Part 4: Prefurbia, Landscaping, and Pad Shaping - By Rick
Harrison - Dec 01, 2010 New forms of landscaping can help reduce
the environmental impacts of land development. A site in its
natural condition absorbs rain water. Streets, driveways, walks,
and rooftops do not. Thus, one acre of natural ground might have
15 percent runoff while an acre of "improved" land might
experience 95 percent runoff. This is why developed land vs.
natural terrain increases runoff volumes. In the first article
in this series, I introduced the concept of an
Environmental/Economic Density (ED) Ratio, which measures design
efficiency. Past comparisons of ED Ratios included buildings,
but these do not tell the entire story because buildings likely
will be the same size. For the true gains in efficiency, I
compute ED without the buildings. For example, the original
single family plan used in an earlier example showed an ED Ratio
of 42 percent and a 37.4 percent ED using a Prefurbia plan.
Without the buildings, the ratio of the origina