Water Detention Analysis using GIS


The Village of Oak Brook and the local Butler School District have
been diligently working over the past few months to determine the
feasibility of adding a new school on Oak Brook Sports Core property.
In order to determine whether or not it would be possible, there was a
considerable amount of analysis pertaining to the amount of available
property, ease of access, available detention, and determining the
general layout of the actual school grounds. The majority of the
preliminary analysis was done in house between Village Engineers and GIS
staff in order to keep cost down before entering the actual planning
phase. As a result there were multitudes of general site layout maps
generated. But as the planning process moved further along, the
required maps and statistics became more advanced because the property
was determined feasible for development. One of the final phases of
analysis that was done internally, prior to the hiring of an
architecture company, was the determination of required detention for
new development.

At this point in the project a general site plan had been proposed,
which included the calculation for approximate impervious surface area.
By taking the calculation of impervious surface area, Village Engineers
and GIS staff were able to determine the amount of detention area that
will be required for new development, based off of the elevation
statistics from an already existing detention area. Once the
approximate required detention area was determined, the GIS specialist
was able to use lidar elevation data to determine an already existing
area, which would require the minimum amount of earth being moved to
support the required detention. As shown in the image, the blue area is
the required detention area, which is surrounded by a red line
representing the total amount of area including the surrounding
retention burm. By using GIS we were able to complete this analysis in
less than two hours at the cost of day to day staffing. Had a
consultant been used, it would have required them to spend extended time
in the field, which would then require additional time to process the
data and development maps and statistics.