Riprap Art. 281.02 The aggregate used for sediment basins will be paid for at the contract unit price per ton (metric ton) for AGGREGATE (EROSION CONTROL).
b.Temporary Ditch Checks. This work will be paid for at the contract unit price per foot (meter) for TEMPORARY DITCH CHECKS, except for aggregate ditch checks which will be paid for at the contract unit price per ton (metric ton) for AGGREGATE DITCH CHECKS.
c.Perimeter Erosion Barrier. This work will be paid for at the contract unit price per foot (meter) for PERIMETER EROSION BARRIER.
d.Inlet and Pipe Protection. This work will be paid for at the contract unit price per each for INLET AND PIPE PROTECTION. Protection of drainage structures with inlet filters will be paid for at the contract unit price per each for INLET FILTERS.
e.Temporary Erosion Control Seeding. This work will be paid for at the contract unit price per pound (kilogram) for TEMPORARY EROSION CONTROL SEEDING.
f.Temporary Mulch. Temporary Mulch will be paid for according to
Article 251 — 07.
g.Temporary Erosion Control Blanket. Temporary Erosion Control Blanket will be paid for at the contract unit price per square yard (square meter) for TEMPORARY EROSION CONTROL BLANKET or TEMPORARY HEAVY DUTY EROSION CONTROL BLANKET. The work of removing, storing, and reinstalling the blanket over areas to be reworked more than once will not be paid for separately but shall be included in the cost of the temporary erosion control blanket or temporary heavy duty erosion control blanket. SECTION 281. RIPRAP
281.01 Description. This work shall consist of furnishing and placing bedding
material, a protective course of stone or broken concrete laid as riprap for erosion protection or sediment control.
281.02 Materials. Materials shall be according to the following.
Item Article/Section
a.Stone ................................................................................................. 1005.01
b.Broken Concrete ................................................................................ 1005.02 CONSTRUCTION REQUIREMENTS Art. 281.03 Riprap
281.03 Preparation. The bed for the riprap shall be excavated to allow the
finished surface to conform to the lines specified. At the toe of the slope, the riprap shall commence on a continuation of the slope after excavation to accommodate the full depth of fabric, bedding lift, and riprap specified.
281.04 Placing. No riprap shall be placed until the preparation has been
approved by the Engineer. Installation of filter fabric and bedding material will be required under stone riprap gradations RR 4, RR 5, RR 6, and RR 7 for all uses, and under broken concrete and stone, or broken concrete dumped riprap when used for erosion protection. The fabric shall be installed according to the plans and Section 282. The placement of material shall begin at the lower elevations, progressing up the slope.
a.Stone Riprap. Class A1 bedding material shall be used with riprap Classes A4, A5, B4, and B5. Class A2 bedding material shall be used with riprap Classes A6, A7, B6, and B7. When filter fabric is used, the following substitutions of bedding material may be made: Quality B may be used in lieu of Quality A; Gradation CA 3 may be used in lieu of Gradation RR 1; and Gradation CA 1 may be used in lieu of Gradation RR 2. Bedding material shall be spread uniformly on the filter fabric to the lines specified. Placing of material by methods which will tend to segregate particle sizes within the bedding will not be permitted. Any damage to the surface of the bedding material or the filter fabric during placing of the bedding shall be repaired before proceeding with the work. Compaction of the bedding material will not be required; but it shall be finished to present a reasonably even surface, free from mounds, windrows, or depressions. The thickness of the stone riprap lift shall be according to the following table. Gradation Min. Thickness Bedding Thickness RR 1 & RR 2 6 in. (150 mm) - RR 3 8 in. (200 mm) - RR 4 16 in. (400 mm) 6 in. (150 mm) RR 5 22 in. (550 mm) 8 in. (200 mm) RR 6 26 in. (650 mm) 10 in. (250 mm) RR 7 30 in. (750 mm) 12 in. (300 mm) Stone riprap shall be placed to the lines and grades shown on the plans. All tapers between minimum thickness and any high points shall be at a uniform rate. There shall be no abrupt changes in the riprap surface. The riprap shall be placed to its full course thickness in one operation and in such a manner as to avoid displacing the bedding material. The riprap shall not be placed or dropped from a height of more than 1 ft (300 mm). Placing riprap by dumping into chutes or by similar methods likely to cause segregation of the various sizes will not be permitted. Riprap Art. 281.07 The finished riprap shall be reasonably well graded with a minimum of voids. The desired distribution of the various sizes of stones shall be obtained by selective loading of the material at the source, by controlled dumping of successive loads during final placing, or by other methods of placement which will produce the specified results. Rearranging of individual stones by mechanical equipment or by hand will be required to the extent necessary to obtain a reasonably well-graded distribution of stone sizes as specified above.
b.Broken Concrete Riprap. Bedding placement, when required, shall be as described for stone riprap in (a). The individual pieces of broken concrete shall be placed by hand, flat upon the slope. The pieces shall be laid with close joints, the larger pieces being placed in the lower courses. Any open joints shall be filled with spalls thoroughly rammed into place. The finished surface of the riprap shall present an even, close surface, true to the lines, grades and sections given.
c.Stone or Broken Concrete Dumped Riprap. Bedding placement, when required, shall be as described for stone riprap in (a). The dumped riprap shall be a minimum of 12 in. (300 mm) thick. Dumped riprap of stone or broken concrete, as specified, shall be placed on slopes or in channels by mechanical means. End dumping of material using mechanical equipment will be permitted, provided the larger stones or pieces of broken concrete are well-distributed and the entire mass, in final position, is roughly graded to conform to the gradation specified. Placement by dumping into chutes or other methods likely to cause segregation will not be permitted. The finished riprap shall be reasonably free from objectionable pockets of small pieces and clumps of large pieces, and the surface shall be shaped to follow the grade of the slope or channel. Rearranging of the dumped stone or broken concrete by mechanical equipment or by hand will be required only to the extent necessary to remove objectionable pockets or clumps of small or large material, and to obtain a surface reasonably true to line and grade.
281.05 Disposal of Surplus Material. Surplus or waste material shall be
disposed of according to Article 202.03.
281.06 Method of Measurement. This work will be measured for payment in
tons (metric tons); or measured in place, and the area computed in square yards (square meters). The area for measurement will include the upper sloped surface of the riprap and upper horizontal surface of the toe anchor. Filter fabric will be measured for payment according to Article 282.08.
281.07 Basis of Payment. This work will be paid for at the contract unit price
per square yard (square meter) or per ton (metric ton) for STONE RIPRAP or STONE DUMPED RIPRAP, of the class (stone quality and gradation) specified; BROKEN CONCRETE RIPRAP; or BROKEN CONCRETE DUMPED RIPRAP. Filter fabric will be paid for according to Article 282.09. Art. 282.01 Filter Fabric SECTION 282. FILTER FABRIC
282.01 Description. This work shall consist of furnishing and installing
geotechnical filter fabric on a prepared earth surface.
282.02 Materials. The filter fabric shall be according to Article 1080.03.
CONSTRUCTION REQUIREMENTS
282.03 General. The filter fabric shall be stored above the ground, inside and
away from sunlight at temperatures less than 140 °F (60 °C), and protected from damage. The exposure of the filter fabric to the elements between laydown and cover shall be a maximum of 14 days.
282.04 Preparation. The depth and area of excavation shall not exceed the
dimensions necessary to properly place the filter fabric. Prior to the installation of the fabric, the surface shall be cleared of debris, sharp objects, and trees. Tree stumps shall be cut to the level of the prepared ground surface. If stumps cannot be cut to the ground level, they shall be completely removed. All wheel tracks, ruts, or surface irregularities in excess of 2 in. (50 mm) in depth shall be graded smooth or otherwise filled with soil to provide a reasonably smooth surface. The filter fabric shall not be placed until the preparation has been approved by the Engineer.
282.05 Placement. The fabric shall be unrolled directly over the surface
either by hand or by mechanical methods, provided the surface is not rutted. The long dimension of the fabric shall be parallel to the centerline of the channel or shoreline. Overlaps in the fabric shall be placed so that any upstream strip of fabric will overlap the downstream strip, and the upslope roll shall overlap the downslope roll. The fabric shall be laid loosely, free of folds and creases. The fabric shall be turned down and buried 2 ft (600 mm) at all exterior limits, except where a stone filled key trench is provided below natural ground. As the riprap proceeds up the grade, the top edge of the fabric shall be buried as a part of the last operation. Fabric of insufficient width or length to fully cover the specified area shall be lapped or sewn. The minimum laps for lap only areas are 12 in. (300 mm) and for sewn areas are 4 in. (100 mm). When sewn, the fabric shall be stitched at a minimum rate of four stitches per 1 in. (25 mm) with high-strength polyester, polypropylene, or kevlar thread. The seam strength shall be equal to or exceed the minimum required grab strength of the fabric according to Article 1080.03.
282.06 Securing Pins. Securing pins for anchoring filter fabric shall be
nominally 3/16 in. (5 mm) diameter steel bars, pointed at one end and fabricated with a head to retain a steel washer having an outside diameter of not less than 1 1/2 in. (38 mm). The length of the pin shall not be less than 12 in. (300 mm). Securing pins shall be inserted through both strips of overlapped cloth at not greater than the following intervals along a line through the midpoint of the overlap.
Referenced in this section
Sections that cite this one
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Source: Illinois Standard Specifications for Road and Bridge Construction, 2022 Edition. Pages 148–151 of 1,217. View official source ↗