By Tasha Anderson for Arizona Builder’s Exchange
The Arizona chapter of the American Society of Civil Engineers held their February Luncheon on Wednesday at the because-Space for Life event center to discuss the Grand Canyon Trans-Canyon Waterline and the plan to replace it rather than fix the existing pipeline.
Guest speakers Kris Provenzano, Grand Canyon Program Manager for Water and Wastewater Infrastructure with the Unites States National Park Service, and Rich Thornton, Project Manager for HDR Engineering, updated the crowd on what’s currently going on with the pipeline project.
The current pipeline is 12.5 miles that moves the water by gravity. It begins at Roaring Springs and travels along Bright Angel Creek and the North Kaibab Trail through Phantom Ranch to Indian Gardens and pumps to the South Rim. Provenzano explained, “The pipeline is fifty years old… and it is failing.”
Thornton added, “Currently, there’s about an average of twenty-five pipeline failures per year since 1980. It costs about $25K per repair. Those outages impact residents… and there’s the logistical challenges working in the inner canyon with all the materials being flown in by a helicopter.”
Both also noted that climate change and environmental conditions affect the pipeline material and are huge factors in the pipeline failure.
Two Primary Alternatives
During the presentation both Provenzano and Thornton gave an overview of two primary alternatives for replacing the aging pipeline and discussed the advantages and disadvantages of each one.
The first alternative they noted is replacement in-kind, which is the simplest option, as it keeps the current alignment of the pipeline.
“[Replacement in-kind] allows for phasing, so I don’t have to replace all of the pipeline at once. I can go to those sections that are of the biggest concern,” said Provenzano, stating one of the biggest advantages of that alternative.
She then began to list its disadvantages, such as the environmental damage caused by construction crews and trucks, potential delays of construction due to the remote area surrounding the pipeline, and, of course, long-term durability.
“The original pipeline was built, and within five years it breaks,” said Provenzano.
The second alternative – and the preferred alternative as explained by Thornton – is source relocation and treatment, which will eliminate seven miles of pipeline between Cottonwood Canyon and Phantom Ranch, where many of the leaks were occurring. New wells will be drilled; a new pump station will be built at Phantom Ranch, and the portion of pipeline between Phantom Ranch and Indian Gardens will be replaced. Thornton also noted the project would include the construction of water treatment facilities in multiple locations.
Provenzano went on to list the advantages of this alternative, including flexibility for future water regulation requirements, less pipe, construction risk minimization and lower initial cost.
“Long term cost though, because I’m now adding water treatment plants and I’m adding infrastructure, the long term cost is actually higher,” Provenzano said, explaining the disadvantage. “The Park Service looked at that, but the value [of the advantages] was so high that it beat out replacing it in-kind.”
Though source relocation and treatment is preferred, no alternative has been chosen yet.
Project Delivery and Schedule
As it stands, the project is currently estimated at $75M-$100M with funding coming from two sources: The Park Service’s line-item construction budget and recreation fees collected at the park entrance.
“The Park Service line-item construction budget for a year is about $80M. So, we’re not getting all the money but we’re getting it over the course of three years. So, we will be getting some fairly large chunks of money starting in ’19, ’20 and ’21,” Provenzano said, explaining their funding process for the project.
The project is still going through the National Environmental Policy Act review process and the National Park Service anticipates having their draft environmental assessment out for public review by this summer. They also hope to obtain a Finding of No Significant Impact in the fall.
“Our goal is to start work at the end of calendar year ’19,” said Provenzano. “We’re looking at the rim work first, which would be the water treatment plant on the South Rim, and over the course of the next year we’ll begin working on the inner canyon work, the more difficult work. And that will be about a two to three-year construction period.”
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