May 17th, 2023 marked the deadline for the City of Escondido’s commitment to the San Pasqual Band of Mission Indians for the completion of the San Pasqual Undergrounding project in Escondido, CA. Over the last 16 months, Sukut crews have removed, relocated, and replaced approximately two and a half miles of the Escondido Canal that crosses through the San Pasqual Indian Reservation. The three major components to accomplish this included: desilting basin construction, demolition and replacement of existing canal with concrete box, and 60-inch pipeline installation. The 110-foot-long by 32-foot-wide desilting basin is a hydraulic structure within the 100-foot city right-of-way that required the construction of large retaining walls and an all-weather access road to facilitate desilting basin use. The demolition and replacement section of the first half-mile of the open canal was replaced with a shallowly buried 60-inch-wide by 48-inch-high precast concrete box culvert. Finally, the construction of a new 60-inch diameter pipeline in a new 1.5-mile-long alignment across portions of the San Pasqual Indian Reservation included a 350-foot-long tunnel to minimize environmental impacts to a riparian area.
This water conveyance project provided a path to a more sustainable water resource for the City of Escondido and Vista. Additionally, through the process of undergrounding the open channel canal limits water lost to evaporation. Lastly, after the construction of the project completed land that was once occupied by open channel canal was given back to the rightful landowners. This land created the opportunity for more tribal members to rejoin the community.
This project had many challenges throughout; however, one of the most notable was rock excavation. Across the 2.5-mile alignment, Sukut encountered rock in two of the most critical locations. The first location was the tunneling operation. Sukut was able to make alignment adjustments to avoid large blue granite boulders, as well as changed construction means and methods to avoid culturally sensitive areas. As this project was on the San Pasqual Indian reservation, exposure to areas with cultural significance was high. The second area we encountered rock was at the cut-and-cover access road. After a week of attempting all methods of conventional excavation, it was deemed that blasting was needed to perform the work. Sukut contracted with a local blasting subcontractor and successfully blasted and excavated the cut and cover access road. Overcoming these rock excavation challenges was instrumental in Sukut delivering an on-time and on-budget project.
In addition to rock excavation, historic rains over the past year made work extremely difficult and jeopardized the project’s completion. From the onset of the project, the City of Escondido made it clear that the completion date was the most crucial goal next to maintaining a safe worksite. This importance of the project completion date was due to a lawsuit filed with the federal government back in 1969. The lawsuit brought by five local Indian tribes along the San Luis Rey River contended that the City of Escondido and Vista had stolen the tribes’ water by the construction of the canal. After nearly 50 years of litigation, a complicated settlement was finally reached a few years ago. One condition of the settlement is that the portion of the canal that runs through the reservation or on nearby land owned by the San Pasqual tribe be put underground by the year 2023.
The tunneling operation completed by Goldenstate Boring Company in conjunction with Sukut is one item of note that embodied quality and craftsmanship. The tunnel boring pits were 35 feet deep, 14 feet wide, and 40 feet long. This temporary installation was completed in two weeks in preparation for the Goldenstate Boring. The team of Goldenstate Boring mobilized and completed the 245-foot-long by 9-foot diameter tunnel in 10 weeks. With adjustments to the alignment and a myriad of engineering hurdles to overcome the team was able to successfully exit the excavation per the schedule.
During the project, Sukut had also turned to the implementation of several innovative techniques. The implementation of a soil nail wall in lieu of a cast-in-place retaining wall allowed for a safer and more economical installation. With this proposed design change, Sukut was able to limit mass excavation and off-site trucking. This limited impact on the public as well as creating the opportunity to start work in areas that would have otherwise been inaccessible.
Another great example of innovation was the use of shotcrete in place of cast-in-place concrete for the desilting basin. This placement method opened the opportunity for single-sided forms, effectively expediting the time spent forming and limiting the time backfilling that would have been needed if the wall had remained cast in place.
The project was a winner in all respects, from bidding through execution, and is an excellent example of Sukut’s capabilities as a heavy civil contractor. Sukut’s safety approach and careful planning also resulted in no safety incidents and zero time lost.
Sukut Construction is one of America’s leading heavy civil contractors with over 55 years of proven industry expertise on residential, public, commercial, and industrial projects. Sukut has received over 50 industry awards and recognitions for its unparalleled civil engineering expertise in work areas that include alternative energy, emergency response, flood control, water control, excavation, land remediation, landfill maintenance, recreation development, resorts development, shoring techniques, transportation, underground utilities, large water systems, and water infrastructure. In addition to its vast array of services, Sukut excels at developing and implementing innovative, technologically-sound solutions to confront the most challenging land development, natural resource, and environmentally friendly energy issues throughout the United States. From employing a fully GPS-guided company-owned fleet of over 275 pieces of heavy equipment to developing proprietary technology for heavy civil engineering and logistics, Sukut’s 55-year track record has elevated its work process to revolutionary and creative practice. This approach makes Sukut time and cost-efficient on every project.