Peeling back the Pavement - POLIS Water Sustainability Project

Key messages
➤ In the natural environment, rainfall is absorbed by the landscape; it nourishes
plants and recharges groundwater. In Canada’s cities however, hard surfaces like
asphalt and concrete do not absorb water. Rain and snowmelt become stormwater
runoff, creating a threat that must be managed.
➤ Flooded streets and basements, polluted beaches, degraded urban streams,
ruined aquatic habitat, dead fish, stressed aquifers, and expensive drainage
infrastructure that demands constant (and increasingly costly) maintenance
are evidence that the current approach to managing stormwater runoff is not a
sustainable long-term option, financially or environmentally.
➤ Rethinking the way we deal with rain and snow in our urban areas means replacing
the conventional pipe-and-convey approach, which moves water off the land as
quickly as possible to far from where it initially fell. Instead, we need an approach
that recognizes rainwater as a valuable resource and seeks to keep it where it falls
to support natural systems and provide a viable decentralized source of water.
➤ In a “Rainwater City” the natural water cycle is protected, runoff volume
is dramatically reduced, and runoff quality is improved when expanding and
retrofitting communities. Urban fish streams are restored and sewage overflows
are reduced.
➤ Incorporating green infrastructure at
the earliest stages of development is a
critical starting point and is generally less
expensive than larger-scale conventional
stormwater controls. Retrofitting existing
neighourhoods can also be cost effective.
Both approaches can enhance recreational
opportunities, green space, and urban
aesthetics.
➤ One of the greatest challenges to
reinventing rainwater management
is the fragmented and disconnected
responsibility for fresh water across
and within jurisdictions in a watershed.
Creating robust solutions requires
addressing issues of governance and
decision making.
➤ Transitioning from managing stormwater
to managing rainfall is possible and
many communities in Canada and around
the world are already leading the way.
Three design
principles are
crucial for moving
from a stormwater
paradigm to a
rainwater paradigm
in our urban
communities:
1. Reduce the amount of
impermeable surfaces by
changing the way we build and
retrofit our communities
2. Use rain as a resource and as a
viable decentralized source of
water for non-potable needs
Integrate decision making
3. on a
watershed scale