2512Gabions and Revet Mattresses

2512.1DESCRIPTION

This Work consists of constructing gabions and revet mattresses.

2512.2MATERIALS

B Filter Materials

2512.3CONSTRUCTION REQUIREMENTS

A General .............................................................................................................................. 2511.3 Excavate, shape, and compact the foundation to the elevation and alignment as required by the Contract.

Provide and place filter Material, unless otherwise required by the Contract. Provide and place gabions and revet mattresses. B Filter Material Place filter Material over the entire area before placing the gabions and revet mattresses. The Contractor may place geotextile filter Material under gabions and revet mattresses on slopes without stepping if specified by the Contract or approved by the Engineer. Use Geotextile 3733 Type 3 under gabions and revetment mattresses. C Baskets and Fasteners C.1 Documentation Provide the following:

section (2512, “Gabions and Revet Mattresses”)

fasteners C.2 Construction Install the baskets to the dimensions, profile, and alignment as required by the C ontract or as directed by the Engineer. Assemble the baskets in accordance with the manufacturer’s recommendations unless otherwise specified in 2512, “Gabions and Revet Mattresses,” 3602, “Gabions and Revet Mattresses Materials,” or as shown on the Plans. Place and fasten the diaphragms in the baskets to the side and bottom mesh to create cell dimensions no greater than 3 feet. Fasten adjoining empty baskets together at their perimeters. Place stones in the cells of baskets in a manner that will minimize voids, does not allow sharp edges to protrude through the mesh, and maintains the basket dimensions as shown on the Plans. Hand place stones as necessary. Fill cells in 1 foot Layers. Fill cells no greater than 1 foot in one Layer. Fill cells no greater than 18 inches in 2 equal Layers. Do not fill cells greater than 1 foot higher than stone Layers in adjacent cells or baskets. For twisted wire gabions, place horizontal connecting wires on top of the stone L ayer in both directions if no supporting basket exists, to prevent the sides from bulging . For welded wire gabions, install preformed stiffeners across the corners of the gabions before filling . Provide 2 rows of stiffeners, 4 per cell, for the front face and the side faces. Provide a single row of stiffeners, 2 per cell, on the back face. The Department will not require stiffeners in interior cells. Provide preformed stiffeners with a Nominal length of 18 inches. Hook the stiffeners at crossing wires. The Contractor may use lacing wire as a stiffener. After filling the basket, fold the top of baskets shut and fasten to the ends, sides, diaphragms, and adjacent baskets.

Stack empty baskets on filled baskets and fasten to the filled baskets at front, exposed sides, and back before filling. Stagger the vertical joints between the baskets of adjacent rows and layers unless otherwise required by the Contract. Backfill behind a gabion structure simultaneously with the cell filling operation. C.3 Fasteners The Contractor may use lacing wire, an alternative fastener approved by the Engineer, or a combination, to fasten the baskets. C.3.a Lacing Wire Place lacing wire at each joint alternating single and double loops every 3 to 6 inches. C.3.b Alternative Fastener Place alternative fasteners at each joint at every mesh opening. Adequately secure spiral binders at the ends to prevent unwinding. D Acceptance The Engineer may consider the Work unacceptable if visible baskets vary by greater than 6 inches from the profile or alignment as shown on the Plans or as directed by the Engineer.

2512.4METHOD OF MEASUREMENT

A Gabions and Revet Mattresses The Engineer will measure Gabions and Revet mattresses by volume based on the Nominal basket dimensions and the number of baskets incorporated into the W ork. B Filter Materials The Engineer will measure filter Materials in accordance with 2511.4B, “Filter Materials.”

2512.5BASIS OF PAYMENT

The Contract Unit Price for both Gabions and for Revet mattresses include the cost of providing the Materials as required by 3601, “Riprap Material,” and 3602, “Gabions and Revet Mattresses Materials,” excavating and preparing the foundations, providing and installing filter Materials , and constructing and filling the Gabions and revet Mattresses. The Department will separately compensate for filter Materials if the Contract contains the relevant Contract Items as listed in 2511, “Riprap.” The Department will pay for Gabions and Revet mattresses on the basis of the following schedule: Item No. Item Unit

2512.507 Gabion cubic yard

7 Revet Mattress cubic yard