PARENT SESSION
PS5 - TIEs & TREs
Sunday, 17 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P067) Assessing the Effects of Leachate from Tire Shreds Used as Roadbed Fill on Auquatic Organisms.
Sheehan, Patrick*,1, Warmerdam, John1, 1 Exponent, Oakland, CA
ABSTRACT- The use of tire shreds as engineered subbase material for specific roadway applications has been proposed by the California Integrated Waste Management Board as a means of reusing a resource that would otherwise require disposal. A proposed application of this light fill material is in roadbeds that are located in or adjacent to waterbodies. The chemicals in the leachate from tire shreds used as roadbed fill may pose a potential threat to exposed aquatic organisms. To assess the risks to aquatic organisms from this reuse of tires, toxicity tests, chemical analyses and toxicity identification evaluations (TIEs) were conducted with the leachate from tire shreds in roadbed test sites with fill both above and below the water table. Geochemical and transport models were used to estimate the distance of groundwater/leachate travel before the chemicals contributing to toxicity are attenuated due to natural processes. Study results indicate that the undiluted leachate from the above the water table application is not toxic to either daphdids or fathead minnows. The leachate from the below the water table application effected both the survival and reproduction of Ceriodaphnia and the growth of exposed fathead minnows. Based on the TIE, the toxicity is primarily associated with metals and specifically the formation of iron precipitates on test organisms. Geochemical and groundwater modeling results indicate that the attenuation of toxicity is expected to be rapid (to occur in groundwater within a short distance of the fill) where the groundwater is aerobic and the pH is neutral to basic.
Key words: tire shreds, toxicity, aquatic organisms, TIE