bawcodeofpractice bank bottom protection mar 2008

5/26/2018 BAWCodeofPractice Bank Bottom Protection MAR 2008

BAWCode of Practice

Use of Standard Construction Methods for Bank and Bottom

Protection on Inland Waterways (MAR)

Issue 2008


BAW Codes of Practice and Guidelines

Publisher

Bundesanstalt fr Wasserbau (BAW)

Kussmaulstrasse 17

76187 Karlsruhe, Germany

P. O. Box 21 02 53

76152 Karlsruhe, Germany

Tel.: +49 721 9726-0Fax: +49 721 9726-4540

[email protected]

www.baw.de

No part of this bulletin may be translated, reproduced or duplicated in any from or by any means without the

prior permission of the publisher: BAW 2008

Karlsruhe December 2008 ISSN 2192-9807


BAW Code of Practice: Use of Standard Construction Methods for Bank and Bottom Protection on InlandWaterways, Issue 2008

MAR Working group

(April 2006 December 2008)

Members:

BARTNIK, Wolfgang Dipl.-Ing., Wasserstraen-Neubauamt Datteln

CONRADI, Stefan Dipl.-Ing., Wasser- und Schifffahrtsdirektion Ost, Magdeburg

FISCHER, Uwe Dipl.-Ing., Bundesministerium fr Verkehr, Bau, und Stadtentwicklung, Bonn

FLEISCHER, Petra Dipl.-Ing., Bundesanstalt fr Wasserbau, Karlsruhe

HEIBAUM, Michael Dr.-Ing., Bundesanstalt fr Wasserbau, Karlsruhe

HOLFELDER, Tilman Dr.-Ing., Bundesanstalt fr Wasserbau, Karlsruhe

KAYSER, Jan Dr.-Ing., Bundesanstalt fr Wasserbau, Karlsruhe (Leiter der AG)

LIEBENSTEIN, Hubert Dipl.-Ing., Bundesanstalt fr Gewsserkunde, Koblenz

NULLE, Undine Dipl.-Ing., Wasser- und Schifffahrtsamt Berlin

OSTERTHUN, Manuela Dr.-Ing., Wasser- und Schifffahrtsdirektion Mitte, Hannover

POHL, Martin Dr.-Ing., Bundesanstalt fr Wasserbau, Hamburg

SHNGEN, Bernhard Prof. Dr.-Ing., Bundesanstalt fr Wasserbau, Karlsruhe

SOYEAUX, Renald Dr.-Ing., Bundesanstalt fr Wasserbau, Karlsruhe

STEIN, Jrgen Dr.-Ing., Bundesanstalt fr Wasserbau, Karlsruhe

THYSSEN, Heinz-Jakob Dipl.-Ing., Wasser- und Schifffahrtsdirektion West, Mnster



II


BAW Code of Practice: Use of Standard Construction Methods for Bank and Bottom Protection on Inland

Waterways, Issue 2008

I

Table of Contents Page

1 Preliminary Remarks 12 Terms and Definitions 23 Boundary Conditions for Standard Construction Methods 43.1 General 43.2 Types of vessel and hydraulic loads 53.3 Waterway cross-sections 73.4 Ground conditions 84 Revetment Components 104.1 Armourstones 104.2 Grout 114.3 Filter layers 114.4 Separation layers 114.5 Impervious lining systems 114.5.1 General 114.5.2 Flexible lining systems 124.5.3 Inflexible lining systems 125 Standard Methods of Construction 125.1

General 12

5.2 Armour layers 145.2.1 Permeable armour layers comprising riprap 145.2.2 Permeable armour layers comprising partially grouted armourstones 165.2.3 Impermeable armour layers comprising fully grouted armourstones 175.3 Toe protection 185.4 Flexible linings 205.5 Freeboard height 205.6 Selection of a standard method of construction 205.6.1 General 205.6.2 Requirement for an impervious lining 215.6.3 Soil classification 225.6.4 Requirement for a filter or a separation layer 225.6.5 Selection of an armour layer 236 Other Methods of Construction 236.1 General 236.2 Revetments in combined rectangular-trapezoidal (KRT) profiles 246.3 Impermeable erosion-resistant pavements 24



7 Vegetation Cover in Standard Methods of Construction 25

7.1 General 25

7.2 Permeable armour layers comprising riprap or partially grouted armourstones as described in

sections 5.2.1 and 5.2.2 respectively 26

7.3 Impermeable armour layers comprising fully grouted armourstones as described insection 5.2.3 27

7.4 Guidance on vegetation cover on flexible linings 27

8 Guidance on Invitations to Tender, Execution of the Works, Quality Control and Maintenance 27

8.1 General 27

8.2 Invitations to tender 28

8.2.1 General 28

8.2.2 Armour layer 29

8.2.3 Underlayers 30

8.2.4 Minimum requirements for secondary tenders 308.3 Execution of the works 31

8.4 Quality assurance 32

8.4.1 General 32

8.4.2 Depth measurements for quality assurance 33

8.5 As-built documents 33

8.6 Guidance on maintenance 34

9 Literature 35

List of Tables

Table 3.2-1: Dimensions of ship types 5

Table 3.3-1: Geometry of the standard canal profiles N.B: Only the first bank is considered

for the revetment design. 8

Table 3.4-1: Characteristic soil parameters for soil types B1 to B5 9

Table 4.1-1: 50 %-values for the standard size classes for riprap armour layers 11

Table 5.1-1: Void ratio of armourstone armour layers as a function of the method of installation

(based on depth measurements taken at the highest points of the armourstones) 13

Table 5.2.1-1: Stone diameters, stone weights and size classes required for standard profiles

approved for all types of inland waterway vessels (ES, GMS, SV, GMS)

for a range of densities (2300 3600 kg/m3) 15

Table 5.2.1-2: Recommended armour layer thicknesses (riprap) for slope and bottom revetments,

taking account of the soils specified in 3.4 16

Table 8.2.1-1: Documentation to be provided on submission of a tender 29

II



List of Figures

Figure 3.2-1: Example of the most unfavourable position of a large self-propelled barge or

push-tow unit at full draught in a T-profile 7

Figure 4.1-1: Definition of the design values G50, shown here for class LMB5/40 10

Figure 5.2.1-1: Diagram of the cross-section of a permeable armour layer of riprap 14

Figure 5.2.2-1: Diagram of the cross-section of a permeable armour layer comprising partially

grouted armourstones 17

Figure 5.2.3-1: Diagram of the cross-section of an impermeable armour layer comprising fully

grouted armourstones 18

Figure 5.3-1: Design of the toe protection 19

Figure 5.6-1: Criteria for the selection of an impermeable or permeable revetment 22

III



IV

List of Annexes

Annex 3.1: Principles of hydraulic design in accordance with /GBB/ 38

Annex 3.2.1: Hydraulic loads at 97 % vkritfor standard T-profiles 40

Annex 3.2.2: Hydraulic loads at 97 % vkrit for standard RT-profiles 41

Annex 4.1-1: Guidance on how to determine the mean stone size, D50, or

the mean stone weight, G50 42

Annex 4.1-2: Cumulative curves for armourstones - classes LMB10/60, LMB5/40, CP90/250 43

Annex 5.2.1-1: Permeable armour layers comprising riprap Recommended

thicknesses, dD, of armour layers for slope and bottom protection systems 44

Annex 5.2.1-2: Permeable armour layers comprising riprap - Documentation of the armour layer

thickness, dD, calculated for slopes (with a geotextile) 46

Annex 5.2.1-3: Permeable armour layers comprising riprap Calculated minimum thicknesses 47

Annex 5.2.2-1: Permeable armour layers comprising partially grouted armourstones -Recommended thicknesses, dD, of armour layers for slope and bottom protection

systems (with a geotextile) 48

Annex 5.2.2-2: Permeable armour layers comprising partially grouted armourstones -

Documentation of the calculated armour layer thickness, dD, for slopes

(with a geotextile) 49

Annex 5.2.3: Impermeable armour layers comprising fully grouted armourstones placed on

a geotextile Required armour layer thickness, dD, against buoyancy 50

Annex 5.6.2-1: Permeable armour layers comprising riprap placed on a geotextile, with an

impermeable lining Required armour layer thickness, dD, against buoyancy 51

Annex 5.6.2-2: Permeable armour layers comprising partially grouted armourstones placed on

a geotextile, with an impermeable lining Required armour layer thickness, dD,

against buoyancy 52



1 Preliminary Remarks

The following Code of Practice deals with standard methods of constructing bank and bottom protection

systems for inland waterways which may be used under defined boundary conditions without the need for

verification by calculation.

The first edition of the Code was published in 1993. Considerably more is now known about how to exe-

cute revetments, the actions on such structures and their stability. In addition, the relevant rules and

standards have either been revised or rewritten. A thorough revision of the Code was therefore necessary

and the revised version is now available as the present 2008 edition.

The standard methods of construction are based on experience in the construction and maintenance of

revetments and on engineering design rules. The latter are to be found in the Principles for the Design of

Bank and Bottom Protection for Inland Waterways /GBB/ which was also published by the Federal Wa-

terways Engineering and Research Institute.

The standard construction methods have been drawn up both with present-day vessels and future ship-

ping in mind, taking account of the increase in the number of large Rhine barges (self-propelled barges).

The principal geometries considered are the trapezoidal profile (T-profile) and the rectangular-trapezoidal

profile (RT-profile) for Class Vb waterways in accordance with the Directives for the Standard Cross-

Sections of Canals for Inland Shipping /RiReS/, with a blockage ratio, n, greater than 5.3. Application of

the standard methods of constructing revetments to smaller canals with the same blockage ratio will gen-

erally result in a conservative design, even though the ships, draughts and bank distances are corre-

spondingly smaller than in standard profiles. A separate hydraulic design is generally required ifungrouted revetments are installed on cross-sections with lower blockage ratios, such as those intended

for one-way traffic, as the loads due to the return current, bow thrusters and, for water depths less than

4 m, to the propeller wash caused by the main propulsion units may be greater than those in standard

profiles.

A value of 97 % of the critical ship speed has been specified as the design speed. It takes economic con-

siderations into account, including the behaviour of shipping and the dimensioning of the revetment.

Individual revetment designs in accordance with the Principles for the Design of Bank and Bottom Protec-

tion for Inland Waterways /GBB/ are required if the geometrical, hydraulic and geotechnical boundaryconditions differ from those on which the standard designs are based. The boundary conditions under

which the methods of construction described in this Code of Practice apply are detailed in section 3 to

enable designers to ascertain whether an individual design is necessary.

All standard methods of construction are technically equivalent unless further restrictions are explicitly

stated. The choice of construction method will be based on technical and economic criteria.

The Codes of Practice "Use of Geotextile Filters on Waterways" /MAG/ and Use of granular filters on

waterways /MAK/ apply to the design of filters required for the standard methods of construction. In addi-

tion, the Code of Practice Use of Cement Bonded and Bituminous Materials for Grouting of

Armourstones on Waterways /MAV/ applies to grouted revetments. Information on the execution of lin-

ings is given in the Recommendations for the use of lining systems on beds and banks of waterways

1



/EAO/. The Supplementary Technical Contract Conditions Hydraulic Engineering for Embankment and

Bottom Revetments (Section 210) /ZTV-W 210/ apply to the tendering procedure and to execution. In all

cases, the latest versions of the above publications shall apply.

2 Terms and Definitions

Some of the principal terms used in this Code of Practice are explained below. Other important terms are

defined in /GBB/.

Armour layer: Upper erosion-resistant layer of a bank or bottom revetment. In standard methods of con-

struction the armour layer consists of a layer of armourstones.

Armour layer thickness: Thickness of the armour layer d D, measured perpendicular to the lower or up-

per edge of the layer (without a filter or impervious lining).

Bank and bottom protection (system): Permeable or impermeable revetment installed on a waterway

to ensure that the geometry of the cross-section is maintained.

Blockage ratio:Ratio, n, of the cross-sectional area of a waterway at a particular water level, A, (which

affects the return flow) to the cross-sectional area, of the submerged midship section of a vessel, AM(n =

A/AM,)

Bow-heavy: Used to describe a ship laden such that the bow is immerged to a greater depth than the

stern. In this case, it is the bow dimensions that are decisive for the design of bank and bottom revet-

ments.

Critical ship speed, vkrit: Speed of a ship in shallow water or in a canal at which the water displaced by

the vessel is prevented from flowing fully in the opposite direction to the ship and past its stern. The tran-

sition from subcritical to supercritical flow begins (the Froude number in the narrowest cross-section adja-

cent to the vessel being equal to 1). In general, displacement craft cannot exceed vkrit. Any attempts by

displacement craft to travel faster than vkrit, e.g. by increasing the driving power, generally result in even

higher return flow velocities and in a greater drawdown than at vkrit, causing the speed of the vessel over

ground to diminish and/or the vessel to be drawn towards the bed of the river or canal.

Dynamic underkeel clearance: Difference between the water depth and the draught of a moving ship

(sailing draught). The latter is the sum of the draught and the squat.

Excess pore water pressure: Water pressure in the pores of a soil that exceeds the hydrostatic pore

water pressure. Excess pore water pressure occurs when the volume of the pore water is prevented from

increasing (if the pore water pressure changes) or when the volume of the granular structure is prevented

from decreasing (if there are changes in the total or effective tension in the granular structure). It is

caused, amongst other things, by rapid water level drawdown. As a result, the pressure in the subsoil will

be higher than that at the water/soil interface.

Filter:The purpose of a filter (comprising a geotextile or aggregates (granular filter)) is to retain soil under

all possible hydraulic conditions (mechanical filtration stability: protection against erosion). At the same

time, it must permit the passage of groundwater without any rise in the seepage line (hydraulic filtration

stability).

2



Freeboard: Distance between the highest possible water level (upper operating water level, plus any

safety margin required) and the lowest point on the bank that must not be overtopped.

Grout: Construction material applied as a liquid and which hardens over time, the setting period being

dependent on the material.

Hydraulic loading:The interaction between a ship and the waterway causes a displacement flow around

the ships hull which is accompanied by the bow wave, the generation of diverging waves at the bow with

a short wave period, water level drawdown adjacent to the ship, the generation of transversal stern waves

with a short wave period and a slope supply flow which restores the surface of the water to its undis-

turbed level. The sequence of bow waves, water level drawdown and transversal stern waves corre-

sponds approximately to the length of the ship and is known as a primary wave (primary wave system).

The waves with short wave periods generated at the bow and stern are referred to as secondary waves

(secondary wave system).

Lane: Width required by a moving ship within a channel for nautical and hydrodynamic reasons.

Manoeuvring area:Area of a canal or waterway in which ships change course, slow down or accelerate,

including turning basins, mooring points, lock waiting areas and loading/unloading facilities.

Minimum armour layer thickness: In addition to the thickness of the armour layer obtained in the geo-

technical design calculations, a certain minimum thickness is required to take account of impacts by ship-

ping, the stability of the layer of dumped armourstones and the variations in its uniformity, anchor cast,

the type of filter used or other technical aspects. (For values, see /GBB/, sections 6.9 and 6.11, and

/Kayser 2005/). The greater armour layer thickness shall apply.

Partial/full grouting: Partial grouting consists of partially filling the voids between the armourstones with

grouting material, full grouting of filling the voids completely with grouting material.

Primary wave: Hydraulic loading.

Revetment: Overall structure of a bank and bottom protection system including the armour layer, the filter

and, if necessary, an impervious lining with a separation layer, but not the underlayer, if used. Permeable

revetments permit unhindered water exchange between the subsoil and the waterway. They generally

comprise an armour layer placed on a filter. Impermeable revetments prevent the exchange of water

between the waterway and the subsoil. They may comprise a permeable armour layer placed on an im-pervious lining, the two being separated by a geotextile separation layer, or an impermeable armour layer

placed on a geotextile separation layer.

Secondary wave: Hydraulic loading.

Separation layer: Separation layers prevent the mixing of different granular layers and erosion. In con-

trast to filters, their hydraulic filtration stability is of minor importance (e.g. non-cohesive soil on soft to

pulpy ground, armourstones on a clay liner, inflexible lining on erosion protection). At the same time,

separation layers may promote the self-healing of defective impervious lining systems.

Stability of the armour layer: The individual stones in riprap armour layers must interlock in order to

ensure that the rock armour is stable. A minimum thickness is therefore required, irrespective of the de-

3



sign calculations (for values, see /Kayser 2005/). Interlocking stones are a prerequisite for the use of the

equations for the sizing of individual stones given in /GBB/.

Standard method of construction: Standardized construction method which can be applied under cer-

tain specified boundary conditions without separate verification by calculation.

Stern-heavy: Used to describe a ship laden such that the stern is immerged to a greater depth than the

bow. In this case, it is the stern dimensions that are decisive for the design of bank and bottom revet-

ments. Generally speaking, ships are stern-heavy when sailing empty or with ballast at the stern (to en-

sure that the propeller is completely submerged).

Toe protection: Lower part of a slope revetment in the absence of a bottom revetment.

Vegetation cover:This may consist of one or both of the following:

(1) Grasses and herbs native to the locality (or legumes for a first soil improvement) sown on the bankslopes. Vegetation may also become established as a result of natural seed dispersal, plant material

being deposited by currents or waves, hay containing ripe seeds being spread over the slopes or by

planting sods or depositing soil containing seeds.

(2) Woody plants (including cuttings), reeds or herbaceous perennials planted on the bank slopes.

Water level drawdown/drawdown velocity: Vessels in motion cause the water to flow around them in a

particular way which results in the lowering of the water level adjacent to the vessel. Drawdown occurs

along the entire length of the ship. The water level drawdown at the banks of the waterway and the asso-

ciated drawdown velocity are relevant for design.

Zone of fluctuating water levels: Zone on a canal slope which is subjected to the highest hydraulic

loads (bow and stern waves, positive surge and drawdown due to lockage operations, wind waves). In the

context of this Code of Practice, the zone of fluctuating water levels extends from 1.0 m below the lower

operating water level, BWu, to 0.7 m above the upper operating water level, BWo.

3 Boundary Conditions for Standard Construction Methods

3.1 General

The standard construction methods apply when certain boundary conditions in respect of

the types of ships using a waterway (see section 3.2 )

the waterway cross-sections (see section 3.2) and

the ground conditions (see section 3.4)

are satisfied. They are based on the Principles for the Design of Bank and Bottom Protection for Inland

Waterways /GBB/.

Certain assumptions on the characteristics of the ships and the armourstones are made to facilitate the

calculation of the hydraulic actions and for design purposes. The parameters subsequently selected arelisted in Annex 3.1.

4



Armourstones of various size classes and densities as defined in section 4.1and grouting materials as

defined in 4.2are taken into account.

Geotextiles or granular filters in accordance with section 4.3may be used as filters.

The impermeable linings used in the standard methods of construction may be tried-and-tested flexible or

inflexible linings as defined in section 4.5, combined with a separation layer as defined in section 4.4.

3.2 Types of vessel and hydraulic loads

The standard methods of construction are based on common types of inland waterway vessel with the

standard dimensions shown in Table 3.2-1, i.e.:

Europe ships (ES)

large self-propelled barges (GMS)

push-tow units (SV)

very large self-propelled barges (GMS).

These types of vessel cover the usual spectrum of ships to be found on Class Vb inland waterways. The

cargo of fully laden ships (with the maximum draught permitted for canals) is usually evenly distributed

over the vessel. Empty ships or ships sailing with ballast are assumed to have a stern-heavy trim. It

should be noted that the coefficient CH, which reflects the influence of the type of ship, the degree of

loading, the trim and the water surface gradient, is considered in relation to the ratio of draught to water

depth, T/h, (see Annex 3.1) in the basic calculations performed here.

Table 3.2-1: Dimensions of ship types

Draught

T mFully laden* EmptyType

Length

L [m]

Width

B [m]

Bow/stern Bow Stern

Europe ships (ES) 85 9.50 2.50 0.70 1.40

Large self-propelled

barges (GMS) 110 11.45 2.80 0.80 1.60

Push-tow units (SV) 185 11.45 2.80 0.60 1.60

Very large self-propelled

barges (GMS)135 12.00 2.80 0.90 1.80

*max. permissible draught for canals

Certain types of vessel such as tugs or pusher craft sailing alone are not considered as they are generally

seen quite rarely on inland waterways. However, the potentially greater loads occurring in canal sections

in which such craft account for a significant proportion of vessels must be taken into account as specified

in /GBB/, in particular where such vessels can be assumed to travel at speeds close to the critical ship

5



speed, similar to the types of vessel referred to above. Such loads result from the possible superpositions

of bow and stern waves or of primary and secondary waves which are not relevant for the types of vessel

in standard canals shown in Table 3.2-1. Higher loads must also be taken into account if the waterways

are frequently used by very large motor yachts assumed to travel close to sliding speed.

Loads caused by typical recreational craft are generally lower than those caused by the types of vessel

referred to in Table 3.2-1 and are covered by the standard methods of construction. The greater run-up

height of secondary waves, in particular those due to recreational craft, is taken into account when the

freeboard is specified (see section 5.5).

It is assumed that only ship-induced currents in the waterway are relevant for design purposes. The ship

speed over ground may be taken as being equal to the ship speed through the water.

As recommended in /GBB/, a ship speed of 97 % of the critical speed is assumed for design purposes.

The value corresponds to the typical measured maximum ship speeds that have been observed irrespec-tive of the permissible ship speeds. It reflects the behaviour of inland navigation vessels on canals. Cases

in which the critical ship speed is reached or exceeded only occur very rarely and are locally limited so

that they do not constitute standard design situations.

Tables with the most important hydraulic loads for the above ship speeds in trapezoidal and rectangular-

trapezoidal profiles are given in Annex 3.2. The ship speeds shown in the tables may be lower than the

permissible ship speed, vzul, stated in the German Regulations for Navigation on Inland Waterways

/BinSchStrO/ if the blockage ratio (ratio of the waterway cross-section to the cross-section of the ship) is

low, e.g. in the case of large self-propelled barges in T-profiles. The opposite case, in which the values of

97 % of the critical ship speed, vkrit,exceed the permissible ship speed, v zul, can occur when the blockage

ratio is high (ships with small cross-sections). Revetment designs as specified in /GBB/ are required for

ship speeds other than 97 % of the critical ship speed.

The ships position is taken to be the most unfavourable path of a fully laden vessel travelling close to the

bank. In the case of T-profiles the ship is assumed to be travelling 1 m over the toe of the slope at the

edge of the navigation channel in accordance with the Directives for the Standard Cross-Sections of

Canals for Inland Shipping /RiReS/. An example of a fully laden large self-propelled barge is shown in

Figure 3.2-1. The same position has been assumed for unladen vessels on the basis of field tests.

In the case of RT-profilesit has been taken into consideration that the available width of the navigation

channel at the level of the relevant draught of the moving vessel is greater than for T-profiles. Further-

more, the distance to the design bank in RT-profiles is taken to be 1.5 m greater than in T-profiles in

keeping with field investigations which revealed greater bank distances in the former.

6



Figure 3.2-1: Example of the most unfavourable position of a large self-propelled barge or push-tow

unit at full draught in a T-profile

The greatest hydraulic loads usually occur when single vessels are travelling along a waterway. It can be

assumed that the loads will be lower when vessels pass or overtake each other owing to the reduced

speeds and changes in the blockage ratios that occur in such situations.

Exceptions are loads due to the propulsion and steering units of ships which are greater when ships pass

each other than when craft are travelling alone. However, they do not generally reach values that would

be relevant for design.

Evaluations of recent measurements of propeller wash at the bottom of waterways have shown that mod-

ern large self-propelled barges single-screw vessels, in particular generate wash velocities of around

3.0 m/s close to the bottom of a waterway when sailing at the permissible dynamic underkeel clearance

on reaches. In this case, the scour depths caused by individual ships are likely to be less than 0.2 m if the

revetment comprises riprap of class LMB5/40with a density of 2650 kg/m3. A value of 0.2 m, which is the

maximum scour assumed to occur, is locally acceptable. Greater, accumulated scour depths are unlikely

on reaches as local increases in the propeller wash loads will not always occur at the same points.

Theoretical calculations assuming extreme values performed in accordance with /GBB/ and measure-

ments performed for large ships have shown that propeller wash velocities of up to around 5.0 m/s mayoccur close to the bottoms of waterways during manoeuvring operations. The associated scour depth in a

bed revetment comprising riprap of class LMB5/40 would be equal to the thickness of the armour layer.

Modified construction methods are therefore required for canal sections in which manoeuvring operations

are frequent. For example, a greater water depth could be selected or a partially grouted armour layer

installed.

3.3 Waterway cross-sections

The standard methods of construction apply to the two principal types of standard canal profile, i.e.

the trapezoidal profile (T-profile) and

7



the rectangular-trapezoidal profile (RT-profile).

Details of the dimensions are laid down in the Directives for the Standard Cross-Sections of Canals for

Inland Shipping /RiReS/. The basic geometry of each profile is summarized in Table 3.3 1.

Table 3.3-1: Geometry of the standard canal profiles

N.B: Only the first bank is considered for the revetment design.

Slope inclination

1 : mWidth at water level

bWS

Water depth

h1stbank 2 ndbank

Profile

[m] [m] [-]

T 55.0 4.00 1:3 1:3

RT 48.5 4.00 1:3

A further profile, known as the combined rectangular-trapezoidal profile (KRT-profile), is also in use. The

sides of the KRT-profile below water-level are vertical while those in the zone of fluctuating water levels

are sloped /RiReS/ (see section 6.2for guidance on execution).

The standard methods of construction are based on the lower operating water level, BW u,which is re-

garded as representative and at which the assumed canal water depth is 4 m. Greater depths result in

lower loads at the same ship speed and are therefore generally speaking not relevant for design.

3.4 Ground conditions

The armour layer thickness required to ensure the local stability of a slope is significantly influenced by

the type of in-situ ground beneath the revetment /GBB/. The standard methods of construction described

in section 5apply to five different types of soil:

B1: sands and gravels

B2: sands

B3: silty sands and gravels

B4: silts, highly silty sands and gravels

B5: cohesive soils

Apart from the shear strength, the permeability of the soil is of particular relevance to revetment design.

The excess pore water pressure beneath a revetment due to water level drawdown close to the slope

caused by passing ships, and its destabilizing effect on the revetment and the subsoil, are inversely pro-

portional to the permeability of the in-situ soil. However, this only applies to cohesionless soils (B1 to B4).

8



If a soil permanently retains an effective cohesion, ck,of at least 3 kPa, even under water, it may be as-

sumed that the local stability of permeable revetments (on cohesive soil, type B5) will not generally re-

quire verification in accordance with section 7.2of /GBB/. The minimum armour layer thicknesses apply in

such cases. The standard methods of construction do not apply if the effective cohesion is 0 < ck < 3

kPa, and in such cases revetments must be designed in accordance with /GBB/. For conservative de-signs, a type B4 soil can be assumed if the cohesion is 0 < c k< 3 kPa and the permeability is 5 10

-6 = k k

= 110-6 m/s.

The mechanical soil parameters of soil types B1 to B5 on which the standard profiles are based have

been summarized in Table 3.4 1 to facilitate classification of the in-situ soil. The classification is based on

the fines content (d5, d10, d15), also shown in Table 3.4-1, which is the main factor determining the charac-

teristic permeability, kk,of the soil. The design calculations for the standard methods of construction were

performed with the lower values of the coefficient of permeability shown in Table 3.4-1.

Table 3.4-1: Characteristic soil parameters for soil types B1 to B5

Soil Descrip-tion

Coefficient of per-meability

Effectiveangle offriction

Effectivecohesion

Wetspecificweight

Specificweightunder

buoyancy

Particle diameter diat i-% passing sieve

kk k' ck' k k' d5 d 10 d 15

[m/s] [] [kN/m] [kN/m] [kN/m] [mm] [mm] [mm]

B 1Sands

and

gravels

kk 510-4 35.0 0 19 11 0.2

B 2 Sands 510-4 > kk 5 10-5 35.0 0 19 11 0.07

B 3

Siltysandsand

gravels

510-5 > kk 5 10-6 32.5 0 18 10

0.002

0.02

B 4

Silts,

highlysiltysandsand

gravels

510-6 > kk 1 10-6 30.0

0(0



4 Revetment Components

4.1 Armourstones

The requirements for armourstones used in revetments are laid down in the European Standard EN13383-1 - Armourstone, Part 1: Specification /DIN EN 13383-1/. The current edition of the Technical Sup-

ply Conditions for Armourstones /TLW/ also applies.

EN 13383-1 specifies various standard size classes with different resistances to hydraulic actions. Small

armourstones are defined by the sieve perforation size, D, (size of the square perforations) and are re-

ferred to as class CPx/y ( Coarse Particle, x being the lower class boundary [mm] and y the upper class

boundary [mm]). The larger classes are defined by the weight, G, of the stones as light gradings LMx/y(Light Mass, x = lower class boundary [kg], y = upper class boundary [kg]) or heavy gradings HMx/y

(Heavy Mass). The stones used in armour layers for revetments on inland waterways generally belong to

classes CP90/250, LMB5/40 and LMB10/60 /Kayser 2005/.

In addition to the provisions of EN 13383, the design value obtained in the hydraulic design of revetments

with riprap armour layers in accordance with /GBB/ is the value below which 50 % (by weight) of the

stone fraction lie (G50 for weight classes and D 50 for size classes). G 50 is shown for a stone fraction of

class LMB5/40 (indicated in red) in Figure 4.1-1. G 50is also given for an average stone fraction (indicated

in green) which is defined by the line drawn between the nominal upper and lower boundaries.

Apart from the required G50(D 50)-value, the cumulative curve according to EN 13383 must lie within cer-

tain boundaries. An example for class LMB5/40 is shown by the hatched area in Figure 4.1-1.

Figure 4.1-1: Definition of the design values G50,shown here for class LMB5/40

The armourstones used must at least satisfy the 50 %-value of the mean cumulative curve (log-linear line

connecting the nominal class boundaries, see the green line given as an example in Figure 4.1-1). This

value must be checked during construction if such a check is specified in the contract. Guidance on how

to determine D50and G 50is given in Annex 4.1-1.

10



The values of D50 and G 50 for the most frequently used size classes are given in Table 4.1-1. The

boundaries mean cumulative curves and usual ranges of fluctuation of the size classes are shown in An-

nex 4.1-2. The procedure for selecting the size class described in section 5.2.1is based on those values.

Table 4.1-1: 50 %-values for the standard size classes for riprap armour layers

Size class 50 % - value

CP90/250 D 50= 150 mm

LMB5/40 G 50= 14 kg

LMB10/60 G 50= 25 kg

The standard methods of constructing armour layers are specified for four different stone densities, s, i.e.

for 2300 kg/m3, 2650 kg/m3, 3000 kg/m3and 3600 kg/m 3.

4.2 Grout

Impermeable cementitious grouting materials are recommended. Compared with partial grouting with

impermeable grouting materials, the use of water-permeable grouting materials is very limited. Bitumi-

nous grouting materials (asphalt) are not dealt with in the description of the standard construction meth-

ods as they are no longer used on inland waterways in Germany for economic reasons and as they are

difficult to install under water. Guidance on the recommended quantities of grouting material is given in

/MAV/ which also lays down the requirements for the raw materials, the required tests and installation.

4.3 Filter layers

The standard requirements for geotextile filters are specified in /TLG/ and /ZTV-W LB 210/ and the re-

quirements for aggregate (granular) filters are set out in /ZTV-W 210/. Granular filters are generally un-

bound. The use of bound granular filters should be limited to the protection of relatively small areas which

can be easily inspected. Guidance on filter design is given in /MAG/ and /MAK/.

4.4 Separation layers

Depending on the application, aggregates as specified in /MAK/ or geotextiles as specified in /MAG/ and

/TLG/ may be used as separation layers. Separation layers between flexible linings and armour layers do

not act as hydraulic filters. If a separation layer is installed beneath an impervious lining, its water perme-

ability must be lower than that of the adjacent soil.

4.5 Impervious lining systems

4.5.1 General

The impervious linings used in the standard construction methods are all surface linings. Detailed guid-

ance on the various impervious lining systems, their characteristics and the limits of their application is

11



given in /EAO/. Vertical linings and the impervious cores of embankments are not covered by the stan-

dard methods of construction as they do not form part of the revetment.

4.5.2 Flexible lining systems

The following types of flexible lining are used on waterways:

natural clay liners

permanently plastic linings with clay and hydraulic binders

geosynthetic clay liners (GCL).

The material requirements and tests on flexible linings shall be as specified in /RPW/ and /EAO/.

The specifications of /TLG/ and the recommendations given in /MAG/ that are relevant to impermeable

linings also apply to GCLs.

4.5.3 Inflexible lining systems

The only inflexible lining systems included in the standard methods of construction are those comprising

armourstones fully grouted with an impermeable cementitious grouting material as specified in /MAV/ and

/EAO/. Guidance on the recommended quantities of grouting material is given in /MAV/ which also in-

cludes the requirements for the constituent materials, the required tests and installation.

5 Standard Methods of Construction

5.1 General

Revetments constructed by means of the standard methods may be permeable or impermeable, depend-

ing on the design. A separate lining may be placed beneath a permeable armour or separation layer, or

the armourstone armour layer may be fully grouted with an impermeable material. Any decision on the

need for a sealing system in a revetment must take hydrogeological and safety aspects into account (see

section 5.6.2).

Embedding the revetment to a depth of 1.5 m below the bottom of the waterway is a tried-and-tested

method of toe protection. Under certain boundary conditions the embedment depth may be reduced or a

toe blanket installed (see section 5.3).

A bottom revetment is generally only required if certain components or structures need to be protected,

e.g. impervious lining systems, inverted siphons just beneath the bottom of the waterway or sheet piling

at moorings. It must be checked whether there is a need for bottom revetments in manoeuvring areas.

The local stability (in accordance with sections 7.2, 7.3, 9.2 and 9.3 of /GBB/) of the standard methods of

construction described below will be ensured if the actions due to ship-induced waves and to currents are

taken into account in accordance with the design principles (see section 3) and the effects of anchor cast

are also considered. The global stability of water-side slopes protected by standard revetments shall be

verified, taking into account the relevant imposed loads detailed in section 7.4 of /GBB/.

12



The weight of the granular filter is fully taken into account in the mass per unit area in the geotechnical

design calculations. Significant structurally unfavourable excess pore water pressures do not occur in

granular filters. Stability is governed by the overall thickness of the armour layer and granular filter. This

has been taken into consideration in the standard methods of construction described below.

The weight of armourstone armour layers is governed to a considerable extent by the void ratio of the

layers which mainly depends on the method of installation. Values based on experience are given in Ta-

ble 5.1-1.

Table 5.1-1: Void ratio of armourstone armour layers as a function of the method of installation (based

on depth measurements taken at the highest points of the armourstones)

In-situ density Void ratio, n Method of installation

loose 50 - 55 % The armourstones are dumped under water.

medium 45 %The armourstones are either dumped in dry conditions or

placed directly on the subgrade by an excavator.

dense 30 - 40 %The armourstone layer is finished manually or compacted

by the placement equipment.

The above empirical values apply to armour layers with the thicknesses specified in section 5.2obtained

by depth measurements taken at the highest points of the armourstones (e.g. depth measurements per-

formed with a frame or a conventional staff with a plate foot with a diameter of around 30 cm or higher).

Measurements performed with spherical foot staffs are also common. In this case, the depth is measuredin the gaps between the top layer of stones instead of at the highest point of the stones. The layer thick-

nesses and void ratios obtained by depth measurements performed with a spherical foot staff are lower

than those obtained with a conventional staff (cf. section 8.2). If spherical foot diameters of 9 cm for

CP90/250, 12 cm for LMB5/40 and 15 cm for LMB 10/60 are used, the upper edge of the revetment will be

around 3 cm to 5 cm lower than that measured at the highest points of the armourstones,

The standard methods of construction described below are based on a void ratio of 50 % as shown in

Table 5.1-1.

The requirements set out in /MSD/ for vegetation cover on the embankments of canals built above thelevel of the surrounding countryside must be taken into consideration.

Revetments that do not extend over the full height of the slope (partial revetments) are not covered by the

standard methods of construction as they are customized solutions for particular ground conditions, e.g.

where the lower slope consists of bedrock, rendering it unnecessary to protect the complete slope. If the

lower edge of the partial revetment is embedded in the rock the armour layer thickness of the correspond-

ing standard method of construction may be adopted to provide a conservative design.

13



5.2 Armour layers

5.2.1 Permeable armour layers comprising riprap

This standard construction method comprises an armour layer of riprap as defined in section 4.1placedon a granular or geotextile filter.

Figure 5.2.1-1: Diagram of the cross-section of a permeable armour layer of riprap

Permeable armour layers comprising riprap readily adapt to ground deformations (flexibility). They have

sufficient resistance to ship collisions provided such collisions occur largely parallel to the axis of the ca-

nal.

The stability of revetments constructed by this method depends largely on the size of individual stones

and the thickness of the installed armour layer. These factors are dependent on the density of the stones

and the void ratio of the armourstone layer. Limited movement or even local displacements of stones may

occur under the loads assumed in the design and are taken into account in the calculations for standard

designs in /GBB/ (stability coefficient, BB,= 2.3, see eq. (6-3) /GBB/). A limited degree of maintenancework may therefore be required. Any damage to the revetments should be repaired as soon as possible.

The standard methods of constructing riprap revetments described in this Code will not ensure sufficient

stability (see section 5.6.5) if high flow loads occur in the vicinity of a revetment (e.g. in manoeuvring ar-

eas, waiting areas and at mooring points). The same applies to temporary moorings constructed for the

duration of the execution of the works.

The size of individual stones required for this particular standard construction method ensures that sur-

face erosion due to breaking waves, return currents, slope supply flow and propeller wash, if relevant, is

limited. It does not depend on the in-situ soil but solely on the hydraulic loads referred to. The required

mean sizes, D50, or mean weights, G 50, of the individual stones and the resulting recommended stonesizes determined in accordance with section 4.1are given in Table 5.2.1-1 as a function of the density of

the stones. Ripraps with the required D50- or G50-values ensure that individual stones possess an ade-

quate degree of stability for the loading scenarios described in section 3.

Beyond Table 5.2.1-1 it may in certain circumstances be useful to select the next lowest size class. How-

ever, the lower size class must also comply with the value of D50or G 50required for the relevant density

and the value should be within the range of variations typical of the relevant class as shown in Annex 4.1-

2. This represents a higher requirement for the next lowest size class and may therefore limit its applica-

tion.

14



The minimum thicknesses of the riprap armour layer required to ensure the stability of the revetment will

increase for a particular density of stone as the size class increases (see Annex 5.2.1-3). For this reason,

it may be appropriate to consider whether the next lowest size class with a G50- or D50value greater than

the mean value of that class should be used.

Table 5.2.1-1: Stone diameters, stone weights and size classes required for standard profiles approved

for all types of inland waterway vessels (ES, GMS, SV, GMS) for a range of densities

(2300 3600 kg/m3)

Density

S

Required value

of D50

Required value

of G50

Recommended

size class

[kg/m3] [mm] [kg] -

2300 260 25 LMB 10/60

2650 200 14 LMB 5/40

3000 160 8 LMB 5/40

3600 120 4 CP 90/250

Relatively large stones and correspondingly thick layers are always required in the case of densities, s,

less than 2650 kg/m3. Generally speaking, the density, s, should be not less than 2650 kg/m3.

For intermediate density values, either the stone size for the next lowest density should be selected for

conservative designs or verification by calculation should be performed with the exact density as specified

in /GBB/.

As a rule, densities greater than 3000 kg/m3 can only be achieved with manufactured armourstones

(slags). If such armourstones are used, provisions on environmental impact must be taken into considera-

tion.

After the size class and density of the stones have been specified, the recommended thickness of the

armour layer must be selected from Table 5.2.1-2, taking the soil and type of filter into consideration.

However, the recommended thicknesses of armour layers on flexible linings only correspond to the speci-

fied minimum thicknesses if the groundwater level is lower than the canal water level when lowered byshipping. If this is not the case, the safety against uplift must be verified (see Annex 5.6.2-1).

15



Table 5.2.1-2: Recommended armour layer thicknesses (riprap) for slope and bottom revetments, taking

account of the soils specified in 3.4

Recommended armour layer thicknesses, dD[m]

for revetments with an embedded toe (embedment depth: 1.50 m)

Slope Bottom

Geotextile

as specified in MAG

Granular filter

as specified in

MAK

Geotextile

as specified in

MAG

Granular filter

as specified in

MAK

Density

[kg/m3]

Armourstone

size class

B1, B2, B5* B3 B4 All soils All soils All soils

2300 LMB10/60 0.70 0.85 0.95 0.70 0.70 0.702650 LMB5/40 0.60 0.70 0.80 0.60 0.60 0.60

3000 LMB5/40 0.55 0.60 0.70 0.55 0.60 0.55

3600 CP90/250 0.50 0.50 0.60 0.50 0.60 0.50

*B5 including flexible linings

In addition to the armour layer thicknesses specified in Table 5.2.1-2, the thicknesses of the armour lay-

ers required for slope and bottom revetments if alternative size classes of armourstones are used are

shown in Annex 5.2.1-1. The values take into account the armour layer thicknesses obtained by geotech-nical calculations for slopes (shown in Annex 5.2.1-2) and the minimum thicknesses for slope and bottom

revetments that are required not only to resist ship collision and anchor cast, for example, but also to

ensure the stability of the armourstone layer (Annex 5.2.1-3). In each case, the higher value applies and

is rounded to the nearest 5/100 [m] in Annex 5.2.1-1 and in Table 5.2.1-2. No distinction has been made

between trapezoidal and rectangular-trapezoidal profiles. The recommended armour layer thicknesses

are based on mean values obtained from the results calculated for each type of profile.

The specific requirements stated in section 5.4must also be taken into account in the case of armour

layers placed on flexible linings.

If stones with densities between the values stated in Annex 5.2.1-1 are used, the required thickness of

the armourstone layer can be interpolated, taking account of the minimum thicknesses shown in the dia-

grams in Annex 5.2.1-2.

5.2.2 Permeable armour layers comprising partially grouted armourstones

This standard method of construction comprises a armour layer of dumped armourstones as described in

section 4.1, partially grouted with an impermeable grouting material as described in section 4.2. The ar-

mour layer may be installed on a granular or geotextile filter.

16



Figure 5.2.2-1: Diagram of the cross-section of a permeable armour layer comprising partially grouted

armourstones

Permeable armour layers comprising partially grouted armourstones have only a limited degree of flexibil-

ity which is governed by the quantity of grouting material used. Collisions by ships may result in damage

to the revetment. Any local damage to partially grouted armour layers should be repaired as soon as pos-

sible as it may otherwise become enlarged.

The execution of grouting work under water must be closely monitored /ZTV-W 210/.

The size class CP90/250 is recommended for the construction of partially grouted armour layers. The pro-

portion of fines in the size class must be limited by specifying 90 mm as the minimum value of D 5 in the

contract documents in order to ensure a sufficiently large void size. Stones of class LMB 5/40 may also be

used.

The thicknesses recommended for partially grouted armour layers comprising armourstones of classes

CP90/250 and LMB 5/40 placed on soil types B1 to B5 or a flexible lining are stated in Annex 5.2.2-1. The

values apply to both bottom and slope revetments and take the density of the stones into account. Thearmour layer thicknesses obtained in calculations performed for the geotechnical design of the slope

(shown in Annex 5.2.2-2) and the minimum thickness, which is usually 40 cm for the size classes used,

have been taken into consideration. The higher value, which has been rounded to the nearest 5/100 [m]

in Annex 5.2.2-1, shall apply in each case. No distinction has been made between trapezoidal and rec-

tangular-trapezoidal profiles. The recommended armour layer thicknesses are based on the mean values

of the results calculated for both types of profile.

The specific requirements stated in section 5.4must also be taken into account in the case of armour

layers placed on flexible linings.

If stones with densities between the values stated in Annex 5.2.2-1 are used, the required thickness of

the armourstone layer can be interpolated, taking account of the minimum thicknesses shown in the dia-

grams in Annex 5.2.2-2.

5.2.3 Impermeable armour layers comprising fully grouted armourstones

This standard method of construction comprises a armour layer of dumped armourstones as described in

section 4.1, fully grouted with an impermeable cementitious grouting material as described in section 4.2.

This type of armour layer may only be installed on a geotextile separation layer as described in section

4.4. The weight class LMB5/40 or LMB 10/60 is recommended.

17



Figure 5.2.3-1: Diagram of the cross-section of an impermeable armour layer comprising fully grouted

armourstones

Any underlayers required beneath an impermeable armour layer must be less permeable than the in-situ

ground, but must nonetheless be filter-stable. Otherwise there is risk that due to a local damage to the

impermeable revetment the hydraulic head of the canal would become distributed over a large area below

the revetment, leading to damage due to buoyancy.

Impermeable armour layers comprising fully grouted armourstones have no flexibility. Damage may occur

as a result of ship collision. Any damage to impermeable armour layers must be repaired in order to re-

store their sealing function.

The minimum thicknesses of impermeable, fully grouted armour layers shown in Annex 5.2.3 are suffi-

cient if the groundwater level is always lower than the canal water level when lowered by shipping. If ex-

cess water pressure acts behind the impervious lining, either temporarily or permanently, the thicknesses

of the armour layer required to ensure sufficient safety against uplift must be calculated. The required

minimum thicknesses and examples of the required armour layer thicknesses obtained by calculation are

given in Annex 5.2.3 for various excess water pressures.

5.3 Toe protection

The stability of slope revetments depends, amongst other things, to a great extent on the design of the

toe. On the basis of past experience, an embedded toe is recommended for the standard methods of

construction. For soil types B2, B3 and B4 defined in section 3.4, the standard methods of construction

described in this Code must include an embedded toe with a minimum embedment depth, t, of 1.50 m

below the design level of the bottom of the waterway (see Figure 5.3 1). This also applies to cohesive

soils (soil type B5) with poor resistance to erosion. The toe trench is generally filled with in-situ soil.

18



Figure 5.3-1: Design of the toe protection

Whenever the in-situ soil beneath the revetment is of soil type B1 the embedment depth of the toe may

be reduced to 1 m if the armour layer thicknesses specified in Annexes 5.2.1-3 and 5.2.2-2 are main-

tained or, alternatively, a toe blanket as shown in Figure 5.3 1 is installed. These measures are also pos-

sible in the case of bedrock or firm cohesive soils (B5) that are resistant to erosion.

The standard methods of construction do not consider scour directly at the toe of the slope as experience

has shown that scour caused by shipping only occurs at a distance of several metres from the toe. Never-

theless, if any local scour should occur directly at the toe of the slope it must be remedied during mainte-

nance work. Alternatively, the depth of the toe protection beneath the bottom of the waterway may be

extended by increasing the standard depth of 1.5 m by the forecast depth of the scour or the toe trench

may be filled with material that is coarser than the in-situ soil, such as gravel. The material must prevent

loss of the in-situ soil. Revetments may also be designed individually in accordance with /GBB/ to take

scour into account.

Excavation of a toe trench in highly erosive soils such as soil type B4 may be difficult. In such cases, very

low slope inclinations should be selected for the toe trench and the revetment should be installed imme-

diately after the trench has been excavated.

Sheet pile walls are only installed at the toe in exceptional cases and are therefore not considered in the

standard methods of construction. The actions and resistances on the sheet pile wall must be determined

as specified in /GBB/. The armour layer thicknesses specified for the standard construction methods in

this Code of Practice may be used to achieve a conservative design. Sheet pile walls are stable in thelong term but are a relatively costly method of toe protection. They can only be constructed in driveable

19



soils without obstacles to driving such as the remains of previous revetments. The connection between

the slope protection and the head of the sheet pile wall must be filter-stable. Scour to depths of 1.50 m

(for soil types B2 to B4, depending on the resistance to erosion, but also for soil type B5) or of 0.75 m (for

soil type B1) in front of the sheet pile wall must be taken into account in designs in accordance with sec-

tion 7.2.5.5 of /GBB/.

5.4 Flexible linings

Permeable revetments comprising riprap or partially grouted armourstones (see sections 5.2.1and 5.2.2

respectively) may be installed on a flexible lining as described in section 4.5.2. The use of underlayers

that are more permeable than the in-situ soil is not permitted as the development of any seepage paths in

the plane beneath the flexible lining must be avoided. There is otherwise a risk that the pressure potential

of the water in the canal could become distributed over a large area below the lining if local damage to

the lining occurs, leading to damage due to buoyancy.

If clay liners are used, only geotextile separation layers as described in section 4.4 should be installed

between the lining and the armourstones. If granular filters are used there is a risk that any defects in the

lining occurring after installation of the clay may become filled with filter material, resulting in permanent

seepage points. By contrast, minor defects in the clay liner can heal due to the superimposed load of

the armour layer.

Owing to the lack of experience with geosynthetic clay liners (GCLs) and permanently flexible linings with

clay and hydraulic binders, their use is currently only recommended for low-risk canal sections higher

than the surrounding ground surface which do not require frequent monitoring /EAO/. Up-to-date informa-

tion on the use of such liners can be found in articles published by the BAW (BAW-Briefpublications) oron the BAW website (www.baw.de).

Geosynthetic clay liners are generally installed with a sand mat (a geotextile filled with sand or a mineral

material to weigh it down). The armourstones placed on GCLs may not exceed class LMB5/40, without

oversized pieces of stone, in order to minimize any local unevenness of the bentonite layer caused by the

impact of the armourstones during installation.

Permanently flexible linings with clay and hydraulic binders cannot be installed on inclined surfaces owing

to the flowing properties of the materials.

5.5 Freeboard height

Slope revetments should extend to a height of at least 70 cm above the relevant design water level to

take account of possible wave run-up. The design water level will either be the upper operating water

level, BWo, or the highest navigable water level, HSW.

5.6 Selection of a standard method of construction

5.6.1 General

The choice of a standard method of construction is influenced by the local boundary conditions (e.g.ground, topography, groundwater table) and the requirements (e.g. for loads due to shipping, actions due

20



to leisure activities, environmental impact) that the revetment needs to satisfy. The correct balance be-

tween the various, possibly opposing, factors must be achieved. The following points must be considered

or specified when selecting a standard method of construction.

5.6.2 Requirement for an impervious lining

An impervious lining may need to be installed on a waterway if the lowest operating water level of a canal

is higher than the highest level of the groundwater table, i.e. there is a permanent hydraulic gradient be-

tween the canal and the groundwater (see top diagram in Figure 5.6 1). The following aspects must be

considered:

a) safety of the embankment (achieving an adequate level of safety in load case 1),

b) waterlogging of adjacent land or flooding of buildings,

c) high seepage losses (standard value of permissible seepage losses based on the cost of replacing

lost water: 15 l/s/km),

d) adverse effects on drinking water reservoirs.

Sufficient groundwater data is needed to determine whether an impervious lining is required. The data is

also needed for the preservation of evidence.

Possible methods of constructing the transitional zone between an impervious lining and the permeable

sections of a revetment are shown in Figure 5.6-1 (centre) and must be considered if an impervious lining

is to be installed. It must be taken into account that impervious linings may be exposed to land-side ex-

cess water pressure if installed in the transitional zone between a cutting and a canal section built above

the level of the surrounding ground surface or if the groundwater and canal water levels are subject tolarge fluctuations. The thickness (or weight) of the armour layer will then need to be calculated as speci-

fied in section 7.3 of /GBB/ and the resulting layer thicknesses may be high. Examples of the thicknesses

of armour layers placed on clay liners and GCLs that are required to take account of a range of excess

water pressures are shown in Annexes 5.6.2-1 and 5.6.2-2 (for riprap and partially grouted armour layers

respectively). Irrespective of this, the minimum thicknesses specified in Annex 5.2.1-3 or Annex 5.2.2-3

must be taken into account.

Alternatively, the groundwater level can also be limited to a structurally acceptable maximum level by

technical measures (e.g. drainage, wells) (cf. Case a) in Figure 5.6 1, centre). The possible environmental

impact of such measures must be considered.

21



Selection criterion Type of revetment

BWu > max. GW

BWu max. GW

Impermeable revetment, if appropriate

a.) Impermeable revetment, if appropriate

If the groundwater level is limited to the maximum permitted

value obtained in the verification of safety against uplift (sec-

tion 7.3.3 of /GBB/) at the lower operating water level, BWu,

with the actual or planned weight of the armour layer.

BWu max. GW

and

BWo min. GW

max. GW

min. GW

BWu

b.) Permeable revetmentWater losses occur and must be acceptable. It must be

checked whether the adjacent areas could become water-

logged.

BWo < min. GW

min. GWBWo

Permeable revetment

BWu: lower operating water level

BWo: upper operating water level

max. GW: highest anticipated groundwater level

min. GW: lowest anticipated groundwater level

Figure 5.6-1: Criteria for the selection of an impermeable or permeable revetment

Impervious linings must extend at least 0.50 m above the upper operating water level (BWo) or the high-

est navigable water level (HSW).

5.6.3 Soil classification

The required thickness of the armour layer depends to a large extent on the type of ground on which the

design of the revetment is based. If different types of soil are present or the soil is stratified, it will be nec-

essary to decide which type of soil the design should be based on. The type of soil (classified as type B1

to B5 in accordance with section 3.4) that is selected must always be the one that results in the greatest

armour layer thickness. Thin soil strata (= 1 m) may generally be disregarded.

5.6.4 Requirement for a filter or a separation layer

Reference should be made to either /MAG/ (for geotextiles) or /MAK/ (for granular filters) to determine

whether a filter is required for the planned slope or bottom revetment.

22



Geotextile separation layers should be installed beneath impermeable armour layers and on top of imper-

vious clay liners. In addition, separation layers are required to prevent any mixing or penetration of layers

of different types of mineral particles (e.g. non-cohesive soil placed on soft or pulpy ground).

5.6.5 Selection of an armour layer

If properly executed, the armour layer construction methods described in section 5.2may be regarded as

technically equivalent on reaches and are all applicable in principle. However, each construction method

has particular strengths and weaknesses which must be evaluated when a construction method is se-

lected for a specific project. The requirements for construction and operation (execution, resistance, per-

meability, etc.), for maintenance (ease of inspection, magnitude of damage, cost of repairs),

environmental impact and cost-effectiveness (production and maintenance costs) must be considered.

The loads due to the propulsion and steering units of vessels will be relatively high in manoeuvring ar-

eas(e.g. mooring points and turning basins, lock waiting areas or areas in which the cross-section radi-

cally changes). Such loads result in greater hydraulic actions than on reaches and affect the stability of

individual stones. Designs taking these aspects into account would result in armour layer dimensions far

exceeding those obtained for the standard methods of construction.

Armour layers comprising partially or fully grouted armourstones (sections 5.2.2 and 5.2.3) are recom-

mended whenever slope or bottom revetments are required to provide protection against scour in ma-

noeuvring areas. Other measures are also possible, such as greater water depths at mooring points or

dolphins to ensure a minimum distance between vessels and the banks in order to limit the loads due to

bow thrusters.

Acceleration and stopping zones in lock waiting areas must be inspected to determine if there is a risk ofscour. In the case of modern vessels, the length of the acceleration area can generally be taken to be

around 100 m for self-propelled barges and 200 m for push-tow units. The length of the stopping area

required for self-propelled barges and push-tow units may be taken to be around 200 m and 300 m re-

spectively.

6 Other Methods of Construction

6.1 General

Two other frequently-used methods of construction are described in the following sections. They are:

revetments in combined rectangular-trapezoidal profiles (KRT-profiles) (see section 6.2) and

impermeable, erosion-resistant pavements (see section 6.3).

Although combined rectangular-trapezoidal profiles are regarded as standard cross-sections /RiReS/ the

revetments in such profiles are exposed to lower loads than those in rectangular-trapezoidal or trapezoi-

dal profiles and are therefore not included in the standard methods of construction.

Impermeable pavements used to be installed extensively on waterways. However, they have become

less widespread over the past two decades owing to technological and economic developments and are

therefore no longer regarded as a standard method of construction.

23



Stone-filled wire mesh elements (such as gabions and rock mattresses) have not been included in the

standard methods of construction as they are only used to a small extent, mostly in areas with unusual

geometrical boundary conditions (e.g. as regards the slope inclinations).

6.2 Revetments in combined rectangular-trapezoidal (KRT) profiles

Revetments in combined rectangular-trapezoidal profiles serve to protect the short slopes above sheet

pile walls (see /RiReS/ for standard dimensions) which are exposed to considerably lower hydraulic loads

than the slopes in trapezoidal profiles.

The following methods of construction are possible:

60 cm riprap, minimum class LMB 5/40, on a granular or geotextile filter (see section 5.2.1) or

40 cm partially grouted armourstones of class CP 90/250 (quantity of grouting material as specified in

/MAV/) on a granular or geotextile filter (see section 5.2.2).

6.3 Impermeable erosion-resistant pavements

Pavements are revetments with a homogeneous structure, uniform thickness and a uniform mass per unit

area (e.g. asphalt concrete). Owing to their internal strength, they do not require a protective covering.

Pavements may also be armour layers comprising elements of the same type joined together to form a

continuous area (e.g. interlocking concrete blocks).

Impermeable erosion-resistant pavements must protect and seal the slopes and the bottom of waterways.

They are made of either asphalt or concrete.

Concrete is a rigid material and cannot adapt to deformations of the subgrade. Asphalt possesses a de-

gree of flexibility due to the viscoelastic properties of the bitumen and is able to resist external stresses

such as settlements or compressive or shearing stresses to a certain extent, depending on the tempera-

ture.

Concrete and asphalt pavements are easily damaged by sudden, high levels of local stress such as ship

collisions.

A separation layer must be placed between an impermeable pavement and the in-situ soil or an under-

layer, if used. The occurrence of seepage paths in the plane beneath the impermeable pavement must beavoided. Separation layers or underlayers that are more permeable than the subgrade are therefore not

permitted beneath impermeable pavements as the pressure potential of the water in the canal would be

distributed over a large area beneath the impermeable pavement if the latter suffered local damage. The

transient stresses due to the changes in pressure caused by water-level drawdown would then result in

extensive damage to the impermeable pavement to a depth of around 1 m below the water level due to

buoyancy.

The minimum concrete thicknesses are 15 cm for installation in dry conditions and 20 cm if the concrete

is placed under water.

24



The recommendations given in /EAAW/ apply to the planning and installation of asphalt pavements for

waterways. Generally speaking, they may only be installed in dry conditions.

Impermeable bituminous pavements are susceptible to root penetration. Maintenance work, especially on

asphalt revetments, must include the removal of any vegetation.

The safety against uplift must be verified in accordance with section 7.3 of /GBB/ if the groundwater level

is high.

7 Vegetation Cover in Standard Methods of Construction

7.1 General

Suitable vegetation should be planted or grown from seed on the banks above the water level in all stan-

dard methods of construction for the following reasons:

to encourage colonization of the banks of waterways by flora and fauna

to improve natural environments and landscapes

to increase the stability of the banks by means of root growth

to provide greater protection of shipping against wind

However, possible adverse effects must also be considered, for example:

increased maintenance costs owing to care of the vegetation cover

collapse of banks at the edge of the vegetation cover

damage to the impervious lining due to root penetration

increase in the amount of plant debris (plant material or dead plants) in the navigation channel

decreased visibility for boatmasters due to high vegetation

reduction in the stability of embankments (see /MSD/).

Generally speaking, the standard methods of construction provide only limited opportunities for vegetation

growth. This is due to the specified bank geometries and revetment designs as well as the fact that re-

vetments in the standard cross-sections are exposed to relatively high loads due to shipping.

Vegetation may develop naturally as a result of seed dispersal by the wind or by plant material being

washed up and deposited in the silt that accumulates in the cavities between the armourstones. The es-

tablishment of vegetation cover may be encouraged and accelerated by covering the armourstone layer

with unfertilized topsoil and by sowing grasses and herbs native to the locality or by other means. The

topsoil should not only be placed on top of the armourstone layer but should also fill as many of the cavi-

ties between the armourstones as possible. However, topsoil is likely to be rapidly washed away in the

zone of fluctuating water levels due to the hydraulic actions on the bank. It should therefore only be

placed on slopes above a height of at least 50 cm above the normal or mean water level.

25



The stability and rate of vegetation growth can be increased if the cavities in armourstone layers are

completely filled with alginate-enriched topsoil. The topsoil mixture is produced in specialized mixing

plants and consists of finely sieved topsoil to which alginate with montmorillonite colloids (i.e. bentonite)

has been added. Mixing the alginate-enriched topsoil with water produces a flowable clay-humus complex

with thixotropic properties that can be pumped into the cavities between the stones (see p. 16 of /STLK207/). When installed, the alginate-enriched topsoil has a higher resistance to erosion than normal topsoil

and can therefore be placed in the armour layer directly above the normal or mean water level.

Furthermore, planting woody plants or cuttings (e.g. of shrubby species of willows) or plant plugs (reeds

or other herbaceous perennials of around 15 cm in length and diameter, with the root ball frequently

wrapped in coir matting) in the unfertilized topsoil or alginate-enriched topsoil placed in the cavities be-

tween the dumped stones is recommended where technically feasible and provided that the stability of

the revetment is not jeopardized. Plant plugs should be planted in rows parallel to the bank (with the dis-

tance between the rows being approx. 30 40 cm). The spaces between the plants should also be

approx. 30 40 cm.

The different moisture requirements of the various types of vegetation must be taken into consideration.

Plants such as the common reed or yellow iris thrive in wet conditions such as those found at normal or

average water levels and up to around 10 cm to 20 cm above them. Sedges and marshland perennials

can grow in slightly drier conditions, but do not thrive particularly well in locations higher than 30 cm to

40 cm above the normal or average water level.

The correct light conditions are also important for successful vegetation growth. Reeds only thrive if there

is not too much shade on the banks. Woody plants may adversely affect the growth of grasses, herbs or

reeds sown or planted nearby, depending on the light conditions.

Successful vegetation growth depends to a large extent on local conditions so that it is not possible to

give any general recommendations on which types of plant to select. It is recommended that vegetation

plans indicating suitable types of plants be drawn up by experts.

Generally speaking, plants that are native to the locality and suitable for the site should always be used.

Seeds and plant cuttings for a particular revetment should be sourced from the locality in which they are

to be used.

Vegetation cover should always extend over continuous areas. Solitary plants may result in local in-

creases in flow loads which would adversely affect the stability of the individual plants.

7.2 Permeable armour layers comprising riprap or partially grouted armourstones as de-

scribed in sections 5.2.1and 5.2.2respectively

The growth of vegetation on permeable armour layers comprising riprap or partially grouted armourstones

depends on a variety of factors and boundary conditions. In addition to the points discussed in section

7.1, other important factors include the thickness of the armour layer, the stone sizes, the size of the cavi-

ties in the stone layer, the stability of the armour layer, including its resistance to the displacement of

stones, and the different wave loads occurring on the various types of waterway.

26



Vegetation cover may be established by sowing grasses and herbs native to the locality or planting reeds,

herbaceous perennials or woody plants, for example, in topsoil or alginate-enriched topsoil placed on the

armour layer (see section 7.1).

Wave action may cause local displacement of the stones in riprap armour layers, resulting in damage toplants. Stone displacement rarely occurs in partially grouted armour layers. On the other hand, the sur-

face on which plants can take root is smaller than in the case of riprap armour layer. Compliance with the

recommended quantity and distribution of the grouting material specified in /MAV/ is required in order to

optimize the conditions for vegetation cover on partially grouted armour layers.

The opportunities for the establishment of fauna provided by the empty cavities between the stones in the

zone of fluctuating water levels and under water depend on the void ratios of the armour layer and stone

surface available for colonization, with higher void ratios and a larger available stone surface being more

favourable. Compliance with the recommended quantities and distribution of grouting material specified in

/MAV/ is therefore an important factor if fauna is to colonize the banks.

7.3 Impermeable armour layers comprising fully grouted armourstones as described in section

5.2.3

Root penetration is generally ruled out on fully-grouted impermeable armourstone revetments owing to

the absence of voids in the armour layers. As a result, grass and herbaceous plants are unable to grow

on such revetments.

It is not permitted to plant woody perennials or reeds on the slopes, and any vegetation of this kind must

always be removed immediately.

7.4 Guidance on vegetation cover on flexible linings

Grasses and herbs may be sown on revetments with flexible linings. Other types of vegetation must be

planted at a sufficient distance from the lining (see /MSD/). This is due to the fact that there are several

varieties of woody plants and reeds whose roots are able to penetrate flexible linings. Undesirable plant

growth on a lining can lead to high maintenance costs. The types of undesirable vegetation that could

grow on the lining must be assessed in advance and maintenance planned accordingly.

8 Guidance on Invitations to Tender, Execution of the Works, Quality Controland Maintenance

8.1 General

Invitations for tenders for slope and bottom protection systems must be based on /STLK 210/, taking ac-

count of the following codes of practice in particular:

Code of practice Use of standard construction methods for bank and bottom protection on inland

waterways/MAR/

Code of practice Use of geotextile filters on waterways /MAG/

Code of practice Use of granular filters on waterways /MAK/

27



Code of practice Use of cement-bonded and bituminous materials for grouting armourstones on

waterways /MAV/

Recommendations for the use of lining systems on the beds and banks of waterways/EAO/

The following sections 8.2 and 8.3 give additional guidance on issuing invitations to tender and on the

execution of the works.

In addition, it must be explicitly stated which parts of the above codes of practice would have to be com-

plied with under the contract for execution of the works.

8.2 Invitations to tender

8.2.1 General

The points stated in section 8.2must be included in the contract documents at the appropriate places.

In additional to the general specifications, compliance with the technical contract conditions set out in

/ZTV-W LB 210/ must be stipulated in the contract for execution of the works.

The properties of the materials must be specified by the Client. The requirements must be specified in the

invitation to tender in accordance with the guidance given in /ZTV W LB 210; MAK; MAV; MAG/.

The methods use

bawcodeofpractice bank bottom protection mar 2008

Documents

bundesanstalt fr gewsserkunde

toe protection

baw code of practice

bundesministerium fr

impermeable armour layers

baw codes of practice

filter layers

separation layers