The Pima County Regional Wastewater Reclamation Department (RWRD) operates and maintains 3,500 miles of sanitary sewer lines in Pima County, Ariz. The primary goal of the Sabino Creek Pump Station and Force Main Project was to replace a wastewater gravity pipe wash crossing, servicing an area near Canyon Ranch Resort that crossed the Sabino Creek to the east.
Flooding in 2006 washed out portions of Sabino Creek, exposing the pipeline and making it vulnerable to damage. Temporary stabilization efforts were conducted. However, to mitigate risk and ensure public safety, RWRD constructed a new 36-ft-deep lift station and a 6-in. 3,300-ft force main to eliminate the existing Sabino Creek gravity sewer crossing.
Another aspect of the project was to involve the community while achieving the goals of the project. The Sabino Creek Pump Station services 260 single-family homes and the Canyon Ranch Resort west of Sabino Creek. Both entities requested limited site disturbance, leaving the natural vegetation intact, and that any new structures blend in with the existing landscape.
As the project progressed, it became apparent that the project site was located in an Arizona Upland biotic community, which housed native plant and animal species. A biological evaluation was required to identify the species which might be adversely affected by the project. Another challenge involved the placement of the lift station. There was not a suitable location for utility placement or access to the area for maintenance purposes once the lift station was built, so an original walking path was used for construction access to the site.
It was determined that more than 2,000 ft of the 3,300 ft force main would be directionally drilled. This allowed for the force of the main to go under washes and limit the disturbance of natural habitat. Armorock Polymer Concrete manholes were selected as structural, sustainable and corrosion-proof alternatives to concrete manholes.
The new pump station and force main now provide the primary means of wastewater conveyance in the area, eliminating the exposed pipe and the potential risk of catastrophic failure during a future storm event