A06_Section_J_Number_2-_Titsworth_Ditch_Gabion_Basket_Weir_Standard_Construction_Specifications.pdf

Bureau of Land Management

Titsworth Ditch

Gabion Basket Weir

Standard Construction Specifications

Bureau of Land Management Roswell Field Office

Roswell, New Mexico

TABLE OF CONTENTS TOC - 1

TABLE OF CONTENTS

DIVISION 01 - GENERAL REQUIREMENTS

011000 SUMMARY

DIVISION 31 – EARTHWORK

311000 SITE CLEARING

312000 EARTH MOVING

313600 GABIONS

APPENDIX A – MACAFERRI SPECIFICATIONS

SECTION 011000 SUMMARY 011000-1

SECTION 011000 - SUMMARY

PART 1 - GENERAL

1.1 RELATED DOCUMENTS

A. Construction Plans and general provisions of the Contract, including General and Supplementary Conditions and other Division 01 Specification Sections, apply to this Section.

1.2 SUMMARY

A. Section Includes:

1. Project information.

2. Work covered by Contract Documents.

3. Work restrictions.

4. Miscellaneous provisions.

1.3 PROJECT INFORMATION

A. Project Identification: Titsworth Ditch Gabion Basket Weir.

1. Project Location: Lincoln County, New Mexico. Near the Village of Lincoln. North of La Cuesta Lane on the Rio Bonito River. 33°30'26.2"N 105°24'09.5"W

B. Owner: Bureau of Land Management

1. Owner's Representative: Roswell Field Office. Michelle Bell (575) 627-0235, Michael McGee (575) 6237-0340. Contracting Officer and Contracting Officer’s Representative will be named after award of contract.

1.4 WORK COVERED BY CONTRACT DOCUMENTS

A. The Work of Project is defined by the Contract Documents and includes, but is not limited to, the following:

1. Construction of gabion basket wall across Rio Bonito at specified location. The purpose of this wall is to divert water to existing irrigation diversion pipe.

B. Type of Contract:

1. Project will be constructed under a single prime contract.

SECTION 011000 SUMMARY 011000-2

1.5 WORK PERFORMED BY OWNER

A. Cooperate fully with Owner, so work may be carried out smoothly, without interfering with or delaying Work under this Contract or work by Owner. Coordinate the Work of this Contract with work performed by Owner.

B. Concurrent Work: Owner will perform the following construction stakeout operations at Project site. Those operations will be conducted simultaneously with Work under this Contract.

1. Owner shall direct Contractor as to location of gabion wall along the river. Contractor will not need to perform stake-out operations, however, Contractor is responsible for ensuring that gabion wall is installed so that top of wall in river matches elevations as indicated on Construction Plans.

1.6 CONTRACTOR'S USE OF SITE AND PREMISES

A. Unrestricted Use of Site: Contractor shall have full use of Project site for construction operations during construction period. Contractor's use of Project site is limited only by Owner's right to perform work or to retain other contractors on portions of Project.

B. Condition of Existing Grounds: Maintain portions of existing grounds, landscaping, and hardscaping affected by construction operations throughout construction period. Repair damage caused by construction operations.

1.7 WORK RESTRICTIONS

A. Comply with restrictions on construction operations.

1. Comply with limitations on use of public streets, work on public streets, rights of way, and other requirements of authorities having jurisdiction. Access to this project is off of La Cuesta Lane. The speed limit on La Cuesta Lane is 10 mph.

B. On-Site Work Hours: Limit work to between 7 a.m. to 5 p.m., Monday through Friday, unless otherwise indicated. Work hours may be modified to meet Project requirements if approved by Owner and authorities having jurisdiction.

1. Weekend Hours: Only by prior written approval of Owner.

2. Early Morning Hours: Only by prior written approval of Owner.

PART 2 - PRODUCTS (Not Used)

PART 3 - EXECUTION (Not Used)

END OF SECTION 011000

SECTION 311000 SITE CLEARING 311000-1

SECTION 311000 - SITE CLEARING

1.1 RELATED DOCUMENTS

A. Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division 01 Specification Sections, apply to this Section.

1.2 SUMMARY

A. Section Includes:

1. Protecting existing vegetation to remain.

2. Removing existing vegetation.

3. Clearing and grubbing.

4. Temporary erosion and sedimentation control.

1.3 DEFINITIONS

A. Subsoil: Soil beneath the level of subgrade; soil beneath the topsoil layers of a naturally occurring soil profile, typified by less than 1 percent organic matter and few soil organisms.

B. Surface Soil: Soil that is present at the top layer of the existing soil profile. In undisturbed areas, surface soil is typically called "topsoil," but in disturbed areas such as urban environments, the surface soil can be subsoil.

C. Topsoil: Top layer of the soil profile consisting of existing native surface topsoil or existing in-place surface soil; the zone where plant roots grow.

D. Vegetation: Trees, shrubs, groundcovers, grass, and other plants.

1.4 MATERIAL OWNERSHIP

A. Except for materials indicated to be stockpiled or otherwise remain Owner's property, cleared materials shall become Contractor's property and shall be removed from Project site.

1.5 FIELD CONDITIONS

A. Improvements on Adjoining Property: Authority for performing site clearing indicated on property adjoining Owner's property will be obtained by Owner before award of Contract.

1. Do not proceed with work on adjoining property until directed by Owner.

SECTION 311000 SITE CLEARING 311000-2

B. Salvageable Improvements: Carefully remove items indicated to be salvaged and store on Owner's premises where indicated.

C. Utility Locator Service: Notify NM811 for area where Project is located before site clearing.

D. Soil Stripping, Handling, and Stockpiling: Perform only when the soil is dry or slightly moist.

PART 2 - PRODUCTS

NOT USED

PART 3 - EXECUTION

3.1 PREPARATION

A. Protect existing site improvements to remain from damage during construction.

1. Restore damaged improvements to their original condition, as acceptable to Owner.

3.2 TEMPORARY EROSION AND SEDIMENTATION CONTROL

A. Provide temporary erosion- and sedimentation-control measures to prevent soil erosion and discharge of soil-bearing water runoff or airborne dust to adjacent properties and walkways, according to requirements of authorities having jurisdiction.

3.3 CLEARING AND GRUBBING

A. Remove obstructions, trees, shrubs, and other vegetation to permit installation of new construction.

1. Do not remove trees, shrubs, and other vegetation indicated to remain or to be relocated.

B. Fill depressions caused by clearing and grubbing operations with satisfactory soil material unless further excavation or earthwork is indicated.

3.4 DISPOSAL OF SURPLUS AND WASTE MATERIALS

A. Remove surplus demolished materials, vegetation and waste materials including trash and debris, and legally dispose of them off Owner's property.

END OF SECTION 311000

SECTION 312000 EARTH MOVING 0312000-1

SECTION 312000 - EARTH MOVING

PART 1 – GENERAL

1.1 SUMMARY

A. Section Includes:

1. Excavating and backfilling for buildings and structures.

B. Related Requirements:

1. Section 311000 Site Clearing.

1.2 DEFINITIONS

A. Backfill: Soil material or controlled low-strength material used to fill an excavation.

1. Initial Backfill: Backfill placed beside and over pipe in a trench, including haunches to support sides of pipe.

2. Final Backfill: Backfill placed over initial backfill to fill a trench.

B. Base Course: Aggregate layer placed between the subbase course and hot-mix asphalt paving.

C. Bedding Course: Aggregate layer placed over the excavated subgrade in a trench before laying pipe.

D. Borrow Soil: Satisfactory soil imported from off-site for use as fill or backfill.

E. Drainage Course: Aggregate layer supporting the slab-on-grade that also minimizes upward capillary flow of pore water.

F. Excavation: Removal of material encountered above subgrade elevations and to lines and dimensions indicated.

G. Fill: Soil materials used to raise existing grades.

H. Structures: Buildings, footings, foundations, retaining walls, slabs, tanks, curbs, mechanical and electrical appurtenances, or other fabricated stationary features constructed above or below the ground surface.

I. Subbase Course: Aggregate layer placed between the subgrade and base course for hot-mix asphalt pavement, or aggregate layer placed between the subgrade and a cement concrete pavement or a cement concrete or hot-mix asphalt walk.

J. Subgrade: Uppermost surface of an excavation or the top surface of a fill or backfill immediately below subbase, drainage fill, drainage course, or topsoil materials.

SECTION 312000 EARTH MOVING 0312000-2

1.3 ACTION SUBMITTALS

A. Product Data: For each type of the following manufactured products required:

1. Geotextile fabric.

1.4 FIELD CONDITIONS

A. Traffic: Minimize interference with adjoining roads, streets, walks, and other adjacent occupied or used facilities during earth-moving operations.

1. Do not close or obstruct streets, walks, or other adjacent occupied or used facilities without permission from Owner and authorities having jurisdiction.

2. Provide alternate routes around closed or obstructed traffic ways if required by Owner or authorities having jurisdiction.

3. Comply with all speed limits. Speed limit on La Cuesta Lane is 10 mph.

B. Utility Locator Service: Notify NM811 for area where Project is located before beginning earth-moving operations.

PART 2 - PRODUCTS

2.1 GEOTEXTILES

A. Geotextile fabric shall be nonwoven needle-punched geotextile, made from polyolefins or polyesters and a puncture strength of at least 80 lbf.

PART 3 - EXECUTION

3.1 PREPARATION

A. Protect structures, utilities, and other facilities from damage caused by settlement, lateral movement, undermining, washout, and other hazards created by earth-moving operations.

B. Protect and maintain erosion and sedimentation controls during earth-moving operations.

C. Protect subgrades and foundation soils from freezing temperatures and frost. Remove temporary protection before placing subsequent materials.

3.2 DEWATERING

A. Provide dewatering system of sufficient scope, size, and capacity to control hydrostatic pressures and to lower, control, remove, and dispose of both surface water and ground water and permit excavation and construction to proceed on dry, stable subgrades.

SECTION 312000 EARTH MOVING 0312000-3

B. Prevent surface water and ground water from entering excavations, from ponding on prepared subgrades, and from flooding Project site and surrounding area.

C. Protect subgrades from softening, undermining, washout, and damage by rain or water accumulation.

1. Reroute surface water runoff away from excavated areas. Do not allow water to accumulate in excavations.

D. Dispose of water removed by dewatering in a manner that avoids endangering public health, property, and portions of work under construction or completed. Dispose of water and sediment in a manner that avoids inconvenience to others.

3.3 EXPLOSIVES

A. Explosives:

1. Do not use explosives.

3.4 EXCAVATION, GENERAL

A. Classified Excavation: Excavate to subgrade elevations unless bedrock is encountered first. If bedrock is encountered before subgrade depth is reached, structures may be placed on bedrock.

Contractor shall be responsible for final leveling of gabions to ensure top of gabion wall matches elevations indicated on Construction Plans. Material to be excavated will not be classified as to type and no separate payment or extra contract time will be made for excavation.

3.5 EXCAVATION FOR STRUCTURES

A. Excavate to indicated elevations and dimensions within a tolerance of plus or minus 1 inch.

3.6 UNAUTHORIZED EXCAVATION

A. Fill unauthorized excavation under gabions by extending bottom elevation of gabion, without altering top elevation.

3.7 SOIL FILL

A. Plow, scarify, bench, or break up sloped surfaces steeper than 1 vertical to 4 horizontal so fill material will bond with existing material.

3.8 GRADING

A. General: Uniformly grade areas to a smooth surface, free of irregular surface changes.

SECTION 312000 EARTH MOVING 0312000-4

3.9 PROTECTION

A. Protecting Graded Areas: Protect newly graded areas from traffic, freezing, and erosion. Keep free of trash and debris.

B. Repair and reestablish grades to specified tolerances where completed or partially completed surfaces become eroded, rutted, settled, or where they lose compaction due to subsequent construction operations or weather conditions.

3.10 DISPOSAL OF SURPLUS AND WASTE MATERIALS

A. Remove surplus satisfactory soil and waste materials, including unsatisfactory soil, vegetation, trash, and debris, and legally dispose of them off Owner's property.

END OF SECTION 312000

SECTION 313600 GABIONS 0313600-1

SECTION 313600 – GABIONS

1.1 RELATED SECTIONS

A. Appendix A – Maccafferi Standard Specifications

1.2 DEFINITIONS

B. Gabion baskets are defined as galvanized steel wire mesh box-shaped baskets of various sizes. The baskets are filled on site with clean hard stones.

C. The selvages of the baskets are the thicker perimeter and edge wires to which the wire mesh is securely tied to withstand sudden or gradual stress from any direction.

D. Reinforcing wires are the thicker wires incorporated into the netting during fabrication.

E. The diaphragms are internal wire mesh partitions which divide the baskets into cells.

F. Lacing or binding wire is the wire used to assemble and join the basket units.

G. Connecting wires are the internal wires used to prevent the mattress from bulging.

1.3 SUBMITTALS

Submit the following:

A. Product Data: Submit all literature, specifications, and other data available from the manufacturer.

Data shall include detailed information on:

1. Gabion basket wire/mesh.

2. Gabion fill stone.

3. Geosynthetic fabric.

B. Certificates of Compliance: Furnish certification that standards specified herein are met.

PART 2 - PRODUCTS

2.1 Gabion Baskets

A. Shall be sized to construct wall of dimensions shown on the plans. Gabion Baskets shall be PVC Coated. See Appendix A – Maccaferri Standard Specifications for further specifications for gabion baskets.

SECTION 313600 GABIONS 0313600-2

2.2 FABRICATION

A. Gabion basket shall be manufactured with all components mechanically connected at production facility. All perimeter edges of the mesh forming the basket and top, or lid, shall be selvedged with wire having a larger diameter. The gabion basket is uniformly partitioned into internal cells.

The diaphragms shall be secured in position to the base so that no additional tying is necessary at the jobsite.

2.3 MATERIALS

A. Material specification for the gabion basket shall conform to Appendix A – Maccaferri Standard Specifications.

B. The material used for gabion basket fill shall be clean, hard stone that shall conform to Appendix A – Maccaferri Standard Specifications.

PART 3 – EXECUTION

3.1 PREPARATION

A. Excavate to elevation required to install gabions. Do not over excavate.

B. Place geotextile fabric between subgrade and gabion baskets and between underground portions of gabion wall as shown on the Construction Plans.

3.2 ASSEMBLY AND PLACING

A. Assembly and Placement of the gabion baskets shall conform to Appendix A - Maccaferri Standard Specifications.

3.3 FILLING

A. Filling of the gabion basket shall conform to Appendix A - Maccaferri Standard Specifications.

B. Filling may be by hand or by mechanical means. Every effort shall be made to keep voids and bulges in the gabion basket to a minimum in order to ensure proper alignment and a neat, compact, square appearance.

END OF SECTION 313600

APPENDIX A

MACCAFERRI STANDARD SPECIFICATIONS

PRODUCT STANDARD SPECIFICATIONS

Rev: 02, Issue Date 06.03.2013

GABION

GALVANIZED & PVC COATED

Gabion – Galvanized & PVC Coated

1.0 Description

This work shall consist of furnishing, assembling, and filling woven wire mesh gabions with rock as specified in the contract to the dimensions, lines and grades shown on the plans, or as determined by the engineer. These specifications are in accordance with ASTM A975 and include gabions as manufactured by Maccaferri Inc or equivalent.

2.0 Materials

2.1 Woven Mesh Gabions

2.1.1 Wire (Zinc Coated):

All tests on the wire must be performed prior to manufacturing the mesh.

Tensile strength: both the wire used for the manufacture of gabions and the lacing wire, shall have a maximum tensile strength of 75,000 psi (515 MPa), in accordance with ASTM A641/A641M.

Elongation: the test must be carried out on a sample at least 12 in. (30 cm) long. Elongation shall not be less than

12%, in accordance with ASTM A370.

Zinc coating: minimum quantities of zinc according to ASTM A641/A641M, Class III soft temper coating.

Adhesion of zinc coating: the adhesion of the zinc coating to the wire shall be such that, when the wire is wrapped six turns around a mandrel having four times the diameter of the wire, it does not flake or crack when rubbing it with the bare fingers, in accordance with ASTM A641/A641M.

2.1.2 PVC (Polyvinyl Chloride) Coating

Specific gravity: 81-84 pcf (1.30-1.35 kg/dm 3, ) in accordance with ASTM D792, Table 1;

Hardness: between 50 and 60 Shore D, according to ASTM D 2240;

Tensile strength: not less than 2,985 psi (20.6 MPa), according to ASTM D412;

Modulus of elasticity: not less than 2,700 psi (18.6 MPa), according to ASTM D412;

Abrasion resistance: the percentage of the weight loss shall be less than 12%, according to ASTM D1242.

Heat Aging Test: prior to UV and abrasion degradation, the PVC polymer coating shall have a projected durability life of 69 years when tested in accordance with UL 746B.

Note: The standard stock color for Maccaferri PVC coating is gray.

The accelerated aging tests are:

Salt spray test: test period 3,000 hours, test method ASTM B117;

Exposure to UV rays: test period 3,000 hours at 145°F (63°C), test method ASTM D1499 and ASTM G152;

Brittleness temperature: no higher than 15°F (- 9°C), or lower temperature when specified by the purchaser, when tested in accordance with ASTM D746.

The properties after aging tests shall be as follows:

Appearance of coated mesh: no cracking, stripping or air bubbles, and no appreciable variation in color;

Specific gravity: variations shall not exceed 6%;

Hardness: variations shall not exceed 10%;

Tensile strength: variations shall not exceed 25%;

Modulus of elasticity: variations shall not exceed 25%;

Abrasion resistance: variations shall not exceed 10%;

Brittleness temperature: shall not exceed + 64°F (+18°C).

Gabions-Galvanized & PVC Coated-Page 2

2.1.3 Galvanized and PVC coated wire mesh gabions (8 x 10 mesh type):

PVC coating thickness: Nominal – 0.02 in. (0.5 mm), Minimum – 0.015 in. (0.38 mm)

Mesh Wire: Diameter – 0.106 in. (2.70 mm) internal, 0.146 in. (3.70 mm) external

Selvedge Wire: Diameter – 0.134 in. (3.40 mm) internal, 0.174 in. (4.40 mm) external

Mesh Opening: Nominal Dimension D = 3.25 in. (83 mm), as per Fig. 1.

2.1.4 Galvanized and PVC coated lacing wire and internal stiffeners:

PVC coating thickness: Nominal – 0.02 in. (0.5 mm), Minimum – 0.015 in. (0.38 mm)

Lacing wire: Diameter – 0.087 in. (2.20 mm) internal, 0.127 in. (3.20 mm) external

Cross Tie/Stiffener wire: Diameter - 0.087 in. (2.20 mm) internal, 0.127 in. (3.20 mm) external

Preformed Stiffener: Diameter – 0.134 in. (3.4 mm) internal, 0.174 in. (4.4 mm) external

2.1.5 Steel Mesh properties

Mesh Tensile Strength: shall have a minimum strength of 2900 lb/ft (42.3 kN/m) when tested in accordance with ASTM A975 section 13.1.1.

Punch Test Resistance: shall have a minimum resistance of 5300 lb (23.6 kN/m) when tested in accordance with ASTM A975 section 13.1.4.

Connection to selvedges: shall have a minimum resistance of 1200 lb/ft (17.5 kN/m) when tested in accordance with

ASTM A975.

2.1.6 Spenax Fasteners (Overlapping Fasteners):

Stainless Steel overlapping fasteners may be used in lieu of, or to complement, lacing wire for basket assembly and installation.

High tensile fasteners shall have a nominal spacing of 4 in. (100 mm) not to exceed 6 in (150 mm) for all assembly and installation. This is based on a 1,200 lb/ft (17.5 kN/m) pull apart resistance for galvanized and PVC coated wire mesh with this spacing (ASTM A975 section 13.1.2).

Fasteners used for assembly and installation of the units on the field shall be tested for compliance with the ASTM A975 section 13.1.2.2 Pull-Apart Resistance. Producer or supplier of the wire mesh shall provide certification no later than 15 days prior of starting construction.

When tested in accordance with section 13.1.2.1, the average maximum resistance of the fasteners from the field shall not be lower than 90% of the resistance provided in the certification.

Stainless Steel Fasteners: Diameter = 0.120 in. (3.05 mm), according to ASTM A313/A313M, Type 302, Class I.

Tensile strength: 222,000 to 253,000 psi (1530-1744 MPA) in accordance with ASTM A313 Table 5.

Proper installation of rings: A properly formed Spenax fastener shall have a nominal overlap of one (1) in. after closure (Fig. 2).

2.2 Tolerances

Wire: Zinc coating, in accordance with ASTM A641/A641M, Class III soft temper coating.

Gabions: ± 5 % on the length, width, and height.

Mesh opening: Tolerances on the hexagonal, double twisted wire mesh opening shall not exceed ± 10% on the nominal dimension D values (see Fig.1):

2.3 Standard Unit Size

0.75 in.

(19 mm)

1.75 in.

(44 mm)

Open Close

Normal overlap of 1 in. (25

mm) after closure

Mesh Type Nominal Dimension D

8 x 10 3.25 in. (83 mm)

D

Fig. 1 Fig. 2

Gabions-Galvanized & PVC Coated-Page 3

2.4 Fabrication

Gabions shall be manufactured and shipped with all components mechanically connected at the production facility. The front, base, back and lid of the gabions shall be woven into a single unit. The ends and diaphragm(s) shall be factory connected to the base. All perimeter edges of the mesh forming the basket and top, or lid, shall be selvedged with wire having a larger diameter.

The gabion is divided into cells by means of diaphragms positioned at approximately 3 ft (1 m) centers. The diaphragms shall be secured in position to the base so that no additional lacing is necessary at the jobsite. See Figure 3.

2.5 Rock

The rock for gabions shall be hard, angular to round, durable and of such quality that they shall not disintegrate on exposure to water or weathering during the life of the structure. Gabion rocks shall range between 4 in. (0.10 m) and 8

in. (0.20 m). The range in sizes shall allow for a variation of 5% oversize and/or 5% undersize rock, provided it is not placed on the gabion exposed surface. The size shall be such that a minimum of three layers of rock must be achieved when filling the gabions.

Table of sizes for gabions L=Length ft (m) W=Width ft (m) H=Height ft (m) # of cells

6 (1.8) 3 (0.9) 3 (0.9) 2

9 (2.7) 3 (0.9) 3 (0.9) 3

12 (3.6) 3 (0.9) 3 (0.9) 4

6 (1.8) 3 (0.9) 1.5 (0.45) 2

9 (2.7) 3 (0.9) 1.5 (0.45) 3

12 (3.6) 3 (0.9) 1.5 (0.45) 4

6 (1.8) 3 (0.9) 1 (0.3) 2

9 (2.7) 3 (0.9) 1 (0.3) 3

12 (3.6) 3 (0.9) 1 (0.3) 4

4.5 (1.4) 3 (0.9) 3 (0.9) 1 All sizes and dimensions are nominal. Tolerances of ± 5% of the width, and length height, of the gab ions shal l be permitted.

Diaphragm

Back

Lid

End

End

Front

W

H

L

Fig. 3

Gabions-Galvanized & PVC Coated-Page 4

3.0 Construction Requirements

3.1 Assembly

Gabions are supplied folded flat and packed in bundles. The units are assembled individually by erecting the sides, ends, and diaphragms, ensuring that all panels are in the correct position, and the tops of all sides are aligned. The four corners shall be connected first, followed by the internal diaphragms to the outside walls. All connections should use lacing wire or fasteners as previously described in Section 2.1.4 and Section 2.1.6.

The procedure for using lacing wire consists of cutting a sufficient length of wire, and first looping and/or twisting to secure the lacing wire to the wire mesh. Proceed to lace with alternating double and single loops through every mesh opening approximately every 6 in. (150 mm), pulling each loop tight and finally securing the end of the lacing wire to the wire mesh by looping and/or twisting.

The use of fasteners shall be in accordance with the manufacturer’s recommendations as specified in Section 2.1.6.

3.2 Installation

After initial assembly, the gabions are carried to their final position and are securely joined together along the vertical and top edges of their contact surfaces using the same connecting procedure(s) described in Section 3.1. Whenever a structure requires more than one layer, the upper empty baskets shall also be connected to the top of the lower layer along the front and back edges of the contact surface using the same connecting procedure(s) described in Section 3.1.

3.3 Filling

Gabions shall be filled with rock as specified in Section 2.4. During the filling operation some manual stone placement is required to minimize voids. The exposed faces of vertical structures may be carefully hand placed to give a neat, flat, and compact appearance. Care shall be taken when placing fill material to ensure that the sheathing on the PVC coated baskets is not damaged.

The cells shall be filled in stages so that local deformation may be avoided. That is, at no time shall any cell be filled to a depth exceeding 1-foot (0.30 m) higher than the adjoining cell. It is also recommended to slightly overfill the baskets by 1 to 2 in. (25 to 50 mm) to allow for settlement of the rock. Behind gabion walls, compact the backfill material simultaneously to the same level as the filled gabions.

3.4 Internal Connecting Wires

MacTie preformed stiffeners or lacing wire can be used as internal connecting wires when a structure requires more than one layer of gabions to be stacked on top of each other. Internal Connecting Wires with lacing wire shall connect the exposed face of a cell to the opposite side of the cell. Internal Connecting Preformed stiffeners shall connect the exposed face of a cell to the adjacent side of the cell. Preformed stiffeners are installed at 45° to the face/side of the unit, extending an equal distance along each side to be braced (approximately 1 ft. (300 mm)). An exposed face is any side of a gabion cell that will be exposed or unsupported after the structure is completed.

3.4.1 3 Feet (1 m) High Gabions

3 feet (1 m) high gabions shall be filled in three layers, 1 foot (300 mm) at a time. Connecting wires/bracings shall be installed after the placement of each layer, that is, at 1 foot (300 mm) high and 2 feet (600 mm) high.

3.4.2 1.5 Feet (0.5 m) High Gabions

1.5 feet (0.5 m) high gabions do not require connecting wires/bracings unless the baskets are used to build vertical structures. In some cases, these units shall be filled in two layers, 9 in. (230 mm) at a time. Connecting wires shall be installed after the placement of the first layer, which is at 9 in. (230 mm) high.

3.5 Lid Closing

Once the gabion baskets are completely full, the lids will be pulled tight until the lid meets the perimeter edges of the basket. A tool such as a lid closer can be used. The lid must then be tightly laced and/or fastened along all edges, ends and tops of diaphragm(s) in the same manner as described in Section 3.1.

Gabions-Galvanized & PVC Coated-Page 5

3.6 Mesh cutting and folding

Where shown on the drawings or otherwise directed by the engineer, the gabions shall be cut, folded and fastened together to suit site conditions. The mesh must be cleanly cut and surplus mesh either folded back or overlapped so that it can be securely fastened together with lacing wire or fasteners in the manner described in Section 3.1. Any reshaped gabions shall be assembled, installed, filled and closed as specified in the previous sections.

4.0 Method of Measurement

4.1 The payment quantities for excavation shall be determined by the outside limits of the gabion structure. Quantities will be determined from cross sections and the linear distance, and paid for under the appropriate excavation bid items.

4.2 The quantity to be paid for “In place gabions” shall be the number of cubic meters or cubic yards of gabions measured in their final position. Project conditions and material availability will determine the actual size of gabions to be used.

4.3 Excavated material beyond the limits of the gabions shall be backfilled with gravel, crushed rock or other material approved by the engineer.

4.4 This bid price shall include the installed in place cost of all materials, equipment, and labor, including gabions, rock, and backfill material.

5.0 Basis of Payment

Accepted gabions will be paid for at the unit price for each pay item included in the contract.

B. Fill depressions caused by clearing and grubbing operations with satisfactory soil material unless further excavation or earthwork is indicated.

D. Dispose of water removed by dewatering in a manner that avoids endangering public health, property, and portions of work under construction or completed. Dispose of water and sediment in a manner that avoids inconvenience to others.

B. Certificates of Compliance: Furnish certification that standards specified herein are met.

END OF SECTION 313600