protection for vertical walls and piers) starts at the shoreward end and 

 proceeds away from the shore, or starts adjacent to the protected structure 

 and proceeds to the outer limits of the scour protection. 



When securing pins are required to prevent the geotextile from slipping 

 during construction, they shall be 3/16-inch in diameter, of steel, pointed 

 at one end and fabricated with a head to retain a steel washer having an 

 outside diameter of no less than 3.8 centimeters (1.5 inches). The pins 

 should have a minimum length of 46 centimeters when used in soils having a 

 medium to high density. For loose soils, longer pins should be used. They 

 should be inserted through both strips of overlapped fabric at the midpoint 

 of the overlap. The maximum pin spacing along overlaps should be 0.6 

 meter (2 feet) for slopes steeper than IV on 3H, 1 meter (3 feet) for 

 slopes of IV on 3H to IV on 4H, and 1.5 meters (5 feet) for slopes flatter 

 than IV on 4H. Additional pins shall be installed as necessary to prevent 

 any slippage of the geotextile, regardless of location. 



e. Repair Method . If the geotextile filter is damaged during the 

 placement of the fabric or of the stone (or blocks) on the fabric, it 

 should be repaired as follows: Cut the damaged part of the fabric out of 

 the sheet and position an undamaged piece of geotextile filter, 1.2 meter 

 (4 foot) longer in each direction, where the fabric has been removed. 

 Extend the edges of the new fabric 0.6 meter (2 feet) beyond and under the 

 edges of the undamaged original filter. 



f. History of Uses in Coastal Construction . The first use of geo tex- 

 tiles was as a filter beneath an interlocking concrete block revetment on 

 the Atlantic coast in South Palm Beach, Florida, in 1958 (Dallaire, 1977). 

 The fabric used was woven of monofilament yarns of polyvinylidene chloride 

 (saran) , containing stabilizers to make the filaments resistant to ultra- 

 violet and heat deterioration. The equivalent opening size (EOS) was equal 

 to a U.S. Standard Sieve No. 100 and the percent of open area (POA) was 4.6 

 percent. Physical properties were as follows: tensile strength approxi- 

 mately 890 newtons (200 pounds) (warp), 445 newtons (100 pounds) (fill); 

 elongation at failure less than 33 percent; burst, 1 790 kilopascals (260 

 pounds per square inch); puncture, 310 newtons (70 pounds); abraded strength, 

 250 newtons (57 pounds) (warp), 85 newtons (19 pounds) (fill). 



In the following 4 years, geotextile filters were used in a number of - 

 coastal structures on the east coast of the United States. In every in- 

 stance, the fabric was the same as in the first use at South Palm Beach. 

 While the fabric performed satisfactorily in these installation, field 

 observations during construction led to the conclusion that construction 

 would be simplified, and a superior structure would result, if a filter 

 could be developed with higher tensile strength, burst, puncture and 

 abrasion resistance for use in conjunction with quarry stone construction 

 materials. Development of a geotextile woven of polypropylene monofilament 

 yarns consisting of at least 85 percent propylene and containing stabilizers 

 and inhibitors to make the filament resistant to ultraviolet and heat 

 deterioration was completed in 1963. The new fabric had an EOS equal to a 

 No. 70 U.S. Standard Sieve and a POA of 5.2 percent. Physical properties 

 were as follows: tensile strength approximately 1 690 newtons (380 pounds) 

 (warp), 979 newtons (220 pounds) (fill); elongation at failure less than 30 



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