Case studies - Living Roofs in Integrated Urban Water Systems - page 158

Rain Rain

Extensive
living roof

Extensive living roof

HEADWATERS
APARTMENTS

Permeable
paving

Permeable
paving

Swale

SENIORS' RESIDENCE

Swale Swale

Groundwater recharge

LEGEND

Rainwater overlow Groundwater recharge

(swales), which are fed through a culvert to be further managed and mitigated
by a large rain garden, a larger-scale design intervention.
As an outcome of the project, increased neighborhood density involved the
provision of 170 units of a variety of new, multi-family, market-housing typolo-
gies. Meanwhile, the project has reduced the impermeable surface area of the
site from 84 percent to 55 percent, as compared to the site's pre- development
state, and restored riparian wetland habitat, which improves runoff quality, and
decreases its quantity, speed and temperature, not only on the site but also
further downstream.

Figure 5.5
Tryon Creek stormwater
runoff system diagram

5.2.5.2 Key living roof design features
1 PROCESS
A major highlight of the project was the daylighting of the culverted Tryon Creek.
This concept was championed by the developer of the site, Jim Wrinkler (Craig
2007). The Headwaters at Tryon Creek is also a prime example of a successful
public/private partnership, because the creek daylighting was initiated by the
developer, who then worked closely with the City of Portland to plan around the
contextual, inancial and logistical constraints of achieving this task (Craig 2007).
The support from the owners of the neighboring ofice building and apartment
block on two adjacent sites (via relocation of their driveways to optimize the size
of the creek, but with no loss of parking units to either building) is a testament
to the idea that decentralized, neighborhood scale improvements to stormwater
management infrastructure are possible (Liptan et al. 2010). The City of Portland,
many public organizations and bureaus, including the Bureau of Environmental
Services (BES), were all heavily involved throughout the planning, funding and
construction process of the development. The BES now manages the public areas
of the site, including the streets and the rain garden to west of the project.

2 KEy CommUNITy BENEFITS
The greatest triumph of the Tryon Creek Headwaters project lies in its holistic
value, rather than isolated design interventions. It is an example where living