Power issues 'played a large role' in flooded Detroit basements, consultants says
A brownout at a pumping station on Detroit's east side during heavy July rainfall "played a large role" in basement backups reported upstream, a consultant investigation into the summer flooding concluded in a presentation to the Great Lakes Water Authority board this week.
Ed Hogan, vice president of the civil engineering firm Wade Trim, on Wednesday summarized the firm's "major findings" of what arose during the July 16 storm that socked the region just weeks after Metro Detroit was hit with downpours in late June.
The Conner Creek pump station in Detroit had a strong power supply during the July storm, but the presentation to the GLWA board Wednesday noted Detroit's Freud and Bluehill pump stations had "weak" power supplies.
The impact of the poor power quality, the presentation notes, lead to unintended pump stoppages or pump trips at the Freud station during June 25 and 26 rain events, which delayed GLWA's ability to get the third pump running, the presentation document said.
It also led to a brownout during the July 16 storm at the Bluehill pump station on Mack Avenue, it reads.
"This created an electrical upset which resulted in a reduced number of pumps running during the event," according to the post-event analysis presentation by Wade Trim and environmental engineering firm Brown and Caldwell.
GLWA, during the July rain event, reported that the Bluehill station had experienced "an external power quality issue."
Although it was not a complete outage, GLWA said at the time that it dispatched a response team to the site and activated an emergency generator. The authority also said it would seek an after-event analysis and work with residents in the tributary system to determine if they had experienced flooding.
The analysis presented Wednesday also notes that the late June storms brought three bursts of rain. The first two bursts resulted in one inch of rainfall and the third brought another six inches.
As a result of the first two bursts, the collection and treatment systems "were at or near capacity," the presentation document notes. Conner Creek facility was at full capacity and was already discharging, it reads.
During the third burst, collection was surcharged, most level sensors were maxed out and water was flooding to the ground surface level.
The analysis also suggests that the timing of a power supply conversion from Detroit's Public Lighting Department grid to DTE Energy was a critical factor in the number of pumps available at Freud during the June storms and at Blue Hill in July.
DTE Energy spokeswoman Jill Wilmot told The Detroit News Thursday they haven't seen the consultant report but disagreed that the supply conversion played a factor.
"We’re working closely with GLWA to coordinate the timing of the transition of the Blue Hill Pumping Station from PLD to DTE," the company said in a Thursday statement, declining further comment due to pending litigation over allegations DTE didn't do enough to ensure reliable electrical power to the Freud pump station.
Suzanne Coffey, interim CEO of GLWA, told The Detroit News earlier this month that it will cost anywhere from "$5 billion to $20 billion" to shore up the regional infrastructure enough to prevent heavy storms from flooding basements in Metro Detroit.