Dams

Industry-Leading Capabilities.

Gracon’s dam maintenance division provides expert dam construction contractors who specialize in rehabilitation and replacement services for dam mechanical equipment of all sizes. As one of the early foundations of the company, dam repair and construction is deeply entrenched in Gracon’s history and future. 

An emphasis in this division is gate construction work, including radial, slide, crest, miter, and drum gates. In the past ten years  Gracon has replaced or repaired more than 100 gates This project exposure ensures that our dam repair contractor’s team is one of the most knowledgeable and experienced in the United States. The inner workings of a dam are complex, but our expert crews draw on years of similar project experience to solve even the most complicated and technical problems. 

Dam Construction Services

Dam Rehabilitation and Construction

Several types of man made dams exist today and are classified according to the type of construction material being used, the slope or cross-section of the dam, the way the dam resists the forces of the water pressure behind it, the means used for controlling seepage, and what the dam’s purpose may be. Examples of Gracon’s project history on dams and gates are shown above.

Roughly 650,000 dams around the world require regular maintenance, repair, and rehabilitation, making existing dams one of the largest markets for construction. The average age of our nation’s dams is 58 years old, and as the population grows, and development continues, high-hazard potential dams are increasing. As owners reduce hazards on their dams through rehabilitation or new construction, they can rely on Gracon’s track record of safe performance. No matter how large or small, dams are powerful structures that require strict safety guidelines during construction. Our Zero Harm Core Value emphasizes worker and public safety as our top priority.

Common Challenges and Solutions

As a premier dam construction company, it’s important that we assess our services to continue to make vast improvements for our clients. As our dams age and require rehabilitation, we run into several common challenges that our dam specialists can solve for you. Some of those common challenges include:

Challenge: Spillways

Solutions: Spillways often become obstructed, have structural damage, or are placed on a weakened foundation that needs to be refurbished. Older dams were designed with less capacity than modern design requirements so generally these spillways would need to be replaced. On a recent project the spillway was in the middle of the dam.  Gracon suggested the spillway be relocated to an abutment to prevent a collapse in a maximum possible flood condition. This would not only alleviate a catastrophe but also enhance the life of the dam.

Challenge: Access to Project Sites

Solution: When doing gate repairs, access can come at a premium. On our Paonia Dam project, the gate chamber was in the center of the dam, 400 feet from the outlet tunnel. The spillway came out over the top of the tunnel which shrank the portal of the tunnel to only a four foot tall opening. To overcome this challenge, Gracon removed a portion of the spillway slab using hydro demolition. This solution made it feasible to move men and equipment up the tunnel and perform the planned work. The only other option was for us to access the gate chamber, via an elevator shaft. We would have had to eliminate the elevator and lower all materials down the shaft; however, we chose not to do this because it would have eliminated a means of egress for our personnel in case of an emergency.

Challenge: Worn Gate Seals

Solutions: When worn gate seals are encountered, the only solution is to replace them. On several of our projects, Gracon has replaced the seal components on both the leaf and frame of the gate with like materials. This solution renews the life of the gate for another 50 years. On our Dillon Dam project, the cast gate leafs had worn so badly that Gracon had to remove a portion of the gate body and replace it with new material to return it to original dimensions.

Challenge: Gate Hub Bushings

Solution: While working on the John Redmond Dam Trunnion Replacement project, the gate hub bushings had frozen into the shafts and weren’t allowing it to open or close. Gracon developed an innovative system to move the very large radial gate to access the gate hubs. Using a steel beam and rigging system above the gate, and additional beams with high capacity hydraulic jacks under the gate, Gracon was able to move the gate off the hubs. Once the gate was moved, we were able to remove the trunnion pin and bushings, machine both hubs, install new thrust washers and hub rings, remove old brass bushings, install new composite greaseless bushings, and install new stainless-steel pins and retainer plates. After completion the gate operated smoothly without binding.

Challenge: Gate Hoists

Solution: Problems with gate hoists include wear and leakage around the piston rings. In the early 2000’s, Gracon suggested replacing the upper ring with a Parker Poly Pak which improved the seal. This method has now been adopted by the Bureau of Reclamation for nearly every hydraulic gate hoist rehabilitation including many performed by Gracon.

“Gracon performed the work on 3 large drum gates. The access was very difficult, but they developed a very efficient, effective and safe work plan. The quality of work was above average, and they were always interested to satisfy the owner.”

-Richard Welsh, USBR

Contact our leading experts and dam construction company today to learn more about our dedication to our work, skillsets, and solutions offered.