00901.pdf

St. John’s Interim Hospital Site Design

SECTION 00901

GEOTECHNICAL REPORT

1980DR-MO-COE-NPD-07-TO#6

New York District

St. John’s Temporary Hospital Facility Joplin, MO Contract No. W912DQ-08-D-0063 Task Order No. CE01

Geotechnical Report

September 2011

Submitted by:

Burns and McDonnell

9400 Ward Parkway Kansas City, MO 64114

Tel: 816-333-9400 Certification: 000165

SUBSURFACE INFORMATION

for the

PROPOSED TEMPORARY HOSPITAL

ST. JOHNS BOULEVARD AND WEST 28TH STREET

JOPLIN, MISSOURI

for

USACE

THERE IS NO EXPRESS OR IMPLIED GUARANTEE AS TO THE ACCURACY OR

COMPLETENESS OF THE INFORMATION AND DATA CONTAINED HEREIN, NOR

OF THE INTERPRETATION THEREOF BY THE OWNER, BURNS & McDONNELL

ENGINEERING COMPANY, OR ANY OF THEIR REPRESENTATIVES.

THE SUBSURFACE INFORMATION AND DATA CONTAINED HEREIN DO NOT

FORM A PART OF ANY CONTRACT DOCUMENT ISSUED BY THE USACE, BURNS

& McDONNELL, OR ANY OF THEIR REPRESENTATIVES.

IF THIS SUBSURFACE INFORMATION IS BEING ISSUED IN ELECTRONIC (PDF) FORMAT IT SHALL ONLY BE ISSUED IN ITS ENTIRETY, CONSISTING OF THE 4-PAGE FRONT-END DOCUMENT WITH A 140-PAGE

APPENDIX (FLYSHEET AND REPORT BY OLSSON).

BURNS & McDONNELL

PROJECT 62737

Burns & McDonnell

Engineers-Architects-Consultants Kansas City, Missouri

SEPTEMBER 2011

COPYRIGHT © 2011 BURNS & McDONNELL ENGINEERING COMPANY, INC.

ST JOHNS HOSPITAL JOPLIN SEPTEMBER 2011

PROJECT No. 62737

TABLE OF CONTENTS

Page No.

I. GENERAL

II. DESIGN NOTES

III. WATER LEVEL INFORMATION

IV. ADDITIONAL SUBSURFACE INFORMATION

V. LIMITATIONS

A. Document Use B. Variations

APPENDICES

APPENDIX A

Geotechnical Engineering Report, Proposed Temporary Hospital, St. Johns Boulevard and West 28th Street, Joplin, Missouri; prepared by Olsson Associates, dated September 15, 2011.

ST JOHNS HOSPITAL JOPLIN 1 SEPTEMBER 2011

PROJECT No.62737

I. GENERAL

This subsurface information document consists of the data and results of a subsurface investigation described in a report titled Geotechnical Engineering Report, Proposed Temporary Hospital, St. Johns Boulevard and West 28th Street, Joplin, Missouri, dated September 15, 2011. The investigation was performed by Olsson Associates (Olsson) of Olathe, Kansas. The report, as prepared by Olsson, is included in Appendix A of this document.

Field exploration and laboratory testing for this investigation was performed by Olsson. The field exploration consisted of drilling and test pits performed on August 16 through August 18, 2011. Drilling included twenty-three (23) borings drilled to depths ranging from 10.5 feet to 59 feet below grade. Eleven (11) test pits excavated to depths ranging from 6 to 12 feet below grade. Laboratory tests were conducted on select available samples following the completion of drilling operations. Boring logs and laboratory test results, as prepared by Olsson, are included in the report in Appendix A of this document. The report attached as Appendix A also contains information obtained in a preliminary exploration completed in June 2011 which included the completion of eighteen (18) borings to depths ranging from

10.0 feet to 46.0 feet below grade.

Samples recovered during the subsurface investigation were transported to the laboratory by Olsson. Olsson was not compensated to store the samples after testing and reporting beyond their customary retention period prior to disposal.

II. DESIGN NOTES

Geotechnical design notes as prepared by Burns & McDonnell pertinent to the current project have not been prepared for this project.

III. WATER LEVEL INFORMATION

Water levels were observed by Olsson, see Appendix A. It should be noted by the reader that fluctuations in water levels may occur over more prolonged periods of readings and can be influenced by various outside factors. It may take groundwater several days to reach its hydrostatic levels in holes in cohesive soils.

Seasonal variations in rainfall, changes to on-site conditions, and changes to off-site conditions can affect groundwater levels. Fluctuations in groundwater levels from those noted in logs should be anticipated during construction. Water levels observed and recorded by others reflect only those conditions that existed at the time of investigation and may vary from true phreatic groundwater levels.

IV. ADDITIONAL SUBSURFACE INFORMATION

Burns & McDonnell has requested from USACE (Owner) additional subsurface information in the vicinity of the Site. Burns & McDonnell was provided with the information as listed below. This information is available for review at Burns & McDonnell’s office upon prior written request.

1. Phase 1 Geologic/Geotechnical Report, St. John’s RHC, Joplin, Missouri; prepared by

Palmerton & Parrish, Inc., June 26, 2009.

ST JOHNS HOSPITAL JOPLIN 2 SEPTEMBER 2011

PROJECT No.62737

Burns & McDonnell is aware that a significant amount of construction and mining activity has been undertaken in the near vicinity of the Site. Additional information in the form of geotechnical reports and/or construction records may exist. Requests for additional information should be directed to the Owner.

Burns & McDonnell is not aware of any additional subsurface information in the vicinity of the Site. Requests for additional subsurface information should be directed to the Owner.

V. LIMITATIONS

A. DOCUMENT USE

The information provided in Appendix A has been prepared for the use of Burns & McDonnell for design purposes relating to civil site preparation. No other warranty, express or implied, is made as to the information included in this document. In the event that conclusions and recommendations based on data contained in this document are made by others, such conclusions and recommendations are the responsibility of others.

The information gathered and presented in this document was not obtained for an environmental audit nor to evaluate the potential for hazardous materials at the Site. The equipment, techniques, and personnel used to perform geoenvironmental exploration differ substantially from those applied in soil and foundation engineering. The purpose of this document is not intended as preparation for a Geotechnical Baseline Report, nor to provide information for use in developing construction cost estimates.

B. VARIATIONS

The subsurface information submitted in this document is based upon data obtained from test borings completed at the approximate locations indicated on the figure titled Boring and Test Pit Location in Appendix A. This document does not reflect variations which may occur between test borings. The nature and extent of variations between the test borings may not become evident until excavation is performed. If during construction, soil, rock, and/or groundwater conditions appear to be different from those described herein, Burns & McDonnell should be advised at once so that recommendations made may be evaluated and modified, if necessary. Water levels, as described in this document, reflect only those conditions that existed at the time that this particular subsurface investigation was performed by Olsson. Fluctuations or changes in water levels and groundwater conditions can be influenced by sources outside the site investigated, by seasonal rainfall, and by changes in drainage conditions in and around the Site. Fluctuations can occur and should be anticipated between the time of investigation and the time of construction.

Geotechnical Engineering Report, Proposed Temporary Hospital, St. Johns Boulevard and West 28th Street, Joplin, Missouri; prepared by Olsson Associates, dated September 15, 2011.

TABLE OF CONTENTS

INTRODUCTION

REPORT LIMITATIONS

PROJECT INFORMATION

SITE LOCATION AND DESCRIPTION

PROJECT DESCRIPTION

EXPLORATORY AND TEST PROCEDURES

FIELD EXPLORATION

LABORATORY TESTING

ENVIRONMENTAL SCREENING

SUBSURFACE CONDITIONS

SOIL TEST BORING AND LABORATORY SUMMARY

WATER LEVEL OBSERVATION

GEOTECHNICAL ENGINEERING RECOMMENDATIONS

SITE DISCUSSION AND GEOTECHNICAL CONSIDERATIONS

SITE PREPARATION

SLOPES AND TEMPORARY EXCAVATIONS

STRUCTURAL FILL

PAST MINE WORK CONSIDERATIONS

FOUNDATION DESIGN CONSIDERATIONS

SEISMIC DESIGN CONSIDERATIONS

LATERAL EARTH PRESSURES

MSE WALLS/REINFORCED SOIL SLOPES

PAVEMENT CONSIDERATIONS

PAVEMENTS SUBGRADE PREPARATION

PAVEMENT DESIGN

CORROSION POTENTIAL AND CHEMICAL ANALYSIS

SITE DRAINAGE AND GROUNDWATER CONSIDERATIONS

CONSTRUCTION OBSERVATION AND TESTING

FIGURES

FIGURE 1 – SITE LOCATION AND TOPOGRAPHY

TABLES

TABLE 1 – FILL PLACEMENT GUIDELINES

TABLE 2 – EARTH PRESSURE PARAMETERS

TABLE 3 – RECOMMENDED MAXIMUM STRENGTH PARAMETERS FOR MSE WALL

DESIGN

TABLE 4 – SUMMARY OF TYPICAL MINIMUM PAVEMENT DESIGN SECTIONS

APPENDICES

BORING LOCATION PLAN

APPENDIX B

SYMBOLS AND NOMENCLATURE

BORING LOGS

TEST PIT LOGS

APPENDIX C

SUMMARY OF LABORATORY TEST RESULTS

CORROSIVITY AND CHEMICAL ANALYSIS TEST RESULTS

APPENDIX D

ROCK CORE PHOTOS

APPENDIX E

TEST PIT PHOTOS

APPENDIX F

IDENTIFIED MINE FEATURES

APPENDIX G

PREVIOUSLY CONDUCTED BORINGS

Temporary Hospital Geotechnical Exploration

St. John’s Boulevard and W. 28th Street Joplin, Missouri

Joplin Temporary Hospital 1

OA Project No. 011-1815

INTRODUCTION

Olsson Associates (Olsson) has completed the geotechnical exploration for the Temporary

Hospital Site in Joplin, Missouri. The site for the temporary hospital is situated southeast of the intersection of St. John’s Boulevard and West 28th Street in Joplin, Missouri. As part of the exploration, Olsson drilled twenty-three (23) borings and excavated eleven (11) test pits at the site.

Additionally, we performed eighteen (18) borings as part of a preliminary exploration during June of

2011. A copy of the borings conducted in June are included in Appendix G of this report. The geotechnical engineering report discusses the subsurface conditions encountered at the borings and provides geotechnical engineering recommendations and opinions for the following:

Discussion on the presence of existing mine working and potential risks;

Foundation design parameters for shallow foundation systems, including allowable bearing pressures, minimum sizes, frost depth and anticipated total and differential settlement;

Lateral earth pressure parameters for design of retaining walls;

Site preparation and general earthwork recommendations, including fill placement and compaction considerations;

Estimates of pavement section thicknesses;

Corrosion potential and chemical testing of the subsurface soils;

Joplin Temporary Hospital 2

REPORT LIMITATIONS

The geotechnical recommendations and opinions presented in this report are based on the available information regarding the proposed construction, the results obtained from our soil test borings and laboratory tests, and our experience with similar projects. It is possible that conditions may be encountered during construction that are substantially different than those indicated by the soil test borings. In these instances, adjustments to construction may be necessary. We recommend that Olsson be retained to provide engineering and testing services for construction activities that involve the foundation and other related activities of this project. Olsson cannot accept responsibility for any conditions which deviate from those described in this report, nor for the performance of the foundations if not engaged to also provide a final exploration and construction observation for this project.

This report was prepared under the direction and supervision of a Professional Engineer registered in the State of Missouri with the firm of Olsson Associates. The conclusions, opinions, and recommendations contained herein are based on generally accepted professional geotechnical engineering practices within this geographic area at the time this report was prepared. No warranty, express or implied, is intended or made. This report has been prepared for the exclusive use of Burns and McDonnell for specific application to the proposed project.

Joplin Temporary Hospital 3

PROJECT INFORMATION

Site Location and Description

The site for the temporary hospital is situated southeast of the intersection of St. John’s Boulevard and West 28th Street in Joplin, Missouri. As shown in Figure 1, the site is characterized by a hill that peaks in the south central portion of the site and slopes downward in all directions.

Figure 1: Site Location and Topography

N

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OA Project No. 011-1815

The elevations across the site range from a high of about 1029 feet (USGS datum) at the crest of the hill to a low on the west side of the site of about 999 feet and a low on the northeast part of the site of about 1003 feet. Our review of aerial photographs dated from 1990 shows that the majority of the site has been heavily treed. At the time of our field exploration, the north, east and central portions of the site had been cleared and fill material had been placed. The west, south and southeast portions of the site were in the process of being cleared. We understand that a majority of the existing fill material contains trees and rubble debris following the tornado that recently travelled through Joplin.

The area of proposed development is contained within an area of Joplin that has undergone significant mining operations that date back to the late 1800’s and continued through to the 1950’s.

To further understand the extent of mining activity in the vicinity of the proposed structure, Olsson reviewed the following documents:

“Phase I Geologic/Geotechnical Report – St. John’s RHC – Joplin, Missouri”, prepared by

Palmerton & Parrish, Inc., dated June 26, 2009

“Mined Land Site Assessment – Proposed St. John’s Boulevard between 28th and Old 32nd

Street – Joplin, Missouri”, prepared by Allgeier, Martin & Associates, Inc., dated December

2001.

In addition to the reports discussed above, Olsson contacted the State of Missouri for any documented information about known mining activities at this site.

From the information that we have received from the State of Missouri as well as the information contained with the reports cited above, several prospect holes and/or shafts are present at this site.

At the time of our field exploration, two potential prospect holes/mine shafts were observed.

However, due to recent grading operations in the north and east portions of the site, evidence of prospect holes and/or mine shafts in these areas could not be observed.

Joplin Temporary Hospital 5

OA Project No. 011-1815

The two potential prospect holes identified were approximately 6 to 8 feet in diameter and had subsided approximately 2 to 3 feet. A mound of soil was observed around the perimeter of the hole.

The locations of these two potential prospect holes are on the Boring Location Plan in Appendix A.

In addition to the prospect holes, an area in the central portion of the site had been identified as containing potential mine tailings. For reference, we have included a copy of the map prepared by

Palmerton and Parish showing the locations of past mining activities in Appendix F. Given the nature of the past mining activities, it is possible that unmapped/undocumented mine features are present across the site.

Project Description

The temporary hospital is planned to be a one to two-story, prefabricated modular building, with a service life of approximately 2 to 3 years. The finished floor elevation of the proposed structure is anticipated to be at an elevation near 1016 to 1018 feet. The modular units will be supported on a foundation system and will have a 3 foot crawl space beneath the floor. The foundation system is anticipated to consist of column pads tied with grade beams. Structural loads were provided by

R&S Tavares Associates, Inc. and are anticipated to be 60 kips, or less for columns and 2 kips per foot, or less, for grade beams. Site development includes temporary parking lots on the west and east sides of the proposed building and a helipad to the south of the proposed building. A roadway is planned along the perimeter of the project.

In general, the south and west portions of the site will be cut to obtain the desired final grades.

Maximum cut depths are anticipated to be in the range of 10 to 12 feet. Fill will be required along the east portion of the site with maximum fill depths on the order of 15 to 20 feet.

To provide grade separation, retaining structures are planned on the west and northeast sides of the site, along the perimeter of the drive that encircles the site. The retaining walls are anticipated to have maximum heights of about 8 to 10 feet. We understand that these retaining wall structures will be constructed as a modular block - geogrid reinforced backfill system. Specific details regarding these walls are not available at the time of this report.

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The central plant for the hospital will be located north of the proposed building. It is anticipated the structure will be approximately 40 feet by 60 feet and will be constructed from modular units consistent with the hospital. In addition to the central plant and hospital building, several smaller ancillary structures are proposed. We understand that these structures may be supported on mat foundations and will be small and lightly loaded.

Joplin Temporary Hospital 7

EXPLORATORY AND TEST PROCEDURES

Field Exploration

The field exploration program consisted of 23 borings and 11 test pits at the site. The boring and test pit locations are shown on the boring location diagram located in Appendix A.

With the exception of Boring B-52 and Test Pits TP-38, TP-39 and TP-54, all borings and test pits were staked in the field and elevations were determined by an Olsson survey crew prior to drilling.

Boring B-52 and Test Pits TP-38, TP-39 and TP-54 were located in the field by measuring distances from existing site features and estimating right angles. The reported elevations at these locations were interpolated from existing site contours. The true surface elevations at these locations could differ due to the limitation associated with interpolation. The drill crew noted any offsets and elevation differences from the staked boring locations.

The borings were drilled to depths ranging from about 10 to 59 feet. ATV and truck mounted drill rigs equipped with continuous-flight solid and hollow stem augers were used to advance the borings.

Soil samples were obtained at selected intervals using split barrel sampler during the performance of the Standard Penetration Test. An automatic trip hammer was used in each boring except borings B-51 and B-52. In borings B-51 and B-52, a rope and cathead hammer was used. The blow counts shown on each boring log are uncorrected. Upon practical auger refusal, Borings B-51 and

52 were advanced into the underlying bedrock using rock coring procedures. The recovered 2 inch diameter core samples were placed in core boxes and returned to our laboratory for visual classification and logging.

Test Pits were excavated using a back hoe to depths ranging from 8 to 12 feet below the existing ground surface. Photographs from the test pits are contained in Appendix E.

Two temporary piezometers were installed at borings B-21 and B-31 to depths of 20 and 18.5 feet, respectively, to measure the water levels. Each well was constructed using 2-inch diameter, Schedule 40 PVC pipe. The screened length at B-21 and B-31 was 10 feet and 8.5 feet, respectively. The filter pack consisted of manufactured 10/20 sand and was placed from the bottom

Joplin Temporary Hospital 8

OA Project No. 011-1815 of the piezometer to a distance of 2 feet above the screen. Each piezometer was completed above grade. At this time, no water level readings in the piezometer have been taken. The remaining borings were left open for 24 hours to obtain groundwater levels and were then backfilled.

Laboratory Testing

The soil and rock core samples obtained from the borings were returned to our laboratory for testing and visual classification. The soil samples were visually classified using the Unified Soil

Classification System (USCS). The moisture content was determined for each split barrel sample.

In addition, Atterberg limit tests and grain size analyses were performed on selected samples. The rock core samples obtained were visually logged. The Rock Quality Designation (RQD) and percent recovery were also determined. RQD is the percent of total length cored consisting only of sound pieces at least 4 inches or more in length and is a measure of the integrity of the rock mass in-situ. Based on RQD, rock quality can be described as excellent (90-100%), good (75-90%), fair

(50-75%), poor (25-50%), and very poor (<25%). Results of the laboratory tests are shown on the boring logs and in Appendix C.

Environmental Screening

During the field exploration, we used a MiniRAE 2000 Photo Ionization Detector (PID) to monitor the drill cuttings and breathing zone behind the drill rig for contaminates. Additionally, headspace readings were taken in jar samples approximately one hour after the sample was obtained to determine the presence of volatile organic compounds (VOC’s). The PID readings are provided on the logs.

Joplin Temporary Hospital 9

SUBSURFACE CONDITIONS

Soil Test Boring and Laboratory Summary

The conditions encountered at each boring and test pit are shown on the boring and test pit logs in

Appendix B. Soil stratification lines shown on the boring and test pit logs represent soil conditions at the boring and test pit locations locations; variations may occur between or around the boring and test pit locations. The lines of demarcation represent the approximate boundary between soil types. This transition usually occurs more gradually.

In the borings and test pits that were conducted in the north and east portions of the site, the subsurface conditions generally consisted of fill underlain by red cherty fat clay soils. The subsurface conditions encountered in the west and south portions of the site generally encountered a 12 to 18 inch thick developed zone underlain with red cherty fat clay soils. In the vicinity of

Borings B-22, B-31, B-51 and B-52, the fat clay was underlain with limestone at depths of approximately 20 to 25 feet.

Topsoil

Topsoil shown on the boring and test pit logs was approximately 12 to 18 inches thick. This zone generally consisted of varying amounts of organics (roots), gravel, cobbles and clay soils. The topsoil encountered in the borings would typically need to be stripped and stockpiled outside of any building, parking lot and fill areas prior to the placement of engineered fill.

Previously Placed Fill

Previously placed fill was encountered in the north and east portions of the site and extended to depths ranging from approximately 5 to 15 feet below the existing ground surface at the boring and test pit locations. The fill material was highly variable in material types and consistency and included fat clay with chert cobbles, organics, trees, concrete and asphalt rubble, metal debris and gravel. Based on the borings and test pits, the organic fill material was primarily concentrated in the north central and east portion of the site.

As the test pits and borings are widely spaced, variations in the location, consistency and thickness of the fill material may be present at this site and should be expected.

Joplin Temporary Hospital 10

OA Project No. 011-1815

Fat Clay/Clayey Gravel

Beneath the developed zone and beneath the fill, each boring and test pit, except B-48 and TP-34, encountered cherty, fat clay soils and clayey gravel. The fat clay and clayey gravel extended to the base of each boring except B-51 and B-52, which were advanced into the underling bedrock.

Variable amounts of chert were observed within the clay soils and the zones classified as clayey gravel were predominately chert cobbles with clay binder. The fat clay soils were generally stiff to hard and generally exhibited relatively high moisture contents.

Highly Weathered Shale

Boring B-48 and Test Pit TP-34 encountered highly weathered shale with traces of chert fragments from the ground surface to the base of the boring and the test pit. The location of B-48 and TP-34 is in the vicinity of the area identified by Palmerton and Parish to contain possible mine tailings.

Visual observation of the shale material indicated the material had horizontal bedding planes and was very stiff to hard. The shale was observed to be free of voids during excavation of the test pit.

Limestone

Limestone was encountered in borings B-51 and B-52 at depths of 20.5 and 23.5 feet below the existing ground surface, respectively. Each boring was advanced into the underlying limestone using rock coring techniques. The percent recovery at the boring locations generally ranged from

90 to 98 percent. The Rock Quality Designation (RQD), which is a measure of how intact the bedrock strata is in-situ, was 90 percent in Boring B-51 and 0 and 65 percent in Boring B-52.

Based on observations during drilling operations, it is likely that B-52 encountered a joint in the limestone and/or a pinnacle. The recorded RQD readings are indicative of very poor to excellent quality limestone. Photographs of the recovered core samples are included in Appendix D.

Practical auger refusal was encountered in borings B-22, B-25 and B-43 through B-50 at depths ranging from 15 to 59 feet below the existing ground surface. Due to the variability of the depth to refusal, we could not ascertain if the refusal occurred on bedrock materials or on boulders.

Joplin Temporary Hospital 11

OA Project No. 011-1815

Water Level Observations

Water level readings were obtained during, upon completion and 24 hours after completion of the auger drilling operations. In the borings that were cored, water level readings were observed prior to rock coring. As water is used to remove cuttings and cool the core bit during rock coring procedures, accurate water level readings cannot be obtained during or after rock coring.

Groundwater was encountered in borings B-43 and B-45 at depths of 40 and 46 feet, respectively, 24 hours upon completion of drilling operations. The remaining borings remained dry.

The absence of water in boreholes during the exploration program should not be construed to represent an absolute or permanent condition. Water typically collects near the soil and bedrock interface and can flow through joints in limestone strata.

In test pit TP-38, a gravel zone in the previously placed fill was encountered at a depth of approximately 4 feet. Water was visually observed flowing out of the material into the excavation indicating the water was trapped within the gravel zone. Additional pockets of trapped water could be encountered within the existing fill across the site.

Variations and uncertainties exist with relatively short-term water level observations in boreholes.

Water levels can and should be anticipated to vary between boring locations, as well as with time within specific borings. Groundwater levels may be expected to fluctuate with variations in precipitation, site grading, drainage and adjacent land use.

Joplin Temporary Hospital 12

GEOTECHNICAL ENGINEERING RECOMMENDATIONS

Site Discussion and Geotechnical Considerations

In general, the borings encountered highly variable subsurface conditions, including relatively shallow limestone bedrock (20 to 25 feet below ground surface) on the higher, south side of the site and fill underlain by cherty fat clay interspersed with cobbles and boulders on the north half of the site. The limestone encountered in the higher portion of the site appears to be a cap rock that has weathered and is localized to that portion of the site. In the remaining borings, the depth of auger refusal was highly variable and we could not ascertain if the refusal occurred on bedrock materials or boulders.

Based on the information we reviewed relating to past mining activities, it does not appear as though the site is underlain by any known mines. However, several documented prospect holes and mine shafts have been noted to be present across the site in past explorations. During our field exploration, two areas were identified as old prospect holes. It is unknown if the identified areas coincide with previously identified areas.

The mine shafts and prospect holes identified in the previous studies were not visually observed during our field observations. It is likely that these other features have been filled in or disturbed due to recent grading operations. Sinkholes have developed in the Joplin area in the past as a result of past mining activities and, if not discovered and mitigated during construction, could impact the temporary hospital. While these risks are common in the Joplin area and cannot be fully eliminated, these risks can be further reduced by thorough evaluation and proper repair during construction. In addition to the mining activities present across the site, previous studies identified a large portion of the site may have been used for mine tailings. The mine tailings could account for some of the variation in the subsurface conditions and isolated area of weathered shale we observed at this site.

The fill material encountered in the north and east portion of the site consisted of lean to fat clay with rubble debris, gravel, organics and trees. The fill material was not placed with strict moisture and density control for future building support. This material will not be suitable for support of settlement sensitive structures and will require removal and replacement with structural fill.

Joplin Temporary Hospital 13

OA Project No. 011-1815

The native fat clay soils had highly variable amounts of chert and cobbles and tended to have relatively high moisture contents. Although these soils were noted as being stiff to hard in consistency at the boring locations, these soils could become unstable during construction and undergo significant pumping and rutting. Discing, spreading and aeration of these soils may be necessary.

Excavation at this site will likely be difficult due to the amount of cobbles that were encountered across the site. We anticipate that the majority of the native fat clay soils will be able to be excavated with standard excavation equipment. Depending on the amount of cobbles present within the clay soils, rock teeth and/or ripper equipped dozers may be necessary to remove some of the material. Areas may require pneumatic breakers in the event that large boulders or chert seams are encountered.

Site Preparation

Prior to commencement of grading operations, existing organic topsoil, vegetation and related root systems, frozen soil, and/or any other unsuitable materials should be removed from the construction areas. Stripping depths will likely vary and should be adjusted as necessary to remove all vegetation and root systems. Significant reworking and moisture conditioning of dry or desiccated soil in and around treed areas should be anticipated. This zone could extend several feet below the ground surface.

The existing fill material at the site consisted of a mixture of lean to fat clay with rubble debris, gravel, organics and trees. Foundations supported directly on the existing fill could experience excessive amounts of total and differential settlement. To minimize the risk associated with settlement of foundations, we recommended that the fill material be entirely removed and replaced with suitable structural fill from beneath the hospital building, central plant, and any other ancillary structure that is sensitive to excessive settlement. Complete removal of the fill material would also aid in identifying potential past mine workings at the site. The existing fill material may be reused as structural fill provided all organic and unsuitable material is removed. Excavation of the fill material should extend a minimum of 10 feet beyond the limits of any settlement sensitive structure.

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OA Project No. 011-1815

Complete removal of existing fill material should also occur in the areas of the proposed retaining walls. The excavation of the fill in the vicinity of the retaining walls should extend a minimum of 5 feet beyond the back of the reinforced zone.

In areas where the owner is willing to accept the risks associated with the existing fill (e.g., excessive movement, deflection and/or cracking), it may be possible to leave some of the existing fill in place. In these areas, we recommended that at least 4 feet of suitable structural fill be present beneath the final subgrade elevations. Depending on the composition of the fill at the base of the excavation, additional undercutting may be recommended at that time. In areas where the existing fill terminates within 4 feet of the final subgrade elevation, it is permissible to stop excavation operations assuming the subgrade is stable. Additional maintenance of pavements and/or structures in the areas where the fill is not removed in its entirety should be anticipated. Any potential prospect holes and/or mine shafts may go undiscovered if the fill is not removed, increasing the risk for future sink holes to develop across the site.

Once excavation of the fill material is complete, we recommend that the upper 9 inches of exposed subgrade be scarified, moisture conditioned and recompacted to a minimum of 95 percent of the materials Standard Proctor maximum dry density (ASTM Specification D-698) at a moisture content between optimum and 4% above optimum.

Where fill is placed on existing slopes steeper than 5:1 (Horizontal:Vertical), benches should be cut into the existing slopes prior to fill placement. Benches should have a minimum vertical face of 1 foot and should be wide enough to accommodate compaction equipment. We recommend that final site grades across the site do not exceed 3:1 (Horizontal:Vertical).

In deep fill areas, the native soils and the controlled fill will consolidate over time, resulting in some surface settlement. Based on fill depths under 10 feet, we expect that consolidation and settlement would occur during fill placement. The amount of settlement would be dependent on the depth to bedrock and the amount of fill. For fill depths between 10 and 20 feet, we expect settlement would continue over the course of 30 to 60 days following placement of fill. In general, total settlements due to the weight of the new fill are anticipated to be in the range of 1 to 2 inches. Construction of settlement sensitive structures, including building foundations, floor slabs, and utilities, should be delayed until the settlement has occurred. Where fill depths exceed 15 feet, we recommend the

Joplin Temporary Hospital 15

OA Project No. 011-1815 rate of settlement be monitored by installing and periodically reading settlement monitoring plates or by obtaining periodic ground surface elevations at the deeper fill locations. A minimum of 3 settlement monitoring plates should be installed within the deeper fill sections. The ground surface elevations should be tied to a fixed, stable benchmark obtained at select points across the site would help provide an indication of the rate and magnitude of settlement.

Slopes and Temporary Excavations

Excavations will be required during mass grading, construction of foundation elements and utilities at this site. All excavating must comply with applicable local, state, and federal safety regulations. The responsibility for excavation safety and stability of temporary construction slopes lies solely with the contractor. We are providing this information below solely as a service to our client. Under no circumstances should the information provided be interpreted to mean that Olsson is assuming responsibility for construction site safety or the Contractors activities. Such responsibility is not being applied and should not be inferred.

For this site, the overburden soil encountered in the borings and test pits consisted of fat clay with cobbles, cobbles with clay binder and lean to fat clay with rubble debris, organics and trees. The soils encountered meet the criteria for Type “B” soils. However, Type “A” and “C” soils could also be present at this site.

Structural Fill

All structural fill and backfill should consist of low plasticity (lean clay) soil or clayey gravel classifying as CL or GC. High plasticity clay soils (soils with a Liquid Limit above 60) should only be used if containing over 35 percent chert fragments retained on the No. 4 sieve. In fills that are comprised primarily of clay soil, rock fragments that are greater than 6 inches in any dimension should not be included in engineered fills. Based on laboratory test results, the on-site soils appear suitable for re-use as structural fill. Unsuitable materials (such as organics, debris or other deleterious materials) would need to be removed from the fill.

Suitable fill material should be placed in loose lifts of 9 inches or less. In general engineered fill should be compacted to a minimum of 95% of the as determined by the Standard Proctor method

(ASTM D-698) at a moisture content between optimum and +4 percent of the optimum moisture content. Adjustment of moisture content may be necessary to allow compaction in accordance with project specifications.

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Fill material comprised of a significant percentage of rock should be spread and compacted such that no voids are present and the rock fragments have intimate contact with the surrounding soil particles. The material should be visually observed to be stable with no pumping and/or rutting.

Placement and compaction should be closely monitored on a full-time basis by a representative of

Olsson, since compaction control testing using moisture-density gauges does not produce consistent data on mixed rock and soil fills.

As an alternative to the on-site soils, granular material may be used. It is recommended that granular fill consist of a ¾ inch minus material, such as MoDOT Type 5 aggregate.

During grading operations, a full-time representative from Olsson should be on site to monitor excavation and grading operations as well as the suitability of fill materials. Laboratory Standard

Proctor tests (ASTM D-698) and classification tests should be performed on representative samples obtained from any off-site proposed cut and/or borrow areas to provide data necessary to determine acceptability and for quality control. Representative samples of the proposed engineered fill materials should be submitted at least 3 days prior to placement so the necessary laboratory tests can be performed. Any imported fill material should be tested prior to placement at the site to verify it complies with the criteria stated in this section of the report. Additional fill placement guidelines are provided in Table 1.

TABLE 1

FILL PLACEMENT GUIDELINES

Areas of Fill Placement Compaction Recommendation (ASTM D698-Standard Proctor)

Moisture Content (Percent of Optimum)

Structural fill placed as part of grading operations with a minimum of 35% chert fragments

95% 0 to +4 percent

Pavement Subgrade – 12” below bottom of pavement or pavement aggregate base with a LL<50 and PI <25

95% 0 to +4 percent

Pavement Subgrade – 12” below bottom of pavement or pavement aggregate base with a minimum of 35% chert fragments as retained on the No. 4 sieve.

95% 0 to +4 percent

Utility Trenches – Within building and pavement areas

95% 0 to +4 percent

Beneath Landscaped/Grass Areas 92% As necessary to obtain density

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Within small excavations, such as in utility trenches, around manholes or behind retaining walls, the use of "Wacker Packers", "Rammax" compactors or vibrating plate compactors to achieve the specified compaction may be required. Loose lift thicknesses of 4 inches are recommended where small compaction equipment is used.

Past Mine Work Considerations

As noted, several prospect holes and mine shafts have been identified across the site and during our field observation, two potential prospect holes were observed. While evidence of additional prospect holes and mine shafts are not visually evident at this time, there is risk associated with undiscovered mine workings being present beneath the proposed building. Unidentified or undiscovered prospect holes and mine shafts could result in sink holes that develop in the future resulting in excessive settlement of the proposed building.

It is recommended that a representative of Olsson be present during grading operations and excavation of foundation elements to observe signs of potential mine workings. Any areas that are observed during grading and foundation construction should be mapped and repaired during construction. Recommendations for remediation of any mine features will be dependent on the conditions encountered during construction.

Visual observation of the weathered shale encountered in B-48 and TP-34 indicated the material was very stiff to hard, horizontally bedded and appeared to be native. Additionally, during excavation of TP-34, the material was uniform and consistent and no voids were present within the sidewall of the excavation. As noted, these soils are within the vicinity of the area identified to contain potential mine tailings. The samples obtained in B-48 and TP-34 represent a very small statistical sampling of weathered shale and it is possible that conditions may be encountered during construction that are substantially different from the boring and test pit. In the event that the weathered shale is associated with mine tailings over-excavation of the material may be necessary.

Recommendations for over-excavation of the shale will be dependent on the conditions encountered during construction.

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Foundation Design Recommendations

Shallow foundations supported on structural fill and/or stiff native soils can be designed for a maximum net allowable soil bearing pressure of 3,000 psf on the soil. This allowable bearing pressure may be increased by 33 percent for short term loading conditions such as loads imposed by winds. The net allowable bearing pressure refers to the bearing pressure at the foundation level in excess of the surrounding overburden pressures.

Perimeter footings and footings beneath unheated areas should extend at least 24 inches below the lowest adjacent finished grade for frost protection and protection from seasonal moisture flucuations, unless greater embedment is recommended to provide confinement of the foundations.

Isolated footings should have a minimum width of 30 inches, and continuous footings should have a minimum width of 16 inches.

The base of all foundation excavations should be free of all water and loose material prior to placing concrete. Concrete should be placed soon after excavating to minimize disturbance to the bearing materials. Should the materials at bearing level become disturbed, the affected material should be removed prior to placing concrete. It is possible that some soils at the project site will have an allowable soil bearing capacity less than the recommended design value. After excavation, the foundation subgrade should be observed by an Olsson representative to evaluate that the soils are uniform and consistent with the soils encountered during this investigation. In the event that isolated areas of soft or unsuitable soils are identified, the Geotechnical Engineer should be consulted to assist in determining appropriate corrective actions.

Shallow foundations designed and constructed as recommended above, would be expected to experience total and differential settlements on the order of 1 inch and ½ inch, respectfully. Additional settlement could occur due to past, undiscovered mine workings.

Mat Foundation

Mat foundation may be designed using a preliminary modulus of subgrade reaction of 100 pci. This value is based on the reaction of a 1 foot by 1 foot area and should be corrected based on the final mat dimensions. It is recommended that Olsson be given the opportunity to review final mat sizes and pressure distribution to provide additional recommendations as needed.

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Uplift Loading and Lateral Load Resistance

Uplift loads on foundations may be resisted by the weight of the footing in addition to the weight of the soil prism extending upward at a 30 angle from the vertical as measured from the bottom of the footing. Horizontal loads may be resisted by sliding friction at the base of the footing using an ultimate coefficient of friction of 0.35. The base friction value is an ultimate value with no factor of safety and may not be applicable in combined uplift and horizontal analyses.

Seismic Design Considerations

The subsurface profile across the site consisted of very stiff, fat clay soils with chert cobbles, cobbled with clay binder and boulders underlain with bedrock. Based on this information, the project site would be classified as Site Class “C” per the 2009 International Building Code (IBC).

Based on information obtained from the Missouri Center for Applied Research and Environmental

Systems website (www.cares.missouri.edu), it does not appear that any faulting is present within the vicinity of the proposed project. While karst prone soils were not identified for this specific site, they are present in the Joplin area and it is possible that voids and or sinkholes may develop in the future.

Remedial measures would depend on the size of the depression and total effected area.

Lateral Earth Pressures

The following soil parameters are provided for use in designing free standing concrete cantilever retaining walls subject to lateral earth pressures. The parameters are based on the understanding that retained soils will be similar in composition to the on-site soils encountered during this exploration.

Walls that are unrestrained at the top and are free to deflect or rotate slightly may be designed for

"active" earth pressure conditions. Active earth pressure is commonly used for design of free-standing cantilever retaining walls. The "at-rest" condition assumes no wall rotation. The

"passive" earth pressure condition should be used to evaluate the resistance of soil to lateral loads.

Table 2 presents recommended values of earth pressure coefficients based on our experience with soils in the area.

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TABLE 2

EARTH PRESSURE PARAMETERS

LEGEND OF SYMBOLS

Z WALL HEIGHT (ft)

H

DEPTH BELOW SURFACE

(ft)

D WALL DISPLACEMENT (ft)

S SURCHARGE LOAD (psf)

P1

SURCHARGE PRESSURE

(psf)

P2 EARTH LOAD (psf)

K (Table 3)

COEFFICIENT OF EARTH

PRESSURE

G (Table 3)

EQUIVALENT FLUID

DENSITY (psf)

PRESSURE CALCULATIONS

SURCHARGE

P1 (psf) = K x S (psf)

EARTH

P2 (psf) = G (pcf) x H (ft)

EARTH PRESSURE COEFFICIENT (K)

EQUIVALENT FLUID DENSITY (G)

DRAINED CONDITION UNDRAINED CONDITION

ACTIVE (Ka) Cohesive 0.40 45 pcf 85 pcf

Granular* 0.33 40 pcf na

AT REST (Ko) Cohesive 0.50 60 pcf 90 pcf

Granular* 0.41 45 pcf

PASSIVE (Kp) Cohesive 2.50 300 pcf

Granular* 3.00 360 pcf

* If granular backfill is utilized, it is recommended the granular backfill be permanently drained

For active earth pressure, wall must rotate about base, with top lateral movements 0.002 Z to

0.004 Z, where Z is wall height

Wall must “move” horizontally to mobilize passive resistance

Uniform surcharge, where S is surcharge pressure, in psf

In-situ soil backfill weight a maximum of 120 pcf

Horizontal backfill, compacted to 95% of Standard Proctor maximum dry density

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Heavy equipment and other concentrated load components not included

No hydrostatic pressure acting on wall

No safety factor included

Ignore passive pressure in frost zone

Backfill placed against structures should consist of granular soils or low plasticity cohesive soils. For the granular values to be valid, the granular backfill must extend out from the base of the wall at an angle of at least 45 and 60 degrees from vertical for the active and passive cases, respectively. To calculate the resistance to sliding, an ultimate coefficient of friction value of 0.35 should be used where the footing bears on soil.

To intercept infiltrating surface water behind the wall, we recommend a perimeter drain be installed at the foundation level. The invert of a drain line around a below-grade building area should be below the finished subgrade elevation for the interior floor. The drain line should be sloped to provide positive gravity drainage and should be surrounded by free-draining granular material graded to prevent the intrusion of fines, or an alternative free-draining granular material encapsulated with suitable filter fabric,. At least a 2-foot wide section of free-draining granular fill should be used for backfill above the drain line and adjacent to the wall and should extend to within

2 feet of final grade. The granular backfill should be capped with compacted cohesive fill to minimize infiltration of surface water into the drain system.

MSE Walls/Reinforced Soil Slopes

We understand that MSE Walls and/or reinforced soil slopes may be used to provide grade separation at this site. These walls are typically subcontracted as design-build structures, since design details are often manufacturer specific. Established design methods for modular block walls address local and internal stability, but do not specifically address the global stability of the wall system. Therefore, we recommend the following general and specific considerations be included in the project specifications for the wall design.

Internal stability analyses should conform to the latest design methodology accepted for use by the

Federal Highway Administration (FHWA), AASHTO or the National Concrete Masonry Association

(NCMA). Since these analysis procedures are based on the use of drained strength parameters, the

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OA Project No. 011-1815 backfill used for the geogrid reinforced backfill section should be a drainable, granular material to conform with the assumptions of the analysis. Cohesive soil or granular material containing high amounts of fines are not considered drainable and should not be allowed in the geogrid reinforced backfill zone unless provisions are made to provide backslope and surface drainage that would prevent water from entering the…