TRENCHLESS TECHNOLOGY PROJECT ON CITY ISLAND IN THE CITY OF NEW YORK

摘要

City Island is an old fishing community with an aging infrastructure located in New York City's borough of The Bronx. The New York City Department of Design and Construction (NYC DDC) was replacing 14,300 feet of 6", 8" and 12" diameter distribution water mains throughout City Island. In addition, the NYC DDC was replacing 8,500 feet of sanitary and storm sewers ranging from 10" to 60" in diameter as well as 36 catch basins. The work encompassed 32 city blocks. City Island, in total, runs approximately 1-1/2 miles long and 1/4 mile wide and has one main avenue running north to south at its midpoint. This nautical town has a variety of boat yards, shops, and restaurants that are always bustling in the Spring and Summer months with tourists from all over the Northeast. The City of New York (NYC) has the right of eminent domain over all city streets, which required Con Edison's gas mains in direct interference with the new sewer and water mains had to be moved. Con Edison had to relocate 5,000 feet of 2" and 4" diameter high-pressure (99 psi MAOP) gas mains and 55 gas services ranging from 1/2" to 1" diameter. The new gas mains had to be relocated to the sidewalk adjacent to 97 trees that could not be damaged in any way. Thus conventional open-trench excavation was out of the question. A special permit had to be obtained from the New York City Parks Department and Con Edison had to guarantee the safety of the root systems of these trees before work could begin. After careful study Con Edison decided to use a trenchless technology method called directional boring along with coiled polyethylene (PE) pipe to install the new gas mains. This method of installation minimized inconvenience to the City Island residents and tourists. It also eliminated the closing of traffic lanes, which would have been necessary with open cutting the entire 5,000 feet for gas main installation. This trenchless technology was particularly effective in City Island since the soil was predominantly clay and contained minimal amounts of rock. The City Island community was very satisfied with the results of this project. Trenchless technology allowed shops and restaurants to thrive during their busy tourist season.