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2013 Outstanding Underground Project The Learning Curve Nozzleman Qualification for New York City Subway Tunnels By William T. Drakeley Jr. and Scott Rand Tinstallation of subway tunnels, shafts, and mittee C660, is a program for certification of-The ACI Shotcrete Nozzleman Certificationprogram, developed and maintained by ACI Comhe MTA CC/Long Island Railroad/East SideAccess Project is an extension and new cross passages for the New York City metro area. nozzlemen employed for the application of dry- or These new subway systems and adjoining con- wet-mix shotcrete. While an ACI Certified Noz- nections allowed the use of the shotcrete process, zleman would be able to demonstrate basic based on certain criteria specified by bid docu- knowledge and skill in shotcrete application, there mentation. This was to be the first major infra- are other aspects involved in shotcreting in an structure use of shotcrete within the boundaries underground environment that require specific of New York City. additional training. There are many craftsmen in Fellow shotcrete experts and co-author Bill the underground construction community that Drakeley have watched this project unfold with have skill and experience in concrete, including a certain level of anticipation. Their primary some experienced in shotcrete application for preoccupation was to ensure proper shotcrete ground support and familiar with the needs for placement was conducted safely by a qualified safety and work-related qualifications in the workforce in an underground environment. tunnel environment. However, they are not ACI- Drakeley was hired to qualify workers for the certified nozzlemen, and, unfortunately, the project. Once the workers were qualified, he educational curriculum and the performance test remained on the project as a consultant and led (structural test panel) do not directly relate to oversight to the work in progress at the request placing underground shotcrete. The test is there- of the project owner. From the outset of the shot- fore not necessarily useful in assessing the ability crete production, the learning curve for proper of a person to apply shotcrete in an underground application techniques had to be successfully construction application. undertaken at an accelerated pace. Given the ACI Committee C660 is not presently con- unprecedented nature of the project, the stakes sidering a curriculum or certification specific to could not have been higher for the future use of tunnel and mining applications. It is important the shotcrete process in the greater New York City to note that the original ACI 506.3R was a non- metropolitan area. mandatory guide for an engineer who wished to design a program for nozzleman certification to Specifications include in a project specification. Even though The design specifications required each many specifications list it as such, ACI 506.3R person applying shotcrete to demonstrate accept- was never a certification program in and of itself. able proficiency, which was defined as applica- In fact, one of the reasons the guide was offi- tion that met the requirements of both the cially withdrawn was because of the confusion specification and the proficiency requirements it often created when blindly referenced in a of ACI Committee C660, Shotcrete Nozzleman project specification. Certification. The contractor was also required to provide operators qualified to perform work Training conforming to requirements of ACI 506R, Due to the lack of official training programs “Guide to Shotcrete,” and ACI 506.3R, “Guide for shotcrete applications in the underground to Certification of Shotcrete Nozzlemen” (this environment and the overwhelming need for such document has been withdrawn by ACI because education, we recommended that a program fol- all nozzleman certification efforts now fall under lowing the applicable training curriculum and ACI Committee C660), with operators certified examining procedure of ACI Committee C660 be according to the requirements of the ACI established for the purpose of qualifying craftsmen Shotcrete Nozzleman Certification program. for application of shotcrete specific to the require- 32 Shotcrete • Winter 2014


2014WinShotcreteEMag
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