Recycled Material Highway Construction Environmental Assessment: Life Cycle Based Risk Assessment of Recycled Materials In Roadway Construction

This paper uses a life-cycle assessment (LCA) framework to characterize comparative environmental impacts from the use of virgin aggregate and recycled materials in roadway construction. To evaluate site-specific human toxicity potential (HTP) in a more robust manner, metals release data from a demonstration site were combined with an unsaturated contaminant transport model to predict long-term impacts to groundwater. The LCA determined that there were reduced energy and water consumption, air emissions, Pb, Hg and hazardous waste generation and non-cancer HTP when bottom ash was used in lieu of virgin crushed rock. Conversely, using bottom ash instead of virgin crushed rock increased the cancer HTP risk due to potential leachate generation by the bottom ash. At this scale of analysis, the trade-offs are clearly between the cancer HTP (higher for bottom ash) and all of the other impacts listed above (lower for bottom ash). The site-specific analysis predicted that the contaminants (Cd, Cr, Se and Ag for this study) transported from the bottom ash to the groundwater resulted in very low unsaturated zone contaminant concentrations over a 200 year period due to retardation in the vadose zone. The level of contaminants predicted to reach the groundwater after 200 years was significantly less than groundwater Maximum Contaminant Levels (MCL) set by the U.S. Environmental Protection Agency (US EPA) for drinking water. Results of the site-specific contaminant release estimates vary depending on numerous site and material specific factors. However, the combination of the LCA and the site specific analysis can provide an appropriate context for decision making. Trade-offs are inherent in making decisions about recycled versus virgin material use, and regulatory frameworks should recognize and explicitly acknowledge these trade-offs in decision processes.

• Record URL:
  • http://rmrc.wisc.edu/wp-content/uploads/2012/10/P43Final.pdf
• 
• Summary URL:
  • http://rmrc.wisc.edu/project-43/
• Corporate Authors:

  University of Wisconsin, Madison

  Recycled Materials Resource Center, 2241 Engineering Hall
  1415 Engineering Drive
  Madison, WI  United States  53706

  University of New Hampshire, Durham

  Recycled Materials Resource Center
  Environmental Technology Building, 35 Colovos Road
  Durham, NH  United States  03824

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Carpenter, Alberta C
  • Gardner, Kevin H
• Publication Date: 2007-8

Language

• English

Media Info

• Media Type: Digital/other
• Edition: Final Report
• Features: Figures; References; Tables;
• Pagination: 23p

Subject/Index Terms

• TRT Terms: Bottom ash; Environmental impacts; Groundwater; Leachate; Life cycle analysis; Metals; Recycled materials; Road construction; Toxicity; Trace elements
• Subject Areas: Environment; Highways; Materials; Pavements; I15: Environment; I30: Materials;

Filing Info

• Accession Number: 01531731
• Record Type: Publication
• Files: TRIS, ATRI, USDOT
• Created Date: Jul 26 2014 12:51PM