Geotechnical.pdf

Subsurface Information for the

TNANG KC-135 Hangar McGhee Tyson Air National Guard Base, Alcoa, Tennessee

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 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 BURNS & McDONNELL.

IF THIS SUBSURFACE INFORMATION IS BEING ISSUED IN ELECTRONIC (PDF) FORMAT. NOTE THAT IT CONSISTS OF A 5‐

PAGE FRONT‐END DOCUMENT WITH A 139‐PAGE APPENDIX (FLYSHEET AND REPORT BY SHIELD).

United States National Guard Bureau McGhee Tyson Air National Guard Base, Alcoa, Tennessee

Project No. 95368 September 2017

COPYRIGHT © 2017 BURNS & McDONNELL ENGINEERING COMPANY, INC.

Project No. 95368 Subsurface Information September 2017

United States National Guard Bureau i Burns & McDonnell

TABLE OF CONTENTS

Page No.

1.0 GENERAL

2.0 DESIGN NOTES

3.0 WATER LEVEL INFORMATION

4.0 ADDITIONAL SUBSURFACE INFORMATION

5.0 LIMITATIONS

5.1 Document Use

5.2 Variations

APPENDIX A - “REPORT OF GEOTECHNICAL EXPLORATION, PROPOSED

TNANG KC-135 HANGAR, MCGHEE TYSON AIR NATIONAL

GUARD BASE, ALCOA, TENNESSEE;” PREPARED BY SHIELD,

INC.; DATED AUGUST 9, 2017

United States National Guard Bureau 1 Burns & McDonnell

1.0 GENERAL

This subsurface information document consists of the data and results from a subsurface investigation described in a report titled, “Report of Geotechnical Exploration, Proposed TNANG KC-135 Hangar, McGhee Tyson Air National Guard Base, Alcoa, Tennessee,” dated August 9, 2017. The investigation was performed by Shield Engineering, Inc. (Shield) of Knoxville, Tennessee. The report, as prepared by

Shield, is included in Appendix A of this document.

Drilling and laboratory testing for this investigation was performed by Shield. The drilling phase was performed May 30 through June 7, 2017. It included the completion of thirteen (13) borings drilled to depths ranging from 4 feet to 99 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 Shield, are included in the report in Appendix A of this document.

Samples recovered during the subsurface investigation were transported to the laboratory by Shield.

Shield was not compensated to store the samples after testing and reporting beyond their customary retention period prior to disposal.

In addition to the drilling and laboratory testing, a geophysical survey study titled, “Geophysical Imaging

Study for Proposed KC135 Hangar at McGhee-Tyson Airport, Alcoa, Tennessee,” was conducted by

Draper Aden Associates of Blacksburg, Virginia under subcontract to Shield. The geophysical imagining survey consisted of eleven (11) transverses performed May 17 through May 18, 2017. The results of the survey is included as an attachment to the Shield report in Appendix A of this document.

2.0 DESIGN NOTES

Geotechnical design notes have not been prepared by Burns & McDonnell for this project.

3.0 WATER LEVEL INFORMATION

Water levels were observed by Shield, refer to the applicable Appendix of this document. 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, or longer, 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

United States National Guard Bureau 2 Burns & McDonnell 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.

4.0 ADDITIONAL SUBSURFACE INFORMATION

Burns & McDonnell has requested from United States National Guard Bureau 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 Kansas City office upon prior written request.

1. “Report of Subsurface Exploration, Aircraft Parking Apron, Tennessee Air National Guard Base, McGhee-Tyson Airport, Alcoa-Tennessee;” prepared by LAW Engineering and Environmental

Services, Inc.; dated May 5, 1999.

2. “Report of Cone Penetration Testing Detention Basin McGhee-Tyson Air National Guard, Blount

County, Tennessee;” prepared by GEOServices, LLC; dated June 22, 2006.

3. “Report of Limited Geotechnical Exploration MTANG Apron Sinkhole, Alcoa, Tennessee;”

prepared by GEOServices, LLC; dated June 28, 2011.

Burns & McDonnell is aware that a significant amount of construction activity has been undertaken in the near vicinity of the Site. Additional information in the form of geotechnical reports and/or construction records associated with construction activity in the vicinity of the Site may exist. Requests for such information should be directed to United States National Guard Bureau.

Other than that listed or described above, 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 United States National Guard Bureau.

5.0 LIMITATIONS

5.1 Document Use

The information presented in this document has been prepared for the use of Burns & McDonnell. 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.

United States National Guard Bureau 3 Burns & McDonnell

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.

5.2 Variations

The subsurface information submitted in this document is based upon data obtained from test borings and geophysical transverses completed at the approximate locations indicated in the applicable Appendix of this document. This document does not reflect variations which may occur between test borings and geophysical transverses. The nature and extent of variations between the test borings and geophysical transverses may not become evident until construction is performed. If during construction, soil, rock, and/or groundwater conditions appear to be different from those described herein, Burns & McDonnell should be advised 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 Shield. 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.

APPENDIX A - “REPORT OF GEOTECHNICAL EXPLORATION PROPOSED

TNANG KC-135 HANGAR MCGHEE TYSON AIR NATIONAL

GUARD BASE, ALCOA, TENNESSEE;” DATED AUGUST 9,

Report of Geotechnical Exploration

Proposed TNANG KC-135 Hangar

McGhee Tyson Air National Guard Base

Prepared for:

Burns & McDonnell

9400 Ward Parkway

Kansas City, Missouri 64114

Prepared by:

Shield Engineering, Inc.

300 Forestal Drive

Knoxville, TN 37918

Shield Project No. 1175018-01

August 9, 2017

TABLE OF CONTENTS

1.0 PROJECT INFORMATION

2.0 OBJECTIVE OF SUBSURFACE EXPLORATION

3.0 GEOLOGY & GENERAL SUBSURFACE CONDITIONS

4.0 SINKHOLE DEVELOPMENT AND RISK ASSESSMENT

5.0 FIELD EXPLORATION PROCEDURES

6.0 LABORATORY TESTING PROGRAM

6.1 Summary of Geotechnical Laboratory Testing

6.2 Summary of Soil Analytical Analysis and Laboratory Resistivity Testing

7.0 SUBSURFACE CONDITIONS

7.1 Description of General Soil Profile

7.1.1 Description of Soil Profile Hangar

7.1.2 Description of Soil Profile Munitions Yard

7.1.3 Description of Soil Profile Apron Addition

7.1.4 Description of Soil Profile Parking Area

7.2 Groundwater Observations

8.0 FOUNDATION RECOMMENDATIONS

8.1 Shallow Foundations

8.2 Settlement Analysis

8.3 General Slab On Grade Recommendations

9.0 SITE PREPARATION RECOMMENDATIONS

9.1 Site Preparation Recommendations

9.3 Structural Fill Recommendations

10.0 SUBSURFACE WALL AND RETAINING WALL RECOMMENDATIONS

11.0 SEISMIC SITE CLASSIFICATION

12.0 TEMPORARY EXCAVATION SLOPING REQUIREMENTS

13.0 PAVEMENT DESIGN RECOMMENDATIONS

14.0 CONSTRUCTION QUALITY ASSURANCE

15.0 LIMITATIONS

Attachments: Appendix A

Figure 1 – Site Location Plan

Figure 2 – Boring Location Plan

Figure 3 – Typical Subsurface Wall Detail

TABLE OF CONTENTS

Appendix B

Key to Soil Classification

Geotechnical Boring Logs

Appendix C

Rock Core Photos

Appendix D

Soil Geotechnical Laboratory Test Results

Soil Analytical Analysis

Appendix E

Summary of Settlement Calculations

Appendix F

Draper Aden Associates Geophysical Study Report

August 9, 2017

Abraham Smith Burns & McDonnell Senior Geotechnical Engineer 9400 Ward Parkway Kansas City, Missouri 64114

Tel: 816 822-3492 Fax: 816 822-4225

Subject: Report of Geotechnical Exploration & Geophysical Survey

Proposed TNANG KC-135 Hangar

McGhee Tyson Air National Guard Base

Shield Project No. 1175018-01

Dear Mr. Smith:

Shield Engineering, Inc. (Shield) has completed our final report of geotechnical exploration for the proposed Tennessee Air National Guard (TNANG) KC-135 Hangar and Apron additions in Alcoa, Tennessee in general accordance with our proposal P2016-790 dated April 10, 2017.

The purpose of our geotechnical exploration was to determine general subsurface conditions and obtain data to provide geotechnical recommendations and considerations for design and construction of the proposed Hangar and Apron Pavement additions. The scope of work authorized for this project included field activities, laboratory testing, and report preparation. Presented herein are the results of Shield’s subsurface exploration, conclusions and geotechnical recommendations as they relate to our understanding of the proposed project.

1.0 PROJECT INFORMATION

The purpose of this project is to provide design of a KC-135 aircraft maintenance Hangar and support shops to support the training and operational mission of KC-135 aircraft. Functional areas include: hangar bay and general/specialized shops. The project location is shown on the attached Figure 1. Additional scope includes the design of POV parking, KC-135 aircraft apron and munitions slab. The hours of operation for this facility should be considered as 24 hours a day/7 days a week.

The Scope of Work includes but is not limited to:

300 Forestal Drive

Knoxville, TN 37918

Telephone 865.544.5959

Fax 865.544.5885 www.shieldengineering.com

Proposed TNANG KC-135 Hangar Shield Project No. 1175018-01

McGhee Tyson Air National Guard Base August 9, 2017

Alcoa, Tennessee Page 2 of 33

a. Single-story hangar. The scope of the project calls for the construction of a 57,400 SF maintenance hangar consisting of the following areas:

(1) Hangar Maintenance Bay - 28,000 SF

(2) General Purpose Shops - 19,400 SF

(3) Corrosion Control Area - 4,600 SF

(4) Avionics Shop - 5,400 SF

b. Site work including water, electrical, sanitary sewer, communications, and storm sewer connections to existing infrastructure. Site work for apron access and vehicle/equipment parking.

c. Exterior construction will include concrete foundation with slab-on-grade, steel framed with load bearing and non-load bearing concrete masonry walls with brick veneer and insulated metal panel finish. Roofs can be combination of trusses, truss/joist, standing seam metal roofing system, etc, Interior construction will include concrete masonry units, gypsum and metal stud partitions, and acoustical suspended ceiling systems.

d. Hangar column loads are going to be approximately 250 kips axial compression, 75 kips of shear, and approximately 175 kips of uplift. Currently it is anticipated that the hangar is to bear upon a continuous footing with a width of 15 feet.

e. Munitions slab is going to be approximately 40 feet by 40 feet and have approximate loads of 250 pounds per square foot.

2.0 OBJECTIVE OF SUBSURFACE EXPLORATION

The objectives of this subsurface exploration were to assess general subsurface conditions and provide geotechnical-related recommendations/considerations for site preparation and foundations for the proposed hangar and apron pavement additions.

3.0 GEOLOGY & GENERAL SUBSURFACE CONDITIONS

McGhee Tyson Airport is located in the Appalachian Valley and Ridge Physiographic Province. This province extends along a northeastern and southwestern trend as a continuous belt of sub-parallel, alternating ridges and valleys extending from the Black Warriors and Coosa Rivers in Alabama to the Susquehanna in Pennsylvania. The geologic age of these formations stretch from the Cambrian to Pennsylvanian and primarily consist of limestone, dolomite, shale, and sandstone. These formations have been folded and faulted in the geologic past and have been subjected to at least one period of erosion since their structural deformation. The sandstone, shale, and cherty dolomite are

Alcoa, Tennessee Page 3 of 33 more resistant to solution weathering and form the ridges whereas the more soluble limestone, dolomite and calcareous shale form the valleys.

According to the Geologic Map of the Louisville Quadrangle (USGS, 2011), the subject is underlain by the Ordovician-aged Chepultepec Dolomite formation, a member of the Knox Group. The Chepultepec dolomite consists largely of well-bedded fairly light mostly fine to medium grained dolomite. Much of it is slightly silty although thin layers of dark dolomite also occur. Dark bluish aphanitic limestone is prominent in the upper part in the southeastern belts, reaching as far northwest as Rogersville and Morristown, but is absent elsewhere. Sandstone layers, commonly cemented by dolomite but locally by quartz, are almost invariably present in the lower third of the formation, which can ordinarily be mapped separately as a basal sandy member. There may be as many as eight prominent layers of sandstone as much as a foot thick, and locally the basal one is much thicker, reaching 10 feet in the area between Jacksboro and Norris. The sandstone layers thicken and become coarser to the northwest. The Chepultepec is normally 700 to 740 feet thick.

Light-colored chert nodules are common in the dolomite, especially in certain layers. Ooids in oolitic chert, where present, are small and uncolored. The chert produced during weathering is generally porous and cavernous, but in some areas it is as massive and abundant as that from the Longview dolomite. The chert is generally light colored and very fine-grained, but typically dull rather than porcelaneous. Over the basal sandy member, blocks of sandstone are prominent in the residuum.

4.0 SINKHOLE DEVELOPMENT AND RISK ASSESSMENT

The bedrock underlying the site is of great geologic age and over time has undergone a natural weathering process that sometimes results in the formation of solution features (e.g. sinkholes). The formation of a sinkhole occurs from the loss of surrounding soil into a solution feature or void in the underlying bedrock and the eventual collapse of the overlying soil dome. The development of sinkholes is a natural and ongoing geologic process facilitated by the in-place weathering of the parent bedrock and movement of groundwater. However, the formation of sinkholes is often accelerated during the construction grading process by the downward seepage of surface water through freshly exposed fractures in the soil which remain from the geologic structure of the parent bedrock. Based on a review of the USGS topographic quadrangle, geophysical work performed by Draper and Associates, subsurface drilling, previous experience on the site and recent dropouts that have occurred during construction of other upgrades to both TANG and the municipal airport, it is Shield’s opinion the property has a “moderate” to “high” risk for the development of future sinkholes affecting structures. It is important an owner understand and be made conscious of the risk associated with building in an area with sinkhole development in order to make a well informed decision regarding this risk. Shield has developed the three categories of “low risk,” “moderate risk,” and “high risk” to define the risk to the owner as follows:

Alcoa, Tennessee Page 4 of 33

Low Risk - Less than one in ten thousand buildings built in a geologic setting underlain by bedrock susceptible to sinkhole development will undergo significant structural distress requiring demolition or significant repair.

Moderate Risk - Between one in one thousand and one in ten thousand buildings built in a geologic setting underlain by bedrock susceptible to sinkhole development will undergo significant structural distress requiring demolition or significant repair.

High Risk - More than one in one thousand buildings built in a geologic setting underlain by bedrock susceptible to sinkhole development will undergo significant structural distress requiring demolition or significant repair.

As mentioned previously, the exposed soils during grading often contain relic structures of the parent bedrock. During grading and stripping of topsoil, the soils are exposed to surface water from rainfall and will transport groundwater downward more rapidly resulting in a greater possibility of new sinkhole formation. This risk increases in areas where the underlying bedrock has been exposed. To reduce the risk of sinkhole formation, designing and creating positive drainage to maintain a well-drained condition for the entire development area is imperative. The pooling or collection of standing water in areas other than designated and designed detention/retention ponds is discouraged.

The continued formation and development of sinkholes cannot be eliminated, but during site development there are several good practices that can be utilized to further reduce the potential for sinkhole formation. The four recommended practices are as follows:

1. In areas of cut, scarify and recompact the exposed upper nine inches of soil to develop a less permeable layer of material.

2. In suspect areas, utilize a liner system for ditches and water collection systems such as asphalt, concrete or geo-membranes. As suggested by Moore (Moore 2006), “the single most important item that can be implemented to prevent future sinkhole collapse occurrence is the use of lined drainage ditches. Types of liners that tend to function the best include 60 mil PVC and/or HDPE geomembrane and concrete and asphalt materials”. Once placed, the membrane should be covered with either a grass/sod layer or rip-rap. Care should be taken when placing the rip-rap not to damage the geomembrane.

3. Utilize high density poly-ethylene (HDPE) pipe for storm systems.

Alcoa, Tennessee Page 5 of 33

4. Prior to slab placement, pressure test all under-slab piping before beginning service.

5. Rout roof drains away from structure and specifically not beneath the structure.

6. Use TDOT Grade D Stone or Controlled Low Strength Material (CLSM) / flowable fill for utility trench bedding and backfill.

5.0 FIELD EXPLORATION PROCEDURES

The field exploration was performed beginning May 30, 2017 and completed on June 8, 2017 by our subcontractor, Total Depth Drilling, under the direction of Shield’s on-site representative. The borings were drilled with an ATV-mounted drill rig.

A total of thirteen (13) soil test borings were extended to pre-determined termination depths and auger refusal depths ranging from 5 feet to 68.5 feet. One additional auger boring was performed to collect a UD sample (B-6A). Upon refusal, bedrock materials were sampled in six borings to a depth of approximately 53.5 feet to 99.5 feet using diamond rock coring techniques to retrieve NQ size rock core. The boring locations were selected by B&M and located in the field by C2RL, Inc., your surveyor. The location of each boring is shown on the Boring Location Plan (Figure 2, in Appendix A).

The test borings were advanced utilizing continuous flight hollow stem augers, with standard penetration test (SPT) and soil sampling performed by means of the split-barrel sampling procedure in general accordance with ASTM D 1586. In this procedure, a 2 inch O.D., split-barrel sampler is driven into the soil a distance of 18 inches by a 140-pound hammer falling 30 inches. The number of blows required to drive the sampler through the final 12 inches of penetration is termed the “standard penetration resistance” or “N-value” and is indicated for each sample on the boring logs in Appendix B. This value can be used as a qualitative indication of the consistency of cohesive soils. This indication is qualitative, because many factors can significantly affect the N-value and prevent direct correlation between samples obtained by various drill crews, drill rigs, drilling procedures, and hammer-rod-spoon assemblies. Rock coring was performed using diamond rock coring techniques in general accordance with ASTM D 2113.

Shield Personnel also performed pocket penetrometer tests on the retrieved SPT samples. The field test results are located on the soil test borings located in Appendix B.

Six (6) relatively undisturbed samples were obtained by pushing a section of 3-inch O.D., 16-gauge steel tubing into the soil at the desired sampling level. The sampling procedure is described by ASTM D 1587. The tube, together with the encased soils, was carefully removed from the ground, Alcoa, Tennessee Page 6 of 33 made airtight, and transported to our laboratory.

The recovered soil samples and rock cores were visually classified in the field by our staff engineers trained in geotechnical engineering. The soil samples and rock cores were labeled, placed in appropriate containers, and transported to Shield’s Knoxville laboratory where they were re-examined by our geotechnical engineer and visually classified. Selected soil samples were subjected to laboratory testing and analysis. The laboratory-testing program is addressed in the subsequent section “Laboratory Testing Program”.

The soil samples / rock cores and the field data collected during the field exploration were used to assist in the description of the subsurface conditions, and for engineering evaluation purposes. The subsurface conditions observed at each test boring location are detailed on the Geotechnical Boring Logs in Appendix B, at the end of this report. In addition, select photos of rock core are in Appendix C.

Groundwater measurements were taken after the completion of augering in each boring, at the termination of the boring, and at approximately 24 hours after the completion of the borings. Core water was bailed out of the rock core borings and the groundwater level was allowed to recharge prior to taking 24-hour groundwater level readings. The groundwater levels are shown on the Geotechnical Boring Logs in Appendix B.

Upon completion of drilling, the borings were plugged and abandoned with cement-bentonite grout.

6.0 LABORATORY TESTING PROGRAM

The purpose of the laboratory testing program was to evaluate the mechanical and index properties of the subsurface soils encountered, and to assist in soil classification and relative strength evaluations.

Representative soil samples were obtained at various depth intervals within the test borings for laboratory testing and analysis. These samples were divided into groups of similar samples according to color and visual classification. The laboratory testing program included the following tests:

Geotechnical Testing

Natural moisture content tests (ASTM D 2216) Atterberg limits (ASTM D 4318) Grain size analysis with hydrometer (ASTM D 422) Classification in accordance with the Unified Soil Classification System (ASTM D 2487) One-Dimensional Consolidation (ASTM D 2435) Modified Proctor (ASTM D 1557) California Bearing Ratio “CBR” (ASTM D 1883)

Alcoa, Tennessee Page 7 of 33

Soil Analytical Analyses Testing pH Soluble Sulfates Chloride Ion Redox Potential Sulfides Field Resistivity Testing

6.1 Summary of Geotechnical Laboratory Testing

The laboratory testing generally indicated that the soils are typical of soils encountered in the Valley and Ridge Physiographic Providence. The results reported are only for the samples that were selected for testing. In addition, the existing fill is heterogeneous and the testing may not represent all soils present at the site.

Atterberg Limit, grain size analysis with hydrometer, natural moisture content and unconfined compression testing were performed to assist in the classification and characterization of the soils encountered on site. Testing reveals the soils have Liquid Limits ranging from 38 to 58 and Plasticity Indices ranging from 21 to 35. Based on the grain size analysis and Atterberg Limit test results the soils that were tested classify as lean clay with sand (CL) and borderline fat clay with sand (CH) based on the Unified Soil Classification System (USCS) per the results in Appendix D.

Natural moisture content testing was performed on random samples and revealed natural moisture contents ranging from 17.6% to 60.3%.

Modified Proctor and subgrade strength tests have been performed from bulk samples collected at boring location B-1 and B-7. The bulk samples at each boring location were collected from auger cuttings within the upper 10 feet. Modified Proctor testing indicates the soils from B-1 and B-7 to have maximum dry densities of 113.1 and 110.0 pounds per cubic foot and optimum moisture content 16.8 and 17.3 percent, respectively. CBR testing was also performed on the collected bulk samples. Boring B-1 resulted with a CBR value of 12.1 at 95% of the modified proctor and boring B-7 had a CBR value of 10.1 at 95% of the modified proctor.

One dimensional consolidation testing was performed on undisturbed samples from borings B-6A (5 feet to 7 feet) and B-5 (42 feet to 44 feet). Consolidation testing was utilized to estimate settlement potential, and is discussed in section 8.2 Settlement Analysis.

Alcoa, Tennessee Page 8 of 33

6.2 Summary of Soil Analytical Analysis and Laboratory Resistivity Testing

Shield’s subcontract laboratory, Test America, performed laboratory testing on 2 select samples from the collected SPT samples from borings B-7 and MSA-1. The following table summarizes the requested analytical testing.

Table1 – Soil Analytical Analysis Results Boring

No.

Sample

Depth (ft) pH

Chloride

(mg/Kg)

Sulfates

(mg/Kg)

Sulfide

(mg/Kg)

Redox Potential

(mV)

B-7 3.5 – 5 4.8 ND 47.7 ND 327

MSA-1 3.5 – 5 4.2 ND ND ND 311

Soil resistivity testing was also performed on the composite soil sample using a Miller Soil Box in general accordance with ASTM G187. Soil resistivity measurements were recorded from selected samples from soil test borings B-7 and MSA-1. Boring B-7, sample interval 8.5 feet to 10 feet resulted with 26,500 ohm-cm @ 26.7 percent moisture and boring MSA-1, sample interval 1.0 feet to 2.5 feet resulted with 15,000 ohm-cm @ 34.7 percent moisture. Based on published data from Handbook of Corrosion Engineering, Roberge, 2000, the sampled soils fall in the category of mildly corrosive to essentially noncorrosive.

Soils in this region do not historically corrode components of construction (i.e. concrete, steel, ductile pipe, etc.). However, it may still be advisable that individual vendors review the chemical analysis data to evaluate the potential for damage to their products.

The results of our laboratory testing are included in Appendix D.

7.0 SUBSURFACE CONDITIONS

The Geotechnical Boring Logs in Appendix B represent our interpretation of the subsurface conditions based on tests and observations performed during the drilling operations at the test boring locations and visual examination of the soil samples and rock cores. The lines designating the interfaces between various strata on the Geotechnical Boring Logs represent the approximate strata

Alcoa, Tennessee Page 9 of 33 boundary; however, the transition between strata may be more gradual than shown, especially where indicated by a broken line. Subsurface conditions may vary between our boring locations.

7.1 Description of General Soil Profile

The following paragraphs provide a general description of the soil conditions encountered. For soil descriptions at a particular boring location and depth, the respective boring log should be reviewed in Appendix B. Soils encountered on site were typically composed of topsoil, fill / possible fill, alluvial and residual soils. Topsoil is the dark-colored organic soil that develops naturally at the ground surface. Fill soil is composed of materials transported to its current location by man. Alluvial soil has been transported to its present location by water. Residual soils are composed of soil materials developed from the in-place weathering of the underlying bedrock materials. In some cases, it was difficult to distinguish the origins of the soils recovered in the soil borings. Therefore, the soil origins depicted in the soil boring logs should be considered approximate.

7.1.1 Description of Soil Profile Hangar

From the ground surface in test borings B-1 through B-4 and B-6 through B-8, topsoil was encountered. The topsoil ranged from approximately 0.2 to 0.5 feet in thickness. The thickness of these soils may vary between boring locations.

Below the surficial grass layer and/or beneath the topsoil in all test borings, with the exception of B- 7, fill soils were encountered to a depth ranging from 4 feet to 16.8 feet below existing grades. The fill generally consisted of light brown to dark brown, dark brownish red, yellowish brown clay with chert and rock fragments. The standard penetration resistance value (SPT) ranged from 3 blows per foot (bpf) to 18 bpf, indicating a soft to very stiff soil consistency. The thickness and consistency of these soils may vary between boring locations.

Underlying the surficial grass, topsoil, and/or fill layer, residuum was encountered to auger refusal depths ranging from 29.5 feet to 68.5 feet below existing grade. The residuum generally consisted of dark brownish red to light brown to brown, yellowish brown clay with black oxide nodules and staining as well chert and rock fragments. SPT blow counts ranged from Weight of Hammer (WOH) bpf to 20 bpf, indicating very soft to very stiff soil consistencies, with most of the soils in the firm range.

Auger refusal was encountered in all borings, with the exception of B-6A, at depths ranging from

29.5 feet to 68.5 feet below existing grade. B-6A was drilled to obtain a UD sample.

Diamond rock coring techniques were used to retrieve rock core specimens of refusal materials at all boring locations. The recovered rock core was typical of bedrock described as the Chepultepec

Alcoa, Tennessee Page 10 of 33

Dolomite formation. The bedrock was typically composed of gray, slightly weathered to fresh dolostone. The measured dip of the bedding plane of the bedrock was approximately 50 degrees.

The Recovery Ratio and Rock Quality Designation (RQD) of the rock core samples were determined in our laboratory. These values are used to evaluate the quality of bedrock in the general area of the boring. The Recovery Ratio is defined as the percentage ratio between the length of core recovered, to the length of core drilled in a given core run. The RQD is defined as the percentage ratio between the length of the recovered core pieces that are at least 4 inches in length (NQ Core), to the length of core drilled in a given core run. The rock core recovery ratio for the cored borings ranged from 58 to 100 percent, but was typically greater than 70. RQD's ranged from 25 to 100 percent but were typically above 60. A very low Recovery Ratio and RQD value typically indicates the bedrock to be discontinuous, highly jointed, or fractured to very fractured as well as very poor quality.

Clay filled voids were observed during coring in borings B-1, B-3, B-5, B-6, and B-8. The majority of the clay voids recorded during coring were 2 feet in thickness or less with the exception of boring B-6. Boring B-6 encountered a clay void from 65 feet to 79.6 feet, which may indicate a floating bolder, rock ledge, or slot at the first encounter of auger refusal/start of rock coring.

7.1.2 Description of Soil Profile Munitions Yard

From the ground surface in test borings MSA-1, topsoil was encountered. The topsoil was approximately 0.1 feet in thickness.

Below the topsoil in test borings MSA-1, fill soils were encountered to a depth of 11.8 feet. The fill generally consisted of brown to dark brownish red, yellowish brown sandy clay with fine rootlets and rock fragments. The SPT blow counts ranged from 2 bpf to 29 bpf, indicating a very soft to very stiff consistency.

Underlying the topsoil and fill in MSA-1, residuum was encountered. The residuum generally consisted of light brown to brown and yellowish brown clay with trace black oxide nodules and staining. SPT blow counts ranged from 2 bpf to 10 bpf, indicating very soft to stiff soil consistencies.

Boring MSA-1 was terminated at their respective predetermined depth of 5 feet below existing grade.

7.1.3 Description of Soil Profile Apron Addition

From the ground surface in test borings A-1 and A-2, topsoil was encountered. The topsoil ranged from approximately 0.1 to 0.3 feet in thickness. The thickness of the topsoil will most likely vary between boring locations.

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Below the topsoil in test borings A-1 and A-2, fill soils were encountered to a depth ranging from 5 feet to 11.8 feet below existing grades. Boring A-2 was terminated in the fill layer at its predetermined termination depth of 5 feet. The fill generally consisted of brownish red clay with chert and rock fragments and trace amounts of fine rootlets. The standard penetration resistance value (SPT) was 10 blows per foot (bpf) to 24 bpf, indicating a stiff to very stiff soil consistency. The thickness and consistency of these soils may vary between boring locations.

Beneath the topsoil and fill in boring A-1, possible colluvium was encountered to a depth of 31.8 feet below existing grade. The possible colluvium generally consisted of dark brownish red clay with rounded black oxide nodules. Standard penetration resistance values (SPT) ranged from 4 bpf to 13 bpf, indicating soft to stiff soil consistency.

Underlying the topsoil, fill, and possible colluvium in boring A-1, residuum was encountered to boring termination depth of 40 feet. The residuum consisted of brownish red to yellowish brown clay. Standard penetration resistance values (SPT) ranged from 10 bpf to 21 bpf, indicating stiff to very stiff soil consistency.

7.1.4 Description of Soil Profile Parking Area

From the ground surface in test borings P-1 and P-2, topsoil was encountered. The topsoil was approximately 0.3 feet in thickness at both boring locations. The thickness of topsoil will most likely vary between boring locations.

Below the topsoil in test borings P-1 and P-2, fill soils were encountered to a depth ranging from 3 feet to 5 feet below existing grades. Boring P-2 was terminated in the fill layer at its predetermined termination depth of 5 feet. The generally consisted of brownish red to yellowish brown and dark brown clay with chert fragments and trace fine rootlets. The SPT blow counts ranged from 8 bpf to 13 bpf, indicating a firm to stiff soil consistency. The thickness and consistency of these soils may vary between boring locations.

Underlying the topsoil and fill in boring P-1, residuum was encountered to boring termination depth of 40 feet. The residuum consisted of brownish red to yellowish brown clay. SPT blow counts of 15 bpf, indicated a stiff soil consistency.

Borings P-1 and P-2 were terminated at their respective predetermined depth of 5 feet below existing grade.

7.2 Groundwater Observations

Groundwater was only observed in borings B-1, B-2, B-5, and B-6 during augering at a depths ranging from 40 feet to 63.5 feet below existing grade. At the completion of augering ground water

Alcoa, Tennessee Page 12 of 33 was observed in borings B-2, B-5, and B-6 at depths ranging from 52.0 feet to 63.5 feet below existing grade. Groundwater measurements were also taken at the time of completion and after 24 hours in all borings. During rock coring, water is introduced into the subsurface as part of the coring process. Thus, water levels measured after rock coring can be influenced by water pumped into the borehole during rock coring. Therefore, after the completion of rock coring, water in the coreholes was bailed out and allowed to recharge prior to taking 24-hour water level readings. Water levels were recorded after 24 hours in borings B-1, B-2, B-6, B-7, and B-8 at depths ranging from 20.2 feet to 45 feet below existing grades. A summary of the groundwater level readings are listed in Table 1 below. It is important to note that fluctuations in the elevations of the static groundwater table may occur seasonally and are also influenced by variations in precipitation, evaporation, site grading activities, surface water run off and/or the nearby presence of surface water features. The actual depth to groundwater at the time of site grading may be higher or lower than that encountered at the time of the subsurface exploration.

Table 2 – Groundwater Readings

Boring

Number

Approx.

Ground

Elevation

(ft)

Approx.

Depth to

Bedrock

(ft)

Approx.

Elevation of Top of

Rock (ft)

24-hr Water

Level in

Borings

Depth

(ft)

Elev.

(ft)

B-1 923.64 56.8 866.84 45.0 878.64 B-2 926.64 67.5 859.14 36.3 890.34 B-3 927.10 42.0 885.10 Dry Dry B-4 921.56 50.5 871.06 Dry Dry B-5 922.71 68.5 854.21 + + B-6 925.28 62.0 863.28 20.2 905.08

B-6A 925.28 N/A N/A + + B-7 924.62 47.5 877.12 23.0 901.62 B-8 924.04 29.5 894.54 39.5 884.54

+No measured water level, borings backfilled upon completion of drilling.

Shield anticipates groundwater will not be an issue during construction based on 24-hour water level readings and proposed grades.

8.0 FOUNDATION RECOMMENDATIONS

Based on a review of the information from the test borings, laboratory test results and project information, the stiff or better existing fill soils, residual soils and or newly compacted soil fill appear generally suitable for the support of shallow spread footing foundations using conventional construction methods. Soil fill materials were encountered during drilling; the fill materials appear to

Alcoa, Tennessee Page 13 of 33 have been placed during the last expansion of the apron. Shield has performed a settlement analysis of the soils for both continuous and column foundations bearing in this fill material. The results of these analyses are discussed in the subsequent section entitled “Settlement Analysis”. The onsite clay materials do appear suitable for use as structural fill provided our subsequent “Structural Fill Recommendations” are followed. Newly compacted fill soil should be composed of clay, silt or shale types of soils.

We recommend sizing the footings for a design soil bearing pressure of 2,000 psf subject to a footing inspection by a geotechnical engineer at the time of construction. It is Shield’s recommendation typical shallow foundations be used for support of the structure. The drilling data and geophysical survey suggest that deep foundations and remedial grouting work will not be necessary. However, as evidenced by karst activity in the area as well as Shield’s previous experience working in East Tennessee, karst conditions can change over time due to various reasons (e.g., surface drainage, wetter seasons, drier seasons, etc.). As such, Shield has provided general shallow foundation recommendations as well as an optional stiffened foundation system to be utilized at the heavily loaded column locations. It is important to note that if a footing inspection is not performed, then the design soil bearing pressure provided above should be considered invalid. The following sections provide recommendations for the installation of foundations, site preparation and the control and placement of structural fill.

Option 1- Foundations Supported on Traditional Shallow Foundations:

As previously described, support the building on conventional shallow foundations and slab on grade designed for an allowable bearing pressure of 2,000 psf.

Option 2 – Foundations Supported on Stiffened Foundations and Thickened Slab:

Although we do not anticipate karst activity in the building area in the foreseeable future, a rigidly designed shallow foundation system (grade beams) that connects continuous and column foundation locations that will be capable of withstanding temporary loss of support due to subsurface changes (sinkhole dropouts) can be designed for the Hangar. In the event that soil loss beneath the foundations occurs, the rigid foundations could provide enough support to prevent extensive damage to the structure and could also accommodate underpinning of the structure in the future if such events occur. The footings should still be designed for a maximum allowable bearing pressure of 2,000 psf. The slab on grade should be designed with sufficient reinforcing steel to span a dropout of 5 feet in diameter. Subgrade design information is provided in the subsequent “Pavement Design Recommendations”.

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8.1 Shallow Foundations

In order to avoid a local shear or "punching" failure of the footings, we recommend minimum widths of 24-inches for isolated/rectangular footings and 18-inches for continuous footings. Perimeter foundations should be embedded a minimum of 18 inches below the final exterior ground surface to provide adequate frost protection and confinement. Interior columns may be designed for more shallow bearing depths. The minimum depth should meet current building code requirements.

The suitability of foundation and/or slab bearing soils in areas between borings should be verified by qualified visual inspection and/or proofrolling as described in subsequent sections. In addition, the opened footing excavations should be examined for uniformity of soil properties and tested using a hand auger and a dynamic cone penetrometer (DCP). The footing evaluation should be performed by a geotechnical engineer and/or his representative prior to the placement of reinforcing steel or concrete. The purpose of the footing evaluation is to locate any unexpected soft soil areas or unsuitable soil areas which may require undercutting and backfilling. Areas in the foundation subgrade that are determined to be unsuitable should be repaired or modified as directed by the geotechnical engineer. The maximum depth of undercut will have to evaluated in the field by Shield.

It is important to note that the foundation recommendations described above should not be considered valid unless a footing evaluation is conducted at the time of foundation installation.

We recommend that the footings be poured as soon as possible after the geotechnical footing excavation evaluation in order to minimize potential disturbance of the bearing soil. The prepared foundation bearing soils should not be left exposed overnight or during inclement weather. If the subgrade soils are exposed overnight or during inclement weather, we recommend the placement of a two to four inch thick "mud-mat" of lean concrete on the bearing soils. Saturation and subsequent disturbance of the foundation subgrade soils can result in a loss of strength and bearing capacity, leading to increased settlement.

We recommend that the slab-on-grade subgrade be carefully proofrolled under the supervision of a Shield geotechnical engineer to check for soft areas. The proofrolling for structural fill should be performed as recommended in the site preparation section of this report. The slab-on-grade should be placed only on soils which proofroll successfully and should have an adequate thickness of granular base. The floor slab should be designed with an adequate number of joints to minimize cracking. The slab should be designed as a floating slab, not rigidly connected to bearing walls or foundations in order to accommodate differential settlement between the foundation and the slab.

The slab should be nominally reinforced to maintain its integrity should minor differential movement occur. In addition, aggregate, such as ASTM D 448 No. 57 or No. 67 stone, should be densified and placed beneath the slab to allow for a suitable base on which to work as well as reduce damage/degradation of the prepared subgrade during construction. The aggregate layer should be at least 4 inches thick. Subgrade design parameters for slabs have been included in the subsequent “Pavement Design Recommendations Section” of this report.

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Subgrade soils to support floor slabs shall consist of suitable bearing natural soils and/or properly placed controlled structural fill and be firm and unyielding. Interior utility trenches should be properly backfilled and compacted as recommended herein. Proof rolling of the subgrade soils is recommended prior to placement of the recommended granular cushion to detect any possible soft or yielding areas which may be present. Any soft or unsuitable bearing subgrade areas which are detected during proof rolling should be removed and replaced with suitably compacted and controlled structural fill in accordance with the recommendations contained herein.

Ultimate passive earth pressures for soil adjacent to footings should be calculated using a coefficient kp=1.5 and dry density γd=90 pcf. The factor of safety should be determined by the designer. The upper 2 feet of soil above the footing should be neglected. An ultimate sliding coefficient of 0.35 should be used with a factor of safety of 1.5 for foundations supported on soil.

It is our understanding the column foundations will be subject to uplift loading. Uplift resistance should include the weight of the column foundation as well as the soil above. Shield recommends using a wet unit weight of soil equal to γsat=110 pcf.

8.2 Settlement Analysis

The foundations for the proposed structures must satisfy two basic and independent criteria. First, the bearing pressure transmitted to the foundation soils must not exceed the ultimate soil bearing capacity reduced by an appropriate factor of safety. Second, settlements due to compression of the foundation soils during the life of the structure should not be of sufficient magnitude to cause damage to the structure or impair its use or appearance. To perform adequately, foundations must be designed to satisfy each of these requirements.

Settlement calculations were performed based on the results from two consolidation test performed on undisturbed samples from borings from borings B-6A (5 feet to 7 feet) and B-5 (42 feet to 44 feet) We have provided a chart that outlines estimated settlements in regards to the ratio of the dimensional size of the foundation and proposed bearing pressures. Although settlement estimates were calculated to be less than 1 inch, the state of the art is such that we expect total settlement not to exceed 1 inch and differential settlement not to exceed 0.5 inches.

Settlement will occur throughout the construction and life of the proposed structure. Shield expects most of the settlement to occur during construction.

8.3 General Slab On Grade Recommendations

We recommend that the slab-on-grade subgrade be carefully proofrolled under the supervision of a Shield geotechnical engineer to check for soft areas. The Proofrolling for structural fill should be

Alcoa, Tennessee Page 16 of 33 performed as recommended in the site preparation section of this report. The slab-on-grade should be placed only on soils which proofroll successfully and should have an adequate thickness of granular base. The floor slab should be designed with an adequate number of joints to minimize cracking. The slab should be designed as a floating slab, not rigidly connected to bearing walls or foundations in order to accommodate differential settlement between the foundation and the slab.

The slab should be nominally reinforced to maintain its integrity should minor differential movement occur. In addition, aggregate, such as ASTM D 448 No. 57 or No. 67 stone, should be densified and placed beneath the slab to allow for a suitable base on which to work as well as reduce damage/degradation of the prepared subgrade during construction. The aggregate layer should be at least 4 inches thick. For small ancillary structures, it may be advisable to include an impermeable membrane (rain barriers) beneath floor slabs. However, the owner should be aware of the potential hazard that “curling” may occur at the slab sides during the slab curing.

Subgrade soils to support floor slabs shall consist of suitable bearing natural soils and/or properly placed controlled structural fill and be firm and unyielding. Interior utility trenches should be properly backfilled and compacted as recommended herein. Proofrolling of the subgrade soils is recommended prior to placement of the recommended granular cushion to detect any possible soft or yielding areas which may be present. Any soft or unsuitable bearing subgrade areas which are detected during Proofrolling should be removed and replaced with suitably compacted and controlled structural fill in accordance with the recommendations contained herein.

9.0 SITE PREPARATION RECOMMENDATIONS

9.1 Site Preparation Recommendations

We recommend that…