underlying mud. As the casing was advanced, traditional rock tooling was used to drill and/or clean out the soil/rock from within the casing. At the conclusion of the drilling operations at each deep foundation location, a clean, open, stable hole was provided through the rockfill by using the temporary casing. Then, a pile was lowered to the bottom of the cased hole, was set for verticality and horizontal positioning, was braced, and then clean sand was placed within the annulus between the inside diameter of the casing and the outside diameter of the pipe pile. The sand served to both protect the pile and to keep it in its target location. At the end of this sequence of operations at each location, the temporary casing was extracted, which allowed the predrilling to continue to other piling locations. This sequencing allowed the driving of the steel pipe piling to the target depths to be completed more efficiently and more safely. Tough Site Access The causeway is effec- tively a 28 mi (45 km) long tunnel, with access from the east near Ogden or access from the west. When travel- ing around the lake to gain access to the work area, the drive required the better part of an afternoon from the time one leaves Ogden to the time one arrives at the desert-like remote location on the western shore of the Salt Lake. A trip from the east to the bridge site also required more than an hour’s drive across the rock topped causeway, which also increased one’s odds of getting a flat tire. As an anecdotal story, a lowboy truck once brought a drill rig in from the east and shuttled the drill to the site of the bridge. After the drill was unloaded, the truck and trailer had to be lifted off the causeway with a crane and physically turned 180 degrees, as no room was available for the permit-length trailer to turn around! The other difficulty of Abandoned rail cars penetrated by drill tooling that had to be “cut away” during excavation This order of operations also proved to be a very efficient means of accurately locating the pile foundations. That is, had pile driving through rock and boulders been possible, “walking” of the piles out of the correct positioning and verticality would have likely occurred. In general, the contractor used the oscillator to advance the casing through approximately 70 ft (21 m) of rockfill comprising the causeway within the lake. While drilling, workers encoun- tered abandoned wood ties, old rails and even railroad cars. In theory, the causeway’s rockfill would have extended about 50 ft (15 m) from the surface; however, the additional depth indicated the amount of settlement the causeway experienced over time, as well as the amount of maintenance undertaken by Southern Pacific and then UPRR to upkeep the track at grade. 100 • DEEP FOUNDATIONS • JULY/AUG 2018 working on the causeway was deal ing wi th the natural elements of a jobsite that made it seem the work was occurring on another planet. The wind never stopped blowing across the lake, and, on some days, the same large waves that threatened the original causeway required a shutdown of field operations due to safety concerns. The blowing wind created salt foam that would cover any exposed equipment, whether a pump or a drill rig, and was adversely affected by the saline environment. Aerial view of causeway’s difficult site access Summary Few sections of track in the western U.S. have had as rich a railroad and engineering history as the Great Salt Lake Causeway. The causeway itself is a case history of railroad engineering vs. the incredible strength of Mother Nature. Working on projects such as this allow modern construction and railroad engineers to take a moment to reflect on the difficulty of the original construction of the transcontinental railroads in an age before modernized equipment. There is no ques- tion that this project was a fascinating one with which to be involved. As with any great project, there were a variety of challenges to overcome, including the weather and remote site. And, of course, the team had to drill through 100 years of material that had been placed within the causeway to keep the trains running on a stretch of railroad that was trying to be reclaimed by the Great Salt Lake. The collaboration between the project stakeholders to deliver a solution that met the needs of such diverse parties demon- strated that there can be a successful balance between the environment and the needs of the modern railroad. Additional information about the causeway and the breach can be found at https://www.youtube.com/ watch?v=uhRV8QBUUY0. civil engineering from the University of Illinois - Urbana Champaign, and is in his 17 year in specialty geotechnical construction and engineering. He is licensed as a registered professional engineer in Missouri, Illinois and Arkansas. Hill is a member of DFI, ADSC and AREMA, including AREMA Committee member Chapter 1: Subgrade & 8: Foundations and Concrete Structures. Jeff Hill, P.E., is the director of business development for Hayward Baker (HBI). He received a B.S. degree in th Carol A. Ravano, P.E., is a senior associate and company-wide manager of the McMillen Jacobs Associates Railroad Engineering and CM Group. She has 25 years of geotechnical and civil engineering experience, and specializes in the design and management of railroad geotechnical and tunnel rehabilitation projects, many of which have been constructed under live track conditions.
