Geotextiles in Embankment Dams - Association of State Dam Safety ...

Geotextiles in Embankment Damsspecific chemicals (leachate) is covered under ASTM D5322 and D5496. Chemicaldegradation may be a factor in waste containment applications such as tailings dams,and industrial effluent storage facilities.Radioactive Degradation – This type of degradation is only an issue for wastecontainment situations and is not considered problematic for embankment dams.Biological Degradation – Micro-organisms (such as bacteria and fungi) do not readilydegrade geotextiles, because the high molecular weights leave very few chain endswhere biodegradation might begin.Other Degradation – Other degradation processes might include ozone, rodent ortermite attack. Synergistic attack (a combination of two or more degradation factorsacting at the same time) is a complex issue, but has not been found to be a problemin most geotextile applications.Aging – Specific test standards have not been developed to measure aging ofgeotextiles. However tests on exhumed samples generally show that geotextiles arestill in good to excellent condition after decades of service.2.13 Application of geotextiles as functional elements in embankment damsIn the Introduction, the functions of all geosynthetics in Dam Construction werebriefly discussed. It should be noted that with the exception of the liquid barrierfunction, geotextiles are shown as a possible choice to fulfill all other functions. It isimportant from a designer’s point of view to know what the functional application isand where it can be used relative to embankment dams in order to consider ageotextile for use in a particular function.2.13.1 Filtration of soils particlesAs discussed in the Introduction, a geotextile (nonwoven or woven) performs a filterfunction if it allows water to pass while controlling the soils migration through thegeotextile. Sometimes the filtration application is a dual function (i.e. filtration anddrainage).• Filter between zones of protective stone and embankment soils or transitionsoils• Internal chimney drain upstream filter• Internal toe drain filter48