MEC&F Expert Engineers : ALMOST 7 INCHES OF FALLING RAIN SWAMPS SIOUX FALLS, SD CAUSES MASSIVE FLASH FLOODING

Friday, August 28, 2015

ALMOST 7 INCHES OF FALLING RAIN SWAMPS SIOUX FALLS, SD CAUSES MASSIVE FLASH FLOODING








Flood: Vehicles, basements swamped after more than 7 inches
Argus Leader staff 8:41 a.m. CDT August 28, 2015
"West side of Sioux Falls off grinnell ave. (The Driver) is out and safe. @ryanisaacson42



(Photo: Joe Ahlqusti / Argus Leader)

More than half a foot of rain fell on parts of Sioux Falls, SD Thursday evening, sending flash floods ripping across roadways and pouring into basements.

No one was hurt, but the waist-deep waters stranded scores of motorists and left hundreds mopping up wet basements. The worst hit areas were in southwestern Sioux Falls, where city crews and property owners were still assessing the damage late Thursday.

As of 2 a.m., all area roads were open, but police urged caution as some vehicles were still on roads as well as debris.

"Our one hundred year rain events now seem to happen every couple of years," Mayor Mike Huether said. "The monster investments in infrastructure have paid off but more work needs to be done."


RAINFALL: Jim Murray, a meteorologist with the National Weather Service for about 15 years — 10 of those in Sioux Falls — said 1-3 inches of rain had been expected Thursday, which itself is a lot. "Whenever we forecast those kind of amounts there's the potential to get significant rain."

That 1-3-inches prediction could very well be the average of most spots, he said.

The biggest rainfall report the NWS got was from a resident who measured 7.73 inches at Drexel Avenue and 61st Street, which is southwest of 57th and Marion. To verify public reports, Murray said weather officials consider the radar at the time and nearby reports to see if it is reasonable. He said the 7.73 inches was quite likely accurate.

Other storm totals:

6.6 inches near 26th and Marion

6.46 near Dunham Park

6.19 in western SF

5.32 off of Cliff south of 57th

2.61 at the Sioux Falls airport

1.5 at LeMars, Iowa

1.1 at Lake Park, Iowa

"We were getting three inches of rain per hour in the early evening hours in Sioux Falls," meteorologist Mike Fuhs said. "There is nothing that can keep up with that."

FLOODED STREETS: Flash flooding swept across streets, intersections and parking lots, making driving risky or impossible across much of the city. No travel was advised in the city late Thursday night.

Sioux Falls Fire Rescue Division Chief Jay Titus said the area of town that experienced the worst flooding is between 41st and 57th streets and Western and Sertoma avenues.

Other areas where flooding was reported: on Interstate 29 under 41st Street, the 57th Street bridge that goes underneath I-229, 41st and Louise Avenue and other areas on 41st Street west of Interstate 29; Kiwanis Avenue near the Great Plains Zoo, and at 69th and Cliff and parts of Sertoma Avenue.



The Big Sioux River surges over the falls at Falls Park early Friday morning, Aug. 28, 2015, after heavy rains Thursday in Sioux Falls.

HARROWING ESCAPE: Danny Sullivan, his wife and daughters were celebrating his father's 50th birthday when they heard the weather was getting bad. They were headed home when they found themselves getting in deeper and deeper water near 54th Street and Plateau Trail.

"There was no way to see except for our headlights," Sullivan said. "Before we knew it … the water was up to the windshield."

Eventually, the car was so submerged that Sullivan and his family were forced to climb out the sunroof of their Ford Freestyle, leaving the car behind. Sullivan, his wife and a few others were later able to push the car onto dry land.

Although his car suffered substantial water damage, Sullivan said he was grateful that no one was hurt.

"I'll never forget any of it," Sullivan said. "I've lived here my whole life and I've never seen anything like that."

STRANDED MOTORISTS: Waist-deep water stalled scores of vehicles on the roads, with some being pushed along by raging waters.

The water levels reached above the wheels of cars. At one point, a car bumper floated down the middle of Louise Avenue. Some people waded from one side of the street to the other, soaked by the cold water. "I'm worried about my house," said Karen Whitcomb, who works at Sears. "I'm determined to get home."

Sabre Judstra, who lives in an apartment near Valhalla Boulevard and Solberg Avenue, was out wading through waist-deep water when he saw a woman driving toward him. "All of a sudden I see a car … I was trying to tell them to turn back," Judstra said.

Judstra and a reserve police officer pushed the floating car to a curb on Solberg Avenue before helping the woman escape.

"We got her out through the window," he said.

The car later became completely submerged in the water along with several others.

David Jones said he helped get people out of a car that was flooded on W. 26th Street.

He said the car was up to water waste high as water swept through the area.

"The people who got out of their car had to have a rope tied out of them to get them through the windows," he said.


DAMAGED BUILDINGS: There were several reports of damaged structures. The National Weather Service said they heard of a partial roof collapse at the Empire Mall. Hy-Vee on S. Louise Avenue had flooding, as did Sanford Health closer to downtown.

Dave Decker, a pastor at Trinity Baptist Church on W. 18th Street just off of Kiwanis Avenue, said a window in the basement broke and flooded the basement with about six inches of water. Some of the flooring in the basement gave in and more water seeped in, he said.

"We were hanging out then water starts coming in the basement wall," he said. "Then a piece of plaster breaks. Then we heard a big crash and the window breaks. Then the water starts coming in like a waterfall."

WET BASEMENTS: Homeowners spent the evening mopping up lower levels.

The city reminded residents to make sure sump pumps are draining outside their homes to prevent backups in their or their neighbor's basement.

"Improperly discharging of sump pumps into the sanitary sewer system can result in sewage backups into homes," said Mark Cotter, the city's public works director. "It is illegal to attach sump pumps to floor drains or otherwise connect them to the City's sanitary sewer system."

POWER OUTAGES: More than 4,000 Xcel Energy customers lost power during the storm. A spokesman for the utility said electricity had been restored to more than 2,500 customer as of 11 p.m. At 1 a.m., the outage was down to 200 or so customers.

"They've got boats out there right now on 41st Street. We've got water in a whole bunch of basements so we're working through that," Eric Pauli said.

LIGHTNING STRIKES: Three houses in southern Sioux Falls caught fire after being struck by lightning.

The first call came in around 4:30 p.m. from 5800 S. Copperhead Drive. Smoke was coming from the roof of the home. Two more lightning strikes were reported a few hundred feet apart, one at 2901 W. Cinnamon Circle and the other at 3004 W. Cinnamon Street. Both calls came in around 5:30 p.m.

NIGHT OF RAIN

Heavy rain: 6.6 inches of rain was reported at 26th Street and Marion road while the airport received just 2.59 inches.

Online: Follow continuing coverage of the heavy rain with photo galleries, videos and more today at argusleader.com.

Tell us your story: Were you stuck in the rain? Tweet @argus911, email argus-

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Aug. 25, 2015, 10:17 p.m.