Federal agencies tackle 2 Folsom Dam projects at once

The U.S. Army Corps of Engineers (USACE) and U.S. Bureau of Reclamation (USBR) have partnered to make necessary enhancements to the perimeter of Folsom Dam and replace rods essential to the main functions of the spillway. The agencies partnered for this joint-federal project (JFP) to raise dam dikes and are joining forces again for another project, this time to fix the spillway. Regarding the replacement of the Folsom Hydraulic Cylinder rods, USBR Project Integration Chief Mark Curney told the Folsom Telegraph, "(USACE and the city of Sacramento) need to get up to 200 years of flood protection or better. … If we have the mother of all storms and we had to basically protect the facility and not over-top the dam, we wanted to be able to basically make a certain release in order to pass that storm event. To where, after the storm event had subsided, we'd be back to life as quick as possible and the dam would be in place." These high-tech rods are what open the spillway gates, relieving pressure on the dam during stormy, rainy seasons. Each rod is eight inches in diameter and 40 feet long. There are six gates total, meaning there are 12 gate rods that need to be replaced. The spare cylinder will also be removed and replaced. Each spillway gate (through which the water flows out of Folsom Lake) needs two rods to function properly. As the gate lifts to let water flow through, the rods extend out, allowing them to control how much water is released. "(We) noticed some of the cutting-edge technology that was supposed to provide a certain amount of years of protection, 25 years plus; as far as the coating on the rods, (they were) showing a few signs of premature aging, so we wanted to make sure that was addressed," Curney said. "… We actually got together, Reclamation, the Corps, Safety, all the departments, DWR, and we came up with various ways to address it. So when we actually came up with the best engineering solution … that's when they came out to where they say, 'All right, let's do a replacement of all rods.' " After the best solution was posed and agreed upon, the work was put up for contract and eventually awarded to Granite Construction Company on Jan. 18 for $16,663,990. Curney said by the two federal agencies working together on the spillway project, their efforts are estimated to have saved $1 billion. He claimed they do not expect the cost to go over $16 million but did say any additional costs that may appear are the price to pay for such a project. To help the public envision what needs replacing, Curney presented an analogy of the coating relative to a paint job on a car. After its painting, the car is covered with a clear coat to protect it from the weather, repetitive washing or other moments when something comes in contact with it. Without the clear coat, the car underneath is at a higher damage risk. The same can be said of the coating on the hydraulic rods. The original coating was made of, according to Curney, the "latest and greatest technology" - High-Velocity Oxygen Fuel (HVOF). For the new rods, the engineers decided to switch to a tried and true chrome-like coating. USACE's synopsis of the spillway project said, "The replacement hydraulic cylinder assemblies must be compatible with the existing gate connection points, cylinder trunnion supports, hydraulic cylinder connections for power, controls, hydraulic fluid piping, and rod position system power and signal wiring as well as the PLC input card. The new hydraulic cylinder rod coating will be laser cladding/weld overlay over groove-based hall-effect contactless linear measurement sensor and transducer for position measuring system." Curney emphasized there's nothing wrong with the technology itself, as even the military relies on HVOF in some of tech products. The cracks occurred because, "For some reason, it didn't quite work as good as we had hoped." He said reports indicated the coating had not been evenly distributed across the rods during the manufacturing process. The cracks are so miniscule they cannot be detected with the naked eye, but Curney said they can't cover the rods with another coating, as it wouldn't quite fix the issues underneath. Replacing them would take away the possibility of uncertainty. Asked how long it would take for the dam to experience serious damage from unattended cracks, Curney stated they estimate the range to be anywhere between five and 15 years, possibly longer. There are three major phases of the rod replacement, the first being manufacturing the rods, second being delivering the rods and the third being their physical replacement. The project has already begun, as the new rods are being manufactured. Currently, they can only have two gates open at the same time, as they maintain their standards to continue supplying Sacramento County with flood protection "at all times." "Imagine from 2017 and now being 2023, we made sure that we actually took a look at all the various ways to perform this type of effort," Curney said. "We made sure that it didn't affect any kind of operations; we made sure it didn't affect the ability to release (in case of) a flood event and provide the city with protection; and we also made sure we took our time to evaluate all the what-ifs and what-coulds." It's tricky for the agencies working on the project to pinpoint an exact timeline, as the 3 1/2-foot dam raise is being constructed at the same time as the spillway. Curney pointed out that another crucial piece of the timeframe is the contractor having to prove their work is safe before all the rods are replaced. He called this the "proof of concept" phase. Taking all things into consideration, Curney said it can take "anywhere from two years to four years," depending on how the rods are manufactured, how the "proof of concept" gate performs and how stormy the upcoming rainy seasons are. The cracks have been on the radar of USACE and USBR for some time, as Curney noted they were noticed during the close-out phase of the spillway's initial construction, completed in 2017. Drew Lessard, area manager of the Bureau of Reclamation's Central California Area Office, shared more on the dam raise and why it's necessary with the Folsom Telegraph. "(The Corps) wanted to provide a little bit more storage to hold water that's coming down during any significant event," Lessard said. "And so they looked into it and planned a raise, and it turned out to be about a (3 1/2-foot) raise that was the right size, which includes modifications to the main gates on the dam, as well as raising everything 3 1/2 feet." USACE's website said the first dike had already been raised in 2020, and this dam raise project involves raising seven more dikes and Mormon Island Auxiliary Dam, and will "(reconfigure) the Folsom Dam penstock gates with modernized temperature control shutters." The modifications are expected to provide Sacramento with more than 200 years of protection. Construction for the dam raise project is expected to begin this fall and be completed within five to six years. USACE awarded the $114.4 million contract for this project to Folsom Dam Constructors (FDC), which is comprised of California Engineering Contractors, Inc. and Shimmick Construction Company, Inc.