[EDITOR’S NOTE: In each issue, Utility Contractor will profile NUCA’s Top Job winners. These projects present the association’s best and most innovative work that keep our country’s utility networks operating at peak performance. To nominate your project for Top Jobs, visit: nuca.com/topjobs]
The Northern Colorado Water Conservancy District (Northern Water), and its Municipal Subdistrict provide water to Northeastern Colorado from the Colorado-Big Thompson (C-BT) and Windy Gap projects. The C-BT Project collects water west of the Continental Divide and delivers it to Northeastern Colorado for agricultural, municipal, domestic and industrial uses. Northern Water and the U.S. Bureau of Reclamation jointly operate and maintain the C-BT Project.
The C-BT project, completed in 1957, collects and delivers on average more than 200,000 acre-feet of water each year. Most of this water is the result of melting snow in the upper Colorado River basin west of the Continental Divide. The project transports the water to the East Slope via a 13.1-mile tunnel beneath Rocky Mountain National Park. From there water is conveyed through canals and pipelines.
One component of the system is the Maitland Siphon, which Northern Water identified in its 2015 strategic initiatives plan as in need of repair. The Maitland Siphon is critical in the distribution of water to the communities located in Northeastern Colorado, including Horsetooth Reservior. By successful completion of the rehabilitation of this siphon, Northern Water is able to ensure uninterrupted water supply to these communities.
Northern Water contracted Lakewood, Colorado-based Underground Infrastructure Technologies (UIT), a Harrison Western company, to rehabilitate the siphon by constructing a steel slipliner inside the existing Maitland Siphon. The existing Maitland Siphon is a reinforced concrete siphon structure located on the Hansen Feeder Canal, located west of Loveland, Colorado, that conveys water under an intermittently flowing natural drainage.
The existing reinforced concrete siphon pipe had a diameter of 12.5 ft. The steel slipline was installed in approximately 245 lf of the existing reinforced concrete siphon pipe. The project had a very tight schedule as the water supply through the canal was completely shut down in order to accommodate the performance of this project. There was no deviating from the planned project schedule, which began in August 2017 and ended in November 2017.
Due to the critical nature of the project, UIT determined that it was prudent to re-survey the existing tunnel siphon as the original survey was performed during the project investigation phase. UIT selected a 3D survey technique that was able to provide more precise results. During this re-survey it was determined that the siphon elbow fittings would not pass through the bend within the siphon as designed in the original project plans. Based on the results of the re-survey, the original engineering for the fittings was redesigned. By identifying this issue, UIT was able to modify the design of the fittings in the manufacturing plant instead of in the field upon discovery, thus avoiding significant costs and project delays.
Mid America manufactured the large-scale pipe (144-in. diameter) and prior to shipping they assembled the critical 7 elbow pieces of the siphon in the factory and then applied a ring in the same diameter as the siphon to ensure that the fittings and bend would pass through the siphon pipe without any difficulty. By being proactive with such a critical portion of the pipe, Mid America ensured that there would be no unexpected issues in the field.
Just getting the materials to the site was a challenge due to the remote location. Once they were able to get materials onsite, UIT crews used a winch system to lower pipe segments into the siphon, anchoring the new steel pieces to the existing concrete siphon to prevent them from moving. Crews then welded the new steel pipeline from the inside, working from the bottom to the top from both sides. Once the steel liner was in place, it was grouted in three pours to prevent it from buckling.
“The project went well from a logistics standpoint,” said Mike Montano, estimator and project manager for UIT. “Northern Water and its designer had a very good design going in, and they were willing to work as partners and were open to suggestions as the project progressed.
“The success of any project is only as good as the construction team who worked the project. We tip our hats to the Harrison Western/UIT employees who helped ensure a safe and successful completion to this award-winning project.”
In addition to Montano, UIT/Harrison Western team members included: Jim Johnson, General Superintendent; Raul Cardenas, Superintendent; Jimmy Mobley, Foreman; Emilio Duarte, Crew member; Ezer Lopez, Crew member; Folfito Lopez, Crew member; Elise (Junior) Muaau, Crew member; and Coval Gelatt, Crew member.
Following installation of the new steel pipe, Coblaco Services performed a field coating application that needed to be climate controlled, working on steep slopes and overhead 14 ft high. Flashfill Services placed the cellular concrete, which was no small feat considering the remote site, with no damage to the new steel pipe.
Contractor: Underground Infrastructure Technologies LLC (UIT)
Project Owner: Northern Colorado Water Conservancy District, Loveland, Colorado
Contractors/Subcontractors: Mid America Pipe (pipe fabrication); Coblaco Services (steel pipe coating); Ferguson Waterworks; Sunbelt Rentals; Northern Colorado Traffic Control; Martin Marietta; Absolute Welding (certified welding services); Ludvik Electric; Flashfill Services (grouting); O’Brien Concrete Pumping (grouting); Wylaco Supply; Albert Frei & Sons; Aklam Inc.
(3D laser scan); Top Gun (siphon cleaning).
Owner’s Designer: Dewberry Engineers