draining (less than 3% passing the U.S. No. 200 sieve) crushed aggregate compacted to at least 95% of ASTM D 698

Estimated Modulus of

Subgrade Reaction

110 pounds per square inch per inch (psi/in) for point loads

1. Floor slabs should be structurally independent of building footings or walls to reduce the possibility of floor slab cracking caused by differential movements between the slab and foundation.

2. The recommended modulus value is based on a 12-inch square plate. The modulus value used in design should be adjusted based on the actual size of the floor slab according to the Naval Facilities Engineering

Design Manual 7.2, page 7.2-155, Table 4.

The use of a vapor retarder should be considered beneath concrete slabs on grade covered with wood, tile, carpet, or other moisture sensitive or impervious coverings, or when the slab will support equipment sensitive to moisture. When conditions warrant the use of a vapor retarder, the slab designer should refer to ACI 302 and/or ACI 360 for procedures and cautions regarding the use and placement of a vapor retarder.

Saw-cut control joints should be placed in the slab to help control the location and extent of cracking. For additional recommendations refer to the ACI Design Manual. Joints or cracks should be sealed with a water-proof, non-extruding compressible compound specifically recommended for heavy duty concrete pavement and wet environments.

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Settlement of floor slabs supported on existing fill materials cannot be accurately predicted, but could be larger than normal and result in some cracking. The floor slab can be stiffened by adding steel reinforcement, grade beams and/or post-tensioned elements.

Floor Slab Construction Considerations

On most project sites, the site grading is generally accomplished early in the construction phase.

However, as construction proceeds, the subgrade may be disturbed by utility excavations, construction traffic, desiccation, rainfall, etc. As a result, corrective action may be required prior to placement of the granular leveling course and concrete.

The condition of the floor slab subgrades should be reviewed and tested immediately prior to placement of the granular leveling course and construction of the slabs. Particular attention should be paid to high traffic areas that were rutted and disturbed earlier and to areas where backfilled trenches are located. Areas where unsuitable conditions are located should be repaired by removing the affected material and replacing it with engineered soil fill.

SEISMIC CONSIDERATIONS

The seismic design requirements for buildings and other structures are based on Seismic Design

Category. Site Classification is required to determine the Seismic Design Category for a structure.

The Site Classification is based on the upper 100 feet of the site profile defined by a weighted average value of either shear wave velocity, standard penetration resistance, or undrained shear strength in accordance with Section 20.4 of ASCE 7-10.

Description Value

2012 International Building Code Site Classification (IBC)

D

Site Latitude 43.0213

Site Longitude -87.9752

SDS Spectral Acceleration for a Short Period

0.093g

SD1 Spectral Acceleration for a 1-Second Period

0.075g

1. Seismic site classification in general accordance with the 2012 International Building Code, which refers to

ASCE 7-10.

2. The 2012 International Building Code (IBC) uses a site profile extending to a depth of 100 feet for seismic site classification. Borings at this site were extended to a maximum depth of 20 feet. The site properties below the boring depth to 100 feet were estimated based on our experience and knowledge of geologic conditions of the general area. Additional deeper borings or geophysical testing may be performed to confirm the conditions below the current boring depth.

3. These values were obtained using online seismic design maps and tools provided by the USGS

(http://earthquake.usgs.gov/hazards/designmaps/).

http://earthquake.usgs.gov/hazards/designmaps/

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GENERAL COMMENTS

Our services are conducted with the understanding of the project as described in the proposal, and will incorporate collaboration with the design team as we complete our services to verify assumptions. Revision of our understanding to reflect actual conditions important to our services will be based on these verifications and will be reflected in the final report. The design team should collaborate with Terracon to confirm these assumptions and to prepare the final design plans and specifications. This facilitates the incorporation of our opinions related to implementation of our geotechnical recommendations. Any information conveyed prior to the final report is for informational purposes only and should not be considered or used for decision-making purposes.

Our analysis and opinions are based upon our understanding of the geotechnical conditions in the area, the data obtained from our site exploration and from our understanding of the project.

Variations will occur between exploration point locations, across the site, or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after construction. Terracon should be retained as the Geotechnical

Engineer, where noted in the final report, to provide observation and testing services during grading, excavation, foundation construction and other earth-related construction phases of the project. If variations appear, we can provide further evaluation and supplemental recommendations. If variations are noted in the absence of our observation and testing services on-site, we should be immediately notified so that we can provide evaluation and supplemental recommendations.

Support of foundations and floor slabs on or above existing fill materials is discussed in this report.

However, even with the recommended construction procedures, there is an inherent risk for the owner that compressible fill or unsuitable material within or buried by the fill will not be discovered.

This risk of unforeseen conditions cannot be eliminated without completely removing the existing fill, but can be reduced by following the recommendations contained in this report. To take advantage of the cost benefit of not removing the entire amount of undocumented fill, the owner must be willing to accept the risk associated with building over the undocumented fills following the recommended reworking of the material.

Our scope of services does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken.

Our services and any correspondence are intended for the sole benefit and exclusive use of our client for specific application to the project discussed and are accomplished in accordance with generally accepted geotechnical engineering practices with no third party beneficiaries intended.

Any third party access to services or correspondence is solely for information purposes only.

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Reliance upon the services and any work product is limited to our client, and is not intended for third parties. Any use or reliance of the provided information by third parties is done solely at their own risk. No warranties, either express or implied, are intended or made.

Site characteristics as provided are for design purposes and not to estimate excavation cost. Any use of our report in that regard is done at the sole risk of the excavating cost estimator as there may be variations on the site that are not apparent in the data that could significantly impact excavation cost. Any parties charged with estimating excavation costs should seek their own site characterization for specific purposes to obtain the specific level of detail necessary for costing.

Site safety, and cost estimating including, excavation support, and dewatering requirements/design are the responsibility of others. If changes in the nature, design, or location of the project are planned, our conclusions and recommendations shall not be considered valid unless we review the changes and either verify or modify our conclusions in writing.

ATTACHM ENTS

ATTACHMENTS

MISC APPENDIX 1

Field Exploration

Boring Layout and Elevations: A Terracon field engineer provided the boring layout.

Coordinates of the borings were estimated from our GIS system based on the boring layout by the Terracon field engineer. The ground surface elevations of the boring locations were estimated by a site topographic survey plan which was provided to Terracon.

Subsurface Exploration Procedures: We advanced the borings with truck-mounted rotary drill rig using continuous flight hollow-stem augers. Four samples were obtained in the upper 10 feet of each boring and at intervals of 5 feet thereafter. In the split-barrel sampling procedure, a standard

2-inch outer diameter split-barrel sampling spoon is driven into the ground by a 140-pound automatic hammer falling a distance of 30 inches. The number of blows required to advance the sampling spoon the last 12 inches of a normal 18-inch penetration is recorded as the Standard Penetration

Test (SPT) resistance value. The SPT resistance values, also referred to as N-values, are indicated on the boring logs at the test depths. We observed and recorded groundwater levels during drilling and sampling. For safety purposes, all borings were backfilled with bentonite chips after their completion. The surface of each boring was patched with concrete.

The sampling depths, penetration distances, and other sampling information were recorded on the field boring logs. The samples were placed in appropriate containers and taken to our soil laboratory for testing and classification by a geotechnical engineer. Our exploration team prepared field boring logs as part of the drilling operations. These field logs included visual classifications of the materials encountered during drilling and our interpretation of the subsurface conditions between samples. Final boring logs were prepared from the field logs. The final boring logs represent the geotechnical engineer's interpretation of the field logs and include modifications based on observations and tests of the samples in our laboratory.

Laboratory Testing

The project engineer reviewed the field data and assigned various laboratory tests to better understand the engineering properties of the various soil strata as necessary for this project.

Procedural standards noted below are for reference to methodology in general. In some cases, variations to methods were applied because of local practice or professional judgment. Standards noted below include reference to other, related standards. Such references are not necessarily applicable to describe the specific test performed.

■ ASTM D2216 Standard Test Methods for Laboratory Determination of Water (Moisture)

Content of Soil and Rock by Mass

■ ASTM D4318 Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of

Soils

■ ASTM D2166/D2166M Standard Test Method for Unconfined Compressive Strength of

Cohesive Soil

The laboratory testing program included examination of soil samples by an engineer. Based on the material’s texture and plasticity, we describe and classify the soil samples in accordance with the Unified Soil Classification System.

SITE LOC ATION AND EXPLOR ATION PLAN S

SITE LOCATION AND EXPLORATION PLANS

SITE LOCATION

Milwaukee VA Oncology Suite ■ Milwaukee, WI

TOPOGRAPHIC MAP IMAGE COURTESY OF THE U.S. GEOLOGICAL SURVEY

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