Hamon Infrastructure constructed a 7-span, 3-unit highway bridge over both Plum Creek and the UPRR in Douglas County immediately south of Castle Rock, Colorado. The Crystal Valley Parkway Bridge was constructed to provide a grade-separated crossing of the UPRR and eventual access to I-25 for the residents of a new sub-division being developed in Douglas County. Hamon Contractors met all the challenges associated with building a major structure in the riparian environment of Plum Creek. These challenges included extensive storm water management and control, management of noxious weeds, wetlands mitigation and endangered species (P.M.J.M) mitigation.
Background
Major contract work included 41,000 cubic yards of roadway embankment; 14,500 cubic yards of select structural backfill; driving 1,800 linear feet of steel pile and sinking 2,500 linear feet of 72 inch diameter caissons. Hamon also formed, placed and finished 5,700 cubic yards of bridge concrete and erected 8,900 linear feet of 84” prestressed bulb tee girders. During the construction of the project Hamon crews placed 1,600 cubic yards of deck concrete in one continuous pour 102 feet wide.
Hamon’s competitive pricing and aggressive scheduling allowed Douglas County to build out the entire bridge rather than building this bridge in phases over time.
The project was completed within the required 12 month duration
Project Benefits
Habitat Conservation: The Crystal Valley project impacted approximately 3.5 acres of PMJM habitat. The mitigation / conservation methods employed by Hamon included the following:
Construction near the habitat was scheduled to start after the hibernation season (November 1 to April 30).
Permanent exclusion zones in prime habitat were established in prime habitat where no access was allowed.
Access pads with minor drainage culverts were established to allow for species connectivity.
Silt was kept out of Plum Creek and prime habitat with silt fence and erosion control blankets outside the exclusion zones.
Riprap for stream bank protection was covered with soil wherever possible.
Revegetation consisting of native species and willow cuttings was installed after construction.
