【国外标准】 Standard Specifications for Silt Fence Materials

This specification covers requirements and test methods for geotextile fabrics and associated components used in temporary silt fence applications. It is applicable to the use of a geotextile as a vertical permeable interceptor designed to remove suspended soil from overland, nonconcentrated water flow. The function of a temporary silt fence is to trap and allow settlement of soil particles from sediment laden water. The purpose is to greatly limit the transport of eroded soil from the construction site by water runoff. Fibers used in the manufacture of geotextiles for silt fence, and the threads used in joining geotextiles by sewing, shall consist of long-chain synthetic polymers composed of at least 95 % by weight of polyolefins or polyester. They shall be formed into a stable network such that the filaments or yarns retain their dimensional stability relative to each other, including selvages. Geotextiles and related materials used for temporary silt fence shall conform with required grab strength, permittivity, apparent opening size, and ultraviolet stability. The prescribed support posts are described in the specification.1.1 This specification covers requirements and test methods for geotextile fabrics and associated components used in temporary silt fence applications. Table 1 is a material purchasing specification based on AASHTO M 288. Table 2 is a specification to be used in areas of high water flow. The specification in Table 2 is a higher strength, higher flow option than Table 1. Table 2 properties can withstand more hydraulic flow than the specification listed in Table 1. The Table 2 specification should be used in sensitive applications, such as areas near regulated waters and wetlands, but also areas that are prone to high flow runoff that require increased structural stability. The design professional has the option of Table 2 where the specifications listed in Table 1 are not sufficient to meet the demand of runoff.1.2 Both specifications are applicable to the use of a geotextile as a vertical permeable interceptor designed to remove suspended soil from overland, nonconcentrated water flow. The function of a temporary silt fence is to trap and allow settlement of soil particles from sediment-laden water. The purpose is to greatly limit the transport of eroded soil from construction sites and other areas affected by water runoff.NOTE 1: It should be noted that proper installation and maintenance are critical for the effective functioning of silt fence.1.3 The tests used to characterize the silt fence are intended to ensure good workmanship and quality and are not necessarily adequate for design purposes in view of the wide variety of possible sediments and performance objectives.1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.NOTE 2: Although the Table 1 specification should be acceptable in most erosion control applications, it should be noted that an alternative silt fence specification for a higher water flow rate, listed in Table 2, may be required by the engineers in areas that are susceptible to higher water runoff; using Table 2 specification will minimize safety hazards such as hydroplaning in these areas.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.