Abstract:
The Gowanus Canal is a 1.7 mile long and 30m wide canal located in the industrial zone of Brooklyn which discharges into the New York Harbor. It was built in the mid-1800s for the purpose of industrial transportation. A century-long industrial waste water discharge with the overflow of surface water and untreated sewage made the canal one of the most contaminated water bodies in the United States. Due to its proximity to Manhattan and the high-end residential neighborhoods in Brooklyn, the area near the canal started to experience rapid gentrification, prompting the EPA to start the cleanup preparation work in 2013. The cleanup scope of work involves dredging of highly contaminated sediment, placement of clean soil material and its capping, and construction of retention tanks. In addition, the deteriorated bulkheads facing the canal have to be reconstructed at many locations before dredging.
In 2018, as part of the bulkhead reconstruction of the pilot work, press-in piling was added for testing after the use of a vibratory hammer had caused major ground settlement and resultant closure of the promenade of a high-end supermarket. The one-month-long press-in piling test exhibited much less noise, vibration, and settlement; satisfying most of the project requirements. Following the test result, a few sections of the project have been utilizing press-in piling for sheet pile installation. The soil conditions consisted of the top layer of contaminated soft soil and the underlying gravel layer with equivalent N-values reaching from 20 to 100. Coated Z-shaped sheet piles in lengths of up to 70 feet were installed with predrilling. In order to verify the sheet pile wall’ s integrity against potential migration of contaminated water, sensors to detect complete engagement of the interlocks were welded at the bottom of each sheet pile pair.