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City of San Rafael
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Table of Contents
Purpose of these Guidelines..............................................................................................................................1
Principles and Benefits of Sustainable Design .................................................................................................1
The Role of Parking Lots in Sustainable Stormwater Design...........................................................................2
A. National Pollutant Discharge Elimination System, (NPDES) ...................................................................2
B. Provide Efficient Site Deign to Maximize the Potential for Landscaping .............................................2
C. Stormwater Facility Challenges................................................................................................................2
Landscape Design Guidelines ..........................................................................................................................3
A. General Design Guidelines .......................................................................................................................3
B. Cool Paving.................................................................................................................................................5
C. Vegetation..................................................................................................................................................5
D. Trees and Tree Shade ................................................................................................................................6
Trees......................................................................................................................................................................6
A. Planting Specifications ..............................................................................................................................6
B. Irrigation .......................................................................................................................................................7
C. Soils and Soil Volume .................................................................................................................................8
Maintenance ......................................................................................................................................................8
Landscape Plans and Submittals......................................................................................................................9
Links and Resources ......................................................................................................................................... iv
Trees for Parking Lots in San Rafael .............................................................................................................. v
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Purpose of these Guidelines
This set of guidelines is intended to promote best practices in parking lot
design, to help simplify the complex decisions that surround design
challenges for parking lots in San Rafael and to aid in the mitigation of
environmental impacts of automobile storage in light of climate
change and toxic chemical runoff. It accompanies the Parking Lot
Landscape Ordinance for the City of San Rafael, specifically Municode
Chapter 14.18 Parking Standards, §045 Designated parking for clean air
vehicles, §130 Parking facility dimensions and design, §160 Parking lot
screening and landscaping, and §240 Grandfathered parking. The
checklists are intended to be suggestive only and not a complete list of
options. The ultimate goal is to facilitate the creation of parking lot
designs in compliance with parking policies for new development and
renovations that help communities think about and plan for changes in
land use, access, circulation and pedestrian-friendly design. It is
addressed to designers and landscape professionals.
Principles and Benefits of Sustainable Design
By attempting to mimic the natural hydrologic function of healthy
ecosystems, sustainable parking lot design can dramatically reduce
pollution. Encouraging the use of low-impact development for new
and retrofitted parking lot projects is one way of capturing important
opportunities for managing stormwater, as parking lots constitute as
much as 70 percent of the total impervious cover in urban landscapes.
The overarching objective is towards watershed health.
Landscape design, including properly selected planting and
hardscape materials, can reduce heat island effect in urbanized areas,
and is an opportunity to address neighborhood aesthetics for more
livable communities.
In addition to good initial design, proper installation and long-term
maintenance are critical for successful projects.
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The Role of Parking Lots in Sustainable Stormwater Design
1 www.cement.org
Landscapes for Stormwater
Management:
§ Vegetated swales
§ Infiltration and flow-through
planters
§ Rain gardens
§ Trees
Pervious Paving System Components1
A. National Pollutant Discharge Elimination System, (NPDES)
Parking lots serve as localized collectors of trash and toxic chemicals,
acting as a filter for the physical removal of trash and contaminants
before it hits the drainage system, finding its way into local creeks and
ultimately into San Francisco Bay. The Parking Lot Landscape
Ordinance for the City of San Rafael requires conformance with
Attachment 4 of the Phase II NPDES Permit, which requires developers
to design projects to treat stormwater draining from parking lots.
B. Provide Efficient Site Deign to Maximize the Potential for Landscaping
Balancing the area allotted to parking spaces with areas allotted for
planted landscape begins to achieve multiple objectives towards
green parking lot design. Substantial landscaped areas including a
system of broad canopy trees within parking lots, “green infrastructure”,
capture rainfall even though these design features are not primarily
dedicated stormwater treatment measures. Trees provide shade to
mitigate heat island effect, and aesthetics, which leads to increased
property values.
C. Stormwater Facility Challenges
1. Retention/Infiltration and Treatment
Existing development and impervious area corresponds to soil
conditions that are typically unfavorable for water infiltration and soil
aeration, which represents a special challenge if a project is subject to
current stormwater management requirements. NPDES prescribes on-
site treatment of 85% of the annual rainfall for a region. This is
approximately a one-inch storm in the Bay Area.
2. Pervious Paving
NPDES prescribes a 1:2 ratio of pervious to impervious area. Pervious
paving allows rainwater to either pass through the paving system itself
or though joint openings between the pavers and may aid in the
infiltration of stormwater runoff to reduce volume. However, as such, it
is not considered a treatment measure as effectiveness becomes
limited at slopes approaching 5%. It should not be used in situations
with known soil contamination, high groundwater table or where soil
infiltration rates are below the accepted standard of 0.5”/hr for these
systems. Functionally, pervious paving must also maintain the same
load bearing capacity as conventional paving.
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Infiltration Planter6
Planters and screening: A recommended 8’ minimum width of perimeter
planting adjacent to the public right of way should visually screen parked
vehicles, but not completely obstruct views into and out of the parking lot for
the purpose of supporting pedestrian safety and security. These planting strips
provide opportunities for stormwater facilities. Earthen berms should not be
used as a screening option because they promote drainage toward paved
surfaces. Screen parking areas from neighboring residents, businesses or streets
with low plantings that create a 36-inch high continuous screen at mature
growth, measured from the top of curb. Above ground utilities, trash
enclosures, masonry walls and fences should be screened with shrubs or vines,
where they face a street or driveway. Landscaping should not obstruct sight
lines, building or parking lot light fixtures, address signs, building entrances and
windows.
B. Cool Paving
Use of high albedo (light colored) paving materials in parking areas and/or
walkways is encouraged. High albedo paving surfaces have a reflectance
factor of at least 0.3. The current US Green Building Council, Leadership in
Energy and Environmental Design (LEED) credit requires that a minimum of 60%
of impervious surface areas be constructed with high-albedo materials and/or
open grid pavement. The ideal application for high albedo paving materials is
for rooftop parking, especially where other shade structures are not possible.
C. Vegetation
The choice of plant material should fit with the surrounding landscape context,
be planted with an appropriate diversity and density for aesthetics and
function within stormwater facilities. Except for trees and screening of utilities,
trash enclosures, etc., plant heights should not exceed three feet for screening
and to maintain sight lines for safety. To ensure year-round green parking lots,
it is recommended that at least 70% of the plant palette, excluding trees, be
evergreen. Year-round interest can be created with plant texture, shape and
seasonal color. Avoid monocultures, which can be susceptible to disease.
Include understory planting for trees, such as shrubs, perennials, ornamental
grasses and groundcover.
Amendments as indicated on the soil test report and based on the
requirements of horticultural plants, shall be added by the contractor at the
time of spreading and/or grading. A minimum of 3” thickness of course mulch
is recommended to maintain soil moisture levels between watering, help
control weeds, protect against erosion, and reduce the risk of soil compaction
from foot traffic or heavy rains.
*The expansive use of decorative rocks, decomposed granite, or wood mulch,
as groundcover for the sole purpose of landscaping in place of live plants is
not acceptable. Artificial turf is not permitted.
6 City of Portland 2004 Stormwater Management Manual
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B. Irrigation
Irrigation for trees shall be placed on a dedicated valve separate from
irrigation to the general landscape. Tree irrigation should be provided
for two full years after planting.
To ensure the potential for healthy trees, two aeration tubes per each
tree are recommended in addition to irrigation.
Davis Tree Planting Specification9
9 City of Davis Tree Planting and Irrigation Specification
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C. Soils and Soil Volume
A soil analysis report, if required, should be prepared by a qualified soil
and plant laboratory after mass grading is completed. For trees up to 25’
crown diameter, the required minimum planter wide shall be 6’; for trees
with greater than 25’ crown diameter, the minimum planter width shall
be 8’. Where tree pits are adjacent to permeable paving, these widths
may be reduced.
Structural soil is a new pavement substrate that can be compacted to
meet engineering requirements for paved surfaces, yet retains qualities
that allow roots to grow freely. The use of structural soil mixes provides
soil volume to promote root growth and to reduce the potential for root
invasion into parking lot paving. Structural soils can add costs to a
project due to additional excavation, drainage systems and the
structural soil material itself. These costs are offset to some degree over
the long term because of higher tree survival rates and reduced
pavement maintenance costs.
The recommended minimum excavation depth is 3’. The tree pit should
be tested for proper drainage prior to planting. Fill pit with water. If
water remains after a 24-hour period, auger three (3) 4-inch diameter by
3-foot deep holes at the bottom of the tree pit. Backfill with drain rock.
Maintenance
Landscape: Maintenance levels greatly depend on plant selection.
Plant palettes composed of 70% evergreen species or varieties and that
require minimum or no shearing will require less physical maintenance.
Regionally appropriate or climate adapted plantings require almost no
irrigation after establishment.
Vegetated swales will require inspection for clogging by sedimentation
or trash and will be in need of mowing yearly or twice yearly.
Irrigation: A dedicated water meter is required for projects with 5,000 sf
or more of irrigated landscaped area. Recycled water for irrigation is
encouraged and may be required in some areas, if available. Smart
Water Application Technology and irrigation equipment including, but
not limited to, controllers, rain sensors, emission devices and valves are
recommended. A four-season irrigation schedule should be provided to
the property owner.
Pervious paving: The technology of pervious paving systems is constantly
improving. As designers and contractors are becoming familiar with
proper installations, projects integrating pervious paving in their designs
are less prone to failure. Depending on the material used, power
washing and vacuum cleaning, on a prescribed basis, are imperative to
limit the amount of sediment clogging the pore spaces of the system.
Trees: Adherence to International Society of Arboriculture (ISA)
Standards for maintenance of trees is strongly recommended.
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Landscape Plans and Submittals
Required landscape plans should be prepared by a licensed landscape
architect with expertise to prepare plans that comply with sustainable
design principles in accordance with State laws and local and regional
ordinances. Landscape plans consist of layout, landscape grading and
drainage, planting irrigation and landscape construction detail plans.
Different project types will require varying levels of submittals.
When development plans are submitted to the Planning Department for
approval, conceptual landscape plans are required. Dependent on
project type, minimum submittal standards for conceptual plans may
include:
§ Landscape statement addressing site planning issues.
§ Conceptual landscape plans on an accurately surveyed
topographic plan.
§ Planting palette for proposed planting plan, showing existing trees
and trees designated to be preserved or removed.
§ Comprehensive arborist report prepared by a certified arborist shall
be required when any protected tree is proposed for removal.
§ Conceptual irrigation plans.
Issuance of a building permit is contingent on approval of landscape
plans by the Planning Department. A landscape inspection and
approval by the Project Planner is required upon completion of the
landscape installation prior to issuance of a Certificate of Occupancy.
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Links and Resources
Bay Friendly Landscaping for Professionals, Stop-Waste.org, Oakland, California, 2008.
Available at: www.stopwaste.org
California Invasive Plant Council, Cal-IPC, www.cal-ipc.org
International Society of Arboriculture: www.isa-arbor.com
Marin County Stormwater Ordinance
Model Water Efficient Landscape Ordinance, California Department of Water Resources
National Pollutant Discharge Elimination System, NPDES: http://cfpub.epa.gv/npdes
Pacific Interlock Pavingstone. www.pacinterlock.com
San Francisco Better Streets Plan: Policies and Guidelines for the Pedestrian realm, City of San Francisco,
San Francisco, California, 2008. Available at: www.sfgov.org
San Francisco Stormwater Design Guidelines. Available at: sfwater.org. Provides calculators to properly
size stormwater facilities.
San Mateo County Sustainable Green Streets and Parking Lots Design Guidebook. First Edition. January
2009.
San Rafael, California – Code of Ordinances
Shoreline Plants: A Landscape Guide for the San Francisco bay, San Francisco Bay Conservation and
Development Commission, San Francisco, California, 2007. Available at:
www.bcdc.ca.gov/pdf/planning/SPLG.pdf
Stormwater Quality Manual for Development Projects in Marin County, Guidance for Applicants. Marin
County Stormwater Pollution Prevention Program, MCSTOPPP. Available at:
http://mcstoppp.org/acrobat/guidanceforapplicantsv_2-5-08.pdf
Water Use Classification of Landscape Species, WUCOLS, University of California Cooperative Extension
*Note: This listing is for reference use only. The City of San Rafael and this Guidebook does not endorse any proprietary
products listed herein.
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Trees for Parking Lots in San Rafael
Botanical Name Common Name
Crown
Diameter
Cercis canadensis Eastern Redbud 20'
Chitalpa tashkentensis Chitalpa 20'
Lagerstroemia indica x L. faurei clones Crape Myrtle 20'
Malus sp. 'Snowdrift', 'Golden Raindrops' Crabapple 20'
Prunus cerasifera 'Krauter Vesuvius',
'Thurndercloud'
Cherry Plum or Purple Leaf Plum 20'
Pyrus kawakamii Evergreen Pear 20'
Acer buergerianum Trident Maple 20-25'
Pyrus calleryana 'Trinity', 'Chanticleer', 'Redspire',
'New Bradford', Aristocrat'
Callery or Flowering Pear 20-25'
Acer campestre 'Queen Elizabeth' Hedge Maple 20-30'
Ginko biloba 'Saratoga', 'Autumn Gold' Maidenhair Tree 20-30'
Laurus nobilis 'Saratoga' Sweet Bay 25'
Koelreuteria paniculata, bipinnata, elegans Goldenrain, Chinese Flame, Formosan Flame 25-30'
Ulmus wilsoniana 'Frontier', 'Prospector' Frontier, Prospector Elm 25-30'
Acer fremanii 'Autumn Blaze' Autumn Blaze Maple 30'
Magnolia grandiflora 'Saint Marys', Russet' Southern Magnolia 30'
Pistacia chinensis 'Keith Davey' Chinese Pistache 30'
Sapium sebiferum Chinese Tallow 30'
Ulmus parvifolia 'Athena', 'Allee', 'Drake' Athena, Allee Chinese Elm 30'
Quercus frainetto 'Forest Green' Forest Green Oak 30'
Quercus shumardii Shumard Red Oak 30-40'
Zelkova serrata 'Green Vase', 'Village Green',
'Musashino'
Green Vase or Sawleaf Zelkova 30-60'
Quercus ilex Holly Oak 35'
Celtis australis European Hackberry 35'
Celtis occidentalis Common Hackberry 35'
Quercus lobata Valley Oak 35'
Quercus suber Cork Oak 35'
Quercus virginiana Southern Live Oak 35'
Quercus agrifolia Coast Live Oak 35-40'
Celtis sinensis Chinese Hackberry 35-40'
Fraxinus americana 'Autumn Purple', 'Chicago
Regal', 'Autumn Applause'
White or American Ash 35-40'
Liriodendron tulipfera Tulip tree 35-40'
Quercus phellos Willow Oak 35-40'
Quercus rubra Red Oak 35-40'
Platanus x acerifolia 'Yarwood', 'Bloodgood', x
hispanica, 'Columbia'
London Plane Tree, Sycamore 35-45'
Cinnamomum camphora Camphor Tree 40-60'
*This list was compiled using tree lists specifically recommended for Parking lots, collected from Bay Area municipalities
including Berkeley, Davis, Hayward, Oakland, Palo Alto, Sacramento, San Francisco, Santa Clara Santa Rosa and Sonoma.