2515Revetment systems

2515.1DESCRIPTION

This Work consists of providing and placing a protective covering for earth slopes, river channels, vehicle accesses, spillways, and susceptible soil erosion areas.

2515.2MATERIALS

2515.3CONSTRUCTION REQUIREMENTS

A General Excavate the foundation for the revetment systems, with geotextile filter, using toe, terminal, and upper bank trenches. Shape the foundation excavation to the cross-sections as shown on the Plans unless otherwise directed by the Engineer. Grade and compact termination trenches, embankment crests, and toes to prevent water from migrating under the block and geotextile Material . Grade final Subgrade smooth before placing the base course Material to allow uniform contact with the geotextile and articulated concrete. B Subgrade Preparation Prepare the subgrade per 2112, “Subgrade Preparation.” Provide subgrade Material free of stones, sticks, and other debris or irregularities that might puncture the geotextile fabric or create other system failures. If the system is subject to vehicle loading, install a geogrid for extra support, as shown on the Plans. C Bedding Material Provide bedding Material consisting of at least 6 inches spread evenly over the compacted Subgrade, made from one of the following Materials:

Compact the Bedding Material per 2106.3G.2, “Quality Compaction.” D Geotextile Filter Place Type 3 geotextile per 3733, “Geosynthetic Materials,” as a filter under the revetment systems unless otherwise required by the Contract. Place the geotextile filter Material on the entire area supporting the revetment system. Secure the geotextile Material with 6-inch steel pins or staples, unless

otherwise shown on the Plans. If installing anchors, cut the geotextile to allow the anchors to penetrate the geotextile. Place and compact prepared Subgrade and bedding Material, and place geotextile Material without tearing, puncturing, or shifting the fabric. Place a 1-inch sand Layer on the geotextile fabric before placing the block. Place the required multiple fabric widths or lengths with the longest dimension parallel to the direction of water flow. Place un-seamed fabric with splices and joints overlapped at least 18 inches, except overlap splices and joints underwater at least 36 inches. Shingle the joint laps in the flow direction and from top of slope to bottom to direct water flow over the joint without undermining . As an alternative to joint over-lapping, the Contractor may sew multiple fabric pieces together to meet the seam breaking strength requirements of 3733, “Geosynthetic Materials.” Bury upgrade edges of the fabric area to direct water flow over the fabric without undermining. For un-seamed geotextile, place steel pins with washers or staples at locations and in quantities as approved by the Engineer to prevent movement of the geotextile during placement of the articulated concrete revetment system. Do not operate construction Equipment directly on top of the geotextile. E Precast Articulated Concrete E.1 Articulated Block Mat Place the mats in accordance with the appropriate manufacturer’s recommendations . Place the mats no greater than 2 inches apart. After cable clamping and anchoring, use Type 3A grout per 2461, “Structural Concrete,” to close gaps greater than 2 inches. Entrench and bury the outside edges of the mat system at least 1 block into the ground filled with compacted fill. Do not allow mats to overlap and blocks to project vertically greater than 1 inch beyond the adjacent block. Fasten the protruding longitudinal and transverse cable connections together along the adjacent sides of the mats. E.2 Articulated Interlocking Block Install articulated interlocking blocks by hand. Do not overlap blocks and allow blocks to project vertically by greater than 1 inch beyond the adjacent blocks. Place anchors through cuts in the geotextile and position the anchors on the concrete block to maximize the pull out resistance. E.3 Clamps Use wire rope clamps to join cable loops of horizontal and vertical adjoining concrete revetment mats as specified by the manufacturer, unless otherwise directed by the Engineer. E.4 Anchors Install anchors at 8-foot intervals at lead edge and around perimeter of the revetment system, and as shown on the Plans, as specified by the manufacturer, or as directed by the Engineer. Embed anchors at least 3.5 feet deep. Fasten the exposed cables of the concrete mats to the anchors driven into the anchor trench. F Concrete Armor Units Place concrete armor units so not to tear the geotextile. Embed and entrench at least one block into the ground at the toe with compacted fill Material. Begin placement of the system at the toe termination trench and proceed up the slope and as per manufacturer’s recommendations . G Filling and Vegetation If vegetation is shown on the Plans, fill voids of the revetment system with screened common topsoil borrow per 3877, “Topsoil Material,” 35-241 seed mix per 3876, “Seed,” and category 30 rolled

erosion prevention product per 3885, “Rolled Erosion Prevention Products,” unless otherwise shown on the Plans. Perform filling and vegetation after the Engineer completes inspection of any required clamping and anchoring systems.

2515.4METHOD OF MEASUREMENT

The Engineer will measure precast articulated concrete of each type by area on the basis of actual surface dimensions as staked. The Engineer will measure geotextile filter Material by area on the basis of actual surface dimensions as staked. The Engineer will not include allowance for overlaps or seams in the measurement for geotextile filter. The Engineer will measure concrete armor units by surface area covered by each size provided, installed, and accepted by the Engineer, including the buried portions, using the outermost extremity of the units as required by the Contract. On small Projects, the Engineer will accept concrete armor units by the number of complete units assembled and installed as required by the C ontract.

2515.5BASIS OF PAYMENT

The Contract Unit Prices for revetment systems include the cost of excavating and preparing the foundations, providing system Materials, geotextile filter, base, and bedding Materials, grouting, clamping, and anchoring. The Department will pay for revetment systems on the basis of the following schedule: Item No. Item Unit

2515.502 Concrete Armor Units ____ (size) each

4 Articulated Block Mat Open Cell Type ___ square yard

4 Articulated Block Mat Closed Cell Type ___ square yard

4 Articulated Interlocking Block Open Cell Type ___ square yard

4 Articulated Interlocking Block Closed Cell Type ___ square yard

4 Concrete Armor Units ____ (size) square yard