The Niles-Newark Intertie Pipeline (NNIP) is a future key element of the Alameda County Water District’s long-range program for conservation, water supply, and water quality management to meet future water demands for the Cities of Newark, Union City, and Fremont, California. In the future, this pipeline will convey water from the District’s Peralta-Tyson Well Field in Fremont to the District’s brackish water desalination plant in Newark. A routing study determined the best alignment for the NNIP and evaluated the best location for a crossing of Interstate 880 (I-880), a major freeway bisecting the NNIP alignment. Alternatives evaluated for the I-880 crossing included an overhead crossing, microtunneling and horizontal directional drilling (HDD). The design and construction of the I-880 crossing has proved to be one of the most challenging aspects of this project, and is the focus of this paper. In this paper, the authors will review key criteria considered when evaluating each of the crossing alternatives, and will provide an in-depth look at the risks identified for the selected design alternative (HDD). This paper will also examine in detail how several of the risks identified for future HDD construction were mitigated through the completion of a pilot project at the crossing location.