One of the first steps taken was the dredging of the marsh to allow the passage of the city's garbage scows. The landfill accepted its first scow in April 1948. Shortly before the landfill opened, an expansion of the landfill project was approved by the City Planning Commission, which called for a project organized in 13 sections. The landfill was planned to be structured in layers, with a layer of garbage covered by a layer of ash (the remains of burnable trash from the city's incinerators), another layer of garbage, and then a layer of dirt to contain the smell. At the end of the landfill's usable life, new real estate would be created, allowing the landfill to top off at above sea level. The plan called for Fresh Kills to be used for 20 years, then developed as a multiuse area with residential, recreational, and industrial components. In 1950, the height was increased to . By 1955, Fresh Kills was the largest landfill in the world, serving as the principal landfill for household garbage collected in New York City.