Spot Check: Stormwater deja vu...again?

On July 23, Winnetka was pummeled. 4.97” of rain in a little less than 6 hours. Standing water, flooded basements, exhausted plumbers, reclamation companies making their numbers for the year, out-of-stocks at Lowes, Home Depot and Best Buy, and tons of curb trash launched two Village Council meetings [Aug.2nd & 12th] and a boatload of letters, phone calls and personal appearances.  

And that was just a “50-year flood."

LET’S JUST CALL IT A 1%-ER

That "100-year flood" thing? It's really a "rain event" that has a 1% chance of happening in any given year. And it's different for every community, based on the rainfall-on-record. For Wnnetka, that's 4.85" in 3 hours.

But wait – there’s more...

  • July 23rd, 2016 – 5” in 6 hours
  • April 8, 2013 –  3.5” in 12 hours (ground was saturated. Water went overland.)
  • July 22&23, 2011 – 6.49” in 3.5 hours
  • September 13-15, 2008 – 8.19” in 36 hours
  • August 2, 2002 – 5.44” in 6 hours

In case you think Winnetka’s being picked on.

WHERE’S WATER COMING FROM?

A boatload of places.

  • Overland & street flooding
  • Seepage 
  • Sanitary sewer backups
  • Sanitary sewer cracks infiltrating or flowing into stormwater system
  • Cross connections, open manholes
  • Backup from the interceptor system [Aug. 2nd, 30:00]
  • Private property hookups, cracks and crashed pipes, joints “significant likely source of infiltration and inflow…”

NEIGHBORS MAY BE A LITTLE TOO GENEROUS

Many parts of Winnetka are lower than neighboring villages. We may be taking on their water and sewage, or the inlets – where all of our water heads to the Metropolitan Water Reclamation District to be cleansed – may be plugged. The Village is working with MWRD to troubleshoot. Can you say “backflow preventers at our borders?”

WHAT WORKED AND WHAT DIDN’T?

For five years, Public Works has been paddling like crazy to address problems in various neighborhoods. [#4 pg. 27] with storm sewer and sanitary sewer fixes. What’s the difference?

  • Northwest Winnetka got a brand-new large-diameter sewer system under Tower Road. It worked, no flooding. Thanks, guys.
  • Winnetka Ave got upgraded pumps to get more water out from more places quicker. It “functioned as designed.” Translation: lowered water levels by Sunday and when temporary pumps were added, drained quickly.
  • Ash Street got larger pumps to – again – move water out faster. Didn’t clog and removed water in less time once it had a place to go. “Place to go” is still a problem.
  • Northeast Winnetka got two fixes – Lloyd Outlet and Tower Road – to reduce flooding on Maple and get rid of flooding on Spruce and East Tower Road. Not so much this time. Some homes still bailing. Village addressing.
  • Various neighborhoods got “targeted sanitary improvements” like smoke testing, sewer relining, sewer replacements, and downspout disconnections. At least they didn’t add to the problem. 
  • Southwest Winnetka got Strand-ed. Big problems need big ideas and big guns. The Cook County Forest Preserve is still listening. If and when it thinks we're ready for prime time, it’ll hand us off to the Cook County Board. The Village Council asks residents to stay strong and watch for the go-ahead to tell the CC Board we reeeally want this. Names and addresses TBD.

UNDERWATER NEIGHBORHOODS DON'T FLOAT THE VC'S BOAT

So the Trustees came up with a short-term bucket list.

  • Reinstate incentives for backflow prevention and overhead sewers. [pg. 44]
  • Get more pumps.
  • Use Duke Childs Field as emergency drainage.
  • Survey residents to see what happened where.
  • Form Winnetka Resident Task Force to aid in getting word out.
  • Understand there are two problems – sewage and stormwater and work on solutions simultaneously.

STRAND'S STILL PADDLING

  • Re-examining the phasing to capture more low hanging fruit, including retrofitting the Skokie Ditch for additional storage.
  • Developing a process to work with the CCFP to stage a solution.

Due date: October 11th Study Session. Note to self. Next oar in the water - 

  • Strand’s projects deal with 474 properties in Southwest Winnetka. Among those are 61 properties throughout the Village that don’t get relief. They’re in so-called “mitigation zones” [Figure #7] and Strand says let’s one-on-one with these home owners to deal with it. Evaluate, budget, solve. TDB for the 2017 budget.

BEFORE YOU GO ALL NOAH’S ARK