139 SECTION 218 SLOPE AND FOUNDATION PROTECTION
218.1 -DESCRIPTION : This work shall consist of the construction of revetments of stone or concrete, with or without engineering fabric, to prevent erosion of slopes or banks, or to protect foundations, a t places indicated on the Plans or where designated by the Engineer, all in accordance with these Specifications and in reasonable close conformity with the lines, grades, dimension, and cross sections shown on the Plans.
218.2 -MATERIALS : Materials shall meet the requirements specified in the following Sub -sections of
MATERIALS SUBSECTION Cement for Grout 701.1 or 701.3 Engineering Fabric for Erosion Control 715.11 Gabions 715.23 Reinforcement 709.3, 709.4 Sand for Grout 702.1.1 through 702.1.5 and 702.6, or 702.2 Shot Rock 704.8 Stone for Gabions 704.3 Stone for Riprap 704.2
The stone for crushed rock slope protection shall meet the requirements of Subsection 704.6, Class 7, except that of subsection 704.6.3 shall not apply . Acceptance for Gradation of Class 7 aggregate shall be by visual inspection; a written explanation of the manufacturing process shall be provided if requested by the Engineer. Class 7 from a non -approved source, shall not exceed a weighted loss of thirty percent (30%) when subjected to five cycles of the Sodium Sulfate Soundness Test, will be acceptable. An alternate to this gradation shall be AASHTO size No. 1. Certified test data from the producer showing the AASHTO No. 1 material meets the gradation requirements of subsection 703.4. Stone for foundation protection shall conform to the requirements of riprap stone, except for size and shape.
CONSTRUCTION METHODS
218.3 -SLOPE PROTECTION : 218.3.1 -General: The slopes to be revetted shall reasonably conform to the lines, grades, dimensions, and cross sections as shown on the Plans, unless otherwise directed. The placing of riprap or grouted riprap shall start in a trench, the invert of which is parallel to and two ( 2) feet below the toe of the slope, and the trench shall be two ( 2) feet in width. The construction shall progress from the invert of the trench u p the slope to conform to the requirements specified.
140 Slope protection with crushed rock, concrete slabs, or precast concrete blocks shall start at a concrete bottom sill, shall be included within side sills, and shall progress upward to the berm in fron t of the abutment. The design and dimensions of the sills shall be as shown on the Plans. The area of the sills shall be considered a part of the area of the slope protection. The concrete sills may be precast or cast -in-place and shall be placed in a t rench excavated to receive them. Concrete used in the sills shall meet the requirements specified in 218.3.6.2. Construction equipment shall not operate directly on engineering fabric. The fabric shall be protected from detrimental contamination by sur face runoff. Any fabric so contaminated shall be removed and replaced with uncontaminated fabric. Weep holes shall be provided as directed by the Engineer when grouted riprap, concrete slab, or concrete block slope protection is specified.
218.3.2 -Riprap: Riprap shall be composed of stones having the dimensions specified, each stone being firmly bedded on the slope in such a manner that it abuts against other stones to form a layer, the interstices of which are filled with suitably sized spalls. The dimensions of each stone in a plane parallel to the plane of the slope shall be not less than three ( 3) inches by twelve ( 12) inches ; unless otherwise specified, the longer dimension shall be placed horizontally. The surface of each stone shall not vary more than three ( 3) inches from the specified surface plane. Abutting stones shall have depths not different by more than 1 -1/2 inches. The average depth of the stone placed in the riprap shall be not less than the specified depth of the riprap. The fir st row of stone shall be firmly bedded on the invert of the trench so as to form a firm foundation, and the construction shall progress up the slope by fitting additional and abutting stones with well broken joints and in such a manner that the most compac t mass of riprap is developed.
218.3.3 -Grouted Riprap: Grouted riprap shall be as defined in subsection 218.3.2 with the interstices filled with spalls and grouted with cement grout. The grout filler shall be composed of a mixture of one part Portland cement and three parts sand, mixed with water to produce a workable consistency. The amount of water shall be that designated by the Engineer. The stone shall be thoroughly wet immediately before grout is applied. As soon as the grout is deposited on t he surface, it shall be thoroughly worked into the joints. The stones shall then be brushed so that their top surfaces are exposed. Grouted riprap shall be cured in accordance with any of the methods specified in subsection
501.15, with a blanket of ear th kept wet for 72 hours, or by sprinkling with a fine spray of
water every two hours during the day -light hours for a period of three days.
218.3.4 -Gabions: Gabions, consisting of galvanized wire mesh baskets filled with rocks, shall conform to these Specifications and the dimensions shown on the Plans. Assembling of the gabion units and their filling with rock shall be carried out as directed by the Engineer. The visible faces of the baskets shall be hand placed to insure an attractive appearance, and the core of the baskets may be filled by mechanical equipment.
218.3.5 -Crushed Rock Slope Protection: The thickness of crushed rock slope protection shall be as indicated on the Plans. The rock shall be raked in place to obtain a reasonably smooth and continuous surface conforming to the thickness and slope lines indicated on the Plans.
141 218.3.6 -Concrete Slope Protection: 218.3.6 .1-General: Concrete slope protection may be by cast -in-place concrete slab or precast concrete blocks; only one method shall be used at any one bridge.
218.3.6 .2-Cast -in-Place Concrete Slab: Concrete slabs sh all be not less than six (6) inches thick, shall be reinforced with Type B Fabric, and shall conform to the applicable provisions of 501, unless otherwise indicated. Transit mix concrete will be permitted. A wood float finish will be acceptable. Constru ction joints shall be provided at intervals of ten (10) feet in both directions. Class B Concrete, meeting the requirements of Section 601 may be used in lieu of the concrete provided above.
218.3.6 .3-Precast Concrete Blocks: Precast concrete blocks sh all conform to the applicable provisions of 601 and shall be made of Class B concrete, reinforced with Type B fabric. The blocks shall be 3 by 1 foot and four ( 4) inches thick. The longer dimension shall be placed on a horizontal plane. The blocks shall be firmly embedded against the slope and against adjoining blocks, with the ends in contact. The finished surface shall present an even, tight surface, reasonably true to line, grade, and section.
218.3.7 -Engineering Fabric: 218.3.7 .1-Fabric Placemen t: The area in which the fabric is to be installed shall be prepared in a relatively smooth state, free of sharp protrusions, depressions and debris. The machine direction of the fabric shall generally be placed parallel with the direction of major water flow, i.e., parallel to the stream or as authorized by the Engineer. The fabric shall be placed in a relatively loose and unstretched condition such that the fabric and underlying material deforms slightly under riprap weight when placed. Fastener pins shall be placed to prevent displacement of the fabric. The fabric shall be field sewn as described in Subsection 715.11.3 or overlapped. When the overlapping technique is used, an overlap of three ( 3) feet shall be maintained so the upgrade fabrics hall always be lapped over the downgrade fabric.
218.3.7 .2-Cover Material Placement: Extreme care shall be exercised in placing cover material over the fabric, especially when riprap is used. Under no circumstances shall heavy angular stone, such as ri prap, be dropped on the fabric from more than one ( 1) foot in height. A cushioning layer of sand or gravel may be placed between the fabric and riprap, providing this material does not inhibit free drainage of the slope. All cover material shall be place d from downslope to upslope in such a manner as to prevent slippage of the cover material off the fabric.
218.4 -FOUNDATION PROTECTION : The area around piers, abutments or other foundations shall be excavated to a depth and width indicated on the Plans, or as otherwise directed. Stone for foundation protection shall be largely equidimensional, angular, and generally ranging in size between one cubic foot and one cubic yard . The stone need not be placed, but may be dumped from trucks or bulldozed in place. The stone shall be placed where indicated on the Plans or as di rected by the Engineer.
218.4.1 -Scour Protection: Stones used for scour protection shall be well graded throughout the thickness as determined by Engineer via visual inspection. Stones smaller than
142 the specified lowest gradation as specified in the pla ns are not allowed in an amount exceeding 20% by weight. Material quality shall be satisfactory to Engineer. The use of shale is not permitted.
218.5 -METHOD OF MEASUREMENT : Except for "Shot Rock" which will be measured in tons, the quantity of work done under Slope Protection will be measured in cubic yards of "Riprap", "Grouted Riprap", or "Gabions", and in square yards of "Crushed Rock Slope Protection", "Concrete Slope Pr otection" or "Fabric for Erosion Control", excluding overlaps. The number of tons of "Shot Rock" shall be determined by the total of the weights shown on receipted railroad freight bills when materials are shipped by rail; by actual measured displacement of barges certified by the producer when water shipments are made, providing materials delivered by the methods are not stockpiled or stored; or determined by the Contractor from the total of weigh slips for each vehicle load weighed on an approved trucks cale, and certified by the Contractor to be correct. Truck scales shall be provided by the producer or Contractor. The scales shall be of sufficient size and capacity to weigh the heaviest loaded trucks that are used for delivery of the material. All tr uck scales shall be mounted on solid foundations which will insure their remaining plumb and level. All truck scales shall be inspected and sealed by the West Virginia Division of Labor, Bureau of Weights and Measures, or other appropriate agencies of the State or its political subdivisions. The Division may, at its option, accept inspection and sealing by out of state agencies when the material is weighed outside West Virginia. A digital recorder shall be required on all truck scales. The digital recor der shall produce a printed record of the gross, tare and net weights, and the time, date, truck identification and project number. Provisions shall be made for constant zero compensation and further provision shall be made so that the scales may not be m anually manipulated during the printing process. The system shall be interlocked so as to allow printing only when the scale has come to rest. In case of a breakdown of the automatic equipment, the Engineer may permit manual operation for a reasonable ti me, normally not to exceed 48 hours, while the equipment is being repaired. Each truck shall be weighed empty prior to each load. A weigh person shall be provided by the producer. The weigh person shall certify that the weight of the material, as determ ined either by the truck scales or from the digital printout of the weights, is correct. Area dimensions will be based on slope measurement; concrete sills will be included in the area measurement for crushed rock or concrete slope protection. Volumes m ay be determined by verified plan dimensions or from measurements of the completed work, as authorized by the Engineer. The quantity of work done under "Foundation Protection" will be measured in cubic yards , actually produced and incorporated in the work , determined in its original position from cross sections by the method of average end areas, unless otherwise authorized by the Engineer.
218.6 -BASIS OF PAYMENT : The quantities, determined as provided above, will be paid for at the contract unit prices bid for these items, which prices and payments shall be full compensation for excavating and preparing the embankment or slope, footing and sill trench; furnishing all the materials, including steel reinforcement; and doing all the work prescribed in a workmanlike and acceptable manner, including all labor, tools, equipment, supplies, and incidentals necessary to complete the work.
143 218.7 -PAY ITEMS : ITEM DESCRIPTION UNIT 218001 -* Riprap Cubic Yard 218002 -* Grouted Riprap Cubic Yard 218003 -* Gabion Cubic Yard 218004 -* “thickness” Crushed Rock Slope Protection Square Yard 218005 -* Concrete Slope Protection Square Yard 218006 -* Foundation Protection Cubic Yard 218007 -* Fabric For Erosion Control Square Yard 218008 -* Shot Rock Ton
* Sequence number