In the United States there are over 270 million tires discarded annually and these tires often end up in landfills. Tire-derived aggregate (TDA), made by cutting scrap tires into small pieces, has been used in a wide range of civil engineering projects such as landfill, retaining wall, embankment and septic system. Specially, TDA can provide additional infiltration volume to allow for groundwater recharge and to reduce the runoff volume. In addition, TDA can provide underground water storage to reduce peak runoff values in areas where infiltration is not desirable. Upon contact with water, however, there is concern that TDA may leach organic and inorganic compounds, leading to water quality impairment of nearby ground and surface waters. On the other hand, previous researches have reported that TDA can remove contaminants from stormwater runoff, including a portion of the dissolved fraction, such as manganese, zinc, and phosphorus.
To investigate the impact of TDA on stormwater runoff, leaching behavior of TDA have been studied under both field and laboratory conditions. Long-term laboratory leaching studies indicate that arsenic, cadmium, chromium, selenium, and zinc exceeded the drinking water standards. However, the use as fill material is typically designed for short-term water inundation of 72 hours or less. Analysis for organics has indicated that leached hydrocarbons should require for future monitoring. Field studies of unsaturated TDA have shown that iron, zinc, and manganese are the primary constituents that leach from TDA. However, TDA in stormwater underground storage and infiltration facilities is unlikely to cause either drinking water standards nor aquatic environmental standards to be exceeded.
The results show that using TDA to improve stormwater quality has the potential to help achieve stormwater management goals, while also turning a waste stream into a useful product source to develop cost-effective water treatment technologies.
Speaker(s)
Yiling Chen, John Gulliver, University of Minnesota