Colusa National Wildlife Refuge Bridge and Auto Tour Improvements


Diamond D constructed improvements to enhance pedestrian and Americans with Disabilities Act (ADA) access to a migratory waterfowl observatory at Colusa National Wildlife Refuge. We widened an existing 63 foot long bridge from 16 feet to 32 feet, reconditioned an access road, reshaped the road to improve drainage and constructed a new entrance gate for the refuge. We also constructed a gravel parking lot, a restroom facility, and a concrete passenger unloading pad with an ADA accessible ramp and walkway that connected to the observatory.

The bridge was widened by placing four 63 foot long, four foot wide precast post-tensioned concrete panels with 140 ton crane on top of a driven pile foundation.


  • Develop SWPPP
  • Survey and layout project
  • Place environmental protection
  • Excavate native material from nearby seasonal wetlands
  • Place and compact native fill, recondition roadway and grade site and roadway
  • Place 1700 tons of aggregate base/ clay mixture for access road and parking area
  • Form and pour 100 yards of concrete for pad and walkway
  • Install pit toilet
  • Install entrance gate
  • Drive six 45 foot long piles
  • Pour and form pile caps
  • Place and secure four 63 foot long, four foot wide precast, post-tensioned concrete panels
  • Install steel guard rail and posts

Owner: Federal Highway Administration, Central Federal Lands Highway Division

Contract Value: $757,571.97 Completion Date: January 30, 2008

Reference: Available Upon Request