report of subsurface exploration and geotechnical

Corporate HQ: 3015 Dumbarton Road Richmond, Virginia 23228 T 804.264.2701 F 804.264.1202 www.fandr.com

VIRGINIA • NORTH CAROLINA • SOUTH CAROLINA • MARYLAND • DISTRICT OF COLUMBIA

A Minority-Owned Business

Report of Subsurface Exploration and

Geotechnical Engineering Evaluation

Bradford Circle Pavement Design Durham, North Carolina

F&R Project No. 66V-0293

Prepared For: RK&K

900 Ridgefield Drive, Suite 350 Raleigh, North Carolina 27609

Prepared By: Froehling & Robertson, Inc.

310 Hubert Street Raleigh, North Carolina 27603

August 23, 2018

TABLE OF CONTENTS

SECTION PAGE

1.0 PURPOSE & SCOPE OF SERVICES ..............................................................................................1

2.0 PROJECT INFORMATION ..........................................................................................................1

3.0 EXPLORATION PROCEDURES ...................................................................................................2

3.1 SUBSURFACE EXPLORATION .......................................................................................................2 3.2 SHWT AND FIELD INFILTRATION TESTING ......................................................................................3 3.3 GEOTECHNICAL LABORATORY TESTING ..........................................................................................3

4.0 REGIONAL GEOLOGY & SUBSURFACE CONDITIONS ..................................................................4

4.1 REGIONAL GEOLOGY ................................................................................................................4 4.2 SUBSURFACE CONDITIONS .........................................................................................................4 4.2.1 GENERAL ...........................................................................................................................4 4.2.2 SURFICIAL MATERIALS...........................................................................................................5 4.2.3 RESIDUAL MATERIALS ...........................................................................................................5 4.3 SOIL MOISTURE AND GROUNDWATER CONDITIONS .........................................................................6

5.0 SHWT & INFILTRATION TESTING RESULTS ................................................................................6

6.0 GEOTECHNICAL LABORATORY TESTING RESULTS ......................................................................7

7.0 GEOTECHNICAL RECOMMENDATIONS .....................................................................................8

7.1 GENERAL ...............................................................................................................................8 7.2 PERVIOUS CONCRETE PAVEMENT DESIGN ......................................................................................8 7.3 POROUS ASPHALT PAVEMENT DESIGN ........................................................................................ 10 7.4 SITE DEVELOPMENT AND EARTHWORK ....................................................................................... 11 7.5 TEMPORARY EXCAVATION RECOMMENDATIONS ........................................................................... 12

8.0 CONTINUATION OF SERVICES ................................................................................................ 13

9.0 LIMITATIONS ........................................................................................................................ 14

APPENDICES

APPENDIX I Field Testing Plan, Figure No. 1

Subsurface Profile, Figure No. 2

APPENDIX II Key to Soil Classification & USCS Chart Boring Logs

APPENDIX III SHWT & Infiltration Testing Report

APPENDIX IV Geotechnical Laboratory Test Results

APPENDIX V GBA Document “Important Information about Your Geotechnical Engineering Report

RK&K Bradford Circle

F&R Project No. 66V-0293 August 23, 2018

1

1.0 PURPOSE & SCOPE OF SERVICES

The purpose of the subsurface exploration and geotechnical engineering evaluation was to

explore the subsurface conditions in the area of the proposed construction and provide

geotechnical engineering recommendations that can be used during the design and construction

phases of the project. Evaluation of hydrologic aspects of pervious pavement design was not

part of F&R’s scope of services. F&R’s scope of services included the following:

Completion of 3 soil test borings (B-1 to B-3) to depths ranging from 9.5 to 10 feet below the existing ground surface;

Preparation of typed Boring Logs and development of a Subsurface Profile;

Performing geotechnical laboratory testing on representative soil samples;

Performing seasonal high water table (SHWT) determinations and field infiltration testing at three locations (I-1 to I-3); and,

Performing a geotechnical engineering evaluation of the subsurface conditions with regard to their suitability for the proposed construction.

2.0 PROJECT INFORMATION

Bradford Circle is currently a gravel road that extends about 325 feet to the east from South

Alston Avenue in Durham, North Carolina. The road has 8 single-family residential homes and

terminates in a cul-de-sac at its east end (see Figure No. 1 in Appendix I). The existing road slopes

down from Alston Avenue to the east with a topographic relief of 12 feet for the first 250 feet of

the road. A cul-de-sac with a diameter of about 70 feet is situated at the east end of the road;

the cul-de-sac is relatively level with approximately 1 to 2 feet of topographic relief.

It is F&R’s understanding that the cul-de-sac and a short section of the road extending west from

the cul-de-sac is planned to be designed as a pervious pavement section. The remaining section

of the road will be a conventional asphalt pavement using a standard City of Durham pavement

section. Although a final grading plan is not available at this stage of the project, F&R was

informed by RK&K that the finished road grade in the areas of new pervious pavement will be

approximately 1-foot above existing road grade. The street does not have regular truck or bus

traffic, and the traffic consists of automobiles with occasional single-unit delivery truck and trash

truck traffic, and random heavy truck traffic (e.g., moving van).

RK&K Bradford Circle F&R Project No. 66V-0293 August 23, 2018

2

3.0 EXPLORATION PROCEDURES

3.1 Subsurface Exploration

F&R advanced a total of 3 soil test borings (B-1 to B-3) to depths ranging from 9.5 to 10 feet below

the existing ground surface. The approximate boring locations are shown on the Field Testing Plan

presented as Figure 1 in Appendix I. The test boring locations were established in the field by making

taped measurements from existing site features. Ground surface elevations at the boring locations

were interpolated from Durham County topographic data. Given these methods of determination,

the boring locations and ground surface elevations should only be considered approximate.

The test borings were advanced by a track-mounted drill rig using 2-1/4” inside diameter (I.D.)

hollow stem augers for borehole stabilization. Representative soil samples were obtained using

a standard two-inch outside diameter (O.D.) split-barrel sampler in general accordance with

ASTM D 1586, Penetration Test and Split-Barrel Sampling of Soils (Standard Penetration Test).

The number of blows required to drive the split barrel sampler three, consecutive 6-inch

increments with an automatic hammer is recorded, and the blows of the last two 6-inch

increments are added to obtain the Standard Penetration Test (SPT) N-values representing the

penetration resistance of the soil.

A representative portion of the soil was obtained from each SPT sample, sealed in an eight-ounce

glass jar, labeled, and transported to our laboratory for classification and analysis by a geotechnical

engineer. The soil samples were classified in general accordance with the Unified Soil Classification

System (USCS), using visual-manual identification procedures (ASTM D2488). The boring logs for

the exploration are presented in Appendix II.

Groundwater level measurements were attempted at the termination of drilling. Since the borings

were located in an active road, the boreholes were backfilled immediately after drilling. As such,

stabilized groundwater readings after a stabilization period of 24-hours were not obtained.


3

3.2 SHWT and Field Infiltration Testing

Seasonal high water table (SHWT) determinations and field infiltration testing were performed at

three locations (I-1 to I-3). The approximate test locations are shown on the Field Testing Plan

presented as Figure 1 in Appendix I. These services were performed by a North Carolina Licensed

Soil Scientist from Three Oaks Engineering under a subcontract agreement with F&R.

The infiltration testing was performed to assess infiltration rates of the subgrade soils using a

double-ring infiltrometer in general accordance with ASTM D 3385-09. At each test location, a pit

with plan dimensions of approximately 4 by 4 feet was mechanically excavated with a backhoe

through the gravel road surface and into subgrade soils to establish a level surface. The test

methodology then consisted of driving two open cylinders, one inside the other into the ground,

partially filling the rings with water and then maintaining the water at a constant level. The volume

of water added to the inner ring to maintain the water level constant is the measure of the volume

of water that infiltrates the soil. The volume of water infiltrated during timed intervals is converted

to an incremental infiltration velocity and is expressed in inches per hour. The results of the SHWT

determinations and infiltration testing are included in Appendix III.

3.3 Geotechnical Laboratory Testing

Bulk soil samples of the roadway subgrade soils were obtained from each infiltration testing location

for geotechnical laboratory testing. The laboratory testing consisted of the following:

Classification testing (Atterberg Limits, Grain Size Analysis and Natural Moisture Content);

Standard Proctor Compaction testing (ASTM D698);

Permeability testing on re-molded samples using a flexible-wall permeameter in general accordance with ASTM D 5084. Testing was at compaction levels of approximately 90, 93 and 95 percent of the maximum dry density as determined by the Standard Proctor testing. The purpose of this testing was to assess permeability/infiltration rates at different degrees of compaction to aid F&R in recommending the design subgrade compaction criteria.

California Bearing Ratio (CBR) testing on re-molded samples at the same different compaction rates used for the permeability testing (i.e., 90, 93 and 95 percent) to provide subgrade strength data.

The laboratory test results are presented in Appendix IV of this report.


4

4.0 REGIONAL GEOLOGY & SUBSURFACE CONDITIONS

4.1 Regional Geology

The project site is located within the Triassic Basin of the Piedmont Physiographic Province of North

Carolina. The Piedmont Province generally consists of hills and ridges that are intertwined with an

established system of draws and streams. The Triassic basin is filled with sedimentary rocks (e.g.,

Sandstone, Siltstone and Mudstone) that formed approximately 190-200 million years ago. The

basin was formed when differential movement occurred along the Jonesboro Fault in this area. The

differential movement resulted in a long, narrow, northeast-trending basin, which gradually filled

with sediments eroded from upland areas of the surrounding topography. The sediments are

thought to be several thousand feet deep and have resulted in sedimentary rock formations which

are frequently encountered within 10 to 20 feet of the ground surface. The sedimentary Triassic

Basin rock formations are commonly interspersed with Diabase dikes and sills that have intruded

the sedimentary formations.

The residual soils that overlie the weathered rock and bedrock in this area typically consist of silty

clays and sandy clays, which can be highly plastic, but become less plastic with increased depth.

These clayey soils typically transition into fine sandy silts and silty sands of increasing density to the

top of Partially Weathered Rock. This transitional zone termed “Partially Weathered Rock” is

typically found overlying the parent bedrock. Partially Weathered Rock (PWR) is defined, for

engineering purposes, as soil material exhibiting Standard Penetration Resistances in excess of 100

blows per foot (bpf). The profile of the PWR and hard rock is quite irregular and erratic, even over

short, horizontal distances.

4.2 Subsurface Conditions

4.2.1 General

The subsurface conditions discussed in the following paragraphs and those shown on the attached

Boring Logs in Appendix II represent an estimate of the subsurface conditions based on an

interpretation of the boring data from F&R using normally-accepted, geotechnical engineering


5

judgments. Although individual soil test borings are representative of the subsurface conditions at

the boring locations on the dates shown, they are not necessarily indicative of subsurface conditions

at other locations or at other times. A Subsurface Profile has been prepared from the boring data to

graphically illustrate the subsurface conditions encountered at the site. The Subsurface Profile is

presented as Figure No. 2 in Appendix I. Strata breaks designated on the boring logs and subsurface

profile represent approximate boundaries between soil types. The transition from one soil type to

another may be gradual or occur between soil samples. This section of the report provides a general

discussion of subsurface conditions encountered in F&R’s borings within areas of proposed

construction. More detailed descriptions of the subsurface conditions at the individual boring

locations are presented on the boring logs provided in Appendix II.

4.2.2 Surficial Materials

Gravel was encountered at the ground surface at each boring and infiltration test location. The

gravel appeared to consist of well graded quarried stone that had become somewhat

contaminated with soil materials. The gravel thickness varied considerably with thickness

increasing to the east. The approximate gravel thicknesses are presented in the following table:

LOCATION B-1 I-3 I-2 B-2 I-1 B-3

GRAVEL THICKNESS (IN.) 2 5 4 9 12 15

4.2.3 Residual Materials

Residual soils were encountered below the surficial gravel layer and consist of low plasticity fine

sandy silt, clayey silt and silty clay (USCS – CL, ML and CL/ML soils). The consistency of the soils

was very stiff to very hard with SPT N-values ranging from 19 to 63 blows per foot (bpf). Boring

B-2 was terminated in very hard residual soils. PWR was encountered in borings B-1 and B-3 at

depths of 9.5 and 7.5 feet, respectively. PWR is defined for engineering purposes as material

that exhibits an SPT N-value of at least 100 blows per foot (bpf). The SPT N-value in the PWR

exhibited 50 blows with 4” of split spoon penetration (50/4”) to 50/5.5”.


6

4.3 Soil Moisture and Groundwater Conditions

The moisture condition of the soil samples ranged from dry to moist. Wet soils were not

encountered in the borings. Groundwater was not encountered during or immediately after

drilling at which time the borings were backfilled because the road is currently being used.

It should be noted that soil moisture conditions and groundwater levels fluctuate depending

upon seasonal factors such as precipitation and temperature. As such, soil moisture and

groundwater conditions at other times may vary from those described in this report. Due to the

presence of relatively impervious soils, trapped or perched water conditions may be encountered

during periods of inclement weather and during seasonally wet periods.

5.0 SHWT & INFILTRATION TESTING RESULTS

The results of the SHWT determinations and field infiltration testing are presented in the

following table and in Appendix III.

Seasonal High Water Table Determinations (depth below ground surface)

Test Location SHWT Perched Water Table

I-1 None Observed (> 41 inches) 25 to 27 inches

I-2 None Observed (> 98 inches) 14 to 26 & 80 to 98 inches

I-3 None Observed (> 92 inches) 8 to 28 & 44 to 92 inches

Field Infiltration Testing

Test Location

Test Depth (inches)

Infiltration Rate

(in/hr) (cm/sec)

I-1 25 0.018 1.27 x 10-5

I-2 14 0.072 5.08 x 10-5

I-3 8 0.198 1.40 x 10-4

Evidence of a SHWT was not noted; however, perched water conditions were noted at various

depth intervals. The hand auger boring for the SHWT determination at I-1 was terminated at 41

inches due to auger refusal, but refusal was not encountered in I-2 and I-3. The infiltration testing

resulted in infiltration rates ranging an order of magnitude from 0.018 to 0.198 inches/hour.


7

6.0 GEOTECHNICAL LABORATORY TESTING RESULTS

The results of the geotechnical index testing are presented in Appendix IV, and a summary of

the permeability testing and CBR testing is presented in the following tables:

Test Location

LAB PERMEABILITY TESTING OF SUBGRADE SAMPLES

Permeability (cm/sec) at % of Standard Proctor Maximum Dry Density

90% 93% 95%

I-1 1.8 x 10-5 1.5 x 10-5 4.2 x 10-6

I-2 3.9 x 10-7 4.0 x 10-7 2.6 x 10-7

I-3 3.1 x 10-7 1.9 x 10-7 3.4 x 10-8

Test Location

LAB CBR TESTING OF SUBGRADE SAMPLES

Average CBR Value at 0.1” Penetration at % of Standard Proctor Maximum Dry Density

90% 93% 95%

I-1 1.8 3.4 3.2

I-2 0.9 2.5 2.1

I-3 0.7 2.3 2.7

The permeability testing indicates that the subgrade soils are relatively impermeable at all of the

different re-molded compaction rates, with the sample from I-1 being somewhat more

permeable that the samples from I-2 and I-3. These results are in the range of published values

for low plasticity silts and clays. As expected, the CBR results generally increased as the re-

molded compaction level increased. However, in general, the CBR results at 93% and 95% were

relatively close and in some cases the CBR value at 93% compaction exceeded the results for

samples remolded to 95% compaction. CBR results in the 2 to 3 range are consistent with CBR

testing that F&R has performed on Triassic silts and clay samples for many past projects.


8

7.0 GEOTECHNICAL RECOMMENDATIONS

7.1 General

The conclusions and recommendations contained in this section of the report are based upon the

results of 3 soil test borings, SHWT and infiltration testing, geotechnical laboratory testing results,

our experience with pavement design, and the information provided to us regarding the proposed

development. It is our opinion that the subsurface conditions encountered at the project site are

generally suitable for the proposed development, from a geotechnical perspective, provided the

recommendations presented in subsequent sections of this report are followed throughout the

design and construction phases of this project. Although infiltration and permeability rates for the

subgrade soil are relatively low, it is F&R’s understanding from RK&K that the site subsurface

conditions are suitable to support the pervious pavements systems from a hydrologic perspective.

This report provides geotechnical recommendations for both pervious concrete pavement and

porous asphalt pavement. For both types of pavement, it is very important that the paving

contractors have demonstrated prior successful experience constructing similar pervious/porous

pavements. F&R recommends that all contractors be pre-qualified, and F&R would like to be

included in this phase of the project. Similarly, for the pavement system to perform successfully, it

equally important that the contractor follow construction procedures that will be presented in this

report, the contract plans and specifications, as well as readily available trade association guidance.

Following construction, continued successful performance of pervious/porous pavements is

contingent upon proper maintenance as pervious/porous pavements require more maintenance (to

maintain the desired permeability of the pavement section) than conventional concrete or asphalt

pavement sections.

7.2 Pervious Concrete Pavement Design

F&R’s evaluation of concrete pavement section thickness is based on design methodology

included in ACI 325.12R-02, Guide for the Design of Jointed Concrete Pavements for Streets and

Local Roads, as well as a Washington State DOT research report, Preliminary Procedures for

Structural Design of Pervious Concrete Pavements. F&R recommends that the pavement section


9

consist of 8-inches of pervious concrete overlying an 8-inch thick base course of uniformly graded

free-draining washed stone such as NCDOT #57 stone. F&R recommends that a non-woven

geotextile filter fabric (such as Mirafi 140N) be placed between the fine grained subgrade soils

and the base course to maintain separation and prevent migration of the fine subgrade soils into

the base course that will serve as a recharge bed for stormwater. The pervious concrete should

have a 28-day design flexural strength of at least 450 psi. The contractor shall submit a concrete

mix design to the designer for approval prior to construction.

Pervious concrete pavements should be constructed in general accordance with technical

guidance provided in ACI 522R-10, Report on Pervious Concrete, and ACI 522.1-13, Specification

for Pervious Concrete Pavement should be considered when preparing the project specifications.

These documents provide guidance on concrete batching/mixing, transportation, placement and

consolidation, finishing, jointing, curing, protection, inspection, testing and long-term

maintenance of pervious concrete pavements. As indicated in the referenced documents, F&R

recommends that two test panels be constructed by the contractor using the same concrete mix

as will be used for the production concrete and the same means and methods as will be used

during construction.

Transverse and longitudinal contraction joints should be constructed in the new concrete to

control cracking. It is recommended that individual sections of jointed concrete be as close to

square as possible and the length to width (L:W) ratio of each section should not be greater than

1.25 Long to 1.0 Wide. It is recommended that longitudinal and transverse contraction joints be

located on a spacing of no greater than 12 feet. The use keyways or keyed construction joints is

not recommended. In areas where the concrete will be placed against fixed objects (e.g.,

buildings, drop inlets, manholes, light bases, etc.), isolation/expansion joints should be

constructed. Curing of the concrete surface is important to assure proper hydration and to help

assure the concrete achieves its potential strength and durability. More detailed design and

construction guidance can be found in the previously referenced ACI documents. In addition,

pavements should be constructed in accordance with applicable sections of the NCDOT Standard


10

Specifications for Roads and Structures. F&R should be afforded an opportunity to review the

pavement design plans prior to final design.

7.3 Porous Asphalt Pavement Design

F&R’s evaluation of asphalt pavement section thickness is based on design methodology included

in the National Asphalt Pavement Association IS 140, Structural Design Guidelines for Porous

Asphalt Pavements and the FHWA-HIF-15-009, Porous Asphalt Pavements with Stone Reservoirs.

F&R recommends that the pavement section consist of 5-inches porous asphalt pavement

overlying a 12-inch thick base course of uniformly graded free-draining washed stone. The

porous asphalt should utilize an aggregate gradation similar to Open-Graded Friction Course

(OGFC). The base course will serve as a recharge bed for stormwater that permeates through

the pavement surface. For porous asphalt pavements, there are a variety of base course

materials that can be used including large stone such as NCDOT #4 stone or AASHTO #3 stone.

To facilitate paving and stabilize the surface for the paving equipment, a thin choker course such

as NCDOT #57 or #67 stone is typically placed at the surface of the base course. The pavement

surface should be placed in at least 2 layers and in individual single layer maximum thicknesses

as required by NCDOT. F&R recommends that a non-woven geotextile filter fabric (such as Mirafi

140N) be placed between the fine grained subgrade soils and the base course to maintain

separation and prevent migration of the fine subgrade soils into the base course.

The contractor shall submit an asphalt mix design to the designer for approval prior to

construction. Porous asphalt pavements should be constructed in general accordance with the

previously referenced documents as well applicable sections of the NCDOT Standard

Specifications for Roads and Structures that includes information regarding materials, weather

limitations, placement, compaction, inspection, testing and long-term maintenance of pervious.

Porous asphalt pavements should never be seal coated of have cracks sealed. F&R should be

afforded an opportunity to review the pavement design plans prior to final design.


11

7.4 Site Development and Earthwork

For pervious/porous pavements, the soil subgrade and pavement surface should be constructed

as flat as flat as possible. The pavement should not be crowned, and the subgrade should slope

no more than 2%. In order to create a near-flat subgrade, the subgrade surface can be terraced

and/or earth berms (or baffles) can be incorporated into the subgrade.

Initial site preparation should include the removal of existing gravel, surficial organic soils, roots,

vegetation and any other deleterious materials from the proposed construction area and

extending a distance of at least 5 feet beyond the construction perimeter. Following the stripping

of deleterious material from proposed structural areas, the exposed subgrade soils at the finished

subgrade level and in fill sections should be evaluated by a geotechnical engineer. This evaluation

may include proofrolling the subgrade with a loaded tandem axle dump truck, scraper, or other

similar type of construction equipment to confirm the stability of the subgrade soils. If unstable

conditions are revealed, the method of repair should be as directed by the project geotechnical

engineer. Based on the results of the borings, soft subgrade are not anticipated.

Based on the proposed pavement finished grade being no more than 1-foot above existing site

grades, it is assumed that the subgrade will consist of native soils. If structural fill is required, the

low plasticity on-site soils will be suitable for use as structural fill material provided they are at a

moisture content suitable to achieve proper compaction and be stable. If soils are required to be

imported to the site to achieve subgrade levels, F&R recommends that a qualified geotechnical

engineer or engineering technician working under the direction of the geotechnical engineer

approve the suitability of the imported soils prior to their delivery to the site. Imported structural

fill should consist of low plasticity soil (LL<35, PI<20), have a maximum dry density of at least 100

pcf, and be free or organic and other deleterious materials.

In order to promote infiltration for the pervious pavement area, F&R recommends that the soil

subgrade immediately below the pervious washed stone base course be scarified to a depth of 12

inches and be recompacted to between 93 and 95 percent of the Standard Proctor maximum dry

density as determined by ASTM D-698. F&R does not recommend a higher degree of subgrade


12

compaction in the pervious pavement area and precautions should be taken to assure the subgrade

is not compacted above this range. In area of the site where conventional pavements will be utilized,

the subgrade should be compacted to at least 100% of the Standard Proctor maximum dry density

and in accordance with other City of Durham pavement construction practices.

All other structural earth fill and backfill should be compacted to at least 95 percent of the Standard

Proctor maximum dry density as determined by ASTM D-698. Structural earth fill should be placed

in loose lifts not exceeding 8 inches when large self-propelled compaction equipment is being

utilized and in lifts not exceeding 4 inches for small/light compaction equipment (e.g., walk behind

Rammax roller). All structural earth fill should be compacted at a moisture content within 3 percent

of the optimum moisture content. All structural fill material should be placed and compacted under

the full-time control and supervision of a qualified geotechnical engineer or engineering technician

working under the direction of the geotechnical engineer. The placement and compaction of all fill

material should be tested at frequent intervals in order to confirm that the recommended degree

of compaction is achieved.

The on-site soils have sufficient silt/clay content to render them moisture sensitive. The on-site soils

will become unstable (i.e., pump and rut) during normal construction activities when in the presence

of excess moisture. Soils with a moisture content greater than three percent above the optimum

moisture content are generally considered to have excessive moisture. During earthwork and

construction activities, surface-water runoff must be drained away from construction areas to

prevent water from ponding on or saturating the soils within excavations or on subgrades. It is

recommended that earthwork be performed during the summer and early fall months when the

weather conditions are more conducive to moisture conditioning of fill materials.

7.5 Temporary Excavation Recommendations

Mass excavations and other excavations required for construction of this project should be

performed in accordance with the United States Department of Labor, Occupational Safety and

Health Administration (OSHA) guidelines (29 CFR 1926, Subpart P, Excavations), or other

applicable jurisdictional codes for permissible temporary side-slope ratios and/or shoring


13

requirements. The OSHA guidelines require daily inspections of excavations, adjacent areas and

protective systems by a “competent person” for evidence of situations that could result in cave-

ins, indications of failure of a protective system, or other hazardous conditions. All excavated

soils, equipment, building supplies, etc., should be placed away from the edges of excavations at

a distance equaling or exceeding the depth of the excavation. F&R cautions that the actual

excavation slopes will need to be evaluated frequently each day by the “competent person” and

flatter slopes or the use of shoring may be required to maintain a safe excavation depending

upon excavation-specific circumstances. The contractor is responsible for providing the

“competent person” and all aspects of site excavation safety. F&R can evaluate specific

excavation slope situations if we are informed and requested by the owner, designer or

contractor’s “competent person”.

8.0 CONTINUATION OF SERVICES

A Geotechnical Engineer and/or civil engineering technician working under his supervision should

be retained to monitor and test earthwork activities, observe subgrade preparations and observe

paving operations. It should be noted that the actual soil conditions at the various subgrade levels

will vary across this site and thus the presence of the Geotechnical Engineer and/or his

representative during construction will serve to validate the subsurface conditions and

recommendations presented in this report. A geotechnical engineer should be employed to

monitor construction, and to report that the recommendations contained in this report are

completed in a satisfactory manner. The continued geotechnical engineering involvement on the

project will aid in the proper implementation of the recommendations discussed herein. The

following is a recommended scope of services:

Review of project plans and construction specifications to verify that the recommendations presented in this report have been properly interpreted and implemented;

Review contractor submittals regarding pervious/porous pavement;

Observe the earthwork process to document that subsurface conditions encountered during construction are consistent with the conditions anticipated in this report;


14

Observe the subgrade conditions before placing structural fill including proofroll observations;

Observe the placement and compaction of any structural fill and backfill, and perform laboratory and field compaction testing of the fill; and,

Observe and perform testing during pavement construction.

9.0 LIMITATIONS

This report has been prepared for the exclusive use of RK&K and/or their agents, for specific

application to the referenced project in accordance with generally accepted soil and foundation

engineering practices. No other warranty, express or implied, is made. Our evaluations and

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

subsurface exploration program, and generally-accepted geotechnical engineering practice. The

evaluations and recommendations do not reflect variations in subsurface conditions which could

exist intermediate of the boring locations or in unexplored areas of the site. Should such variations

become apparent during construction, it will be necessary to re-evaluate our recommendations

based upon on-site observations of the conditions.

There are important limitations to this and all geotechnical studies. Some of these limitations are

discussed in the information prepared by GBA, which is included in Appendix IV. We ask that you

please review this GBA information.

Regardless of the thoroughness of a subsurface exploration, there is the possibility that conditions

between borings will differ from those at the boring locations, that conditions are not as anticipated

by the designers, or that the construction process has altered the soil conditions. Therefore,

experienced geotechnical engineers should evaluate earthwork and pavement construction to

observe that the conditions anticipated in design actually exist. Otherwise, we assume no

responsibility for construction compliance with the design concepts, specifications, or

recommendations.

In the event that changes are made in the proposed construction, the recommendations presented

in the report shall not be considered valid unless the changes are reviewed by our firm and

conclusions of this report modified and/or verified in writing. If this report is copied or transmitted


15

to a third party, it must be copied or transmitted in its entirety, including text, attachments, and

enclosures. Interpretations based on only a part of this report may not be valid.

APPENDIX I

FIGURES

)

))

!>

!>

!>

S. Al

ston A

ve.

Bradford Circle

B-2B-3

B-1

I-3I-2

I-3

NAD 1983 StatePlane North Carolina FIPS 3900 (Feet)Client:Pro ject:LocationF&R Project No.:Data:Date:

Field Testing Plan

Scale: 1:600 1 inch = 50 feetFIGURE

No.:

RK&K

Du rham, Durham County, NC

NCOne Map 2017August 2018

0 25 50 75 10012.5 Feet

Bradford Circle

66V-0293

FROEHLING & ROBERTSON, INC.310 Hubert Street

Raleigh, North Carolina 27603-2302 I USAT 919.828.3441 I F 919.828.5751

ÜDisclaimer: F&R makes no warranties or guarantees regarding the accuracy orcompleteness of geographic features shown on this map. Spatial accuracy ofmeasurement provided by source agencies can be obtained by contacting F&R.Engineering Stability Since 1881

1

Legend!> Boring Location

) SHWT/Infiltration Test Location

APPENDIX II

BORING LOGS

KEY TO SOIL CLASSIFICATION Correlation of Penetration Resistance with Relative Density and Consistency Sands and Gravels Silts and Clays

No. of Relative No. of Relative Blows, N Density Blows, N Density

0 - 4 Very loose 0 - 2 Very soft 5 - 10 Loose 3 - 4 Soft 11 - 30 Medium dense 5 - 8 Firm 31 - 50 Dense 9 - 15 Stiff Over 50 Very dense 16 - 30 Very stiff 31 - 50 Hard Over 50 Very hard Particle Size Identification (Unified Classification System)

Boulders: Diameter exceeds 8 inches

Cobbles: 3 to 8 inches diameter

Gravel: Coarse - 3/4 to 3 inches diameter Fine - 4.76 mm to 3/4 inch diameter

Sand: Coarse - 2.0 mm to 4.76 mm diameter Medium - 0.42 mm to 2.0 mm diameter Fine - 0.074 mm to 0.42 mm diameter

Silt and Clay: Less than 0.07 mm (particles cannot be seen with naked eye) Modifiers

The modifiers provide our estimate of the amount of silt, clay or sand size particles in the soil sample. Approximate

Content

Modifiers Field Moisture

Description

≤ 5%: Trace

Saturated: Usually liquid; very wet, usually from below the groundwater table

5% to 12%: Slightly silty, slightly clayey, slightly sandy

Wet: Semisolid; requires drying to attain optimum moisture

12% to 30%: Silty, clayey, sandy Moist: Solid; at or near optimum moisture 30% to 50%: Very silty, very clayey, very

sandy Dry: Requires additional water to attain

optimum moisture

2.0

4.0

6.0

7.8

9.5

5‐9‐10‐17

6‐10‐10‐11

6‐9‐15‐17

8‐22‐32‐50/4"

23‐28‐50/5.5"

GROUNDWATER DATA:

0 Hr: Dry, Caved at 6.0'

0.20.5

2.0

4.0

7.5

9.5

0.0

2.0

4.0

6.0

8.0

19

20

24

54

100+

GRAVEL (2" Gravel‐Contaminated with Soil)

FILL: Very Stiff, Light Brown, Moist, Fine SandySilty CLAY (CL/ML)

NATIVE SOILS: Very Stiff, Brown and ReddishBrown, Moist, Fine Sandy Silty CLAY (CL/ML)

Very Stiff, Orangish Brown, Moist, Fine SandySILT (ML)

Very Stiff to Very Hard, Maroon‐Tan to Tan,Moist, Fine Sandy Clayey SILT (ML)

PARTIALLY WEATHERED ROCK: Sampled as VeryHard, Maroon, Dry, Silty SAND

Boring Terminated at 9.5 feet.

344.8344.5

343.0

341.0

337.5

335.5

Elevation: 345 ± Drilling Method: 2.25" ID HSA

Hammer Type: Automatic

Froehling & Robertson, Inc.

City/State: Durham, NC

Project: Bradford Circle

Total Depth: 9.5'

Date Drilled: 2/16/18

Remarks* SampleBlows

ElevationDescription of Materials

(Classification)

Boring Location: See Boring Location Plan

BORING LOGBoring: B‐1 (1 of 1)

Driller: D. Tignor

SampleDepth(feet)

Depth

R

N‐Value(blows/ft)

*Number of blows required for a 140 lb hammer dropping 30" to drive 2" O.D., 1.375" I.D. sampler a total of 18 inches in three 6" increments.The sum of the second and third increments of penetration is termed the standard penetration resistance, N‐Value.

Client: RK&K

Project No: 66V‐0293

BORING_LOG 66V‐0293 BORE LO

GS.GPJ F&R.GDT 2/21/18

2.0

4.0

6.0

8.0

10.0

4‐12‐21‐33

13‐25‐32‐43

14‐19‐24‐23

7‐14‐19‐34

20‐35‐28‐39

GROUNDWATER DATA:

0 Hr: Dry, Caved at 6.5'0.8

6.0

8.0

10.0

0.0

2.0

4.0

6.0

8.0

33

57

43

33

63

GRAVEL (9" Gravel Contaminated with Soil)

NATIVE SOILS: Hard to Very Hard, DarkMaroon‐Brown, Dry to Moist, Silty CLAY (CL)

Hard, Grayish‐Tan, Moist, Fine Sandy SILT (ML)

Very Hard, Dark Maroon‐Brown, Moist, SiltyCLAY (CL)

Boring Terminated at 10 feet.

337.2

332.0

330.0

328.0






Total Depth: 10.0'




(Classification)



Driller: D. Tignor

SampleDepth(feet)

Depth

R

N‐Value(blows/ft)


Client: RK&K




2.0

4.0

6.0

8.0

9.9

7‐13‐16‐25

10‐21‐22‐26

11‐21‐26‐40

15‐15‐19‐25

7‐19‐29‐50/5"

GROUNDWATER DATA:

0 Hr: Dry, Caved at 6.5'

1.3

9.5

9.9

0.0

2.0

4.0

6.0

8.0

29

43

47

34

48

GRAVEL (15" Stone Contaminated with Soil)

NATIVE SOILS: Very Stiff to Hard, DarkMaroon‐Brown, Moist, Silty CLAY (CL)

PARTIALLY WEATHERED ROCK: Sampled as VeryHard, Dark Maroon‐Brown, Moist, Silty CLAY

Boring Terminated at 9.9 feet.

334.7

326.5

326.1






Total Depth: 9.9'




(Classification)



Driller: D. Tignor

SampleDepth(feet)

Depth

R

N‐Value(blows/ft)


Client: RK&K




APPENDIX III

SHWT & INFILTRATION TESTING RESULTS

SEASONAL HIGH WATER TABLE DETERMINATION AND INFILTRATION TESTING

Bradford Circle Durham, North Carolina

Job # 18-751

Prepared For:

Froehling & Robertson, Inc. 310 Hubert Street

Raleigh, NC 27603

Prepared By:

324 Blackwell Street, Suite 1200 Durham, NC 27701

(919) 732-1300

May 22, 2018

John C Roberts

18-751 Bradford Circle 1 May 22, 2018

SHWT & Infiltration Report

INTRODUCTION

Froehling & Robertson, Inc (F&R) is investigation the design possibilities of converting Bradford Circle from a gravel road into a permeable pavement stormwater control measure (SCM). Bradford Circle is located in Durham, NC off of Alston Avenue. The proposed SCM will infiltrate, collect, and treat runoff from adjacent impervious surfaces. As part of the design process, a confirmation of the seasonal high water table (SHWT) and infiltration tests conducted below the existing gravel roadbed have been requested. Three Oaks Engineering (Three Oaks) has been retained to perform these tests.

INVESTIGATION METHODOLOGY

The field investigation was performed on May 9, 2018 by John C. Roberts, LSS and Evan T. Morgan, LSS-IT. A backhoe was used to excavate the gravel road and subgrade to natural soil in 4-feet by 4-feet test pits. Soil borings were advanced via a hand auger. Observations of the landscape (slope, drainage patterns, etc.) as well as soil properties (depth, texture, seasonal wetness, restrictive horizons, etc.) were recorded. Soil color was determined with a Munsell Soil Color Chart. The infiltration rate of a soil was determined using the ASTM D3385-18 Standard Test Method for Infiltration Rate of Soils in Field Using Double-Ring Infiltrometer. A compact constant-head permeameter (Amoozemeter) was used to maintain a constant volume of water within the inside ring. RESULTS

Depth to Seasonal High Water Table and Soil Description

Three soil borings were advanced at the excavated test pits and their locations shown on Figure 1. Each boring was terminated at 7-feet below the gravel subbase or auger refusal; whichever was shallower. Evidence of a SHWT was not observed at the soil borings. A perched water table (PWT) was observed at the boring locations; the details of which are shown in Table 1. Boring 1 was terminated at 41 inches due to auger refusal. Full soil profile descriptions are attached. Table 1. Depth to SHWT and PWT

Soil Boring SHWT

(in. below surface) PWT

(in. below surface) I-1 B1 >41 25-27 I-2 B2 >98 14-26; 80-98 I-3 B3 >92 8-28; 44-92

Double Ring Infiltrometer Measurements

Three double ring infiltration tests were conducted throughout Bradford Circle in conjunction with the SHWT borings. The tests were conducted below the existing gravel subgrade. The results of the tests are listed in Table 2. Full data sheets are attached.



Table 2. Infiltration Test Results

Test Location Depth from road

surface (in)

Infiltration Rate

(in/hr)

I-1 Test 1 25 0.018 I-2 Test 2 14 0.072 I-3 Test 3 8 0.198

CONCLUSIONS

The findings presented herein represent Three Oaks’ professional opinion based on our soil evaluation. This report is provided to assist in designing of the SCM by providing the soil information. A SHWT was not observed within 41 inches of the existing surface at B1 and within 7-feet below the subgrade at B2 and B3. The infiltration tests resulted in measurements of 0.018, 0.072 and 0.198 in/hr at borings B1, B2 and B3, respectively.

Key to Abbreviations for Soil Profile Descriptions

Reference:

Schoeneberger, P.J., D.A. Wysocki, E.C. Benham, and Soil Survey Staff. 2012. Field book for

describing and sampling soils, Version 3.0. Natural Resources Conservation Service,

National Soil Survey Center, Lincoln, NE.

APPENDIX IV

GEOTECHNICAL LABORATORY TEST RESULTS

85

90

95

100

105

110

115

120

125

130

0 5 10 15 20 25 30 35

0 5 10

I-01

I-02

I-03

54.6

63.7

65.8

2.7

1.8

0.9

MOISTURE-DENSITYRELATIONSHIP

I-01

I-02

I-03

16.2

13.6

12.4

I-1

I-2

I-3

Received 5/9/18

Received 5/9/2018

Received 5/9/2018

1.0' - 2.0'

1.0' - 2.0'

1.0' - 2.0'

12.9

13.6

12.6

Dark Brown, SANDY LEAN CLAY (CL)

Dark Brown, SANDY LEAN CLAY (CL)

Dark Red / Brown, SANDY LEAN CLAY (CL)

37

35

28

18

17

18

19

18

10

42.7

34.5

33.3

114.9

115.5

119.3

D-698 A

D-698 A

D-698 A

Client: City of Durham

City/State: Durham, North CarolinaProject: Bradford Circle

Project No: 66V-0293

R

F r o e h l in g & R o b e r t s o n , I n c .PR

OCT

OR

CURV

E 6

6V-0

293

CLAS

SIFI

CATI

ON

S &

PRO

CTO

RS.G

PJ F

&R.

GD

T 8

/23/

18

Sample

Depth (ft) Classification PLSample

Sample Notes

% GRAVEL(+ #4)

SampleLocation

NaturalMoisture (%)

Max DryDensity (pcf)

OptimumMoisture (%)

LL PI % SAND(#4 - #200)

% FINES(- #200)

ASTM

0

10

20

30

40

50

60

0 20 40 60 80 100

PI

19

18

10

PLLL Classification % Natural Water Content

16.2

13.6

12.4

ATTERBERG LIMITS

37

35

28

18

17

18

Liquid Limit

Plas

ticity

Inde

x

FinesBoring No. Depth

CH

ML MH

SANDY LEAN CLAY (CL)



54.6

63.7

65.8

CL-ML

CL

Sheet: 1 of 1

I-01

I-02

I-03

1.0' - 2.0'

1.0' - 2.0'

1.0' - 2.0'




R

F r o e h l in g & R o b e r t s o n , I n c .AT

TERB

ERG

_LIM

ITS_

USC

S 6

6V-0

293

CLAS

SIFI

CATI

ON

S &

PRO

CTO

RS.G

PJ F

&R.

GD

T 8

/23/

18

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

0.0010.010.1110100Grain Size (mm)

fineSILT OR CLAY

I-01I-02I-03

ClassificationSANDY LEAN CLAY (CL)SANDY LEAN CLAY (CL)SANDY LEAN CLAY (CL)

LL PL PI

0.094D30 D10

Cc

%Silt16.213.612.4

54.663.765.8

Content

GRAIN SIZEDISTRIBUTION

COBBLES

Depth

% Water

3/8 3 4 6 810 1416 20 30 40 50 60 100140200

U.S. SIEVE OPENING IN INCHES

I-01I-02I-03

Depth

Boring No.

D10025

37.537.5

D60 %Gravel2.71.80.9

%Sand42.734.533.3

Cu

U.S. SIEVE NUMBERS HYDROMETER

6

%Clay

4 3 2 1.5 1 3/4 1/2

181718

191810

373528

Perc

ent F

iner

(By

Wei

ght)

GRAVELcoarse fine coarse medium

SAND

1.0' - 2.0'1.0' - 2.0'1.0' - 2.0'

1.0' - 2.0'1.0' - 2.0'1.0' - 2.0'

Boring No.




R

F r o e h l in g & R o b e r t s o n , I n c .U

S_G

RAIN

_SIZ

E 6

6V-0

293

CLAS

SIFI

CATI

ON

S &

PRO

CTO

RS.G

PJ F

&R.

GD

T 8

/23/

18

I-02 (90%) I-2 CL 63.7

Sample Number Sample Location USCS % - #200

I-01 (90%) I-1 CL 54.6

I-01 (90%) Dark Brown, SANDY LEAN CLAY 114.9 12.9


Sample Information Proctor Value (ASTM D-698)

Sample Number Classification Max. Dry Density (pcf) Optimum Moisture %

Date Received: 5/9/2018 I-01 (90%) 2.530 2.480

Project Location: Durham, North Carolina I-02 (90%) 3.340 3.210

Client Name: RK&K I-02 (90%) 13.6

Project Number: 66V-0293 Percent Swell A B

Project Information Natural Moisture (%)

Project Name: Bradford Circle I-01 (90%) 16.2

Final Density (pcf) 102.8 103.8 105.6 105.7

Final Moisture (%) 21.5 21.2 20.9 21.0

Density (pcf) 102.6 103.7 105.6 105.3

Moisture (%) 12.6 12.7 13.1 13.4

0.2 in Pen. 1.6 1.8 0.9 0.9

FROEHLING & ROBERTSON, INC.

California Bearing Ratio Test Report

0.1 in Pen. 1.8 1.8 0.9 1.0

SOAKED CBR TEST RESULTS

Results I-01 (A) [90%] I-01 (B) [90%] I-02 (A) [90%] I-02 (B) [90%]

0

5

10

15

20

25

30

35

40

45

50

0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450 0.500

Fo

rce

on

Pis

ton

(p

si)

Penetration (in)

Load Penetration Curve

I-01 (A)

I-01 (B)

I-02 (A)

I-02 (B)


I-03 (90%) I-3 CL 65.8

I-03 (90%) Dark Red/Brown, SANDY LEAN CLAY 119.3 12.6



Date Received: 5/9/2018 I-03 (90%) 2.620 2.770

Project Location: Durham, North Carolina

Client Name: RK&K




Final Density (pcf) 106.8 107.0

Final Moisture (%) 19.9 19.8

Density (pcf) 106.2 106.8

Moisture (%) 12.6 12.0

0.2 in Pen. 0.7 0.7



0.1 in Pen. 0.7 0.8


Results I-03 (A) [90%] I-03 (B) [90%]

0

2

4

6

8

10

12

14

16

18

0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450 0.500

Fo

rce

on

Pis

ton

(p

si)

Penetration (in)


I-03 (A)

I-03 (B)

I-02 (93%) I-2 CL 63.7


I-01 (93%) I-1 CL 54.6





Date Received: 5/9/2018 I-01 (93%) 2.510 2.430







Final Moisture (%) 21.7 22.5 19.9 20.6

Density (pcf) 105.4 105.8 109.7 107.0

Moisture (%) 13.4 13.4 14.2 14.4

0.2 in Pen. 2.8 3.2 2.8 1.8



0.1 in Pen. 3.1 3.7 3.2 1.9



0

10

20

30

40

50

60

70

80

0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450 0.500

Fo

rce

on

Pis

ton

(p

si)

Penetration (in)


I-01 (A)

I-01 (B)

I-02 (A)

I-02 (B)


I-03 (93%) I-3 CL 65.8




Date Received: 5/9/2018 I-03 (93%) 2.570 2.750


Client Name: RK&K







Moisture (%) 12.7 13.4

0.2 in Pen. 1.6 2.4



0.1 in Pen. 2.0 2.7


Results I-03 (A) [93%] I-03 (B) [93%]

0

10

20

30

40

50

60

0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450 0.500

Fo

rce

on

Pis

ton

(p

si)

Penetration (in)


I-03 (A)

I-03 (B)



0.1 in Pen. 1.8 4.6 1.9 2.4



Moisture (%) 13.4 13.1 13.9 13.9

0.2 in Pen. 1.8 4.3 1.8 2.4

Final Moisture (%) 18.6 18.1 19.1 19.0

Density (pcf) 108.4 110.5 109.0 109.9






Date Received: 5/9/2018 I-01 (95%) 2.290 1.810






I-02 (95%) I-2 CL 63.7


I-01 (95%) I-1 CL 54.6

0

20

40

60

80

100

120

0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450 0.500

Fo

rce

on

Pis

ton

(p

si)

Penetration (in)


I-01 (A)

I-01 (B)

I-02 (A)

I-02 (B)



0.1 in Pen. 2.9 2.6


Results I-03 (A) [95%] I-03 (B) [95%]

Moisture (%) 12.7 13.1

0.2 in Pen. 2.9 2.6






Client Name: RK&K


Date Received: 5/9/2018 I-03 (95%) 2.490 2.560






I-03 (95%) I-3 CL 65.8

0

10

20

30

40

50

60

70

80

0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450 0.500

Fo

rce

on

Pis

ton

(p

si)

Penetration (in)


CBR-3 (A)

CBR-3 (B)

Project: Bradford Circle Date:

Client: City of Durham Sample No:

Project No: 66V-0293 Location:

Elapsed Head Inflow Outflow Average Flow Temp Permeability

DATE Time Time (sec) water (cm) Burette (cc) Burette (cc) Flow (cm) Ratio (C°) cm/sec

06/27/18 13:00:00 0 74.93 0.00 10.00 0 0 22.4

06/27/18 13:01:00 60.0 67.13 1.56 8.24 8.34 1.128 22.4 3.7E-05

06/27/18 13:02:00 60.0 62.13 2.56 7.00 5.63 1.240 22.4 2.5E-05

06/27/18 13:03:00 60.0 56.73 3.64 5.90 5.48 1.019 22.4 2.8E-05

06/27/18 13:04:00 60.0 51.43 4.70 4.80 5.43 1.038 22.4 2.8E-05

06/27/18 13:05:00 60.0 47.43 5.50 4.00 4.02 1.000 22.4 2.2E-05

06/27/18 13:06:00 60.0 43.23 6.34 3.18 4.17 0.976 22.4 2.4E-05

06/27/18 13:07:00 60.0 39.63 7.06 2.42 3.72 1.056 22.4 2.1E-05

06/27/18 13:08:00 60.0 36.23 7.74 1.80 3.27 0.912 22.4 2.0E-05

06/27/18 13:09:00 60.0 33.23 8.34 1.16 3.12 1.067 22.4 1.8E-05

06/27/18 13:10:00 60.0 30.43 8.90 0.60 2.81 1.000 22.4 1.7E-05

06/27/18 13:11:00 60.0 27.93 9.40 0.10 2.51 1.000 22.4 1.6E-05

1.8E-05

Inflow Outflow Cell Head Tail

Area Area PSI PSI PSI

0.20 0.20 54.0 51.0 49.6

98.49

Date:

I-01 (90.7%)

1.0' - 2.0'

05/09/18

Drew Council

HYDRAULIC CONDUCTIVITY

Using A Flexible Wall Permeameter

6/27/2018Performed By:

Average Permeability cm/sec. Pressures

ASTM D-5084

2.0E-064.0E-066.0E-068.0E-061.0E-051.2E-051.4E-051.6E-051.8E-052.0E-052.2E-05

Hyd

rau

lic C

on

du

cti

vit

y (

cm

/sec)

Time (sec)

Time Versus Hydraulic Conductivity


Client: RK&K Sample No:




06/27/18 9:23:00 0 74.93 0.00 10.00 0 0 22.4

06/27/18 9:39:00 960.0 72.33 0.52 9.42 2.76 1.115 22.4 5.8E-07

06/27/18 10:01:00 1320.0 69.43 1.10 8.72 3.21 1.207 22.4 4.7E-07

06/27/18 10:26:00 1500.0 66.13 1.76 8.02 3.42 1.061 22.4 4.8E-07

06/27/18 10:47:00 1260.0 63.63 2.26 7.50 2.56 1.040 22.4 4.4E-07

06/27/18 11:17:00 1800.0 59.93 3.00 6.72 3.82 1.054 22.4 4.6E-07

06/27/18 11:42:00 1500.0 57.13 3.56 6.16 2.81 1.000 22.4 4.3E-07

06/27/18 12:13:00 1860.0 53.63 4.26 5.48 3.47 0.971 22.4 4.3E-07

06/27/18 12:48:00 2100.0 50.23 4.94 4.78 3.47 1.029 22.4 3.8E-07

06/27/18 13:13:00 1500.0 47.73 5.44 4.28 2.51 1.000 22.4 4.0E-07

06/27/18 13:29:00 960.0 46.13 5.76 3.96 1.61 1.000 22.4 4.0E-07

06/27/18 13:50:00 1260.0 44.23 6.14 3.58 1.91 1.000 22.4 3.7E-07

3.9E-07



0.20 0.20 65.0 62.8 60.6

154.77

Date:

05/09/18

I-02 (90.7%)

1.0' - 2.0'

Drew Council





ASTM D-5084

3.4E-07

3.5E-07

3.6E-07

3.7E-07

3.8E-07

3.9E-07

4.0E-07

4.1E-07

Hyd

rau

lic C

on

du

cti

vit

y (

cm

/sec)

Time (sec)







06/27/18 14:10:00 0 74.23 0.14 9.50 0 0 21.4

06/27/18 14:48:00 2280.0 71.13 0.76 8.88 3.12 1.000 21.6 3.9E-07

06/27/18 15:17:00 1740.0 69.03 1.18 8.48 2.06 0.952 21.6 3.5E-07

06/27/18 15:57:00 2400.0 66.33 1.72 7.90 2.81 1.074 21.6 3.4E-07

06/28/18 8:23:00 59160.0 36.43 7.70 1.28 31.65 1.107 21.7 1.7E-07

3.1E-07



0.20 0.20 53.6 50.6 49.2

98.49

Date:

05/09/18

I-03 (90.1%)

1.0' - 2.0'



ASTM D-5084

Drew Council



1.0E-07

1.5E-07

2.0E-07

2.5E-07

3.0E-07

3.5E-07

4.0E-07

4.5E-07

Hyd

rau

lic C

on

du

cti

vit

y (

cm

/sec)

Time (sec)







06/27/18 13:06:00 0 74.93 0.00 10.00 0 0 22.4

06/27/18 13:07:00 60.0 72.93 0.40 9.34 2.66 1.650 22.4 9.4E-06

06/27/18 13:08:00 60.0 68.93 1.20 8.58 3.92 0.950 22.4 1.9E-05

06/27/18 13:09:00 60.0 64.93 2.00 7.76 4.07 1.025 22.4 2.0E-05

06/27/18 13:10:00 60.0 61.43 2.70 7.04 3.57 1.029 22.4 1.8E-05

06/27/18 13:11:00 60.0 57.93 3.40 6.30 3.62 1.057 22.4 1.8E-05

06/27/18 13:12:00 60.0 54.93 4.00 5.70 3.02 1.000 22.4 1.6E-05

06/27/18 13:13:00 60.0 51.83 4.62 5.10 3.07 0.968 22.4 1.7E-05

06/27/18 13:14:00 60.0 48.93 5.20 4.54 2.86 0.966 22.4 1.6E-05

06/27/18 13:15:00 60.0 45.83 5.82 3.90 3.17 1.032 22.4 1.7E-05

06/27/18 13:16:00 60.0 43.63 6.26 3.46 2.21 1.000 22.4 1.2E-05

06/27/18 13:19:00 180.0 36.93 7.60 2.16 6.63 0.970 22.4 1.3E-05

1.5E-05



0.20 0.20 53.5 50.5 49.1

98.49

Date:

05/09/18

I-01 (93.1%)

1.0' - 2.0'



ASTM D-5084

Drew Council



2.0E-06

4.0E-06

6.0E-06

8.0E-06

1.0E-05

1.2E-05

1.4E-05

1.6E-05

1.8E-05

Hyd

rau

lic C

on

du

cti

vit

y (

cm

/sec)

Time (sec)







06/27/18 9:24:00 0 74.93 0.00 10.00 0 0 22.4

06/27/18 9:39:00 900.0 72.33 0.52 9.28 3.11 1.385 22.4 6.0E-07

06/27/18 10:01:00 1320.0 69.23 1.14 8.54 3.42 1.194 22.4 4.9E-07

06/27/18 10:26:00 1500.0 65.63 1.86 7.76 3.77 1.083 22.4 5.1E-07

06/27/18 10:46:00 1200.0 62.93 2.40 7.20 2.76 1.037 22.4 4.8E-07

06/27/18 11:18:00 1920.0 58.93 3.20 6.36 4.12 1.050 22.4 4.5E-07

06/27/18 11:41:00 1380.0 56.03 3.78 5.78 2.91 1.000 22.4 4.7E-07

06/27/18 12:14:00 1980.0 52.23 4.54 5.00 3.87 1.026 22.4 4.3E-07

06/27/18 12:47:00 1980.0 48.53 5.28 4.26 3.72 1.000 22.4 4.3E-07

06/27/18 13:13:00 1560.0 45.73 5.84 3.70 2.81 1.000 22.4 4.2E-07

06/27/18 13:28:00 900.0 44.23 6.14 3.40 1.51 1.000 22.4 3.9E-07

06/27/18 13:51:00 1380.0 42.03 6.58 2.96 2.21 1.000 22.4 3.8E-07

4.0E-07



0.20 0.20 65.0 62.8 60.5

161.81

Date:

05/09/18

I-02 (92.2%)

1.0' - 2.0'



ASTM D-5084

Drew Council



3.5E-073.6E-073.7E-073.8E-073.9E-074.0E-074.1E-074.2E-074.3E-074.4E-07

Hyd

rau

lic C

on

du

cti

vit

y (

cm

/sec)

Time (sec)







06/27/18 14:10:00 0 74.63 0.06 9.64 0 0 22.4

06/27/18 14:48:00 2280.0 73.73 0.24 8.92 2.25 4.000 22.4 1.1E-07

06/27/18 15:18:00 1800.0 72.83 0.42 8.58 1.30 1.889 22.4 1.4E-07

06/27/18 15:59:00 2460.0 71.53 0.68 8.14 1.76 1.692 22.4 1.5E-07

06/28/18 8:23:00 59040.0 50.73 4.84 2.94 23.51 1.250 22.4 1.1E-07

06/28/18 9:21:00 3480.0 49.93 5.00 2.78 0.80 1.000 22.4 7.5E-08

06/28/18 11:05:00 6240.0 47.03 5.58 2.18 2.96 1.034 22.4 1.5E-07

06/28/18 12:00:00 3300.0 42.83 6.42 1.32 4.27 1.024 22.4 4.3E-07

1.9E-07



0.20 0.20 53.8 50.8 49.4

98.49

Date:

05/09/18

I-03 (93.6%)

1.0' - 2.0'



ASTM D-5084

Drew Council



0.0E+005.0E-081.0E-071.5E-072.0E-072.5E-073.0E-073.5E-074.0E-074.5E-075.0E-07

Hyd

rau

lic C

on

du

cti

vit

y (

cm

/sec)

Time (sec)







06/27/18 13:12:00 0 74.93 0.00 10.00 0 0 22.4

06/27/18 13:13:00 60.0 73.43 0.30 9.62 1.71 1.267 22.4 7.0E-06

06/27/18 13:14:00 60.0 72.13 0.56 9.34 1.36 1.077 22.4 6.1E-06

06/27/18 13:15:00 60.0 70.93 0.80 9.10 1.21 1.000 22.4 5.7E-06

06/27/18 13:17:00 120.0 68.53 1.28 8.58 2.51 1.083 22.4 5.8E-06

06/27/18 13:20:00 180.0 65.53 1.88 7.90 3.22 1.133 22.4 4.9E-06

06/27/18 13:24:00 240.0 61.13 2.76 7.10 4.22 0.909 22.4 5.5E-06

06/27/18 13:27:00 180.0 58.33 3.32 6.54 2.81 1.000 22.4 4.8E-06

06/27/18 13:31:00 240.0 54.73 4.04 5.84 3.57 0.972 22.4 4.7E-06

06/27/18 13:34:00 180.0 52.23 4.54 5.34 2.51 1.000 22.4 4.4E-06

06/27/18 13:41:00 420.0 47.23 5.54 4.34 5.03 1.000 22.4 3.9E-06

06/27/18 13:56:00 900.0 37.83 7.42 2.48 9.40 0.989 22.4 3.6E-06

4.2E-06



0.20 0.20 53.5 50.5 49.1

98.49

Date:

05/09/18

I-01 (96.2%)

1.0' - 2.0'



ASTM D-5084

Drew Council



2.0E-06

2.5E-06

3.0E-06

3.5E-06

4.0E-06

4.5E-06

5.0E-06

Hyd

rau

lic C

on

du

cti

vit

y (

cm

/sec)

Time (sec)







06/27/18 9:25:00 0 74.93 0.00 10.00 0 0 22.4

06/27/18 9:40:00 900.0 72.93 0.40 9.62 1.96 0.950 22.4 4.4E-07

06/27/18 10:01:00 1260.0 71.03 0.78 9.20 2.01 1.105 22.4 3.0E-07

06/27/18 10:27:00 1560.0 68.73 1.24 8.72 2.36 1.043 22.4 3.0E-07

06/27/18 10:46:00 1140.0 67.13 1.56 8.40 1.61 1.000 22.4 2.9E-07

06/27/18 11:18:00 1920.0 64.53 2.08 7.86 2.66 1.038 22.4 2.8E-07

06/27/18 11:40:00 1320.0 62.63 2.46 7.50 1.86 0.947 22.4 3.0E-07

06/27/18 12:14:00 2040.0 60.03 2.98 6.98 2.61 1.000 22.4 2.7E-07

06/27/18 12:46:00 1920.0 57.53 3.48 6.50 2.46 0.960 22.4 2.8E-07

06/27/18 13:14:00 1680.0 55.63 3.86 6.10 1.96 1.053 22.4 2.4E-07

06/27/18 13:28:00 840.0 54.53 4.08 5.90 1.06 0.909 22.4 2.8E-07

06/27/18 13:51:00 1380.0 52.93 4.40 5.58 1.61 1.000 22.4 2.5E-07

2.6E-07



0.20 0.20 65.0 62.9 60.5

168.84

Date:

05/09/18

I-02 (94.5%)

1.0' - 2.0'



ASTM D-5084

Drew Council



2.2E-07

2.3E-07

2.4E-07

2.5E-07

2.6E-07

2.7E-07

2.8E-07

2.9E-07

Hyd

rau

lic C

on

du

cti

vit

y (

cm

/sec)

Time (sec)







06/27/18 14:10:00 0 74.53 0.08 10.00 0 0 22.0

06/27/18 14:49:00 2340.0 74.03 0.18 9.82 0.70 1.800 22.0 6.1E-08

06/27/18 15:18:00 1740.0 73.93 0.20 9.76 0.20 3.000 22.0 1.6E-08

06/27/18 16:00:00 2520.0 73.73 0.24 9.66 0.35 2.500 22.0 2.3E-08

06/28/18 8:24:00 59040.0 67.73 1.44 8.50 5.93 0.967 22.0 2.9E-08

06/28/18 9:21:00 3420.0 67.43 1.50 8.44 0.30 1.000 22.0 2.6E-08

06/28/18 11:10:00 6540.0 66.93 1.60 8.34 0.50 1.000 22.0 2.3E-08

06/28/18 12:00:00 3000.0 66.33 1.72 8.22 0.60 1.000 22.0 5.9E-08

3.4E-08



0.20 0.20 54.0 51.0 49.6

98.49

Date:

05/09/18

I-03 (96.1%)

1.0' - 2.0'



ASTM D-5084

Drew Council



0.0E+00

1.0E-08

2.0E-08

3.0E-08

4.0E-08

5.0E-08

6.0E-08

7.0E-08

Hyd

rau

lic C

on

du

cti

vit

y (

cm

/sec)

Time (sec)


APPENDIX V

GBA DOCUMENT

Geotechnical-Engineering ReportImportant Information about This

Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.

While you cannot eliminate all such risks, you can manage them. The following information is provided to help.

The Geoprofessional Business Association (GBA) has prepared this advisory to help you – assumedly a client representative – interpret and apply this geotechnical-engineering report as effectively as possible. In that way, clients can benefit from a lowered exposure to the subsurface problems that, for decades, have been a principal cause of construction delays, cost overruns, claims, and disputes. If you have questions or want more information about any of the issues discussed below, contact your GBA-member geotechnical engineer. Active involvement in the Geoprofessional Business Association exposes geotechnical engineers to a wide array of risk-confrontation techniques that can be of genuine benefit for everyone involved with a construction project.

Geotechnical-Engineering Services Are Performed for Specific Purposes, Persons, and ProjectsGeotechnical engineers structure their services to meet the specific needs of their clients. A geotechnical-engineering study conducted for a given civil engineer will not likely meet the needs of a civil-works constructor or even a different civil engineer. Because each geotechnical-engineering study is unique, each geotechnical-engineering report is unique, prepared solely for the client. Those who rely on a geotechnical-engineering report prepared for a different client can be seriously misled. No one except authorized client representatives should rely on this geotechnical-engineering report without first conferring with the geotechnical engineer who prepared it. And no one – not even you – should apply this report for any purpose or project except the one originally contemplated.

Read this Report in FullCostly problems have occurred because those relying on a geotechnical-engineering report did not read it in its entirety. Do not rely on an executive summary. Do not read selected elements only. Read this report in full.

You Need to Inform Your Geotechnical Engineer about ChangeYour geotechnical engineer considered unique, project-specific factors when designing the study behind this report and developing the confirmation-dependent recommendations the report conveys. A few typical factors include: • the client’s goals, objectives, budget, schedule, and risk-management preferences; • the general nature of the structure involved, its size, configuration, and performance criteria; • the structure’s location and orientation on the site; and • other planned or existing site improvements, such as retaining walls, access roads, parking lots, and underground utilities.

Typical changes that could erode the reliability of this report include those that affect:• the site’s size or shape;• the function of the proposed structure, as when it’s changed from a parking garage to an office building, or from a light-industrial plant to a refrigerated warehouse;• the elevation, configuration, location, orientation, or weight of the proposed structure;• the composition of the design team; or• project ownership.

As a general rule, always inform your geotechnical engineer of project changes – even minor ones – and request an assessment of their impact. The geotechnical engineer who prepared this report cannot accept responsibility or liability for problems that arise because the geotechnical engineer was not informed about developments the engineer otherwise would have considered.

This Report May Not Be ReliableDo not rely on this report if your geotechnical engineer prepared it:• for a different client;• for a different project;• for a different site (that may or may not include all or a portion of the original site); or • before important events occurred at the site or adjacent to it; e.g., man-made events like construction or environmental remediation, or natural events like floods, droughts, earthquakes, or groundwater fluctuations.

Note, too, that it could be unwise to rely on a geotechnical-engineering report whose reliability may have been affected by the passage of time, because of factors like changed subsurface conditions; new or modified codes, standards, or regulations; or new techniques or tools. If your geotechnical engineer has not indicated an “apply-by” date on the report, ask what it should be, and, in general, if you are the least bit uncertain about the continued reliability of this report, contact your geotechnical engineer before applying it. A minor amount of additional testing or analysis – if any is required at all – could prevent major problems.

Most of the “Findings” Related in This Report Are Professional OpinionsBefore construction begins, geotechnical engineers explore a site’s subsurface through various sampling and testing procedures. Geotechnical engineers can observe actual subsurface conditions only at those specific locations where sampling and testing were performed. The data derived from that sampling and testing were reviewed by your geotechnical engineer, who then applied professional judgment to form opinions about subsurface conditions throughout the site. Actual sitewide-subsurface conditions may differ – maybe significantly – from those indicated in this report. Confront that risk by retaining your geotechnical engineer to serve on the design team from project start to project finish, so the individual can provide informed guidance quickly, whenever needed.

This Report’s Recommendations Are Confirmation-DependentThe recommendations included in this report – including any options or alternatives – are confirmation-dependent. In other words, they are not final, because the geotechnical engineer who developed them relied heavily on judgment and opinion to do so. Your geotechnical engineer can finalize the recommendations only after observing actual subsurface conditions revealed during construction. If through observation your geotechnical engineer confirms that the conditions assumed to exist actually do exist, the recommendations can be relied upon, assuming no other changes have occurred. The geotechnical engineer who prepared this report cannot assume responsibility or liability for confirmation-dependent recommendations if you fail to retain that engineer to perform construction observation.

This Report Could Be MisinterpretedOther design professionals’ misinterpretation of geotechnical-engineering reports has resulted in costly problems. Confront that risk by having your geotechnical engineer serve as a full-time member of the design team, to: • confer with other design-team members, • help develop specifications, • review pertinent elements of other design professionals’ plans and specifications, and • be on hand quickly whenever geotechnical-engineering guidance is needed. You should also confront the risk of constructors misinterpreting this report. Do so by retaining your geotechnical engineer to participate in prebid and preconstruction conferences and to perform construction observation.

Give Constructors a Complete Report and GuidanceSome owners and design professionals mistakenly believe they can shift unanticipated-subsurface-conditions liability to constructors by limiting the information they provide for bid preparation. To help prevent the costly, contentious problems this practice has caused, include the complete geotechnical-engineering report, along with any attachments or appendices, with your contract documents, but be certain to note conspicuously that you’ve included the material for informational purposes only. To avoid misunderstanding, you may also want to note that “informational purposes” means constructors have no right to rely on the interpretations, opinions, conclusions, or recommendations in the report, but they may rely on the factual data relative to the specific times, locations, and depths/elevations referenced. Be certain that constructors know they may learn about specific project requirements, including options selected from the report, only from the design drawings and specifications. Remind constructors that they may

perform their own studies if they want to, and be sure to allow enough time to permit them to do so. Only then might you be in a position to give constructors the information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Conducting prebid and preconstruction conferences can also be valuable in this respect.

Read Responsibility Provisions CloselySome client representatives, design professionals, and constructors do not realize that geotechnical engineering is far less exact than other engineering disciplines. That lack of understanding has nurtured unrealistic expectations that have resulted in disappointments, delays, cost overruns, claims, and disputes. To confront that risk, geotechnical engineers commonly include explanatory provisions in their reports. Sometimes labeled “limitations,” many of these provisions indicate where geotechnical engineers’ responsibilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly.

Geoenvironmental Concerns Are Not CoveredThe personnel, equipment, and techniques used to perform an environmental study – e.g., a “phase-one” or “phase-two” environmental site assessment – differ significantly from those used to perform a geotechnical-engineering study. For that reason, a geotechnical-engineering report does not usually relate any environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated subsurface environmental problems have led to project failures. If you have not yet obtained your own environmental information, ask your geotechnical consultant for risk-management guidance. As a general rule, do not rely on an environmental report prepared for a different client, site, or project, or that is more than six months old.

Obtain Professional Assistance to Deal with Moisture Infiltration and MoldWhile your geotechnical engineer may have addressed groundwater, water infiltration, or similar issues in this report, none of the engineer’s services were designed, conducted, or intended to prevent uncontrolled migration of moisture – including water vapor – from the soil through building slabs and walls and into the building interior, where it can cause mold growth and material-performance deficiencies. Accordingly, proper implementation of the geotechnical engineer’s recommendations will not of itself be sufficient to prevent moisture infiltration. Confront the risk of moisture infiltration by including building-envelope or mold specialists on the design team. Geotechnical engineers are not building-envelope or mold specialists.

Copyright 2016 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document or its wording as a complement to or as an element of a report of any

kind. Any other firm, individual, or other entity that so uses this document without being a GBA member could be committing negligent

Telephone: 301/565-2733e-mail: [email protected] www.geoprofessional.org

report of subsurface exploration and geotechnical

Documents