Plum Creek Raw Water Return Pipeline

Under a design-build contract, Providence conducted the planning, permitting, design, and installation of 4.3-miles of 30-inch raw water welded steel pipe (WSP) to deliver renewable water supplies from the Plum Creek Diversion facilities to the Town’s existing raw water delivery system within an aggressive 30-month schedule.

Project services included easement acquisition support; detailed pipe and tunnel design; construction specifications; extensive permitting; third party reviews; public outreach; detailed cost estimating; coordination with Federal, State, and local regulatory entities; as well as coordination with Castle Rock’s raw water pump station project.

One of the key objectives for the Town of Castle Rock’s long-term water plan was to maximize the use of their local renewable water supplies. To accomplish this, the Plum Creek Diversion structure and pump station, located downstream of the Town along Plum Creek near Sedalia, was used to bring renewable water back into the Castle Rock system. PIC designed the Plum Creek Raw Water Return Pipeline to convey water from the diversion pump station back to the Town for reuse.

The project involved hydraulic, soils, and loading evaluations associated with developing technical specifications related to wall thickness, coatings, and manufacturing. The project’s planning phases involved performing alternative analyses to route the pipeline through portions of the Town of Castle Rock, the Town of Sedalia, and Douglas County. The design phases involved developing technical specifications, drawings, and geotechnical design reports associated with the project’s numerous tunnels. The pipeline’s route analyses involved evaluating costs, public impacts, environmental compliance, schedule, and constructability. The analyses were the basis for obtaining Douglas County Location and Extent Permit, as well as U.S. Army Corps of Engineers and U.S. Fish and Wildlife approvals.

The WSP project involved two long stream crossings in Douglas County, both with an average length of 130-feet, one of Plum Creek and one of East Plum Creek. All crossings were concrete encased and installed under the Colorado Fish and Wildlife 404 permit standards in addition to local flood plain division permits. Project also included four 54-inch trenchless crossings which were necessary to cross State Highway 85, North Meadows Drive, the BNSF and UPRR Railroads, and a congested area of large diameter sanitary sewer utilities.