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

A Minority-Owned Business

Report of Geotechnical Study

Lucks Lane Improvements Chesterfield County, Virginia

F&R Project No. 60R-0279

Prepared For:

Kimley Horn & Associates 1700 Willow Lawn Drive, Suite 200

Richmond, Virginia 23230

Prepared By: Froehling & Robertson, Inc.

3015 Dumbarton Road Richmond, Virginia 23228

September 12, 2014 Revised October 31, 2014

Kimley-Horn & Associates Lucks Lane Improvements – Chesterfield County F&R File No. 60R-0279 Revised November 12, 2014

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TABLE OF CONTENTS

SECTION PAGE

EXECUTIVE SUMMARY ........................................................................................................... 1

1.0 PURPOSE & SCOPE OF SERVICES .................................................................................. 2

2.0 PROJECT INFORMATION .............................................................................................. 2

2.1 PROPOSED CONSTRUCTION ............................................................................................. 2

2.2 SITE DESCRIPTION ......................................................................................................... 3

3.0 EXPLORATION PROCEDURES ........................................................................................ 3

3.1 SUBSURFACE EXPLORATION ............................................................................................. 3

3.2 LABORATORY TESTING ................................................................................................... 5

4.0 REGIONAL GEOLOGY & SUBSURFACE CONDITIONS ...................................................... 5

4.1 REGIONAL GEOLOGY ...................................................................................................... 5

4.2 SUBSURFACE CONDITIONS ............................................................................................... 6

4.2.1 Surficial Soils ..................................................................................................... 6

4.2.2 Asphalt Pavement ............................................................................................. 7

4.2.3 Fill .................................................................................................................... 7

4.2.4 Residual Soils .................................................................................................... 7

4.2.5 Soft Weathered Rock ........................................................................................ 8

4.2.6 Auger Refusal Materials .................................................................................... 8

4.4 SUBSURFACE WATER ..................................................................................................... 8

4.5 LABORATORY TEST RESULTS ............................................................................................ 9

5.0 GEOTECHNICAL DESIGN RECOMMENDATIONS ............................................................. 9

5.1 GENERAL .................................................................................................................... 9

5.2 PAVEMENT DESIGN RECOMMENDATIONS .......................................................................... 10

5.3 PAVEMENT OVERLAYS.................................................................................................. 12

5.4 DRAINAGE ................................................................................................................ 13

5.5 EVALUATION OF ON-SITE SOILS FOR FILLS AND ROADWAY SUBGRADES ..................................... 14

5.6 CULVERT STRUCTURE RECOMMENDATIONS ........................................................................ 16

5.6.1 General ........................................................................................................... 16

5.6.2 Culvert Recommendations .............................................................................. 17

5.7 LATERAL EARTH PRESSURES ........................................................................................... 18

5.8 UNDERGROUND STORMWATER DETENTION BASIN .............................................................. 19

6.0 GEOTECHNICAL CONSTRUCTION RECOMMENDATIONS .............................................. 20

6.1 SITE PREPARATION ...................................................................................................... 20

6.2 SELECT FILL PLACEMENT AND COMPACTION ....................................................................... 21

6.3 LIME MODIFICATION / STABILIZATION .............................................................................. 22

6.4 CULVERT STRUCTURE CONSTRUCTION .............................................................................. 22

6.5 SURFACE WATER/GROUNDWATER CONTROL ..................................................................... 23

6.6 TEMPORARY EXCAVATION RECOMMENDATIONS ................................................................. 23

6.7 EXCAVATION CONDITIONS ............................................................................................. 24

7.0 CONTINUATION OF SERVICES .................................................................................... 25

8.0 LIMITATIONS ............................................................................................................. 26


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APPENDICES APPENDIX I Site Vicinity Map (Drawing No. 1) Boring Location Plan (Drawing No. 2 and 3) APPENDIX II Key to Soil Classification Unified Soil Classification Chart Boring Logs (10 pages) APPENDIX III

Laboratory Summary Sheet (2 pages) Standard Proctor (3 pages) CBR Results (3 pages)

APPENDIX IV ASFE Document “Important Information about Your Geotechnical Engineering Report”


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EXECUTIVE SUMMARY

This Executive Summary is provided as a brief overview of our geotechnical engineering

evaluation for the project and is not intended to replace the more detailed information

contained elsewhere in this report. As an overview, this summary inherently omits details that

could be very important to the proper application of the provided geotechnical design

recommendations. This report should be read in its entirety prior to implementation into initial

design.

The site was explored by ten (10) soil test borings performed in multiple phases

between January 21 and June 10, 2014. The borings were performed at select locations

along the proposed roadway realignment, box culvert widening, and within the

proposed storm water management basin.

Site subsurface conditions generally consist of surficial soils or asphalt pavements

underlain by residual soils, soft weathered rock and competent bedrock.

Subgrade soils may need to be improved, due to soft or loose soils, or excessive natural

moisture contents (exceeding 1.2 times the respective optimum moisture content, as

determined by the Standard Proctor tests). The subgrade soils can be improved through

various methods, including, but not limited to removal and replacement, discing and

drying, or lime modification methods.

Subsurface water is not expected to negatively impact construction for new roadway

construction, but will likely be encountered during excavations for the box culvert

widening, depending on the water level within Falling Creek at the time of construction.

Auger refusal on competent rock was encountered in the borings for the box culvert

widening and within the stormwater detention basin; therefore difficult excavation

operations should be anticipated in these areas depending on final site grades.


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1.0 PURPOSE & SCOPE OF SERVICES

The purpose of our subsurface exploration and geotechnical engineering evaluation was to explore

the subsurface conditions in the areas of the proposed Lucks Lane Improvement project, and

provide general geotechnical engineering design and construction recommendations that may be

used during the design and construction of the proposed improvements.

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

Completion of ten (10) Standard Penetration Test (SPT) borings drilled to depths

ranging from 2 to 22 feet below the existing ground surface;

Preparation of typed Boring Logs;

Performance of geotechnical laboratory testing on representative soil samples;

Performance of a geotechnical engineering evaluation of the subsurface conditions

with regard to their suitability for the proposed construction;

Preparation of this geotechnical report by professional engineers, providing

descriptions of the above noted activities, as well as providing geotechnical design

and construction recommendations.

Our scope of services did not include survey services, quantity estimates, preparation of plans or

specifications, evaluations of earthquake motions, or the identification and evaluation of wetland

or other environmental aspects of the project site.

2.0 PROJECT INFORMATION

2.1 Proposed Construction

We understand that this phase of the project consists of improving the Lucks Lane corridor

between Walton Bluff Parkway and Spirea Road (approximately 4,000 linear feet) in Chesterfield

County, Virginia. We understand the majority of improvements will be performed between

Evergreen Parkway and Amber Forest Drive, (approximately 2,600 linear feet), where Lucks Lane

will be widened from a two-lane roadway to a four-lane divided roadway. The total reconstruction

of this section of Lucks Lane will be required as the roadway will be widened on both sides and a

16-foot median will be constructed along the center-line of the roadway. Additional site

improvements will also consist of lengthening the existing box culvert over Falling Creek, as well as

the construction of a stormwater detention system along the south side of Lucks Lane, east of

Falling Creek.


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In most cases, cut and fill operations are expected to be less than three feet for much of the

roadway improvements. However, up to 8.5 feet of fill being required along the shoulders and

above the existing ditches between Station 105+00 and 107+00 and up to 7.5 feet of cut will be

performed near Amber Forest Drive and Spiria Road for turning lanes and roadway widening.

Additional cuts and fills (up to 6 feet) are expected for the stormwater management basin and (up

to 17 feet of cut) into the existing slope on the northeast side of Falling Creek (approximately

Sta.113+75 to 117+50). Recommendations and analyses for the special design retaining wall, on

the northeast side of Falling Creek, will be provided in an additional supplemental geotechnical

exploration.

Traffic loading information was provided in the drawing Lucks Lane Reconstruction Project –

Preliminary Field Inspection Plans, prepared by Kimley Horn and Associates, dated December 3,

2013. The 2036 Average Daily Traffic (ADT) volume for this section of Lucks Lane is predicted to

be 18,500 vehicles per day (vpd), with 1 percent tractor trailer truck traffic.

2.2 Site Description

The project site is located along the Lucks Lane corridor and extends from just west of Evergreen

Parkway east to Spirea Road, in Chesterfield County, Virginia, as indicated on the Site Vicinity Plan

(Drawing No. 1, Appendix I). This section of Lucks Lane is primarily a two-lane asphalt paved road

in a residential area, with partially wooded areas bordering both sides of the road. Lucks Lane

traverses over Falling Creek via a box culvert, approximately 350 feet east of its intersection with

Evergreen Parkway.

3.0 EXPLORATION PROCEDURES

3.1 Subsurface Exploration

The exploration program was performed in multiple phases between January 21 and June 10, 2014

due to site access restrictions from property owners and additional underground utility marking

operations after Boring B-3 was drilled through a water line that was not detected during standard

Miss Utility marking operations. The exploration consisted of ten (10) SPT soil test borings

(designated B-1 through B-5, BC-1, BC-2 and P-1 through P-3. Borings B-1 through B-5 were drilled

within the proposed widening, to depths ranging from 1.4 feet to 8 feet. Borings B-2 and B-3 were

terminated at depths of 4 feet and 1.4 feet, respectively, due to the presence of underground

utilities. Borings BC-1 and BC-2 were drilled to depths of 22 and 19 feet, respectively, for the box

culvert widening. Borings, P-1, P-2 and P-3 were drilled to 5 to 20 feet for the proposed

stormwater management basin. The boring locations were selected and staked in the field by F&R


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personnel, using a hand-held GPS unit and by measuring from existing features. The approximate

locations of the borings are shown on the Boring Location Plans (Drawing Nos. 2 and 3) included in

Appendix I. The boring locations shown on the attached Boring Location Plan should be

considered approximate.

The soil test borings were performed in accordance with generally accepted practice using an ATV-

mounted CME-55 rotary drill rig, equipped with an automatic hammer. Steel Casing and Hollow-

stem augers were advanced to pre-selected depths, the center plug was removed, and

representative soil samples were recovered with a standard split-spoon sampler (1 3/8 in. ID, 2 in.

OD) in general accordance with ASTM D 1586, the Standard Penetration Test. For these tests, a

weight of 140 pounds was freely dropped from a height of 30 inches to drive the split-spoon

sampler into the soil. The number of blows required to drive the split-spoon sampler three or four

consecutive 6-inch increments was recorded, and the blows of the second and third increments

were summed to obtain the Standard Penetration Resistance (N-value). The N-value provides a

general indication of in-situ soil conditions and has been correlated with certain engineering

properties of soils.

An automatic hammer was used to perform the Standard Penetration Test (SPT) on this project.

Research has shown that the Standard Penetration Resistance (N-value) determined by an

automatic hammer is different than the N-value determined by the safety hammer method. Most

correlations that are published in the technical literature are based on the N-value determined by

the safety hammer method. This is commonly termed N60 as the rope and cathead with a safety

hammer delivers about 60 percent of the theoretical energy delivered by a 140-pound hammer

freely falling 30 inches. Several researchers have proposed correction factors for the use of

hammers other than the safety hammer to correct the values to be equivalent to the safety

hammer SPT N60-values. The correction is made using the following equation:

N60 = Nfield x CE

Nfield is the value recorded in the field and CE is the energy ratio for the hammer utilized in the field.

The guidelines provided in the Performance and Use of the Standard Penetration Test in

Geotechnical Engineering Practice manual, published by the Center for Geotechnical Practice and

Research at the Virginia Polytechnic Institute and State University, recommend that a correction

factor (CE) be used to covert Nfield values to N60 values, when using an automatic hammer. The N-

values reported on the Boring Logs included in this report are the actual, uncorrected, field derived

values (Nfield). It is recommended that corrected N60 values be used for engineering analysis. We

recommend that a correction factor (CE) of 1.32 be used to convert Nfield values to N60 values for

the particular machine used for this investigation.


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Rock encountered at Borings BC-1 and BC-2 and was cored at depths 17 to 22 feet and 14 to 19

feet, respectively. The rock was cored using a high-recovery barrel advanced with a diamond

impregnated cutting head in general accordance with ASTM D 2113 (Practice for Diamond Core

Drilling for Site Investigation).

Prior to demobilization, the boreholes were backfilled with auger cuttings, with borings performed

within the roadway being patched with cold mix asphalt patch. Periodic observation of the

backfilled boring should be performed, as the boring backfill could settle over time resulting in

subsidence of the ground around the borehole.

Representative portions of the split-spoon and bulk soil samples collected throughout the

exploration program were placed in glass jars and bags, respectively, and were transported to our

laboratory. In the laboratory, the soil samples were evaluated by a member of our engineering

staff, in general accordance with techniques outlined in the visual-manual identification procedure

(ASTM D 2488). The soil descriptions and classifications discussed in this report and shown on the

attached Boring Logs are based on visual observation and should be considered approximate.

Copies of the boring logs, as well as classification procedures are provided in Appendix II.

Soil samples recovered from this project will be stored at F&R’s office for a period of 60 days. The

samples will be discarded after 60 days, unless prior notification is provided to us in writing.

3.2 Laboratory Testing

In addition to soils classified using the visual/manual method, select soil samples were subjected

to Gradation (VTM 25), Atterberg Limits (VTM 7), and Water Content (ASTM D 2216) testing to

substantiate the visual classifications and assist with the estimation of the soils’ pertinent

engineering properties. Standard Proctor (VTM 1) and California Bearing Ratio (CBR) (VTM 8) tests

were also performed on bulk samples for use in pavement design recommendations. The

laboratory testing results are discussed in Section 4.5 of this report and are also included in

Appendix III.

4.0 REGIONAL GEOLOGY & SUBSURFACE CONDITIONS

4.1 Regional Geology

The project site lies within the extreme eastern edge of the Piedmont Physiographic Province, the

largest physiographic province in Virginia. It is bounded on the east by the Fall Zone, which

separates the Piedmont from the Coastal Plain, and on the west by the mountains of the Blue

Ridge Province. The Piedmont Province is characterized by gently rolling topography, deeply-


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weathered bedrock, and relatively rare solid bedrock outcrops. Rock is strongly weathered in the

Piedmont's humid climate and bedrock is generally buried under a blanket of saprolite (thoroughly

decomposed rock), which varies in depth (from about 6 to 60 feet.) Available geologic references

report that the natural site soils comprise residual soils formed by the erosion of the underlying

saprolites and bedrock (Petersburg Granite Formation). The subsurface conditions described

below are generally representative of sites lying within the Piedmont Province.

The boundary between soil and rock is often not sharply defined. The transitional terms “Hard or

Soft Weathered Rock” are used to described the partially decomposed rock that is normally found

overlying the parent bedrock. For engineering purposes, weathered rock maintains the overall

rock structure, but can generally be penetrated by soft formation drilling equipment such as

augers and can be sampled with a split spoon sampler. Soft Weathered Rock (SWR) is described

as broken and partially weathered rock with Standard Penetration Resistance N-values between

50 blows per 6 inches and 50 blows per inch. Hard Weathered Rock (HWR) is described as broken

and partially weathered rock with N-values in excess of 50 blows per inch.

Weathering is facilitated by fractures, joints and the presence of less resistant rock types.

Consequently, the profile of the SWR or HWR is often quite irregular, even over very short

horizontal distances. Also, it is not unusual to find lenses, layers, or zones of less resistant SWR

and more resistant HWR, and boulders of hard rock within the soil mantle well above the

competent bedrock.

4.2 Subsurface Conditions

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

Boring Logs represent an estimate of the subsurface conditions based on interpretation of the

boring data using normally accepted geotechnical engineering judgments. The transitions

between different soil strata are usually less distinct than those shown on the boring logs.

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. The Boring Logs are presented in Appendix II.

4.2.1 Surficial Soils

Surficial Soil was encountered at the surface of the borings performed for the box culvert widening

(BC-1 & BC-2) and storm water management basin (P-1, P-2, P-3) to approximate depths ranging

from 0.4 to 0.9 feet (5 to 11 inches) below the existing ground surface. Surficial Soil is typically a

dark-colored soil containing roots, fibrous matter, and/or other organic components and is

generally unsuitable for engineering purposes. F&R has not performed any laboratory testing to


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determine the organic content or other horticultural properties of the observed Surficial Soil

materials. Therefore, the term Surficial Soil is used instead of “Topsoil” to indicate that the soils

have not been evaluated for their suitability for landscaping and/or other purposes. The Surficial

Soil depths provided in this report are based on field observations and should be considered

approximate. We note that the transition from Surficial Soil to underlying materials may be

gradual, and therefore the observation and measurement of Surficial Soil depths is subjective.

Actual Surficial Soil depths should be expected to vary across the site.

4.2.2 Asphalt Pavement

Borings B-1 through B-5 were performed within the Lucks Lane improvement corridor. The

borings encountered a pavement sections consisting of 6 to 8 inches of asphalt underlain by 6 to

11 inches of crushed stone. It should be noted that thicknesses were obtained from the sides of

the borehole, and therefore, these depths are considered approximate, since coring was not

performed.

4.2.3 Fill

Fill may be any material that has been transported and deposited by man. Materials described as

fill were encountered beneath the pavement section at Boring B-2 to a depth of 4 feet below the

top of pavement. The sampled fill material was described as Clayey SAND (SC) with a standard

penetration resistances (N-value) of 25 blows per foot (bpf), indicating that the soil is medium

dense in relative density.

It is possible that fill, associated with utility trench backfill, may extend to depths deeper than

those observed in the areas of Borings B-2 and B-3. These borings were terminated within fill

materials due to the presence of underground utilities being observed within the boreholes.

4.2.4 Residual Soils

Residual soils were encountered beneath the surficial soils, and extended to the borings’ planned

termination depths or to the top of soft weathered rock. Sampled residual soils typically consist of

Lean CLAYs (CL), Clayey SANDs (SC), Silty SANDs (SM), GRAVELs with Clay (GC), and Sandy SILT

(ML). The field N-values for the fine-grained soils (CLAYs and SILTs) ranged from 5 to 45 blows per

foot (bpf), with the majority below 16 bpf, indicating that these soils are firm to hard in

consistency. Field N-values ranging from 1 to 33 bpf were measured within the coarse-grained

soils (SANDs), indicating these soils have a very loose to dense relative density.


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4.2.5 Soft Weathered Rock

Soft Weathered Rock (SWR) is a transitional material between soil and rock which contains the

relict rock structure, with very hard consistencies or very dense densities. SWR materials were

encountered beneath the residual soils and extend to the top of auger refusal materials in Borings

BC-1, BC-2, P-1 and P-3. When sampled, the SWR broke into Silty SAND (SM) or GRAVEL with Clay

(GC) with penetration resistances ranging from 50/5” to 50/0”.

4.2.6 Auger Refusal Materials

Auger refusal occurs when materials are encountered that cannot be penetrated by the soil auger

and is normally indicative of a very hard or very dense material, such as boulders, rock lenses, rock

pinnacles, or the upper surface of competent bedrock, which is what we encountered at this site.

Auger refusal was encountered in Borings BC-1, BC-2, P-1 and P-3, at depths ranging from 5 to 17

feet below existing site grades. Auger refusal conditions with a CME 55 do not necessarily indicate

conditions impenetrable to other equipment. Auger refusal conditions will likely vary in

unexplored areas of the site.

Competent bedrock was sampled from Borings BC-1 and BC-2 between 14 feet and 22 feet.

Sampled rock was classified as Petersburg Granite and was characterized by a white, black and

pink color, fresh to slight weathering, and moderate to slight fracturing. The granites was found to

be hard and could not be gouged by a geologist’s pick with moderate effort. Recovery

percentages (REC) of the rock cores range between were 67% and 100% and the rock quality

(RQD) ranged from 60% to 62%.

4.4 Subsurface Water

The test borings were monitored during and upon completion of drilling operations to obtain

short-term subsurface water information. The subsurface water data, obtained during our

subsurface exploration, have been summarized in the following table:

Boring Boring Depth

(Feet)

Subsurface Water Depth During Drilling

(Feet)

Subsurface Water Depth Before Removal of

Augers (Feet)

Cave-in Depth (Feet)

B-1 8 Not encountered Not observed 5.7

B-2 4 Not encountered Not observed 4

B-3 1.4 Not encountered Not observed -




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Boring Boring Depth

(Feet)

Subsurface Water Depth During Drilling

(Feet)

Subsurface Water Depth Before Removal of

Augers (Feet)

Cave-in Depth (Feet)

BC-1 22 Not encountered Not observed 17

BC-2 19 Not encountered Not observed 11.2

P-1 13.6 Not encountered Not observed 12.6

P-2 20 Not encountered Not observed 17.5

P-3 5 Not encountered Not observed 2

It should be noted that the location of the subsurface water could vary by several feet because of

seasonal fluctuations in precipitation, water level within Falling Creek, evaporation, surface water

runoff, local topography, and other factors not immediately apparent at the time of this

exploration. Normally, the highest subsurface water levels occur in the late winter and spring and

lowest levels occur in the late summer and fall. It should also be noted that boreholes often cave

in where wet soil conditions, or flowing water is encountered.

4.5 Laboratory Test Results

As discussed in Section 3.2, laboratory testing was performed on representative soil samples

collected during our subsurface exploration. The results from the laboratory testing are

summarized in the table below and are included in Appendix III.

Boring No.

Sample Depth (Feet)

LL/PI(a)

%

Passing #200

Sieve(b)

%

Natural Water

Content %

Maximum Dry Density/Optimum

Moisture pcf/%

CBR @ 100%

Compaction

USCS(c)

Class. AASHTO

Class.

B-1 Bulk 29/11 34.1 -- 117.2/13.2 16.7 SC A-2-6

B-4 Bulk 48/23 49.0 -- 108.9/17.4 2.9 SC A-7-6

B-5 Bulk 35/13 46.9 -- 113.5/13.1 7.1 SC A-6

(a) Liquid Limit and Plasticity Index from Atterberg Limits test (VTM 7) (c) Unified Soil Classification System (b) Percentage of fines (silt and/or clay) from #200 Sieve Wash (VTM-25)

5.0 GEOTECHNICAL DESIGN RECOMMENDATIONS

5.1 General

The following evaluations and recommendations are based on our observations at the site,

interpretation of the field and laboratory data obtained during this exploration, and our

experience with similar subsurface conditions and projects. Soil penetration data has been used to


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develop pavement sections according to AASHTO standards. Subsurface conditions in unexplored

locations may vary from those encountered. If the structure locations, loadings, or elevations are

changed, we should be notified and requested to confirm and, if necessary, re-evaluate our

recommendations.

Selection of an appropriate pavement design is dependent on the proposed loads, soil conditions

and characteristics, and construction constraints such as proximity to other structures, pavements,

material costs and other factors. The subsurface exploration aids the geotechnical engineer in

identifying the soil strata that are appropriate for the design needs or the appropriate measures

needed to facilitate a suitable working surface. In addition, since the method of construction

greatly affects the soils intended for structural support, consideration must be given to the

implementation of suitable methods of site preparation, fill compaction, and other aspects of

construction.

5.2 Pavement Design Recommendations

The thicknesses of the recommended pavement sections are directly related to the service life, the

initial cost of placement, the preparation of the soil subgrade, and the method by which the

granular base and the pavements are placed. The following pavement sections are designed and

evaluated using the AASHTO Guide for Design of Pavement Structures 1993 (revised May 2003)

with the 2009 VDOT’s “Guidelines for Use of the 1993 AASHTO Pavement Design Procedure.”

The table below summarizes the parameters for our pavement designs for new pavement

construction. If the traffic loads differ from the numbers used for our design, F&R should be

notified so that we can adjust our pavement design recommendations, as necessary. To reduce

the amount of potentially unsuitable soils (See Section 5.5 for further details) along the proposed

roadway due to the low CBR criterion, we have provided pavement design sections below based

upon a Design CBR (DCBR) value of 4.7. This DCBR value was calculated by taking 2/3 of the

second lowest laboratory determined CBR value. Subsequently, all final subgrades within the

pavement area should be carefully evaluated by the geotechnical engineer for their suitability for

pavement and/or new fill support. If encountered in pavement areas, any unsuitable materials

should be undercut and either replaced with engineered fill or re-compacted in accordance with

the recommendations of this report.

Design Parameter Lucks Lane

2012 Two-Way Traffic Volume (ADT) Vehicles per day

13,700

2036 Two-Way Traffic Volume (ADT) Vehicles per day

18,500


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Design Parameter Lucks Lane

Tractor Truck Traffic 1%

Single Unit Truck Traffic 1%

Growth Rate 1.26%

Directional Factor 53%

Lane Distribution Factor 100%

The following flexible pavement sections are recommended for portions of the road where new

pavement will be placed. Two pavement alternatives have been provided for the new road

sections. The alternatives include thickening the asphalt base course, or thickening the gravel

subbase course.

Based upon the factors provided above, our evaluation of the existing pavement section indicates

that it will be sufficient to provide the required support for the anticipated traffic with the current

soil conditions.

5.3 Temporary Pavements

We also understand that temporary pavement sections will be used along this section of Lucks

Lane and Evergreen Parkway during this phase. The following flexible pavement section is

recommended for sections where temporary pavement construction is planned. Our design

Recommended Flexible Pavement Design Alternative 1

Layer VDOT Specification Thickness (Inches)

Surface Course Asphalt Concrete

(SM-9.5 or SMA-9.5) 1.5

Intermediate Course Asphalt Concrete (IM-19.0) 2.0

Base Course Asphalt Concrete (BM-25.0) 4.0

Sub-Base Untreated Dense-graded

Aggregate Material No. 21B 6.0

Recommended Flexible Pavement Design Alternative 2


Surface Course Asphalt Concrete

(SM-9.5 or SMA-9.5) 1.5


Base Course Asphalt Concrete (BM-25.0) 3.0




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uses the same parameters listed in the previous section, except that the design life was reduced

to 6 months.

5.4 Pavement Overlays

In addition to replacing or re-aligning the roadway, we anticipate that some of the existing

pavement may be left in place and overlain. If existing asphalt pavement sections are to be left in

place and an overlay is to be used, we recommend milling 1.5 inches of the existing asphalt

pavement, followed by overlaying with a minimum of 2 inches of new SM-9.5 or SMA-9.5. It

should be noted that deeper milling may be required, depending on the condition of the existing

asphalt pavement, the thickness of existing pavement section, and final design grades.

If not directly addressed, it is our opinion that existing cracks will reflect through an overlay within

one to two years after the placement of the new pavement. We also believe that the existing

pavements may separate from the new pavement, resulting in joint cracks within the same time

frame. In order to reduce the likelihood of this type of cracking, we recommend that a

geosynthetic pavement reinforcement, such as HaTelit by Huesker, be installed between the

existing pavement and the overlay, where existing cracks are observed in the milled pavement,

and along joints between the existing pavement and newly placed pavement. The pavement

reinforcement consists of a bitumen-coated polyester grid that bonds between the asphalt layers,

takes the tensile forces and redistributes them over a larger area. This serves to reduce the

potential for reflective cracking in the asphalt surface. The product should be installed along

cracks and joints in accordance with manufacturer’s guidelines, and particular attention must be

given to surface preparation. Also, it must be understood that while this product is intended for

use over cracked pavements, severely broken and loose asphalt or potholed areas will still likely

require complete replacement.

Based upon brief site visits, the existing pavement appears to be in fair condition. Therefore, we

do not anticipate that the entire reconstructed length will need reinforcement. The need and

extent of the pavement reinforcement should be determined in the field by a qualified engineer,

once the existing road surface has been milled. Performance of a detailed pavement condition

survey, and the identification of such areas was not within F&R’s current scope of services.

Temporary Pavements






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5.5 Drainage

An important consideration with the design and construction of pavements is surface and

subsurface drainage. Where standing water develops, softening of the subgrade and other

problems related to the deterioration of the pavement or failures can be expected. Furthermore,

good drainage should reduce the possibility of the subgrade materials becoming saturated over a

long time. Based upon the results of the soil test borings, we do not expect that subsurface water

will affect the performance of pavements; however, infiltrating surface water may become

trapped within the pavement subbase, above the underlying fat clays and clayey sands. The use of

underdrains or a drainage layer along the edges of the pavement will assist in decreasing the

deteriorating effect of water on the subgrades and premature failure of the pavement sections.

The potential for standing water that may develop on the surface of the pavement may be

reduced by:

adequate design (surface graded to control runoff to desired locations - catch

basins, drain inlets, gutters, etc.);

adequate compaction of each lift of pavement section component material (to

minimize localized settlements that result in ponding);

accurate grading of each lift of pavement section component material (to achieve

the desired design grades);

installing temporary weep holes in drainage structures, construction of drainage swales

and diversion ditches and proper backfill and grading behind curbs to minimize water

intrusion from behind the curbs.

We note that the following guidelines are found in the Guidelines For 1993 AASHTO Pavement

Design:

1) When Aggregate Base Material, Type I, Size #21-B is used as an untreated base or

subbase, it should be connect to a longitudinal pavement drain (UD-4) with outlets or

daylighted (to the face of the ditch) to provide for positive lateral drainage on all

roadways with a design ADT of 1,000 vehicles per day or greater. (Refer to the current

VDOT Road and Bridge Standards for installation details.) Other drainage layers can also

be used.

2) Undercutting, transverse drains, stabilization, and special design surface and subsurface

drainage installations, should be considered whenever necessary to minimize the

adverse impacts of subsurface water on the stability and strength of the pavement

structure.


Page - 14 -

3) Standard CD-1 and CD-2 should be considered for use with all types of unstabilized

aggregates, independent of the traffic levels.

We recommend that pavement underdrains be designed and installed beneath new

pavements, in accordance with guidelines contained in VDOT’s Road and Bridge Standards and

Drainage Manual. However, construction during wet seasonal conditions (typically November

through May) with heavy precipitation may result in a perched groundwater table or softening

of the soils at the surface. Additional underdrains may be required based on prevailing

conditions during construction that were not evident during our subsurface exploration.

5.6 Evaluation of On-Site Soils for Fills and Roadway Subgrades

The suitability of potential fill materials has been evaluated by conducting a series of laboratory

tests. Particle size gradation (sieve) analyses and Atterberg Limits test were conducted to provide

data for classification of the soils. Standard Proctor tests were performed to evaluate the range of

the optimum moisture contents of on-site soils. Moisture content tests were then performed to

identify potentially unsuitable soil due to excessive moisture. Our evaluation of potentially

unsuitable soils was based on the following criteria:

Soils with measured excessive natural moisture contents (those having natural moisture

contents that are at least 1.2 times the respective optimum moistures determined by

Standard Proctor tests)

Relatively soft soils (SPT resistance values, Nfield, less than 5 blows per foot)

High plasticity soils (LL>40 and PI>20) (most commonly CH and MH soils)

Low CBR values (Soaked CBR < 7)

Based on the laboratory test results, the majority of the soils in the vicinity of the project area

appear to be suitable for use as compacted fills and pavement subgrade soils. Laboratory test

results indicated that the majority of the soils tested to be suitable based on the range of LL and PI

Values obtained. The onsite near-surface soils may require moisture conditioning to reduce

moisture to within acceptable range. The zone of potentially unsuitable soils along with estimated

depths of treatment and our recommended treatment alternatives are presented in the table

below.

We recommend that these areas be denoted on the plans in order to assist the contractor and on-

site inspectors in identifying areas of potentially unsuitable soils. We recommend that the

unsuitable zones be extended beyond the toes of embankment fill slopes to a distance equal to


Page - 15 -

two times the depth of unsuitable soils below the top of existing grade. The zones and depths of

potentially unsuitable soils identified in this report, or lack thereof, should only be considered as

an aid in identifying actual unsuitable soils during construction. Actual areas and depths of

unsuitable materials should be identified in the field by the on-site inspection team during

construction. Zones of high plasticity soils are not expected to be encountered along the entire

length of the project. As such, we recommend that the onsite inspection team evaluation the

roadway subgrade in order to verify that the anticipated subgrade material is of suitable nature.

Begin Station

End Station

Approx. Cut or Fill Depth to

Proposed Grade

(ft)

Nearest Boring

Thickness of Unsuitable Material,

from Existing Grade (ft)

Reason for Unsuitable Material* (A,B, C, D)

Recommended Alternatives**

(E,F, G, H)

108+00 114+00 <1 B-1, B-2 2 B E,F,G

114+00 118+00 3 Cut B-2, B-3 2 B E,F,G

118+00 121+50 <1 B-3 2 B E,F,G

121+50 126+50 <1 B-4 2 A,B,D E or H

126+50 130+00 <1 B-5 2 B E,F,G

Unsuitable Reasoning

o A: Plasticity (LL>40, PI>20) o B: Excessive Moisture (>1.2 times the optimum moisture from the Standard Proctor

Test) o C: Low strength material (N-Value < 5 blows per foot) o D: Low CBR value

Remediation Options

o E: Undercut and replace o F: Scarify and dry in-place, recompact o G: Lime Modification o H: Lime Stabilization

Note

The recommendations above are based on the assumption that prior to filling operations, the

site will be prepared in accordance with the recommendations provided in Section 6.1 of this

report.

Depending on their plasticity and sand contents, excessively moist soils may be acceptable for use

as fill material if carefully evaluated at the time of construction and allowed to dry or treated to

bring the moisture content to within an acceptable range (less than 1.2 times the optimum

moisture content). Finer grained soils (Clays and Silts) are generally more sensitive to variations in

moisture content and can become “unsuitable” if they are exposed and/or contain excessive

moisture at the time of construction. While these soils still may be suitable for use as fill, they may


Page - 16 -

require additional working or treatment in order to adjust moisture contents to within acceptable

levels. This might be accomplished by spreading, discing and drying. However, another alternative

is to apply a small percentage of lime (typically 1 to 3 percent of lime by weight) to dry these soils

(lime modification) and reduce the moisture contents to within acceptable range.

High-plasticity soils (LL>40) were encountered in the near surface soils of Boring B-4. We

recommend that they be excavated to a minimum of 2 feet below the top of subgrade and

replaced with VDOT Select material, Type II (having a minimum CBR of 7); the excavated materials

should not be used for embankment fill. The replacement of over excavated materials should

follow the recommendations for compacted fill placement in Section 6.2. If excavated materials

consist of high plasticity and/or low CBR material, lime stabilization may be feasible to reduce the

plasticity and/or increase the CBR in order to reuse this material in fill areas. The quantity of lime

required should be determined by laboratory testing, and the results and proposed method of

mixing should be provided to Chesterfield County for approval prior to construction if lime

modification or stabilization is to be attempted. See Section 6.3 for further information regarding

lime modification/stabilization. If left untreated, materials identified as unsuitable based only on

low CBR values should not be used within 3 feet of the top of subgrade but may be suitable if

placed in deeper areas of the proposed roadway.

5.7 Culvert Structure Recommendations

5.7.1 General

The geotechnical design of the box culvert structure widening, which passes over Falling Creek, is

discussed in the following paragraphs. For each component of the structure the following

recommendations apply.

Subsurface water will likely be encountered at the culvert, pending the water level within Falling

Creek at the time of construction. The contractor should, be prepared to dewater any excavations

by means of a sump pit and pump if surficial or perched water does enter the excavation. Water

that is allowed to remain in the excavations may deteriorate the soils and compromise the bearing

integrity.

After the excavations have been performed, we recommend that a geotechnical engineer or

his/her representative verify the soils are suitable for support of the proposed loads. This can be

done visually and with a probe. Any soft soils that are identified should be removed from the load

bearing areas and replace with Type I Select Material as specified by VDOT’s 2007 Road and Bridge

Specifications (Section 207.01).


Page - 17 -

5.7.2 Culvert Recommendations

The scope of services for this project involved evaluating the subsurface conditions in the vicinity

of the box culvert structures over Falling Creek. The subsurface conditions in the vicinity of the

selected drainage structure location was evaluated for potential excessive settlements due to

embankment fill construction above the structure that might be detrimental to the stability of the

respective structure. In general, a minimum of 8 inches of bedding material should be provided

for structures bearing on rock.

The table below summarizes the estimated undercut depths and recommended minimum bedding

thicknesses for the selected drainage structure based on the VDOT Road and Bridge Standard PB-

1. If suitable bearing materials are not encountered within 24 inches of the culvert invert

elevation, placement of a stabilization geotextile is recommended.

It may be necessary to stabilize any soft and saturated soils at the base of the excavations before

culvert bedding placement. For undercut areas, we recommend backfilling with suitable

compacted fill material in accordance with Section 6.4 of this report and capping with the

minimum recommended bedding thickness. Bedding materials should be VDOT #25 or #26

stone. In the case of areas that will be at or below the water level of an existing channel, we

recommend VDOT #57 stone be placed and wrapped in a woven subgrade stabilization geotextile

to reduce the potential for erosion of the subgrade soils beneath the pipe or culvert then capped

with a minimum of 4 inches of VDOT #25 or 26 stone to reduce point loads and provide a stiffer

base. Box culvert bedding and backfilling should be performed in accordance with VDOT Road and

Bridge Specifications Sections 205 and 302 as well as VDOT Standard PB-1.

Approx. Culvert Station

Culvert Type

and Size

Culvert Length

(ft)

Approx. Invert In Elevation

(ft)

Approx. Invert Out Elevation

(ft)

Respective Boring

Approx. Depth of

Water Below Invert

Elevation (ft)

Estimated Undercut Depth / Min. Bedding Thickness (See

Note 2) (in)

112+75 12’x10’

Box 66 194.64 BC-2 Note 1 0 to 24 / 8

112+75 12’x10’

Box 66 194.30 BC-1 Note 1 0 to 24 / 8

Notes:

1. Subsurface water was not observed during or upon completion of drilling operations at Borings BC-1 and BC-2. However, subsurface water will likely be encountered at the time of construction, pending the water level within Falling Creek.

2. Depth is relative to the respective structure invert elevations. Undercut depths are estimated. Actual undercut depths should be determined during construction and should be to firm, suitable bearing soils.


Page - 18 -

The recommendations provided in the table above are based on the short term subsurface water

information provided in Section 4.3. We recommend that long term subsurface water level

information be obtained at the onset of construction via test pits and/or temporary monitoring

wells. Based on the obtained information, the recommendations in the table above may or may

not continue to be applicable.

5.8 Lateral Earth Pressures

The following information is provided to aid in analysis of soil loads on any below-grade walls.

Earth pressures on walls below grade are influenced by structural design of the walls, conditions of

wall restraint, methods of construction and/or compaction, and the strength of the materials

being restrained. The most common conditions assumed for earth retaining wall design are the

active and at-rest conditions. Active conditions apply to relatively flexible earth retention

structures, such as freestanding walls, where some movement and rotation may occur to mobilize

soil shear strength. Walls that are rigidly restrained, such as pit and tunnel walls, should be

designed for the structure requiring the use of at-rest earth pressures.

A third condition, the passive state, represents the maximum possible pressure when a structure is

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

pressures. Because significant wall movements are required to develop the passive pressure, the

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

We recommend the following lateral earth pressure coefficients and other parameters for design

of temporary retaining or permanent below-grade walls. The crushed stone or granular soil

parameters may be used provided the backfill extends out from the bottom of the wall and within

a 45-degree slope from the base of the wall.

Design Parameters Silty SAND (SM) or More Granular Soil

VDOT No. 57 Stone

Moist unit weight of backfill 125 pcf 105 pcf

Angle of Internal Friction (ø) 30o 40o

Equivalent Fluid Unit Weight (pcf), Active 41 23

Equivalent Fluid Unit Weight (pcf), At Rest 63 38

Coefficient of Earth Pressure at Rest (Ko) 0.5 0.36

Coefficient of Passive Earth Pressure (Kp) 3.0 4.6

Coefficient of Active Earth Pressure (Ka) 0.33 0.22

Coefficient of Friction [Concrete on Soil]() 0.36 0.36


Page - 19 -

The backfill material should be extended a minimum distance equal to the wall height laterally

from the back face of the wall, or for a cantilevered wall, from the heel of the wall footing.

Our recommendations were given assuming that the ground surface above the wall is level. The

recommended equivalent fluid pressures were provided assuming that constantly functioning

drainage systems, consisting of slotted 4 inch diameter PVC pipe, are installed between walls and

crushed stone backfill to reduce the potential for buildup of hydrostatic pressures and lateral

stresses in excess of those stated. If a functioning drainage system is not installed, then lateral

earth pressures should be determined using the buoyant weight of the soil. Hydrostatic pressures

calculated with the unit weight of water (62.4 pcf) should be added to these earth pressures to

obtain the total stresses for design.

Surcharge loads should be evaluated using the appropriate active or at-rest pressure coefficients

provided above. The effect of surcharge loads should be added to the recommended earth

pressures to determine total lateral stresses.

5.9 Underground Stormwater Detention Basin

We understand that an Underground Stormwater Detention basin will be constructed along the

south side of Lucks Lane, east of Falling Creek. The detention system is anticipated to consist of

three pipes, approximately 6 feet in diameter and 150 feet long. We recommend that the

stormwater detention basin be installed in accordance with the guidelines set within Virginia

Stormwater Management Handbook, with a minimum thickness of 6 inches VDOT #57 stone for

pipe bedding considerations.

Sandy Lean CLAY (CL), Sandy SILT (ML), Clayey SAND (SC) and Silty SAND (SM) soils were typically

encountered in the borings. Laboratory soil permeability tests were not performed as part of this

exploration. However, based upon our experience with similar soils and on published correlations

to soil types, the coefficient of permeability for the CLAYs and SILTs is expected to fall within the

range of 10-6 to 10-5 cm/s (centimeters per second); and the permeability is expected to fall

between 10-5 and 10-3 cm/s for the SANDs. The CLAYs are naturally suitable for retaining storm

water; however, the SANDs are typically not considered suitable for water retention. We also note

that because the soils encountered at the site are residual, they tend to vary from being

predominantly sands to predominantly clays, both horizontally and vertically, throughout the area

of the underground stormwater detention basin. Subsequently, it should be expected that the

permeability of the soils around the detention basin could exhibit the full range of permeabilities

noted above.


Page - 20 -

For construction of the earth embankment along the south side of the underground stormwater

detention basin, we recommend the soils be compacted to at least 95 percent of the Standard

Proctor maximum dry density in order to achieve the specified coefficient of permeability, if water

retention is desired using onsite cut soils, and to achieve the desired stability of the fill slope.

Available grading information indicates that the majority of the underground detention basin will

be in cut areas, and fill placement should mostly be required for the earth embankment on the

south side of the new detention system. Our exploration did not include a detailed analysis of

slope stability for any temporary or permanent condition, as slope heights do not exceed 15 feet;

however, for these soil types, we generally recommend temporary cut slopes (above subsurface

water) no steeper than 1(H):1(V) and permanent cut or fill slopes (above subsurface water) no

steeper than 2(H):1(V). Stability analyses should be performed for any slopes designed to be

steeper than these recommendations.

6.0 GEOTECHNICAL CONSTRUCTION RECOMMENDATIONS

6.1 Site Preparation

Before proceeding with construction, the site should be cleared, and surficial soils, pavements, and

other deleterious non-soil materials should be stripped or removed from the proposed

construction area. Stripping and clearing operations should be performed in accordance with

Section 303 of VDOT’s Roadway and Bridge Specifications, hereafter referred to as “The VDOT

Specifications”. It should be noted that although only 5 to 11 inches of surficial soils were

encountered within the half of the borings, the thickness of surficial soils elsewhere within the

project limits may be greater, particularly near wetlands and roots balls. Attention should be given

to areas where any trees are to be removed from within the limits of the project site. It is our

experience that poorly cleared sites have many root systems left in place just beneath the ground

surface. The roots systems draw water from the lower levels of the soil profile and can quickly

cause the otherwise suitable subgrade soils to become very soft and wet, which can lead to the

premature deterioration of the pavement. We recommend that care be exercised to remove as

much of the root systems, within the affected project limits, as possible to reduce potential

degradation of the subgrade soils. Subsequently, we recommend that, for estimating and bidding

purposes, it be assumed that stripping will extend approximately 6 inches deeper than the

observed topsoil depths noted above.

After clearing and stripping, areas intended to support new fill, pavements and structures should

be carefully evaluated by a geotechnical engineer. At that time, the subgrade should be


Page - 21 -

proofrolled with a 20- to 30-ton loaded truck, or other pneumatic-tired vehicle of similar size and

weight, under the observation of the geotechnical engineer. Proofrolling should be performed

during a time of good weather and not while the site is wet, frozen, or severely desiccated. The

proofrolling observation is an opportunity for the geotechnical engineer to locate inconsistencies

in the existing subgrade, especially near existing utilities where fill may exist and where new fill

placement is proposed, that may not have been encountered in our borings.

6.2 Select Fill Placement and Compaction

Select fill may be required to replace undercut unsuitable soils and for grading purposes. The

select fill may be off-site borrow meeting the requirements of Type II Select Material, as presented

in Section 207.02 of the VDOT Roads and Bridges Specifications, and having a minimum laboratory

measured CBR of 7. Other materials may be suitable for use as controlled structural fill materials

and general fill to be placed outside of the road section, and should be individually evaluated by

the geotechnical engineer. Select fill should be free of boulders, cobbles, organic matter, debris,

or other deleterious materials and should have a maximum particle size no greater than 3 inches.

We recommend that select fill be compacted to at least 95 percent of the Standard Proctor (ASTM

D 698 or AASHTO T 99) maximum dry density, at a moisture content that lies between 0.8 and 1.2

times the optimum moisture content, as determined by the Standard Proctor moisture/density

test. Fill materials should be placed in horizontal lifts with maximum thickness of 8 inches loose

measure, per Section 303.4 of the VDOT Specifications. New fill should be adequately keyed into

stripped and scarified subgrade soils. During fill operations, positive surface drainage should be

maintained to prevent the accumulation of water. In confined areas, such as utility trenches,

portable compaction equipment and thin lifts of 3 to 4 inches may be required to achieve specified

degrees of compaction.

Dense graded aggregate (VDOT 21B) placed as pavement subbase course should be compacted to

100 percent of maximum dry density per ASTM D698, Standard Proctor Method.

Generally, we do not anticipate significant problems controlling moistures within approved fill

during periods of dry weather, but moisture control may be difficult during winter months or

extended periods of rain. We recommend that the contractor have equipment on site during

earthwork for both drying and wetting of fill soils. Attempts to work the soils when wet can be

expected to result in deterioration of otherwise suitable soil conditions or of previously placed and

properly compacted fill.

If construction traffic or weather has disturbed the subgrade, the upper 8 inches of soils intended

for structural or pavement support should be scarified moisture controlled, if necessary, and re-


Page - 22 -

compacted. Each lift of fill should be tested to confirm that the recommended degree of

compaction is attained. In confined areas, a greater frequency may be required.

6.3 Lime Modification / Stabilization

Lime modification refers to the modification of soil properties without significant increase in soil

support strength. Lime can modify almost all fine-grained soils, but the most dramatic

improvement occurs in clay soils of moderate to high plasticity (LL>40, PI>20), such as those

encountered at this site. By adding a certain percentage of lime (typically 1 to 3 percent, by

weight), the clay can be modified to achieve the following benefits:

Plasticity reduction

Reduction in moisture holding capacity

Swell reduction

Improved stability

The ability to construct a solid working platform

Lime stabilization occurs when a sufficient amount of lime (typically 4 to 6 percent of lime by

weight) is added to generate long-term strength gain through a pozzolanic reaction. As a result,

lime stabilization can produce long-lasting strength gains. The key to pozzolanic reactivity and

stabilization is a reactive soil, a good mix design protocol, and reliable construction practices. If

lime modification or stabilization is selected, a lime stabilization mix design should be developed

and approved. The quantity of lime required should be determined by laboratory testing, and the

results and proposed method of mixing should be provided Chesterfield County for approval prior

to construction.

6.4 Culvert Structure Construction

All bedding and foundation subgrades should be observed, evaluated, and verified for the design

bearing pressure by the geotechnical engineer after excavation and prior placement of any

structures. If weak or otherwise unsuitable soils are encountered during construction, localized

undercutting and/or in-place stabilization of bedding or foundation subgrades will be required.

The actual need for, and extent of, undercutting should be based on field observations made by

the geotechnical engineer or his/her representative at the time of construction.

Excavations should be made in such a way as to provide bearing surfaces that are firm and free of

loose, soft, wet, or otherwise disturbed soils. Foundation concrete should not be placed on frozen

or saturated subgrades. If such materials are allowed to remain below foundations, settlements

will increase. Foundation excavations should be concreted as soon as practicable after they are

excavated. If an excavation is left open for an extended period, a thin mat of lean concrete should


Page - 23 -

be placed over the bottom to minimize damage to the bearing surface from weather or

construction activities. Water should not be allowed to pond in any excavation.

In a dry and undisturbed state, the subgrade soils at the site will provide suitable subgrade support

for fill placement and construction operations. However, when wet, the soil can degrade quickly

either with or without disturbance from contractor operations. Therefore, good site drainage

should be maintained during earthwork operations to help maintain the stability of the soil.

Attempting site work during adverse seasonal conditions will have significant effect on the site

work budget, as substantially more undercutting will be required. Ideally, earthwork should be

performed during the summer or early fall (typically drier and warmer months).

6.5 Surface Water/Groundwater Control

Subsurface water, for the purposes of this report, is defined as water encountered below the

existing ground surface. Based on the subsurface water data obtained during our exploration

programs, we anticipate that subsurface water could be encountered during earthwork and

shallow excavations if done during wet periods of the year, especially within the immediate area of

Falling Creek. The contractor should be prepared to dewater excavations due to perched water

seepage or surface water entering them, particularly near the sites’ streams and wetlands.

Dewatering should be done in a manner that will not disturb the subgrade soils and will provide a

firm and stable subgrade. During the construction, we recommend that steps be taken to enhance

surface flow away from any excavations and promote rapid clearing of rainfall and runoff water

following rain events. It should be incumbent on the contractor to maintain favorable site

drainage during construction to reduce deterioration of otherwise stable subgrades.

6.6 Temporary Excavation Recommendations

Mass excavations and other excavations required for construction of this project must 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 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 the excavation 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


Page - 24 -

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”.

6.7 Excavation Conditions

Auger refusal materials were only encountered in Borings BC-1, BC-2, P-1 and P-3, at approximate

depths between 5 and 17 feet (EL 188 to 203 feet). Based on the foregoing, difficult excavation

conditions should be anticipated on this site for construction of the storm water detention system

and box culvert widening. F&R notes that the profile of the bedrock surface will likely be irregular

and variable, and that bedrock could be encountered at higher, or lower, elevations between test

boring locations.

In mass excavations for general site work, hard or dense soils (soils with standard penetration

resistances of 30 or more blows per foot) can usually be removed by ripping with a single-tooth

ripper attached to a large crawler tractor, or by breaking it out with a tracked excavator or large

front-end loader. In confined excavations such as foundations, utility trenches, etc., removal of

partially weathered rock typically requires use of large backhoes, pneumatic spades, hoe rams or

pre-drilling and splitting.

The definition of rock can be a source of conflict during construction. The following definitions

have been incorporated into specifications on other projects and are provided for your general

guidance:

GENERAL EXCAVATION:

Rip Rock - Any material that cannot be removed by scrapers, loaders, pans,

dozers, or graders; and requires the use of a single-tooth ripper

mounted on a crawler tractor having a minimum draw bar pull rated

at not less than 56,000 pounds.

Blast Rock - Any material which cannot be excavated with a single-tooth ripper

mounted on a crawler tractor having a minimum draw bar pull rated

at not less than 56,000 pounds (Caterpillar D-8K or equivalent) or by a

Caterpillar 977 front-end loader or equivalent; and occupying an

original volume of at least one (1) cubic yard.

TRENCH EXCAVATION:

Blast Rock - Any material which cannot be excavated with a backhoe having a

bucket curling force rated at not less than 25,700 pounds (e.g.


Page - 25 -

Caterpillar Model 315 or equivalent), and occupying an original

volume of at least one-half (1/2) cubic yard.

7.0 CONTINUATION OF SERVICES

We recommend that we be given the opportunity to review the foundation plan, grading plan, and

project specifications when construction documents approach completion. This review evaluates

whether the recommendations and comments provided herein have been understood and

properly implemented. We also recommend that Froehling & Robertson, Inc. be retained for

professional and construction materials testing services during construction of the project. Our

continued involvement on the project helps provide continuity for proper implementation of the

recommendations discussed herein.

As he Geotechnical Engineer of Record, F&R should be retained to monitor and test earthwork

activities, and subgrade preparations for any fill and pavement sections. It should be noted that

the actual soil conditions may 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. We recommend that F&R be employed

to monitor the earthwork and pavement construction, and to report that the recommendations

contained in this report are completed in a satisfactory manner. Our involvement with 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;

Provide additional guidance for full depth reclamation, if used; and

Observe any fill placement for compliance with the geotechnical recommendations.

These services are not included in our current scope of services and can be rendered for an

additional cost. It should also be noted that the pavement design was based on standard

knowledge of materials and their relative costs. Additional value may be obtained by further

optimization of the pavement section based on actual material and labor costs as the construction

of the project approaches.


Page - 26 -

8.0 LIMITATIONS

This report has been prepared for the exclusive use of Kimley Horn & Associates, or their agent, for

specific application to the Lucks Lane Improvements project, in accordance with generally

accepted soil and foundation engineering practices. No other warranty, express or implied, is

made. Our evaluations and recommendations are in nature and based on design information

furnished to us and assumed by us; the data obtained from the previously described subsurface

exploration program, and generally accepted geotechnical engineering practice.

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

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

please review this ASFE information.

Once site design for the project is determined, we recommend that a project specific exploration

be performed to better define geotechnical issues. If this report is copied or transmitted 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

Froehling & Robertson, Inc. SITE VICINITY MAP

Drawing No. 1

Project No: 60R-0279 Client: Kimley Horn & Associates Project: Lucks Lane Improvements City/State: Chesterfield County, Virginia

Source: DeLorme Scale: Not to Scale Date: September 2014

Approximate

Site Location

Spirea Road

Evergreen

Parkway

Froehling & Robertson, Inc. Drawing No. 2


Source: Kimley Horn Scale: Not to Scale Date: September 2014

BORING LOCATION PLAN

- Approximate Boring Location

B-1

B-4

B-3

B-2

P-3

BC-1

BC-2

P-1

P-2

Evergreen

Parkw

ay

Glad

ston

e Glen

Place

Smo

ketree Parkw

ay

Falling C

reek

Falling C

reek

Froehling & Robertson, Inc. Drawing No. 3


Source: Kimley Horn Scale: Not to Scale Date: September 2014

BORING LOCATION PLAN

- Approximate Boring Location

B-1

B-4

B-3

B-5

Spirea R

oad

Smo

ketree Parkw

ay

APPENDIX II

COARSE-GRAINED SOILS Well-graded gravelE

Poorly graded gravelE

Silty gravelE,F,G

Clayey gravelE,F,G

Well-graded sandI

Poorly graded sandI

Silty sandF,G,I

Clayey sandF,G,I

FINE-GRAINED SOILS Lean clayK,L,M

SiltK,L,M

Organic clayK,L,M,N

Organic siltK,L,M,O

Fat clayK,L,M

Elastic siltK,L,M

Organic clayK,L,M,P

Organic siltK,L,M,Q

HIGHLY ORGANIC SOILS Peat

A Based on the material passing the 3-in. (75-mm) sieve. G If fines are organic, add "with organic K If soil contains 15 to < 30 % plus No. 200, addB If field sample contained cobbles or boulders, or both, fines" to group name. "with sand" or "with gravel", whichever is

add "with cobbles or boulders, or both" to group name. H Sands with 5 to 12 % fines require dual predominant.C Gravels with 5 to 12 % fines require dual symbols: symbols: L If soil contains ≥ 30 % plus No. 200,

GW-GM well-graded gravel with silt SW-SM well-graded sand with silt predominantly sand, add "sandy" to

GW-GC well-graded gravel with clay SW-SC well-graded sand with clay group name.

GP-GM poorly graded gravel with silt SP-SM poorly graded sand with silt M If soil contains ≥ 30 % plus No. 200,

GP-GC poorly graded gravel with clay SP-SC poorly graded sand with clay predominantly gravel add "gravelly" to D I If soil contains ≥ 15 % gravel, add "with group name.

gravel" to group name. N PI ≥ 4 and plots on or above "A" line.E If soil contains ≥ 15 % sand, add "with sand" J If Atterburg limits plot in hatched area, O PI < 4 or plots below "A" line.

to group name. soil is a CL-ML, silty clay. P PI plots on or above "A" line.F If fines classify as CL-ML, use dual symbol GC-GM, Q PI plots below "A" line.

or SC-SM.

OL

Clean Sands

(Less than 5% finesH)

Sands with fines

(More than 12% finesH)

Inorganic

Organic

CHInorganic

Fines classify as CL or CH

ML

MH

SP

SM

SC

CL

Organic

Primarily orgainic matter, dark in color, and organic in odor

Cu ≥ 4 and 1 ≤ Cc ≤ 3D

Cu < 4 and/or [Cc < 1 or Cc > 3]D

Fines classify as ML or MH

Fines classify as CL or CH

Cu ≥ 6 and 1 ≤ Cc ≤ 3D

Cu < 6 and/or [Cc < 1 or Cc > 3]D

Fines classify as ML or MH

Soil Classification

Group

Symbol

GW

GP

GM

OH

PT

Silts and Clays

Liquid limit 50 or

more

Group NameB

PI < 4 or plots below "A" lineJ

PI > 7 and plots on or above "A" lineJ

GC

SW

Criteria for Assigning Group Symbols and Group Names Using Laboratory TestsA

Clean gravels

(Less than 5% finesC)

Gravels with fines

(More than 12% finesC)

FROEHLING & ROBERTSON, INC.

Engineering Stability Since 1881

CLASSIFICATION OF SOILS FOR ENGINEERING PURPOSES

ASTM Designation: D 2487 (Based on the Unified Soil Classification System)

More than 50% retained on the No. 200 sieve

50% or more passes the No. 200 sievePI plots on or above "A" line

PI plots below "A" line

Gravels

(More than 50%

of coarse fraction

retained on No. 4

sieve)

Sands

(50% or more of

coarse fraction

passes No. 4 sieve)

Silts and Clays

Liquid limit less

than 50 Liquid limit − oven dried

Liquid limit − not dried < 0.75

Liquid limit − oven dried

Liquid limit − not dried < 0.75

Cu = 𝐷60

𝐷10

Cc = 𝐷

302

𝐷10

𝑋 𝐷60

KEY TO BORING LOG SOIL CLASSIFICATION

Particle Size and Proportion

Visual descriptions are assigned to each soil sample or stratum based on estimates of the

particle size of each component of the soil and the percentage of each component of the soil.

Particle Size

Descriptive Terms

Proportion

Descriptive Terms

Soil Component Particle Size Component Term Percentage

Boulder > 12 inch Major Uppercase Letters > 50%

Cobble 3 - 12 inch (e.g., SAND, CLAY)

Gravel-Coarse 3/4 - 3 inch

-Fine #4 - 3/4 inch Secondary Adjective 20% - 50%

Sand-Coarse #10 - #4 (e.g., sandy, clayey)

-Medium #40 - #10

-Fine #200 - #40 Minor Some 15% - 25%

Silt (non-cohesive) < #200 Little 5% - 15%

Clay (cohesive) < #200 Trace 0% - 5%

Notes:

1. Particle size is designated by U.S. Standard Sieve Sizes

2. Because of the small size of the split-spoon sampler relative to the size of gravel, the true percentage of gravel

may not be accurately estimated.

Density or Consistency

The standard penetration resistance values (N-values) are used to describe the density of

coarse-grained soils (GRAVEL, SAND) or the consistency of fine-grained soils (SILT, CLAY).

Sandy silts of very low plasticity may be assigned a density instead of a consistency.

DENSITY CONSISTENCY

Term N-Value Term N-Value

Very Loose 0 - 4 Very Soft 0 - 1

Loose 5 - 10 Soft 2 - 4

Medium Dense 11 - 30 Firm 5 - 8

Dense 31 - 50 Stiff 9 - 15

Very Dense > 50 Very Stiff 16 - 30

Hard > 30

Notes:

1. The N-value is the number of blows of a 140 lb. Hammer freely falling 30 inches required to drive a standard

split-spoon sampler (2.0 in. O.D., 1-3/8 in. I.D.) 12 inches into the soil after properly seating the sampler 6

inches.

2. When encountered, gravel may increase the N-value of the standard penetration test and may not accurately

represent the in-situ density or consistency of the soil sampled.

F:\Branch 62\GEOWORD\REPORTS\keyblsc.enc.doc

LETTERGRAPH

SYMBOLSMAJOR DIVISIONS

SOIL CLASSIFICATION CHART

OH

CH

MH

OL

CL

ML

SC

SM

SP

COARSEGRAINED

SOILS

SW

TYPICAL

DESCRIPTIONS

WELL-GRADED GRAVELS, GRAVEL -SAND MIXTURES, LITTLE OR NOFINES

POORLY-GRADED GRAVELS,GRAVEL - SAND MIXTURES, LITTLEOR NO FINES

SILTY GRAVELS, GRAVEL - SAND -SILT MIXTURES

GC

GM

GP

GW

CLAYEY GRAVELS, GRAVEL - SAND -CLAY MIXTURES

WELL-GRADED SANDS, GRAVELLYSANDS, LITTLE OR NO FINES

POORLY-GRADED SANDS,GRAVELLY SAND, LITTLE OR NOFINES

SILTY SANDS, SAND - SILTMIXTURES

CLAYEY SANDS, SAND - CLAYMIXTURES

INORGANIC SILTS AND VERY FINESANDS, ROCK FLOUR, SILTY ORCLAYEY FINE SANDS OR CLAYEYSILTS WITH SLIGHT PLASTICITY

INORGANIC CLAYS OF LOW TOMEDIUM PLASTICITY, GRAVELLYCLAYS, SANDY CLAYS, SILTYCLAYS, LEAN CLAYS

ORGANIC SILTS AND ORGANICSILTY CLAYS OF LOW PLASTICITY

INORGANIC SILTS, MICACEOUS ORDIATOMACEOUS FINE SAND ORSILTY SOILS

INORGANIC CLAYS OF HIGHPLASTICITY

ORGANIC CLAYS OF MEDIUM TOHIGH PLASTICITY, ORGANIC SILTS

CLEANGRAVELS

GRAVELS WITHFINES

CLEAN SANDS

(LITTLE OR NO FINES)

SANDS WITHFINES

LIQUID LIMITLESS THAN 50

LIQUID LIMITGREATER THAN 50

GRAVELAND

GRAVELLYSOILS

FINEGRAINED

SOILS

SANDAND

SANDYSOILS

SILTSAND

CLAYS

SILTSAND

CLAYS

MORE THAN 50%OF COARSEFRACTION

RETAINED ON NO.4 SIEVE

MORE THAN 50%OF COARSEFRACTION

PASSING ON NO.4 SIEVE

MORE THAN 50%OF MATERIAL ISSMALLER THANNO. 200 SIEVE

SIZE

MORE THAN 50%OF MATERIAL ISLARGER THANNO. 200 SIEVE

SIZE

(LITTLE OR NO FINES)

(APPRECIABLEAMOUNT OF FINES)

(APPRECIABLEAMOUNT OF FINES)

NOTE: DUAL SYMBOLS ARE USED TO INDICATE BORDERLINE SOIL CLASSIFICATIONS

EXISTING FILL FILL EXISTING FILL MATERIALS

Subsurface water was notencountered duringdrilling operations.

Subsurface water was notobserved upon removal ofaugers.

Cave in depth was 5.7feet.

Boring was offset 80 feeteast due to overheadpower lines.

14

18

7

2.0

4.0

6.0

8.0

5-6-8-12

5-7-11-13

4-3-4-5

7 Inches Asphalt10 Inches Crushed Stone

RESIDUUM: Medium Dense to Loose, Brownand White, Clayey Fine to Medium SAND, littleSilt, trace Gravel - Moist

(SC)

Boring terminated at 8 feet.Boring backfilled upon completion.

223.4222.4

216.0

0.61.6

8.0

0.0

2.0

4.0

6.0

Driller: Corey Sequist

SampleDepth(feet)

Description of Materials(Classification)

Date Drilled: 6/9/14

Drilling Method: HSA 2-1/4" IDHammer Type: Automatic

Froehling & Robertson, Inc.

Client: Kimley Horn & Associates

*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.

City/State: Chesterfield County, VirginiaProject: Lucks Lane Improvements

Boring Location: See Boring Location Plan

BORING LOGBoring: B- 1 (1 of 1)

N-Value(blows/ft)

Elevation: 224 ±Total Depth: 8.0'

Project No: 60R-0279

Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60R

-027

9.G

PJ F

&R.

GD

T 9

/11/

14



Cave in depth was 4 feet.

254.0

10-11-14-12


FILL: Medium Dense, White and Brown, ClayeyFine SAND, little Silt - Moist

(SC-FILL)

Auger refusal at 4 feet on possible utiltiy line orbridge culvert.

Boring backfilled upon completion.

211.5210.6

208.0

0.51.4

4.0

2.0


SampleDepth(feet)










N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60R

-027

9.G

PJ F

&R.

GD

T 9

/11/

14


Auger refusal at 2 feet due to water line utiltiyline .


222.4221.6

0.61.4


SampleDepth(feet)










N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60R

-027

9.G

PJ F

&R.

GD

T 9

/11/

14




12

20

10

4.0

6.0

8.0

3-5-7-9

8-10-10-11

3-5-5-7


RESIDUUM: Medium Dense, Brown andYellow, Clayey Fine to Medium SAND, little Silt,trace Mica - Moist

(SC)


239.5238.6

232.0

0.51.4

8.0

2.0

4.0

6.0


SampleDepth(feet)










N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60R

-027

9.G

PJ F

&R.

GD

T 9

/11/

14




12

14

8

2.0

4.0

6.0

8.0

4-5-7-7

4-5-9-11

3-3-5-6


RESIDUUM: Medium Dense to Loose, Brown,Red and Yellow, Clayey Fine to Medium SAND,little Silt, trace Mica - Moist

(SC)


252.3251.8

245.0

0.71.2

8.0

0.0

2.0

4.0

6.0


SampleDepth(feet)










N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60R

-027

9.G

PJ F

&R.

GD

T 9

/11/

14




Driller noted cobblesbetween 10 and 16 feet

10

11

8

5

7

33

100+

1.5

3.0

5.0

7.5

10.0

15.0

22.0

3-4-6

3-4-7

3-4-4

2-2-3

1-2-5

44-15-18

50/0REC=67%RQD=62%

Surficial SoilRESIDUUM: Stiff to Firm, Brown, Sandy LeanCLAY, trace Silt, trace Roots, trace Mica - Moist

(CL)

Firm, Dark Gray and Brown, Lean CLAY, little Silt,trace Sand - Moist

(CL)[Strong Organic Odor Noted in Sample]

Dense, Gray and Brown, Fine to Coarse GRAVEL,trace Clay, trace Sand - Wet

(GC)

SOFT WEATHERED ROCK: Very Dense, Gray andBrown, Fine to Coarse GRAVEL, trace Clay, traceSand - Wet

(GC)ROCK: Hard, Pink, White and Black, Very Slightto Fresh Weathering, Slightly Fractured, CoarseGrained Petersburg GRANITE


204.6

197.0

194.5

188.1188.0

183.0

0.4

8.0

10.5

16.917.0

22.0

0.0

1.5

3.5

6.0

8.5

13.5

16.917.0

Driller: Craig Sequist

SampleDepth(feet)









BORING LOGBoring: BC-1 (1 of 1)

N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60R

-027

9.G

PJ F

&R.

GD

T 9

/11/

14




15

16

6

1

28

100+

1.5

3.0

5.0

7.5

10.0

19.0

7-7-8

6-8-8

5-3-3

1-0-1

5-12-16

50/3REC=100%RQD=60%

Surficial SoilRESIDUUM: Medium Dense, Brown, ClayeyFine to Medium SAND, trace Mica - Moist

(SC)Firm, Brown, Sandy Lean CLAY - Moist

(CL)

Very Loose, Brown, Silty Fine to Medium SAND -Moist

(SM)

Medium Dense, Brown, Silty Fine to CoarseSAND, trace Gravel - Moist

(SM)

SOFT WEATHERED ROCK: Very Dense, Brown,Silty Fine to Coarse SAND, trace Gravel - Moist

(SM)ROCK: Hard, Pink, White and Black, Slight toVery Slight Weathering, Slightly to ModeratelyFractured, Coarse Grained Petersburg GRANITE


202.6

200.0

197.5

195.0

189.5189.0

184.0

0.4

3.0

5.5

8.0

13.514.0

19.0

0.0

1.5

3.5

6.0

8.5

13.514.0


SampleDepth(feet)









BORING LOGBoring: BC-2 (1 of 1)

N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60R

-027

9.G

PJ F

&R.

GD

T 9

/11/

14




10

16

7

10

28

100+

1.5

3.0

5.0

7.5

10.0

2-3-7

4-9-7

2-4-3

5-5-5

13-13-15

50/1

Surficial SoilRESIDUUM: Stiff to Very Stiff, Brown, SandyLean CLAY, trace fine gravel - Moist

(CL)Firm, Brown, Sandy Lean CLAY - Moist

(CL)

Medium Dense, Brown, Clayey Fine to CoarseSAND, little Gravel - Moist

(SC)

Dense, Brown, Silty Fine to Coarse SAND, littleGravel, trace Clay - Moist

(SM)

SOFT WEATHERED ROCK: Very Dense, Gray,Silty Fine to Coarse SAND - Moist

(SM)Auger refusal at 13.6 feet.


214.4

212.0

209.5

207.0

201.5201.4

0.6

3.0

5.5

8.0

13.513.6

0.0

1.5

3.5

6.0

8.5

13.5


SampleDepth(feet)









BORING LOGBoring: P-1 (1 of 1)

N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60R

-027

9.G

PJ F

&R.

GD

T 9

/11/

14




6

6

6

9

12

10

16

1.5

3.0

5.0

7.5

10.0

15.0

20.0

1-3-3

3-3-3

1-3-3

2-4-5

2-5-7

4-4-6

5-7-9

Surficial SoilRESIDUUM: Brown and Red, Sandy Lean CLAY- Moist

(CL)Loose, Brown, Clayey Fine to Medium SAND,trace Roots, trace Silt - Moist

(SC)Stiff, Brown, Sandy Lean CLAY, trace Silt - Moist

(CL)

Medium Dense, Brown, Clayey Fine SAND, traceSilt - Moist

(SC)

Stiff, Brown, Sandy SILT, trace Clay - Moist(ML)

Medium Dense, Brown, Silty Fine to CoarseSAND - Moist

(SM)


216.1

214.0

211.5

209.0

205.0

200.0

197.0

0.9

3.0

5.5

8.0

12.0

17.0

20.0

0.0

1.5

3.5

6.0

8.5

13.5

18.5


SampleDepth(feet)










N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60R

-027

9.G

PJ F

&R.

GD

T 9

/11/

14




8

45

100+

1.5

3.0

5.0

3-4-4

8-25-20

50/5

Surficial SoilRESIDUUM: Firm to Hard, Brown, Sandy LeanCLAY, little Silt, trace Mica - Moist

(CL)SOFT WEATHERED ROCK: Very Dense, Brown,Silty Fine SAND, trace Mica, with RockFragments - Moist

(SM)Auger refusal at 5 feet.


207.6

205.0

203.0

0.4

3.0

5.0

0.0

1.5

3.5


SampleDepth(feet)










N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60R

-027

9.G

PJ F

&R.

GD

T 9

/11/

14

APPENDIX III

B- 1 29 18 11 0.0 65.4 34.1 SC A-2-6 117.2 13.2 16.7

B- 1 2.0 19.5

B- 1 4.0 20.7

B- 1 6.0 19.2

B- 2 2.0 3.9

B- 4 48 25 23 0.0 47.0 49.0 SC A-7-6 108.9 17.4 2.9

B- 4 2.0 23.6

B- 4 4.0 27.0

B- 4 6.0 21.8

B- 5 35 22 13 0.0 52.8 46.9 SC A-6 113.5 13.1 7.1

B- 5 2.0 21.3

B- 5 4.0 23.7

B- 5 6.0 25.2

BC-1 0.0 11.4

BC-1 1.5 12.1

BC-1 3.5 12.4

BC-2 0.0 11.4

BC-2 1.5 12.1

BC-2 3.5 12.4

BC-2 6.0 11.8

BC-2 8.5 13.1

BC-2 13.5 10.4

P-1 0.0 18.3

P-1 1.5 14.3

P-1 3.5 13.7

P-1 6.0 14.6

P-1 8.5 6.8

P-2 0.0 25.8

AASHTOClass.

%Sand

%Fines

CBRValue@ 0.1

PIOptimum

WaterContent (%)

MaximumDry Density

(pcf)Depth (ft)

USCSClass.

LABORATORY TESTSUMMARY SHEET

Boring/Sample No.

WaterContent (%)

%Gravel

Sheet: 1 of 2

LL PL

City/State: Chesterfield County, Virginia

Project: Lucks Lane Improvements


Froehling & Robertson, Inc.Froehling & Robertson, Inc.Froehling & Robertson, Inc.Froehling & Robertson, Inc.


R

LAB

SU

MM

AR

Y

60

R-0

27

9.G

PJ

F&

R.G

DT

9

/12

/14

Bulk

Bulk

Bulk

P-2 1.5 16.7

P-2 3.5 12.6

P-2 6.0 21.3

P-2 8.5 22.1

P-2 13.5 22.8

P-3 0.0 18.1

P-3 1.5 11.7

P-3 3.5 2.7

AASHTOClass.

%Sand

%Fines

CBRValue@ 0.1

PIOptimum

WaterContent (%)

MaximumDry Density

(pcf)Depth (ft)

USCSClass.

LABORATORY TESTSUMMARY SHEET

Boring/Sample No.

WaterContent (%)

%Gravel

Sheet: 2 of 2

LL PL




Froehling & Robertson, Inc.Froehling & Robertson, Inc.Froehling & Robertson, Inc.Froehling & Robertson, Inc.


R

LAB

SU

MM

AR

Y

60

R-0

27

9.G

PJ

F&

R.G

DT

9

/12

/14

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)

GRAIN SIZEDISTRIBUTION

COBBLES

3/83

46

810

1416

2030

4050

60100

140200

U.S. SIEVE OPENING IN INCHES

21.5

13/4

1/2

18

25

22

11

23

13

29

48

35

Pe

rce

nt

Fin

er

(By

We

igh

t)

GRAVEL

coarse fine coarse medium

SAND

fineSILT OR CLAY

Boring No. Depth

B- 1

B- 4

B- 5

at

at

at

at

at

Classification

CLAYEY SAND (SC)

CLAYEY SAND (SC)

CLAYEY SAND (SC)

LL PL PI

0.505

0.194

0.175

D30 D10

Cc

Boring No. Depth

B- 1

B- 4

B- 5

at

at

at

at

at

D100

4.75

4.75

4.75

D60 %Gravel

0.0

0.0

0.0

%Sand

65.4

47.0

52.8

34.1

49.0

46.9

Cu

U.S. SIEVE NUMBERS HYDROMETER

6

%Silt %Clay

43





R

Froehling & Robertson, Inc.Froehling & Robertson, Inc.Froehling & Robertson, Inc.Froehling & Robertson, Inc.U

S_

GR

AIN

_S

IZE

6

0R

-02

79

.GP

J F

&R

.GD

T

9/1

2/1

4

Bulk

Bulk

Bulk

Bulk

Bulk

Bulk

0

10

20

30

40

50

60

0 20 40 60 80 100

PIPL

18

25

22

LL Classification % Natural Water Content

29

48

35

34.1

49.0

46.9

Boring No. Depth

CL-ML

CL CH

ML MH

B- 1

B- 4

B- 5

Liquid Limit

Pla

stic

ity

Ind

ex

ATTERBERG LIMITS

Fines

CLAYEY SAND (A-2-6)

CLAYEY SAND (A-7-6)

CLAYEY SAND (A-6)

Sheet: 1 of 1

11

23

13





R

Froehling & Robertson, Inc.Froehling & Robertson, Inc.Froehling & Robertson, Inc.Froehling & Robertson, Inc.A

TT

ER

BE

RG

_LI

MIT

S_

AA

SH

TO

6

0R

-02

79

.GP

J F

&R

.GD

T

9/1

2/1

4

Bulk

Bulk

Bulk

Sp

. g

r. fo

r Z

AV

is a

n a

ssu

me

d v

alu

e

Dry

de

nsity, p

cf

70

80

90

100

110

120

130

140

Water content, %

0 5 10 15 20 25 30 35 40

100% SATURATION CURVESFOR SPEC. GRAV. EQUAL TO:

2.82.72.6

Test specification: ASTM D 698-12 Method A Standard

60R0279 7-8-14

Lucks Lane Improvement

Kimley Horn

N/A

Brownish Clayey Sand [Sample Marked B-1]

SC A-2-6

29 11

86.1 % 56.7 %

34.1 %

Maximum dry density = 117.2 pcf

Optimum moisture = 13.2 %

Curve No.: 1

Project No.: Date:

Project:

Client:

Sample Number: 1 [Control #120196]

Remarks:

MATERIAL DESCRIPTION

Description:

Classifications - USCS: AASHTO:

Nat. Moist. = Sp.G. =

Liquid Limit = Plasticity Index =

%<No.10 = %<No.40 =

%<No.60 = %<No.200 =

TEST RESULTS

FigureFROEHLING & ROBERTSON, INC.

MOISTURE-DENSITY RELATIONSHIP

Sp

. g

r. fo

r Z

AV

is a

n a

ssu

me

d v

alu

e

Dry

de

nsity, p

cf

70

80

90

100

110

120

130

140

Water content, %

0 5 10 15 20 25 30 35 40


2.82.72.6


60R0279 7-7-14


Kimley Horn

N/A


SC A-7-6

48 23

90.7 % 61.1 %

49.0 %



Curve No.: 2

Project No.: Date:

Project:

Client:


Remarks:


Description:




%<No.10 = %<No.40 =

%<No.60 = %<No.200 =

TEST RESULTS



Sp

. g

r. fo

r Z

AV

is a

n a

ssu

me

d v

alu

e

Dry

de

nsity, p

cf

70

80

90

100

110

120

130

140

Water content, %

0 5 10 15 20 25 30 35 40


2.82.72.6


60R0279 7-8-14


Kimley Horn


SC A-6

35 13

92.5 % 73.6 %

46.9 %



Curve No.: 3

Project No.: Date:

Project:

Client:


Remarks:


Description:




%<No.10 = %<No.40 =

%<No.60 = %<No.200 =

TEST RESULTS



California Bearing Ratio

Project No.: 60R-0279 Test Date: 7/12/2014

Client: Kimley Horn & Associates Tested By: C.M.

Project: Lucks Lane Improvements Compaction method: ASTM D1883/AASHTO T193/VTM8

Location: Chesterfield County, Virginia X Soaked CBR

X 65 Blows

CBR @ 0.2 in. penetration (wet): 16.0

CBR @ 0.1 in. penetration (wet): 16.7 Maximum Dry Density (pcf): 117.2

Swell (%): 0.3 Optimum Moisture Content (%): 13.2

Dry Density Before Soaking (pcf): 116.6

Dry Density After Soaking (pcf): 114.8 Visual Description:

Retained on 3/4 inch sieve (%): 0.0 Brown Clayey SAND

Surcharge Weight (pounds): 10.0

F&R Lab No.: 120196

Moisture Content Before Soaking (%): 12.3%

Moisture Content After Soak, Top in. (%): 14.5% Source:

Moisture Content After Soak, Ave. (%): 16.6%

B-1

0

100

200

300

400

500

600

700

800

900

1000

1100

0 0.1 0.2 0.3 0.4 0.5

Str

ess o

n P

isto

n (

psi)

Penetration (inches)

Soaked

Dry

FROEHLING & ROBERTSON, INC.Engineering Stability Since 1881

3015 Dumbarton Road

Richmond, Virginia 23228-5831 I USA

T 804.264.2701 I F 804.264.3549






X 65 Blows








F&R Lab No.: 120196




B-4

0

100

200

300

400

500

600

700

800

900

1000

1100

0 0.1 0.2 0.3 0.4 0.5

Str

ess o

n P

isto

n (

psi)


Soaked

Dry


3015 Dumbarton Road


T 804.264.2701 I F 804.264.3549






X 65 Blows








F&R Lab No.: 120196




B-5

0

100

200

300

400

500

600

700

800

900

1000

1100

0 0.1 0.2 0.3 0.4 0.5

Str

ess o

n P

isto

n (

psi)


Soaked

Dry


3015 Dumbarton Road


T 804.264.2701 I F 804.264.3549

APPENDIX IV

Geotechnical Services Are Performed forSpecific Purposes, Persons, and ProjectsGeotechnical engineers structure their services to meet the specific needs oftheir clients. A geotechnical engineering study conducted for a civil engi-neer may not fulfill the needs of a construction contractor or even anothercivil engineer. Because each geotechnical engineering study is unique, eachgeotechnical engineering report is unique, prepared solely for the client. Noone except you should rely on your geotechnical engineering report withoutfirst conferring with the geotechnical engineer who prepared it. And no one— not even you — should apply the report for any purpose or projectexcept the one originally contemplated.

Read the Full ReportSerious problems have occurred because those relying on a geotechnicalengineering report did not read it all. Do not rely on an executive summary.Do not read selected elements only.

A Geotechnical Engineering Report Is Based on A Unique Set of Project-Specific FactorsGeotechnical engineers consider a number of unique, project-specific fac-tors when establishing the scope of a study. Typical factors include: theclient's goals, objectives, and risk management preferences; the generalnature of the structure involved, its size, and configuration; the location ofthe structure on the site; and other planned or existing site improvements,such as access roads, parking lots, and underground utilities. Unless thegeotechnical engineer who conducted the study specifically indicates oth-erwise, do not rely on a geotechnical engineering report that was:• not prepared for you,• not prepared for your project,• not prepared for the specific site explored, or• completed before important project changes were made.

Typical changes that can erode the reliability of an existing geotechnicalengineering report include those that affect: • 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,

• elevation, configuration, location, orientation, or weight of the proposed structure,

• composition of the design team, or• project ownership.

As a general rule, always inform your geotechnical engineer of projectchanges—even minor ones—and request an assessment of their impact.Geotechnical engineers cannot accept responsibility or liability for problemsthat occur because their reports do not consider developments of whichthey were not informed.

Subsurface Conditions Can ChangeA geotechnical engineering report is based on conditions that existed atthe time the study was performed. Do not rely on a geotechnical engineer-ing report whose adequacy may have been affected by: the passage oftime; by man-made events, such as construction on or adjacent to the site;or by natural events, such as floods, earthquakes, or groundwater fluctua-tions. Always contact the geotechnical engineer before applying the reportto determine if it is still reliable. A minor amount of additional testing oranalysis could prevent major problems.

Most Geotechnical Findings Are ProfessionalOpinionsSite exploration identifies subsurface conditions only at those points wheresubsurface tests are conducted or samples are taken. Geotechnical engi-neers review field and laboratory data and then apply their professionaljudgment to render an opinion about subsurface conditions throughout thesite. Actual subsurface conditions may differ—sometimes significantly—from those indicated in your report. Retaining the geotechnical engineerwho developed your report to provide construction observation is the most effective method of managing the risks associated with unanticipatedconditions.

A Report's Recommendations Are Not FinalDo not overrely on the construction recommendations included in yourreport. Those recommendations are not final, because geotechnical engi-neers develop them principally from judgment and opinion. Geotechnicalengineers can finalize their recommendations only by observing actual

Important Information About Your

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

Geotechnical Engineering ReportThe following information is provided to help you manage your risks.

subsurface conditions revealed during construction. The geotechnicalengineer who developed your report cannot assume responsibility or liability for the report's recommendations if that engineer does not performconstruction observation.

A Geotechnical Engineering Report Is Subject toMisinterpretationOther design team members' misinterpretation of geotechnical engineeringreports has resulted in costly problems. Lower that risk by having your geo-technical engineer confer with appropriate members of the design team aftersubmitting the report. Also retain your geotechnical engineer to review perti-nent elements of the design team's plans and specifications. Contractors canalso misinterpret a geotechnical engineering report. Reduce that risk byhaving your geotechnical engineer participate in prebid and preconstructionconferences, and by providing construction observation.

Do Not Redraw the Engineer's LogsGeotechnical engineers prepare final boring and testing logs based upontheir interpretation of field logs and laboratory data. To prevent errors oromissions, the logs included in a geotechnical engineering report shouldnever be redrawn for inclusion in architectural or other design drawings.Only photographic or electronic reproduction is acceptable, but recognizethat separating logs from the report can elevate risk.

Give Contractors a Complete Report andGuidanceSome owners and design professionals mistakenly believe they can makecontractors liable for unanticipated subsurface conditions by limiting whatthey provide for bid preparation. To help prevent costly problems, give con-tractors the complete geotechnical engineering report, but preface it with aclearly written letter of transmittal. In that letter, advise contractors that thereport was not prepared for purposes of bid development and that thereport's accuracy is limited; encourage them to confer with the geotechnicalengineer who prepared the report (a modest fee may be required) and/or toconduct additional study to obtain the specific types of information theyneed or prefer. A prebid conference can also be valuable. Be sure contrac-tors have sufficient time to perform additional study. Only then might yoube in a position to give contractors the best information available to you,while requiring them to at least share some of the financial responsibilitiesstemming from unanticipated conditions.

Read Responsibility Provisions CloselySome clients, design professionals, and contractors do not recognize thatgeotechnical engineering is far less exact than other engineering disci-plines. This lack of understanding has created unrealistic expectations that

have led to disappointments, claims, and disputes. To help reduce the riskof such outcomes, geotechnical engineers commonly include a variety ofexplanatory provisions in their reports. Sometimes labeled "limitations"many of these provisions indicate where geotechnical engineers’ responsi-bilities begin and end, to help others recognize their own responsibilitiesand risks. Read these provisions closely. Ask questions. Your geotechnicalengineer should respond fully and frankly.

Geoenvironmental Concerns Are Not Covered The equipment, techniques, and personnel used to perform a geoenviron-mental study differ significantly from those used to perform a geotechnicalstudy. For that reason, a geotechnical engineering report does not usuallyrelate any geoenvironmental findings, conclusions, or recommendations;e.g., about the likelihood of encountering underground storage tanks orregulated contaminants. Unanticipated environmental problems have ledto numerous project failures. If you have not yet obtained your own geoen-vironmental information, ask your geotechnical consultant for risk man-agement guidance. Do not rely on an environmental report prepared forsomeone else.

Obtain Professional Assistance To Deal with MoldDiverse strategies can be applied during building design, construction,operation, and maintenance to prevent significant amounts of mold fromgrowing on indoor surfaces. To be effective, all such strategies should bedevised for the express purpose of mold prevention, integrated into a com-prehensive plan, and executed with diligent oversight by a professionalmold prevention consultant. Because just a small amount of water ormoisture can lead to the development of severe mold infestations, a num-ber of mold prevention strategies focus on keeping building surfaces dry.While groundwater, water infiltration, and similar issues may have beenaddressed as part of the geotechnical engineering study whose findingsare conveyed in this report, the geotechnical engineer in charge of thisproject is not a mold prevention consultant; none of the services per-formed in connection with the geotechnical engineer’s studywere designed or conducted for the purpose of mold preven-tion. Proper implementation of the recommendations conveyedin this report will not of itself be sufficient to prevent moldfrom growing in or on the structure involved.

Rely, on Your ASFE-Member GeotechncialEngineer for Additional AssistanceMembership in ASFE/The Best People on Earth exposes geotechnicalengineers to a wide array of risk management techniques that can be ofgenuine benefit for everyone involved with a construction project. Conferwith you ASFE-member geotechnical engineer for more information.

8811 Colesville Road/Suite G106, Silver Spring, MD 20910Telephone: 301/565-2733 Facsimile: 301/589-2017

e-mail: [email protected] www.asfe.org

Copyright 2004 by ASFE, Inc. Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with ASFE’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of ASFE, and only for

purposes of scholarly research or book review. Only members of ASFE may use this document as a complement to or as an element of a geotechnical engineering report. Any otherfirm, individual, or other entity that so uses this document without being an ASFE member could be commiting negligent or intentional (fraudulent) misrepresentation.

IIGER06045.0M

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