The project consists of the excavation, trucking and disposal of roughly 88,000 cy of contaminated soil at a former MGP (manufactured gas plant) site in Rockaway Park, New York. The depth of excavation varies from 8ft below grade to 2ft below grade. All of the 8ft excavations are conducted within a 120 ft x 200 ft enclosure, which is relocated at the completion of the excavation beneath the footprint of the tent. Temporary sheeting is installed to support the excavation. DNAPL barriers, which are specially designed sheet piles with over-sized interlocks, were installed at the northern perimeter of the job site to a final depth of 50 to 120 ft below grade. The interlocks were then flushed and grouted to provide an impermeable barrier that should contain the deeper contaminants on site. Once the excavation is complete, a site wide cap of sand and gravel will be placed over the 9.7 acre site.

Posillico designed and implemented the use of temporary sheet piles as excavation support that would be installed around the perimeter of the tent. The use of sheet piles for excavation protection, as opposed to benching, as called for in the design drawings, reduced the number of tent moves from upwards of 24 to 14. Posillico designed and installed a steel base frame for the tent to sit on. This eliminated the need to use a crane to move the tent, it can be relocated instead of using a combination of pay loaders and backhoes. This engineered out the constant high winds experienced at the site, increasing and allowing more flexibility for scheduling the tents relocation.

Posillico was able to work with the client to resolve issues relating to the max GW for trucks leaving the site, community resistance to the project and short comings in the original design so that the project stayed on track for it's accelerated completion.