DEPARTMENT OF THE ARMY EM 1110-2-1913

U.S. Army Corps of Engineers

CECW-EG Washington, DC 20314-1000

Manual

No. 1110-2-1913 30 April 2000

Engineering and Design

DESIGN AND CONSTRUCTION OF LEVEES

1. Purpose. The purpose of this manual is to present basic principles used in the design and

construction of earth levees.

2. Applicability. This manual applies to all Corps of Engineers Divisions and Districts having

responsibility for the design and construction of levees. 

3. Distribution. This manual is approved for public release; distribution is unlimited.

4. General. This manual is intended as a guide for designing and constructing levees and not intended

to replace the judgment of the design engineer on a particular project.

FOR THE COMMANDER:

RUSSELL L. FUHRMAN

Major General, USA

Chief of Staff

This manual supersedes EM 1110-2-1913, dated 31 March 1978.
EM 1110-2-1913

30 April 2000

US Army Corps

of Engineers

ENGINEERING AND DESIGN

Design and Construction 

of Levees

ENGINEER MANUAL
AVAILABILITY 

Electronic copies of this and other U.S. Army Corps of Engineers 

(USACE) publications are available on the Internet at 

http://www.usace.army.miVinetlusace-docs/. This site is the only 

repository for all official USACE engineer regulations, circulars, 

manuals, and other documents originating from HQUSACE. 

Publications are provided in portable document format (PDF). 
i

DEPARTMENT OF THE ARMY EM 1110-2-1913

U.S. Army Corps of Engineers

CECW-EG Washington, DC 20314-1000

Manual

No. 1110-2-1913 30 April 2000

Engineering and Design

DESIGN AND CONSTRUCTION OF LEVEES

Table of Contents

Subject Paragraph Page 

Chapter 1

Introduction

Purpose ......................................................... 1-1 1-1

Applicability ..................................................... 1-2 1-1

References ....................................................... 1-3 1-1

Objective ........................................................ 1-4 1-1

General Considerations ............................................. 1-5 1-1

Chapter 2

Field Investigations

Preliminary and Final Stage .......................................... 2-1 2-1

Section I

Geological Study

Scope .......................................................... 2-2 2-1

Office Study ..................................................... 2-3 2-2

Field Survey ..................................................... 2-4 2-3

Report .......................................................... 2-5 2-3

Section II

Subsurface Exploration

General ......................................................... 2-6 2-3

Phase 1 Exploration ................................................ 2-7 2-3

Phase 2 Exploration ................................................ 2-8 2-3

Borings ......................................................... 2-9 2-4

Geophysical Exploration ............................................ 2-10 2-4

Section III

Field Testing

Preliminary Strength Estimates ....................................... 2-11 2-6

Vane Shear Tests .................................................. 2-12 2-6

Groundwater and Pore Pressure Observations ............................ 2-13 2-7

Field Pumping Tests ............................................... 2-14 2-7
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Subject Paragraph Page 

Chapter 3

Laboratory Testing 

General ......................................................... 3-1 3-1

Classification and Water Content Determinations .......................... 3-2 3-2

Section I

Fine-Grained Soils

Use of Correlations ................................................ 3-3 3-2

Shear Strength .................................................... 3-4 3-7

Consolidation ..................................................... 3-5 3-7

Permeability ..................................................... 3-6 3-7

Compaction Tests ................................................. 3-7 3-7

Section II

Coarse-Grained Soils

Shear Strength .................................................... 3-8 3-8

Permeability ..................................................... 3-9 3-8

Density Testing of Pervious Fill ....................................... 3-10 3-8

Chapter 4

Borrow Areas

General ......................................................... 4-1 4-1

Available Borrow Material ........................................... 4-2 4-1

General Layout ................................................... 4-3 4-1

Design and Utilization .............................................. 4-4 4-2

Chapter 5

Seepage Control

Section I

Foundation Underseepage

General ......................................................... 5-1 5-1

Cutoffs ......................................................... 5-2 5-1

Riverside Blankets ................................................. 5-3 5-1

Landside Seepage Berms ............................................ 5-4 5-2

Pervious Toe Trench ............................................... 5-5 5-3

Pressure Relief Wells ............................................... 5-6 5-5

Section II

Seepage Through Embankments

General ......................................................... 5-7 5-8

Pervious Toe Drain ................................................ 5-8 5-9

Horizontal Drainage Layers .......................................... 5-9 5-10

Inclined Drainage Layers ............................................ 5-10 5-10

Design of Drainage Layers ........................................... 5-11 5-10

Compaction of Drainage Layers ....................................... 5-12 5-10
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Subject Paragraph Page 

Chapter 6

Slope Design and Settlement

Section I

Embankment Stability

Embankment Geometry ............................................. 6-1 6-1

Standard Levee Sections and Minimum Levee Section ...................... 6-2 6-1

Effects of Fill Characteristics and Compaction ............................ 6-3 6-2

Section II

Stability Analyses

Methods of Analysis ............................................... 6-4 6-3

Conditions Requiring Analysis ........................................ 6-5 6-3

Minimum Acceptable Factors of Safety ................................. 6-6 6-4

Measures to Increase Stability ........................................ 6-7 6-4

Surface Slides .................................................... 6-8 6-5

Section III

Settlement

General ......................................................... 6-9 6-6

Settlement Analyses ................................................ 6-10 6-6

Chapter 7

Levee Construction

Section I

Levee Construction Methods

Classification of Methods ........................................... 7-1 7-1

Section II

Foundations 

Foundation Preparation and Treatment .................................. 7-2 7-1

Methods of Improving Stability ....................................... 7-3 7-3

Section III

Embankments

Embankment Construction Control .................................... 7-4 7-5

Embankment Zoning ............................................... 7-5 7-6

Protection of Riverside Slopes ........................................ 7-6 7-6

Chapter 8

Special Features

Section I

Pipelines and Other Utility Line Crossing Levees

General Considerations ............................................. 8-1 8-1

General Considerations for Pipelines Crossing Through or Under Levees ........ 8-2 8-2

General Consideration for Pipelines Crossing Over Levees ................... 8-3 8-3
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Subject Paragraph Page 

Pipe Selection .................................................... 8-4 8-3

Antiseepage Devices ............................................... 8-5 8-4

Closure Devices ................................................... 8-6 8-6

Camber ......................................................... 8-7 8-6

Installation Requirements ............................................ 8-8 8-7

Section II

Access Roads and Ramps

Access Roads .................................................... 8-9 8-10

Ramps .......................................................... 8-10 8-10

Section III

Levee Enlargement

General ......................................................... 8-11 8-12

Earth-Levee Enlargement ............................................ 8-12 8-12

Floodwall-Levee Enlargement ........................................ 8-13 8-13

Section IV

Junction with Concrete Closure Structures

General ......................................................... 8-14 8-15

Design Considerations .............................................. 8-15 8-17

Section V

Other Special Features

Construction of Ditches Landside of Levee ............................... 8-16 8-17

Levee Vegetation Management ........................................ 8-17 8-17

Appendix A

References

Appendix B

Mathematical Analysis of Underseepage and Substratum Pressure

Appendix C

Design of Seepage Berms

Appendix D

Filter Design

Appendix E

Drainage Trench

Appendix F

Emergency Flood Protection

Appendix G

Use of Soil Cement for Levee Protection
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Appendix H

Notation

List of Tables

No. Title Page 

1-1. Major and Minimum Requirements ......................................... 1-2

1-2. Classification of Levees According to Use .................................... 1-3

2-1. Factors Requiring Intensive Field Investigations and Design Studies ................ 2-1

2-2. Stages of Field Investigations ............................................. 2-2 

2-3. Types of Contour Maps ................................................. 2-3

2-4. Phase I Boring and Sampling Techniques .................................... 2-4

2-5. Applicable Geophysical Methods of Exploration ............................... 2-6

2-6. Preliminary Appraisal of Foundation Strengths ................................ 2-7

3-1. Laboratory Testing of Fine-Grained Cohesive Soils ............................. 3-1

3-2. Laboratory Testing of Pervious Materials .................................... 3-2

6-1. Minimum Factors of Safety - Levee Slope Stability ............................. 6-4

7-1. Classification According to Construction Method of Levees Composed of 

 Impervious and Semipervious Materials .................................... 7-2

7-2. Embankment Construction Deficiencies ...................................... 7-6

8-1. Criteria for Pipelines Crossing Levees ....................................... 8-2

B-1. Factors Involved in Seepage Analyses ....................................... B-2

B-2. Methods for Determination of Design Parameters .............................. B-3

B-3. Examples of Transformation Procedure ...................................... B-5

C-1. Summary of Distances to Effective Source of Seepage, Effective Lengths 

 of Riverside Blankets, and Vertical Permeability of Riverside Blanket 

 Materials at the Crest of 1950 High Water .................................. C-2

C-2. Examples of Design of Seepage Berms ...................................... C-7

D-1. Categories of Base Soil Materials .......................................... D-2

D-2. Criteria for Filters ...................................................... D-3

D-3. D10 and D90 Limits for Preventing Segregation ................................. D-3

F-1. Matching Pipe Size to Pump Size .......................................... F-11

F-2. Crisafulli Pumps - Model CP 2 inch to 24 inch ................................ F-12

F-3. Marlow Self Priming Centrifugal Pumps ..................................... F-12

F-4. Capacity of Corrugated Metal Pipe Culverts .................................. F-14

G-1. Initial Cement Content for Moisture Density Tests ............................. G-3

G-2. Durability Test Weight Loss Criteria ....................................... G-4

G-3. Unconfined Compressive Strength Criteria (ASTM D 1633) ...................... G-5

List of Figures

No. Figure Page 

3-1. Plasticity chart (ENG Form 4334 .......................................... 3-3

3-2. Example correlations of strength characteristic for fine-grained soils ................ 3-4

3-3. Example correlations for consolidation characteristics of fine-grained soils

 (after Kapp, ref. A-5e) ................................................. 3-5

3-4. Comparisons of Atterberg limits and natural water content ....................... 3-7

3-5. Example correlations for properties of coarse-grained soils ....................... 3-9

4-1. Plan of typical levee and borrow areas with traverse and foreshore ................. 4-3
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No. Figure Page 

5-1. Example of incorrect and correct berm length according to existing foundation 

 conditions ........................................................... 5-2

5-2. Typical partially penetrating pervious toe trench ............................... 5-4

5-3. Typical pervious toe trench with collector pipe (Figure 5-6 shows trench details) ....... 5-5

5-4. Pervious toe trench located beneath landward slope ............................. 5-5

5-5. Special equipment for compacting sand in pervious toe trenches .................... 5-6

5-6. Pervious toe trench with collector pipe ....................................... 5-7

5-7. Typical relief well ...................................................... 5-8

5-8. Embankment with through seepage ......................................... 5-9

5-9. Use of horizontal and inclined drainage layers to control seepage through an 

 embankment ......................................................... 5-11

8-1. Typical sections, drainage structures through levees ............................ 8-5

8-2. Typical precast conduit (levees) ........................................... 8-5

8-3. Details of pipeline levee crossing ........................................... 8-9

8-4. Example of levee turnout ................................................. 8-11

8-5. Example of levee turnaround .............................................. 8-11

8-6. Enlargements ......................................................... 8-13

8-7. I-type floodwall-levee enlargement ......................................... 8-14

8-8. Inverted T-type floodwall-levee enlargement .................................. 8-15

8-9. Junction of levee and drainage structure ...................................... 8-16

B-1. Illustration of symbols used in Appendix B ................................... B-4

B-2. Transformation of top strata .............................................. B-6

B-3. Effective seepage exit length for L3 = 4 and d = 100 m or 100 ft ................... B-8

B-4. Relation between x3 for blocked or open exits and x3 for L3 = 4 .................... B-10

B-5. Equations for computation of underseepage flow and substratum pressures for 

 Cases 1 through 4 ..................................................... B-14

B-6. Equations for computation of underseepage flow and substratum pressures for

 Cases 5 and 6 ........................................................ B-15

B-7. Equations for computation of underseepage and substratum pressures for Case 7 ....... B-16

B-8. Ratio between head landward of levee and head at landside toe of levee for levees 

 found on semipervious to stratum underlain by a pervious substratum .............. B-18

C-1. Design of landside seepage berms on impervious top stratum ...................... C-4

D-1. Analysis of a gap-graded material .......................................... D-5

D-2. Illustration of the design of a graded filter .................................... D-7

E-1. Formulas and design curves for drainage trenches (ref. A-3b (2)) ................... E-2

E-2. Example of design of a drainage trench ...................................... E-5

F-1. Sandbag barrier ....................................................... F-5

F-2. Flash board and box levee ................................................ F-6

F-3. Placement of polyethylene sheeting on temporary levee .......................... F-7

F-4. Placement of polyethylene sheeting in the wet ................................. F-8

F-5. Prefabricated rubber pipe stoppers for outlet opening of a manhole ................. F-16

F-6. Prefabricated rubber pipe stoppers for outlet opening of a manhole ................. F-16

F-7. Typical manhole ....................................................... F-17

F-8. Adapting manhole for use as emergency pumping station ......................... F-18

F-9. Sealing top of manhole with wood .......................................... F-19

F-10. Treatment of bottom of manhole ........................................... F-20

F-11. Suction line to pump from manhole ......................................... F-21

F-12. Ringing sand boils ...................................................... F-23
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No. Figure Page 

G-1. Typical moisture-density curve ............................................ G-4

G-2. Stair-step method of slope protection ........................................ G-6

G-3. Relationship of slope, facing thickness, layer thickness, and horizontal layer width ...... G-7

G-4. Typical pug mill central plant ............................................. G-10

G-5. Mixing paddles of a twin-shaft, continuous-flow central mixing plant ............... G-10

G-6. Typical construction sequence ............................................. G-11

G-7. “Deadman” pulling vibratory sheepsfoot roller up the slope ....................... G-12

G-8. Transverse single-shaft rotary mixer ........................................ G-14

G-9. Bulk mechanical spreader ................................................ G-15
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1-1

Chapter 1

Introduction

1-1. Purpose

The purpose of this manual is to present basic principles used in the design and construction of earth levees.

1-2. Applicability

This manual applies to all Corps of Engineers Divisions and Districts having responsibility for designing and

constructing levees.

1-3. References

Appendix A contains a list of required and related publications pertaining to this manual. Unless otherwise

noted, all references are available on interlibrary loan from the Research Library, ATTN: CEWES-IM-MI-R,

U.S. Army Engineer Waterways Experiment Station, 3909 Halls Ferry Road, Vicksburg, MS 39180-6199.

1-4. Objective

The objective of this manual is to develop a guide for design and construction of levees. The manual is

general in nature and not intended to supplant the judgment of the design engineer on a particular project.

1-5. General Considerations

a. General

(1) The term levee as used herein is defined as an embankment whose primary purpose is to furnish flood

protection from seasonal high water and which is therefore subject to water loading for periods of only a few

days or weeks a year. Embankments that are subject to water loading for prolonged periods (longer than

normal flood protection requirements) or permanently should be designed in accordance with earth dam

criteria rather than the levee criteria given herein.

(2) Even though levees are similar to small earth dams they differ from earth dams in the following

important respects: (a) a levee embankment may become saturated for only a short period of time beyond

the limit of capillary saturation, (b) levee alignment is dictated primarily by flood protection requirements,

which often results in construction on poor foundations, and (c) borrow is generally obtained from shallow

pits or from channels excavated adjacent to the levee, which produce fill material that is often heterogeneous

and far from ideal. Selection of the levee section is often based on the properties of the poorest material that

must be used.

(3) Numerous factors must be considered in levee design. These factors may vary from project to

project, and no specific step-by step procedure covering details of a particular project can be established.

However, it is possible to present general, logical steps based on successful past projects that can be followed

in levee design and can be used as a base for developing more specific procedures for any particular project.

Such a procedure is given in Table 1-1. Information for implementing this procedure is presented in subsequent chapters.
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1-2

Table 1-1

Major and Minimum Requirements

Step Procedure

 1 Conduct geological study based on a thorough review of available data including analysis of aerial photographs. Initiate

preliminary subsurface explorations.

 2 Analyze preliminary exploration data and from this analysis establish preliminary soil profiles, borrow locations, and

embankment sections.

 3 Initiate final exploration to provide:

a. Additional information on soil profiles.

b. Undisturbed strengths of foundation materials.

c. More detailed information on borrow areas and other required excavations.

 4 Using the information obtained in Step 3:

a. Determine both embankment and foundation soil parameters and refine preliminary sections where needed, noting all

possible problem areas.

b. Compute rough quantities of suitable material and refine borrow area locations.

 5 Divide the entire levee into reaches of similar foundation conditions, embankment height, and fill material and assign a

typical trial section to each reach.

 6 Analyze each trial section as needed for:

a. Underseepage and through seepage.

b. Slope stability.

c. Settlement.

d. Trafficability of the levee surface.

 7 Design special treatment to preclude any problems as determined from Step 6. Determine surfacing requirements for the

levee based on its expected future use.

 8 Based on the results of Step 7, establish final sections for each reach.

 9 Compute final quantities needed; determine final borrow area locations.

10 Design embankment slope protection.

(4) The method of construction must also be considered. In the past levees have been built by methods

of compaction varying from none to carefully controlled compaction. The local economic situation also

affects the selection of a levee section. Traditionally, in areas of high property values, high land use, and

good foundation conditions, levees have been built with relatively steep slopes using controlled compaction,

while in areas of lower property values, poor foundations, or high rainfall during the construction season,

uncompacted or semicompacted levees with flatter slopes are more typical. This is evident by comparing

the steep slopes of levees along the industrialized Ohio River Valley with levees along the Lower Mississippi

River which have much broader sections with gentler slopes. Levees built with smaller sections and steeper

slopes generally require more comprehensive investigation and analysis than do levees with broad sections

and flatter slopes whose design is more empirical. Where rainfall and foundation conditions permit, the trend

in design of levees is toward sections with steeper slopes. Levee maintenance is another factor that often

has considerable influence on the selection of a levee section.

b. Levee types according to location. Levees are broadly classified according to the area they protect

as either urban or agricultural levees because of different requirements for each. As used in this manual,

urban and agricultural levees are defined as follows:

(1) Urban levees. Levees that provide protection from flooding in communities, including their

industrial, commercial, and residential facilities.
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1-3

(2) Agricultural levees. Levees that provide protection from flooding in lands used for agricultural

purposes.

c. Levee types according to use. Some of the more common terms used for levees serving a specific

purpose in connection with their overall purpose of flood protection are given in Table 1-2.

Table 1-2

Classification of Levees According to Use

Type Definition

Mainline and Levees that lie along a mainstream and its

 tributary levees tributaries, respectively.

Ring levees Levees that completely encircle or “ring” an area subject to inundation from all directions.

Setback levees Levees that are built landward of existing levees, usually because the existing levees have suffered distress or

are in some way being endangered, as by river migration.

Sublevees Levees built for the purpose of underseepage control. Sublevees encircle areas behind the main levee which

are subject, during high-water stages, to high uplift pressures and possibly the development of sand boils. 

They normally tie into the main levee, thus providing a basin that can be flooded during high-water stages,

thereby counterbalancing excess head beneath the top stratum within the basin. Sublevees are rarely

employed as the use of relief wells or seepage berms make them unnecessary except in emergencies.

Spur levees Levees that project from the main levee and serve to protect the main levee from the erosive action of stream

currents. Spur levees are not true levees but training dikes.

d. Causes of Levee Failures. The principal causes of levee failure are

(1) Overtopping.

(2) Surface erosion.

(3) Internal erosion (piping).

(4) Slides within the levee embankment or the foundation soils.
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2-1

Chapter 2

Field Investigations

2-1. Preliminary and Final Stage

Many field investigations are conducted in two stages: a preliminary stage and a final (design) stage. Normally, a field investigation in the preliminary stage is not extensive since its purpose is simply to provide

general information for project feasibility studies. It will usually consist of a general geological reconnaissance with only limited subsurface exploration and simple soil tests. In the design stage, more comprehensive exploration is usually necessary, with more extensive geological reconnaissance, borings, test pits, and

possibly geophysical studies. The extent of the field investigation depends on several factors. Table 2-1 lists

these factors together with conditions requiring extensive field investigations and design studies. Sometimes

field tests such as vane shear tests, groundwater observations, and field pumping tests are necessary.

Table 2-2 summarizes, in general, the broad features of geologic and subsurface investigations.

Section I

Geological Study

2-2. Scope

A geological study usually consists of an office review of all available geological information on the area

of interest and an on-site (field) survey. Since most levees are located in alluvial floodplains, the distribution

and engineering characteristics of alluvial deposits in the vicinity of proposed levees must be evaluated. The

general distribution, nature, and types of floodplain deposits are directly related to changes in the

depositional environment of the river and its tributaries. Each local area in the floodplain bears traces of

river action, and the alluvial deposits there may vary widely from those in adjacent areas. The general nature

and distribution of sediments can be determined through a study of the pattern of local river changes as a

basis for selection of boring locations.

Table 2-1

Factors Requiring Intensive Field Investigations and Design Studies

Factor Field Investigations and Design Studies Should be more Extensive Where:

Previous experience There is little or no previous experience in the area particularly with respect to levee performance

Consequences of failure Consequences of failure involving life and property are great (urban areas for instance)

Levee height Levee heights exceed 3 m (10 ft)

Foundation conditions Foundation soils are weak and compressible

Foundation soils are highly variable along the alignment

Potential underseepage problems are severe 

Foundation sands may be liquefaction susceptible

Duration of high water High water levels against the levee exist over relatively long periods

Borrow materials Available borrow is of low quality, water contents are high, or borrow materials are variable along

the alignment

Structure in levees Reaches of levees are adjacent to concrete structures
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2-2

Table 2-2

Stages of Field Investigations

1. Investigation or analysis produced by field reconnaissance and discussion with knowledgeable people is adequate for design

where:

a. Levees are 3 m (10 ft) or less in height.

b. Experience has shown foundations to be stable and presenting no underseepage problems.

Use standard levee section developed through experience.

2. Preliminary geological investigation: 

a. Office study: Collection and study of

(1) Topographic, soil, and geological maps.

(2) Aerial photographs.

(3) Boring logs and well data.

(4) Information on existing engineering projects.

b. Field survey: Observations and geology of area, documented by written notes and photographs, including such features as:

(1) Riverbank slopes, rock outcrops, earth and rock cuts or fills.

(2) Surface materials.

(3) Poorly drained areas.

(4) Evidence of instability of foundations and slopes.

(5) Emerging seepage.

(6) Natural and man-made physiographic features.

3. Subsurface exploration and field testing and more detailed geologic study: Required for all cases except those in 1 above. Use

to decide the need for and scope of subsurface exploration and field testing:

a. Preliminary phase:

(1) Widely but not necessarily uniformly spaced disturbed sample borings (may include split-spoon penetration tests).

(2) Test pits excavated by backhoes, dozers, or farm tractors.

(3) Geophysical surveys (e.g., seismic or electrical resistivity) or cone penetrometer test to interpolate between widely

spaced borings.

(4) Borehole geophysical tests.

b. Final phase:

(1) Additional disturbed sample borings.

(2) Undisturbed sample borings.

(3) Field vane shear tests for special purposes.

(4) Field pumping tests (primarily in vicinity of structures).

(5) Water table observations (using piezometers) in foundations and borrow areas.

2-3. Office Study

The office study begins with a search of available information, such as topographic, soil, and geological

maps and aerial photographs. Pertinent information on existing construction in the area should be obtained.

This includes design, construction, and performance data on utilities, highways, railroads, and hydraulic

structures. Available boring logs should be secured. Federal, state, county, and local agencies and private

organizations should be contacted for information. The GIS (Geographic Information System) became used

extensively in major range of projects. It is capable of compiling large multi-layered data bases, interactively

analyzing and manipulating those data bases, and generating and displaying resultant thematic maps and

statistics to aid in engineering management decisions. Federal, state, and private organizations provide free

internet access to such systems. Table 2-3 shows some of the contour maps GIS systems provide. 
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2-3

Table 2-3

Types of Contour Maps

Contour Type Uses

Geologic Structure Contour maps in which each line represents GIS can produce these maps based on the selection

Elevation Maps the elevation of the top of a geological material of one of four structure parameters

or facies

Geologic formations Contours the top of a user-defined geologic

formation

Blow counts Contours the top of a structure identified by the A blow count is defined as the number of standard

first, second, or third occurrence of a specified blows required to advance a sampling device into

range of blow counts 150 mm (6 in.) of soil

Soil units Contours the top of a structure identified by the

first, second, or third occurrence of one or

more soil types

Fluid level elevation - Show elevation data (hydraulic head) from Help to evaluate the direction of ground water flow

water table contour unconfined water bearing units where the fluid and the energy gradient under which it is flowing

maps surface is in equilibrium with atmospheric

pressure

Fluid level elevation - Show elevation data from confined water

potentiometric surface bearing units where the fluid surface is under

maps pressure because of the presence of a

confining geologic unit

Hydraulic conductivity Show the rate of water flow through soil under GIS stores vertical and horizontal conductivity data

a unit gradient per unit area for up to five water bearing zones

Portray the variations in the water-bearing Necessary parameter for computing ground water

properties of materials which comprise each flow rates, which is important since groundwater

water bearing zone velocity exerts a major control on plume shape

2-4. Field Survey 

The field survey is commenced after becoming familiar with the area through the office study. Walking the

proposed alignment and visiting proposed borrow areas are always an excellent means of obtaining useful

information. Physical features to be observed are listed in Table 2-2. These items and any others of significance should be documented by detailed notes, supplemented by photographs. Local people or organizations

having knowledge of foundation conditions in the area should be interviewed.

2-5. Report

When all available information has been gathered and assimilated, a report should be written that in essence

constitutes a geological, foundation, and materials evaluation report for the proposed levee. All significant

factors that might affect the alignment and/or design should be clearly pointed out and any desirable changes

in alignment suggested. All maps should be to the same scale, and overlays of maps, e.g., topography and

soil type, aerial photograph and topography, etc., to facilitate information correlation is desirable. The

development of a project GIS will simplify and expedite consistently georeferenced map products.
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2-4

Section II

Subsurface Exploration

2-6. General

a. Because preliminary field investigations usually involve only limited subsurface exploration, only

portions of the following discussion may be applicable to the preliminary stage, depending on the nature of

the project.

b. The subsurface exploration for the design stage generally is accomplished in two phases, which may

be separate in sequence, or concurrent: (1) Phase 1, the main purpose of which is to better define the geology

of the area, the soil types present and to develop general ideas of soil strengths and permeabilities;

(2) Phase 2, provides additional information on soil types present and usually includes the taking of undisturbed samples for testing purposes.

2-7. Phase 1 Exploration

Phase 1 exploration consists almost entirely of disturbed sample borings and perhaps test pits excavated with

backhoes, dozers, farm tractors, etc., as summarized in Table 2-4, but may also include geophysical surveys

which are discussed later.

Table 2-4

Phase I Boring and Sampling Techniques

Technique Remarks

1. Disturbed sample borings

a. Split-spoon or standard 1-a. Primarily for soil identification but permits estimate of shear strength of

penetration test clays and crude estimate of density of sands; see paragraph 5-3d of EM 1110-1-1906

Preferred for general exploration of levee foundations; indicates need and locations for undisturbed samples

b. Auger borings 1-b. Bag and jar samples can be obtained for testing

2. Test pits 2. Use backhoes, dozers, and farm tractors

3. Trenches 3. Occasionally useful in borrow areas and levee foundations

2-8. Phase 2 Exploration

Phase 2 subsurface exploration consists of both disturbed and undisturbed sample borings and also may

include geophysical methods. Undisturbed samples for testing purposes are sometimes obtained by

handcarving block samples from test pits but more usually by rotary and push-type drilling methods (using

samplers such as the Denison sampler in extremely hard soils or the thin-walled Shelby tube fixed piston

sampler in most soils). Samples for determining consolidation and shear strength characteristics and values

of density and permeability should be obtained using undisturbed borings in which 127-mm- (5-in.-)

diameter samples are taken in cohesive materials and 76.2-mm- (3-in.-) diameter samples are taken in

cohesionless materials. EM 1110-1-1906 gives details of drilling and sampling techniques.
EM 1110-2-1913

30 Apr 2000

2-5

2-9. Borings

a. Location and spacing. The spacing of borings and test pits in Phase 1 is based on examination of

airphotos and geological conditions determined in the preliminary stage or known from prior experience

in the area, and by the nature of the project. Initial spacing of borings usually varies from 60 to 300 m

(nominally 200 to 1,000 ft) along the alignment, being closer spaced in expected problem areas and wider

spaced in nonproblem areas. The spacing of borings should not be arbitrarily uniform but rather should be

based on available geologic information. Borings are normally laid out along the levee centerline but can

be staggered along the alignment in order to cover more area and to provide some data on nearby borrow

materials. At least one boring should be located at every major structure during Phase 1. In Phase 2, the

locations of additional general sample borings are selected based on Phase 1 results. Undisturbed sample

borings are located where data on soil shear strength are most needed. The best procedure is to group the

foundation profiles developed on the basis of geological studies and exploration into reaches of similar

conditions and then locate undisturbed sample borings so as to define soil properties in critical reaches.

b. Depth. Depth of borings along the alignment should be at least equal to the height of proposed levee

at its highest point but not less than 3 m (nominally 10 ft). Boring depths should always be deep enough

to provide data for stability analyses of the levee and foundation. This is especially important when the

levee is located near the riverbank where borings must provide data for stability analyses involving both

levee foundation and riverbank. Where pervious or soft materials are encountered, borings should extend

through the permeable material to impervious material or through the soft material to firm material. Borings

at structure locations should extend well below invert or foundation elevations and below the zone of

significant influence created by the load. The borings must be deep enough to permit analysis of approach

and exit channel stability and of underseepage conditions at the structure. In borrow areas, the depth of

exploration should extend several feet below the practicable or allowable borrow depth or to the groundwater table. If borrow is to be obtained from below the groundwater table by dredging or other means,

borings should be at least 3 m (nominally 10 ft) below the bottom of the proposed excavation.

2-10. Geophysical Exploration

a. It is important to understand the capabilities of the different geophysical methods, so that they may

be used to full advantage for subsurface investigations. Table 2-5 summarizes those geophysical methods

most appropriate to levee exploration. These methods are a fairly inexpensive means of exploration and

are very useful for correlating information between borings which, for reasons of economy, are spaced at

fairly wide intervals. Geophysical data must be interpreted in conjunction with borings and by qualified,

experienced personnel. Because there have been significant improvements in geophysical instrumentation

and interpretation techniques in recent years, more consideration should be given to their use.

b. Currently available geophysical methods can be broadly subdivided into two classes: those accomplished entirely from the ground surface and those which are accomplished from subsurface borings.

Applicable geophysical ground surface exploration methods include: (1) seismic methods, (2) electrical

resistivity, (3) natural potential (SP) methods, (4) electromagnetic induction methods, and (5) ground

penetrating radar. Information obtained from seismic surveys includes material velocities, delineation of

interfaces between zones of differing velocities, and the depths to these interfaces. The electrical resistivity

survey is used to locate and define zones of different electrical properties such as pervious and impervious

zones or zones of low resistivity such as clayey strata. Both methods require differences in properties of

levee and/or foundation materials in order to be effective. The resistivity method requires a resistivity

contrast between materials being located, while the seismic method requires contrast in wave transmission

velocities. Furthermore, the seismic refraction method requires that any underlying stratum transmit waves
EM 1110-2-1913

30 Apr 2000

2-6

Table 2-5

Applicable Geophysical Methods of Explorationa

 Suspected In Situ Material Subsurface

 Top of Fault Voids or Cavity Elastic Moduli Boundaries, Conduits Landfill

 Bedrock Detection Detection (Velocities) Dip, ... and Vessels Boundaries

Seismic W S W S

Refraction

Seismic S S S W

Reflection

Natural S

Potential (SP)

DC Resistivity S S S S S W

Electro- S S W W

Magnetics

Ground S S S S S S

Penetrating

Radar

Gravity S S S

Magnetics S S

W - works well in most materials and natural configurations.

S - works under special circumstances of favorable materials or configurations.

Blank - not recommended.

 After EM 1110-1-1802. a

at a higher velocity than the overlying stratum. Difficulties arise in the use of the seismic method if the

surface terrain and/or layer interfaces are steeply sloping or irregular instead of relatively horizontal and

smooth. Therefore, in order to use these methods, one must be fully aware of what they can and cannot do.

EM 1110-1-1802 describes the use of both seismic refraction and electrical resistivity. Telford et al. (1990)

is a valuable, general text on geophysical exploration. Applicable geophysical exploration methods based

on operation from the ground surface are summarized in Table 2-5. A resistivity survey measures variations

in potential of an electrical field within the earth by a surface applied current. Variation of resistivity with

depth is studied by changing electrode spacing. The data is then interpreted as electrical resistivity expressed

as a function of depth. (Telford et al. 1990; EM 1110-1-1802)

c. Downhole geophysical logging can be used with success in correlating subsurface soil and rock

stratification and in providing quantitative engineering parameters such as porosity, density, water content,

and moduli. They also provide valuable data for interpreting surface geophysical data. The purpose in using

these methods is not only to allow cost savings, but the speed, efficiency and often much more reliable

information without lessening the quality of the information obtained. Electromagnetic (EM) induction

surveys use EM transmitters that generate currents in subsurface materials. These currents produce

secondary magnetic fields detectable at the surface. Simple interpretation techniques are advantages of these

methods, making EM induction techniques particularly suitable for horizontal profiling. EM horizontal

profiling surveys are useful for detecting anomalous conditions along the centerline of proposed levee

construction or along existing levees. Self potential (SP) methods are based on change of potential of ground

by human action or alteration of original condition. Four electric potentials due to fluid flow, electrokinetic

or streaming, liquid junction or diffusion, mineralizaion, and solution differing concentration, are known.
EM 1110-2-1913

30 Apr 2000

2-7

The qualitative application of this method is relatively simple and serves best for detection of anomalous

seepage through, under, or around levees (Butler and Llopis, 19909; EM 1110-1-1802). 

Section III

Field Testing

2-11. Preliminary Strength Estimates

It is often desirable to estimate foundation strengths during Phase 1 of the exploration program. Various

methods of preliminary appraisal are listed in Table 2-6.

Table 2-6

Preliminary Appraisal of Foundation Strengths

Method Remarks 

1. Split-spoon penetration 1-a. Unconfined compressive strength in hundreds kPa (or tons per square foot), of clay is about

resistance 1/8 of number of blows per 0.3 m (1 ft), or N/8, but considerable scatter must be expected. 

Generally not helpful where N is low 

1-b. In sands, N values less than about 15 indicate low relative densities. N values should not

be used to estimate relative densities for earthquake design

2. Natural water content of 2. Useful when considered with soil classification, and previous experience is available

 disturbed or general type

 samples

3. Hand examination of 3. Useful where experienced personnel are available who are skilled in estimating soil shear 

disturbed samples strengths

4. Position of natural water 4-a. Useful where previous experience is available

 contents relative to liquid

 and plastic limits 4-b. If natural water content is close to plastic limit foundation shear strength should be high

4-c. Natural water contents near liquid limit indicate sensitive soil usually with low shear

strengths 

5. Torvane or pocket pene- 5. Easily performed and inexpensive but may underestimate actual values ; useful only for 

 trometer tests on intact preliminary strength classifications

 portions of general samples

or on walls of test trenches

2-12. Vane Shear Tests

Where undisturbed samples are not being obtained or where samples of acceptable quality are difficult to

obtain, in situ vane shear tests may be utilized as a means of obtaining undrained shear strength. The

apparatus and procedure for performing this test are described in ASTM D 2573. The results from this test

may be greatly in error where shells or fibrous organic material are present. Also, test results in high

plasticity clays must be corrected using empirical correction factors as given by Bjerrum (1972) (but these

are not always conservative).

2-13. Groundwater and Pore Pressure Observations

Piezometers to observe groundwater fluctuations are rarely installed solely for design purposes but should

always be installed in areas of potential underseepage problems. The use and installation of piezometers are

described in EM 1110-2-1908. Permeability tests should always be made after installation of the
EM 1110-2-1913

30 Apr 2000

2-8

piezometers; these tests provide information on foundation permeability and show if piezometers are

functioning. Testing and interpretation procedures are described in EM 1110-2-1908.

2-14. Field Pumping Tests

The permeability of pervious foundation materials can often be estimated with sufficient accuracy by using

existing correlations with grain-size determination; see TM 5-818-5. However, field pumping tests are the

most accurate means of determining permeabilities of stratified in situ deposits. Field pumping tests are

expensive and usually justified only at sites of important structures and where extensive pressure relief well

installations are planned. The general procedure is to install a well and piezometers at various distances from

the well to monitor the resulting drawdown during pumping of the well. Appendix III of TM 5-818-5 gives

procedures for performing field pumping tests.
EM 1110-2-1913

30 Apr 2000

3-1

Chapter 3

Laboratory Testing

3-1. General

a. Reference should be made to EM 1110-1-1906 for current soil testing procedures, and to EM 1110-2-

1902 for applicability of the various shear strength tests in stability analyses.

b. Laboratory testing programs for levees will vary from minimal to extensive, depending on the nature

and importance of the project and on the foundation conditions, how well they are known, and whether

existing experience and correlations are applicable. Since shear and other tests to determine the engineering

properties of soils are expensive and time-consuming, testing programs generally consist of water content

and identification tests on most samples and shear, consolidation, and compaction tests only on representative samples of foundation and borrow materials. It is imperative to use all available data such as

geological and geophysical studies, when selecting representative samples for testing. Soil tests that may

be included in laboratory testing programs are listed in Table 3-1 for fine-grained cohesive soils and in

Table 3-2 for pervious soils, together with pertinent remarks on purposes and scope of testing.

Table 3-1

Laboratory Testing of Fine-Grained Cohesive Soils

Test Remarks

Visual classification and water On all samples

content determinations

Atterberg limits On representative samples of foundation deposits for correlation with shear or consolidation

parameters, and borrow soils for comparison with natural water contents, or correlations with

optimum water content and maximum densities

Permeability Not required; soils can be assumed to be essentially impervious in seepage analyses

Consolidation Generally performed on undisturbed foundation samples only where:

a. Foundation clays are highly compressible

b. Foundations under high levees are somewhat compressible

c. Settlement of structures within levee systems must be accurately estimated

Not generally performed on levee fill; instead use allowances for settlement within levees based

on type of compaction. Sometimes satisfactory correlations of Atterberg limits with coefficient of

consolidation can be used. Compression index can usually be estimated from water content.

Compaction a. Required only for compacted or semi-compacted levees

b. Where embankment is to be fully compacted, perform standard 25-blow compaction tests

c. Where embankment is to be semi-compacted, perform 15-blow compaction tests

Shear strength a. Unconfined compression tests on saturated foundation clays without joints or slickensides

b. Q triaxial tests appropriate for foundation clays, as undrained strength generally governs

stability

c. R triaxial and S direct shear: Generally required only when levees are high and/or

foundations are weak, or at locations where structures exist in levees

d. Q, R, and S tests on fill materials compacted at appropriate water contents to densities

resulting from the expected field compaction effort
EM 1110-2-1913

30 Apr 2000

3-2

Table 3-2 

Laboratory Testing of Pervious Materials

Test Remarks

Visual classification Of all jar samples

In situ density Of Shelby-tube samples of foundation sands where liquefaction susceptibility must be evaluated

determinations

Relative density Maximum and minimum density tests should be performed in seismically active areas to

determine in situ relative densities of foundation sands and to establish density control of sand fills

Gradation On representative foundation sands:

a. For correlating grain-size parameters with permeability or shear strength

b. For size and distribution classifications pertinent to liquefaction potential

Permeability Not usually performed. Correlations of grain-size parameters with permeability or shear strength

used. Where underseepage problems are serious, best guidance obtained by field pumping tests

Consolidation Not usually necessary as consolidation under load is insignificant and occurs rapidly

Shear strength For loading conditions other than dynamic, drained shear strength is appropriate. Conservative

values of φ’ can be assumed based on S tests on similar soils. In seismically active areas, cyclic

triaxial tests may be performed

3-2. Classification and Water Content Determinations

After soil samples have been obtained in subsurface exploration of levee foundations and borrow areas, the

first and essential step is to make visual classifications and water content determinations on all samples

(except that water content determinations should not be made on clean sands and gravels). These samples

may be jar or bag samples obtained from test pits, disturbed or undisturbed drive samples, or auger samples.

Field descriptions, laboratory classifications, and water content values are used in preparing graphic representations of boring logs. After examining these data, samples of fine-grained soils are selected for Atterberg limits tests, and samples of coarse-grained soils for gradation tests.

Section I

Fine-Grained Soils

3-3. Use of Correlations

Comparisons of Atterberg limits values with natural water contents of foundation soils and use of the plasticity chart itself (Figure 3-1), together with split-spoon driving resistance, geological studies, and previous

experience often will indicate potentially weak and compressible fine-grained foundation strata and thus the

need for shear and perhaps consolidation tests. In some cases, in the design of low levees on familiar foundation deposits for example, correlations between Atterberg limits values and consolidation or shear strength

characteristics may be all that is necessary to evaluate these characteristics. Examples of correlations among

Atterberg limits values, natural water content, shear strength and consolidation characteristics are shown in

Figures 3-2 and 3-3. Correlations based on local soil types and which distinguish between normally and

overconsolidated conditions are preferable. Such correlations may also be used to reduce the number of tests

required for design of higher levees. As optimum water content may in some cases be correlated with Atterberg limits, comparisons of Atterberg limits and natural water contents of borrow soils as shown in

Figure 3-4 can indicate whether the borrow materials are suitable for obtaining adequate compaction.
300 u A 

zoo 

I 

100 

00 100 zoo 300 400 500 

LIQUID UMIT1 LL 

I I U-LINE: PI•0.9(LL•O) f-f- A-LINE: PI•0.73(LL- 20) 40 

v 

30 

I/ 

zo I/ 

IV CL "" v 

10 

l'-~L,-ML !>' MILt 9L 

I/ 

0 "" I lA I I 0 10 20 30 40 

LIQUID UMIT 1 LL 

Figure 3·1. Plasticity chart (ENG Form 4334) 

e8° eo 70 eo 

' 

70 ' 

eo 

v - CH 

50 

' ~ 

' '/ 

IV 

v 

MH&.OH 

I 

50 eo 70 

110 100 

"' I 

'-< T 

IJ•L ~ 

I-' 

D 

v t--A•L/!t 

PLASTICITY 

110 I~ 

10 

eo 

60 

40 

30 

20 

CHART 

m 

:s: w..a. 

o..a. 

>o 

~N I 

I\) ..a. OCQ 

o..a. 

ow 
EM 1110-2-1913 

30 Apr 2000 

o.s 

0.4 

c 

p v-~ 

---- 0.2 7 

0 20 40 60 

PI 

60 

a. c/p versus plasticity index for normally 

consolidated soils (after Bjerrum, ref. A-2) 

4 0 

3 S 

Vl 

~ 3 0 

a:: 

c, 

w 

0 

z 

" ~ 

" 

0 

~ ~ 

00~ 

0 K 0 

100 

• 2S 

'B. .......... 

20 

OA 

~ 

IS 

0 

0 

~ 0 

0 10 

c. <P' versus plasticity index 

20 30 40 so 

PLASTICITY IN DEX, PI 

6 B (I 

OCR • ,..,I 'we EOVERCONSOLIDATION 

RATIO 

b. SJovc versus overconsolidation 

ratio (after Ladd and Foott, 

1974, Ref. A-2) 

I I 

LEGEND 

SYMBOL DISTRICT 

0 ST. LOUIS -

0 MEMPHIS 

A VI C KS BURG 

..... 

0 A 

0 A 

-

---1--

- ( 0 

A 

60 70 80 

Figure 3-2. Example correlations of strength characteristics for fine-grained soils 

3-4 
.4 I I I I 

LEGEND 

f. 21-.SYMBOL. DISTRICT 

0 ST. LOUIS 

,0- 0 MEMPHIS 

4 VICKSBURG 

• NEW ORLEANS 

u 

u '· x 

IIJ 

D 

:: o. z 8 _NOTE: Cc ~ = 10.010 TO OoiSI W'l. 

0 H o. a: 

a. 

~ o. 

u 

4 

a. 2 

0 

• 

. ~ ~ ?6 .... lS 

.....---:::: 

A 

, 

... '~ ~ -... 0 • 

4 

UNEOF REGRESSION 

Cc=O.Oll 

A 

CLL·l61-

• ~ ~ ~ ..,..,.,.....-

""o 

. "' ~ 9/-

~~ :f>'' ~ • ~ 

~ • c.=o.oog (LL-10) 

, (TERZAGHI & PECK) 

• I 

I 

~ 

EM 1110-2-1913 

30 Apr 2000 

v 

..,........., 

0 10 20 30 so 60 7(1 60 90 too 110 120 130 

L.IQUIO I.. I MIT, I.. I.. 

a. Compression index versus liquid limit for normally consolidated soils 

u 

u 

x 

ltl 

0 

z 

z 

0 

·~ 4 

Ill 

a: 

Q. 

::£ 

0 

u 

VOID RATIO, e FOR Pc- 23.9 kPa (500 psf) 

b. Compression index versus initial void ratio for tidal marsh 

0 

Figure 3-3. Example correlations for consolidation characteristics of fine-grained soils (after Kapp, ref. A-2) 

3-5 
EM 1110-2-1913 

30 Apr 2000 

..; 

~ "' 

"'15 

~ z 

0 

j: 

"" c 

::; 

!il 

s 

u 

.. 

c 

~ 

u "' 

;;: 

.. 

"' 0 

u 

s 

2 

10" 2 

I 

6 

s 

~ 

3 

2 

I 

6 

s 

~ 

3 

2 

10" ~ 

I 

6 

. 

\ 

\ \. 

\. 

"\. "\. 

'\. 

'\. " ' ~ 1/HOI~rVRB~D ~AN Pl.~~: 

' I"\. r- C., IN liANG£ OF lfiRCIN COI-t~RE$JION 

1\. Cr IN RANG/! DF RI!CONPRI!J510N 

' ........ "' .-LJESAaorl! THI~ LOW I! If LIHIT 

' " ""- ~ 

' ........ 

.......... .......... !"'-. 

I ~ "' " CONI'LEri!LY '-frEHOLI)E/l ............ "' .sANP~~~: ~ " Cv ttl!~ lJELOW rill$ VPPER LIH IT r--.... ........... ......... 

"""f"-... -...... 

•o ll I 1~0 

LIQUID LlloiiT (LL) 

c. Coefficient of consolidation versus liquid limit {from NAVFAC DM-7 ref. A-1) 

200 NATURAL WATER CONTENT~") % 

2 

1 

0.7 

0.5 

0.3 

0.2 

0.1 

0.07 

o.os 

0.03 

0.02 

0.01 

0.007 

0.001 

d. Coefficient of secondary compression versus water content {from NAVFAC DM-7 ref. A-1) 

Figure 3-3. {Concluded) 

3-6 
E-< 

0 

0 

10 

20 

~30 

rz.. 

Z40 

..... 

70 

80 

90 

NATURAL WATER CONTENT 

AND ATTERBERG LIMITS 

{% DRY WEIGHT) 

20 40 60 80 100 120 

v •• . ~ . ( ~ 

. ii! ~- . ~ .: 0 . 

\' - . ~ . ... 

_;;;:; ~· I ~ 

~ . } \. 

., 

} \ 

l· . PLASTIC 

KANCil!.. 

( 

.) :1 

( ~ :=! 

y 

/ 

~ 

0 

3.05 

6.1 

UJ 

9.15 ~ E-< 

Pi! 

12.2 ~ 

z 

..... 15.2 ::r: 

E-< 

P.. 

18.3 ~ 

21.3 

24.4 

27.4 

Figure 3-4. Comparisons of Atterberg limits and natural 

water contents 

3-4. Shear Strength 

EM 1110-2-1913 

30 Apr 2000 

Approximate shear strengths of fine-grained 

cohesive soils can be rapidly determined on 

undisturbed foundation samples, and occasionally on reasonably intact samples from disturbed 

drive sampling, using simple devices such as the 

pocket penetrometer, laboratory vane shear 

device, or the miniature vane shear device (Torvane). To establish the reliability of these tests, 

it is desirable to correlate them with unconfined 

compression tests. Unconfined compression 

tests are somewhat simpler to perform than Q 

triaxial compression tests, but test results exhibit 

more scatter. Unconfined compression tests are 

appropriate primarily for testing saturated clays 

which are not jointed or slickensided. Of the 

triaxial compression tests, the Q test is the one 

most commonly performed on foundation clays, 

since the in situ undrained shear strength generally controls embankment design on such soils. 

However, where embankments are high, stage 

construction is being considered, or important 

structures are located in a levee system, R 

triaxial compression tests and S direct shear tests 

should also be performed. 

3-5. Consolidation 

Consolidation tests are performed for those cases 

listed in Table 3-1. In some locations correlations of liquid limit and natural water content with coefficient of consolidation, compression index, and 

coefficient of secondary compression can be used satisfactorily for making estimates of consolidation of 

foundation clays under load. 

3-6. Permeability 

Generally there is no need for laboratory permeability tests on fine-grained fill materials, nor on surface 

clays overlying pervious foundation deposits. In underseepage analyses, simplifying assumptions must be 

made relative to thickness and soil type of fine-grained surface blankets. Furthermore, animal burrows, root 

channels, and other discontinuities in surface blankets can significantly affect the overall effective permeability. Therefore, an average value of the coefficient of permeability based on the dominant soil type 

(Appendix B) is generally of sufficient accuracy for use in underseepage analyses, and laboratory tests are 

not essential. 

3-7. Compaction Tests 

The type and number of compaction tests will be influenced by the method of construction and the variability 

of available borrow materials. The types of compaction tests required are summarized in Table 3-1. 

3-7 
EM 1110-2-1913

30 Apr 2000

3-8

Section II

Coarse-Grained Soils

3-8. Shear Strength

When coarse-grained soils contain few fines, the consolidated drained shear strength is appropriate for use

in all types of analyses. In most cases, conservative values of the angle of internal friction (φ) can be

assumed from correlations such as those shown in Figure 3-5, and no shear tests will be needed.

3-9. Permeability

To solve the problem of underseepage in levee foundations, reasonable estimates of permeability of pervious

foundation deposits are required. However, because of difficulty and expense in obtaining undisturbed

samples of sands and gravels, laboratory permeability tests are rarely performed on foundation sands.

Instead, field pumping tests or correlations such as that of Figure 3-5 developed between a grain-size

parameter (such as D ) and the coefficient of permeability, k , are generally utilized. 10

3-10. Density Testing of Pervious Fill

Maximum density tests on available pervious borrow materials should be performed in accordance with

ASTM D 4253 so that relative compaction requirements for pervious fills may be checked in the field when

required by the specification. Due to the inconsistencies in duplicating minimum densities (ASTM D 4254),

relative density may not be used. Factors such as (but not limited to) site specific materials, availability of

testing equipment and local practice may make it more practical to utilize methods other than ASTM D 4253

and ASTM D 4254 to control the degree of compaction of cohesionless material. The other methods used

include comparison of in-place density to either the maximum Proctor density or the maximum density

obtained by ASTM 4253 (if vibratory table is available).
75 80 90 

45 

U) 

IZl 

IZl 

~40 

IZl 

e 

z 

0 

(;35 

1i:: 

""' ...:I 

~ 

lb/cu.ft 

DRY UNIT WEIGHT (")'0 ) 

100 110 120 130 140 

rfOBTAINED FROM 

EFFECTIVE STRESS 

FAILURE ENVELOPES 

EM 1110-2-1913 

30 Apr 2000 

150 

~30 t--1----7'-~---,.,<----,!" .:;;...-...,t:.:=:....:~,t:------I.L- APPROXIMATE CORRELATION E-o 

~ 

r... 

0 

e325 

CJ 

~ 56 

IS FOR COHESIONLESS 

MATERIALS WITHOUT 

PLASTIC FINES 

2240 2400 

a. Angle of internal friction versus unit weight (from NAVFAC DM-7 ref. A-1) 

Figure 3-5. Example correlations for properties of coarse-grained soils 

3-9 
EM 1110-2-1913 

30 Apr 2000 

0 

Ill 

1/) 

~ 0 

"" I 

~ 

)( 

:I! 

:J 

... 

< 

a: 

... 

1/) 

... 

0 

> 

... 

..J 

iii 

<· 

Ill 

:I! 

a: 

IIJ 

0. 

... 

0 

... 

z 

IIJ 

u 

i&: 

... 

Ill 

0 

0 

.n. 

• nl./ ~oc / 

2,000 HH-+t-t----+rr-·ji~/-<""~,.+-H-HH----1 

o ,rj g 

b.O " L'EGENO 

1

•

000 

J= t:lS:$!$~~~ES::::t=E~ WEl.':- = - HH-+t+f'l·.-..•·w-~· r-'-+1

9-"=+ •-+--HI- 0 H-151 A - H•llll: ~. 

A~~· e H-185 -

500 1-1-1-+++-~tfM~~~+---l-+-+rll- 0 FC-105 -

I~ • ES-39 -

HH--t-t-tl-1- 1 ....;..-t-----1--++-1- b. ES~4 -

• y • OR-1 

200 HH-+tl'f-----i--+-+-+--1- V l.D-1 -

I y L-2 

e 0 LO~ 

1001-1-H~+-----+-~-+-+~~··~·~·-----~ Jill 

NOTE: kH BASED ON FIEl.D PUMPING 

TESTS. 

2.0 

EFFECTIVE GRAIN Sl ZE OF STRATUM, 0 10 , MM 

b. Effective grain size, 0 10 versus coefficient of permeability, kh (from WES TM No. 3-424, ref. A-1) 

Figure 3-5. (Concluded) 

3-10 
EM 1110-2-1913

30 Apr 2000

4-1

Chapter 4

Borrow Areas

4-1. General

In the past borrow areas were selected largely on the basis of material types and quantities and haul

distances. Today, borrow areas receive much more attention and must be carefully planned and designed,

because of considerations such as environmental aspects, increasing land values, and greater recognition of

the effects of borrow areas with respect to underseepage, uplift pressures, overall levee stability, and erosion.

The following paragraphs discuss some factors involved in locating and using borrow areas.

4-2. Available Borrow Material

a. Material type. Almost any soil is suitable for constructing levees, except very wet, fine-grained soils

or highly organic soils. In some cases, though, even these soils may be considered for portions of levees.

Accessibility and proximity are often controlling factors in selecting borrow areas, although the availability

of better borrow materials involving somewhat longer haul distances may sometimes lead to the rejection

of poorer but more readily available borrow.

b. Natural water content. Where compacted levees are planned, it is necessary to obtain borrow material

with water content low enough to allow placement and adequate compaction. The cost of drying borrow

material to suitable water contents can be very high, in many cases exceeding the cost of longer haul

distances to obtain material that can be placed without drying. Borrow soils undergo seasonal water content

variations; hence water content data should be based on samples obtained from borrow areas in that season

of the year when levee construction is planned. Possible variation of water contents during the construction

season should also be considered.

4-3. General Layout

Generally, the most economical borrow scheme is to establish pits parallel and adjacent to the levee. If a

levee is adjacent to required channel excavation, levee construction can often utilize material from channel

excavation. Large centralized borrow areas are normally established only for the construction of urban

levees, where adjacent borrow areas are unavailable. Long, shallow borrow areas along the levee alignment

are more suitable, not only because of the shorter haul distance involved, but also because they better satisfy

environmental considerations.

a. Location. Where possible, borrow area locations on the river side of a levee are preferable as borrow

pits. Borrow area locations within the protected area are less desirable environmentally, as well as generally

being more expensive. Riverside borrow locations in some areas will be filled eventually by siltation,

thereby obliterating the man-made changes in the landscape. While riverside borrow is generally preferable,

required landside borrow from ponding areas, ditches, and other excavations should be used wherever

possible. A berm should be left in place between the levee toe and the near edge of the borrow area. The

berm width depends primarily on foundation conditions, levee height, and amount of land available. Its

width should be established by seepage analyses where pervious foundation material is close to the bottom

of the borrow pit and by stability analyses where the excavation slope is near the levee. Minimum berm

widths used frequently in the past are 12.2 m (40 ft) riverside and 30.5 m (100 ft) landside, but berm widths

should be the maximum practicable since borrow areas may increase the severity of underseepage effects.

In borrow area excavation, an adequate thickness of impervious cover should be left over underlying
EM 1110-2-1913

30 Apr 2000

4-2

pervious material. For riverside pits a minimum of 0.91 m (3 ft) of cover should be left in place, and for

landside pits the cover thickness should be adequate to prevent the formation of boils under expected

hydraulic heads. Topsoil from borrow and levee foundation stripping can be stockpiled and spread over the

excavated area after borrow excavation has been completed. This reinforces the impervious cover and

provides a good base for vegetative growth.

b. Size and shape. It is generally preferable to have riverside borrow areas “wide and shallow” as

opposed to “narrow and deep.” While this may require extra right-of-way and a longer haul distance, the

benefits derived from improved underseepage, hydraulic, and environmental conditions usually outweigh

the extra cost. In computing required fill quantities, a shrinkage factor of at least 25 percent should be

applied (i.e., borrow area volumes should be at least 125 percent of the levee cross-section volume). This

will allow for material shrinkage, and hauling and other losses. Right-of-way requirements should be

established about 4.6 to 6.1 m (15 to 20 ft) beyond the top of the planned outer slope of the borrow pit. This

extra right-of-way will allow for flattening or caving of the borrow slopes, and can provide maintenance

borrow if needed later.

4-4. Design and Utilization

a. Slopes. Excavation slopes of borrow areas should be designed to assure stability. This is particularly

important for slopes adjacent to the levee but could also be important for any slope whose top is near the

right-of-way limits. Borrow area slopes must also be flat enough to allow mowing, if required. Also, where

landside pits are to be placed back into cultivation, changes in grade must be gentle enough to allow farm

equipment to operate safely. The slopes of the upstream and downstream ends of riverside pits should be

flat enough to avoid erosion when subjected to flow at high water stages.

b. Depths. Depths to which borrow areas are excavated will depend upon factors such as (1) groundwater

elevation, (2) changes at depth to undesirable material, (3) preservation of adequate thickness of riverside

blanket, and (4) environmental considerations.

c. Foreshore. The foreshore is that area between the riverside edge of the borrow area and the riverbank

as shown in Figure 4-1. If a foreshore is specified (i.e., the borrow excavation is not to be cut into the

riverbank), it should have a substantial width, say 61 m (200 ft) or more, to help prevent migration of the

river channel into the borrow area.

d. Traverse. A traverse is an unexcavated zone left in place at intervals across the borrow area

(Figure 4-1). Traverses provide roadways across the borrow area, provide foundations for transmission

towers and utility lines, prevent less than bank-full flows from coursing unchecked through the borrow area,

and encourage material deposition in the borrow area during high water. Experience has shown that when

traverses are overtopped or breached, severe scour damage can result unless proper measures are taken in

their design. Traverse heights should be kept as low as possible above the bottom of the pit when they will

be used primarily as haul roads. In all cases, flat downstream slopes (on the order of 1V and 6H to 10H)

should be specified to minimize scour from overtopping. If the traverse carries a utility line or a public road,

even flatter slopes and possibly stone protection should be considered.

e. Drainage. Riverside borrow areas should be so located and excavated that they will fill slowly on a

rising river and drain fully on a falling river. This will minimize scour in the pit when overbank river stages

occur, promote the growth of vegetation, and encourage silting where reclamation is possible. The bottom

of riverside pits should be sloped to drain away from the levee. Culvert pipes should be provided through

traverses, and foreshore areas should be ditched through to the river as needed for proper drainage. Landside

pits should be sloped to drain away from or parallel to the levee with ditches provided as necessary to outlet
RIVER 

VARIES ---o-l 

BORROW 

AREA 

BORROW 

AREA 

VARIE.S 

w 

w 

EM 1110-2-1913 

30 Apr 2000 

f---~c:~---1 ..J 

Figure 4-1. Plan of typical levee and borrow areas with traverse and foreshore 

points. Gravity outlets or pump stations should be located so as to minimize lengths of flow paths within 

the pit area. 

f Flow conditions. To avoid damage from confined or restricted flow through the riverside borrow areas, 

obstructions or impediments to smooth and uniform flow should be removed if possible, or else protective 

measures must be taken. Riverside borrow areas should be made as uniform in width and grade as possible, 

avoiding abrupt changes. Removal of obstructions that could cause concentrated flow includes degradation 

of old levee remnants and of narrow high ground ridges beyond the borrow area, as well as removal of timber 

from traverses and from foreshore areas immediately adjacent to the borrow area. Obstructions to flow that 

cannot be removed include transmission towers, bridge piers, and other permanent structures near the levee. 

In such areas, stone protection should be provided for the levee or borrow area slopes if scour damage is 

considered probable. 

g. Environmental aspects. The treatment of borrow areas after excavation to satisfy aesthetic and 

environmental considerations has become standard practice. The extent of treatment will vary according to 

the type and location of a project. Generally, projects near urban areas or where recreational areas are to be 

developed will require more elaborate treatment than those in sparsely populated agricultural areas. 

Minimum treatment should include proper drainage, topographic smoothing, and the promotion of conditions 

conducive to vegetative growth. Insofar as practicable, borrow areas should be planted to conform to the 

surrounding landscape. Stands of trees should be left remaining on lands ide borrow areas if at all possible, 

and excavation procedures should not leave holes, trenches, or abrupt slopes. Restoration of vegetative 

growth is important for both landside and riverside pits as it is not only pleasing aesthetically but serves as 

protection against erosion. Willow trees can aid considerably in drying out boggy areas. Riverside pits 

should not be excavated so deep that restored grass cover will be drowned out by long submergence. 

4-3 
EM 1110-2-1913

30 Apr 2000

4-4

Agencies responsible for maintenance of completed levees should be encouraged to plant and maintain

vegetation, including timber, in the borrow areas. It is desirable that riverside borrow pits be filled in by

natural processes, and frequent cultivation of these areas should be discouraged or prohibited, if possible,

until this has been achieved. Guidelines for landscape planting are given in EM 1110-2-301. 

h. Clearing, grubbing, and stripping. Borrow areas should be cleared and grubbed to the extent needed

to obtain fill material free of objectionable matter, such as trees, brush, vegetation, stumps, and roots.

Subareas within borrow areas may be specified to remain untouched to preserve standing trees and existing

vegetation. Topsoil with low vegetative cover may be stripped and stockpiled for later placement on outer

landside slopes of levees and seepage berms.
EM 1110-2-1913

30 Apr 2000

5-1

Chapter 5

Seepage Control

Section I

Foundation Underseepage

5-1. General

Without control, underseepage in pervious foundations beneath levees may result in (a) excessive hydrostatic

pressures beneath an impervious top stratum on the landside, (b) sand boils, and (c) piping beneath the levee

itself. Underseepage problems are most acute where a pervious substratum underlies a levee and extends

both landward and riverward of the levee and where a relatively thin top stratum exists on the landside of

the levee. Principal seepage control measures for foundation underseepage are (a) cutoff trenches, (b) riverside

impervious blankets, (c) landside seepage berms, (d) pervious toe trenches, and (e) pressure relief wells.

These methods will be discussed generally in the following paragraphs. Detailed design guidance is given in

Appendixes B and C. Turnbull and Mansur (1959) have proposed control measures for underseepage also.

Additional information on seepage control in earth foundations including cutoffs, impervious blankets,

seepage berms, relief wells and trench drains is given in EM 1110-2-1901 and EM 1110-2-1914.

5-2. Cutoffs

A cutoff beneath a levee to block seepage through pervious foundation strata is the most positive means of

eliminating seepage problems. Positive cutoffs may consist of excavated trenches backfilled with compacted

earth or slurry trenches usually located near the riverside toe. Since a cutoff must penetrate approximately

95 percent or more of the thickness of pervious strata to be effective, it is not economically feasible to

construct cutoffs where pervious strata are of considerable thickness. For this reason cutoffs will rarely be

economical where they must penetrate more than 12.2 m (40 ft). Steel sheet piling is not entirely watertight

due to leakage at the interlocks but can significantly reduce the possibility of piping of sand strata in the

foundation. Open trench excavations can be readily made above the water table, but if they must be made

below the water table, well point systems will be required. Cutoffs made by the slurry trench method

(reference Appendix A) can be made without a dewatering system, and the cost of this type of cutoff should

be favorable in many cases in comparison with costs of compacted earth cutoffs.

5-3. Riverside Blankets

Levees are frequently situated on foundations having natural covers of relatively fine-grained impervious

to semipervious soils overlying pervious sands and gravels. These surface strata constitute impervious or

semipervious blankets when considered in connection with seepage control. If these blankets are continuous

and extend riverward for a considerable distance, they can effectively reduce seepage flow and seepage

pressures landside of the levee. Where underseepage is a problem, riverside borrow operations should be

limited in depth to prevent breaching the impervious blanket. If there are limited areas where the blanket

becomes thin or pinches out entirely, the blanket can be made effective by placing impervious materials in

these areas. The effectiveness of the blanket depends on its thickness, length, distance to the levee riverside

toe, and permeability and can be evaluated by flow-net or approximate mathematical solutions, as shown

in Appendix B. Protection of the riverside blanket against erosion is important.
EM 1110-2-1913 

30 Apr 2000 

5-4. Landside Seepage Berms 

a. General. If uplift pressures in pervious deposits underlying an impervious top stratum landward of 

a levee become greater than the effective weight of the top stratum, heaving and rupturing of the top stratum 

may occur, resulting in sand boils. The construction of landside berms (where space is available) can 

eliminate this hazard by providing (a) the additional weight needed to counteract these upward seepage 

forces and (b) the additional length required to reduce uplift pressures at the toe of the berm to tolerable 

values. Seepage berms may reinforce an existing impervious or semipervious top stratum, or, if none exists, 

be placed directly on pervious deposits. A berm also affords some protection against sloughing of the 

landside levee slope. Berms are relatively simple to construct and require very little maintenance. They 

frequently improve and reclaim land as areas requiring underseepage treatment are often low and wet. 

Berms can also serve as a source of borrow for emergency repairs to the levee. Because they require 

additional fill material and space, they are used primarily with agricultural levees. Subsurface profiles must 

be carefully studied in selecting berm widths. For example, where a levee is founded on a thin top stratum 

and thicker clay deposits lie a short distance landward, as shown in Figure 5-l, the berm should extend far 

enough landward to lap the thick clay deposit, regardless of the computed required length. Otherwise, a 

concentration of seepage and high exit gradients may occur between the berm toe and the landward edge of 

the thick clay deposit. 

/.AREA OF POSSIBLe r--L-i S~£PAGE CONCENTRATION 

·. ·· .. . ·· .. :·· .:~·.· ..... ·.··.:: . .. . . ..... '/J!' . •• 0 • .. ·.·.: .. ·.: ... · ... ·.·.·.· .. ·:.·.·:··.·.·::: . . . . . . . . . .. . .. . . . . • •• 0 0 •••••••• 

INCORRE:CT 

... • -. :r • 0 

... 

CORRECT 

Figure 5-1. Example of incorrect and correct berm length according to existing foundation conditions 

b. Types of seepage berms. Four types of seepage berms have been used, with selection based on 

available fill materials, space available landside of the levee proper, and relative costs. 

(1) Impervious berms. A berm constructed of impervious soils restricts the pressure relief that would 

otherwise occur from seepage flow through the top stratum, and consequently increases uplift pressures 

5-2 
EM 1110-2-1913

30 Apr 2000

5-3

beneath the top stratum. However, the berm can be constructed to the thickness necessary to provide an

adequate factor of safety against uplift.

(2) Semipervious berms. Semipervious material used in constructing this type of berm should have an

in-place permeability equal to or greater than that of the top stratum. In this type of berm, some seepage will

pass through the berm and emerge on its surface. However, since the presence of this berm creates additional

resistance to flow, subsurface pressures at the levee toe will be increased.

(3) Sand berms. While a sand berm will offer less resistance to flow than a semipervious berm, it may

also cause an increase in substratum pressures at the levee toe if it does not have the capacity to conduct

seepage flow landward without excessive internal head losses. Material used in a sand berm should be as

pervious as possible, with a minimum permeability of 100 x 10 cm per sec. Sand berms require less material -4

and occupy less space than impervious or semipervious berms providing the same degree of protection.

(4) Free-draining berms. A free-draining berm is one composed of random fill overlying horizontal sand

and gravel drainage layers (with a terminal perforated collector pipe system), designed by the same methods

used for drainage layers in dams. Although the free-draining berm can afford protection against

underseepage pressures with less length and thickness than the other types of seepage berms, its cost is

generally much greater than the other types, and thus it is rarely specified.

c. Berm design. Design equations, criteria, and examples are presented in Appendix C for seepage

berms. 

d. Computer programs to use for seepage analysis. 

(1) If the soil can be idealized with a top blanket of uniform thickness and seepage flow is assumed to be

horizontal in the foundation and vertical in the blanket, then LEVSEEP (Brizendine, Taylor, and Gabr 1995)

or LEVEEMSU (Wolff 1989; Gabr, Taylor, Brizendine, and Wolff 1995) could be used.

(2) If the soil profile is characterized by a top blanket and two foundation layers of uniform thickness,

and seepage flow is assumed to be horizontal in the foundation, horizontal and vertical in the transition layer,

and vertical in the blanket, then LEVEEMSU or the finite element method (CSEEP) could be used

(Biedenharn and Tracy 1987; Knowles 1992; Tracy 1994; Gabr, Brizendine, and Taylor 1995). LEVEESMU

would be simpler to use.

(3) If the idealized soil profile includes irregular geometry (slopes greater than 1 vertical to

100 horizontal), more than three layers and/or anisotropic permeability (k Ö k ), then only the finite element v h

method (CSEEP) is applicable. When using CSEEP it is recommended that FastSEEP, a graphical pre- and

post-processor, be used for mesh generation, assigning boundary conditions and soil properties, and viewing

the results (Engineering Computer Graphics Laboratory 1996).

5-5. Pervious Toe Trench

a. General. Where a levee is situated on deposits of pervious material overlain by little or no impervious

material, a partially penetrating toe trench, as shown in Figure 5-2, can improve seepage conditions at or near

the levee toe. Where the pervious stratum is thick, a drainage trench of any practicable depth would attract

only a small portion of the seepage flow and detrimental underseepage would bypass the trench.

Consequently, the main use of a pervious toe trench is to control shallow underseepage and protect the area

in the vicinity of the levee toe. Pervious toe trenches may be used in conjunction with relief well systems;
EM 1110-2-1913 

30 Apr 2000 

the wells collect the deeper seepage and the trench collects the shallow seepage. Such a system is shown 

in Figure 5-3. The trench is frequently provided with a perforated pipe to collect the seepage. The use of 

a collector system is dependent on the volume of seepage and, to some degree, the general location of the 

levee. Collector systems are usually not required for agricultural levees but find wider use in connection 

with urban levees. 

b. Location. As seen in Figures 5-2 and 5-3, pervious drainage trenches are generally located at the levee 

toe, but are sometimes constructed beneath the downstream levee slope as shown in Figure 5-4. Here the 

trench is located at the landward quarter point of the levee, and discharge is provided through a horizontal 

pervious drainage layer. Unless it is deep enough, it may allow excessive seepage pressures to act at the toe. 

There is some advantage to a location under the levee if the trench serves also as an inspection trench and 

because the horizontal pervious drainage layer can help to control embankment seepage. 

c. Geometry. Trench geometry will depend on the volume of expected underseepage, desired reduction 

in uplift pressure, construction practicalities, and the stability of the material in which it is being excavated. 

Trench widths varying from 0.61 to 1.83 m (2 to 6ft) have been used. Trench excavation can be expedited 

if a ditching machine can be used. However, narrow trench widths will require special compaction 

equipment. One such piece of equipment (Figure 5-5), which is a vibrating-plate type of compactor specially 

made to fit on the boom of a backhoe, has apparently performed satisfactorily. 

<t. 

WATERS tot I . LANDS IDE 

. . . . . .... • PERVIOUS STRATUM 

. . . 

Figure 5-2. Typical partially penetrating pervious toe trench 

d. Bac/ifi/1. The sand backfill for trenches must be designed as a filter material in accordance with 

criteria given in Appendix D. If a collector pipe is used, the pipe should be surrounded by about a 305-mm 

(1-ft) thickness of gravel having a gradation designed to provide a stable transition between the sand backfill 

and the perforations or slots in the pipe. A typical section of a pervious drainage trench with collector pipe 

is shown in Figure 5-6. Placement of trench backfill must be done in such a manner as to minimize 

segregation. Compaction of the backfill should be limited to prevent breakdown of material or over compaction resulting in lowered permeabilities. 

5-4 
RIVt':RSIOt: 

. . . . . . . · .. · ... 

r • • 

.. . . ..... 

£ 

I I 

PERVIOUS STRATUM 

EM 1110-2-1913 

30 Apr 2(100 

LANDS lOt. 

R£l.I£F' W£/.LS 

Figure 5-3. Typical pervious toe trench with collector pipe (Figure 5-6 shows trench details) 

f«VERSIDE 

. . . . . . . : . . . . . . . . . ~ .. ;.. .. . .. . . 

. . 

. 

I HORIZONrAt. 

DRAINAG~ l.AYER 

.. 

. ... 

Figure 5-4. Pervious toe trench located beneath landward slope 

5·6. Pressure Relief Wells 

LANOSID£ 

L 

• . 

a. General. Pressure relief wells may be installed along the landside toe of levees to reduce uplift 

pressure which may otherwise cause sand boils and piping of foundation materials. Wells accomplish this 

by intercepting and providing controlled outlets for seepage that would otherwise emerge uncontrolled 

landward of the levee. Pressure relief well systems are used where pervious strata underlying a levee are 

5-5 
EM 1110-2-1913 

30 Apr 2000 

too deep or too thick to be penetrated by cutoffs 

or toe drains or where space for landside berms 

is limited. Relief wells should adequately penetrate pervious strata and be spaced sufficiently 

close to intercept enough seepage to reduce to 

safe values the hydrostatic pressures acting 

beyond and between the wells. The wells must 

offer little resistance to the discharge of water 

while at the same time prevent loss of any soil. 

They must also be capable of resisting corrosion 

and bacterial clogging. Relief well systems can 

be easily expanded if the initial installation does 

not provide the control needed. Also, the discharge of existing wells can be increased by 

pumping if the need arises. A relief well system 

requires a minimum of additional real estate as 

compared with the other seepage control measures such as berms. However, wells require 

periodic maintenance and frequently suffer loss 

in efficiency with time, probably due to clogging 

of well screens by muddy surface waters, bacteria growth, or carbonate incrustation. They 

increase seepage discharge, and means for 

collecting and disposing of their discharge must 

be provided. 

b. Design of well systems. The design of a 

pressure relief well system involves determination of well spacing, size, and penetration to 

reduce uplift between wells to allowable values. 

Factors to be considered are (a) depth, stratification, and permeability of foundation soils, 

(b) distance to the effective source of seepage, 

(c) characteristics of the landside top stratum, if 

;;. any, and (d) degree of pressure relief desired. 

Figure 5-5. Special equipment for compacting sand in 

pervious toe trenches 

Guidance on the method used to determine well 

spacing, size, and penetration is contained in EM 

1110-2-1914 and U.S. Army Engineer Waterways Experiment Station TM No. 3-424. Where 

no control measures are present, relief wells for 

agricultural and urban levees should be designed 

so that imax midway between the wells or landward from the well line should not exceed 0.50 (equivalent to FS = 1.7 for an average soil saturated unit 

weight of 1840 kg/m3 (115 pet)). Many combinations of well spacing and penetration will produce the 

desired pressure relief; hence, the final selected spacing and penetration must be based on cost comparisons 

of alternative combinations. After the general well spacing for a given reach oflevee has been determined, 

the actual location of each well should be established to ensure that the wells will be located at critical 

seepage points and will fit natural topographic features. 

5-6 
. . .. . ''.· ........... '·· .. . .., .. ': ... . , ... . .. . . ·' . .. . . . . : .. ·"' '.:· ... :·-~: • ·::·. '.r • 

~LTER :II(AT~AL:. • Q 

• •. • •• ··(sAND)" •••• ~ ,... ,.. \ . ·. ' ~ 

... : .·· ·. ::--··· .. q :-... •• •-:•· •• \. fij ·. . .. . . . .. ' -~ • ·:· . :~ ··" ·'· •.• ., • n: f-l 

:·. :··· <.' ••• •• · oe: . A ,, . -~ • ,._ • P,. 

.... ' • ... • . .• • ~-··· ···~· . . ~ --~ p:: .. ~-.. .... . •. ·- ·~ ~: . 0 

·' •• ·: ·-. ~ '.; ~ ~~~ -~ E-c . ~ _-·~--·~-~ ·~ .. ~ ,~~:-/~.::!; _,@;u •1- ~ · ' ··-; -•. ~ · • ·--~·---.-~ :rac-li::l 

• -· • .- .. ·~ ·• . ' •• ~- •• --c;- ·a:: ::S . • • • _._. ... ·~·. • ~0 

····:-·· : • ·• ...... • • 0..0 

~·· : •· ·• ••••• r• . '-: .... ·. . 

Figure 5-6. Pervious toe trench with collector pipe 

EM 1110-2-1913 

30 Apr 2000 

c. Design of individual wells. The design of the 

well involves the selection of type and length of 

riser pipe and screen, design of the gravel pack, and 

design of well appurtenances. A widely used well 

design that has given good service in the past is 

shown in Figure 5-7. 

(1) Riser pipe and screen. The well screen 

normally extends from just below the top of the 

pervious stratum to the bottom of the well, with 

solid riser pipe installed from the top of the pervious 

strata to the surface. In zones of very fine sand or 

silt, the screen is replaced by unperforated (blank) 

pipe. The type of material for the riser and screen 

should be selected only after a careful study of the 

corrosive properties of the water to be carried by the 

well. Many types of metals, alloys, fiberglass, plastics, and wood have been used in the past. At the 

present time, stainless steel and plastic are the most 

widely used, primarily because of their corrosionresistant properties. Plastic risers should be considered with caution, being susceptible to damages 

during mechanical treatment or chemical treatment 

which develop excessive heat or cold. 

(2) Filter. The filter that surrounds the screen 

must be designed in accordance with criteria given 

in Appendix D using the slot size of the screen and 

the gradation of surrounding pervious deposit as a 

basis of design. No matter what size screen is used, 

a minimum of 152.4 mm (6 in.) of filter material 

should surround the screen and the filter should 

extend a minimum of610.8 mm (2ft) above the top 

and 1.2 m (4 ft) below the bottom of the well screen. Above the filter to the bottom of the concrete or 

impervious backfill, sand backfill may be used. 

(3) Well appurtenances. In selecting well appurtenances, consideration must be given to ease of 

maintenance, protection against contamination from back flooding, damage by debris, and vandalism. To 

prevent wells from becoming backflooded with muddy surface water, which greatly impairs their efficiency 

when they are not flowing, an aluminum check valve, rubber gasket, and plastic standpipe, as shown in 

Figure 5-7, can be installed on each well. To safeguard against vandalism, accidental damage, and the 

entrance of debris, the tops of the wells should be provided with a metal screen or flap-type gate. The 

elevation of the top of any protective standpipes must be used in design as the well discharge elevation. 

d. Well installation. Proper methods of drilling, backfilling, and developing a relief well must be 

employed or the well will be of little or no use. These procedures are described in detail in EM 1110-2-1914. 

5-7 
EM 1110-2-1913 

30 Apr 2000 

PLASTIC STAND PIPE 

Figure 5-7. Typical relief well 

Section II 

Seepage Through Embankments 

5-7. General 

PIPE 

THROUGH VERY 

FINE SAND OR 

SILT STRATA 

Should through seepage in an embankment emerge on the landside slope (Figure 5-8a), it can soften finegrained fill in the vicinity of the landside toe, cause sloughing of the slope, or even lead to piping (internal 

erosion) of fine sand or silt materials. Seepage exiting on the landside slope would also result in high 

seepage forces, decreasing the stability of the slope. In many cases, high water stages do not act against the 

levee long enough for this to happen, but the possibility of a combination of high water and a period ofheavy 

precipitation may bring this about. Iflandside stability berms or berms to control underseepage are required 

because of foundation conditions, they may be all that is necessary to prevent seepage emergence on the 

5-8 
RIVl:RSIDE 

EM 1110·2-1913 

30 Apr 2000 

LANDS IDE 

IYCT SLOP£ 

a. Homogeneous section on impervious foundation seepage emerging on landside slope 

RIVtRSIDE T.ANDSIDE 

GRAVEL OR I?OCK. 

b. Section with pervious toe 

RIVE:RSIOE LANDS IDE 

F!/...TER SAND 

c. Pervious toe combined with partially penetrating toe trencn 

Figure 5-8. Embankment with through seepage 

slope. On the other hand, if no berms are needed, lands ide slopes are steep, and floodstage durations and 

other pertinent considerations indicate a potential problem of seepage emergence on the slope, provisions 

should be incorporated in the levee section such as horizontal and/or inclined drainage layers or toe 

drains to prevent seepage from emerging on the landside slope. These require select pervious granular 

material and graded filter layers to ensure continued functioning, and therefore add an appreciable cost to 

the levee construction, unless suitable materials are available in the borrow areas with only minimal 

processing required. Where large quantities of pervious materials are available in the borrow areas, it may 

be more practicable to design a zoned embankment with a large landside pervious zone. This would provide 

an efficient means of through seepage control and good utilization of available materials. Additional 

information on seepage control in earth embankments including zoning embankments and vertical (or 

inclined) and horizontal drains is given in Chapter 8 of EM 1110-2-1901. 

5-9 
EM 1110-2-1913

30 Apr 2000

5-10

5-8. Pervious Toe Drain

A pervious toe (Figure 5-8b) will provide a ready exit for seepage through the embankment and can lower the

phreatic surface sufficiently so that no seepage will emerge on the landside slope. A pervious toe can also be

combined with partially penetrating toe trenches, which have previously been discussed, as a method for controlling shallow underseepage. Such a configuration is shown in Figure 5-8c.

5-9. Horizontal Drainage Layers

Horizontal drainage layers, as shown in Figure 5-9a, essentially serve the same purpose as a pervious toe but

are advantageous in that they can extend further under the embankment requiring a relatively small amount

of additional material. They can also serve to protect the base of the embankment against high uplift

pressures where shallow foundation underseepage is occurring. Sometimes horizontal drainage layers serve

also to carry off seepage from shallow foundation drainage trenches some distance under the embankment

as shown previously in Figure 5-4.

5-10. Inclined Drainage Layers

An inclined drainage layer as shown in Figure 5-9b is one of the more positive means of controlling internal

seepage and is used extensively in earth dams. It is rarely used in levee construction because of the added

cost, but might be justified for short levee reaches in important locations where landside slopes must be steep

and other control measures are not considered adequate and the levee will have high water against it for

prolonged periods. The effect of an inclined drainage layer is to completely intercept embankment seepage

regardless of the degree of stratification in the embankment or the material type riverward or landward of

the drain. As a matter of fact, the use of this type of drain allows the landside portion of a levee to be built

of any material of adequate strength regardless of permeability. When used between an impervious core and

outer pervious shell (Figure 5-9c), it also serves as a filter to prevent migration of impervious fines into the

outer shell. If the difference in gradation between the impervious and pervious material is great, the drain

may have to be designed as a graded filter (Appendix D). Inclined drains must be tied into horizontal

drainage layers to provide an exit for the collected seepage as shown in Figures 5-9b and 5-9c.

5-11. Design of Drainage Layers

The design of pervious toe drains and horizontal and inclined drainage layers must ensure that such drains

have adequate thickness and permeability to transmit seepage without any appreciable head loss while at the

same time preventing migration of finer soil particles. The design of drainage layers must satisfy the criteria

outlined in Appendix D for filter design. Horizontal drainage layers should have a minimum thickness of

457.2 mm (18 in.) for construction purposes.

5-12. Compaction of Drainage Layers

Placement and compaction of drainage layers must ensure that adequate density is attained, but should not

allow segregation and contamination to occur. Vibratory rollers are probably the best type of equipment for

compaction of cohesionless material although crawler tractors and rubber-tired rollers have also been used

successfully. Saturation or flooding of the material as the roller passes over it will aid in the compaction process and in some cases has been the only way specified densities could be attained. Care must always be taken

to not overcompact to prevent breakdown of materials or lowering of expected permeabilities. Loading, dumping, and spreading operations should be observed to ensure that segregation does not occur.

Gradation tests should be run both before and after compaction to ensure that the material meets specifications

and does not contain too many fines.
EM 1110-2-1913 

30 Apr 2000 

-R-IV_E_R_S_I_O_E __ __;~-·~,'?,.~---L-A-N_D_S_I_D_E a. Horizontal drainage layer 

RIVERSIDE: 

LANDS\ DE 

b. Inclined drainage layer-homogeneous embankment 

RIVERSIDE: 

LANDS IDE 

c. Inclined drainage layer-zoned embankment 

Figure 5-9. Use of horizontal and inclined drainage layers to control seepage through an embankment 

5-11 
EM 1110-2-1913

30 Apr 2000

6-1

Chapter 6

Slope Design and Settlement

Section I

Embankment Stability

6-1. Embankment Geometry

a. Slopes. For levees of significant height or when there is concern about the adequacy of available

embankment materials or foundation conditions, embankment design requires detailed analysis. Low levees

and levees to be built of good material resting on proven foundations may not require extensive stability

analysis. For these cases, practical considerations such as type and ease of construction, maintenance,

seepage and slope protection criteria control the selection of levee slopes. 

(1) Type of construction. Fully compacted levees generally enable the use of steeper slopes than those

of levees constructed by semicompacted or hydraulic means. In fact, space limitations in urban areas often

dictate minimum levee sections requiring select material and proper compaction to obtain a stable section.

(2) Ease of construction. A 1V on 2H slope is generally accepted as the steepest slope that can easily

be constructed and ensure stability of any riprap layers.

(3) Maintenance. A 1V on 3H slope is the steepest slope that can be conveniently traversed with

conventional mowing equipment and walked on during inspections.

(4) Seepage. For sand levees, a 1V on 5H landside slope is considered flat enough to prevent damage

from seepage exiting on the landside slope.

(5) Slope protection. Riverside slopes flatter than those required for stability may have to be specified

to provide protection from damage by wave action.

b. Final Levee Grade. In the past, freeboard was used to account for hydraulic, geotechnical,

construction, operation and maintenance uncertainties. The term and concept of freeboard to account for

these uncertainties is no longer used in the design of levee projects. The risk-based analysis directly

accounts for hydraulic uncertainties and establishes a nominal top of protection. Deterministic analysis using

physical properties of the foundation and embankment materials should be used to set the final levee grade

to account for settlement, shrinkage, cracking, geologic subsidence, and construction tolerances. 

c. Crown width. The width of the levee crown depends primarily on roadway requirements and future

emergency needs. To provide access for normal maintenance operations and floodfighting operations,

minimum widths of 3.05 to 3.66 m (10 to 12 ft) are commonly used with wider turnaround areas provided

at specified intervals; these widths are about the minimum feasible for construction using modern heavy

earthmoving equipment and should always be used for safety concerns. Where the levee crown is to be used

as a higher class road, its width is usually established by the responsible agency.

6-2. Standard Levee Sections and Minimum Levee Section

a. Many districts have established standard levee-sections for particular levee systems, which have

proven satisfactory over the years for the general stream regime, foundation conditions prevailing in those

areas, and for soils available for levee construction. For a given levee system, several different standard
EM 1110-2-1913

30 Apr 2000

6-2

sections may be established depending on the type of construction to be used (compacted, semicompacted,

uncompacted, or hydraulic fill). The use of standard sections is generally limited to levees of moderate

height (say less than 7.62 m (25 ft)) in reaches where there are no serious underseepage problems, weak

foundation soils, or undesirable borrow materials (very wet or very organic). In many cases the standard

levee section has more than the minimum allowable factor of safety relative to slope stability, its slopes

being established primarily on the basis of construction and maintenance considerations. Where high levees

or levees on foundations presenting special underseepage or stability problems are to be built, the uppermost

riverside and landside slopes of the levee are often the same as those of the standard section, with the lower

slopes flattened or stability berms provided as needed.

b. The adoption of standard levee sections does not imply that stability and underseepage analyses are

not made. However, when borings for a new levee clearly demonstrate foundation and borrow conditions

similar to those at existing levees, such analyses may be very simple and made only to the extent necessary

to demonstrate unquestioned levee stability. In addition to being used in levee design, the standard levee

sections are applicable to initial cost estimate, emergency and maintenance repairs.

c. The minimum levee section shall have a crown width of at least 3.05 m (10 ft) and a side slope flatter

than or equal to 1V on 2H, regardless of the levee height or the possibly less requirements indicated in the

results of stability and seepage analyses. The required dimensions of the minimum levee section is to

provide an access road for flood-fighting, maintenance, inspection and for general safety conditions.

6-3. Effects of Fill Characteristics and Compaction

a. Compacted fills. The types of compaction, water content control, and fill materials govern the

steepness of levee slopes from the stability aspect if foundations have adequate strength. Where foundations

are weak and compressible, high quality fill construction is not justified, since these foundations can support

only levees with flat slopes. In such cases uncompacted or semicompacted fill, as defined in paragraph 1-5,

is appropriate. Semicompacted fill is also used where fine-grained borrow soils are considerably wet of

optimum or in construction of very low levees where other considerations dictate flatter levee slopes than

needed for stability. Uncompacted fill is generally used where the only available borrow is very wet and

frequently has high organic content and where rainfall is very high during the construction season. When

foundations have adequate strength and where space is limited in urban areas both with respect to quantity

of borrow and levee geometry, compacted levee fill construction by earth dam procedures is frequently

selected. This involves the use of select material, water content control, and compaction procedures as

described in paragraph 1-5.

b. Hydraulic Fill. Hydraulic fill consists mostly of pervious sands built with one or two end-discharge

or bottom-discharging pipes. Tracked or rubber-tired dozers or front-end loaders are used to move the sand

to shape the embankment slopes. Because a levee constructed of hydraulic fill would be very pervious and

have a low density, it would require a large levee footprint and would be susceptible to soil liquefaction.

Hydraulic fill would also quickly erode upon overtopping or where an impervious covering was penetrated.

For these reasons, hydraulic fill may be used for stability berms, pit fills and seepage berms but shall not

normally be used in constructing levee embankments. However, hydraulic fill may be used for levees

protecting agricultural areas whose failure would not endanger human life and for zoned embankments that

include impervious seepage barriers. 
EM 1110-2-1913

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6-3

Section II

Stability Analyses

6-4. Methods of Analysis

The principal methods used to analyze levee embankments for stability against shear failure assume either

(a) a sliding surface having the shape of a circular arc within the foundation and/or the embankment or (b) a

composite failure surface composed of a long horizontal plane in a relatively weak foundation or thin

foundation stratum connecting with diagonal plane surfaces up through the foundation and embankment to

the ground surface. Various methods of analysis are described in EM 1110-2-1902, and can be chosen for

use where determined appropriate by the designer. Computer programs are available for these analyses, with

the various loading cases described in EM 1110-2-1902, so the effort of making such analyses is greatly

reduced, and primary attention can be devoted to the more important problems of defining the shear strengths,

unit weights, geometry, and limits of possible sliding surfaces.

6-5. Conditions Requiring Analysis

The various loading conditions to which a levee and its foundation may be subjected and which should be

considered in analyses are designated as follows: Case I, end of construction; Case II, sudden drawdown

from full flood stage; Case III, steady seepage from full flood stage, fully developed phreatic surface;

Case IV, earthquake. Each case is discussed briefly in the following paragraphs and the applicable type of

design shear strength is given. For more detailed information on applicable shear strengths, methods of

analysis, and assumptions made for each case refer to EM 1110-2-1902.

a. Case I - End of construction. This case represents undrained conditions for impervious embankment

and foundation soils; i.e., excess pore water pressure is present because the soil has not had time to drain

since being loaded. Results from laboratory Q (unconsolidated-undrained) tests are applicable to fine-grained

soils loaded under this condition while results of S (consolidated-drained) tests can be used for pervious soils

that drain fast enough during loading so that no excess pore water pressure is present at the end

of construction. The end of construction condition is applicable to both the riverside and landside slopes.

b. Case II - Sudden drawdown. This case represents the condition whereby a prolonged flood stage

saturates at least the major part of the upstream embankment portion and then falls faster than the soil can

drain. This causes the development of excess pore water pressure which may result in the upstream slope

becoming unstable. For the selection of the shear strengths see Table 6-1a. 

c. Case III - Steady seepage from full flood stage (fully developed phreatic surface). This condition

occurs when the water remains at or near full flood stage long enough so that the embankment becomes fully

saturated and a condition of steady seepage occurs. This condition may be critical for landside slope

stability. Design shear strengths should be based on Table 6-1a. 

d. Case IV - Earthquake. Earthquake loadings are not normally considered in analyzing the stability of

levees because of the low probability of earthquake coinciding with periods of high water. Levees constructed of loose cohesionless materials or founded on loose cohesionless materials are particularly

susceptible to failure due to liquefaction during earthquakes. Depending on the severity of the expected

earthquake and the importance of the levee, seismic analyses to determine liquefaction susceptibility may

be required. 
EM 1110-2-1913

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6-4

Table 6-1a

Summary of Design Conditions

Analysis Condition Shear Strength Pore Water Pressure a

During and End-of- Free draining soils - use effective Free draining soils - Pore water pressures can be estimated using

Construction stresses analytical techniques such as hydrostatic pressure computations for

no flow or steady seepage analysis techniques (flow nets, finite

element analyses or finite difference analyses).

Low permeability soils - use Low permeability soils - Total stresses are used; pore water

undrained strengths and total pressures are set to zero in the slope stability computations.

stressesb

Steady State Use effective stresses. Residual Estimated from field measurements of pore water pressures,

Seepage Conditions strengths should be used where hydrostatic pressure computations for no flow conditions, or steady

previous shear deformation or seepage analysis techniques (flow nets, finite element analyses or

sliding has occurred. finite difference analyses).

Sudden Drawdown Free draining soils - use effective Free draining soils - First stage computations (before drawdown) -

Conditions stresses steady-state seepage pore pressures as described for steady state

seepage condition. Second and third stage computations (after

drawdown) - pore water pressures estimated using same

techniques as for steady seepage, except with lowered water

levels. 

Low permeability soils - Three stage Low permeability soils - First stage computations - steady-state

computations: First stage use seepage pore pressures as described for steady state seepage

effective stresses; second stage condition.

use undrained shear strengths and Second stage computations - Total stresses are used pore water

total stresses; third stage use pressures are set to zero.

drained strengths (effective Third stage computations - Use same pore pressures as free

stresses) or undrained strengths draining soils if drained strengths are being used; where undrained

(total stresses) depending on which strengths are used pore water pressures are set to zero. 

strength is lower - this will vary

along the assumed shear surface. 

 Effective stress parameters can be obtained from consolidated-drained (CD, S) tests (either direct shear or triaxial) or consolidateda

undrained (CU, R) triaxial tests on saturated specimens with pore water pressure measurements. Direct shear or Bromhead ring shear

tests should be used to measure residual strengths. Undrained strengths can be obtained from unconsolidated-undrained (UU, Q) tests.

Undrained shear strengths can also be estimated using consolidated-undrained (CU, R) tests on specimens consolidated to appropriate

stress conditions representative of field conditions; however, the “R” or “total stress” envelope and associated c and ö, from CU, R tests

should not be used.

 For saturated soils use ö = 0; total stress envelope with ö > 0 is only applicable to partially saturated soils. b

6-6. Minimum Acceptable Factors of Safety

The minimum required safety factors for the preceding design conditions along with the portion of the

embankment for which analyses are required and applicable shear test data are shown in Table 6-1b.

6-7. Measures to Increase Stability

Means for improving weak and compressible foundations to enable stable embankments to be constructed

thereon are discussed in Chapter 7. Methods of improving embankment stability by changes in embankment

section are presented in the following paragraphs.

a. Flatten embankment slopes. Flattening embankment slopes will usually increase the stability of an

embankment against a shallow foundation type failure that takes place entirely within the embankment.

Flattening embankment slopes reduces gravity forces tending to cause failure, and increases the length of

potential failure surfaces (and therefore increases resistance to sliding).
EM 1110-2-1913

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6-5

Table 6-1b

Minimum Factors of Safety - Levee Slope Stability

 Applicable Stability Conditions and Required Factors of Safety 

End-of- Long-Term

Type of Slope Construction (Steady Seepage) Rapid Drawdown Earthquake a b

New Levees 1.3 1.4 1.0 to 1.2 (see below)

Existing Levees -- 1.4 1.0 to 1.2 (see below) c

Other Embankments and dikes 1.3 1.4 1.0 to 1.2 (see below) d e,f c,f f

 Sudden drawdown analyses. F. S. = 1.0 applies to pool levels prior to drawdown for conditions where these water levels are a

unlikely to persist for long periods preceding drawdown. F. S. = 1.2 applies to pool level, likely to persist for long periods prior to

drawdown.

 See ER 1110-2-1806 for guidance. An EM for seismic stability analysis is under preparation. b

 For existing slopes where either sliding or large deformation have occurred previously and back analyses have been performed to c

establish design shear strengths lower factors of safety may be used. In such cases probabilistic analyses may be useful in

supporting the use of lower factors of safety for design.

 Includes slopes which are part of cofferdams, retention dikes, stockpiles, navigation channels, breakwater, river banks, and d

excavation slopes.

 Temporary excavated slopes are sometimes designed for only short-term stability with the knowledge that long-term stability is e

not adequate. In such cases higher factors of safety may be required for end-of-construction to ensure stability during the time the

excavation is to remain open. Special care is required in design of temporary slopes, which do not have adequate stability for the

long-term (steady seepage) condition. 

 Lower factors of safety may be appropriate when the consequences of failure in terms of safety, environmental damage and f

economic losses are small. 

b. Stability berms. Berms essentially provide the same effect as flattening embankment slopes but are

generally more effective because of concentrating additional weight where it is needed most and by forcing

a substantial increase in the failure path. Thus, berms can be an effective means of stabilization not only for

shallow foundation and embankment type failures but for more deep-seated foundation failures as well.

Berm thickness and width should be determined from stability analyses and the length should be great

enough to encompass the entire problem area, the extent of which is determined from the soil profile.

Foundation failures are normally preceded by lateral displacement of material beneath the embankment toe

and by noticeable heave of material just beyond the toe. When such a condition is noticed, berms are often

used as an emergency measure to stabilize the embankment and prevent further movement. 

6-8. Surface Slides

Experience indicates that shallow slides may occur in levee slopes after heavy rainfall. Failure generally

occurs in very plastic clay slopes. They are probably the result of shrinkage during dry weather and moisture

gain during wet weather with a resulting loss in shear strength due to a net increase in water content, plus

additional driving force from water in cracks. These failures require maintenance and could be eliminated

or reduced in frequency by using less plastic soils near the surface of the slopes or by chemical stabilization

of the surface soils.
EM 1110-2-1913

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6-6

Section III

Settlement

6-9. General

Evaluation of the amount of postconstruction settlement that can occur from consolidation of both

embankment and foundation may be important if the settlement would result in loss of freeboard of the levee

or damage to structures in the embankment. Many districts overbuild a levee by a given percent of its height

to take into account anticipated settlement both of the foundation and within the levee fill itself. Common

allowances are 0 to 5 percent for compacted fill, 5 to 10 percent for semicompacted fill, 15 percent for

uncompacted fill, and 5 to 10 percent for hydraulic fill. Overbuilding does however increase the severity

of stability problems and may be impracticable or undesirable for some foundations.

6-10. Settlement Analyses

Settlement estimates can be made by theoretical analysis as set forth in EM 1110-1-1904. Detailed

settlement analyses should be made when significant consolidation is expected, as under high embankment

loads, embankments of highly compressible soil, embankments on compressible foundations, and beneath

steel and concrete structures in levee systems founded on compressible soils. Where foundation and

embankment soils are pervious or semipervious, most of the settlement will occur during construction. For

impervious soils it is usually conservatively assumed that all the calculated settlement of a levee built by a

normal sequence of construction operations will occur after construction. Where analyses indicate that more

foundation settlement would occur than can be tolerated, partial or complete removal of compressible

foundation material may be necessary from both stability and settlement viewpoints. When the depth of

excavation required to accomplish this is too great for economical construction, other methods of control

such as stage construction or vertical sand drains may have to be employed, although they seldom are

justified for this purpose.
EM 1110-2-1913

30 Apr 2000

7-1

Chapter 7

Levee Construction

Section I

Levee Construction Methods

7-1. Classification of Methods

a. Levee embankments classified according to construction methods used are listed in Table 7-1 for

levees composed of impervious and semipervious materials (i.e., those materials whose compaction

characteristics are such as to produce a well-defined maximum density at a specific optimum water content).

While the central portion of the embankment may be Category I (compacted) or II (semicompacted), riverside

and landside berms (for seepage or stability purposes) may be constructed by Category II or III

(uncompacted) methods.

b. Pervious levee fill consisting of sands or sands and gravels may be placed either in the dry with normal

earthmoving equipment or by hydraulic fill methods. Except in seismically active areas or other areas

requiring a high degree of compaction, compaction by vibratory means other than that afforded by tracked

bulldozers is not generally necessary. Where underwater placement is required, it can best be accomplished

with pervious fill using end-dumping, dragline, or hydraulic means, although fine-grained fill can be so

placed if due consideration is given to the low density and strength obtained using such materials.

Section II

Foundations

7-2. Foundation Preparation and Treatment

a. General. Minimum foundation preparation for levees consists of clearing and grubbing, and most

levees will also require some degree of stripping. Clearing, grubbing, stripping, the disposal of products

therefrom, and final preparation are discussed in the following paragraphs.

b. Clearing. Clearing consists of complete removal of all objectional and/or obstructional matter above

the ground surface. This includes all trees, fallen timber, brush, vegetation, loose stone, abandoned

structures, fencing, and similar debris. The entire foundation area under the levee and berms should be

cleared well ahead of any following construction operations.

c. Grubbing. Grubbing consists of the removal, within the levee foundation area, of all stumps, roots,

buried logs, old piling, old paving, drains, and other objectional matter. Grubbing is usually not necessary

beneath stability berms. Roots or other intrusions over 38.1 mm (1-1/2 in.) in diameter within the levee

foundation area should be removed to a depth of 0.91 m (3 ft) below natural ground surface. Shallow tile

drains sometimes found in agricultural areas should be removed from the levee foundation area. The sides

of all holes and depressions caused by grubbing operations should be flattened before backfilling. Backfill,

consisting or material similar to adjoining soils, should be placed in layers up to the final foundation grade

and compacted to a density equal to the adjoining undisturbed material. This will avoid “soft spots” under

the levee and maintain the continuity of the natural blanket.

d. Stripping. After foundation clearing and grubbing operations are complete, stripping is commenced.

The purpose of stripping is to remove low growing vegetation and organic topsoil. The depth of stripping

 
EM 1110-2-1913

30 Apr 2000

7-2 Table 7-1

Classification According to Construction Method of Levees Composed of Impervious and Semipervious MaterialsCategory Construction Method UseI. Compacted Specification of: Provides embankment section occupying minimum space. Provides 

strong embankments of low compressibility needed adjacent to

a. Water content range with respect to standard concrete structures or forming parts of highway systems.

effort optimum water content 

 b. Loose lift thickness (152.4 mm to 228.6 mm 

(6-9 in.))

c. Compaction equipment (sheepsfoot or rubber- Requires strong foundation of low compressibility and availability of

tired rollers) borrow materials with natural water contents reasonably close to

specified ranges.

d. Number of passes to attain a given percent

compaction based on standard maximum density

e. Minimum required density Used where field inspection is not constant throughout the project.

II. Semicompacted Compaction of fill materials at their natural water The most common type of levee construction used in reaches 

content (i.e., no water content control). Borrow where:materials known to be too wet would require some drying before placement. Placed in thicker lifts than a. There are no severe space limitations and steep-slopedCategory I (about 304.8 mm (12 in.)) and compacted Category I embankments are not required.either by controlled movement of hauling and spreadingequip ment or by fewer passes of sheepsfoot or rubber- b. Relatively weak foundations could not support steep-slopedtired rollers. Compaction evaluated relative to 15-blow Category I embankments.compaction test. 

c. Underseepage conditions are such as to required wider 

embankment base than is provided by Category I construction.

d. Water content of borrow materials or amount of rainfall during

construction season is such as not to justify Category I

 compaction.

III. Uncompacted a. Fill cast or dumped in place in thick layers with Levees infrequently constructed today using method a except for 

little or no spreading or compaction. temporary emergency. Both methods are used for construction 

of stability berms, pit fills and seepage berms. 

b. Hydraulic fill by dredge, often from channel 

excavation.
EM 1110-2-1913

30 Apr 2000

7-3

is determined by local conditions and normally varies from 152.4 to 304.8 mm (6 to 12 in.) Stripping is

usually limited to the foundation of the levee embankment proper, not being required under berms. All

stripped material suitable for use as topsoil should be stockpiled for later use on the slopes of the

embankment and berms. Unsuitable material must be disposed of by methods described in the next

paragraph.

e. Disposal of debris. Debris from clearing, grubbing, and stripping operations can be disposed of by

burning in areas where this is permitted. When burning is prohibited by local regulations, it needs to be

disposed of in an environmentally approved manner. 

f. Exploration trench. An exploration trench (often termed “inspection trench”) should be excavated

under all levees unless special conditions as discussed later warrant its omission. The purpose of this trench

is to expose or intercept any undesirable underground features such as old drain tile, water or sewer lines,

animal burrows, buried logs, pockets of unsuitable material, or other debris. The trench should be located

at or near the centerline of hauled fill levees or at or near the riverside toe of sand levees so as to connect

with waterside impervious facings. Dimensions of the trench will vary with soil conditions and embankment

configurations. Backfill should be placed only after a careful inspection of the excavated trench to ensure

that seepage channels or undesirable material are not present; if they are, they should be dug out with a base

of sufficient width to allow backfill compaction with regular compaction equipment. To backfill narrower

trenches properly, special compaction procedures and/or equipment will be required. Trenches should have

a minimum depth of 1.83 m (6 ft) except for embankment heights less than 1.83 m (6 ft), in which case the

minimum depth should equal the embankment height. Exploration trenches can be omitted where landside

toe drains beneath the levee proper constructed to comparable depths are employed (toe drains are discussed

in more detail later in this chapter).

g. Dewatering. Dewatering levee foundations for the purpose of excavation and back filling in the dry

is expensive if more than simple ditches and sumps are required, and is usually avoided if at all possible.

The cost factor may be an overriding consideration in choosing seepage control measures other than a

compacted cutoff trench, such as berms, blankets, or relief wells. Where a compacted cutoff trench

involving excavation below the water table must be provided, dewatering is essential. TM 5-818-5 provides

guidance in dewatering system design.

h. Final foundation preparation. Soft or organic spots in the levee foundation should be removed and

replaced with compacted material. Except in special cases where foundation surfaces are adversely affected

by remolding (soft foundations for instance), the foundation surface upon or against which fill is to be placed

should be thoroughly broken up to a depth of at least 152.4 mm (6 in.) prior to the placement of the first lift

of fill. This helps to ensure good bond between the foundation and fill and to eliminate a plane of weakness

at the interface. The foundation surface should be kept drained and not scarified until just prior to fill

placement in order to avoid saturation from rainfall.

7-3. Methods of Improving Stability

a. General. Levees located on foundation soils that cannot support the levee embankment because of

inadequate shear strength require some type of foundation treatment if the levee is to be built. Foundation

deposits that are prone to cause problems are broadly classified as follows: (1) very soft clays, (2) sensitive

clays, (3) loose sands, (4) natural organic deposits, and (5) debris deposited by man. Very soft clays are

susceptible to shear failure, failure by spreading, and excessive settlement. Sometimes soft clay deposits

have a zone of stronger clay at the surface, caused by dessication, which if strong enough may eliminate the

need for expensive treatment. Sensitive clays are brittle and even though possessing considerable strength

in the undisturbed state, are subject to partial or complete loss of strength upon disturbance. Fortunately,
EM 1110-2-1913

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7-4

extremely sensitive clays are rare. Loose sands are also sensitive to disturbance and can liquefy and flow

when subjected to shock or even shear strains caused by erosion at the toe of slopes. Most organic soils are

very compressible and exhibit low shear strength. The physical characteristics and behavior of organic

deposits such as peat can sometimes be predicted with some degree of accuracy. Highly fibrous organic soils

with water contents of 500 percent or more generally consolidate and gain strength rapidly. The behavior

of debris deposited by man, such as industrial and urban refuse, is so varied in character that its physical

behavior is difficult, if not impossible, to predict. The following paragraphs discuss methods of dealing with

foundations that are inadequate for construction of proposed levees.

b. Excavation and replacement. The most positive method of dealing with excessively compressible

and/or weak foundation soils is to remove them and backfill the excavation with suitable compacted material.

This procedure is feasible only where deposits of unsuitable material are not excessively deep. Excavation

and replacement should be used wherever economically feasible.

c. Displacement by end dumping.

(l) Frequently low levees must be constructed across sloughs and stream channels whose bottoms consist

of very soft fine-grained soils (often having high organic content). Although the depths of such deposits may

not be large, the cost of removing them may not be justified, as a levee of adequate stability can be obtained

by end-dumping fill from one side of the slough or channel, pushing the fill over onto the soft materials, and

continually building up the fill until its weight displaces the foundation soils to the sides and front. By continuing this operation, the levee can finally be brought to grade. The fill should be advanced with a V-shaped

leading edge so that the center of the fill is most advanced, thereby displacing the soft material to both sides.

A wave of displaced foundation material will develop (usually visible) along the sides of the fill and should

not be removed. A disadvantage of this method is that all soft material may not be displaced which could

result in slides as the embankment is brought up and/or differential settlement after construction. Since this

type of construction produces essentially uncompacted fill, the design of the levee section should take this

into account.

(2) When this method of foundation treatment is being considered for a long reach of levee over unstable

areas such as swamps, the possibility of facilitating displacement by blasting methods should be evaluated.

Blasters’ Handbook (1966) (Appendix A-2) presents general information on methods of blasting used to

displace soft materials.

(3) The end-dumping method is also used to provide a working platform on soft foundation soils upon

which construction equipment can operate to construct a low levee. In this case, only enough fill material

is hauled in and dozed onto the foundation to build a working platform or pad upon which the levee proper

can be built by conventional equipment and methods. Material forming the working platform should not be

stockpiled on the platform or a shear failure may result. Only small dozers should be used to spread and

work the material. Where the foundation is extremely weak, it may be necessary to use a small clamshell

to spread the material by casting it over the area.

d. Stage construction.

(1) General. Stage construction refers to the building of an embankment in stages or intervals of time.

This method is used where the strength of the foundation material is inadequate to support the entire weight

of the embankment, if built continuously at a pace faster than the foundation material can drain. Using this

method, the embankment is built to intermediate grades and allowed to rest for a time before-placing more

fill. Such rest periods permit dissipation of pore water pressures which results in a gain in strength so that

higher embankment loadings may be supported. Obviously this method is appropriate when pore water
EM 1110-2-1913

30 Apr 2000

7-5

pressure dissipation is reasonably rapid because of foundation stratification resulting in shorter drainage

paths. This procedure works well for clay deposits interspersed with highly pervious silt or sand seams.

However, such seams must have exits for the escaping water otherwise they themselves will become seats

of high pore water pressure and low strengths (pressure relief wells can be installed on the landside to

increase the efficiency of pervious layers in foundation clays). Initial estimates of the time required for the

needed strength gain can be made from results of consolidation tests and study of boring data. Piezometers

should be installed during construction to monitor the rate of pore water dissipation, and the resumption and

rate of fill placement should be based on these observations, together with direct observations of fill and

foundation behavior. Disadvantages of this method are the delays in construction operation, and uncertainty

as to its scheduling and efficiency.

(2) Prefabricated vertical (wick) drains. If the expected rate of consolidation under stage construction

is unacceptably slow, it may be increased by the use of prefabricated vertical (wick) drains. Such drains are

geotextile wrapped plastic cores that provide open flowage areas in the compressible stratum. Their purpose

is to reduce the length of drainage paths, thus speeding up primary consolidation. The wick drains are very

thin and about 101.6 mm (4 in.) wide. They can be pushed into place through soft soils over 30.5 m (100 ft)

deep. Before the drains are installed, a sand drainage blanket is placed on the foundation which serves not

only to tie the drains together and provide an exit for escaping pore water, but as a working platform as well.

This drainage blanket should not continue across the entire base width of the embankment, but should be

interrupted beneath the center.

e. Densification of loose sands. The possibility of liquefaction of loose sand deposits in levee

foundations may have to be considered. Since methods for densifying sands, such as vibroflotation, are

costly, they are generally not considered except in locations of important structures in a levee system.

Therefore, defensive design features in the levee section should be provided, such as wider levee crest, and

flatter slopes.

Section III

Embankments

7-4. Embankment Construction Control

a. Construction control of levees may present somewhat different problems from that of dams because:

(1) Construction operations may be carried on concurrently along many miles of levee, whereas the

majority of dams are less than about 0.8 km (0.5 mile) in length and only in a few cases are dams longer than

4.8 km (3 miles). This means that more time is needed to cover the operations on many levee jobs.

(2) While inspection staff and testing facilities are located at the damsite, levee inspection personnel

generally operate out of an area office which may be a considerable distance from the levee project.

(3) There are frequently fiscal restraints which prevent assigning an optimum number of inspectors on

levee work or even one full-time inspector on small projects. Under these conditions, the inspectors used

must be well-trained to observe construction operations, minimizing the number of field density tests in favor

of devoting more time to visual observations, simple measurements, and expedient techniques of classifying

soils, evaluating the suitability of their water content, observing behavior of construction equipment on the

fill, and indirectly assessing compacted field densities.

b. Although it has previously been stated that only limited foundation exploration and embankment

design studies are generally needed in areas where levee heights are low and foundation conditions adequate
EM 1110-2-1913

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7-6

(i.e., no question of levee stability), the need for careful construction control by competent inspection exists

as well as at those reaches where comprehensive investigations and analyses have been made. Some of the

things that can happen during construction that can cause failure or distress of even low embankments on

good foundations are given in Table 7-2.

Table 7-2

Embankment Construction Deficiencies

 

Deficiency Possible Consequences

Organic material not stripped from foundation Differential settlements; shear failure; internal erosion

caused by through seepage

Highly organic or excessively wet or dry fill Excessive settlements; inadequate strength

Placement of pervious layers extending completely through Allows unimpeded through seepage which may lead 

the embankment to internal erosion and failure

Inadequate compaction of embankment (lifts too thick, Excessive settlements; inadequate strength; through 

haphazard coverage by compacting equipment, etc.) seepage

Inadequate compaction of backfill around structures in embankment Excessive settlements; inadequate strength; provides

seepage path between structure and material which

may lead to internal erosion and failure by piping

7-5. Embankment Zoning

As a general rule levee embankments are constructed as homogeneous sections because zoning is usually

neither necessary nor practicable. However, where materials of varying permeabilities are encountered in

borrow areas, the more impervious materials should be placed toward the riverside of the embankment and

the more pervious material toward the landside slope. Where required to improve underseepage conditions,

landside berms should be constructed of the most pervious material available and riverside berms of the more

impervious materials. Where impervious materials are scarce, and the major portion of the embankment

must be built of pervious material, a central impervious core can be specified or, as is more often done, the

riverside slope of the embankment can be covered with a thick layer of impervious material. The latter is

generally more economical than a central impervious core and, in most cases, is entirely adequate.

7-6. Protection of Riverside Slopes

a. The protection needed on a riverside slope to withstand the erosional forces of waves and stream

currents will vary, depending on a number of factors:

(1) The length of time that floodwaters are expected to act against a levee. If this period is brief, with

water levels against the levee continually changing, grass protection may be adequate, but better protection

may be required if currents or waves act against the levee over a longer period.

(2) The relative susceptibility of the embankment materials to erosion. Fine-grained soils of low

plasticity (or silts) are most erodible, while fat clays are the least erodible.

(3) The riverside slope may be shielded from severe wave attack and currents by timber stands and wide

space between the riverbank and the levee.
EM 1110-2-1913

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7-7

(4) Structures riverside of the levee. Bridge abutments and piers, gate structures, ramps, and drainage

outlets may constrict flow and cause turbulence with resultant scour.

(5) Turbulence and susceptibility to scour may result if levee alignment includes short-radius bends or

if smooth transitions are not provided where levees meet high ground or structures.

(6) Requirements for slope protection are reduced when riverside levee slopes are very flat as may be

the case for levees on soft foundations. Several types of slope protection have been used including grass

cover, gravel, sand-asphalt paving, concrete paving, articulated concrete mat, and riprap, the choice

depending upon the degree of protection needed and relative costs of the types providing adequate protection.

b. Performance data on existing slopes under expected conditions as discussed above are invaluable

in providing guidance for the selection of the type of slope protection to be used.

c. Sometimes it may be concluded that low cost protection, such as grass cover, will be adequate in

general for a levee reach, but with a realization that there may be limited areas where the need for greater

protection may develop under infrequent circumstances. If the chances of serious damage to the levee in

such areas are remote, good engineering practice would be to provide such increased protection only if and

when actual problems develop. Of course, it must be possible to accomplish this expeditiously so that the

situation will not get out of hand. In any event, high-class slope protection, such as riprap, articulated mat,

or paving should be provided on riverside slopes at the following locations:

(1) Beneath bridges, since adequate turf cannot be generally established because of inadequate sunlight.

(2) Adjacent to structures passing through levee embankments.

d. Riprap is more commonly used than other types of revetments when greater protection than that

afforded by grass cover is required because of the relative ease of handling, stockpiling, placement, and

maintenance. Guidance on the design of riprap revetment to protect slopes against currents is presented in

EM 1110-2-1601. Where slopes are composed of erodible granular soils or fine-grained soils of low

plasticity, a bedding layer of sand and gravel or spalls, or plastic filter cloth should be provided beneath the

riprap.

e. When suitable rock is not available within economical haul distances, soil cement may provide the

most economical slope protection (see Appendix G). 
EM 1110-2-1913

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8-1

Chapter 8

Special Features

Section I

Pipelines and Other Utility Lines Crossing Levees

8-1. General Considerations

a. Serious damage to levees can be caused by inadequately designed or constructed pipelines, utility

conduits, or culverts (all hereafter referred to as “pipes”) beneath or within levees. Each pipe crossing should

be evaluated for its potential damage which would negatively impact the integrity of the flood protection

system and could ultimately lead to catastrophic failure. During high water, seepage tends to concentrate

along the outer surface of pipes resulting in piping of fill or foundation material. High water also results in

uplift pressures that may cause buoyancy of some structures. Seepage may also occur because of leakage

from the pipe. In the case of pipes crossing over levees, leakage can cause erosion in the slopes. In addition,

loss of fill or foundation material into the pipe can occur if joints are open. The methods of pipe installation

should be understood by the designer to anticipate problems that may occur. Some of the principal

inadequacies that are to be avoided or corrected are as follows:

(1) Pipes having inadequate strength to withstand loads of overlying fill or stresses applied by traffic.

(2) Pipe joints unable to accommodate movements resulting from foundation or fill settlement.

(3) Unsuitable backfill materials or inadequately compacted backfill.

(4) High pressures from directional drilling that could result in hydro-fracturing the surrounding

materials.

b. Some state and local laws prohibit pipes from passing through or under certain categories of levees.

As a general rule, this should not be done anyway, particularly in the case of pressure lines. However, since

each installation is unique, pipes in some instances may be allowed within the levee or foundation. Major

factors to be considered in deciding if an existing pipe can remain in place under a new levee or must be

rerouted over the levee, or if a new pipe should be laid through or over the levee are as follows:

(1) The height of the levee.

(2) The duration and frequency of high water stages against the levee.

(3) The susceptibility to piping and settlement of levee and foundation soils.

(4) The type of pipeline (low or high pressure line, or gravity drainage line).

(5) The structural adequacy of existing pipe and pipe joints, and the adequacy of the backfill compaction.

(6) The feasibility of providing closure in event of ruptured pressure lines, or in the event of failure of

flap valves in gravity lines during high water.

(7) The ease and frequency of required maintenance.
EM 1110-2-1913

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8-2

(8) The cost of acceptable alternative systems.

(9) Possible consequences of piping or failure of the pipe.

(10) Previous experience with the owner in constructing and maintaining pipelines.

General criteria for pipes crossing levees are given in Table 8-1.

Table 8-1

Criteria for Pipelines Crossing Levees

Leaving Existing Pipeline

 in Foundations of New Pipeline Installation 

Pipelines Proposed Levees Pipes Through Levees Pipes Over Levees

Must be known to be in good condition X

Must have adequate strength to withstand levee loading X X

Must have adequate cover as needed

to prevent damage by vehicular

traffic or heavy equipment X

Must have adequate cover for frost

protection X

Must have sufficient flexibility in

joints to adjust under expected

settlement and stretching of pipe X X X

Pressure lines must have provisions

for rapid closure in event of

leakage or rupture X X X

Gravity discharge pipes must have

provisions for emergency closure

in event of inoperative flap

valves on riverside end X X

Must have pervious backfill under

landside third of levee where:

 a. Foundation materials are

 susceptible to piping X

 b. Levee materials are

 susceptible to piping X

8-2. General Considerations for Pipelines Crossing Through or Under Levees

a. General. As has been noted previously, it is preferable for all pipes to cross over a levee rather than

penetrate the embankment or foundation materials. This is particularly true for pipes carrying gas or fluid

under pressure. Before consideration is given to allowing a pressure pipe (and possibly other types of pipe)

to extend through or beneath the levee, the pipe owner should provide an engineering study to support his

request for such installation. The owner, regardless of the type of pipe, should show adequate capability to

properly construct and/or maintain the pipe. Future maintenance of pipe by the owner must be carefully
EM 1110-2-1913

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8-3

evaluated. It may be necessary to form an agreement to the effect that should repairs to a pipe in the levee

become necessary, the pipe will be abandoned, sealed, and relocated over the levee.

b. Existing pipes

(1) All existing pipelines must be located prior to initiation of embankment construction. As previously

noted, inspection trenches may reveal abandoned pipes not on record. It is preferable that all abandoned

pipes be removed during grubbing operations and the voids backfilled. Any existing pipe should meet or

be made to meet the criteria given in Table 8-1. If this is not feasible and removal is not practical, they

should be sealed, preferably by completely filling them with concrete. Sealed pipes must also meet the

criteria given in Table 8-1 relating to prevention of seepage problems.

(2) In general, existing pressure pipes should be relocated over the proposed new levee. Rupture or

leakage from such pipes beneath a levee produces extremely high gradients that can have devastating effects

on the integrity of the foundation. Therefore, as indicated by the criteria in Table 8-1, it is imperative that

pressure pipes be fitted with rapid closure valves or devices to prevent escaping gas or fluid from damaging

the foundation.

(3) Although gravity drainage lines may be allowed or even required after the levee is completed, it is

likely that existing pipes will not have sufficient strength to support the additional load induced by the

embankment. Therefore, existing pipes must be carefully evaluated to determine their supporting capacity

before allowing their use in conjunction with the new levee.

c. New Pipelines. Generally, the only new pipelines allowed to penetrate the foundation or

embankment of the levee are gravity drainage lines. The number of gravity drainage structures should be

kept to an absolute minimum. The number and size of drainage pipes can be reduced by using such

techniques as ponding to reduce the required pipe capacity. 

8-3. General Considerations for Pipelines Crossing Over Levees

In the past the term and concept of freeboard was used to account for hydraulic, geotechnical, construction,

operation and maintenance uncertainties. Pipelines crossing over the levee were encouraged to be within

the freeboard zone to reduce or eliminate many of the dangers that are inherent with pipelines crossing

through the embankment or foundation. The term and concept of freeboard to account for these uncertainties

is no longer used in the design of levee projects. Therefore, since freeboard no longer exists, pipes must

cross over the completed levee cross section. Problems do exist, however, with pipelines crossing over the

levee. These pipes must be properly designed and constructed to prevent (a) flotation if submerged,

(b) scouring or erosion of the embankment slopes from leakage or currents, and (c) damage from debris

carried by currents, etc. In some areas climatic conditions will require special design features. Guidance

on design methods and construction practices will be given later in this chapter.

8-4. Pipe Selection

a. EM 1110-2-2902 contains a discussion of the advantages and disadvantages of various types of pipe

(i.e., corrugated metal, concrete, cast iron, steel, clay, etc.). The selection of a type of pipe is largely

dependent upon the substance it is to carry, its performance under the given loading, including expected

deflections or settlement, and economy. Although economy must certainly be considered, the overriding

factor must be safety, particularly where urban levees are concerned.
EM 1110-2-1913

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8-4

b. The earth load acting on a pipe should be determined as outlined in EM 1110-2-2902. Consideration

must also be given to live loads imposed from equipment during construction and the loads from traffic and

maintenance equipment after the levee is completed. The respective pipe manufacturers organizations have

recommended procedures for accounting for such live loads. These recommended procedures should be followed unless the pipe or roadway owners have more stringent requirements.

c. Required strengths for standard commercially available pipe should be determined by the methods

recommended by the respective pipe manufacturers organizations. Where cast-in-place pipes are used,

design procedures outlined in EM 1110-2-2902 should be followed. Abrasion and corrosion of corrugated

steel pipe should be accounted for in design using the method given in Federal Specification WW-P-405B(1)

(Appendix A) for the desired design life. The design life of a pipe is the length of time it will be in service

without requiring repairs. The term does not imply the pipe will fail at the end of that time. Normally, a

design life of 50 years can be economically justified. Corrugated pipe should always be galvanized and

protected by a bituminous or other acceptable coating as outlined in EM 1110-2-2902. Protective coatings

may be considered in determining the design life of a pipe.

d. Leakage from or infiltration into any pipe crossing over, through, or beneath a levee must be prevented. Therefore, the pipe joints as well as the pipe itself must be watertight. For pipes located within or

beneath the embankment, the expected settlement and outward movement of the soil mass must be

considered. Where considerable settlement is likely to occur the pipe should be cambered (para 8-7). Generally, flexible corrugated metal pipes are preferable for gravity lines where considerable settlement is

expected. Corrugated metal pipe sections should be joined by exterior coupling bands with a gasket to assure

watertightness. Where a concrete pipe is required and considerable settlement is anticipated, a pressure-type

joint with concrete alignment collars should be used. The collars must be designed either to resist or

accommodate differential movement without losing watertight integrity. Where settlement is not significant,

pressure-type joints capable of accommodating minor differential movement are sufficient. Design details

for concrete collars are shown in EM 1110-2-2902. Cast iron and steel pipes should be fitted with flexible

bolted joints. Steel pipe sections may be welded together to form a continuous conduit. All pressure pipes

should be pressure tested at the maximum anticipated pressure before they are covered and put into use.

e. During the design, the potential for electrochemical or chemical reactions between the substratum

materials or groundwater and construction materials should be determined. If it is determined that there will

be a reaction, then the pipe and/or pipe couplings should be protected. The protective measures to be taken

may include the use of cathodic protection, coating of the pipe, or use of a corrosion-resistant pipe material.

8-5. Antiseepage Devices

a. Antiseepage devices have been employed in the past to prevent piping or erosion along the outside

wall of the pipe. The term “antiseepage devices” usually referred to metal diaphragms (seepage fins) or

concrete collars that extended from the pipe into the backfill material. The diaphragms and collars were

often referred to as “seepage rings.” However, many piping failures have occurred in the past where seepage

rings were used. Assessment of these failures indicated that the presence of seepage rings often results in

poorly compacted backfill at its contact with the structure.

b. Where pipes or conduits are to be constructed through new or existing levees:

(1) Seepage rings or collars should not be provided for the purpose of increasing seepage resistance.

Except as provided herein, such features should only be included as necessary for coupling of pipe sections

or to accommodate differential movement on yielding foundations. When needed for these purposes, collars

with a minimum projection from the pipe surface should be used.
EM 111-0-2-1913 

30 Apr 2000 

(2) A 0.45-m (18-in.) annular thickness of drainage fill should be provided around the landside third of 

the pipe, regardless of the size and type of pipe to be used, where lands ide levee zoning does not provide for 

such drainage fill. For pipe installations within the levee foundation, the 0.45-m (18-in.) annular thickness 

of drainage fill shall also be provided, to include a landside outlet through a blind drain to ground surface 

at the levee toe, connection with pervious underseepage features, or through an annular drainage fill outlet 

to ground surface around a manhole structure. Figure 8-1 shows typical sections of drainage structures 

through levees. Figure 8-2 shows typical precast conduits through the levee. 

L.ANDSIDE 

Dralna9e Fill 

Inlet structure for 

concrete pipe 

~ of Levee 

Reinforced 

concrete pipe 

elnforced concrete pipe 

RNERSIDE 

Reinforced concrete 

outlet structure , 

0/sclxirQe pipes from pump/nQ 

plants rrey terminate In Qatewe/ls 

Outlet structure 

Flap 9ate required 

for fast-rlslnQ streams 

Figure 8-1. Typical sections, drainage structures through levees 

8-6. Closure Devices 

a. All pipes allowed to penetrate the embankment or foundation of a levee must be provided with 

devices to assure positive closure. Gravity lines should be provided with flap-type or slide-type service gates 

on the riverside of the levee. Automatic flap-type gates are usually used where the water is likely to rise 

to the "Gate Closing Stage" rather suddenly and where the water stage is likely to fluctuate within a few feet 

above and below the "Gate Closing Stage" for prolonged periods of time during flood season. Automatic 

gates are also required on slower rising streams or bodies of water where frequent visits from operating 

personnel are not practical. 

b. Slide-type gates are usually preferred as service gates where the rate of rise of the water during major 

floods is slow, enough (minimum of 12-hr flood prediction time) to give ample time for safe operation. The 

principal advantages of the slide gate in comparison with automatic flap gates are greater reliability of 

operation and the ease with which emergency closure can be made in event obstructions prevent closure of 

the gate. Usually emergency closure can be made by filling the manhole with sandbags. The obvious 

8-5 
EM 1110-2-1913 

30 Apr 2000 

Inlet Structure 

for Pipe 

lANDSIDE 

\__Reinforced precast 

concrete 

Figure 8-2. Typical precast conduit (levees) 

LS i of Levee 

Floor Stand RIVERSIDE 

disadvantage of slide type gates is that personnel must be on hand for their operation. Also their initial cost 

is generally greater than that for a flap-type gate. 

c. A slide-type gate with a flap-type gate attachment is often used and affords the advantages of automatic flap gate operation with the added safety of the slide-type gate. Such installations usually eliminate 

the need for a supplemental emergency gate as described below. 

d. Experience has shown that service gates occasionally fail to close completely during critical flood 

periods because of clogging by debris, mechanical malfunctions, or other causes. This, of course, can cause 

flooding of, the protected areas. Supplemental emergency gates are intended to minimize these risks insofar 

as necessary and economically practical. For an emergency gate to be effective it must be located so that 

its controls are accessible during flood stage. Provisions required for emergency protection of other areas 

should be consistent with the risks and cost involved. 

e. Pressure pipes should be fitted with valves at various stations that can be closed rapidly to prevent 

gas or fluid from escaping within or beneath a levee should the pipe rupture within these areas. Provisions 

for closure of pressure pipes on the water side must also be provided to prevent backflow of floodwater into 

the protected area should the pipe rupture. These requirements should generally be followed in other areas, 

but may be relaxed to be consistent with the risks and costs involved. 

8-7. Camber 

The alignment of a gravity structure must be such as to provide for a continuous slope toward the outlet. 

Settlement of the embankment and foundation can significantly alter the initial grade line of a pipe. 

Therefore, the expected settlement of the levee must be considered in establishing the initial grade line. If 

the settlement will result in an upward gradient in the direction of flow or not allow the desired gradient to 

be maintained, the pipe should be cambered. The amount of camber required can usually be taken as the 

mirror image of the settlement curve along a line established by the final required grade. The camber should 

then be laid out, preferably as a vertical curve, on a grade such that all parts of the pipe will slope toward the 

outlet when installed. If the gradient of the pipe is limited and the camber will initially result in a slope away 

from the outlet, the portion of the pipe from the inlet up to the point of greatest load may be installed level. 

The remaining portion of the pipe is then installed on a vertical curve tangent to the first portion of the pipe. 

8-6 
EM 1110-2-1913

30 Apr 2000

8-7

Regardless of the type of pipe selected, movements at the joints must be considered as discussed in

paragraph 8-4d.

8-8. Installation Requirements

a. General. The installation of pipes or other structures within the levee or foundation probably

requires the greatest care and the closest supervision and inspection of any aspect of levee construction.

Most failures of levee systems have initiated at the soil-structure interface and therefore every effort must

be made to ensure that these areas are not susceptible to piping. Of overriding importance is good

compaction of the backfill material along the structure. Pipes installed by open trench excavation should

be installed in the dry and a dewatering system should be used where necessary. Pipes installed by

directional drilling, microtunneling, or other trenchless methods require special consideration. 

b. Pipes crossing through or beneath levees

(1) The preferred method of installing pipes within the embankment or foundation of a levee has

historically been by the open cut method. Preferably, new levees should be brought to a grade about

610.8 mm (2 ft) above the crown of the pipe. This allows the soil to be preconsolidated before excavating

the trench. The trench should be excavated to a depth of about 610.8 mm (2 ft) below the bottom of the pipe

and at least 1.2 m (4 ft) wider than the pipe. The excavated material should be selectively stockpiled so that

it can be replaced in a manner that will not alter the embankment zoning if there is some or will result in the

more impervious soils on the riverside of the levee.

(2) After the trench has been excavated, it should be backfilled to the pipe invert elevation. In

impervious zones, the backfill material should be compacted with mechanical compactors to 95 percent standard density at about optimum water content.

(3) First-class bedding should be used for concrete pipe and other rigid pipe, as shown in EM 1110-2-

2902 except no granular bedding should be used in impervious zones. For flexible pipe, the trench bottom

should be flat to permit thorough tamping of backfill under the haunches of the pipe. Backfill should be

compacted to 95 percent standard density at about optimum water content. The backfill should be brought

up evenly on both sides of the pipe to avoid unequal side loads that could fail or move the pipe. Special care

must be taken in the vicinity of any protrusions such as joint collars to ensure proper compaction. Where

granular filter material is required, it should be compacted to a minimum of 80 percent relative density. In

areas where backfill compaction is difficult to achieve, flowable, low strength concrete fill has been used

to encapsulate pipes in narrow trenches.

(4) In existing levees, the excavation slopes should be stable, meet OSHA criteria, but in no case be

steeper than 1V on 1H. The excavated material should be selectively stockpiled as was described for new

levees. The pipe is installed as described in the previous paragraphs. Impervious material within 0.61 m

(2 ft) of the pipe walls should be compacted to 95 percent standard density at optimum water content, with

the remainder of the backfill placed at the density and water content of the existing embankment.

(5) Installation of pipes in existing levees by directional drilling, microtunneling, tunneling or jacking

may be considered. It is recognized, that in some instances, installation by the open cut method is not

feasible or cannot be economically justified. Where trenchless methods are allowed, special considerations

are required. 

(6) Pipes under levees. 
EM 1110-2-1913

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8-8

(a) General. Pipes crossing beneath levees also require special considerations. Such crossings

should be designed by qualified geotechnical engineers. Pipes constructed with open excavation methods

should proceed in accordance with the requirements stated in the above paragraph, Pipes Crossing Through

or Beneath Levees. If directional drilling or other trenchless methods are used, seepage conditions may be

aggravated by the collapse of levee foundation material into the annular void between the bore and pipe.

Penetration through the top stratum of fine-grained materials may concentrate seepage at those locations.

Pipes constructed with trenchless methods should proceed only after a comprehensive evaluation of the

following: comprehensive understanding of the subsurface soil and groundwater conditions to a minimum

depth of 6.1 m (20 ft) below the lowest pipe elevation, locations of the pipe penetration entry and exit,

construction procedure, allowable uplift pressures, on-site quality control and quality assurance monitoring

during construction operation, grouting of the pipe annulus, backfilling of any excavated areas, and repair

and reinstatement of the construction-staging areas. Guidance for construction of pipelines beneath levees

using directional drilling is provided in Appendix A of WES CPAR-GL-98-1 (Staheli, et al. 1998). Guidance

for construction of pipelines using microtunneling methods is provided in WES CPAR-GL-95-2 (Bennett,

et al. 1995).

(b) Pipes installed by directional drilling. The pipe entry or exit location, when located on the

protected (land) side, should be set back sufficiently from the land side levee toe to ensure that the pipe

penetrates some depth of a pervious sand stratum but is no less than 91.5 m (300 ft) from the centerline of

the levee crest. The pipe entry or exit location, when located on the unprotected (river) side, should be

located at least 6.1 m (20 ft) riverward of the levee stability control line. This is the distance between the

river side levee toe and an eroding bank line which will maintain the minimum design criteria for slope

stability. 

If directional drilling is to be used, the depth of the pipe under the levee should be at a level to maintain

an adequate factor of safety against uplift from the pressurized drilling fluid during the drilling operation.

A positive means of maintaining an open vent to the surface should be required whether through bored holes

or downhole means while installing the drill pipe. 

The drilling fluid should consist of a noncolloidal lubricating admixture to ensure suspension and removal

of drilling cuttings. The pilot hole should be advanced at a rate to maintain a continuous return flow. The

annular space should be sufficient to ensure that no blockage occurs with the drilling cuttings. The

prereamer boring diameter should be of sufficient size to ensure that the production pipe can be advanced

without delay and undue stress to the surrounding soils. The prereamer boring operation should be

continuous for the down-slope and up-slope cutting segments. Excessive drilling fluid pressures can

hydraulically fracture the levee foundation and levee embankment and should be avoided. 

Where economically feasible, the pipeline should be bored through rock where the pipeline crosses the

levee centerline. 

The maximum allowable mud pressure acting against the borehole wall should be evaluated using the

Delft equation presented in the Appendix A of WES CPAR-GL-98-1 (Staehli, et al., 1998). During

construction, the actual mud pressure existing in the borehole must be measured by a pressure measuring

device located on the outside of the drill string no more than 5 ft from the drill bit. The drilling operator

should be required to monitor these pressures and adjust the drilling mud pressure so as not to exceed the

maximum pressure determined by Delft equation. 

Where the casing pipe is carrying multiple fibre optic cables and each cable is installed within its own

HDPE inner duct, the detail shown in Figure 8-3a should be used to prevent preferred seepage path (both

external and internal). The casing pipe must end in the encasements.
EM 1110-2-1913

30 Apr 2000

8-9

The directional drilling contract should be required to show proof that all of his pressure sensors and

readout devices have been calibrated by a national standard within the last 6 months. 

A full time inspector, not on directional drilling contractor’s payroll, should be required to observe the

construction.

The drilling fluid should be processed through an active drilling mud conditioning unit to remove the

cuttings from the drill fluid and maintain its viscosity.

c. Pipes crossing over levees. Pipe crossings on the surface of the levee should be designed to counteract uplift of the empty pipe at the design high water stage. This may be accomplished by soil cover, anchors,

headwalls, etc. All pipes on the riverside of the levee should have a minimum of 305 mm (1 ft) of soil cover

for protection from debris during high water. It is desirable for pipe on the landward side to also be covered

with soil. Pipes crossing beneath the levee crown should be provided with sufficient cover to withstand

vehicular traffic as outlined in paragraph 8-4b. Depth of cover should also be at least the depth of local frost

protection. Where mounding of soil over the pipe is required, the slope should be gentle to allow mowing

equipment or other maintenance equipment to operate safely on the slopes. The approach ramps on the levee

crown should not exceed 1V on 10H in order to allow traffic to move safely on the crown. The trenching

details for pipelines cross-up and over-levees are shown in Figure 8-3b and Figure 8-3c.

Section II

Access Roads and Ramps

8-9. Access Roads

a. Access road to levee. Access roads should be provided to levees at reasonably close intervals in

cooperation with state and local authorities. These roads should be all-weather roads that will allow access

for the purpose of inspection, maintenance, and flood-fighting operations.

b. Access road on levee. Access roads, sometimes referred to as patrol roads, should be provided also

on top of the levees for the general purpose of inspection, maintenance, and flood-fighting operations. This

type of road should be surfaced with a suitable gravel or crushed stone base course that will permit vehicle

access during wet weather without causing detrimental effects to the levee or presenting safety hazards to

the levee inspection and maintenance personnel. The width of the road surfacing will depend upon the crown

width of the levee, where roadway additions to the crown are not being used, and upon the function of the

roadway in accommodating either one- or two-way traffic. On levees where county or state highways will

occupy the crown, the type of surfacing and surfacing width should be in accordance with applicable county

or state standards. The decision as to whether the access road is to be opened to public use is to be made

by the local levee agency which owns and maintains the levee.

(1) Turnouts. Turnouts should be used to provide a means for the passing of two motor vehicles on a

one-lane access road on the levee. Turnouts should be provided at intervals of approximately 762 m

(2500 ft), provided there are no ramps within the reach. The exact locations of the turnouts will be

dependent upon various factors such as sight distance, property lines, levee alignment, and desires of local

interests. An example turnout for a levee with a 3.65 m (12-ft) levee crown is shown in Figure 8-4.

(2) Turnarounds. Turnarounds should be provided to allow vehicles to reverse their direction on all

levees where the levee deadends, and no ramp exists in the vicinity of the deadend. An example turnaround

for a levee with a 3.65-m (12-ft) crown is shown in Figure 8-5.
EM 1110-2-1913 

30 Apr 2000 

TO MANHOLE ----------------- CONCRETE ENCASEMENT 

~ OVERLYING GLAY B~ 

COARSE GRAlN AQUIFER/ 

a. Detail of end casing (for pipe lines beneath the levees) 

VERTICAL TRENCH WALLS 

BACKFILL, COMPACTED IN 6-INCH LIFTS 

BEDDING 

b. On riverside, within 50 ft of levee (for pipe lines cross-up and over-levees) 

BACKFILL, COMPACTED IN 6-INCH LIFTS 

c. On landside (for pipelines cross-up and over-levees) 

Figure 8-3. Details of pipeline levee crossing 

8-10 
Figure 8-4. Example of levee turnout 

LAND SIDE 

a 

~...,. 

--+---r-: 

.32m 

24' 

15.24-m 

50' 

RIVERSIDE 

LANDSIDE 

RIVERSIDE 

Figure 8-5. Example of levee turnaround 

8-10. Ramps 

7.32m 

24-' 

EM 1110-2-1913 

30 Apr 2000 

a. Ramps should be provided at sufficient locations to permit vehicular traffic to access onto and from 

the levee. Ramps may be located on both the landside and the riverside of the levee. Ramps on the landside 

ofthe levee are provided to connect access roads leading to a levee with access roads on top of a levee and 

8-11 
EM 1110-2-1913

30 Apr 2000

8-12

at other convenient locations to serve landowners who have property bordering the levee. Ramps are also

provided on some occasions on the riverside of the levee to connect the access road on top of the levee with

existing levee traverses where necessary. The actual locations of the ramps should have the approval of the

local levee agency which owns and maintains the levee. When used on the riverside of the levee, they should

be oriented to minimize turbulence during high water.

b. Ramps are classified as public or private in accordance with their function. Public ramps are

designed to satisfy the requirements of the levee owner: state, county, township, or road district. Private

ramps are usually designed with less stringent requirements and maximum economy in mind. Side-approach

ramps should be used instead of right angle road ramps because of significant savings in embankment. The

width of the ramp will depend upon the intended function. Some widening of the crown of the levee at its

juncture with the ramp may be required to provide adequate turning radius. The grade of the ramp should

be no steeper than 10 percent. Side slopes on the ramp should not be less than 1V on 3H to allow grasscutting equipment to operate. The ramp should be surfaced with a suitable gravel or crushed stone. Consideration should be given to extending the gravel or crushed stone surfacing to the levee embankment to

minimize erosion in the gutter. In general, private ramps should not be constructed unless they are essential

and there is assurance that the ramps will be used. Unused ramps lead to maintenance neglect.

c. Both public and private ramps should be constructed only by adding material to the levee crown and

slopes. The levee section should never be reduced to accommodate a ramp.

Section III

Levee Enlargements

8-11. General

The term levee enlargement pertains to that addition to an existing levee which raises the grade. A higher

levee grade may be required for several reasons after a levee has been constructed. Additional statistical

information gathered from recent floodings or recent hurricanes may establish a higher project flood

elevation on a river system or a higher elevation for protection from incoming tidal waves produced by

hurricane forces in low-lying coastal areas. The most economical and practical plan that will provide

additional protection is normally a levee enlargement. Levee enlargements are constructed either by adding

additional earth fill or by constructing a flood-wall, “I”-type or “inverted T”-type, on the crown.

8-12. Earth-Levee Enlargement

a. The earth-levee enlargement is normally preferred when possible, since it is usually more economical.

This type of enlargement is used on both agricultural and urban levees where borrow sites exist nearby

and sufficient right-of-way is available to accommodate a wider levee section.

b. An earth-levee enlargement is accomplished by one of three different methods: riverside, straddle,

or landside enlargement. A riverside enlargement is accomplished by increasing the levee section generally

at the crown and on the riverside of the levee as shown in Figure 8-6a. A straddle enlargement is

accomplished by increasing the levee section on the riverside, at the crown, and on the landside of the leveeas shown in Figure 8-6b. A landside enlargement is accomplished by increasing the levee section, generally

at the crown and on the landside of the levee as shown in Figure 8-6c. There are advantages and

disadvantages to each enlargement method that will have to be looked at for each project. The riverside

enlargement would be more costly if the riverside slope has riprap protection and it could also be an

encroachment for narrow floodways that would impact top of levee designs. Landside enlargements would

require additional right-of-way and larger fill quantities for levees with flatter landside slopes. The strattle
EM 1110-2-1913 

30 Apr 2000 

enlargement would require the whole levee system to be stripped with work being done on both sides of the 

levee. 

RIVERSIDE: 

a. Riverside levee enlargement 

RIVERSIDE 

b. Straddle levee enlargement 

RIVERSIOE 

c. Landside levee enlargement 

Figure 8-6. Enlargements 

It 

I 

~ 

I 

l.AWDSIOE 

LANDSIDE 

OfUGINAI. &ROIJNO 

SURI'ACE 

c. The modified levee section should be checked for through seepage and underseepage as discussed 

in Chapter 5 and for foundation and embankment stability as discussed in Chapter 6. Sufficient soil borings 

should be taken to determine the in situ soil properties of the existing levee embankment for design purposes. 

d. An earth-levee enlargement should be made integral with the existing levee. Every effort should be 

made such that the enlargement has at least the same degree of compaction as the existing levee on which 

it is constructed. Preparation of the interface along the existing levee surface and upon the foundation should 

be made to ensure good bond between the enlargement and the surfaces on which it rests. The foundation 

surface should be cleared, grubbed, and stripped as described in Chapter 6. The existing levee surface upon 

which the levee enlargement is placed should also be stripped of all low-growing vegetation and organic 

8-13 
EM 1110-2-1913

30 Apr 2000

 Structural design of crest walls is given in ETL 1110-2-341. 1

8-14

topsoil. The topsoil that is removed should be stockpiled for reuse as topsoil for the enlargement. Prior to

constructing the enlargement, the stripped surfaces of the foundation and existing levee should be scarified

before the first lifts of the enlargements are placed.

8-13. Floodwall-Levee Enlargement

a. A floodwall-levee enlargement is used, when additional right-of way is not available or is too expensive or if the foundation conditions will not permit an increase in the levee section. Economic justification

of floodwall-levee enlargement cannot usually be attained except in urban areas. Two common types of

floodwalls that are used to raise levee grades are the I wall and the inverted T wall.1

b. The I floodwall is a vertical wall partially embedded in the levee crown. The stability of such walls

depends upon the development of passive resistance from the soil. For stability reasons, I floodwalls rarely

exceed 2.13 m (7 ft) above the ground surface. One common method of constructing an I floodwall is by

combining sheet pile with a concrete cap as shown in Figure 8-7. The lower part of the wall consists of a

row of steel sheet pile that is driven into the levee embankment, and the upper part is a reinforced concrete

section capping the steel piling.

c. An inverted T floodwall is a reinforced concrete wall whose members act as wide cantilever beams

in resisting hydrostatic pressures acting against the wall. A typical wall of this type is shown in Figure 8-8.

The inverted T floodwall is used to make floodwall levee enlargements when walls higher than 2.13 m (7 ft)

are required.

d. The floodwall should possess adequate stability to resist all forces which may act upon it. An I floodwall is considered stable if sufficient passive earth resistance can be developed for a given penetration of the

wall into the levee to yield an ample factor of safety against overturning. The depth of penetration of the

I wall should be such that adequate seepage control is provided. Normally the penetration depth of the I wall

required for stability is sufficient to satisfy the seepage requirements. For the inverted T floodwall, the wall

should have overall dimensions to satisfy the stability criteria and seepage control as presented in

EM 1110-2-2502. 

e. The existing levee section should be checked for through seepage and underseepage as discussed in

Chapter 5 and for embankment and foundation stability as discussed in Chapter 6 under the additional hydrostatic forces expected. If unsafe seepage forces or inadequate embankment stability result from the higher

heads, seepage control methods as described in Chapter 5 and methods of improving embankment stability

as described in Chapter 6 may be used. However, some of these methods of controlling seepage and

improving embankment stability may require additional right-of-way for construction which could eliminate

the economic advantages of the floodwall in comparison with an earth levee enlargement. As in earth levee

enlargements, a sufficient number of soil borings should be taken to determine the in situ soil properties of

the existing levee embankment for design purposes.
-<' FLOODWALL, SEE - -... DETAIL "A" 

~·~~ 

Figure 8-7. 1-type floodwall-levee enlargement 

/FLODDWALL, SEE 

\ DETAIL"A" 

Figure 8-8. Inverted T-type floodwall-levee enlargement 

-

DETAIL "A" 

DETAIL "A" 

EM 1110-2-1913 

30 Apr 2000 

8-15 
EM 1110-2-1913

30 Apr 2000

8-16

Section IV

Junction with Concrete Closure Structures

8-14. General

In some areas, a flood protection system may be composed of levees, floodwalls, and drainage control structures (gated structures, pumping plants, etc.). In such a system, a closure must be made between the levee

and the concrete structure to complete the flood protection. One closure situation occurs when the levee ties

into a concrete floodwall or a cutoff wall. In this closure situation the wall itself is usually embedded in the

levee embankment. In EM 1110-2-2502 a method of making a junction between a concrete floodwall and

levee is discussed and illustrated. Another closure situation occurs when the levee ties into a drainage

control structure by abutting directly against the structure as shown in Figure 8-9. In this situation the

abutting end walls of the concrete structure should be battered 10V on 1H to ensure a firm contact with the

fill.

8-15. Design Considerations

When joining a levee embankment with a concrete structure, items that should be considered in the design

of the junction are differential settlement, compaction, and embankment slope protection.

a. Differential settlement. Differential settlement caused by unequal consolidation of the foundation

soil at the junction between a relatively heavy levee embankment and a relatively light concrete closure

structure can be serious if foundation conditions are poor and the juncture is improperly designed.

Preloading has been used successfully to minimize differential settlements at these locations. In EM 1110-2-

2502 a transitioning procedure for a junction between a levee embankment and a floodwall is presented that

minimizes the effect of differential settlement.

b. Compaction. Thorough compaction of the levee embankment at the junction of the concrete structure

and levee is essential. Good compaction decreases the permeability of the embankment material and ensures

a firm contact with the structure. Heavy compaction equipment such as pneumatic or sheepsfoot rollers

should be used where possible. In confined areas such as those immediately adjacent to concrete walls, compaction should be by hand tampers in thin loose lifts as described in EM 1110-2-1911.

c. Seepage. Seepage needs to be analyzed to determine the embedment length of the structure-levee

junction. Zoning of the embankment materials needs to be maintained through the junction unless analysis

indicates different zoning is required.

d. Slope protection. Slope protection should be considered for the levee embankment at all junctions

of levees with concrete closure structures. Turbulence may result at the junction due to changes in the

geometry between the levee and the structure. This turbulence will cause scouring of the levee embankment

if slope protection is not provided. Slope protection for areas where scouring is anticipated is discussed in

paragraph 7-6.
-

.... -

f" 

~ 

/ tl~ ~ 7 ........................... -1 ~ ~~~ ~ 

~~~ ;J MR GATES 

\ \ 

'--' 

€ LEVEE >.t:::: ,___)>< 

fEJ wL1HJJ Br 

~ y? 

BATTERED 10v ON 1h 

-~ ............. 

~~~ 7 

......... 

PLAN 

SCALES 

30m 0 

60FT 0 - M M I 

SECTION A-A 

SCALES 

10m 0 10m 

~~ ~~ 

~f 

30m 

60FT I 

40FT 0 40FT --I I 

Figure 8-9. Junction of levee and drainage structure 

I 

v 

I 

....... 

EM 1110-2-1913 

30 Apr 2000 

......... ~ 

f; LEVEE~ 

_..,.lL 

/ 

8-17 
EM 1110-2-1913

30 Apr 2000

8-18

Section V

Other Special Features

8-16. Construction of Ditches Landside of Levee

Sometimes requests are made to locate irrigation and/or drainage ditches in close proximity to the landside

levee toe. Such ditches may lead to serious seepage and/or slope stability problems. The location and depth

of proposed ditches should be established by seepage and stability analyses. This requires information on

foundation soil conditions, river stages and geometry of the proposed ditch. 

Drainage ditches should be located such that the exit gradient in the bottom of the ditch does not exceed 0.5

at the landside levee toe and does not exceed 0.8 at a distance 45.72 m (150 ft) landward of the landside levee

toe and beyond. Between the landside levee toe and 45.72 m (150 ft) landward of the landside levee

toe, the maximum allowable exit gradient in the bottom of the ditch should increase linearly from 0.5 to 0.8.

The exit gradient should be computed assuming the water level in the ditch is at the bottom of the ditch. 

8-17. Levee Vegetation Management

To protect or enhance esthetic values and natural resources, vegetation on a levee and its surrounding areas

(trees, bushes and grasses) is an important part of design considerations. Vegetation can be incorporated in

the project as long as it will not diminish the integrity and the functionality of the embankment system or

impede ongoing operations, maintenance and floodfighting capability. A multidiscipline team including

structural and geotechnical engineers, biologists and planners should evaluate the vegetation design or proposal. Coordination with local governments, states and Native American tribes may be needed during the

design process. EM 1110-2-301 and ER 500-1-1 are two documents covering the vegetation policy

applicable to both federal levees and non-federal levees under the PL-84-99 program.
EM 1110-2-1913

30 Apr 2000

A-1

Appendix A

References

A-1. Required Publications

TM 5-818-5

Dewatering and Groundwater Control for Deep Excavations

ER 500-1-1

Natural Disaster Procedures

ER 1110-2-1806

Earthquake Design and Evaluation for Civil Works Projects

EM 1110-2-301

Guidelines for Landscape Planting at Floodwalls, Levees, and Embankment Dams

EM 1110-2-1601

Hydraulic Design of Flood Control Channels

EM 1110-2-1614

Design of Coastal Revetments, Seawall, and Bulkheads

EM 1110-1-1802

Geophysical Explorations for Engineering and Environmental Investigations

EM 1110-2-1901

Seepage Analysis and Control for Dams

EM 1110-1-1904

Settlement Analysis

EM 1110-1-1906

Soils Sampling

EM 1110-2-1902

Stability of Earth and Rock-Fill Dams
EM 1110-2-1913

30 Apr 2000

A-2

EM 1110-2-1906

Laboratory Soils Testing

EM 1110-2-1908

Instrumentation of Embankment Dams and Levees

EM 1110-2-1911

Construction Control for Earth and Rock-Fill Dams

EM 1110-2-1914

Design, Construction, and Maintenance of Relief Wells

EM 1110-2-2300

Earth and Rock-Fill Dams General Design and Construction Considerations

EM 1110-2-2502

Retaining and Flood Walls

EM 1110-2-2902

Conduits, Culverts, and Pipes

Federal Specification WW-P-405B(1)

Corrugated Steel Pipe

U.S. Army Engineer Waterways Experiment Station, CE, “Soil Mechanics Design, Stability of Slopes and

Foundations,” Technical Memorandum No. 3-777, Feb 1952, P.O. Box 631, Vicksburg, Miss. 39180

U.S. Army Engineer Waterways Experiment Station, CE, “Underseepage and Its Control, Lower Mississippi

River Levees,” Technical Memorandum No. 3-424, Vol I, Oct 1956, P.O. Box 631, Vicksburg, Miss. 39180

U.S. Army Engineer Division, Lower Mississippi Valley, CE, “Design Procedures for Design of Landside

Seepage Berms for Mississippi River Levees,” P.O. Box 80, Vicksburg, Miss. 39180

U.S. Army Engineer District, Rock Island, CE, “Engineering and Design Studies for Underseepage Control

(Slurry Trench Cutoff) for Saylorville Dam, Des Moines River, Iowa,” Design Memorandum, Nov 1965,

Clock Tower Bldg., Rock Island, Ill. 61201

U.S. Army Engineer District, Savannah, CE, “West Point Project, Chatahoochee River, Alabama and

Georgia, Construction of Slurry Trench Cutoff,” May 1968, P.O. Box 889, Savannah, Ga., 31402
EM 1110-2-1913

30 Apr 2000

A-3

Tuck and Torrey 1993

Tuck, G. F. and Torrey, V. H., III, Upper Mississippi River Basin Flood of 1993 Flood-Fight Reconnaissance

and Survey of Expedient Methods Employed, December 1993, U.S. Army Engineer Waterways Experiment

Station, 3909 Halls Ferry Road, Vicksburg, MS 39180-6199 

NAVFAC, Soil Mechanics Foundations and Earth Structures, Design Manual 7, Mar 1971. U.S. Naval

Publications and Forms Center, 5801 Tabor Avenue, Philadelphia, Pennsylvania 19120

A-2. Related Publications

Bennett, Guice, Khan, and Staheli 1995

Bennett, R. D., Guice, L. K., Khan, S., and Staheli, K., 1995, “Guidelines for Trenchless Technology:

Cured-in Place Pipe (CIPP), Fold and Formed Pipe (FFP) Mini-Horizontal Directional Drilling (mini-HDD)

Microtunneling,” Construction Productivity Advancement Research (CPAR) Program, GL-95-2, U.S. Army

Engineer Waterways Experiment Station, Vicksburg, MS.

Bhowmik 1994

Bhowmik, N. G., et al., The 1993 Flood on the Mississippi River in Illinois, January 1994, Illinois State

Water Survey Miscellaneous Publication 151, 2204 Griffith Drive, Champaign, IL 61820

Biedenharn and Tracy 1987

Biedenharn, D. G., and Tracy, F. T., 1987, “Finite Element Method Package for Solving Steady-State

Seepage Problems,” Technical Report ITL-87-6, U.S. Army Engineer Waterways Experiment Station,

Vicksburg, MS

Bjerrum 1972

Bjerrum, L., ”Embankments on Soft Ground,” Proceedings, Specialty Conference on Performance of Earth

and Earth-Supported Structures, Vol II, 11-14 June 1972. ASCE, 345 East 47th St., New York, New York

10017

Blasters’’ 1966

Blasters’’ Handbook, 15th ed., E. 1. Dupont de Nemours and Co., Inc., 1966, Wilmington, Delaware 19898

Brizendine, Taylor, and Gabr 1995

Brizendine, A. L., Taylor, H. M., Jr., and Gabr, M. A., 1995. “LEVSEEP: Analysis Software for Levee

Underseepage and Rehabilitation,” Technical Report GL-95-10, U.S. Army Engineer Waterways Experiment

Station, Vicksburg, MS 

Butler and Llopis 

Butler, Dwain K., and Llopis, Jose L., “Assessment of Anomalous Seepage Conditions,” Geotechnical and

Environmental Geophysics, Vol. II, pp. 153-173, Environmental and Groundwater, Society of Exploration

Geophysicists, P.O. Box 702740, Tulsa, OK 74170-2740.

Dobrin 1960

Dobrin, M. B., Geophysical Prospecting, 1960, McGraw Hill Publishing Co., 1221 Avenue of The Americas,

New York, New York, 10020

Engineering Computer Graphics Laboratory 1996

Engineering Computer Graphics Laboratory, 1996, “FastSEEP Automated Seepage Analysis Reference

Manual,” Brigham Young University, Provo, UT
EM 1110-2-1913

30 Apr 2000

A-4

Gabr, Brizendine, and Taylor 1995

Gabr, M. A., Brizendine, A. L., and Taylor, H. M., Jr., 1995, “Comparison Between Finite Element Study

and Simplified Analysis of Levee Underseepage,” Technical Report GL-95-11, U.S. Army Engineer

Waterways Experiment Station, Vicksburg, MS

Gabr, Taylor, Brizendine, and Wolff 1995

Gabr, M. A., Taylor, H. M., Jr., Brizendine, A. L., and Wolff, T. F., 1995, “LEVEEMSU: Analysis Software

for Levee Underseepage and Rehabilitation,” Technical Report GL-95-9, U.S. Army Engineer Waterways

Experiment Station, Vicksburg, MS

General Accounting Office 1995

General Accounting Office, Midwest Flood: Information on the Performance, Effects, and Control of Levees,

August 1995, GAO/RCED-95-125, Resources, Community, and Economic Development Division, P.O. Box

6015, Gaithersburg, MD 20884-6015

Interagency Floodplain Management Review

Committee 1994

Interagency Floodplain Management Review Committee, Sharing the Challenge: Floodplain Management

Into the 21st Century, June 1994, Report to the Administration Floodplain Management Task Force,

Government Printing Office, Superintendent of Documents, P.O. Box 371954, Pittsburgh, PA 15250-7954

Johnson 1970

Johnson, S. J., “Foundation Precompression with Vertical Sand Drains,” Journal, Soil Mechanics and

Foundations Division, American Society of Civil Engineers, Jan 1970, ASCE, 345 East 47th St., New York,

New York 10017

Kapp, York, Aronowitz, and Sitomer 1966

Kapp, M. S., York, D. L., Aronowitz, A., and Sitomer, H., “Construction on Marshland Deposits: Treatment

and Results,” Utilization of Sites of Soft Foundations Highway Research Record No. 133, pp 1-22, 1966,

Transportation Research Board, 2101 Constitution Avenue, N. W., Washington, D. C. 20418

Knowles 1992

Knowles, V. R., 1992, “Applications of the Finite Element Seepage Analysis Corps Program CSEEP

(X8202),” Technical Report ITL-92-6, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS

Ladd and Foott 1974

Ladd, Charles C., and Foott, Roger, 1974, “New Design Procedure for Stability of Soft Clays, Vol. 100

No. GT7, Journal of the Geotechnical Engineering Division.

Sherard 1979

Sherard, J. L., 1979, “Sinkholes in Dams of Coarse, Broadly Graded Soils,” Transaction of the 13th

International Congress on Large Dams, New Delhi, India, Vol. 11, pp 25-35.

Staheli, Bennett, O’Donnell, and Hurley 1998

Staheli, K., Bennett, D., O’Donnell, H. W., and Hurley, T. J., 1998, “Installation of Pipelines Beneath Levees

Using Horizontal Directional Drilling,” Construction Productivity Advancement Research (CPAR) Program,

GL-98-1,U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS. 
EM 1110-2-1913

30 Apr 2000

A-5

Telford, Geldart, Sheriff, and Keys 1990

Telford, W. M., Geldart, L. P., Sheriff, R. E., and Keys, D. A., 1990, “Applied Geophysics,” Cambridge

University Press, New York.

Tobin 1995

Tobin, G. A., “The Levee Love Affair: A Stormy Relationship,” Water Resources Bulletin, Vol 31, No. 3,

1995, American Water Resources Association, 950 Herndon Parkway, Herndon, VA 22070-5531

Tracy 1994

Tracy, F. T., 1994, “Seepage Package,” CSEEP Micro Version, X8202, U.S. Army Engineer Waterways

Experiment Station, Vicksburg, MS

Turnbull and Mansur 1959

Turnbull, W. J. and Mansur, C. I., “Design of Underseepage Control Measures for Dams and Levees,”

Journal, Soil Mechanics and Foundations Division, American Society of Civil Engineers, Oct. 1959, ASCE,

345 East 47th St., New York, New York 10017

Turnbull and Mansur 1959

Turnbull, W. J. and Mansur, C. I., “Construction and Maintenance of Underseepage Control Measures,”

Journal, Soil Mechanics and Foundations Division, American Society of Civil Engineers, Dec. 1959, ASCE,

345 East 47th St., New York, New York 10017

Wolff 1989

Wolff, T. F., 1989, “LEVEEMSU: A Software Package Designed for Levee Underseepage Analysis,”

Technical Report GL-89-13, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS

ASTM D 1056

American Society for Testing and Materials, 1916 Race Street, Philadelphia, Pennsylvania 19103

ASTM D 2573

American Society for Testing and Materials, 1916 Race Street, Philadelphia, Pennsylvania 19103.

AASHTO M 243-73

American Association of State Highway and Transportation Officials, 341 National Press Bldg., Washington,

DC. 20004
EM 1110-2-1913

30 Apr 2000

B-1

Appendix B

Mathematical Analysis of Underseepage

and Substratum Pressure

B-1. General

The design of seepage control measures for levees often requires an underseepage analysis without the use

of piezometric data and seepage measurements. Contained within this appendix are equations by which an

estimate of seepage flow and substratum pressures can be made, provided soil conditions at the site are

reasonably well defined. The equations contained herein were developed during a study (reported in

U.S. Army Engineer Waterways Experiment Station TM 3-424 (Appendix A) of piezometric data and

seepage measurements along the Lower Mississippi River and confirmed by model studies. It should be

emphasized that the accuracy obtained from the use of equations is dependent upon the applicability of the

equation to the condition being analyzed, the uniformity of soil conditions, and evaluation of the various

factors involved. As is normally the case, sound engineering judgment must be exercised in determining soil

profiles and soil input parameters for these analyses.

B-2. Assumptions

It is necessary to make certain simplifying assumptions before making any theoretical seepage analysis. The

following is a list of such assumptions and criteria necessary to the analysis set forth in this appendix.

a. Seepage may enter the pervious substratum at any point in the foreshore (usually at riverside borrow

pits) and/or through the riverside top stratum.

b. Flow through the top stratum is vertical.

c. Flow through the pervious substratum is horizontal.

d. The levee (including impervious or thick berms) and the portion of the top stratum beneath it is

impervious.

e. All seepage is laminar.

In addition to the above, it is also required that the foundation be generalized into a pervious sand or gravel

stratum with a uniform thickness and permeability and a semipervious or impervious top stratum with a

uniform thickness and permeability (although the thickness and permeability of the riverside and landside

top stratum may be different).

B-3. Factors Involved in Seepage Analyses

The volume of seepage (Q ) that will pass beneath a levee and the artesian pressure that can develop under s

and landward of a levee during a sustained high water are related to the basic factors given and defined in

Table B-1 and shown graphically in Figure B-1. Other values used in the analyses are defined as they are

discussed in subsequent paragraphs.
EM 1110-2-1913

30 Apr 2000

B-2

B-4. Determination of Factors Involved in Seepage Analyses

Table B-2 contains a brief summary of methods normally used to determine the factors necessary to perform

a seepage analysis. The determination of these factors is discussed in more detail in the following

paragraphs. Many of the methods given, such as exploration and testing, have previously been mentioned

in the text; however, they will be discussed herein in more detail as they apply to each specific factor. The

use of piezometric data, although rarely available on new projects, is mentioned primarily because it is not

infrequent for seepage analyses to be performed as a part of remedial measures to existing levees in which

case piezometric data often are available.

Table B-1

Factors Involved in Seepage Analyses

Factor Definition

H Net head on levee

M Slope of hydraulic grade line (at middepth of pervious stratum) beneath levee

i

c Critical gradient for landside top stratum

L1 Distance from river to riverside levee toe

L2 Base width of levee and berm

L3 Length of foundation and top stratum beyond landside levee toe

L Distance from effective seepage entry to effective seepage exit

s Distance from effective seepage entry to landside toe of levee or berm

X1 Distance from effective seepage entry to riverside levee toe

X Distance from landside levee toe to effective seepage exit 3

d Thickness of pervious substratum

z Thickness of top stratum

zb Transformed thickness of top stratum

zbl Transformed thickness of landside top stratum

zbr Transformed thickness of riverside top stratum

z Thickness of individual layers comprising top stratum (n = layer number) n

zt Transformed thickness of landside top stratum for uplift computation

kb Vertical permeability of top stratum

kbl Vertical permeability of landside top stratum

kbr Vertical permeability of riverside top stratum

kf Horizontal permeability of pervious substratum

k Vertical permeability of individual layers comprising top stratum (n = layer number) n

Qs Total amount of seepage passing beneath the levee

ho Head beneath top stratum at landside levee toe

hx Head beneath top stratum at distance x from landside levee toe
EM 1110-2-1913

30 Apr 2000

B-3

Table B-2

Methods for Determination of Design Parameters

Factor Method of Determination

H From design flood stage or net levee grade

kbl, kbr From laboratory tests, estimations, and transformations

kf Field pump tests, correlations

z Foundation exploration, knowledge of depth and locations of borrow pits, ditches, etc. b

zbl , zbr From transformations

d Foundation exploration

i

c From equation B-9

M From piezometers or from determining effective entrance and exit points of seepage

L1 From maps

L2 From preliminary or existing levee section

L3 From foundation exploration and knowledge of location of levee

s From piezometric data or estimated from equations

x1 From knowing M or from equation B-7 or B-8

x3 From knowing M or from equation B-3, B-3A, B-4, B-5, or B-6

Qs From equation B-11 or B-12

ho From piezometric data or estimated from equations

hx From piezometric data or estimated from equations

a. Net head, H. The net head on a levee is the height of water on the riverside above the tailwater or

natural ground surface on the landside of the levee. H is usually based on the design or project flood stage

but is sometimes based on the net levee grade.

b. Thickness, z and vertical permeability, k , of top stratum. b

(1) Exploration. The thickness of the top stratum, both riverward and landward of the levee, is extremely

important in a seepage analysis. Exploration to determine this thickness usually consists of auger borings

with samples taken at 0.91- to 1.52-m (3- to 5-ft) intervals and at every change of material. Boring spacing

will depend on the potential severity of the underseepage problem but should be laid out so as to sample the

basic geologic features with intermediate borings for check purposes. Landside borings should be sufficient

to delineate any significant geological features as far as 152.4 m (500 ft) away from the levee toe. The effect

of ditches and borrow areas must be considered.

(2) Transformation. The top stratum in most areas is seldom composed of one uniform material but

rather usually consists of several layers of different soils. If the in situ vertical permeability of each soil (k )n

is known, it is possible to transform an overall effective thickness and permeability. However, if good

judgment is exercised in selection of these values, a reasonably accurate seepage analysis can be made by

using a simplified procedure. Basically this procedure consists of assuming a uniform vertical permeability
EM 1110-2-1913 

30 Apr 2000 

for the generalized top stratum equal to the permeability of the most impervious strata and then using the 

transformation factor given in equation B-1 to determine a corresponding thickness for the entire top stratum. 

A POINT OF EFFECTIVE SEEPAGE ENTRY 

B - POINT OF EFFECTIVE SEEPAGE EXIT 

~ 

~r---------------~s~------------------~4---~X 

L 

Figure B-1. Illustration of symbols used in Appendix B 

kb F =-

I k 

II 

where F1 = transformation factor. 

(B-1) 

If the in situ thickness of each soil layer (z0) is known, the value of corresponding transformed thickness (z1

) 

can be expressed as 

kb 

z, = Z11 F1 = Z11 k 

II 

The total in situ thickness (z) and total transformed can be expressed as 

II 

z = L zll 

II 

zb = L z, 

1 

Some examples using this procedure are given in Table B-3 and in Figure B-2. 

B-4 

(B-la) 

(B-lb) 

(B-lc) 
Ft

'

Kb

Kn

k

f

'

Qs

M·d

EM 1110-2-1913

30 Apr 2000

B-5

Table B-3

Examples of Transformation Procedure

 Actual Actual Transformed Thickness,

 Thickness Permeability z , m (ft) t

Strata z , m (ft) cm/sec (k = 1x 10 cm/sec) n b

-4

Clay 1.52 (5) 1 x 10 1 1.52 (5.0) -4

Sandy silt 2.44 (8) 2 x 10 1/2 1.22 (4.0) -4

Silty sand 1.52 (5) 10 x 10 1/10 0.15 (0.5) -4

z = 5.48 (18) z = 2.90 (9.5) b

A generalized top stratum having a uniform permeability of 1 x10 cm/sec and 2.9 m (9.5 ft) thick would -4

then be used in the seepage analysis for computation of the length to the effective seepage exit. However,

the thickness zb may or may not be the effective thickness of the landside top stratum zt that should be used

in determining the allowable pressure beneath the top stratum. The transformed thickness of the top stratum

for estimating allowable uplift z equals the in situ thicknesses of all strata above the base of the least

t

pervious stratum plus the transformed thicknesses of the underlying more pervious top strata. This means

that z will equal z only when the least pervious stratum is at the ground surface. Several examples of this b t

transformation are given in Figure B-2. In making the final determination of the effective thicknesses and

permeabilities of the top stratum, the characteristics of the top stratum at least 61 to 91.4 m (200 to 300 ft)

landward of the levee must be considered. In addition, certain averaging assumptions are almost always

required where soil conditions are reasonably similar. Thin or critical areas should be given considerable

weight in arriving at such averages.

c. Thickness d and permeability kf of pervious substratum. The thickness of the pervious substratum

is defined as the thickness of the principal seepage-carrying stratum below the top stratum and above rock

or other impervious base stratum. It is usually determined by means of deep borings although a combination

of shallow borings and seismic or electrical resistivity surveys may also be employed. The thickness of any

individual pervious strata within the principal seepage carrying stratum must be obtained by deep borings.

The average horizontal permeability kf of the pervious substratum can be determined by means of a field

pump test on a fully penetrating well or by the use of correlations as shown in Figure 3-5(b) in the main text.

For areas where such correlations exist their use will usually result in a more accurate permeability

determination than that from laboratory permeability tests. In addition to the methods above, if the total

amount of seepage per unit length passing beneath the levee (Qs), the hydraulic grade line beneath the levee

(M) and the thickness of pervious stratum (d) are known, kf can be estimated from

(B-2)

d. Distance from riverside levee toe to river, L1 . This distance can usually be estimated from

topographic and stratigraphic maps.

e. Base width of levee and berm, L . L can be determined from anticipated dimensions of new levees 2 2

or by measurement in the case of existing levees.

f. Length of top stratum landward of levee toe, L3 . This distance can usually be determined from

borings, topographic maps, and/or field reconnaissance. In determining this distance careful consideration
CASE ACTUAL STRATA 

TRANSFORMED STRATA FOR 

COMPUTATION OF SEEPAGE 1c;,(CM) 

AND SUBSTRATUM PRESSURE SEC 

t 

1/2 

c....._ ~ g~ :z,1=1.52m (5')CLAY lx1o-• 

C\ie -4------ ~ :Z,:r=__1_22m (4') SANDY SILT 

-~---

4 :z,3 J.15m ~ SILTY SAND 

1/10 

:z,, =.15m (.5') ,SILTY SAND 

• t / 

, 1/10 

1/2 

1 

GS 

1/2 

1/10 

Figure B-2. Transformation of top strata 

t 

TRANSFORMED STRATA FOR 

COMPUTATION OF MAXIMUM 

ALLOWABLE UPLIFT 

c....._ ~ g~ ~ =1.52m(5') CLAY 

C\l'-'" ·m - - - - - - I -

~ ~ =1,22m(4') SANDY SILT ----......---- 4 Z:! =.15m(.5') ~ ~ SILTY SAND 

f z,. =1~52m(5') SILTY SAND 

gc- -;------

-.;:j<CXl ( ') ~.::::;_ ~ =2t4m B SANDY SILT 

r -I------

Z:! =1 j52m(5') CLAY 

t t S::;;' ~ =2.44m(B') SANDY SILT 

..--<C'J ....... . ! ~-=- ------- r ~ =1.52m(5') CLAY 

Z:! -·--~-- J.15m(.5') SILTY SAND 

wm 03: 

)>_. 

"0 ... .. ... No 0• oN o.!.. 

CD 

... 

w 
x3

'

1

c

'

k

f

z

bl d

k

bl

c '

k

bl

k

f

z

bl d

x

3

'

1

c tanh (cL3)

x3'

tanh (cL3)

c

x

3

' (0.1 d ) x

3

N

EM 1110-2-1913

30 Apr 2000

B-7

must be given to any geological feature that may affect the seepage analysis. Of special importance are

deposits of impervious materials such as clay plugs which can serve as seepage barriers and if located near

the landside toe could force the emergence of seepage at their near edge, thus having a pronounced effect on

the seepage analysis.

g. Distance from landside levee toe to effective seepage exit, x . The effective seepage exit (point B, 3

Figure B-1) is defined as that point where a hypothetical open drainage face would result in the same

hydrostatic pressure at the landside levee toe and would cause the same amount of seepage to pass beneath

the levee as would occur for actual conditions. This point is also defined as the point where the hydraulic

grade line beneath the levee projected landward with a slope M intersects the groundwater or tailwater. If

the length of foundation and top stratum beyond the landside levee toe L3 is known, x3 can be estimated from

the following equations:

(1) For L3 = 4

(B-3)

where

(B-3A)

(2) For L3 = finite distance to a seepage block

(B-4)

(3) For L = finite distance to an open seepage exit 3

(B-5)

(4) The relationship between zbl and x3 where L3 is infinite in landward extent has been computed from

equation B-3 and plotted in Figure B-3 for various values of kf/kbl and assuming d = 100 m or 100 ft. The

x value corresponding to values of d other than 100 m or 100 ft can be computed from equation B-6 below: 3

(B-6)

where

x N is the value of x for d = 100 m or 100 ft 3 3
EM 1110-2-1913 

30 Apr 2000 

to.ooo 

.:::: 

0 

~ 

0 

E 

0 

0 

-I 

" <:<: 

0 

u. 

£ 

.to: 

<:<: 

0 

E 

~ 

I 

1-

(.J 

z 

w 

--' 

1-

x 

w 

w 

> 

6 

w 

u. 

u. 

w 

sooo 

AOOO 

3000 

2000 

1000 

500 

.coo 

roo 

I 

FOR La • oo 

X3= 

I 

VALUES OF x1 SHOWN ARE FOR d .100 

FOR VALUES OF •'d" OrnER rnAN d=l00 

x, • 0 • 1-fd xu• • 1oo1. 

3 .( 5 10 20 

EFFECTIVE THICKNESS OF TOP STRATUM IN m OR ft (zb,) 

Figure B-3. Effective seepage exit length for L3 = oo and d =100m or ft 

30 

k 

Example: Using Figure B-3, find x3 for soil with ....L = 200, ~~ = 3.05 m (10ft), and d = 45.7 m (150ft) 

kbl 

k 

Solution: 1 -From Figure B-3 the value x3 for ....L = 200, zb1 = 3.05 m (I 0 ft). Then for zbL = 3.05 m and d = 

kbl 

100m, x/ =246m; or zbL = 10ft and d = 100ft, x/ =450ft 

B-8 
x3

' 0.1 45.7 x3N

x3' (0.1) (6.76) (246) ' 167 m

x

3

' 0.1 d (450) ' 0.1 150 (450) ' 551 ft

x1'

tanh cL1

c

x1'

1

c tanh cL1

i

c

'

ãr

ãw

'

GS& 1

1 % e

EM 1110-2-1913

30 Apr 2000

B-9

2 - Apply Equation B-6 to determine x for d = 45.7 m (150 ft) 3

or

(5) If L3 is a finite distance either to a seepage block or an open seepage exit, the effective exit length x3

can be computed by using equation B-4 or B-5 or by multiplying x3 (for L3 = 4) by a factor obtained from

Figure B-4.

h. Distance from effective source seepage entry to riverside levee toe, x . The effective source of 1

seepage entry into the pervious substratum (point A in Figure B-1) is defined as that line riverward of the

levee where a hypothetical open seepage entry face fully penetrating the pervious substratum and with an

impervious top stratum between this line and the levee would produce the same flow and hydrostatic pressure

beneath and landward of the levee as will occur for the actual conditions riverward of the levee. It is also

defined as that line or point where the hydraulic grade line beneath the levee projected riverward with a slope

M intersects the river stage.

(1) If the distance to the river from the riverside levee toe L is known and no riverside borrow pits or l

seepage blocks exist, x can be estimated from the following equation: 1

(B-7)

(2) If a seepage block (usually a wide, thick deposit of clay) exists between the riverside levee toe and the

river so as to prevent any seepage entrance into the pervious foundation beyond that point, x1 can be estimated

from the following equation:

(B-8)

where L equals distance from riverside levee toe to seepage block and c is from equation B-3A. 1

i. Critical gradient for landside top stratum, ic. The critical gradient is defined as the gradient required

to cause boils or heaving (flotation) of the landside top stratum and is taken as the ratio of the submerged or

buoyant unit weight of soil ãr comprising the top stratum and the unit weight of water ãw or

(B-9)
EM 1110-2-1913 

30 Apr 2000 

~ 

... 

w 8 !: • .. z ... ... "' 

"' ~ 0 

... ~ 

>< .... 

" .. ... ... 

w 

1-

z 

... 

a: 

0 

... 

... >< 

.. 

z 

.... 

:::0 

L 

~ u 

"' 0 

... 

a: 

0 

.... 

u 

< 

... 

4.0 

s.o 

2.0 

FOR BLOCKED EXITS WHERE rl FOR L 1 • 00 > 4 • 

I 

r 1 FOR fiNITE L1 G r 1 fO~ L1 •"' lHE ·FACTOR, r 1 fOR Ll • " I 

VALUES OF r 1 FOR L1 • " CAN BE OBTAINED 

FROM FIG. B-3 

0.3 0.5 

RATIO 

s • 

Figure B-4. Ratio between x3 for blocked or open exits and x3 for L3 = "" 

where 

G5 = specific gravity of soil solids 

e = void ratio 

to 

j. Slope of hydraulic grade line beneath levee, M. The slope of the hydraulic grade line in the pervious 

substratum beneath a levee can best be determined from readings of piezometers located beneath the levee 

where the seepage flow lines are essentially horizontal and the equipotential lines vertical. If such readings 

during high water are available, M can be determined from the following relation: 

B-10 
M '

Äh

R

M '

H

x1% L2% x3

Qs' S/ kf H

Qs' Mkfd

EM 1110-2-1913

30 Apr 2000

B-11

(B-10a)

where 

Äh = the difference in piezometer readings

 R = the horizontal distance between piezometers

This relationship is not valid, however, until artesian flow conditions have developed beneath the levee. If no

piezometer readings are available, as in the case for new levee design, M must be determined by exit points

and first establishing the effective seepage entrance and then connecting these points with a straight line, the

slope of which is M. For new levees M is expressed as 

(B-10b)

B-5. Computation of Seepage Flow and Substratum Hydrostatic Pressures

a. General

(1) Seepage. For a levee underlain by a pervious foundation, the natural seepage per unit length of levee,

Q , can be expressed by the general equation B-11. S

(B-11)

where

S/ = shape factor

This equation is valid provided the assumptions upon which Darcy's law is based are met. The mathematical

expressions for the shape factor S/ (subsequently given in this appendix) depend upon the dimensions of the

generalized cross section of the levee and foundation, the characteristics of the top stratum both riverward and

landward of the levee, and the pervious substratum. Where the hydraulic grade line M is known from

piezometer readings, the quantity of underseepage per unit length of the levee can be determined from equation

B-12 as

(B-12)

(2) Excess hydrostatic head beneath the landside top stratum.

(a) The excess hydrostatic head h beneath the top stratum at the landside levee toe is related to the net o

head on the levee, the dimensions of the levee and foundation, permeability of the foundation, and the

character of the top stratum both riverward and landward of the levee. The head ho can be expressed as a

function of the net head H and the geometry of the piezometric line as subsequently shown.

(b) The head hx beneath the top stratum at a distance x landward from the landside levee toe can be

expressed as a function of the net head H and the distance x although it is more conveniently related to the

head h at the levee toe. When h is expressed in terms of h it depends only upon the type and thickness of o x o
S/ '

d

L2% 0.86d

S/ '

d

L1% L2% L3

ho' H

L3

L1% L2% L3

hx' ho

L3& x

L3

for x # L3

hx' 0 for x $ L3

EM 1110-2-1913

30 Apr 2000

B-12

the top stratum and pervious foundation landward of the levee; the ratio hx/ho is thus independent of riverward

conditions.

(c) Expressions for S/, h , and h are discussed in the following paragraphs. o x

b. Various underseepage flow and top substratum conditions.

Case 1 - No Top Stratum. Where a levee is founded directly on pervious materials and no top stratum exists

either riverward or landward of the levee (Figure B-5a), the seepage QS can be obtained from equation B-11

in which

(B-13)

The excess hydrostatic head landward of the levee is zero and ho = hx = 0. The severity of such a condition

in nature is governed by the exit gradient and seepage velocity that develop at the landside levee toe which can

be estimated from a flow net compatible with the value of S/ computed from Equation B-13. The maximum

allowable exit gradient should be 0.5.

Case 2 - Impervious Top Stratum Both Riverside and Landside. This case is found in nature where the levee

is founded on thick (zbl > 4.58 m (15 ft)) deposits of clay or silts with clay strata. For such a condition little

or no seepage can occur through the landside top stratum. 

a. If the pervious substratum is blocked landward of the levee, no seepage occurs beneath the levee and

Q = 0. The head beneath the levee and the landside top stratum is equal to the net head at all points so that s

H = h = h . o x

b. If the top stratum is impervious between the levee and river and has a length L1, and if an open seepage

exit exists in the impervious top stratum at some distance L from the landside toe (i.e., L is not infinite as 3 3

shown in Figure B-5b), the distance from the landside toe of the levee to the effective seepage entry (river,

borrow pit, etc.) is S = L1 + L2 and

(B-14)

The heads ho and hx can be computed from

(B-15)

(B-16)
S/ '

d

L1% L2% 0.43d

S/ '

d

0.43d % L2% L3

ho' H

L3

0.43d % L2% L3

hx' ho

L3& x

L3

S/ '

d

x1% L2% 0.43d

S/ '

d

0.43d % L2% x3

ho' H

x

3

0.43d % L2% x

3

EM 1110-2-1913

30 Apr 2000

B-13

Case 3 - Impervious Riverside Top Stratum and No Landside Top Stratum. This condition may occur

naturally or where extensive landside borrowing has taken place resulting in removal of all impervious material landward of the levee for a considerable distance. Seepage can be computed utilizing Equation B-11 and

the following shape factor

(B-17)

The excess head at the top of the sand landward of the levee is zero and the danger from piping must be evaluated from the upward gradient obtained from a flow net. This case is shown in Figure B-5c.

Case 4 - Impervious Landside Top Stratum and No Riverside Top Stratum. This is a more common case

than Case 3, occurring when extensive riverside borrowing has resulted in removal of the riverside impervious

top stratum (Figure B-5d). For this condition the seepage is computed from Equation B-11 utilizing the shape

factor given in Equation B-18 below; the heads h and h can be computed from Equations B-19 and B-20, o x

respectively.

(B-18)

(B-19)

(B-20)

Case 5 - Semipervious Riverside Top Stratum and No Landside Top Stratum. The same equation for the

shape factor as was used in Case 3 can be applied to this condition provided x is substituted for L as follows: 1 1

(B-21)

Since no landside top stratum exists, h = h = 0. This case is illustrated in Figure B-6a. o x

Case 6 - Semipervious Landside Top Stratum and No Riverside Top Stratum. The same equations for the

shape factor and heads beneath the landside top stratum that are used for Case 4 are applicable to this case

provided x is substituted for L (Figure B-6b). These equations are as follows: 3 3

(B-22)

(B-23)
EM 1110-2-1913 

30 Apr 2000 

~· CASE 1 - No top stratum ~· CASE 2 - Impervious topstrat\Jll 

both riverside and: lands.fde 

J = A 

L2 + 0.86d 

h .::; h ~ 0 

0 X 

.£.· CASE 3 - Impervious riverside top: 

stratunt & no landstde- top stratum 

d. CASE 4. - Imperv~us landsfde- t~ 

s tr~tum & n~ rfversJde: tap stratt.R: 

$ d ~ L

1 ~ L

2 + o.43d 

h = h .. 0 0 . X 

BASIC OEFIHITIONS ANU EQUATIONS 

HEAO.BENEATH TOP STRATUM AT LANDSIDE LEVEE TOE .•. 

HEAD BENEATH TOP STRATUM AT DISTANCE x FROH UUIDSIDE LEVEE TOE 

SHAPE· FACTOR FOR USE m SEEPAGE EQUATION 

SEEPAGE PER UNIT. LENGTH OF LEVEE .... Q • s 

Figure B-5. Equations for computation of underseepage flow and substratum pressures for cases 1 

through 4 

B-14 
~· CASE 5 - Semipervious riverside top stratum and no landside top stratum 

EM 1110-2-1913 

30 Apr 2000 

H ----

I! • d~·. '.. ~ • :' • .. , : '• • ~ : •' '•• ' :- :• : ~ • 

$ • xl + [2 + o.43d 

h • h • 0 0 X 

d 

~ •• •• t ,. ••• .... •• •• • • •• • ,_...... 

~· CASE 6 - Semipervious landside top stratum and no riverside top stratum 

Figure B-6. Equations for computation of underseepage flow and substratum pressures for cases 5 and 6 

(B-24) 

Case 7- Semipervious Top Strata Both Riverside and Landside. Where both the riverside and 1andside top 

strata exist and are semipervious (Figure B-7), the quantity ofunderseepage can be computed from equation 

B-11 where Sis defined in Equation B-25. 

d 9=----

The head beneath the top stratum at the 1andside toe of the levee is expressed by 

(B-25) 

(B-26) 

The equations above are valid for all conditions where the landside top stratum is semipervious. However, 

the head ~ beneath the semipervious top stratum depends not only on the head h0 but also on conditions 

landward of the levee. Expressions are given below for typical conditions encountered landward oflevees. 

B-15 
EM 1110-2-1913 

30 Apr 2000 

a. L3 = oo 

~~'! ,, '~ ~-h.;"l~ :~''''k'. [),,,, :·· ''}--· . . ' ' . . . b . .. (X) 

' ·, ' ~ ' .... ., ' ) ' . . ' ' ' :: ··, 

x, =-!-

hx =ho e-cr 

x, c tanh(cL, ) 

cos h c(L3 ~x) 

h.= ho cosh cL3 

h. (for x=L, )= coshh cL 

b. L3 is finite to a seepage block 

X, L2 L3 tan h(cL ) X = 3 

3 c 

h =h sinh c(L3 ~x) 

• o sin h cL3 

h, (for x=L3 )=0 

c. L3 is finite to an open seepage exit 

BASIC DEFINITIONS AND EQUATIONS 

$kH = 1 x+L+x I 2 3 

SEEPAGE PER UNIT LENGTH OF LEVEE........................................ Q, = 

Hx3 HEAD BENEATH TOP STRATUM AT LANDSIDE LEVEE TOE............ h = __ ___::. __ 0 

XI + L + X 2 3 

Figure B-7. Equations for computation of underseepage and substratum pressures for Case 7 

B-16 

3 
hx

' hoe

&cx

hx' ho

cosh c(L3& x)

cosh cL3

hx(at x ' L3) '

ho

cosh cL3

hx' ho

sinh c(L3& x)

sinh cL3

hx(at x ' L3) ' 0

c '

kbl

kfz

bl d

, ho' H

x3

x1% L2% x3

EM 1110-2-1913

30 Apr 2000

B-17

(1) For L3 = 4

(B-27)

where

e = 2.718

(2) For L3 = a finite distance to a seepage block

(B-28)

and

(B-29)

(3) For L = a finite distance to an open seepage exit 3

(B-30)

and

(B-31)

(4) Values of c and h in Equations B-27 through B-30 are as follows: o

(B-32)

(5) In order to simplify the determination of hx for various values of x, the relationship between hx/ho and

x/x3is plotted in Figure B-8 for L3 = 4 and for various values of x3/L3 for both a seepage block and an open

seepage exit. The procedure for determining h using Figure B-8 can be summarized as follows: x

a. Determine x , L , x and the head h at the landside toe of the levee. 1 2 3 o

b. For the given distance x where hx needs to be determined find the ratios x/x3 and x3/L3, then enter the

appropriate graph in Figure B-8 to read the corresponding value of h /h . x o

c. Knowing the ratio h /h and the value of h compute h . x o o x

(6) Values of ho and hx resulting from the equations above are actually hydrostatic heads at the middle

of the pervious substratum; where the ratio kf/kb is less than 100 to 500, values of ho and hx immediately
EM 1110-2-1913 

30 Apr 2000 

beneath the top stratum will be slightly less than those computed because of the head loss resulting from 

upward seepage through the sand stratum. 

1(1 0 J:..S::. 

0 

~ 

RATIO .21.. 

1<:3 

Figure B-8. Ratio between head landward of levee and head at landside toe of levee for levees founded on 

semipervious top stratum underlain by a pervious substratum 

B-18 
EM 1110-2-1913

30 Apr 2000

C-1

Appendix C

Design of Seepage Berms

C-1. General

This appendix presents design factors, equations, criteria, and examples of designing landside seepage berms.

A discussion of the four major types of landside seepage berms is presented in the main text of this manual.

The design equations presented are taken from U.S. Army Engineer Waterways Experiment Station

TM 3-424 and EM 1110-2-1901 (Appendix A). Design procedures are taken from TM 3-424 and from

procedures developed by the Lower Mississippi Valley Division (Appendix A).

C-2. Design Factors

a. Seepage records, if available, should be studied to determine the severity of the underseepage

conditions during high water. A projection based upon these records of underseepage during high water to

the design flood should be made based on experience and judgment. Aerial photographs and borings should

be used to evaluate geologic and soil conditions. The location of drainage ditches and borrow pits should

be noted and considered in design. Additional borings should be made where required to determine in situ

soil and geological data needed for design.

b. The distance s from the landside toe of the levee to the point of effective seepage entry is equal to the

base width of the levee L2 1 plus the effective length of blanket x on the riverside of the levee. The effective

length of blanket x can be determined by using blanket equations presented in Appendix B. The effect of 1

riverside borrow pits or natural low areas such as oxbows, must be considered in determining x1. The

effective length of blanket x1 should be the lesser of the distance based on the blanket thickness outside the

riverside borrow pit and the distance based on the blanket thickness inside the riverside borrow pit plus the

distance from the riverside toe of the levee to the borrow pit. The blanket equations assume an infinite

blanket length. However, this assumption may not be valid if the river is close to the levee. If the computed

value of x is greater than L (distance from riverside toe of levee to the river), then x should equal L . 1 1 1 1

Distances to effective sources of seepage, effective lengths of riverside blankets, and vertical permeabilities

of riverside blanket materials at different sites along the Mississippi River at the crest of the 1950 high water

period are given in Table C-1. The values of x1 are observed values adjusted to an assumed condition of a

riverside blanket of infinite length with the same thickness as that of the borrow pit. The adjustment was

made by use of blanket equations presented in Appendix B to partially eliminate the effect of different top

strata riverward of the borrow pits and different distances between the levee and river at various sites.

c. The thickness d and permeability kf of the pervious materials between the bottom of the blanket and

the entrenched valley must be determined before designing a seepage berm. In Appendix B, paragraph B-4c,

methods are described for determining d and k .f

d. The permeability kbl and effective thickness zbl of the landside blanket must be determined before the

seepage exit length x can be computed. If the blanket is composed of more than one stratum and the vertical 3

permeability of each stratum is known, the thickness of each stratum of the blanket can be transformed into

an equivalent thickness of material having the same permeability as for one of the strata. A procedure and

example for transforming the actual thickness of a stratified blanket into an effective thickness zbl with a

uniform vertical permeability is described in Appendix B, paragraph B-4b(2). The critical thickness of the

landside top stratum zt that should be used to determine if uplift pressure is within safe limits may or may

not be equal to z for stratified layers. The procedure and examples for computing z for different conditions bl t

of soil stratification are also presented in Appendix B, paragraph B-4b(2).
EM 1110-2-1913

30 Apr 2000

C-2Table C-1a

Summary of Distances to Effective Source of Seepage, Effective Lengths of Riverside Blankets, and Vertical Permeability of Riverside Blanket Materials at the Crest of1950 High Water (Metric Units) Blanket in Riverside Number of  Borrow Pit Piezometer Lines Suggested

 Thickness from Which Data S, m x m k x 10 cm/sec Design Values 1 br a -4

Soil Type in m Were Obtained Max Min Avg Max Min Avg Max Min Avg k x , m br 1Sand -- 3 304.8 243.8 292.6 146.3 61 112.8 – – – – 76.2Silty sand <1.52 3 243.8 170.7 204.2 97.5 70.1 85.3 14.2 1.6 7.0 7.0 91.4 b

1.52 to 3.05 1 170.7 170.7 170.7 85.3 85.3 85.3 1.8 1.8 1.8 2.5 182.9

5.7c

Silt and sandy <1.52 4 457.2 182.9 320 371.8 83.3 204.2 7.4 0.24 2.2 2.0 121.9 silt 1.52 to 3.05 2 487.7 277.4 384 362.7 155.4 259.1 5.0 0.33 2.7 1.5 243.8

365.8

>3.05 2.4 1.0 c

Clay <1.52 6 390.1 185.9 310.9 228.6 33.6 210.3 1.7 0.34 0.79 0.8 182.9

1.52 to 3.04 2 524.3 463.3 493.8 387.1 326.1 356.6 1.3 0.86 1.08 0.5 396.2 d d d

3.05 to 4.58 2 – – – – – – – – – 0.2 762.0>4.58 3 960.1 243.8 487.7 4 4 4 0.0 0.00 0.00 0.05 1219.2e

0.4 or L c,f 1

 Values of x computed from observed values of x and adjusted to a condition where L = 4. a 1 1 1 Does not include Hole-in-the-Wall where values of S and x may not be reliable because artesian flow conditions did not develop until near the crest of the 1950 high water. b 1

 Averages of all values of k for a given soil type without regard to thickness. c br

 Values are considered to be too high as at these piezometer lines (Upper Francis) seepage could enter the pervious substratum through a silty blanket riverward of the borrow pit d

as well as through the clay in the borrow pit.

 Use the smaller of the two values. e

 Average does not include k for blanket thickness between 1.52 and 3.05 m. f br
EM 1110-2-1913

30 Apr 2000

C-3

Table C-1bSummary of Distances to Effective Source of Seepage, Effective Lengths of Riverside Blankets, and Vertical Permeability of Riverside Blanket Materials at the Crest of1950 High Water (English Units) Blanket in Riverside Borrow Pit Numer of Piezometer 

 Thickness Lines from Which Data S, ft x ft k x 10 cm/sec Suggested Design Values 1 br a -4

Soil Type in ft Were Obtained Max Min Avg Max Min Avg Max Min Avg k x (ft) br 1Sand -- 3 1080 800 960 480 200 370 -- -- -- -- 250Silty sand <5 3 800 560 670 320 230 280 14.2 1.6 7.0 7.0 300 b

5 to 10 1 560 560 560 280 280 280 1.8 1.8 1.8 2.5 600

5.7c

Silt and sandy <5 4 1500 600 1050 1220 270 670 7.4 0.24 2.2 2.0 400 silt 5 to 10 2 1600 910 1260 1190 510 850 5.0 0.33 2.7 1.5 800

1200

>10 2.4 1.0 c

Clay <5 6 1280 610 1020 750 110 690 1.7 0.34 0.79 0.8 600

5 to 10 2 1720 1520 1620 1270 1070 1170 1.3 0.86 1.08 0.5 1300 d

10 to 15 0 -- -- -- -- -- -- -- -- -- 0.2 2500>15 3 3150 800 1600 4 4 4 0.0 0.00 0.00 0.05 4000 or L1e

0.4c,f

 Values of x computed from observed values of x and adjusted to a condition where L = 4. a 1 1 1 Does not include Hole-in-the-Wall where values of S and x may not be reliable because artesian flow conditions did not develop until near the crest of the 1950 high water. b 1

 Averages of all values of k for a given soil type without regard to thickness. c br

 Values are considered to be too high as at these piezometer lines (Upper Francis) seepage could enter the pervious substratum through a silty blanket riverward of the borrow pit d

as well as through the clay in the borrow pit.

 Use the smaller of the two values. e

 Average does not include k for blanket thickness between 5 and 10 ft. f br
EM 1110-2-1913 

30 Apr 2000 

e. The seepage exit length x3 can be calculated from equations presented in Appendix B, 

paragraph B-4g. These equations are applicable to conditions where the length of the landside blanket L3 

is either infinite or finite. 

C-3. Design Equations and Criteria 

a. Design equations. Equations for the design oflandside seepage berms for the four major berm types 

are presented in Figure C-1. These equations are valid when a lands ide blanket of infinite length exists. A 

discussion of the four major landside seepage berms is presented in paragraph 5-4. 

y~ • :~~:;':!r:~ vd,bt 

Yi • ~~::!cl unit vd,ht 

Tv • un..lt vei~tht ot ...-..ter 

B • tot&l Df:t. bf:a.d on 

leTt:t: 

h' • H (~x '::--:• ':---,--) _o •+x3 +x 

·~- 't (~) t - y' 

1 + ~v 

USET!_2.,8 

PERVIOUS SUBSTRATUM 

b • bc&.d &l land.dde t.o. Of lt"YCe 

0 Kx 

vithoul kr1l • ....::1..-

• +X) 

h' - bc&.d &t. l&.ndslde t.oe or lnce vltb 

0 ...... 

10 • ~!:"';:!e ~~:ep-L41~t &t 1&:)4-

11 • :~:'"r!,h upvu-d 'radlcat &t t..oe 

vhere: 

A • 6 + Jsd r • 1) 

r • 1

0 /1 1 

h~ • "• [1 • or ·(~)(ex )'] b' - l l. 0 0 t t•--- 1 + 10 

h • a..Uovable hc-.4 &t toe 

.. or bent • 11 · &t 

X • requirN bc-r. vldth 

t • required thlcbu:u of bcr-. 

a.t toe of lu·cc 

kt • ~=~lca..l per-.u.b111ty of 

r • ra.ct.or or aa.tcty &.«;&lnat 

uplift at t~ or leTcc 

X • l (X + 2:X: ) I ) p IP 

Figure C-1. Design of landside seepage berms on impervious top stratum 

b. Design criteria 

~ • flov into kra per foot 

of levee 

1 • diatancc fro- la.Nhlde toe 

or levee to crre-ctlvc 

aaur~c or &ecpe..&e entry 

x3 • :~·~::~: ~(~:::~;~• toe 

source of seepe.c:e exit. 

d - etreett.ve tbt.ck.ne•• or perr1ou• •ub•t.rat.UII. 

Perrloul Bera vi t.h 

Collector 

( 1) Where a levee overlies a top stratum creating a landside blanket and the upward gradient through the 

blanket at the landside toe of the levee is greater than 0.8, a seepage berm should be designed with an 

allowable upward gradient of 0.3 through the blanket and berm at the landside toe of the levee. For a 

C-4 
ho

N '

H(X % 0.43 D)

x

1

% L2% X % 0.43 D

d k

h

/k

v

Qs'

kf Hd

x1% L2% X % 0.43 D

EM 1110-2-1913

30 Apr 2000

C-5

saturated unit soil weight of 1840 kg/m (115 pcf), this is equivalent to a factor of safety of 2.8. The factor 3

of safety of 2.8 applies only to new construction, not to existing projects. A factor of safety lower than 2.8

may be used, based on sufficient soil data and past performance in the area. The berm width should be based

on an allowable upward gradient of 0.8 through the top stratum at the landside toe of the berm, subject to

the limitations in the paragraphs which follow. The thickness of the berm should be increased 25 percent

to allow for shrinkage, foundation settlements and variations in design factors. Where field observations

during lesser floods indicate severe seepage problems would occur at the design flood, the berm dimensions

should be extended. 

(2) All berms should have minimum thickness of 1.52 m (5 ft) at the levee toe, a minimum thickness of

0.61 m (2 ft) at the berm crown, and a minimum width of 45.7 m (150 ft). 

(3) For conditions where the computed upward gradient at the landside toe of the levee is between 0.5

and 0.8 without a berm, a berm with minimum dimensions as specified in (2) above should be constructed.

Also for conditions where the computed gradient is less than 0.5, but either severe seepage has been observed

or seepage is expected to become severe and soften the landside portion of the levee, the minimum berm

should be constructed.

(4) The width of the berm is usually limited to about 91.4 to 121.9 m (300 to 400 ft), although the design

calculations may indicate that a greater berm width is required. When the selected width of the berm is less

than the calculated width, using berm design equations of Figure C-1, the head h N and berm thickness t at o

the levee toe will be less than for the computed width. For the selected berm, hoN should be recomputed

assuming an i1 of 0.8 at the toe of the new berm and a linear piezometric grade line between the toe of the

new berm and the point of effective seepage entry. The design thickness of the selected berm at the toe of

the levee and the estimated seepage flow under the levee will be based on the value of hoN corresponding to

the selected berm. 

(5) For conditions where no landside blanket exists, the necessity for a landside seepage berm will be

based on the exit gradient and seepage velocity as discussed in paragraph B-5b. The berm thickness at the

landside toe should be of such magnitude that the upward gradient io does not exceed 0.3. The design

thickness of the berm should be increased by 25 percent to allow for shrinkage, foundation settlements, and

variationsin design factors. The head hoN beneath the berm at the landside toe of the levee can be determined

from Equation C-1.

(C-1)

In the above equation D& is the transformed thickness of the pervious stratum which is equal to ,

L2is the base width of the levee, H is the total net head on levee, X is the berm width, and x1 , is the effective

length of impervious blanket riverside of the levee. If no riverside blanket exists, the value of x1 is assumed

to be 0.43 D&. The rate of seepage Qs below the levee per unit length of levee can be determined using

Equation C-2.

(C-2)
EM 1110-2-1913

30 Apr 2000

C-6

In the equation above, k is the permeability of the pervious substratum and d is the effective thickness of f

the pervious substratum. H , x1 , L2 , X , and D& are as previously defined. If Qs exceeds 757.1 R/min

(200 gal/min) per 30.5 m (100 ft) of levee, a riverside blanket should be designed to reduce the seepage.

Riverside blankets are discussed in paragraph 5-3.

(6) The slope of berms should be generally 1V on 50H or steeper to ensure drainage. If the berm is

constructed after the levee has caused the foundation to consolidate fully, a slope of 1V on 75H can be used.

Where wide, thick berms are required, consideration may be given to using a berm with a broken surface

slope to more closely simulate the theoretical thickness and consequently reduce the cost of the berm. Where

this is done, the steeper riverward slope of the berm should be no flatter than 1V on 75H and the landward

slope of the berm should be no flatter than 1V on 100H.

(7) In short reaches where computations indicate no berm is necessary, but berms are required in adjacent

reaches, it may be advisable to continue the berm construction through such reaches due to concentration of

seepage in these areas. Also, in areas where entrance conditions in adjacent reaches are highly variable,

potential adverse effects of close entry in adjacent reaches should be taken in to consideration. 

C-4. Design Example

An example design problem with solution is presented in Table C-2 illustrating the design of impervious,

semipervious, sand, and free draining landside seepage berms overlaying a thin landside top stratum. Each

berm is designed for the same conditions using the design equations and design criteria as presented in this

appendix.
(") 

I 

....... 

Table C-2a 

Examples of Design of Seepage Berms (Metric Units) 

Designs based on following conditions: 

H 7.6m z, = 1.83 m 

1,000 x 10·4 em/sec 0.30 

d 30.5 m 0.80 

3 X 1 0-4 em/SeC y' 840.5 kg/m3 

s 304.8 m 137.2 m 

Suggested Design Dimensions 

Reguired Berm Thickness Berm Approximate 

Width Thicknessa h lb 

0 at Berm Width Berm Thickness 

Type Berm X,m t, m m Crown m X,m Slope Levee Toe m 

Impervious 268.2 2.22 4.33 0.61 243.89 1 on 75 3.87 

1.49 3.23 0.61 121.9 1 on 75 2.22 

Semi pervious 85.34 1.16 2.62 0.61 83.82 1 on 75 1.74 

Sand 79.20 1.0 2.53 0.61 76.20 1 on 75 1.61 

Pervious with 65.53 0.88 2.35 0.61 60.96 1 on 75 1.43 

collector 

a At toe of levee. 

b Head at toe of levee with berm, measured above surface of natural ground. 

c Thickness increased 25 percent for shrinkage, foundation settlements, and variations in design factors. 

d Calculations based on suggested construction dimensions. 

y' 

y' 

F 

840.5 kg/m3 for impervious berms 

920.6 kg/m3 for sand berm or 

pervious berm with collector, 

F = 1.6 

1.6 for impervious berm 

Approximated 

Suggested Construction Dimensions Material 

Thicknessc Berm Thicknessc Required 

at Berm Width at Levee m3 per 100m 

Crown m X,m Toem of Levee 

0.76 243.8 4.85 73,266 

0.76 121.9 2.77 23,312 

0.76 83.82 2.16 13,321 

0.76 76.20 2.01 11,528 

0.76 60.96 1.80 8,4541 

e Berm width considered longer than necessary. If boils developed 121.9 m or farther landward of the toe of the levee, the levee probably would not be endangered. 

Therefore, an alternate design for an impervious berm with a width of 121.9 m is also given. 

' Sand and gravel blankets and collector system are also required. 

m 

s: 

(,) ...... 0 ...... 

...... l>o 

~r\, I 

1\) ...... 

0<0 

0 ...... ow 
EM 1110-2-1913

30 Apr 2000

C-8 Table C-2b

Examples of Design of Seepage Berms (English Units)Designs based on following conditions:H = 25 ft z = z = 6.0 ft ãN = 52.5 pcf for impervious berms bl tk = 1,000 × 10 cm/sec i = 0.30 ãN = 57.5 pcf for sand berm or pervious f o -4

berm with collector, F = 1.6

 d = 100 ft i = 0.80 F = 1.6 for impervious berm 1k = 3 × 10 cm/sec ãN = 52.5 pcf L = 4 bl 3 -4 s = 1,000 ft x = 450 ft 3

Approximated

 Suggested Design Dimensions Suggested Construction Dimensions Material

 Required Berm Thickness Berm Approximate Thickness Berm Thickness Required cWidth Thickness h N at Berm Width Berm Thickness at Berm Width at Levee yd per 100 ft a b o

Type Berm X, ft t, ft ft Crown ft X, ft Slope Levee Toe ft Crown ft X, ft Toe ft of LeveeImpervious 880 7.3 14.2 2.0 800 1 on 75 12.7 2.5 800 15.9 28,600 e

4.9 10.6 2.0 400 1 on 75 7.3 2.5 400 9.1 9,100

Semipervious 280 3.8 8.6 2.0 275 1 on 75 5.7 2.5 275 7.1 5,200Sand 260 3.3 8.3 2.0 250 1 on 75 5.3 2.5 250 6.6 4,500Pervious with 215 2.9 7.7 2.0 200 1 on 75 4.7 2.5 200 5.9 3,300f collector

 At toe of levee. a Head at toe of levee with berm, measured above surface of natural ground. b

 Thickness increased 25 percent for shrinkage, foundation settlements, and variations in design factors. c

 Calculations based on suggested construction dimensions. d Berm width considered longer than necessary. If boils developed 400 ft or farther landward of the toe of the levee, the levee probably would not be endangered. Therefore, an e

alternate design for an impervious berm with a width of 400 ft is also given.

 Sand and gravel blankets and collector system are also required. f
EM 1110-2-1913

30 Apr 2000

 In paragraphs D-2 and D-3 the criteria apply to drains and filters; for brevity, only the word filter will be used. 1

 In practice, it is normal for a small amount of protected soil to move into the filter upon initiation of seepage. This action should quickly stop and 2

may not be observed when seepage first occurs. This is one reason that initial operation of embankment seepage control measures should be closely

observed by qualified personnel. 

3

 Guide for Determining the Gradation of Sand and Gravel Filters, Soil Mechanics Note No. 1, U.S. Department of Agriculture Soil Conservation

Services, Engineering Division, January 1986.

D-1

Appendix D

Filter Design

D-1. General

The objective of filters and drains used as seepage control measures for embankments is to efficiently control

the movement of water within and about the embankment. In order to meet this objective, filters and drains

must, for the project life and with minimum maintenance, retain the protected materials, allow relatively free

movement of water, and have sufficient discharge capacity. For design, these three necessities are termed,

respectively, piping or stability requirement, permeability requirement, and discharge capacity. This

appendix will explain how these requirements are met for cohesionless and cohesive materials, and provide

general construction guidance for installation of filters and drains. The terms filters and drains are

sometimes used interchangeably. Some definitions classify filters and drains by function. In this case, filters

must retain the protected soils and have a permeability greater than the protected soil but do not need to have

a particular flow or drainage capacity since flow will be perpendicular to the interface between the protected

soil and filter. Drains, however, while meeting the requirements of filters, must have an adequate discharge

capacity since drains collect seepage and conduct it to a discharge point or area. In practice, the critical

element is not definition, but recognition, by the designer, when a drain must collect and conduct water. In

this case the drain must be properly designed for the expected flows. Where it is not possible to meet the

criteria of this appendix, the design must be cautiously done and based on carefully controlled laboratory

filter tests. 

D-2. Stability

Filters and drains allow seepage to move out of a protected soil more quickly than the seepage moves within 1

the protected soil. Thus, the filter material must be more open and have a larger grain size than the protected

soil. Seepage from the finer soil to the filter can cause movement of the finer soil particles from the

protected soil into and through the filter. This movement will endanger the embankment. Destruction of 2

the protected soil structure may occur due to the loss of material. Also, clogging of the filter may occur

causing loss of the filter’s ability to remove water from the protected soil. Criteria developed by many years

of experience are used to design filters and drains which will prevent the movement of protected soil into the

filter. This criterion, called piping or stability criterion, is based on the grain-size relationship between

the protected soil and the filter. In the following, the small character “d” is used to represent the grain size

for the protected (or base) material and the large character “D” the grain size for the filter material.

Determine filter gradation limits using the following steps:3

1. Determine the gradation curve (grain-size distribution) of the base soil material. Use enough samples

to define the range of grain sizes for the base soil or soils and design the filter gradation based on the base

soil that requires the smallest D size. 15
EM 1110-2-1913

30 Apr 2000

D-2

2. Proceed to step 4 if the base soils contains no gravel (materials larger than No. 4 sieve). 

3. Prepare adjusted gradation curves for base soils with particles larger than the No. 4 (4.75 mm ) sieve.

a. Obtain a correction factor dividing 100 by the percent passing the No. 4 (4.75 mm) sieve.

b. Multiply the percentage passing each sieve size of the base soil smaller than No. 4 (4.75 mm) by the

correction factor from step 3a. 

c. Plot these adjusted percentages to obtain a new gradation curve. 

d. Use the adjusted curve to determine the percent passing the No. 200 (0.075 mm) sieve in step 4.

4. Place the base soil in a category based on the percent passing the No. 200 (0.075 mm) sieve in accordance

with Table D-1.

Table D-1

Categories of Base Soil Materials

 Percent Finer Than the No. 200

Category (0.075 mm) Sieve

1 >85

2 40-85

3 15-39

4 <15

5. Determine the maximum D15 size for the filter in accordance with Table D-2. Note that the maximum

D is not required to be smaller than 0.20 mm. 15

6. To ensure efficient permeability, set the minimum D greater than or equal to 3 to 5 × maximum d of 15 15

the base soil before regrading but no less than 0.1 mm.

7. Set the maximum particle size at 75 mm (3 in.) and the maximum passing the No. 200 (0.075 mm) sieve

at 5 percent. The portion of the filter material passing the No. 40 (0.425 mm) sieve must have a plasticity

index (PI) of zero when tested in accordance with EM 1110-2-1906, “Laboratory Soils Testing.”

8. Design the filter limits within the maximum and minimum values determined in steps 5, 6, and 7.

Standard gradations may be used if desired. Plot the limit values, and connect all the minimum and

maximum points with straight lines. To minimize segregation and related effects, filters should have

relatively uniform grain-size distribution curves, without “gap-grading”—sharp breaks in curvature

indicating absence of certain particle sizes. This may require setting limits that reduce the broadness of

filters within the maximum and minimum values determined. Sand filters with D90 less than about 20 mm

generally do not need limitations on filter broadness to prevent segregation. For coarser filters and gravel

zones that serve both as filters and drains, the ratio D /D should decrease rapidly with increasing D size. 90 10 10

The limits in Table D-3 are suggested for preventing segregation during construction of these coarser filters.
40 & A

40 & 15

15 percent size of filter material

15 percent of the protected soil

$ 3 to 5

EM 1110-2-1913

30 Apr 2000

D-3

Table D-2

Criteria for Filters

Base Soil Base Soil Description and

Category Percent Finer Than the No. 200 (0.075 mm) Sieve (a)

1 Fine silts and clays; more than 85 percent finer (c) D15 # 9 × d85

2 Sands, silts, clays and silty and clayey sands; 40 to 85 percent finer D15 # 0.7 mm

3 Silty and clayey sands and gravels; 15 to 39 percent finer (d), (e) D15 #

 [(4 × d85) - 0.7 mm] + 0.7

mm

4 Sands and gravels; less than 15 percent finer (f) D15 # 4 to 5 × d85

(a) Category designation for soil containing particles larger than 4.75 mm is determined from a gradation curve of the base soil

which has been adjusted to 100 percent passing the No. 4 (4.75 mm) sieve.

(b) Filters are to have a maximum particle size of 75 mm (3 in.) and a maximum of 5 percent passing the No. 200 (0.075 mm)

sieve with the plasticity index (PI) of the fines equal to zero. PI is determined on the material passing the No. 40 (0.425 mm)

sieve in accordance with EM 1110-2-1906, “Laboratory Soils Testing.” To ensure sufficient permeability, filters are to have a

D size equal to or greater than 4 × d but no smaller than 0.1 mm. 15 15

(c) When 9 × d is less than 0.2 mm, use 0.2 mm. 85

(d) A = percent passing the No. 200 (0.075 mm) sieve after any regrading.

(e) When 4 × d is less than 0.7 mm, use 0.7 mm. 85

(f) In category 4, the D15 # 4 × d85 criterion should be used in the case of filters beneath riprap subject to wave action and drains

which may be subject to violent surging and/or vibration. 

Table D-3

D10 and D90 Limits for Preventing Segregation

Minimum D10 Maximum D90

 (mm) (mm)

 < 0.5 20

 0.5 - 1.0 25

 1.0 - 2.0 30

 2.0 - 5.0 40

 5.0 - 10 50

 10 - 50 60

D-3. Permeability

The requirement that seepage move more quickly through the filter than through the protected soil (called

the permeability criterion) is again met by a grain-size relationship criterion based on experience:

Permeability

(D-1)
Minimum 50 percent size of filter material

hole diameter or slot width

$ 1.0

EM 1110-2-1913

30 Apr 2000

1

 Sherard, J. L., Dunnigan, L. P., “Filters and Leakage Control in Embankment Dams,” Proceeding of the Symposium on Seepage and Leakage from

Dams and Impoundments, ASCE National Convention, Denver, Colorado, 1985.

2

 EM 1110-2-2300 states, “Collector pipe should not be placed within the embankment, except at the downstream toe, because of the danger of either

breakage or separation of joints, resulting from fill placement and compaction operations, or settlement, which might result in either clogging and/or

piping.”

D-4

Permeability of a granular soil is roughly proportional to the square of the 10- to 15-percent size material.

Thus, the permeability criterion ensures that filter materials have approximately 9 to 25 or more times the

permeability of the protected soil. Generally, a permeability ratio of at least 5 is preferred; however, in the

case of a wide band of uniform base material gradations, a permeability ratio as low as 3 may be used with

respect to the maximum 15-percent size of the base material. There may be situations, particularly where

the filter is not part of a drain, where the permeability of the filter is not important. In those situations, this

criterion may be ignored. 

D-4. Applicability

The previously given filter criteria in Table D-2 and Equation D-1 are applicable for all soils (cohesionless

or cohesive soils) including dispersive soils. However, laboratory filter tests for dispersive soils, very fine 1

silt, and very fine cohesive soils with high plastic limits are recommended. 

D-5. Perforated Pipe2

The following criteria are applicable for preventing infiltration of filter material into perforated pipe, screens,

etc.:

(D-2)

In many instances a filter material meeting the criteria given by Table D-2 and Equation D-1 relative to the

material being drained is too fine to meet the criteria given by Equation D-2. In these instances, multilayered

or “graded” filters are required. In a graded filter each layer meets the requirements given by Table D-2 and

Equation D-1 with respect to the pervious layer with the final layer in which a collector pipe is bedded also

meeting the requirements given by Equation D-2. Graded filter systems may also be needed when

transitioning from fine to coarse materials in a zoned embankment or where coarse material is required for

improving the water-carrying capacity of the system. 

D-6. Gap-Graded Base

The preceding criteria cannot, in most instances, be applied directly to protect severely gap- or skip-graded

soils. In a gap-graded soil such as that shown in Figure D-1. The coarse material simply floats in the matrix

of fines. Consequently, the scattered coarse particles will not deter the migration of fines as they do in a

well-graded material. For such gap-graded soils, the filter should be designed to protect the fine matrix

rather than the total range of particle sizes. This is illustrated in Figure D-1. The 85-percent size of the total

sample is 5.2 mm. Considering only the matrix material, the 85-percent size would be 0.1 mm resulting in

a much finer filter material being required. This procedure may also be followed in some instances where

the material being drained has a very wide range of particle sizes (e.g., materials graded from coarse gravels

to significant percentages of silt or clay). For major structures such a design should be checked with filter

tests. 
. I 

U S. STANDARD SIEVE OPENING IH INCHES U S. STANDARD SIEVE NUMBERS 

6 4 3 ~ 

,,.. I f t 3 4 6 I 10 1416 20 30 40 50 70 100 140 

I f'\:-t I II ·' I I I ..... ~--- I 

--1--~ - -- 1-1- -- r- ~ ,~ 

' r ..... 

"' -- ...... -. f4 f-Du- - ,.:; ~- . 

100 

90 

i"""o r-..... . -. - 80 

- . ~ . TOTAL MATERIAL· v "70 

.. .. - . - -·- - ·-·- . -- 1---

1-1- -- -- .. -

---·- -- -- .. . - -·f- -- - 30 

. .. -- - -·- - 0. -I20 , 

- - -- -.. - . . 0 

1-'-1- -- .. --- c 

500 100 50 10 5 I 05 0.1 GAAIN SitE IN MllLIMttUS 

COBBLES SAND 

Figure D-1. Analysis of a gap-graded material 

20o 

- . o, 

l'o ~ 

-~ [; 

-, - too. I' 

1-1-~ ·-1\. 

. ' 0 

-

-

0.05 

HYDROMmR 

. 1--:-

- 1- M~TRIX MATERIAL •. 

r-r-. 

r\"7 - \ ~-

~ 

.. 

1-r- - -- 0.01 11.005 

SILT OR aAT 

10 

I... 

30 

40 

50 

60 

·-- 70 

'90 

- 0.01 

w-" o-" .... l>O '01 

.. N 

I 

...., .... OCD 

0-> 

ow 
EM 1110-2-1913

30 Apr 2000

 Sherard, J. L., “Sinkholes in Dams of Coarse, Broadly-Graded Soils,” Transactions of the 13th International Congress on Large Dams, New 1

Delhi, India, Vol. II, 1979, pp 25-35.

D-6

D-7. Gap-Graded Filter

A gap-graded filter material must never be specified or allowed since it will consist of either the coarse

particles floating in the finer material or the fine material having no stability within the voids produced by

the coarse material. In the former case the material may not be permeable enough to provide adequate

drainage. The latter case is particularly dangerous since piping of the protected material can easily occur

through the relatively large, loosely filled voids provided by the coarse material. 

D-8. Broadly Graded Base

One of the more common soils used for embankment dams is a broadly graded material with particle sizes

ranging from clay sizes to coarse gravels and including all intermediate sizes. These soils may be of glacial,

alluvial-colluvial, or weathered rock origin. As noted by Sherard (1979) , since the 85-percent size of the 1

soil is commonly on the order of 20 to 30 mm, a direct application of the stability criteria D15/d85 # 4 to 5

would allow very coarse uniform gravel without sand sizes as a downstream filter, which would not be

satisfactory. The typical broadly graded soils fall in Soil Category 2 in Table D-2 and require a sand or

gravelly filter with D # 0.7 mm. 15

D-9. Example of Graded Filter Design for Drain

Seldom, if ever, is a single gradation curve representative of a given material. A material is generally

represented by a gradation band which encompasses all the individual gradation curves. Likewise, the

required gradation for the filter material is also given as a band. The design of a graded filter which shows

the application of the filter criteria where the gradations are represented by bands is illustrated in Figure D-2.

A typical two-layer filter for protecting an impervious core of a dam is illustrated. The impervious core is

a fat clay (CH) with a trace of sand which falls in Category 1 soil in Table D-2. The criterion D15 # 9 × d85

is applied and a “point a” is established in Figure D-2. Filter material graded within a band such as that

shown for Filter A in Figure D-2 is acceptable based on the stability criteria. The fine limit of the band was

arbitrarily drawn, and in this example, is intended to represent the gradation of a readily available material.

A check is then made to ensure that the 15-percent size of the fine limit of the filter material band (point b)

is equal to or greater than 3 to 5 times the 15-percent size of the coarse limit of the drained material band

(point c). Filter A has a minimum D size and a maximum D size such that, based on Table D-3, 10 90

segregation during placement can be prevented. Filter A meets both the stability and permeability

requirements and is a suitable filter material for protecting the impervious core material. The second filter,

Filter B, usually is needed to transition from a fine filter (Filter A) to coarse materials in a zoned

embankment dam. Filter B must meet the criteria given by Table D-2 with respect to Filter A. For stability,

the 15-percent size of the coarse limit of the gradation band for the second filter (point d) cannot be greater

than 4 to 5 times the 85-percent size of the fine limit of the gradation bank for Filter A (point e). For

permeability, the 15-percent size of the fine limit (point f) must be at least 3 to 5 times greater than the

15-percent size of the coarse limit for Filter A (point a). With points d and f established, the fine and coarse

limits for Filter B may be established by drawing curves through the points approximately parallel to the

respective limits for Filter A. A check is then made to see that the ratio of maximum D90/minimum D10 size

Filter B is approximately in the range as indicated in Table D-3. A well-graded filter which usually would

not meet the requirements in Table D-3 may be used if segregation can be controlled during placement.

Figure D-2 is intended to show only the principles of filter design. The design of thickness of a filter for

sufficient seepage discharge capacity is done by applying Darcy’s Law, Q = kia.
... 

-

.iJ.S. STA!IDARD SIEVE OPEHIHQ IH IHCHES · U.S. ITIJIDAIID SIEVE NUMBERS 

tOO 11tStzt01 I 4. ~ 2 1~· 1 ·~ ~ ~ :1 4 I I tO t4tl 20 3D 40 ·sa ·70 tOO t40 200 

I I I \ ' ll\ I . I I I I ~ I I 1\ 

' \ " i' 

1\ 'e· 10 

\ \ ~ 

\ \ \ 10 

\ \ \ ~ 

.\ \ \ ~' ~ 

\ ~' ~ 

~ ~ 

':?.., r\. 

\ d) \ 

70 

_\ \ 

\ \ .\ 

\ \ at;;9 (das) min 

\ 1\ 1\ 

_\ i\ f ~3 lo 5a i\ 

\ \ 

d \j I\. "b \ a'\. "" 0 

d~ .Ia 5~ 1\ I'. 

20 

D ~ t'\.. 

HYDROMETm 

I I 

I I 

1\. . ! I 

_(das)mln 

"\. 

1\ 1\ 

i\. 

~~\.. ' «.'! '').-G)\ \..,('! ,~~ Q 

' ' ' I' 

b~3 to 5c" 

too sa 10 I D.l 0.1 0.05 0.01 0.005 

ORJJH SIZE IN MIWMETERI 

Figure D-2. Illustration of the design of a graded filter 

' 

I'. 

D 

1 

' 70 

'\. 

C"\ 

100 

.0.001 

m 

s: 

w-" o-" _. )>O 

"C' 

-. N 

I 

N-" 

0<0 

0-> 

ow 
EM 1110-2-1913

30 Apr 2000

D-8

D-10. Construction

EM 1110-2-1911 and EM 1110-2-2300 provide guidance for construction. Major concerns during

construction include: 

a. Prevention of contamination of drains and filters by runoff containing sediment, dust, construction

traffic, and mixing with nearby fine-grained materials during placement and compaction. Drain and filter

material may be kept at an elevation higher than the surrounding fine-grained materials during construction

to prevent contamination by sediment-carrying runoff. 

b. Prevention of segregation, particularly well-graded filters, during handling and placement.

c. Proper in-place density is usually required to be no less than 80-percent relative density. Granular

materials containing little or no fines should be saturated during compaction to prevent “bulking” (low

density) which can result in settlement when overburden materials are placed and the drain is subsequently

saturated by seepage flows.

d. Gradation should be monitored closely so that designed filter criteria are met. 

e. Thickness of layers should be monitored to ensure designed discharge capacity and continuity of the

filter. 

Thus, quality control/assurance is very important during filter construction because of the critical function

of this relatively small part of the embankment. 

D-11. Monitoring

Monitoring of seepage quantity and quality (see Chapter 13 of EM 1110-2-1901 for method of monitoring

seepage) once the filter is functioning is very important to the safety of the embankment. An increase in

seepage flow may be due to a higher reservoir level or may be caused by cracking or piping. The source of

the additional seepage should be determined and action taken as required (see Chapters 12, 13, and 14 of EM

1110-2-1901). Decreases in seepage flows may also signal dangers such as clogging of the drain(s) with

piped material, iron oxide, calcareous material, and effects of remedial grouting. Again, the cause should

be determined and appropriate remedial measures taken. Drain outlets should be kept free of sediment and

vegetation. In cold climates, design or maintenance measures should be taken to prevent clogging of drain

outlets by ice. 
kNf ' kh kv

dN ' d kh /kv

EM 1110-2-1913

30 Apr 2000

E-1

Appendix E

Drainage Trench

E-1. General

This appendix presents the design and analysis of drainage trenches. The design criteria and the example

presented are taken from U.S. Army Engineer Waterways Experiment Station TM 3-424 (Appendix A).

E-2. Applicability

A drainage trench can be used to control underseepage where the top stratum is thin and the pervious

foundation is relatively shallow so that the trench substantially penetrates the aquifer. Where the pervious

foundation is deep, a drainage trench of moderate depth would attract only a small portion of the

underseepage. The drainage trench method is known to be effective where the ratio of the thickness of the

landside blanket, zbl , to the depth of the pervious foundation, d, is greater than 25 percent. While only

substantial penetration by the drainage trench provides significant landside relief, a trench with limited

penetration may be used in conjunction with a landside blanket to contain seepage pressures.

E-3. Design Criteria

The design criteria and graphs are applicable only for homogeneous, isotropic pervious foundations having

an impervious top stratum landward of the drainage trench. The distance from the source of seepage to the

landside toe of the levee, S, to be used in the design may be estimated by a procedure outlined in Appendix B.

Seepage into a drainage trench, Q , and the maximum head landside of the levee, h , where the blanket st 4

landside of the levee consists of impervious or relatively impervious soil, can be computed using the graphs

presented in Figure E-1. The analysis and design procedure is as follows:

a. Where kh > kv transform the in situ pervious stratum into a homogeneous, isotropic formation using

kN and dN for k and d, respectively, as follows: f f

(E-1)

(E-2)

where

 d = thickness of the pervious foundation

 kh = coefficient of horizontal permeability

 kv = coefficient of vertical permeability

 kNf = transformed coefficient of permeability of the foundation

 dN = transformed depth of the pervious foundation

b. From the geometry of the drainage trench, Figure E-1, find the ratio of r /d, (Case I) or b /d (Case II) d d

where:

 r = radius of the circular sector of the trench for Case I b

 b = width of the rectangular trench section for Case II d
m 

I 

N 

2.4 

2.2 r\. 

2.0 

1.8 ' '\ 

1.6 '\ 

1.4 

"'\ ' ~ 

z 1.2 

<r: 

0 

"l?'U> ':c!> 

~7 

!'-

0 fLa 

a-: 

r-----------"s'-------t__::=----!.-UPLIFT BENEATH 

TOP STRATUM 

SHAPE FACTOR S = S+ EL 

.:::__:_!A_+= d d 

MAXIMUM NET UPLIFT RATIO UNDER TOP IMPERVIOUS BLANKET 

LANDSIDE OF DRAIN IN h {{=S, A., 

fJ/"d 1. 0 ~U> t.-- ~ CASE I 

0.8 ' ' ~ 

0.6 

0.4 

i' 

~ ..... ~ ... At ~Aa 

""" ' 0.2 

0.0 

-0.2 

NOT : "lllll ~ '- CURVES SHOWN ARE BASED 

~ON THE RATIO s '~ IJL 1'1 ..... <r>l 

r -

' I \ 

-0.4 I 

0.001 0.01 0.1 0.2 0.30.4 0.60.81.0 

NOTE: 

~I.!._ 

d ' d 

SHAPE FACTORS = EL 

_s- + -.::::= d d 

MAXIMUM NET UPLIFT RATIO UNDER TOP IMPERVIOUS BLANKET 

LANDSIDE OF DRAIN IN h 

{{= s. "· 

CASE II 

SEEPAGE PER UNIT LENGTH OF STRUCTURE IS A Q=k, HS 

WHERE K" > K., TRANSFORM_ PERVIUS SUBSTRATUM TO A HOMOGENEOUS, 

ISOTROPIC FOUNDATION AND USE "K, FOR k, AND d FOR d IN ABOVE FORMAULAS. 

k, = }k::k. AND d=dJF 

Figure E-1. Formulas and design curves for drainage trenches (ref. EM 1110-2-1601) 

wm 

os: 

)>_. 

"C _. ... _. 

NO 

0• oN o..:.. 

CD 

_. 

w 
S/

1

'

d

S % r

d

% EL1

S/

2

'

d

S % EL2

Qst ' S/ kN

f H

h4' H S/ ë

EM 1110-2-1913

30 Apr 2000

E-3

c. Use the computed ratio of rd/d or bd/d to enter the appropriate graph of Figure E-1 to determine the

corresponding value of EL/d and ë. The factor EL is the extra length of pervious substratums corresponding

to the increased resistance to flow into a drainage trench as compared to a fully penetrated open trench, and

ë is an uplift factor. The values of EL1/d and ë, are related to Case I, while EL2/d and ë2 are related to

Case II.

d. Once the magnitude of EL is determined, the value of the shape factor S/ which is equivalent to the

ratio in the flow net of the number of flow channels to the number of equipotential drops, can be determined

as:

Case I:

(E-3)

Case II:

(E-4)

e. Calculate the quantity of discharge per unit length of the levee, Qst, and the maximum head landside

of the trench, h , using the following expressions: 4

(E-5)

(E-6)

where

H = total head acting on the levee, or the height of flood stage above the average low-ground surface or

tail water

Where there is no top stratum landside of the levee, seepage flow into the drainage trench and beyond can

be estimated from the flow net analysis.

E-4. Limitations of the Method

The method of controlling underseepage using the trench drain method has several limitations:

a. If the top stratum landside of the drainage trench has a certain degree of perviousness, seepage into

the trench and the maximum head landward of the levee will be somewhat less than those computed from

Figure E-1. Therefore, design based on Figure E-1 will be slightly on the conservative side if the top stratum

landside of the drain trench is semipervious.

b. If the pervious foundation is highly stratified, seepage may bypass the drain and emerge landward of

the drain thereby defeating its purpose. For such cases, other methods of seepage control are more effective.

c. If the trench is underlain by either impervious or semipervious strata of either clay, silt, or fine sand,

the formulas presented in Part E-3 are no longer applicable.
EM 1110-2-1913

30 Apr 2000

E-4

E-5. Design Example

Figure E-2 illustrates the design of a drainage trench in a thin impervious blanket overlying a shallow

pervious stratum. The trench drain (Case II) is designed using equations presented in Part E-3 of this

appendix.
m 

I 

U1 

{ 

.. 

I 

0 

~ 

243.em 

eoo· 

.:-:. . -~ '·. 

}t 

Lki!c;-, -- co:::O-xi~O 4 om/oea .. ;·c" 

k'r • ~ •COOxlo-4 om/ooe(.03m/mln).': > .... d'•d" kH/kV •.Slm (200~) , • . 

. , . ,_. :·. -~ ··. :.- .... :: .. :. : . ~ .' : : ·--~ . .' .. : · ..... :· ... : .... ~- . :· 

CROSS SECTION OF LEVEE, FOUNDATION AND DRAINAGE TRENCH 

bd/d =7.em(25')/61m(200') =0.125; EL2jd•=0.80 and'-2 =0.75 

,£ 1 1 1 :1' = S/d'+E~/d' = 243.8m(800')/61m(200')+0.B • 4.l! =.208 

SEEPAGE FLOW PER UNIT LENGTH OF LEVEE, Q0 : 

Q0 - # k H = 0.208x.03m(.1')/mln x 7.6m(25') -.04?4m3 /mpm OF LEVEE 

or 1.445ni'pm/30.5m(100') OF LEVEE 

MAX!Ytm HEAD BENEATH LANDSIDE BLANKET, h"' : 

hoo/H = # .208x.75=.156 OR 15.8,; 

hoo= 1.56xH=.156x7.6m(25')= 1.17m(3.9') 

Figure E-2. Example of design of a drainage trench 

.. / 

DETAILS OF DRAINAGE TRENCH 

m 

s: 

w::::: 

0_. 

)>O 

'C' 

-. N I\).:.. 

O<D 

0-> 

ow 
EM 1110-2-1913

30 Apr 2000

F-1

Appendix F

Emergency Flood Protection

F-1. Introduction

a. Flood fighting. Flood fighting can be defined as those emergency operations that are taken in advance

of and during a flood to prevent or minimize damages to public and private property. As defined herein,

flood fighting includes the hasty construction of emergency levees; the overbuilding of existing levees or

natural river banks; ring and U-shaped levees constructed around facilities or areas of high property value;

preservation of vital facilities including water treatment plants and wells; power and communication

facilities; protection of sanitary and storm sewer systems; and provisions for interior drainage treatment during flood stages. Flood fighting plans should acknowledge that it may not be feasible to protect entire

communities based on economic or time and equipment considerations; therefore, evacuation of certain areas

may be a necessary facet of an emergency operation. 

b. Recommended local organization. Each community with a flood history should establish an

organization and written plans for the purpose of conducting flood fighting operations. These plans should

include identification of flood-prone areas and previous high water marks; flood fighting or evacuation plans;

delegation of responsibilities; lists of important suppliers of materials and special equipment; lists of local

contractors; and establishment of earth borrow sites, etc. The plan should further provide for the

establishment of an emergency operation center and list various assistance programs available, either through

the State or Federal government. Further assistance in developing these plans can be provided by the State

or local Civil Defense Director in the area. 

F-2. Flood Barrier Construction

a. Introduction. The two basic features of an emergency levee system include the flood barrier, generally

constructed of earth fill, and the related interior drainage treatment. It is desirable that individuals assigned

to a flood-fight situation have prior knowledge of flood barrier construction, interior drainage, and related

flood-fight problems which they may encounter. They should also be acquainted with the past flood

emergency efforts, historical flood stages, and forecasted stages for the community. The following

information will provide personnel with guidelines based on actual experience. However, it cannot be over

emphasized that individual resourcefulness is a key element in a successful flood fight. 

b. Preliminary work. 

(1) Alignment. A complete alignment for the barrier should be established promptly and, if possible, in

cooperation with State or local floodplain management officials. The alignment should be the shortest

practical route, provide the maximum practical protection, and take advantage of any high ground where

practicable. The flood barrier should be kept as far landward of the river as possible to prevent

encroachment on the floodway and to provide maximum space for overbank flows. This is especially

important for smaller floodways where encroachment would directly impact the water surface profile. Sharp

bends should be avoided. Topographic, plat, or city street maps may be useful in selecting alignment. In

choosing the alignment, consideration should be given as to whether sufficient time remains to complete

construction before the flood crest arrival. Potentially unstable river banks should be avoided. Keep as

many trees and brush between the levee and river as possible to help deflect current, ice, and debris. However, in constricted areas of the river, 1.52 m (5 ft), and preferably 3.05 m (10 ft), should be allowed between

the levee toe and vertical obstructions such as trees. In urban areas, many communities within a flood prone
EM 1110-2-1913

30 Apr 2000

F-2

area already have some levees in-place. These communities typically fight the flood along this primary line

of defense. Moving the alignment farther landward creates problems in determining methods to stop

floodwater backup through storm and sanitary sewer lines. It could also leave storm and sanitary lift stations

on the riverside of the flood barrier. Leaving some homes outside the line of protection also exposes the

watermains to floodwater infiltration. Right-of-way considerations may also influence the final alignment.

Generally, the city or county engineer will assist in laying out the line and grade for the barrier, or a professional surveyor may be available. However, if help is not available, a hand-level along with a known

elevation can be used to lay out rough grade. As soon as the alignment is firm, quantities of earthwork

should be estimated for establishing equipment and borrow requirements.

(2) Drainage. In laying out a flood barrier, the problem of interior drainage from snowmelt, rain, or

sewer backup should be considered. A certain amount of ponding, if valuable property will not be damaged,

is not detrimental and may be allowed. The excess interior water can be pumped out over the levee if pumps

are available.

(3) Borrow area and haul road. The two prime requisites for a borrow area are that adequate material

be available and that the site be accessible at all times. The quantity estimate plus an additional 50 percent

should provide the basis for the area requirement. The area must be located so that it will not become

isolated from the project by high water. The borrow area should also be located where the present water

table, if known, and the water table levels caused by high water will not hinder or stop its use. If possible,

a borrow area should be selected which will provide suitable materials for levee construction as covered

below. Local contractors and local officials are the best source of information on available borrow areas.

If undeveloped, the area should be cleared of brush, trees, and debris, with topsoil and surface humus being

stripped. In cold regions in early spring, it will probably be necessary to rip the area to remove frozen material. An effort should be made to borrow from the area in such a manner that the area will be relatively

smooth and free-draining when the operation is complete. The haul road may be an existing road or street,

or it may have to be constructed. To mitigate damages it is highly desirable to use unpaved trails and roads,

or to construct a road if the haul distance is short. In any case, the road should be maintained to avoid

unnecessary traffic delays. The use of flagmen and warning signs is mandatory at major crossings such as

highways, near schools, and at major pedestrian crossings. A borrow area, or source of sand for sandbags,

should also be located promptly. This can become a critical item of supply in some areas due to long haul,

project isolation, etc. It may become necessary to stockpile material near anticipated trouble areas.

(4) Equipment. One of the important considerations in earthwork construction is the selection of proper

equipment to do the work. Under emergency conditions, obtaining normally specified earthwork equipment

will be difficult and the work will generally be done with locally available equipment. It may be wise to call

for technical assistance in the early contract stage to insure that proper and efficient equipment use is

proposed. If possible, compaction equipment should be used in flood-barrier construction. This may involve

sheepsfoot, rubber-tired, or vibratory rollers. Scrapers should be used for hauling when possible because

of speed (on short haul) and large capacity. Truck haul, however, has been the most widely used. A ripper

will be necessary for opening borrow areas in the early spring if the ground is frozen. A bulldozer of some

size is mandatory on the job to help spread dumped fill and provide minimum compaction.

(5) Construction contract. The initiation of a construction contract under emergency conditions is very

unique in that sole judgment as to the competence and capabilities of the contractor lies with field personnel.

Field personnel, therefore, must be somewhat knowledgeable in construction operations. The initial contract

is very important in that it delineates what equipment must be accounted for on the project and what is

available for construction. During construction, if it becomes obvious that the equipment provided by the

initial contract is inadequate to provide reasonably good construction or timely completion, a new or supplemental contract may be required. Procedures are the same as in the initial contract. Flexibility may be
EM 1110-2-1913

30 Apr 2000

F-3

built into the original contract if it can be foreseen that additional pieces of equipment will ultimately be

used. 

(6) Supplies. Early anticipation of floodfight problems will aid greatly in providing necessary and

sufficient supplies on hand. These include sandbags, polyethylene, pumps, etc. The importance of initiative,

resourcefulness, and foresight of the individual on the project cannot be over emphasized. Technical

assistance may be invaluable in locating potential problem areas which, with proper materials at hand, could

be alleviated early.

c. Earth fill levees.

(1) Foundation preparation. Prior to embankment construction, the foundation area along the levee alignment should be prepared. This is particularly important if the levee is to be left in place. Since spring

flooding is the only condition providing much advance warning, the first item of work in cold regions

probably will be snow removal. The snow should be pushed riverward so as to decrease ponding when the

snow melts. Trees should be cut and the stumps removed. All obstructions above the ground surface should

be removed, if possible. This will include brush, structures, snags, and similar debris. The foundation

should then be stripped of topsoils and surface humus. (Clearing and grubbing, structure removal, and

stripping should be performed only if time permits.) Stripping may be impossible if the ground is frozen.

In this case, the foundation should be ripped or scarified, if possible, to provide a rough surface for bond with

the embankment. Every effort should be made to remove all ice or soil containing many ice lenses. Frost

or frozen ground can give a false sense of security in the early stages of a flood fight. It can act as a rigid

boundary and support the levee; but on thawing, soil strength may be reduced sufficiently for cracks or slides

to develop. It also forms an impervious barrier to prevent seepage. This may result in a considerable

buildup in pressure under the soils landward of the levee, and upon thawing pressure may be sufficient to

cause sudden blowouts. If this condition exists it must be monitored, and one must be prepared to act quickly

if sliding or sand boils develop. If stripping is possible, the material should be pushed landward and

riverward of the toe of levee and windrowed. After the flood, this material may be spread on the slopes to

provide topsoil for vegetation.

(2) Materials. Earth fill materials for emergency levees will usually come from local borrow areas. An

attempt should be made to utilize materials which are compatible with the foundation materials. Due to time

limitations, however, any local materials may be used if reasonable construction procedures are followed.

The material should be relatively clean (free of debris) and should not contain large frozen pieces of earth.

(a) Clay. Clay is preferred because the section can be made smaller (steeper side slopes). Clay is also

relatively impervious (will not readily permit passing of water) and has relatively high resistance to erosion

in a compacted state. A disadvantage in using clay is that adequate compaction is difficult to obtain without

proper equipment and when the material is wet. Another disadvantage is if the clay is wet and sub-freezing

temperatures occur, this may cause the material to freeze in the borrow pit and hauling equipment. Weather

could cause delays and should definitely be considered in the overall construction effort.

(b) Sand. If sand is used, the section should comply as closely as possible with recommendations in

paragraph F-2.C.(3)(b) below. Steep slopes without poly coverage on the riverside slope will result in

seepage through the levee that exits on the landward slope causing slumping of the slope and potential overall

failure if it occurs over an extended period of time.

(c) Silt. Material which is primarily silt should be avoided. If used, poly facing must be applied to the

river slope. In addition to being very erodible, silt, upon wetting, tends to collapse if not properly

compacted. 
EM 1110-2-1913

30 Apr 2000

F-4

(3) Levee section.

(a) General. In standard levee design the configuration of the levee is generally dictated by the

foundation soils and the materials available for construction. Therefore, even under emergency conditions,

an attempt should be made to make the embankment compatible with the foundation. Information on

foundation soils may be available from local officials or engineers, and it should be utilized. The two levee

sections cited below are classical and idealized, and usual field conditions depart from them to various

degrees. However, if they are used as a guide, possible serious flood-fight problems could be lessened

during high water. In determining the top width of any type of section, consideration should be given as to

whether a revised forecast will require additional fill to be placed. A top width adequate for construction

equipment will facilitate raising the levee. Finally, actual dike construction will, in most cases, depend on

time, materials, and right-of-way available.

(b) Sand section. Use 1 V (Vertical) on 3 H (Horizontal) toward a river, 1 V on 5 H landward slope,

and 3.05-m (10-ft) top width.

(c) Clay section. Generally 1 V on 2 1/2 H slopes are used but for low height levees 1 V on 2 H slopes

have been used successfully. It is important to always use a 3.05 m (10 ft) top width. When clay levees are

constructed on pervious foundations, the bottom width may not be adequate to reduce the potential for

foundation piping. This can be accomplished by using berms either landward or riverward of the levee.

Berm thickness will be site specific. Berms reduce the potential for foundation piping, but do not reduce

foundation seepage. 

(4) Placement and compaction. As stated above, obtaining proper compaction equipment for a given soil

type will be difficult. It is expected in most cases that the only compaction will be from that due to the

hauling and spreading equipment; i.e., construction traffic routed over the fill. Levee height should provide

0.61 m (2 ft) of freeboard above forecast flood crest. In urban areas, the upstream end of the project should

use a larger freeboard than the downstream end.

(5) Slope protection.

(a) General. Methods of protecting levee slopes from current scour, wave wash, seepage, and debris

damage are numerous and varied. However, during a flood emergency, time, availability of materials, cost

and construction capability preclude the use of all accepted methods of permanent slope protection. Field

personnel must decide the type and extent of slope protection the emergency levee will need. Several

methods of protection have been established which prove highly effective in an emergency. Again,

resourcefulness on the part of the field personnel may be necessary for success.

(b) Polyethylene and sandbags. Experience has shown that a combination of polyethylene (poly) and

sandbags is one of the most expedient, effective, and economical methods of combating slope attack in a

flood situation. Poly and sandbags can be used in a variety of combinations, and time becomes the factor

that may determine which combination to use. Ideally, poly and sandbag protection should be placed in the

dry. However, many cases of unexpected slope attack will occur during high water, and a method for

placement in the wet is covered below. See Figures F-1 to F-4 for suggested methods of laying poly and

sandbags. Since each flood fight project is generally unique (river, personnel available, materials, etc.),

specific details of placement and materials handling will not be covered. Personnel must be aware of

resources available when using poly and sandbags.
SECTION 

NOTE: 

Alternate direction of socks with 

bottom layer par.ollel to flow, 

nex-t Ioyer perpendicular to flow, etc. 

Lap unfilled portion under: next · 

EM 1110-2-1913 

30 Apr 2000 

sack. 

Tyino 

Ta.mp 

s.acks 

thoroughly 

or 

&houtd 

sewino 

be 

liocka 

In 

approximately 

place. 

not nece"ary. 

V2 METHOD 

~t 

OF LAPPING SACKS 

lull of sand. 

Figure F-1. Sandbag barrier 

(c) Toe anchorage and poly placement. Anchoring the poly along the riverward toe is important for a 

successful job. It may be done in three different ways: ( 1) After completion of the levee, a trench excavated 

along the toe, poly placed in the trench, and the trench backfilled; (2) Poly placed flat-out away from the toe, 

and earth pushed over the flap; and (3) Poly placed flat-out from the toe and one or more rows of sandbags 

placed over the flap. The poly should then be unrolled up the slope and over the top enough to allow for 

anchoring with sandbags. Poly should be placed from downstream to upstream along the slopes and 

overlapped at least 0.61 m (2ft). The poly is now ready for the "hold-down" sandbags. 

F-5 
EM 1110-2-1913 

30 Apr 2000 

TYPES OF WOOD AND EARTH LEVEES 

RIVERSIDE LANDS IDE 

(I' Material to be tamped 

C I against bottom board 

li\ 50x1 00mm(2x4in)Approx1.5m(5ft)long 

.6m{2ft)Min. penetratration 

50x100 OR 100x200mm 

{2x4 OR 4x4in) Posts 

25x304.8mm(lx12in) 

Boarding 

CD BASE WIDTH TWO TIMES HEIGHT ® 

FLASH BOARD LEVEE BOX LEVEE 

Figure F-2. Flash board and box levee 

RIVERSIDE 

(d) Slope anchorage. It is mandatory that poly placed on levee slopes be held down. An effective 

method of anchoring poly is a grid system of sandbags, unless extremely high velocities, heavy debris, or 

a large amount of ice is anticipated. Then a solid blanket of bags over the poly should be used. A grid 

system can be constructed faster and requires fewer bags and much less labor than a total covering. Various 

grid systems include vertical rows oflapped bags, two-by-four lumber held down by attached bags, and rows 

F-6 
EM 1110-2-1913 

30 Apr 2000 

1 BAG EVERY 1.82m(6ft) 

SAND BAGS STAGGERED TO PROTECT 

POLYETHYLENE FROM DEBRIS & ICE 

--

EXCESS POLYETHYLENE ROLLED 

FOR FUTURE DIKE RAISE 

GROUND UNE 

PLACE EDG.E OF POLYETHYLENE 

IN 152mm(16in) DEEP TRENCH (DEEPER TRENCH IS DESfRABLE) OR LAYOUT FROM TOE 

LACE .15m(6mil) POLYETHYLENE LOOSELY 

WITH SLACK) ON THE SMOOTH SURFACE 

SECTION 

5 

dV~9 SC1f1 -

METHODS OF ANCHORING 

POLYETHYLENE 

.15rnm(6mil) BLACK POLYETHYLENE IS THE MOST 

DESIRABLE .15mm(6mil) CLEAR SECOND .10mm(4mil) BLACK THIRJ2~ .10mm(4mil) CLEAR FOURTH & .Oomm(2mil) POLYETHYLE~E SHOULD O~LY BE USED AS A 

LAST RESORT. 

Figure F-3. Placement of polyethylene sheeting on temporary levee 

F-7 
EM 1110-2-1913 

30 Apr 2000 

;' 

I 

'· '· -

Figure F-4. Placement of polyethylene sheeting in the wet 

of bags held by a continuous rope tied to each bag. Poly can also be held down by a system using two bags 

tied with rope and the rope saddled over the levee crown with a bag on each slope. 

(e) Placement in the wet. In many situations during high water, poly and sandbags placed in the wet 

must provide the emergency protection. Wet placement may also be required to replace or maintain 

damaged poly or poly displaced by current action. Figure F-4 shows a typical section oflevee covered in 

the wet. Sandbag anchors are formed at the bottom edge and ends of the poly by bunching the poly around 

F-8 
EM 1110-2-1913

30 Apr 2000

F-9

a fistful of hand or rock and tying the sandbags to this fist-sized ball. Counterweights consisting of two or

more sandbags connected by a length of 6.35-mm (1/4-in.) rope are used to hold the center portion of the

poly down. The number of counterweights will depend on the uniformity of the levee slope and current

velocity. Placement of the poly consists of first casting out the poly sheet with the bottom weights and then

adding counterweights to slowly sink the poly sheet into place. The poly, in most cases, will continue to

move down slope until the bottom edge reaches the toe of the slope. Sufficient counterweights should be

added to insure that no air voids exist between the poly and the levee face and to keep the poly from flapping

or being carried away in the current. For this reason, it is important to have enough counterweights prepared

prior to the placement of the sheet.

(f) Overuse of poly. In past floods there has been a tendency to overuse and in some cases misuse poly

on slopes. For example, on well compacted clay embankments, in areas of relatively low velocities, use of

poly would be unnecessary. Also, placement of poly on landward slopes to prevent seepage must not be

done. It will only force seepage to another exit and may prove detrimental. Poly has been used on the

landside slope of levees to prevent rainwater from entering a crack where slope movement has occurred,

particularly in fat clay soils. Keeping water out of the cracks resulting from slope movements is desirable

to prevent lubrication and additional hydrostatic pressure on the slip surface. 

(g) Riprap. Riprap is a positive means of providing slope protection and has been used in a few cases

where erosive forces were too large to effectively control by other means. Objections to using riprap when

flood fighting are: (1) rather costly; (2) large amount necessary to protect a given area; (3) availability; and

(4) little control over its placement, particularly in the wet.

(h) Groins. In the past, small groins, extending 3.05 m (10 ft) or more into the channel were effective

in deflecting current away from the levees. Groins can be constructed by using sandbags, snow fence, rock,

compacted earth, or any other substantial materials that are available. Preferably groins should be placed

in the dry and at locations where severe scour may be anticipated. Consideration of the hydraulic aspects

of placing groins should be given, because haphazard placement may be detrimental. Hydraulic technical

assistance should be sought if doubts arise in the use of groins. Construction of groins during high water

will be very difficult and results will generally be minimal. If something other than compacted fill is used,

some form of anchorage or bonding should be provided. (For example, snow fence anchored to a tree beyond

the toe of the levee.)

(i) Log booms. Log booms have been used to protect levee slopes from debris or ice attack. Logs are

cabled together and anchored with a dead man in the levee. The boom will float out in the current and,

depending on log size, will deflect floating objects.

(j) Miscellaneous measures. Several other methods of slope protection have been used. Straw bales

pegged into the slope may be successful against wave action, as is straw spread on the slope and overlain

with snow fence. 

(6) Sandbag dikes. The sandbag dike should not be considered as a primary-flood barrier. The main

objections to their use are that the materials (bags and sand) are quite costly; they require a tremendous

amount of manpower; and are time consuming to construct. They are also very difficult to raise if the flood

forecasts are revised. Sandbag dikes should be used where a very low and relatively short barrier is required

and earth fill would not be practicable, such as in the freeboard range along an arterial street. They are very

useful in constricted areas such as around or very close to buildings, where rights-of-way would preclude

using earth fill. They are also useful where temporary closure is required, such as roads and railroad tracks.

A polyethylene seepage barrier should be incorporated into the sandbag structure. The poly must be on the

riverward slope and brought up immediately behind the outermost layer of bags. The poly should be
EM 1110-2-1913

30 Apr 2000

F-10

keyed-in to a trench at the toe and anchored, or, at best, lapped under the sandbags for anchorage. See

Figure F-1 for recommended practices in sandbag dike construction. A few points to be aware of in sandbag

construction are: (1) sand, or predominantly sandy or gravelly material should be used; (2) extremely fine,

clean sand, such as washed mortar sand, should be avoided; (3) bags should be 1/2 full; (4) bags should be

lapped when placing; (5) bags should be tamped tightly in place; and (6) the base width should be wide

enough to resist the head at high water. Sandbagging is also practical for raising a narrow levee, or when

construction equipment cannot be used. Sandbag raises should be limited to 0.91 m (3 ft), if possible.

(7) Miscellaneous flood barriers. In addition to earth fill and sandbag levees, two other types of flood

barriers should be mentioned. They are the flashboard and the box levees, both of which are constructed

using lumber and earth fill (see Figure F-2). They may be used for capping a levee or as a barrier in highly

constricted areas. Two disadvantages in using these barriers are the long construction time involved and very

high cost. Therefore, these barriers are not recommended, unless a very unusual situation warrants their use.

F-3. Emergency Interior Drainage Treatment

a. General. High river stages often disrupt the normal drainage of sanitary and storm sewer systems,

render sewage treatment plants inoperative, and cause backup in sewers and the discharge of untreated

sewage directly into the river. When the river recedes, some of the sewage may be trapped in low lying

pockets to remain as a possible source of contamination. Hastily constructed dikes intended to keep out river

waters may also seal off normal outlet channels for local runoff, creating large ponds on the landward side

of the dikes, making the levees vulnerable from both sides. If the ponding is excessive, it may nullify the

protection afforded by the dikes even if they are not overtopped. Sewers may also back up because of this

ponding.

b. Preliminary work. In order to arrive at a reasonable plan for interior drainage treatment, several items

of information must be obtained by field personnel. These are:

(1) Size of drainage area.

(2) Pumping capacity and/or ponding required.

(3) Basic plan for treatment.

(4) Storm and sanitary sewer and water line maps, if available.

(5) Location of sewer outfalls (abandoned or in use).

(6) Inventory of available local pumping facilities.

(7) Probable location of pumping equipment.

(8) Whether additional ditching is necessary to drain surface runoff to ponding and/or pump locations.

(9) Location of septic tanks and drain fields (abandoned or in use).
5000 per × 0.378 m

3

/person/day

24 hr × 60 min

' 1.314 m

3

/min

5000 persons × 100 gal/person/day

24 hr × 60 min/hr

' 347 gpm

EM 1110-2-1913

30 Apr 2000

F-11

c. Pumps, types, sizes, and capacities.

(1) Storm sewer pumps. Table F-1 indicates the size of pump needed to handle the full flow discharge

from sewer pipes up to 610 mm (24 in.) in diameter. Table F-2 shows sizes and capacities of agricultural--

type pumps which may be useful in ponding areas.

Table F-1

Matching Pipe Size to Pump Size

Sewer Pipe Size, mm (in.) Probable Required Pump Size, mm (in.)

152.4 (6) 50.8 (2)

203.2 (8) 50.8 to 76.2 (2 to 3)

254.0 (10) 76.2 to 101.6 (3 to 4)

304.8 (12) 101.6 to 152.4 (4 to 6)

381.0 (15) 152.4 to 203.2 (6 to 8)

457.2 (18) 152.4 to 254 (6 to 10)

533.4 (21) 203.2 to 254 (8 to 10)

609.6 (24) 254 to 304.8 (10 to 12)

(2) Fire engine pumps. The ordinary fire pumper has a 101.6 mm (4-in.) suction connection and a

pumping capacity of about 2838.75 R/min (750 gpm). Use only if absolutely necessary.

(3) Pump discharge piping. The Crisafulli pumps are generally supplied with 15.24-m (50-ft) lengths

of butyl rubber hose. Care must be taken to prevent damage to the hose. Irrigation pipe or small diameter

culverts will also serve as discharge piping. Care should be taken to extend pump discharge lines riverward

far enough to not cause erosion of the levee. On 304.8 mm (12-in.) or larger lines, substantial anchorage

is required. These pumps must not be operated on slopes greater than 20 degrees from horizontal.

(4) Sanitary sewage pumping. During high water, increased infiltration into sanitary sewers may

necessitate increased pumping at the sewage treatment plant or at manholes at various locations to keep the

system functioning. To estimate the quantity of sewage, allow 0.378 m (100 gal) per capita per day for

3

sanitary sewage and an infiltration allowance of 35.28 m per km-day (15,000 g/mile-day) of sewer per day. 3

In some cases, it will be necessary to pump the entire amount of sewage, and in other cases only the added

infiltration will have to be pumped to keep a system in operation.

Example: Estimate pumping capacity required at an emergency pumping station to be set up at the first

manhole above the sewage treatment plant for a city of 5,000 population and approximately 48.24 km

(30 miles) of sewer (estimated from map of city). In this case, it is assumed that the treatment plant will not

operate at all.

Required capacity = (infiltration) + (sewage)

Sewage demand: 
35.31 m

3

km

× 48.24 km 1

24 hr × 60 min

' 1.18 m

3

/min

15000 gal/mile/day × 30 miles

24 hr × 60 min/hr

' 312 gpm

EM 1110-2-1913

30 Apr 2000

F-12

Table F-2

Crisafulli Pumps - Model CP 2 in. to 24 in.

Size m /min Head Elec. Gas or Diesel 3 a

mm (in.) (gal/min) m (ft) kW (hp) kW (hp)

 50.8 (2) 0.56 (150) 0.745 (1)

101.6 (4) 1.88 (500) 5.59 (7.5) 11.18 (15)

152.4 (6) 3.76 (1000) 7.45 (10) 14.9 (20)

203.2 (8) 11.27 (3000) 3.04 (10) 11.18 (15) 18.62 (25)

304.8 (12) 18.79 (5000) 18.62 (25) 29.8 (40)

406.4 (16) 35.70 (9500) 29.8 (40) 48.4 (65)

609.6 (24) 93.95 (25000) 55.88 (75) 104.3 (140)

 50.8 (2) 0.49 (130) 0.745 (1)

101.6 (4) 1.84 (490) 7.45 (10) 14.9 (20)

152.4 (6) 3.19 (850) 11.18 (15) 18.62 (25)

203.2 (8) 9.21 (2450) 6.1 (20) 14.9 (20) 26.08 (35)

304.8 (12) 14.09 (3750) 22.35 (30) 37.2 (50)

406.4 (16) 30.06 (8000) 33.52 (45) 63.3 (85)

609.6 (24) 71.4 (19000) 74.5 (100) 141.6 (190)

 50.8 (2) 0.45 (120) 0.745 (1)

101.6 (4) 1.79 (475) 8.94 (12) 18.62 (25)

152.4 (6) 2.99 (795) 14.9 (20) 26.08 (35)

203.2 (8) 8.08 (2150) 9.84 (30) 18.62 (25) 33.52 (45)

304.8 (12) 12.96 (3450) 26.08 (35) 52.15 (70)

406.4 (16) 26.68 (7100) 44.70 (60) 93.12 (125)

609.6 (24) 62.38 (16600) 93.12 (125) 186.24 (250)

 Use high head pumps for heads over 6.1 m or 59.71 KPa (20 ft). a

Infiltration: 

Required pumping capacity: 2.49 m /min (659 gpm). From Table F-3, use one 101.6 mm (4-in.) pump 3

or its equivalent.

Table F-3

Marlow Self Priming Centrifugal Pumps

Size Capacity Horsepower b

mm (in.) AGC Rating m /min (gal/min) kW (hp) a 3

38.1 (1.5) 4M 0.25 (67) 1.34 (1.8)

50.8 (2) 7-10M 0.44-0.63 (117-167) 1.71-3.66(2.3-4.9)

76.2 (3) 20-30M 1.26-1.89 (334-500) 3.66-8.36 (4.9-

11.2)

101.6 (4) 30-40M 1.89-2.51 (500-665) 14.92-28.94 (20-

38.8)

152.4 (6) 90M 5.67 (1500) 32.46 (43.5)

203.2 (8) 125M 7.87 (2080) 46.25 (62)

254.0 (10) 12.6 (3330) 46.25 (62)

 Gallons per hour, thousands. a

 At 75 kPa (7.67-m, 25-ft) head. b
EM 1110-2-1913

30 Apr 2000

F-13

d. Metal culverts.

(1) Pumping of ponded water is usually preferable to draining the water through a culvert since the

tailwater (drainage end of culvert) could increase in elevation to a point higher than the inlet, and water could

back up into the area being protected. Installation of a flapgate at the outlet end may be desirable to

minimize backup.

(2) Table F-4 shows the capacity of corrugated pipe culverts on a flat slope, with H factor (head)

representing the difference between the headwater level and tailwater level, assuming the outlet is

submerged. If the outlet is not submerged the head equals the difference in elevation between the headwater

level and 0.6 of the diameter of the pipe measured from the bottom of the pipe upward. The capacity would

change for smooth pipe, pipe laid on a slope, or if headwalls or wingwalls are used.

(3) If a culvert is desired to pass water from a creek through a levee, a computation of the drainage

basin by an engineer is required to determine pipe size.

e. Preventing backflow in sewer lines. 

(1) Watertight sluice gates or flap gates are one answer. Emergency stoppers may be constructed of

lumber, sandbags, or other materials, using poly as a seal, preferably placed on the discharge end of the

outfall pipe. 

(2) Figures F-5 and F-6 contain manufacturer's literature on prefabricated rubber pipe stoppers which

can be placed in the outlet opening of a manhole. 

(3) Figures F-7 to F-11 illustrate methods of sealing off the outlet openings of a manhole with standard

materials which are normally available so that the manhole may be used as an emergency pumping station.

F-4. Flood Fight Problems

a. General. Problem situations which arise during a flood fight are varied and innumerable. The

problems covered below and in “Emergency Interior Drainage Treatment” are those which are considered

most critical to the integrity of the flood barrier system. It would be impossible to enumerate all of the

problems, such as supplies, personnel, communication, etc., which field personnel must handle. The most

valuable asset of field personnel under emergency conditions is their common sense. Many problems can

be solved instantly and with less effort through the application of good common sense and human relations.

Problems, such as those below, can be identified early only if a well organized levee patrol system with a

good communication system exists. The problems are presented with the assumption that high water is on

the levee slopes.

b. Overtopping. Overtopping of a levee is the flowing of water over the levee crown. Since most

emergency levees are of an urban nature, overtopping should be prevented at any cost. Overtopping will

generally be caused by: (1) unusual hydrologic phenomena, including unexpected rainfall, faster than

expected rainfall, faster than expected snowmelt, and ice and debris blockages, which cause a much higher

stage than anticipated; (2) insufficient time in which to complete the flood barrier; or (3) unexpected

settlement of the barrier. Generally, the flood barriers are constructed 0.61 m (2 ft) above the crest prediction. If the crest prediction is raised during construction, additional height must be added to the barrier.

Capping should be done with earth fill or sandbags, using normal construction procedures. For levee

construction, the 3.05 m (10 ft) top width allows the barrier to be raised relatively quickly with regular

 
EM 1110-2-1913

30 Apr 2000

F-14

Table F-4a

Capacity of Corrugated Metal Pipe Culverts

Without Headwalls and With Outlet Submerged (outlet control-full flow) (Circular) (metric Units)

Dia.

In mm 0.003 0.006 0.008 0.011 0.014 0.017 0.023 0.028 0.034 0.040 0.045 0.050 0.056 0.071 0.085 0.1 0.113

CUBIC METERS PER SECOND

Pipe Pressure in kPa

304.2 2.98 4.17 5.07 5.96 6.6 7.15 8.34 9.23 10.1 11 11.9 12.5 13.1 14.9 16.1 17.3 18.5 Length = 61 m

381 5.07 7.15 8.64 10.13 11.3 12.2 14.3 15.8 17.3 18.8 20.3 21.2 22.4 25 27.4 29.5 32.8

457.2 7.75 10.73 13.11 15.5 17 18.5 21.5 23.8 26.2 28.3 29.8 32.8 32.8 38.7 41.7 44.7 47.7

533.4 10.7 15.2 18.5 21.4 23.8 26.2 29.8 32.8 35.8 38.7 41.7 44.7 47.7 53.6 56.6 62.6 65.6

609.6 14.6 20.3 25 28.6 32.8 35.8 41.7 44.7 50.7 53.6 56.6 59.6 62.6 71.5 77.5 83.4 89.4

685.8 18.5 26.2 32.8 35.8 41.7 44.7 53.6 60 62.6 68.5 74.5 77.5 83.1 92.3 101 107 116

762.0 23.2 32.8 41.7 47.7 50.7 56.6 65.6 74.5 80.5 86.4 95.4 98.3 98 116 125 137 146

914.4 35.8 47.7 59.6 68.5 77.5 83.4 98.3 110 119.2 128.1 137 146 155 170 188 203 215

1066.8 47.7 68.5 83.4 95.4 107.2 116.2 134.1 152 164 178.8 191 203 212 235 256 277 298

1238.4 65.6 89.4 110 128 143 155 179 203 221 238.4 253 268 280 316 349 373 399

1371.6 83.4 116.2 143 164 181.8 200 232 260 289 304 325 346 361 405 444 477 510

1524 101 143 175 203 226.5 247 286 319 352 375 400 423 447 498 542 587 626

Dia.

In mm 0.003 0.006 0.008 0.011 0.014 0.017 0.023 0.028 0.034 0.040 0.045 0.050 0.056 0.071 0.085 0.100 0.113

CUBIC METERS PER SECOND

Pipe Pressure in kPa

304.2 2.38 3.27 4.17 4.8 5.4 6 6.9 7.5 8.3 8.9 9.5 10.1 10.7 11.9 13.1 14.3 15.2 Length = 122 m

381 4.17 5.66 7.15 8.05 9.24 10.1 11.6 12.8 14.3 15.5 16.4 17.6 18.5 20.6 22.6 24.4 26.2

457.2 6.26 8.94 11 12.8 14.3 15.5 17.9 20.3 22 23.8 25.6 26.8 28.6 32.8 35.7 38.7 41.7

533.4 8.94 12.8 15.8 18.2 20.3 22.1 25.6 28.6 32.8 35.8 35.8 38.7 42 44.7 50.7 536 56.6

609.6 12.5 17.6 21.5 25 28 29.8 35.8 38.7 44.7 47.7 51 53.6 57 62.6 68.5 74.5 80.5

685.8 16.4 23.2 28.6 32.8 35.8 41.7 47.7 51 56.6 62.6 66 68.6 74.5 83 89.4 98.3 104

762.0 20.9 29.2 35.8 41.7 47.7 50.7 60 66 71.5 77.5 83 89.4 92 104 113 125 131

914.4 29.8 44.7 53.6 62.6 71.5 77.5 89.4 98 107 116 125 134 140 158 173 185 197

1066.8 44.7 62.6 77.5 89.4 98.3 107 125 140 152 164 175 185 197 221 238 262 277

1238.4 59.6 83.4 104.3 119.2 134 146 167 188 206 220 238 250 265 295 25 352 378

1371.6 77.5 107.3 134.1 152 170 188 215 241 265 286 307 325 343 381 417 453 486

1524 95 134.1 164 191 215 232 268 298 328 358 381 405 426 477 522 566 602

Dia.

In mm 0.003 0.006 0.008 0.011 0.014 0.017 0.023 0.028 0.034 0.040 0.045 0.050 0.056 0.071 0.085 0.100 0.113

CUBIC METERS PER SECOND

Pipe Pressure in kPa

304.2 2.09 2.98 3.6 4.17 4.77 5.07 5.96 6.56 7.15 7.75 8.12 8.64 9.24 10.4 11.3 12.2 13.11 Length = 197 m

381 3.58 5.07 6.3 7.15 8.05 8.94 10.1 11.3 12.5 13.4 14.3 15.2 16.1 17.9 19.7 21.2 22.6

457.2 5.66 8.05 9.8 11.3 12.5 13.7 15.8 17.6 19.4 20.9 22.3 23.8 25 27.7 29.8 32.8 35.8

533.4 8.05 11.6 14.3 16.4 18.2 19.7 22.9 25.9 28.3 29.8 32.8 35.8 35.8 41.7 44.7 47.7 50.7

609.6 11.3 16.1 19.7 22.6 25 27.4 32.8 35.8 38.7 41.7 44.7 47.7 50.7 56.6 65.6 65.6 71.5

685.8 14.9 21.1 25.9 29.8 33 35.8 41.7 47.7 50.7 56.6 59.6 62.6 65.6 74.5 80.5 86.4 92.4

762.0 19.1 26.8 32.8 38.7 42 47.7 53.6 59.6 66 68.5 74.5 80.5 83.4 95.4 104 110 119

914.4 28.9 41.7 50.7 56.6 65.6 71.5 80.5 92.4 98.3 107 113 122 128 143 155 167 179

1066.8 41.7 56.6 72 83.4 92.3 101 116 131 143 152 164 173 182 203 221 238 256

1238.4 56.6 80.5 95 113 125 137 158 176 191 206 221 232 244 274 298 322 346

1371.6 71.5 101 125 143 161 175 203 229 247 268 286 304 322 358 390 423 453

1524 92.3 128 158 182 203 221 256 289 313 337 358 381 402 447 495 530 566
EM 1110-2-1913

30 Apr 2000

F-15

Table F-4b

Capacity of Corrugated Metal Pipe Culverts

Without Headwalls and With Outlet Submerged (outlet control-full flow) (Circular) (Metric Units)

Dia. m PER SECOND

In

m

3

Head on Pipe in m

0.003 0.006 0.008 0.011 0.014 0.017 0.023 0.028 0.034 0.040 0.045 0.051 0.057 0.071 0.085 0.099 0.113

0.305 0.3 0.43 0.53 0.61 0.67 0.73 0.85 0.94 1.04 1.13 1.22 1.28 1.34 1.52 1.64 1.77 1.88 Length = 6.10 m

0.381 0.52 0.73 0.88 1.04 1.16 1.25 1.46 1.61 1.77 1.92 2.07 2.16 2.29 2.56 2.8 3.02 3.35

0.457 0.79 1.1 1.34 1.58 1.74 1.89 2.19 2.44 2.68 2.9 3.05 3.35 3.35 3.96 4.27 4.57 4.88

0.533 1.10 1.55 1.89 2.19 2.44 2.68 3.05 3.35 3.66 3.96 4.27 4.57 4.88 5.49 5.79 6.4 6.71

0.610 1.49 2.07 2.56 2.93 3.35 3.66 4.27 4.57 5.18 5.49 5.79 6.1 6.4 7.32 7.92 8.53 9.14

0.686 1.89 2.68 3.35 3.66 4.27 4.57 5.49 6.1 6.4 7.01 7.62 7.92 8.53 9.45 10.36 10.79 11.89

0.762 2.38 3.35 4.27 4.88 5.18 5.79 6.7 7.62 8.23 8.84 9.75 10.06 10.7 11.89 12.8 14.02 14.94

0.914 3.66 4.88 6.1 7.01 7.92 8.53 10.06 11.28 12.19 13.11 14.02 14.94 15.85 17.37 19.2 20.72 21.95

1.067 4.88 7.01 8.53 9.77 10.79 11.89 13.72 15.54 16.76 18.29 19.5 20.73 21.64 24.07 26.21 28.35 30.48

1.219 6.71 9.14 11.28 13.11 14.63 15.84 18.29 20.73 22.56 24.38 25.9 27.42 28.65 32.31 35.66 38.1 40.84

1.372 8.53 11.89 14.63 16.76 18.59 20.42 23.72 26.52 29.52 31.09 33.22 35.36 36.88 41.45 45.41 48.77 52.12

1.524 10.36 14.63 17.98 20.73 23.16 25.30 24.26 32.61 35.97 38.4 40.89 3.28 45.72 50.9 55.47 60.04 64.0

Dia. m PER SECOND

In

m

3

Head on Pipe in m

0.003 0.006 0.008 0.011 0.014 0.017 0.023 0.028 0.034 0.040 0.045 0.051 0.057 0.071 0.085 0.099 0.113

0.305 0.26 0.34 0.43 0.49 0.55 0.61 0.70 0.76 0.85 0.91 0.97 1.04 1.1 1.22 1.34 1.46 1.55 Length = 12.19 m

0.381 0.43 0.58 0.73 0.82 0.94 1.04 1.19 1.31 1.46 1.58 1.68 1.8 1.89 2.10 2.32 2.5 2.68

0.457 0.64 0.91 1.13 1.31 1.46 1.58 1.83 2.07 2.26 2.44 2.62 2.74 2.93 3.35 3.66 3.96 4.27

0.533 0.91 1.31 .61 1.86 2.07 2.26 2.62 2.93 3.35 3.66 3.66 3.96 4.27 4.57 5.18 5.49 5.79

0.610 1.28 1.8 2.19 2.56 2.86 3.05 3.66 3.96 4.57 4.88 5.18 5.49 5.79 6.4 7.01 7.62 8.23

0.686 1.68 2.38 2.93 3.35 3.66 4.27 4.88 5.18 5.79 6.4 6.71 7.01 7.62 8.53 9.14 10.1 10.67

0.762 2.13 2.99 3.66 4.27 4.88 5.18 6.1 6.71 7.32 7.92 8.53 9.14 9.45 10.7 11.58 12.8 13.41

0.914 3.05 4.57 5.49 6.4 7.32 7.92 9.14 10.1 10.79 11.89 12.8 13.72 14.32 16.15 17.68 18.9 20.11

1.067 4.57 6.4 7.92 9.14 10.1 10.97 12.8 14.32 15.54 16.76 17.98 18.9 20.11 22.56 24.36 26.82 28.35

1.219 6.1 8.53 10.69 12.19 13.72 14.94 17.07 18.20 14.69 22.56 24.38 25.6 27.13 30.17 33.22 36.0 38.71

1.372 7.92 10.87 13.72 15.54 17.37 19.20 21.95 24.69 27.13 29.26 31.39 33.22 35.06 39.01 42.67 46.32 49.7

1.524 9.75 13.72 16.76 19.51 21.95 23.77 27.43 30.48 33.53 36.58 39.01 41.45 43.59 48.77 53.34 57.91 61.6

Dia. m PER SECOND

In

m

3

Head on Pipe in m

0.003 0.006 0.008 0.011 0.014 0.017 0.023 0.028 0.034 0.040 0.045 0.051 0.057 0.071 0.085 0.099 0.113

0.305 0.21 0.3 0.36 0.43 0.49 0.52 0.61 0.67 0.73 0.79 0.85 0.88 0.94 1.07 1.16 1.25 1.34 Length = 18.29 m

0.381 0.37 0.52 0.64 0.73 0.82 0.91 1.04 1.16 1.28 1.37 1.46 1.55 1.64 1.83 2.0 2.16 2.32

0.457 0.58 0.82 1.0 1.16 1.28 1.4 1.61 1.8 1.98 2.13 2.29 2.44 2.56 2.83 3.05 3.35 3.66

0.533 0.82 1.19 1.46 1.68 1.86 2.01 2.35 2.65 2.9 3.05 3.35 3.66 3.66 4.27 4.57 4.88 5.18

0.610 1.16 1.65 2.01 2.32 2.56 2.8 3.35 3.66 3.96 4.27 4.57 4.88 5.18 5.79 6.4 6.71 7.32

0.686 1.52 2.16 2.66 3.05 3.35 3.66 4.27 4.88 5.18 5.74 6.1 6.4 6.7 7.62 8.23 8.84 9.45

0.762 1.95 2.74 3.35 3.96 4.26 4.88 5.49 6.1 6.71 7.01 7.62 8.23 8.53 9.75 10.67 11.28 12.14

0.914 2.96 4.27 5.18 5.79 6.7 7.32 8.23 9.45 10.1 10.70 11.58 12.5 13.11 14.63 15.85 17.07 18.29

1.067 4.26 5.79 7.32 8.53 9.45 10.36 11.89 13.41 14.6 15.54 16.76 17.68 18.59 20.73 22.56 24.38 26.21

1.219 5.79 8.23 9.75 11.58 12.8 14.02 16.15 17.98 19.51 14.63 22.56 23.77 25.0 28.04 30.48 32.92 35.36

1.372 7.32 10.36 12.8 14.63 16.45 17.98 20.73 23.47 25.3 27.43 29.26 31.09 32.92 36.58 39.93 43.28 46.33

1.524 9.44 13.11 16.15 18.59 20.73 22.56 26.21 29.57 32.0 34.44 36.58 39.01 41.15 45.72 50.6 54.25 57.91
EM 1110-2-1913 

30 Apr 2000 

Figure F-5. Prefabricated rubber pipe stoppers for outlet opening of a manhole 

... " .. ..,... .... ~ 

liCUNI-BAU.. plU& 

Figure F-6. Prefabricated rubber pipe stoppers for outlet opening of a manhole 

F-16 
.. 

to_ 

"b 

·-· 

-~ 

't:> 

.. 

6 -t>.~ 

' .. 

P· .:~ .~ L> 0.: -~ -~· . • . .._·.....;·--~~--:-. ~0--_,_, 

•• - Q> ~ 

p 

-6 

- ·~ 

I> 0 

Figure F-7. Typical manhole 

~ 

EM 1110-2-1913 

30 Apr 2000 

construction equipment. However, if the flood barrier consists of poly and sandbags having a minimum top 

width and limited base width, raising the barrier is very time consuming and labor intensive. Experience has 

shown that sandbag barriers over 0.91 m (3 ft) in height do not perform well for prolonged floods; 

underseepage becomes a real problem and failures have occurred as the water approaches the top of 

protection. 

c. Seepage. Seepage is percolation of water through or under a levee, generally appearing first at the 

landside toe. Seepage through the levee is applicable only to a relatively pervious section. Seepage, as such, 

is generally not a problem unless (1) the landward levee slope becomes saturated over a large area; 

(2) seepage water is carrying material from the levee; or (3) pumping capacity is exceeded. Seepage which 

causes severe sand boils and piping is covered below. Seepage is difficult to eliminate, and attempts to do 

so may create a much more severe condition. Pumping of seepage should be held to a minimum, based on 

the maximum ponding elevation without damages. Seepage should be permitted if no apparent ill-effects 

are observed, and if adequate pumping capacity is available. If seepage causes sloughing of the landward 

slope, it should be flattened to 1 Von 4H or flatter. Material for flattening should be at least as pervious as 

the embankment material. 

F-17 
EM 1110-2-1913 

30 Apr 2000 

o' I 

.. 

. . . . , . 

. . . . , ... 

... 

----SUCTION LINE TO PUMP 

PIPE PLUG MADE FROM 50.Bx101.6= 

(2x4in) AND 25.4=(1in) STOCK 

(BOARDS OR PLYWOOD) 

457.2mm(1Bin)SEWER PIPE 

TO RIVER .... 

. . . . . ~ . . ' .... •· . . . •.p.-·: • .. ,. .•. '···~~- •. ·~.·-

~I· . . ·•, • '• •,. & 

... , .. . , . . . . ,. . . . .. . . . 

Figure F-8. Adapting manhole for use as emergency pumping station 

d. Sand boils. 

( 1) Description. A sand boil is the rupture of the top foundation stratum landward of a levee caused 

by excess hydrostatic head in the substratum. Even when a levee is properly constructed and of such mass 

to resist the destructive action of floodwater, water may seep through a sand or gravel stratum under the 

levee and break through the ground surface on the lands ide in the form of bubbling springs. When such 

eruptions occur, a stream of water bursts through the ground surface, carrying with it a volume of sand or 

silt which is distributed around the hole. A sand boil may eventually discharge relatively clear water, or the 

discharge may contain quantities of sand and silt, depending upon the magnitude of pressure and the size of 

the boil. They usually occur within 3.05 m to 91.4 m (10 to 300ft) from the landside toe of the levee, and 

in some instances have occurred up to 304.8 m (1,000 ft) away. 

(2) Destructive action. Sand boils can produce three distinctly different effects on a levee, depending 

upon the condition of flow under the levee. 

F-18 
PLAN 

SCALE: 1m.m(3/32in)= 10. 7mm( lin) 

Figure F-9. Sealing top of manhole with wood 

EM 1110-2-1913 

30 Apr 2000 

LUMBER OR 

(a) Piping flow. Piping is the active erosion of subsurface material as a result of substratum pressure 

and concentration of seepage in the localized channels. The flow breaks out at the landside toe in the form 

of one or more large sand boils. Unless checked, this flow causes the development of a cavern under the 

levee, resulting in the subsidence of the levee and possible overtopping. This case can be easily recognized 

by the slumping of the levee crown. 

(b) Non-piping flow. In this case, the water flows under pressure beneath the levee without following 

a defined path, as in the case above. This flow results in one or more boils outcropping at or near the 

landside toe. The flow from these boils tends to undercut and ravel the landside toe, resulting in sloughing 

F-19 
EM 1110-2-1913 

30 Apr 2000 

.· .' "". 

' i 

. · 

p • 

. .. . . . . . . . . . . • I·; P· 

' · .

. ,. p , . 

SECTION A A 

v. 

-.,-----....... ...... '· 

• Jl 

. . r . . . . . ·.. "' 

. 

\ \ 

p 

. p • •• 

• I> • . . 

P. 

S€CTION 8 B 

Figure F-10. Treatment of bottom of manhole 

F-20 

p- • • • 

. , . . . :. . . . . . .... . . . . . . " . .. 

. . . .. ~ 
NOTE: 

IF 90" ELBOW IS 

:/.·. 

·4 

I. . 

. 

. ~ ..... '.: 

~ ... (. 

(i 

AVAILABLE 101.6x101.6mm -----~ (4x4in) NOT REQUIRED . r1 

EM 1110-2-1913 

30 Apr 2000 

SUCTION LINE TO PUMP 

r--+--''-+--PLUG OUTLET 

PIPE WITH 

SAND BAGS 

TO RIVER 

. ~. •( • ~ • 6 • t.. ... -1 

-~ . ... . . . ... "' . . 

: J. , .•. 4. ·.• < . ' • ( 4 ,· . t. : .... 

101.6x101.6=(4x4in) 

OR 2-50.8x101.6= 

{2x4in) 

Figure F-11. Suction line to pump from manhole 

. .. 

t,. • 

"6 

<· ..... ,.!. l. ... . . . .d.. :I> /. . 

SECTION B-B 

. .. · t .. 

. ~~ 

F-21 
EM 1110-2-1913

30 Apr 2000

F-22

of the landward slope. Evidence of this type of failure is found in undercutting and ravelling at the landside

toe.

(c) Saturating flow. In this case, numerous small boils, many of which are scarcely noticeable, outcrop

at or near the landside toe. While no boil may appear to be dangerous in itself, the consequence of the group

of boils may cause flotation (“quickness”) of the soil, thereby reducing the shearing strength of the material

at the toe, where maximum shearing stress occurs, to such an extent that failure of the slope through sliding

may result.

(3) Combating sand boils. All sand boils should be watched closely, especially those within 30.5 m

(100 ft) of the toe of the levee. All boils should be conspicuously marked with flagging so that patrols can

locate them without difficulty and observe changes in their condition. A sand boil which discharges clear

water in a steady flow is usually not dangerous to the safety of the levee. However, if the flow of water

increases and the sand boil begins to discharge material, corrective action should be undertaken immediately.

The accepted method of treating sand boils is to construct a ring of sandbags around the boil, building up

a head of water within the ring sufficient to check the velocity of flow, thereby preventing further movement

of sand and silt. See Figure F-12 for technique in ringing a boil. Actual conditions at each sand boil will

determine the exact dimensions of the ring. The diameter and height of the ring depend on the size of the

boil and the flow of water from it. In general, the following considerations should control: (1) the base

width of the sandbag section should be no less than 1 1/2 times the contemplated height; (2) encompass weak

soils near the boil within the ring of sandbags, thereby preventing a potential failure later; and (3) the ring

should be of sufficient size to permit sacking operations to keep ahead of the flow of water. The height of

the ring should only be that necessary to stop movement of soil, and not as high as to completely eliminate

seepage. The practice of carrying the ring to the river elevation is not necessary and may be dangerous in

high stages. If seepage flow is completely stopped, a new boil will likely develop beyond the ring; this boil

could then suddenly erupt and cause considerable damage. Where many boils are found to exist in a given

area, a ring levee of sandbags should be constructed around the entire area and, if necessary, water should

be pumped into the area to provide sufficient weight to counterbalance the upward pressure.

e. Erosion. Erosion of the riverside slope is one of the most severe problems which will be encountered

during a flood fight. Emergency operations to control erosion have been presented earlier under “Slope

Protection.”

f. Storm and sanitary sewers. 

(1) Problems. Existing sewers in the protected area may cause problems because of seepage into the

lines, leakage through blocked outlets to the river, manhole pumps not spread throughout the sewer system,

and old or abandoned sewer locations which were not found during preflood preparations. Any of these

conditions can cause high pressures in parts of the sewer system and lead to the collapse of lines at weak

points and blowing off of manhole covers.

(2) Solutions. During the flood fight, continued surveillance of possible sewer problems is necessary.

If the water level in a manhole approaches the top, additional pumps in manholes may alleviate the problem.

In sanitary sewers, additional pumping may be required at various locations in the system to provide

continued service to the homes in the protected area. When pumps are not available, manholes may have to

be ringed with sandbags or by some other method which allows the water to head up above the top of the

manhole. To eliminate the problem of disposing of this leakage from manholes the ring dike would have

to be raised above the river water surface elevation. This creates high pressures on the sewer and should not

be done. As with sand boils, it is best to ring the manhole part way to reduce the head and dispose of what

leakage occurs. Directly weighing down manhole covers with sandbags or other-items is not recommended
L"ANOSIOE 

NOTE 

Bottom to b~ no less than 

Tie into levee if boil is near toe 

PLAN 

Figure F-12. Ringing sand boils 

El-EVATION 

EM 1110-2-1913 

30 Apr 2000 

RIVERSIDE 

SECTIONAL ELEVATION 

NOTE• 

En!ire base to· be cleared 

of debris and scarified. 

Loos·e earth to be used belw«n 

all socks. 

All joints to be staggered. 

where high heads are possible. A 30-kPa (10-ft) head on a manhole cover 0.61 m (2ft) in diameter would 

exert a force of9.16 kN (2,060 lb-force). Thus, a counterweight of more than a ton would have to be placed 

directly on the cover. 

F-23 
EM 1110-2-1913

30 Apr 2000

F-24

g. Slope stability on weak foundations. In areas that have very weak foundation soils it may not be

possible to construct full height flood barriers in preferred locations because of inadequate slope stability.

However, if flood waters are slow to rise and fall, it is possible to use the rising floodwater as a restraining

load on the riverside slope to meet stability criteria. This is usually used for closure structures or for staged

construction where the flood barrier is only constructed after the river reaches an established level. This

procedure would also require that the flood barrier be removed before the river went down below the

established level. 

h. Causes of levee failures. In addition to the problems covered above, the following conditions could

contribute to failure:

(1) Joining of a levee to a solid wall, such as concrete or piling. Flood barriers consisting of sandbags

greater than 0.91 m (3 ft) in height and joining a solid wall have performed poorly in the past due to

excessive underseepage and instability of the sandbag prism. 

(2) Structures projecting from the riverside of levee.

(3) A utility line crossing or a drain pipe through the fill.

(4) Tops of stoplogs on roads or railroad tracks at a lower elevation than the levee.

(5) Joining a sandbag barrier to a levee. Seepage problems at the juncture with the levee fill have caused

very poor performance. 
EM 1110-2-1913

30 Apr 2000

G-1

Appendix G

Use of Soil Cement for Levee Protection

G-1. Purpose

The purpose of this appendix is to provide guidance on the design and construction of soil cement slope

protection for levees and embankments. This includes soil cement, materials, mixture proportioning, design

of slope protection, construction, quality control, inspection, and testing.

G-2. General Considerations

a. Soil Cement. The American Concrete Institute defines soil cement as a mixture of soil and measured

amounts of portland cement and water compacted to a high density. Soil cement can be further defined as

a material produced by blending, compacting, and curing a mixture of soil/aggregate, portland cement,

possibly admixtures including pozzolans, and water to form a hardened material with specific engineering

properties. 

b. Application. Although riprap has historically been used for slope protection for levees, dams,

channels, etc.,there are situations when suitable rock is not available within economical haul distances and

soil cement slope protection may be the most economical and appropriate selection. 

c. History. The use of soil cement for slope protection has increased considerably over the past

30 years. The main focus of this effort has come from the U.S. Bureau of Reclamation (USBR) in the

construction of dams. The first experimental use of soil-cement for slope protection was a test section

constructed by USBR at Bonny reservoir in eastern Colorado in 1951. Observation of the performance of

this test section for the first 10-year period of service indicated excellent performance of the soil cement

which was subject to harsh wave action and repeated cycles of freezing and thawing. This lead to the

conclusion that use of soil cement for slope protection was feasible based on both economical and service

life considerations. 

d. Economics. The decision to use soil cement instead of riprap is primarily an economic one.

However, not every soil is suitable for producing soil cement for this application. Therefore, the designer

must compare the availability of suitable soil for soil cement versus the availability of suitable rock for

riprap. The designer must prepare a cost analysis in arriving at a decision. Factors that must be considered

for soil cement include cost of cement, location of suitable soil, special processing requirements if needed,

haul distance, dimensions and configuration of the slope protection and mixing and placement methods. For

riprap, considerations include cost and availability of rock, size and availability of rock, haul distance,

special processing requirements, configuration of placement and placement effort. Cost estimates of the

alternative methods provide the basis for the economic analysis. 

G-3. Materials

a. Soils. In general most soils of medium to low plasticity (Plasticity Index (PI) equal to or less than

12) can be used for soil cement. However for levee protection, better quality granular materials are

recommended since the soil cement may be subjected to repeated cycles of wetting-drying, freezing-thawing

and wave action. It is recommended that the soil should not contain any material retained on a 2-in.

(50.8 mm) sieve, nor more than 45 percent retained on a No. 4 (4.75-mm) sieve, nor more than 35 percent

or less than 5 percent passing the No. 200 (0.075-mm) sieve. The PI should be equal to or less than 12 and
EM 1110-2-1913

30 Apr 2000

G-2

the organics content should be less than 2 percent. It should be noted that clay balls (nodules of clay and silt

mixed with sand materials) can form when the PI is as low as 8. Clay balls can be detrimental when soil

cement is exposed to weathering and the clay tends to wash out leaving voids in the soil cement structure.

Clay balls greater than 25.4 mm (1-in.) should be removed and the minus 25.4-mm (1-in.) clay ball content

should be limited to 10 percent. For economic reasons, the soil should be obtained from a borrow area close

to the construction site. Samples from borrow sources must be evaluated for gradation and PI. If in-situ

soils are not suitable it may be necessary to blend materials from several borrow sources.

b. Cement. Portland cements meeting specifications of ASTM C 150 are suitable. Generally, Type I

is used for soil cement. However, soil cement can be subject to sulfate attack and it is the lime in the cement

that is involved in the reaction. Therefore, sulfate bearing soils or water should be avoided. There is no

definitive test to determine the threshold sulfate content at which a soil is deemed to be potentially reactive

however experience has shown that soils with a sulfate content as low as low as 0.3 percent have developed

reactions. If exposure to sulfates is not avoidable, Type II cement is recommended. Use of fly ash as a

replacement for portland cement is not recommended in that experience has indicated that fly ash reduces

early age compressive strength and durability when used in soil cement.

c. Water. Most water is acceptable for soil-cement. The primary requirement is that water should be

free from substances deleterious to hardening of the soil cement. Specifically, water should be free from

objectionable quantities of organic matter, alkali, salts, and other impurities. Presence of soluble sulfates

should be of concern. Seawater has been used satisfactorily. The presence of chlorides in seawater may

increase early strength. The quality of water for soil cement should be similar to that used for mixing

concrete. Guidance on water quality may be found in Corps of Engineers CRD-C 400. 

G-4. Proportioning Soil Cement Mixtures

a. General. One of the key factors that accounts for the successful use of soil cement is careful predetermination of engineering control factors in the laboratory and their application during construction. The

composition of soils varies considerably and these variations affect the manner in which the soils react when

combined with portland cement and water. The way a given soil reacts with cement is determined by simple

laboratory tests conducted on mixtures of cement, soil, and water. These tests determine three fundamental

requirements for soil cement: the minimum cement content needed to harden the soil adequately; the proper

moisture content; and the density to which the soil cement must be compacted. Generally, the procedure to

determine the mixture cement content consists of the following steps: soil classification test to determine

an appropriate soil type; moisture density tests at a selected initial cement content to determine target density

and water content values; durability tests at a range of cement content values including the initial cement

content; unconfined compressive strength tests; and selection of final cement content based on test results.

b. Selection of soils. The design of a soil cement mixture begins with selection of a suitable soil type,

The objective is to select a soil that can be stabilized with the minimum cement content and that will be

suitably durable for the range of service conditions to which it will be subjected. Guidance on specifications

for grading and plasticity of soils were given previously. Generally, soil cement made with granular

materials requires less cement than soil cement made with sands and fine grained soils. The latter materials

are also less durable. If the soils available in the immediate area of construction do not meet desired

specifications it may be necessary to blend several soil types to obtain the desired characteristics. However,

before blending is specified, the increased costs of processing and monitoring should be compared to the

increased cost of additional cement required for the natural material. Occasionally the designer may encounter soils that are unreactive or are marginally reactive requiring apparently excessive amounts of cement.

Often such soils contain acidic organic materials that affect the reaction.
EM 1110-2-1913

30 Apr 2000

G-3

c. Cement content general. A series of laboratory tests must be conducted to determine cement content.

Inherent in these tests is also the determination of design soil density and water content. If the project is

large and more than one candidate soil is available, it may be appropriate to conduct the entire series of tests

on each soil to determine the most economical mixture for the project. Also, if several borrow areas having

significantly different soils are involved it may be necessary to conduct laboratory tests on soil from each

borrow area to determine the appropriate mixture for each soil. The tests involved in this process include:

moisture density tests (ASTM D 558) to determine initial design density and moisture content based on a

selected initial cement content and durability tests (ASTM D 559 and D560) to determine resistance to

repeated cycles of wetting and drying and freezing and thawing which might be expected under natural

climatic changes. Compressive strength tests (ASTM D 1632 and D 1633) should be conducted on

laboratory prepared specimens. Tests are conducted at several cement content values and the final cement

content is that which produces the required durability and strength at the lowest practical cement content.

Strength and rate of strength gain are important factors in performance of the soil cement. Adequate strength

is required to resist forces of wave action and uplift pressures.

d. Moisture density tests. Moisture density tests are conducted to determine values of density and water

content for molding soil cement durability samples and for field control of compaction during construction.

The cement content for moisture density tests is selected based on soil classification. Soils should be

classified following procedures indicated in ASTM D 2487, Standard Test Method of Classification of Soils

for Engineering Purposes. Initial cement contents for different soil classifications are indicated in Table G-1.

The appropriate value of cement content for moisture-density tests may be selected from this table. Only

coarse grained soil symbols are shown as these are the soil types preferred for soil cement for slope

protection. Representative soil samples should be collected and moisture density tests conducted following

procedures indicated in ASTM D 558, Standard Test Methods for Moisture Density Relations of Soil

Cement Mixtures. Results of the tests are plotted as shown in Figure G-1 from which values of dry density

and moisture content are selected for molding durability specimens. The dry density may be the maximum

or a percentage of the maximum density indicated on the plot. Past experience has indicated that a minimum

density of 98 percent of the maximum ASTM D 558 density is adequate. The water content is the value

associated with the selected density. The water content at maximum dry density is termed the “Optimum

Water Content” (OWC).

Table G-1

Initial Cement Content for Moisture Density Tests

Soil Classification Initial Cement Content

(ASTM D 2487) (percent dry weight of soil)

GW, GP SW, SP 7

GM, SM 8

GC, SC 9

SP 11

e. Durability tests. Two types of durability tests are conducted: ASTM D 559, Standard Test Methods

for Wetting and Drying of Compacted Soil Cement Mixtures and ASTM D 560, Standard Test Methods of

Freezing and Thawing of Compacted Soil Cement Mixtures. These tests were designed to reproduce in the

laboratory the moisture and temperature changes expected under field conditions. These tests measure the

effect of internal volume changes produced by changes in moisture and temperature. From these tests the

minimum cement content required to produce a structural material that will resist volume changes produced

by changes in moisture and temperature can be determined. Wet dry tests should be conducted in all

geographic areas. Freeze-thaw tests should be conducted in all areas that experience at least one cycle of

freezing and thawing per year since levee protection is expected to be subjected to this condition over a long
EM 1110-2-1913 

30 Apr 2000 

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Moisture content·- percent 

Figure G-1. Typical moisture-density curve 

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period of time. Ifthere is absolutely no expectancy of freeze thaw cycles in the geographic area this test may 

be omitted. Each type oftest consists of twelve two-day cycles ofwetting/drying or freezing/thawing as 

appropriate and thus requires 24 days to complete. 

For each type of test, duplicate specimens of soil cement should be prepared at cement contents equal to 

the cement content used for the moisture density test and at cement contents 2 percent above and 2 percent 

below that used for the moisture density test. For example, if the cement content for moisture density tests 

is 7 percent, samples for durability tests should be molded at 5, 7, and 9 percent cement. Ideally, a moisturedensity test should be conducted for each cement content to determine maximum density and optimum 

moisture water content for that particular design mixture since these values vary with cement content. If this 

is not possible the density and moisture content determined from the initial tests may be used. 

After each cycle (of either the wet-dry or freeze-thaw) the specimen is scrubbed with a wire brush to 

remove soil cement that becomes loosened or unbonded as a result of exposure to the test environment. 

After the twelve cycles are completed, the total weight loss is calculated and this value is compared to 

established criteria. The weight loss criteria are shown in Table G-2. Assuming both tests are conducted, 

specimens must meet both criteria. If specimens do not meet both criteria, adjustments must be made in the 

soil gradation and/or cement content based on engineering judgment and at least one set of tests should be 

rerun. Adjustments may include blending of aggregate to the soil and/or increasing the cement content. 

Table G-2 

Durability Test Weight Loss Criteria 

Type of Durability Test 

Wet Dry (ASTM D 558) 

Freeze Thaw (ASTM D 559) 

G-4 

Maximum Weight Loss 

After 12 Cycles (percent) 

6 

8 
EM 1110-2-1913

30 Apr 2000

G-5

f. Unconfined compressive strength tests. The next step is to conduct unconfined compressive strength

tests (ASTM D 1632 Making and Curing Soil Cement Compression and Flexure Test Specimens in the

Laboratory, and ASTM D 1633 Compressive Strength of Molded Soil Cement Cylinders). Strength of the

soil cement is important in slope protection to provide resistance to wave action and uplift pressures. In fact,

strength may be the determining factor in arriving at the final design cement content. Experience has shown

that often the cement content of specimens meeting compressive strength criteria is higher than that

necessary to meet durability requirements. The cement content for specimens for initial compressive

strength tests will be the minimum cement content of the specimens that met durability criteria. The water

content and dry density will be that used to mold durability specimens. Duplicate specimens should be prepared and tested as indicated according to the ASTM procedures previously indicated. Minimum

compressive strength criteria are indicated in Table G-3. If strengths of specimens tested at the initial cement

content do not meet minimum criteria, then the cement content should be increased in two percentage point

increments and compressive strength tests rerun until criteria are met or it is determined that another mix

design approach must be undertaken. If time constraints do not permit conduct of unconfined compressive

strength tests until the durability tests have been completed, it may be necessary to conduct these tests

simultaneously. If this is necessary, the unconfined compressive strength tests should be conducted on

specimens prepared at all of the cement contents used in the durability tests. This approach obviously

requires that many more specimens be prepared and tested however the savings in time may be more

economical than conducting the tests in sequence.

Table G-3

Unconfined Compressive Strength Criteria (ASTM D 1633)

Cure Time (days) Minimum Compressive Strength, kPa (psi)

 7 4138 (600)

 28 6034 (875)

g. Final cement content. The final cement content is the minimum cement content used in specimens that

met or exceeded both the durability and compressive strength criteria. Some designers have added one or

two percentage points to this cement content to account for variability in the field cement content where the

proposed method of construction is mixed in place. Where central plant mix procedures are used control of

cement content is generally accurate.

G-5. Design of Slope Protection

a. General considerations. Design of slope protection with soil cement is somewhat similar to design

with riprap in that protection must be provided against erosional forces from wave action and stream

currents. Soil cement slope protection can be provided in two configurations: stair step or plating. In stair

step slope protection the soil cement is usually placed in successive horizontal layers adjacent to the slope.

This method is preferred for slopes exposed to moderate to severe wave action or debris carrying, rapidly

flowing water. The plating method consists of placing one or more layers of soil cement parallel to, i.e.,

directly on, the slope. This method is used where less severe exposure is expected.

b. Stair step method. The stair step method consists of constructing successive horizontal lifts of

compacted soil cement up the slope to the desired height of protection (Figure G-2). Each successive lift is

set back by an amount equal to the compacted lift thickness times the cotangent of the slope which results

in a stair step pattern approximately parallel to the embankment slope. Layer thickness can be from 152.4

to 304.8 mm (6 to 12 in.) depending on the type of compaction equipment used. Historically, stair step construction has been accomplished with 152.4 mm (6 in.) compacted lifts. However, thicker lifts require less
EM 1110-2-1913 

30 Apr 2000 

\Max. water 

152.4-304.8mm ~\level 

(6-12in.)~ 

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Figure G-2. Stair-step method of slope protection 

2.4m(8') .. 1 

~~ .61m(21 

~ ~ i. Embankment 

~ 3 

Soil-cement 

NOT TO SCALE 

construction effort and result in fewer bond surfaces. The disadvantage of thicker lifts is more loss of soil 

cement at the exposed edge during construction and additional effort is required to obtain desired density 

throughout the lift. The width of the layer also is a function of type and size of construction equipment. 

Experience has shown that a layer width of about 2.4 m (8 ft) is generally most convenient. Since stair step 

protection is indicated for more severe environmental conditions, a thicker covering over the slope is 

generally specified. Experience has indicated that the total thickness of soil cement measured perpendicular 

to the slope should be 0.61 to 0.92 m (2 to 3 ft). The relationships between slope, facing thickness, layer 

thickness and horizontal layer width are shown in Figure G-3. 

c. Plating method. The plating method consists oflifts placed parallel to, i.e., directly on, the slope and 

is used in areas where a thinner facing is required. Generally two 152.4 mm (6-in.) lifts or one 203.2-mm 

(8-in.) lift are used for plating. One of the primary considerations in plating protection is providing 

resistance to high flow especially with debris. To date there are no definitive design criteria to determine 

lift thickness based on abrasion, however, since the plating method is applicable for areas subjected to less 

harsh environments, experience has shown 304.8 mm (12 in.) of protection is adequate. In the plating 

method, lifts can be constructed so that the resulting construction joints are either parallel or perpendicular 

to the flow of water. If placement and compaction of the soil cement are up and down the slope, the 

construction joint will be perpendicular to the water flow. If placement and compaction are along the slope, 

the construction joints will be parallel to the flow of water. For the plating method of construction, the slope 

should be 3H:IV or flatter in order to properly spread and compact the soil cement. Construction on steeper 

slopes may be accomplished if special compaction equipment is used. 

d. Freeboard and wave runup. Freeboard is the vertical distance from the top of the levee to the water 

surface. The freeboard should be sufficient to prevent waves from overtopping the levee or damaging the 

crest. Slope protection should be provided in the freeboard area to prevent erosion. When a wave contacts 

the face of the levee it will run up the slope. Wave run up is the vertical height above the still-water level 

to which the uprush from a wave will rise on a structure. It is not the distance measured along the inclined 

surface. To calculate the wave run up for soil cement slope protection, the wave run up value based on riprap 

protection is first calculated and this value is multiplied by a factor based on the type and condition of the 

soil cement slope protection. For calculation of wave run up for riprap, designers should consult the 

following references: EM 1110-2-1614, Design of Coastal Revetments, Seawall, and Bulkheads, dated 

30 June 1995; and the Automated Coastal Engineering System (ACES) computer program. For stair step 

construction with vertical faces on the layers the run up factor 1.2. Where the faces have become rounded 

due to weathering and erosion the run up factor is 1.3. For plating slope protection the run up factor is 1.4. 

G-6 
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Figure G-3. Relationship of slope, facing thickness, layer thickness, and 

horizontal layer width 

EM 1110-2-1913 

30 Apr 2000 

e. Transitions. Transitions between soil cement and earth or other structures should be addressed. Tiebacks similar to riprap emplacements can be designed to avoid flanking of the structure. An alternative is 

to use a riprap section at either end of the soil cement structure. Where soil cement joins other structures 

and compaction is difficult it may be appropriate to use lean concrete. 

f Drainage and seepage. Although no distress to soil cement slope protection due to rapid drawdown 

has been reported and the current thinking is that drainage is not required unless severe drawn down is 

anticipated, the designer should be aware of the preventative measures can be used. Three concepts are 

presented. One is design of the levee so that the least permeable zone is adjacent to the soil cement. This 

will provide protection against build up of excess pore water pressure. A second method is to determine that 

the weight of the facing is sufficient to resist uplift pressures. Here, there may be some pore pressure relief 

through shrinkage cracks in the soil cement. Obviously, some estimate must be made of the gross hydraulic 

conductivity of the soil cement. A third measure is to provide deliberate drainage conduits through the soil 

cement. This approach was used by the Bureau of Reclamation at Merrit Dam. Three rows of 76.2- to 

G-7 
EM 1110-2-1913

30 Apr 2000

G-8

127-mm- (3- to 5-in.-) diameter weep holes were drilled into the facing after construction and included

118 holes on 3.05 m (10 ft) centers. In such arrangements, a filter is placed in the area of weep hole before

soil cement construction.

G-6. Construction

a. General. There are two general methods in common use for constructing soil-cement: mixed-in-place

and central mix plant. Regardless of the equipment and methods used the goal is to obtain thoroughly mixed

and adequately compacted and cured soil-cement. The central mix method involves mixing of a borrow

material with cement and water, at a centrally located plant. The mixture is then transported to the site. The

mixed-in-place method involves mixing of cement and water with the in-place soil at the site, and is

infrequently used for embankment soil cement applications.

The most common method of soil-cement construction for bank protection is central mix plant. For soil--

cement used as bank protection, particularly where banks experience higher flow velocity forces, adequate

strength and durability, and consistent quality, are primary requirements. It is harder to achieve these

objectives using mixed-in-place construction than central mix plant.

Two methods are used for placement and compaction of soil cement for embankments: stair step or

plating. Design for these methods was discussed earlier in this document. The stair step method is the

predominant method used, although construction using both methods is discussed in the subsequent sections

on spreading and compaction.

Soil cement should not be mixed or placed when the soil or subgrade is frozen or when the air temperature

is below 9EC (45EF). Specifications may allow soil cement construction to proceed if the air temperature

is at least 4EC (40EF) and rising. Hot weather poses a few problems for soil cement construction, requiring

sometimes additional moisture application to the materials, faster placement and compaction operations, and

additional curing effort.

b. Central mix plant construction. There are two basic types of central mix plants: pugmill mixers

either continuous or batch type, and rotary drum mixers (also a batch type of mixer). The uniformity of soil

cement produced by these plant types is generally roughly equivalent, provided they have been properly

calibrated. Continuous mix pugmill plants have higher production rates, while batch plants are often easier

to calibrate, and require less frequent calibration. Batch-type pugmill plants have been used, but

infrequently. Production rates between 76.4 and 152.9 m (100 and 200 cu yd/hr) are common for stair-step 3

soil cement construction. The basic steps of central mix plant construction of soil cement are: subgrade

preparation, borrow materials, mixing, transporting, spreading, compacting, bonding lifts, finishing,

construction joints, and curing and protection.

(1) Subgrade preparation. A firm subgrade is necessary to compact the overlying layers of soil cement

to the required density. The subgrade is prepared by removing and replacing, or stabilizing, soft or wet

areas, removing deleterious materials, and grading and compaction to construction plans and specifications.

Most overly wet subgrade areas can be corrected by aerating and recompacting, or some type of chemical

stabilization. Dry subgrades are surface moistened immediately prior to soil-cement placement.

(2) Borrow materials. Soil borrow sources are usually near the construction site and may consist

partially or wholly of excavated bed and/or bank material. Native borrow materials are naturally variable

in composition. Excavation, blending and stockpiling methods for borrow material should be selected to

minimize this variation, and produce as consistent a material as possible. Horizontally stratified soil layers

can be blended by deep excavation using full face cuts, insuring all layers are cut with each equipment pass.
EM 1110-2-1913

30 Apr 2000

G-9

If materials vary laterally across the borrow areas, loads from different locations should be blended in a

systematic fashion. Further blending can also be done as materials are brought to the plant stockpile area.

Alternating the loads from different parts of the plant stockpiles, or even using a front-end loader to take a

vertical cut of the stockpiles, also helps blend materials as they are fed to the mixing plant.

Screening the borrow material through a 25-mm (1-in.) to 38.1-mm (1-1/2-in.) mesh at the pit or at the

plant can help remove oversize clay balls and other oversize materials. Selective excavation may be

necessary to avoid excessive clay balls or clay content in the borrow area.

Stockpiles should be separated from each other and all plant equipment by at least 15.2 m (50 ft). Where

the soil contains coarse aggregate, stockpiling is done in layers to minimize segregation.

(3) Mixing. Central mixing plants with rated capacities of 227 to 907 metric tons (250 to 1,000 tons)

per hour (about 95.56 to 382.3 m (125 to 500 cu yd)) are used commonly. Special blending requirements 3

may require several stockpiles and separate storage feeder bins. Prior to mixing and placing, it is necessary

to measure the quantities and proportions of material supplied by the plant. The plant should be accurately

calibrated.

(a) Pugmill mixers. The most common continuous mixing plants contain a twin shaft pugmill.

Figure G-4 shows a diagram of a typical pugmill central mix plant. USBR recommends a twin-shaft pugmill

with a rated capacity of at least 152.9 m (200 cu yd)/hr. A pugmill mixing chamber contains twin shafts 3

rotating in opposite directions, with paddles (see Figure G-5) that force mix the soil cement and move it

through the chamber by the pitch of the paddles. Material feeds (by adjusting gate openings and belt speed)

and pugmill features (such as pugmill tilt and paddle pitch) may be adjusted to optimize the mixing actions

and production. Thoroughness of blending is partly determined by the length of mixing time. A mixing time

of 30 sec is commonly specified, although shorter times have also been shown to be adequate, depending

on the mixer efficiency.

Batch type pugmill mixers, where the materials are delivered to a pugmill mixer in a discrete batch rather

than as a continuous ribbon of material, can provide effective mixing of soil cement, but are seldom used,

largely due to lower production capacity and lack of availability.

(b) Rotary drum mixers. Although rotary drum (also called tilt drum) mixers are sometimes used, they

are generally lower in production capacity than pugmill mixers. These plants are typically converted central

mix concrete plants, and function in the same manner. Mixing times for these plants are typically about

60 sec.

(4) Transporting. Haul trucks can be of the end or bottom dump variety, although many types are used.

Where conditions are extremely hot and/or windy or where sudden showers are a possibility, soil cement

should be protected by using canvas covers on haul vehicles. Equipment should be clean. The elapsed time

between mixing and compacting should be kept to a minimum. Sixty minutes is usually the maximum.

Therefore, most specifications require haul times to be kept below a maximum of thirty minutes.

In stair step construction, temporary ramps are constructed at intervals along the bank to enable trucks

to reach the layer to be placed. These temporary ramps should have a minimum 0.457 m (18-in.) thickness

of material to protect the edge of the previous lift from truck traffic. There is also a requirement, where

streambeds are dry, for ramps to be spaced to allow egress from the channel in case of a flood. These are

constructed at 45E angles, with a minimum of 0.61 m (2 ft) of cover over the soil cement, and spaced about

91.4 to 121.9 m (300 to 400 ft) apart.
EM 1110-2-1913 

30 Apr 2000 

CEMENT STORAGE SILO 

WATER METER 

~ 1 

STORAGE HOPPER 

RETAINING WALL 

. . .. · . ·... . 

VANE FEEDER 

SOIL FEED 

" I 

CONVEYOR BELT 

NOT TO SCALE 

Figure G-4. Typical pug mill central plant 

Figure G-5. Mixing paddles of a twin-shaft, continuousFigure G-6 shows a typical step-construction 

sequence. Frequently time and cost savings have 

been realized by using conveyor systems to deliver 

the soil cement to the spreader. This removes the 

necessity for ramp construction and truck 

maneuvering and provides a cleaner end product. 

Narrower layers and plating applications can also 

be placed using a conveyor system. The soil 

cement can be delivered from above or below 

directly to a spreader box. 

(5) Spreading. Soil cement must be spread in 

a manner that will provide a compacted layer of 

uniform thickness and density, conforming to the 

design grade and cross section. 

flow central mixing plant (a) Stair step method. There are a wide 

variety of spreading devices and methods for stair 

step construction. One of the most common is the spreader box attached to a dozer or grader. An 

G-10 
PNEUMATIC 

TIRED ROLLER 

SHEEPSFOOT 

ROLLER 

Figure G-6. Typical construction sequence 

SPREADER 

EM 1110-2-1913 

30 Apr 2000 

alternate method is to place material in windrows to be spread by a grader. Care must be taken with the 

windrow operation not to over manipulate the material which may cause separation and premature drying. 

Layers are spread 15 to 30 percent greater than the required compacted thickness. Experimentation may be 

necessary to determine the appropriate spread thickness since different combinations of equipment and soil 

type may produce different amounts of precompaction. Spreading may also be done with asphalt-type or 

RCC pavers. Some of these pavers are equipped with one or more tamping bars which provide some initial 

compaction. 

Placement of stair-step sections may need to be limited to a maximum of 1.22 m (4ft) height in a single 

shift to avoid instability producing bulging in the outer face from the surcharge weight of material and 

equipment above. 

(b) Plating method. A variety of methods may be used for spreading of soil cement for plating 

applications. On relatively level surfaces, the methods are the same as for stair step placement. Plating construction on steeper slopes requires different procedures than stair step construction. Dozers are commonly 

used to spread soil cement on steeper slopes. USBR has reported best results in terms of producing uniform 

thickness and minimum waste when soil cement was spread from the top to the bottom, rather than from 

bottom to top. Whatever method is used, careful attention needs to be paid to achieving uniform thickness. 

(6) Compaction. Minimum compaction to be achieved in the field is normally specified as a percentage 

of maximum density determined by ASTM D 558 or ASTM D 1557, typically requiring 98 percent of 

maximum density. Moisture content of the soil cement mixture must be controlled within tight limits to 

ensure consistent optimum conditions for compaction. USBR practice has been to place soil cement at water 

contents at or slightly dry of optimum. This can help avoid excessively wet mixes that may cause traffic and 

compaction difficulties, as well as lift distortion and increased cracking due to shrinkage. Compaction 

should begin as soon as possible and be completed within about one hour after initial mixing. No section 

of soil cement should be left unworked for longer than 30 min. Climatic conditions at some sites, such as 

very cool, humid weather, may allow relaxation of this guidance. Moisture loss by evaporation during hot 

weather compaction should be replaced by light applications of water. Compaction is done by various types 

of rollers. For fine grained soils, a sheepsfoot roller is generally used for initial compaction, followed by 

a pneumatic-tire roller for final compaction. USBR practice has often been to compact the lower portion of 

the lift with a towed sheepsfoot roller, using the vibratory steel-wheeled roller for the upper portion of the 

lift. Some problems have been encountered with vibratory roller compactors when used for finer grained 

materials. Vibratory rollers may create fine transverse cracks in the soil cement surface, requiring a 

G-11 
EM 1110-2-1913 

30 Apr 2000 

rubber-tired roller for final compaction to close most of the cracks. Compacting soil cement at or above 

optimum moisture can produce rutting from pneumatic tire rolling. For coarse grained soils, vibratory steelwheeled or heavy pneumatic rollers are generally used. Compacted layer thickness is typically from 152.4 

to 228.6 mm (6 in. to 9 in.), although greater thicknesses of coarse grained soils can be compacted with 

heavy equipment designed for thicker lifts. The specified minimum density must be achieved throughout 

the lift thickness, regardless of the lift thickness and compaction equipment used. Compactor weight, and 

vibration amplitude and frequency must be adjusted during construction to obtain the best compaction. Test 

sections are a valuable aid in determining the optimum compaction equipment characteristics and 

procedures. 

(a) Stair step method. Compaction of the outer edge of the layer is usually not necessary from the 

standpoint of structural integrity. However, uniform edges provide a better appearance and allow for easier 

emergency egress from streambeds. Sharp edges reduce wave runup but increase roughness. Edge 

compaction can be accomplished by hand tampers or through the use of some type of edge support during 

compaction. 

(b) Plating method. Compaction is done with various roller types. Construction on near horizontal surfaces is similar to layered construction. Compaction on steeper side-slopes requires different procedures. 

A rolling deadman (Figure G-7) has been used to winch the roller up and down slope. Adequate compaction 

has been achieved using bulldozers, although their use is not recommended. Multiple overlapping passes 

are usually required. Surface tearing can be minimized by using cut grousers or street pads. Compaction 

from bottom to top has been most successful. 

Figure G-7. "Deadman" pulling vibratory sheepsfoot 

roller up the slope 

the layer which would reduce bond. 

(7) Bonding lifts. The bond between soil 

cement layers is generally weak. No definite 

criteria is available on the most effective methods 

ofbonding between layers; however, bonding may 

be considered if layer separation is anticipated. 

Layer separation may be a concern from strong 

wave action, or at the upper lift of some sections, 

where there is little weight above the lift to 

mobilize shear resistance. The most significant 

factor in bond strength is time delay between lifts. 

The shorter the time between lifts the better the 

bond. Long placements may be broken up into 

shorter segments, enabling subsequent lifts to be 

placed more rapidly. Moist curing increases the 

bond strength but excess water tends to decrease it. 

Most specifications require temporarily exposed 

surfaces to be kept moist and clean. Care must be 

taken to avoid tracking clay or other materials onto 

Power brooms should be used for lift surface cleaning to remove loose and unhanded material. USBR 

studies have suggested that roughening the lift surface with steel power brooming does not significantly 

contribute to increased bond strength. Brooming is not permitted prior to 1 hr after compaction to allow adequate set of the soil cement. 

Both dry cement and cement slurry lift bonding have been used and evaluated in USBR test sections, with 

encouraging results. A slurry mix should have a water/cement ratio of about 0. 70 to 0.80 and an application 

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G-13

the latter rate. Dry cement applications have a disadvantage of being susceptible to wind, while cement slurry

is susceptible to rapid drying. Whichever method may be used, the material should be applied immediately

before placement of the next lift.

(8) Finishing. As compaction nears completion the entire layer should be shaped to specified lines,

grades, and cross sections. Edge shaping can be done with a modified blade or a curved attachment on the

roller. The lift may require scarification to take out imprints left by equipment or to remove thin surface

compaction planes. Scarification can be done with a variety of spring tooth or spike toothed harrows, or

similar equipment. Soils containing gravel may not require scarification. Final surface compaction

following scarification is performed with a steel-wheeled roller in nonvibratory mode, or a rubber-tired

roller. A smooth “table top” finish is not required and may be detrimental to lift joint shear strength. Wheel

marks are acceptable, although they may make lift joint cleanup more difficult

The edges on stair-stepped soil cement applications have been finished by cutting back the uncompacted

edges, by using special rounded attachments on compaction equipment, and by leaving sacrificial

uncompacted edge material in place to be eroded later.

(9) Construction joints. Construction joints are required at the completion of each day’s work or when

work must be stopped for time periods longer than allowed for placement and compaction of fresh soil

cement. They are made by cutting back into the finished work to proper crown and grade. The joint must

be vertical, full depth, and transverse to the layer direction and is usually done with the toe of a grader blade

or bulldozer blade. Care must be taken that no debris is present on the joint edge, and that new material

placed against the joint adheres to the previous work. Joints should be staggered to inhibit cracking

throughout the structure

(10) Curing and protection. Proper curing is essential, because strength gain and durability is dependent

upon time, temperature and the presence of moisture. All permanently exposed surfaces should be moist

cured for a period of seven days. Traffic should be kept off the soil cement during the curing period. Light

traffic is sometimes allowed on the completed soil cement, provided the curing is not disrupted.

Soil cement must be protected from freezing during the curing period. Insulation blankets, straw, or a

soil cover are commonly used. Light rainfall should not interrupt construction. However, a heavy rain prior

to compaction can be detrimental. For mixed-in-place operations, if rain falls during the cement spreading

operation, the cement already spread must be quickly mixed with the soil, and compaction must proceed

immediately. After soil cement has been compacted, rain will seldom have detrimental effects.

(a) Moist curing. Water curing may be done with fog spraying, or with weighted and secured plastic

sheeting if wind is not a problem. Wet burlap can also be used if a moist condition can be maintained. A

minimum of 152.4 mm (6 in.) of moist earth can be specified as an alternative. The earth cover may also

inhibit freezing should colder temperatures be expected.

(b) Bituminous membrane curing. Membrane curing using some types of bituminous material (generally

an emulsified asphalt) can be used as an option to water curing where no succeeding layers will come in

contact with the membrane. However, the black color may be objectionable to owners. Bituminous

membrane curing should not be used for levees, ponds or reservoirs which will have water frequently in

contact with the membrane, without evaluation of environmental effects of the bituminous membrane. An

application rate of 0.68 to 1.4 R/m (0.15 to 0.30 gal/sq yd) is required. The soil cement should be moistened 2

just prior to the membrane application. Sand can be spread over the bituminous membrane curing if light

traffic is necessary, to prevent tracking of the bituminous material.
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30 Apr 2000 

c. Mixed-in-place construction. In-place mixing is generally not used nor recommended for multi -layer 

construction. Plating type embankment applications are possible with the mixed-in-place method of soil 

cement, although again are not recommended. The basic steps in mixed-in-place construction are: soil 

preparation, cement addition, pulverization and mixing, compaction, finishing, curing, and protection. 

Following mixing, the construction techniques are essentially identical to central plant soil cement and are 

not further discussed under the mixed-in-place method. Although windrow type mobile pugmill mixers are 

used for pavement mixed-in-place construction, they are seldom used for embankment applications. Mix-inplace operations are generally performed using transverse single or multiple-shaft rotary mixers (see Figure G-8). In-place strength of the soil cement using mixed-in-place construction may be only 60 to 

80 percent of the laboratory values, due partly to less efficient mixing compared to central mixing. Adding 

one to two percent cement is common practice to compensate for the higher variation in strength using 

mixed-in-place construction. 

(1) Soil preparation and pulverization. The 

soil is prepared by removing and replacing, or 

stabilizing, soft or wet areas, removing deleterious 

materials such as stumps, large roots, organic 

soils, and aggregate greater than 76.2 mm (3 in.) in 

size, and grading to the approximate final design 

profile. Most overly wet areas can be corrected by 

aerating and recompacting, or some type of 

chemical stabilization. Proper moisture content is 

essential for unimpeded construction traffic and 

for satisfactory pulverization and mixing. Dry 

soils may be disced and wetted by spray trucks 

until moisture content is near optimum for the soil 

cement. A moisture content near optimum may be 

Figure G-8. Transverse single-shaft rotary mixer necessary for pulverizing fine grained soils. Pulverization of soil prior to cementitious materials 

spreading is generally necessary to insure uniform cement mixing. Pulverization of soils with higher fines 

content or higher plasticity may be difficult without proper moisture control and proper equipment. 

(2) Cementitious materials application. Cementitious materials are distributed on the soil surface using 

a bulk mechanical spreader (see Figure G-9), or for smaller projects, by hand placing cement bags. 

Mechanical spreaders must be operated at uniform speed with a relatively constant level of cement in the 

hopper to produce a uniform spread of cement. Mechanical spreaders also require sufficient traction for 

proper distribution, sometimes requiring wetting and rolling the soil prior to spreading. Some spreaders are 

directly attached behind a bulk cement truck, where cement is pneumatically moved into the spreader hopper 

for distribution. PCA (1995) has convenient tables to convert the required cement content as a percentage 

by weight of oven-dry soil into a cement spread quantity in terms of weight of cement per square foot of 

soil surface. Cement spreading can be performed only when wind is absent and may require environmental 

permits. Although cement slurry spray applicators, including admixture capability, are available, they have 

not been widely used as yet. 

(3) Pulverization and mixing. Most soils must be pulverized prior to mixing operations, using the rotary 

mixers. For mixing, single-shaft mixers require at least two passes; one to mix the soil and cement, and the 

second to add water. Multiple-shaft mixers handle these functions in one pass. Agricultural equipment does 

not generally give adequate results. In-place mixing efficiency is generally poorer than central mixed soil 

cement. 

G-14 
Figure G-9. Bulk mechanical spreader 

EM 111 0-2-1913 

30 Apr 2000 

(4) Compaction, finishing, curing, and 

protection. These construction techniques for 

mixed-in-place construction are essentially identical 

to those for central plant soil cement. 

G-7. Quality Control, Inspection, and 

Testing 

Adequate quality control and inspection 

procedures are important factors in successful soilcement construction. Construction control procedures for soil-cement are fairly standardized. The 

quality of the two basic operations (soil-cement 

mixing and actual construction) are insured through 

control of four basic factors: cement content, 

moisture content, compaction, and curing. These 

factors can be controlled easily by organizing the 

inspection steps into a routine that fits in with the 

sequence of construction steps. These steps are slightly different for central-plant construction and mixed-inplace construction. 

a. Central-plant construction. The inspector checks on the following items. 

(1) Construction site and equipment. Equipment must be clean, appropriate for the soil type, adjusted 

properly, and designed to preclude contamination introduction. Hauling vehicles must have protective 

covers where appropriate. The site should be set up to meet production and timing requirements and provide 

efficient traffic flow and proper separation distances for material stockpiles. 

(2) Soil. Soil must match identification data given in the laboratory report. The inspector should check 

for uniformity of color, texture, and moisture. The soil should be monitored as it is stockpiled. Upon completion of the stockpile it is sampled and tested for acceptance. Gradation, specific gravity, and Atterberg 

limits should be tested regularly. 

(3) Cement application. The amount of cement is specified either as a percentage of cement by weight 

of oven-dry soil material, or in pounds of cement per cubic foot of compact soil-cement. Pre-construction 

plant calibration and daily calibration checks insure an accurate mix. Different types of calibration 

procedures are applicable depending on the type of mixing plant used. In addition to plant calibration and 

daily checks of mix proportions, freshly mixed soil-cement cement content can be tested using a titration test 

and hardened soil-cement cement content can be tested using ASTM D 806. 

(4) Water Application. Water is added at the central mixing plant in quantities sufficient to bring the 

mixture to the optimum moisture content as determined by a laboratory moisture-density test. Generally the 

moisture content should not be more than two percentage points below or above the specified optimum 

moisture. To estimate mixing water requirements stockpile moisture content is determined and additional 

water requirements calculated. Experienced inspectors can determine, in a qualitative way, the moisture 

requirements just prior to compaction by squeezing the mixture in the palm of the hand. A mixture near 

optimum moisture content is just moist enough to dampen the hands when packed tightly and can be broken 

in two with little or no crumbling. During compaction the surface of the material may dry out (indicated by 

a graying of the surface). Moisture is brought back to optimum by fog spraying. 

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 Reference available through American Society for Testing and Materials, 1916 Race Street, Philadephia, PA 19103. 1

G-16

(5) Mix uniformity. Uniformity is checked visually by noting color uniformity either at the plant or by

digging a hole in the loosely placed material in the layer. If, due to lightness of soil material color, it is

difficult to determine mixing, a 2 percent solution of phenolphthalein can be sprayed on a cut face of the

material to determine if any cement is present. The cement in the mixture will turn treated material pinkishred while untreated soil will retain its natural color.

(6) Transporting and spreading. Specified timing requirements for transporting and spreading should

be monitored. Traffic patterns and possible material contamination (especially near layer edges and ramps)

should be checked. Layer offset distances and layer thickness and uniformity should also be checked. The

spreader should not be allowed to empty, but should be stopped while there is still mix left in the hopper.

This insures uniform spreader operation.

(7) Compaction. Samples of the soil-cement are taken from the batch and prepared for laboratory

moisture-density testing at the same time compaction is taking place. This accounts for timing parameters.

In-place density testing is conducted as soon as possible after compaction in a spot where the laboratory

material has been taken. Field and laboratory densities are then compared.

(8) Curing. Curing specifications and placement procedures should be closely monitored by the inspector. If water curing is used, the equipment must be capable of fog, rather than pressure, spraying. The

surface must be kept continuously moist. Exposed surfaces should be cured for seven days. Curing times

must be satisfied as well as provisions made in the case of freezing temperatures. Membrane cures must be

of sufficient thickness to hold in moisture.

G-8. References

American Society for Testing and Materials 1999 1

American Society for Testing and Materials. (1993). 1993 Annual Book of Standards, Philadelphia, PA.

ASTM C-150-98 1

American Society for Testing and Materials. 1998. “Specification for Portland Cement.”

ASTM D-558-96 1

American Society for Testing and Materials. 1996a. “Test Methods for Moisture-density Relations of Soilcement Mixtures.”

ASTM D-559-96 1

American Society for Testing and Materials. 1996b. “Test Methods for Wetting and Drying Compacted

Soil-cement Mixtures.”

ASTM D-560-96 1

American Society for Testing and Materials. 1996c. “Test Methods for Freezing and Thawing Compacted

Soil-cement Mixtures.”

ASTM D-806-96 1

American Society for Testing and Materials. 1996d. “Test Method for Cement Content of Soil-cement

Mixtures.”
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G-17

ASTM D-1557-91 1

American Society for Testing and Materials. 1991. “Test Method for Laboratory Compaction Characteristics of Soil Using Modified Effort.”

ASTM D-1632-96 1

American Society for Testing and Materials. 1996e. “Practice for Making and Curing Soil Cement

Compression and Flexure Test Specimens in the Laboratory.”

ASTM D-1633-96 1

American Society for Testing and Materials. 1996f. “Test Method for Compressive Strength of Molded

Soil Cement Cylinders.”

ASTM D-2487-93 1

American Society for Testing and Materials. 1993. “Classification of Soils for Engineering Purposes.”

CRD-C-400

Corps of Engineers

Portland Cement Association 1995

Portland Cement Association. 1995. “Soil Cement Construction Handbook.”
where c ' kbl

kf zbl d

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H-1

Appendix H

Notation

The symbols that follow are used throughout this manual and correspond wherever possible to those

recommended by the American Society of Civil Engineers.

Symbol Term

c Cohesion per unit area; a constant for natural top stratum

cN Effective cohesion in terms of effective stress

cv Coefficient of consolidation

Cc Compression index

Cá Coefficient of secondary compression

d Effective thickness of pervious substratum

e Void ratio

Ft Transformation factor for permeability

ho Excess hydrostatic head

hNo Hydrostatic head beneath landside toe of levee

hx Hydrostatic head beneath top stratum

H Net head

i

c Critical gradient for landside top stratum

i

1 Upward gradient at landside toe of berm

i

o Upward gradient at landside toe of levee

k Coefficient of permeability

k Coefficient of permeability (top stratum) b

kf Average horizontal coefficient of permeability

k Coefficient of permeability (vertical) n

kbl Permeability of landside stratum

kbr Permeability of riverside stratum

L Distance from riverside levee toe to river 1

L2 Base width of levee and berm

L3 Length of top stratum landward of levee toe

Md Slope of hydraulic grade line

(Continued)
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H-2

Symbol Term

Q Shear test for specimen tested at constant water content (unconsolidated-undrained)

QS Total amount of seepage passing beneath levee

R Shear test for specimen consolidated and then sheared at constant water content (consolidated-undrained)

s (a) distance from the landside toe of the levee to the point of effective seepage entry

(b) shear test for specimen consolidated and sheared without restriction of change in water content (consolidated-drained)

x Effective length of riverside blanket 1

x Distance from landside levee toe to effective seepage exit 3

zb Effective thickness of stratum

zt Transformed thickness of top stratum

zbl Effective thickness of landside top stratum

zbr Effective thickness of riverside top stratum

zbt Effective thickness of top stratum

ã Wet unit weight of soil t

ã Unit weight of water w

ãN Submerged or buoyant unit weight of soil

öN Angle of internal friction based on effective stresses

S/ Shape factor to generalized cross section of the levee and foundation