The changing tide - island restoration project uses GPS-enabled machine control

The use of GPS-enabled automatic grade control technology to ensure accurate dirt subgrade elevation is becoming more and more of a mainstream construction practice. Dirtmoving is usually a fairly straightforward, stable situation—in contrast to the recent utilization of a high-speed stakeless GPS grading system to restore Yellow Bar Hassock marsh island in Jamaica Bay, located in a Hudson River estuary between the New York City boroughs of Brooklyn and Queens. The biggest differences between Yellow Bar Hassock marsh island and a typical dirtmoving project were the fill material and varying tides. On the island project, 375,000 cubic yards of wet sand that were dredged from nearby Ambrose Channel were used to restore about 40 acres on the 70-acre island.