LAKE FOREST — Street flooding requiring the Lake Forest Fire Department to rescue eight people and two dogs October 14 was partly caused by poorly maintained culverts designed to help water flow from its source to the east fork of the north branch of the Chicago River.
Debris such as construction signs and tires slowed water flow from the west through culverts underneath Highway 41 and the Union Pacific Railroad’s freight tracks causing street and other flooding, according to civil engineer Mike Bleck of Lake Forest-based Bleck Engineering.
Bleck, who has done drainage, highway and utility engineering for Lake Forest, Lake Bluff and Northwestern Medicine Lake Forest Hospital, said he inspected culverts going under the highway and Union Pacific freight rail line that runs along 41 between Lake Forest and Lake Bluff after heavy storms July 11 and 12.
“Some of them were so plugged up hardly any water could get through,” said Bleck, referring to the culverts under the highway. “The railroad was even more challenging. They were plugged up with brush and buckthorn.”
The culverts under Highway 41 are maintained by the Illinois Department of Transportation while those under the railroad tracks are the responsibility of the Union Pacific, according to Bleck.
Rainstorms that cause flooding are becoming more frequent in Lake Forest because of the inability of the drainage system to handle the amount of water and the saturation caused by frequent rain, according to Michael Thomas, the city’s public works director.
Of the five heaviest rain falls in the last seven years, two have occurred in the last three months, according to a presentation Thomas made to the Lake Forest City Council October 16 at City Hall.
The record was set in July when 6.7 inches fell on Lake Forest, causing widespread flooding and street closures and the evacuation of the hospital. Bleck said the poorly maintained culverts were a contributing factor to the damage that caused the evacuation.
Three months later, the official rainfall was 3.71 inches October 14, but Thomas said 5.21 inches fell at a measuring station on Butler Drive between Green Bay Road and Highway 41 where the water flows eastward to the river. Before that, 5.55 inches fell over three days in May 2010, 4.95 inches over two days in April 2013, and 3.31 in May 2014.
Thomas said the problems were compounded this fall because of autumn leaves. He said the leaves added to blockage not only in the culverts but also on the streets where they clogged the entrance to storm sewers. There is street sweeping but not every street every day.
“We sweep the streets until the first snow flake falls,” said Thomas. Though people can rake leaves away from storm sewer entrances by their homes, he urged caution. “The covers can pop up from the water pressure.”
Saturation from rain earlier in the week made things worse, according to Thomas. He said 1.88 inches falling October 18 coupled with Saturday’s total made it more than five inches in a short period of time.
Thomas said the city offers a free home inspection to let residents know what they can do to minimize the chances of water in their basements. He urged a backup sump pump as well as a battery powered power source for the pump.
All rainwater from the eastern edge of Lake Forest flows to the river as does everything from just west of Waukegan Road, according to Bleck. He said when the storm sewers fill up, the water gets there on streets or through yards.
The problems around Deerpath Road and Highway 41 are further compounded by an aging pumping station operated by IDOT. Thomas said it has been there since the 1950s and has not been updated.
“IDOT has been looking at it for four or five years but they don’t have the money,” said Bleck. “It didn’t help the situation,” he added referring to the hospital evacuation.
In Lake Bluff, 4.25 of inches of rain fell and the Highway 176 underpass beneath the Metra tracks was closed October 14 for about six hours, according to Village Engineer Jeff Hanasen. Though more rain has fallen this year than in the last few, he said he knows of no significant infrastructure problems.