212GEOTEXTILES

212.1DESCRIPTION—This work is furnishing and installing geotextiles for the class specified.

212.2MATERIAL—Use geotextiles as specified in Section 735 for the specified class and type.

and with a 1 1/2-inch washer head. If allowed, alternate securing devices that provide equivalent or greater anchorage may be used.

212.3CONSTRUCTION—As shown on the Standard Drawings, and as follows:

specified for the class of fabric used. Do not allow traffic or construction equipment directly on the fabric.

does not bridge depressions in the soil and is not damaged by rock projections. Lay the fabric flat in the prepared trench without stretching. Lay the top of the fabric back on the sides to allow for the placement of the aggregate backfill and pipe. Place and compact the aggregate backfill up to the pipe invert level and install pipe. Continue filling the remainder of the trench with compacted aggregat e backfill, as indicated. Backfill aggregate and install pipe in a manner to prevent damage to the fabric. Lap out or overlap the geotextile as shown on the Standard Drawings for the specific type of subsurface drain being constructed. Use fabric of a width to allow a minimum trench-width overlap across the backfill at the trench top where required. Overlap adjacent ends of rolls an amount equal to the trench width. Do not allow the fabric to be exposed for more than 2 weeks without covering with aggregate.

specified in Section 865.3 or Section 866.3.

Roll out the geotextile over the prepared surface . Place fabric in a loose and unstretched condition , but without folds or wrinkles. Do not drag the geotextile on the ground during placement and handling. Overlap fabric roll-ends and edges a minimum of 6 inches with adjacent material. Place cover material by back dumping then spread the cover material ahead of all equipment. Do not make abrupt turns with tracked equipment that would result in pulling, folding, or tensioning of the fabric. Steel pins, as specified in Section 212.2, may be used to secure the fabric before placement of the cover material to prevent lif ting of the fabric by wind. Do not allow the fabric to be exposed for more than 2 weeks before covering with subbase or other required cover material. Compact the cover material as specified in Section 206.3.

and grade the surface to a relatively smooth condition. Undercut areas of soft material and replace with acceptable compacted material, as directed. Lay the fabric on the prepared area in a loose and unstre tched condition. Overlap all adjacent edges a minimum of 1.5 feet. For underwater placement, overlap a minimum of 3 feet. Offset adjacent roll ends a minimum of 10 feet. Anchor the fabric in place by securing pins or other acceptable methods, along overlaps, at the spacing shown in Table A. Overlap the fabric so the upslope fabric is overtop the downslope fabric and the upstream fabric is overtop the downstream fabric. Place securing pins on a maximum 6 foot spacing on the unlapped

portions of the fabric, such as perimeters. Securing pins may be eliminated for slopes flatter than 6:1, provided that aggregate, rock, or other acceptable means are used to secure the fabric.

TABLE A Securing Pin Spacing Slope Steeper Than 3:1 3:1 to 4:1 Flatter Than 4:1 Pin Spacing along Overlaps

2 feet

3 feet

5 feet

Cover the fabric with the covering material as soon as possible. Do not expose the fabric for more than 2 weeks. Place cover material in a manner that slippage of the cover material over the fabric does not occur. Do not drop rocks directly on the fabric from a height greater than 1 foot. Do not allow the rock placement procedure to puncture or damage the fabric. W hen placing rock greater than 1 foot in siz e, use a minimum 6-inch layer of bedding on top of the geotextile to prevent damage to the fabric.

with the cross sections. Remove any object that may puncture the geotextile. Roll out the geotextile over the prepared subgrade. Place the geotextile free of wrinkles. Do not drag the geotextile on the ground during placement or handling. Overlap adjacent rolls in a minimum of 2 feet. Do not allow any equipment directly on the geotextile until it is covered to full depth of subbase. Place subbase material by back dumping then spread the subbase ahead of all equipment at full plan depth. Place subbase material so that equipment is never in direct contact with the fabric. Do not make abrupt turns with tracked equipment that would result in deformation of the fabric. Maintain positive slope for drainage. Steel pins, as specified in Section 212.2, may be used to secure the fabric before placement of the subbase to prevent lifting of the fabric by wind. Compac t the subbase material as specif ied in Section 350.3. Fill any wheel ruts that form during construction with additional subbase to maintain plan profile. Do not remove the wheel ruts by blading the wheel ruts level.

212.4MEASUREMENT AND PAYMENT—

Measured by the length of trench.

For the type indicated or specified, except when used as silt barrier fence paid for under Section 865 or Section 866.

For the type indicated or specified.