Purpose:

The scope of this study is limited to all new and existing lots that fall under the following classifications:
(a) municipally-owned surface parking lots and multi-storied car park facilities that charge fees; and
(b) privately-owned surface parking lots used in shopping malls and other retail developments (that do not charge fees).

Recommendations:

Furthermore, it is recommended that the Implementation Plan below be used as a guideline for effective implementation of the above recommendations.
 

Implementation Plan:

Financial Implications and Impact Statement:

(1) greenery (e.g. shrubs, trees, vines) and the necessary supporting infrastructure (e.g. containers, pergolas, etc.).  It is expected that these costs will be greater than those currently spent on greening in parking lots as this paper recommends increasing greenery.  The average annual cost of planting and maintaining an urban ‘city’ tree is approximately $200 (Torrie Smith Associates 1997: 8) and it is estimated that each m2 of green roof costs about 50 pounds (or $120) to construct (Johnston & Newton 1993: 72).

(2) porous paving materials, infiltration systems, and rainwater collection systems.  It is expected that these costs will be significantly higher than those currently spent on paving asphalt. The cost of constructing a parking space using asphalt is estimated to be between $5,000 and $20,000 (the low end of which applies to surface lots and the high end of which applies to underground lots) (personal comm. Mehr 1998).  The average cost of porous materials, however, is almost 40% greater than asphalt (City of Toronto 1993a).  Costs associated with infiltration systems are expected to be quite high while those associated with rainwater collection systems are not expected to be very significant, the purchase cost of rain barrels being about $50-$350 (City of Toronto 1998).

Financial implications are also expected to arise if the proposed greening initiatives result in a reduction in the number of parking spaces available (which then causes a subsequent loss in revenues).  As will be noted in the section on Proposals for Landscaping, however, many of the initiatives do not require a reduction in parking space numbers.  Furthermore, this is only applicable to municipally-owned lots in the study.

Where financial losses are incurred as a result of implementing the proposed initiatives, however, it is expected that they will be offset by their many positive environmental and social impacts.  A summary benefit-cost ratio incorporating all the realized benefits from trees as well as all costs associated with their implementation and maintenance has been developed by McPherson (1994) for Chicago street trees.  In this study, McPherson (1994: 131) concluded that there was a benefit-cost ratio of 2.83 meaning that the value of projected benefits is nearly three times the value of projected costs.  The benefits are all those identified in this paper (under the Background section) and costs pertain to planting, pruning, removal, waste disposal, infrastructure repair, litigation and liability, inspection and program administration (see Appendix 2.1).

Funding Sources:

(2) For all new and existing lots it is proposed that property tax relief for parking lots practising greening be built into the tax rating system.  This provides a form of economic incentive for parking lots that don’t charge fees (e.g. shopping malls) to adopt the proposed initiatives.  It also helps mitigate the financial implications discussed above.  Property tax relief may be brought about by the application of the Fair Municipal Finance Act and within that, the Range of Fairness policy (Ministry of Finance 1997, 1998; personal comm. C. Bode, 1998).  This policy provides municipalities with the flexibility to distribute taxes more fairly among different classes of property by permitting the city to introduce new property classes (Ministry of Finance 1998; personal comm. C. Bode, 1998) (see Appendix 3.1).  The accompanying tax rates with these new classes would reflect the amount of greenery on the parking lot.  This is completely under the purview of the municipality and does not require provincial approval (personal comm. C. Bode, 1998).  Examples of possible new classes include: (a) parking lots with more than 10% green space; (b) parking lots with more than 20% green space; and (c) parking lots with more than 30% green space.  Higher percentages of green area would of course correspond with overall lower tax rates.  The difference in property taxes as a result of new class ratings could then be used to cover planting and maintenance expenses.  This incentive is particularly important for those existing parking lots that do not have to comply with the recommendations and guidelines that fall under Site Plan Approval (City of Toronto 1996b, 1997).

Background:

1. Context of the Study

The context for examining the use of porous paving materials comes from certain actions adopted by the City of Toronto in the past.  In October of 1992, City Council adopted Clause 38 of the City Services Committee Report No. 15 (contained in Executive Committee Report No. 28 on the city’s Sewer System Master Plan), in which certain paved areas of the city (including parking lots) were demarcated as potential spots for the implementation of porous paving materials.  Further to that, the Commissioner of Public Works and the Environment submitted a report in 1993 on the use of porous materials for surface paving.  In that report, it was suggested that developers be encouraged to use decorative paving stones on walkways, roadways, driveways and parking areas that allow for infiltration (e.g. ecostone, turf stone) (personal comm. G. Horgan, 1998).  Then, in 1996, the City of Toronto established a Stormwater Group.  Its most recent project, “Demonstration of Non-Structural Stormwater Management Practices” addresses the importance of intercepting rainwater before it reaches paved areas, the use of porous pavements, the importance of building rooftop gardens and installing rain barrels, and other options for effective stormwater management (Aquafor Beech Ltd. et al 1998).

While these previous studies provide a context for assessing greening and stormwater management initiatives, parking lots provide a focus for examining how such initiatives could be adopted and implemented.  Parking lots were chosen because:
(1) the asphalt typically used in paving contributes to the urban heat island effect (see Appendix 4.1) while increasing the amount of stormwater runoff due to its non-permeable character (Litman 1995; Pollution Probe 1991);
(2) they take up space which could otherwise be used for more desirable, or optimal uses, such as public space for communities (Litman 1995)⁷; and
(3) they typically have very low aesthetic value which is particularly important for lots situated in residential communities.

Conversely, increased plantings will contribute to expanding the urban forest in Toronto.  The urban forest refers to the canopy coverage in the city and includes all kinds of trees found within a city, including park, street, yard, and residential trees (Hibberd 1989).  The old city of Toronto’s urban forest has a canopy coverage of 20-25% overall (Hough et al 1997) but decreases to only about 8% in commercial and mixed-use areas (Torrie Smith Associates 1997: 20).
 

2. Benefits of Greenery and Stormwater Management

a) Improved ambient air quality
Trees and the leaves of climbing plants are able to absorb air-borne dust particles and other particulate matter (Johnston & Newton 1993: 10; City of Seattle 1992).  Streets with trees have been found to contain only 10-15% of the dust found on similar streets without trees (Kuhn 1993).  In order to fully achieve this benefit, however, it is important to try and have as many clusters of trees as possible as it is the density of the canopy coverage that affects the amount of air filtered (Sampson et al 1992: 60).

b) CO2 sequestration and storage
Trees and other plant life are able to effectively store and sequester carbon.  The rate at which a tree captures carbon dioxide and converts it into carbon to form the tree mass is called the rate of carbon sequestration (Torrie Smith Associates 1997: 3).  For every new tonne (t) of wood that grows, about 1.47 t of CO2 are removed from the air and about 1.07 t of O2 are produced (OPA 1998: 11).  A detailed study of street trees in Toronto was recently conducted in which counts were made according to three size classes (based on tree diameter).  The results of this study show that an average of 37 kg of carbon is sequestered per year (or 136 kg CO2/yr stored) by each street tree (Torrie Smith Associates 1997: 6)⁸.  When compared against the average cost of planting and maintaining an urban street tree (estimated to be $200), it means that the cost per tonne of carbon sequestered is $280 for small trees, $182 for medium trees, and $30 for every large tree planted (Torrie Smith Associates 1997: 8).  Clearly, large trees provide the greatest return on the planting investment.

c) Energy Savings
It is critical to note, however, that sequestration is only a temporary means for reducing CO2.  When decomposition occurs, carbon is released again.  Therefore, it is important to think of how trees can incur carbon avoidance.  Strategic tree planting that accounts for solar heat action in the summer and wind patterns in the winter can be an effective means for decreasing cooling and heating needs.  More specifically, deciduous greenery (e.g. deciduous trees, trumpet vine, Russian Vine, and clematis) that is planted on the south and east-facing borders of lots provide shade and evaporative cooling while evergreens (and ivy in particular) planted on the north and west-facing borders block winter winds (Johnston & Newton 1993; Sampson et al 1992: 57; Parker 1989: 2).

In the summer, the urban heat island effect can cause temperatures to increase substantially in the downtown core.  Shading from strategically-placed trees can reduce the amount of pavement subjected to large temperature increases.  Furthermore, a single large tree can transpire 450 litres of moisture per day which, when multiplied by a significant number of trees, can incur a significant reduction in temperature (Hough et al 1997).  This is especially relevant when considering that for every degree of temperature increase, the power use from air conditioning is estimated to rise between 1 and 2 % (Healthy City Office 1998: 34).  Similarly, strategic plantings that provide protection from winter winds can decrease heating needs of buildings that are adjacent to or part of a parking lot.

d) Other benefits
Plant life beautifies an area and can add significantly to property values of both residential and business communities (Johnston & Newton 1993).  Plant life also contributes to psychological and physical well-being due to its aesthetic appeal.  Furthermore, significant areas of greenery, such as those potentially to be found on rooftops, can provide habitats for native plants and birds, provide more outdoor space for residents, and offer opportunities for urban food production.  In addition, the use of rooftop greening can protect roofs from temperature extremes and ultra-violet light and thereby increase a roof’s life expectancy from 10 to at least 50 years (Johnston & Newton 1993: 49).

Benefits may also be achieved through the use of effective stormwater management techniques, notably porous paving materials that are lighter in colour as well as infiltration and rainwater collection systems.

a) Decreased stormwater runoff
When rainwater enters the sewer system after running off hard paved surfaces, the system becomes overloaded and forces untreated runoff to enter the lake (City of Toronto Public Works and the Environment 1993).  Due to the fact that porous paving materials allow for greater levels of water infiltration than asphalt, these can actually decrease the amount of stormwater passed through the system untreated.  Similarly, trees and rooftop greening on flat or sloped roofs can intercept and absorb storm water, thereby reducing runoff and acting as a filter for infiltrating water (Local Environs 1998: 1)⁹.

b) Decreased urban heat island effect
Although the aim of using porous paving materials is to aid in stormwater management, it can also aid in decreasing the urban heat island effect.  Non-porous asphalt surfaces can heat up to 60ºC (or 140ºF) under direct sunlight (Torrie Smith Associates 1997: 17).  Through the use of lighter-coloured surface materials which are also porous, however, some of this effect may be mitigated as porous materials store much less heat than asphalt (Torrie Smith Associates 1997).
 

3. Existing initiatives in Toronto

(2) Landscaping Manuals.  In 1997, the former city of Toronto produced the Urban Design Handbook (City of Toronto 1997a).  The handbook is a broad and general set of greening initiatives intended to complement more specific planting guidelines presented in the former city’s Streetscape Manual (City of Toronto 1997b), also released in 1997 (personal comm. R. Patrella, L. DeSorcy, E. Horvath, 1998).  Landscaping on surface parking lots are specifically addressed in the Urban Design Handbook, section 3.6.  As with former official plans, however, both documents deal only with the issue of aesthetics that greening can provide in terms of providing fencing and other visual aids to improve the streetscape (personal comm. R. Stanley, 1998).  It is important to note that some other former municipalities do not have any such manuals for landscaping¹¹.

(3) Stormwater Demonstration Projects.  The Toronto Stormwater Group is currently involved in three stormwater demonstration projects: North Bloor West Village, Moore Park, and Garrison Creek (Aquafor Beech Limited et al., 1998; personal comm. K. Mercer, 1998).  These projects are investigating options for non-structural stormwater management options (e.g. planting trees, removing paved surfaces, using porous pavement, and installing rooftop gardens) on both public lands (parks, roadways, right of ways, and institution property) and private lands (residences).

(4) Existing Initiatives on Municipally-Owned Parking Lots.  On the 153 municipally-owned lots within the new City of Toronto, the Parking Authority provides greenery on some surface lots according to the policy in the Urban Design Handbook (1997)  and Streetscape Manual (1997) (personal comm. Nathoo 1998) .  In Figure 1 an example of such greening is shown.

Figure 1. Example of greenery on a municipally-owned surface lot in Toronto.

Figure 2. Example of a municipally-owned surface lot without greenery.

In this figure, one can see that cars are parked without any streetscape landscaping.  In fact, on this lot there was one lone tree and yet this lot is situated in a very residential setting.

This study has also examined municipally-owned car park facilities.  Currently, there are 4 joint ventures between the Parking Authority and private developers to develop rooftop greening on car park facility roofs and an additional 2 are now being negotiated (see Appendix 5.1).  Figure 3 illustrates what this rooftop greening looks like.

Figure 3.  Example of greening on municipally-owned car park rooftop.

The greenery is only 2 feet wide and runs only along the perimeter of one edge of the rooftop.  No municipal car parks have greenery on their balconies.  In addition, there are currently no municipally-owned lots with porous paving or rainwater collection systems (personal comm. Nathoo 1998)¹².

(5) Existing Initiatives on Privately-Owned Parking Lots.  It is difficult to determine what has been done thus far in regards to greening on privately-owned parking lots around shopping malls and grocery stores in the City of Toronto due to the lack of one single body overseeing the operation of such lots.  Moreover, the total number of privately-owned parking lots is undetermined (City Clerk, Licensing Authority, personal comm. 1998).  Nevertheless, an example of what would be considered a ‘good’ greening practice (relative to other lots in Toronto) can be found at Sherway Gardens Shopping Mall.  Sherway Gardens has a very big parking lot with 5,700 parking spaces and 750 trees (personal comm. R. Saker, 1998).  This means that there is one tree per every seven and a half parking spaces.  Most other parking lots, however, have much less greening than this parking lot as is seen by Figure 4.

Figure 4. Example of privately-owned surface lot at Yorkdale Shopping Mall.

Discussion:
This discussion will focus on proposals for landscaping on surface and car park lots as well as proposals for improved stormwater management techniques.

1. Proposals for Landscaping on Parking Lots

These objectives are fundamental to the planting strategies developed and presented below.  These strategies can be grouped into three sets of solutions.

(A) Optimum use of available space
There are three possibilities for optimizing available space:

(1) Using any space that is not sufficient for a parking spot for plantings. For example, there are many parking lots (both big and small) that are of irregular shape and that would therefore permit some planting to be done without the loss of any parking space (see Figure 5). This is very important for application in small parking lots that don’t have enough space for big planting projects.

Figure 5.  Using insufficient parking space for greening.

(2) Narrowing the vehicle aisles on parking lots (i.e. switching from two-way traffic to one-way traffic  and angled parking).  See Figure 6.

Figure 6. Using decreased aisle widths for greening.

For example, two-way traffic aisles are usually 6 to 6.5 m wide (McCluskey 1987).  By switching to angled parking (of 45o), aisles could be switched to only one-way traffic and reduced to about 3 m wide (see Figure 7).  This idea has been implemented in France where they commonly have one-way traffic circulation on parking lots and 45o angled parking and aisle widths average 2.57 m (McCluskey, 1987:203).  Where 90o angled parking (or non-angled parking) is used, the aisle width must increase to at least 3.62 m (ibid.).  By re-striping lots and changing their geo-metrics, lots can incorporate angled parking and smaller aisle widths and in so doing, can gain 5-10% more space which can then be used for landscaping (Keneipp and Van Dyke 1993).

 Figure 7. Different options for angled parking.

 Source: (McCluskey 1987: 201)

(3) Reducing the size of some parking spaces.  The standard size of a single parking space in Toronto is 5.9 x 2.6 m.  Some European cities, however, do use smaller-sized parking stalls.  For instance, in Britain the preferred parking space size for 90º angled parking is 5.5 x 2.4 m while the recommended minimum is 4.9 x 2.4m (McCluskey, 1987:198).  Recent studies have shown that the percentage of smaller cars sold yearly (in Europe and North America) began to increase dramatically in the 1980s and has since stabilized at about 52 percent of total vehicles sold each year (Keneipp and Van Dyke 1993: 81; see Appendix 6.1).  With car size reductions there are significant opportunities to decrease the dimension of the parking module (parking stall and vehicle aisle) (see Figure 8).

Figure 8. Parking Module

Source: (ULI & NPA 1993: 80)

While it is not possible to reduce all parking stalls within a lot, a small percentage could be depending on the users of the lot.  For example, a standard stand-alone lot could have 80% of their stalls standard size and 20% smaller than standard.  This initiative should follow on the use of angled parking as parking in smaller stalls is easier in this form (Kenneipp & Van Dyke 1993).

(B) How, Where and What to Plant
The second set of solutions promotes the following:

(1) Use of continuous tree pits.   Continuous pits are favoured over single tree pits as these allow for bigger soil volume and greater water and oxygen infiltration which is healthier for trees (City of Toronto 1997b; refer to Figure 6).  Such pits also save on space as one continuous pit for five trees takes less space than five single tree pits.  Detailed guidelines for tree planting in pits are presented in the Streetscape Manual (ibid).  For recommendations on planting and the use of different tree species see Appendix 7.1.

(2) Use of climbing plants.   These include ivy, vines, and climbing bittersweet and are efficient for the numerous benefits they provide in significantly smaller space than that used by trees.  These plants are commonly used in many German cities¹³.  They can be used on parking lots to form a green wall between two rows of cars or as a green ceiling over parked cars or pedestrian aisles on some kind of climbing frame (see Figure 9).

Figure 9. Use of climbing plants on surface lots.

Source: (McCluskey 1987: 126)

They can also be used on the walls of surrounding buildings or shopping-malls, including the walls of car parks.  Climbers support themselves by spiralling upwards around an object.  This object could be timber battens, trellis work, steel cables, concrete ballasts, plastic ropes, or even other living, woody material (Johnston & Newton 1993).  Plants which hold on with clinging roots or petioles (e.g. clematis) will also benefit from a grid of thin material to which they can attach themselves (see Figure 10).

Figure 10. Pedestrian Walkway.

Source: (Johnston & Newton 1993: 59)

(C) Optimal use of car park rooftops and balconies
The final set of landscaping initiatives deals specifically with rooftop and balcony greening on car park facilities and proposes:
(1) Use of climbing plants on balconies.  Many car park facilities have balconies on every level that are either fenced or completely open on the top half.  Such spots offer opportune places for implementing greenery such as climbing plants discussed above in Section b(2).  This would aid in creating an effect of a green wall (see Figure 11).

Figure 11.  Use of climbing plants on balconies.

Source: (Johnston & Newton 1993: 33)

(2) Use of gardens and greenery on rooftops.  In Figure 12, one can see how rooftops can be optimally used for greening practices.

Figure 12. Example of rooftop greening.

Source: (Johnston & Newton 1993: 45).

While greening initiatives on rooftops is a relatively new architectural phenomenon in North America, many European cities have been developing this form of greening for years.  More recently, architects and city planners in various world cities have proposed to expand this idea to include greening on the roofs of car parks¹⁴.  The work that has been carried out on rooftops thus far suggest two main types of greening initiatives: extensive and intensive.
(a) Extensive greening, or eco-roofs, are not meant to be trodden on and should not, therefore, be seen as community amenity areas.  The recommended growing medium (i.e. soil) is about 10-15 cm and can therefore support only low vegetation (Johnston & Newton 1993: 58; Landscape Architecture 1998).  Due to these rather simplistic design features, however, this type of greening does not usually require irrigation.  See Figure 13.

Figure 13. Extensive rooftop greening.

Elements shown in this diagram include a spruce rafter, A; a steel connector, B; an I-section, C; a recycled fibreboard roofing sheet, D; a polyethylene vapor screen, E; perlite insulation, F; synthetic rubber to prevent rain and root penetration, G; a polypropylene drainage layer, H; substrate, I; a nylon anchorage net, J; grass mats, K; and a gutter, L.

Source: (Johnston & Newton 1993: 60).

(b) Intensive greening, as the name implies, is meant for more intensive use including pedestrian usage (as shown in Figure 12).  This kind of greening can support gardening but requires a growing medium of at least 100 cm and much more care and maintenance, including irrigation.  As noted earlier, this form of rooftop greening is more expensive than extensive greening.
See Appendix 8.

2. Proposals for Stormwater Management on Parking Lots

(1) Porous paving materials:
In Figure 14, examples of porous paving materials are shown.

Figure 14.  Different porous paving materials.

Source: (City of Toronto Public Works and the Environment 1993)

Due to the many benefits of porous pavement it is recommended that it should be used wherever possible (see Appendix 10.1).  Even though some case studies have presented very good evaluations of porous paving materials¹⁶, the best parking lot candidates for the use of porous paving are those that are not excessively used (i.e. in the case of very large lots those more peripheral zones that are only occasionally used by drivers).

In the development of plans for the use of porous pavement, the fact that people tend to park as close to their destination as possible was taken into consideration (McCluskey, 1989).  Using this as a starting point, it is proposed that surface treatment of paving materials correspond to the lots intensity of usage.  Figure 15 proposes such an idea for a large lot.  In this figure one can see three different zones of paving.

Figure 15. Proposal for zoning within a parking lot for porous paving materials.

Asphalt is used in the zone nearest to the destination point (e.g. a shopping mall entrance or parking lot exit); a combination of asphalt and porous materials is proposed for the middle zone; and in the third and most peripheral zone, porous material should be used.  Indeed, such zoning would be difficult to apply on small lots but should be done on those that are not too busy.

(2) Infiltration systems:
Porous paving materials should ideally incorporate infiltration systems too that filter out oil and grease likely to be run-off on surface parking lots during rain events. Soak-away pits and infiltration trenches are two methods for disposing of storm water run-off from paved areas, provided the soil conditions are suitable and the infiltrated stormwater does not impact on underground structures (such as basements and utilities) (City of Toronto City Services Committee, 1993).  Infiltration trenches are somewhat preferred to the soak-away pits, however, because of their larger storage capacity (personal comm., G. Horgan, 1998).  In addition, the Stormwater Group has been examining the potential for using storage ponds and constructed wetlands which aim to redress the hydrological imbalances resulting from urban development.  These structures store runoff and release it slowly to receiving water bodies. They restore water quality by removing contaminants before entering surface waters (Hough et al., 1997).  See Appendix 9 for diagrams of these structures.

(3) Rainwater collection systems:
Irrigation on rooftop gardens can be assisted by the use of stored rain water.  Methods for achieving this include the use of reservoirs, cisterns, soaker hoses, or the drainage layer itself.  Figure 16 provides an example of a rainwater barrel.

Figure 16.  Rain water barrel.

Source: (Metro Works Environmental Citizenship n.d.)

All of these store water and return it to the system when needed.  Alternatively, runoff can be directed to a subsurface reservoir to provide water to plants on an as-needed basis¹⁷.  Rainwater collection can be a very efficient way of reducing stormwater runoff (John van Nostrand Associates et al 1998; see Appendix 11).  Collected water can also be used for other purposes aside from those pertaining to the roof.  These uses include washing parking lot surfaces and buildings on lots (such as the mall complex).

3. Proposals for Implementing Landscaping and Stormwater Management Initiatives

a) Increasing greenery
For increasing the amount of greenery used on parking lots, however, SPA is least preferred because of its inherent limitations (as listed in Appendix 12.1).  Therefore, for implementing more greenery on parking lots in Toronto, zoning by-laws are considered to be more effective mechanisms.

By-laws
The purpose of by-laws is to regulate the use of land and the erection and location of buildings, parking lots, and other urban structures (Stonehouse 1998: 13).  Although zoning may not be preferred by developers because of the restrictions, inflexibility and occasional increased costs that it places on development (Stonehouse 1998: 14), from the perspective of increasing greenery in the city it may be very effective for these same reasons.  Therefore, this study proposes that:

(1) the City of Toronto adopt a new zoning by-law that requires lots to be at least 10% green and to be subject to landscaping initiatives described above.  This by-law would combine elements of the following two cases: Chicago’s Mandatory Landscape Ordinance and Atlanta’s Landscaping Ordinance.

(a) The former ordinance (or by-law) requires all new parking lots and existing lots that propose to undertake significant renovations to contain 10% green space (ICLEI n.d.: 2; personal comm. Hoeer 1998).  This ordinance does not specify exactly what form of greenery should be used nor where exactly it should be placed on a lot; it stipulates that part of the greening be used as screening around the perimeter of a lot.  It also promotes planting clusters of green space with continuous lines of soil and plantings.  Through site plans, developers must show that they have met these zoning requirements prior to obtaining their occupancy permit (personal comm. Hoeer 1998)¹⁸.
(b) Atlanta’s Landscaping Ordinance requires surface parking lots with 30 or more spaces to have landscaped strips along the lot’s perimeter as well as landscaped areas within the lot¹⁹.

It is proposed that this zoning by-law be applied to existing and new surface lots as well as existing car park facilities.  For the latter, greenery could be implemented on either or both the rooftops and car park balconies.

(2) the zoning by-law proposed in (1) also be applied to new car park facilities but that the percentage of green space be increased to at least 70% of the car park’s roof and balcony area (i.e. the car park’s outer shell).  The city of Chicago is currently working on revising its policies for rooftops of car park facilities.  In the spring of 1999, the Department of Zoning is hoping to pass either a new zoning by-law or make an amendment to the existing one discussed above, to enforce green rooftops on car park facilities, especially in residential areas with little green space (personal comm. Hoeer 1998).  The exact percentage that will be required to be greened is currently undetermined.  (See Appendix 12.2.)

(3) consideration be made of the following zoning by-laws.  These are:

(a) zoning for the minimum number of spaces to be provided at lots that are part of retail developments according to the development’s total square footage²⁰.  There are no such requirements applicable to the municipal lots in this study as stand-alone lots can provide however many spaces deemed necessary by the Parking Authority; and
(b) zoning for the standard parking space size of 2.6 X 5.9 meters as stipulated in the old City of Toronto’s Municipal Code, Chapter 248.  (This is considered standard size across all the former municipalities as well and is standard according to a typical large car.)

In order to effectively implement what is proposed in (1) and (2) above, these by-laws need to be assessed because they may conflict with the ability of developers to implement the study’s landscaping initiatives.  If deemed necessary, it is proposed that the city consider amending these two by-laws.  This would involve one or both of the following:

(a) either decreasing the minimum space requirements or changing the minimum to a maximum number of spaces that must be provided; and/or
(b) developing an additional standard for parking spaces that is smaller than the current standard.  Depending on their use, lots would then have to contain a certain percentage of spaces that meet with this new standard.

Despite the fact that one of this study’s objectives was to avoid a loss in the number of available parking spaces, some of the landscaping initiatives proposed may result in this effect.  While this hi-lights the importance of looking at the above zoning by-laws it also bears on automobile use reduction strategies (Apogee Research International Ltd. & Osborne Group 1995)²¹.

b) Increasing the use of stormwater management measures

(1) It is recommended that porous paving materials on surface lots be implemented through SPA.  In Toronto, it is not possible to implement porous paving materials everywhere due to the absence of the necessary soil and ground conditions which permit their use (personal comm. S. Grice 1998).  It is not advised to use zoning by-laws to enforce their implementation as zoning cannot adequately demarcate where such materials should be implemented and where they should not be.  That is, zoning cannot provide for the fact that some sites will simply not be able to undertake the implementation of porous paving materials.
(2) It is also proposed that, where possible, the SPA process should demand that infiltration systems below at-grade level as well as rainwater collection systems on rooftops be implemented on surface and car park lots that must undergo this approval process.

Conclusions:

Endnotes:

  ¹For the purposes of this study, greenery is considered a separate initiative from the stormwater management options looked at here.  It should be noted, however, that greenery itself plays a very important role in stormwater management as will be discussed in the Benefits section.

  ²Site plan approval will be described in further detail under Mechanisms for Implementation.

  ³Under SPA, a significant renovation is not clearly defined.  It does appear, however, that in order to be deemed significant, major changes to the lot in terms of access and exit points, parking facades or structures within the lot, must be proposed in order to count.

  ⁴At Sherway Gardens Mall, the owner received numerous complaints and questions from customers and nearby residents when several trees were removed (in order to be replaced by other plants) (personal comm. Saker 1998).

  ⁵Prices at surface lots and car parks were compared across municipally and privately-owned lots in Toronto.  Municipally-owned surface lots ranged between $.85 to $1.50 for each half hour; privately-owned surface lots ranged between $2.25 and $2.50. Municipally-owned car park lots are about $1.50 for each half hour whereas privately-owned surface lots are higher at about $2.25 per half hour.

  ⁶The basis for the Smog Report is the city’s 1988 plan to reduce CO2 by 20% by 2005 (Healthy City Office 1998: 5).  Further to this in 1997, city council adopted targets to reduce NOx and VOC emissions across the city by a minimum of 45% by 2005 (Healthy City Office 1998: 5)

  ⁷Compared to all other modes of transportation, the automobile requires the most space overall, including that taken up by the provision of parking space (Litman 1995: 3-4).

  ⁸Broken down by size class, large tree species sequester an average of 47 kg/year (or 172 kg of CO2 stored per year); medium species sequester an average of 22 kg/year (or 81 kg of CO2 stored per year); and small species sequester an average of 15 kg/year (or 55 kg of CO2 stored per year) (Torrie Smith Associates 1997: 6, 20).

  ⁹Runoff mitigation through the use of green roofs has proven to be quite substantial.  In Switzerland, extensive green roofs retain between 70 and 100% of summer rain (White 1998).

  ¹⁰Section 3.18 states that Council is required to approve surface lots on the basis that they undertake to “ameliorate the impact of at grade surface parking lots by encouraging landscaping fencing and other appropriate treatments for surface parking lots in order to improve the appearance of the lots and to contribute to the visual continuity of the street edge…” (from City of Toronto Urban Development Services 1997: 52).

  ¹¹Conversations with Clerks for East York and Etobicoke found that these municipalities have limited landscaping requirements.  In East York there are no written landscaping requirements and in Etobicoke it is only stipulated that shopping malls should have a 1.5 metre area of landscaping around their perimeter.

  ¹²The Parking Authority is a financially self-sustaining agency of the City of Toronto whose mandate is to “exercise all powers, rights, authorities and privileges with respect to the construction, maintenance, operation and management of parking facilities within the City of Toronto…” (Parking Authority 1997: 1).  While an agency of the city with a Board of Directors composed of 2 Councillors and 5 citizens, it is subject to the same development and zoning regulations as private developers.

  ¹³In 1983, the Kassel City Corporation in Germany launched a campaign encouraging communities (with their financial and information support) to take on the increased planting of climbing plants (Johnston and Newton, 1993).

  ¹⁴This is the case in Melbourne where developers and architects are currently working on developing rooftop gardens on car park facility rooftops (Local Environs 1998: 1).  Just outside of Melbourne in Port Phillip, landscape architect students have actually recently designed a successful rooftop garden for a local car park roof (personal comm. White 1998).

  ¹⁵ “Non-structural methods are defined as small scale and/or natural ways of managing stormwater by: (a) redirecting rainwater away from the sewer system; (b) detaining rainwater to reduce the amount of rainwater entering the sewer system during rainstorms; (c) encouraging rainwater to infiltrate into the ground; (d) intercepting rainwater before it reaches paved areas; and (e) filtering rainwater to remove pollutants” ( Aquafor Beech Limited 1998:2).

  ¹⁶Study on stormwater control conducted in City of Yokohama, Japan (Watanabe, 1995) has addressed the issue of use of permeable pavement and infiltration pipes. The standard thickness of the permeable pavement for the study was 35 cm; a 5 cm thick permeable surface course on a 30cm thick base course. Study was conducted in a housing area of western part of Yokohama, where passenger vehicles constitute the major traffic on the roads. Follow up study, eight years after placement of the pavement, has shown that only a light deterioration in the texture has been observed, but there have been no cracks, settlements, nor maintenance problems (Watanabe, 1995). Unfortunately, the exact kind of porous pavement used is not mentioned in the report.

  ¹⁷Extensive information and details on drainage systems can be found through the Rooftop Gardens Resource web site, published by City Farmer: www.cityfarmer.org/rooftop59.html#rooftop

  ¹⁸Chicago’s success in greening as a result of implementing this by-law can be illustrated by the fact that even those parking lots not subject to the zoning by-law have been undertaking greening initiatives on their own lots (personal comm. Hoeer 1998).  This is thought to be due to the fact that businesses and lot owners are sensing the economic gains that they can make from having a more attractive lot to serve their clientele (ibid).

  ¹⁹Similar zoning policies have been applied in Portland, Oregon, where the Park Bureau has implemented new zoning regulations that stipulate the amount of greenery commercial developments must provide (Urban et al 1989).  Unfortunately, only this limited information on Portland’s regulations could be obtained.

  ²⁰Examples of current zoning requirements are: 5.5 spaces per 104.5 m2 in East York and 5.5 spaces per 93 m2 in Etobicoke (personal comm. City Clerks 1998).  In both cases, no maximum number of spaces is stipulated.

  ²¹“Parking supply relates to the ability of local governments to control the total number of parking spaces that are available within a given area, such as downtown, and thereby influences the number of automobiles that will be attracted to the area…” (Apogee Research International, Ltd., and Osborne Group 1995:85).

A transition ratio or tax ratio shows how a property class’s tax rate compares with the residential rate. If a class’s ratio falls within the range of fairness, the municipality has full flexibility to adjust it up or down within the range. If it falls outside the range of fairness, the municipality can bring it closer to the range, but not farther away from the range.

Province has released the following ranges of fairness (Ministry of Finance, 1998):

• commercial and industrial properties: 0.6 to 1.1 times the residential rate
• multi-residential properties: 1 to 1.1 times the residential rate
• pipeline properties: 0.6 to 0.7 times the residential rate

Tax rate for ‘Commercial land’, which applies to parking lots, (personal comm., City Clerk with Licencing Authority, City of Toronto) in the City of Toronto is 7.64 % (City of Toronto, 1998), which is 6,06 times higher than the residential rate (1.26%; City of Toronto, 1998).

With the new Tax Fairness Measures, City of Toronto has the power to introduce as many new property classes and tax rates as it finds appropriate (Christian Bode, personal communication). Of course, new tax rates can only be same or lower than existing ones, i.e., tax rates should be closer to the Range of Fairness. Therefore, it is possible for the City to introduce new tax rate class for parking lots that practice greening. For example, City could introduce several classes such as: parking lots with more than 10% of greened space, parking lots with more than 20% of greened space, and parking lots with more than 30% of greened space. Higher percentage of greened area would mean lower tax rates, i.e., lower property taxes!

Research conducted by the UCLA graduate student (Al Hemiddi, 1991) shows how surface treatments, including plant cover, affect ambient temperature. Al Hemiddi (1991) measured surface and air temperature at about 1m high, around noontime, during different periods over an entire year, for a total of about 70 days. The ground treatments he investigated included: a shaded sidewalk, unshaded paved plaza, an exposed lawn, a space between a high and dense shrub fence and a building, and a parking lot. Results were very interesting. During clear days, especially in the summer, differences in the air temperatures (1m above ground) of up to about 30C were often observed between the air above an exposed pavement on parking lot and the space behind the shrubs. Such difference in the air temperature next to the building's skin, in addition to the shading effects of the plants, can reduce significantly the heat gain through walls and the resulting energy consumption for air conditioning. As the air conditioning load contributes to the peak load of the electrical utilities, such effects of the landscape around a building can be of significant economical value to the utilities, in addition to the reduction of the overall energy use.
The variations in temperature of different surfaces were even bigger. During the hottest period of the study the parking lot surface reached about 500C, while the surface of the lawn was about 290C, and that of the shaded sidewalk was about 230C

Research has shown that 20-30 % of air pollution in cities may be the direct result of warmer temperatures, and that for every degree of increased temperature, smog production increases by 2-5% (City of Chicago n.d.).  The urban heat island effect has caused almost every city around the world to experience a temperature increase of between 1.70C and 4.90C compared to their surrounding area (City of Chicago n.d.).

•  Identify at-grade and sub-surface utilities early in the approval process. Utilities are mapped by, and available from Public utilities Coordinating Committee (City of Toronto, 1997b).
•  For tree species selection (for boulevard location) following guideline apply (City of Toronto, 1997b):

• Assign the largest potential root space possible for each tree. Trees planted in 5.6 cu.m or more of the soil do better than their counterparts in smaller (City of Toronto, 1997b).

Figure 8.1. A simple extensive greening project on a sloped roof.

Source: (Johnston & Newton 1993: 48)

Intercept Rain
           plant trees

Reduce Impervious Areas
           remove paved surfaces
           remove impervious structures
           install rooftop gardens

Divert Run-off
           disconnect downspouts
           divert water to roads/parking lots
           retrofit driveways

Infiltrate Into the Ground
           increase vegetation, increase gardens
           use porous pavement
           install soak away pits (surface of subsurface)
           create grassy swales or ditches
           install perforated pipes

Recycle Stormwater
           install rain barrels
           build ponds
           create wetlands
           build rooftop gardens
           install detention tanks
           install cisterns

 Figure 9.1.  Cross section of infiltration system.

 Source: (Aquafor Beech Ltd et al 1998)

 Figure 9.2. Stormwater management system, including use of constructed wetlands.

 Source: (Hough et al 1997: 23)

Several different porous paving materials have been tested (City of Toronto, 1993), but not all are suitable for Toronto:

• porous concrete - would not stand up to Toronto's winter condition;
• crushed aggregate and porous asphalt - have limited life expectancy and high maintenance requirements. Only limited applications are possible (e.g., front yard parking areas, boulevards and boulevard parking areas, low traffic parking lots).

Commissioner of Public Works and the Environment (City of Toronto, 1993) has recommended use of porous materials were possible, but has also agreed that making it mandatory for all property owners to pave whole driveways, front yard and boulevard parking areas with porous materials would not be equitable. The reason for that was that porous pavements were approximately 1/3 more expensive, and not at all location in the City have the soil conditions suitable for water infiltration.

When selecting a site it is also important to make sure that water being infiltrated into the subsoil materials does not impact on underground structures such as: basements, utilities, foundation, hydro chambers, etc.

SPA is a process by which municipalities can attempt to control the physical details of all development projects by requiring developers to submit plans and drawings for review and approval (Stonehouse 1998: 15; City of Toronto Planning & Development Dept. 1996: 50).  It is applied to all new developments as well as existing developments that propose to undertake significant renovations or modifications.  When a developer, including the Parking Authority, wants to construct a parking lot, they are required to submit their design to planners on staff with the city.  At this stage, it is suggested that the developer meet with the planner to discuss the project proposal (City of Toronto Planning & Development Dept. 1996: 50).  The planner ensures that requirements stipulated in the Urban Design Handbook (1997) and Streetscape Manual (1997) are met by the development.  Once the developer submits his/her proposal and SPA forms, they meet with a planner as well as staff with the Works Department and Urban Design Group (personal comm. R. Patrella 1998).

There are both positive and negative aspects to the use of SPA.

The positive elements are:
(1) It is a negotiated process between the developer and the planning department of the city.  Therefore, developers do not face a restrictive process.
(2) Because SPA is applied at the onstart of the development process, it can be applied easily to the development when it goes to the landscaping and urban design stage (Stonehouse 1998: 17).

The negative elements are:
(1) The entire new City of Toronto is not under the purview of SPA (although the complete former City of Toronto falls within it) (Stonehouse 1998: 15).
(2) Most importantly, there is nothing within SPA that requires a certain amount or kinds of greening to be implemented (personal comm. Mehr 1998).  Although planners can demand whatever they feel is appropriate, the only landscaping manuals that they have to go on are the Urban Design Handbook (1997) and Streetscape Manual (1997).  This suggests certain weaknesses not found in zoning and all its rigidity.  (It should be noted, however, that if the planner requires certain landscaping to which the developer objects, the City can demand a payment-in-lieu of the improvement stipulated which then allows the City to undertake the improvement itself [personal comm. Patrella 1998]).  In addition, developers are likely to choose the cheapest landscaping option when undertaking a parking lot development (personal comm. deSorcy 1998).  According to the suggestions used in the Handbook and Manual, the cheapest options provide for very sparse greening only.

12.2 The idea of using car park roofs for greening is especially significant in areas where there is little green space for community residents to enjoy (as in the central area of the City).  Due to the fact that zoning regulations in all the former municipalities of Toronto require that all residential or mixed use developments provide public amenity space, car park facility rooftops should be considered as a potential source of amenity space.  In fact, this has been stipulated by the Planning and Development Department for the former City of Toronto and, as indicated above, has already been adopted in a couple of cases (City of Toronto Planning & Development Dept. 1996: 63).  In these cases, however, they were all joint ventures not initiated by the Parking Authority.

 References:

Aquafor Beech Limited, Lura Group, Schollen & Company INC., Geomatics International, and Centre for Watershed Protection. 1998. North Bloor West Village: Non-structural Stormwater Demonstration Project. Prepared for Toronto Stormwater Group.

Al Hemiddi, N. 1991. Measurements of Surface and Air Temperatures Over Sites with Different Land Treatments. Paper presented at Passive and Low Energy (PLEA ‘91) Conference.

City of Seattle.  1992.  The City of Seattle's Environmental Action Agenda: Environmental Stewardship in Seattle.  Seattle: City of Seattle Planning Department.  (A Seattle Environmental Priorities Project.)

City of Toronto. 1998. Information about your 1998 Final Tax Bill. Brochure

City of Toronto City Forestry. 1997. Streetscape Manual.

City of Toronto City Service Committee. 1993. Use of Porous Materials for Surface Paving. City of Toronto Services Committee Report No. 6: 75-79.

City of Toronto Parks and Recreation. 1996. Would you like a FREE TREE? Pamphlet. Parks and Recreation: Urban Forestry Section.

City of Toronto Planning Development Department.  1996. Site Plan Approval.  From the Development Approval Manual.  Toronto: prepared by the City of Toronto.

City of Toronto Public Works and the Environment.  1993.  Rainwater Infiltration Through Porous Paving Surfaces. Toronto: City Clerk's Department.

City of Toronto Urban Development Services.  1997.  Urban Design Handbook (Section 3.5: Landscaping for Surface Parking Lots).  Toronto: prepared by the City of Toronto.

Daley, R.M. 1993. City Trees: The City of Chicago’s Guide to Urban Tree Care. City of Chicago Department of Environment.

Healthy City Office.  1998.  Smog: Make It or Break It.  Toronto: prepared by the City of Toronto.

Hibberd, B.G.  1989.  Urban Forestry Practice.  (Handbook 5).  London: Forestry Commission, UK.

Hightshoe G.L. 1988. Native Trees for Urban and Rural America: A Planting Design Manual for Environmental Designers. Iowa State University Research Foundation, Ames, Iowa.

Hough, M., Benson, B. and J. Evenson.  1997.  Greening the Toronto Port Lands.  Toronto: Waterfront Regeneration Trust.

IBI group and Bruce Brown Associates Limited.1990. Greater Toronto Area Urban Structure Concepts Study. Background report no. 5: Greening/Environment. Prepared for The Greater Toronto Coordinating Committee.

ICLEI (International Council For Local Environmental Initiatives) (not dated). Case Study No. 37: Greening the City.  Chicago: ICLEI.

Johnston & Newton. 1993.  A Guide to Using Plants on Roofs, Walls and Pavements. London: London Ecology Unit.

John van Nostrand Associates, Brown and Storey Architects, Gartner Lee Limited, R. V. Anderson Associates Limited, McConnell Weaver, Digital River Inc., and Corban and Goode Landscape Architects. 1998. Demonstration of Non-Structural Storm Water Management Practices: Garrison Creek Working Brief. Prepared for Toronto Stormwater Group.

Keneipp, J.M. and Van Dyke, W. 1993. Parking Geometrics. In: ULI & NPA, The Dimensions of Parking. pg. 79-83.

Kuhn, M.  1993.  Rooftop Resource (URL: http://www.cityfarmer.org/roofmonica61.html#rooftop).

Landscape Architect. 1998.  Grass-Roofs Movement.  Landscape Architect (May): 47-51.

Lipkis, A. and Lipkis K. 1990. The Simple Act of Planting a Tree: Healing Your Neighbourhood. Your City, and Your World. Jeremy P. Tarcher, Inc., Los Angeles.

Litman, T.  1995.  Land Use Impact Costs of Transportation.  Prepared in coordination with the Victoria Transport Policy Institute, Victoria.

Local Environs.  1998.  Rooftop greening in Port Phillip.  In Local Environs (Official Newsletter of Environs Australia - the Local Government Environment Network) 9 (2): 1.

McCluskey. 1987. Parking, A Handbook of Environmental Design. London

Metro Works Environmental Citizenship. (not dated). Water-wise Tips For The Summer Season: Be Water-Wise... It Makes cents! Brochure.

Ministry of Finance. 1998. Tax Fairness Measures for Municipalities. Backgrounder. (URL: http://www.gov.on.ca/FIN/html)

Ministry of Finance. 1997.  Next Step to a Fair and Equitable Property Tax System Introduced. (URL: http://www.gov.on.ca/FIN/html)

OPA (Office of Policy Analysis).  1992.  Cooling our Communities:  A Guidebook on Tree Planting and Light-Colored Surfacing.  Prepared by the Climate Change Division, U.S. Environmental Protection Agency.

McPherson, E.G.  1994.  Benefits and Costs of Tree Planting and Care in Chicago.  In Chicago's Urban Forest Ecosystem: Results of the Chicago Urban Forest Climate Project.  eds. E.G. McPherson, D.J. Nowak, and R.A. Rowntree.  USDA Forest Service General Technical Report NE-186.  Radnor, PA: USDA.

Parker, J. H.  1989.  The Impact of Vegetation on Air Conditioning Consumption.  Proceedings from Workshop on Controlling Summer Heat Islands, Berkeley.

Parking Authority.  1997.  Annual Report 1997.  Toronto: Parking Authority.

Pollution Probe.  1991.  The Costs of the Car: A Preliminary Study of the Environmental and Social Costs Associated with Private Car Use in Ontario.

Sampson, R. N., Moll, G. A. and J. J. Kielbaso.  1992.  Opportunities to Increase Urban Forests and the Potential Impacts on Carbon Storage and Conservation.  In Forests and Global Change Volume 1: Opportunities for Increasing Forest Cover.  eds. R. N. Sampson and D. Hair.  pp. 51-67.  Washington, D.C.: American Forests.

Stonehouse, D.  1998.  Building City and Nature: A Planners' Perspective on the Use of Land Use Controls to Implement a Green Infrastructure System in the Toronto Port Lands.  Prepared for Current Issues Paper, Department of Geography and Planning, University of Toronto.

Torrie Smith Associates and ICLEI.  1997.  Urban Forestry and Community Cooling: A Background Paper.  Prepared for Toronto Atmospheric Fund (Ottawa).

Urban Land Institute (ULI) and National Parking Association (NPA). 1993. The Dimensions of Parking. Third Edition. Washington.

Urban, J., Sievert, R. C., and J. Patterson.  1989.  A Blueprint for Tomorrow: Getting Tress into Urban Design.  In Shading Our Cities: A Resource Guide for Urban and Community Forests.  pp.93-101.  eds. G. Moll & S. Ebenreck.  Washington, D.C.: Island Press.

White, T.  1998.  Untitled.  Excerpts from a paper in progress.  Melbourne.

Personal contacts:

David Stonehouse, Parks & Recreation, City of Toronto
Jane Hayes, Parks & Recreation, City of Toronto/Evergreen Foundation
Murray Boyce, Parks & Recreation, City of Toronto
Erika Horvath, City Forestry, City of Toronto

Rollin Stanley, Urban Planning and Development Services, City of Toronto
Leo deSorcy, Urban Planning and Development Services, City of Toronto
Rhonda Patrella, Urban Planning and Development Services, City of Toronto

Greg Hocken, Healthy City Office, City of Toronto

Ian Mehr, Planner with Parking Authority, City of Toronto
Amir Nathoo, Designer with Parking Authority, City of Toronto
Ruth Wortzman, Assistant to president of Parking Authority, City of Toronto
Real Estate representative with Parking Authority (name unknown; communication took place through R. Wortzman and faxed questions), City of Toronto

City Clerks with Zoning Departments in East York, Etobicoke
City Clerk with Taxes and Water Office, City of Toronto
City Clerk with Licencing Authority, City of Toronto

Monica Kuhn, landscape architect, Toronto
Roy van Veen, Licensing Authority
Christian Bode, Minstry of Finance, Ontario
Natasha Duffy, UofT Urban Forests Centre
Rick Saker, Operations Manager, Sherway Gardens Mall

Dr. Hildegard Feldmann, Department of Urban Landscapes, UFZ Centre for Environmental Research, Leipzig, Germany
Suzanne Malec Hoeer, former employee of Chicago Department of Zoning
Terry White, landscape architect, Melbourne, Australia