TRANSBAY SANITARY SEWER FORCE MAIN REPLACEMENT
Over 3 million gallons of sewage per day is collected within Coronado's city limits (including Naval Air Station North Island) and pumped across San Diego Bay for eventual treatment in Point Loma. The Transbay Sanitary Sewer Force Main Replacement project replaced an existing ductile iron sewer force main that had been in service for over 30 years and was nearing the end of its useful life. The project utilized state-of-the-art horizontal directional drilling methods in order to install the line within a very small construction footprint and under a tight schedule. The work consisted of a 3,200' long bore that extended 50' below the bottom of San Diego Bay, with simultaneous horizontal directional drilling occurring on each end until the pilot bores met in the middle. The new line has an expected 75-year lifespan and now allows the old line to serve as a completely redundant backup force main. By addressing sewer infrastructure problems before actual failure, the City avoided the devastating financial and environmental impacts of the short-sighted "fix-it-when broken" policies often found with municipal agencies. The project was successfully completed with minimal impact even though it was located directly adjacent to the vital economic marketplaces of Seaport Village and the Coronado Ferry Landing and two large condominium developments. It has won the following awards to date: American Society of Civil Engineers' 2008 Outstanding Project and the American Public Works Association Project of the Year Award. View slide show.