2023 Freetown DAT Report - Flipbook - Page 47
Freetown DAT
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choice think about changing their travel mode.
Just as the least expensive way to transport people is
to reduce the need for motorized transport, the least
expensive way to reduce trash is to reduce the need for
generation of materials fthat require disposal. Although
trash of all kinds is discarded, the nature of plastic
bottles (primarily their ability to float and propensity to
jam and clog waterways) makes them a greater risk than
other forms of trash. An inspection of clogs removed
from stormwater channels show that a majority of the
debris by volume, especially the floating debris, are
plastic bottles.
Source reduction by providing alternatives to plastic
bottles can be cost effective. The Freetown City Council
City Hall, for example, utilizes both disposal plastic
bottles and large (approximately 20 liter) reusable water
bottles that result in no trash.
Catching rainwater from roofs to fill cisterns both
provides local water supplies and has a small effect
on stormwater runoff. During August alone, Freetown
receives approximately 770 liters of rain fall per square
meter, with approximately 1,500 liters of rainfall/square
feet annually. Upscaling to the kind of large underground
cistern possible in a new building (such as the Annie
Walsh Cable Car stop), can reduce localized flooding
challenges. Underground cisterns, however, are far more
expensive, subject to local site conditions, and require a
pump to access that water.
The most effective stormwater catchment systems are
those that catch water at the height of a watershed,
where there may be more available land for ground
infiltration systems, larger rain capture and storage
opportunities, and the ability to slow water releases
before they move through stormwater conveyance
systems. For example, a future cable car site at Fourah
Bay College could most cost effectively catch and store
rainwater.
Trash in stormwater sewers creates local flooding and impedes pedestrian flows. A large portion, often a majority, of
these clogs are made up of plastic bottles.
Catching rainwater provides water supplies and slightly
reduces stormwater runoff.
