The ENVIRONMENT

A goal of avoiding or minimizing impacts to the Iowa River Greenbelt was pursued aggressively throughout the planning of the Iowa River Bridge project. The placement of the project, the construction methods used, and the post-construction program all fit the desire to tread as gently as possible through the Greenbelt.

• Land Use: Of the three locations considered for the bridge, the final location required the least amount of Greenbelt land and impacted the smallest possible area. The crossing also avoids better-quality forest areas.
   
• Land Impact: The bulk of bridge construction activity took place within the footprint of the bridge's permanent location. The "launching" of pre-constructed bridge sections across completed piers from the east side of the valley further minimized activity on the valley floor. Environmental impact boundaries were clearly marked throughout the construction site.
   
• Water Quality: Bridge piers straddles the river; none were located in the water. Runoff from the bridge is channeled into an enclosed system of drainage pipes, then to silt basins off either side of the bridge. The basins are located away from the river.
   
• Visual Impact: The steel I-girder design is slender; longer spans reduce the number of piers needed, which minimizes visual obstructions at river level. Differences can be seen in the various bridge concept designs proposed for this project.
   
• Soil Erosion: Soil is loose and highly prone to erosion by wind and water. Contractors were required to keep the amount of land cleared at any one time to a minimum. Extensive erosion control measures were put in place during clearing and grading, to minimize soil loss and siltation into the waterway.
   
• On-Site Monitoring: A biologist monitored construction activities at the site to ensure they did not present a threat to the Iowa River and its plant, animal and aquatic populations.
   
• Post-Construction: Disturbed areas were restored to pre-construction contours and re-seeded/replanted. Project impacts are monitored 3 to 5 years after construction is completed.