san rafael parking lot guidelines

+Parking Lot Landscape Design & Maintenance Guidelines DRAFT

City of San Rafael ©2013

Alicia Yballa | LEED AP, BD+C Leading Landscapes, LLC

Bob Brown | AICP

Community Development Department 1400 Fifth Avenue

PO Box 151560 San Rafael, CA 94915-1560

www.cityofsanrafael.org 415-485-3085

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City of San Rafael Parking Lot Landscape Design & Maintenance Guidelines

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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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Landscape Design Guidelines

Pedestrian walkway over stormwater facility 3

“Increasing a site’s landscape area by 25% is in essence decreasing the site’s stormwater runoff by almost 25% even without the use of active stormwater facilities.”4

A. General Design Guidelines

Key Design Considerations: § Safety/Egress: Pedestrian walkways, parking lot entries and exits § Stormwater management – percent impervious cover, stormwater facilities § Aesthetics in context with surrounding neighborhood: street and building

frontages § Climate adapted plant palette – water conservation, maintenance § Maintenance: irrigation, integrated pest management § Trees for shade and stormwater management § Screening § Topography/slope; erosion control Pedestrian walkways: Optimum alignment of stormwater facilities is sometimes in conflict with desired pedestrian flow and can present challenges with American Disabilities Act (ADA) compliance. Provisions for pedestrian circulation addresses safety, prevents trampling of the landscape and are an ideal opportunity for using pervious paving. Sizing: As a general rule, for effective stormwater infiltration and treatment, dedicated landscape space should be 4% of the total impervious catchment area dependent on soil infiltration capacity, the types of stormwater facilities incorporated in the design and whether or not the project is subject to NPDES requirements. Soil testing is imperative to the design process as perforated under drains may be necessary where native soil infiltrations are low. Online resources provide calculators to help properly design and size stormwater facilities. See the Links and Resources within these Guidelines.

2 www.pavestoneatlanta.com 3 ibid, Nevue Ngan Associates 4 San Mateo County Sustainable Green Streets and Parking Lots Design Guidebook ©2009

Pervious paving types: § Pervious Asphalt/Concrete § Pervious Interlocking Joint Pavers § Reinforced Gravel Paving § Reinforced Grass Paving

Permeable paving in parking stalls2

Pervious paving is ideally placed in parking stalls and pedestrian walkways and is especially suited for parking lots that are interiorly drained, effectively reducing impervious area that generates stormwater runoff by up to 50%. When used in parking stalls adjacent to tree plantings, the effective soil volume for tree growth is increased thereby increasing the likelihood of successful trees and tree shade. It is particularly ideal for use in retrofit projects. A wide variety of materials can result in a design that delineates specific uses within an area and facilitates way finding. For example, a concrete band can separate pervious material in parking stalls from the drive aisle, at the same time functioning as an edge for the pervious paving.

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\

Check dams in bioswale5

Setbacks/Minimum Planting Areas: Required front, side street, side and rear yard setback areas should be fully landscaped and irrigated except for permitted paved areas and other approved encroachments. When landscape setback areas are used for stormwater treatment, such as a bio-swale, the setback area may be increased to meet required shade tree planting. Vegetated Swales: Many parking lots have a long, continuous space to support a functioning landscape system and can be excellent candidate sites for vegetated swales. Aside from their function as a widely accepted stormwater management strategy, they are relatively low-cost, simple to construct and easily retrofitted. Their value as an aesthetic feature in the landscape is rapidly gaining popularity. In narrowly constrained situations, in combination with pervious paving, vegetated swales may be utilized to better manage stormwater on-site.

Vegetated Swale7

Planting area types include infiltration and flow-through planters, their distinguishing feature being that the side slopes typically used in swales are replaced with vertical sidewalls, allowing for more storage volume in less space. They are easily incorporated into retrofit conditions, can be built to fit in narrow spaces between utilities, trees and other existing site elements. In situations where there is underlying soil contamination, unfavorable soil conditions for infiltration, or a high water table, flow-through planters allow some infiltration before draining to an underdrain system to help manage runoff volume. Topography/Slope: In situations with steep topography, terraced stormwater planters and closely spaced check dams and weirs are two features that can be used to decrease the velocity of runoff and enhance infiltration in stormwater facilities on-site.

5 Nevue Ngan Associates, San Mateo County Sustainable Green Streets and Parking Lots Design Guidebook ©2009 7 Acomb, G. & W. Ren, Landscape Architecture Dept., Univ. of Florida–Program for Resource Efficient Communities ©2008

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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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Shade8

D. Trees and Tree Shade

Significant tree canopy provides energy benefits in the reduction of heat gain from paved surfaced and parked vehicles. Trees provide natural cooling benefits by evaporating water and providing direct shading of asphalt surfaces. Required ratios of tree to number of parking spaces is dependent on canopy diameter: 1 tree per 4 parking spaces for 30’+ diameter canopy trees and 1.5 trees per 4 parking spaces for 20’-25’ diameter canopy trees. Alternative shade structures may replace shade tree planting after the minimum interior tree requirement is satisfied or when sufficient soil volume and planting conditions cannot be achieved for proper tree growth. These alternatives may include solar carports, trellises or arbors, shade sails or cool paving materials. In consideration of solar orientation to maximize shade benefits, placement of tall trees is encouraged along the southerly and westerly perimeters of the parking lot. Preserve existing, healthy trees whenever possible. Mature trees are often able to soak up water at a rate comparable to what can be captured by a stormwater facility. Leaf canopies intercept and hold large quantities of rainwater on the leaf surface. Trees provide air quality benefits by acting to remove particulate matter and gaseous air pollutants such as ozone, nitrogen oxides, sulfur dioxide and ammonia. Well-maintained mature trees can provide economic benefits by increasing property values and the quality of life in urban developments. Refer to the City’s List of Recommended Parking Lot Trees within these guidelines.

Trees A. Planting Specifications

Trees should be planted a minimum of five feet from sewer, water, gas, cable and electrical lateral services lines, as well as from any paving and structures. Trees should be located a minimum of seven feet from utility boxes, fifteen feet from a light pole and a minimum of thirty feet from the face of a traffic signal, or as otherwise specified by the City. Provide root barriers when a tree is located within seven feet of a structure or edge of paving. Provide tree protection during construction, including, but not limited to proper pruning prior to commencement of construction to avoid interference of branches with construction equipment, placement of protective fencing, avoidance of soil compaction and grading within the tree driplines, and maintenance of positive drainage away from tree trunks. Ideally, a certified Arborist should monitor soil preparation and tree planting. Stakes should be removed when the tree trunk diameter meets or exceeds the diameter of the stake.

8 Nevue Ngan Associates, Sustainable Green Streets and Parking Lots Design Guidebook, San Mateo County ©January 2009

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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.

san rafael parking lot guidelines

Documents

landscape design guidelines

general design guidelines

sustainable stormwater

benefits of sustainable

landscape plans

role of parking lots

stormwater facility

bd c leading landscapes