Council Reviews Possible Flood Prevention Plans
Improvements include a massive tunnel project to funnel water to Lake Michigan.
After a three-and-a-half hour study session Tuesday evening, the Winnetka Village Council took big steps toward finding solutions to the area's flooding troubles.
Thomas Burke, Jr., of Christopher B. Burke Engineering, presented a 25-page packet outlining the flood risk reduction assessment for the village, encompassing drainage improvements and conceptual plans, as well as cost estimates.
Areas studied include North of Willow Road, South of Willow Road, the Winnetka Avenue underpass, the Cherry Street outlet, the Spruce Street outlet (including the Lloyd Park Outlet and Tower Road area), the ravine and Greenwood Avenue.
Trustee Christopher Rintz congratulated Burke’s firm on a “job well done,” as did many of the other trustees.
“This is, by far, one of the most comprehensive works I’ve seen in such a short period of time of any firm I’ve worked with,” he said. “This really helps move the conversation forward in a big way.”
Previous studies by the firm examined the 10-year storm events, which have a 10 percent chance of occurring, after the Sept. 2008 storm, but, after the July 23-24 storm this summer, analysis for 25-, 50- and 100-year storm events (those with a four, two and one percent chance of occurring, respectively) was incorporated. The village can choose the level of protection for each project, which would entail larger sewers, detention, outfalls and pumps for larger storm events.
Several audience members brought up the idea of a “blue ribbon committee” of resident experts. Tucker said, “[This council] is your blue ribbon committee." The council said it still welcomes public comments.
Trustee William Johnson explicitly asked for help from those who have expertise in finance, engineering or related fields.
“We would love to hear from you,” he said. “We will take you seriously.”
Summary of Proposed Improvements
North of Willow Road: Improvements include new large storm sewers, stormwater storage in conjunction with the park district, and additional storage on Cook County Forest Preserve property. Water detention would also occur in Winnetka Park District’s Skokie Playfield, New Trier High School’s Duke Childs Field, the Winnetka District 26 field between Skokie and Washburn, and the forest preserve south and west of the golf course. The cost estimate for 25-, 50- and 100-year protection is $13 million, $14.8 million and $17.5 million, respectively.
South of Willow Road: Improvements include a new large diameter outlet storm sewer to the forest preserve ditch, lowering and regrading Skokie Ditch, and storage on Cook County Forest Preserve property. This proposal also allows creation of a detention area adjacent to a closed landfill. The cost estimate for 25-, 50- and 100-year protection is $9.7 million, $12.6 million and $17.8 million, respectively.
Winnetka Avenue underpass: Improvements include a new storm sewer and larger pipe sizes from the Winnetka Avenue underpass to the outlet at Elder Lane. The cost estimate for 25-, 50- and 100-year protection is $2.9 million, $3.4 million and $4.4 million, respectively.
Cherry Street Outlet: Improvements include new storm sewers along Oak, Cherry and Ash streets, as well as Sheridan Road, and a larger outlet to Lake Michigan. The cost estimate for 25-, 50- and 100-year protection is $1.8 million, $1.9 million and $2 million, respectively.
Spruce Street Outlet: These improvements were divided into Tower Road relief and the Lloyd Park outlet. Tower Road stormwater would be discharged to the ravine outlet system and the cost estimate for 25-year protection is $1.3 million, with a cost of $1.4 million for 50- and 100-year protection. A new intermediate outlet from Sheridan Road at Lloyd Park would also be created, with a cost estimate of $500,000 for all levels of protection.
Ravine area: Improvement to this area would include regrading the lower areas to prevent water retention, and the cost estimate is $500,000. However, IDOT is evaluating improvements here and the village is not considering funding this right now.
Greenwood Avenue area: Improvements include new large storm sewers and larger pipers to increase transfer of water into the storage reservoir south of Tower Road near Forest Way Drive. The cost estimate for 25-, 50- and 100-year protection is $2.2 million, $2.3 million and $2.9 million, respectively.
Total cost for these projects
- 10-year protection: $14.1 million
- 25-year protection: $31.9 million
- 50-year protection: $37.4 million
- 100-year protection: $47 million
Village President Jessica Tucker asked Burke if 25- or 50-year improvements would be enough to prevent problems that would arise in 100-year events, but Burke said there was no way to know for sure if some homes would not flood with the lower level of protection.
Lake Michigan Outlet Project
This is not a study area, but a larger scale project that would combine improvements to the areas north of Willow Road, south of Willow Road, Provident Avenue, the Cherry Street outlet and the underpass.
While all improvements require significant permitting, this project would require the most, as it would be diverting stormwater from the Chicago River to Lake Michigan. The Army Corp of Engineers, the Illinois Department of Natural Resources and the Metropolitan Water Reclamation District would be involved.
Tunneling for the eight-foot storm sewer under Willow Road from Glendale Avenue to the lake, with multiple sewers extending into the study areas, could cost either $32.5 million through clay or $56.9 million through rock.
If a new outlet to Lake Michigan is constructed, the total cost would be $37.8 million for all projects with 100-year protection, including the Lloyd Park outlet, Tower Road relief, and the ravine and Greenwood Avenue areas. However, if tunneling must be done through rock, the total cost would be $62.2 million for everything.
With the Lake Michigan Outlet Project, the village is estimating the cost at $34 million, before soil borings is completed to determine what type of material will have to be tunneled through.
How to Pay for Stormwater Projects
For the tunnel, the village is considering financing it with bonds at the current low interest rates or implementing a stormwater utility fee to raise money. The other improvement areas will be funded through cash reserves, according to the village agenda’s conceptual plan.
Steve Saunders, public works director and village engineer, said once the backbone system is in place with the Lake Michigan tunnel, other improvements can be added as they come up.
He said the tunnel project could possibly be completed within five to seven years, and it’s an “alternative to a complex series of projects, and can be done concurrent with construction on [the smaller] projects” at the Lloyd Park outlet, Tower Road and Greenwood Avenue.
Burke said he would recommend pursuing the tunnel project, while addressing water quality, because it gives the most flexibility. He also said the tunnel wasn’t considered when doing the previous studies for smaller storm events, but when the firm took 25-, 50- and 100-year events into account, it made sense.
When asked about getting another engineering firm to survey again for a second opinion, Saunders said the council would have to live with some of the estimates.
“You’re not going to know the cost until you have bids in front of you,” he said.
Rintz, after shooting down the idea of raising property taxes to pay for the improvements, said he was happy to be moving forward.
“It’s easy to get bogged down with this,” he said. “We don’t want to get into a situation where we need one more data point to make a decision. We’re never going to have a perfect plan. We will deal with it as it comes.
“We were looking for something visionary to bring us to the promised land, and this tunnel is it.”
The council decided by the end of the session to put together a critical path plan, look into financing options, get in touch with regulatory agencies, as well as have soil borings completed to determine the tunnel drilling cost and possibly look into getting second opinions on the conceptual costs.
The group also agreed the Lake Michigan tunnel and the smaller projects at Lloyd Park, Tower Road and Greenwood Avenue would be the way to go, with those smaller projects moving forward from this point.
Trustee Gene Greable said it’s time for the council to get moving.
“We made a big step forward tonight, and we need to keep it up.”