AS06_GSI Engineering Geo Report 166078 10-03-2016 - Steam Chilled Water Pipin..pdf

Geotechnical-Engineering Report

Geotechnical Services Are Performed for Specific Purposes, Persons, and Projects Geotechnical engineers structure their services to meet the specific needs of their clients. A geotechnical-engineering study conducted for a civil engineer may not fulfill the needs of a constructor — a construction contractor — or even another civil engineer. Because each geotechnical- engineering study is unique, each geotechnical-engineering report is unique, prepared solely for the client. No one except you should rely on this geotechnical-engineering report without first conferring with the geotechnical engineer who prepared it. And no one

— not even you — should apply this report for any purpose or project except the one originally contemplated.

Read the Full Report Serious problems have occurred because those relying on a geotechnical-engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only.

Geotechnical Engineers Base Each Report on a Unique Set of Project-Specific Factors Geotechnical engineers consider many unique, project-specific factors when establishing the scope of a study. Typical factors include: the client’s goals, objectives, and risk-management preferences; the general nature of the structure involved, its size, and configuration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless the geotechnical engineer who conducted the study specifically indicates otherwise, do not rely on a geotechnical-engineering report that was:

• not prepared for you;

• not prepared for your project;

• not prepared for the specific site explored; or

• completed before important project changes were made.

Typical changes that can erode the reliability of an existing geotechnical-engineering report include those that affect:

• the function of the proposed structure, as when it’s changed from a parking garage to an office building, or from a light-industrial plant to a refrigerated warehouse;

• the elevation, configuration, location, orientation, or weight of the proposed structure;

• the composition of the design team; or

• project ownership.

As a general rule, always inform your geotechnical engineer of project changes—even minor ones—and request an assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed.

Subsurface Conditions Can Change A geotechnical-engineering report is based on conditions that existed at the time the geotechnical engineer performed the study. Do not rely on a geotechnical-engineering report whose adequacy may have been affected by: the passage of time;

man-made events, such as construction on or adjacent to the site; or natural events, such as floods, droughts, earthquakes, or groundwater fluctuations. Contact the geotechnical engineer before applying this report to determine if it is still reliable. A minor amount of additional testing or analysis could prevent major problems.

Most Geotechnical Findings Are Professional Opinions Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. Geotechnical engineers review field and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ — sometimes significantly — from those indicated in your report. Retaining the geotechnical engineer who developed your report to provide geotechnical-construction observation is the most effective method of managing the risks associated with unanticipated conditions.

A Report’s Recommendations Are Not Final Do not overrely on the confirmation-dependent recommendations included in your report. Confirmation-dependent recommendations are not final, because geotechnical engineers develop them principally from judgment and opinion. Geotechnical engineers can finalize their recommendations only by observing actual subsurface conditions revealed during construction. The geotechnical engineer who developed your report cannot assume responsibility or liability for the report’s confirmation-dependent recommendations if that engineer does not perform the geotechnical-construction observation required to confirm the recommendations’ applicability.

A Geotechnical-Engineering Report Is Subject to Misinterpretation Other design-team members’ misinterpretation of geotechnical-engineering reports has resulted in costly

Important Information about This

Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.

While you cannot eliminate all such risks, you can manage them. The following information is provided to help.

problems. Confront that risk by having your geo technical engineer confer with appropriate members of the design team after submitting the report. Also retain your geotechnical engineer to review pertinent elements of the design team’s plans and specifications. Constructors can also misinterpret a geotechnical-engineering report. Confront that risk by having your geotechnical engineer participate in prebid and preconstruction conferences, and by providing geotechnical construction observation.

Do Not Redraw the Engineer’s Logs Geotechnical engineers prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical-engineering report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognize that separating logs from the report can elevate risk.

Give Constructors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can make constructors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation.

To help prevent costly problems, give constructors the complete geotechnical-engineering report, but preface it with a clearly written letter of transmittal. In that letter, advise constructors that the report was not prepared for purposes of bid development and that the report’s accuracy is limited;

encourage them to confer with the geotechnical engineer who prepared the report (a modest fee may be required) and/ or to conduct additional study to obtain the specific types of information they need or prefer. A prebid conference can also be valuable. Be sure constructors have sufficient time to perform additional study. Only then might you be in a position to give constructors the best information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions.

Read Responsibility Provisions Closely Some clients, design professionals, and constructors fail to recognize that geotechnical engineering is far less exact than other engineering disciplines. This lack of understanding has created unrealistic expectations that have led to disappointments, claims, and disputes. To help reduce the risk of such outcomes, geotechnical engineers commonly include a variety of explanatory provisions in their reports. Sometimes labeled “limitations,” many of these provisions indicate where geotechnical engineers’ responsibilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly.

Environmental Concerns Are Not Covered The equipment, techniques, and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical study. For that reason, a geotechnical-engineering report does not usually relate any environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated environmental problems have led to numerous project failures. If you have not yet obtained your own environmental information, ask your geotechnical consultant for risk-management guidance. Do not rely on an environmental report prepared for someone else.

Obtain Professional Assistance To Deal with Mold Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts of mold from growing on indoor surfaces.

To be effective, all such strategies should be devised for the express purpose of mold prevention, integrated into a comprehensive plan, and executed with diligent oversight by a professional mold-prevention consultant. Because just a small amount of water or moisture can lead to the development of severe mold infestations, many mold- prevention strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of the geotechnical- engineering study whose findings are conveyed in this report, the geotechnical engineer in charge of this project is not a mold prevention consultant;

none of the services performed in connection with the geotechnical engineer’s study were designed or conducted for the purpose of mold prevention. Proper implementation of the recommendations conveyed in this report will not of itself be sufficient to prevent mold from growing in or on the structure involved.

Rely, on Your GBC-Member Geotechnical Engineer for Additional Assistance Membership in the Geotechnical Business Council of the Geoprofessional Business Association exposes geotechnical engineers to a wide array of risk-confrontation techniques that can be of genuine benefit for everyone involved with a construction project. Confer with you GBC-Member geotechnical engineer for more information.

8811 Colesville Road/Suite G106, Silver Spring, MD 20910 Telephone: 301/565-2733 Facsimile: 301/589-2017 e-mail: info@geoprofessional.org www.geoprofessional.org

Copyright 2015 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, or its contents, in whole or in part, by any means whatsoever, is strictly prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document as a complement to or as an element of a geotechnical-engineering report. Any other firm, individual, or other entity that so uses this document without being a GBA member could be commiting negligent or intentional (fraudulent) misrepresentation.

GSI

TABLE OF CONTENTS

Page No.

1. INTRODUCTION ................................................................................................................. 1-1

1.1 General .................................................................................................................. 1-1

1.2 Project Description ................................................................................................. 1-1

2. FIELD EXPLORATION ....................................................................................................... 2-1

3. SITE CONDITIONS ............................................................................................................. 3-1

3.1 Regional Geology .................................................................................................. 3-1

3.2 Surface Conditions ................................................................................................. 3-1

3.3 Subsurface Conditions ........................................................................................... 3-1

3.4 Groundwater Conditions ........................................................................................ 3-2

3.5 Soil Chemical Properties ........................................................................................ 3-3

4. LABORATORY TESTING ................................................................................................... 4-1

5. CONCLUSIONS AND RECOMMENDATIONS ................................................................... 5-1

5.1 General Geotechnical Considerations .................................................................... 5-1

5.2 Earthwork .............................................................................................................. 5-1

5.2.1 Site Preparation ....................................................................................... 5-1

5.2.2 Engineered Structural Fill ........................................................................ 5-1

5.2.3 Compaction of Engineered Structural Fills ............................................... 5-1

5.2.4 Utility Trench Backfill ............................................................................... 5-2

5.2.5 Correction of Unsuitable Foundation Soils ............................................... 5-2

5.2.6 Excavation Slopes ................................................................................... 5-3

5.3 Precast Box Conduits ............................................................................................ 5-4

5.4 Lateral Earth Pressures ......................................................................................... 5-4

5.5 Construction Considerations .................................................................................. 5-5

5.6 Construction Observation and Quality Assurance .................................................. 5-5

6. CLOSING REMARKS AND LIMITATIONS ......................................................................... 6-1

APPENDICES

Appendix A - General Vicinity Map Boring Location Plan

Appendix B - Boring Logs Key to Symbols Legend & Nomenclature Unified Soil Classification System (USCS)

Appendix C - Field & Laboratory Test Results

VAMC DOM Steam and Chilled Water Piping Des Moines, Iowa

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1. INTRODUCTION

1.1 General

This report summarizes the findings of our geotechnical exploration for the proposed steam and chilled water lines located at the Veterans Administration Central Iowa Health Care System hospital in Des Moines, Iowa. The scope of work was outlined in our proposal dated July 25, 2016. Mr. Paul

Dahlberg AIA, Project Manager at Anderson Engineering of Minnesota, LLC, authorized this exploration on August 10, 2016.

The purpose of this geotechnical study is to explore the subsurface conditions at the proposed site with exploratory borings, evaluate the engineering properties of the subsurface materials with appropriate field and laboratory tests, and perform engineering analyses for developing design and construction recommendations for the proposed project.

1.2 Project Description

We understand the development will consist of DOM steam and chilled water lines. We understand the steam line will be housed in a continuous precast concrete box conduit with 5 precast vault structures to support expansion loops. The steam line encasement will be founded between 5 to 6 feet below site grade, while the expansion loop vaults will be founded approximately 10 feet below site grade. The chilled water line will be buried next to the precast box conduit.

Based on the plan and profile provided with the RFP, we understand that the ground surface elevation along the length of the line varies between approximately 909 feet and 922 feet. We understand the depths of the proposed structures described above will follow the existing ground surface elevation.

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2. FIELD EXPLORATION

We drilled four borings for this geotechnical exploration on September 10, 2016 with a Mobile B-57 truck-mounted drilling rig using 4-inch diameter continuous flight augers. We drilled four borings near the vault locations to a depth of approximately 15 feet below the site grade at the time of our exploration.

We selected boring locations based on a preliminary site sketch provided by Mr. Dahlberg on July

11, 2016. GSI personnel established field locations by measuring distances from reference points shown on this preliminary site plan. Locations of the borings in relation to existing and proposed features are indicated on the Boring Location Plan included in Appendix A.

We interpolated ground surface elevations using a preliminary site plan provided by Mr. Dahlberg.

The ground surface elevations at the borings are shown on the boring logs included in Appendix B.

The locations and elevations of the borings should be considered accurate only to the degree implied by the methods used in their determination.

Our drill crew obtained soil samples at the intervals shown on the boring logs in Appendix B.

Recovered samples were sealed in plastic containers, labeled, and protected for transportation to the laboratory for further examination, testing, and classification.

We obtained split-barrel samples (designated “Split Spoon” or “S” samples) while performing

Standard Penetration Tests (SPT) with a 1-3/8 inch I.D. thick-walled sampler, driven using an automatic hammer in general accordance with ASTM D1586, “Penetration Test and Split-Barrel

Sampling of Soils.” The “N” value, reported in blows per foot (bpf), equals the number of blows required to drive the sampler through the last 12 inches of the 18-inch sample interval using a 140-pound hammer falling 30 inches.

Our drilling personnel prepared field boring logs during drilling operations. These field logs report drilling and sampling methods, sampling intervals, groundwater measurements and the subsurface conditions we encountered. At the conclusion of drilling, our drill crew made groundwater measurements and backfilled the borings in accordance with Iowa state regulations.

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3. SITE CONDITIONS

3.1 Regional Geology

The project site is located near the southern edge of the geomorphic region referred to as the ʺDes

Moines Glacial Lobe.” This landform region was formed by extensive glacial activity including erosion, reworking, and deposition. Typically, the predominant surficial sediment is glacial drift deposited by the Wisconsinan glacier. Glacial soils commonly encountered within approximately

15 feet of ground surface are classified as supraglacial sediments. The supraglacial materials are generally variable and can be stratified in composition consisting of very silty sandy clay interbedded with silt and sand seams, layers, and extensive pockets throughout. In contrast, the underlying subglacial soils, which were deposited beneath the glacial ice as it advanced, tend to be a more homogeneous composition of silty sandy clay materials.

3.2 Surface Conditions

At the time of our exploration, boring B-1 was located in the asphalt parking lot west of Volunteer

Drive. Borings B-2 and B-3 were located in a grass lawn with trees, bordered on the south by the parking lot described above and on the north by parking spaces along Amvet Avenue, and on the west by a second parking lot. Boring B-4 was performed near the north boundary of the asphalt parking north of Amvet Avenue.

3.3 Subsurface Conditions

Although we observed some variability, the subsurface materials we encountered within the depths of exploration generally comprised lean clay and poorly graded gravel with sand fill overlying lean clay with varying amounts of sand or clayey sand. General descriptions of the strata we encountered are presented below, while more detailed subsurface information is presented on the boring logs located in Appendix B. Please note that the indicated depths are relative to the site grade at the time of our exploration.

Stratum 1

We encountered fill materials comprising lean clay and poorly graded gravel with sand in borings B-

1, B-2 and B-4 beneath approximately 6 inches of topsoil or asphalt pavement and extending to a depth of approximately 2.5 feet. This material was generally described as brown to dark brown or grayish brown and dry to slightly moist. We measured Standard Penetration Test (SPT) N-values

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between 6 and 16 blows per foot (bpf), indicating the lean clay or poorly graded gravel with sand is in a stiff or loose condition.

Stratum 2

We encountered lean clay with varying amounts of sand or clayey sand in all of our borings beneath the surficial fill materials in borings B-1, B-2 and B-4 and beneath 6 inches of topsoil in boring B-3 and extending to a depth of approximately 5 feet in boring B-1 and extending to the termination depth of our other borings at a depth of approximately 15 feet. This material was generally described as brown to dark brown, yellowish brown, gray or grayish brown. We measured SPT N-values between

7 and 24 bpf, indicating the lean clay with varying amounts of sand is in a medium stiff to very stiff condition.

Stratum 3

We encountered an interbedded layer of clayey sand in boring B-1 at a depth of 5 feet and extending to a depth of 13.5 feet, where we then encountered a layer of lean clay like that described above.

The lean clay extended to the termination depth of the boring at approximately 15 feet. The clayey sand was generally described as brown, yellowish brown or gray and moist. We measured SPT N-values of 7 and 9 bpf, indicating the clayey sand is in a loose condition.

3.4 Groundwater Conditions

Our drill crew made water level observations during drilling and after completion of the borings to evaluate groundwater conditions. We observed groundwater in boring B-4 as indicated on the boring log at a depth of approximately 13 feet below site grade. We did not encounter groundwater in any of our other borings.

The groundwater conditions we observed during our exploration program should not be construed to represent an absolute or permanent condition. Uncertainty is involved with short-term water level observations in boreholes.

In addition to the water levels indicated above, the slow percolation rate of the on-site clays can cause water to pond or become perched for extended time periods. The clay in this vicinity can also contain thin sand lenses that can transport water laterally. Excavations that encounter perched water or sand seams may flood and require dewatering.

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The free ground water surface or ground water table within unconfined aquifers is generally a subdued reflection of surface topography. Water generally flows downward from upland positions

(recharge zones) to low lying areas or surface water bodies (discharge zones). As such, the groundwater level and the amount and level of any perched water on the site may be expected to fluctuate with variations in precipitation, site grading, drainage and adjacent land use. Long-term monitoring utilizing piezometers or observation wells is required to evaluate the potential range of groundwater conditions.

3.5 Soil Chemical Properties

We selected four soil samples between 5 and 10 feet of the site for chemical analyses pertaining to soil corrosivity to steel and concrete. The results of these analyses are summarized below and a copy of the analytical laboratory report is included in Appendix C.

Table 3.5-1: Chemical Analyses

Boring

No.

Sample

No.

Depth pH

Chloride

(mg/kg)

Sulfate

(mg/kg)

B-1 S-4 8.5-10.0 8.0 ND 290

B-2 S-3 5.0-6.5 7.9 ND 382

B-3 S-3 5.0-6.5 8.5 ND ND

B-4 S-4 8.5-10.0 8.4 ND ND

Please note the acronym “ND” stands for Not Detected.

Based on the pH and chloride ion analytical results, we anticipate the corrosion potential of the on-site soils to uncoated steel is low. The sulfate content of the tested site soils is between 0% and

0.1%, indicating the site is generally suitable for use of Type 1 Portland Cement.

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4. LABORATORY TESTING

Our engineering staff reviewed the field boring logs to outline the depth, thickness and extent of the soil strata. The samples taken from the borings were examined in our laboratory and visually classified in general accordance with ASTM D2488, “Description and Identification of Soils (Visual-

Manual Procedure).” We established a testing program to evaluate the engineering properties of the recovered samples. A GSI technician performed laboratory testing in general accordance with the following current ASTM test methods:

Moisture Content (ASTM D2216, “Laboratory Determination of Water (Moisture) Content of

Soil and Rock”)

Atterberg Limits (ASTM D4318, “Liquid Limit, Plastic Limit, and Plasticity Index of Soils”)

Minus No. 200 Sieve Wash (ASTM D1140, “Amount of Material in Soils Finer Than the No.

200 (75-μm) Sieve”)

Laboratory test results are presented on the boring logs in Appendix B and are tabulated in Appendix

C.

Moisture content tests were used to evaluate the existing moisture condition of the soils. The

Atterberg limits and Minus No. 200 sieve tests were used to help classify the soils under the Unified

Soils Classification System. The Atterberg limits were also used to evaluate the plasticity characteristics of the soils.

The following data summarize our laboratory test results. We used these data to develop the allowable bearing values, anticipated settlements, and other geotechnical design criteria for the project.

Natural Moisture Content ................................................................ 1.7 to 29.4%

Liquid Limit ............................................................................................ 28 to 34

Plastic Limit ........................................................................................... 17 to 19

Plasticity Index ...................................................................................... 11 to 15

Percent Passing the No. 200 Sieve .............................................. 32.8 to 63.2%

Standard Penetration Test (SPT ’N’ blows per foot) ................................ 6 to 24

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Based on the results of this testing program, we reviewed and supplemented the field logs to arrive at the final logs as presented in Appendix B. The final logs represent our interpretation of the field logs and reflect the additional information obtained from the laboratory testing. Stratification boundaries indicated on the boring logs were based on observations made during drilling, an extrapolation of information obtained by evaluating samples from the borings, and comparisons of similar engineering characteristics. Locations of these boundaries are approximate and the transitions between soil types may be gradual rather than clearly defined.

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5. CONCLUSIONS AND RECOMMENDATIONS

5.1 General Geotechnical Considerations

The soils we encountered in the test borings are generally capable of supporting the anticipated loads exerted by the precast box conduit and precast concrete vaults. We did not encounter groundwater within the depth of expected excavation.

5.2 Earthwork

5.2.1 Site Preparation

Adjacent foundations and structures that will remain must be protected (where applicable) while performing excavations. Roof drains and stormwater drainage from these structures as well as the surrounding area should be directed away from the proposed construction area.

Relocation of existing utilities may be required for the placement of the new steam and chilled water line. We recommend that any abandoned utility pipes that cannot be removed be plugged with grout to reduce the potential for future collapse or moisture migration into the subgrade soils. Excavations resulting from utility removal must be replaced with engineered structural fill as outlined in Section

5.2.3.

5.2.2 Engineered Structural Fill

We anticipate that foundation excavations will be backfilled with the on-site material. Backfill soils should be free of vegetation, organics or other deleterious material. Any additional engineered structural fill should consist of granular material or low plasticity cohesive material with a liquid limit

(LL) less than 50, a plasticity index (PI) between 10 and 25, and be free from organic matter or debris. Granular fill should have a maximum particle size of 2 inches and meet IDOT freeze/thaw durability and magnesium sulfate soundness requirements.

5.2.3 Compaction of Engineered Structural Fills

Unless otherwise noted, fill materials should be placed in loose lifts not to exceed 9 inches and be compacted to a minimum of 95 percent of the maximum dry unit weight obtained from ASTM D698

(Standard Proctor). Moisture content at the time of compaction should be controlled to between optimum and 4 percent above optimum moisture content.

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If possible, granular fill materials containing less than 10 percent fines should be compacted to a minimum of 95 percent of the maximum dry unit weight obtained from ASTM D698. Granular fill materials which do not produce a definable moisture-density curve when tested according to ASTM

D698 should be compacted to a minimum of 75 percent relative density (ASTM D4253, “Maximum

Index Density and Unit Weight of Soils Using a Vibratory Table” and ASTM D4254, “Minimum Index

Density and Unit Weight of Soils and Calculation of Relative Density”). Granular materials should be placed at a moisture content that will achieve the desired densities. Please note that relative density and standard Proctor tests measure different parameters and are not interchangeable.

In general, proper compaction of cohesive soils can be achieved with sheepsfoot or pneumatic-type compactors, while compaction of granular soils can be achieved with smooth-drum or smooth-plate vibratory compactors. Water flooding is not an acceptable compaction method for any soil types.

5.2.4 Utility Trench Backfill

As a minimum, utility trench backfill material should meet the requirements of engineered structural fill as defined in Section 5.2.2. Backfill soils in utility trenches must be placed in lifts of 6 inches or less in loose thickness and be compacted in accordance with Section 5.2.3.

Controlled low strength material (CLSM) or flowable fill may also be used for utility backfills. We recommend designing flowable fill with a compressive strength between 50 and 300 pounds per square inch (psi). CLSM with a maximum compressive strength less than 300 psi can be readily excavated with a backhoe. The intent for the CLSM is to provide a backfill that can be placed in a single lift, without personnel entering the excavation and without the need for compaction equipment.

Where used beneath pavements or flatwork, CLSM should be terminated one foot below the pavement subgrade elevation. To provide uniform support beneath pavements and flatwork the fill placed over the CLSM should be of similar composition as the surrounding bearing materials and be constructed as moisture-conditioned and compacted engineered structural fill in accordance with

Section 5.2.3.

5.2.5 Correction of Unsuitable Foundation Soils

If soft, loose, or otherwise unsuitable soils are encountered at the bottom of the precast concrete box, an over-excavation and replacement/recompaction procedure will be required. The unsuitable

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soils beneath the precast concrete vault should be removed to the required depth, with the excavation extending laterally 9 inches in all directions for each vertical foot of over-excavation.

Structural fill for the over-excavated areas should be of similar composition as the surrounding materials or meet the requirements of engineered structural fill material as defined in Section 5.2.2.

Backfill material should be compacted in accordance with Section 5.2.3. CLSM, as defined in

Section 5.2.4 may also be used to backfill over-excavated areas.

5.2.6 Excavation Slopes

Vertical cuts and excavations may stand for short periods of time, but should not be considered stable in any case. All excavations should be sloped back, shored, or shielded for the protection of workers. As a minimum, trenching and excavation activities should conform to federal and local regulations.

The clay soils we encountered in the test borings generally classify as a type “B” soil while the clayey sand soils we encountered in our test borings generally classify as type “C” soils according to OSHA's

Construction Standards for Excavations. In general, the maximum allowable slope for shallow excavations of less than 20 feet in a type “B” soil is 1H:1V while the maximum allowable slope for shallow excavations of less than 20 feet in a type “C” soil is 1.5H:1V, although other provisions and restrictions may apply. If different soil types are encountered, the maximum allowable slope may be different.

The Contractor is responsible for designing any excavation slopes or temporary shoring. The

Contractor must also be aware that slope height, slope inclination, and excavation depths (including utility trench excavations) should in no case exceed those specified in federal, state, or local safety regulations, such as OSHA Health and Safety Standards for Excavations, 29 CFR Part 1926, or successor regulations.

Excavations performed near existing structures must not compromise the integrity or support of the existing foundation elements. Shoring, bracing, underpinning or other methods of maintaining foundation integrity may be required.

The information presented in this section is solely for our client’s reference. GSI assumes no responsibility for site safety or the implementation of proper excavation techniques.

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5.3 Precast Box Conduits

Based on the subsurface conditions revealed by the boring and testing program, the precast concrete vault structures may bear on undisturbed native soils at a depth of 10 feet below site grades.

A net allowable soil bearing pressure of 2,000 pounds per square foot (psf) may be used to size precast concrete vault structures bearing on a native soils at a depth of approximately 10 feet below site grade. The allowable bearing pressure is expressed in terms of the net pressure transferred to the soil. The net allowable bearing pressure is defined as the total structural dead load including the weight of the precast concrete vault, less the weight of the soil excavated for the foundation elements. This value may be increased by one-third for transient loading conditions such as wind or seismic forces.

5.4 Lateral Earth Pressures

Earth-retaining structures such as precast concrete vaults should be designed to withstand lateral earth pressures caused by adjacent soil and applied surcharge loads. The magnitude of the lateral earth pressure will depend on the height of the walls, stiffness of the walls, magnitude of the surcharge loads behind the walls, and the backfill and existing soil conditions behind the walls.

Assuming the walls are rigid and cannot move sufficiently to mobilize the shear strength of the soil, we recommend designing for an at-rest earth pressure condition.

Table 5.4.1: Lateral Earth Pressure Coefficients

115 24 0.59 0.42 2.37

115 31 0.48 0.32 3.12

Active

(Ka)

Passive

(Kp)

Soil Type

(USCS Symbol)

Wet Unit

Weight

(pcf)

Drained

Friction Angle

(Φ')

At

Rest

(Ko)

Clayey Sand (SC)

Lean Clay (CL)

The values provided above are empirical and are based on basic testing as well as our experience with similar materials. Please contact us if different materials are to be used for backfill. Appropriate factors of safety should be applied to the computed lateral earth pressures.

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Static surcharge loads imposed on below grade structures may be computed by multiplying the static surcharge load (q) by the at-rest pressure coefficient (Ka or Ko). Appropriate factors of safety should be applied to the computed lateral earth pressures.

5.5 Construction Considerations

If construction of the project is to be performed during periods of freezing temperatures, steps should be taken to prevent the soils under conduits or vaults from freezing. In no case should fill materials or precast structures be placed on frozen or partially frozen materials. Frozen materials should be removed and replaced with a suitable material as described in earlier sections of this report.

Construction performed during periods of high precipitation may result in saturated unstable soils, and caving or sloughing of excavations. Control of soil moisture will be necessary for successful soil compaction, and to maintain soil bearing capacity.

5.6 Construction Observation and Quality Assurance

We recommend that GSI be retained to review those portions of the plans and specifications that pertain to foundations and earthwork to evaluate consistency with our findings and recommendations. GSI will provide up to 2 hours of engineering support services at no charge to review project documents.

Site grading, including proof-rolling, replacement or recompaction of material, and placement of fill and backfill, should be observed by a quality assurance technician from GSI under the direction of a registered professional engineer. The technician should perform density tests and make any other observations necessary to assure that the requirements of the specifications are being achieved.

It is the opinion of GSI that construction observation by the geotechnical engineer of record or his designated representative is necessary to complete the design process. Field observation services are viewed as essential and a continuation of the design process. Unless these services are provided by GSI, the geotechnical engineer will not be responsible for improper use of our recommendations or failure by others to recognize conditions which may be detrimental to the successful completion of the project.

GSI Project No. 166078 October 3, 2016

© 2016 GSI Engineering Northern Division, LLC Page 5-6

GSI

GSI will be available to make field observations and provide consultation services as may be necessary. A written proposal outlining the cost of construction testing services such as soil and concrete quality assurance can be provided upon request.

GSI Project No. 166078 October 3, 2016

© 2016 GSI Engineering Northern Division, LLC Page 6-1

GSI

6. CLOSING REMARKS AND LIMITATIONS

This report is presented in broad terms to provide an assessment of the subsurface conditions and their potential effect on the adequate design and economical construction of the proposed structure.

The analyses, conclusions, and recommendations contained in this report are based on the site conditions existing at the time of the exploration, the project layout described herein, and the assumption that the information obtained from our four borings is representative of subsurface conditions along the piping alignment.

Any changes in the design or location of the proposed structure should be assumed to invalidate the conclusions and recommendations given in this report until we have had the opportunity to review the changes and, if necessary, modify our conclusions and recommendations accordingly. If subsurface conditions different from those encountered in the explorations are observed during construction or appear to be present beneath excavations, GSI should be advised at once so that the conditions can be reviewed and recommendations reconsidered where necessary.

If there is a substantial lapse in time between the submission of this report and the start of construction, or if site conditions or the project layout have significantly changed (due to further development of grading plans, natural causes, or construction operations at or adjacent to the site), we recommend that this report be reviewed to determine the applicability of our previous conclusions and recommendations.

Our geotechnical exploration and subsequent recommendations address only the design and construction considerations contained in this report. We make no warranty for the contents of this report, neither expressed nor implied, except that our professional services were performed in accordance with engineering principles and practices generally accepted at this time and location.

The scope of services for this exploration did not include a wetlands evaluation, an environmental assessment, or an investigation for the presence of hazardous or toxic materials in the soil, surface water, groundwater, or air within or adjacent to this site. If contamination is suspected or is a concern, we recommend the scope of this study be expanded to include an environmental assessment.

This report was prepared by the firm of GSI Engineering Northern Division, LLC (GSI) under the supervision of a professional engineer registered in the State of Iowa. Report preparation was in

GSI Project No. 166078 October 3, 2016

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GSI

accordance with generally accepted geotechnical engineering practices for the exclusive use of our client for evaluating the design of the project as it relates to the geotechnical aspects discussed herein. Recommendations are based on the applicable standards of the profession at the time of this report within this geographic area. GSI Engineering Northern Division, LLC will not be responsible for misrepresentation of this report resulting from partial reproduction or paraphrasing of its contents.

We appreciate the opportunity to be of service on this project. Please contact us if we can provide further information regarding the contents of this report or the scope and cost of additional services.

Respectfully submitted, GSI Engineering Northern Division, LLC

Ian Sutherland, I.E. Thomas C. Kettler, Jr., P.E.

Staff Engineer Senior Engineer

IMS/TCK

X:\7 - IOWA PROPOSALS AND PROJECTS\2016 Projects\166078\Geo-rpt (166078).docx

APPENDIX A

General Vicinity Map Boring Location Plan

Copyright © and (P) 1988–2012 Microsoft Corporation and/or its suppliers. All rights reserved. http://www.microsoft.com/streets/ Certain mapping and direction data © 2012 NAVTEQ. All rights reserved. The Data for areas of Canada includes information taken with permission from Canadian authorities, including: © Her Majesty the Queen in Right of Canada, © Queen's Printer for Ontario. NAVTEQ and NAVTEQ ON BOARD are trademarks of NAVTEQ. © 2012 Tele Atlas North America, Inc. All rights reserved. Tele Atlas and Tele Atlas North America are trademarks of Tele Atlas, Inc. © 2012 by Applied Geographic Solutions. All rights reserved. Portions © Copyright 2012 by Woodall Publications Corp. All rights reserved.

General Vicinity Map

PROJ. #:

SCALE:DATE:

FIG #:

EngineeringDRAWN BY:

NTS GSI

PROJECT WICHITA, KANSAS

WSU PARKING GARAGE

BORING LOCATION PLAN

9/27/16

MNT MANAGER:

166078

IMS

jvitteri Text Box GSI Engineering Northern Division, LLC 4450 Northwest Urbandale Drive Urbandale, Iowa 50322

(515) 270-6542 www.gsinetwork.com isutherland Text Box

BORING LOCATION PLAN

VAMC DOM STEAM AND CHILLED WATER PIPING

DES MOINES, IOWA

isutherland Text Box

IMS

jvitteri Text Box

APPENDIX B

Boring Logs Key to Symbols Legend & Nomenclature Unified Soil Classification System (USCS)

916.5

911.5

906.5

901.5

896.5

891.5

886.5

881.5

S-1

S-2

S-3

S-4

S-5

6" ASPHALT PAVEMENT

FILL (LEAN CLAY)- grayish brown, dry, stiff, asphalt fragment

LEAN CLAY- grayish brown, moist, stiff, trace sand, roots, rust stains, iron stains, trace fat clay

CLAYEY SAND- brown, moist, loose

- yellowish brown to gray, calcium nodules, rust stains, iron stains, else as above

LL=28; PL=17; PI=11

% Pass #200: 32.8

LEAN CLAY- gray, very moist, medium stiff

Bottom of Boring @ 15'

0.5'

2.5'

5.0'

13.5'

15.0'

CL

CL

SC

CL

1.7

16.6

13.2

19.4

29.4

BORING LOG No. B-1

BORING NO. LOCATION OF BORING ELEVATION DATUM DRILLER LOGGER

B-1 See Boring Location Plan 921.5 Site Topo D. Heldt J. Sui

WATER LEVEL OBSERVATIONS TYPE OF SURFACE DRILL RIG

WHILE END OF 24 HOURS Asphalt Mobile B-57

DRILLING DRILLING AFTER DRILLING AFTER DRILLING DRILLING METHOD TOTAL DEPTH

N.E. N.E. Boring Plugged After Drilling 4 in. Continuous Flight Augers 15.0 ft.

PROJECT: VAMC DOM Steam and Chilled Water Piping

LOCATION: Des Moines, Iowa

JOB NO.: 166078

DATE: September 10, 2016

DEP.

FT.

SAMPLE

NO. &

TYPE

SAMPLE DATA

"N"

BLOWS

(FT)

REC.

COLOR, CONSISTENCY, MOISTURE

GEOLOGIC DESCRIPTION & OTHER REMARKS

SOIL DESCRIPTION

USCS

CLASS.

MC

LABORATORY DATA

Dry Dens.

pcf qu ksf

ELEV.

FT.

914.5

909.5

904.5

899.5

894.5

889.5

884.5

879.5

S-1

S-2

S-3

S-4

S-5

6" TOPSOIL

FILL (LEAN CLAY)- brown to dark brown, slightly moist, stiff, roots, concrete fragment

LEAN CLAY W/SAND- dark brown to brown, slightly moist, very stiff

LEAN CLAY- brown to gray, moist, stiff

LL=34; PL=19; PI=15

- yellowish brown to gray, trace sand, rust stains, iron stains, trace gravel, else as above

- no gravel, else as above

Bottom of Boring @ 15'

0.5'

2.5'

5.0'

15.0'

CL

CL

CL

9.5

13.4

13.4

14.9

14.1

BORING LOG No. B-2

BORING NO. LOCATION OF BORING ELEVATION DATUM DRILLER LOGGER

B-2 See Boring Location Plan 919.5 Site Topo D. Heldt J. Sui

WATER LEVEL OBSERVATIONS TYPE OF SURFACE DRILL RIG

WHILE END OF 24 HOURS Grass Mobile B-57

DRILLING DRILLING AFTER DRILLING AFTER DRILLING DRILLING METHOD TOTAL DEPTH

N.E. N.E. Boring Plugged After Drilling 4 in. Continuous Flight Augers 15.0 ft.

PROJECT: VAMC DOM Steam and Chilled Water Piping

LOCATION: Des Moines, Iowa

JOB NO.: 166078

DATE: September 10, 2016

DEP.

FT.

SAMPLE

NO. &

TYPE

SAMPLE DATA

"N"

BLOWS

(FT)

REC.

COLOR, CONSISTENCY, MOISTURE

GEOLOGIC DESCRIPTION & OTHER REMARKS

SOIL DESCRIPTION

USCS

CLASS.

MC

LABORATORY DATA

Dry Dens.

pcf qu ksf

908.5

903.5

898.5

893.5

888.5

883.5

878.5

873.5

S-1

S-2

S-3

S-4

S-5

6" TOPSOIL

LEAN CLAY- gray, slightly moist, stiff, roots

LEAN CLAY W/SAND- dark brown to gray, moist, stiff, roots, calcium nodules

LEAN CLAY- greenish gray, moist, very stiff, heavy calcium nodules, rust stains

- as above

- stiff, else as above

Bottom of Boring @ 15'

0.5'

2.5'

5.0'

15.0'

CL

CL

CL

15.3

16.2

11.6

12.8

13.8

BORING LOG No. B-3

BORING NO. LOCATION OF BORING ELEVATION DATUM DRILLER LOGGER

B-3 See Boring Location Plan 913.5 Site Topo D. Heldt J. Sui

WATER LEVEL OBSERVATIONS TYPE OF SURFACE DRILL RIG

WHILE END OF 24 HOURS Grass Mobile B-57

DRILLING DRILLING AFTER DRILLING AFTER DRILLING DRILLING METHOD TOTAL DEPTH

N.E. N.E. Boring Plugged After Drilling 4 in. Continuous Flight Augers 15.0 ft.

PROJECT: VAMC DOM Steam and Chilled Water Piping

LOCATION: Des Moines, Iowa

JOB NO.: 166078

DATE: September 10, 2016

DEP.

FT.

SAMPLE

NO. &

TYPE

SAMPLE DATA

"N"

BLOWS

(FT)

REC.

COLOR, CONSISTENCY, MOISTURE

GEOLOGIC DESCRIPTION & OTHER REMARKS

SOIL DESCRIPTION

USCS

CLASS.

MC

LABORATORY DATA

Dry Dens.

pcf qu ksf

S-1

S-2

S-3

S-4

S-5

6" ASPHALT PAVEMENT

FILL (POORLY GRADED GRAVEL W/SAND)- grayish brown, dry, loose, asphalt fragments, concrete fragments

LEAN CLAY W/SAND- gray, moist, stiff, rust stains, iron stains, calcium nodules

- fine sand seam, else as above

SANDY LEAN CLAY- gray, moist, stiff, rust stains, iron stains % Pass #200: 63.2

LEAN CLAY- gray, moist, medium stiff, trace sand, sand seam

Bottom of Boring @ 15'

0.5'

2.5'

8.5'

13.5'

15.0'

GP-SP

CL

CL

CL

2.0

16.9

23.7

17.8

20.8

BORING LOG No. B-4

BORING NO. LOCATION OF BORING ELEVATION DATUM DRILLER LOGGER

B-4 See Boring Location Plan 910.0 Site Topo D. Heldt J. Sui

WATER LEVEL OBSERVATIONS TYPE OF SURFACE DRILL RIG

WHILE END OF 24 HOURS Asphalt Mobile B-57

DRILLING DRILLING AFTER DRILLING AFTER DRILLING DRILLING METHOD TOTAL DEPTH

N.E. 13.0 ft. Boring Plugged After Drilling 4 in. Continuous Flight Augers 15.0 ft.

PROJECT: VAMC DOM Steam and Chilled Water Piping

LOCATION: Des Moines, Iowa

JOB NO.: 166078

DATE: September 10, 2016

DEP.

FT.

SAMPLE

NO. &

TYPE

SAMPLE DATA

"N"

BLOWS

(FT)

REC.

COLOR, CONSISTENCY, MOISTURE

GEOLOGIC DESCRIPTION & OTHER REMARKS

SOIL DESCRIPTION

USCS

CLASS.

MC

LABORATORY DATA

Dry Dens.

pcf qu ksf

1. The exploratory borings were drilled on September 10, 2016 using 4-inch diameter continuous flight augers.

2. These logs are subject to the limitations, conclusions, and recommendations in this report.

3. Results of tests conducted on samples recovered are reported on the logs.

Notes:

Symbol Description

Strata symbols

Paving

Fill

Low plasticity clay

Clayey sand

Topsoil

Sandy lean clay or lean clay with sand

Misc. Symbols

Water table at the conclusion of drilling

KEY TO SYMBOLS

Boring Log Legend and Nomenclature

Items shown on boring logs refer to the following:

1. Depth - Depth below ground surface or drilling platform

2. Sample -Types designated by letter:

A - Disturbed sample, obtained from auger cuttings or wash water.

S - Split barrel sample, obtained by driving a 2-inch split-barrel sampler unless otherwise noted.

C - California liner sample, obtained using a thick-walled liner sampler containing 2-inch-diameter liner tubes.

U - Undisturbed sample, obtained using a thin-walled tube, 3-inch-diameter, or as noted, and open sampling head.

Recovery - Recovery is expressed as a percentage of the length recovered to the total length pushed, driven or cored.

Resistance - Resistance is designated as follows:

P - Sample pushed in one continuous movement by hydraulic rig action.

12 - The Standard Penetration Resistance is the number of blows for the last 12 inches of penetration of split spoon sampler, driven by a 140-pound hammer falling 30 inches.

50/4" - Number of blows to drive sampler distance shown.

3. Soil Description - Description of material according to the Unified Soil Classification: word description giving soil constituents, consistency or density, and other appropriate classification characteristics. Geologic name or type of deposit and other pertinent information, where appropriate, is shown under Geologic Description or other Remarks.