Project Summary

Muscatine-Louisa Drainage District #13 (MLDD) operates four pumps at the station just south of Muscatine: two electric, one natural gas, and one diesel. The diesel-powered pump plays a critical role in the region’s sustained protection during emergencies and potential power outages. However, flow testing at 14.2’ TDH showed the pump had regressed to 83,000 GPM; 74% of the pump’s design capacity. It was suspected this regression was due to a worn impeller.

Very quickly, Klingner’s team discovered that the pump’s regression was largely not due to its condition. The existing pump was powered by a refurbished 1930s, 6 cylinder, 530 HP industrial marine engine. This engine was undersized, and the pump was being run at a reduced speed to limit the horsepower required. With an appropriately-sized engine, the pump would be capable of conveying even more water according to the pump curve.

Rather than replace the entire pump station, Klingner developed a highly complex engine replacement and rehabilitation of the existing “pull-out” pump at half the cost. With the District’s approval, a 12 cylinder turbo diesel engine capable of 1,475 HP was identified as the most cost-effective solution. Although oversized for the maximum flowrate of the pump, a government-surplus, low hour engine could be purchased and retrofitted at a fraction of the cost of a new engine. Since the replacement engine has a different operating speed and the existing equipment was designed for a lower horsepower, a new right-angle gear and high-speed drive shaft were required. Calculations showed that a turndown ratio of 3:1 was required to operate the pump at the revised hydraulic conditions.

Once the team knew the engine would match the pump operationally, the engine had to be perfectly aligned within the building. As the refurbished pump’s positioning was fixed, every new piece of machinery had to fit between the existing pump and station wall. At the same time, the high speed shaft required a minimum length to be at the proper angle to extend its bearing life. Klingner carefully coordinated with the manufacturer to balance operational needs with physical limitations, resulting in a universal shaft bearing life in excess of 30,000 hours. New fuel lines were run beneath the floor from the existing fuel system to the engine fuel filters, and the existing engine base was removed so that the new engine could be secured to the foundation. A “duct room” was built within the building footprint to funnel rejected engine heat from the engine radiator to a new mechanically-operated louver / damper, ensuring that radiator exhaust was discharged outside of the building while maintaining access to the radiator for inspection and maintenance. New roof exhausters were then added to increase airflow through the building.

Additionally, Klingner developed a wiring scheme and “black start” procedure for emergency operations, which involves powering the two engine block heaters separately. This allowed the voltage to match commonly available portable generators. Installing a plug and cord for the final connection to the heater allows them to operate from a portable generator during power outages. Alternate power is also available for the starting batteries, fuel transfer pumps, new automatic grease system, and lights.

The refurbished pump and new engine have delivered an 87% increase in pumping capacity for MLDD.