Photo By Samuel Weldin | Kylie Ward, Kansas City District asset manager, peers down the length of the conduit...... read more read more
On the surface, what is a dam to most people? A large mound of dirt? Throw in some concrete? An elongated pile of branches and trees operated by a crew of beavers? Sure, that’s not technically wrong – but there is much more to it, and a multidisciplined team of engineers from the Kanas City District recently conducted a periodic inspection of the Melvern Lake and Dam project in Melvern, Kansas, to dive into the “more.”
Erected in 1972, reservoir filled and fully operational by 1975, the Melvern Dam has been an incredible asset to local and national infrastructure for nearly 50 years. This 123-foot-high and 9,750-foot-long “mound of dirt” impounds the Marais des Cygnes River, which is notorious for destructive flooding. The 7,000-acre reservoir the dam creates, Melvern Lake, has become a local and national hub for recreation enthusiasts as they flock to fish, boat, hunt and camp in the five parks that surround the lake.
Since the earthen dam’s inception, authorized by the Flood Control Act of 1954, the U.S. Army Corps of Engineers has been tasked with the operational effectiveness and security of the dam and reservoir. While each of the dams underneath the Kansas City District’s umbrella of responsibility are inspected annually, the periodic five-year inspection takes a deeper dive into all aspects of the project affecting the safety and operational capability of the dam. The national USACE Dam Safety Program seeks to ensure that USACE owned and operated dams do not present unacceptable risk to people, property or the environment, with the emphasis on people. Life safety and limiting property damage remain at the forefront of the USACE mission, and these periodic assessments are a part of ensuring mission success.
“These PIs are extremely important. It is a great opportunity to learn the project and for the newer engineers get up to speed on the project's history. We look at everything and identify what we need to prepare for in the future,” said Glen Bellew, Northwestern Division levee safety program manager. “Our ultimate goal is to maintain the safety at this project, the more information we have, the better prepared we are to make recommendations with strong justifications when submitting budget requests.”
Surface inspection aside, the imperative infrastructure that lies underneath is what allows these dams to function properly and are what the periodic inspection also covers. To put it simply, each dam and reservoir is equipped with an intake structure (water flows in), conduit tunnel (water flows through) and outlet channel (water flows out). This is what is used to control the water flows and mitigate flood risk to local communities and infrastructure downstream. A 2005 study conducted by the University of Southern Illinois concluded that the total amount of monetary damage prevented by USACE flood control measures throughout history exceeds $700 billion – however, this number more than likely exceeds $1 trillion in present day.
“Periodic Inspections allow our team to inspect the dam more closely than we do in our annual inspections. We review the dam’s design and instrumentation before the inspection to ensure the dam is functioning as intended, and plan and develop recommendations for items requiring attention in upcoming years,” said Breanna Birkett, Melvern Dam’s geotechnical engineer. “The stilling basin and conduit inspection were especially important this year. We usually only dewater the stilling basin and conduit to lay eyes on these components once every 10 years.”
Inspecting a dam’s conduit, requires much coordination and careful planning on our engineer’s and operation project manager’s part. Melvern’s conduit runs approximately 767 feet and is 11.5 feet in diameter. Generally, there is water flowing in some capacity, so our team must ensure a thorough dewatering process, which can take several days, before being able to enter and properly inspect. Upon entering, the team will traverse the entirety of it, ending at the installed stoplogs holding back the reservoir. During that time, they inspect the concrete conduit for cracking, water-tight joints and joint displacement, and inspect the stoplogs and gates for cavitation, corrosion and paint and weld condition.
Due to the presence of hazardous energy within the structure, the team follows hazardous energy control program (HECP) protocols during inspection of the conduit to make it as safe as possible and mitigate risk. Other safety measures include locking the gates and storing the keys in a lockbox to ensure gates are not operated while people are inside the conduit. The team signs in and out of the conduit as they inspect, and gate controls are unlocked when the conduit is clear and the team is ready to begin gate exercises.
“The conduit and stilling basin inspection are vital to dam safety. Since water is usually flowing through these structures, without these inspections, we may not be able to detect an issue until it has grown into a large and expensive problem,” said Birkett. “The dewatering crew spends several days power washing all surfaces in the stilling basin and conduit so the team can thoroughly inspect all areas and recommend preventative maintenance and repairs as necessary. Dewatering inspections are a unique aspect of a rewarding job in dam safety.”
Over the course of the two-day periodic inspection, all facets of the structure will be meticulously examined. Notes will be made, reports will be filed and recommendations will be submitted with the ultimate goal being the safety of the local community and continually strengthening American infrastructure.
| Date Taken: | 11.22.2024 |
| Date Posted: | 12.02.2024 11:04 |
| Story ID: | 486409 |
| Location: | US |
| Web Views: | 36 |
| Downloads: | 0 |
This work, Beneath the Surface, by Samuel Weldin, identified by DVIDS, must comply with the restrictions shown on https://www.dvidshub.net/about/copyright.
No keywords found.
