WISE Local Infrastructure Project in the Town of Castle Rock Demanded a Unique Set of Design and Construction Solutions

In support of its goal to secure a long-term and sustainable water supply, the town of Castle Rock, Colorado, successfully negotiated inclusion in the regional WISE (water infrastructure and supply efficiency) project requiring the construction of a water transmission line to the South Metro WISE Authority project. The five miles of waterline was constructed within an existing Xcel Energy utility easement from the Parker Water District distribution system at Outter Marker Road to the Ray Waterman Regional Water Treatment Center. Material selection for the 5-mi 36-in. connecting line presented a significant challenge considering the overhead Xcel Energy power line along the alignment. Any metallic components of the line would require cathodic protection. The undulating terrain and rocky soils presented further challenges, including road and drainage basin crossings, requiring three horizontal directional drills (HDD), ranging from 700 to 1,700 ft in length. Installation was completed using a hybrid PVC approach, consisting of fused PVC pipe for all trenchless and restrained pipe and bell-and-spigot PVC for all else. This paper will detail the project’s design and construction phases, expanding on the material options debated, and how the combination of fused and belled PVC joints minimized cathodic protection requirements and overall project costs.