SUBSURFACE EXPLORATION AND GEOTECHNICAL …€¦ · Matrix Engineering Group, Inc. (Matrix) has...

SUBSURFACE EXPLORATION AND

GEOTECHNICAL ENGINEERING EVALUATION

AT

Clifton Elementary School Replacement 3132 Clifton Church Road, SE

Atlanta, Georgia

Submitted to

DeKalb County School District Sam A. Moss Service Center

1780 Montreal Road Tucker, Georgia 30084

PROJECT NUMBER: MEG 301434 December 2013

4358 Chamblee Tucker Road, Ste 3 Tucker, GA 30084 Tel. 7704483124

Fax. 7704485324 www.matrixengineeringgroup.com

December 30, 2013 Mr. Brian Albanese, Project Manager DeKalb County School District Sam A. Moss Service Center 1780 Montreal Road Tucker, Georgia 30084 Re: Subsurface Exploration and Geotechnical Engineering Evaluation

Clifton Elementary School Atlanta, Georgia 30316

Matrix Engineering Group Project Number MEG-301434 Dear Mr. Albanese: Matrix Engineering Group, Inc. has completed the authorized Subsurface Exploration for the proposed development at the Clifton Elementary School located in Atlanta, Georgia. The scope of this work included the drilling of thirteen (13) soil test borings. This report describes our investigative procedures and presents our findings, conclusions and engineering recommendations. Additionally, a Multi-Channel Analysis of Surface Waves (MASW) was performed in order to determine the in situ shear wave velocity profile for the upper 100 ft of subsurface. The weighted average Shear Wave Velocity was used to determine the IBC 2012 seismic site class and provide the recommended Design Accelerations (SDS & SD1). Matrix Engineering Group, Inc. appreciates the opportunity to have worked with the DeKalb County School District on this project and looks forward to our future association. If you have any questions or need further assistance, please do not hesitate to call. Best Regards,

MATRIX ENGINEERING GROUP, INC. Eric Taylor Amin Tomeh, PE Project Manager Senior Geotechnical Engineer [email protected] Principal [email protected] Distribution (email .PDF): Mr. Brian Albanese – DeKalb County Schools M:\1.0 MATRIX PROJECTS FOLDER\Clifton Elementary School\1.0 GEOTECHNICAL - MEG 301434\ Report\Subsurface Exploration - Clifton Elem Dec 2013.doc

Geotechnical, Environmental, and Construction MatConsultants Geotechnical, Environmental, and ConsMaterials Consultants Geotechnical, EnvironmentalConstruction Materials Consultants Geotechnical, and Construction Materials Consultants GeotechniGeotechnical, Environmental, and Construction MatConsultants Geotechnical, Environmental, and ConsMaterials Consultants Geotechnical, EnvironmentalConstruction Materials Consultants Geotechnical,

MATRIX ENGINEERING GROUP, INC.

EXECUTIVE SUMMARY A subsurface exploration was completed for the proposed Clifton Elementary School Replacement at the existing campus of the Clifton Elementary School located in Atlanta, Georgia. The objective of this exploration was to evaluate the subsurface soil conditions and provide recommendations for the site preparation and construction of the proposed development. For detailed information and discussions, refer to the appropriate section in the body of this report. The project will consist of the construction of a new, two-story elementary school facility and

involves demolition of the existing school building. The project will also include construction of a new playground, parking area and driveways.

A total of thirteen (13) soil test borings, designated as B1 through B13, were performed throughout

the subject site in order to explore the subsurface conditions and provide specific geotechnical recommendations for the proposed development.

The site has been graded in the past during the construction of the existing school buildings. The

northern areas of the site (around the existing school buildings) are primarily covered with asphalt pavement and underlying layer of Graded Aggregate Base (GAB), which measured approximately six (6) inches in total thickness. The southern areas of the site are primarily covered with a layer of grass and topsoil, which measured approximately four (4) inches in thickness.

Man made fill or disturbed soils were noted at test borings B2, B4, B5, B6, B7, B8, B12 and B13.

The fill thickness ranges between 3.5 and 8.5 feet BGS. The fill material generally consisted of loose to medium dense, silty sand (SM) and firm, silty clay (ML-CL). The consistency of the fill material ranged between 6 blows/ft (bpf) and 23 bpf, but was typically observed to be between 6 and 13 bpf.

Residual soils were encountered at each of the soil borings below the encountered fill material. The

residual soils generally consisted of interbedded layers of medium dense to very dense, silty coarse to fine sands (SM). The soil consistency of the residual material ranged between 2 and 51 bpf, but was typically observed to be between 6 and 33 bpf.

Partially weathered rock (PWR) was found in borings B1, B2, B4, B5, B6, B8, B9, B10 and B13 at

depths ranging from 0.5 to 19.5 feet BGS. Additionally, shallow auger refusal was encountered at test borings B1, B2, B4, B5, B6, B7, B9, B10, B11, B12 and B13 at depths ranging from 2-19.5 feet BGS. Due to the presence of PWR and shallow refusal, general recommendations for rock excavation are provided in Section 7.1 of this report.

Due to safety concerns associated with the occupants at the site, the borings were backfilled at the

completion of drilling prior to leaving the site, and a stabilized 24-hour groundwater reading was forgone. Groundwater was not encountered at any of the test borings at the time of drilling. All borings were backfilled by Matrix staff at the completion of the drilling operation.

The data indicates that the building may be supported on shallow foundations. These foundations

should be situated below the loose and surficial materials in residual soils or newly constructed fill and be designed for a maximum allowable bearing pressure of 3,000 psf. Refer to Section 7.5.

Based on the data obtained from the boring logs and the provided site plans prior to writing this

report, foundations for the proposed development will be situated in previously placed fill materials in the northern-most areas of the building footprint. The encountered existing fill should be adequate to provide the recommended bearing capacity. However, because of the heterogeneity of man-made fill,

any fill areas should be evaluated and tested carefully during construction. A recommended foundation inspection criterion is provided in Section 8.2 of this report.

Based on the soils encountered, the existing subgrades appear to be generally adequate for the

placement of the fill required to prepare the building pad and site grades. It should be noted that the soils below the existing structures were unexplored. We assume that the soils below the existing structures are at least as suitable as the soils encountered at the test boring locations, however, the condition of these soils cannot be ascertained without proper testing. Once prepared, the suitability of the exposed subgrades in all areas should be confirmed by a geotechnical engineer prior to placing new fill.

Due to the presence of an underground utility line within the proposed building footprint, we

recommend that the utility line be properly abandoned and removed. The concrete slab-on-grade for the proposed structure should be supported on new fill or residual

soils, which have been scarified and recompacted in accordance with the subgrade preparation recommendations in Section 7.3 of this report. Provided the fill material is installed to a minimum of 95% of the standard maximum dry density, a modulus of subgrade reaction (k) of 125 pci can be used for designing the floor slab-on-grade. Refer to Section 7.4 of this report for additional recommendations.

The onsite material appears to be suitable for structural fill and retaining wall backfill provided they

are moisture conditioned at the time of construction. An angle of internal friction () = 28 º and a cohesion c=200 pcf can be used as design strength parameters for the material.

Based on our experience with projects of similar magnitude and soil conditions, we recommend that a

subgrade CBR value of 4 be used for the design of new flexible pavements, and a modulus of subgrade reaction (k) of 125 pci be used for the design of new rigid pavements and concrete slabs-on-grade, provided the new fill is placed in accordance with our recommendations. Refer to Sections 7.5 of this report for specific design recommendations.

Based on the Multi-Channel Analysis of Surface Waves (MASW) technique and the resulting

Vs100 of 1,755 ft/sec, we recommend that a Site Class “C” be used for seismic design purposes per IBC2012.

TABLE OF CONTENT

Cover Letter

Executive Summary

Table of Content

SECTION Page Number

1.0 INTRODUCTION............................................................................................................................................ 1 2.0 PROJECT DESCRIPTION............................................................................................................................ 1 3.0 SCOPE OF WORK.......................................................................................................................................... 1 4.0 EXPLORATION AND TESTING PROGRAM.......................................................................................... 2

4.1 Subsurface Exploration............................................................................................................................. 2 4.2 Laboratory Testing ..................................................................................................................................... 3

5.0 SITE DESCRIPTION AND GENERAL SITE GEOLOGY ..................................................................... 3

5.1 Site Description........................................................................................................................................... 3 5.2 General Site Geology.................................................................................................................................. 4

6.0 GENERAL SUBSURFACE CONDITIONS................................................................................................ 4

6.1 Surface Materials and Man-Made Fill..................................................................................................... 5 6.2 Residual Material ....................................................................................................................................... 5 6.3 Partially Weathered Rock and Bedrock ................................................................................................... 5 6.4 Groundwater............................................................................................................................................... 5 6.5 Summary of Test Boring Records............................................................................................................. 6

7.0 FINDINGS AND RECOMMENDATIONS................................................................................................. 7

7.1 Excavation Considerations........................................................................................................................ 7 7.2 Groundwater & Dewatering...................................................................................................................... 8 7.3 Subgrade Preparation................................................................................................................................ 9 7.4 Slab-On-Grade Construction .................................................................................................................... 9 7.5 Pavement Design...................................................................................................................................... 10 7.6 Foundations.............................................................................................................................................. 10 7.8 Slopes and Vertical Cuts .......................................................................................................................... 11 7.7 Retaining Walls and Lateral Earth Pressures ....................................................................................... 11 7.9 Seismic Site Classification (IBC 2012)................................................................................................... 13

8.0 CONSTRUCTION RECOMMENDATIONS ........................................................................................... 15

8.1 Structural Fill ........................................................................................................................................... 15 8.2 Construction Inspection and Testing...................................................................................................... 16

APPENDIX

Figure 1: Approximate Soil Boring & MASW Locations Figure 2: Contoured Depths to Auger Refusal or PWR Correlation of Standard Penetration Resistance with Relative Compactness Consistency

Soil Boring Logs & Cutlines Laboratory Test Results USGS Design Maps Reports

Subsurface Exploration and Engineering Evaluation December 30, 2013 Clifton Elementary School Matrix Engineering Group Project No. 301434

M A T R I X E N G I N E E R I N G G R O U P , I N C . T u c k e r , G e o r g i a

1

1.0 INTRODUCTION

Matrix Engineering Group, Inc. (Matrix) has completed the authorized Subsurface Exploration and

Geotechnical Engineering Evaluation for the proposed Clifton Elementary School Replacement on the

existing campus of the Clifton Elementary School, which is located at 3132 Clifton Church Road, in

Atlanta, Georgia. The objective of this exploration was to perform thirteen (13) soil test borings in order

to explore the subsurface conditions, and provide the findings and recommendations regarding the

geotechnical aspects of the proposed development. This report describes our investigative procedures

and presents our findings, conclusions and engineering recommendations.

This work was authorized on December 10, 2013 and performed in general accordance with the

Geotechnical Services Quote Form which was issued on November 26, 2013, as part of RFQ Number 14-

752-007, dated November 14, 2013.

2.0 PROJECT DESCRIPTION

The proposed project consists of construction of a new, two-story elementary school facility and

involves demolition of the existing school building. The project will also include construction of

a new playground, parking area and driveways.

The proposed Finished Floor Elevation (FFE) for the proposed facility is unknown at the time of

writing this report.

Anticipated column loads are also unknown at the time of writing this report.

3.0 SCOPE OF WORK

The scope of work for this project consisted of:

Drilling and sampling a total of thirteen (13) soil test borings located throughout the site in order

to explore the subsurface conditions and provide geotechnical recommendations for the proposed

development. Borings were extended to a maximum depth of 20 feet below the existing ground

surface (BGS). Due to shallow auger refusal at some locations, a total of six (6) offset borings

were performed near the designated boring locations.

Field and laboratory testing to determine the engineering characteristics of the soils encountered

in the soil borings.

Performing a Seismic Site Classification per Chapter 16 of the 2012 International Building Code

(IBC2012) utilizing the measured average shear wave velocity for the upper 100 feet of

subsurface (Vs,100).



2

Providing recommended short (0.2 second) and 1-second Design Response Accelerations (SDs &

SD1) for seismic events having a 2% probability of exceedance in 50 years.

Performing a geotechnical engineering analysis for the proposed development.

Preparation of this geotechnical report based on the data gathered during the exploration.

The purpose of this report is to document the site subsurface conditions, to analyze and evaluate the data

obtained, and to provide recommendations regarding the geotechnical aspects of the proposed

development.

4.0 EXPLORATION AND TESTING PROGRAM

4.1 Subsurface Exploration

The geotechnical exploration program consisted of the drilling and sampling of a total of thirteen (13) soil

test borings located throughout the project site. The test borings were located in the field by Matrix staff

utilizing tape measurements and a compass, while relying on existing features (i.e. existing buildings,

parking areas and the general site layout). The approximate locations of the soil borings are presented on

Figure 1 in the appendix of this report. For exact locations, the owner may elect to survey the boring

locations. Matrix should be informed of any deviations in order to evaluate and modify our

recommendations, if necessary.

The subsurface exploration was performed using a truck-mounted CME 55 drill rig equipped with an

automatic hammer in general accordance with ASTM D1586 standards. The borings were advanced to

depths of up to 20 feet BGS. Borings were advanced by augering through the soils with continuous

flights of 3 inch augers. At regular intervals, the auger flights were removed from the bore hole, and soil

samples were obtained through the center of the bore hole with a standard 1.4-inch I.D., 2.25-inch O.D.,

split-tube sampler. The sampler is first seated 6 inches to penetrate any loose cuttings, and then driven an

additional foot with blows of a 140-pound hammer falling 30 inches. The number of hammer blows

required to drive the sampler the final foot is recorded and is designated as the Standard Penetration

Resistance (N-Value). The penetration resistance, when properly evaluated, is an index of the soil

strength, consistency and ability to support foundations.

Representative soil samples were obtained using split-spoon sampling techniques. The samples were

classified in the field in general accordance with ASTM D2488 (Visual-Manual Procedure for Description

of Soils). Representative portions of the soil samples were placed in sealable, plastic bags and transported

to our laboratory. During the field operations, Matrix staff maintained a continuous log of the subsurface



3

conditions including changes in the stratigraphy and any observed groundwater levels. Soil descriptions

and penetration resistance values are presented graphically on the Soil Boring Records included in the

Appendix of this report.

4.2 Laboratory Testing

The laboratory testing program for this project consisted of performing soil classifications in accordance

with ASTM D2488-06, as well as Laboratory Moisture Content Determination in general accordance with

ASTM D2216. The soil samples were examined by a geotechnical engineer and visually classified on the

basis of texture and plasticity in accordance with the Unified Soil Classification System.

The soil samples are kept in sealed plastic bags and will be stored for a period of 60 days and then

disposed of unless otherwise instructed by the owner or the engineer.

5.0 SITE DESCRIPTION AND GENERAL SITE GEOLOGY

5.1 Site Description

The Clifton Elementary School is located at 3132 Clifton Church Road SE in Atlanta, Georgia 30316.

The subject site consists of the area immediately surrounding the existing school buildings, as well as

the area designated for the proposed school building and driveways. The site is accessible from the

school entrance from along Clifton Church Road. Based on an existing site survey by Geosurvey,

Ltd. On April 24, 2002, the site occupies approximately 16.22 acres. The Finished Floor Elevations

of the existing school buildings are at or near 819 feet MSL. Underground utilities are present

throughout the site and, most notably, an 18” Corrugated Metal Pipe (CMP) is located below the

proposed building footprint.

Based on the Conceptual Site Plan which was dated on December 12, 2013, the proposed school

building will be located just south of the existing school buildings and will overlap the southern-most

portion of the existing school building footprint. A Parent Drop-off & Pick Up Area and Bus Drop-

off & Pick Up Area are proposed west and south of the proposed building footprint, respectively. It

appears that the existing parking area will be expanded to 116 parking spaces and extend further

south than the existing parking area. A future PE Addition is designated along the rear elevation of

the proposed building.

Based on a review of USGS Maps, as well as our visual observations, the portion of the subject site

which is currently occupied with the existing school buildings is generally level, with an approximate



4

elevation of 820 feet MSL and slopes downwards at the existing play area within the southern areas

to an elevation of approximately 780 feet MSL along the southern periphery of the site. The site has

generally been developed in the past during the construction of the existing school building, but the

boundaries of the site are generally wooded. Topographic relief from the site is on the order of 15-20

feet.

5.2 General Site Geology

The subject site is located in the Piedmont Geologic Province, which contains the oldest rock formations

in the Southeastern United States. The parent rocks in the region are primarily comprised of the

unconsolidated mass of quartz, feldspar, mica, and a wide variety of dark minerals such as hornblende and

amphibole.

The proportion of felsic and mafic minerals in these parent rocks, as well as of quartz that is very resistant

to weathering, limits the amount of clay in the soils. Therefore these soils are sandy and have faint

horizons, and in small-scattered areas, hard rock is exposed.

Chemical decomposition initially occurs along the boundaries of individual mineral crystals. As a result,

partially weathered rock has the appearance of dense sand (SM, SP). With further weathering, the

individual crystals other than quartz are attacked and the mass becomes a micaceous silty sand (SM) or

micaceous sandy silt (ML). In this stage, the original banding of the parent rock is apparent, but the

original crystalline structure is not observed. Reflecting the composition of the original rock, mica flakes,

rather than the quartz grains, often comprise the majority of the sand-size particles. Finally, in the more

advanced stages of chemical weathering, the material is changed into a red or reddish-brown silty clay

(CL or CH) or clayey silt (ML or MH). Depending on the quartz content, a sandy fraction will be present.

In this weathered stage, the banding and crystalline structure of the parent rocks is lost.

6.0 GENERAL SUBSURFACE CONDITIONS

The subsurface conditions were characterized by visual-manual examination of the soils obtained from the

split-spoon sampler and observation from the auger’s cutting during the drilling operation. The soil

boring logs, designated as B1 to B13, are provided in the appendix of this report. The test borings were

extended to a maximum depth of 20 feet below ground surface (BGS) elevations. The subsurface

conditions within the drilled borings are characterized as follows:



5

6.1 Surface Materials and Man-Made Fill

The site has been graded in the past during the construction of the existing school buildings. The northern

areas of the site (around the existing school buildings) are primarily covered with asphalt pavement and

underlying layer of Graded Aggregate Base (GAB), which measured approximately six (6) inches in total

thickness. The southern areas of the site are primarily covered with a layer of grass and topsoil, which

measured approximately four (4) inches in thickness. Topsoil thickness may vary elsewhere onsite and the

reported thicknesses should not be used to estimate the amount of stripping that will be necessary to

properly prepare the site for structural fill. Additionally, the term topsoil should not connote a horticultural

(or agricultural) definition or classification, but rather a visually determined organic-laden material.

Man made fill was encountered at test borings B2, B4, B5, B6, B7, B8, B12 and B13. The fill thickness

ranges between 3.5 and 8.5 feet BGS. The fill material generally consisted of loose to medium dense,

silty sand (SM) and firm, silty clay (ML-CL). The consistency of the fill material ranged between 6

blows/ft (bpf) and 23 bpf, but was typically observed to be between 6 and 13 bpf.

6.2 Residual Material

Residual soils are those which have weathered in place from the parent rock. Residual soils were

encountered at each of the soil borings below the encountered fill and/or surface materials. The residual

soils generally consisted of interbedded layers of medium dense to very dense, silty coarse to fine sands

(SM). The soil consistency of the residual material ranged between 2 and 51 bpf, but was typically

observed to be between 6 and 33 bpf.

6.3 Partially Weathered Rock and Bedrock

Partially Weathered Rock (PWR) is a regionally used term for residual material with a Standard

Penetration Resistance of 100 bpf or more, but which can be penetrated by the soil drilling equipment.

PWR, or shallow auger refusal in rock material, were encountered at borings performed within the drilled

residual soil depths. Partially weathered rock was found in borings (B1, B2, B4, B5, B6, B8, B9, B10 and

B13) at depths ranging from 0.5 to 19.5 feet BGS. Additionally, shallow auger refusal was encountered at

test borings B1, B2, B4, B5, B6, B7, B9, B10, B11, B12 and B13 at depths ranging from 2-19.5 feet BGS.

6.4 Groundwater

Groundwater level measurements were obtained in boreholes at the completion of drilling. Due to

safety concerns associated with the occupants at the site, the borings were backfilled at the

completion of drilling prior to leaving the site, and a stabilized 24-hour groundwater reading was



6

forgone. Groundwater was not encountered at any of the test borings. Groundwater elevations do

fluctuate with seasonal changes and typically vary on the order of 4 to 8 feet.

6.5 Summary of Test Boring Records

The geologic profile described generally represents the conditions encountered in the soil borings. Some

variations in the description should be expected. The stratification lines designating the interfaces between

earth materials shown on the boring logs are approximate; in-situ transition may be gradual.

Table 1 below summarizes the field findings from the soils test borings.

Table 1: Summary of test boring records.

Boring No.

Planned Depth (ft)

Groundwater Depth (ft)

PWR Depth (ft)

Auger Refusal Depth (ft)

B1 20 N/E 0.5 4

B2 20 N/E 18.5 19.5

B3 20 N/E N/E N/E

B4 20 N/E 8.5 9.5

B5 20 N/E 18.5 19.5

B6 20 N/E 8.5 9.5

B7 20 N/E N/E 12

B7-A 20 N/E N/E N/E

B8 20 N/E 8.5 N/E

B9 20 N/E 3.5 5

B9-A 20 N/E 18.5 N/E

B10 20 N/E 0.5 2

B11 20 N/E N/E 6



7

Boring No.

Planned Depth (ft)

Groundwater Depth (ft)

PWR Depth (ft)

Auger Refusal Depth (ft)

B12 20 N/E N/E 17.5

B13 20 N/E 8.5 10

7.0 FINDINGS AND RECOMMENDATIONS

The following recommendations are based on the information furnished to us, the data obtained from the

subsurface exploration, and our past experience with similar projects. They were prepared in general

accordance with established and accepted professional geotechnical engineering practice in this region.

Our recommendations are based on findings from the dates referenced within this report and do not

reflect any variations that would likely exist at later dates or between the pre-designated borings or

unexplored areas. Depths and/or thicknesses are approximate and should not be used for estimating

quantities during construction, specifically as it relates to topsoil or other surface materials.

If information becomes available which may impact our recommendations, Matrix Engineering Group

shall be afforded the opportunity to review this information and re-evaluate the recommendations

contained within this report and make any alterations deemed necessary by a Georgia Registered

professional engineer. This report is intended for the use of DeKalb County Board of Education and its

current design team. No other warranty is expressed or implied. Matrix Engineering Group, Inc. is not

responsible for conclusions, opinions, or recommendations made by others based on this report.

It should be noted that the soils below the existing structures were unexplored. We assume that the soils

below the existing structures are at least as suitable as the soils encountered at the test boring locations,

however, the condition of these soils cannot be ascertained without proper testing.

The following recommendations present general guidelines for the proposed development.

7.1 Excavation Considerations

The recommendations provided in this Section are based on the Conceptual Site Plan, as well as email

correspondence with Mr. Brian Albanese (DCSD). It is our understanding that the FFE for the proposed

building has not been determined. We assume that the FFE for the proposed building will be at or near the



8

existing building elevations. We assume that the existing grades for the proposed building pad will require

excavation and fill placement on the order of 5 to 10 feet to prepare the proposed site grades. Due to the

presence of underground utilities and fill materials within the proposed building area, we recommend that

any material which is excavated and planned for re-use as structural fill be examined by the geotechnical

engineer of record at the time of excavation in order to determine the its suitability.

Based on the site topography, it appears that excavation will generally be planned for the southern areas

of the site, as well as utility trenches. Information regarding the locations and elevations of proposed

underground utilities were not provided to us at the time of issuing this report.

PWR was encountered at test borings B1, B2, B4, B5, B6, B8, B9, B10 and B13 at depths ranging from

0.5 to 19.5 BGS with auger refusal at test borings B1, B2, B4, B5, B6, B7, B9, B10, B11, B12 and B13

at depths ranging from 2-19.5 feet BGS. Depending on the final design elevations, some amount of

non-conventional grading, such as localized blasting or hammering may be required near these areas.

Based on these observations, we recommend that the following general specifications for rock

excavation, or a variation thereof, be incorporated into the project documents:

General Recommendations for Rock Excavation:

Rock excavation shall consist of all material which can not be excavated except by drilling, blasting or wedging.

It shall consist of un-decomposed stone hard enough to ring under a hammer, and the amount of solid stone

shall be not less than one (1) cubic yard in volume. Rock is further defined as follows:

(1) General Excavation: Any material occupying an original volume of more than one cubic yard which cannot

be excavated with a single-tooth ripper drawn by a crawler tractor having a minimum draw bar pull rated at not

less than 80,000 pounds (caterpillar D-8 or larger)

(2) Trench Excavation: Any material occupying an original volume of more than one cubic yard which cannot

be excavated with a backhoe having a bucket curling force rated at not less than 40,000 pounds, using a rock

bucket and rock teeth (a John Deere 790 or larger).

7.2 Groundwater & Dewatering

Based on the lack of groundwater at the time of this investigation, and the proposed finished grades,

we do not anticipate groundwater to impact the construction of the proposed development.



9

If encountered, groundwater levels should be maintained at a minimum of 3 feet below the bottom of

any proposed excavation (only during construction) in order to protect the exposed subgrade’s

integrity. Groundwater levels should be controlled utilizing sump and pump systems as needed at the

time of construction. If necessary, a thin “mud-mat” of lean or rejected concrete, or crushed stone,

can be placed at the bottom of an open excavation in order to protect the exposed sub-grades

integrity.

7.3 Subgrade Preparation

Based on the soils encountered, the existing subgrades appear to be adequate for placement of the fill that

may be required to prepare the building pads and site grades. Subgrade preparation for the proposed

development should be the stripping of topsoil and soft soils, if encountered, and recompacting the upper

12 inches of the exposed subgrade to 98% of the maximum dry density, as determined by Standard

Proctor testing (ASTM D 698). The presence of underground utility lines, or other items, such as septic

tanks, or trash pits during the grading operation should be treated on an individual basis. Due to the

presence of an underground utility line within the proposed building footprint, we recommend that the

utility line be properly abandoned and removed. If removed, the excavation should be backfilled with

structural fill in accordance with the recommendations of Section 8.1 of this report.

Once prepared, the suitability of the exposed subgrades in all areas should be confirmed by a geotechnical

engineer, prior to placing new fill. A proofroll test should be performed with a loaded tandem-wheeled

dump truck with an approximate weight of 25 tons. Any material that deflects excessively or ruts under

the loaded truck should be densified or removed and replaced with well-compacted materials. The

proofrolling should be observed by the geotechnical engineer.

7.4 Slab-On-Grade Construction

The concrete slab-on-grade for the proposed structure will be supported on new fill. Provided the fill

material is installed to a minimum of 95% of the maximum dry density (standard effort), a modulus of

subgrade reaction (k) of 125 pci can be used for designing the floor slab-on-grade. Slab reinforcement

and joint spacing should be carefully considered to control random cracking due to slab shrinkage. Slabs

should be isolated from the foundations to allow differential movements to take place between the

slab and walls. We recommend that at least a 10 mil vapor barrier/retarder (such as polyethylene) be

installed below the (slab-on-grade) concrete to limit intrusion of water vapor through the slab.

Beneath slab-on-grade areas, a minimum of 4 inches of clean, densely-graded, granular material with

a balanced content of fines is recommended to facilitate fine grading and provide stable surface for



10

construction traffic and building loads. Open-graded bases do not meet these requirements because

they are relatively incompactable, difficult to trim, and are unstable for construction traffic. It is also

difficult to fine grade an open-graded base to a relatively uniform elevation, which can result in

restraint to concrete movement as the concrete cools or dries, thus increasing the probability of out-

of-joint cracking. If open-graded bases are specified, the surface of these bases should be choked off

with a clean fine-graded material with at least 10 to 30% of the particles passing a No. 100 sieve, but

not contaminated with clay, silt, or organic material.

7.5 Pavement Design

Based on our experience with projects of similar magnitude and soil conditions, we recommend that a

subgrade CBR value of 4 be used for the design of new flexible pavements, and a modulus of subgrade

reaction of 125 pci be used for the design of rigid pavements, provided the new fill is placed in

accordance with our recommendations.

The architect/engineer should select the pavement section most appropriate to the development based on

available traffic data and anticipated traffic loads. Pavements should be constructed in accordance with all

applicable specifications of the Asphalt Institute and the Georgia Department of Transportation:

Pavements sub-base (Graded Aggregate Base) should conform to Section 815 of the State of Georgia

Department of Transportation Specifications for Road and Bridge Construction. The sub-base should

be compacted to 100% of the maximum dry density for crushed stone as determined by the modified

moisture-density relationship test (ASTM D 1557C). Additionally, proofrolling of the finished

sub-base should be performed prior to paving in order to detect any soft spots or excessive rutting

which may require stabilization.

Pavements should be provided with the facilities for surface and subsurface drainage. Standing water on

the pavement surface eventually may seep into the base course layer and soften the pavement subgrade

which leads to premature deterioration of the pavement. In areas where landscape areas slope toward the

pavement, a perimeter drain along the back of the curb intercepting migration of surface water should be

provided to minimize seepage under the pavement.

7.6 Foundations

The data obtained from the soil borings indicate that the proposed building may be supported on shallow

foundations. These foundations should be situated below the surficial topsoil layer, in residual soil or at

newly constructed fill, in order to avoid differential settlements. We recommend a maximum net



11

allowable soil bearing pressure not to exceed 3,000 pounds per square foot (psf) for design of

foundations constructed on the residual soil or newly structural fill. The encountered existing fill should

be adequate to provide the recommended bearing capacity. However, because of the heterogeneity of

man-made fill, any fill areas should be evaluated and tested carefully during construction. A

recommended foundation inspection criterion is provided in Section 8.2 of this report. The net allowable

soil bearing pressure refers to that pressure which may be transmitted to the foundation soils in excess

of the final minimum surrounding overburden pressure. We recommend that all continuous footings

have a minimum width of 2 feet, and should be a minimum 18 inches below subgrade elevations to

prevent shear failure and to minimize the effects of frost.

Total settlement of footing foundations situated in the recommended bearing strata described above

will depend on the magnitude of load and size of footing. For lightly to moderately loaded structures

such as one and two-story buildings, settlement is estimated to be on the order of 1 inch or less. Based

on the subsurface conditions, and our laboratory evaluation, we do not anticipate differential settlements

to exceed 1/2 inches between column supports (assuming 50 foot spacing), provided that all foundations

bear within the recommended residual soils and/or newly constructed fill.

7.7 Slopes and Vertical Cuts

A common practice in this region has been to limit slopes to 2.0(H) to 1.0(V) or flatter. The soil

conditions at this site may tolerate a maximum temporary slope of 1.0(H) to 1.0(V). The soils in this area

may contain fissures, foliation planes and other discontinuities that could cause sloughing or possibly a

slope failure, even on relatively flat slopes. Therefore, the excavation for the slopes should be monitored

by a geotechnical engineer to ensure that soil conditions are similar to those we have encountered.

Potential planes of weakness will be more visible at depth as the excavation proceeds. If weak conditions

are evident, the engineer can then recommend any necessary remedial actions.

Vertical cuts that exceed 5 feet should be braced or shored as required by OSHA regulations for safety.

Additionally, stairways, ladders, ramps or other means of safe access should be made available for any

trenches deeper than 4 feet. If any excavation, including a utility trench, is extended to a depth of more

than 20 feet, it will be necessary to have the slopes designed by a professional engineer.

7.8 Retaining Walls and Lateral Earth Pressures

The design of any retaining wall is based on the determination of the lateral earth pressures that will act on

the wall. These pressures are a function of the retained soils properties, and the structural design of the



12

wall. Three common conditions are considered to exist behind a retaining wall depending on the wall’s

structural design; namely Active, At-Rest, and Passive earth pressure conditions. Active earth pressures

are mobilized when a relatively flexible retaining structure such as a free standing wall is designed

allowing for slight movement or deflection. At-rest conditions apply to restrained retaining wall design

such as basement or tunnel walls. The passive state represents the maximum possible pressure when a

structure is pushed against the soil, and is used in wall design to help resist at-rest or active pressures.

Since significant movement has to occur before the passive earth pressure is mobilized, the total

calculated passive pressure should be reduced by one-half to two-thirds for design purposes.

Based on our experience, wall movement (known as tilt), that is necessary for earth pressures to

mobilize, range from 0.01H to 0.02H for the Active state and 0.02H to 0.04H for the Passive state. It

is assumed that the ground surfaces behind retaining walls will be constructed relatively level and that

residual soils like those encountered in our borings will be used for wall backfill. Based on our

experience with similar soils and laboratory test data, we recommend that an effective angle of

internal friction (’) = 30º and a cohesion c = 200 psf be used as design strength parameters for the

silty soils encountered on the site. These strength parameters result in the following earth pressures

coefficients and equivalent fluid pressure per foot of depth for compacted fill (based on a total (wet)

unit weight (w) of 120 pcf). A coefficient of friction of 0.40 could be used between the wall

foundations and the underlying soil. When calculating the resistance to sliding, we recommend using

a factor of safety of 1.5.

Table 2

Earth Pressure Condition

Coefficient Recommended Equivalent Earth Pressure (pcf)(1)

Active (Ka) 0.35 42.0

At-Rest (Ko) 0.5 60.0

Passive(2) (Kp) 3.0 --

(1) Assumes a constantly functional drainage system (2) Because significant wall movements are required to develop the passive pressure, the design passive pressure should be taken as

one-half to two-thirds of the total calculated passive pressure.

Backfill against the walls should be done carefully to minimize the horizontal load on the wall. Heavy

equipment should not be used to compact the soil within 10 feet of the walls. The use of hand-tampers



13

should be sufficient to obtain the required density when working the 10-foot zone adjacent to the wall.

Recommended structural fill specifications and procedures are provided in Section 8.1 of this report.

These retaining wall/below grade wall recommendations should not be correlated with soil parameters for

use in Mechanically Stabilized Earth (MSE) wall design. We recommend that soil parameters for any

MSE retaining wall design be established through appropriate laboratory testing by the wall designer.

7.9 Seismic Site Classification (IBC 2012)

Matrix conducted an analysis, utilizing the Multi-Channel Analysis of Surface Waves (MASW)

technique, to determine the Seismic Site Classification for the proposed site. The Probabilistic Ground

Motion values were retrieved for a central location within the project site, utilizing the USGS Earthquake

Hazards Program, using latitude (N 33.69561) & longitude (W -84.30185). The following are the

Spectral Response Acceleration Parameters for a 2% probability in 50 years:

Ss: Short period (0.2 second), Spectral Response = 0.180

S1: 1-second period, Spectral Response = 0.089

The site classification was undertaken in general accordance with the International Building Code 2012

(IBC2012), Table 1613.3.2 and chapter 20 of ASCE 7 by relying on the shear wave velocity for the upper

100 ft of the subgrade.

A site-specific seismic evaluation was carried out by conducting surface velocity testing and

performing a Multi-Channel Analysis of Surface Waves (MASW) in order to determine the Seismic

Site Classification for the proposed project. Two (2) traverses were deployed; designated as line 1

and line 2, as shown on the attached Figure 1. MASW utilizes seismic energy of Rayleigh type

surface waves to calculate the shear wave velocity. For this method, the geophones (receivers)

remain stationary and data is collected with the source located off the end of the line of geophones.

Data is collected at multiple locations (i.e., offsets) in order to obtain the optimal survey settings that

would yield the most coherent data set. This data is then processed and inverted to calculate a 1-D

shear wave velocity profile.

A weighted average of the 1-D shear wave velocity profile can then be used to get an average shear

wave velocity down to the maximum depth of the 1-D shear wave velocity profile. For this survey,

the most coherent data set was obtained along Line 1 which was generally oriented in a North-South



14

direction. A proprietary pressure-coupled land streamer was deployed with Geophones spaced 5 ft

apart and the source position was located 60 ft off the northern end of the transect. The source

consisted of a 20 pound hammer striking a steel plate. The surface along which the land streamer was

deployed was grass. The data was collected using a 24-channel Geode seismograph, manufactured by

Geometrics, Inc., with 4.5 Hz geophones.

The data was processed using the KGS SurfSeis 3 software package, developed by Kansas Geologic

Survey. This software is used to process and invert the surface wave data, and produces a 1-D shear

wave velocity model, presented below.



15

The analysis yielded an average shear wave velocity (for the upper 100 ft) Vs100 at 1755 ft/sec. This

value corresponded to a Seismic Site Class ‘C’. A Site Class C correlates to the following site

coefficients adjusted for site class, based on Tables 1613.3.3(1) and 1613.3.3(2) of IBC 2012:

Fa = 1.2

Fv = 1.7

The maximum considered earthquake spectral response accelerations for short periods and at

1-second periods follow:

SMS = 0.216 Equation (16-37, IBC2012)

SM1 = 0.151 Equation (16-38, IBC2012)

This translates to the following Design Spectral Response Acceleration Parameters:

SDS = 0.144 Equation (16-39, IBC2012)

SD1 = 0.100 Equation (16-40, IBC2012)

8.0 CONSTRUCTION RECOMMENDATIONS

8.1 Structural Fill

Staged, methodical and well planned grading is key to avoiding unnecessary costs and time delays. Areas

should not be stripped or disturbed if the grading contractor is unable to properly seal the subgrade prior

to departure each day. Exposure of soils to moisture from direct rainfall or runoff usually renders these

soils un-usable for several days. This usually gets mischaracterized as an unsuitable soils condition which

is inaccurate. Unsuitable soils are defined as those containing deleterious matter (such as organics,

alluvium, debris and/or trash). Moisture problems should be avoided by employing best management

practices that involve maintaining positive drainage, placing berms, diversion channels, and/or sealing the

subgrade to avoid water infiltration. Other measures involve covering all stockpiled soils with heavy tarps

or plastic to avoid saturating the soils in the event of rainfall. Means and methods of construction are

certainly the contractor’s jurisdiction; however, exposing otherwise suitable soils to excessive moisture or

softening of existing subgrades as a result of unscrupulous construction traffic should be avoided and

planned for.

We recommend that the following criteria be used for structural fill:

1. Adequate laboratory proctor density tests should be performed on representative samples of the

proposed fill materials to provide data necessary for the quality control. The moisture content at the



16

time of compaction should be within 3 percentage points of the optimum moisture content. In

addition, we recommend that the fill soils be free of organics and relatively non-plastic with plasticity

indices less than 20.

2. Suitable fill material should be placed in thin lifts (lift thickness depends on type of equipment used,

but generally lifts of 8 inches loose measurements are recommended). The soils should be compacted

by mechanical means such as sheepsfoot rollers. When placing fill adjacent to an existing sloped

grade, proper benching into the existing slope should be employed.

3. Any proposed slopes should incorporate only suitable fill, clean of organics or any other vegetative

content. Topsoil should only be used to provide a cover over the completed slope so as to promote

vegetative growth which in turn protects the slope’s surface against scour and erosion. Slopes should

be overbuilt and cut back to the proposed grades, exposing the firm compacted inner core. The

amount of overbuilding would vary depending on the site conditions, types of soils used and degree

of compaction achieved.

4. We recommend that the fill be compacted to a minimum of 95% of the Standard Proctor Maximum

Dry Density (ASTM Specifications D 698). The top 2 feet under pavements or structural areas should

be compacted to a minimum of 98% of the Standard Proctor Test.

5. An experienced soil engineering inspector should take adequate density tests throughout the fill

placement operation to ensure that the specified compaction is being achieved.

8.2 Construction Inspection and Testing

During construction, it is advisable that Matrix Engineering Group inspect the site preparation and

foundation construction work in order to ensure that our recommended procedures are followed. The

placement of any compacted fill should be inspected and tested. The utilization of acceptable on-site

borrow materials, as well as adequate off-site selected fill must be verified.

Each footing excavation should be inspected by Matrix Engineering Group, Inc. in order to verify the

availability of the required bearing pressure and to determine any special procedures required. At a

minimum, Hand Auger and Dynamic Cone Penetrometer testing in accordance with ASTM STP 399

should be performed every 50 feet for wall footing or as directed by the geotechnical engineer.

APPENDIX

Figure 1: Approximate Test Boring and MASW Locations

Figure 2: Contoured Depths to Auger Refusal or PWR

Correlation of Standard Penetration Resistance with Relative Compactness and Consistency

Boring Logs and Cutlines

Laboratory Test Results

USGS Design Maps Reports

CLIENT

DRAWN

CGLSREVIEWED DATE PROJECT NUMBER FIGURE

AT 12/27/2013 1

Approximate Test Boring Locations Plan Clifton Elementary School Replacement

Atlanta, Georgia

DeKalb County Board of Education

TITLE

MEG 301434

B7B9

B4

B6B5

B2B3

B8

B1

B12B10B11 B13

Soil Boring Cutline

C

B

C

A

B

A

Approximate Boring Locations

MASW Alignment

Line 1

Line 2

CLIENT

DRAWN

MEGREVIEWED DATE PROJECT NUMBER FIGURE

AT 12/27/2013 2

Contoured Depths to Auger Refusal or PWR Clifton Elementary School Replacement

Atlanta, Georgia

DeKalb County Board of Education

TITLE

MEG 301434

B7B9

B4

B6

B5

B2 B3

B8

B1

B12B10B11B13

THIS FIGURE SHOWS INTERPOLATED DEPTHS OF PARTIALLY WEATHERED ROCK (PWR) AND/OR MECHANICAL AUGER REFUSAL, WHICHEVER WAS ENCOUNTERED FIRST. MAXIMUM DRILLED DEPTHS WERE 20 FT. THEREFORE, ANY CONTOURS DEEPER THAN 20 FT ARE ESTIMATES BASED ON EXPECTED DEPTHS TO PWR,

ESPECIALLY AT BORING B3 THAT DID NOT ENCOUNTER SUCH WITHIN ITS DRILLED DEPTH.

DEPTH TO AR/PWR (FT)

NO. OF BLOWS, N RELATIVE COMPACTNESS

0 - 4 Very Loose

5 - 10 Loose

11 - 30 Medium Dense

31 - 50 Dense

Over 50 Very Dense

NO. OF BLOWS, N RELATIVE COMPACTNESS

0 - 1 Very Soft

2 - 4 Soft

5 - 8 Firm

9 - 15 Stiff

16 - 30 Very Stiff

31 - 50 Hard

Over 50 Very Hard

Water Table Level after 24 Hours

Water Table Level at the Time of Drilling

Standard Penetration Test

Dynamic Cone Pentrometer Test (ASTM STP399)

50/2" Number of Blows (50) to Drive the Spoon a Number of Inches (2")

DRILLING SYMBOLS

DRILLING PROCEDURES

CORRELATION OF STANDARD PENETRATION RESISTANCEWITH RELATIVE COMPACTNESS AND CONSISTENCY

SAND & GRAVEL

SILT & CLAY

SOIL SAMPLING AND STANDARD PENETRATION TESTING ARE PERFORMED IN ACCORDANCE WITH ASTMD1586-84 (RE-APPROVED IN 1992). THE STANDARD PENETRATION RESISTANCE (N) REPRESENTS THENUMBER OF BLOWS OF A 140-LB HAMMER FALLING 30 INCHES ON A 2.0 INCH O.D. 1.4 INCH I.D. SPLIT SPOONSAMPLER TO DRIVE IT ONE FOOT. THE SAMPLES OBTAINED FROM THE SPLIT SPOON SAMPLER ARECLASSIFIED IN THE FIELD IN ACCORDANCE WITH ASTM D2488-93 (VISUAL MANUAL PROCEDURE FORDESCRIPTION OF SOILS).

W.H. Weight of Hammer (0 blows/ft)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Grass with topsoil layerPartially Weathered Rock, sampled as Gray, Coarse to FineSilty SAND

No sample recovered. Split-spoon was unable to penetratethe PWR.Auger refusal at 4 feet BGS

PWR50/6"

50/0"

DRILL HOLE LOGPROJECT: Clifton Elementary School Replacement PROJECT NO.: MEG301434

CLIENT: DeKalb County Board of Education - Operations DATE: 12/18/13

BORING NO. B1

LOCATION: Refer to Figure 1 ELEVATION:

DRILLER: Kilman Brothers LOGGED BY: Talha Tayyab

DRILLING METHOD: ASTM D1586 STATION:

File: Boring Logs Date Printed: 12/30/2013DEPTH TO - WATER> INITIAL: None AFTER 24 Hours: None CAVING>

EL

EV

AT

ION

(fe

et)

DE

PT

H(f

ee

t)

Description

SO

IL T

YP

E

SO

ILS

YM

BO

L

SA

MP

LE

RS

TEST RESULTS

10 20 30 40 50Penetration -

Natural Moisture Content (%).

N-ValueBlows/ft

(ASTM D1586)

This information pertains only to this boring and should not be interpreted as being indicitive of the site.

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Asphalt pavementGraded Aggregate Base (GAB)Fill - Medium Dense, Reddish Brown, Silty SAND

Possible Fill - Medium Dense, Reddish Brown, Silty SAND

Residual - Medium Dense, Tannish Gray, Micaceous, SiltySAND with weathered rock fragments

Soil color changes to olive gray

Partially Weathered Rock, sampled as Gray, Silty Coarse toFine SANDAuger refusal at 19.5 feet BGS

GW-SWFILL

FILL

SM

PWR

13

11

22

19

50/5"



BORING NO. B2





EL

EV

AT

ION

(fe

et)

DE

PT

H(f

ee

t)

Description

SO

IL T

YP

E

SO

ILS

YM

BO

L

SA

MP

LE

RS

TEST RESULTS



N-ValueBlows/ft

(ASTM D1586)


0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Asphalt pavementGraded Aggregate Base (GAB)Residual - Medium Dense, Orange-Brown, Micaceous, SiltySAND with MnO staining

Loose, Orange-Brown, Micaceous, Clayey SAND with MnOstaining

Medium Dense, Gray with Pink & Brown streaks, Silty SANDwith weathered rock fragments

Dense changing to Medium Dense, Tannish Gray, Silty SAND

Boring terminated at 20 feet BGS

GW-SWSM

SC

SM

SM

11

9

18

33

27



BORING NO. B3





EL

EV

AT

ION

(fe

et)

DE

PT

H(f

ee

t)

Description

SO

IL T

YP

E

SO

ILS

YM

BO

L

SA

MP

LE

RS

TEST RESULTS



N-ValueBlows/ft

(ASTM D1586)


0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Grass with topsoil layerFill - Firm, Reddish Brown, Silty CLAY

Residual - Medium Dense, Reddish Brown with Pink & Graystreaks, Silty SAND

Partially Weathered Rock, sampled as Tannish Gray, SiltyCoarse to Fine SANDAuger refusal encountered at 9.5 feet BGS

FILL

SM

PWR

6

16

50/4"



BORING NO. B4





EL

EV

AT

ION

(fe

et)

DE

PT

H(f

ee

t)

Description

SO

IL T

YP

E

SO

ILS

YM

BO

L

SA

MP

LE

RS

TEST RESULTS



N-ValueBlows/ft

(ASTM D1586)


0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Grass with topsoil layerFill - Medium Dense, Reddish Brown, Silty SAND

Residual - Firm, Reddish Brown, Silty CLAY

Firm, Gray-Brown, Sandy SILT

Partially Weathered Rock, sampled as Orange-Gray, SiltyCoarse to Fine SANDAuger refusal at 19.5 feet BGS

FILL

CL

ML

PWR

23

12

6

6

50/5"



BORING NO. B5





EL

EV

AT

ION

(fe

et)

DE

PT

H(f

ee

t)

Description

SO

IL T

YP

E

SO

ILS

YM

BO

L

SA

MP

LE

RS

TEST RESULTS



N-ValueBlows/ft

(ASTM D1586)


0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Grass with topsoil layerFill - Firm, Reddish Brown, Silty CLAY

Residual - Medium Dense, Reddish Brown with Pink & Orangestreaks, Silty SAND

Partially Weathered Rock, sampled as Tannish Gray, SiltyCoarse to Fine SANDAuger refusal encountered at 9.5 feet BGS

FILL

SM

PWR

8

17

50/5"



BORING NO. B6





An offset boring was performed approximately 10 feet from the initial boring location. Auger refusal was encountered at 8.5 feetBGS at the offset boring location.

EL

EV

AT

ION

(fe

et)

DE

PT

H(f

ee

t)

Description

SO

IL T

YP

E

SO

ILS

YM

BO

L

SA

MP

LE

RS

TEST RESULTS



N-ValueBlows/ft

(ASTM D1586)


0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Grass with topsoil layerFill - Medium Dense, Reddish Brown, Micaceous, Silty SAND

Soil color changes to orange-brown

Residual - Dense, Reddish Orange, Micaceous, Silty SANDwith weathered rock fragments

Auger refusal at 12 feet BGS

FILL

SM

13

12

31

50/0"



BORING NO. B7





EL

EV

AT

ION

(fe

et)

DE

PT

H(f

ee

t)

Description

SO

IL T

YP

E

SO

ILS

YM

BO

L

SA

MP

LE

RS

TEST RESULTS



N-ValueBlows/ft

(ASTM D1586)


0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Grass with topsoil layerFill - Reddish Brown, Micaceous, Silty SAND


Residual - Reddish Orange, Micaceous, Silty SAND withweathered rock fragments

Firm changing to Very Soft, Orange-Brown, Sandy SILT withMnO staining


FILL

SM

ML 8

2



BORING NO. B7-A





Auger refusal was encountered at 12 feet BGS at the initial boring location (B7). This boring log represents the offset boring whichwas performed approximately 10 feet from the initial boring location. Sampling was performed at the offset boring beginning at13.5 feet BGS.

EL

EV

AT

ION

(fe

et)

DE

PT

H(f

ee

t)

Description

SO

IL T

YP

E

SO

ILS

YM

BO

L

SA

MP

LE

RS

TEST RESULTS



N-ValueBlows/ft

(ASTM D1586)


0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Grass with topsoil layerPossible Fill - Loose, Reddish Brown, Micaceous, Silty SAND

Residual - Medium Dense, Reddish Brown, Micaceous, SiltySAND with weathered rock fragments

Partially Weathered Rock, sampled as Reddish Orange, SiltyCoarse to Fine SAND

Loose changing to Medium Dense, Orange-Brown, SiltySAND with MnO staining


FILL

SM

PWR

SM

6

14

50/5"

10

11



BORING NO. B8





EL

EV

AT

ION

(fe

et)

DE

PT

H(f

ee

t)

Description

SO

IL T

YP

E

SO

ILS

YM

BO

L

SA

MP

LE

RS

TEST RESULTS



N-ValueBlows/ft

(ASTM D1586)


0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Grass with topsoil layerResidual - Medium Dense, Orange-Brown, Micaceous, SiltySAND with weathered rock fragments

Partially Weathered Rock, sampled as Orange-Gray, SiltyCoarse to Fine SAND


SM

PWR

14

50/6"



BORING NO. B9





EL

EV

AT

ION

(fe

et)

DE

PT

H(f

ee

t)

Description

SO

IL T

YP

E

SO

ILS

YM

BO

L

SA

MP

LE

RS

TEST RESULTS



N-ValueBlows/ft

(ASTM D1586)


0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Grass with topsoil layerResidual - Orange-Brown, Micaceous, Silty SAND

Residual - Very Dense changing to Medium Dense, TannishGray, Micaceous, Silty SAND

Partially Weathered Rock, sampled as Tannish Gray, Coarseto Fine SAND


SM

SM

PWR

51

19

50/3"



BORING NO. B9-A




File: Boring Logs Date Printed: 12/30/2013DEPTH TO - WATER> INITIAL: None AFTER 24 Hours: 19.5 ft CAVING>

Auger refusal was encountered at 5 feet BGS at the initial boring location (B9). This boring log represents the offset boring whichwas performed approximately 10 feet from the initial boring location. Sampling was performed at the offset boring beginning at 8.5feet BGS.

EL

EV

AT

ION

(fe

et)

DE

PT

H(f

ee

t)

Description

SO

IL T

YP

E

SO

ILS

YM

BO

L

SA

MP

LE

RS

TEST RESULTS



N-ValueBlows/ft

(ASTM D1586)


0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Grass with topsoil layerPartially Weathered Rock, sampled as Gray, Coarse to FineSilty SANDAuger refusal at 2 feet BGS

PWR50/3"



BORING NO. B10





Due to shallow auger refusal at the initial boring location (B10), three additional offset borings were performed in the near theinitial boring location. Auger refusal was encountered at each of the boring locations ranging from 1-2 feet BGS.

EL

EV

AT

ION

(fe

et)

DE

PT

H(f

ee

t)

Description

SO

IL T

YP

E

SO

ILS

YM

BO

L

SA

MP

LE

RS

TEST RESULTS



N-ValueBlows/ft

(ASTM D1586)


0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Grass with topsoil layerResidual - Loose changing to Medium Dense, Olive Gray, SiltySAND with weathered rock fragments



SM9

12



BORING NO. B11





Due to shallow auger refusal at the initial boring location (B11), an offset boring was performed in the near the initial boringlocation. Auger refusal was encountered at the offset boring at 2.5 feet BGS.

EL

EV

AT

ION

(fe

et)

DE

PT

H(f

ee

t)

Description

SO

IL T

YP

E

SO

ILS

YM

BO

L

SA

MP

LE

RS

TEST RESULTS



N-ValueBlows/ft

(ASTM D1586)


0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Grass with topsoil layerPossible Fill - Loose, Reddish Brown, Micaceous, Silty SAND

Residual - Medium Dense changing to Loose, Reddish Brown,Micaceous, Silty SAND

Medium Dense, Yellowish Orange, Micaceous, Silty SAND

Auger refusal at 17.5 feet BGS

FILL

SM

SM

7

12

8

24

50/0"



BORING NO. B12





EL

EV

AT

ION

(fe

et)

DE

PT

H(f

ee

t)

Description

SO

IL T

YP

E

SO

ILS

YM

BO

L

SA

MP

LE

RS

TEST RESULTS



N-ValueBlows/ft

(ASTM D1586)


0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

Grass with topsoil layerPossible Fill - Loose, Red, Micaceous, Silty SAND

Residual - Medium Dense, Tannish Gray, Micaceous, SiltySAND with weathered rock fragments

Partially Weathered Rock, sampled as Tannish Gray, SiltyCoarse to Fine SAND


FILL

SM

PWR

8

13

50/1"



BORING NO. B13





EL

EV

AT

ION

(fe

et)

DE

PT

H(f

ee

t)

Description

SO

IL T

YP

E

SO

ILS

YM

BO

L

SA

MP

LE

RS

TEST RESULTS



N-ValueBlows/ft

(ASTM D1586)


B8

B9

B13

B13

8

13

50/1"

B9

14

50/6"

B8

6

14

50/5"

10

11

0

5

10

15

20

25

Dep

th i

n F

eet

0

5

10

15

20

25

Dep

th in

Feet

Plan View Topsoil

Fill

Silty sand

Partially Weathered Rock

MATRIX ENGINEERING GROUP, INC.GENERALIZED SOIL PROFILE

HORIZONTAL DRAWN BY/APPROVED BY

ET/AT

DATE DRAWNSCALE:VERTICAL 12/30/2013SCALE: 1"=5'

Clifton Elementary School Replacement

PROJECT NO. MEG301434FIGURE NUMBER

A-A

B6

B7

B12

B12

7

12

8

24

50/0"

B7-A

8

2

B7

13

12

31

50/0"

B6

8

17

50/5"

0

5

10

15

20

25

Dep

th i

n F

eet

0

5

10

15

20

25

Dep

th in

Feet

Plan View Topsoil

Fill

Silty sand

Silt




ET/AT




B-B

B5

B6

B10

B10

50/3"

B6

8

17

50/5"

B5

23

12

6

6

50/5"

0

5

10

15

20

25

Dep

th i

n F

eet

0

5

10

15

20

25

Dep

th in

Feet

Plan View Topsoil


Fill

Silty sand

Low plasticityclay

Silt



ET/AT




C-C

Boring Number

Sample Depth(ft BGS)

Natural Moisture Content (%)¹

Soil Classification

B3 3.5-5 8.0 SM

B4 3.5-5 19.1 SM

B5 8.5-10 30.6 CL

B6 3.5-5 27.3 SM

B7 8.5-10 11.2 SM

B8 8.5-10 31.8 SM

B9 3.5-5 8.9 SM

B10 0-1.5 14.4 SM

B12 8.5-10 31.1 SM

B13 3.5-5 20.7 SM

¹ As determined in general accordance with ASTM D2216

Laboratory Test Results

12/27/13 Design Maps Detailed Report

geohazards.usgs.gov/designmaps/us/report.php?template=minimal&latitude=33.695608&longitude=-84.30185&siteclass=2&riskcategory=0&edition=ibc-2012&… 1/4

From Figure 1613.3.1(1) [1]

From Figure 1613.3.1(2) [2]

Design Maps Detailed Report

2012 International Building Code (33.69561°N, 84.30185°W)

Site Class C – “Very Dense Soil and Soft Rock”, Risk Category I/II/III

Section 1613.3.1 — Mapped acceleration parameters

Note: Ground motion values provided below are for the direction of maximum

horizontal spectral response acceleration. They have been converted from

corresponding geometric mean ground motions computed by the USGS by applying

factors of 1.1 (to obtain SS) and 1.3 (to obtain S1). Maps in the 2012 International

Building Code are provided for Site Class B. Adjustments for other Site Classes are

made, as needed, in Section 1613.3.3.

SS = 0.180 g

S1 = 0.089 g

Section 1613.3.2 — Site class definitions

The authority having jurisdiction (not the USGS), site-specific geotechnical data, and/or

the default has classified the site as Site Class C, based on the site soil properties in

accordance with Section 1613.

2010 ASCE-7 Standard – Table 20.3-1

SITE CLASS DEFINITIONS

Site Class vS N or Nch su

A. Hard Rock >5,000 ft/s N/A N/A

B. Rock 2,500 to 5,000 ft/s N/A N/A

C. Very dense soil and soft rock 1,200 to 2,500 ft/s >50 >2,000 psf

D. Stiff Soil 600 to 1,200 ft/s 15 to 50 1,000 to 2,000 psf

E. Soft clay soil <600 ft/s <15 <1,000 psf

Any profile with more than 10 ft of soil having the

characteristics:

Plasticity index PI > 20,

Moisture content w ≥ 40%, and

Undrained shear strength su < 500 psf

F. Soils requiring site response

analysis in accordance with Section

21.1

See Section 20.3.1

For SI: 1ft/s = 0.3048 m/s 1lb/ft² = 0.0479 kN/m²

http://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/IBC-2012-Fig1613p3p1(1).pdf

http://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/IBC-2012-Fig1613p3p1(2).pdf

http://www.usgs.gov/



Section 1613.3.3 — Site coefficients and adjusted maximum considered earthquake spectral

response acceleration parameters

TABLE 1613.3.3(1)

VALUES OF SITE COEFFICIENT Fa

Site Class Mapped Spectral Response Acceleration at Short Period

SS ≤ 0.25 SS = 0.50 SS = 0.75 SS = 1.00 SS ≥ 1.25

A 0.8 0.8 0.8 0.8 0.8

B 1.0 1.0 1.0 1.0 1.0

C 1.2 1.2 1.1 1.0 1.0

D 1.6 1.4 1.2 1.1 1.0

E 2.5 1.7 1.2 0.9 0.9

F See Section 11.4.7 of ASCE 7

Note: Use straight–line interpolation for intermediate values of SS

For Site Class = C and SS = 0.180 g, Fa = 1.200

TABLE 1613.3.3(2)

VALUES OF SITE COEFFICIENT Fv

Site Class Mapped Spectral Response Acceleration at 1–s Period

S1 ≤ 0.10 S1 = 0.20 S1 = 0.30 S1 = 0.40 S1 ≥ 0.50

A 0.8 0.8 0.8 0.8 0.8

B 1.0 1.0 1.0 1.0 1.0

C 1.7 1.6 1.5 1.4 1.3

D 2.4 2.0 1.8 1.6 1.5

E 3.5 3.2 2.8 2.4 2.4

F See Section 11.4.7 of ASCE 7

Note: Use straight–line interpolation for intermediate values of S1

For Site Class = C and S1 = 0.089 g, Fv = 1.700



Equation (16-37):

Equation (16-38):

Equation (16-39):

Equation (16-40):

SMS = FaSS = 1.200 x 0.180 = 0.216 g

SM1 = FvS1 = 1.700 x 0.089 = 0.151 g

Section 1613.3.4 — Design spectral response acceleration parameters

SDS = ⅔ SMS = ⅔ x 0.216 = 0.144 g

SD1 = ⅔ SM1 = ⅔ x 0.151 = 0.100 g



Section 1613.3.5 — Determination of seismic design category

TABLE 1613.3.5(1)

SEISMIC DESIGN CATEGORY BASED ON SHORT-PERIOD (0.2 second) RESPONSE

ACCELERATION

VALUE OF SDS

RISK CATEGORY

I or II III IV

SDS < 0.167g A A A

0.167g ≤ SDS < 0.33g B B C

0.33g ≤ SDS < 0.50g C C D

0.50g ≤ SDS D D D

For Risk Category = I and SDS = 0.144 g, Seismic Design Category = A

TABLE 1613.3.5(2)

SEISMIC DESIGN CATEGORY BASED ON 1-SECOND PERIOD RESPONSE ACCELERATION

VALUE OF SD1

RISK CATEGORY

I or II III IV

SD1 < 0.067g A A A

0.067g ≤ SD1 < 0.133g B B C

0.133g ≤ SD1 < 0.20g C C D

0.20g ≤ SD1 D D D

For Risk Category = I and SD1

= 0.100 g, Seismic Design Category = B

Note: When S1 is greater than or equal to 0.75g, the Seismic Design Category is E for

buildings in Risk Categories I, II, and III, and F for those in Risk Category IV,

irrespective of the above.

Seismic Design Category ≡ “the more severe design category in accordance with

Table 1613.3.5(1) or 1613.3.5(2)” = B

Note: See Section 1613.3.5.1 for alternative approaches to calculating Seismic Design

Category.

References

1. Figure 1613.3.1(1): http://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/IBC-2012-

Fig1613p3p1(1).pdf

2. Figure 1613.3.1(2): http://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/IBC-2012-

Fig1613p3p1(2).pdf

SUBSURFACE EXPLORATION AND GEOTECHNICAL …€¦ · Matrix Engineering Group, Inc. (Matrix) has...

Documents

Transcript of SUBSURFACE EXPLORATION AND GEOTECHNICAL …€¦ · Matrix Engineering Group, Inc. (Matrix) has...