Soils_Exploration_Report_-_Bldg_1_Envelope.pdf

December 11, 2012 L - 79,401

REPORT OF SOILS EXPLORATION

REPAIR HANGAR P1 BUILDING ENVELOPE

ILLINOIS AIR NATIONAL GUARD

SPRINGFIELD, ILLINOIS

PREPARED FOR

SAIC ENERGY, ENVIRONMENT & INFRASTRUCTURE, LLC

622 EMERSON ROAD, SUITE 600

ST. LOUIS, MISSOURI 63141-6728

PREPARED BY

TESTING SERVICE CORPORATION

1701 WEST MARKET STREET

BLOOMINGTON, ILLINOIS 61701

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December 11, 2012 L - 79,401

REPORT OF SOILS EXPLORATION

REPAIR HANGAR P1 BUILDING ENVELOPE

ILLINOIS AIR NATIONAL GUARD

SPRINGFIELD, ILLINOIS

INTRODUCTION

This report presents results of our site exploration which was performed to determine subsurface soil and groundwater conditions in the area of Hangar P1 at the Illinois Air National Guard facility in Springfield, Illinois. These services were provided in accordance with Testing Service Corporation (TSC) Proposal No.

49,810, dated October 8, 2012, and the attached general conditions. The scope of our evaluation included completion of soil borings, field and laboratory testing on subsurface soil samples, and an engineering analysis and evaluation of the site conditions. Results of field and laboratory work along with the conclusions based upon that work are included in the following sections of this report.

BACKGROUND INFORMATION

We understand that the project will consist of modifications to Hangar P1 at the existing Illinois Air National Guard facility in Springfield, Illinois. We understand that the existing hangar building was constructed in the late 1930's or early 1940's. New bays were added to the structure in the late 1950's or early 1960's.

Partial structural drawings from July of 1950 provided by SAIC indicate that the building is supported on conventional spread footings. The column footing dimensions range from 8'-8" to 8'-10" with bearing depths ranging from 4'-4" to 5'-6" below the floor slab. A note on one of the plan sheets indicates that the footings were designed based upon a soil pressure of 2,000 pounds per square foot (psf).

Repair Hangar P1 Building Envelope Illinois Air National Guard Springfield, Illinois L - 79,401 December 11, 2012

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We understand that settlement of the structure has been observed, particularly near the northwest and southeast corners of the building. The modifications to the building will include closing in an overhead door on the west side of the building. The purpose of the geotechnical engineering services outlined in this proposal is to evaluate the subsurface conditions which may have led to the observed settlement.

Recommendations regarding the new foundation for the wall infill are also required.

FIELD EXPLORATION

In order to allow for an evaluation of the subsurface conditions in the area of the building, four (4) soil borings were drilled by TSC in November of 2012. Three (3) of these borings were drilled along the west wall of the building and one (1) boring was located near the southeast corner. Each of these borings were drilled to a depth of approximately 35 feet below the existing ground surface. The locations of these borings are shown on the Boring Location Plan included in the appendix of this report.

The borings were drilled and sampled according to currently recommended American Society for Testing and Materials (ASTM) specifications. Soil sampling was performed at 2-1/2 foot intervals to a depth of 15 feet and at 5 foot intervals thereafter to the termination depth of each boring. Samples were generally obtained in conjunction with the Standard Penetration Test, for which the driving resistance of a 2 inch diameter split-spoon sampler provides an indication of the relative density of granular materials and consistency of cohesive soils. Selected samples were also obtained by thin walled tube methods. Water level readings were taken during and following completion of the drilling operations.

LABORATORY TESTING

Soil samples were examined in the laboratory to verify field descriptions. Laboratory testing included moisture content determinations as well as measurements of unconfined compressive strength, by direct or indirect methods on portions of the cohesive soil samples. Selected samples were also tested to determine dry unit weight values. A sample of the shallow cohesive soil was also tested to determine Atterberg Limit values. All phases of the laboratory testing program were conducted in general accordance with applicable ASTM standards. The results of these tests are shown on the Boring Logs included in the Appendix.

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SUBSURFACE CONDITIONS

Borings B-2 and B-3 were drilled through the existing Portland cement concrete pavement adjacent to the west wall of the building. The concrete thickness at these locations ranges from approximately 0.7 foot to

1.3 feet. Borings B-1 and B-2 were drilled in grass covered areas where approximately one foot of topsoil was noted at the ground surface.

A layer of tough to very tough silty clay was encountered below the surface materials at each boring location. These cohesive soils generally have unconfined compressive strength values that range from

1.0 to 2.0 tons per square foot (tsf). Moisture content values are typically between 25 and 30 percent.

These soils were noted to a depth of approximately 5-1/2 feet.

Deposits of loose silt and/or soft to stiff silty clay were encountered below the near surface soils. These soils have Standard Penetration Test (N) values typically ranging from 4 to 7 blows per foot. The silty clay soils have unconfined compressive strength values that are generally below 1.0 tsf and as low as 0.5 tsf.

Corresponding moisture content values range from near 25 percent to slightly above 30 percent. Atterberg Limits testing on a sample obtained from a depth of approximately 10 feet indicate a liquid limit value of 38 and a plastic limit value of 24. These relatively low strength soils were found to a depth of approximately 23 feet.

Hard silty to sandy clay soils were found below a depth of 23 feet at each location. These soils have N values that are generally in excess of 50 blows per foot, unconfined compressive strength values in excess of 4.0 tsf and moisture content values that are generally at or below 10 percent. At Borings B-1 and B-2 these soils were found to the termination depth. Weathered shale was encountered at depths of approximately 34-1/2 and 33 feet at Borings B-3 and B-4, respectively. The weathered shale was sampled to the termination depth of both of these borings.

Free water was noted in the bore holes while drilling at depths ranging from approximately 28 to 13 feet.

It appears that this water is the result of seepage from the high moisture content clayey silt and silty clay deposits. Upon completion and removal of the augers, the water levels were on the order of 10 to 12 feet below the existing ground surface.

Springfield, Illinois L - 79,401 December 11, 2012

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ANALYSIS AND CONCLUSIONS

As previously noted, each of the soil borings revealed deposits of low strength clayey silt and or silty clay between depths of approximately 5-1/2 and 23 feet. Based upon unconfined compressive strength tests completed on samples of the cohesive soils, we estimate that the shear strength of these deposits is in the range of 500 to 700 pounds per square foot (psf). The typical foundation for the structure consists of an 8'-8" spread footing bearing at a depth of approximately 5 feet. Based upon these footing dimensions and the soil strength, the calculated theoretical net allowable bearing pressure is in the range of 1,200 to 1,700 psf. These values are somewhat below the design soil pressure of 2,000 psf noted on the foundation plans. Based upon this calculation, it appears that the bearing soils have been over stressed by the spread footings supporting the structure resulting in the observed settlement.

We have also performed a calculation to estimate the expected settlement of the foundations due to consolidation of the soft/loose soils under the foundation loads. This calculation was based upon an estimated coefficient of consolidation for the supporting soils based upon a correlation to the liquid limit value. Based upon this correlated value and the typical foundation dimensions and bearing depth, the estimated settlement using a 2,000 psf soil pressure is on the order of 4 inches.

Based upon the subsurface soil and groundwater conditions, it does not appear that there will be a total bearing capacity failure of the foundation of the building. However, given the history of the building, it is likely that there will be ongoing incremental movement of the supporting soils similar to what has occurred over the last several years. In order to minimize the potential for future movement, we expect that underpinning of the structure will be required to provide support on the undisturbed native soils below the depth of the compressible deposits. Based upon the subsurface conditions encountered in the borings, it appears that underpinning elements extending to and into the hard silty and sandy clay soils a depth of approximately 25 feet will be required. The underpinning system must be designed to resist the vertical loads transferred from the foundations. In order to minimize the potential for settlement, new foundations associated with the planned modifications should also extend to and into the hard clay soils.

Springfield, Illinois L - 79,401 December 11, 2012

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Any underpinning elements should be installed by contractors experienced in the design and construction of these types of structures. A licensed structural engineer should also be retained to evaluate the impact of any modifications to the existing building. We are available to assist in the design and provide recommendations regarding soil support values.

CLOSURE

The analysis and recommendations submitted in this report are based upon the data obtained from the four

(4) soil borings performed at the locations indicated on the Boring Location Plan included in the appendix of this report. This report does not reflect any variations which may occur between these borings, the nature and extent of which may not become evident until during the course of construction. If variations are then identified, the recommendations contained in this report should be reevaluated after performing on-site observations.

We are available to review this report with you at your convenience.

Douglas P. Ramsey Registered Professional Engineer Illinois No. 062-040905

APPENDIX

UNIFIED CLASSIFICATION CHART

LEGEND FOR BORING LOGS

BORING LOGS

BORING LOCATION PLAN

Dark brown clayey TOPSOIL (OL) Very tough brown-dark brown silty CLAY, trace sand, moist (CL)

Tough brown-dark brown-gray very silty CLAY, trace sand, very moist (CL)

Very loose gray-brown clayey SILT, trace sand, moist (ML)

Soft gray silty CLAY, trace sand and gravel, moist (CL)

Stiff to tough gray silty CLAY, trace sand and gravel, moist (CL)

Hard brown silty CLAY, little sand and gravel, moist (CL)

Hard gray sandy CLAY, little gravel, dry (CL)

End of Boring at 35.0'

* Approximate unconfined compressive strength based on measurements with a calibrated pocket penetrometer.

1.0

3.0

5.5

11.0

13.0

23.0

28.0

583.4

581.4

578.9

573.4

571.4

561.4

556.4

SS

SS

ST

SS

ST

SS

SS

SS

SS

SS

27.9

31.1

24.5

27.0

26.9

25.2

22.3

11.2

7.8

7.4

1.98 2.0*

0.95 1.0*

0.5*

0.82 0.75*

1.07 1.0*

4.37 4.5+*

4.5+*

4.5+*

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Repair Hanger P1 Building Envelope, Illinois Air National Guard, Springfield, I

28.0 '

B-1 L-79,401

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SAIC E.E.I., LLC, 622 Emerson Rd. Ste. 600, St. Louis, MO, 63141

Caved @ 10'549.4 approximate boundaries between soil types;

DATE STARTED

AT END OF BORING

DATE COMPLETED

SAMPLE

WC DRY DEPTHN

in-situ, the transition may be gradual.

Division lines between deposits represent

WATER TABLE

GROUND SURFACE

END OF BORING

WHILE DRILLING

JOB

24 HOURS

ELEV. SOIL DESCRIPTIONS

NO. TYPE

D I S T A N C E

B E L O W

S U R F A C E

I N

F E E T

L E N G T H

R E C O V E R Y

DRILL RIG NO.

PROJECT

CLIENT

BORING

ELEVATIONS

Qu

Concrete Pavement Tough brown-dark brown silty CLAY, trace sand, moist (CL)

Tough brown-gray silty CLAY, trace sand, moist (CL)

Loose gray-brown clayey SILT, trace sand, moist to very moist (ML)

Soft to stiff dark brown-gray silty CLAY, trace sand, moist (CL)

Stiff gray silty CLAY, trace sand, moist (CL)

Hard brown silty CLAY, little sand and gravel, moist (CL)

Hard gray sandy CLAY, little gravel, dry to moist (CL) strength based on measurements with a calibrated pocket penetrometer.

0.7

3.0

5.5

11.0

17.0

23.0

28.0

584.1

581.8

579.3

573.8

567.8

561.8

556.8

SS

SS

SS

SS

SS

SS

SS

SS

SS

SS

95.29

50/5"

26.1

25.3

26.5

30.7

26.4

27.1

25.7

11.2

8.0

10.8

1.5*

1.60 1.75*

0.70 0.5*

0.66 0.5*

0.82 0.75*

7.54 4.5+*

4.5+*

8.16 4.5+*

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Repair Hanger P1 Building Envelope, Illinois Air National Guard, Springfield, I

13.5 '

B-2 L-79,401

584.8

SAIC E.E.I., LLC, 622 Emerson Rd. Ste. 600, St. Louis, MO, 63141

10.0 '549.8 approximate boundaries between soil types;

DATE STARTED

AT END OF BORING

DATE COMPLETED

SAMPLE

WC DRY DEPTHN

in-situ, the transition may be gradual.

Division lines between deposits represent

WATER TABLE

GROUND SURFACE

END OF BORING

WHILE DRILLING

JOB

24 HOURS

ELEV. SOIL DESCRIPTIONS

NO. TYPE

D I S T A N C E

B E L O W

S U R F A C E

I N

F E E T

L E N G T H

R E C O V E R Y

DRILL RIG NO.

PROJECT

CLIENT

BORING

Concrete Pavement

Tough brown-dark brown silty CLAY, trace sand, moist (CL) Tough brown silty CLAY, trace sand, moist

(CL)

Loose gray-brown clayey SILT, trace sand, very moist to moist (ML)

Stiff brown silty CLAY, trace sand, moist

(CL)

Stiff gray-brown silty CLAY, trace sand, moist (CL)

Hard brown sandy CLAY, little gravel, moist

(CL)

Hard gray sandy CLAY, little gravel, dry to moist (CL)

Hard gray weathered SHALE

End of Boring at 35.0'

* Approximate unconfined compressive strength based on measurements with a calibrated pocket penetrometer.

1.3

3.0

6.0

13.0

18.0

23.0

28.0

34.5

583.7

581.9

578.9

571.9

566.9

561.9

556.9

550.4

SS

SS

SS

ST

SS

ST

SS

SS

SS

SS

96.07

26.6

25.1

29.9

25.1

26.7

26.7

26.1

9.7

9.3

10.1

1.5*

1.33 1.25*

0.75*

0.90 0.75*

4.5+*

4.44 4.5+*

4.63 4.5+*

11-26-12 11-26-12

Repair Hanger P1 Building Envelope, Illinois Air National Guard, Springfield, I

16.0 '

B-3 L-79,401

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12.0 '549.9 approximate boundaries between soil types;

DATE STARTED

AT END OF BORING

DATE COMPLETED

SAMPLE

WC DRY DEPTHN

in-situ, the transition may be gradual.

Division lines between deposits represent

WATER TABLE

GROUND SURFACE

END OF BORING

WHILE DRILLING

JOB

24 HOURS

ELEV. SOIL DESCRIPTIONS

NO. TYPE

D I S T A N C E

B E L O W

S U R F A C E

I N

F E E T

L E N G T H

R E C O V E R Y

DRILL RIG NO.

PROJECT

CLIENT

BORING

Dark brown clayey TOPSOIL (OL) Very tough brown-dark brown silty CLAY, trace sand and gravel, moist (CL)

Hard brown-gray silty CLAY, trace sand and gravel, moist (CL)

Soft brown silty CLAY, trace sand, very moist (CL)

Stiff brown very silty CLAY, trace sand, moist

(CL)

LL = 38 PL = 24

Stiff gray-brown silty CLAY, trace sand, moist (CL)

Tough brown silty CLAY, trace sand and gravel, moist (CL)

Hard brown silty CLAY, little sand and gravel, moist (CL)

Hard gray sandy CLAY, little gravel, dry (CL)

Hard gray weathered SHALE strength based on measurements with a calibrated pocket penetrometer.

1.0

3.0

5.5

8.0

11.0

18.0

23.0

28.0

33.0

583.7

581.7

579.2

576.7

573.7

566.7

561.7

556.7

551.7

SS

ST

SS

ST

SS

SS

SS

SS

SS

SS

102.98

50/5"

21.5

16.6

31.2

27.9

28.2

28.6

24.4

11.6

8.4

10.6

2.25*

4.5+*

0.53 0.5*

0.75*

0.78 0.75*

0.82 0.75*

1.11 1.0*

4.72 4.5+*

14.31 4.5+*

11-27-12 11-27-12

Repair Hanger P1 Building Envelope, Illinois Air National Guard, Springfield, I

13.0 '

B-4 L-79,401

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SAIC E.E.I., LLC, 622 Emerson Rd. Ste. 600, St. Louis, MO, 63141

12.0 '549.7 approximate boundaries between soil types;

DATE STARTED

AT END OF BORING

DATE COMPLETED

SAMPLE

WC DRY DEPTHN

in-situ, the transition may be gradual.

Division lines between deposits represent

WATER TABLE

GROUND SURFACE

END OF BORING

WHILE DRILLING

JOB

24 HOURS

ELEV. SOIL DESCRIPTIONS

NO. TYPE

D I S T A N C E

B E L O W

S U R F A C E

I N

F E E T

L E N G T H

R E C O V E R Y

DRILL RIG NO.

PROJECT

CLIENT

BORING