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Monday, 29 October 2007 02:47

Rental Power: The Pulse of Flood-Ravaged Communities

Written by  Don Butler
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Temporary power supplied by rental generators provided the pulse that kept many devastated communities alive throughout The Great Flood of ’93.

One flood-ravaged city that is sincerely thankful for the immediate availability of rental power is Des Moines, Iowa. When the flood struck Des Moines in mid-July, Ziegler Power Systems, Iowa, and Cat Rental Power worked together with the U.S. Army Corps of Engineers and National Guard virtually nonstop for days to ship rental gen. sets to hospitals, communications systems, utilities, government agencies and private businesses. During the first week of the flood, Ziegler provided a total of 32 megawatts (MW) to the Des Moines area. Cat Rental Power, headquartered in Mossville, IL, represents more than 80 dealers in North America and more than 100 dealers in other areas of the world who rent industrial-size gen. sets and related auxiliary equipment. During widespread emergencies like The Great Flood, dealers share equipment. Ziegler is the Cat dealer located in Des Moines.

A primary reason why people in Des Moines are thankful for rental power is because it played a critical role in getting the Des Moines Water Works up and running after the plant was deluged by flood waters. All told, the flooding caused 250,000 Des Moines residents to endure life without running water for 12 days and potable water for 21 days.

As of mid-August, at least 50 deaths have been linked to The Great Flood of ’93, which disrupted the lives of people in nine Midwestern states. Approximately 70,000 people evacuated their homes, and preliminary estimates are that the floods caused more than $12 billion in damage to homes, businesses and farms. In Des Moines, one death was attributed to the flood, and damages were estimated at $600 million.

At $12 billion, The Great Flood ranks as one of the nation’s costliest natural disasters, second only to last year’s Hurricane Andrew, which caused $16 billion in insured damages, according to the Insurance Information Institute.
In addition to Iowa, Cat Rental Power provided more than 13 MW of rental power to meet the immediate needs of hard-hit communities in the Upper Midwest. Other states most affected by The Great Flood are Illinois, Kansas, Missouri, Nebraska, North Dakota, Minnesota, South Dakota and Wisconsin.

Des Moines Water
Works Deluged

On Saturday July 10, utility-supplied power in Des Moines faltered when the rain-swollen Raccoon and Des Moines rivers swept out of their banks and flooded utility substations. At one point, approximately one-third of downtown Des Moines was without power.

Serious problems began at the Des Moines Water Works at 2 a.m. on Sunday, July 11, when two substations feeding the water treatment plant flooded. Despite Water Works employees’ efforts to keep the plant dry, the Raccoon River poured into the offices and grounds of the 4½-acre complex. At 3:02 a.m., motors used to drive three pumps feeding the city’s water system were shut off as flood waters submerged the basement and five feet of the first floor of the facility. The total capacity of the Des Moines Water Works is 100 million gallons per day.

At 9 a.m., 30 Water Works officials gathered to map out a strategy for restoring water to the city. When the meeting ended, a total of 20 teams were organized and an operations base was established. The goal: to restore the water system by July 18, seven days after the pump motors were shut off.

Taking Steps

One of the first steps in the reclamation process was to secure rental gen. sets to power water pumps. Without gen. sets, the only choice was to wait for the waters to recede, and utility power to be restored. That was not an alternative.

While the National Guard fortified a 12-foot levee built by Water Works employees, six rental gen. sets supplied by Ziegler were airlifted to the plant by helicopter. The gen. sets, ordered by the Army Corps of Engineers, were placed on top of the levee which surrounded the entire plant. Helicopters transported heavy equipment in and out of the plant because roads immediately outside the facility were eight feet under water.

After the gen. sets were hooked up, water pumps pumped flood water outside the levee. By Tuesday, July 13, the water had dropped enough for engineers to get a better look at the equipment needing repair or replacement.

Meanwhile, rental gen. sets were continually shipped to the plant. By Wednesday, 13 rental gen. sets -- totaling 800 kilowatts (kW) -- were on site powering water pumps and air driers and other equipment used in the restoration process. The facility’s portable emergency backup generator set, which suffered water damage and was since repaired, also powered equipment.

As the plant dried out, workers set out to tackle the principle task of restoring motors that drive three pumps used to feed the city’s water system.

Power dilemma

While engineers assessed damage, Midwest Power, the local electric utility, worked night and day to restore power to the water treatment plant. As early as Tuesday, utility power to the plant was available.

However, the reliability of the power was questionable because it was fed into the plant by a makeshift transmission line configuration. The main problem with the incoming transmission line was that it lacked a backup system.

The reliability issue created a dilemma for Water Works engineers. They knew a serious setback would result if the utility power used to drive the city water system pumps was lost during the restoration process.

Eventually, engineers ordered two Cat® utility-grade power modules from Ziegler at 11 p.m. on Friday, July 16. Rated at 1600-kW prime power with 4,160 volt (V) capability each, the rental units were a perfect match for the water plant pump motors. As such, it eliminated the need to order and hook up transformers to boost voltage.

By the time the units were ordered, Water Works engineers learned that the power modules had already been shipped from the Caterpillar Large Engine Center in Lafayette, IN. As a result, the equipment arrived on site at 9:00 a.m. Saturday, approximately one day ahead of schedule.

The power modules were transported into the plant complex via a makeshift road built over the levee by the Army Corps of Engineers. The second unit arrived later that same day.

Within hours, the two power modules were paralleled with each other and tested. As a result, the units provided a total 3,200-kW prime power -- enough to feed the water system indefinitely, if necessary. The temporary configuration also provided sufficient backup power to the utility.

The immediate concern, however, was whether the water pumps supplying water to the city were operational. To find out, engineers tapped into the power modules for power because it was a fail-safe method for testing the pumps.

During the water system recharge operations, the 950-hp pump was to be used. Once the system is charged, the 950-hp unit then operates in tandem with a 1,750-hp pump. A second 1,750-hp pump serves as backup.
Unfortunately, the temporary power confirmed engineers’ fears that the 950-hp unit and one of the 1,750-hp pumps were nonfunctional, despite repair work that had been performed.

Unprecedented Tactic

Engineers now pinned their hopes on the third pump, which was under repair. However, the water works had never charged the system with a 1,750-hp pump because it was considered to be too powerful. Still, the city was desperate for water and engineers decided the larger pump would work if the right procedures were followed.
By Sunday, work on the pump was completed. To alleviate pressure on the system during start-up, the pump discharge valve was throttled. This decreased the flow from the large pump and prevented pressure surges in the distribution system.

When preparations were completed, electricity from the power modules activated the 1,750-hp pump at 7:30 p.m. Sunday. During the startup, members of the Water Works stood at the highest point of the city waiting for water to flow from a fire hydrant.

If it did, it would mean the unprecedented tactic to restore water to the city worked. If not, there was a major problem. Fortunately, it did. As a result, the Des Moines Water Works technically met its goal of restoring water to the system by Sunday, July 18.

Meanwhile, utility power was fully restored to the Des Moines Water Works. And, after solving a series of water system problems, Des Moines residents were informed on July 22 that running water was available. Potable water was fully restored on July 31.

Lessons learned

Almost immediately after the Water Works was flooded, discussions began about how to make sure the city of Des Moines never experiences another water crisis as a result of flooding. Ideas ranged from installing bigger and better levees to building a second water treatment plant on ground that is much higher than the original plant location.

It will be awhile before final decisions are made. However, decision makers in both public and private sectors of the Des Moines areas have come to realize that they can rely on Ziegler and the Cat Rental Power network for their temporary power needs -- no matter how critical or extensive the emergency power outage.

Don Butler is a Sales and Rental Manager for Ziegler Power Systems in Des Moines, Iowa.

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