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

Geotextiles in Embankment Damsexpected amount of strain in a geotextile in order to account for the long-term creepthat will take place. Calculation procedures for determining stress levels in ageotextile are provided by (Koerner, 2005a).4.3 Environmental degradationThe service life of geotextiles can be dramatically reduced by environmentaldegradation. Environmental factors leading to such degradation include prolongedexposure to ultraviolet light, high temperatures, oxidation, hydrolysis, chemicaldegradation, radioactive degradation, and biological degradation (Koerner, 2005a).Ultraviolet light is problematic where geotextiles are left exposed without covering.High temperatures may be a problem during construction or in certain specialapplications. Most buried applications protect geotextiles from high temperaturesand from oxidation. Shallow burial of only a few feet will not protect a geotextilefrom oxidation. Shallow burial applications should be expected to have shortenedlife spans due to oxidation of the geotextile.Hydrolysis is rarely a problem unless the geotextile is exposed to fluids with low orhigh pH, and then this is polymer specific. One study (Grubb et al., 2001) ofpolyester and polypropylene geotextiles used in the disposal of gold mine tailingsdemonstrated that highly alkaline wastes in the residual products of a cyanidebeneficiation process cut average retained strengths by more than 40% at 360 days ofexposure.Chemical degradation is polymer specific; for example, diesel fuel is known todegrade polypropylene and polyethylene geotextiles. Contact with radioactive soil orgas in not normally anticipated for water retention embankments and is principally asissue in industrial and waste containment settings. Geotextiles manufactured frommodern polymers are not degraded by biological organisms.4.4 Installation damageGeotextiles, geomembranes, and other geosynthetic materials are susceptible toinstallation damage. Contamination, degradation, abrasion, puncture, and tearing ofgeotextiles during the construction process is likely to occur unless a strict regimenof quality assurance and quality control is followed from the beginning to the end ofconstruction process. The issue is so significant that Chapter 6 of this report detailsconstruction methods.80