The rain hit on an early summer Friday. In June 2017 a freakish storm, later described as a once-in- 500-year rain event, dropped more than 7 inches of water on central Michigan in just 36 hours. The storm was concentrated over a relatively small area. Midland County, home to roughly 83,000 people, was hit especially hard. Near the city of Midland, the Tittabawasse River quickly rose to flood stage and beyond. On Saturday Rapid Response Brings Calm After the Storm A Michigan consultancy combines innovative technology with strong working relationships to aid public safety and facilitate rapid recovery from a major flood. By John Stenmark
High water from the Tittabawasse River and its tributaries caused serious damage and safety issues at more than 100 locations in Midland County.
the river crested at 32.15 feet, more than eight feet above flood stage. It reached the second-highest level in more than 30 years. In less than two days the river flow jumped from 3,200 cubic feet per second (cfs) to more than 39,000 cfs. The flooding inundated homes, businesses and infrastructure, inflicting millions of dollars in damage. The county’s roads were hit especially hard. By Saturday morning, the Midland County Road Commission had closed roads in more than 120 locations throughout the county. The reasons for closures emphasized safety and ranged from standing water to washouts, damaged pave- ment and loss of culverts and drainage structures. The MCRC needed to act quickly to assess the damage and get repairs underway. The effort included identifying areas requiring immediate attention and developing plans for temporary or permanent repairs. The amount of urgent work was overwhelming. But there was good news: MCRC had a solid partner who was ready to go to work. Rapid Response Led by MCRC Managing Director Terry Palmer, the response to the crisis began immediately. “On Monday morning, we took stock, pri- oritized the damage and determined which roads we could open with minor repairs,” Palmer said. “There were over a dozen water crossings that would require more major repairs—which is when OHM Advi- sors called and offered to assist. They had a team ready to assess our crossings and start the process of obtaining topographic data for the major failures.” Craig Schripsema, manager of OHM Advisors’ office in Midland, deployed the firm’s survey teams to the affected area. The relationship between MCRC and OHM Advisors had developed over many years. A Michigan-based firm providing architecture, en-
gineering and planning for clients in the public and private sectors, OHM Advisors employs more than 500 people in 16 offices across three states. “We work alongside Midland County on many projects,” said OHMAdvisors Survey Practice Leader Ray Lillibridge. “We don't offer typical solutions; we bring forth the best solution customized for the county and not what's most profitable for us. That approach to in- novation has really helped strengthen our partnership.” By Monday the county emergency services were in the field identify- ing washed out bridges and culverts. The locations were marked on a paper map at the MCRC office. Lillibridge quickly added the locations to a GIS application so the information could be readily shared among OHMAdvisors’ teams. “Once we started plotting known washouts, we were logistically able to create a plan of attack,” he said. “We knew a couple of sites had no access, in which case we had to wait for the county to bring in temporary solutions. On Tuesday morning two OHM Advisors field crews began survey- ing the damaged areas. They needed to gather data that would enable their engineers to evaluate the damage and develop plans to repair or rebuild the sites. In addition to often-circuitous routes to the sites, the two-person field crews faced soggy conditions and unstable, poten- tially dangerous slopes near the edges of the washouts. Lillibridge determined that the best and safest approach to quickly producing ac- curate information would be a blend of field technologies including unmanned aerial systems (UAS), GNSS and total stations. At each site, OHM Advisors surveyors conducted a quick walkaround before setting ground control points (GCP) for the aerial imagery. They marked the points using chevron targets. The crews set a minimum of
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may 2020
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