The Dahlia St. roadway and drainage improvements on State Highway 224 to East 78th Ave. project included the construction of new storm drainage, curb, gutter, sidewalk and driveways, new traffic signals, and rebuilding the roadway to three lanes with bike lanes in each direction.

Major components of this project included major utility relocations to increase Adams County ROW, 3,810 LF of RCP storm line from 66-inch diameter to 18-inch diameter with 154 planned utility crossings, 31 precast drainage structures, 1,000 LF of new 12-inch water main, 14 new water services, 5,200 SY of varying flatwork and 9,400 tons of HMA paving.

The control and maintenance of traffic is a significant portion of the project
for storm line and waterline installation and sidewalk, driveway, and roadway
construction. This section of roadway is an integral artery for Commerce City
industry and CDOT coordination is required for traffic impacts that occur due to
work in and near SH224.

The implementation of multiple MHTs, road closures and project phasing approaches have been utilized to keep the project moving forward despite challenges coordinating utility relocations, unforeseen utility conflicts and inter-agency coordination.

The first phase of the project required the coordination of major utility relocations
based on the initial design to facilitate increasing Adams County ROW and place
detour pavement to allow traffic to be maintained on Dahlia during mainline
storm installation and the subsequent concrete and asphalt paving. The storm
construction started at a tie-in to existing infrastructure at 78th Avenue adjacent to the O’Brian Canal.

Major challenges included the initial use of slide rail shoring dictated by design due to sandy soil conditions and proximity to the existing road and utility conflicts in 77th Avenue that required a full closure of the intersection and coordination with Centurylink to relocate facilities, as well as coordinating an open-cut mainline storm pipe crossing at SH224 and subsequent milling, paving and striping within CDOT ROW while minimizing traffic impacts to SH224.

IHC Scott was able to accelerate the project schedule by obtaining approval for an
engineered stacked trench box shoring system for the storm line installation in lieu of the slide rail system. This change increased productivity and significantly decreased the timeline. Once the storm line was installed within a hundred feet of the crossing at SH224, The prep and grading for flatwork and asphalt, successfully coordinating access with the various property owners affected by the work through the completion of paving the east side of the project and allowing traffic to shift and construction to begin on the west side. The flexible project phasing approaches, budget and schedule management with Adams County and other stakeholders have allowed this project to be successful, making IHC Scott one of Adams County’s preferred contractors in their public works department.