Using GIS to Develop Lot Coverage Ratio Ordinances

Blog_Using_GIS_to_Develop_Lot_Coverage_Ratio_Ordinances.png

The City of Highland Park is an established older community that is
experiencing redevelopment of smaller structures into larger structures.
The larger structures and their supporting infrastructure create a
large impervious footprint. These larger impervious areas create larger
amounts of storm water runoff that can overwhelm existing storm drainage
infrastructure.

The city wants properties to absorb as much of their own impervious
runoff as possible. Therefore, they were looking to create an ordinance
that encouraged property owners to leave a percentage of their lot as
pervious surface. The ordinance also creates a fee applied to owners
that exceed this impervious percentage. The collected fees go directly
to storm sewer improvements

The Planning Division of Community Development contacted the GIS
Office for assistance with analysis for the ordinances. The goal was to
rank the lots within residential zoning districts by their percentage of
impervious surface. This allows the Planners to develop an ordinance
that reflects the varying density of residential development per
neighborhood and does not punish residents living in more densely
developed neighborhoods

The GIS Office converted county parcel data into a lot layer by
combining parcels with the same address. Intersecting overlaying man
made data layers such as buildings and driveways created the impervious
areas for each lot. Dividing impervious areas by the total are area of
the lot created the percent impervious values for each lot. Lastly, the
lots received a zoning district based on their underlying zoning
district. Then querying the lots in each zoning district provides
percent impervious value ranges for each zoning district.

GIS provided information that allowed the Planner to create an
ordinance that fairly applied fees only to overbuilt properties within
each neighborhood. Without GIS, the Planners could not create the
ordinance or would have used a time intensive estimation process. The
ordinance ensures owners that overdevelop their lots are assessed a fee
for the burden they place on existing storm sewers.

Using GIS to Develop Lot Coverage Ratio Ordinances

Blog_Using_GIS_to_Develop_Lot_Coverage_Ratio_Ordinances.png

The City of Highland Park is an established older community that is
experiencing redevelopment of smaller structures into larger structures.
The larger structures and their supporting infrastructure create a
large impervious footprint. These larger impervious areas create larger
amounts of storm water runoff that can overwhelm existing storm drainage
infrastructure.

The city wants properties to absorb as much of their own impervious
runoff as possible. Therefore, they were looking to create an ordinance
that encouraged property owners to leave a percentage of their lot as
pervious surface. The ordinance also creates a fee applied to owners
that exceed this impervious percentage. The collected fees go directly
to storm sewer improvements

The Planning Division of Community Development contacted the GIS
Office for assistance with analysis for the ordinances. The goal was to
rank the lots within residential zoning districts by their percentage of
impervious surface. This allows the Planners to develop an ordinance
that reflects the varying density of residential development per
neighborhood and does not punish residents living in more densely
developed neighborhoods

The GIS Office converted county parcel data into a lot layer by
combining parcels with the same address. Intersecting overlaying man
made data layers such as buildings and driveways created the impervious
areas for each lot. Dividing impervious areas by the total are area of
the lot created the percent impervious values for each lot. Lastly, the
lots received a zoning district based on their underlying zoning
district. Then querying the lots in each zoning district provides
percent impervious value ranges for each zoning district.

GIS provided information that allowed the Planner to create an
ordinance that fairly applied fees only to overbuilt properties within
each neighborhood. Without GIS, the Planners could not create the
ordinance or would have used a time intensive estimation process. The
ordinance ensures owners that overdevelop their lots are assessed a fee
for the burden they place on existing storm sewers.