UNITED STATES DEPARTMENT OF AGRICULTURE

NATURAL RESOURCES CONSERVATION SERVICE

OREGON

[CONSTRUCTION SPECIFICATION]{.underline}

[CS-61 WIRE MESH GABIONS]{.underline}

61.1 [SCOPE]{.underline}

> The work shall consist of furnishing and installing wire mesh gabions
> at the location and to the lines and grade as shown on the drawings.

61.2 [MATERIALS]{.underline}

> Wire shall be American Iron and Steel Institute 1006, or 1010, medium
> tensile strength steel wire with galvanized or polyvinyl chloride
> coating conforming to the requirements of Federal Specification
> QQ-W-61b. Wire used in the mesh shall not be less than 0.11 inch in
> diameter. Selvages shall be made from wire of not less than 0.148 inch
> in diameter. Tie and connecting wire shall not be less than 0.09
> inches in diameter.
>
> Rock for filling the baskets shall conform to MS-212 and shall be
> within the grading limits as shown on the drawing.
>
> The filter and bedding requirements are shown on the plan and the
> material shall conform to the applicable NRCS material specifications
> shown in the plan.

61.3 [FOUNDATION PREPARATION]{.underline}

> The foundation shall be cut or filled and graded to the lines and
> grades shown on the drawings. When fill is required, it shall consist
> of approved materials and shall conform to the material and compaction
> requirements shown on the plan. Vegetation, surface irregularities,
> and loose material shall be removed from foundations. Gabions or
> bedding shall not be placed until the foundation preparation is
> completed.

61.4 [BEDDING]{.underline}

> When bedding is specified beneath the gabion, the bedding material
> shall be spread uniformly and compacted to the depth and density using
> the material shown on the drawing.

61.5 [FABRICATION]{.underline}

> The wire mesh shall be securely fastened at the intersection of all
> wires making up the mesh. Maximum mesh openings shall not be greater
> than 4.5 inches measured in any direction. Gabions shall be fabricated
> so that the sides, lid, and diaphragms can be assembled at the
> construction site into rectangular baskets of the specified sizes.
> Where the length of the gabion exceeds its width, the gabion shall be
> equally divided by diaphragms into cells, so that the effective length
> of each cell does not exceed the gabion width.
>
> Gabion top, bottom, side and diaphragm edges shall be connected in a
> manner that the strength and flexibility at the connection is at least
> equal to that of the mesh. Edges of the wire mesh fabric shall be
> securely salvaged or bound.

61.6 [ASSEMBLY]{.underline}

> Unless otherwise specified, the manufacturer's installation
> recommendations shall be followed.
>
> Ties and connections shall be very securely made with the wire
> provided by the manufacturer. Adjoining gabions shall be joined by
> connections with a strength equal to that of the wire mesh. Tie wires
> used to connect adjoining gabions shall be separate from tie wires
> used to assemble the individual baskets.

61.7 [FILLING]{.underline}

> The placement of rock in gabion baskets, including the installation of
> connecting wires, shall be performed in the following sequence for the
> depth of the gabions as indicated:
>
> a\. [Thirty-Six Inch deep gabion baskets]{.underline}:
>
> \(1\) Fill gabions to a depth of 12 inches and tightly tie one
> connecting wire in each direction to opposite faces of each gabion at
> 12-inches above the base.
>
> \(2\) Fill gabions another 12 inches and tightly tie one connecting
> wire in each direction to opposite faces of each gabion at this level.
>
> \(3\) Complete filling of gabions.
>
> b\. [Eighteen and Twelve Inch deep gabion baskets]{.underline}:
>
> \(1\) Connecting wires are not necessary in the 12-inch size.
>
> \(2\) Connecting wires are only necessary in the 18-inch size gabion
> when it is used to construct vertical structures. If required, tie one
> connecting wire in each direction to the opposite face, at 9 inches
> above the base, after filling with rock to this level.

The gabions shall be carefully filled with rock, by hand or machine
placement, to ensure alignment and provide a compacted mass with a
minimum of voids. Machine placement may have to be supplemented with
hand work for the final arrangement of rocks.

> Cells in the row shall be filled in stages such that the depth of rock
> placed in any cell does not exceed the depth in an adjoining cell by
> more than one foot. Rock on visible faces shall not be smaller than 4
> inches.

61.8 [CLOSURE AND SECURING]{.underline}

> When the gabion has been filled, the lid shall be bent and stretched
> until it meets the perimeter edges of the front and end panels. To
> assist in closing and lacing, a pinch bar or special closing tool may
> be used. The lid shall then be tightly laced with lacing wire to the
> edges of the front and end panels. The lids shall also be securely
> tied to each adjoining gabion with lacing wire along all contact
> edges. Lacing adjacent lids to the vertical panels in one operation is
> acceptable. Lacing the back edge of the lid to adjoining gabions shall
> be done prior to filling the gabion. The lid shall be tied to each
> diaphragm by lacing wire.

61.9 [FILTER MATERIAL]{.underline}

> Filter material, if required, shall be of the gradation and depth
> placed at the location as shown on the drawing. Fabric filters shall
> not be placed adjacent to the woven wire without bedding.

61.10 [BACKFILLING]{.underline}

> The backfill material shall be native soil material, unless otherwise
> specified, compacted to the density of the undisturbed surrounding
> soil.

11. [ITEMS OF WORK AND CONSTRUCTION DETAILS FOR THIS
    PROJECT]{.underline}