By utilizing the tax parcel database, each tax record was assigned to an NSA using GIS. Each tax
record was analyzed for residential use and this number was used as a proxy for the total number
of residential units.
Each noxious facility was buffered by ¼ mile. The residential parcels that fell within the buffer
boundaries were used to calculate the number of residential units near noxious facilities. The
number of residential units near noxious facilities was divided by the total number of residential
units to get the percentage of residents near noxious facilities for each NSA.
Sources: U.S. Environmental Protection Agency Air Facility System, 2013.
Information Technology, Chesapeake, 2013.
Real Estate Assessor, Chesapeake, 2012.
Drainage Score
– A score that represents the how well an NSA can handle storm water runoff
based on existing infrastructure and drainage conditions.
The percentage of each NSA with poor drainage was calculated using a digitized soil database.
Any soil ranked poorly or very poorly drained was considered an area with poor drainage. The
area of an NSA with poorly drained soiled was divided by the entire area of the NSA to obtain
the percentage of an NSA with poorly drained soil.
The percentage of each NSA reporting storm water problems was calculated. The number of
reported storm water problems in 2012 was summarized for each NSA. This summarized value
was divided by the number of single family residential parcels.
The percentage of each NSA with infrastructure greater than 50 years old was calculated. The
residential area older than 50 years old was divided by the total area residential area to obtain the
percentage of residential areas in the NSA older than 50 years.
The calculated values were multiplied to obtain the drainage score and were categorized below:
Average – 0 .0 - 0.15
Low – 0.15 – 0.93
Sources: Public Works, Chesapeake, 2012.
NRCS, U.S. Department of Agriculture, 2013.
November 2014
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