What’s With All The Rain Lately?

What’s With All The Rain Lately?

On Thursday, May 14th and again on Sunday, May 17th, the Village experienced two very intense rainfalls. Lake County received between 1.29” and 3.77” of rain from 7am Thursday to 7am Friday. Deerfield measured 2.34“ within about 3 hours and 3.63“ thru Friday AM. On Sunday, another 1.4” to 3.1” fell in 24 hours, but the most intense amount fell in about 2 hours.

On May 18th, the Lake County Stormwater Management Commission (LCSMC) observed that the Des Plaines River in Lincolnshire was at “major” flood stage. The North Branch in Deerfield, just downstream of Bannockburn was at “minor” flood stage.

Weather is unpredictable! Just ask the weatherman.

Rainfall intensity is one of the many variables the we use in predicting the size of storm sewers, ditches and detention ponds needed to convey runoff to the local streams and waterways throughout our community.

Intensity is the speed of time it takes for the rain to fall. A more intense rainfall produces more runoff than an April shower lasting all day. Intensity is related to the probability that a certain rainfall will cause flooding or be insignificant. Probability is the description of how likely the rainfall intensity will be.

In 2020, the LCSMC will be adopting new rainfall intensity charts that will reflect our most current experience. That means that all future redevelopment project will be using charts that predict the intensity increasing by about 50% over the old charts.

The Village Public Works maintains and cleans the roadway storm sewers, curb inlets, roadside ditches and major public waterways. These pipes are not designed to carry all intensity storms. When the storm sewers are full, the runoff goes through yards, along curb lines and into ponds for slower release to the major waterways. Sometimes ponding occurs on roadways during the most intense rainfall or until the downstream pipes can release the water slowly.

Each homeowner has private sump pumps, yard drains & swales that need just as much maintenance as the roadway systems do. Every homeowner should know how the stormwater flows across or through their property. It is best to check your sump pumps every year or so. Clean private pipes, swales and inlet.

If you notice a curb or parkway inlet that is covered with leaves, have your landscaper remove them or call the Village Hall and ask that Public Works maintain the public inlet. Efficient operation of the public system will help prepare for the next intense rainfall.
If you would like to read more information about stormwater check out the Village website under Storm & Sanitary Sewers.

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