GIS Contributes to Current Storm Water Study

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The April 18th flooding event hit northern Illinois rather hard, and
the Village of Lincolnwood was no exception. Many flooded basements
resulting from backed up sewers and contributed to many headaches
amongst the village’s residents. An existing storm water study was
already being conducted by the village, so it was decided to gather data
during this historic flooding event to help solidify the importance of
implementing this plan to village officials at the next village board
meeting. The data that was gathered was provided to GIS, where maps were
then created for use during the future storm water study presentation.

The data that was gathered for this study are known as freeboard
measurements. A freeboard measurement is the difference in elevation
between the top of the water level inside a manhole and the actual
elevation of the manhole where it sits at street grade. During the
morning of the flood, Public Works employees went to various locations
around the village, lifted up manholes, and recorded the freeboard
measurement. Some manholes were measured multiple times throughout the
morning and the lowest measurement would be used. Any freeboard
measurement that was four feet or less was considered a sewer failure.
Water can backup into basements and flood streets when it gets into this
range. Areas that contained these ranges seemed to support the existing
storm water study. This helps support the village’s conclusion that
these areas cannot withstand large storms of short durations. Without
using GIS, the data gathered from this flood might not be so clearly
understood on how it relates to the current storm water study and how
the flooding could be improved in the future if the findings from this
study are implemented.