36C78619B0018-005.pdf

REPORT C OVER PAGE

Geotechnical Engineering Report Fayetteville National Cemetery Expansion

Fayetteville, Arkansas

October 26, 2018

Terracon Project No. 35185052

Prepared for:

Vali Cooper International

Covington, Louisiana

Prepared by:

Terracon Consultants, Inc.

Little Rock, Arkansas mailto:Taqi@valiint.com

REPORT TOPICS

REPORT TOPICS

INTRODUCTION

SITE CONDITIONS

PROJECT DESCRIPTION

GEOTECHNICAL CHARACTERIZATION

GEOTECHNICAL OVERVIEW

EARTHWORK

SHALLOW FOUNDATIONS

SEISMIC CONSIDERATIONS

FLOOR SLABS

LATERAL EARTH PRESSURES

PAVEMENTS

GENERAL COMMENTS

Note: This report was originally delivered in a web-based format. Orange Bold text in the report indicates a referenced section heading. The PDF version also includes hyperlinks which direct the reader to that section and clicking on the logo will bring you back to this page. For more interactive features, please view your project online at client.terracon.com.

ATTACHMENTS

EXPLORATION AND TESTING PROCEDURES

SITE LOCATION AND EXPLORATION PLAN

EXPLORATION RESULTS

SUPPORTING INFORMATION

http://client.terracon.com/

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INTRODUCTION

Geotechnical Engineering Report

Fayetteville National Cemetery Expansion

700 South Government Avenue

Fayetteville, Arkansas Terracon Project No. 35185052

October 26, 2018

INTRODUCTION

This report presents the results of our subsurface exploration and geotechnical engineering services performed for the proposed Fayetteville National Cemetery expansion to be located at

700 South Government Avenue in Fayetteville, Arkansas. The purpose of these services is to provide information and geotechnical engineering recommendations relative to:

■ subsurface soil and rock conditions ■ floor slab design and construction

■ groundwater conditions ■ pavement design and construction

■ site preparation and earthwork ■ seismic site classification per IBC

■ foundation design and construction

The geotechnical engineering scope of work for this project included the advancement of twelve test borings to depths of about 10 to 15 feet, or to auger refusal, whichever occurs first. Auger refusal was encountered in the borings at depths ranging from approximately 7.5 to 14.4 feet below existing site grades.

Maps showing the site and boring locations are shown in the Site Location and Exploration

Plan sections, respectively. The results of the laboratory testing performed on soil samples obtained from the site during the field exploration are included on the boring logs in the

Exploration Results section of this report.

Fayetteville National Cemetery Expansion ■ Fayetteville, Arkansas

October 26, 2018 ■ Terracon Project No. 35185052

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SITE CONDITIONS

The following description of site conditions is derived from our site visit in association with the field exploration and our review of publicly available geologic and topographic maps.

Item Description

Parcel information

The project is located at 700 South Government Avenue in Fayetteville, Arkansas

Latitude: 36.0532° Longitude: -94.1699°

See Site Location Plan

Existing improvements Existing Fayetteville National Cemetery

Current ground cover Grass

Existing topography The site slopes downhill to the southwest with an elevation difference of about 9 feet across the site boundaries

Geology 1, 2

Fayetteville Shale - The Fayetteville Shale is a black, fissile, concretionary, clay shale. Dark-gray, fine-grained limestones commonly are interbedded with the shales in north-central Arkansas

1. Interactive Geologic Map of Arkansas and Geological Google Earth files published by the Arkansas

Geological Survey, 2015, www.geology.ar.gov

2. “Stratigraphic Summary of Arkansas”, published by the Arkansas Geological Commission, 1998, revised

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PROJECT DESCRIPTION

Our initial understanding of the project was provided in our proposal and was discussed in the project planning stage. A period of collaboration has transpired since the project was initiated, and our final understanding of the project conditions is as follows:

Information provided Information provided by Mr. Taqi Muhammad via email on September 17, Proposed structure

The proposed expansion at the Fayetteville National Cemetery is planned over an area of about 2.13 acres over five tracts. We understand that the expansion will include a columbarium area, a crypt field, and an in-ground cremains area, with associated parking and drive areas. A new maintenance building is planned for Lot 5

Building construction

We have assumed the building construction will consist of:

■ Wood or Steel frame

■ Slab-on-grade

Maximum loads

Structural loads were not provided. We considered the following building loads for developing the design recommendations:

■ Columns: 50 kips maximum

■ Walls: 5 kips per linear foot maximum

■ Slabs: 150 pounds per square foot maximum

If loads exceed those described, Terracon should be contacted to evaluate and verify the recommendations outlined in this report are suitable for the anticipated loads.

Grading/slopes We expect final grade will remain near existing grade

Below grade structures Crypt field

Free-standing retaining walls Future columbarium retaining wall along western boundary of site

Pavements Concrete or asphalt pavement for drive and parking areas

Estimated start of construction Late 2018 or early 2019

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GEOTECHNICAL CHARACTERIZATION

Subsurface Profile

We have developed a general characterization of the subsurface conditions based upon our review of the subsurface exploration, laboratory data, geologic setting and our understanding of the project. This characterization, termed GeoModel, forms the basis of our geotechnical calculations and evaluation of site preparation and foundation options. Conditions encountered at each exploration point are indicated on the individual logs. The individual logs can be found in the

Exploration Results section and the GeoModel can be found in the Figures section of this report.

Stratification boundaries on the boring logs and GeoModel represent the approximate location of changes in native soil types; in situ, the transition between materials may be gradual.

Groundwater Conditions

The boreholes were observed while drilling and after completion for the presence and level of groundwater. Groundwater was observed at a depth of about 12 feet while drilling at Boring B-9, and at depths of about 8 and 9.5 feet after boring completion at Borings B-7 and B-9. Groundwater was not observed in the other borings while drilling, or for the short duration that the borings could remain open. However, this does not necessarily mean these borings terminated above groundwater. Due to the low permeability of the soils encountered in the borings, a relatively long period may be necessary for a groundwater level to develop and stabilize in a borehole in these materials. Long term observations in piezometers or observation wells sealed from the influence of surface water are often required to define groundwater levels in materials of this type.

Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff and other factors not evident at the time the borings were performed. Therefore, groundwater levels may establish at time of construction or during the life of the project. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project.

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GEOTECHNICAL OVERVIEW

The soil stratigraphy at this site is a surficial layer of lean clay and fat clay soils containing varying amounts of sand to depths of about 6 to 10 feet below the existing ground surface at all the borings. The clay soils were underlain by highly weathered shale bedrock to the maximum depths explored of about 7.4 to 14.4 feet at all the borings except Boring B-6, in which auger refusal was observed in fat clay soils at a depth of about 8 feet. Groundwater was observed at a depth of about

12 feet while drilling at Boring B-9, and at depths of about 8 and 9.5 feet after boring completion at

Borings B-7 and B-9. Groundwater was not observed in the other borings while drilling or after boring completion.

Near-surface low-strength (soils with SPT N-values equal to or less than 5 blows per foot) soils were observed to depths of about 2 to 3.5 feet at the Borings B-8, B-9 and B-12. In their present condition, the low-strength soils are not suitable for providing direct support to new fill, shallow foundations, on-grade slabs or pavements. Subgrade improvement will be required to support new fills, shallow foundations, slabs-on-grade or pavements on these soils. We recommend that the low-strength soils be overexcavated and replaced with new engineered fill beneath the maintenance building and columbarium areas.

Existing fill consisting of poorly graded gravel soils was observed at Boring B-3 to a depth of about

0.3 feet below the existing ground surface. We assume that the existing fill was constructed as part of the existing site development near that boring. We understand that the existing fill will be removed as part of the earthwork required for the planned in-ground cremains area.

Expansive soils are present at this site. The high-plasticity soils are prone to volume changes with variations in moisture content. Based on the laboratory test results and the subsurface conditions observed at Borings B-8 and B-9, we estimate a potential vertical rise (PVR) of about

1 to 2 inches could be possible at the existing ground surface at the maintenance building area.

The typical method for mitigating the effects of expansive soils for these types of structures is to undercut some of the soil and construct a building pad of low volume-change engineered fill below the floor slab of the thickness required to reduce the PVR to about 1 inch. We recommend that at least 2 feet of existing soils within the building footprint be undercut below the finished subgrade elevation and replaced with at least 2 feet of low-volume change engineered fill. Terracon should be contacted to evaluate the potential of slab movement and revise our recommendations, if necessary, after finished floor elevation and the final grading plan are available. More detailed recommendations are discussed in the Earthwork section.

This report provides recommendations to help mitigate the effects of soil shrinkage and expansion. However, even if these procedures are followed, some movement and (at least minor) cracking in the structure should be anticipated. The severity of cracking and other damage such as uneven floor slabs will probably increase if modification of the site results in excessive wetting

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The near-surface soils observed in the boring locations are moisture-sensitive and susceptible to strength loss with moisture content increase, and when exposed to repetitive construction traffic.

We anticipate subgrade improvement could be necessary during site grading and construction to support the planned columbarium, building and pavements, as well as construction traffic, particularly when wet conditions exist.

Based on the subsurface conditions observed at the boring locations, the columbarium and maintenance building can be supported on conventional shallow footing foundations bearing on tested and approved, native lean clay soils or new engineered fill. The Shallow Foundation section addresses support of the columbarium and building bearing on native lean clay soils or new engineered fill. The Floor Slab section addresses the floor slab-on-grade supported on new engineered fill.

The pavements can be supported on new, engineered fill. Recommendations for designing and constructing flexible and rigid pavement systems are provided in the Pavements section.

The General Comments section provides an understanding of the report limitations.

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EARTHWORK

Earthwork will include clearing and grubbing, excavations and fill placement. The following sections provide recommendations for use in the preparation of specifications for the work. These recommendations include critical quality criteria as necessary to render the site in the state considered in our geotechnical engineering evaluation for the building foundations.

Site Preparation

It is our understanding that a maintenance building exists at the time of this report at Lot 3. This structure will be razed and reconstructed at Lot 5 as part of the site development. Any remaining above- and below-grade elements, including the floor slab, foundations, septic lines, and pavement should be removed. Attention should be given to removing all loose or poorly compacted existing fill materials that are often associated with existing buildings. All existing utilities should be properly abandoned. This should include removal of all poorly compacted trench backfill extending into the proposed in-ground cremains area. Excavation created by demolition and removal of existing features should be backfilled with engineered fill that is placed and compacted as recommended in this report.

Surface vegetation, topsoil, and any other existing surface or subsurface structures, should be removed from the construction areas. Complete stripping of the topsoil should be performed in any of the proposed building and parking/driveway areas.

As discussed in the Geotechnical Overview section, we recommend removing the low-strength soils within the columbarium and maintenance building footprint and replacing with new, engineered fill.

Additionally, the on-site fat clay soils have a high potential for shrink and swell movement with variations in moisture content. We recommend removing and replacing the native fat clays exposed in the maintenance building subgrade with low volume-change, new engineered fill to a minimum depth of 2 feet below the finished building subgrade elevation. The native fat clays should be excavated and replaced extending at least 5 feet beyond the outside perimeter of the building footprint. Terracon should be contacted to review and revise our recommendations, if necessary, after finished floor elevation and the final grading plan are available.

The near-surface fill and native soils observed at the boring locations are moisture-sensitive and susceptible to strength loss with moisture content increase, and when subjected to repetitive construction traffic. We anticipate subgrade improvement could be necessary during site preparation and grading, particularly if the soils are wet and exposed to repetitive construction traffic. We recommend Terracon be retained to evaluate the site conditions during site grading and construction, and provide subgrade improvement recommendations based on the actual conditions.

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After stripping the surface materials and completing any undercuts required for removing the existing fill, low-strength soils and high-plasticity soils, and/or site grading, but prior to placing new fill, the subgrade should be proof-rolled to aid in locating soft areas. Terracon should observe the site to confirm that the site has been effectively stripped of unsuitable materials. Terracon should also monitor a proof-rolling procedure to evaluate and approve the stability of the exposed subgrade materials. Proof-rolling can be performed with a rubber-tired construction vehicle weighing at least 25 tons, such as a loaded scraper or tandem-axle dump truck. If proof-rolling is not practical, the subgrade should be evaluated by Terracon using other methods.

Unstable areas identified by proof-rolling or evaluation should be scarified, moisture conditioned, and compacted, or removed and replaced full-depth with new engineered fill. The appropriate method of improvement, if required, would depend on factors such as schedule, weather, the size of area to be improved, and the nature of the instability. Performing site grading operations during warm, dry periods would help reduce the amount of subgrade treatment required.

After proof-rolling and treating any unstable soils, and just prior to placing fill in areas below design grade, the top 9 inches of the subgrade should be scarified, moisture conditioned to within 1 percent below to 3 percent above the material’s optimum moisture content, and compacted to the density recommended in the Compaction Requirements table below.

Close monitoring of the site preparation operations will be critical in providing proper subgrade support for fill placement and support of the on-grade slabs and foundations. This is why we recommend Terracon be retained during initial critical phases of the earthwork to observe the actual site conditions and make the necessary recommendations.

Fill Material Types

Fill required to achieve design grade should be classified as structural fill and general fill.

Structural fill is that material used below, or within 10 feet of structures, pavements or constructed slopes. General fill is that material used to achieve grade outside of these areas. Earthen materials used for structural and general fill should meet the following material property requirements:

Soil Type 1 USCS Classification Acceptable Location for Placement

Imported low volume-change material

CL, GC, SC

LL ≤ 45 and 10 ≤ PI ≤ 20 All locations and elevations

On-site lean soils 2

CL

LL ≤ 45 and 10 ≤ PI ≤ 20 All locations and elevations

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Soil Type 1 USCS Classification Acceptable Location for Placement

On-site fat clay soils 3

CH

LL ≥ 45 or PI≥20

Below upper 2 feet of floor slab bearing elevation and any other lightly-loaded structures, below upper 1 foot of pavements

Well-graded granular GW/GM 4 Beneath floor slabs and pavements

1. Structural and general fill should consist of approved materials that are free of organic matter and debris.

Frozen material should not be used, and fill should not be placed on a frozen subgrade. A sample of each material type should be submitted to the Geotechnical Engineer for evaluation prior to use on this site.

2. The lean clay soils can be re-used as engineered fill provided they are tested and meet the requirements for low volume-change engineered fill.

3. The fat clay soils should not be re-used as engineered fill.

4. Similar to AHTD Class 7 aggregate base course.

Fill Compaction Requirements

Structural and general fill should meet the following compaction requirements.

Fill lift thickness 9 inches or less in loose thickness

Compaction requirements 1 At least 95 percent of the material’s standard Proctor maximum dry density (ASTM D 698)

Moisture content cohesive soil

Within 1 percent below to 3 percent above the material’s optimum moisture content value as determined by the standard Proctor test at the time of placement and compaction

Moisture content granular material 2 Workable moisture levels

1. We recommend that engineered fill be tested for moisture content and compaction during placement.

Should the results of the in-place density tests indicate the specified moisture or compaction limits have not been met, the area represented by the test should be reworked and retested as required until the specified moisture and compaction requirements are achieved

2. Specifically, moisture levels should be maintained low enough to allow for satisfactory compaction to be achieved without the granular fill material pumping when proof-rolled

Utility Trench Backfill

All trench excavations should be made with sufficient working space to permit construction including backfill placement and compaction. Utility trenches are a common source of water infiltration and migration. If utility trenches are backfilled with relatively clean granular material, they should be capped with at least 18 inches of cohesive fill to reduce the infiltration and conveyance of surface water through the trench backfill.

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Grading and Drainage

All grades must provide effective drainage away from the building during and after construction and should be maintained throughout the life of the structure. Water retained next to the building can result in soil movements greater than those discussed in this report. These greater movements can result in unacceptable differential floor slab and/or foundation movements, cracked slabs and walls, and roof leaks. The roof should have gutters/drains with downspouts that discharge onto splash blocks at a distance of at least 10 feet from the building.

Exposed ground should be sloped and maintained at a minimum 5 percent away from the building for at least 10 feet beyond the perimeter of the building. Locally, flatter grades may be necessary to transition ADA access requirements for flatwork. After building construction and landscaping, final grades should be verified to document effective drainage has been achieved. Grades around the structure should also be periodically inspected and adjusted as necessary as part of the structure’s maintenance program. Where paving or flatwork abuts the structure a maintenance program should be established to effectively seal and maintain joints and prevent surface water infiltration.

Earthwork Construction Considerations

Unstable subgrade conditions are likely to develop during general construction operations, particularly where the soils are wetted and/or subjected to repetitive construction traffic. Unstable soils, where encountered, should be improved in-place prior to placing new engineered fill. In some areas, it may be necessary to strip and/or undercut the rutted and wet surface soils prior to performing ground improvement. Subgrade improvement techniques are discussed in detail in the following paragraphs.

The near-surface fill and native soils observed at the site are susceptible to disturbance from construction activity, particularly when the soil has a high natural moisture content or is wetted by surface water or seepage. During wetter periods of the year, these soils will pump and rut under the weight of heavy construction equipment, especially rubber-tired vehicles. The contractor should consider using track-mounted (low ground pressure) equipment to reduce subgrade disturbance and/or instability. Dedicated haul roads and work areas should be used for construction traffic on the building and pavement subgrades.

After the stripping operations, care should be taken to maintain the subgrade moisture content prior to new fill placement. If the subgrade should become excessively wet or dry, frozen, or disturbed, the affected material should be removed or these materials should be scarified, moisture conditioned, and compacted to meet the requirements in the Compaction

Requirements table, or replaced with new engineered fill.

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If site grading occurs during wet periods of the year or if wet conditions develop, the potential for subgrade issues will increase. Alternatives for subgrade improvement could include the following:

■ Scarification and Recompaction - It may be feasible to scarify, dry, and recompact the exposed soils. The success of this procedure would depend primarily upon favorable weather and sufficient time to dry the soils. Even with adequate time and weather, stable subgrade may not be achievable if the thickness of the soft soil is greater than 1 to 1-1/2 feet. The soil should be moisture conditioned and compacted to meet the requirements in the Compaction Requirements table.

■ Crushed Stone - Crushed stone or gravel could be used to improve subgrade stability.

Typical undercut depths would range from 1 foot to 2 feet below finished subgrade elevation. The use of high modulus geotextiles (i.e., engineering fabric or geogrid) could also be considered after underground work such as utility construction is completed.

Equipment should not be operated above the fabric or geogrid until one full lift of crushed stone fill is placed above.

The maximum particle size of granular material placed over geotextile fabric or geogrid should not exceed 1½ inches. Geotextiles can also be considered for severe subgrade conditions during winter months. It should be expected that a minimum of 12 to 18 inches of engineered fill will be required with any geogrid application.

Terracon should be retained during construction to observe earthwork and to perform necessary tests and observations during subgrade preparation; evaluation of exposed subgrade soils;

placement and compaction of engineered fills; and just prior to construction of foundations.

Excavations

We anticipate the fill and native soils will be excavatable using conventional back-hoes, front-end loaders and motorized scrapers.

Temporary excavations will probably be required during grading and site development operations.

The contractor, by his contract, is usually responsible for designing and constructing stable, temporary excavations and should shore, slope or bench the sides of the excavations as required to maintain stability of the excavation sides and bottom. All excavations should comply with applicable local, state and federal safety regulations, including the current Occupational Safety and Health

Administration (OSHA) Excavation and Trench Safety Standards.

As a minimum, excavations should be performed in accordance with OSHA 29 CFR, Part 1926, Subpart P, “Excavations” and its appendices, and in accordance with any applicable local, and/or state regulations.

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Construction site safety is the sole responsibility of the contractor who controls the means, methods, and sequencing of construction operations. Under no circumstances shall the information provided herein be interpreted to mean Terracon is assuming any responsibility for construction site safety, or the contractor's activities; such responsibility shall neither be implied nor inferred.

Construction Observation and Testing

The earthwork efforts should be monitored under the direction of the Geotechnical Engineer. This monitoring should include documentation of adequate removal of vegetation and top soil, proof-rolling and mitigation of areas delineated by the proof-roll to require mitigation.

Each lift of compacted fill should be tested, evaluated, and reworked as necessary until approved by the Geotechnical Engineer prior to placement of additional lifts. Each lift of fill should be tested for density and water content at an appropriate frequency.

In areas of foundation excavations, the bearing subgrade should be evaluated under the direction of the Geotechnical Engineer. In the event unanticipated conditions are encountered, the

Geotechnical Engineer should prescribe mitigation options.

In addition to the documentation of the essential parameters necessary for construction, the continuation of the Geotechnical Engineer into the construction phase of the project provides the continuity to maintain the Geotechnical Engineer’s evaluation of subsurface conditions, including assessing variations and associated design changes.

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SHALLOW FOUNDATIONS

By preparing the site as recommended in the Site Preparation section, we expect that the shallow foundation bearing materials will consist of native lean clay soils or new engineered fill. Shallow foundation design recommendations for the proposed columbarium and maintenance building are presented in the following subsections.

Design Parameters – Compressive Loads

Maximum net allowable bearing pressure 1, 2 2,000 psf

Required bearing stratum 3

Tested and approved, native lean clay soils or new, engineered fill. Bearing stratum to be verified by

Terracon

Minimum foundation dimensions Columns: 30 inches

Continuous: 18 inches

Minimum embedment below existing grade 4 24 inches

Estimated total settlement from structural loads 2, 5

Approximately 1 inch

Estimated differential settlement 2, 6 About ⅔ of total settlement

Ultimate coefficient of sliding friction 7 0.35 (ultimate)

1. The maximum net allowable bearing pressure is the pressure in excess of the minimum surrounding overburden pressure at the footing base elevation. An appropriate factor of safety has been applied.

2. Values provided are for maximum loads noted in Project Description.

3. Unsuitable or soft soils should be over-excavated and replaced according to the recommendations presented in Earthwork.

4. For confinement and to reduce the effects of seasonal moisture variation

5. Actual foundation settlement will depend upon the variations within the subsurface soil profile, the structural loading conditions, the embedment depth of the footing, the thickness of compacted fill and the quality of earthwork operations

6. Differential settlements are as measured over a span of 50 feet

7. No factor of safety has been applied to the coefficient of sliding friction

Uplift forces can be resisted by the dead weight of the shallow foundation and the effective weight of any soil above the shallow foundation. A total unit weight of soil not exceeding 115 pcf is appropriate for the on-site soils backfilled above the foundation, assuming it is compacted to at least 95 percent of the material’s standard Proctor maximum dry density. A total unit weight of

150 pcf could be assumed for shallow foundation concrete. The ground surface should be sloped away from the foundation to avoid ponding of water and saturation of the backfill materials.

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Foundation Construction Considerations

As noted in Earthwork, the footing excavations should be evaluated under the direction of the

Geotechnical Engineer. The base of all foundation excavations should be free of water and loose soil, prior to placing concrete. Concrete should be placed soon after excavating to reduce bearing soil disturbance. Care should be taken to prevent wetting or drying of the bearing materials during construction. Excessively wet or dry material or any loose/disturbed material in the bottom of the footing excavations should be removed/reconditioned before foundation concrete is placed.

If unsuitable bearing soils are encountered at the base of the planned footing excavation, the excavation should be extended deeper to suitable soils, and the footings could bear directly on these soils at the lower level or on lean concrete backfill placed in the excavations. This is illustrated on the sketch below.

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SEISMIC CONSIDERATIONS

The seismic design requirements for buildings and other structures are based on Seismic Design

Category. Site Classification is required to determine the Seismic Design Category for a structure. The Site Classification is based on the upper 100 feet of the site profile defined by a weighted average value of either shear wave velocity, standard penetration resistance, or undrained shear strength in accordance with Section 20.4 of ASCE 7-10.

Based on the results of our site characterization program, we conclude that Site Class C is appropriate for the subject site. The scope of services did not include site profile determination to a depth of 100 feet. Exploration for this project extended to a maximum depth of 14.4 feet and the site classification assumes that materials encountered at the bottom of the deepest exploration continue to a depth of 100 feet.

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FLOOR SLABS

Grade-supported floor slabs should be supported on a minimum of 24 inches of LVC material.

LVC fill should be placed and compacted as recommended in section Earthwork. Depending on site grading plans, this may require overexcavation of existing soils and replacement with soils meeting the LVC criteria outlined in this report within the proposed maintenance building.

Image not to scale

Floor Slab Design Parameters

Floor slab support 1, 2 A minimum 24-inch thick low volume change (LVC) layer over suitable native soil or engineered fill

Modulus of subgrade reaction 150 pounds per square inch per inch (psi/in) for point loading conditions

Granular course beneath slab 3, 4, 5 Minimum 4 inches

Capillary break layer thickness 4, 5 Minimum 4 inches

1. We recommend an LVC layer be present below the floor slab. This layer should be at least 24 inches thick and should meet the LVC material criteria outlined in this report in section Earthwork. Where existing soils meet the LVC criteria, they should be moisture conditioned and recompacted as recommended in this report.

2. We recommend subgrades be maintained in a relatively moist condition until the floor slab is constructed. If the subgrade should become excessively wet or dry prior to construction of the floor slab, the affected material should be removed or the materials be scarified, moisture conditioned, and recompacted. Upon completion of

LVC Material (LL<45 & PI<20)

Drainage Layer

Concrete Slab-on-Grade

4 inches

Minimum

20 inches

Minimum

24 inches

Minimum

Responsive ■ Resourceful ■ Reliable 17 grading operations in the building area, care should be taken to maintain the recommended subgrade moisture content and density prior to construction of the building floor slab.

3. If the purpose of this layer is solely to create a level base for concrete placement to maintain a more uniform slab thickness, well-graded sand, gravel or crushed stone can be used.

4. If penetration of moisture vapor through the slab is a concern, in our opinion the floor slab design should include a capillary break layer in addition to a vapor retarder (refer to ACI 302 and/or ACI 360 for procedures and cautions regarding the use and placement of vapor retarders). In our opinion, capillary break layers should be comprised of granular materials that have less than 5 percent fines (material passing the #200 sieve). Other design considerations such as cold temperatures and condensation development could warrant additional design considerations.

5. These granular materials may be considered part of the LVC zone.

Where appropriate, saw-cut control joints should be placed in the slab to help control the location and extent of cracking. For additional recommendations refer to the ACI Design Manual. Joints or cracks that develop in floor slabs should be sealed with a water-proof, non-extruding compressible compound specifically recommended for concrete and wet environments.

The use of a vapor retarder should be considered beneath concrete slabs-on-grade that will be covered with wood, tile, carpet or other moisture sensitive or impervious coverings, or when the slab will support equipment or materials sensitive to moisture. When conditions warrant the use of a vapor retarder, the slab designer should refer to ACI 302 and/or ACI 360 for procedures and cautions regarding the use and placement of a vapor retarder.

Floor Slab Construction Considerations

On most project sites, the site grading is generally accomplished early in the construction phase.

However, as construction proceeds, the subgrade may be disturbed due to utility excavations, construction traffic, desiccation, rainfall, etc. As a result, the floor slab subgrade may not be suitable for placement of aggregate base capillary break material and concrete, and corrective action will be required.

Terracon should review the condition of the floor slab subgrade immediately prior to placement of the granular leveling course/capillary break material and construction of the slab. Particular attention should be paid to high traffic areas that were rutted and disturbed earlier and to areas containing backfilled trenches. Areas where unsuitable conditions are located should be repaired by removing and replacing the affected material with properly compacted engineered fill.

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LATERAL EARTH PRESSURES

Reinforced concrete walls with unbalanced backfill levels on opposite sides should be designed for earth pressures at least equal to those indicated in the following table. Earth pressures will be influenced by structural design of the walls, conditions of wall restraint, methods of construction and/or compaction and the strength of the materials being restrained. Two wall restraint conditions are shown. Active earth pressure is commonly used for design of free-standing cantilever retaining walls and assumes wall movement. The "at-rest" condition assumes no wall movement such as the proposed loading dock wall. The recommended design lateral earth pressures do not include a factor of safety and do not provide for possible hydrostatic pressure on the walls or for pressures from swell of the medium to high plasticity fat clays that may be present behind walls.

Earth Pressure Coefficients

Earth Pressure

Conditions

Coefficient for

Backfill Type

Equivalent Fluid

Density (pcf)

Surcharge

Pressure, p1 (psf)

Earth Pressure, p2 (psf)

Active (Ka)

Granular - 0.33

Lean Clay Fill -

0.42

(0.33)S

(0.42)S

(40)H

(50)H

At-rest (Ko)

Granular - 0.50

Lean Clay Fill -

0.58

(0.50)S

(0.58)S

(55)H

(70)H

Passive (Kp)

Granular - 3.0

Lean Clay Fill -

2.4

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Applicable conditions to the above include:

For active earth pressure, wall must rotate about base, with top lateral movements of about

0.002 H to 0.004 H, where H is wall height

For passive earth pressure to develop, wall must move horizontally to mobilize resistance

Uniform surcharge, where S is surcharge pressure

In-situ soil backfill weight a maximum of 120 pcf

Horizontal backfill, compacted between 95 and 98 percent of standard Proctor maximum dry density

Loading from heavy compaction equipment not included

No hydrostatic pressures acting on wall

No dynamic loading

No safety factor included in soil parameters

Ignore passive pressure in frost zone

Backfill placed against structures should consist of granular soils or low plasticity cohesive soils. For the granular values to be valid, the granular backfill must extend out from the base of the wall at an angle of at least 45 degrees from vertical for the active and at-rest cases, and 60 degrees for the passive case. To calculate the resistance to sliding, a value of 0.3 should be used as the ultimate coefficient of friction between the footing and the underlying soil.

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To control hydrostatic pressure behind the wall we recommend that a drain be installed at the below-grade wall with a collection pipe leading to a reliable discharge.

Granular backfill in this case consists of ASTM D 448 No. 57 or 67 stone or equivalent

Perforated pipe should be rigid PVC, sized to transport the expected water

Exterior ground surface should consist of a 24-inch clay cap sloped to drain from the wall

The clay cap can be replaced by a pavement section

Weep holes can be considered in lieu of the perforated drain pipe for retaining walls, if the water seepage will not impact the retaining wall or adjacent structures

If drainage is not possible, then combined hydrostatic and lateral earth pressures should be calculated for lean clay backfill using an equivalent fluid weighing 90 and 100 pcf for active and at-rest conditions, respectively. For granular backfill, an equivalent fluid weighing 75 and 85 pcf should be used for active and at-rest conditions, respectively. These pressures do not include the influence of surcharge, equipment or floor loading, which should be added. Heavy equipment should not operate within a distance closer than the exposed height of retaining walls to prevent lateral pressures exceeding those provided.

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PAVEMENTS

General Pavement Comments

Based on the understood grading scheme, the subsurface conditions observed at the boring locations and preparing the subgrade as recommended in Site Preparation, the pavement subgrade materials should consist of at least 1 foot of tested and approved, new engineered fill.

Within two days before placing aggregate base or concrete, we recommend the moisture content and density of the top 8 inches of the subgrade be evaluated and then the subgrade should be proof-rolled. Areas not in compliance with the required ranges of moisture or density should be moisture conditioned and compacted. Particular attention should be paid to high traffic areas that were rutted and disturbed earlier and to areas where backfilled trenches are located. Areas where unsuitable conditions are located should be repaired by removing and replacing the materials with properly compacted engineered fill.

Support characteristics of subgrade for pavement design do not account for shrink/swell movements of an expansive clay subgrade, such as soils encountered on this project. Thus, the pavement may be adequate from a structural standpoint, yet still experience cracking and deformation due to shrink/swell related movement of the subgrade.

Pavement Design Parameters

Recommended pavement sections for parking areas and drives are included in the following table.

The alternative minimum pavement sections are based on the completed subgrade having a CBR value of at least 3 percent and a modulus of subgrade reaction (k) of at least 100 psi/in. Imported fill materials should have the ability to achieve a minimum CBR value of 3 percent and meet the other requirements for engineered fill recommended in Site Preparation. In no case should soils classifying as ML, CL-ML, or SM according to the Unified Soil Classification System be used as engineered fill in pavement areas.

The light-duty pavement sections assume that light-duty parking areas will be traveled by only automobiles totaling less than 100 cars per day. The heavy-duty pavement sections assume 10 semi-tractor trailer units and other heavy vehicles per day using the entrance drives. If the anticipated traffic exceeds our assumptions, please contact Terracon so that the recommended pavement sections can be re-evaluated and modified if necessary.

Long-term pavement performance will be dependent upon several factors, including maintaining subgrade moisture levels and providing preventive maintenance. The civil engineer should consider the following recommendations in the design and layout of pavements:

Site grading at a minimum 2 percent grade away from the pavements

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The subgrade and the pavement surface have a minimum 1/4 inch per foot slope to promote effective surface drainage

Joint sealant should be applied to cracks

Effective perimeter drainage should be constructed

All landscaped areas in or adjacent to pavements should be sealed to reduce or prevent moisture migration to subgrade soils

Low permeability backfill should be compacted against the exterior side of curb and gutter

Curb, gutter and/or sidewalk should be placed directly on engineered fill subgrade materials rather than on unbound granular base course materials

Pavement Section Thicknesses

The following table provides options for Asphaltic Concrete and for Portland Cement Sections:

Traffic Area Pavement

Section 1

Minimum Recommended Pavement Section Thickness (in.)

Asphalt

Surface

Course 2

Asphalt

Binder

Course 2

Portland

Cement

Concrete2

(4,000 psi)

Aggregate

Base 2

Total

Thickness

Light-duty I 3 --- --- 8 11

II --- --- 5 4 9

Heavy-duty I 1.5 2.5 8 12

II --- --- 6 4 10

Dumpster

Pad

II --- --- 7 4 11

1 Pavement Section I = Asphaltic Concrete over Aggregate Base

Pavement Section II = 4,000 psi, Air Entrained Portland Cement Concrete (PCC)

2 Arkansas State Highway and Transportation Department Standard Specifications for Highway

Construction

These pavement sections are considered minimal sections based upon the expected traffic and the existing subgrade conditions. Their satisfactory performance will require that timely maintenance be performed and effective drainage be developed and maintained.

Asphaltic concrete should conform to the requirements for asphaltic concrete hot mix binder course

(25 mm) and surface course (9.5 mm) in Sections 406 and 407, respectively, of the AHTD Standard

Specifications for Highway Construction, 2014 Edition. The aggregate base course should consist of crushed stone that conforms to the requirements for Class 7 aggregate base in Section 303 of the 2014 AHTD specifications. Concrete should conform to the requirements for Portland Cement

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Concrete Pavement in Section 501 of the AHTD Standard Specifications for Highway

Construction.

We recommend all portland cement concrete pavement details for joint spacing, joint reinforcement, and joint sealing be prepared in accordance with American Concrete Institute (ACI

330R and ACI 325.9R, current editions). Portland cement concrete pavements subjected to heavy trucks should be provided with mechanically reinforced joints (doweled or keyed) in accordance with ACI 330R, current edition.

Pavement Drainage

Pavements should be sloped to provide rapid drainage of surface water. Water allowed to pond on or adjacent to the pavements could saturate the subgrade and contribute to premature pavement deterioration. In addition, the pavement subgrade should be graded to provide positive drainage within the granular base section.

Pavement Maintenance

The pavement sections represent minimum recommended thicknesses and, as such, periodic maintenance should be anticipated. Therefore preventive maintenance should be planned and provided for through an on-going pavement management program. Maintenance activities are intended to slow the rate of pavement deterioration and to preserve the pavement investment.

Maintenance consists of both localized maintenance (e.g. crack and joint sealing and patching) and global maintenance (e.g. surface sealing). Preventive maintenance is usually the first priority when implementing a pavement maintenance program. Additional engineering observation is recommended to determine the type and extent of a cost-effective program. Even with periodic maintenance, some movements and related cracking may still occur and repairs may be required.

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GENERAL COMMENTS

Our analysis and opinions are based upon our understanding of the project, the geotechnical conditions in the area, and the data obtained from our site exploration. Natural variations will occur between exploration point locations or due to the modifying effects of construction or weather.

The nature and extent of such variations may not become evident until during or after construction.

Terracon should be retained as the Geotechnical Engineer, where noted in the final report, to provide observation and testing services during pertinent construction phases. If variations appear, we can provide further evaluation and supplemental recommendations. If variations are noted in the absence of our observation and testing services on-site, we should be immediately notified so that we can provide evaluation and supplemental recommendations.

Our scope of services does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken.

Our services and any correspondence or collaboration through this system are intended for the sole benefit and exclusive use of our client for specific application to the project discussed and are accomplished in accordance with generally accepted geotechnical engineering practices with no third party beneficiaries intended. Any third party access to services or correspondence is solely for information purposes to support the services provided by Terracon to our client. Reliance upon the services and any work product is limited to our client, and is not intended for third parties.

Any use or reliance of the provided information by third parties is done solely at their own risk. No warranties, either express or implied, are intended or made.

Site characteristics as provided are for design purposes and not to estimate excavation cost. Any use of our report in that regard is done at the sole risk of the excavating cost estimator as there may be variations on the site that are not apparent in the data that could significantly impact excavation cost. Any parties charged with estimating excavation costs should seek their own site characterization for specific purposes to obtain the specific level of detail necessary for costing.

Site safety, and cost estimating including, excavation support, and dewatering requirements/design are the responsibility of others. If changes in the nature, design, or location of the project are planned, our conclusions and recommendations shall not be considered valid unless we review the changes and either verify or modify our conclusions in writing.

FIGURES

FIGURES

This is not a cross section. This is intended to display the Geotechnical Model only. See individual logs for more detailed conditions.

D E

P T

H B

E L

O W

G R

A D

E

F ee

t) 10/26/2018 Terracon Project No. 35185052 Fayetteville National Cemetery Expansion Fayetteville, Arkansas

First Water Observation

Second Water Observation

Final Water Observation

Aggregate layer

Containing varying amounts of sand, brown, grayish brown and gray, medium stiff to hard

Brownish gray to gray, soft rock

LEGEND

Fat Clay

Lean Clay

Highly Weathered Shale

Sandy Fat Clay

Fill

Sandy Lean Clay

Fat Clay with Sand

Lean Clay with Sand

Layering shown on this figure has been developed by the geotechnical engineer for purposes of modeling the subsurface conditions as required for the subsequent geotechnical engineering for this project.

Numbers adjacent to soil column indicate depth below ground surface.

NOTES:

GEOMODEL

Groundwater levels are temporal. The levels shown are representative of the date and time of our exploration. Significant changes are possible over time.

Water levels shown are as measured during and/or after drilling. In some cases, boring advancement methods mask the presence/absence of groundwater. See individual logs for details.

Model Layer General DescriptionLayer Name

Fill

Lean clay and fat…