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. Aggregate Ditch Art. 283.03 Slope Pin Spacing Steeper than 1:3 (V:H) 2 ft (600 mm) 1:3 (V:H) to 1:4 (V:H) 3 ft (900 mm) Flatter than 1:4 (V:H) 5 ft (1.5 m) Each securing pin shall be pushed through the fabric until the washer bears against the fabric and secures it firmly to the surface. Additional pins, regardless of location, shall be installed as necessary to prevent any slippage of the filter fabric. When the Engineer determines that the proper lap is not being maintained by the use of pins, the fabric shall be sewn according to Article 282.05.
282.07 Protection. The fabric shall be protected during construction from
contamination by surface runoff. Fabric damaged during installation or during placement of riprap shall be replaced or repaired. Repairs shall be made by removing the material around the damage and covering it with a patch of fabric using an overlap of 2 ft (600 mm) in each direction. The patch shall be held in position with securing pins.
282.08 Method of Measurement. This work will be measured for payment in
place and the area computed in square yards (square meters). The buried edges of the fabric will not be measured for payment and the overlap joints and seams will be measured as a single lift of material.
282.09 Basis of Payment. This work will be paid for at the contract unit price
per square yard (square meter) for FILTER FABRIC. SECTION 283. AGGREGATE DITCH
283.01 Description. This work shall consist of furnishing and installing
aggregate in roadside ditches.
283.02 Materials. Materials shall be according to the following.
Item Article/Section
a.Aggregate Ditch ................................................................................. 1005.01
b.Filter Fabric ........................................................................................ 1080.03 CONSTRUCTION REQUIREMENTS
283.03 Aggregate Ditch. The stone aggregate ditch shall be constructed on
filter fabric without any bedding material. The filter fabric shall be constructed according to Section 282, except that the edges along the centerline of the ditch shall be turned down and buried 6 in. (150 mm), the upstream and downstream edges shall be turned down and buried 12 in. (300 mm), and securing pins at overlaps shall be inserted at each edge of the ditch bottom and at intervals of not greater than 5 ft (1.5 m) extending up the slopes.
Referenced in this section
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Source: Illinois Standard Specifications for Road and Bridge Construction, 2022 Edition. Pages 151–152 of 1,217. View official source ↗