Development at the $250M Columbus LOT venture, aimed toward decreasing sewage overflow into the Olentangy River, is over two-thirds whole with development on agenda. The venture features a major tunnel, shafts, and complicated engineering to deal with geology demanding situations. Set for of entirety by way of September 2026, the venture comes to more than one corporations and complex equipment to satisfy environmental consent orders and beef up water high quality for Columbus.
Photograph courtesy of Clint Wilson/Black & Veatch
The microtunneling dull gadget (MTBM) is decreased into the Gowdy shaft for Columbus, Ohio’s Decrease Olentangy venture.
Lately greater than two-thirds whole, Columbus, Ohio’s Decrease Olentangy Tunnel venture (LOT) is designed to attenuate the volume of sewage that overflows into the Olentangy River all over flooding. The $250 million enterprise features a major tunnel of roughly 17,000 toes. of 12-ft. diameter tunnel, at a mean intensity of fifty toes. This portion is mined with a tunnel dull gadget (TBM) and built of precast concrete segments.
“Turning in a venture of this measurement calls for steady, shut coordination between all events to successfully whole the paintings and navigate any problems that can rise up,” stated Jeremy Cawley, venture supervisor of town of Columbus Department of Sewage and Drainage (DOSD). “We’re very lucky to have, and a great deal recognize, the top stage of sharing, cooperation and dedication supplied by way of the entire corporations concerned.”
Photograph courtesy of Clint Wilson/Black & Veatch
Town of Columbus is beneath two Ohio Environmental Coverage Company consent orders to beef up water high quality and cut back the possibility of human touch with waterborne pollution by way of decreasing mixed sewer overflows and sanitary sewer overflows into creeks and rivers all over rainy climate occasions. Granite Development serves because the high contractor at the venture, whilst Black & Veatch is liable for development control and inspection services and products, overseeing and tracking all facets of the paintings.
As well as, Delve Underground is a sub-consultant to DLZ, which is the high design representative liable for the total design supply. Delve’s tasks integrated help with the design of the tunnel and shafts at the venture.
In line with Cawley, development goes smartly.
“Granite finished the mining of the southern portion of the principle tunnel from Gowdy Box to Vine Boulevard, which is roughly 5,000 linear ft, and is constant with the development of all related shafts. They’re mining the northern succeed in of the principle tunnel and feature finished 5,500 linear ft so far. Additionally they are running at the deep rock connector tunnel to the prevailing OARS tunnel and feature completed the mining of the 1,100 linear ft, 90-inch micro-tunnel to the 2d Street web site, in addition to the jet grouted protected havens alongside the alignment.”
The Gowdy shaft, which is the TBM release location, used to be built by way of slurry wall panels and has a figure-eight form.
“This used to be carried out in an effort to supply flexibility all over development and required twin launches of the TBM,” Cawley stated. “The contractor finished the southern phase of the tunnel first, to probably permit glide to that portion of the tunnel whilst they proceed development of the northern phase, will have to problems rise up all over that piece. This is able to permit town to nonetheless meet the date necessities in their CSO consent order whilst the opposite paintings is completed.”
Paintings started in 2021, with considerable of entirety scheduled for the tip of September 2026.
“The principle demanding situations for this venture are and feature been controlling the bottom and effectively growing the intervention protected havens by way of the jet grouting procedure,” stated Cawley. “The cushy floor geology in Columbus varies extensively, and has numerous cobbles, boulders and gravel which make it very difficult to mine. On account of this, the contractor has to watch the bottom stipulations and muck regularly in an effort to modify strategies and components to forestall floor agreement and clogging of the gadget.”
Key duties closing for crews come with of entirety of the principle tunnel; the deep rock connector tunnel; ultimate construct out of the entire shafts; in addition to the DSR 873 redirection jack and bore. Because of many of the paintings being subterranean, the elements hasn’t had a significant have an effect on.
Heavy equipment used at the venture contains the brand new Herrenknecht 14-ft. 7-in. earth force steadiness TBM, particularly designed for the geology of this venture and thought to be essentially the most necessary piece of kit. The TBM used to be built at Herrenknecht’s major facility in Shwanau, Germany, and used to be shipped to Toledo, Ohio, by way of barge. From there it used to be transported by way of Edwards Shifting and Rigging in 3 separate items to the Gowdy Box release web site. Setup and reducing of the gadget into the shaft used to be assisted by way of an 800-ton Maxim crane.
The Herrenknecht AVN 2500 90-in. micro-tunnel dull gadget is also being applied, along side two HS-3180 Liebherr cranes; two Comacchio jet grout rigs; and smaller items of kit.
Photograph courtesy of Clint Wilson/Black & Veatch
The principle tunnel fabrics required are the precast segmental tunnel liners being produced by way of CSI Concrete Programs in Macedonia, Ohio, and the 90-in. micro-tunneling pipe, which used to be produced by way of Rinker Fabrics in Columbus.
Cawley famous the outlet via at Vine Boulevard went in line with plan. Granite slowed manufacturing to extra safely excavate in the course of the secant pile shaft partitions and got here in on line and grade. Paintings at the 36-in. reduction sewer has been finished and used to be carried out with a mixture of conventional open-cut excavation and jack and bore strategies.
Development associated with the connector tunnel is ongoing. Granite has finished kind of 30 p.c of the rock excavation.
“The rock tunnel is roughly 170 ft beneath the outside, and is being built in karstic limestone,” Cawley stated. “Because of the karst options, Granite is carrying out phased grouting of the rock to regulate the water. The excavation is being finished by way of drill and blast, sequential excavation strategies.”
Whilst various paintings stays, Cawley stated he is happy with what is already been achieved, because of the gifted workforce assembled to hold out the multi-year venture.
“Attending to paintings along and be told from the pros concerned has been an absolute privilege. Additionally it is very rewarding to understand this venture will supply this kind of sure and long-lasting have an effect on to town and area as an entire.” CEG
