Contact: Schiavone Construction Co. LLC
Construction of the 72 nd Street Station, Part of the 2nd Avenue Subway Project in NYC
Using Customized Enclosed Mucking System
Secaucus, NJ. SK Constructors Joint Venture (a joint venture of Schiavone, J.F. Shea and Kiewit) is engaged in the mining of the new 72nd Street Station Cavern, G3/G4 tunnels and complete final concrete lining. The entire project duration is 37 months, during which all excavation, waterproofing, concrete lining, utility and street restoration must be completed. The contract value is $447M, so to complete this volume of work in the allowable time is an aggressive undertaking to say the least. To further complicate the situation, all rock can only be removed via two 28 foot diameter shafts located at the corners of 2nd Avenue and 69th and 72nd Streets. The excavation is by drill and blast method, which will result in the removal of over 375,000 loose cubic yard of rock. The initial stage of the rock excavation utilized a crane and bucket method (see shaft and crane pictures). SSK realized that as the excavation work developed, the conventional crane and bucket method could not keep up with the rock yield; thus, a high capacity removal system was required. The result was the design and construction of a pile supported/steel frame muck handling system, which is fully cladded with insulated panels that serve to mitigate noise, dust and an overall impact to the highly residential neighborhood. Two identical systems were constructed at each shaft. The approximate dimensions are 160 feet long by 45 feet high by 32 feet wide. The system is comprised of a gantry hoist and twelve dump stations oriented in two parallel rows of six. Each dump station accommodates a 25 yard muck bucket that is hydraulically dumped into a waiting tri-axle truck below (refer to the picture of a dumping operation in progress). Each system was designed to handle up to approximately 600 loose cubic yards per shift. Some normal operating inefficiency was expected; however, actual daily yields have been satisfactory to meet the schedule goal of the Project.
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