•· CIVIL WORKS CONSTRUCTION

GUIDE SPECIFICATION

z.S. SU/

.,CW-02541 O.S8 FEB 1980 '

WIRE MESH GABIONS e (SLOPE AND

. CHANNEL PROTECTION)

DEPARTMENT OF THE ARMY CORPS OF ENGINEERS • . OFFICE OF THE CHIEF OF ENGINEERS

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CIV!L WORKS CONSTRUCTION . GUIDE SPECIFICATION , ! .

. ,v • I"'?~

FOR

WIRE MESH GABIONS (SLOPE AND CHANNEL PROTECTION).

Instructions

CW-02541 February 1980 ·

.. L Th.is guide specification is intended to facilitat'e the preparation •. · · . and review of specifications for the procurement and .i.n~tallation o-f

st~~l wire mesh gabion units used as a measure of prqtaction against erosion forces of parallel stream flow. The instaUati,on erocedures

· contained herein do not apply to the field assembly o( gabion units into structural members intended to resist lateral e~'th or water ·

·. forces.

2. The use of gabion units ~s an erosion protection.feature is generally applicable to earth slopes th11t are IV on 2H or flatter.· For slopes steeper than IV on 2H, special precaution .and design attention should be given to the use of anchor pipes, pegs, · intermediate gabion anchor walls, or counterfort members to resist displacement during and following construction or slope inundation •

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3. Construction experience has shown th.it the PVC c~C.ing of gabion . wire mesh and lacing wire has split during the manipulation of assembly, when the materials were assembled after having been stored in free#ng temperatures. In order to preserve the ductility of the · PV.C coated mesh and lacing wire during basket assembly and stone filling, prec~tionary statements should be added to these specifications as appropriate, to insure their protective stor~ge. In· addition, provisions should be added when applicable to prevent placed but unfiiled basket .units from being subjected to freezj.ng temperatures and then filled during a subsequent working shift. · " ·

4. The bedding layer beneath gabion or revetment mattress units · should be a minimum of 6 inches thick and designed as a filter when the slope or any portion of the slope being protected consists of soils susceptible to erosion. To assure sufficient relative perme~bili ty arid drainage, to prevent the migration of slope materials into t:he bedding layer, and for the reterition of bedding materials by the overlying gabion units, the particle size distribution of the bedding material should conform to the following criteria •.

a. D15B > 5 D15S

b. D15B< ·s D85S

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CW-02541 Feb 80

C • Dl5G < 5 D85B

d. DSOB < 25 D50S

where D15B = the 15% size of the bedding material (Max. D15) D50B = the 50% size of the bedding material (Max. D50) D85B = the 85% size of the bedding material (Min. D85) D15S .. the 15% size of the slope material to be protected

(Min.DIS) D50S = the 50% size of the slope material to be protected

(Min.D50) D85S = the 85% size of the slope material to be protected

(Min.DBS) D15G .. the 15% size of the gabion stone fill (Max. D15)

Stone filled units have a potential for becoming impermeable. For extreme cases of long protected slope distances, or any application where large volumes of seepage or captured runoff is anticipated, design consideration should be given to the carrying capacity of the bedding and the need for providing pipe drains through the gabion units.

5. Although the prov1s1on of a pervious bedding layer beneath gabion slope protection is preferred particularly for slopes steeper than IV on 2H, construction economy may be achieved in some cases through the use of filter fabric. The specifications for the filter fabric should be in accordance with the instructions contained in Guide Specification· CW-02215, November 1977.

6. Instructions dealing with preparation and submission of specifications are in ER 1110-2-1200.

7. Capitalized instructional notes to the Contracting Officer will be deleted from the text of the contract specifications. Alternate paragraphs that are not used will be deleted, as well as designations such as "Alternate l," etc.

8. A single asterisk is used throughout the text to indicate portions wich should be deleted when inapplicable.

9. Standards and other specifications referenced in this guide specification should be checked for obsolescence and for dates and applicability of amendments and revisions issued subsequent to the publication of this guide specification. Part 2 of EP 1110-1-5, "Index to Publications Referenced in Guide Specifications for Civil Works and Military Construction" is revised and distributed quarterly by OCE as an aid in dating and checking such references.

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JO~ . Copies of· _th{a baste guide specific;ation may be: ;equishi.oned' from;>OCE ,Public;atioris Depot, · 890 South Pickett Street; Alexandria, Virgirii~/ 22304<-(703/ 274.,;7771 L · -.· ·· · NOTE: - THESE INSTRUCTIONS ARE FOR INFORMATION ONLY

. AND .WILL WT BE INCLlDED 'IN lllAFTS ·OF SPECIFlCATIONS ' .· SUBMITTED FOR APPROVAL. . •. .

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CIVIL WORKS CONSTRUCTION GUIDE SPECIFICATtON

.FOR

WIRE MESH GABIONS

· cw..:.02541 Feb 80 ·

. (SLOI>E AND CHANNEL PRO'ttCTION)

Paragraph

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5 5.1 . (Alternate 1)

5 .1 (Alternate 2)

5 .2 ·. · s.2.1 5~2.2 5.3

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9.

10 10.1 . 10.2

TABLE OF CONTENTS

SCOPE . .

APPLICABLE PUBLICATIONS .

GENERAL

DESCRIPTION

.MATERIALS Galvanized Steel Wire Mesh

Gabions · PVC Coated Galvanized Steel

Wire Mesh Gabions . Stone Fill Quality . Gradation · Bedding Material . Acceptance Requirements .

··FOUNDATION PREPARATION

. BEDDING. PLACEMENT.

FABRICATION (PVC Coated) Galvanized Steel

Wire Cabions ASSEMBLY AND.INSTALLATION

MEASUREMENT AND PAYMENT Bedding Material Gabions .• · ·

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Section 2

Wire· MeshGabions ·

cw..:02541 _ Feb 80

L · SCOPE~ 'ttd.s ._section, in co~junction with the contract dr~wings, . . . .

*(Except materials and equipment

specified to be furnished by the Government). . . . , . . . . .

· 2 . APt>LICABLE PUBUCATIONS. The following publications of the

issu¢Ei" listed beJow, but referred to thereafter by basic designation

-. only~ -form a part of this sp~ification to the extent .indicated by the

referenc~s thereto:

2 . 1 F'eder~t Sped : ications -(Fe-d. Spec.). · - . . . . . QQ-W-46lg Wire , Steel, . . .

-Carbon -(Rou~d, _'Bare, and Coated)

2. 2 Anl~rican Society for- Testing and Materials (ASTH) . .

ASTM A90 Weight of Coating on Zinc-Coa~ed Iron or Steel · Articles ·. ' , · ·: · \ ·. , • . . . .

~STM A239 Locating _ the Thinnest Spot in a Zinc (Galvanized) ·

_ Coating on lron or .Steel Articles by the Preec~ Test (Copper

Sulfate Dip)

.ASTM G23 Operating Light and Water Exposure Apparatus (Carb<;>n · . . ' ' . . \ ' . . . . · .. . . . . . . . . .

Arc T~pe) _for Exposure of Nonmetallic Materials _ _ .

. . .

3~ GENERAL. _The work under this specification includes _furnishing,

.assembling, filling, and tying open wire mesh rectangular compartmented . . ..:. . ·. ' • . ·. . . . . .· . . · . . . · ' • .gabions placed on a prepared surface of bedding material ae apecified -

herein, · and in accordance with the lines, grades and dimensions shown on

the drawings or otherwise established in the field by the Contracting

Officer. -

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CW-02541 Feb 80

4. DESCRIPTION. As described in this specification, gabion units

consist of compartmented rectangular basket containers with a minimum

dimension greater than 12 inches, fabricated from *(galvanized steel)

(PVC coated galvanized steel) triple twisted wire mesh with hexagonal

openings,· and filled with stone.

5. MATERIALS.

*5.1 (Alternate 1) Galvanized steel wire mesh gabions. Gabion

basket units shall be of nonraveling construction and fabricated from

a triple twisted hexagonal mesh of hot dipped galvanized steel wire

having a minimum diameter of 0.118 inches after galvanization. The

steel wire used shall be galvanized prior to fabrication into mesh.

All gabion diaphragm and frame wire Rhall equal or exceed Fed. Spec.

QQ-W-46lg, possess medium tensile strength, and a Finish 5 Class 3

zinc coating of not less than 0.80 oz/sq. ft. of uncoated wire

surface. The weight of zinc coating shall be as determined by ASTM

test designation A-90. The uniformity of coating shall equal or

exceed four one minute dips by the Preece Test, ASTM test designation

A239. Mesh openings shall be hexagonal in shape, and uniform in size

measuring not more than approximately 3 1/4 inches by 4-1/2 inches.

Selvedge or perimeter basket frame wire shall be of heavier gauge than

the wire mesh with a minimum diameter after galvanization of 0.150

inches. Wire used for lacing or as :internal connecting wire within

basket cells may be of soft tensile strength and of lighter gauge with

a minimum diameter after galvanization of 0.0866 inches.

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CW-02541 Feb SO·

*5 .1 (Al ternai:·J 2) · PVC Coated Galvanized Steel Wire Mesh Gab ions.

PVCcoatedgabion basket units shall be of nonraveling. construction, . .· .

fabrica.ted "from a triple twisted hexagonal mesh of hot dipped·

galvanized steel wh-e•having a minimum diameter of 0.105.inches .after

galvanization, ·and ·additionally coated with .a minimum of 0.020 inches·

of PVC. The steel core wire used shall be galvanized and PVC coated

prior to fabrication into mesh •. The core wire of all gabion diaphragm

and frame' components shall equal or exceed Fed. Spec. QQ,;..W-46lg,

possess medium .. tensile strength, and a Finish 5 Class 3 coating of not

less than0.08 oz/sq. ft. of uncoated wire surface. Mesh openings

·. shall be hexagonal in shape and .uniform in size measuring approximately

3-1/ 4 inches by 4-1/ '2 inches. Selvage or perimeter basket frame core

wire· sha11 be o'f heavier gauge than that of the wire mesh with a

minimum diameter after galvanization of 0.132 inches, and an overall

diameter•. (core wire plus PVC coating) of 0.174 inches. Coated wire

used for lacing or as internal connecting wire within basket cells may

be.of soft tens_ile strength and an overall·diameter (co,re wire plus·

PVC coating) of O .127 inches. The PVC coated wire of all gabion

components shall be resistant to the destructive effects cif immeuion

in acidic/ salt, or polluted water, exposqre to ultraviolet light and . . . .

abrasion, and retain these characteristics after a period of not less

than 3,000 hours under test in accordance with ASTM Test Designation

G-23 •

CW-02541 Feb 80

5.2 Stone Fill.

5.2.1 Quality. Stone shall be durable and of suitable quality to

insure permanence in the structure and climate in which it is to be

used. It shall be free of cracks, seams, and other defects that would

tend to increase unduly its deterioration from natural causes or reduce

its size to that which could not be retained in the gabion baskets.

The inclusion of objectionable quantities of dirt, sand, clay, and

rock fines will not be permitted. The sources from which the

contractor proposes to obtain the material shall be selected well in

advance of the time when the material will be required in the work.

*(Selected stone from the required excavation may be used if

satisfying all requirements as to quality and dimensions). Suitable

samples of stone fill material shall be submitted to the Contracting

Officer for approval prior to delivery of any such material to the

site of the work. Unless otherwise specified, all test samples shall

be obtained by the contractor and delivered at his expense to the

Contracting Officer at the job site at least 30 days in advance of the

time when the placing of the stone-filled gabions is expected to

begin. Suitable tests and service records will be used to determine

the acceptability of the stone. In the event suitable test reports

and service records are not available, as in the case of newly

operated sources, the mat erial shall be subjected to such teats aA are

necessary to determine its acceptability for use in the work. Tests

to which the material may be subjected include petrographic analysis,

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CW-02541 . . . Feb- 80 . ···

. . sp·ec~fic grav1ty•, absorpti~n, wetting and · dry in~, freezing, . tha-wing, ·

~net such o.the,r' Jes~.s ,ii~ may he considered necess11ry to :c1emc>nt1trotti to

the .safi.sfactionof th~ Contracting Officer that the .il)ated&ls are . ·. ' ' · _ . · .. . ; _ ' . . . : . . . . . . . '

.· · acceptable fen:.' use in the wor~. All tests will be made by or. under

the supervision of the Goverm1~erit: and at its expense.

·. 5.2.2 G~adation. . . . $tone fill used in the gabions shall be a . . . . ~ . .

~n.:.gr~ded mixture ~ith . sizes ranging ·between 4 inches and 8 inches,

. · based . on u. s. $tarid11rd square mesh sievu. · No stone shall have . . ..

minimum dimerision ' less than 3 inches •

. ·· .. . NO~: · . FOR BASKET. UNITS WIT!-\ INTERIOR CELL_. ·.DIMENSIONS LARGER THAN 3 · FEET WIDE BY · 3 · FEET DEF;P, STONE FILL WITH MAXIMUM DIMENSIONS_ . RANGING B.ETWEEN 4 . INCHES AND 12 INCHES MAY BE . . . USED, WITH ~ STONES PERMITTED HAVING A MINIMUM ·

· • DIMENSION LESS THAN 3. INCHES_: . . . .

5 .3 · Bedding Material. . · The'. material shall be c~aiposed of tough . . •, . .

.durable parti~les, ;easonably free . froin thin, flat, and el<,ngate~

. pieces, and coritain no . organic n,atter o; soft friable parl:ieles in

. .. quantities con~idered objectionable by the Contracting iOfficer.

Beddirig ma~~~iai shall _coniist of sartd and gravel or crushed stone, . . -.

we 11 gnded between the prescribed limits listed be lor,,, and c_onform to

the requirements,· of J>St°/l 5. 2 .T as to quality.

Siev~ Des1g11ations . Percent hy We~ght .

U. S. Standa.rd Square Mesh Passing

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CW-02541 Feb 80

*(Filter fabrics shall meet the provisions of Section , plastic ----filter fabric.)

5.4 Acceptance Requirements. For each shipment of materials to

the site, the Contractor shall furnish the Contracting Officer, in

duplicate, a manufacturer's certificate or affidavit signed by a

legally authorized official from the company manufacturing the gabion

units, that all material contained within that shipment meets the

composition, physical, and manufacturing requirements stated in this

specification.

6. FOUNDATION PREPARATION. After excavation or stripping to the

extent indicated on the drawings or as directed by the Contracting

Officer, remaining loose or otherwise unsuitable materials shall be

removed and all depressions carefully backfilled artd compacted using

suitable materials from adjacent required excavation. Any buried

debris protruding from the foundation that will impede the proper

installation and final appearance of the gabion layer shall also be

removed, and the voids carefully back-filled and compacted as directed

by the Contracting Officer. Immediately prior to placing the bedding

material, the prepared foundation surface shall be inspected by the

Contracting Officer, and no material shall be placed .thereon until

that area has been approved.

7. BEDDING PLACEMENT. Bedding material shall be spread uniformly

on the prepared foundation surface in a manner satisfactory to the

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CW-02541 Feb 80

Contra~ting Qfficer, and to the slopes, lines, and gt'ades as indicated

on the dra~ings 5>r as directed, Placfog of bedding material by

· methods which will tend to segregate par tic.le sizes will not be ' . . . .

perinitted •. Anf damage to the foundation· surface dur.ing bedding . . .

placement shall be repaired before proceeding with the work.

Compaction of the bedding materials will not be required, but it shall

be finished to present a reasonably even surface free from mounds or windrows.

8, FABRICATION.

*8.1 (PVC Coated) Galvanized Steel Wire Mesh Gabions, . Gabions

shall ."?e fabricated in such a manner tbat the sides, ends, lid, and

diaphragms.can be assembled at the construction site into rectangular

baskets of the· sizes_ specified and shown on the drawings, Gabions

shall be of sing-le unit . construction, i.e., the hue, ·lid, ends, and

· sides _shl!._11 be either woven into a single unit or one edge of these

members ·connected.tq the base section of the gabion in such a manner . ' . . . ' .

that strength and flexibility at the point of connection: is at least

equal to that Of the mesh. Where the length of the gabion exceeds one

·. and one-half its horizontal width, the gab ion shall be equally divided

by· diaphraglllS of the same mesh and gauge as the body of . the · gabions, .·

in.to cells whose length does not exceed the horizontal width. The

gabionshall. be furnished with the necessary diaphragms secured in

proper position on the _base · in such a manner that no additional tying

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W LIBRARY·

· ater & Po . R. · D we, esources Servic..F,1

enver, Colorado

CW-02541 Feb 80

at this juncture will be necessary. All perimeter edges of the mesh

forming the gabion shall be securely selvedged so that the joints

formed by tying the selvedges have at least the same strengthas the

body of the mesh. Lacing wire or connecting wire shall be supplied in

sufficient quantity for securely fastening all diaphragms and edges of

the gabion.

9. ASSEMBLY AND INSTALLATION. Empty gabion units shall be

assembled individually and placed on the approved surface to the lines

and grades as shown on the drawings or as directed by the Contracting

Officer, with the sides, ends, and diaphragms erected in such a manner

to insure the correct position of all creases and that the tops of all

sides are level. All adjoining empty gabion units must be connected

by tie wire lacing along the perimeter of their contact surfaces in

order to obtain a monol'ithic structure. Lacing of adjoining basket

units shall be accomplished by continuous stitching with alternating

single and double loops at intervals of not more than S inches. All

lacing wire terminals shall be securely fastened. The use of

expedient clip connections for this purpose as final lid closing will

not be permitted. The initial line of basket units shall be placed on

the prepared bedding layer surface in a direction parallel to stream

flow, and partially filled to provide anchorage against deformation

and displacement during filling operations. After adjoining empty

basket units are set to line and grade and common sides with adjacent

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CW702541 . · 'Feb 80

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units thorough1y: ,.tic-ed, they shall be placed in tension and stretched .·

. to remove a~Y . kinks fro01 ' ~he• mesh and to a uniform al ignmerit. The

:stiE!t:ching ~f empty hasket units shall be .accomplish~d in. such a . . •.· . . .· .. . . . .

, mann~t as t~ p~e~ent: : any pos;ible unraveling • . Stone filling

ope~ations . shall carefully proceed with placement by hand or machine

·· so ·as not to d~mage . galv~nized *(or PVC) wire coating, . to assure a

minimum of voids b.etween the stones, and the maintenance of, alignment

throughout the filling proces.s. Undue bulging of the mesh shall be

avoided.. To avoid localized . deformation, the basket units in any row

are to _be filled. in, stage~ consisting of maximum 12 inch courses, and

at no time shall any cell be filled to . a depth exceeding one foot · more

.thai:i· the · adjoining cell. The maximum height from which the. stone may

· be dro.pped into the basket units shall be 36 inches. :.*(For gab'ion

unitfi in excess o.f 2. feet in thickness, ·a minimum 0£ two uniformly

.. spaced c~nnect~ng wir.eir shall be placed between each stone layer in

all ceJls, connecting compartment faces that are parallel to_ stream· . ' . . . . ' . . . . .

flow. Connecting. wires shall be looped ~round one mesh .opening . at

each basket face and the wire terminals shall be securely twisted to ..

prevent · their loosening) .•

NOTE: FOR GABION UNITS ·IN EXCESS OF 4 FEET IN THICKNESS, AND PLACED IN HORIZONTAL OR NEAR HORIZONTAL POSITION TO RESIST HIGH VELOCITY

' FLO'W, OR AS PART OF A STILLING BASIN FEATURE; A M,INIMUM OF TWO · UNIFORMLY SPACED VERTICAL . CONNECTING Wm.ES PER CELL LINKING nIE

· FOUNDATION MESH TO BASKET LID MESH SHOULD BE SPECIFIED.

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CW-02541 Feb 80

Along all exposed faces, the outer layer of stone shall be carefully

placed and arranged by hand to insure a neat and compact appearance.

The last layer of stone shall be levelled with the top of the gabion

to allowfor the proper closing of the lid and to provide an even

surface that is uniform in appearance. Lids shall be stretched tight

over the stone fill using crowbars or lid closing tools, until the lid

meets the perimeter edges of the front and end panels. The lid shall

then be tightly laced with tie wire along all edges, ends, and

internal cell diaphragms by continuous stitching with alternating

single and double loops at intervals of not more than 5 inches .

Special attention shall be given to see that all projections or wire

ends are turned into the baskets. Where shown on the drawings or as

directed by the Contracting Officer, or where a complete gabion unit

cannot be installed because of space limitations, the basket unit

shall be cut, folded, and wired together to suit existing site

conditions. The mesh must be cleanly cut and the surplus mesh cut out

completely, or folded back and neatly wired to an adjacent gabion

face. The assembling, installation, filling, lid closing, and lacing

of the reshaped gabion units shall be carried out as specified above.

10. MEASUREMENT AND PAYMENT.

10.1 Bedding Material. The quantity of bedding material to be

paid for will be computed from the theoretical bedding thickneBs as

specified herein or as shown on the drawings, and the area8 acceptably

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placedcwh~re) shown on the drawings or staked in the, field. Payment

• for b_edding will be made at the contract unit price per: cubic yard for ' ' '

. . paym~nt _ ltem No. uBedding Material," which price shall :i_nclude ' ' '

all costs of furnishing, hauling, placing, and maintenance of t~e

· bedding layers .untilplacement of the gabion cover is co~pleted and

accepted. · No payment will be made for excess thickness of bedding

layers or for material required to replace material lost by rain wash,

. wind erosion,.· or otherwise, except for additional bedding material

ordered in writing by the Contracting Officer.

10. 2 Gahions. ·· Cab ions meeting the requirements of these

specificaHon:s and acceptablyplaced within the limits indicated on ' ' '

the drawings or otherwise established in the field by the Cont:raCting . . -• . . ·-.

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· Officer, will be measured by the c_ubic yard of stone-filled gabions in.·

place. Payment will be made at· the contract unit price per cubic .yard

· under payment· Item No. "Gabion Protection" which price shall

include the co~ts of furnishing, assembling, and placing the wire

baskets, the stone fill, and all other materials, labor, equipment,

· too ls, supplies, and incidental cos ts in connection with compleHng

th is . item. of work.

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