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Geotechnical Engineering Seminar
Friday 05 May 2017, 12:00 - 13:00

Please join us on Friday, May 5th for the weekly Geotechnical Engineering Seminar from Noon to 1PM in ECJ 7.208. This week’s speaker is Dr. Paul C. Schmall, with Moretrench. The presentation is entitled: Ground Freezing for the Northern Boulevard Crossing. The speaker has kindly provided the pizza.


The Northern Boulevard Crossing of the MTA Capital Construction East Side Access (ESA) project in Queens, New York  is a 125-ft long sequentially excavated (SEM) tunnel mined between two 85-ft deep, diaphragm wall-supported access shafts.  The project was considered the most challenging aspect of the overall project for several reasons. The tunnel was situated approximately 55 ft below the water table and would be mined through glacial deposits including silts, sands, boulders, till and bedrock. In addition to crossing beneath the heavily travelled Northern Boulevard itself, the tunnel alignment also passed beneath a pile-supported elevated railway line and a below-grade active subway structure. A number of conventional excavation support and groundwater control options were initially considered to facilitate the tunneling, but discarded in light of various restrictions. Ultimately, a horizontally-installed protective frozen arch above the tunnel alignment extending to bedrock was deemed the only viable approach in the highly challenging subsurface conditions.  Dr. Schmall’s presentation will discuss  the design, installation and operation of the frozen arch, together with heave and settlement control measures instituted in support of the ground freezing operation.


Paul C. Schmall is a Senior Vice President and Chief Engineer for Moretrench, a nationally recognized company providing a comprehensive range of construction and specialized geotechnical services.  He has responsibility for the company’s complex groundwater control projects involving dewatering, grouting, ground freezing and artificial recharge for underground construction. Over the course of his career, Dr. Schmall has engineered and managed numerous technically complex projects in the United States and overseas. He is proactive in advancing the state of the practice by sharing his experience and expertise with the engineering community through seminar and conference presentations, instruction of several short courses, and by serving on industry committees. Dr. Schmall is a co-author of the third edition of Construction Dewatering and Groundwater Control, published in 2007.

Location ECJ 7.208