Impervious Surface Analysis


The Village of Oak Brook has ordinances in place that require a
certain amount of area on each property designated for storm water
drainage. Typically the Village requires a certain percentage of a
given property to be a pervious surface in an effort to reduce overland
flow of storm water. If the property is not able to meet this level of
pervious surface, then they are often instructed to create detention on
the property to hold excess water in the event of heavy rain. When
existing or new developments want to create or expand their impervious
surfaces, the Village must verify that they are doing so within the set
regulations. Typically these approvals are done by reviewing the
proposed building plans, or as-built. But recently there was a
discrepancy brought up by a property owner over the proposed addition of
new parking on his neighboring property. In order to give the
complainant proof of his neighbor meeting the impervious surface
regulations, GIS was brought in to analyze the total area and provide a
map and statistics displaying the results of the analysis.

By using the planimetric data that the Village acquired in 2009, the
GIS specialist was able to get measurements of all pervious and
impervious surfaces that fall within the property. These surfaces
included: parking, sidewalks, green areas, and the building itself.
Once these statistics were gathered, the planned parking improvements
were added to the current statistics, resulting in the total proposed
impervious surface for the given property. Once these numbers were
reviewed by Village engineers, it was confirmed that the property met
the regulations set by the Village and construction could move forward.
Without the use of GIS, valuable time would have been spent in the
field gathering these measurements and analyzing them in a non-spatial
format. GIS allowed for the quick and accurate gathering of all
information, with the added benefit of graphic representations to
support the findings.