Amend 0002 - 18235 GEOTECH REPORT.pdf

Report of Geotechnical Exploration

Veterans Affairs Structural Repairs

Murfreesboro, Tennessee

S&ME Project No. 1247-18-038

PREPARED FOR:

Design-Aire Engineering

220 N. College Avenue

Indianapolis, Indiana 46202

PREPARED BY:

S&ME, Inc.

820 Fesslers Parkway, Suite 240

Nashville, TN 37210

January 3, 2019

S&ME, Inc. | 820 Fesslers Parkway, Suite 240 | Nashville, TN 37210 | p 615.244.6020 | www.smeinc.com

January 3, 2019

Design-Aire Engineering

220 N. College Avenue

Indianapolis, IN 46202

Attention: Mr. Dave Haun

Reference: Report of Geotechnical Exploration

Veterans Affairs Structural Repairs

3400 Lebanon Road; Murfreesboro, Tennessee

S&ME Project No. 1247-18-038

Dear Mr. Haun:

S&ME, Inc. (S&ME) is pleased to submit the following Report of Geotechnical Exploration performed for the planned Veterans Affairs building structural repairs located at 3400 Lebanon Road; Murfreesboro, Tennessee. Our services were provided in general accordance with our Proposal No. 12-1800489, dated November 28, 2018 as authorized by Design-Aire Engineering. This report describes our understanding of the project and the subsurface conditions encountered and presents our conclusions and recommendations for site preparation, foundations, retaining walls, floor slab support, and pavements.

We appreciate the opportunity to serve as your geotechnical engineering consultant during this phase of the project. Please contact us with questions regarding this report, or if we may be of further assistance.

Sincerely, S&ME, Inc.

Eric C. Conway, E.I. Phillip J. Collins, P.E.

Project Engineer Principal Engineer

1/3/19

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Table of Contents

1.0 Introduction

1.1 Purpose

1.2 Project Information

1.3 Scope of Study and Report Format

2.0 Exploration and Testing Programs

2.1 Field Exploration

2.1.1 Site Reconnaissance

2.1.2 General

2.1.3 Soil Test Borings

2.2 Laboratory Test Program

3.0 Subsurface Conditions

3.1 Geologic Conditions

3.1.1 Fill Materials

3.1.2 Residual Materials

3.2 Subsurface Conditions

3.2.1 Summary of Subsurface Conditions

3.2.2 Subsurface Water

3.2.3 Test Boring Refusal

3.2.4 General

3.3 Laboratory Test Results

4.0 Conclusions and Recommendations

4.1 General

4.2 Site Assessment

4.2.1 Visual Observations

4.2.2 Previously Placed Fill

4.2.3 Fat Clays

4.2.4 Karst Geology

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4.2.5 Soft Soils

4.2.6 Conclusions and Recommendations

4.3 Site Preparation

4.3.1 General

4.3.2 Excavation

4.4 Fill Placement and Compaction

4.4.1 Soil Fill

4.5 Site Degradation during Construction

4.6 Foundations

4.7 IBC Seismic Site Class

4.8 Slab-On-Grade

4.9 Retaining Walls

5.0 Follow-Up Services

6.0 Limitations

List of Tables Table 3-1: Summary of Borings

Table 3-2: Laboratory Test Results

Table 4-1 Below-grade Wall Design Parameters

Appendices Appendix I –Figures

Appendix II – Field Exploration

Appendix III - Laboratory Summary

Appendix IV- Important Information about Your Geotechnical Engineering Report

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1.0 Introduction

1.1 Purpose

The purpose of this geotechnical exploration was to explore subsurface conditions at the site pursuant to developing site preparation, foundation, retaining wall, and slab-on-grade construction recommendations. This report provides the following:

A summary of the project and provided information;

A summary of current site conditions, topography, and area geology;

A summary of the field exploration methods;

A Test Location Plan, and individual test boring logs for each boring;

A summary of the subsurface conditions encountered in the test borings;

A summary of laboratory test methods and results;

Conclusions and Site Assessment;

Recommendations for site preparation, structural fill placement, and groundwater control, as applicable;

Recommendations for foundation design, allowable bearing capacity, and construction guidelines;

Recommendations for lateral earth pressures for retaining walls (i.e., cast in place cantilever walls; S&ME’s scope did not include parameters for other wall types, design of walls, or slope stability analyses);

Recommended Seismic Site Class using the general procedure in general accordance with the 2012

International Building Code (IBC); and

Recommendations for design and construction of the concrete slab-on-grade, including subgrade modulus, based on assumed loading conditions.

1.2 Project Information

Initial project information was provided in a Request For Proposal (RFP), dated November 21, 2018. Based on the

RFP, the project includes an exploration of subsurface conditions to help assess reported settlement in several of the buildings within the Veterans Affairs campus located at 3400 Lebanon Road in Murfreesboro, Tennessee. The

RFP included an attached aerial with notations showing the areas of interest on the VA campus and an aerial with notations showing the desired boring locations within the VA campus.

Based on the information provided, the project includes potential repairs due to cracking and/or settlement at

Buildings 107 and 116 and at the Connector between Buildings 5 and 7. In addition, possible repairs may be made at the northwest wing of building 5 and at the Connector between Buildings 5 and 6. We understand that the ages of the buildings are as follows:

Building 107 – constructed circa 1960

Building 116 – circa 1986

Building 5 – circa 1945

Building 7 – unknown construction date

Buildings 5-7 Connector – exact construction date unknown, but prior to 1972

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Based on the information provided, it is not clear when the cracks and settlement were first observed.

We understand that the structural loads on the existing structures include column loads of about 40 kips and wall loads of about 2 klf. We have not been provided any information regarding finished grades. Based on our site reconnaissance, the exterior surface in the areas of concern are generally grass covered and relatively flat.

The project information and assumptions detailed above should be reviewed and confirmed by the appropriate team members. Modifications to our recommendations may be required if the planned development differs from our stated information and assumptions described herein.

1.3 Scope of Study and Report Format

This geotechnical exploration included a site reconnaissance, field and laboratory testing, and engineering analysis. The following sections of this report present discussions of the field exploration, site conditions, laboratory test results, and conclusions and recommendations. Following the text of this report, figures, and exploration logs are provided in the Appendix.

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

2.0 Exploration and Testing Programs

2.1 Field Exploration

2.1.1 Site Reconnaissance

Limited visual site reconnaissance was performed in readily viewable areas on the south side of Building 107, in the Connector between Buildings 107 and 116, and in the Connector between Buildings 5 and 7. Tile floors were observed to be uneven in some areas, with some cracks observed in the tile. Significant cracks were not observed in the exterior brick veneer. Our observations were for the purpose of providing a summary of the general conditions in the areas of concern and were limited in nature. We understand that a structural engineer will also be reviewing the site conditions for Design-Aire Engineering.

2.1.2 General

The subsurface conditions were explored on December 11-13, 2018 with 15 test borings performed in general accordance with ASTM D1586, the Standard Test Method for Standard Penetration Test (SPT) and Split-Barrel

Sampling of Soils and ASTM D2488, the Standard Practice for Description and Identification of Soils (Visual-Manual

Procedure). Refer to the Test Location Plan, Figure 2, in the Appendix for the approximate boring locations. Mr.

Phil Collins, P.E. of S&ME laid out the borings based on the general locations noted in the aerial provided in the

RFP. The locations were finalized in a site meeting between Mr. Collins and Mr. Dave Haun of Design-Aire

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Engineering. The approximate boring locations were recorded utilizing a handheld GPS unit. The locations were cross referenced by estimating right angles and pacing or measuring distances from site features (i.e., building, sidewalks, pavements, etc.). Based on the methods used to establish the locations of the test borings, this information should be considered approximate. If more precise location information is required, a professionally licensed surveyor should be retained to obtain that information. We have not been provided grading information at this time. Therefore, elevations are not included on the boring logs.

2.1.3 Soil Test Borings

The test borings were advanced by mechanically twisting 2 ¼-inch diameter hollow stem augers (HSA) into the ground with a Geoprobe 7822 DT drill rig. Soil samples were obtained with a standard 1.4-inch inside diameter

(ID), 2-inch outside diameter (OD) split-spoon sampler at 2½-foot intervals. The sampler was first seated 6 inches and then driven an additional foot with blows of the 140-pound hammer falling 30 inches. The number of hammer blows required to drive the sampler the final foot was recorded and is designated the “standard penetration resistance” (N-value) with units of blows per foot (bpf). The N-value provides a general indication of in-situ soil conditions and has been correlated with certain engineering properties of soils. An automatic trip drop hammer was used for the standard penetration resistance testing. The automatic hammer generally has a higher efficiency than a manual hammer, and may yield lower N values. The N values reported on our boring logs are the field values without any adjustments or “corrections”.

The soil samples obtained during our field activities were visually classified by members of our engineering staff in general accordance with ASTM D2488, the Standard Practice for Description and Identification of Soils (Visual-

Manual Procedure). The resulting soil descriptions are shown on the Test Boring Records in the Appendix. Soil consistencies provided on the boring logs are based on correlations with N-values and visual/manual procedures.

Subsurface water level readings were taken in each of the borings during drilling and upon completion of the soil drilling process. Upon completion of drilling and sampling, each borehole was backfilled with soil cuttings and a borehole closure device. Due to safety concerns, the boreholes were not left open for delayed subsurface water level measurements.

2.2 Laboratory Test Program

Select samples were subjected to moisture content (ASTM D2216) and Atterberg Limits (ASTM D4318) testing to aid our soil classification and to evaluate the relative volume change potential of on-site soils. Laboratory test results are summarized in Section 3.3 of this report.

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3.0 Subsurface Conditions

3.1 Geologic Conditions

3.1.1 Fill Materials

Fill material was encountered in twelve of the test borings during this exploration. Fill can be composed of different soil types from various sources and can also contain debris, organics, topsoil, and/or deleterious materials. The engineering properties of fill depend primarily on its composition, density, and moisture content. If observation and/or test reports are available to document the placement of the encountered fill materials, we request they be provided to us for review and incorporation into our analyses.

3.1.2 Residual Materials

The Geologic Map of the Walterhill Quadrangle, Tennessee (1964, Tennessee Division of Geology) indicates this particular site is underlain by the Ridley Limestone Formation This formation is typically a hard, brownish-gray, fine-grained, medium-bedded to massive limestone with occasional shale partings. The limestone weathers to produce a layer of native soil (residuum) which is typically a brown or reddish-brown silty clay with chert. This formation often includes a variable top of rock profile.

Since the bedrock underlying the site consists of carbonate rock (i.e., limestone/dolomite), the site is susceptible to the typical carbonate 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 the hazards. Of these hazards, the occurrence of sinkholes is potentially the most damaging to overlying soil-supported structures.

In Middle Tennessee, sinkholes occur primarily due to differential weathering of the bedrock and flushing or raveling of overburden soils into cavities in the bedrock. The loss of solids creates a cavity or dome in the overburden. Growth of the dome over time or excavation over the dome can create a condition in which rapid, local subsidence or collapse of the roof of the dome occurs.

A certain degree of risk with respect to sinkhole formation and subsidence must be accepted at any site located within this geologic setting. While a rigorous effort to assess the potential for sinkhole development at this site was beyond our scope of services, we did not observe surficial signs of sinkhole activity at the site. 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. If desired, S&ME can perform additional exploration and assessment to better identify the risk associated with the karst geology.

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3.2 Subsurface Conditions

3.2.1 Summary of Subsurface Conditions

The following is a general summary of the subsurface conditions encountered in the borings.

Table 3-1: Summary of Borings

Boring

No.

Surface

Cover Material

SPT N-Values

(blows per foot) Refusal Depth (feet)

B-107-01 4” Topsoil

Fill 0.3’ to 6’

Fat Clay (CH)

Residual 6’ to 13.8’

Fat Clay (CH)

Fill: 3 to 7

Residual: 16 to 19

(50/1 near AR)

13.8

B-107-02 3” Topsoil

Fill 0.25’ to 6’

Fat Clay (CH)

Residual 6’ to 12.8’

Fat Clay (CH)

Fill: 9 to 10

Residual: 9 to 20 12.8

B-107-03 5” Topsoil

Fill 0.4’ to 3.9’

Lean Clay (CL)

Residual Not Encountered

Fill: 16

(50/3 near AR)

Residual: N/A

3.9

B-107-04 7” Topsoil

Fill 0.6’ to 3’

Fat Clay (CH)

Residual 3’ to 6.4’

Fat Clay (CH)

Fill: 9

Residual: 23

(50/2 near AR)

6.4

B-107-05 7” Topsoil

Fill 0.6’ to 3’

Fat Clay (CH)

Residual 3’ to 14’

Fat Clay (CH)

Fill: 15

Residual: 11 to 15

(50/3 near AR)

B-107-06 4” Topsoil

Fill 0.3’ to 3’

Fat Clay (CH)

Residual 3’ to 12.7’

Fat Clay (CH)

Fill: 9

Residual: 18 to 27 12.7

B-107-07 3” Topsoil

Fill 0.25’ to 6’

Fat Clay (CH)

Residual 6’ to 11.3’

Lean Clay (CL)

Fill: 8 to 14

Residual: 29 to 31 11.3

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Boring

No.

Surface

Cover Material

SPT N-Values

(blows per foot) Refusal Depth (feet)

B-107-08 5” Topsoil

Fill 0.4’ to 3’

Fat Clay (CH)

Residual 3’ to 12.1’

Lean, Fat Clay (CL, CH)

Fill: 9

Residual: 12 to 34 12.1

B-116-01 5” Topsoil

Fill 0.4’ to 3’

Fat Clay (CH)

Residual 3’ to 11’

Fat Clay (CH)

Fill: 11

Residual: 12 to 29

B-116-02 5” Topsoil

Fill 0.4’ to 3’

Fat Clay (CH)

Residual 3’ to 16.2’

Lean, Fat Clay (CL, CH)

Fill: 4

Residual: 10 to 22 16.2

BC-01 4” Topsoil

Fill 0.3’ to 3’

Fat Clay (CH)

Residual 3’ to 11.1’

Lean, Fat Clay (CL, CH)

Fill: 5

Residual: 2 to 23 11.1

BC-02 4” Topsoil

Fill Not Encountered

Residual 0.3’ to 10.6’

Lean, Fat Clay (CL, CH)

Fill: N/A

Residual: 2 to 20 10.6

BC-03 4” Topsoil

Fill 0.3 to 3’

Lean Clay (CL)

Residual 3’ to 11.6’

Lean Clay (CL)

Fill: 8

Residual: 1 to 22 11.6

BC-04 5” Topsoil

Fill Not Encountered

Residual 0.4’ to 9’

Lean Clay (CL)

Fill: N/A

Residual: 0 to 11

(50/4 near AR)

BC-05 1” Topsoil

Fill Not Encountered

Residual 0.1’ to 7.6’

Lean Clay (CL)

Fill: N/A

Residual: 4

(50/3 near AR)

7.6

*NOTES: 1) Topsoil depth could vary significantly from our findings. 2) AR = auger refusal. 3) Fill material included varying amounts of gravel sand, and also included organic material in some borings; although Borings BC-02, BC-04, and B-05 did not appear to have fill based on visual classification, it is likely that the near surface material near those locations also includes fill.

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3.2.2 Subsurface Water

Subsurface water was not encountered in any of the borings at the time of drilling. Post-drilling water levels were not obtained because the borings were backfilled after completion as a safety precaution. It should be noted that groundwater levels fluctuate with seasonal and cyclical temperature and precipitation, and may be higher or lower at other times of the year. Also, it is not uncommon for subsurface water to migrate along the soil/rock interface following periods of inclement weather or for zones of water to be found within the soil overburden.

3.2.3 Test Boring Refusal

All of the borings encountered auger refusal at depths ranging from about 3.9 feet to 16.2 feet below the ground surface. It should be noted that a variable top of rock profile may be present at the site and is common to the site geology. Refusal is a designation applied to material that cannot be penetrated by the power of the drilling equipment. Refusal discussed herein is based on conditions impenetrable to the drilling equipment used in this exploration (i.e., Geoprobe 7822 DT rig) and does not necessarily suggest the conditions would be impenetrable to other equipment.

3.2.4 General

The subsurface descriptions above are of a generalized nature to highlight the major subsurface stratification features and material characteristics. The boring logs included in the Appendix should be reviewed for specific information at individual test locations. The depth and thickness of the subsurface strata indicated on the boring logs were generalized from and estimated between boring locations. The transition between materials may be more gradual than indicated on the boring logs. 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 stratification lines were used for our analytical purposes and, unless specifically stated otherwise, should not be used as the basis for design or construction cost estimates.

3.3 Laboratory Test Results

The moisture content of selected samples from the borings ranged from 18.4 percent to 39.9 percent. Additional test results are summarized in Table 3-2 below.

Table 3-2: Laboratory Test Results

Boring

No.

Depth

(feet)

Liquid

Limit

Plastic

Limit

Plasticity

Index

Classification based on

Plasticity

B-107-02 1-2.5 55 24 31 CH (Fat Clay)

B-107-07 3.5-5 76 35 41 CH (Fat Clay)

B-116-02 3.5-5 74 34 40 CH (Fat Clay)

BC-04 1-2.5 41 21 20 CL (Lean Clay)

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4.0 Conclusions and Recommendations

4.1 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 the boring locations. If it becomes apparent during construction that encountered conditions vary substantially from those presented herein, this office should be notified at once. At that time, the conditions can be evaluated and the recommendations of this report modified, in written form, if necessary. Also, if the scope of the project should change significantly from that described herein, we should be notified and these recommendations should be re-evaluated.

4.2 Site Assessment

Based on the subsurface conditions encountered during this exploration, our assessment includes the following considerations:

4.2.1 Visual Observations

Based on our limited visual reconnaissance, we observed uneven floors and tile with cracks in some interior areas.

We attribute these conditions to settlement and/or slight heaving within the slabs on grade. We did not observe significant cracking of exterior brick veneer or indications of significant exterior foundation settlement. Based on our observations, the cracks and uneven floors appeared to be cosmetic in nature. We observed a “low spot” at

Boring B-107-04, on the south exterior side of Building 107, but based on our exploration, we did not observe indications of a sinkhole at that location.

4.2.2 Previously Placed Fill

Previously placed fill material was encountered in most of the borings to depths of about 3 to 6 feet. We have not been provided documentation regarding the placement of the fill materials. Therefore, we must classify this site as having undocumented fill. If documentation of the fill exists, we request it be forwarded to us for inclusion into our analyses. There is some risk that is associated with having a structure bear on undocumented fill. However, since our borings were adjacent to the existing structure, it is not certain the existing foundations are bearing on undocumented fill. In addition, based on the estimated age of the structures (at least 30 years old) and the results of our exploration, we do not conclude that fill is the primary factor in recent slab settlement.

4.2.3 Fat Clays

Fat clays were encountered in most of the borings. Although these materials can sometimes have workability issues, they can often be used successfully as subgrade material, bearing material, and even as fill if they are in the moderate to high plasticity range, with liquid limits in the 40 to 60 percent range and plasticity indices generally between 20 and 35. However, higher plasticity clays were also encountered at relatively shallow depths at the site.

These more plastic clays have liquid limits greater than 60 percent and plasticity indices above 35. The higher plasticity clays generally appeared to be deeper than 3’, but there may be more shallow zones of high plasticity

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4.2.4 Karst Geology

Since the bedrock underlying this site contains carbonate rock (i.e., limestone/dolomite), it is susceptible to the hazards of a karst geology, including irregular weathering, cave and cavern conditions, and overburden sinkholes.

As such, the owner must be willing to accept some risk of sinkhole development at this site. However, based on our limited visual reconnaissance and our subsurface exploration, we did not observe indications of sinkholes at the boring locations. Additionally, the widespread nature of the reported cracks/uneven floors (Buildings 107, 116, and Connectors between Buildings 5 and 7) does not lead us to conclude sinkhole activity as the cause of distress at this time. If desired, S&ME can perform additional exploration and assessment to better determine the risks associated with the karst geology.

4.2.5 Soft Soils

Soft material was encountered at shallow depths (1-2.5 feet) at Buildings 107 and 116 (Borings B-107-01 and B-

116-02). Soft to very soft material was encountered at depths of 1 to 5 feet at all of the borings at the Connector between Buildings 5 and 7.

4.2.6 Conclusions and Recommendations

Based on the information provided and our exploration, we conclude that the observed floor cracks and uneven slabs may be the result of shrink/swell cycles due to high plasticity clay and/or settlement due to softer soils that have been subjected to water infiltration over time. To address these issues, we recommend the following:

Initially, it may be desirable to perform slab coring and assessment of interior slab subgrades to provide more information on the conditions beneath slabs. Such an approach would help us to better identify whether or not high plasticity soils might be contributing to the slab distress. It might also be desirable to further explore the exterior conditions via test pits to better assess the character and limits of the soft material encountered in our test borings. Crack monitors can also be installed, if desired, to better determine whether cracks are active. Such efforts could be done in a phased approach or all at once, depending on the needs of the owner. Depending on the conditions encountered in follow-up explorations, additional and/or revised recommendations may be required.

Whether or not additional exploration is performed, we recommend a program of regular maintenance of gutters and/or roof drains, as well as other drainage features. Reducing the amount of water exposure to the slab subgrade should help reduce the potential for slab distress, whether the cause is high plasticity clay or soft soil conditions.

In areas with uneven floors, we recommend the floors be leveled, if possible, by either grinding of the slab or via application of a leveling compound. If this approach is not possible, we recommend distressed

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January 3, 2019 10 floor slabs be removed and replaced. If slabs are removed, the subgrade conditions should be assessed prior to new work. Soft soils should be over-excavated and replaced with engineered fill or as otherwise recommended by the geotechnical engineer. If high plasticity soils are encountered directly beneath the slabs, we recommend they be removed to a depth of at least one foot and replaced with engineered fill.

At this time, we do not anticipate that existing foundations will be underpinned or that new foundations will be required, at least not in the initial repair approach. However, if cracks expand in length or width or if other signs of distress occur, additional measures, such as underpinning and/or new foundations may be required.

It is emphasized that our conclusions and recommendations are based on limited information, and if more information becomes available, additional and/or revised recommendations may be required.

The following sections have been included, as requested, to provide general recommendations related to site preparation, fill placement, foundations, slabs, seismic site class, and retaining walls. We do not anticipate that all of these features will be needed to address the existing conditions.

4.3 Site Preparation

4.3.1 General

Since the cracks and uneven floors appear to be primarily cosmetic in nature, site preparation for repairs may be limited. However, to the degree applicable, slabs, foundations, excessively soft or plastic soil, topsoil, and fill with debris/organics should be removed during site preparation. Such removal should extend at least 3 feet beyond the construction limits (deeper if more than 3 feet of material must be removed). Unless they are able to be re-used in non-structural areas, these materials should be removed from the site.

After initial site preparation is complete, the stability of the exposed subgrade in areas to receive fill and/or at-grade areas should be thoroughly assessed by a member of our engineering staff. This evaluation can consist of, but not be limited to, random probing with a small diameter steel rod, observation of a proofroll, and/or shallow test pits/hand auger borings. A proofroll consists of repeated passes from a loaded tandem-axle dump truck or similar piece of heavy, rubber-tired equipment through the subject area. In areas where proofrolling is not possible due to space constraints, the stability of the subgrade should be assessed using probing methods. Areas noted to pump, rut, or deflect under the applied loading should generally be undercut to firm, suitable soils as recommended by the geotechnical engineer. Areas where undercutting is performed should be backfilled with properly compacted structural fill as described in Section 4.4 of this report.

4.3.2 Excavation

As previously noted, auger refusal was encountered at depths ranging from about 3.9 to16.2 feet during our exploration. Therefore, we do not expect the need for rock excavation, unless there are areas where deep cuts will be made for earthwork, foundations, or utility trenches. The actual need for rock excavation will depend on the final structural repair details and the degree to which a variable top of rock profile occurs within the planned construction areas.

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Excavation for temporary or permanent conditions should comply with Occupational Safety and Health

Administration (OSHA) requirements. If excavation is required adjacent to existing structures, care should be exercised so as not to undermine the existing foundations. Where needed, underpinning or other appropriate means should be used to support existing structures during construction or repairs. Safety is solely the responsibility of the contractor.

4.4 Fill Placement and Compaction

4.4.1 Soil Fill

If fill placement is needed, fill operations should not begin until representative samples of proposed fill soils are collected and tested. We recommend allowing 3 to 5 days to complete sampling and testing in advance of fill placement activities. The test results will be used to evaluate whether the proposed fill soils meet appropriate specifications and for quality control during grading.

We recommend structural soil fill be defined as inorganic, natural soil with maximum particle sizes of 4 inches, maximum gravel content of 20 percent, and plasticity index (PI) of 35 and less. Some of the high plasticity clay at the site may have plasticity indices greater than 35 and should only be used with caution. Structural soil fill should be placed in loose, horizontal lifts not exceeding 8 inches in thickness. Each lift should be compacted to at least 98 percent of the maximum dry density (MDD) as determined by the standard Proctor method (ASTM D 698). The moisture content should be controlled to within 3 percentage points of optimum moisture content. In addition to meeting the compaction requirement, fill material should be stable under movement of the construction equipment and should not exhibit rutting or pumping.

The fill should be uniformly well compacted. Accordingly, fill placement should be observed by a qualified field technician working under the direction of our geotechnical engineer. In addition to this visual evaluation, the technician should perform in-place field density tests to confirm whether the contractor’s means and methods are capable of achieving the recommended compaction. Any areas that do not meet the compaction specification should be re-compacted to achieve compliance.

4.5 Site Degradation during Construction

Subgrade surfaces that are stable at the time of grading can become unstable during wet weather and/or as heavy construction equipment traffic moves over the prepared surface. Subgrade damage can be reduced by maintaining positive surface drainage during grading operations and construction to prevent water from ponding on the surface. Additionally, the surface should be rolled smooth to enhance drainage if precipitation is expected.

Subgrades damaged by construction equipment should be promptly repaired to avoid further degradation in adjacent areas and to prevent water ponding. Construction traffic should be limited to specific areas during grading to avoid degrading subgrades throughout the site, particularly after precipitation events. The geotechnical engineer should be contacted to provide recommendations for treatment if the soils become excessively wet or dry, or frozen.

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4.6 Foundations

The exploration findings indicate that the building can be supported by footings bearing on approved residual soils or properly compacted soil fill. We recommend using a maximum allowable net soil bearing pressure of

2,500 pounds per square foot (psf) to size footings supported by approved material for Buildings 107, 116, and the Connector between Buildings 5 and 7. If soft or loose areas are encountered during foundation construction, they should be thoroughly evaluated. It is noted that underpinning or some over-excavation and replacement may ultimately be required in areas with soft soils. Based on our exploration, we anticipate that maximum over-excavation would be less than 5 feet, although the depth could vary. As previously noted, if excavations are required adjacent to existing foundations, care should be exercised so as not to undermine the existing foundations or otherwise, the existing foundations should be underpinned.

Minimum strip and individual spread footing widths should be at least 18 inches and 24 inches wide, respectively.

This recommendation is made to help prevent a "localized" or "punching" shear failure condition that could exist with very narrow footings. Foundations can be constructed at a minimum of 18 inches below subgrade. Constructing the foundations at this depth provides confinement and protection against frost penetration.

We recommend that individual footings bear on only one type of material. If competent rock is encountered at or above bearing elevation, we recommend that rock be over-excavated at least 12 inches and replaced with engineered fill or other material approved by the geotechnical engineer.

Loose or soft soil, debris, or excess surface water should be removed from the foundation excavations before concrete or reinforcing steel is placed. Foundation subgrades should also be level or suitably benched. Opened foundation excavations should be backfilled with concrete the same day they are opened. Footings should be poured “neat” to the excavation so that water cannot collect behind forms before backfilling. A 2- to 3-inch thick mud-mat of lean concrete may be used to protect the exposed foundation soils if the opened excavations cannot be backfilled with concrete the same day they are opened.

Excavations for foundations should be observed by a member of our staff prior to placement of reinforcing steel and concrete. Foundation evaluations may consist of, but not be limited to hand auger borings and portable dynamic cone penetrometer testing, as well as probing with a small diameter steel rod between test locations.

If the recommendations in this report are followed, we estimate total settlement of 1 inch or less and differential settlement of ½ inch or less over a distance of about 30 feet. This assumes that excessively soft zones are addressed, as required.

4.7 IBC Seismic Site Class

In accordance with the 2012 International Building Code, it is our opinion that a Seismic Site Class of C can be used for design of the structures, based on the subsurface conditions encountered during our exploration and our knowledge of the site geology. Based on the depth to rock, we do not believe a site class of A or B will be appropriate for this site.

3400 Lebanon Road; Murfreesboro, Tennessee

S&ME Project No. 1247-18-038

January 3, 2019 13

4.8 Slab-On-Grade

Where needed for the repair details, slabs may be supported at grade on residual soils and/or approved fill material, provided the subgrade is prepared according to the recommendations in this report. The slab should be constructed over at least 4 inches of compacted, dense-grade aggregate (DGA) base. The purpose of the base is to provide a uniform bearing surface and should not be considered a part of the slab design. Provided that the slab is underlain by 4 inches of DGA, a modulus of subgrade reaction, ks, of 150 pounds per cubic inch (pci) can be used in the design.

Foundation and utility line installation, weather, and other construction activities can disturb the floor slab subgrade between completion of grading and slab construction. For this reason, our geotechnical engineer should evaluate the subgrade immediately prior to placing the base materials and slab concrete. During this evaluation, the subgrade should be thoroughly evaluated by our personnel and areas judged to be unstable should be undercut and replaced as recommended by our geotechnical engineer.

Based on the results of our exploration, the floor slab is not likely to be subjected to hydrostatic pressure from groundwater. However, water vapor transmission through the slab is still a design consideration. Evaluating the need for and design of a moisture retarder or moisture barrier for moisture control is outside our scope of services and should be provided by the floor slab designer based on the planned floor coverings and the corresponding design constraints, as outlined in ACI 302.1R-04 Guide for Concrete Floor and Slab Construction.

Further, health and environmental considerations with respect to any potentially harmful vapor transmission are also outside of our scope.

4.9 Retaining Walls

We have not been given detailed design or grading information at this time and are not aware of specific exterior retaining walls for this project. However, we are providing general recommendations related to small site walls in the event they are to be incorporated into the repair design. Retaining walls that can rotate at the top may be designed for the “active” earth pressure condition. Retaining walls that are fixed at the top and cannot rotate, such as basement walls, should be designed for “at-rest” earth pressure conditions. Soils behind the retaining walls exert a triangular stress distribution which can be modeled in terms of an “equivalent fluid”.

Onsite soils generally have significant clay content and are not recommended for use as wall backfill. We recommend use of select, free draining, granular fill material, free of organics and other deleterious materials such as No. 57 gradation washed stone within a 1:1 upward slope from the bottom of the wall foundation.

Alternatively, a 6 inch perforated polyethylene pipe covered with a two foot column of No. 57 stone, wrapped with a non-woven filter fabric may also be used immediately behind exterior retaining walls, and on-site material may be used as remaining backfill. The two foot column of stone immediately behind the exterior retaining wall should be capped with 2 feet of relatively impervious material and graded to drain away from the wall. We recommend the following ultimate values for the design of retaining walls on this site:

3400 Lebanon Road; Murfreesboro, Tennessee

January 3, 2019 14

Table 4-1 Below-grade Wall Design Parameters

Design Quantity Material Value

Level Backfill

Active earth pressure coefficient (Ka) #57 gradation washed stone 0.3*

Equivalent fluid unit weight (active) #57 gradation washed stone 30 pcf*

At Rest earth pressure coefficient (Ko) #57 gradation washed stone 0.5*

Equivalent fluid unit weight (at rest) #57 gradation washed stone 50 pcf*

Active earth pressure coefficient (Ka) Compacted site fill 0.45

Equivalent fluid unit weight (active) Compacted site fill 55 pcf

At Rest earth pressure coefficient (Ko) Compacted site fill 0.6

Equivalent fluid unit weight (at rest) Compacted site fill 70 pcf friction coefficient Concrete and rock 0.55 friction coefficient Concrete and soil 0.35

*These values only apply if #57 stone is placed in areas within a 1:1 upward slope from bottom of wall foundation; otherwise, use compacted site fill values

If a uniform area surcharge (including a sloped backfill) is applied behind the wall, a portion of the surcharge is transferred to the wall in the form of a uniform or rectangular lateral stress distribution. The magnitude of the lateral stress transferred to the wall is a function of the soil’s strength and the permissible degree of deflection or rotation. It is computed by multiplying the soil’s “earth pressure coefficient” by the magnitude of the surcharge.

Surcharge loading should be expected for below grade walls and will depend on the slab load as well as final structural column and wall foundation layout.

The above values also assume adequate drainage is present behind the wall to prevent the build-up of hydrostatic pressure. The free draining granular wall backfill recommended may also be incorporated into the retaining wall drainage system, assuming a filtered, reliable outlet is provided.

We are not aware of details associated with retaining walls that may be required for this site. The above values were provided for a conventional cantilevered retaining wall. It should be noted that if other wall types are required or if significant slopes are planned, additional exploration, testing, and assessment, including global stability analysis, may be required.

3400 Lebanon Road; Murfreesboro, Tennessee

S&ME Project No. 1247-18-038

January 3, 2019 15

5.0 Follow-Up Services

Field observations, monitoring, and Quality Assurance testing during site grading, foundation, and slab and retaining wall construction activities are an extension of the geotechnical design. We recommend that we be allowed to continue our involvement in the project through these phases of construction.

Competent personnel under the general administrative supervision of a geotechnical engineer familiar with the design requirements and considerations of this project should perform Quality Assurance observations and testing related to earthwork. We recommend that qualified geotechnical personnel observe proofrolling and associated undercutting (as required), evaluate foundation excavation and subgrades, evaluate the materials to be used as fill, and test the compaction of all fill and backfill. The monitoring of the earthwork activities should be performed on a full-time basis.

6.0 Limitations

This report has been prepared in accordance with generally accepted geotechnical engineering practice for specific application to this project. The conclusions and recommendations contained in this report are based upon applicable standards of our practice in this geographic area at the time this report was prepared. No other representation or warranty either expressed or implied, is made.

We relied on project information given to us to develop our conclusions and recommendations. If project information described in this report is not accurate, or if it changes during project development, we should be notified of the changes so that we can modify our recommendations based on this additional information, if necessary.

Our conclusions and recommendations are based on limited data from a field exploration program. Subsurface conditions can vary widely between explored areas. Some variations may not become evident until construction. If conditions are encountered which appear different than those described in our report, we should be notified. This report should not be construed to represent subsurface conditions for the entire site.

Unless specifically noted otherwise, our field exploration program did not include an assessment of regulatory compliance, environmental conditions or pollutants or presence of any biological materials (mold, fungi, and bacteria). If there is a concern about these items, other studies should be performed. S&ME can provide a proposal and perform these services if requested. S&ME should be provided the opportunity to review the final plans and specifications to confirm that earthwork, foundation, and other recommendations are properly interpreted and implemented. The recommendations in this report are contingent on S&ME’s review of final plans and specifications followed by observation and monitoring of earthwork and foundation construction activities.

The recommendations in this report are only applicable to areas within the vicinity of our exploration and should not be used for other areas or for structures not specifically addressed in this report.

Appendices

Appendix I – Figures

SCALE:

DATE:

PROJECT NUMBER

FIGURE NO.

NOT TO SCALE

12-6-18

1247-18-038

VA STRUCTURAL REPAIRS

LEBANON ROAD

MURFREESBORO, TENNESSEE

SITE LOCATION PLAN

REFERENCE:

GOOGLE EARTH

SITE

SCALE:

DATE:

PROJECT NUMBER

FIGURE NO.

AS SHOWN

12-6-18VA STRUCTURAL REPAIRS

LEBANON ROAD

MURFREESBORO, TENNESSEE

TEST LOCATION PLAN

REFERENCE:

GOOGLE EARTH

B107-08

B107-03 B107-06

B107-07

BC-04

BC-01

BC-02

BC-05

B107-04

B107-01

BC-03

B107-02

B116-01

B116-02

B107-05

1247-18-038

Appendix II – Field Exploration

Core Diameter Inches

BQ 1-7/16

NQ 1-7/8

HQ 2-1/2

TEST BORING RECORD LEGEND

FINE AND COARSE GRAINED SOIL INFORMATION

COARSE GRAINED SOILS

(SANDS & GRAVELS)

FINE GRAINED SOILS

(SILTS & CLAYS)

PARTICLE SIZE

N Relative Density N Consistency Qu, KSF

Estimated Boulders Greater than 300 mm (12 in)

0-4 Very Loose 0-1 Very Soft 0-0.5 Cobbles 75 mm to 300 mm (3 to 12 in)

5-10 Loose 2-4 Soft 0.5-1 Gravel 4.74 mm to 75 mm (3/16 to 3 in)

11-20 Firm 5-8 Firm 1-2 Coarse Sand 2 mm to 4.75 mm

21-30 Very Firm 9-15 Stiff 2-4 Medium Sand 0.425 mm to 2 mm

31-50 Dense 16-30 Very Stiff 4-8 Fine Sand 0.075 mm to 0.425 mm

Over 50 Very Dense Over 30 Hard 8+ Silts & Clays Less than 0.075 mm

The STANDARD PENETRATION TEST as defined by ASTM D 1586 is a method to obtain a disturbed soil sample for examination and testing and to obtain relative density and consistency information. A standard 1.4-inch I.D./2-inch O.D. split-barrel sampler is driven three 6-inch increments with a 140 lb. hammer falling 30 inches. The hammer can either be of a trip, free-fall design, or actuated by a rope and cathead. The blow counts required to drive the sampler the final two 6-inch increments are added together and designate the N-value defined in the above tables.

ROCK PROPERTIES

ROCK QUALITY DESIGNATION (RQD) ROCK HARDNESS

Percent RQD Quality Very Hard: Rock can be broken by heavy hammer blows

0-25

25-50

50-75

75-90

90-100

Very Poor

Poor

Fair

Good

Excellent

Hard:

Rock cannot be broken by thumb pressure, but can be broken by moderate hammer blows.

Moderately Hard:

Small pieces can be broken off along sharp edges by considerable hard thumb pressure; can be broken with light hammer blows.

Soft:

Rock is coherent but breaks very easily with thumb pressure at sharp edges and crumbles with firm hand pressure.

Very Soft:

Rock disintegrates or easily compresses when touched; can be hard to very hard soil.

RQD = Sum of 4 in. and longer Rock Pieces Recovered Length of Core Run

X100 !QD

NQ

REC

Recovery = Length of Rock Core Recovered

Length of Core Run X100

SYMBOLS

KEY TO MATERIAL TYPES SOIL PROPERTY SYMBOLS

N: Standard Penetration, BPF

M: Moisture Content, %

LL: Liquid Limit, %

PI: Plasticity Index, %

Qp: Pocket Penetrometer Value, TSF

Qu:

Unconfined Compressive Strength Estimated Qu, TSF

D: Dry Unit Weight, PCF

F: Fines Content

SAMPLING SYMBOLS

Topsoil

Asphalt

Crushed Aggregate

Fill Material

Shot-rock Fill

Low Plasticity Inorganic Silt

High Plasticity Inorganic Silt

Low Plasticity Inorganic Clay

High Plasticity Inorganic Clay

Low Plasticity Inorganic Silt or Clay

High Plasticity Inorganic Silt or Clay

Organic Silts/Clays

Well-Graded Gravel

Poorly-Graded Gravel

Silty Gravel

Clayey Gravel

Well-Graded Sand

Poorly-Graded Sand

Silty Sand

Clayey Sand

Peat

Limestone

Sandstone

Siltstone

Shale

Claystone

Weathered Rock

Dolomite

Granite

Gneiss

Schist

Amphibolite

Metagraywacke

Phylite

Undisturbed Sample

Split-Spoon Sample

Rock Core Sample

Auger or Bag Sample

No Sample Recovery

Water Level at Time of Drilling

Delayed Water Level Reading

0-4

5-10

11-30

31-50

Over 50

Very Loose

Loose

Medium Dense

Dense

Very Dense

3.0

2.0

4.5+

4.5

50/1

50/1

TOPSOIL - 4 inches

FILL: FAT CLAY (CH) - soft to firm, reddish brown with black, with chert, damp

RESIDUUM: FAT CLAY (CH) - very stiff, reddish brown with black tan, with chert, moist

Refusal at 13.8 feet Boring terminated at 13.8 feet

MATERIAL DESCRIPTION

BORING LOG B-107-01

1s t 6 in

R U

N

BLOW COUNT

/ CORE DATA

E

LE

V A

T

IO

N

(f ee t)

W A

T E

R L

E V

E L

THIS LOG IS ONLY A PORTION OF A REPORT PREPARED FOR THE NAMED

PROJECT AND MUST ONLY BE USED TOGETHER WITH THAT REPORT.

BORING, SAMPLING AND PENETRATION TEST DATA IN GENERAL

ACCORDANCE WITH ASTM D-1586.

STRATIFICATION AND GROUNDWATER DEPTHS ARE NOT EXACT.

WATER LEVEL IS AT TIME OF EXPLORATION AND WILL VARY.

1.

2.

3.

4.

SPT N-Value (bpf)

P oc ke t P en ts f)

2n d

6i n

/ R

EC

3r d

6i n

/ R Q

D

S A

M P

LE

T

Y P

E

S A

M P

LE

N

O

G R

A P

H

IC

LO

G

N V

A

LU

E

D E

P T

H

(f ee t)

NOTES:

10 20 30 40 50 60 70 80 90

PL LLNM

FINES %FINES %

LOGGED BY: Eric Conway, E.I.

NOTES:

CAVE-IN DEPTH: N/A

PROJECT: Veterans Affairs Structural Repairs Murfreesboro, Tennessee

S&ME Project No. 1247-18-038

CLIENT: Design-Aire Engineering

DATE DRILLED: 12/12/18

DRILL RIG: Geoprobe 7822DT

DRILLER: Tri-State Drilling LLC

HAMMER TYPE: Automatic

SAMPLING METHOD: Split spoon

DRILLING METHOD: 2 1/4 inch Hollow Stem Auger

ELEVATION:

BORING DEPTH: 13.8 ft

WATER LEVEL: dry

S

M E

B O

R

IN

G L

O G

S

P T

A N

D P

P Q

N M

V A

S T

R U

C T

U R

A L

R E

P A

IR

S

B O

R

IN

G L

O G

S .G

P J

G

IN

T S

T D

U S

L A

B .G

D T

/2

/1

3.25

3.0

4.5

2.5

TOPSOIL - 3 inches

FILL: FAT CLAY (CH) - stiff, reddish brown with black, with chert

FAT CLAY (CH) - very stiff to stiff, orangish brown with black, with chert

Refusal at 12.8 feet Boring terminated at 12.8 feet

MATERIAL DESCRIPTION

BORING LOG B-107-02

1s t 6 in

R U

N

BLOW COUNT

/ CORE DATA

E

LE

V A

T

IO

N

(f ee t)

W A

T E

R L

E V

E L

THIS LOG IS ONLY A PORTION OF A REPORT PREPARED FOR THE NAMED

PROJECT AND MUST ONLY BE USED TOGETHER WITH THAT REPORT.

BORING, SAMPLING AND PENETRATION TEST DATA IN GENERAL

ACCORDANCE WITH ASTM D-1586.

STRATIFICATION AND GROUNDWATER DEPTHS ARE NOT EXACT.

WATER LEVEL IS AT TIME OF EXPLORATION AND WILL VARY.