Trenchless Technology

JAN 2019

Trenchless Technology is the premier communications vehicle for the trenchless industry. Through our multiple platforms, readers receive insights into the trenchless industry, as well as keep connected to the latest news, products and projects.

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36 T R E N C H L E S S T EC H N O LO GY JA N UA RY 2019 M I C H E L S CO R P.'S microtunneling team extended the limits of technology by successfully completing a 470-ft long tunnel with a tight, U- shaped vertical curve under the Tualatin River in Tualatin, Oregon. Michels used its new Herrenknect AVN 1800 Microtunnel Boring Ma- chine (MTBM) and specialty 84-in. OD reinforced concrete pipe (RCP) to com- plete the tight 650-ft radius curve. The Tualatin Interceptor and Siphon Improvements King City Siphon will re- place the original wastewater intercep- tor which was constructed in 1974 and has reached the end of its useful life. The new siphon – a non-gravity fed util- ity - was fitted with seismically resilient pipe that is better suited for the corro- sive environment within the pipeline. The specialty pipe was designed in and shipped from Malaysia for this project. The tunnel was bored in less than a month, holing through in late Novem- ber; comprehensive planning took sub- stantially longer. Michels worked on the design-build project with project owner Clean Water Services, general contractor Mortenson, and lead engi- neer Kennedy Jenks for more than a year to design and complete it. That process included a comprehensive re- view of Michels' many trenchless con- struction options to determine which one had the best potential for success. Ultimately microtunneling was deter- mined to be the best fit. The Tualatin project required the boundary-pushing design to allow the siphon system to meet the required functionality with a minimal construc- tion footprint. Typically, a microtun- neling project would be launched and received from watertight, secant pile shafts up to 60 ft deep to allow for a straight alignment or minor horizontal and vertical curves. However, this proj- ect used 20-ft-deep sheet piling shafts, resulting in significant cost savings. Michels took on the challenging task by proposing the vertical U- shaped curve alignment, even though a simi- lar project with such a large curve or tight radius had not been previously executed in North America. Michels engaged many industry leaders to complete the project. Jackcontrol AG helped in designing and supplying the RCP jacking pipe and hydraulic joints. Aldea Services assisted in technical de- sign of the tunnel and provided over- sight. Herrenknecht consulted on the MTBM capabilities and purchase of a new AVN 1800. A VMT gyro steering control system was configured on the MTBM to ensure tight line and grade tolerances were met. In addition, Mi- chels included Derrick equipment and P U S H I N G T H E B O U N D A R I E S Tualatin River Project Extends the Capabilities of Microtunneling By Brenden Tippets

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