Lake diversion part of Winnetka’s new stormwater plan
Updated: July 23, 2012 6:13AM
The Village of Winnetka must mount a succession of regulatory, financial and political hurdles before its vision for a flood relief tunnel along Willow Road can come to fruition.
But village administrators say meetings with regulators to date suggest that obtaining the necessary permits remains feasible.
The ambitious project would divert some rainwater from west Winnetka and the Chicago River watershed to Lake Michigan.
The tunnel project will be a key component of a new Stormwater Master Plan now in development. Village trustees June 12 awarded a contract to Baxter and Woodman to create the plan, which is intended to provide the framework for planning, financing, constructing and maintaining improvements to the stormwater and sanitary sewer systems. The consultants’ costs have been capped at $101,220.
Public Works Director Steven Saunders says the village will keep moving foward on stormwater and sanitary sewer initiatives already underway, including the engineering work trustees have authorized for the Tower Road Relief Sewer, the Greenwood Avenue Relief Sewer and the Lake Michigan outlet at Lloyd Place.
“The Stormwater Master Plan does not necessitate that we stop, take a step back and maybe start over,” Saunders told trustees last week.
Winnetka officials and citizens were quick to latch onto the tunnel idea last fall when Christopher B. Burke Engineering included the option in a comprehensive study of eight flood-prone areas of the village. The tunnel was an alternative to increased underground storage and above-ground detention on public property, including land owned by the Cook County Forest Preserve District.
The tunnel and connecting sewers would relieve flooding in five of eight vulnerable neighborhoods. They include two areas north and south of Willow Road; an area around Provident Avenue and Blackthorn Road; the underpass area of southeast Winnetka and the area around Cherry Street and Sheridan Road.
The village has hired the firm of Baird and Associates to conduct an engineering study of the tunnel project as it relates to the Lake Michigan coastline.
The stormwater diversion project will require approvals from the Illinois Environmental Protection Agency, the Illinois Department of Natural Resources, the U.S. Army Corps of Engineers, the Metropolitan Water Reclamation District and the Union Pacific Railway.
Under the proposal, an oversized sewer of eight-feet in diameter would be constructed along Willow Road from Glendale Avenue to Lake Michigan. To counter the natural topography which slopes upward, a tunnel would be burrowed between Birch Street and Poplar Street in order to use gravity to keep the flow of stormwater moving toward the lake.
Flash flooding last July overwhelmed Winnetka’s stormwater drains and sewers, causing water to burst through window wells and back up into basements. It marked the third major flood in several years. Several Burke studies have found that Winnetka’s stormwater infrastructure in some areas cannot handle the five-year, or even the two-year storm, that is, rainstorms with a 20 or 50 percent chance of occurring in any given year.
The cost of the stormwater improvements, including the tunnel, have been estimated at $39 million.
If the improvements are financed through general obligation bonds repaid with property taxes, a $40 million bond issue would cost, on average, an additional $658 a year per parcel over each of the next 20 years, according to a village analysis.
The village also is conducting a stormwater utility rate study to look at financing improvements through higher charges for water and sewer service.