report of geotechnical study -...

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

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Report of Geotechnical Study

Beulah Road Improvements Chesterfield County, Virginia

F&R Project No. 60S-0532

Prepared For:

AECOM 4840 Cox Road

Glen Allen, Virginia 23060

Prepared By: Froehling & Robertson, Inc.

3015 Dumbarton Road Richmond, Virginia 23228

July 2015

AECOM Beulah Road Improvements – Chesterfield County F&R File No. 60S-0532 July 23, 2015

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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/Possible Fill ................................................................................................. 7 4.2.4 Alluvial Soils ...................................................................................................... 7

4.4 SUBSURFACE WATER ..................................................................................................... 7 4.5 LABORATORY TEST RESULTS ............................................................................................ 8

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

5.1 GENERAL .................................................................................................................... 9 5.2 PAVEMENT DESIGN RECOMMENDATIONS ............................................................................ 9 5.3 PAVEMENT OVERLAYS.................................................................................................. 11 5.4 DRAINAGE ................................................................................................................ 12 5.5 EVALUATION OF ON-SITE SOILS FOR FILLS AND ROADWAY SUBGRADES ..................................... 13

6.0 GEOTECHNICAL CONSTRUCTION RECOMMENDATIONS .............................................. 16

6.1 SITE PREPARATION ...................................................................................................... 16 6.2 SELECT FILL PLACEMENT AND COMPACTION ....................................................................... 16 6.3 LIME MODIFICATION / STABILIZATION .............................................................................. 17 6.4 CULVERT STRUCTURE CONSTRUCTION .............................................................................. 18 6.5 SURFACE WATER/GROUNDWATER CONTROL ..................................................................... 19 6.6 TEMPORARY EXCAVATION RECOMMENDATIONS ................................................................. 19

7.0 CONTINUATION OF SERVICES .................................................................................... 19

8.0 LIMITATIONS ............................................................................................................. 20


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APPENDICES APPENDIX I Site Vicinity Map (Drawing No. 1) Boring Location Plan (Drawing No. 2 through 5) APPENDIX II Key to Soil Classification Unified Soil Classification Chart Boring Logs (10 pages) Pavement Core Logs (5 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 between June 18 and 25, 2015. The borings were performed at select locations along the proposed roadway realignment and widening. The borings were typically spaced at 500 foot intervals within the improvement areas.

• Site subsurface conditions generally consist of surficial soils or asphalt pavements underlain by fill, possible fill and alluvial soils.

• 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.

• Flexible pavement designs are provided for the new construction to Beulah Road and Kingsland Road in Section 5.2 of this report.

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


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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 Beulah Road 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 one (1) hand auger with DCP testing and nine (9) Standard Penetration Test (SPT) borings drilled to depths ranging from 7.5 to 9 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 project will consist of improving the western end of Beulah Road, approximately 3,200 linear feet between its intersections with Kingsland Road and Hilmar Drive, in Chesterfield County, Virginia. We understand the majority of improvements will consist of widening Beulah Road, primarily along its southern side, as well as improving the intersection with Kingsland Road. The improvement will result primarily in the total reconstruction of this section of Beulah Road; isolated sections, typically in the transition areas at the project limits will be milled and overlaid. In addition, no large culverts or significant cuts/fills are not expected for this project.

Traffic loading information was obtained from VDOT’s published 2014 traffic counts. The 2014 Average Daily Traffic (ADT) volumes for these section of Beulah Road and Kingsland Road are


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7,900 vehicles per day (vpd) and 6000 vpd, respectively, with 1 percent tractor trailer truck traffic and 1 percent single unit truck traffic.

2.2 Site Description

The project site is located along the Beulah Road corridor and extends from Iron Bridge Road/Kingsland Road to just east of Hilar Drive, in Chesterfield County, Virginia, as indicated on the Site Vicinity Plan (Drawing No. 1, Appendix I). The section of Beulah Road that is to be improved consists of a two-lane, undivided road with three intersections within the 3,200 foot long improvement corridor. The area around the intersection of Kingsland Drive and Beulah Road is relatively wooded.

3.0 EXPLORATION PROCEDURES

3.1 Subsurface Exploration

The exploration program was performed between June 18 and 25, 2015. The exploration consisted of a total of ten (10) soil test borings, designated B-1 through B-10. The borings were drilled to depth ranging 7.5 to 9 feet below existing site grades. The boring locations were selected and staked in the field by F&R personnel, using a hand-held GPS unit and by measuring from existing features, with borings being offset at the time of drilling in order to avoid underground or overhead utilities. The approximate locations of the borings are shown on the Boring Location Plans (Drawing Nos. 2 through 5) included in Appendix I. The boring locations shown on the attached Boring Location Plan should be considered approximate.

Nine (9) of the soil test borings, Borings B-1 and B-3 through B-10, were performed in accordance with generally accepted practice using a truck mounted CME-55 rotary drill rig, equipped with an automatic hammer. 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.


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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 1.3 be used to convert Nfield values to N60 values for the particular machine used for this investigation.

Due to the presence of underground and overhead utilities, Boring B-2 was performed using a hand auger, in conjunction with Dynamic Cone Penetrometer (DCP) testing in order to obtain subsurface soil information. The DCP is a device utilizing a 15 pound steel weight falling 30 inches to drive a cone with a diameter of 1.5 inches and height of 1.66 inches a distance of 1.75 inches into the ground. The number of hammer blows required to drive the cone three successive 1.75 inch increments is recorded, and these blow counts provide a general indication of in-situ soil conditions and has been correlated with certain engineering properties of soils

Prior to demobilization, the boreholes were backfilled with auger cuttings; borings performed within the roadway were patched with cold mix asphalt patch. Periodic observation of the backfilled borings 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


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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 and pavement core 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 Geologic Map of Virginia (1993) reports that the project site lies within the very western edge of the Coastal Plains Physiographic Province of Virginia. The site is very near where the Coastal Plains transitions into the Piedmont Physiographic Province. Within this transition zone, the shallow alluvial soils of the Coastal Plain are often found to overlie the residual soils of the Piedmont. The topography of the Coastal Plain is a terraced landscape that stair-steps down to the coast and to the major rivers. The risers (scarps) are former shorelines and the treads (flat parts) are emergent bay and river bottoms. The higher, older plains in the western part of the Coastal Plain are more dissected by stream erosion than the lower, younger terrace treads. It is commonly held that this landscape was formed over the last few million years as sea level rose and fell in response to the repeated melting and growth of large continental glaciers and as the Coastal Plain slowly uplifted.

Locally, the soils of the project site are described as Tertiary-aged Pliocene Sand and Gravel which is underlain by the Mississippian-aged Petersburg Granite. The Pliocene Sands and Gravels consist of interbedded yellowish-orange to reddish-brown gravelly sand, sandy gravel, and fine to coarse


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sand, poorly to well-sorted, cross-bedded in part, and includes lesser amounts of clay and silt in thin to medium beds at elevations near those at the site, as indicated on our boring logs.

The Piedmont Province is characterized by gently rolling topography, deeply-weathered bedrock, and relatively rare solid outcrop occurrences. Rocks are strongly weathered in the Piedmont's humid climate and bedrock is generally buried under a blanket of saprolite, which is variable in depth (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 subsurface conditions described below are generally representative of sites lying within the Coastal Plain Province.

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 and Pavement Core Logs are presented in Appendix II.

4.2.1 Surficial Soils

Surficial Soil was encountered at the surface of the borings B-2 through B-5 to approximate depths ranging from 0.3 to 0.4 feet (3 to 5 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 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.


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4.2.2 Asphalt Pavement

Borings B-1 and B-6 through B-10 were performed within the existing roadways of Beulah Road and Kingsland Road improvement corridor. The borings encountered a pavement section consisting of 6 to 14 inches of asphalt underlain by 0 to 12 inches of crushed stone. It should be noted asphalt thicknesses of greater than 10 inches were observed at Borings B-1, B-8 and B-9, which were located closest to the intersection of Beulah Road and Iron Bridge Road (Route 10). Copies of the pavement core logs are provided in Appendix II.

4.2.3 Fill/Possible Fill

Fill/Possible Fill may be any material that has been transported and deposited by man. Materials described as fill/possible fill were encountered beneath the surficial soils and pavement sections at Borings B-1, B-3, B-4, B-5 and B-10 to depths of 2 to 3 feet below existing site grades. The sampled fill material was described as Clayey SAND (SC), Silty SAND (SM) or Poorly Graded SAND (SP) with a standard penetration resistances (N-values) ranging between 3 and 38 blows per foot (bpf), indicating that the soils are very loose to dense in relative density.

4.2.4 Alluvial Soils

Alluvial soils were encountered beneath the surficial soils, fill/possible fill and pavement sections and extended to the borings’ planned termination depths. Sampled alluvial soils typically consist of Clayey SANDs (SC). The field N-values for the coarse-grained soils (Sands) ranged from 1 to 30 blows per foot (bpf), indicating these soils have a very loose to dense relative density.

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 9 Not encountered Not observed 6.3

B-2 7.5 Not encountered Not observed 7.0





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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)






It should be noted that the location of the subsurface water could vary by several feet because of seasonal fluctuations in precipitation, 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-4 Bulk 33/19 41.7 6.2 121.9/11.1 25.2 SC A-6

B-5 6 – 8 39/25 41.9 16.7 - - SC A-6

B-6 Bulk 39/22 49.5 9.7 117.5/13.3 26.0 SC A-6

B-8 3 – 5 20/8 49.6 12.1 - - SC A-4

B-9 Bulk 20/9 47.8 6.2 127.6/8.1 29.9 SC A-4 (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)


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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 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. Our designs are also based upon a Design CBR (DCBR) value of 12, as the above referenced manual limits the maximum design resilient modulus to 15,000 psi, while the calculated resilient modulus using the actual Design CBR value (18) was 19600 psi. 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.


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Design Parameter Beulah Road Kingsland Road

Combined for Entry Section off

of Iron Bridge Road

2014 Two-Way Traffic Volume (ADT) Vehicles per day (Obtained from VDOT Traffic Data)

7,900 6,000 13,900

Design Life 20 Years 20 Years 20 Years Tractor Truck Traffic 1% 1% 1% Single Unit Truck Traffic 1% 1% 1% Assumed Growth Rate 1% 1% 1% Directional Factor 50% 50% 50% Lane Distribution Factor 100% 100% 90%

The following flexible pavement sections are recommended for portions of the road where new pavement will be placed. Two pavement sections have been provided for the new road sections. One design is for the new roadway sections along the main routes of Beulah and Kingsland Roads, east of their intersection with each other; the other design is for the section of Beulah Road between Iron Bridge Road and its intersection with Kingsland Road (Station 98+25 to 100+75), where daily traffic loading is anticipated to experience traffic loads from both Beulah and Kingsland Roads.

Recommended Flexible Pavement Design Beulah Road & Kingsland Road

(from Kingsland Road to Hilmar Drive) Layer VDOT Specification Thickness (Inches)

Surface Course Asphalt Concrete (SM-9.5 or SMA-9.5) 2.0

Base Course Asphalt Concrete (BM-25.0) 4.0

Sub-Base Open Graded Drainage Layer 6.0


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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 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,

Recommended Flexible Pavement Design Beulah Road

(from Iron Bridge Road to Kingsland Road) Layer VDOT Specification Thickness (Inches)


Intermediate Course Asphalt Concrete (IM-19.0) 2.0



Recommended Flexible Pavement Design Paved Shoulders

Layer VDOT Specification Thickness (Inches)





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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.

5.4 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 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);


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• 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.

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.

5.5 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)


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• 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 < 18)

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 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)

Beulah Road 98+25 101+00 <1 B-9 2 B E,F,G

101+00 109+00 <1 B-2, B-3, B-10 2 B, C E,F,G

109+00 114+00 <1 B-4 2 B E,F,G 114+00 119+00 <1 B-5 2 B,C E, F, G 119+00 126+75 <1 B-6, B-7 2 B E,F,G

Kingsland Road 10+00 11+93 <1 B-8, B-9 2 B E,F,G


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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 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 not encountered in the near surface soils of the borings. However, if encountered during site grading operations, 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 18); 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


Page - 16 -

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.

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 3 to 5 inches of surficial soils were encountered within 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 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


Page - 17 -

measured CBR of 18. 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-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). 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


Page - 18 -

• 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 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).


Page - 19 -

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. 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 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”.

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


Page - 20 -

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 the 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.

8.0 LIMITATIONS

This report has been prepared for the exclusive use of AECOM, or their agent, for specific application to the Beulah Road Improvements project, in accordance with generally accepted soil 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.


Page - 21 -

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: 60S-0532 Client: AECOM Project: Beulah Road Improvements City/State: Chesterfield County, Virginia

Source: DeLorme Scale: Not to Scale Date: July 2015

Approximate Site Location

Gladstone Glen Place

Froehling & Robertson, Inc. Drawing No. 2


Source: AECOM Scale: As Shown Date: July 2015

BORING LOCATION PLAN

- Approximate Boring Location

B-1

B-8

B-9

B-2






B-10

B-3






B-4

B-5






B-6 B-7

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

1.5

3.5

5.5

7.5

8-11-20

2-2-4

5-8-11

11-13-16

Surficial Soil

ALLUVIUM: Loose to Very Loose, Brown andGray, Clayey Fine to Medium SAND - Moist

(SC)

Boring terminated at 7.5 feet.Boring backfilled upon completion.

0.3

7.5

0.0

2.0

4.0

6.0

Subsurface water notencountered duringdrilling operations

Subsurface water was notobserved upon removal ofthe augers

Cave in at 7 feet

Drilling Method: Hand AugerHammer Type: DCP

Froehling & Robertson, Inc.

Client: AECOM

Boring: B- 2 (1 of 1)

Driller: S. Sequist

SampleDepth(feet)

Depth

R

HAND AUGER LOG

*Penetration is the number of blows required for a 15 lb hammer dropping 20" to drive 1.375" truncated rod a total of 1.75".

* SampleBlows

Elevation Remarks

City/State: Chesterfield County, VirginiaProject: Beulah Road Improvements

Elevation:

Description of Materials(Classification)

Date Drilled: 6/25/15

Nc

Boring Location: Beulah Rd Sta 101+25

Project No: 60S-0532Total Depth: 7.5'

HAN

D_A

UG

ER_L

OG

(LO

NG

NAM

E) 6

0S-0

532.

GPJ

F&

R.G

DT

7/2

3/15



Cave in at 6.3 feet.

25

7

18

15

3.0

5.0

7.0

9.0

4-5-20-15

5-2-5-7

3-8-10-11

4-6-9-14

12" Asphalt

8" Crushed Stone

FILL, Medium dense, gray, POORLY-GRADEDSAND with GRAVEL, trace clay, moist

(FILL - SP)

ALLUVIUM: Loose to Medium Dense, Brown toRed and Gray, Clayey Fine SAND - Moist

(SC)

Boring terminated at 9 feetBoring backfilled and patched upon completion

1.0

1.7

3.0

9.0

1.0

3.0

5.0

7.0

Driller: S. Sequist

SampleDepth(feet)



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


Client: AECOM

*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.



BORING LOGBoring: B- 1 (1 of 1)

N-Value(blows/ft)

Elevation:Total Depth: 9.0'

Project No: 60S-0532

Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60S

-053

2.G

PJ F

&R.

GD

T 7

/23/

15




13

4

11

30

2.0

4.0

6.0

8.0

5-6-7-4

1-2-2-3

2-4-7-9

8-12-18-21

Surficial Soil

FILL: Medium Dense, Gray, Clayey Fine toMedium SAND, trace Roots - Moist

(SC-FILL)

ALLUVIUM: Very Loose to Dense, Gray andBrown, Clayey Fine to Medium SAND - Moist

(SC)

Boring terminated at 8 feetBoring backfilled upon completion

0.4

2.0

8.0

0.0

2.0

4.0

6.0

Driller: S. Sequist

SampleDepth(feet)





Client: AECOM





N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60S

-053

2.G

PJ F

&R.

GD

T 7

/23/

15



Cave in at 7 feet

6

14

10

13

2.0

4.0

6.0

8.0

3-4-2-3

3-5-9-11

4-5-5-5

5-5-8-6

Surficial Soil

POSSIBLE FILL: Loose, Brown, Clayey Fine toMedium SAND, trace Roots - Moist

(Possible FILL - SC)

ALLUVIUM:Medium Dense to Loose, Brownand Gray, Clayey Fine to Medium SAND - Moist

(SC)


0.4

2.0

8.0

0.0

2.0

4.0

6.0

Driller: S. Sequist

SampleDepth(feet)





Client: AECOM





N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60S

-053

2.G

PJ F

&R.

GD

T 7

/23/

15




3

4

8

13

2.0

4.0

6.0

8.0

1-2-1-1

1-2-2-2

2-4-4-5

3-6-7-9

Surficial Soil

POSSIBLE FILL: Very Loose, Brown, Clayey Fineto Medium SAND, trace Roots - Moist

(Possible FILL - SC)

ALLUVIUM: Very Loose to Medium Dense,Brown and Gray, Clayey Fine to Medium SAND -Moist

(SC)


0.4

2.0

8.0

0.0

2.0

4.0

6.0

Driller: S. Sequist

SampleDepth(feet)





Client: AECOM





N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60S

-053

2.G

PJ F

&R.

GD

T 7

/23/

15




8

6

28

27

2.0

4.0

6.0

8.0

7-6-2

1-3-3-4

7-11-17-16

7-13-14-13

8" Asphalt

ALLUVIUM: Loose to Medium Dense, Gray toBrown, Clayey Fine to Medium SAND - Moist

(SC)


0.7

8.0

0.5

2.0

4.0

6.0

Driller: S. Sequist

SampleDepth(feet)





Client: AECOM





N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60S

-053

2.G

PJ F

&R.

GD

T 7

/23/

15




12

8

12

26

2.0

4.0

6.0

8.0

3-7-5

4-4-4-5

2-5-7-10

10-12-14-18

6" Asphalt

ALLUVIUM: Medium Dense, Gray, Clayey Fineto Medium SAND - Moist

(SC)

Loose to Medium Dense, Brown, Clayey Fine toMedium SAND - Moist

(SC)

Medium Dense, Reddish-Brown, Clayey Fine toMedium SAND - Moist

(SC)


0.5

2.0

6.0

8.0

0.5

2.0

4.0

6.0

Driller: S. Sequist

SampleDepth(feet)





Client: AECOM





N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60S

-053

2.G

PJ F

&R.

GD

T 7

/23/

15




22

11

10

19

3.0

5.0

7.0

9.0

12-12-10-4

3-5-6-4

3-5-5-7

3-9-10-11

11" Asphalt

12" Crushed Stone

ALLUVIUM:Medium Dense to Loose, Brown,Clayey Fine to Medium SAND - Moist

(SC)

Medium Dense, Brown and Gray, Clayey Fine toMedium SAND - Moist

(SC)


0.9

1.9

7.0

9.0

1.0

3.0

5.0

7.0

Driller: S. Sequist

SampleDepth(feet)





Client: AECOM



Boring Location: Kingsland Rd Sta 11+00


N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60S

-053

2.G

PJ F

&R.

GD

T 7

/23/

15




10

6

14

22

3.0

5.0

7.0

9.0

4-6-4-3

1-3-3-6

3-7-7-7

5-10-12-10

14" Asphalt

ALLUVIUM:Loose to Medium Dense, Gray andBrown, Clayey Fine to Medium SAND - Moist

(SC)


1.2

9.0

1.0

3.0

5.0

7.0

Driller: S. Sequist

SampleDepth(feet)





Client: AECOM





N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60S

-053

2.G

PJ F

&R.

GD

T 7

/23/

15




38

1

9

11

2.0

4.0

6.0

8.0

15-22-16

WOH-WOH-1-2

2-4-5-6

6-8-3-17

9" Asphalt

FILL: Dense, gray, SILTY SAND, moist(SM-FILL)

ALLUVIUM: Very Loose to Medium Dense,Brown and Gray, Clayey Fine to Medium SAND -Moist

(SC)


0.8

2.0

8.0

0.5

2.0

4.0

6.0

Driller: S. Sequist

SampleDepth(feet)





Client: AECOM




BORING LOGBoring: B-10 (1 of 1)

N-Value(blows/ft)



Depth

R

* SampleBlows

Elevation Remarks

BORI

NG

_LO

G (L

ON

G N

AME)

60S

-053

2.G

PJ F

&R.

GD

T 7

/23/

15

Project Date of

Name: Beulah Road Improvements Extraction: 6/18/2015

Project Number: 60S-0532 Project Location: Chesterfield County, Virginia

Boring/Core Identification: Boring/Core GPS Coordinates:

Latitude:

B-1 Longitude:

General Boring/Core Location: Beulah Road Sta 98+50

Pavement Section Composition: Asphalt: 12 in. Void Underlying Pavement no (yes/no)

Aggregate Base Material: 8 in. Void Depth Below Pavement N/A in.

Soil Cement: 0 in.

Welded Wire Fabric (WWF) or Rebar: N/A WWF/Rebar/Both

Embedment Depths from Top of Core: N/A in. Rebar

N/A in. Welded Wire Fabric

Vapor Barrier or Geotextile Fabric: no (yes/no)

Description of Vapor Barrier or Geotextile: N/A

Subgrade Soil Description: Poorly Graded SAND with Gravel and Brown Clayey SAND

Notes:

The last 3" of asphalt crumbled and

was not able to be cored

Top Bottom

of core of core

PAVEMENT SECTION COMPOSITION AND DESCRIPTION

Project Date of




Latitude:

B-6 Longitude:




Soil Cement: 0 in.






Subgrade Soil Description: Brown Clayey SAND

Notes:

Top Bottom

of core of core


Project Date of




B-7 Latitude:

Longitude:




Soil Cement: 0 in.







Notes:

Top Bottom

of core of core


Project Date of




B-8 Latitude:

Longitude:

General Boring/Core Location: Kingsland Road Sta 11+00



Soil Cement: 0 in.






Subgrade Soil Description: Brown and Gray Clayey SAND

Notes:

Top Bottom

of core of core


Project Date of




B-9 Latitude:

Longitude:




Soil Cement: 0 in.







Notes:

Top Bottom

of core of core


Project Date of




B-10 Latitude:

Longitude:




Soil Cement: 0 in.







Notes:

Top Bottom

of core of core


APPENDIX III

B-01 1.0 6.1

B-01 3.0 28.0

B-01 5.0 23.6

B-01 7.0 16.7

B-03 0.0 15.5

B-03 2.0 6.2

B-03 4.0 16.8

B-03 6.0 12.6

B-04 0.0 20.1

B-04 33 14 19 6.2 0.0 58.3 41.7 SC A-6 121.9

Bulk

11.1 25.2

B-04 2.0 10.0

B-04 4.0 17.1

B-04 6.0 15.5

B-05 0.0 18.4

B-05 2.0 20.9

B-05 4.0 15.6

B-05 6.0 39 14 25 16.7 0.0 58.1 41.9 SC A-6

B-06 0.0 12.3

B-06 39 17 22 9.7 0.5 50.0 49.5 SC A-6 117.5 13.3 26

B-06 2.0 24.2

B-06 4.0 14.0

B-06 6.0 12.3

B-07 0.0 9.4

B-07 2.0 24.2

B-07 4.0 17.7

B-07 6.0 13.1

B-08 1.0 12.5

B-08 3.0 20 12 8 12.1 0.0 50.4 49.6 SC A-4

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: Beulah Road Improvements

Client: AECOM

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


R

LAB

SU

MM

AR

Y

60

S-0

53

2.G

PJ

F&

R.G

DT

7

/22

/15

Bulk

B-08 5.0 15.3

B-08 7.0 14.6

B-09 20 11 9 6.2 1.5 50.7 47.8 SC A-4 127.6 8.1 29.9

B-09 1.0 15.1

B-09 3.0 13.6

B-09 5.0 13.9

B-09 7.0 17.1

B-10 0.0 10.4

B-10 2.0 19.2

B-10 4.0 11.6

B-10 6.0 16.5

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



Client: AECOM

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


R

LAB

SU

MM

AR

Y

60

S-0

53

2.G

PJ

F&

R.G

DT

7

/22

/15

Bulk

0

10

20

30

40

50

60

0 20 40 60 80 100

PI

19

25

22

8

9

PLLL Classification % Natural Water Content

6.0

3.0

6.2

16.7

9.7

12.1

6.2

ATTERBERG LIMITS

33

39

39

20

20

14

14

17

12

11

Liquid Limit

Pla

stic

ity

Ind

ex

FinesBoring No. Depth

CH

ML MH

CLAYEY SAND (SC)

CLAYEY SAND (SC)

CLAYEY SAND (SC)

CLAYEY SAND (SC)

CLAYEY SAND (SC)

41.7

41.9

49.5

49.6

47.8

CL-ML

CL

Sheet: 1 of 1

B-04

B-05

B-06

B-08

B-09

at

at

at

at

at

Client: AECOM




R

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

TT

ER

BE

RG

_LI

MIT

S_

US

CS

6

0S

-05

32

.GP

J F

&R

.GD

T

7/2

2/1

5

Bulk

Bulk

Bulk

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

14

14

17

12

11

19

25

22

8

9

33

39

39

20

20

Pe

rce

nt

Fin

er

(By

We

igh

t)

GRAVEL

coarse fine coarse medium

SAND

fineSILT OR CLAY

Boring No. Depth

B-04

B-05

B-06

B-08

B-09

at

at

at

at

at

6.0

3.0

Classification

CLAYEY SAND (SC)

CLAYEY SAND (SC)

CLAYEY SAND (SC)

CLAYEY SAND (SC)

CLAYEY SAND (SC)

LL PL PI

0.185

0.186

0.139

0.113

0.142

D30 D10

Cc

Boring No. Depth

B-04

B-05

B-06

B-08

B-09

at

at

at

at

at

D100

4.75

4.75

9.5

4.75

12.5

D60 %Gravel

0.0

0.0

0.5

0.0

1.5

%Sand

58.3

58.1

50.0

50.4

50.7

41.7

41.9

49.5

49.6

47.8

Cu

U.S. SIEVE NUMBERS HYDROMETER

6

6.0

3.0

%Silt %Clay

43

Client: AECOM




R

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

S_

GR

AIN

_S

IZE

6

0S

-05

32

.GP

J F

&R

.GD

T

7/2

2/1

5

Bulk

Bulk

Bulk

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

60S0532 6-30-15

Beulah Road Improvements

AECOM

N/A

Brownish Clayey Sand [Bulk Sample B-4]

SC A-6

6.2 %

33 19

99.7 % 83.1 %

41.7 %

Maximum dry density = 121.9 pcf

Optimum moisture = 11.1 %

Curve No.: 1

Project No.: Date:

Project:

Client:

Sample Number: 1 [Control #121899]

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


60S0532 6-30-15


AECOM

N/A

Reddish Brown Clayey Sand [Bulk Sample B-6]

SC A-6

9.7 %

39 22

97.9 % 83.3 %

49.5 %



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


60S0532 7-1-15


AECOM

N/A

Light Brown Clayey Sand [Bulk Sample B-9]

SC A-4

6.2 %

20 9

97.2 % 84.3 %

47.8 %



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.: 60S-0532 Test Date: 7/6/2015

Client: AECOM Tested By: C. Mallory

Project: Beulah Road Improvements Compaction method: ASTM D1883/AASHTO T193/VTM8

Location: Chesterfield County, Virginia X Soaked CBR

X 65 Blows

CBR @ 0.1 in. penetration (wet): 25.2

CBR @ 0.2 in. penetration (wet): 27.0 Maximum Dry Density (pcf): 121.9

Swell (%): 0.2 Optimum Moisture Content (%): 11.1

Dry Density Before Soaking (pcf): 120.9

Dry Density After Soaking (pcf): 124.0 Visual Description:

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

Surcharge Weight (pounds): 10.0

F&R Lab No.: 121889

Moisture Content Before Soaking (%): 10.5%

Moisture Content After Soak, Top in. (%): 12.0% Source:

Moisture Content After Soak, Ave. (%): 11.2%

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)

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.: 121889




B-6

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.: 121889




B-9

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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