The Santa Ana River Interceptor (SARI) Line is a 23-mile-long wastewater pipeline that extends from the boundary of Orange and San Bernardino counties in Southern California to the Orange County Sanitation District (OCSD) sewage treatment plant. Several segments run adjacent to and under the Santa Ana River and nearly 4 miles of the pipeline were in jeopardy of failure during heavy rainstorms. To ensure the long-term integrity of the pipeline, protect public health and safeguard the environment, the Orange County Flood Control District, in cooperation with other stakeholders, embarked on the Santa Ana River Interceptor Relocation Project to relocate and replace the SARI Mainline with a new pipeline. A portion of the project consisted of 4,000 feet of 101.5-inch OD microtunnel completed in four drives including installation of 2,900 feet of 84-inch ID reinforced concrete pipe and 1,100 feet of 99.5-inch ID steel casing. This design also required excavation of several deep shafts in difficult locations. Ground conditions along the four alignments were an extremely abrasive mixed face combination with soft to stiff silt and loose sand, gravel, sand, and clay exhibiting a flowing behavior with cobbles and some boulders. The groundwater table ranged from the tunnel invert at the lowest point to approximately 17 feet above the tunnel invert at the highest. Originally designed as a traditional conservative microtunnel project with several short, straight drives, the SARI Mainline offered an ideal opportunity for an innovative value engineering proposal. By suggesting a standard curve microtunnel drive and a compound curve microtunnel drive utilizing an innovative hydraulic joint the project contractor was able to eliminate shafts and combine multiple drives on the project. Reinforced Concrete Pipe (RCP) with Carnegie style bell and spigot joints was designed for use on the sections of the project being considered for the curved drives. After revising the design and incorporating appropriate changes to the standard pipe, the RCP manufacturer concurred that the pipe would perform through the curves, an important step in the value engineering (“VE”) process. Preliminary sketches of a curved alignment were prepared to determine the potential curve radii. Based on the sketches and load calculations it was determined that RCP with the incorporation of the hydraulic joint was more than sufficient to handle the potential joint deflection. The coordination and cooperation between the agency, contractor and manufacturer resulted in a savings to the project of over $1 million and offered a 20% reduction in the tunneling schedule.