Weymouth was originally opened in 1940, and is one of the largest water treatment plants in the country. It serves all of Los Angeles, Orange, San Diego, Riverside, San Bernardino and Ventura Counties. The plant currently treats & delivers 520 million gallons of water per day.The project involves an upgrade and expansion consisting of placement of underground cast in place hydro conduit and 3 cast in place structures. All of the tunnel work will be done in an excavation approximately 25 to 30 feet deep. The three structures involve slab on grade, cast in place walls and cast in place structural decks which are being placed monolithically with the walls.