Inflatable dam upgrades city's water system

November 2009 » Web Exclusive
Kristen Braden, Esq.

As a city grows in population, upgrades to public services become necessary — new schools, more police and fire protection, additional community programs — but the most vital upgrade is to water services. To meet the needs of its expanding population and as a response to existing and future development, the city of Marysville , Ohio , embarked on a project to upgrade its water storage and delivery system.

Project
Upground Reservoir Project, Marysville , Ohio

Participants
H.R. Gray
City of Marysville , Ohio

Product application
H.R. Gray manages project changes, including switch to an Obermeyer Hydro inflatable dam.

With a total budget of $24 million, the Marysville Upground Reservoir Project consisted of four contracts providing a complete system to capture water from Mill Creek, pump it to the new reservoir, and ultimately deliver the water to the Marysville Water Plant. Although the existing system included a well and a diversion from Mill Creek, there was no real storage capacity for water, so the new reservoir was especially important for the city.

One of the four contracts encompassed construction of a dam, intake structure, and a pump station building, in addition to installation of an inflatable dam purchased under a separate contract between the city and a dam manufacturer. Depending on the flow rates and water levels in Mill Creek, the pump station is able to provide 26 million gallons of water daily to the reservoir.

To meet the city's desired completion date, an additional contract was issued for the design and procurement of an inflatable dam and associated controls. The inflatable dam system monitors water flow and levels in Mill Creek, as well as adjusts the amount of water diverted to the new reservoir to maintain environmentally friendly flow conditions. In addition to monitoring stream flows and water levels at the dam, the pump station's control center also monitors reservoir water levels via remote solar-powered transmitters, maintains historical data, and sends reports back to the main water plant.

Professional services needed
The city was involved in many projects at one time — including building a new wastewater treatment plant. Consequently, Marysville officials realized they needed professional assistance to ensure that all projects were executed properly. Because of the complexity of the projects and the time restraints, the city decided to hire a professional construction manager to oversee the project.

In 2007, H.R. Gray was hired as the construction manager for the project by the city of Marysville 's Department of Public Services. H.R. Gray provides construction management services for complex projects, including scheduling, cost estimating, and construction inspection, as well as analysis and resolution of construction disputes.

“We faced several challenges on this project,” noted Lucius A. Marks, P.E., vice president of H.R. Gray. “The original manufacturer specified for the inflatable dam could not meet the delivery schedule, some of the design specifications and materials were outdated, construction changes had to be coordinated with the general trades' contractor, and the adjacent residential area could not be disturbed during construction.”

Finding an alternate dam
Because of product delivery delays with the inflatable dam's manufacturer, H.R. Gray assisted the city with finding an alternate product that met its timeline. H.R. Gray researched other manufacturers and found a solution that was not only more efficient, but also less expensive than the original system and could be delivered to complete the project on time.

H.R. Gray recommended an inflatable dam system from Obermeyer Hydro., Inc., a manufacturer of spillway gates and dams for water control. The Obermeyer system features a rubber bladder covered by steel gates, protecting the inflatable air bladder from the elements and from floating debris and ice. The original design called for a dam that, at any particular time, would be either all inflated or all deflated. This would limit the city's control over the diversion of the water and could prevent the city from meeting environmental requirements. Instead, the selected system consists of four independently operating bladders and gates allowing more precise control of the amount of water diverted.

By controlling the pressure in the bladders, the pool elevation behind the dam can be infinitely adjusted within the system control range (full inflation to full deflation) and precisely controlled by the city. With this system, the city can easily meet regulatory requirements for water flow and other environmental concerns. In addition, the Obermeyer Hydro system allows the city to compile reports and track historical data. The system is also more aesthetically pleasing since, when the dam is completely deflated, the rubber bladders are covered by steel gates, which are curved and flush with the creek bed. Additionally, while the dam is inflated, a minimum flow over the dam will be maintained and residents downstream from the dam will still see water flow in the creek.

Fixing the spec changes
“Because the size and configuration of the new dam was physically different from what was originally specified, it was necessary to coordinate changes with the general trades' contractor for the pump station to revise the building layout and make modifications within the control systems,” Marks said.

Many portions of the original inflatable dam system's specifications could not be used, as the new system had different components that would not fit the original design. Not only was the control system in the building different, but the concrete structure that the inflatable bladders and steel gates attach to ended up being different than originally specified. H.R. Gray had to coordinate changes and make certain that all the components to the project were still included within the scope and would fit within the structures built.

Working with the contractor and city officials, H.R. Gray ensured that all the design changes were completed in advance of the inflatable dam's installation, thereby avoiding any costly rework.

Keeping the public happy
Because of the project's proximity to a park and a residential subdivision, it was crucial that the surrounding area not be disrupted during construction. Through a tremendous amount of coordination, H.R. Gray was able to keep the public happy and allow continuation of normal activities.

“We set-up a project website and e-mail address to keep the neighbors informed of construction activities and progress,” Marks said. “Before construction started, we held a public meeting to address any concerns. And to keep the residents informed, we regularly handed out flyers.”

H.R. Gray stipulated that construction work take place during appropriate hours and made sure that the contractor did not damage any personal property. To alleviate dust conditions, the surrounding area was continually watered, and roads were cleaned often to remove mud tracked in by construction vehicles. Because the reservoir was also close to a school, H.R. Gray closely monitored large deliveries to avoid traffic congestion and maintain pedestrian safety.

The new dam and reservoir
The new dam allows Marysville city operators to have greater control over the water level and flows on both sides of the dam. Since multiple air bladders inflate independently, operators can vary the amount of air in the dam on a day-to-day basis, making the dam a more efficient and effective tool. For the residents, the creek that runs through the park behind their homes still exists and has been made even more appealing. Additionally, Marysville decided to make the top of the embankment around the reservoir a walking path.

H.R. Gray's construction management services proved to be a wise choice for the city of Marysville . All of the design challenges were solved, the new inflatable dam system was a much better solution than the original product, and the area's residents were not disturbed during construction. Even with the addition of a fire suppression system in the pump station and inclement weather, the project was completed on schedule in April 2009.

According to Rick Varner, wastewater superintendant for the city of Marysville , H.R. Gray was proactive in identifying and resolving issues throughout construction. “H.R. Gray was given a difficult task in overseeing the construction project in which the design engineer was no longer involved,” said Varner. “They were resourceful during the preconstruction and construction period to minimize change orders and to ensure the project was completed successfully to the city's requirements. The H.R. Gray team of Lu Marks, Kristen Braden, and Mike Mohr did an outstanding job in handling this project. They made the city of Marysville's priorities their own by adhering to the budget, addressing residents' concerns, and ensuring compliance with all the regulatory requirements.”

The Obermeyer Hydro inflatable dam comprises four independently operating bladders and gates, allowing more precise control of the amount of water diverted.
The inflatable dam has individual bladders that are used to raise and lower structure. By controlling the pressure in the bladders, the pool elevation behind the dam can be infinitely adjusted within the system control range — full inflation to full deflation.
When the dam's bladders are completely deflated, they are covered by steel gates, which are curved and flush with the creek bed.

Kristen Braden, Esq. , is construction project manager for H.R. Gray. She can be contacted at kbraden@hrgray.com . H.R. Gray is a management and consulting firm serving the public sector, offering construction management services for complex projects and resolution of construction disputes. H.R. Gray has offices in Columbus and Akron, Ohio; Lexington, Ky.; and Austin, Texas . Visit www.hrgray.com for more information.


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