576 MGD Flood Control Solution

Unique Pumping System Aids in Mississippi and Nebraska Flooding

This year has been a record-breaking year for floods. As spring turned to summer and snowmelt combined with seasonal rains began inundating the Midwestern and Southern United States, Rain for Rent’s team of experienced emergency liquid handling experts was put to the test on multiple occasions.

On May 14, the Army Corps of engineers opened the Morganza Spillway, a 10-ton steel floodgate that has remained closed for more than four decades. The gate was opened to protect more densely populated cities down stream along the Mississippi River from the worst flooding in more than 70 years.

The spillway’s redirection of the flooded river sent water as high as 25 ft in rural areas of Mississippi. In Vicksburg, a massive industrial wastewater pond mixed with river water and threatened to overtop containment and further exacerbate flooding in the area.

Rain for Rent provided a temporary pumping solution to gather water from the pond and discharge it into a tributary of the Mississippi River. Two Power Prime DV-600c 24-in. pumps, the largest portable bypass pump in the industry, were set on a floating barge that would rise and fall with the level of the river while drawing water from the pond. The pumps produced 40,000 gpm and prevented the containment pond from overspilling.

While water levels stabilized in rural Mississippi near the end of June, flood problems were getting worse almost 800 miles north along the banks of the Missouri River.

Much of Omaha, Neb., was in danger of catastrophic flooding as water levels in the river lapped at record highs. Any rainfall in the city and surrounding suburbs would cause the CSO levels to back up in the city’s storm water system, threatening residents and businesses. These flows can be extremely dangerous and cause potentially serious health and safety hazards for sections of the city on higher ground not immediately affected by the raging Missouri River. Large and prolonged rain events in Omaha can cause estimated stormwater flows of up to 10 billion gallons per day.

The city’s wastewater treatment plant struggled to deal with combined sewer overflow (CSO) from seasonal rains. As the river rose, the ability to discharge treated water was severely hindered. Meanwhile the College World Series of Baseball — a key economic and tourism event for the city — was scheduled to begin at a newly constructed stadium. The city did not want water to affect the games or the stadium and an emergency call was put in to Rain for Rent to help design a solution.

Rain for Rent’s solution for Omaha’s excess CSO was a two-station pumping project. In less than one week from the initial call, Rain for Rent designed and deployed the first pump station to handle 100,000 gpm. The station used one DV-600c, three HD-600 and three ES-600 pumps to extract water from a culvert in the storm sewer system. That effluent was then discharged to the river via a custom made diversion flume lined with 40mm EPDM liner and K-rails. Installers and operators dubbed the custom discharge flume “the big slip and slide.”

The Power Prime DV-600c handles flows up to 28,000 gpm and 4.5-in. solids through a 24-in. discharge and 30-in. suction. The ES-600 is an electric submersible pump, capable of 17,500 gpm through a 24-in. discharge. The HD-600 is a hydraulic submersible pump that discharges up to 19,000 gpm through a 24-in. discharge and submerses up to 40 ft.

This first pumping station was put to the test almost immediately after installation as a three-hour rain event pushed CSO levels even higher. Rain for Rent’s first pumping station handled the CSO and was applauded by city engineers.

At the second pumping station, a parking lot was demolished to access to large wastewater treatment plant culverts. The tops were cut off these culverts to install four new FP-1050 floating pumps, three additional Power Prime DV-600c pumps and another HD-600 pump.

The high-efficiency, axial-flow FP-1050 is a self-contained floating pump station. This 42-in. pump meets Tier 3 emissions standards and moves up to 68,500 gpm of water and up to 27 ft of head. The floating pumps were floated in the culvert, rising and falling with the variable runoff flows.

This second station handled up to 400,000 gpm and was estimated to have the ability to handle any 10-year rain event that could conceivably happen while the Missouri River is in a flooded condition.

The CSO bypass pumping stations are expected to be in place as long as Omaha’s river remains swollen, which the Army Corps of Engineers estimates could take several months. At the beginning of July, water levels along the Missouri River in Omaha climbed to 36 ft with flows reaching over 216,000 cu ft per second (cfs). Normal July flows are around 32,000 cfs and river height varies between 15 and 19 ft. Any height over 27 ft is a flooded stage in Omaha.

Thanks to the nationwide presence and coordination of trained and experienced pumping professionals Rain for Rent was able to mobilize quickly in response to the emergency flood pumping needs throughout the Southern and Midwestern United States.