The location of the study area around the Upper Malletts Creek area in southwestern Ann Arbor.
Courtesy of Washtenaw County's Office of Water Resources
There will be a public meeting from 7 to 8:30 p.m. Thursday at Lawton Elementary School’s cafeteria at 2250 South 7th St. in Ann Arbor.
The city of Ann Arbor directed Pratt and his team to conduct a study of flooding issues in the area with the Upper Malletts Creek drain and come up with possible solutions for the watershed area bounded by Ann Arbor-Saline Road, Interstate 94 and Scio Church Road.
Much of that portion of Malletts Creek is in underground pipes carrying storm water runoff from urban areas of Ann Arbor. About 37 percent of the watershed area to the drain is impervious surfaces.
During the storm associated with the Dexter tornado in 2012, the deluge of rain overwhelmed the rain system in southwest Ann Arbor. The closest rain gauges to the neighborhood recorded rainfall of 1.5 inches in half an hour, and 1.9 inches in 70 minutes, Pratt said.
Water could not get off the street and so it flooded the yards -- especially in the area by Scio Church Road west of I-94.
The water started flooding on the surface during the heavy rain event a year ago, and traveled from Wilkshire Court to Mershon Drive to Delware through the streets and people’s backyards.
Pratt said part of the intent of the study is to determine if all of the storm water pipes were at capacity during the storm, or if there are areas where water was not able to drain into a pipe.
“Our goal is to reduce the probability of flooding if this type of event is going to happen again,” Pratt said.
The project is a partnership between the city and the county. Spicer Group was hired by the city to do the consulting work for the project on a contract of up to $200,000. Pratt was an employee of Spicer Group until his election in November to the post of Water Resources Commissioner.
Pratt said his input was removed from a portion of the bidding process to make it fair - however the review team selected Spicer Group as the top choice.
The county’s water resources office is involved in the project because Malletts Creek is a county drain under its jurisdiction.
Over the course of this year Pratt and his team will be soliciting public input to help develop a suite of solutions by February of 2014.
Each complaint or concern about flooding issues will be put on a map. Pictures and videos also are helpful in determining how flooding happened during the storm and will help engineers find solutions, Pratt said.
Though neighborhoods in southwest Ann Arbor historically have had concerns of sewage backing up into basements from footing drains, a recent program to install sump pumps with special valves by the city has alleviated some of those problems, Pratt said.
Many of the homes in those neighborhoods had drains underneath the house to remove water that could collect there. Those drains were connected to Ann Arbor’s sanitary sewer system in the 1980s, Pratt said.
The southwest corner of Ann Arbor is lower than the rest of the city, and has mostly clay soils, Pratt said. The ground water level is fairly high, Pratt said.
Old aerial maps of Ann Arbor show the corner was interlaced with creeks before it was developed into subdivisions, Pratt said.
“We hope people can look past what’s the reason for the problem and to the solutions,” Pratt said.
A volunteer committee of nine residents also has been created to help guide the study.
Information and updates on the study are online at a website created for the project.
Amy Biolchini covers Washtenaw County, health and environmental issues for AnnArbor.com. Reach her at (734) 623-2552, amybiolchini@annarbor.com or on Twitter.