Charles C. Roberts, Jr.

Most municipalities have a water and sewage department as part of their governmental structure. Like any other industrial environment, complex mechanical and electrical equipment are at work performing various functions such as water purification, auxiliary power generation, sludge removal and decomposition of organic wastes. Failure of mechanical or electrical equipment can result in a substantial monetary loss, giving rise to an insurance related claim. A review of four case studies involving such claims gives insight into the technical issues involved. Figure 1 is a view of a typical clarifier pond showing a rotating boom structure that sweeps floating solids to discharge openings on the side. The boom gear drive unit failed, rendering the clarifier inoperative. Figure 2 is a view of the drive base
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showing a water mark inside. Figure 3 shows the remains of the large 2 inch diameter ball bearings, showing evidence of improper lubrication. Apparently the pond had flooded during a severe rain storm, such that the water level was above the oil sump, causing contamination of the lubricant. After the water receded, the unit was allowed to run until the failure occurred. The maintenance department failed to change the contaminated oil after the flood, a procedure that probably would have saved the gear drive unit.
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Figure 4 is a view of an auxiliary generator unit which is typically required for emergency power to run a sewage treatment plant. The unit caught fire during a test cycle, resulting in a total loss. Figure 5 is a view of the diesel engine, showing
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severe damage to the oil pan assembly. Figure 6 is a close-up of the oil pan hole, revealing the remains of a bearing and connecting rod that had failed. The connecting rod was propelled through the oil pan wall, allowing hot oil to escape and become atomized by the turbulent air flow from the cooling fan. Hot surfaces are the likely cause of oil vapor ignition, resulting in the fire that ultimately destroyed the unit. The cause of the loss was mechanical failure of a connecting rod bearing.
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Figure 7 is a view of a large rotating drum used to accelerate biological decomposition of effluent from a sewage treatment plant. The main support shaft failed causing the assembly to settle into its basin. Figure 8 is a view of the shaft which suffered a metal fatigue related failure (see Insurance Adjuster, March 1983). This failure was design related.
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Chlorinator equipment is found in most water treatment operations. A chlorinator room usually contains the chlorine tanks and apparatus used to feed the chlorine to the water supply. A unique failure mode of equipment in these buildings relates to the inadvertent escape of chlorine gas. Although the amount of gas escaping may be minute, it combines with water vapor causing a corrosive hydrochloric acid environment. Figure 9 is a view of a chlorinator room where an improperly installed hose fitting leaked, allowing chlorine solution to enter the area. There was evidence of severe corrosion as indicated by the arrow. The air vent grill shown in Figure 10 was badly corroded, additional evidence of chlorine leakage. A motor controller failed in the chlorinator room as a result of the corrosive environment.
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Figure 11 is a view of another chlorinator room showing evidence of severe corrosion at the ventilation grill. As a result of corrosion from a chlorine solution leak, the furnace thermostat in the room locked shut, causing the furnace to overheat. The very high temperature in the unoccupied room most likely exceeded 150F. This caused polymer housings on several pieces of equipment to soften and sag, rendering the contents a total loss. The causes of losses in water treatment plants are unique to that environment. As exemplified in the chlorine leakage examples, the cause of the malfunction may not be a deficiency in the equipment but leakage of a contaminate that causes a malfunction. Telltale signs such as rust on ferrous metals and green corrosion on copper based metals give clues as to the cause of a loss. As always, the cause of the loss is pivotal in the decision making regarding coverage.