RETC 2023 | PREVIEW
TRACK: MICROTUNNELING AND TRENCHLESS TUNNELING Monday, 12 June – afternoon session
Track sponsor: Stantec Chairs: Jay Shankar, Amtrak; Leah McGovern, STV
There are to be four papers presented in the first day’s afternoon session track on Microtunneling and Trenchless Tunneling – the only dedicated track during RETC 2023, although small bore, microtunneling and pipe-jacking are among trenchless methods that feature in parts of some other projects to be described in papers to the conference. The first paper is entitled ‘The Versatility of Tunneling and Trenchless Methods for Sustainable Grid Construction’, and is by Peter Schmaeh and Dr Marc Peters of Herrenknecht. Description of the details to be covered discuss how underground high voltage power cables are coming to be important in replacing above-ground and vulnerable overhead lines when seeking to support development of a sustainable power grid that features renewable energies. The details say that public concerns and environmental awareness have been enabling new, modern power cables to be installed underground with smart tunneling and trenchless solutions in both urban and countryside locations, and for crossings and landfall sections that bring ashore cables tied to offshore generation facilities, such as windfarms. Methods from the tunneling and pipeline industries enable flexible solutions and alignments to be developed, including versatile tunnel concepts and installation of protective pipes, such as enabled by Herrenknecht’s E-Power Pipe and Direct Pipe systems. The second paper is ‘Curved Microtunneling to Reduce Disruption in
City Environment’, by Daniel Cressman of Black & Veatch. The paper describes the work on a sewer in Toronto to install
a concrete pressure pipe by microtunneling methods to take the alignment under a wide road and then stay within a narrow
permitted corridor for the project. Slurry microtunneling was used to deal with mixed face conditions under the high groundwater level in the urban environment and the curved alignment was used also to help negotiate subsurface obstacles, including other existing utilities, condominium tiebacks and a bridge structure. Third of the four papers is ‘Missouri River Intake Screen Structure and
Tunnel: Overcoming Underground Challenges to Build Vital Infrastructure’, by Ryan Ward of Michels Trenchless. With microtunneling selected as the excavation method with the highest probability of success in river valley deposits (sands, gravels, cobbles and boulders) under high hydrostatic head, the construction work on the bank of the Missouri River, in North Dakota, sunk a shaft with secant piles for the drive to get underway. The tunnel linked to a cofferdam in the river, where intake screens would be installed for the operational phase of the project which is part of the Red River Valley Water Supply Project. While the tunnel is relatively short and small bore, the works required extensive planning and preparation, and focused execution, to overcome the geological challenges. The fourth and final paper in this afternoon track focuses on small scale tunneling – ‘Northeast Boundary Tunnel Project: First Street Connector Tunnel and Mount Olivet Road Diversion Sewer Design and Construction’, by Brierley Associates and The Lane Corporation. The Northeast Boundary Tunnel (NBT) project in Washington,
DC, involves construction of a long CSO drainage tunnel with multiple connections, including seven shafts, in an urban setting. Discussed are to be two of the connection points into the large tunnel – First Street Connector and Mount Olivet Road Diversion Sewer, respectively. The NBT project is being developed by DC Water.
● A review of the completion of the LA Metro Regional Connector Transit project, which included bored tunnels, an SEM cavern and three underground stations, plus cut and cover tunnels. Paper by VN Tunnel and Underground, and LA County Metropolitan Transportation Authority
Difficult Ground (Track sponsor: Stantec) ● On the 50th anniversary of its opening, a spotlight on
the challenges of investigation for and construction of the high-elevation Eisenhower Memorial Tunnel, in Colorado. Paper by Stantec, and Colorado Department of Transportation
● A look at the geological challenges for construction of the JWPCP Effluent Outfall Tunnel project, in Los Angeles. Paper by Pini Group, and Dragados
● Taking a focus on the part of the Purple Line Extension of LA metro, the paper looks at preparing for and executing the bored pressurized face tunneling through a confined gas zone. Paper by Traylor Bros, Golder Associates, and LA County Metropolitan Transportation Authority
● Second Narrows Water Supply Tunnel project, which involved conventional deep shaft excavation in variable weak rock, in Canada. Paper by McMillen Jacobs (now Delve Underground), Greater Vancouver Water District, WSP Golder, Traylor Aecon
Geotechnical Consideration ● A review of how the lump-sum, design build
procurement was undertaken with particular reference to development of the geotechnical baseline report (GBR). Paper by CB3A, Aecom, Stantec, and Narragansett Bay Commission
● Two presentations on the use of artificial ground freezing (AGF): for its adaptable use on smaller tunnels and varied geometries, such as cross passage and adit construction; and, ways to horizontally excavate into soil that is a frozen temporary support to an excavation. Both papers by SoilFreeze
● Discussion of the ground improvement challenge with extensive jet grouting in glacial soils to permit both EPBM boring and micro-tunneling for the Lower Olentangy Tunnel project, in Ohio. Paper
Summer 2023 | 51
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57
