In late September 2016, rising waters of the Cedar River initiated a state of emergency in Cedar Rapids, IA.
Memories were still fresh of the great flood of 2008, the worst in the city’s history. The Cedar River crested at 31 feet, which is 19 feet above flood stage, inundating more than 1,000 downtown blocks and surrounding areas. More than 300 public buildings and 900 businesses were damaged with total flood cost placed at $5.4 billion.
Eight years later, the remnants of Hurricane Paine in the Gulf of California dumped heavy rains in parts of Minnesota and Northern Iowa, giving Cedar Rapids only four days’ notice to prepare for flood crests of more than 25 feet.
To implement the city’s Flood Response Plan, a 24-hour-a-day Incident Command Center was established in the city’s central fire station.
Immediate action was taken to design and construct a temporary flood protection system for both sides of the river to protect low-lying areas that have been redeveloped since the 2008 flood.
Above-ground measures included installation of Hesco sand-filled barrier walls at various locations based on projected river levels. Placed end-to-end, the length of these barriers exceeded nine miles. Earthen berms reinforced with clay were constructed, and more than 400,000 sand bags were filled and positioned to hold back rising waters. These efforts, along with traffic control and evacuations, public safety measures, and communications and public outreach were coordinated from the command center.
Just as important were proactive steps. “In the flood zone, we have 29 miles of storm sewers with 45 connections to the river,” said Dave Wallace, Cedar Rapids utility engineering manager. “We had to prevent flood waters from backing up into the storm sewer system and flooding streets, homes and businesses from underground. With only four days’ notice before the expected crest, we had to work fast.”
Creative measures were required to prevent flood waters from entering underground piping before rapidly rising waters rose above their entry points to the river. Crews built manhole “cones” that capped storm water intakes and manholes to prevent water from the rising river being released onto the streets.
“We built 300 of the cones, and it took two days,” said Wallace. “We estimated another 1,500 cones were needed, and there simply wasn’t time to construct them before underground pipes were flooded.”
The solution also included placing inflatable plugs inside pipe entry points. About 60 plugs were inserted into entry ends of storm sewer pipes ranging in diameter from 12 to 48 inches. These rubber “bladders” were inserted mechanically and then filled with air to help seal off the pipe.
The plugs, primarily from Cherne Industries, were provided by United Rentals Trench Safety.
“The company carries pneumatic plugs as part of its large inventory of pipe testing equipment,” said Andy Stoulil, sales representative in the company’s Des Moines branch. “The logistics of immediately assembling the number of plugs in the sizes needed, in such a short time period, definitely was a challenge (see sidebar).”
Other emergency measures included plugging four storm sewer pipes with concrete and four others with sandbags. Another storm sewer pipe was plugged with compacted clay at a critical point in order to stave off the water and prevent flooding to the NewBo District, a low-lying area of redevelopment that includes restaurants, commercial property, housing and the surrounding downtown district.
Wallace credits the plugging efforts with significantly reducing floodwater damages.
Local contractors, material and equipment suppliers, the Cedar Rapids fire and police departments, the Iowa National Guard, other organizations, and individual citizens played key roles in fighting the flood waters.
Preventive efforts and other factors combined to lessen the impact of the 2016 flood.
Massive preventive steps were quickly and effectively implemented.
No heavy rains fell on the flooding area which would have greatly increased the likelihood of a breech in the temporary levee structures and a much wider area being impacted.
The river crested more than 2½ feet lower than expected, at 22 feet above flood level.
The 2016 flood goes down as the second-highest crest in the history of Cedar Rapids. However, compared to the 2008 flood, the recent one resulted in minimal direct water damage, Wallace said. While precautionary evacuations were put in place, homes and businesses were widely untouched by floodwaters due to the measures that were so quickly put into place.
Cedar Rapids continues to pursue permanent flood control, and has adopted a master plan that calls for a system of gates, levees, and permanent and removable walls on both sides of the river. Work is already underway to construct earthen levees, pump stations and detention basins in some of the city’s lowest lying areas.
Information about the Cedar Rapid’s permanent flood control system is available on the city website, cityofcr.com/floodcontrol.
United Rentals, Cherne Provide Pipe Plugs
Preventing water from the rising Cedar River from entering the city of Cedar Rapids’ storm sewer pipelines and overflowing into the streets was a critical element in the city’s efforts to mitigate damage from the flood that hit in late September 2016.
Sixty-six inflatable plugs ranging in diameter from 12 to 24 inches were provided by United Rentals Trench Safety. And with only four days’ notice of the expected flood crest of the river, delivering the plugs quickly was imperative.
“We received the first call at 3 p.m. Friday, Sept. 23, from Joy Huber, city of Cedar Rapids fleet service manager,” said Andy Stoulil, of the Des Moines United Rentals Trench Safety location. “The initial request was for 35 plugs in diameters of 12 to 24 inches. I coordinated with Eli Hofer, our branch manager in Omaha, who assembled the order with a combination of United Rentals inventory and a purchase of additional plugs from Cherne Industries. Cherne opened its warehouse in Des Moines early Saturday morning, and we sent a truck to pick up the equipment. The truck was loaded at 6:30 a.m.”
Three hours later, the truck arrived in Des Moines and driver Mitch Davis and Stoulil transferred the plugs to a third-party carrier and made the first delivery mid-day Saturday − less than 24 hours from receiving the request from the city.
Late the evening of the same day, Cedar Rapids City Engineer Nate Kampman inquired about 60- and 72-inch plugs.
“We had both of those sizes in stock in Des Moines,” Stoulil said, “and got them on a truck at 11 p.m. that night. They were delivered by 2 a.m.”
Sunday afternoon, Stoulil received another call from Huber requesting another 30 to 35 plugs in the 12- to 18-inch range.
“United Rentals purchased these from Cherne, which opened its warehouse again on Sunday afternoon,” said Stoulil. “We loaded the plugs on our truck at 3 p.m. on Sunday and delivered to Cedar Rapids by 8 p.m. that evening.”
City personnel and contractors installed the plugs at the access ends of the pipes.
A lower than expected flood crest of the river, lack of heavy rains during the flooding period, construction of above-ground barriers, and the steps to keep water from flooding through buried storm system infrastructure combined to greatly restrict flood damage.
In addition to city personnel, including members of the fire and police departments, city office workers, suppliers like United Rentals, area contractors, and individual volunteers played an important part in holding floodwaters in check.
“Our trench safety team members put aside their weekend plans to help ensure that the residents of Cedar Rapids would be protected from a natural disaster. We are proud to be part of a company that steps up for our communities,” concluded Stoulil.
There are 80 United Rentals Trench Safety locations throughout the U.S. which inventory pipe plugs and pipe testing equipment, along with air test kits, hydrostatic test pumps, manhole vacuum test kits and joint test kits, and consultation and engineering assistance on safe placement and removal of pipe plugs. United Rentals Trench Safety also is a primary provider of trench shielding and shoring rental systems in North America.
Based in Minneapolis, MN, Cherne Industries is a leading manufacturer of pipe plugs and testing equipment.