W912P523B0003 TSpecsAppB Geotechnical Exploration Report.pdf

Report of Geotechnical Exploration

K-25 Museum

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

Prepared for:

M&W Drilling

8321 Oak Ridge Highway

Knoxville, Tennessee 37931

Prepared by:

S&ME, Inc.

1413 Topside Road

Louisville, Tennessee 37777

October 23, 2015

K-25 Musuem

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 ii

Table of Contents

1.0 Executive Summary

2.0 Introduction

2.1 Purpose

2.2 Site and Project Description

2.2.1 Site Description

2.2.2 Project Description

2.3 Scope of Services

3.0 Exploration and Testing

3.1 Field Exploration

3.2 Laboratory Testing

4.0 Subsurface Conditions

4.1 Site Geology

4.2 Subsurface Conditions

4.2.1 Surficial

4.2.2 Existing Fill Soil

4.2.3 Residual Soil

4.2.4 Refusal Materials

4.2.5 Ground Water

5.0 Laboratory Testing and Discussion of Results

5.1 Index Properties

5.2 Moisture-Density Relationship (Modified)

5.3 Triaxial Shear

5.4 Unconfined Compressive Strength of Soil

5.5 One-dimensional Consolidation

6.0 Site Assessment

6.1 General

6.2 Shallow Foundation Support on Existing Fill and Firm Residual Soil

6.3 Use of Existing Fill Soil and Borrow Materials as Structural Fill

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 iii

7.0 Recommendations

7.1 General

7.2 Shallow Foundation Recommendations

7.3 Mat Foundations and Concrete Slabs-On-Grade

7.4 Pavement Recommendations

7.4.1 Flexible Pavement

7.4.2 Rigid Pavement

7.4.3 General

7.5 Subsurface Wall Recommendations

8.0 Construction Considerations

8.1 Site Preparation

8.2 Engineered (Soil) Fill

8.3 Dense-Graded Aggregate Fill

8.4 Moisture Sensitive Soils

8.5 Drainage and Surface Water Concerns

9.0 Limitations

List of Figures Figure 1 Site Vicinity Map ......................................................................................................Appendix I

Figure 2 Boring Location Plan................................................................................................Appendix I

Figure 3A Geologic Map .........................................................................................................Appendix I

Figure 3B Geologic Map..........................................................................................................Appendix I

Figure 4A Subsurface Profile A-A’ ........................................................................................Appendix I

Figure 4B Subsurface Profile B-B’ ..........................................................................................Appendix I

Figure 4C Subsurface Profile C-C’.........................................................................................Appendix I

Figure 4D Subsurface Profile D-D’ ........................................................................................Appendix I

Figure 4E Subsurface Profile E-E’ ..........................................................................................Appendix I

Figure 5 Typical Retaining Wall Backfill Detail...................................................................Appendix I

List of Tables Table 4-1

Table 4-2

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 iv

Appendices Appendix I – Figures, Boring Logs, and Subsurface Profile Sections.........................................................ii

Appendix II – Laboratory Test Procedures and Test Results .................................................................... iii

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 1

1.0 Executive Summary

S&ME has completed the geotechnical exploration for the proposed K-25 Museum located at the U.S.

Department of Energy’s East Tennessee Technology Park (ETTP) in Oak Ridge, Tennessee. The purpose of this exploration was to characterize the site subsurface conditions and to provide geotechnical recommendations for general site preparation, excavation and fill requirements, and design and construction of shallow foundations, including allowable soil bearing pressure.

Published geologic information indicates the site is underlain by bedrock from the Cannon Limestone and

Catheys Formation’s of the Chickamauga Group located within the Appalachian Valley and Ridge

Physiographic Province of east Tennessee. The geotechnical exploration included the drilling of a total of

9 soil test borings (Borings B-1 through B-4 and B-6 through B-10) within the proposed construction area.

The soil borings were extended to auger refusal or boring termination depths, which varied from 51.5 to

65.7 feet and 10 to 81.5 feet below the ground surface, respectively. The results of our exploration generally indicate the site is underlain by existing fill and residual soil. A discussion of the project and the materials encountered in the borings, as well as the results of laboratory testing, is presented in this report.

Portions of the onsite existing fill and residual materials generally appear suitable for reuse as new fill provided the recommendations presented herein are implemented during construction. Soft to firm soils should be identified and support conditions corrected where these materials are encountered at the foundation bearing or subgrade elevation using the methods described in this report.

Considering the nature of the proposed project and the subsurface data obtained, it is our opinion the site is suitable for the proposed construction. Recommendations for subgrade preparation are provided in the following sections of this report. This summary provides an overview and should not in any way be considered a substitute for the thorough review of the detailed sections of this report.

2.0 Introduction

2.1 Purpose

The purpose of this exploration was to characterize the site subsurface conditions and to provide geotechnical recommendations for general site preparation, excavation and fill requirements, and design and construction of shallow foundations, including allowable soil bearing pressure. A geotechnical exploration program consisting of soil test borings was used to assess the subsurface conditions.

2.2 Site and Project Description

2.2.1 Site Description

The site of the proposed K-25 Museum is located at the U.S. Department of Energy’s East Tennessee

Technology Park (ETTP) in Oak Ridge, Tennessee. Please see Figure 1 (Appendix I) for the approximate location of the site.

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 2

More specifically, the project site is situated at the former location of the K-25 Gaseous Diffusion Process

Facility and generally lies south of the former K-25 Building, and west and northwest of the existing K-1652

(Fire Station) Building. Based on the preliminary architectural site layout and grading plan, the project site is approximately 3.5 acres in size and varies in elevation from about 780 ft, msl, in the low-lying, western portion of the site, to about 788 ft, msl, at the northwest corner of the K-1652 Fire Station Building in the eastern portion of the site, to about 796 ft, msl, at the higher, central portions of the site. An existing retaining wall extends from its maximum height of approximately 10 feet at the northwest corner of the K-

1652 Fire Station Building to the west for approximately 85 feet. Currently, the site consists of relatively level grassed and paved areas.

2.2.2 Project Description

Project information was provided during telephone conversations and in email correspondence dating from

August 20, 2015 by Ms. Teresa Pierce of URS/CH2M Oak Ridge, LLC (UCOR). We were provided the following drawings and reports via email:

Report of Subsurface Investigation for Plant Protection Building K-1652, dated December 27, 1979.

Drawing C1E700000B276 Revision 1, Proposed Equipment Building Site Plan, dated May 18, 2015.

A Topographic Survey drawing of the proposed site.

50% Final Preliminary Design Report, Design and Museum Professional Services for ETTP Site

Interpretation and K-25 Historic Preservation, dated June 24, 2015.

Drawing No. C1 Revision C, Site Layout and Paving Plan, dated July 26, 2015.

Drawing No. S110 Revision C, Equipment Building/Viewing Tower – Ground Level/Foundation

Plan, dated July 24, 2015.

Drawing No. L103 Revision C, Equipment Building/Viewing Tower Planting Plan, dated July, 26, 2015.

Drawing No. C401 Revision C, Site Grading and Stage 2 Erosion Prevention and Sediment Control

Plan, dated August 8, 2015.

The proposed K-25 Museum will communicate the undertaking of the Manhattan Project during World War II and will consist of three main components: (1) the renovation of the 2nd floor of the K-1652 Fire Station

Building with new museum exhibits; (2) the construction of an Equipment Building and Viewing Tower which will illustrate a representation of the K-25 uranium processing systems at full scale and provide panoramic views of the former K-25 Building footprint; and (3) site development which includes landscaping, sidewalks, parking, and associated wayside exhibits. The geotechnical exploration conducted at the site was performed to support the design and construction of the Equipment Building and Viewing Tower and the site development.

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 3

At the time of our report, a proposed grading plan was provided to us with respect to preliminary design activities. Based on this drawing it is anticipated up to 3 feet of fill (just west of the K-1652 Building) and little to no excavation are planned for site development.

The 3-story Equipment Building will consist of steel frame construction and is proposed to be supported on a system of shallow spread and continuous footings with concrete slab-on-grade. The approximate 50 foot tall

Viewing Tower will be included in the steel frame construction, consisting of an elevator and stairwell constructed with reinforced concrete shear walls that is proposed to be supported on a mat foundation. The planned finish floor elevation (FFE) for the Equipment Building is 796.0 feet, msl. At the time of report preparation, structural loading information was not provided to us; however we assume maximum loads on isolated spread footings or thickened sections of a slab will not exceed about 150 to 200 kilo-pounds (kips).

2.3 Scope of Services

This geotechnical exploration involved geotechnical drilling and sampling, geotechnical laboratory testing, and engineering analyses. The following sections of this report present discussions of the field exploration, laboratory testing, site conditions, and conclusions and recommendations. The figures and boring logs are provided in Appendix I, while the laboratory test results are provided in Appendix II.

The scope of services for this project did not include an environmental assessment for determining the presence or absence of wetlands, or hazardous or toxic materials in the soil, bedrock, surface water, subsurface water, or air, on, or below, or around this site. Any statements in this report or on the boring logs regarding odors, colors, and unusual or suspicious items or conditions are strictly for informational purposes only.

3.0 Exploration and Testing

3.1 Field Exploration

The subsurface conditions were explored with 9 soil test borings located within the proposed construction area (see Figure 2, Boring Location Plan). The boring locations were selected by representatives of UCOR and staked in the field by representatives of UCOR prior to our arrival on site.

Drilling was performed from August 18 to September 1, 2015, by M&W Drilling Inc. The borings were advanced using 3.25-inch inside diameter hollow stem augers (HSA) and a Geoprobe® 7730 DT drill rig. The drill crew worked in general accordance with ASTM D6151 (HSA Drilling). Sampling of overburden soils was accomplished using the standard penetration test procedure (ASTM D1586), relatively undisturbed Shelby tube samples (ASTM D1587), and by obtaining bulk samples of the augered soil cuttings at select intervals.

The soil test borings were backfilled with the soil cuttings produced during the drilling activities at the completion of sampling.

3.2 Laboratory Testing

After completion of the field exploration and sampling phase of this project, the soil samples were transported to our laboratory where they were visually classified by a member of our geotechnical staff.

Samples were selected and tested for natural moisture content (ASTM D2216), Atterberg limits (ASTM

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 4

D4318), modified Proctor moisture-density relationship testing (ASTM D1557), unconfined compression

(ASTM D2166), unconsolidated undrained (UU) triaxial compression (ASTM D2850), and one-dimensional consolidation (ASTM D2435). The results of the laboratory testing are discussed in Section 5.0 of this report. The laboratory test data sheets are found in Appendix II.

4.0 Subsurface Conditions

4.1 Site Geology

The site, and most of east Tennessee, lies in the Appalachian Valley and Ridge Physiographic Province.

The Province is characterized by elongated, northeasterly-trending ridges formed on highly resistant sandstones and shales. Between ridges, broad valleys and rolling hills are formed primarily on less resistant limestones, dolomites and shales.

We researched three main sources regarding the geology at this site. The first source was a publication from the State of Tennessee, Department of Conservation, Division of Geology titled Geologic Map of East

Tennessee, Bulletin 58, Plate 8, Loudon, dated 1956. The second source was a publication authored by P. J.

Lemiszki titled Geological Mapping of the Oak Ridge K-25 Site, Oak Ridge, Tennessee, issued January 1994.

The third source was a publication from the United States Department of Energy (DOE) titled

Environmental Assessment, Transfer of Land and Facilities within the East Tennessee Technology Park and

Surrounding Areas, Oak Ridge, Tennessee, DOE/EA-1640, issued October 2011.

The Geologic Map of East Tennessee indicates the site is underlain by the lower and middle parts of the

Chickamauga Limestone. More recently, the Chickamauga Limestone is most often referred to as the

Chickamauga Group or Supergroup, as it is comprised of numerous formations which predominate different elevations in the group. Generally speaking, the Chickamauga Group is comprised primarily of limestone with minor amounts of shale. The Chickamauga Group generally weathers to produce a medium to high plasticity clay soil. Silica in the form of chert is resistant to weathering and scattered throughout the residuum.

Lemiszki’s publication on the geology of this site goes in to more detail about the Chickamauga

Supergroup, as the author refers to it. Based on additional geologic mapping at the site, this portion of K-

25 was actually situated along the axis of an east-west oriented syncline as shown in the following geological cross section from the publication. The Cannon Limestone and Catheys Formation are poorly exposed and only exist in the minor syncline in the middle of the former K-25 Facility.

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 5

Section B-B’ – Excerpt from Figure 8, Page 20 of Lemiszki’s Geological Mapping of the Oak Ridge K-

25 Site.

The DOE’s Environmental Assessment contains a summary of the existing geologic conditions at the site. It confirms the site is underlain by the Cannon Limestone and Catheys Formation of the Chickamauga

Group. It also addresses the degree of karst development between groups and formations with the greatest activity noted in the Knox Group and to a lesser extent in the Chickamauga Group. There are numerous faults mapped at the K-25 facility, but they are no longer active with the most recent fault movements likely occurring over 200 million years ago.

Lemiszki provides detailed descriptions of the Cannon Limestone and Catheys Formation, which are paraphrased here. The Cannon Limestone is commonly dark gray, thick to massive beds with some thin beds. Fossils are found in varying quantities throughout the formation. Chert is rare but stylolites are common. The Catheys Formation is medium to dark gray, thin to thick bedded, occasionally coarse grained limestone with shale seams and partings. Some beds are very fossiliferous. The upper part of the formation is interbedded with calcareous, green and red shales. Chert and siltstone fragments are common in the overburden soils.

Since the bedrock underlying this site contains carbonate rock (i.e., limestone/dolomite), it is susceptible to the hazards of irregular weathering, cave and cavern conditions, and overburden sinkholes. Carbonate rock, while appearing very hard and resistant, is soluble in slightly acidic water. This characteristic, plus differential weathering of the bedrock mass is responsible for these hazards. Of these hazards, the occurrence of sinkholes is potentially the most damaging to overlying soil-supported structures.

Sinkholes occur primarily due to differential weathering of the bedrock and flushing or raveling of overburden soil into the cavities within the bedrock. This loss of solids creates a cavity, or dome, in the overburden. Growth of the cavity over time, or excavation over the dome, can create a condition in which rapid subsidence, or collapse, of the roof of the dome occurs.

A certain degree of risk with respect to sinkhole formation and subsidence should be considered at any site located within carbonate geologic settings. Several closed depressions, which can be indicative of past sinkhole activity, were observed on the United States Geological Survey (USGS – Elverton Quadrangle, TN) topographic map to the south and west of the site. However, subsurface conditions encountered in the borings were not indicative of sinkhole formation (i.e., relatively thick intervals of very soft, saturated soils

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 6 immediately above bedrock). In addition, the surrounding structures at the K-25 facility appear to have performed adequately over time.

It is our opinion the risk of sinkhole development at this site is comparable to other sites located within similar geologic settings which have been developed successfully. However, the owner must be willing to accept the risk of future sinkhole development at this site. The risk of sinkhole development can likely be reduced by following the recommendations provided in the following sections of this report.

4.2 Subsurface Conditions

The subsurface conditions at the site of the proposed K-25 Museum facility were explored with 9 soil test borings (Borings B-1 through B-4 and B-6 through B-10). We understand proposed Boring B-5 was deleted from the field exploration program after the proposed footprint of the proposed K-25 Museum was moved to the east. The locations for the borings were provided by UCOR representatives and established in the field by their representatives (see Figure 2). Ground surface elevations were interpolated from contour plots on drawings provided by UCOR.

Subsurface conditions encountered at each boring location are shown on the boring logs in Appendix I.

Figures 4A, 4B, 4C, 4D, and 4E also contain subsurface profile sections which graphically show the subsurface conditions at selected locations. The boring logs represent our interpretation of the subsurface conditions, based on the field logs and visual examination of the samples by one of our geotechnical professionals. The lines designating the interfaces between various strata on the boring logs represent the approximate interface locations. The ground water levels provided on the logs correspond to levels at the time of boring (i.e., when first encountered) and after 24 hours. Ground surface elevations provided on the boring logs should be considered approximate. A summary of the boring depths is presented in Table 4.1.

Table 4-1

Boring Summary

Boring

I.D.

Ground

Surface

Elevation, msl (feet)

K-25 Plant Boring Coordinates Auger Refusal / Boring

Termination Depth

(feet)

Auger Refusal /

Boring Termination

Elevation, msl (feet)South West

B-1 796.0 264+96 1074 W 57.0 (1) 739.0

B-2 796.0 264+96 1024 W 65.7 (1) 730.3

B-3 796.0 265+26 1074 W 61.7 (1) 734.3

B-4 796.0 265+26 1024 W 51.5 (1) 744.5

B-6 793.5 265+72 1204 W 61.5 (1) 732.0

B-7 796.0 265+72 1024 W 81.5 (2) 714.5

B-8 795.0 266+65 1125 W 10.0 (2) 785.0

B-9 796.0 266+65 1000 W 10.0 (2) 786.0

B-10 795.5 267+25 1040 W 10.0 (2) 785.5

Notes: Coordinates are from the K-25 Plant Coordinate System.

(1) Auger Refusal

(2) Boring Termination

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 7

The subsurface descriptions are of a generalized nature to highlight the major subsurface stratification features and material characteristic at the boring locations. The boring logs included in Appendix I should be reviewed for specific information at individual boring locations. Information on actual subsurface conditions exists only at the specific boring locations and is relevant to the time the exploration was performed. Variations may occur and should be expected between boring locations.

The test borings performed at this site typically encountered fill and residual soil. Fill soil is soil that has been transported to its present location by man. Residual soil is soil that has developed from the in-place weathering of the underlying parent bedrock.

4.2.1 Surficial

Borings B-1, B-2, B-3, B-4, B-7, and B-10 encountered a surficial layer of asphalt and crushed stone aggregate approximately 3 inches and 9 inches in thickness, respectively. Borings B-6, B-8, and B-9 encountered a thin surficial topsoil layer which ranged from about 2 to 3 inches in thickness.

4.2.2 Existing Fill Soil

Underlying the veneer of surface materials fill soil was encountered in all of the borings. The fill typically ranged in thickness from about 0.5 (Boring B-2) to 6.3 feet (Boring B-6) and extended to depths varying from about 1.5 (Boring B-2) to 6.5 feet (Boring B-6) below the ground surface. The fill soil typically consisted of brown, red, yellow, and gray fat clay with varying percentages of weathered shale, chert, and limestone fragments. Occasional fine roots and coal fragments were also observed in the fill. The moisture condition of the fill soil was typically slightly moist to moist, however some intervals were observed to be wet (Boring B-7).

The SPT N-values used to evaluate the consistency of the fill ranged from 5 to 35 blows per foot, indicating consistencies ranging from firm to hard. The lower consistency materials (i.e., N-values of 5 to

6) were encountered in the upper approximately 3 to 6.5 feet in Borings B4, B-6, B-7, and B-10. We note that the blow counts in the fill were likely amplified due to the presence of rock fragments within the sample intervals.

4.2.3 Residual Soil

Residual soil was encountered underlying the fill soil in the borings. Residual soils are derived from the in-place weathering of the parent bedrock. The residual soil at this site consisted of various hues of brown, yellow, red, and gray fat to silty clays and silts with varying percentages of weathered shale fragments, chert fragments, black manganese nodules, and staining. Occasional intervals of preserved relict bedding were observed in the higher consistency residuum.

The SPT N-values used to evaluate the consistency of the residuum ranged from 1 to over 50 blows per foot, indicating consistencies ranging from very soft to very hard. The lower consistency materials were encountered at depths greater than 50 feet below ground surface in Borings B-1 (N-value of 5), B-2 (N-values of 1 and 4), and B-3 (N-value of 3). The higher consistency materials were encountered at depths corresponding to auger refusal in Borings B-2 and B-4. Typically, the residuum was firm to very stiff in consistency.

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 8

4.2.4 Refusal Materials

Auger refusal was encountered in Borings B-1 through B-6 at depths varying from about 51.5 to 65.7 feet below ground surface. Auger refusal is a designation applied to any material that cannot be penetrated by the power auger used to drill the borings.

Refer to Table 4-1, which provides the refusal depths encountered in the borings as well as the boring termination depths.

4.2.5 Ground Water

Ground water levels were measured in all of the soil test borings (except Boring B-3) at the time of boring

(i.e., when first encountered during the advancement of the boring). Further, ground water measurements were obtained approximately 24 hours after the completion of drilling in all the borings except Boring B-3, B-8, B-9, and B-10. The recorded ground water levels are presented in Table 4-2 and on the boring logs.

Table 4-2

Ground Water Data Summary

Boring

I.D.

Ground

Surface

Elevation, msl (feet)

Depth to

Ground Water at Time of

Boring (feet)

Ground Water

Elevation at Time of Boring, msl

(feet)

Depth to Ground

Water After 24

Hours (feet)

Ground Water

Elevation After 24

Hours, msl (feet)

B-1 796.0 30.0 766.0 20.0 776.0

B-2 796.0 40.0 756.0 21.0 775.0

B-3 796.0 N.R. -- N.R. --

B-4 796.0 40.0 756.0 23.5 772.5

B-6 793.5 40.0 753.5 20.0 773.5

B-7 796.0 40.0 756.0 21.4 774.6

B-8 795.0 N.E. -- N.R. --

B-9 796.0 N.E. -- N.R. --

B-10 795.5 N.E. -- N.R. --

Notes:

N.E. – Not Encountered

N.R. – Not Recorded

Ground water levels may fluctuate due to seasonal changes in precipitation amounts, construction activities in the area, the level of nearby water features, and/or other factors. The ground water information presented in this report is the information collected at the time of our field activities.

5.0 Laboratory Testing and Discussion of Results

This section describes the geotechnical laboratory testing program and summarizes the test results. The laboratory testing procedures and laboratory test results are included in Appendix II. The laboratory tests were performed on split-soon, relatively undisturbed Shelby tube, and bulk soil samples obtained during

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 9 the field exploration. The following paragraphs provide a short discussion of the general types of testing conducted and the test results.

5.1 Index Properties

Natural moisture contents, liquid limit, plastic limit, and plasticity index tests (collectively referred to herein as Atterberg limits) were performed on selected split-spoon, bulk, and relatively undisturbed

Shelby tube samples. These tests were used to confirm our visual-manual classifications and classify the triaxial and consolidation test samples, as well as the potential on-site borrow soil samples.

The natural moisture contents of the soils which were tested ranged from 25.0 percent (B-6, 1.0 to 5.0 ft) to 37.4 percent (B-3, 15.0 to 17.0 ft).

Liquid limits for the soil samples tested ranged from 47 to 71; plastic limits ranged from 23 to 37; and plasticity indices ranged from 18 to 40. The tested soils were classified as ML, MH, and CH in accordance with the Unified Soil Classification System (USCS) based on Atterberg limits testing only.

A summary of the index property test results are found in Table II-1. The Atterberg limits test reports are found in Appendix II.

5.2 Moisture-Density Relationship (Modified)

Two modified Proctor moisture-density relationship tests (ASTM D1557) were performed on bulk samples of soil obtained from Borings B-8 and B-10. The results are summarized in Table II-1 in Appendix II.

Maximum dry densities of the tested samples were 110.6 and 111.8 pounds per cubic foot (pcf) with corresponding optimum moisture contents of 17.3 and 17.2 percent, respectively. The natural moisture content of the tested samples obtained from Borings B-8 and B-10 were 33.2 and 33.6 percent, respectively. The natural moisture content of the bulk soil sample tested from Boring B-8 was about 15.9 percent above optimum moisture content, while the natural moisture content of the bulk soil sample tested from Boring B-10 was about 16.4 percent above optimum moisture content.

5.3 Triaxial Shear

The triaxial shear test results are summarized in Table II-2 in Appendix II. Three unconsolidated-undrained triaxial shear strength tests (ASTM D 2850) were performed on relatively undisturbed Shelby tube sample specimens to estimate the shear strength of the on-site foundation soils. The total stress parameters were used to estimate the tested soils short-term undrained shear strength. The total stress cohesion intercepts for the samples tested under unconsolidated-undrained conditions varied from 1.46 to 2.96 kips per square foot (ksf) and total stress friction angles varied from 1.5 to 21.6 degrees.

One triaxial Q-test was performed on a specimen obtained from Boring B-7, 5.0 to 7.0 ft. The specimen was tested at a confining pressure which approximated the in-situ effective overburden pressure on the sample as it existed in the ground. The undrained shear strength of the tested specimen was 1.36 ksf.

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 10

5.4 Unconfined Compressive Strength of Soil

A total of eight unconfined compressive strength of soil tests (ASTM D 2166) were performed on relatively undisturbed samples. The results of the unconfined compressive strength tests performed indicated that the tested samples had unconfined compressive strengths ranging from 1.80 to 5.60 ksf.

A summary of the unconfined compressive strength test results are found in Table II-2. The unconfined compressive strength test reports are found in Appendix II.

5.5 One-dimensional Consolidation

Three one-dimensional consolidation tests (ASTM D 2435) were performed on relatively undisturbed soil samples obtained from borings across the proposed site. The test results indicated that the samples tested had a “laboratory” compression index ranging from 0.17 to 0.31. The recompression index ranged from 0.014 to 0.040. The preconsolidation pressure for all samples tested varied from 4.0 to 5.2 ksf. A summary of the consolidation test results are found in Table II-3. The consolidation test reports are found in Appendix II.

6.0 Site Assessment

6.1 General

The conclusions and recommendations presented in this report are based on the preceding project information and the results of this exploration. Actual subsurface conditions may vary between or away from the soil boring locations. If it becomes apparent during construction that the conditions encountered vary substantially from those presented herein, this office should be notified at once. At that time, S&ME should be retained to evaluate and modify the recommendations of this report, if necessary.

Also, if the scope of the project should change significantly from that described herein, these recommendations may have to be reevaluated.

This exploration was performed to provide information for the construction of the proposed K-25

Museum.

6.2 Shallow Foundation Support on Existing Fill and Firm Residual Soil

Existing fill materials were encountered to depths of 1.5 to 6.5 feet below the existing ground surface in the borings. The fill contained chert fragments, limestone fragments, weathered shale fragments, coal fragments, and fine roots and was sometimes of lower consistency. Further, the blow counts in the fill were likely amplified due to the presence of rock fragments within the sample intervals. Given the variable materials within the fill and the variable consistency, it is not likely the material was placed in a controlled manner for direct foundation support.

As is the case with any fill placed without technical observations, the possibility exists that the fill may contain concentrated amounts of deleterious material and soft compressible zones not disclosed by our borings. Accordingly, there are certain risks associated with construction on these types of fill. The risk primarily consists of excessive and/or non-uniform settlement caused by zones or pockets of soft, loose, Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 11 or uncompacted material. Therefore, we do not recommend shallow foundations or slabs-on-grade derive their support by bearing in uncontrolled fill for structures proposed for the K-25 Museum.

Zones of firm residual soil were encountered in Borings B-2 and B-6 at the existing fill/residual soil interface. Firm residual soils are likely of lower strength and higher compressibility than the stiff, or better, residual soils encountered in the borings.

To reduce the risk associated with shallow foundation or slab-on-grade support on the uncontrolled fill or firm residuum, we recommend undercutting the fill and firm residuum to the underlying stiff residuum and bringing the site back to grade using engineered (soil) fill or dense graded aggregate. Lower consistency soil zones should be recognized during site development, proofrolling operations, or foundation subgrade evaluations.

The uppermost zones of firm residuum were encountered to depths ranging from approximately 3.0 feet

(Boring B-2) to 13.0 feet (Boring B-6) below the ground surface. These soils were observed to be in the upper range of firm consistency with N-values of 8 bpf. Boring B-2 was drilled near the proposed Viewing

Tower elevator and associated elevator pit. Firm residual soils in this area will likely be excavated during the elevator pit construction. Near Boring B-6 we understand that a single line of spread footings supporting “unfinished structural steel beams” are planned for the westernmost part of the Equipment

Building. We anticipate low applied foundation pressures for these footings. Undercutting of firm residual soils in this area can be reduced or eliminated if a minimum of 5 feet of newly compacted engineered soil fill or dense graded aggregate is provided for support below the foundation bearing elevation of these footings. These support conditions should sufficiently meet the recommendations for bearing capacity and settlement provided later herein.

Recommendations for design and construction of shallow foundations are included in Section 7.0 of this report. Proofrolling to identify soft to firm subgrade soils is discussed in Section 8.1 of this report.

6.3 Use of Existing Fill Soil and Borrow Materials as Structural Fill

Select intervals of excavated existing fill soil may be considered for re-use as newly compacted structural soil fill as long as the recommendations provided for engineered soil fill (reference Section 8.2) are met.

Adjustments to soil moisture will likely be necessary to bring the soil to the acceptable level for adequate compaction. This is a function of the weather conditions at the time of fill placement, and the grading contractor should anticipate this task. We note that some of the existing fill materials tested as part of this exploration had PI values in excess of 35 percent, were wet, and contained varying percentages of weathered shale, chert, and limestone fragments with occasional fine roots and coal fragments. Materials removed from the proposed building or pavement areas, or otherwise undercut, should be evaluated during excavation to assess whether they are suitable for reuse. Excavated fill materials that do not meet our requirements for structural soil fill should not be used as new fill to support structures or pavements;

however, may be used to raise grades in non-structural areas.

Contingency monies for offsite borrow soils or dense-graded aggregate for use as new fill should be included as a part of the site preparation budget. The Geotechnical Engineer should evaluate these soils to determine their suitability prior to grading. This evaluation should include standard or modified Proctor compaction, Atterberg limits, and grain size distribution. Recommendations for site preparation, engineered (soil) fill, and dense graded aggregate are provided in Sections 8.1, 8.2, and 8.3, respectively.

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 12

7.0 Recommendations

7.1 General

The following recommendations assume the Equipment Building and Viewing Tower structures will be relatively moderately loaded, having maximum loads on isolated spread footings or thickened sections of a slab of about 150 to 200 kips, or less. Our recommendations also assume site development will require up to 3 feet of fill and little to no excavation.

7.2 Shallow Foundation Recommendations

Considering the nature of the proposed project and the subsurface data obtained, it is our opinion that the use of a shallow foundation system to support the proposed structure(s) is appropriate. Shallow foundations bearing on stiff or harder residual soil or new well-compacted structural fill are recommended for support of the proposed structure(s). After the site is properly prepared in accordance with our recommendations, soil supported foundations may be sized for a maximum allowable soil bearing pressure of 2,500 pounds per square foot (psf). Undercutting and replacement of lower consistency residual soil will be required if encountered in foundation excavations.

Even if the design loads would allow smaller sizes, we recommend all isolated spread foundations be a minimum of 24 inches wide to reduce the possibility of a localized punching shear failure. All foundations should be designed to bear at least 18 inches below finished exterior grade to develop the design bearing pressure and to protect against frost heave.

We have estimated settlement of the proposed foundations using the data obtained from this exploration, considering an applied pressure of approximately 2,500 psf, and assuming foundations bearing on excavations prepared as recommended. The results of our analysis indicate maximum total settlements ranging from about 0.75 to 1.25 inches and maximum differential settlements of about 0.5 to

0.75 inches.

Lateral capacity of footings includes a soil lateral pressure and coefficient of friction as described in the

2012 IBC Section 1806. Soil supported foundations will be embedded in material similar to those described as Class 5, as described in Table 1806.2. Where footings are cast neat against the sides of excavations in natural soils or properly compacted fill, an allowable lateral bearing pressure of 100 psf per foot depth below natural grade may be used in computations. An allowable sliding resistance of 130 psf may be used for clays and silts similar to those described as soil Class 5. An increase of one-third in the allowable lateral capacity may be considered for load combinations, including wind or earthquake, unless otherwise restricted by design code provisions.

S&ME should be retained to perform foundation excavation observations at the time of construction to confirm the recommendations provided in this report are consistent with the conditions encountered. A dynamic cone penetrometer (DCP) is commonly utilized to provide information that is compared to the data obtained in the geotechnical report. Where unacceptable materials are encountered, the material should be excavated to stiff, suitable soils or remediated at the Geotechnical Engineer's direction.

At this site, it is anticipated some lower consistency (i.e. soft to firm) soil may be encountered in foundation excavations where not removed as part of general site grading. Where encountered, these

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 13 materials should be undercut to the underlying stiff residuum. The undercut excavation should extend laterally beyond the outside edge of the foundation for a distance equal to at least one-half of the depth of undercut below the foundation bearing elevation. The excavation may then be backfilled using compacted engineered (soil) fill, compacted dense-graded aggregate, or flowable fill.

Foundation excavations should be opened, evaluated, remedial work performed, and concrete placed in an expeditious manner. Exposure to weather often reduces foundation support capabilities, thus necessitating remedial measures prior to concrete placement. It is also important that proper surface drainage be maintained both during (especially in terms of maintaining dry foundation excavations) and after construction.

7.3 Mat Foundations and Concrete Slabs-On-Grade

Based on the soil types encountered by our exploration, mat foundation and concrete slab-on-grade construction may be supported on evaluated and approved residual soil or newly placed, properly compacted structural soil fill that proofrolls successfully. Undercutting and replacement of lower consistency residual soil will be required if exposed at the subgrade elevation.

Based upon the assumption that approved residual soil or newly placed compacted structural soil fill will be used for support of the mat foundation/floor slab, we recommend the mat foundation/floor slab be designed using a subgrade soil modulus of 100 pounds per cubic inch (pci). This value is for small diameter loads (i.e., a 1 foot by 1 foot plate) and should be adjusted for wider loaded areas. To provide a level of soil subgrade protection from weather related deterioration, we suggest a 4-inch thickness of compacted dense graded aggregate (Section 8.3).

Based on the results of our exploration, mat foundation or grade slabs would not be subjected to hydrostatic pressure from ground water. Even though the bottom of the slab will not be exposed to hydrostatic pressure, vapor penetration of the slab may be a design consideration.

Surface drainage should be controlled during construction to prevent excessive surface water drainage beneath completed mat foundations or slabs. Immediately prior to placement of dense-graded aggregate stone base material and concrete, the subgrade should be proofrolled to detect subgrade areas that may have softened, loosened, or otherwise been disturbed by construction activities or weather. The proofroll should be observed by a staff professional or senior technician under the direction of the Geotechnical

Engineer. Areas found to deflect excessively should be repaired.

The above discussion provides information for support and construction of mat foundation or grade slabs at the site. The mat foundation/floor slab design (performed by others) should also address slab thickness, subbase, strength, jointing, curing, surface finish, flatness/levelness, and any floor finish system requirements.

Due to the likelihood of fine-grained soils (i.e., clays and silts) being used as structural soil fill in the construction area, the mat foundation/floor slab subgrade should not be allowed to dry during construction. If these soils become dry and are exposed to free moisture, they can swell and crack the slab. For this reason, we recommend that soils beneath mat foundations, floor slabs, and pavement be compacted and maintained throughout construction at their optimum moisture content or slightly above.

The subgrade should be retested just prior to placing granular base material.

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 14

7.4 Pavement Recommendations

Based on the Civil Design Narrative provided in the 50% Final Preliminary Design Report prepared by

Smee and Busby Architects, there will be a new asphalt entrance drive and parking area associated with the proposed construction. Both flexible (asphalt) and rigid (roller compacted concrete (RCC)) pavement options are presented for use at this site. We utilized the American Association of State Highway and

Transportation Officials (AASHTO) flexible and rigid pavement design methods to analyze the pavement sections recommended in the Civil Design Narrative.

7.4.1 Flexible Pavement

The Civil Design Narrative provides the following flexible asphalt pavement section:

Table 7-1 Flexible Pavement Thicknesses

Pavement Material Thickness

Bituminous Asphalt Surface Mix 2.0 inches

Bituminous Asphalt Binder Mix 3.0 inches

Aggregate Base Course 10.0 inches

Our pavement calculations are based on the following assumptions:

An Average Daily Traffic (ADT) 200 trips per day of all vehicle types was provided by Ms. Pierce with UCOR.

For design purposes, light delivery trucks, such as panels and pickups, are considered as passenger cars.

Parking lot areas expected to experience little or no truck traffic can typically be designed for car and light truck loads only. Typically light load parking lot areas encompass the parking stalls and parking stall access lanes. Truck traffic in these areas is assumed to be limited to a few medium trucks and the occasional heavy truck that may stray into the parking stall area. The Asphalt Institute Publication IS-091, Full-Depth Asphalt Pavement for Parking Lots, Service Stations and Driveways, 5th Edition recommends approximately 3.45 daily Equivalent Single Axle Loads (ESALs) per 1000 vehicles per day for light duty parking lots. The anticipated ADT of 200 daily trips would result in approximately 0.7 daily ESALs for light duty parking areas. Two daily ESALs were added (total of 2.7 ESALs) for occasional stray truck traffic for medium duty pavements.

S&ME does not practice traffic engineering. Assumed traffic intensities should be verified prior to construction. In addition, the following criteria were used for the analysis of the flexible and rigid pavement sections:

20 year Design Life

0.7 Daily Equivalent Single-Axle Loads (ESAL) for Light-Duty Pavement (car traffic only)

2.7 Daily ESAL for Medium-Duty Pavement (car and stray truck traffic)

85 percent Reliability

Initial Serviceability index of 4.2

Terminal Serviceability index of 2

Standard Deviation of 0.45 flexible (0.35 rigid)

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 15

Assumed California Bearing Ratio (CBR) value of 3.0 based on the encountered soils

Based on these criteria, the asphalt pavement section presented in the Civil Design Narrative should be adequate for support of the anticipated traffic volumes over the assumed design life.

7.4.2 Rigid Pavement

The Civil Design Narrative provides the following rigid RCC pavement section:

Table 7-2 Rigid Pavement Thicknesses

Pavement Material Thickness

RCC 6.0 inches

Aggregate Base Course 4.0 inches

Using the assumed traffic data and design criteria from the previous section, the RCC pavement section presented in the Civil Design Narrative should be adequate for support of the anticipated traffic volumes over the assumed design life.

7.4.3 General

We recommend the assumed ESAL values be confirmed prior to construction. We understand budgetary considerations sometimes warrant thinner pavement sections than those presented. However, the client, owner, and project designers should be aware thinner pavement sections may result in increased maintenance costs and lower than anticipated pavement life. If thinner pavement sections are warranted, alternate reinforced pavement sections can be considered, including the use of geogrid reinforcement.

We recommend the use of an aggregate base course equivalent to the material recommended in Section

8.3 below. The bituminous asphalt surface mix should be Grade D or E as per Section 411 of the

Tennessee Department of Transportation (TDOT) specifications and the asphalt binder should be Grade

BM or BM-2 as per Section 307 of the TDOT specifications. Compaction requirements for the crushed aggregate base course and the bituminous asphalt pavement should also generally follow TDOT specifications.

Our recommendations are based on the assumption the subgrade has been properly prepared and new structural soil fill has been placed as outlined in the following sections of this report. All paved areas should be constructed with positive drainage to direct water off-site and to minimize surface water seeping into the pavement subgrade. The subgrade should have a minimum slope of 1 percent. In down grade areas, the base course should extend through the slope to allow any water entering the base course an exit path.

7.5 Subsurface Wall Recommendations

Based on the proposed grading plan for the K-25 History Center renovation (i.e., west of the K-1652 Fire

Station Building), we anticipate retaining walls will likely be used around the structure. In addition, below

Oak Ridge, Tennessee

S&ME Project No. 7143-15-062

October 23, 2015 16 grade walls will be required for construction of Viewing Tower elevator and associated elevator pit. We do not recommend using the fine grained site soils encountered in the borings as wall backfill. Therefore, we are providing equivalent fluid pressures for two backfill conditions for retaining walls. These are; (1) active earth pressure for granular backfill (open graded No. 57 stone) and (2) at-rest earth pressure for granular backfill.

Condition 1 - The active earth pressure for granular backfill will result in an equivalent fluid pressure of 35 pcf. If the granular backfill is to develop active earth pressure conditions, walls must be free to rotate or translate at the top approximately one inch laterally for every 20 feet of wall height.

Condition 2 - The at-rest earth pressure for granular backfill will result in an equivalent fluid pressure of

55 pcf. For retaining walls that will not rotate or translate, such as building walls or other walls rigidly connected to structures, at-rest conditions will develop. However, if any below grade walls will be backfilled before they are braced internally by floors, then the wall design must be checked assuming a fully cantilevered support condition using the active earth pressure profile given above.

These equivalent fluid pressures assume a unit weight of 100 pounds per cubic foot for the open-graded stone backfill. The wedge of clean aggregate backfill should have a minimum width of 1 foot at the base of the wall or the width of the footing heel, whichever is greater, and increase in width a minimum of 0.6 feet per foot of wall height. The aggregate should be fully encapsulated with a properly designed geotextile (filter fabric) to prevent migration of the adjacent soils into the aggregate. Please see Figure 5 in Appendix I for a depiction of the proper construction of a wedge of aggregate backfill behind a retaining wall.

In all cases, forces from any expected surcharge loading, including sloping backfill, should be added to the equivalent fluid pressures. The walls should be properly drained to remove water and prevent the buildup of hydrostatic pressures.