Experts reviewing June’s flooding on behalf of metro Detroit’s regional water system said water-logged basements were inevitable, but the “depth and duration” of the residential flooding would have been less without power failures at key east-side pumping stations.
The statements based on model simulations came Wednesday at a meeting of the Great Lakes Water Authority (GLWA) Board of Directors. The authority hired two firms to reconstruct what happened and suggest improvements. In addition, the board directly hired a third firm to complete its own review.
Ed Hogan, a vice president at Detroit-based engineering firm Wade Trim, said their preliminary investigation shows the heavy rain would have caused some basement flooding no matter how GLWA facilities responded.
“The initial model results indicate the geographical extent of basement flooding was very similar to what would have occurred under more ideal circumstances,” Hogan said. “What is different, is the depth to which that basement flooding may have occurred, also the duration.
“But there is no question that the intensity of this rain event and the duration of the intensity of this rain event was such that there was going to be extensive basement flooding.”
He didn’t share any specific estimates from his modeling on Wednesday.
The storm on June 25 and 26 damaged thousands of homes and ruined hundreds of vehicles in freeway flooding. The brunt hit Detroit, Dearborn, Garden City, Ypsilanti and the Grosse Pointes. Wayne and Washtenaw counties were later declared a national disaster area.
GLWA officials have said an intense amount of rain primarily caused the June flooding. But the authority acknowledged that electrical problems hampered east-side pumping station operations at Conner Creek and Freud.
GLWA subscribes to two weather services that predicted about 1.5 inches of rain June 25-27, versus 6 to 8 inches that the area received overnight, Hogan said. The system is designed to handle up to 1.7 inches in an hour, he said.
Hogan said besides the rain, the power failures at Freud was the “next biggest issue.”
Up to seven stormwater pumps are designed to work at one time at both Freud and Conner Creek.
Freud had only three pumps running during the June storm because of a damaged power line. Conner Creek had a total of five pumps working by 1:53 a.m. after a power issue delayed three pumps from starting initially, GLWA officials have said.
Employees were aware of the power outage at Freud three days before the storm. But former CEO Sue McCormick has said she only knew of the electrical problem the morning of the storm. Under scrutiny, McCormick resigned in July.
Dave Nitz, who GLWA also hired, said he’s investigating other “power quality” issues at Freud. Nitz is a vice president with engineering firm Brown and Caldwell, which is working with Wade Trim.
It’s not clear when the full investigation done by both engineering firms will be done.
GLWA officials say they are working on power solutions with DTE. But they’ve ruled out adding more generators because it would take too long for the additional generators to get started during afast-moving storm. They are trying to reestablish a third power line to Freud to reduce the impact of potential power outages.
GLWA is in the process of a $250 million rebuild of Conner Creek, built in 1929, and Freud, constructed in 1955. But the process could take several years.
More: Investigators pushed for basement flooding text alerts. But Detroiters never got them.
More: 150 million gallons of raw sewage discharged into Michigan waters after storms
GLWA faces multiple lawsuits from flood victims suing to recover damages, citing the pump stations’ breakdowns. The Detroit Water and Sewerage Department reports it has received more than 27,000 claims from the June flooding.
In Detroit, the cleanup goes on.
Friday is the last day in Detroit for bulk daily pickup of flood debris in affected areas. More than 60 million pounds has been removed from neighborhoods so far, city officials said. And residents in Washtenaw and Wayne counties have until Sept. 13 to apply for FEMA aid from the June storm.
Contact Christine MacDonald: firstname.lastname@example.org or 313-418-2149.