Bridge Deck Runoff: Water Quality Analysis and Best Management Practice Effectiveness

AIDC project number: RR08.13


Robert A. Perkins (UAF)

  • US Department of Transportation (RITA)
  • Alaska Department of Transportation & Public Facilities
  • Start Date: Jul 1, 2008
  • End Date: Sep 30, 2010

Project Summary

ADOT&PF is responsible for more than 700 bridges, most of which span water bodies. Are these water bodies affected by storm water (rain and snowmelt) runoff from the bridge decks? What are the regulatory and economic constraints on the agency regarding this runoff? What actions, if any, should ADOT&PF take? These are questions addressed by this project. Best management practices are mandated or recommended for certain bridges. Which BMP is best for each bridge is not defined in law, but requires selection by ADOT&PF after consideration of the bridge characteristics, costs and benefits of candidate BMPs, and practicalities of construction. While many practical BMPs are in place for runoff from streets and parking lots, far fewer options exist for bridges and fewer still work in Alaska's cold climate. Transportation officials in Norway, Canada, and northern U.S. states were contacted in the search for economical and practical BMPs for bridge decks. The project includes development of a database of all Alaskan bridges and their parameters relevant to storm water runoff. From those parameters, a numerical rating is being developed for each bridge. This rating, together with certain regulatory thresholds, will be used to determine if BMPs are required.