Tunnel Business Magazine

FEB 2018

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Page 23 of 43

TUNNELINGONLINE.COM TBM: TUNNEL BUSINESS MAGAZINE // FEBRUARY 2018 the design modifications included reduced construction, commu- nity impacts and maintenance costs by eliminating the construc- tion of two shafts in a residential neighborhood. These changes also accelerated the overall project schedule. "The decision to use a curved drive was a matter of practical- ity in terms of schedule, neighborhood impact, cost and overall project goals, all of which were successfully met and delivered by implementing the curve design," Super Excavators project man- ager Justin Kolster said. The approximately 700-ft long microtunnel run, completed in August 2015, started out with a 140-ft straight alignment, fol- lowed by a 340-ft long curve on a 915-ft radius, and finished with a straight 210-ft run. Hanson Pipe (now Forterra) of Columbus, Ohio, was the pipe supplier for the proje ovided laser guidance equipment and Akkerman supplie er Excavators retained Scott Ludlow, S.J. Ludlow Consulting Engineers Inc., of Indianapolis, Indiana, to complete the engineering design neces- sary to obtain final approval of curved VECP erved as consultant for the owner. Setting New Standards e recently, the district completed a project that not only sets a new mark for the longest curved drive complete America, but also one of the longest projects. On Dec. 5, 2017, Ward and Burke Construction Ltd. broke through on the first leg of the Kingsbury Run Culvert Repair Project, marking the completion of a 2,722-ft long drive with multiple curves. The longest overall drive completed in the United States to date is 3,000 ft, while the longest curved drive was 2,427 ft (completed by Ward and Burke in Canada in 2013). Value engineering resulted in the final microtunnel drive length, which had multiple horizontal curve components, including one curve radius of 787 ft. Crews used a Herrenknecht A or micr er d . 1 and recovered on Dec. 5, installing 60-in. wet-cast RCP jacking pipe from Forterra using molds brought from Germany. The project was originally specified as three separate drives. Elimination and relocation of shaft locations helped avoid exca- vations in ground that was potentially contaminated with PCBs. Crews used the Jackcontrol system to help distribute jacking loads and avoid p e system. "The key to successfully completing long-distance drives is en- suring properly managing friction loads," said Colin Irwin, project manager for Ward and Burke. Ward and Burke equippe with five interjacking stations in the event extra pushing force was needed; ultimately three IJSs were used. Ward and Burke used a slurry separation plant from ITE GmbH. The dual lubrication pumps provided bentonite to the head and to the annulus. Other Notable Projects Superior Stones Canal CSO Improvements The total scope of this $2.1 million project award to Super Excava- tors includes rehabilitation and replacement of pump stations, con- struction of CSO storage tank and pumping facility, trenchless and open cut construction of forcemains and gravity sewers and other associated work. The purpose of this project is to increase the capac- ity of the sewer system, and reduce the amount of sewage discharg- ing into the Cuyahoga River. The microtunneling includes a single run of 760 lf of 48-in. RCP using an Akkerman SL60 (62.5-in. OD) through stiff silty clay soils. The run includes a contractor-designed curved alignment and is at a 5.5 percent slope. The project began in October 2017 to be completed by the end of October 2018. Indepen- dence Excavating is the prime contr er. The value-engineered curve allowed the drive to avoid the foun- dation of a historic building along the alignment. "The curve on the Superior Stones project was a risk mitigation measure to help ensure that the building was damaged," said Doug Gabriel, Deputy Director of Engine . The curved drive was successfully completed in fall 2017 using Forterra dry-cast pipe. Westerly Low Level Relief Sewer The Westerly Low Level Relief Sewer (WLLRS) Project includes regulator modifications, upsizing of dry weather outlet (DWO) sew- ers, and approximately 2,600 lf of new 72- in. diameter relief/stor- age sewer with relatively shallow depths of 8 to 25 ft. TH completed the design of this project in 2016. The contractor (Ward & Burke) holed out on Sept. 8, 2017. The 2,650-ft long tunnel was completed using a slurry microtunnel. High-strength RCP was used as the final liner in the tunnel and was strong enough to take the expected jacking forces even on an 1,850-ft long drive. The 1,850-ft drive had been the longest microtunnel drive ever f ompletion of the first leg of the Kingsbury Run project. Looking Ahead Despite all the work complete , more work re- mains. This spring, the district will advertise for the Doan Valley Relief and Consolidation Sewer. Designe oject included a curved drive in the design – a first for the district. Pre- viously, the microtunnels were designed as a straight drive with value engineering proposals resulting in the incorporation of curved drives. "Whatever we do, we try to give the contractor flexibility," Ga- y of our designs give the option of multiple meth- ods so that we can take advantage of what the contractor knows and does best." Recent bids have allowed methods including microtunneling, jack-and-bore, open-cut or conventional tunneling, depending on the situation. "We go into our projects with our eyes wide open and don't get stuck on one particular construction method," Gabriel said. As part of Project Clean Lake, a multi-billion-dollar consent decree program to minimize sewer overflows, the district has undertaken increasingly complex microtunneling drives. F E A T U R E S T O RY

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