Cowi, in a joint company with GFT (formerly Gannett Fleming), has obtained a contract of $ 25.4 million to deliver construction and construction inspection for the Irvine Ranch Water (IRWD) district of California Siphon Improvement Project: The largest capital program in the district history, according to the Board records.
The expansion of $ 291 million will replace the existing prey of 59 feet with a new 136 -foot embankment dam and will increase the storage of recycled water by ten, from 578 acres to 5,000 acres. District officials say that the update, scheduled for completion by 2028, will strengthen the resilience of drought, reduce confidence in imported supplies and save customers for $ 85 million for 50 years.
“This is a significant milestone for Cowi in the south of California,” said Arun Parsons, Cowi North America vice president, to announce the contract on September 30. “We have impressed the bold implementation of Irwd … and exactly reflects the type of future approach and leader in the industry than Cowi champions.”
Scope of expansion and supervision
Irwd’s environmental files, reviewed by Enr, ask to demolish the current dam and build a 136 -foot embankment, increasing the 388 -foot ridge at 466 feet above sea level.
Planned improvements include a new slope, filtration drainage system, updated circulation works, and filtration and disinfection facilities at the footing. New access and maintenance roads will be built, along with wetlands and riparian mitigation.
A schematic map shows the project to improve the Sifon reservoir planned in Irvine, California, including the footprint of the new 136 -foot dam, proposed treatment facilities, spill, intake and starting work and flood area. Image courtesy of Irwd/Eir.
In order to strengthen public confidence, Irwd convened an independent design and security review box by 2021, consisting of nationally renowned prey engineers. The panel conducted design reviews and visits to the site, issuing a closing letter in February 2025 confirmed that the concerns had been resolved and met the requirements of the California Safety Division.
The construction is expected to last two to three years. Irwd has not yet granted a main contractor, although permission and design are complete. To reduce community impacts, the district plans to restrict truck access during peak hours, limit most activities on weekdays and enforce dust and noise controls.
Long -term financing and value
Funded by an existing evaluation of capital facilities already collected on property tax bills, the $ 291 million program will not increase drinking water rates, according to Irwd.
Federal support includes a prize of $ 12.25 million within the framework of the Watersmart program of the Bipartisan Infrastructure Act. In the financing announcement, the then Secretary of the Interior, Deb Haaland, said that the expansion of the Siphon reservoir “emphasizes the federal commitment to strengthen the resilience of the drought in California.”
The IRWD projects long -term customers saving the water purchases imported from the north of California and the Colorado river. )[T]The Siphon deposit improving project is expected to save customers for approximately $ 85 million for 50 years, “said the district.
As the expanding deposit will allow almost 100% of the recycled water produced to be stored and reused, the increase in supply could be deployed during the summer months for irrigation, industrial cooling, dust control and removal of fires, eholorating the reliability of water over the next few decades, the district said.
The Irwd recycled water network covers 570 miles of “Purple Pipe” – the standard color of the industry used to distinguish non -polable water lines – and serves more than 6,200 accounts or 28% of total deliveries.
Cowi has worked on other deposit projects and prisoners in California, such as Anderson Dam, Lafayette and Briones Reservoirs, Chabot Dam and Folsom Dam.
