Parking lot newly resurfaced. Asphalt surface allows for zero infiltration of rain.
Last year the city announced with some fanfare the creation of green standards for parking lots. These standards give guidelines for building parking lots that will reduce their impact on the environment. Current construction methods are simple and cheap but add to a host of environmental problems. Black asphalt bakes in the sun. The cumulative effect of all the parking lots in the city along with other urban structures increases the urban heat island effect. When rain hits an asphalt surface, it heats up and quickly runs off into the nearest sewer. This warm water runoff in downtown Toronto is quickly routed toward watercourses such as the Don River. The flush of warm water along with all the grit, oil, and other pollutants it picks up along the way is the major cause of habitat degradation in our river systems.
The green standards seek to reduce these effects with a number of design changes. Foremost is the inclusion of permeable paving surfaces. This type of surface allows for infiltration of rain water into the underlying soil. Another consideration is to break up the expanse of asphalt by planting trees within the parking lot. Additionally swales can be added to capture runoff from the surface before it hits the sewers.
All this sounds great but it has apparently fallen on deaf ears when it comes to actually applying these methods. This past winter a parking lot in Stan Wadlow Park at the edge of Taylor-Massey Creek was resurfaced. The parking lot was completely resurfaced with asphalt. Only one small island around a hydro pole was left for planting. On the south side of the parking lot a swale was dug but this will have next to no effect because the asphalt surface has been graded to slope away from it toward the middle where there are two storm drains. This means that less than 1% of the total parking lot runoff will flow into the swale.
Storm drains in centre of parking area. Asphalt is sloped down toward them which collects all the runoff.
Swales are meant to trap runoff but this one will capture none. Curb stones prevent most runoff reaching the swale and the asphalt is sloped away from it.
So, it seems that on the surface the city has tried to apply the new standards but the application here is paper thin. The city needs to set a higher standard when redesigning its own parking lots. How do they expect private parking lot builders to do better when they fail so miserably?
One small area left open. Since it's next to a hydro pole there won't be any shade trees, just decorative shrubs.