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Geotechnical Engineering Report Ridgeway EMS Station

Fairfield County, South Carolina

February 17, 2015

Terracon Project No. 73155009

Prepared for:

Genesis Consulting Group

Columbia, South Carolina

Prepared by:

Terracon Consultants, Inc.

Columbia, South Carolina

Terracon Consultants, Inc. 521 Clemson Road Columbia, South Carolina 29229

P [803] 741 9000 F [803] 741 9900 terracon.com

February 17, 2015

Genesis Consulting Group

1330 Lady Street, Suite 205

Columbia, South Carolina 29201

Attn: Mr. David Brandes, P.E.

Re: Geotechnical Engineering Report

Ridgeway EMS Station

Fairfield County, South Carolina


Dear Mr. Brandes:

Terracon Consultants, Inc. (Terracon) has completed the geotechnical engineering services

for the above referenced project. This study was performed in general accordance with our

Proposal No. P73150042, dated January 23, 2015 and approved on January 28, 2015.

This report presents the findings of the subsurface exploration and provides geotechnical

recommendations concerning earthwork and the design and construction of foundations,

floor slabs, and pavements for the proposed project.

We appreciate the opportunity to be of service to you on this project. If you have any

questions concerning this report or we may be of further service, please contact us.

Sincerely,

Terracon Consultants, Inc.

Phillip A. Morrison, P.E. Kenneth J. Zur, P.E.

Geotechnical Department Manager Senior Geotechnical Engineer

SC Registration No. 17275 SC Registration No. 25833

Copies: Addressee (1 via email)

File (1)

TABLE OF CONTENTS

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Page EXECUTIVE SUMMARY ............................................................................................ i 1.0 INTRODUCTION ....................................................................................................... 1 2.0 PROJECT DESCRIPTION ........................................................................................ 1

2.1 Project Description ........................................................................................ 1 2.2 Site Location and Description ........................................................................ 2

3.0 SUBSURFACE CONDITIONS ................................................................................... 3 3.1 Geology ........................................................................................................ 3 3.2 Typical Subsurface Profile ............................................................................. 3 3.3 Groundwater Conditions ................................................................................ 4

4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION ................................ 4 4.1 Geotechnical Considerations......................................................................... 4 4.2 Earthwork ...................................................................................................... 5

4.2.1 Site Preparation ................................................................................. 5

4.2.2 Subgrade Preparation ........................................................................ 5

4.2.3 Material Types ................................................................................... 6

4.2.4 Compaction Requirements ................................................................ 7

4.2.5 Excavation ......................................................................................... 7

4.2.6 Additional Considerations .................................................................. 9

4.3 Foundation Systems ..................................................................................... 9 4.3.1 Design Recommendations ................................................................. 9

4.3.2 Construction Recommendations .......................................................10

4.4 Site Seismic Coefficient ................................................................................11 4.5 Floor Slabs ...................................................................................................11

4.5.1 Design Recommendations ................................................................11

4.5.2 Construction Considerations .............................................................12

4.6 Pavements ...................................................................................................12 4.6.1 Design Recommendations ................................................................12

4.6.2 General Design Recommendations ..................................................13

4.6.3 Construction Considerations .............................................................14

5.0 GENERAL COMMENTS ......................................................................................... 15

APPENDIX A – FIELD EXPLORATION

Exhibit A-1 – Site Location Plan

Exhibit A-2 – Boring Location Plan

Exhibit A-3 – Field Testing Description

Exhibit A-4 to A-6 – Boring Logs

APPENDIX B – LABORATORY TESTING

Exhibit B-1 – Laboratory Testing Description

Exhibit B-2 – Summary of Laboratory Data

Exhibits B-3 to B-4 Laboratory Data Sheets

APPENDIX C – SUPPORTING DOCUMENTS

Exhibit C-1 – General Notes

Exhibit C-2 – Unified Soil Classification System

Geotechnical Engineering Report Ridgeway EMS Station ■ Fairfield County, SC February 17, 2015 ■ Terracon Project No. 73155009

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EXECUTIVE SUMMARY

A geotechnical investigation has been performed for a proposed Ridgeway EMS Station to

be constructed along Old SC Highway 21 just north of Ridgeway, South Carolina. Two

borings were performed to power auger refusal at depths of 21.2 and 23.4 feet below the

existing ground surface. Based on the information obtained from our subsurface exploration,

the site can be developed for the proposed project. The following geotechnical

considerations were identified:

Below about 3 to 5-½ feet of loose clayey sand, the soil profile includes interlayered

zones of dense to very dense silty sand and partially weathered rock. Power auger

refusal (the presumed top of rock) was encountered in each boring. Depths ranged

from 21.2 and 23.4 feet below the existing ground surface. Groundwater was not

encountered in the borings to the auger refusal depths.

Excavation will penetrate a substantial thickness of high consistency soil and partially

weathered rock. There is a potential that bedrock could be encountered between or

beyond the boring locations. Further, boulders or rock pinnacles could be

encountered within the soil mass. The possibility of encountering such materials

should be considered in the project schedule and budget.

The building can be supported by shallow spread footings bearing on firm residual

soils or compacted structural fill.

Based on the 2012 International Building Code, the seismic site classification for this

site is C.

Close monitoring of the construction operations discussed herein will be critical in

achieving the design subgrade support. We therefore recommend that the Terracon

be retained to monitor this portion of the work.

This summary should be used in conjunction with the entire report for design purposes. It

should be recognized that details were not included or fully developed in this section, and

the report must be read in its entirety for a comprehensive understanding of the items

contained herein. The section titled GENERAL COMMENTS should be read for an

understanding of the report limitations.

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GEOTECHNICAL ENGINEERING REPORT

RIDGEWAY EMS STATION

FAIRFIELD COUNTY, SOUTH CAROLINA


February 17, 2015

1.0 INTRODUCTION

This report presents the results of our geotechnical engineering services performed for the

proposed Ridgeway EMS Station to be constructed along Old SC Highway 21 in Fairfield

County, South Carolina. The purpose of these services is to provide information and

geotechnical engineering recommendations relative to:

subsurface soil conditions groundwater conditions

earthwork foundation design and construction

seismic site class floor slab design and construction

pavement design and construction

Our geotechnical engineering scope of work for this project included the advancement of

two test borings to power auger refusal depths of depth of 21.2 and 23.4 feet below the

existing ground surface. The Site Location Plan, Boring Location Plan, and Boring Logs are

included in Appendix A of this report. The results of the laboratory testing performed on soil

samples obtained from the site during the field exploration are included in Appendix B of this

report. Descriptions of the field exploration and laboratory testing are included in their

respective appendices.

We note that slope stability of the proposed cut slope is not part of Terracon’s current scope

of services. If this analysis is desired, the work could be performed as a follow-up service to

this report.

2.0 PROJECT DESCRIPTION

2.1 Project Description

ITEM DESCRIPTION

Site layout See the attached Boring Location Plan (Exhibit A-2)

Structures The EMS station will be a 2,400 s.f., single-story building with one

interior parking bay for the EMS vehicle.

Building construction The building is understood to be a steel framed structure with a

concrete slab-on-grade.



ITEM DESCRIPTION

Finished floor elevation The finished floor elevation will be 492 feet, based on the

provided grading plan.

Maximum loads

The loads were not provided at the time of this report. We have

presumed the following:

Maximum Column Load: less than 50 kips

Maximum Uniform Slab Load:

Truck stall: 300 psf

Other areas: 150 psf

Grading

Based on the provided grading plan, the majority of the site will be

cut to reach the planned grades. Cut depths will be up to 20 feet

with the deepest at the east corner of the site. There will be up to

about 2 feet of cut in the west corner of the site.

Slopes The plans indicate that cut slopes of 2H:1V are planned. The cut

heights will reach about 20 feet.

Retention/detention

A storm water detention/retention pond is planned on the west

side of the site. The depth of the pond will be about 2 feet. It will

primarily be constructed by filling perimeter embankments.

Traffic loading We anticipate moderate-duty concrete/asphalt drives and light-

duty parking stalls.

2.2 Site Location and Description

ITEM DESCRIPTION

Location The site is located on the north side of Old SC Highway 21, just

north of Ridgeway, SC.

Existing improvements The site is currently undeveloped.

Surrounding developments The site is bordered on the north and east by undeveloped land

and to the west by a rural residence.

Current ground cover The site is currently covered by moderate density deciduous

trees.

Existing topography In the general development, site topography slopes downward to

the west from Elevation 520 to 488 feet.

Existing utilities

Power lines are present along Old Highway 21. Underground

telecommunications lines were indicated along the edge of the

pavement of the north side of Old 21. No other utilities were

marked at the time of our exploration.



3.0 SUBSURFACE CONDITIONS

3.1 Geology

The subject site is located in South Carolina’s Piedmont physiographic province. The in-

place chemical and mechanical weathering of the parent sedimentary and metamorphic rock

forms the soils present in this region. A common soil profile includes a surficial clayey or silty

layer transitioning to coarser material at depth. Generally dividing the soil layer from the

bedrock is a very dense layer referred to as “partially weathered rock”. Partially weathered

rock is composed of irregular zones of very dense soil and rock. Partially weathered rock

exhibits standard penetration test values of 100 blows per foot (bpf) or more.

The topography of the underlying bedrock surface and the thickness of the various soil and

weathered rock strata vary greatly in short, horizontal distances because of variation in

mineralogy of the material, previous and present groundwater conditions, and past tectonic

activity (faulting, folding, intrusions, etc.). Further, the presence of boulders and rock

pinnacles is possible within the soil matrix.

3.2 Typical Subsurface Profile

Specific conditions encountered at each boring location are indicated on the individual

boring logs. Stratification boundaries on the boring logs represent the approximate location

of changes in soil types; in-situ, the transition between materials may be gradual. Details for

each of the borings can be found on the boring logs included in Appendix A of this report.

Based on the results of the borings, subsurface conditions on the project site can be

generalized as follows:

Description Approximate Depth to

Bottom of Stratum (feet) Material Encountered Consistency/Density

Surface 2 inches Topsoil N/A

Stratum 1 3 to 5-½

Clayey sand Loose to very dense

Stratum 2 13-½ to 21 Silty sand intermixed with partially weathered rock

(silty sand) Dense to very dense

Stratum 31 21.2 and 23.4

Partially weathered rock (silty sand)

Very dense

Notes: 1. Power auger refusal (presumed top of rock) encountered in Borings B-1 and B-2, respectively.

Laboratory testing of the moderate depth soils (Stratum 2) indicates that the silty sands have

fines contents of about 20 to 26 percent with moisture contents from 5 to 10 percent at the

time of our exploration.



3.3 Groundwater Conditions

Groundwater was not encountered in any of the borings at the time of drilling or when the

borings were checked 24 hours later. These observations represent groundwater conditions

at the time of the field exploration and may not be indicative of other times, or at other

locations.

Groundwater levels can be expected to fluctuate with varying seasonal and weather

conditions. Further, water can perch above the very dense soil and partially weathered rock

layers that comprise the explored strata and expose itself with excavation faces made

through the materials such as is planned for this site.

4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION

4.1 Geotechnical Considerations

The site is suited for the proposed construction of the planned structure. The building may

be supported by conventional spread footings with tolerable settlement estimates.

The primarily issue at this site will be the presence of high consistency soils and partially

weathered rock within the planned excavation range. The borings indicate a typical

piedmont setting, including several feet of moderate to high consistency soil transitioning to

partially weathered rock and eventually reaching the basement rock. As can be seen in the

boring logs, the thicknesses of the residual soil and partially weathered rock as well as the

depth to rock are somewhat variable. Based on limited data, the rock surface elevations

appear to generally decrease to the west, falling roughly in proportion to the existing ground

surface. From our review of the proposed grading data, it appears that rock could be

encountered by the excavation in the east portion of the pavement areas where excavation

is deepest. Utility trenches may also encounter rock.

Though groundwater was not encountered by the borings, there is the potential for periodic

groundwater seeps from the face of the cut slope due to perched water in the upper soils

above the very dense soils and partially weathered rock layers. This can occur after heavy

or prolonged rain events. It would be prudent to consider providing a ditch along the base of

the cut slope slopes to provide separation from the adjacent pavements and move the water

around the site.

Geotechnical engineering recommendations for foundation and pavement systems and

other earth related phases of the project are outlined below. The recommendations

contained in this report are based upon the results of field and lab testing presented in

Appendix A and Appendix B, respectively, engineering analyses, and our current

understanding of the proposed project.



4.2 Earthwork

The following presents recommendations for site preparation, excavation, subgrade

preparation and placement of engineered fills on the project. The recommendations

presented for design and construction of earth supported elements including foundations,

slabs and pavements are contingent upon following the recommendations outlined in this

section. All grading for the structure should incorporate the limits of the proposed structure

plus five feet beyond proposed perimeter building walls and any exterior columns.

Earthwork on the project should be observed and evaluated by Terracon. The evaluation of

earthwork should include observation and testing of engineered fill, subgrade preparation,

foundation bearing soils, and other geotechnical conditions exposed during the construction

of the project.

4.2.1 Site Preparation

After the area has been timbered and the stumps removed, topsoil, concentrations of large

roots and any other unsuitable materials should be stripped and removed from the

construction area. The stripping should extend at least 5 feet beyond the construction limits.

Clean topsoil may be stockpiled for reuse in landscaped areas or pavement shoulders.

Once the contractor’s stripping activities nears completion, we recommend that our

representative observe the subgrade to identify any remaining pockets of organics or

unsuitable material that should be removed.

The site is moderately to heavily wooded, requiring clearing and grubbing activities to

prepare the fill and shallow cut portions of the construction area for mass grading. Clearing

can, for the most part, be accomplished using conventional equipment. Small potholes and

disturbed areas will be created throughout the subgrade in the course of removing the

stumps and rootmat associated with the trees present at the site. These areas are

sometimes “leveled” in the process of cleaning the site in preparation for grading, generally

without receiving adequate compaction. We recommend that the stump holes associated

with large tree stumps be enlarged to remove any loosened soil and to allow fill placement

and compaction with conventional equipment in the fill and at-grade areas. The resulting

holes should then be backfilled as described in Section 4.2.2 of this report.

4.2.2 Subgrade Preparation

After stripping, the exposed subgrades in the at-grade areas and areas receiving fill should

be proofrolled. Cut areas should be proofrolled after they have been excavated to their

proposed subgrade levels. Proofrolling should be performed with a heavily loaded tandem

axle dump truck or with similar approved construction equipment under the observation of

the Terracon geotechnical engineer. If conditions are found to be unstable, the subgrade

should be undercut to soils that would provide a firm base for the compaction of the

structural fill. The undercut soils should be replaced with compacted structural fill, placed as



described in the “Earthwork” section of this report. Mass fill placement may commence after

proofrolling has been successfully completed.

The exposed subgrade soils will be composed of primarily silty sands which can become

unstable when exposed to construction traffic after periods of inclement weather or during

colder periods of the year. Traffic exposure to wet subgrades can destabilize what would

have been otherwise satisfactory conditions, requiring further repair. As a precaution, we

recommend that once the planned subgrade levels have been achieved, the construction

traffic be rerouted from planned structural areas (building and pavements) after periods of

precipitation to allow them to dry. This should help reduce the amount of subgrade repairs

required later in the project. Positive drainage should be maintained at all times to prevent

ponding of stormwater on exposed subgrades or during the operation life of the structure.

Additionally, when inclement weather is expected or over long holiday weekends, exposed

subgrade soils should be rolled smooth to limit stormwater infiltration into prepared

subgrade soils.

4.2.3 Material Types

Engineered fill should meet the following material property requirements:

Fill Type 1 USCS Classification Acceptable Location for Placement

Imported Structural

Fill CL, ML, SM and SC All locations and elevations

On-Site Soils 2 SC and SM All locations and elevations

Notes:

1. Controlled, compacted 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.

It should be expected that as the excavation extends downward into more dense material,

the soils excavated will be more massive. As there is limited embankment planned, it may

be more practical to stockpile some of the shallow soil in the event that the deepest soils are

difficult to breakdown for use as compacted structural fill. Otherwise, the contractor should

expect to need heavy, pad-foot rollers such as a CAT 915 to break down the partially

weathered rock into material that can be placed in 8 inch lifts and compacted. We do not

recommend the use of very coarse partially weathered rock as fill or placing boulders within

the fill as the fill thicknesses are rather limited, generally 3 feet or less.



4.2.4 Compaction Requirements

ITEM DESCRIPTION

Fill Lift Thickness

8 inches or less in loose thickness when heavy,

self-propelled compaction equipment is used.

4 inches in loose thickness when hand-guided

equipment (i.e. jumping jack or plate compactor) is

used.

Compaction Requirements 1

95% of the material’s standard Proctor maximum

dry unit weight (ASTM D698).

Moisture Content

Within the range of -2 percent and +2 percent of the

optimum moisture content as determined by the

standard Proctor test at the time of placement and

compaction.

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.

4.2.5 Excavation

Based on the boring data, the mass excavation will encounter high consistency residual

soils (SPT values greater than 30 bpf), partially weathered rock and potentially mass rock.

The use of specialized equipment will be required to excavate these materials. Large, track-

mounted excavating equipment, such as a CAT Model 320, can generally excavate through

a substantial thickness of partially weathered rock. Similarly, large bulldozers, such as a

CAT Model D-8K, equipped with a single-tooth ripper can generally break down partially

weathered rock to sizes that can be loaded and removed. Reaching near to or below the

auger refusal levels will likely require the use of pneumatic tools or explosives (if allowed),

especially in trenches.

Depending on the volume rock encountered, the contractor may consider the use of blasting

techniques. The project site is located within less than 500 feet away from an existing

residence. As such, this structure may be adversely influenced by the shock of blasting. As

such, alternate rock excavation techniques such as the use of pneumatic equipment may

also be considered. A detailed plan of the contractor’s actual method of rock removal should

be submitted to the designers for review and approval.

If rock blasting is needed, we recommend that it be monitored to determine whether any

detrimental impact occurs. Typical monitoring would include seismic accelerometers, blast

monitors and the like at the surrounding existing structures (if possible) or at least at the

property boundaries to measure the vibrations associated with both the signature blasting

and production blasting. Further, we recommend that the owner budget for a comprehensive

precondition survey of the existing structures to be made prior to commencement of any



blasting to provide a baseline of the existing conditions. A precondition survey and vibration

data may be found invaluable to help the owner protect himself from frivolous litigation.

Terracon can aid the designers in developing a plan for these activities.

Because of the presence of substantial partially weathered rock above the planned

excavation base and rock encountered just below that level, we recommend that a rock

definition similar to the one in the following paragraph be included in the project

specifications. Unit rates for mass rock and trench rock should be included in the bid

package to limit disputes, in quantifying the final volume rock excavation.

Any material which cannot either be ripped using a tracked dozer or similar

equipment with a minimum draw bar force of 60,000 pounds pulling a single-

tooth ripper or excavated using a front end loader with a minimum bucket

breakout force of 30,000 pounds should be considered mass rock. Further,

any material that cannot be excavated with a backhoe having a minimum

bucket curling force of not less than 30,000 pounds and outfitted with rock

teeth should be considered trench rock.

It is typical to excavate shallow underground utilities with small to moderate sized backhoes.

This type of equipment will likely be underpowered if those excavations must be made in

partially weathered rock and rock, expected to be present at the planned subgrade levels.

For utility trenches below the building and elsewhere, it may be more practical to over-

excavate these areas with the larger mass excavation equipment below the utility trench

depth and then replace the partially weathered rock with compacted structural fill. The

structural fill could then be more quickly excavated with moderate powered backhoes.

Further, more uniform excavations can be made in the structural fill than in partially

weathered rock. Excavations in partially weathered rock can loosen massive pieces of earth

requiring significantly more time, material, and effort to backfill with structural fill, especially if

irregularly shaped excavations are created.

Groundwater was not encountered in the borings to the auger refusal depths of 21.2 and

23.4 feet below the existing ground surface. However, perched water can collect above and

travel along very hard soil layers and bedrock. If intersected by excavation, the water can

seep into the excavation until depleted, restarting when recharged by surface water

infiltration. As a precaution, we recommend that the civil design include a shallow ditch to

separate the slope and the paved areas. The ditch should be sloped positively drain into an

area drain or other means away from the area. This will provide a means to limit a wet toe

and help limit the introduction of water into the pavement subgrades.

As a minimum, all temporary excavations should be sloped or braced as required by

Occupational Health and Safety Administration (OSHA) regulations to provide stability and

safe working conditions. Temporary excavations will probably be required during grading

operations. The grading 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 both the excavation sides and bottom.

All excavations should comply with applicable local, state and federal safety regulations,

including the current OSHA Excavation and Trench Safety Standards.

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 that Terracon is assuming any

responsibility for construction site safety or the contractor's activities; such responsibility

shall neither be implied nor inferred.

4.2.6 Additional Considerations

The geotechnical engineer should be retained during the construction phase of the project to

observe earthwork and to perform necessary tests and observations during subgrade

preparation; proofrolling; placement and compaction of controlled compacted fills; backfilling

of excavations into the completed subgrade, and just prior to construction of building floor

slabs and pavements.

4.3 Foundation Systems

4.3.1 Design Recommendations

DESCRIPTION COLUMN WALL

Net allowable bearing pressure 1 3,000 psf 3,000 psf

Minimum dimensions 24 inches 18 inches

Minimum embedment below finished grade for

frost protection 2

18 inches 18 inches

Approximate total settlement <1 inch <1 inch

Estimated differential settlement <¾ inch <¾ inch

Equivalent unit weight for passive resistance 3 300 pcf

Coefficient of sliding friction 3 0.35

1. The recommended net allowable bearing pressure is the pressure in excess of the minimum

surrounding overburden pressure at the footing base elevation. Assumes any unsuitable fill or

soft soils, if encountered, will be undercut and replaced with engineered fill.

2. And to reduce the effects of seasonal moisture variations in the subgrade soils.

3. The sides of the excavation for the spread footing foundation must be nearly vertical and the

concrete should be placed neat against these vertical faces for the passive earth pressure values

to be valid. Passive resistance in the upper 1 foot of the soil profile should be neglected. If passive

resistance is used to resist lateral loads, the base friction should be neglected.



4.3.2 Construction Recommendations

To check that soil bearing conditions compatible with the design value are achieved, we

recommend that the footing excavations be observed and tested by a Terracon

representative. This evaluation should include performing hand auger borings and dynamic

cone penetration testing (DCP) at different locations and random probing of the surface.

If unsuitable bearing soils are encountered in footing excavations, the excavations 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. The footings could also

bear on properly compacted backfill extending down to the suitable soils. Overexcavation for

compacted backfill placement below footings should extend laterally beyond all edges of the

footings at least 8 inches per foot of overexcavation depth below footing base elevation. The

overexcavation should then be backfilled up to the footing base elevation with compacted

layers of soil backfill placed in lifts of 9 inches or less in loose thickness and compacted to at

least 95 percent of the material's maximum standard effort maximum dry unit weight (ASTM

D 698).

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. If the soils at the bearing level become excessively dry, disturbed or saturated,

or frozen, the affected soil should be removed prior to placing concrete. Place a lean

concrete mud-mat over the bearing soils if the excavations must remain open overnight or

for an extended period of time. It is recommended that the geotechnical engineer be

retained to observe and test the soil foundation bearing materials.



4.4 Site Seismic Coefficient

Code Used Site Classification

2012 International Building Code (IBC) 1 C

2

1. In general accordance with the 2012 International Building Code which refers to ASCE7-10.

2. Based on the results of the soil boring which penetrated very dense soil and partially weathered

rock depths of 21.2 and 23.4 feet before encountering power auger refusal (presumed top of

rock).

4.5 Floor Slabs


DESCRIPTION VALUE

Interior building floor system Slab-on-grade concrete.

Floor slab support

Minimum 12 inches of approved on-site or imported soils

placed and compacted in accordance with Earthwork section

of this report.

Subbase 4-inch compacted layer of free draining, granular subbase

material.

Subgrade reaction modulus, k 100 pci 1

1. The structural fill material to be placed under the building has not been identified at this time. To

provide the noted k value, the material should be able to achieve a CBR value of at least 4 when

compacted to the level noted in Section 4.2.4.

A subgrade prepared and tested as recommended in this report should provide adequate

support for lightly to moderately loaded floor slabs. Slab construction can begin after the

completion of any necessary undercutting or in-place stabilization. We recommend that floor

slabs be designed as ”floating” slabs, that is, fully ground supported and structurally

independent of any building footings or walls. This is to aid in minimizing the possibility of

cracking and displacement of the floor slabs because of differential movements between the

slab and the foundation. Narrower, turned-down slab-on-grade foundations may be utilized

at the approval of the structural engineer.

The slabs should be appropriately reinforced to support the proposed loads. Moderate loads

are anticipated in the equipment parking bays. A subgrade reaction modulus achievable by

some of the area soils has been provided in the table above. The slab thickness and

reinforcement can be based on this value. The structural fill used at the site should have a

CBR value of at least 4 to provide the noted k value.

Control joints should be saw cut into the slab after concrete placement in accordance with

ACI Design Manual, Section 302.1R-37 8.3.12 (tooled control joints are not recommended).

Positive separations and/or isolation joints should be provided between slabs and all



foundations, columns or utility lines to allow independent movement. Interior trench backfill

placed beneath slabs should be compacted in accordance with recommendations outlined in

the Earthwork section of this report. Other design and construction considerations, as

outlined in the ACI Design Manual Section 302.1R, are recommended.

The use of a vapor retarder or barrier 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 sensitive to moisture. When conditions

warrant the use of a vapor retarder/barrier, the slab designer and slab contractor should

refer to ACI 302 and ACI 360 for procedures and cautions regarding the use and placement

of a vapor retarder/barrier.

4.5.2 Construction Considerations

We recommend the area underlying the floor slab be rough graded and then thoroughly

proofrolled with a loaded tandem axle dump truck prior to final grading and placement of base

rock. 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 affected material with properly

compacted fill. All floor slab subgrade areas should be moisture conditioned and properly

compacted to the recommendations in this report immediately prior to placement of the base

rock and concrete.

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 base rock and concrete and corrective action will be

required to repair the damaged areas.

4.6 Pavements


No traffic information has been provided to us at the time of this report. As such, we have

assumed the following:

Pavement design life of 20 years

Light-duty pavement (minimal loading, visitor and employee parking spaces)

Medium-duty pavement (loading below, drives and aprons)

o 30 passenger vehicles per day

o 1 trash truck per week

o 5 delivery vehicles per week

o 10 EMS trucks per week



Based on our experience with similar soil conditions, we have used a CBR value of 4 for the

design. Subgrade preparation in the pavement areas should be performed as outlined in the

“Earthwork” section of this report.

Pavement Design Alternatives

Pavement

Type Material

Layer Thickness (inches)

Medium-Duty Light-Duty

Flexible

HMA Surface Course 1 1-½ 1-½

Tack Coat 0.04 to 0.08 gal/sy -

HMA Intermediate Course 1 1-½ -

Prime Coat (If required) 0.30 gal/sy 0.30 gal/sy

Base Course1 8 6

Rigid Portland Cement Concrete

1 5 5

Base Course1 4 4

1. See “General Design Recommendations” section below.

The above sections represent minimum thicknesses and, as such, periodic maintenance

should be anticipated. Pavements subjected to high traffic volumes and heavy trucks require

thicker pavement sections.

For areas subject to concentrated and repetitive loading conditions such as entrances,

dumpster pads and areas where heavy-trucks frequently stop or turn, we recommend using a

Portland cement concrete pavement with a thickness of at least 6 inches underlain by at least

4 inches of crushed stone. As a minimum, the concrete pavement area for dumpster pads

should be large enough to support the container and tipping axle of the refuse truck.

4.6.2 General Design Recommendations

Aggregate base course should be SCDOT Graded Aggregate Base (SCDOT Section 305).

Asphaltic cement concrete should be an approved mix design selected from the current

SCDOT Standard Type C (SCDOT Section 402 and 403). Compaction levels of the asphalt

and Macadam Base Course materials should conform to SCDOT requirements.

Portland cement concrete should conform to Section 501 of the SCDOT Standard

Specifications and have a minimum flexural strength of 550 psi and compressive strength of

4,000 psi. Portland cement concrete pavement should contain about 5 to 7 percent

entrained air and should have a maximum water to cement ratio of about 0.45. A maximum

slump of 4 inches should be used for non-slip formed placement, and 2 inches for slip

formed placement. The compressive and flexural strength of the pavement should be tested



to verify its strength. The concrete should be deposited by truck mixers or agitators and

placed a maximum of 90 minutes from time the water is added to the mix.

To limit the amount of random cracking of the slab due to drying, shrinkage, or thermal

expansion and contraction of the concrete, we recommend a 15-foot maximum joint

spacing. They should be laid out as square as possible. In heavy-duty and dumpster pad

areas, we further recommend that the pavement sections be reinforced with 6-inch by 12-

inch, D5 x D3 deformed welded wire fabric. Note that the heavier steel should be in the

longitudinal direction. The reinforcing wire fabric should be placed just slightly above the

mid-depth of the slab.

Transitions from dissimilar paving materials should be thickened and then tapered to the

design section within about 5 feet. Isolation joints should be used at penetrations within the

paving and at the termination of the paving to allow free relative movement. Polyurethane,

self-leveling, elastomeric joint sealant should be used to seal all joints within the concrete

pavement to limit the flow of water to the underlying subgrade.

Construction joints should be designed as butt joints. They should be reinforced with A615

Grade 40 smooth steel dowels for load transfer while holding adjacent panels in plane and

allowing for longitudinal expansion and contraction. The dowels should be placed at the mid-

height of the slab and placed perpendicular to the panel edge, both vertically and

horizontally. One end should be lightly greased or sleeved to break the concrete bond and

allow free inter-panel movement.

4.6.3 Construction Considerations

Pavement subgrades prepared early in the project should be carefully evaluated as the time

for pavement construction approaches. We recommend the pavement areas be rough

graded and then thoroughly proofrolled with a loaded tandem-axle dump truck. Particular

attention should be paid to high traffic areas that were rutted and disturbed and to areas

where backfilled trenches are located. Areas where unsuitable conditions are located should

be repaired by replacing the materials with properly compacted fill.

The pavement subgrade may have sections that consist of very coarse partially weathered

rock. If large pieces of loosened material are present, they should be removed and replaced

with compacted structural fill or stone base. If ignored, these areas will tend to shift under

the wheel loads of heavy vehicles and cause the premature failure of the pavement.

Future performance of pavements constructed on the site will be dependent upon

maintaining stable moisture content of the subgrade soils; and, providing for a planned

program of preventative maintenance. The performance of all pavements can be enhanced

by minimizing excess moisture that can reach the subgrade soils. The following

recommendations should be considered at minimum:



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

Sealing all landscaped areas in, or adjacent to pavements to reduce moisture

migration to subgrade soils;

Placing compacted backfill against the exterior side of curb and gutter; and,

Placing curb, gutter and/or sidewalk directly on subgrade soils without the use of

base course materials.

Preventative maintenance should be planned and provided through an on-going pavement

management program in order to enhance future pavement performance. Preventative

maintenance activities are intended to slow the rate of pavement deterioration, and to

preserve the pavement investment.

Preventative maintenance consists of both localized maintenance (e.g. crack and joint

sealing and patching) and global maintenance (e.g. surface sealing). Preventative

maintenance is usually the first priority when implementing a planned pavement

maintenance program and provides the highest return on investment for pavements. Prior to

implementing any maintenance, additional engineering observation is recommended to

determine the type and extent of preventative maintenance.

5.0 GENERAL COMMENTS

Terracon should be retained to review the final design plans and specifications so

comments can be made regarding interpretation and implementation of our geotechnical

recommendations in the design and specifications. Terracon also should be retained to

provide testing and observation during excavation, grading, foundation and construction

phases of the project.

The analysis and recommendations presented in this report are based upon the data

obtained from the borings performed at the indicated locations and from other information

discussed in this report. This report does not reflect variations that may occur between

borings, across the site, or due to the modifying effects of weather. The nature and extent of

such variations may not become evident until during or after construction. If variations

appear, we should be immediately notified so that further evaluation and supplemental

recommendations can be provided.

The scope of services for this project 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.



This report has been prepared for the exclusive use of our client for specific application to

the project discussed and has been prepared in accordance with generally accepted

geotechnical engineering practices. No warranties, either express or implied, are intended or

made. Site safety, excavation support, and dewatering requirements are the responsibility of

others. In the event that changes in the nature, design, or location of the project as outlined

in this report are planned, the conclusions and recommendations contained in this report

shall not be considered valid unless Terracon reviews the changes and either verifies or

modifies the conclusions of this report in writing.

APPENDIX A

FIELD EXPLORATION

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT

INTENDED FOR CONSTRUCTION PURPOSES

521 CLEMSON ROAD COLUMBIA, SC 29229

PH. (803) 741-9000 FAX. (803) 741-9900

A-1

Exhibit SITE LOCATION MAP Project Mngr.

Drawn By:

Checked By:

Approved By:

JDF

PTK

JDF

PAM Date:

Project No.

Scale:

File Name:

73155009

N.T.S.

A-1

Feb 2015

RIDGEWAY EMS STATION


SITE

Project Mngr:

Approved By:

Checked By:

Drawn By:

Project No.

Scale:

Date:

File No.Consulting Engineers and Scientists

Exhibit

521 CLEMSON ROAD COLUMBIA, SC 29229FAX. (803) 741-9900PH. (803) 741-9000

JDF

PTK

JDF

PAM

73155009

AS SHOWN

REMS

FEBRUARY 2015

BORING LOCATION PLAN

A-2RIDGEWAY EMS STATION


DIAGRAM IS FOR GENERAL LOCATION ONLY, AND

IS NOT INTENDED FOR CONSTRUCTION PURPOSES

EXPLANATION

BORING LOCATION

SCALE IN FEET

50 0 25 50

B-1

B-2


Responsive ■ Resourceful ■ Reliable Exhibit A-3

Field Exploration Description

Two (2) test borings were drilled at the site on February 4 and 5, 2015. The borings were drilled

to power auger refusal, occurring at depths of 21.1 and 23.4 feet below the ground surface at

the approximate locations shown on the attached Boring Location Plan, Exhibit A-2.

The borings were located in the field by using the proposed site plan and an aerial photograph

of the site, and measuring from existing property lines and site features. The ground surface

elevations at the boring locations were interpolated from the contour lines shown on the

provided topographic plan and are shown on the Boring Logs. The boring locations shown on

the Boring Location Plan and the ground surface elevations shown on the Boring Logs are

approximate and should be considered accurate only to the degree implied by the method of

location.

The test borings were advanced with an ATV-mounted CME-550X drill rig utilizing 3-¼-inch

inside diameter hollow-stem augers. Penetration resistance measurements were obtained by

driving a split-spoon sampler into the subsurface materials with a 140-pound automatic hammer

falling 30 inches. The penetration resistance value is a useful index in estimating the

consistency or relative density of materials encountered. A CME automatic SPT hammer was

used to advance the split-barrel sampler in the borings performed on this site. A greater

efficiency is typically achieved with the automatic hammer compared to the conventional safety

hammer operated with a cathead and rope. Published correlations between the SPT values and

soil properties are based on the lower efficiency cathead and rope method. This higher

efficiency affects the standard penetration resistance blow count (N) value by increasing the

penetration per hammer blow over what would be obtained using the cathead and rope method.

The effect of the automatic hammer's efficiency has been considered in the interpretation and

analysis of the subsurface information for this report.

Continuous lithologic logs of each boring were recorded by our field personnel during the drilling

operations. At selected intervals, samples of the subsurface materials were taken by a driving a

split-spoon sampler.

Representative disturbed soil samples were obtained from the borings and were in sealed

containers and returned to our laboratory where our engineer visually reviewed and classified

them. The purposes of this review are to check the drillers’ field classifications and visually

estimate the soils’ relative constituents (sand, clay, etc.). The soil types and penetrometer

values are shown on the Boring Logs. These records represent our interpretation of the field

conditions based on the driller’s field logs and our engineer’s review of the soil samples. The

lines designating the interfaces between various strata represent approximate boundaries only,

as transitions between materials may be gradual.

Groundwater conditions were evaluated in each boring at the time of site exploration and when

checked again after 24 hours. The boreholes were then backfilled with the auger cuttings.


Responsive ■ Resourceful ■ Reliable Exhibit A-3

Our exploration services include storing the collected soil samples and making them available

for inspection for 60 days from the report date. The samples will then be discarded unless

requested otherwise.

0.3

3.0

5.5

8.0

13.5

21.2

TOPSOIL, (3 inches)CLAYEY SAND (SC), fine grained, reddish brown, loose

SILTY SAND (SM), trace stone fragments, fine grained, brown, dense

SILTY SAND (SM), trace stone fragments, fine grained, brown, very dense, (PartiallyWeathered Rock)

SILTY SAND (SM), trace stone fragments, fine grained, brown, very dense

PARTIALLY WEATHERED ROCK

Auger Refusal at 21.2 Feet

2-3-5N=8

12-21-27N=48

29-50/3"

6-24-35N=59

50/0"

50/0"

50/0"

2610

496.5

494

491.5

489

483.5

476

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

LOCATION

DEPTH

GR

AP

HIC

LO

G See Exhibit A-2

TH

IS B

OR

ING

LO

G IS

NO

T V

ALI

D IF

SE

PA

RA

TE

D F

RO

M O

RIG

INA

L R

EP

OR

T.

GE

O S

MA

RT

LO

G-N

O W

ELL

731

550

09 -

RE

MS

.GP

J E

NV

ST

AN

DA

RD

201

2.G

DT

2/1

7/1

5

Page 1 of 1

Advancement Method:3-1/4" Hollow Stem Auger

Abandonment Method:Borings backfilled with soil cuttings upon completion.

521 Clemson RoadColumbia, South Carolina

Notes:

Project No.: 73155009

Drill Rig: CME-550X

Boring Started: 2/4/2015

BORING LOG NO. B-1Genesis Consulting GroupCLIENT:Columbia, South Carolina

Driller: J. Pawless

Boring Completed: 2/5/2015

Exhibit: A-4

See Exhibit A-3 for description of field procedures.

See Appendix B for description of laboratoryprocedures and additional data (if any).

See Appendix C for explanation of symbols andabbreviations.

FIE

LD T

ES

TR

ES

ULT

S

PE

RC

EN

T F

INE

S

WA

TE

RC

ON

TE

NT

(%

)

Surface Elev.: 497 (Ft.)

ELEVATION (Ft.)

SA

MP

LE T

YP

E

WA

TE

R L

EV

EL

OB

SE

RV

AT

ION

S

DE

PT

H (

Ft.)

5

10

15

20

Cave-in at 20'Cave-in at 20'

WATER LEVEL OBSERVATIONSNo free water observed

PROJECT: Ridgeway EMS Station

SITE: Old SC Highway 21 Fairfield County, South Carolina

0.2

3.0

5.5

12.0

21.0

23.4

TOPSOIL, (2 inches)CLAYEY SAND (SC), fine grained, brown, loose

CLAYEY SAND (SC), with stone fragments, fine grained, brown, very dense

SILTY SAND (SM), with rock fragments, fine grained, brown, very dense, (PartiallyWeathered Rock)

SILTY SAND (SM), with rock fragments, fine grained, brown to brownish gray, very dense

PARTIALLY WEATHERED ROCK

Auger Refusal at 23.4 Feet

2-3-4N=7

11-28-31N=59

18-50/5"

13-49-50/3"

13-21-34N=55

57-45-34N=79

50/0"

205

506

503

500.5

494

485

482.5

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

LOCATION

DEPTH

GR

AP

HIC

LO

G See Exhibit A-2

TH

IS B

OR

ING

LO

G IS

NO

T V

ALI

D IF

SE

PA

RA

TE

D F

RO

M O

RIG

INA

L R

EP

OR

T.

GE

O S

MA

RT

LO

G-N

O W

ELL

731

550

09 -

RE

MS

.GP

J E

NV

ST

AN

DA

RD

201

2.G

DT

2/1

7/1

5

Page 1 of 1

Advancement Method:3-1/4" Hollow Stem Auger

Abandonment Method:Borings backfilled with soil cuttings upon completion.


Notes:

Project No.: 73155009

Drill Rig: CME-550X

Boring Started: 2/5/2015

BORING LOG NO. B-2Genesis Consulting GroupCLIENT:Columbia, South Carolina

Driller: J. Pawless

Boring Completed: 2/5/2015

Exhibit: A-5

See Exhibit A-3 for description of field procedures.

See Appendix B for description of laboratoryprocedures and additional data (if any).

See Appendix C for explanation of symbols andabbreviations.

FIE

LD T

ES

TR

ES

ULT

S

PE

RC

EN

T F

INE

S

WA

TE

RC

ON

TE

NT

(%

)

Surface Elev.: 506 (Ft.)

ELEVATION (Ft.)

SA

MP

LE T

YP

E

WA

TE

R L

EV

EL

OB

SE

RV

AT

ION

S

DE

PT

H (

Ft.)

5

10

15

20

Cave-in at 20'Cave-in at 20'

WATER LEVEL OBSERVATIONSNo free water observed



APPENDIX B

LABORATORY TESTING


Responsive ■ Resourceful ■ Reliable Exhibit B-1

Laboratory Testing Description

Samples retrieved during the field exploration were taken to the laboratory for further

observation by the project geotechnical engineer and were classified in accordance with the

Unified Soil Classification System (USCS) described in Appendix C. At that time, the field

descriptions were confirmed or modified as necessary and an applicable laboratory testing

program was formulated to determine engineering properties of the subsurface materials.

Laboratory tests were conducted on selected soil samples and the test results are presented in

this appendix. The laboratory test results were used for the geotechnical engineering analyses,

and the development of foundation and earthwork recommendations. Laboratory tests were

performed in general accordance with the applicable ASTM, local or other accepted standards.

Selected soil samples obtained from the site were tested for the following engineering

properties:

Percent Fines ASTM D1140-06 Moisture Content Determination ASTM D2216-10

Sheet 1 of 1

Summary of Laboratory Results

DryDensity

(pcf)

WaterContent

(%)

BORINGID

CompressiveStrength

(tsf)

%<#200Sieve

LiquidLimit

USCS Classificationand Soil Description

Depth(ft)

PlasticLimit

PlasticityIndex

%Gravel

%Sand


PROJECT NUMBER: 73155009

CLIENT: Genesis Consulting Group Columbia, South Carolina

EXHIBIT: B-2

LAB

OR

AT

OR

Y T

ES

TS

AR

E N

OT

VA

LID

IF S

EP

AR

AT

ED

FR

OM

OR

IGIN

AL

RE

PO

RT

. L

AB

SU

MM

AR

Y:

US

CS

731

5500

9 -

RE

MS

.GP

J E

NV

ST

AN

DA

RD

201

2.G

DT

2/1

7/1

5

B-1 8.5 - 10 26.3 9.8

B-2 8.5 - 9.8 20.2 4.8



APPENDIX C

SUPPORTING DOCUMENTS

TraceWithModifier

Water Level Aftera Specified Period of Time

GRAIN SIZE TERMINOLOGYRELATIVE PROPORTIONS OF SAND AND GRAVEL

TraceWithModifier

Standard Penetration orN-Value

Blows/Ft.

Descriptive Term(Consistency)

Loose

Very Stiff

Exhibit C-1

Standard Penetration orN-Value

Blows/Ft.

Ring SamplerBlows/Ft.

Ring SamplerBlows/Ft.

Medium Dense

Dense

Very Dense

0 - 1 < 3

4 - 9 2 - 4 3 - 4

Medium-Stiff 5 - 9

30 - 50

WA

TE

R L

EV

EL

Auger

Shelby Tube

Ring Sampler

Grab Sample

8 - 15

Split Spoon

Macro Core

Rock Core

PLASTICITY DESCRIPTION

Term

< 1515 - 29> 30

Descriptive Term(s)of other constituents

Water InitiallyEncountered

Water Level After aSpecified Period of Time

Major Componentof Sample

Percent ofDry Weight

(More than 50% retained on No. 200 sieve.)Density determined by Standard Penetration Resistance

Includes gravels, sands and silts.

Hard

Very Loose 0 - 3 0 - 6 Very Soft

7 - 18 Soft

10 - 29 19 - 58

59 - 98 Stiff

less than 500

500 to 1,000

1,000 to 2,000

2,000 to 4,000

4,000 to 8,000> 99

LOCATION AND ELEVATION NOTES

SA

MP

LIN

G

FIE

LD

TE

ST

S

(HP)

(T)

(b/f)

(PID)

(OVA)

DESCRIPTION OF SYMBOLS AND ABBREVIATIONS

Descriptive Term(Density)

Non-plasticLowMediumHigh

BouldersCobblesGravelSandSilt or Clay

10 - 18

> 50 15 - 30 19 - 42

> 30 > 42

_

Hand Penetrometer

Torvane

Standard PenetrationTest (blows per foot)

Photo-Ionization Detector

Organic Vapor Analyzer

Water levels indicated on the soil boringlogs are the levels measured in theborehole at the times indicated.Groundwater level variations will occurover time. In low permeability soils,accurate determination of groundwaterlevels is not possible with short termwater level observations.

CONSISTENCY OF FINE-GRAINED SOILS

(50% or more passing the No. 200 sieve.)Consistency determined by laboratory shear strength testing, field

visual-manual procedures or standard penetration resistance

DESCRIPTIVE SOIL CLASSIFICATION

> 8,000

Unless otherwise noted, Latitude and Longitude are approximately determined using a hand-held GPS device. The accuracyof such devices is variable. Surface elevation data annotated with +/- indicates that no actual topographical survey wasconducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographicmaps of the area.

Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dryweight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils haveless than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, andsilts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may beadded according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are definedon the basis of their in-place relative density and fine-grained soils on the basis of their consistency.

Plasticity Index

01 - 1011 - 30

> 30

RELATIVE PROPORTIONS OF FINES

Descriptive Term(s)of other constituents

Percent ofDry Weight

< 55 - 12> 12

No Recovery

RELATIVE DENSITY OF COARSE-GRAINED SOILS

Particle Size

Over 12 in. (300 mm)12 in. to 3 in. (300mm to 75mm)3 in. to #4 sieve (75mm to 4.75 mm)#4 to #200 sieve (4.75mm to 0.075mmPassing #200 sieve (0.075mm)

ST

RE

NG

TH

TE

RM

S Unconfined CompressiveStrength, Qu, psf

4 - 8

GENERAL NOTES

Exhibit C-2

UNIFIED SOIL CLASSIFICATION SYSTEM

Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A

Soil Classification

Group

Symbol Group Name

B

Coarse Grained Soils:

More than 50% retained

on No. 200 sieve

Gravels:

More than 50% of

coarse fraction retained

on No. 4 sieve

Clean Gravels:

Less than 5% fines C

Cu 4 and 1 Cc 3 E

GW Well-graded gravel F

Cu 4 and/or 1 Cc 3 E

GP Poorly graded gravel F

Gravels with Fines:

More than 12% fines C

Fines classify as ML or MH GM Silty gravel F,G,H

Fines classify as CL or CH GC Clayey gravel F,G,H

Sands:

50% or more of coarse

fraction passes No. 4

sieve

Clean Sands:

Less than 5% fines D

Cu 6 and 1 Cc 3 E

SW Well-graded sand I

Cu 6 and/or 1 Cc 3 E

SP Poorly graded sand I

Sands with Fines:

More than 12% fines D

Fines classify as ML or MH SM Silty sand G,H,I

Fines classify as CL or CH SC Clayey sand G,H,I

Fine-Grained Soils:

50% or more passes the

No. 200 sieve

Silts and Clays:

Liquid limit less than 50

Inorganic: PI 7 and plots on or above “A” line

J CL Lean clay

K,L,M

PI 4 or plots below “A” line J ML Silt

K,L,M

Organic: Liquid limit - oven dried

0.75 OL Organic clay

K,L,M,N

Liquid limit - not dried Organic silt K,L,M,O

Silts and Clays:

Liquid limit 50 or more

Inorganic: PI plots on or above “A” line CH Fat clay

K,L,M

PI plots below “A” line MH Elastic Silt K,L,M

Organic: Liquid limit - oven dried

0.75 OH Organic clay

K,L,M,P

Liquid limit - not dried Organic silt K,L,M,Q

Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat

A Based on the material passing the 3-inch (75-mm) sieve

B If field sample contained cobbles or boulders, or both, add “with cobbles

or boulders, or both” to group name. C

Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded

gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly

graded gravel with silt, GP-GC poorly graded gravel with clay. D

Sands with 5 to 12% fines require dual symbols: SW-SM well-graded

sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded

sand with silt, SP-SC poorly graded sand with clay

E Cu = D60/D10 Cc =

6010

2

30

DxD

)(D

F If soil contains 15% sand, add “with sand” to group name.

G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.

H If fines are organic, add “with organic fines” to group name.

I If soil contains 15% gravel, add “with gravel” to group name.

J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.

K If soil contains 15 to 29% plus No. 200, add “with sand” or “with gravel,”

whichever is predominant. L

If soil contains 30% plus No. 200 predominantly sand, add “sandy” to

group name. M

If soil contains 30% plus No. 200, predominantly gravel, add

“gravelly” to group name. N

PI 4 and plots on or above “A” line. O

PI 4 or plots below “A” line. P

PI plots on or above “A” line. Q

PI plots below “A” line.

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