B01 Attachment J01 Volume 1 - Specifications 6.15.2021.pdf

ECS Mid-Atlantic, LLC Geotechnical Engineering Report Amherst Medical Clinic

3761 South Amherst Highway Madison Heights, Virginia 24572

ECS Project No. 12:19292

June 10, 2021

June 10, 2021

Mr. David Verdis, EIT Kimley-Horn and Associates, Inc.

1700 Willow Lawn Drive Suite 200 Richmond, Virginia 23230

ECS Project No. 12:19292

Reference: Geotechnical Engineering Report Amherst Medical Clinic 3761 South Amherst Highway Madison Heights, Virginia 24572

Dear Mr. Verdis:

ECS Mid-Atlantic, LLC (ECS) has completed the subsurface exploration, laboratory testing, and geotechnical engineering analyses for the above-referenced project. Our services were performed in general accordance with our agreed to scope of work. This report presents our understanding of the geotechnical aspects of the project along with the results of the field exploration and laboratory testing conducted, and our design and construction recommendations.

It has been our pleasure to be of service to Kimley-Horn during the design phase of this project. We would appreciate the opportunity to remain involved during the continuation of the design phase, and we would like to provide our services during construction phase operations as well to verify subsurface conditions assumed for this report. Should you have any questions concerning the information contained in this report, or if we can be of further assistance to you, please contact us.

Respectfully submitted, ECS Mid-Atlantic, LLC

Hunter B. Ingram III, EIT Project Engineer hingram@ecslimited.com

Brandon M. Quinn, PE Senior Project Engineer bquinn@ecslimited.com

Brian Wyatt, PE Principal Engineer bwyatt@ecslimited.com

Brian S Wyatt Digitally signed by Brian S Wyatt Date: 2021.06.10 12:00:13 -04'00'

Amherst Medical Center June 10, 2021 ECS Project No. 12:19292 Page i

TABLE OF CONTENTS

EXECUTIVE SUMMARY

1.0 INTRODUCTION

2.0 PROJECT INFORMATION

2.1 Project Location/Current Site Use/Past Site Use

2.2 Proposed Construction

3.0 FIELD EXPLORATION AND LABORATORY TESTING

3.1 Site Geology

3.2 Subsurface Characterization

3.3 Groundwater Observations

3.4 Laboratory Testing

4.0 DESIGN RECOMMENDATIONS

4.1 Foundations

4.2 Slabs on Grade

4.3 Seismic Design Considerations

4.4 Pavements

5.0 SITE CONSTRUCTION RECOMMENDATIONS

5.1 Subgrade Preparation

5.1.1 Stripping and Grubbing

5.1.2 Proofrolling

5.2 Earthwork Operations

5.2.1 Existing Man-Placed Fill

5.2.2 High Plasticity Soils

5.2.3 Structural Fill

5.3 Foundation and Slab Observations

5.4 Utility Installations

6.0 CLOSING

APPENDICES

Appendix A – Drawings & Reports

Site Location Diagram Boring Location Diagram Subsurface Cross-Section

Appendix B – Field Operations

Reference Notes for Boring Logs Subsurface Exploration Procedure: Standard Penetration Testing (SPT) Boring Logs B-1 through B-8

Appendix C – Laboratory Testing

Laboratory Test Results Summary Plasticity Chart

Amherst Medical Clinic June 10, 2021 ECS Project No. 12:19292 Page 1

EXECUTIVE SUMMARY

This Executive Summary is intended as a very brief overview of the primary geotechnical conditions that are expected to affect design and construction. Information gleaned from the Executive Summary should not be utilized in lieu of reading the entire geotechnical report.

The soils encountered in our borings consisted of firm to very stiff residual soils of high plasticity as well as soft to very stiff fill soils.

The fill soils will require undercut and replacement with adequate structural fill as defined in this report. An ECS representative should be on site to confirm that unsuitable material has been completely removed. A buried concrete slab was also encountered at the eastern most boundary of the site and should be removed before placement of pavements or structural fills.

The high plasticity soils encountered at the site have the potential for moisture related volume change and should be handled properly during construction. If material from onsite cuts is to be used as structural fill, construction time consideration for moisture conditioning should be made.

Assuming subgrades are prepared as recommended in this report, the proposed building can be supported by conventional shallow foundations consisting of column and/or strip footings bearing on the existing soils or rock. The foundations can be designed for an allowable bearing pressure of 2,000 psf based on anticipated design loads. The building can be designed based on a seismic site classification of D as currently configured.

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1.0 INTRODUCTION

The purpose of this study was to provide geotechnical information for the design of foundations and pavements for the proposed medical office building and parking lots. The project will include a single story, 15,000 to 20,000 square foot building as well as an asphalt parking lot to accommodate approximately 50 vehicles. The recommendations developed for this report are based on project information supplied by Kimley-Horn.

Our services were provided in accordance with our Proposal No. 12:14533, dated February 19, 2021, as authorized by Kimley-Horn on April 30, 2021 via purchase order number ECS000-21-02RIC. Our services have been provided under the Master Agreement for Continuing Professional Services dated February 3, 2015.

This report contains the procedures and results of our subsurface exploration and laboratory testing programs, review of existing site conditions, engineering analyses, and recommendations for the design and construction of the project.

The report includes the following items:

Observations from our site reconnaissance including current site conditions, surface drainage features, and unusual site features

A review of published soil survey and geologic information relevant to the planned development

A description of the field exploration and laboratory tests performed and discussion of subsurface conditions

Final logs of the soil borings and records of the field exploration prepared in accordance with the standard practice for geotechnical engineering. A boring location plan is included, and the laboratory test results are plotted on the boring logs and included on a laboratory test summary.

Descriptions of subsurface conditions including topsoil, pavement, FILL or debris, rock, and groundwater depths and strata depths

Recommended allowable soil bearing pressure(s) and design parameters for buildings foundations and estimates of predicted foundation settlement. Recommendations for subgrade improvement, if indicated

Recommendations for seismic site classification in accordance with the International Building Code, Section 1613 based on the soil borings and our experience in this geologic setting

Recommendations for a subgrade modulus for slab design and for underslab drainage and moisture protection. Evaluation of the potential for groundwater to affect below grade slabs.

Recommendations for minimum asphalt pavement sections for the new drive lanes and parking areas based on soil types encountered and traffic data provided by the Civil Engineer. This does not include pavements in the public right-of-way.

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Recommendations for development of earthwork specifications. Evaluation of the on-site soil characteristics encountered in the soil borings. Discussion of the suitability of the on-site materials for reuse as Engineered Fill to support foundations, slabs, and pavements. Recommendations for compaction requirements and suitable on and off-site borrow materials.

Evaluation of ground water and rock conditions and their impacts on the proposed construction

2.0 PROJECT INFORMATION

2.1 PROJECT LOCATION/CURRENT SITE USE/PAST SITE USE

The site is located at 3761 South Amherst Highway in Madison Heights, Virginia. At the time of our visit, much of the ground surface was paved with manicured grass in the unpaved areas. There are two existing buildings at the northwest and southeastern corners of the site. The site is bounded to the north by Dixie Airport Road; to the west by South Amherst Highway; to the east by residential property; and to the south by commercial properties. Figure 2.1.1 shows the location of the site where the proposed additions/pavements are to be constructed. The full site location diagram can be found in Appendix A of this report. Existing private utilities were observed in the vicinity of the eastern most building and required slight alteration to our proposed boring location B-2

Figure 2.1.1. Site Location

Site grades are relatively flat across the area of proposed development, sloping towards the northeast corner of the site. The ground surface rise from approximately El. +916 to El. +925 feet based on published topographic maps (Google Earth).

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Based upon available historical aerial imagery, the site appears to have been developed in its current state sometime between 1962 and 1968. Prior to the current configuration, the site was used commercially.

2.2 PROPOSED CONSTRUCTION

The following information explains our understanding of the planned development including proposed buildings and related infrastructure.

SUBJECT DESIGN INFORMATION / ASSUMPTIONS

Building Footprint Approximately 15,000 to 20,000 square feet in plan-view # of Stories One-story above grade Usage Medical Facility Framing Wood and metal frame with a slab on grade floor Column Loads* 75 kips (assumed) Wall Loads 3 kips/ft (assumed) Lowest Finish Floor Elevation

± 2 foot of existing grades (assumed)

*Assumed load are based on reasonable material and product loads. If final design loads exceed our assumed loads, this report needs to be revised to update our foundation recommendations, bearing capacity, and settlement calculations.

3.0 FIELD EXPLORATION AND LABORATORY TESTING

Our exploration procedures are explained in greater detail in Appendix B including the insert titled Subsurface Exploration Procedures. Our scope of work included drilling 8 borings. Our borings were located with a handheld GPS unit while referencing Google Earth aerial imaging. Their approximate locations are shown on the Boring Location Diagram in Appendix A.

3.1 SITE GEOLOGY

Based on the Digital Representation of the 1993 Geologic Map of Virginia, the project site is located within the Piedmont Geologic Province in Central/Southwest Virginia. The site itself is located at the border between the Proterozoic Z-Cambrian aged Alligator Back Formation, which consists primarily of meta-argillite and schist and a similar aged formation of primarily ultramafic rock and schist.

Particularly where non-carbonate materials are present, the boundary between soil and rock is not sharply defined. A transitional zone termed "highly weathered rock" (HWR hereafter) is normally found overlying the parent bedrock. HWR is defined, for engineering purposes, as residual material with Standard Penetration resistance greater than 100 blows per foot (bpf). Because weathering is facilitated by fractures, joints, and the presence of less resistant rock types, the profile of the HWR and hard rock is typically irregular and erratic, similar to that described for the rock types themselves. Also, it is not unusual to find lenses and naturally floating boulders of hard rock in zones of HWR within the soil mantle, well above the general bedrock level.

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3.2 SUBSURFACE CHARACTERIZATION

The subsurface conditions encountered were generally consistent with published geological mapping. The following sections provide generalized characterizations of the soil and rock strata. Please note that the ground surface elevations were not surveyed by a licensed surveyor; these elevations are approximate based on Google-Earth©; therefore, elevation ranges are approximate +/- several feet. Please refer to the boring logs in Appendix B.

Approximate Depth (ft) Stratum Description

Ranges of SPT(1) N-values

(bpf)

0-0.7 (Surface cover) n/a

Topsoil [4 inches] (B-1/B-2/B-3/B-5/B-8) Asphalt [2 to 3 inches]; Gravel [2 to 5 inches] (B-4/B-6/ B-7)

N/A

0.7-7.5 I FILL, Soft to hard, SILT and SILT with SAND (ML), contains rock fragments, moist 4 to 48

0.7-20+ II

Residuum, Firm to Very Stiff, ELASTIC SILT (MH) and LEAN CLAY with varying concentrations of sand (CL), contains mica, moist; Occasional Loose to Medium Dense, SILTY SAND (SM)

5 to 23

18.0-20+ III Highly Weathered Rock Sampled as Very Dense, SILTY SAND (SM), moist 50+

Notes:

(1) Standard Penetration Testing

A graphical presentation of the subsurface conditions is shown on the Subsurface Cross Section Diagram included in Appendix A.

3.3 GROUNDWATER OBSERVATIONS

Groundwater seepage into our borings was not observed during our exploration at the depths explored.

We observed borehole caving at depths ranging from 3.1 to 10.4 feet which may be an indicator of groundwater presence, but does not appear to be in this case.

3.4 LABORATORY TESTING

The laboratory testing consisted of selected tests performed on samples obtained during our field exploration operations. Classification and index property tests were performed on representative soil samples. The laboratory testing program included natural moisture content tests (ASTM D2216), percent passing the No. 200 sieve tests (ASTM D1140), and Atterberg Limits tests (ASTM D4318). The results of all laboratory testing conducted are included in the Appendix of this report.

Each sample was visually classified on the basis of texture and plasticity in accordance with ASTM D2488 Standard Practice for Description and Identification of Soils (Visual-Manual Procedures) including USCS classification symbols, and ASTM D2487 Standard Practice for Classification for Engineering Purposes (Unified Soil Classification System (USCS)). After classification, the samples were grouped in the major zones noted on the boring logs in Appendix B. The group symbols for each soil type are indicated in

ECS Project No. 12:19292 Page 6 parentheses along with the soil descriptions. The stratification lines between strata on the logs are approximate; in situ, the transitions may be gradual.

4.0 DESIGN RECOMMENDATIONS

4.1 FOUNDATIONS

The soils encountered during our exploration were primarily of residual soils consisting of firm to very stiff ELASTIC SILT (MH) and LEAN CLAY (CL). The consistency of the natural soils on-site appears suitable for construction of the proposed medical facility, however high plasticity soils such as the ELASTIC SILT observed on site have the propensity for moisture related volume change. We do not anticipate that removal of these soils would be a practical alternative for this facility, therefore we have provided bearing recommendations below to lessen the risk of foundation damage due to the shrink-swell potential of the existing site soils.

Soft undocumented fill soils were encountered in Boring B-4 near the existing building on the eastern side of the site to an approximate depth of 2.5 feet below the ground surface. These soils are not suitable for support the proposed development and will require a full undercut to an adequate bearing stratum in residual soils. Based on the soft fill soils encountered in Boring B-4, additional soft and possibly deeper fill soils could be encountered within the footprint of the eastern most building. If additional fill soils are encountered within the building footprint, they should be removed and replaced with adequate structural fill to desired grades.

Undocumented fill soils were also encountered near the existing barber shop to the west in Boring B-5 to a depth of approximately 7.5 feet below the ground surface. While undocumented, they appear to have been placed with some degree of compactive effort, although blow counts were likely elevated by fragments of rock or obstructions in the fill. Based upon the proposed building and parking lot layout, we anticipate that these soils will be removed during grading operations, however a final grading plan was not provided. If these soils are left in place, they should be proofrolled prior to grading or construction operations to determine of undercuts are required. An ECS representative should be on site during construction to observe proofrolls and foundation excavations to confirm an adequate bearing stratum and that unsuitable material has been completely removed.

Additionally, a buried concrete slab was encountered below the topsoil at the original location of boring B-3. The lateral extent of the buried slab is not known at this time. All existing structures and utilities should be removed prior to placement of structural fill or building construction.

Provided subgrades and Structural Fills are prepared as recommended in this report, the proposed structure can be supported by shallow foundations including column footings and continuous wall footings. We recommend the foundation design use the following parameters:

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Design Parameter Column Footing Wall Footing

Net Allowable Bearing Pressure(1) 2,000 psf 2,000 psf

Acceptable Bearing Soil Material Stiff Residual Soils or Structural Fill

Stiff Residual Soils or Structural Fill

Minimum Width 24 inches 16 inches

Minimum Interior Footing Embedment Depth (below slab or finished grade)

24 inches 24 inches

Minimum Exterior Frost Depth (below final exterior grade)(2)

36 inches 36 inches

Estimated Total Settlement (3) Less than 1- inch Less than 1- inch

Estimated Differential Settlement (4) Less than ¾ inches between columns

Less than ¾ inches

Notes:

(1) Net allowable bearing pressure is the applied pressure in excess of the surrounding overburden soils above the base of the foundation.

(2) For bearing considerations/expansive soil concerns

(3) Based on assumed structural loads. If final loads are different, ECS must be contacted to update foundation recommendations and settlement calculations.

(4) Based on maximum column/wall loads and variability in borings. Differential settlement can be re-evaluated once the foundation plans are more complete.

Potential Undercuts: Most of the soils at the foundation bearing elevation are anticipated to be suitable for support of the proposed structure. However, as previously discussed existing fill was encountered within the proposed building footprint to depth up to 2.5 feet below the ground surface. These existing fill soils and other soft or unsuitable soils observed at the footing bearing elevations, should be undercut and removed. Additional unsuitable fill soils may be encountered in unexplored areas. Any undercut should be backfilled with cementitious flowable fill (f’c ≥ 200 psi at 28 days), crushed angular gravel (VDOT No. 57 Stone), or compacted VDOT No. 21-A Stone up to the original design bottom of footing elevation;

the original footing shall be constructed at the desired footing elevations.

4.2 SLABS ON GRADE

Provided subgrades and structural fills are prepared as discussed herein, the proposed floor slabs can be constructed as Ground Supported Slabs (or Slab-On-Grade). Based on a lowest finished floor elevation of ± 2 feet of existing grades, it appears that the slabs will bear on newly compacted fill or stiff residual soils.

Any existing fill soils encountered should be removed below slab areas. The following graphic depicts our soil-supported slab recommendations:

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Figure 4.2.1

1. Drainage Layer Thickness: 4 inches

2. Drainage Layer Material: GRAVEL (GP, GW), SAND (SP, SW)

Soft or yielding soils may be encountered in some areas. Those soils should be removed and replaced with compacted Structural Fill in accordance with the recommendations included in this report.

Subgrade Modulus: Provided the Structural Fill and Granular Drainage Layer are constructed in accordance with our recommendations, the slab may be designed assuming a modulus of subgrade reaction, k1 of 100 pci (lbs./cu. inch). The modulus of subgrade reaction value is based on a 1 foot by 1 foot plate load test basis.

Porous Slab Base: We recommend the slab-on-grade be underlain by a minimum of 4 inches of clean, angular gravel (crushed stone) having a maximum aggregate size of 1.5 inches. VDOT No. 57 Stone is considered suitable for this purpose. This porous fill layer will facilitate the fine grading of the building pad, provide more uniform bearing conditions, and help prevent the rise of water to the bottom of the slab (capillary action).

Vapor Barrier: Before the placement of concrete, a vapor barrier may be placed on top of the granular drainage layer to provide additional protection against moisture penetration through the floor slab. When a vapor barrier is used, special attention should be given to surface curing of the slab to reduce the potential for uneven drying, curling and/or cracking of the slab. Depending on proposed flooring material types, the structural engineer and/or the architect may choose to eliminate the vapor barrier.

Slab Isolation: Soil-supported slabs should be isolated from the foundations and foundation-supported elements of the structure so that differential movement between the foundations and slab will not induce excessive shear and bending stresses in the floor slab. Where the structural configuration prevents the use of a free-floating slab such as in a drop down footing/monolithic slab configuration, the slab should be designed with suitable reinforcement and load transfer devices to preclude overstressing of the slab.

4.3 SEISMIC DESIGN CONSIDERATIONS

Seismic Site Classification: The International Building Code (IBC) 2015 requires site classification for seismic design based on the upper 100 feet of a soil profile. At least two methods are utilized in classifying sites, namely the shear wave velocity (vs) method and the Standard Penetration Resistance (N-value) method. The second method (N-Value) was used in classifying this site.

Concrete Slab Vapor Barrier

Granular Capillary Break/Drainage Layer

Compacted Subgrade

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SEISMIC SITE CLASSIFICATION

Site

Class Soil Profile Name Shear Wave Velocity, Vs, (ft./s)

N value (bpf)

A Hard Rock Vs > 5,000 fps N/A B Rock 2,500 < Vs ≤ 5,000 fps N/A C Very dense soil and soft rock 1,200 < Vs ≤ 2,500 fps >50 D Stiff Soil Profile 600 ≤ Vs ≤ 1,200 fps 15 to 50 E Soft Soil Profile Vs < 600 fps <15

Based upon our interpretation of the subsurface conditions, the appropriate Seismic Site Classification is “D” as shown in the preceding table.

Ground Motion Parameters: In addition to the seismic site classification, ECS has determined the design spectral response acceleration parameters following the IBC methodology. The Mapped Responses were estimated from the USGS website https://www.usgs.gov/natural-hazards/earthquake-hazards/design-ground-motions. The design responses for the short (0.2 sec, SDS) and 1-second period (SD1) are noted in bold at the far right end of the following table.

GROUND MOTION PARAMETERS [IBC 2015 Method]

Period (sec)

Mapped Spectral Response

Accelerations (g)

Values of Site Coefficient for Site Class

Maximum Spectral Response Acceleration

Adjusted for Site Class (g)

Design Spectral Response

Acceleration (g)

Reference Figures 1613.3.1

(1) & (2)

Tables 1613.3.3

(1) & (2)

Eqs. 16-37 & 16-38

Eqs. 16-39 & 16-40

0.2 SS 0.177 Fa 1.6 SMS=FaSs 0.284 SDS=2/3

SMS 0.189

1.0 S1 0.070 Fv 2.4 SM1=FvS1 0.168 SD1=2/3

SM1 0.112

The Site Class definition should not be confused with the Seismic Design Category designation which the Structural Engineer typically assesses. If a higher site classification is beneficial to the project, we can provide additional testing methods that may yield more favorable results.

4.4 PAVEMENTS

Subgrade Characteristics: Based on the results of our borings, it appears that the pavement subgrades in cuts will consist mainly of ELASTIC SILT (MH) and LEAN CLAY (CL) material. We anticipate pavement subgrades in fill areas will consist of similar materials from on-site cuts.

California Bearing Ratio (CBR) testing was not performed as part of this study. Therefore, we have assumed a CBR value of 3.5 for preliminary design purposes, based on a two-thirds reduction of the predicted CBR values for each county included in Appendix I of the VDOT Pavement Design Guide for Subdivision and Secondary Roads in Virginia.

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Traffic Loading Information: We were not provided traffic loading information; therefore, we have assumed loadings typical of this type of project. Specifically, for Light-Duty and Heavy-Duty Pavements, we have assumed EAL18 of 7,000 and 100,000, respectively.

Pavement Design Recommendations: Our pavement design was performed in general accordance with the AASHTO Guide for Design of Pavement Structures, considering the VDOT Guidelines for 1993 AASHTO Pavement Design. The preliminary pavement sections below are guidelines that may or may not comply with local jurisdictional minimums.

PROPOSED PAVEMENT SECTIONS

FLEXIBLE PAVEMENT RIGID PAVEMENT

MATERIAL Heavy Duty Light Duty Heavy Duty Light Duty

Portland Cement Concrete (f’c = 4000 psi) - - 6 in 5 in

Asphaltic Concrete Surface Course (SM-9.5) 2 in 2 in - -

Asphaltic Concrete Surface Course (IM-19.0) 2 in - - -

Graded Aggregate Base Course (AASHTO #21A/21B) 7 in 7 in 6 in 5 in

In general, heavy duty sections are areas that will be subjected to trucks, buses, or other similar vehicles including main drive lanes of the development. Light duty sections are appropriate for vehicular traffic and parking areas.

Large, front loading trash dumpsters frequently impose concentrated front wheel loads on pavements during loading. This type of loading typically results in rutting of asphalt pavement and ultimately pavement failures. For preliminary design purposes, we recommend that the pavement in trash pickup areas consist of a 6-inch thick, 4,000 psi, reinforced concrete slab over 6-inches of dense graded aggregate.

Prior to subbase placement and paving, we recommend that CBR testing of the subgrade soils (both natural and fill soils) be performed to determine the soil engineering properties for final pavement design.

5.0 SITE CONSTRUCTION RECOMMENDATIONS

5.1 SUBGRADE PREPARATION

5.1.1 Stripping and Grubbing

All existing buildings should be demolished and the debris removed from the site. Demolition should include removal of all existing foundations, slabs, underground utilities, and associated loose backfill. If a basement is present beneath the existing buildings, ECS should be consulted during construction for specific recommendations for removal and backfilling.

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The subgrade preparation should consist of stripping all vegetation, rootmat, topsoil, existing fill, and any soft or unsuitable materials from the 5-foot expanded building and 2-foot expanded pavement limits, and 5 feet beyond the toe of Structural Fills. Borings performed in “undisturbed” areas of the site contained an observed 4 inches of topsoil. Deeper topsoil or organic laden soils may be present in wet, low-lying, and poorly drained areas. In wooded areas, the root balls may extend as deep as about 2 feet and will require additional localized stripping depth to completely remove the organics. ECS should be retained to verify that topsoil and unsuitable surficial materials have been removed prior to the placement of structural fill or construction of structures.

5.1.2 Proofrolling

Prior to fill placement or other construction on subgrades, the subgrades should be evaluated by an ECS field technician. The exposed subgrade should be thoroughly proofrolled with construction equipment having a minimum axle load of 10 tons (e.g. fully loaded tandem-axle dump truck). Proofrolling should be traversed in two perpendicular directions with overlapping passes of the vehicle under the observation of an ECS technician. This procedure is intended to assist in identifying any localized yielding materials.

Where proofrolling identifies areas that are unstable or “pumping” subgrade those areas should be repaired prior to the placement of any subsequent Structural Fill or other construction materials. Methods of stabilization include undercutting, moisture conditioning, or chemical stabilization. The situation should be discussed with ECS to determine the appropriate procedure. Test pits may be excavated to explore the shallow subsurface materials to help in determining the cause of the observed unstable materials, and to assist in the evaluation of appropriate remedial actions to stabilize the subgrade.

5.2 EARTHWORK OPERATIONS

5.2.1 Existing Man-Placed Fill

Fill Content: Soft to Very Stiff SILT (ML). A buried slab also exists at the eastern most portion of the site

Fill Removal in Building Areas: All existing fill should be removed from below the planned building areas.

If fill soils are to remain in place in pavement areas depending upon final grades, the fill should be proofrolled and observed by an ECS representative to determine if undercuts should be performed.

5.2.2 High Plasticity Soils

High plasticity soils are prevalent at the project site. Ideally, such soils would be excluded from reuse as fill and be undercut and replaced in cut subgrades for slabs, pavements, and footings to avoid the potential for moisture-related volume change or instability when wet; however, we anticipate this would not be practical for the subject site. Therefore, it should be recognized that high plasticity soils are moisture sensitive and may be problematic during construction activities. Care should be taken to provide adequate drainage and maintenance of exposed subgrades. Due to the risk of shrink-swell, or moisture-related volume change, we have provided a footing embedment depth recommendation in Section 4.2 of this report.

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5.2.3 Structural Fill

Prior to placement of Structural Fill, representative bulk samples (about 50 pounds) of on-site and/or off-site borrow should be submitted to ECS for laboratory testing, which will typically include Atterberg limits, natural moisture content, grain-size distribution, and moisture-density relationships (i.e., Proctors) for compaction. Import materials should be tested prior to being hauled to the site to determine if they meet project specifications. Alternatively, Proctor data from other accredited laboratories can be submitted if the test results are within the last 90 days.

Satisfactory Structural Fill Materials: Materials satisfactory for use as Structural Fill should consist of inorganic soils with the following engineering properties and compaction requirements.

STRUCTURAL FILL INDEX PROPERTIES

Subject Property

Building and Pavement Areas (Borrow Soils) LL < 50, PI<25 Building and Pavement Areas (On-site Soils) LL < 60, PI < 30 Max. Particle Size 4 inches Max. organic content 3% by dry weight

STRUCTURAL FILL COMPACTION REQUIREMENTS

Subject Requirement

Compaction Standard Standard Proctor, ASTM D698 Required Compaction 95% of Max. Dry Density

Moisture Content +/-3 % points of the soil’s optimum value

Loose Thickness 8 inches prior to compaction

On-Site Borrow Suitability: Significant natural deposits of soils that meet the requirements of adequate structural fill are not present on the site. If material from on-site cuts is to be used as structural fill, additional time for moisture conditioning will likely be required due to the high plasticity of the soils encountered.

Fill Placement: Fill materials should not be placed on frozen soils, on frost-heaved soils, and/or on excessively wet soils. Borrow fill materials should not contain frozen materials at the time of placement, and all frozen or frost-heaved soils should be removed prior to placement of Structural Fill or other fill soils and aggregates. Excessively wet soils or aggregates should be scarified, aerated, and moisture conditioned.

5.3 FOUNDATION AND SLAB OBSERVATIONS

Protection of Foundation Excavations: Exposure to the environment may weaken the soils at the footing bearing level if the foundation excavations remain open for too long a time. Therefore, foundation concrete should be placed the same day that excavations are made. If the bearing soils are softened by surface water intrusion or exposure, the softened soils must be removed from the foundation excavation

ECS Project No. 12:19292 Page 13 bottom immediately prior to placement of concrete. If the excavation must remain open overnight, or if rainfall becomes imminent while the bearing soils are exposed, a 1 to 3-inch thick “mud mat” of “lean” concrete should be placed on the bearing soils before the placement of reinforcing steel.

Footing Subgrade Observations: Most of the soils at the foundation bearing elevation are anticipated to be suitable for support of the proposed structure. It is important to have ECS observe the foundation subgrade prior to placing foundation concrete, to confirm the bearing soils are what was anticipated.

Slab Subgrade Verification: Prior to placement of a drainage layer, the subgrade should be prepared in accordance with the recommendations found in Section 5.1.2 Proofrolling.

5.4 UTILITY INSTALLATIONS

Utility Subgrades: The soils encountered in our exploration are expected to be generally suitable for support of utility pipes. The pipe subgrades should be observed and probed for stability by ECS. Any loose or unsuitable materials encountered should be removed and replaced with suitable compacted Structural Fill, or pipe stone bedding material.

Utility Backfilling: The granular bedding material (AASHTO #57 stone) should be at least 4 inches thick, but not less than that specified by the civil engineer’s project drawings and specifications. We recommend that the bedding materials be placed up to the springline of the pipe. Fill placed for support of the utilities, as well as backfill over the utilities, should satisfy the requirements for Structural Fill and Fill Placement.

Excavation Safety: All excavations and slopes should be constructed and maintained in accordance with OSHA excavation safety standards. The contractor is solely responsible for designing, constructing, and maintaining stable temporary excavations and slopes. The contractor’s responsible person, as defined in 29 CFR Part 1926, should evaluate the soil exposed in the excavations as part of the contractor’s safety procedures. In no case should slope height, slope inclination, or excavation depth, including utility trench excavation depth, exceed those specified in local, state, and federal safety regulations. ECS is providing this information solely as a service to our client. ECS is not assuming responsibility for construction site safety or the contractor’s activities; such responsibility is not being implied and should not be inferred.

6.0 CLOSING

ECS has prepared this report to guide the geotechnical-related design and construction aspects of the project. We performed these services in accordance with the standard of care expected of professionals in the industry performing similar services on projects of like size and complexity at this time in the region.

No other representation, expressed or implied, and no warranty or guarantee is included or intended in this report.

The description of the proposed project is based on information provided to ECS by our client. If any of this information is inaccurate or changes, either because of our interpretation of the documents provided or site or design changes that may occur later, ECS should be contacted so we can review our recommendations and provide additional or alternate recommendations that reflect the proposed construction.

ECS Project No. 12:19292 Page 14

We recommend that ECS review the project plans and specifications so we can confirm that those plans/specifications are in accordance with the recommendations of this geotechnical report.

Field observations, and quality assurance testing during earthwork and foundation installation are an extension of, and integral to, the geotechnical design. We recommend that ECS be retained to apply our expertise throughout the geotechnical phases of construction, and to provide consultation and recommendation should issues arise.

ECS is not responsible for the conclusions, opinions, or recommendations of others based on the data in this report.

APPENDIX A – Diagrams & Reports

Site Location Diagram Boring Location Diagram Subsurface Cross-Section

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APPENDIX B – Field Operations

Reference Notes for Boring Logs Subsurface Exploration Procedure: Standard Penetration Testing (SPT) Boring Logs B-1 through B-8

REFERENCE NOTES FOR BORING LOGS

MATERIAL1,2

1Classifications and symbols per ASTM D 2488-17 (Visual-Manual Procedure) unless noted otherwise.

2To be consistent with general practice, “POORLY GRADED” has been removed from GP, GP-GM, GP-GC, SP, SP-SM, SP-SC soil types on the boring logs.

3Non-ASTM designations are included in soil descriptions and symbols along with ASTM symbol [Ex: (SM-FILL)].

4Typically estimated via pocket penetrometer or Torvane shear test and expressed in tons per square foot (tsf).

5Standard Penetration Test (SPT) refers to the number of hammer blows (blow count) of a 140 lb. hammer falling 30 inches on a 2 inch OD split spoon sampler required to drive the sampler 12 inches (ASTM D 1586). “N-value” is another term for “blow count” and is expressed in blows per foot (bpf). SPT correlations per 7.4.2 Method B and need to be corrected if using an auto hammer.

6The water levels are those levels actually measured in the borehole at the times indicated by the symbol. The measurements are relatively reliable when augering, without adding fluids, in granular soils. In clay and cohesive silts, the determination of water levels may require several days for the water level to stabilize. In such cases, additional methods of measurement are generally employed.

7Minor deviation from ASTM D 2488-17 Note 14.

8Percentages are estimated to the nearest 5% per ASTM D 2488-17.

Reference Notes for Boring Logs (03-24-2021).doc © 2021 ECS Corporate Services, LLC. All Rights Reserved

COHESIVE SILTS & CLAYS

UNCONFINED

COMPRESSIVE

STRENGTH, QP4

<0.25

0.25 - <0.50

0.50 - <1.00

1.00 - <2.00

2.00 - <4.00

4.00 - 8.00

>8.00

SPT5

(BPF)

CONSISTENCY7

(COHESIVE)

GRAVELS, SANDS & NON-COHESIVE SILTS

SPT5

DENSITY

<5 5 - 10

11 - 30 31 - 50

>50

Very Loose Loose

Medium Dense Dense

Very Dense

WATER LEVELS6

RELATIVE

AMOUNT7

Trace

With

Adjective (ex: “Silty”)

COARSE

GRAINED

(%)8

<5

FINE

GRAINED

(%)8

<5

DRILLING SAMPLING SYMBOLS & ABBREVIATIONS

PARTICLE SIZE IDENTIFICATION

DESIGNATION PARTICLE SIZES

Hollow Stem Auger Power Auger (no sample) Bulk Sample of Cuttings Wash Sample Shelby Tube Sampler Split Spoon Sampler

Rock Quality Designation % Rock Sample Recovery % Rock Core, NX, BX, AX Rock Bit Drilling Pressuremeter TestSS

ST

WS

BS

PA

HSA

RQD

PM

RD

RC

REC

Boulders Cobbles

Gravel:

Sand:

Silt & Clay (“Fines”) Fine Medium

Coarse Fine Coarse

0.074 mm to 0.425 mm (No. 200 to No. 40 sieve) <0.074 mm (smaller than a No. 200 sieve)

0.425 mm to 2.00 mm (No. 40 to No. 10 sieve)

2.00 mm to 4.75 mm (No. 10 to No. 4 sieve)

4.75 mm to 19 mm (No. 4 sieve to ¾ inch) ¾ inch to 3 inches (19 mm to 75 mm) 3 inches to 12 inches (75 mm to 300 mm) 12 inches (300 mm) or larger

>50 31 - 50 16 - 30

9 - 15 5 - 8 3 - 4 <2

Very Hard Hard

Very Stiff

Stiff Firm Soft

Very Soft

ASPHALT

CONCRETE

GRAVEL

TOPSOIL

VOID

BRICK

AGGREGATE BASE COURSE

GW

GP

GM

GC

SW

SP

SM

SC

ML

MH

CL

CH

OL

OH

PT

WELL-GRADED GRAVEL

gravel-sand mixtures, little or no fines

POORLY-GRADED GRAVEL

gravel-sand mixtures, little or no fines

SILTY GRAVEL

gravel-sand-silt mixtures

CLAYEY GRAVEL

gravel-sand-clay mixtures

WELL-GRADED SAND

gravelly sand, little or no fines

POORLY-GRADED SAND

gravelly sand, little or no fines

SILTY SAND

sand-silt mixtures

CLAYEY SAND

sand-clay mixtures

SILT

non-plastic to medium plasticity

ELASTIC SILT

high plasticity

LEAN CLAY

low to medium plasticity

FAT CLAY

high plasticity

ORGANIC SILT or CLAY non-plastic to low plasticity

ORGANIC SILT or CLAY high plasticity

PEAT

highly organic soils

WL (First Encountered)

WL (Completion)

WL (Seasonal High Water)

WL (Stabilized)

FILL POSSIBLE FILL PROBABLE FILL ROCK

FILL AND ROCK

25 - 45

10 - 20

30 - 45

10 - 25

APPENDIX C – Laboratory Testing

Laboratory Test Results Summary Plasticity Chart

LL PL PI %<#40 AASHTO

67 40 27 98.1 A-7-5

81 37 44 99.0 A-7-5

LIQUID AND PLASTIC LIMITS TEST REPORT

TEST RESULTS (ASTM D4318-10 (MULTIPOINT TEST))

Sample Location

Sample Number

Sample Depth (ft) %<#200 USCS Material Description

B-1 S-2 3.5-5 81.2 MH Red-orange ELASTIC SILT WITH

SAND

B-2 S-1 1-2.5 92.2 MH Red-brown ELASTIC SILT

Project: Amherst Medical Clinic Project No.: 12:19292 Client: Kimley-Horn Date Reported: 6/7/2021

Office / Lab Address Office Number / Fax

ECS Mid-Atlantic LLC - Roanoke 7670 Enon Drive

Suite 101 Roanoke, VA 24019

(540)362-2000 (540)362-1202

Tested by Checked by Approved by Date Received

J.Ginter H.Ingram 5/17/2021

0 10 20 30 40 50 60 70 80 90 100 110

LIQUID LIMIT

ML or OLCL-ML MH or OH

P L A S T I C I T Y I

N D E X

Dashed line indicates the approximate upper limit boundary for natural soils

J. Geil