The Eastern Municipal Water District provides water to the Inland Empire region of Southern California supplied from an agreement with the Metropolitan Water District of Southern California (MWD) via the Colorado River Aqueduct and State Water Project and local groundwater supplies, recycled water and desalination efforts. To ensure capacity to provide water to customers as the area continues to grow, the District designed the Murrieta Road Transmission Pipeline project. The pipeline supports the District’s new groundwater desalination facility and allows additional water to be supplied reliably to the surrounding community.
The project included three different components – the Murrieta Road Pipeline, the Perris Valley South Pipeline, and the Brackish Water Pipeline – and involved the open cut and trenchless construction of nearly 8,300’ of pipe.
The Murrieta Road Pipeline involved the open cut installation of 5,900’ of 36” CML&C pipe, 800’ of 42” CML&C pipe, and microtunnel construction of 445’ of 60” welded steel casing and 445’ of 42” carrier pipeline under Salt Creek completed in a single drive.
Perris Valley South Pipeline involved the open cut construction of 695’ of 36” CML&TW and mortar coated pipe, 125’ of 24” CML&TW and mortar coated pipe, and 125’ of 18” CML&TW and mortar coated and CML&EC pipe. This work was performed at the EMWD Desalination Complex in Menifee, CA.
The final scope of work, the Brackish Water Pipeline, included 225’ of 24” PVC pipeline at the EMWD Desalination Complex.
All three pipelines involved all the appurtenances, connections to existing pipelines, valves, blowoffs, cathodic protection, permitting, traffic control, site access and security during construction, surface restoration including paving after excavation, backfill, and compaction was complete, landscape restoration at the Desalination Complex including planting and irrigation restoration, and testing, disinfection, and startup.
The microtunnel portion of the project included launch and reception shafts, with the final tunnel at 31’ below the ground surface. Dewatering was a major concern given the proximity of Salt Creek, and six dewatering wells were used to draw the groundwater below the tunnel depth. In addition to dewatering, settlement monitoring of the ground surface and nearby utilities was required to ensure no over excavation took place during tunneling, as flowing soil conditions were a concern. Ground conditions in the vicinity included artificial fill, younger alluvial
soils, and older alluvial deposits consisting of silty, clayey sand and poorly to well graded sand with varying amounts of gravel.