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Environmental Indicators
The environmental indicators reported here measure the impacts to natural conditions that are estimated to result from each scenario. Compare the results in the table below. There are significant differences in acres of open space, natural buffers along water bodies, and impervious surfaces, as well as differences in the estimated water consumption and water quality impacts from each scenario. The total length of docks and of paths also vary dramatically; they are included as environmental indicators for their potential impacts to marsh shading and impervious surfaces, respectively.
For an example of existing developments that make environmental concerns their first design priority, view this article on
conservation subdivisions in northeast Georgia.
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Site Tip
Each indicator name in the table is linked to a page of additional information and resources for learning more about that specific topic.
View the Indicator Methods section for more information on specific indicator assumptions and calculations.
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Open
Space
Percent of Site
Total Acres
Natural acres
Managed acres
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15%
85 (0.09 per DU)*
28
57
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71%
469 (0.65 per DU)*
432
37
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67%
445 (0.47 per DU)*
403
42
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Amount of
land left undeveloped (natural) or as parks (managed) in each
scenarios. |
Vegetated
Buffer
Acres required by Georgia law
Scenario acres within 25'
Scenario acres within 100'
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**21
**0
**0
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14
14
54
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14
13
44
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Georgia law
requires a 25' buffer area adjacent to state waters. Results shown
are the total buffer acres needed for the project site for compliance
with this law, versus actual scenario acres left as natural open
space within 25' of waters or wetlands, and scenario acres left
as natural open space within 100' of these areas.** |
Docks
Total dock length (feet)
Total dock area (feet2)
(For number of docks per dwelling unit, see Social
Indicators)
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43,721
262,326
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1,013
6,078
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2,086
12,518
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Total linear
feet of all docks in each scenario and total area covered by docks. |
Paths,
Trails, and Sidewalks
Total (linear feet)
Impervious
Pervious
(See cost per dwelling unit in Economic
Indicators)
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32,159
32,159
0
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78,846
26,946
51,900
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127,134
78,859
48,275
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Total
length of trails found in each scenario with the total broken
into total pervious and impervious lengths |
Water Consumption
Estimated total gallons/day
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358,926
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231,584
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287,765
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Estimates
water consumption totals for residential and park parcels in the
scenarios based on national and local averages |
Impervious Surface
Percentage (of total site)
Total Acres
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26 %
169
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14%
95
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18 %
119
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Amount of
impervious surface measured in each scenario based on literature
estimates of impervious cover by land use type |
Pollutant Runoff***
Change in total runoff volume to surrounding waters
Change in total nitrogen
Change in total phosphorus
Change in total suspended solids
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53.13 %
153.32 %
640.07 %
61.16 %
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28.28 %
84.46 %
297.79 %
43.31 %
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42.39 %
114.39 %
357.35 %
68.86 %
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Calculated
in the water quality module of EPA's Smart Growth Index software.
Results are displayed as the change between the amount of runoff
from the undeveloped site (baseline) and the amount of runoff
from the site if developed as depicted in each scenario. |
*The open space indicator is also reported relative to the total
number of dwelling units (DU) in each scenario. More information
on reporting results per dwelling unit is available in the Scenario
Dwelling Units section. |
**The conventional scenario has more required vegetated buffer
acres because of the addition of manmade lakes. This scenario
shows zero actual acres because this indicator measures natural
vegetated acres in the buffer zone, that is, parcel area designated
as natural open space. Unlike in the conservation and new urbanist
scenarios, residential lots in the conventional scenario extend
to the edge of the marsh. |
***Pollutant runoff is reported as the percent change from baseline. |
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