When in rains, what happens to the rainwater? The development of the
modern city often results in neglecting the effects of storm water on our
environment. With ever increasing
construction of impermeable surfaces such as roads, buildings and parking lots,
we limit the areas where storm water can penetrate the earth’s surface to be
recycled back into the ground. This reduced amount of
infiltrating water can lower ground water levels, which in turn can stress on downstream
environments, which depend on steadier flows of water. Storm drains help
control the volume of water left on the surface but seldom separate potentially
harmful pollutants that rainwater may have picked up off roadways and other infrastructure.
Did you know that approximately 70% of all storm drains lead directly
to open waterways, without treatment; and that 46% of all impaired rivers and
lakes in the U.S. are polluted due to uncontrolled storm water runoff?
As part of the LEED
initiative, this property is taking action in protecting the quality of U.S.
waterways by reducing the discharge of sediment, oil and chemicals into storm
drains, surface water and groundwater. Infiltration basins are one way of
offsetting these environmental impacts.
An
infiltration basin is a facility constructed within highly permeable soils that
provides temporary storage of storm water runoff. An infiltration basin does
not normally have a structural outlet to discharge runoff. Instead, outflow from
an infiltration basin is percolated through the surrounding soil. Infiltration
basins are used to remove pollutants and to infiltrate storm water back into
the ground. Such infiltration also helps to reduce increases in both the peak
rate and total volume of runoff caused by land development. Pollutant removal
is achieved through filtration of the runoff through the soil as well as
biological and chemical activity within the soil. In order to ensure proper
percolation in the 5 infiltration basins stationed on this property, both K4
and K5 sands (see sample materials below) are laid in the beds of these basins.
These materials are highly permeable and can intercept silt, sediment, and
debris that could otherwise clog the top layer of the soil below the basin. The
sand layer will also facilitate silt, sediment, and debris removal from the
basin and can be readily restored following removal operations.
