**OFFICE OF BRIDGE DEVELOPMENT**

**MANUAL FOR HYDROLOGIC AND HYDRAULIC DESIGN**

**CHAPTER 11, EVALUATING SCOUR AT BRIDGES**

**APPENDIX E**

**GUIDELINE FOR OBTAINING**

**SOIL SAMPLES IN STREAMS AND ON FLOOD PLAINS**

![](media/image1.png)

**FEBRUARY 2003**

CHAPTER 11, APPENDIX E

GUIDELINE FOR OBTAINING

SOIL SAMPLES IN STREAMS AND ON FLOOD PLAINS

FOR EVALUATING SCOUR AT BRIDGES

INTRODUCTION

The SHA Interdisciplinary Scour Team has developed this guideline to:

-   explain the extent of soils information needed for a bridge scour
    evaluation,

-   provide guidance on how to obtain the soil samples, and

-   set forth the roles of the scour team members in conducting the soil
    sampling program.

The Office of Bridge Development uses the Maryland SHA Bridge Scour
Program (ABSCOUR) as the primary tool for evaluating scour at bridges.
This program requires certain information on surface and subsurface
soils in the stream channel and on the flood plain. Estimated scour
depths are usually dependent on the characteristics of these soils, so
appropriate samples need to be collected and accurately measured. To
accomplish this task, a scour team is formed to prepare and conduct a
soil-sampling plan. The challenge to the scour team is to obtain the
information needed for the scour evaluation in a reasonable and
cost-effective manner.

INTERDISCIPLINARY SCOUR TEAM

Normally, the members of the interdisciplinary scour team will include
representatives from Structures H&H, the Bridge Division and the Office
of Materials and Technology, Geotechnologic Explorations:

-   The Structures H&H member develops and coordinates the soil sampling
    plan. In addition, he or she conducts a preliminary reconnaissance
    and scour assessment of the bridge site and provides detailed
    information on the location of each sample to be taken.

-   The Geotechnical Engineer assists in the development of the
    soil-sampling plan and makes arrangements to collect, test and
    evaluate the samples.

-   The Bridge Project Engineer provides information regarding the
    structure, design schedules and proposed locations of borings for
    foundation analysis and design.

CONSULTANT SCOUR STUDIES

Consultants preparing scour reports for SHA bridges or for Federally
financed county bridges submit a soil-sampling plan to the SHA similar
to the one presented in this guideline. The consultant initiates an
early coordination meeting with Structures H&H to present the conceptual
plan for conduct of the work. The conceptual plan includes the names of
the consultant's interdisciplinary scour team, a schedule for the
conduct of the work, and an outline for the completion of Hydrology,
Geomorphology, Hydraulic, Soil-Sampling and Scour Reports. Arrangements
are made at the early coordination meeting for follow-up meetings to
review progress of the work. Decisions are made regarding the
soil-sampling plan and who is to do the work. The soil-sampling plan is
incorporated in the scour report.

PRELIMINARY SCOUR ASSESSMENT

The Structures H&H Engineer conducts a preliminary scour assessment and
reconnaissance of the bridge crossing. Consideration is given to the
timing of the soil sampling effort, whenever feasible, to obtain surface
stream samples during the summer or fall when stream flow is at a
minimum.

The Engineer uses information obtained from this initial visit to make
rough estimates of the scour at bridge piers and abutments. If scour
depths are excessive, this "heads up" signal is evaluated to decide if
proposed locations of piers or abutments should be changed.

The following objectives are accomplished with the preliminary scour
assessment and reconnaissance of the bridge crossing:

-   pebble counts of the bed load in the stream channel,

-   a plan for obtaining sub-pavement samples,

-   visual observations of the characteristics of the flood plain soils,
    vegetation and other features,

-   locations where additional samples are needed over and beyond the
    six sites in Table 1.

-   one or more sketches providing complete information to the Geotechs
    on the location of each flood plain and channel bed sample to be
    taken.

-   photographs and sketches depicting the relationship of the proposed
    or existing bridge with the stream and its flood plain.

Using information from available reports (Hydrology, Geomorphology and
HEC-RAS studies) the Engineer completes the ABSCOUR computations and
discusses the results with the Bridge Project Engineer.

Next, the Structures H&H Engineer, in consultation with the Bridge and
Geotechnical Engineers, prepares a preliminary soil sampling program.
This information is set forth on the Soil Sampling Plan Worksheet
(Appendix A).

THE SOIL SAMPLING PLAN AND SCHEDULE

The SHA ABSCOUR program requires soils information at the locations set
forth in Table 1.

TABLE 1

Locations of Soil Samples for Scour Evaluations (See Figure 1)

  -------------------- ---------------- ---------------- ----------------
  Channel Location     Left Flood Plain Channel          Right Flood
                                                         Plain

  Approach             1                2                3
  cross-section                                          

  Bridge cross-section 4                5                6
  -------------------- ---------------- ---------------- ----------------

The Structures H&H Engineer determines the location of these sites for
the bridge project and works with the Geotechs in developing the
sampling plan. . Other samples, in addition to the six locations noted
above, are included as needed, particularly if the stream under
consideration is not stable. These other sample locations may include
point bars, channel banks, and additional upstream or downstream
cross-sections.

The H&H Engineer provides detailed information and sketches to the
Geotechnical Engineer regarding the location of each surface sample
site. Particular attention is given to ways and means of collecting the
sub-pavement samples in the stream bed.

The Geotechnical Engineer arranges for notification of property owners
for permission to work on their property.

Sample locations 4, 5 and 6 typically include both surface soil samples
and soil borings. The worksheet in Appendix A serves as a convenient
means to outline the sampling plan.

![](media/image2.jpeg){width="5.995138888888889in" height="3.7in"}

PROCEDURES FOR OBTAINING SAMPLES

The Geotechnical Engineer makes arrangements to collect the following
samples.

1.  The Approach cross-section

Please refer to Figure 1 and note that sample locations 1 and 3 are on
the flood plain at the approach section, upstream of the bridge. In many
cases, the flood plain soils are fairly uniform so that one sample at
each location will be adequate. The Structures H&H Engineer determines
the number of samples required as a part of the preliminary scour
assessment and provides a sketch depicting the location of each sample.

For non-cohesive soils, a sample pit with a depth of about 12 inches is
dug at the selected sample sites. If the soil is relatively uniform,
take one sample from the each pit. If the soil consists of layers of
significantly different materials, sample each layer.

The Soils Lab runs a sieve analysis on the bagged samples to determine
the particle size distribution and D50 size. Fill in all required
information on the tag for each soil sample. Note the location of each
sample and plot the locations on maps for inclusion in the scour report.

For cohesive soils, Shelby tube samples can be taken and tests run in
the EFA apparatus to measure directly the critical velocity of the
soils. If it is not practical to get a Shelby tube sample of the surface
soils, other sampling techniques can be used to provide an estimate of
the soil's ability to resist erosion. Soils are classified as 1) low
resistance to erosion, 2) average resistance to erosion or 3) high
resistance to erosion. This classification is based on the Geotechnical
Engineer's best judgment of the evaluation of the results of the soil
tests. Table 2 provides guidance as to how to use this information in
the ABSCOUR analysis. Neill's use of the term competent velocity is
equivalent to SHA's use of the term critical velocity

Table 2

Tentative Guide to Competent Velocities for Erosion of Cohesive Material

(From Neill's Guide to Bridge Hydraulics, 1973)

+-----------------+-----------------+-----------------+-----------------+
| FLOW DEPTH      | COMPETENT MEAN  |                 |                 |
|                 | VELOCITIES      |                 |                 |
| Ft.             | (ft/sec) \*     |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
|                 | LOW RESISTANCE  | AVERAGE         | HIGH RESISTANCE |
|                 | TO EROSION      | RESISTANCE TO   | TO EROSION      |
|                 |                 | EROSION         |                 |
+-----------------+-----------------+-----------------+-----------------+
| 5               | 1.9             | 3.4             | 5.9             |
+-----------------+-----------------+-----------------+-----------------+
| 10              | 2.1             | 3.9             | 6.6             |
+-----------------+-----------------+-----------------+-----------------+
| 20              | 2.3             | 4.3             | 7.4             |
+-----------------+-----------------+-----------------+-----------------+

Recommendations:

Classify very soft or soft soils (loads\< 500 psf) as low resistance

Classify medium stiff to stiff soils (loads 500 to 2000 psf) as average
resistance

Classify very stiff to hard soils (loads\> 2000 psf) as high resistance

The flood plain samples are used to decide if the soil has the strength
to resist the estimated flood plain velocities. A vital consideration in
this regard is the characteristics of the flood plain vegetation. If the
vegetation is very thick and deep rooted, it is likely to protect the
underlying soil and keep it from being eroded by the flow on the flood
plain. In general, overbank flows have low velocities and shallow depths
which do not have the strength to erode thick vegetative covers. Use the
information collected on the flood plain and in the channel at the
approach section to decide whether scour at the bridge will be live bed
or clear water scour. Note the characteristics of the flood plain
vegetation on the Appendix A Worksheet.

Use two different sampling techniques for the stream channel:

-   Sample the "pavement" or surface layer of stones using the pebble
    count method. In most cases the Structures H&H Engineer makes the
    pebble counts during the reconnaissance visit.

-   Sample the "sub-pavement" or layer below the surface layer of stones
    to a depth of 6" to 12" to obtain adequate material to make a sieve
    analysis. This is accomplished with an open-ended cylinder or, for
    deeper water, some sort of casing arrangement. Sampling in water
    deeper than about two feet will present problems. Bed material can
    vary significantly over the channel width, particularly at bends.
    Consider taking samples at several locations in the channel
    cross-section to obtain a representative sample. Sub-pavement
    sampling requires a joint effort between the Structures H&H Engineer
    and the Geotechnical Engineer to select the right time of year, pick
    appropriate sample locations and obtain the right equipment to
    accomplish the work.

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-   Measure the thickness of the surface layer of stones. If this
    pavement is very thin, consisting of only a few layers of "armoring"
    stones, do not rely on the layer for protection of the stream bed.
    For such cases, use the D50 size of the sub-pavement. Conversely, if
    the pavement layer is thick, say 6 inches or more, it is usually
    reasonable (depending on the stream characteristics) to use the D50
    size of the pavement in the scour calculations to determine live-bed
    or clear water scour.

Special sampling equipment may be needed (wet suit, casing, etc,) if the
water in the channel is more than about two feet deep. For very deep
streams where the channel bottom is not accessible, it may be necessary
to obtain samples from bars. These considerations are evaluated and
taken into account by the Structures H&H Engineer when preparing the
soil-sampling plan.

2.  The Bridge cross-section

### Surface Samples

Designate the soil sample locations at the bridge as numbers 4, 5 and 6
(Figure 1). If the bridge spans only the channel, sample locations 4 and
6 do not exist.

Take the [surface]{.underline} soil samples at locations 4, 5 and 6 in a
manner similar to that described for the approach section. Judgment is
needed in selecting sample sites at an existing bridge, because it is
common for scour to have occurred under the bridge. In such cases, the
scour holes may have filled back in with silt. This silt is easily
erodible and is probably not representative of the stream bed at this
location. For such cases, determine the bed load material under the
silt. Give consideration to obtaining a more representative sample of
the stream bed upstream or downstream of the bridge.

The Structures H&H Engineer selects and prepares sketches of the
location of all surface samples.

### Borings

Soil or rock borings are typically designated at each pier and abutment
by the Bridge Engineer for use in the foundation analysis. These borings
may also serve as valuable information for the scour evaluation;
however, in some cases the foundation borings will not be representative
of the flood plain. The Structures H&H Engineer is interested in the
soils in front of the abutment whereas the Bridge Engineer may designate
the location of the foundation boring well behind the abutment and
possibly out of the flood plain. To address this issue, the Structures
H&H Engineer reviews the location of the proposed foundation borings
with the Bridge Engineer. If necessary, especially for the clear water
scour condition, an additional boring of flood plain soils in front of
the abutment is taken.

For purposes of scour evaluation, extend the borings at least 15 feet
below stream bed for small bridges. For major streams, the potential
scour at piers or abutments is much greater and the minimum depth of
borings for scour is decided on a case by case basis. A minimum of one
boring is to be obtained for each sample location in Figure 1 (Locations
4, 5 and 6), except as provided for below.)

The H&H Engineer should plan to be present at the bridge site when
borings are taken to review the boring plan with the drilling crew.
(Please note that surface sampling can also be accomplished during the
visit of the Structures H&H Engineer).

The abutment borings serve to provide additional information about sub
surface soils at locations 4 and 6 in Figure 1. The pier borings,
depending on the configuration of the bridge, may provide information
for locations 4, 5 and 6.

In some cases, there may be a need to obtain additional borings beyond
that needed for the foundation analysis. Typical examples include:

-   If there are no piers in the channel, take at least one boring in
    the stream channel. (Note: for small bridges, the abutment borings
    may indicate that subsurface conditions are consistent at each
    abutment. Therefore, a third channel boring may not be needed.)
    Generally, consider drilling the channel boring to the same depth as
    the abutment borings. This information is used by the Geotech to
    prepare a profile or cross-section of the subsurface soils at the
    bridge.

-   For purposes of the foundation analysis, a core size of 1 3/8 inch
    internal diameter is normally specified. If the subsurface material
    is coarse gravel or cobbles, however, the small core diameter will
    be inadequate to obtain a reasonable estimation of the D50 size of
    the material. In this case additional subsurface exploration
    techniques are used to obtain the particle size distribution of the
    underlying material.

The subsurface exploration serves to provide an overview of the types of
materials at the bridge. It will also indicate whether the subsoils tend
to be homogeneous, or whether there are subsurface layers with different
properties such as sand, gravel, clay, or rock.

If the subsurface material consists of cohesive soils, samples can be
obtained with Shelby tubes and tested in the EFA Apparatus to obtain the
critical shear strength of the material. The Structures H&H Engineer in
consultation with the Bridge and Geotechnical Engineers determines if
Shelby tube samples are needed for the sampling plan. SHA is in the
beginning stages of use of the EFA Apparatus; therefore, the number of
requests for the conduct of critical shear strength tests may need to be
limited.

If the subsurface material is rock, determine the properties of the rock
with respect to its resistance to scour. As a minimum, determine the RQD
of the rock and request the opinion of the SHA Geologist as to its
resistance to scour. If the potential for scour in the rock is
significant, the Interdisciplinary Scour Team should evaluate the
competency of the rock and decide if additional information (analysis
using the erodibility index method, etc.) is necessary.

If the subsurface material is sand, one or two samples are adequate
unless there is a *significant change* in the makeup of the material.
(from fine sand to medium sand; from very coarse sand to very fine
gravel, etc.). Additional samples are taken as necessary for layered
materials (See below). Sieve analyses should be run on these samples and
the D50 size reported for each sample taken. The depths and elevations
of the samples should be included in the soil boring report.

If the subsurface material is gravel or cobbles, the standard 1 3/8-inch
core will not be wide enough to obtain a representative sample for a
determination of the D50 particle size. For such cases, it may be
feasible to use an oversize split spoon sampler or an auger to obtain
the sample size required to get a representative particle size
distribution and D50 of the material.

In some cases, it may be feasible to obtain a representative sample of
the coarse material subsoils by getting the auger sample from the flood
plain near the stream bank. If the sample must be taken in the
streambed, it may be feasible to set a casing down into the mud line,
and then auger inside the casing to keep the sample from being washed
away when it is extracted. The ground elevation of each boring needs to
be determined so that the boring log can be correlated with the stream
bed elevation and the bridge foundations. When it becomes difficult for
the drilling crew to establish accurate ground elevations, a minimum
requirement is to tie in the ground at the boring location to a bridge
feature (low steel elevation, bridge deck elevation, etc.) and to
document the measurements on the boring log)

Arrangements for sampling coarse bed materials are made by the drilling
crew. The crew should be familiar with the procedures to be used and the
equipment needed to take samples of coarse bed materials. All necessary
equipment should be brought to the project site. Planning for such
eventualities should be a part of the Soil Sampling Plan.

After obtaining the completed boring logs, the Geotechnical Engineer
plots the subsurface profile of the soils under the bridge. This plot
includes, as appropriate, the elevations of the flood plains, the
channel bed, pier and abutment footings and pile tip elevations, when
available. The Structures H&H Engineer will provide this information.

#### 

#### APPENDIX E-1 

SOIL SAMPLING PLAN FOR EVALUATING SCOUR AT BRIDGES

PRELIMINARY PLAN (STRUCTURES H&H ENGINEER) \_\_\_\_\_\_\_

FINAL SOIL-SAMPLING PLAN (GEOTECHNICAL ENGINEER) \_\_\_\_\_\_\_

PROJECT NUMBER
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
DATE\_\_\_\_\_\_\_\_\_\_

Interdisciplinary Scour Team:

Office of Bridge Development

Structures H&H
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Bridge Project Engineer
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Geotechnologic Explorations Unit
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

RESPONSIBILITY FOR OBTAINING SAMPLES

1.  Pebble Counts: Structures H&H

2.  Locating all other samples: Structures H&H

3.  Taking all other samples: Geotechnical Engineer with assistance from
    Structures H&H Engineer (Sub-pavement samples, etc.)

SAMPLE LOCATION SITES

![](media/image2.jpeg){width="5.995138888888889in"
height="3.7in"}Upstream distance to Approach Section from Bridge
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Provide sketch(s) of locations of all sample sites

Soil Samples -- document the soil sample identification numbers and
locations (bag samples and borings) on Figure 1

Locations of additional sample sites (Describe, identify and note on
sketch)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

DATA COLLECTION PLAN AT SOIL SAMPLE SITES

+--------------------------+------------+-------------+--------------+
|                          | Left Flood | Channel     | Right Flood  |
|                          | Plain      |             | Plain        |
+--------------------------+------------+-------------+--------------+
|                          | ## AP      |             |              |
|                          | PROACH CRO |             |              |
|                          | SS-SECTION |             |              |
+--------------------------+------------+-------------+--------------+
| **Sample Number (Figure  | **1**      | **2**       | **3**        |
| 1)**                     |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
| Granular Soils           |            |             |              |
+--------------------------+------------+-------------+--------------+
| D50- top layer           |            |             |              |
+--------------------------+------------+-------------+--------------+
| D50 -- 2^nd^ layer       |            |             |              |
+--------------------------+------------+-------------+--------------+
| D-50 -- 3^rd^ layer      |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
| Cohesive Soils           |            |             |              |
+--------------------------+------------+-------------+--------------+
| Erodibility              |            |             |              |
| Classification -- Sample |            |             |              |
| #1                       |            |             |              |
+--------------------------+------------+-------------+--------------+
| Erodibility              |            |             |              |
| Classification-- Sample  |            |             |              |
| #2                       |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
| Pavement D50 from Pebble |            |             |              |
| Counts                   |            |             |              |
+--------------------------+------------+-------------+--------------+
| Thickness of Pavement    |            |             |              |
+--------------------------+------------+-------------+--------------+
| Sub-pavement D50         |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
| Cohesive Soils           |            |             |              |
+--------------------------+------------+-------------+--------------+
| Erodibility              |            |             |              |
| Classification -- Sample |            |             |              |
| #1                       |            |             |              |
+--------------------------+------------+-------------+--------------+
| Erodibility              |            |             |              |
| Classification-- Sample  |            |             |              |
| #2                       |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
| Description of Flood     |            |             |              |
| Plain; Estimated         |            |             |              |
| Manning's "n" values     |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          | **BRIDGE   |             |              |
|                          | CROSS      |             |              |
|                          | -SECTION** |             |              |
|                          |            |             |              |
|                          | **SURFACE  |             |              |
|                          | SOIL       |             |              |
|                          | SAMPLES**  |             |              |
+--------------------------+------------+-------------+--------------+
| **Sample Number (Figure  | **4**      | **5**       | **6**        |
| 1)**                     |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
| Granular Soils           |            |             |              |
+--------------------------+------------+-------------+--------------+
| D50- top layer           |            |             |              |
+--------------------------+------------+-------------+--------------+
| D50 -- 2^nd^ layer       |            |             |              |
+--------------------------+------------+-------------+--------------+
| D-50 -- 3^rd^ layer      |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
| Cohesive Soils           |            |             |              |
+--------------------------+------------+-------------+--------------+
| Erodibility              |            |             |              |
| Classification -- Sample |            |             |              |
| #1                       |            |             |              |
+--------------------------+------------+-------------+--------------+
| Erodibility              |            |             |              |
| Classification-- Sample  |            |             |              |
| #2                       |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          | Left Flood | Channel     | Right Flood  |
|                          | Plain      |             | Plain        |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
| Pavement D50 from Pebble |            |             |              |
| Counts                   |            |             |              |
+--------------------------+------------+-------------+--------------+
| Thickness of Pavement    |            |             |              |
+--------------------------+------------+-------------+--------------+
| Sub-pavement D50         |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
| Cohesive Soils           |            |             |              |
+--------------------------+------------+-------------+--------------+
| Erodibility              |            |             |              |
| Classification -- Sample |            |             |              |
| #1                       |            |             |              |
+--------------------------+------------+-------------+--------------+
| Erodibility              |            |             |              |
| Classification-- Sample  |            |             |              |
| #2                       |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          |            |             |              |
+--------------------------+------------+-------------+--------------+
|                          | **BRIDGE   |             |              |
|                          | CROSS      |             |              |
|                          | -SECTION** |             |              |
|                          |            |             |              |
|                          | **S        |             |              |
|                          | UB-SURFACE |             |              |
|                          | SOIL       |             |              |
|                          | SAMPLES**  |             |              |
+--------------------------+------------+-------------+--------------+
| PROVIDE THE FOLLOWING    |            |             |              |
| INFORMATION FOR EACH     |            |             |              |
| BORING                   |            |             |              |
+--------------------------+------------+-------------+--------------+
| **Sample Number (Figure  | **4**      | **5**       | **6**        |
| 1)**                     |            |             |              |
+--------------------------+------------+-------------+--------------+
| Boring Number and        |            |             |              |
| Location                 |            |             |              |
|                          |            |             |              |
| (Plot on Figure 1)       |            |             |              |
+--------------------------+------------+-------------+--------------+
| D50 , depth and          |            |             |              |
| elevation of each        |            |             |              |
| granular soil sample     |            |             |              |
| taken from the boring    |            |             |              |
+--------------------------+------------+-------------+--------------+
| Depth, elevation and     |            |             |              |
| critical shear stress    |            |             |              |
| for each cohesive soil   |            |             |              |
| sample (Shelby tube)     |            |             |              |
+--------------------------+------------+-------------+--------------+
| Need for further testing |            |             |              |
| (erodibility index,      |            |             |              |
| etc.)                    |            |             |              |
+--------------------------+------------+-------------+--------------+
| All descriptive          |            |             |              |
| information for rock     |            |             |              |
|                          |            |             |              |
| Cores including RQD      |            |             |              |
+--------------------------+------------+-------------+--------------+
| Elevation of bottom of   |            |             |              |
| existing or proposed     |            |             |              |
| footing                  |            |             |              |
+--------------------------+------------+-------------+--------------+
| Estimated elevation of   |            |             |              |
| pile tips                |            |             |              |
+--------------------------+------------+-------------+--------------+
| **Use the boring data to |            |             |              |
| plot a cross-section or  |            |             |              |
| profile of the           |            |             |              |
| subsurface soils under   |            |             |              |
| the bridge.**            |            |             |              |
+--------------------------+------------+-------------+--------------+