The Calleguas Municipal Water District has completed the horizontal directionally drilled (HDD) segment of construction of an ocean outfall located in Port Hueneme, California. The new outfall is the termination of a salinity management system developed by the Calleguas Creek Watershed Management Plan, and connects onshore pipeline facilities at Port Hueneme to a diffuser located 3,900 feet offshore. The outfall consists of approximately 2,300 feet of 36-inch high density polyethylene (HDPE) installed via HDD connecting to 2,700 feet of 30-inch steel seafloor pipe. The HDD segment exited about 1,300 feet offshore, and involved reaming, pipe layout and pullback using the assistance of divers, barges and tug boats. Highlights of the project included a 60-foot elevation difference between entry and exit points and an exit location below 30 feet of water.This paper details events and responses as they occurred during HDD construction. Particular challenges were expected during the sequencing and execution of drilling near the exit location, especially with regards to drilling fluid escape and borehole stability. The solutions to these challenges will be explored and discussed for future HDD and ocean outfall work.
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