The Horizontal Directionally Drilled Installation of Dual Parallel 3,220-Foot Fusible PVC Pipelines

Sacramento Regional County Sanitation District (Regional San) completed Phase 1A of the Sacramento Power Authority Cogeneration Recycled Water Pipeline Project (SPA Project) in July 2016. Construction of the second phase, 1B, is estimated to be completed in March 2018. The purpose of the project is the conveyance of approximately 1,000 acre-feet per year (AFY) of tertiary filtered and disinfected recycled water to the Sacramento Power Authority Cogeneration Plant for use as cooling water, and an additional 1,700 AFY for irrigation at landscaped areas, parks, school playing fields, and golf courses adjacent to the 1B pipeline alignment. Phase 1A of the SPA Project included the trenchless installation of 3,220 lineal feet of dual fusible PVC (fPVC) pipelines (18-inch reclaimed water, and 10-inch side stream effluent) via horizontal directional drilling (HDD). This paper will discuss the benefits of trenchless installation as it relates to this project, the design criteria used to develop a horizontal directional drilling plan, the challenges encountered during construction, and the overall risk mitigation strategy that resulted in a successful trenchless HDD installation of parallel dual pipelines.