1 Emeryville Tree Planting Opportunity
Draft Inventory and Planting Guide
November 13, 2023
Prepared by PlaceWorks
2 Emeryville Tree Planting Opportunity
Draft Inventory and Planting Guide
11/10/2023
Contents
Introduction and Purpose..............................................................................................................................3 Document Organization ................................................................................................................................4 Existing Policies and Related Documents......................................................................................................5 Emeryville Urban Forestry Ordinance .......................................................................................................5 Emeryville General Plan.............................................................................................................................5 Emeryville Landscaping and Water Use Requirements.............................................................................6 Existing Public Trees Inventory......................................................................................................................7 Tree Well Opportunity Sites Evaluation and Results Summary .....................................................................8 Equity Priority Index ..............................................................................................................................9 Planting Suitability Index .....................................................................................................................10 Results Summary and Discussion ............................................................................................................12 Additional Opportunity Sites Evaluation..................................................................................................15 Union Pacific Rail Corridor...................................................................................................................16 South Side of 40th Street ....................................................................................................................17 Hollis Street between 45th and 53rd Streets......................................................................................20 Powell Street between Interstate 80/Interstate 580 and Emeryville Police Station............................20 General Planting Recommendations...........................................................................................................21 Planting Guide .............................................................................................................................................24 Previous Inventory Tree Well Status ...................................................................................................24 Soil Cover.............................................................................................................................................24 Indicator Species.................................................................................................................................24 Overhead Powerline Present...............................................................................................................24 Underground Utility Present ...............................................................................................................24 Requires Under-Pavement Treatments...............................................................................................24 Access to Available Additional Soil ......................................................................................................25 Type of Under-Pavement Treatments.................................................................................................25 Planting Cutout Size (small, medium, large)........................................................................................25 Potential for cutout expansion............................................................................................................25 Available space for spread (diameter feet) .........................................................................................25 3 Sun Exposure.......................................................................................................................................26 Wind Exposure ....................................................................................................................................26 Species Guide ..............................................................................................................................................27 Appendix A: Equity Priority and Planting Priority Input Factors..................................................................31 Equity Priority Index Input Layers............................................................................................................31 Planting Suitability Index Input Layers.....................................................................................................35 Appendix B: Other Reference Figures .........................................................................................................36 Appendix C: Planting Bulb-out Analysis.......................................................................................................38 Introduction and Purpose
Urban trees offer a multitude of important ecological, economic, social, and public health benefits that are increasingly important for mitigating the effects of climate change:
• Cooling ambient temperatures in urban environments by providing shade and reducing the heating effects of impervious surfaces like asphalt and concrete, known as the urban heat island effect. • Managing stormwater volume and quality by absorbing stormwater, filtering groundwater pollutants, and reducing the volume of stormwater entering storm drains. • Improving air quality by absorbing air pollutants directly, and by cooling temperatures and reducing the need for air conditioning.
• Creating more welcoming public spaces and better conditions for walking and biking by providing shade, attractive landscapes, and cooler temperatures.
The City of Emeryville currently has over 2,900 street trees and 850 park trees providing shade and other benefits to the City’s 12,692 residents. Emeryville is prioritizing densifying tree canopy in the city to protect the community, especially vulnerable community members, from hotter temperatures and flood impacts.
This document provides information about where and when to plant new street trees in the city’s rightsof-way, what site treatments are needed for different types of planting opportunity sites, and other recommendations for planting and species types based on characteristics of potential planting sites. This document serves as an action plan, as well as a reference guide, for Emeryville staff to use along with the accompanying interactive web mapping tool showing the locations and attributes of existing street trees and tree planting opportunities. The web mapping tool is an interactive map hosted on the Emeryville’s ArcGIS Online organization, available through the following link and shown in Figure 1:
https://arcg.is/1j8PDa
4 FIGURE 1: PUBLIC STREET TREE MAP VIEWER
Users can zoom in and out, turn layers on and off, click on specific features to look at a pop-up window with information about them, and export data. In addition to viewing locations and attributes of the City’s publicly maintained trees, Emeryville staff may also use the web map to keep track of tree planting dates and maintenance schedules, including attaching invoice document files and photos to features in the tree planting site layer shown in the map.
Document Organization
The first section of this report summarizes Emeryville’s existing policies and requirements pertaining to street trees.
The following sections of the report briefly describe Emeryville’s inventory of existing trees, and then what are referred to as opportunity sites, or areas that the City of Emeryville and project staff identified as potentially suitable for additional trees within the city’s right-of-way (e.g., streets and sidewalks). Note that this report evaluates street trees only, and not trees within city parks, although these are viewable as a layer in the web map.
The Tree Well Opportunity Sites Evaluation and Results Summary section of the report describes how the project team collected and used opportunity site characteristic data to identify highest-priority opportunity sites based on equity factors and on lowest cost/highest feasibility. ‘Tree wells’ in this case refer to any public planting beds built for the purpose of planting trees. The project team evaluated both existing empty tree wells recorded in the City’s street tree inventory, and other sites in the City’s rightsof-way that are not currently planted and do not have tree well cutouts, identified by City Council and staff as potential opportunity sites.
The General Planting Recommendations section includes a guide to evaluating potential site costs and treatments based on site characteristics data collected in the survey and shown in the web map tool and offers general recommendations for street tree planting and care. 5 Existing Policies and Related Documents
Emeryville Urban Forestry Ordinance
The City of Emeryville’s Urban Forestry Ordinance went into effect on November 20, 2003, and achieves the following:
• Defines ‘Street Tree’ to mean any tree growing within the public right-of-way, including unimproved public streets and sidewalks, and any tree growing on land under the jurisdiction of the City of Emeryville, such as public parks or other open spaces.
• Directs the City to maintain an inventory of street trees in Emeryville and to track their ongoing maintenance and health.
• Delineates responsibilities between private property owners and the City of Emeryville with regards to public rights-of-way as well as ‘parkways’ or ‘parking strips,’ which are planted areas between the property line and roadway (not including sidewalks or curbs). • Defines the process by which a property owner must apply for an encroachment permit to plant a street tree in a parkway abutting their property (and describes circumstances in which this requirement is waived).
• Defines the conditions under which the property owner or the City is to be responsible for street tree maintenance.
• Defines the process by which a property owner must apply for an encroachment permit to remove a street tree in a parkway abutting their property (and describes circumstances in which this requirement is waived).
• Defines the process for abating nuisance trees, or trees that pose a hazard to people or property. • Defines prohibited actions that could endanger the health of street trees, like “dumping deleterious materials like salt or oil in parking strips or drains,” as well as penalties for violating the ordinance.
Emeryville General Plan
Emeryville General Plan Urban Design Element (Chapter 5) contains three policies related to street trees:
• Policy UD-P-43 aims to provide “continuous and consistent street tree planting…along Green Streets and in Neighborhood Centers.” Green streets are described in the General Plan as “streets distinguished by elements such as additional trees and plantings, wide sidewalks, pedestrian pathways and public art.”1 Neighborhood Centers are neighborhood retail clusters, with landscaping, public art, and amenities that attract visitors and define them as community gathering places.
• Policy UD-P-46 aims to provide street trees on City streets where feasible and prioritizes planting street trees “in a row along the curb, between the vehicle roadway, and sidewalk, unless this is physically impossible due to constraints such as underground water or sewer lines.” • Policy UD-P-47 aims to “follow [Rescape, formerly Bay-Friendly] Landscaping guidelines” when planting streetscape landscaping and to prioritize the dual purposes of “treating stormwater runoff and providing shade and beauty to the urban realm.” All three of these policies are associated with Implementation Action UD-A-4, directing the City to prepare a citywide streetscape plan.
1 Emeryville General Plan Parks, Open Space, Public Facilities, and Services Element. Page 4-3. 6 Emeryville General Plan Conservation Safety and Noise Element (Chapter 6) contains three policies related to street trees:
• Policy CSN-P-19 aims to “protect the natural environment, including mature trees and landscaping, from destruction during new construction and redevelopment,” and stipulates that “adequate replacement shall be provided where protection is impossible.” The associated Implementation Action CSN-A-13 directs the City to “utilize (the) Site Plan Review process to ensure public health and safety and the protection of natural and cultural resources.” • Policy CSN-P-20 aims to “encourage incorporation of native plants into landscape plans for new developments and City projects and parks and preservation of mature trees on new developments and city projects.” The associated Implementation Action CSN-A-15 directs the City to update the Capital Improvements Program.
• Policy CSN-P-21 aims to “discourage the use of non-native invasive species in any landscaped or natural areas.” The associated Implementation Action CSN-A-16 directs the City to implement a Climate Action Plan in coordination with all City departments.
The intent of Policies CSN-P-20 and CSN-P-21 is to support native populations of insects and birds by planting the native tree species that support them. Birds are dropping at an alarming rate across North America. According to Dr. Douglas Tallamy, Professor of Entomology at the University of Delaware, 432 species of birds are at risk of extinction and there are three billion fewer breeding birds compared to 45 years ago. Dr. Tallamy notes that birds need protein when reproducing and rearing their young – especially moth and butterfly larvae. These protein-rich, soft larvae have co-evolved with and need specific native plants to survive. Dr. Tallamy has extensively researched which plants, per region in the United States, will support the greatest number of moth and butterfly species. The top-ranking genera (and potential species attracted) include Oaks (271), Alders (196), and Maples (116). Conversely, non-native species support few to none. Including native trees in our landscapes is vital to maintaining this important link between birds and larvae to support a healthy and viable food web.2
Emeryville Landscaping and Water Use Requirements
The City of Emeryville’s Planning Department maintains landscaping and water use requirements for developers in the Emeryville Zoning Ordinance, applying to anyone constructing or enlarging a structure or parking lot of a certain size or for which a building permit is required. The Landscaping and Water Use Requirements ordinances include the following provisions:
• Water use and irrigation standards (minimums, maximums, rules for reclaimed water on-site, and standards for recycled water use).
• Composition of required landscaping types (e.g., a mix of trees, ground cover, shrubs, vines, etc.) • Protection and preservation of existing healthy trees to the extent possible, with adequate replacement where preservation is infeasible.
• Requirements for percentage of project area to be dedicated to landscaping by land use. • Minimum rootable soil volume and adequate soil drainage requirements for trees planted in new developments. Rootable soil volume refers to adequate volumes of soil available to accommodate tree root growth. Strong root systems maintain the health and structural integrity of the tree. The ordinance requires:
2 Burghardt, Karin T., Douglas W. Tallamy, and W. Gregory Shriver. "Impact of native plants on bird and butterfly biodiversity in suburban landscapes." Conservation biology 23.1 (2009): 219-224. 7 o A minimum of 600 cubic feet of rootable soil for small trees (15 to 24 feet wide and 20 feet tall at maturity),
o A minimum of 900 cubic feet for medium-size trees (25 to 34 feet wide and 35 feet tall at maturity), and
o A minimum of 1,200 cubic feet for large trees (more than 35 feet wide at maturity).
In addition to these requirements, Emeryville Public Works staff employ the following guidelines for tree planting in the City’s rights-of-way:
o Plant trees at a spacing of three trees per 80 feet.
o Plant trees at a minimum of 15 feet from streetlights. o Plant trees at a minimum of 25 feet from traffic signals.
The Urban Forestry Toolkit developed by Vibrant Cities Lab (a partnership between U.S. Forestry Service and nonprofit American Forests) provide much more general best practices for adequate spacing between trees and avoiding conflicts with utilities:
https://www.vibrantcitieslab.com/resources/avoiding-conflict-between-trees-and-utilities/ Existing Public Trees Inventory
The City of Emeryville contracts with West Coast Arborists (WCA) to maintain and periodically update the City’s inventory of public trees in a Graphic Information Systems (GIS) database. The City’s inventory of public trees is shown in Figure 2.
FIGURE 2: EXISTING PUBLIC TREES IN EMERYVILLE
Note: the layer used in Figure 2 was last updated in May 2022, prior to the severe winter storms in January 2023 that toppled approximately 80 trees in the Marina Park area. 8 The City of Emeryville has 728 trees planted in public parks, 279 trees planted in landscaped roadway medians, 85 trees planted in parking lot-adjacent planting beds, and 2,655 other trees planted in wells and planting strips along Emeryville’s streets and sidewalks.
According to I-Tree, a partnership between public parks and nonprofit organizations to summarize tree canopy data, Emeryville’s total tree canopy coverage, which includes all public and private tree cover, is 10 percent total and 12 percent of land only (i.e., excluding water area). Comparatively, 12 percent of San Francisco’s, 18 percent for Oakland’s, and 18 percent for all of Alameda County’s respective total areas are tree canopy.
Tree Well Opportunity Sites Evaluation and Results Summary In addition to recording the health and condition of Emeryville’s living tree canopy, the tree inventory maintained by WCA identifies tree wells that are empty or that contain dead trees or stumps. Project staff evaluated these tree well “opportunity sites” in addition to other opportunity sites that are not in the WCA inventory of Emeryville’s public trees. The study area includes all rights-of-way in Emeryville except for the area west of the Emeryville Police Station along Powell Street. This area was significantly impacted by high winds and storms during winter 2023, which toppled approximately 80 trees in Marina Park. Re-planting the marina is a larger effort beyond the scope of this study, which is focused on opportunities to increase shade density in the city’s paved areas.
Figure 3 shows the study area boundary at the Emeryville Police Station on Powell Street, the street tree well opportunity sites, and other opportunity sites evaluated in this study.
FIGURE 3: TREE PLANTING OPPORTUNITY SITES AND STUDY AREA PlaceWorks and SBCA Tree Consulting Services surveyed the 160 tree well opportunity sites and additional opportunity sites in Google Street View and in person to collect data on the suitability for planting at opportunity sites. Project staff collected information about the presence of aboveground obstructions, 9 health of surrounding indicator plant species, planting cutout size, and other planting site characteristics.
Project staff collected site characteristics data for existing street tree well opportunity sites (the smallest green and brown points shown in Figure 3) as well as for the additional street tree opportunity sites shown as large blue circles with white centers in Figure 3.
Assuming trees planted in opportunity sites reach a 15-foot-diameter branch spread at maturity, planting all tree well opportunity sites (small green and brown points) and additional street tree opportunity sites (blue circles), would increase Emeryville’s overall tree density between 1 and 2 percent, for an overall tree canopy coverage of between 11 and 12 percent citywide. Assuming trees planted in opportunity sites reach a 25-foot-diameter branch spread at maturity, planting out all opportunity sites could result in up to a 4 percent increase in Emeryville’s citywide tree density.
Project staff also gathered and mapped sidewalk frontages at various development sites within the city (blue, yellow, green, and violet polygons), but these sites were not evaluated for planting suitability because they are all part of larger pending development projects with site-specific landscaping plans.
Project staff also conducted an additional GIS analysis of where the City might add planting curb extensions or ‘bulb-outs’ to existing streets, e.g., in place of on-street parking. This analysis is discussed in Appendix C.
For existing street tree well opportunity sites recorded in the WCA citywide tree inventory, PlaceWorks staff used GIS and survey data to create three priority ranking indices: an Equity Priority Index, a Planting Suitability Index, and a combined Cumulative Index to rank sites in terms of priority. Emeryville staff can focus on planting higher-priority sites in the first year, second-highest priority sites in the second year, and so on. The three priority indices are each described in the following subsections.
Equity Priority Index – This index assigns higher-priority scores to opportunity sites in areas (census tracts or block groups) of Emeryville where additional tree canopy is potentially the most beneficial based on socioeconomic, demographic, and public health indicators. The equity priority index includes the following component factors:
• Census block groups with lower tree cover per capita, higher percentages of impervious surface area, and higher-than-average surface temperatures. These are areas where street trees would likely provide the most benefit.
• Census block groups with median income 15 percent or more below the citywide median income.
Low-income communities tend to have less tree cover than wealthier communities, and residents have fewer resources to cope with increased health impacts. • Census block groups with high asthma rates, higher-than-average shares of the population over 65, and higher-than-average shares of the population under age six. These populations are potentially the most vulnerable to increased heat.
• Census block groups with higher shares of non-White residents. Historically, local governments have under-invested in infrastructure and amenities, including street trees, in communities of color, such that neighborhoods with higher shares of non-White residents still disproportionately lack adequate street trees and greenspace compared to neighborhoods with higher shares of White residents.3
• Census tracts that score above the 55th percentile for CalEnviroScreen (CES) 4.0, a statewide environmental justice scoring index that cities and counties can use to identify communities 3 Landry, Shawn M., and Jayajit Chakraborty. "Street trees and equity: evaluating the spatial distribution of an urban amenity." Environment and Planning a 41.11 (2009): 2651-2670. 10 (census tracts) that are disproportionately burdened by various sources of pollution, combined with factors related to public health outcomes and socioeconomic opportunity.
Appendix A Figures 1 through 4 describe each layer used in the equity priority index.
Planting Suitability Index – This index assigns higher planting suitability index scores to opportunity sites based on characteristics of each site that will foster easier planting preparations and/or healthier trees. The Planting Suitability Index includes the following factors:
• Sites with larger planting cutouts, open soil, plenty of space for root and branch spread, and/or minimal need for under-pavement treatments prior to planting. • Sites that are located sufficiently far away from underground and overhead utilities and from former environmental cleanup sites.
• Sites sufficiently far away from driveways, so that street trees do not impair pedestrian and driver visibility as they mature and grow larger trunks.
Appendix A Figures 5 and 6 describe mapped factors used in the Planting Suitability Index.
Cumulative Index – This index combines both equity priority and planting suitability indices together by adding together the numeric index weight scores assigned to each tree well opportunity site for each.
Figure 4 lists all equity priority factors, planting suitability factors, and the associated index weights for each factor that together comprise the cumulative index.
11 FIGURE 4: CUMULATIVE STREET TREE PLANTING PRIORITY INDEX AND COMPONENT INDICES 12 Results Summary and Discussion
Figure 5 shows tree well opportunity sites with the highest equity priority index scores.
FIGURE 5: TREE WELL OPPORTUNITY SITES WITH THE HIGHEST EQUITY PRIORITY SCORES Opportunity sites with the highest equity priority scores are those in Census Block Group (CBG) 060014251041 in southeast Emeryville, bounded by San Pablo Boulevard to the west, 40th Street to the south, and by Emeryville city limits to the north and east. This is Emeryville’s most populous CBG, with 1,971 residents in 2019 according to the 2019 American Community Survey (ACS). This CBG has the highest population of any Emeryville CBG and the lowest tree cover per resident. This CBG also has the highest share of non-White residents, the highest share of residents making less than Emeryville’s Area Median Income, and along with CBG 060014251042, has the highest share of residents living below the Federal Poverty Line (FPL), at 20.3 percent. While not included in the equity index, CBG 060014251041 also has the highest percentage of renters out of all Census Block Groups in Emeryville.
Figure 6 shows tree well opportunity sites with the highest planting suitability based on characteristics of the planting site.
13 FIGURE 6: TREE WELL OPPORTUNITY SITES WITH THE HIGHEST PLANTING SUITABILITY SCORES Opportunity sites with the highest planting suitability scores are those in open-soil planting strips, that have large planting cutouts, and/or that have access to additional available soil. Access to additional available soil includes sites in large open-soil planting beds, tree wells with large pavement cutouts, and/or tree well sites that are close to additional soil sources, like a nearby park or private yard adjacent to the tree well.
Appendix A Figure 7 provides examples of tree wells with nearby access to additional available soil.
Access to additional available soil indicates where sites are likely to require less costly under-pavement treatments to establish adequate rootable soil. Emeryville’s soil contains a high proportion of clay, which provides nutrients to plants but easily compacts. As a result, planting sites in Emeryville in many cases are likely to require “structural soil” treatments, or treatments that create structural “void space” for roots to grow. Opportunity sites with large, open soil planting beds, large pavement cutouts, or access to additional available soil may require little or no structural soil treatments, compared to sites with small tree cutouts and little soil volume. Structural soil treatments typically consist of digging out the existing soil from the site and mixing one part of the soil with three parts clean crushed rock as well as any soil amendments based on results of prior soil analysis. The rock mixture in the soil provides the structure that creates muchneeded aeration and space for tree roots to grow. This is illustrated in Appendix B Figure 8.
Besides opportunity sites with open soil and large cutouts, other suitable sites are those sufficiently far from driveways (to minimize pedestrian/auto visibility conflict), sufficiently far from underground utilities, and sufficiently far from former cleanup sites. It should be noted that sites with lower suitability index scores are not necessarily unsuitable for planting all together, but rather, they may require more analysis or more costly site preparations like under-pavement treatments and soil remediation.
Soil that is contaminated with heavy metals or chemicals can be prohibitively costly to remediate due to the high cost of hauling and disposing of contaminated soil. Project staff recommend testing at least one 14 soil sample from every opportunity site as the first step to determining the exact soil treatments required and potential costs of site preparation. Figure 7 shows the sites with the highest combined scores (15 or above).
FIGURE 7: OPPORTUNITY SITES WITH HIGHEST COMBINED OPPORTUNITY SCORES The sites shown in Figure 7 have the highest combined equity priority and planting suitability scores, but there are many sites in Emeryville that are high-priority and highly suitable for planting besides these. Of the 160 total opportunity tree well sites, 50 sites score 5 or above for equity priority, and 32 of these are sufficiently far from barriers and obstructions like driveways, utilities, and former environmental cleanup sites.
Figure 8 shows all 160 tree well opportunity sites and their combined cumulative scores. 15 FIGURE 8: ALL TREE WELL OPPORTUNTY SITES BY COMBINED CUMULATIVE INDEX SCORE Sites with the lowest scores are those near underground utilities. Sites with this characteristic were assigned the most heavily weighted negative planting opportunity score, such that any positive scores assigned to these sites are effectively canceled out if the site is proximate to an underground utility.
Proximity to underground utilities, like gas mains and underground power lines, is the only indicator that could potentially preclude planting all together. There are 41 tree well opportunity sites that are proximate to underground gas mains, electricity lines, sewer mains, or storm gravity mains, based on GIS data available from the Pacific Gas and Electric Company (PG&E) and the California Public Utilities Commission (CPUC). of these, 20 would otherwise have a cumulative score of 10 or greater if not for their proximity to an underground utility. Project staff recommend procuring sewer lateral video or using ground-penetrating radar to assess the locations of nearby underground utilities more precisely, as GIS data may be imprecise by several feet. However, this additional step would require between $4,000 to $12,000 per mile of rightof-way assessed.
Additional Opportunity Sites Evaluation
In addition to existing tree well opportunity sites, Emeryville City Council members and staff identified other opportunity sites that PlaceWorks and SBCA evaluated in the field and in Google Streetview for planting suitability. These areas are shown in Figure 9 and are listed below, with summary findings from site visits and Google Street View.
16 FIGURE 9: ADDITIONAL STREET TREE PLANTING OPPORTUNITY SITES EVALUATED Union Pacific Rail Corridor
Project staff surveyed several sites along the Union Pacific railway right-of-way within Emeryville city limits for potential planting suitability.
Of these locations, one open planting strip area along the east side of the rail corridor on Overland Avenue between 62nd and 64th Streets was found to be a potentially suitable location with adequate soil volume and sufficiently far away from utilities and other barriers. The adjacent parking area on Overland Avenue appears to be underutilized and is potentially a suitable area to replace some parking spaces with additional bulb-out planters containing shade trees. Staff should consider this option after the parcel along the southerly frontage of Overland Avenue at this location is redeveloped (currently in process). This area is included in the web map and shown in Figure 10.
17 FIGURE 10: RAILROAD CORRIDOR OPPORTUNITY AREA: OVERLAND AVE BETWEEN 62nd ST. AND 64th ST.
The other rail corridor opportunity site is at the western end of Park Avenue adjacent to the rail corridor.
The planting cutout at this location is large and has ‘purple pipe’ reclaimed water irrigation infrastructure, which are the light lavender utility boxes shown in Figure 11. However, there are two young Arborvitae (Platycladus orientalis) and seven red Zonal Geranium plants (Pelargonium zonale) planted in the space already, somewhat reducing the available space for roots.
FIGURE 11: RAIL CORRIDOR SECONDARY SITE 3: PARK AVENUE WEST END South Side of 40th Street
Project staff surveyed the length of 40th Street on the south side and identified three locations with open soil that are potentially suitable. These locations appear to have potentially adequate soil volume and are 18 sufficiently far from underground utilities and former environmental cleanup site buffers. These locations are included in the web map and shown in Figures 12, 13, and 14.
FIGURE 12: 40th STREET SOUTH SIDE LOCATION 1
Location one is at the 40th Street entrance to Michael’s craft store (at 3991 Hollis Street). This location is sufficiently spaced between two trees to have enough branch space, and is part of a long planting cutout, but the location has an aboveground utility (the white box shown in the figure), as well as stormwater infrastructure belowground according to GIS data. This location is also approximately 15 feet from a driveway, potentially posing a pedestrian safety issue.
The second location along the south side of 40th Street is in the open soil planting bed at 1321 40th Street, as shown in Figure 13.
19 FIGURE 13: 40th STREET SOUTH SIDE LOCATION 2
An additional tree at this location would provide shade for pedestrians accessing the nearby bus stop (located just outside the frame next to the light pole and trash can in Figure 13) and would provide additional shade and privacy screening to residents at 1321 40th Street. This location does, however, have underground stormwater and electrical infrastructure, so ground-penetrating radar is recommended to confirm whether the locations are sufficiently far from these utilities.
The third location along the south side of 40th Street is near the intersection with Emery Street, shown in Figure 14.
FIGURE 14: 40th STREET SOUTH SIDE LOCATION 3
20 This location would provide additional screening for residences and shade for pedestrians accessing the bus stop but is the location of several underground utilities (stormwater and electric) shown at the site.
Hollis Street between 45th and 53rd Streets
Project staff surveyed the length of Hollis Street between 45th and 53rd Street. This length of Hollis Street is almost entirely covered in asphalt or pavement and would require pavement removal in most locations.
There are three vacant tree wells on Hollis Street between 45th and 53rd Streets sufficiently far from utilities or former environmental cleanup sites. However, these sites, which are tree wells cut into concrete, have relatively small planting cutouts (3x3 or smaller), and are likely to require under-pavement treatments to ensure adequate soil volumes that meet the City’s minimum requirements for new trees. These three sites along Hollis Street are shown in the web map and in Figure 15.
FIGURE 15: HOLLIS STREET TREE PLANTING OPPORTUNITY SITES The width of sidewalk between the tree cutout perimeter and the building side in this location is also less than the minimum Americans with Disabilities Act (ADA) requirement of four feet to accommodate wheeled mobility devices, so planting at this site would likely not comply with ADA requirements unless the sidewalk in this area were widened to accommodate the four-foot minimum.
Powell Street between Interstate 80/Interstate 580 and Emeryville Police Station There is ample open soil access along the south side of Powell Street between Interstates 80 and 580 to the east and the Emeryville Police Station to the west. The north side of Powell Street is largely paved, with less available soil in the public right-of-way than on the south side. The potentially suitable area on the south side of Powell Street is shown in Figure 16.
21 FIGURE 16: SOUTH SIDE OF POWELL STREET
Figure 16 shows the proximity of the bay adjacent to this stretch of potential planting area. Soil testing at this location is particularly important because groundwater is more likely to contain salt and contaminants from the bay that could impact trees planted in this location. The costs of remediating contaminated soil may be partly mitigated by the fact that the area is open soil, precluding pavement removal, but hauling contaminated soil away from the site could pose prohibitively high costs, depending on the nature of contamination. Project staff recommend soil testing in up to four different areas along the south side of this section of Powell Street shown in Figure 16.
General Planting Recommendations
Emeryville has ample tree well opportunity sites located in high equity-priority areas and that have high planting suitability scores. In addition, the east side of the Union Pacific rail corridor along Overland Street at 65th Street and the south side of Powell Street are the most potentially suitable planting areas for future tree wells.
Among the most important considerations for creating a dense urban tree canopy that provides cooling, aesthetic, and stormwater filtering benefits is healthy, structurally sound, and mature trees with enough space for roots and branches to grow. The City already requires minimum soil volumes for new street trees, which is an important requirement for ensuring tree health. In addition, project staff also recommend the following general tree planting guidelines for new street trees.
1. Prioritize planting trees first in areas where need is highest, and at opportunity sites with large cutouts or access to additional soil.
For opportunity sites with more access to open soil, trees can be planted relatively soon and likely at relatively low cost depending on soil testing results and associated remediations required. Opportunity sites with access to additional available soil are likely to have the lowest potential costs associated with preparing the site for planting because they are less likely to require structural soil treatments, or they are more likely to require less costly structural soil treatments.
2. Prioritize fewer trees planted per year but with designated staff and funding for early maintenance.
Prioritize planting fewer trees per year (between 5 and 10) and establishing three-year regular maintenance and watering schedules for all newly planted trees. Trees require significantly more maintenance and irrigation during the first several years after planting to ensure they will reach maturity and provide the maximum benefit to the community. This includesstaking young trees during the first year after planting, providing additional irrigation, even for drought-tolerant species, for at least the first two years after planting, and structural pruning for up to five years after planting depending on the nursery stock quality, species, and desired tree structure at maturity. 22 As a rough order of magnitude, staff recommend watering newly planted trees four times per month or as necessary until three months after a new street tree is planted, twice per month for trees planted in the ground for between four and six months, and once per month after seven months until the tree has reached desired maturity (up to two years).
The City may wish to increase planting goals in subsequent years depending on costs and staff capacity needed for adequate structural pruning and other planting maintenance.
3. Test soil at every site to determine appropriate soil treatments and other site preparations. Test soil in more than one location per site for sites within 400 feet of a former cleanup site.
Project staff highly recommend testing the soil in at least one or two locations at every opportunity site as a first step before considering soil preparations and other site treatments. Emeryville has been home to a variety of industrial land uses over the nearly 130 years that the City has been incorporated, and soil contamination from metals, salts, or chemicals is a potential risk to plant health throughout the city. In particular, the area west of Shellmound Street is built on top of landfill over bay mud. These areas are associated with a higher risk of contamination from the brackish water of the San Francisco Bay estuary, which also concentrates pollutants from urban and agricultural stormwater runoff.
At the time of this report, contracting with arborists to sample soil at each site and send samples to a lab costs roughly between $200 and $400 per site. Soil tests provide detailed horticultural analyses, including mineral content, PH, salts, and any toxic substances, and provide recommended organic or chemical amendments.
4. Prioritize selecting high-quality nursery stock for planting in the City’s rights-of-way.
Project staff recommend that the City maintain a list of local nurseries and staff contacts to ensure access to quality trees that have had adequate care to prevent root girdling from lack of space for outward root growth. Figure 17 shows an example of root girdling.
Figure 17: Example of Root Girdling
City staff, or contracted arborists responsible for purchasing trees in the City’s rights-of-way should choose younger trees without root girdling or other evidence of inadequate space for root growth.
5. Prioritize planting younger trees.
23 Younger trees are more likely to acclimatize to their newly planted environments and less likely to attract diseases or die due to environmental shocks.
6. Prioritize native and drought-tolerant trees listed in the Species Guide provided at the end of this document.
SBCA has provided an updated species list suitable for the City of Emeryville for the year 2023.
Emeryville staff may use this list in conjunction with the web map tool to identify appropriate tree species based on site characteristics like sun and wind exposure or available space for root spread.
24 Planting Guide
This Planting Guide was developed to assist Emeryville staff, developers, and/or consultants with determining suitable tree species, potential site treatments, and associated costs based on characteristics of each planting opportunity site. It is meant to be used in conjunction with the Species Guide at the end of this document, and with the web map hosted on the City of Emeryville’s ArcGIS Online organization. Bold headings summarize opportunity site characteristics relevant to determining site preparations and/or species recommendations. Bulleted and Italicized subheadings describe whether the characteristic informs recommended site preparations, tree species, or both. Bullet points below each subheading describe the levels or categories relevant to determining site preparations and/or species recommendations and their associated cost levels.
Previous Inventory Tree Well Status
• Informs site preparation recommendations.
o Empty Well: site treatments are potentially less costly. o Stump: needs to be removed; potentially more costly, depending on size. o Dead Tree: needs to be removed; potentially more costly, depending on size.
Soil Cover
• Informs site preparation recommendations.
o Open Soil: site treatments are potentially less costly. o Asphalt: site treatments are potentially more costly. o Concrete: site treatments are potentially most costly.
Indicator Species
• Can inform site preparation recommendations.
Certain species health indicators, like ash dieback on a Raywood Ash tree species, indicate that trees in that planting bed have limited space for root growth, and the site may require more costly treatments to increase soil volume.
Overhead Powerline Present
• Informs suitable species recommendations.
o Choose species with shorter heights at maturity when overhead powerlines are present.
Underground Utility Present
• Informs site preparation recommendations.
o No: Less costly. This location is likely sufficiently far from underground utilities and does not require ground-penetrating radar to assess precise utility location. o Yes: Potentially more costly. Recommend avoiding planting at this location or using ground-penetrating radar to determine precise location of underground utility and planting in this location only if site is determined to be within 10 feet or more from utility.
Requires Under-Pavement Treatments
25 • Informs site preparation recommendations.
o No: site treatments are potentially less costly. These are open planting sites, sites with large cutouts, and/or that have access to additional soil volumes. o Yes: site treatments are potentially more costly. These are planting sites surrounded by pavement or concrete that will likely require under-pavement treatments to increase soil volume.
Access to Available Additional Soil
• Informs site preparation recommendations.
o Yes: site treatments are potentially less costly and may include water jet treatments only. o No: site treatments are potentially more costly, requiring structural soil or underpavement treatments. • Informs suitable species.
o Yes: larger-stature species (requiring 900 up to 1,200 cubic feet of rootable soil) are more suitable.
o No: smaller-stature species (requiring 500 cubic feet of rootable soil) are more suitable.
Type of Under-Pavement Treatments4
• Informs site preparation recommendations.
o Water jet treatments only: less costly
o Structural Soil: more costly
o Contamination remediation and disposal of contaminated soil: most costly Planting Cutout Size (small, medium, large)
• Informs site preparation recommendations.
o Larger planting cutouts may require less costly site preparation treatments, like cutting out additional space.
o Sites with smaller cutouts will likely require additional pavement cutouts and/or underpavement treatments. • Informs species recommendations.
o Larger cutouts are more suitable for tree species with larger statures. o Smaller cutouts are more appropriate for tree species with smaller statures.
Potential for cutout expansion
• Informs site preparation recommendations.
o Yes: site treatments are potentially less costly, requiring only soil loosening and amending.
o No: site treatments are potentially more costly, requiring structural soil treatments underneath pavement or asphalt.
Available space for spread (diameter feet)
• Informs species recommendations.
4 Note: type of under-pavement treatments not yet determined and depend on soil analysis. 26 o More space for branches to spread is more suitable for larger-stature species with taller branching height to avoid conflict with taller vans and trucks. o Less space for branches to spread is more suitable for smaller, more vertical or fastigiate species.
Sun Exposure
• Informs species recommendations.
o Less sun exposure is more suitable for species that require or are more tolerant to less light.
o More sun exposure is more suitable for species that require or are tolerant to more light.
Wind Exposure
• Informs site preparation recommendations.
o Less wind exposure is potentially less costly, in that sites exposed to less wind may not require as much soil volume.
o More wind exposure may result in more costly site preparations, in that sites exposed to more wind may require more soil volume. Trees in windy sites need a greater volume of soil to hold onto moisture and allow the tree to conduct photosynthesis during windy conditions.
• Informs species recommendations.
o More wind exposure is more suitable for species that require or are tolerant to drier soil. o Less wind exposure is more suitable for species that require or are tolerant to more moist soil.
27 Species Guide
The Species Guide was developed by Steve and Molly Batchelder of SBCA Tree Consulting based on Emeryville’s current tree inventory, cross-referenced with the tree greenhouse gas (GHG) calculator (iTree).
Information was gathered from the Urban Forest Ecosystems Institute at Cal Poly: https://ufei.calpoly.edu/ and Oaktopia: https://www.oaktopia.org/sites
Steve and Molly have gone through the list in 2023 to update the recommendations for best species to plant in Emeryville, prioritizing drought tolerance and compatible growing conditions. Evergreen trees are more appropriate for sites that will not receive supplemental irrigation after establishment due to their ability to make carbohydrates in the winter/wet months. 28 Botanical Name Common Name Origin Deciduous or
Evergreen Comments
Stature/ Soil
Volume
Requirements
1 Water Use
2 Suitable
Under High
Voltage Lines
Minimum
Parkway
Width
(feet)
Acacia stenophylla Shoestring Acacia Australia Evergreen Do not over irrigate,
requires early structural
pruning
S Very low Yes 4'
Acer x freemanii 'Jeffersred' Autumn Blaze Maple Hybrid Deciduous A. saccharinum x A. rubrum; requires structural pruning
L Medium No 7'
Acer buergerianum Trident Maple Japan, China Deciduous Known to tolerate air pollution
S Medium Yes 4'
Acer negundo 'Sensation' Boxelder CA Native Deciduous Narrow, upright, good for bioswales
M High No 7'
Aesculus x carnea Red Horsechestnut Hybrid Deciduous
‘Fort McNear’ and ‘Briotii’
are cultivar; leaves are
tattered by end of summer
so best in less windy sites
S Medium Yes 7'
Arbutus 'Marina' Marina Madrone Hybrid Evergreen Beautiful red bark, attracts birds
S-M Low Yes 2'
Angophora costata Rusty Gum Eastern Australia Evergreen Closely related to the Eucalyptus
L Low No 7'
Cercis canadensis var
texensis ‘Oklahoma’ Eastern Redbud Eastern US Deciduous Shiny foliage, leaves have a
thick cuticle to resist
pathogens
S Medium Yes 2'
Cercis chinensis ‘Avondale’ Avondale Chinese Redbud China and Japan Deciduous Widely adapted, less seed pods
S Medium Yes 2'
Corymbia ficifolia Red Flowering Gum Western
Australia Evergreen Drought tolerant, lovely flowers, more wide than tall M Low No 4'
Eriobotrya deflexa Bronze Loquat
Taiwan and
Southern
Vietnam
Evergreen Powerline friendlyS Medium Yes 4'
Eucalyptus polyanthemos Silver Dollar Gum Southeastern
Australia Evergreen Drought tolerant, very tough tree
L Low No 7'
Eucalyptus spathulata Swamp Mallee Western
Australia Evergreen Tolerant of poor soil, Drought tolerant M Low No 4'
Gingko biloba Maiden Hair China Deciduous
May different cultivars for
different situations: 'Golden
Colonnade', 'Princeton
Sentry', 'Autumn Gold';
Well-drained soil.
M Medium No 7'
Gleditsia triacanthos
'Northern Sentinel' or
'Street Keeper'
Honey Locust Eastern and
Central US Deciduous Drought tolerant, tolerant
of urban conditions
M Low No 7'
Hesperocyparis macrocarpa Monterey Cypress Point Lobos Evergreen Parks only, great in windL Low No -
Koelreuteria bipinnata Chinese Flame Tree Asia Deciduous Wind tolerant, good tree
for streets
M Low Yes 4'
Koelreuteria paniculata Golden Rain Tree Central China Deciduous Wind tolerant, drought
tolerant, good tree for
streets, there is a fastigiate
cuitivar available
M Low Yes 4'
29 Lagerstroemia indica
‘Natchez’ or ‘Muskogee’ Hybrid Crepe Myrtle Southern US Deciduous Powdery mildew resistant S Low Yes 4'
Lagunaria patersonia Primrose Tree South Pacific
and Australia Evergreen Pleasing pink blooms
M Low No 4'
Leptospermum pertersonii Lemon-Scented Tea Tree Eastern Australia Evergreen Lemon-scented leavesS Low Yes 2' Liquidambar sytraciflua
‘Slender Silhouette’ Slender Silhouette Eastern US Deciduous 40 feet high x 3-4 feet wide,
better suited for narrow
locations
S Low No 2'
Lophostemon confertus Brisbane Box Australia Evergreen Overplanted in the bay, use
sparingly
M Low No 4'
Magnolia grandiflora ‘Edith
Bogue’ Edith Bogue Magnolia Eastern US Evergreen More upright and suitable for streets M Medium No 4'
Magnolia grandiflora ‘Little
Gem’ Little Gem Magnolia Eastern US Evergreen Smallest of the Southern Magnolia cultivars S Medium Yes 2'
Melaleuca linariifolia Flaxleaf Paperbark Eastern Australia Evergreen Carpet of white flowers that covers canopy in the spring
S-M Low No 4'
Melaleuca quinquenervia Paperbark (Cajeput)
Eastern and
Northern
Australia
Evergreen Do not use multi
-stemmed
specimens
M Low No 4'
Metrosideros excelsa New Zealand Christmas Tree New Zealand Evergreen Very suited to Emeryville, dark shadeM Low No 4' Parrotia persica 'Vanessa' Persian Ironwood Iran, Turkey and Georgia Deciduous Striking fall color
S Low Yes 4'
Pinus patula Jelecote Pine Mexico Evergreen
Great for coastal areas,
lovely color combination of
bark and needles
M Low No 7'
Pinus pinea Italian Stone Pine Mediterranean Evergreen Parks only, no supplemental
irrigation
L Low No-
Pistacia atlantica ×
integerrima 'Red Push' Red Push Pistache Hybrid Deciduous Hybrid, plant in warmer locations S Drought
tolerant No 4'
Pistacia chinensis Chinese Pistache China Deciduous Keith Davey is the male cultivar
M Low No 4'
Quercus agrifolia Coast Live Oak Native Evergreen
Iconic native oak to the Bay
Area; best to procure trees
with genetics from bay
influence locations
L Low No 7'
Quercus x comptoniae Compton Oak Southeastern US Both
Cross between Q. virginiana
and Q. lyrata and can be
both deciduous or
evergreen
M Medium No 4'
Quercus engelmannii Engelmann Oak South CA,
Northern Baja Partly Deciduous Attracts wildlife, warmer locations L Low No 7'
Quercus frainetto ‘Forest
Green’ Hungarian Oak
South Central
and Eastern
Europe
Deciduous
Upright form, deep green
very glossy rounded lobes; yellow to brown fall colorM Medium No 7' Quercus hypoleucoides Silverleaf Oak SW United
States, Mexico Evergreen
Powdery mildew resistant,
good drought tolerance,
summertime irrigation
tolerance, very small acorns
if any
M Low No 7'
30 Quercus oblongifolia Mexican Blue Oak
Arizona, New
Mexico, Texas,
northwestern
and central
Mexico
Partly Deciduous
More upright growth habit
than cousin Q. engelmannii,
powdery mildew resistant
M Medium No 7'
Quercus rugosa Netleaf Oak
Mexico,
Southwest US,
Guatemala
Evergreen
Adaptable to variety of
growing conditions,
beautiful new red foliage
M Low No 7'
Quercus suber Cork Oak Spain, Portugal Semi-evergreen
Soil must have good
drainage, must procure
specimens with good root
systems, very drought
tolerant
L Drought
tolerant No 7'
Quercus tomentella Island Oak Channel Islands,
Northwest Baja Evergreen
Tolerant of wide range of
soil conditions, upright
growth, good pest and
disease resistance
M Low No 7'
Quercus trojana Macedonian Oak Eurasia Deciduous Fast growing, no powdery mildew M-L Medium No 7'
Quercus virginiana Southern Live Oak Southern US Evergreen Strong branching, drought
resistant and fungal
infection resistant, upright
cultivars preferred
L Medium No 7'
Rhus lancea syn: Searsia
lancea African Sumac South Africa Evergreen Dense shade, spreading form S Drought tolerant Yes 4' Robinia pseudoacacia Black Locust Eastern and
Central US Deciduous Historical tree in CA, strong wood and fragrant flowers L Low No 7' Robinia pseudoacacia
'Frisia' Frisia Locust Cultivar Deciduous Chartreuse foliage, welldrained soil M Very Low No 7' Schinus terebinthifolia Brazilian Pepper South America Evergreen Very tough tree M Drought tolerant Yes 4'
Tilia tomentosa Silver Linden
Southeastern
Europe and
Southwestern
Asia
Deciduous Underside of leaf is silvery
white M Low, Drought
tolerant No 7'
Tristaniopsis laurina
'Elegant' Elegant Water Gum Australia Evergreen Aesthetically pleasing multistemmed trees S Low Yes 4' Ulmus americana hybrids American Elm Cultivars Deciduous There are a number of DED
resistant cultivars, small
narrow cultivars available,
'Emerald Sunshine' is a
good cultivar
L Medium No 7'
Zelkova serrata Sawleaf Zelkova Eastern Asia Deciduous
“Green Vase’ and
‘Musashino’ are more
narrow cultivars; ‘Village
Green’ is spreading
M-L Medium No 7'
1. Stature is tree size at maturity. S is 20-30 feet, M is 30-60 feet, and L is 60-120 feet. These also are correlative with soil volume requirements, where S is 600 cubic feet of rootable soil, M is 900 cubic feet, and L is 1,200 cubic feet.
2. Water use ranges from drought tolerant, low, medium, and high. Drought tolerance and wind tolerance can be improved by increasing the available soil volume requirements. 31 Appendix A: Equity Priority and Planting Priority Input Factors Equity Priority Index Input Layers
Appendix Figure 1 shows mapped factors at the census block-group level used in the Equity Priority Index.
APPENDIX FIGURE 1: I-TREE EQUITY PRIORITY FACTORS BY CENSUS BLOCK GROUP Emeryville’s easternmost census block group (CBG) 060014251041, shaded in dark pink in Appendix Figure 1, has the highest planting priority score according to the I-Tree priority factors and associated weights listed in the top left corner of the figure.
5 CBGs 060014251012 and 060014251011 have the highest percentage of residents over 64 compared to other Emeryville CBGs, at 25 and 21 percent, respectively, where residents over 64 years of age constitute 12 percent or less of the population in other Emeryville CBGs. CBGs 060014251023 and 060014251032 have the highest percentages of children under age five (between 7 and 8 percent compared to other CBGs with under-five population shares at 5 percent or less).
CBG 060014251021 has the highest share of non-White/non-Hispanic residents, at 66 percent.
Appendix Figure 2 shows the cumulative CES 4.0 score for Emeryville census tracts, which are larger than CBGs. 5 https://landscape.itreetools.org/maps/prioritize/
32 APPENDIX FIGURE 2: CALENVIROSCREEN 4.0 CUMULATIVE SCORE PERCENTILE BY CENSUS TRACT
Census Tract 6001425101, the westernmost census tract in Emeryville, has the highest cumulative CES percentile score out of the tracts in Emeryville. This tract scores in the 61st percentile, meaning this tract scores higher than 61 percent of all other California census tracts for cumulative pollution, public health, and socioeconomic burdens that the residential population faces in this tract. However, this tract has a relatively low residential population (1,659) compared to other tracts in Emeryville, which contain between 2,795 and 3,906 residents.
Tract 6001425104, in the southeastern part of Emeryville, has the second-highest CES percentile index in Emeryville, at 56 percent. This tract contains CBG 060014251041, which has the highest block group-level equity priority score according to I-Tree and other CBG-based equity factors. Census Tract 600145102, running from north to south along the length of Emeryville, scores in the 52nd percentile, and is the third-highest percentile of Emeryville census tracts.
Appendix Figure 3 shows median incomes by Emeryville census tract, and how the tract-level median incomes compare to the citywide median income, which is $109,960 in 2021 according to the American Community Survey. 33 APPENDIX FIGURE 3: MEDIAN INCOME BY EMERYVILLE CENSUS TRACT The legend in Appendix Figure 3 shows how much each census tract median income deviates from Emeryville’s citywide median income as a percentage of the citywide median income. Census Tract 6001425101 has the lowest median income of any census tract in Emeryville at $85,341, 22 percent below the citywide median income of $109,960.
Appendix Figure 4 shows linguistic isolation, which is a factor used in CES 4.0 to describe households with adults speaking limited English according to U.S. Census data.
34 APPENDIX FIGURE 4: LINGUISTIC ISOLATION BY EMERYVILLE CENSUS TRACT Census Tract 6001425102 is the most linguistically isolated census tract in Emeryville. However, this tract scores in the 57th percentile for linguistic isolation compared to all other census tracts in California, so the extent of linguistic isolation in this tract is just above the statewide average. All other tracts in Emeryville have lower-than-average rates of linguistically isolated households.
35 Planting Suitability Index Input Layers
Figure 5 shows all layers used in the planting suitability scoring index for tree well opportunity sites. Unlike equity factors, these layers are a combination of various buffers and can be depicted in one map, rather than being block group-level or tract-level data necessitating multiple maps, as is the case for the layers used in the Equity Priority Index.
APPENDIX FIGURE 5: PLANTING SUITABILITY FACTORS
Project staff assigned higher suitability scores to tree well opportunity sites close to transit stops and benches and assigned negative suitability scores to opportunity sites within the circular and linear buffers around former cleanup sites and underground utilities.
36 Appendix B: Other Reference Figures
APPENDIX FIGURE 6: ACCESS TO ADDITIONAL AVAILABLE SOIL
In the photo shown on the left in Appendix Figure 6, a street tree is planted in a small tree well cut out of the sidewalk pavement, but the tree has access to additional available soil in the adjacent open planting bed that the tree’s roots can utilize. The photo on the right shows an empty tree well opportunity site on 67th Street east of Hollis Street that also has access to additional available soil in the adjacent planting strip with pink rhododendrons.
APPENDIX FIGURE 7: STRUCTURAL SOIL
Source: https://citygreen.com/structural-soil-vs-soil-cells-whats-the-better-choice/ Figure 7 illustrates the process of adding structural soil, which involves adding crushed rock to soil to create structure and space for roots to grow, especially where soils impact easily, like in Emeryville. 37 For opportunity areas with small cutouts in the sidewalk and no access to additional soil, soil treatments could potentially be more costly, requiring more complex under-pavement treatments like soil cells to provide adequate soil volumes meeting Emeryville’s soil volume requirements. One of these treatments are soil cells, or silva cells, shown in Appendix Figure 8.
APPENDIX FIGURE 8: SOIL CELLS
Source:
https://citygreen.com/structural-soil-vs-soil-cells-whats-the-better-choice/ Soil cells are modular structure systems that require removing pavement or asphalt entirely to install the suspended pavement structure shown in Appendix Figure 8. Both the installation and the units themselves can be costly. 38 Appendix C: Planting Bulb-out Analysis
A planting bulb-out or planting extension is an extension of the curb into the roadway that accommodates trees and landscaping. Appendix Figure 9 shows an example of a planting bulb-out replacing an area that would otherwise be a street parking space in Emeryville on 65th Street near Overland Avenue.
APPENDIX FIGURE 9: PLANTING BULB-OUT EXAMPLE IN EMERYVILLE Using GIS, project staff identified street segments in Emeryville that could potentially accommodate planting bulb-outs based on roadway width and presence of parking lanes and bike lanes.
Planting bulb-outs typically require roughly 6 x 6 feet of space. Streets with on-street parking lanes were considered potentially suitable for planting bulb-outs because parking spaces typically have sufficient space to be converted to planting bulb-outs. Roadways without parking lanes were considered potentially suitable for bulb-outs if the roadway had sufficient remaining width to accommodate 10 feet of driving lane once 6 feet of roadway width was subtracted, and if the roadway did not have an existing on-street bike lane (Class II or Class III). Streets were not considered suitable for bulb-outs if they have an on-street bike because bulb-outs are likely to cause right-of-way conflicts with on-street bike lanes.
Finally, project staff overlaid underground utilities data over the resulting potentially suitable street segments to identify which street segments are suitable and conflict free, and which are proximate to underground utilities. The results are shown in Appendix Figure 10.
39 FIGURE 10: PLANTING BUILB-OUT ANALYSIS
The bright violet street segments in Appendix Figure 10 are the resulting set of streets in Emeryville with parking lanes, without on-street bike lanes, and with sufficient width to potentially accommodate planting bulb-outs. The green and turquoise utilities buffers are overlayed on top of the violet roadway casings layer to show where roadway segments have utility conflicts (where there is a green line on top of a violet line) and where there are no utility conflicts (violet roadway segment features with no green utility buffer on top of them). Potentially suitable street segments with no utility buffers include:
• Vallejo Street between 66th Street and Peabody Lane
• Steve Dain Drive between Doyle Street and San Pablo Avenue • Emery Street between 5th Street and Park Avenue
• And 40th Street between Adeline Street and San Pablo Avenue Roadway segments with utility buffers indicate areas where project staff recommend ground penetrating radar to determine the exact location of underground utilities. Utility rights-of-way may run in the center of the street sufficiently far from planting bulb-out locations in many cases.