&EPA
United States
Environmental Protection
Agency
2012 GREEN INFRASTRUCTURE TECHNICAL ASSISTANCE PROGRAM
City of Atlanta
Atlanta, GA
Boone Boulevard
Green Infrastructure Conceptual Design
Photo: Street-side bioretention
MARCH 2014
EPA 830-R-14-001
-------
About the Green Infrastructure Technical Assistance Program
Stormwater runoff is a major cause of water pollution in urban areas. When rain falls in undeveloped
areas, the water is absorbed and filtered by soil and plants. When rain falls on our roofs, streets, and
parking lots, however, the water cannot soak into the ground. In most urban areas, stormwater is
drained through engineered collection systems and discharged into nearby waterbodies. The
stormwater carries trash, bacteria, heavy metals, and other pollutants from the urban landscape,
polluting the receiving waters. Higher flows also can cause erosion and flooding in urban streams,
damaging habitat, property, and infrastructure.
Green infrastructure uses vegetation, soils, and natural processes to manage water and create healthier
urban environments. At the scale of a city or county, green infrastructure refers to the patchwork of
natural areas that provides habitat, flood protection, cleaner air, and cleaner water. At the scale of a
neighborhood or site, green infrastructure refers to stormwater management systems that mimic
nature by soaking up and storing water. These neighborhood or site-scale green infrastructure
approaches are often referred to as low impact development.
EPA encourages the use of green infrastructure to help manage stormwater runoff. In April 2011, EPA
renewed its commitment to green infrastructure with the release of the Strategic Agenda to Protect
Waters and Build More Livable Communities through Green Infrastructure. The agenda identifies
technical assistance as a key activity that EPA will pursue to accelerate the implementation of green
infrastructure.
In February 2012, EPA announced the availability of $950,000 in technical assistance to communities
working to overcome common barriers to green infrastructure. EPA received letters of interest from
over 150 communities across the country, and selected 17 of these communities to receive technical
assistance. Selected communities received assistance with a range of projects aimed at addressing
common barriers to green infrastructure, including code review, green infrastructure design, and cost-
benefit assessments. Through the assistance provided to the City of Atlanta (City), EPA developed a
concept design for a green infrastructure project to revitalize a distressed neighborhood and reduce
flooding and combined sewer overflows (CSOs). The following report presents this concept design in
detail, and is intended to provide a nationally applicable model for green infrastructure implementation
in distressed neighborhoods.
For more information, visit http://water.epa.gov/infrastructure/areeninfrastructure/qi support.cfm.
-------
Acknowledgements
Principal USEPA Staff
Mary Jo Bragan, EPA Region IV
Tamara Mittman, U.S. EPA Headquarters
Christopher Kloss, U.S. EPA Headquarters
Community Team
Julie Todd, City of Atlanta
Susan Rutherford, City of Atlanta
Andrew Walter, City of Atlanta
Jonathan Lewis, City of Atlanta
Walt Ray, Park Pride
Ellen Wickersham, Invest Atlanta
Tony Torrence, Community Improvement Association
Consultant Team
Eric Byrne, Tetra Tech
Julie Kaplan, Tetra Tech
Jonathan Smith, Tetra Tech
Bobby Tucker, Tetra Tech
Martina Frey, Tetra Tech
Stakeholder Meeting Participants
Bill Eisenhauer, MAUWI
Clifford Ice, City of Atlanta
Anne Keller, EPA Region IV
Nolton Johnson, City of Atlanta
Stacy Funderburke, The Conservation Fund
Catherine Owens, Atlanta BeltLine Inc.
Lee Harrop, Atlanta BeltLine Inc.
Michael Elliot, Georgia Tech Center for Quality Growth
C. Shaheed DuBouis, Vine City Civic Association
Lisa Glanville, City of Atlanta
This report was developed under EPA Contract No. EP-C-11-009 as part of the 2012 EPA Green
Infrastructure Technical Assistance Program.
-------
Contents
Executive Summary vi
1 Introduction 1
1.1 Project Process and Local Context 1
1.2 Benefits of Green Infrastructure 2
2 Boone Boulevard Site 4
2.1 Existing Conditions 4
2.2 Proposed Site Design 6
3 Goals 7
3.1 Project Goals 7
3.2 Design Goals 7
4 Green Infrastructure Toolbox 8
4.1 Bioretention Facilities 8
4.2 Permeable Pavement 10
4.3 Impervious Area Conversion 12
5 Green Infrastructure Conceptual Design 13
5.1 Conceptual Layout 13
5.2 Green Infrastructure Sizing 15
6 Green Infrastructure Technical Specifications 17
6.1 Common Elements 17
7 Operations and Maintenance 23
8 Capital Cost Estimates 25
9 References 27
Appendix A Proctor Creek/North Avenue Needs Assessment A-1
Appendix B Proctor Creek/ North Avenue Project Prioritization Summary B-l
Appendix C Conceptual Design Layouts C-l
IV
-------
Figures
Figure 2-1. Boone Boulevard green infrastructure catchment area 5
Figure 2-2. Boone Boulevard from Brawley Dr., facing east 6
Figure 2-3. Boone Boulevard from Walnut St., facing west 6
Figure 4-1. Bioretention incorporated into a right-of-way 9
Figure 4-2. Bioretention incorporated into traditional parking lot design 9
Figure 4-3. Planter box within street right-of-way 9
Figure 4-4. Flow-through planter box attached to building 9
Figure 4-5. Tree box using grate inlets in street 10
Figure 4-6. Permeable pavement one-way cycle track 12
Figure 4-7. Permeable interlocking concrete paver parking stalls 12
Figure 4-8. Conversion of impervious roadway to vegetated center median 12
Figure 5-1. Conceptual layout for Boone Boulevard green infrastructure practices 14
Figure 6-1. Typical planter box 20
Figure 6-2. Permeable interlocking concrete pavers 22
Figure 6-3. Pervious concrete 22
Tables
Table 1-1. Studies estimating percent increase in property value from green infrastructure 3
Table 2-1. Drainage area characteristics 6
Table 5-1. Existing drainage area runoff volumes 16
Table 5-2. Proposed green street SCM sizing 16
Table 6-1. Traditional bioretention/planter box specifications 19
Table 6-2. Permeable pavement 21
Table 7-1. Bioretention operations and maintenance considerations 23
Table 7-2. Permeable pavement operations and maintenance considerations 24
Table 8-1. Cost estimate for implementation of Boone Boulevard green infrastructure 25
-------
Executive Summary
This report describes a green infrastructure conceptual plan developed for a portion of Boone Boulevard
in the City of Atlanta. Located at the border of the English Avenue and Vine City neighborhoods, Boone
Boulevard lies within the Proctor Creek Watershed, in an area designated by the EPA as an
environmental justice community for watershed improvements. Like many environmental justice
communities, the area confronts a range of environmental, social, and economic challenges:
The area is served by both separate and combined sewer systems, leading to water quality
impairments in Proctor Creek;
Frequent and repeated flooding contributes to a significant number of abandoned properties;
The area has a 20% housing vacancy rate and a foreclosure rate of 40%;
41% of the 9,000 residents of English Avenue and Vine City live below the poverty line;
Nearly half of all households earn less than $22,355 per year;
The crime rate in Vine City is more than twice the City of Atlanta average (Park Pride, 2011).
A local nonprofit, Park Pride, identified green infrastructure as a promising approach to addressing the
community's challenges. In 2010 and 2011, Park Pride led a coalition of local and national partners-
including residents, local, state and federal government agencies, impacted businesses and institutions
of higher learningin a Visioning Process to propose 200 acres of green infrastructure. The proposed
green infrastructure would offer a connected series of green spaces to the community while also
reducing the amount of combined sewer overflows, which contribute to the water quality impairments
in Proctor Creek.1 In the spring of 2011, Park Pride published the resulting plan, Proctor Creek/North
Avenue Watershed Basin: A Green Infrastructure Vision (PNA Vision). The green infrastructure proposed
for the PNA project includes parks, stormwater management greenways, community gardens and other
vegetative areas, as well as constructed streams, rain gardens and bioretention ponds. In addition to the
series of connected green spaces, the PNA Vision calls for the introduction of green streetsa design
approach that uses natural systems to reduce stormwater runoff, improve water quality, enhance
pedestrian safety, and beautify neighborhoods. The Boone Boulevard conceptual design and project
prioritization presented in this report provide a site-specific green street design that complements the
city's concept for this transportation corridor and could be integrated with several planned roadway
improvements. The project also can serve as a template for additional green street retrofits elsewhere
as the PNA Vision progresses.
Section 1 of this report presents the project process and local context and describes the benefits of
green infrastructure. Site conditions and the proposed site design are found in Section 2, the goals of
the project and design are discussed in Section 3, and the types of green infrastructure considered for
the project are included in Section 4. The conceptual design is presented in Section 5, and green
infrastructure technical specifications are included in Section 6. Section 7 provides information on
proper operation and maintenance of green infrastructure, and Section 8 provides detailed capital cost
estimates for the proposed conceptual design. References are found in Section 9. Appendix A is the
Proctor Creek/North Avenue Needs Assessment and Appendix B is the Project Prioritization Summary.
Conceptual design layouts are found in Appendix C.
1 In 2008, the City completed combined sewer separation of the Greensferry combined sewer overflow (CSO); however, the
North Avenue CSO facility is still operational. Both facilities are located in the headwaters of the Proctor Creek Watershed.
VI
-------
I Introduction
I.I Project Process and Local Context
The Proctor Creek/North Avenue (PNA) watershed basin is an urban watershed immediately west of
downtown Atlanta. Land use within the PNA consists of primarily low income residential and commercial
uses that are supported by two wastewater treatment plants, one of which is a combined sewer
treatment facility. The watershed has experienced frequent and repeated flooding in recent years
resulting in a significant quantity of abandoned properties.
In 2011, Park Pride in conjunction with a coalition of local and national partners developed the Proctor
Creek/North Avenue Watershed Basin: A Green Infrastructure Vision (PNA Vision). The PNA Vision
proposed a series of green infrastructure projects within the PNA area that offer a network of green
spaces to the community while providing capacity relief for the combined sewer system. Proposed
green infrastructure features include parks, day-lighted streams, greenways, and community gardens.
EPA used the PNA Vision as a starting point for designing a green infrastructure project in the Proctor
Creek watershed. The PNA Vision and other studies were reviewed to identify needs within the
watershed (summarized in Appendix A). Needs include:
Flood reduction and management to provide capacity relief for the combined sewer system;
Cleaner surface and groundwater;
Improved streets and sidewalks; and
Economic revitalization.
Project team members, accompanied by Park Pride staff, conducted a field assessment of the watershed
to collect additional information about potential green infrastructure sites identified in the PNA Vision.
A meeting was held with City planners, stakeholders, and citizen representatives to discuss the
preliminary field evaluation results and to help inform the selection and project prioritization criteria.
Sites were then scored and ranked according to priority criteria. This process is summarized in Appendix
B. The City used the information gleaned from this evaluation process to select a single green
infrastructure project to develop into a conceptual plan. The selected project incorporates green
infrastructure practices along the Boone Boulevard roadway corridor from Maple Street to James P.
Brawley Drive.
Boone Boulevard is an east-west road that is located in the northwest quadrant of Atlanta. It passes
through several neighborhoods and crosses the future path of the Atlanta BeltLine, a large-scale multi-
use trail and greenway system. The City of Atlanta has been considering the redevelopment of Boone
Boulevard (previously named Simpson Road) for several years. Plans for this corridor are detailed in the
City's 1995 Simpson Redevelopment Plan and the City's 2006 Simpson Road Corridor Redevelopment
Plan Update. The 2006 update presents a concept that involves concentrated mixed-use activity nodes
linked by a continuous transportation corridor with streetscape and residential uses.
Implementing a green infrastructure project along Boone Boulevard would complement the city's
concept for this corridor and could be integrated with several planned roadway improvements. This
corridor is being reconstructed between Chappell Road and Northside Drive to reduce the road from
four lanes to two lanes and to add improved bike lanes. In addition, Boone Boulevard is part of the Cycle
Atlanta Phase 1 study conducted by the Atlanta Regional Commission Livable Centers Initiative (LCI). The
Atlanta Regional Commission recently awarded the city $2.0M for installation of projects in the Phase 1
study. For Boone Boulevard, that includes resurfacing and restriping the current roadway surface. In
April 2013, the City of Atlanta Department of Watershed Management was awarded a Section 319(h)
grant in the amount of $387,747 to provide incremental funding for implementation of the green
-------
infrastructure components of the project. The City has made a further commitment to expand the scope
of the green street to 1.2 linear miles along Boone Boulevard connecting downtown Atlanta to the west
side of the BeltLine.
1.2 Benefits of Green Infrastructure
Urbanization and associated land cover change inhibit many of the processes that drive the natural
hydrologic cycle, including infiltration, percolation to groundwater, and evapotranspiration. Traditional
engineering approaches exacerbate these changes by rapidly conveying stormwater runoff into drainage
systems, discharging higher flows and pollutant loads into receiving waters. As a result, stormwater
runoff from urbanized areas is often a significant source of water quality impairments.
Green infrastructure is an important design strategy for protecting water quality that provides multiple
community benefits. EPA defines green infrastructure as structural or non-structural practices that
mimic or restore natural hydrologic processes within the built environment. Common green
infrastructure practices include permeable pavement, bioretention facilities, and green roofs. These
practices complement conventional stormwater management practices by enhancing infiltration,
storage, and evapotranspiration throughout the built environment and managing runoff at its source.
Green infrastructure methods often offer greater versatility in design than conventional management
practices, and can be incorporated into new urban development and redevelopment designs with
relative ease. Green infrastructure practices have also been shown to cost-effectively reduce the
impacts of stormwater runoff while reducing stormwater control measure (SCM) maintenance
requirements (Chen and Hobbs, 2013). In addition, a key advantage of green infrastructure over
conventional infrastructure is that green infrastructure provides multiple benefits to the surrounding
community, including the following:
Increased property values: Many aspects of green infrastructure can increase property values,
including improved aesthetics, drainage, and recreational opportunities. Table 1-1 summarizes the
recent studies that have estimated the effect that green infrastructure or related practices have on
property values. The majority of these studies addressed urban areas, although some suburban
studies are also included. The studies used statistical methods for estimating property value trends
from observed data.
Increased enjoyment of surroundings: A large study of inner-city Chicago found that one-third of
the residents surveyed said they would use their courtyard more if trees were planted (Kuo, 2003).
Residents living in greener, high-rise apartment buildings reported significantly more use of the area
just outside their building than did residents living in buildings with less vegetation (Hastie, 2003;
Kuo, 2003). Research has found that people make more walking trips when they are aware of
natural features in the neighborhood and judge distances to be greater than they actually are in less
green neighborhoods (Wolf 2008).
Increased safety and reduced crime: Researchers examined the relationship between vegetation
and crime for 98 apartment buildings in an inner city neighborhood and found the greener a
building's surroundings are, the fewer total crimes (including violent crimes and property crimes),
and that levels of nearby vegetation explained 7 to 8 percent of the variance in crimes reported by
building (Kuo, 2001a). The stress reduction effects of trees are likely to also have the effect of
reducing road rage and improving the attention of drivers (Wolf, 1998; Kuo, 2001a). Generally, if
properly designed, narrower, green streets decrease vehicle speeds and make neighborhoods safer
for pedestrians (Wolf, 1998; Kuo, 2001a).
-------
Increased sense of well-being: There is a large body of literature indicating that green space makes
places more inviting and attractive and enhances people's sense of well-being. People living and
working with a view of natural landscapes appreciate the various textures, colors, and shapes of
native plants, and the progression of hues throughout the seasons (Northeastern Illinois Planning
Commission, 2004). Birds, butterflies, and other wildlife attracted to the plants add to the aesthetic
beauty and appeal of green spaces and natural landscaping. Attention restorative theory postulates
that exposure to nature reduces mental fatigue, with the rejuvenating effects coming from a variety
of natural settings, including community parks and views of nature through windows; in fact, desk
workers who can see nature from their desks experience 23 percent less time off sick than those
who cannot see any nature, and desk workers who can see nature also report a greater job
satisfaction (Wolf, 1998).
Table 1-1. Studies estimating percent increase in property value from green infrastructure
Source
Percent increase in
Property Value Notes
Ward et al. (2008) 3.5 to 5%
Shultz and Schmitz (2008) 0.7 to 2.7%
Wachter and Wong (2006) 2%
Anderson and Cordell (1988) 3.5 to 4.5%
Voicu and Been (2008)
9.4%
Espey and Owasu-Edusei (2001) 11%
Pincetl et al. (2003)
1.5%
Hobden, Laughton and Morgan 6.9%
(2004)
New Yorkers for Parks and
Ernst & Young (2003)
8 to 30%
Estimated effect of green infrastructure on adjacent
properties relative to those farther away in King County
(Seattle), WA.
Referred to effect of clustered open spaces, greenways
and similar practices in Omaha, NE.
Estimated the effect of tree plantings on property values
for select neighborhoods in Philadelphia.
Estimated value of trees on residential property
(differences between houses with five or more front yard
trees and those that have fewer), Athens-Clarke County
(GA).
Refers to property within 1,000 feet of a park or garden
and within 5 years of park opening; effect increases over
time.
Refers to small, attractive parks with playgrounds within
600 feet of houses.
Refers to the effect of an 11% increase in the amount of
greenery (equivalent to a one-third acre garden or park)
within a radius of 200 to 500 feet from the house.
Refers to greenway adjacent to property.
Refers to homes within a general proximity to parks.
-------
2 Boone Boulevard Site
2.1 Existing Conditions
The proposed green street project on Boone Boulevard will treat an area of just over 2.5 acres between
Brawley Drive and Maple Street, covering over 2,200 feet of roadway. The entire catchment area is
approximately 92% impervious, and has an average slope of approximately 5%. The soils are
predominantly classified as urban with a null Hydrologic Soil Group (HSG) value. There are no known
potential soil contamination issues within the project area. The project area is not designated as a
groundwater recharge area.
Most of the existing 4-lane roadway (two lanes each direction) is drained via a combined sewer system
that intersects a main trunk line running north-south along Vine St. The block between Brawley Dr. and
Griffin St. drains westward to a separate storm main at Brawley Drive. The City-owned right-of-way
extends beyond the edges of the sidewalks located on both sides of the roadway. There are
approximately 26 driveway entrances along the project area, although several of these connect to
vacant lots. In addition, there are bus stops at the southwest and northeast corners of each of the seven
intersections. Currently there is no designated on-street parking along Boone Boulevard.
A planned road diet will convert the existing 4-lane (2 lanes each direction) road to two, 10-foot travel
lanes with a 12-foot left turn lane at selected intersections. According to the City of Atlanta, left-turn
lanes will be required at Brawley Dr., Sunset Ave., and Vine St. (east-bound only). A 5-foot-wide bike
lane will also be included on both sides of the street. Although the existing right-of-way is
approximately 55 feet along Boone Boulevard, the road diet improvements will only extend between
the inside edge of the sidewalk on both sides of the street, which is typically a 44-foot width.
The City provided GIS data layers for their storm and sanitary sewer network in the project area, which
included locations, diameters, and material types for all of the pipe lines, and locations and rim
elevations for the structures (e.g., catch basins, manholes, drop inlets, etc.). The GIS data also contained
invert elevations for seven of the structures in the project area, which ranged in depth from 2.4 to 3.6
feet. Catch basins or drop inlets are located at every intersection within the project area. The storm
drains along Boone Boulevard are reinforced concrete pipe with either 12- or 15-inch diameters. The
combined sewer trunk line running under Vine St. is 12 feet in diameter according to the GIS layer, with
unknown depth. The sewer line and associated laterals along Boone Boulevard, which were more
critical to the green street implementation, were shown to have invert depths in excess of 5.2 feet and
are not likely to conflict with proposed green street drainage features.
Boone Boulevard is also adjacent to the future site of a public park. Part of the City of Atlanta's
approved proposals to restore the Vine City neighborhood involves the establishment of the 16-acre
Historic Mims Park. The park will be located south of Boone Boulevard between Elm and Walnut Streets
and will consolidate numerous vacant lots that are owned by the City. The park would be built in phases
and include various monuments that salute Atlanta's historic figures, a retention pond to manage runoff
from within the park, public art, educational activities, a museum, and an urban farm and greenhouses.
Figure 2-1 depicts the project catchment area, existing storm drainage network and topography, and
parcel boundaries.
-------
Legend
Storm Pipes
Elevation Contour (2ft)
Green Street Catchment
Parcels
City of Atlanta
Boone Boulevard
Green Infrastructure Design
Figure 2-1. Boone Boulevard green infrastructure catchment area
-------
Table 2-1 shows the drainage area properties for each catchment area. Catchment areas were
delineated by block and road centerline. For example, drainage area "Vin-Wal N" represents the north
side of Boone Boulevard between Vine St. and Walnut St. Offsite contributions from private driveways,
curb cuts, etc. are also a factor in the green infrastructure design.
Table 2-1. Drainage area characteristics
Property
Area (ac)
Slope (%)
Imperv. (%)
Wai-
Map
S
0.15
4.5
100
Wai-
Map
N
0.38
4.4
100
Vin-
Wal S
0.18
4.5
100
Vin-
Wal
N
0.19
4.5
100
Elm-
Vin
S
0.23
5.0
88
Elm-
Vin
N
0.16
4.8
82
Sun-
Elm N
&S
0.66
3.0
88
Gri-
Sun
S
0.21
5.9
100
Gri-
SunN
0.17
5.2
100
Bra-
Gri
S
0.18
6.4
78
Bra-
Gri
N
0.19
6.2
79
Example photographs of the study area are provided in Figure 2-2 and Figure 2-3.
Figure 2-2. Boone Boulevard from Brawley Dr.,
facing east
Figure 2-3. Boone Boulevard from Walnut St.,
facing west
2.2 Proposed Site Design
The overall vision for the Boone Boulevard green infrastructure project, provided in detail in Appendix C,
is to implement "green street" infrastructure in conjunction with the planned road diet improvements.
The proposed design includes a combination of planter box and permeable pavement features, in
addition to several bioretention systems proposed outside of the road right-of-way in Mims Park. Each
practice was designed to capture and treat the runoff from a 1.2 inch rainfall event. Several extended
planting strips are also proposed along the roadway to reduce impervious area and take advantage of
underutilized areas created by the road diet. Consistent with green street objectives, the extended
planting strips help reduce overall runoff to downstream areas and receiving SCMs. The design and
layout of the proposed green street was governed mostly by traffic and community needs, followed by
water quality sizing criteria, as discussed in Section 4.
-------
3 Goals
3.1 Project Goals
As stated in the Introduction, the goals for this project were largely shaped by the PNA Vision. The PNA
Vision brought together a coalition of local and national stakeholders to identify community goals within
the Proctor Creek/ North Avenue watershed and to propose alternative solutions. Among the goals
identified in the PNA Vision were:
Flood reduction and management to provide capacity relief for the combined sewer system;
Cleaner surface and groundwater;
Improved streets and sidewalks; and
Economic revitalization.
By engaging a range of stakeholders, the PNA Vision was also able to propose innovative approaches to
meeting multiple community goals. One proposed approach was the creation of a network of connected
green spaces. Features such as parks, greenways, and community gardens could achieve watershed
goals, while also improving aesthetics and quality of life. Green street projects, in particular, were
highlighted as a holistic design option to serve the range of community goals.
3.2 Design Goals
Design guidance from the City's Transportation Planning Division took precedence since Boone
Boulevard is slated to undergo a road diet project. As a result, the green street features were designed
to comply with the road diet design criteria provided by the City's Transportation Planning Division,
which is described in more detail in Chapter 5.
The Stormwater Control Measures (SCM) proposed for Boone Boulevard were designed using minimum
standard #2 of the Unified Stormwater Sizing Criteria in Volume 2, Chapter 1.3.2.1 of the Georgia
Stormwater Management Manual (Atlanta Regional Commission, 2001). One of the purposes of the
sizing criteria is:
...to provide a framework for designing a Stormwater management system to remove
Stormwater runoff pollutants and improve water quality
The Water Quality Criterion states that Stormwater management facilities
treat the runoff from 85% of the storms that occur in an average year. For Georgia, this
equates to providing water quality treatment for the runoff resulting from a rainfall
depth of 1.2 inches. Reduce average annual post-development total suspended solids
loadings by 80%.
As specified, the sizing criteria will treat the runoff from 85% of storms in an average year and provide
partial retention of larger storm events to reduce downstream flooding impacts. Specifically, a design
rainfall depth of 1.2 inches was determined from the Georgia Stormwater Management Manual to
calculate the water quality treatment volume (WQV).
-------
4 Green Infrastructure Toolbox
Green infrastructure uses vegetation, soils, and natural processes to manage water within the context of
the site design. A range of green infrastructure practices can be incorporated into the urban landscape
to complement and enhance the layout of an existing or proposed site while also providing water quality
treatment and volume reduction. The following sections describe common green infrastructure
practices that are well suited for dense, urban areas and were identified as appropriate for
consideration in the Boone Boulevard Green Street project.
4.1 Bioretention Facilities
Bioretention facilities are shallow, depressed areas with a fill soil and vegetation that infiltrate runoff
and remove pollutants through a variety of physical, biological, and chemical treatment processes. The
depressed area is planted with small to medium sized vegetation including trees, shrubs, grasses, and
perennials, and may incorporate a vegetated groundcover or mulch that can withstand urban
environments and tolerate periodic inundation and dry periods. Bioretention may be configured
differently depending on the site context and design goals. This section summarizes general design
considerations for bioretention facilities, and describes two configurations designed for dense urban
areas: planter boxes and tree boxes.
Bioretention is well suited for removing stormwater pollutants from runoff, particularly for smaller
(water quality) storm events, and can be used to partially or completely meet stormwater management
requirements on smaller sites. Bioretention areas can be incorporated into a development site to
capture roof runoff and parking lot runoff and within rights-of-way to capture sidewalk and street runoff
(Figure 4-1 and Figure 4-2).
General guidelines for applying bioretention facilities are as follows:
For unlined systems, maintain a minimum of 5 feet between the facility and a building and at
least 10 feet from a building with a basement.
A surface dewatering time of no greater than 72 hours either through infiltration with soils of
sufficient percolation capacity or with an underdrain system and outlet to a drainage system.
Use of an underdrain system is very effective in areas with low infiltration capacity soils.
Planted with native and non-invasive plant species that have tolerance for urban environments,
frequent inundation, and drought conditions.
Inclusion of an overflow structure with a non-erosive overflow channel to safely pass flows that
exceed the capacity of the facility or design the facility as an off-line system.
Inclusion of a pretreatment mechanism such as a grass filter strip, sediment forebay, or grass
swale upstream of the practice to enhance the treatment capacity of the unit.
-------
Figure 4-1. Bioretention
incorporated into a
right-of-way
Figure 4-2. Bioretention incorporated into
traditional parking lot design.
Planter Box: Planter boxes are bioretention facilities contained within a concrete box, allowing them to
be incorporated into tighter areas with limited open space. Runoff from a street or parking lot typically
enters a planter box through a curb cut, while runoff from a roof drain typically enters through a
downspout. Planter boxes are often categorized either as flow-through planter boxes or infiltrating
planter boxes. Infiltrating planter boxes have an open bottom to allow infiltration into the underlying
soils. Flow-through planter boxes are completely lined and have an underdrain system to convey flow
that is not taken up by plants to areas that are appropriate for drainage away from building foundations.
Planter boxes are well suited to narrow areas adjacent to streets and buildings (Figures 4-3 and 4-4).
Figure 4-3. Planter box within
street right-of-way
Figure 4-4. Flow-through planter
box attached to building
-------
Tree Box: Tree boxes are bioretention facilities configured for dense urban areas that use the water-
uptake benefits of trees. They are generally installed along street corridors with curb inlets (Figure 4-5).
Tree boxes can be incorporated immediately adjacent to street and sidewalks with the use of a
structural soil, modular suspended pavement, or underground retaining wall to keep uncompacted soil
in its place. Tree boxes typically contain a highly engineered soil media to enhance pollutant removal
while retaining high infiltration rates. The uncompacted media allows urban trees to thrive, providing
shade and an extensive root system for water uptake. For low to moderate flows, stormwater enters
through the tree box inlet and filters through the soil. For high flows, stormwater will bypass the tree
box if it is full and flow directly to the downstream curb inlet.
Figure 4-5. Tree box using
grate inlets in street
4.2 Permeable Pavement
Conventional pavement results in increased surface runoff rates and volumes. Permeable pavements,
in contrast, allow streets, parking lots, sidewalks, and other surfaces to retain the underlying soil's
natural infiltration capacity while maintaining the structural and functional features of the materials
they replace. Permeable pavements contain small voids that allow water to drain through the
pavement to an aggregate reservoir and then infiltrate into the soil. If the native soils below the
permeable pavements do not have enough percolation capacity, underdrains can be included to direct
the stormwater to other downstream stormwater control systems. Permeable pavement can be
developed using modular paving systems (e.g., concrete pavers, grass-pave, or gravel-pave) or poured-
in-place solutions (e.g., pervious concrete or permeable asphalt).
Permeable pavement reduces the volume of stormwater runoff by converting an impervious area
to a treatment unit. The aggregate sub-base can provide water quality improvements through
filtering and enhance additional chemical and biological processes. The volume reduction and
water treatment capabilities of permeable pavements are effective at reducing stormwater
pollutant loads.
10
-------
Permeable pavement can be used to replace traditional impervious pavement for most pedestrian
and vehicular applications. Composite designs that use conventional asphalt or concrete in high-
traffic areas adjacent to permeable pavements in lower-traffic areas along shoulders or in parking
areas can be implemented to meet both transportation and stormwater management needs.
Permeable pavements are most often used in constructing pedestrian walkways, sidewalks,
driveways, low-volume roadways, and parking areas of office buildings, recreational facilities, and
shopping centers (Figure 4-6 and Figure 4-7).
General guidelines for applying permeable pavements are as follows:
Permeable pavements can be substituted for conventional pavements in parking areas, low-
volume/low-speed roadways, pedestrian areas, and driveways if the grades, native soils,
drainage characteristics, and groundwater conditions of the paved areas are suitable.
Permeable pavement is not appropriate for stormwater hotspots where hazardous materials
are loaded, unloaded, or stored, unless the sub-base layers are completely enclosed by an
impermeable liner.
The granular capping and sub-base layers should provide adequate construction platform and
base for the overlying pavement layers.
If permeable pavement is installed over low-permeability soils or temporary surface flooding is
a concern, an underdrain should be installed to ensure water removal from the sub-base
reservoir and pavement.
The infiltration rate of the soils or an installed underdrain should drain the sub-base within 24
to 48 hours.
An impermeable liner can be installed between the sub-base and the native soil to prevent
water infiltration when clay soils have a high shrink-swell potential or if a high water table or
bedrock layer exists.
Measures should be taken to protect permeable pavements from high sediment loads,
particularly fine sediment, to reduce maintenance. Typical maintenance includes removing
sediment with a vacuum truck.
II
-------
:':>/V-/^::: .^
Figure 4-6. Permeable pavement
one-way cycle track
Figure 4-7. Permeable interlocking
concrete paver parking stalls
4.3 Impervious Area Conversion
In areas where existing impervious surfaces are unutilized or unwarranted, impervious paved areas can
be converted to pervious landscaped areas. While impervious area conversion does not provide
treatment to runoff from adjacent surfaces like other green infrastructure practices it does reduces the
volume and pollutant load of stormwater as a result of land cover change. Impervious area conversion
can be used to reduce the required size of downstream stormwater control measures. Two examples of
impervious area conversion suitable for use in roadway corridors are vegetated medians (Figure 4-8) and
extended planting strips.
Figure 4-8. Conversion of impervious roadway
to vegetated center median
12
-------
5 Green Infrastructure Conceptual Design
The selection of green infrastructure practices was informed by both the project goals for the site and
the physical constraints posed by existing and future redevelopment conditions. The green
infrastructure design goals identified by City of Atlanta staff primarily included improving the aesthetics
of the roadway while simultaneously providing water quality and hydrologic benefits.
5.1 Conceptual Layout
Since Boone Boulevard is already planned to undergo a road diet project, the green street features were
designed to comply with the road diet design criteria provided by the City's Transportation Planning
Division.
Based on the aforementioned design requirements for the road diet, proposed green street features
could be located along all sections of roadway that do not require an adjacent left turn lane. In these
areas, up to 12 feet of road width is available to locate a curbside planter box, which is the City of
Atlanta's preferred practice. Given the narrow footprint available for detention and treatment within
the road corridor, planter boxes are generally limited to one side of the street. Since the existing road
crest will be preserved during the planned street improvements, the planter boxes were designed to
treat the water quality volume from one half of the roadway.
In areas where additional space is not available to treat the other half of the roadway with planter
boxes, permeable pavement is proposed for the opposite bike lane to provide adequate treatment.
Where implemented, the permeable pavement bike lanes are proposed to extend the entire block to
connect to the down gradient catch basin and simplify the construction process. As a result, the
permeable pavement infiltration capacity is typically oversized with respect to its catchment's water
quality volume. In street sections where runoff is treated by planter boxes or off-line bioretention,
impermeable asphalt is proposed for bike lanes in lieu of permeable pavement.
The City also expressed interest in installing stormwater treatment features adjacent to Boone
Boulevard in Historic Mims Park. Separate bioretention systems were proposed for the area between
Elm and Vine streets to treat runoff from the entire Sunset-Elm block, and south side of the Elm-Vine
block. This approximate half-acre grassed open area is relatively flat, devoid of utilities, and up-gradient
of existing storm sewers that connect back to the main trunk line along Vine St. Runoff from the Sunset-
Elm block could be diverted via new culverts under Boone Boulevard and Elm Street, in addition to a
new catch basin at the southwest corner of the Boone-Elm intersection. The Elm Street culvert would
discharge into a stone settling basin in the park before overflowing into a series of two bioretention cells
sized to treat the water quality volume. The second bioretention cell contains a grassed spillway that
could discharge overflow to a shared outlet structure (i.e., concrete box riser with 4-sided weir) located
in the other bioretention system treating the Elm-Vine-S drainage area. Runoff from the south side of
the Elm-Vine block could be conveyed to the park area via a curb cut and recessed concrete flume
through the sidewalk. Runoff could be conveyed through a pretreatment grass swale before entering
the bioretention cell that contains the outlet structure. All of the bioretention cells would require
perforated underdrains that connect to the outlet structure. A new reinforced concrete pipe culvert
would convey flow from the outlet structure to the existing combined sewer system running along Vine
St.
Figure 5-1 shows the proposed green street design for the Boone Boulevard project area.
13
-------
Proposed Catch
Stone Dissipation Basin " / Grass Spillway (2)
hL/' JMH
Stone Spillway (2) 1« Riser Outlet StructurelandtCulvert
Prppl^d'Street Parking
Legend
^ Storm Sewers ^^ New Culvert Impermeable One-Way Cycle Track |* J Bioretention/Planter Box
Sewer Mains New Travel Lane I Permeable One-Wfey Cycle Track I ^ Extended Planting Strip
Boone Boulevard
Green Infrastructure Design
Figure 5-1. Conceptual layout for Boone Boulevard green infrastructure practices
14
-------
5.2 Green Infrastructure Sizing
The Stormwater Control Measures (SCM) proposed for Boone Boulevard were designed using Minimum
Standard #2 of the Unified Stormwater Sizing Criteria as described in Volume 2, Chapter 1.3.2.1 of the
Georgia Stormwater Management Manual (Atlanta Regional Commission, 2001). One of the purposes of
the sizing criteria is:
...to provide a framework for designing a Stormwater management system to remove
Stormwater runoff pollutants and improve water quality
The Water Quality Criterion states that Stormwater management facilities
treat the runoff from 85% of the storms that occur in an average year. For Georgia, this
equates to providing water quality treatment for the runoff resulting from a rainfall
depth of 1.2 inches. Reduce average annual post-development total suspended solids
loadings by 80%.
The sizing criteria will treat the runoff from 85% of storms in an average year and provide partial
retention of larger storm events to reduce downstream flooding impacts. Specifically, a design rainfall
depth of 1.2 inches was determined from the Georgia Stormwater Management Manual to calculate the
water quality treatment volume (WQV), using the following equation:
wn 1.2* Rv* A
WQv =
12
Where "A" equals the drainage area in acres and "Rv" is the volumetric runoff
coefficient. Rv is calculated using the imperviousness of the drainage area:
Rv = 0.05 + 0.009*7
Where "I" is imperviousness expressed as a percent.
Table 5-1 shows the calculated water quality treatment volumes for each of the sub-catchment areas.
Table 5-2 shows the proposed sizing for the Boone Boulevard green street SCMs. All the planter boxes
and bioretention cells were designed using the typical design standard for the City of Atlanta and use a
6-inch ponding depth underlain by a 2-foot-deep soil media and associated gravel underdrain system. All
are adequately sized to treat the water quality volume. Permeable pavement bike lanes are designed to
use interlocking concrete paver blocks underlain with an 18-inch drainage/storage layer and an
associated underdrain system. As mentioned in Section 5.1, the permeable pavement bike lane
locations are proposed to extend the entire way down each block, which yield subsurface storage
volumes that exceed the targeted water quality treatment volume. The only undersized permeable
pavement bike lane is the one for the Vine-Walnut block where the drainage area delineation includes a
portion of Walnut street north of Boone Boulevard.
15
-------
Table 5-1. Existing drainage area runoff volumes
Subcatchment
Wai-Map S
Wai-Map N
Vin-Wal S
Vin-Wal N
Elm-Vin S
Elm-Vin N
Sun-Elm N&S
Gri-Sun S
Gri-Sun N
Bra-Gri S
Bra-Gri N
SCM Type
Planter Box
Permeable Pavement
Planter Box
Permeable Pavement
Bioretention
Permeable Pavement
Bioretention
Planter Box
Permeable Pavement
Permeable Pavement
Permeable Pavement
DA (ac)
0.15
0.38
0.18
0.19
0.23
0.16
0.66
0.21
0.17
0.18
0.19
WCUac-ft) WQV
0.015
0.036
0.017
0.018
0.019
0.012
0.055
0.020
0.016
0.014
0.015
(cu.ft.)
636
1,560
745
781
830
543
2,404
859
690
601
636
Table 5-2. Proposed green street SCM sizing
SCMID
Wai-Map S
Vin-Wal S
Vin-Wal N
Wai-Map N
Elm-Vin S
Elm-Vin N
Sun-Elm N & N
Gri-Sun N
Gri-Sun S
Bra-Gri S
Bra-Gri N
SCM Type Width (Ft)
Planter Box 8
Permeable Pavement 5
Planter Box 8
Permeable Pavement 5
Bioretention 552
Permeable Pavement 5
Bioretention 27
Planter Box 8
Permeable Pavement 5
Permeable Pavement 5
Permeable Pavement 5
Length (Ft)
159
299
186
377
552
300
190
215
317
383
386
Surface Storage
Area (Sq ft) Vol. (Cu ft)1
1,273 636
1,496 718
1,489 745
1,886 905
1,660 830
1,498 719
5,134 2,567
1,717 859
1,583 760
1,917 920
1,929 926
%ofWQ
Vol.
100%
46%
100%
116%
100%
133%
100%
100%
110%
180%
120%
1. Does not include water storage in bioretention media
2. Triangular dimension; width and length are base and height dimensions
16
-------
6 Green Infrastructure Technical Specifications
The purpose of this section is to provide guidance for designing the green infrastructure practices during
final design. Design criteria for the planter boxes were derived from standard details provided by the
City of Atlanta. Design of the bioretention cells and permeable pavement are based on criteria provided
in Chapter 3.2.2 and Chapter 3.3.7 of the Georgia Stormwater Manual (Vol. 2), respectively. For the
reader's benefit, design guidance for these three practices is consolidated into Table 6.1 and Table 6.2 at
the end of this section.
6.1 Common Elements
a) Soil Media
Soil media is typically specified to meet the growth requirements of the selected vegetation while still
meeting the hydraulic requirements of the system. The system must be designed to drain the surface
storage volume in no more than 48 hours. The expected infiltration rate should be at least 0.5 in/hr.
Based on research from NC State, the engineered soil mixture shall be a blend of sandy loam, loamy
sand, or loam texture with a content of fines (silt and clay) ranging from 8 to 12%. Organic matter should
compose 1.5 to 3% of the mixture to help vegetation establish and increase sorption of pollutants.
Organic material should not consist of manure or animal compost. Newspaper mulch has been shown to
be an acceptable additive.
Gradation analyses of the blended material, including hydrometer testing for clay content and
permeability testing of the soil filter material, should be performed by a qualified soil testing laboratory
and submitted to the project engineer for review. Particle gradation tests should conform with ASTM
C117/C136 (AASHTO T11/T27) and the blended material should have no less than 8% passing the 200
sieve and shall have a clay content of less than 2%. Other soil media design criteria include:
pH should be between 5.5 and 6.5, cation exchange capacity (CEC) should be greater than 5
milliequivalent (meq)/100 g soil, and a maximum soluble salts concentration of 500 ppm.
High levels of phosphorus in the media have been identified as the main cause of bioretention
areas exporting nutrients. All bioretention media should be analyzed for background levels of
nutrients. Total phosphorus should not exceed 15 ppm.
Geotextile fabric of Mirafi 170n or equivalent may be placed between the sides of the filter layer
and adjacent soil to prevent surrounding soil from migrating into the filter and clogging the
outlet. Overlap seams must be a minimum of 12 inches.
b) Underdrain
An underdrain is required in areas where existing soils have an infiltration rate less than 0.5 in/hr and
should meet the following criteria:
The underdrain piping should be 6" (4" for planter boxes) rigid Schedule 40 PVC (AASHTO M252)
and have 3/8-inch perforations spaced at 6-inch centers, with a maximum of 4 holes per row.
The total opening area should exceed the expected flow capacity of the underdrain and does
not limit infiltration through the soil media. Structure joints shall be sealed so they are
watertight.
17
-------
Internal water storage zones can be created within the bottom of the bioretention cell by
installing an upturned elbow on the underdrain where it discharges into the outlet structure.
At least one line of underdrain should be spaced at a maximum of 10 feet on center on a
minimum grade of 0.5%.
Underdrain pipes must be bedded in 10 to 12 inches of clean, well-graded ₯A" to %" washed
stone.
A choking layer composed of 2" of washed sand and 2" of #8 stone should be placed above the
gravel layer to prevent the underdrain from clogging from migrating media particles.
The underdrain must drain freely and discharge to the existing stormwater infrastructure.
c) Plant Selection
For the practice to function properly as stormwater treatment and blend into the landscape, vegetation
selection is crucial. Appropriate vegetation will have the following characteristics:
1. Plant materials must be tolerant of drought, ponding fluctuations, and saturated soil conditions
for 10 to 48 hours.
2. It is recommended that a minimum of three tree, three shrubs, and/or three herbaceous
groundcover species be incorporated to protect against facility failure from disease and insect
infestations of a single species.
3. Woody vegetation should not be specified at inflow locations.
4. Native plant species or tough/vigorous cultivars that are not invasive and do not require
chemical inputs are recommended to be used to the maximum extent practicable.
5. Additional information and guidance on the appropriate woody and herbaceous species
appropriate for bioretention in Georgia, and their planting and establishment, can be found in
Appendix F (Landscaping and Aesthetics Guidance) of the Georgia Stormwater Management
Manual, Vol. 2 (Atlanta Regional Commission, 2001).
6. After planting, the filter area should be mulched with 2-3 inches of triple-shredded hardwood
mulch. A one-time spot fertilization is optional for first-year plantings.
d) Geotechnical Investigation
A full geotechnical investigation is recommended to characterize the soils prior to final design. Pertinent
information includes permeability at each bioretention site, hydrologic soil group type, depth to water
table, and the presence of expansive soils. If expansive soils are present, bioretention design should
include an impermeable barrier since the proposed bioretention cell locations are adjacent to
infrastructure such as roads and buildings.
e) Maximizing Infiltration
SCMs implemented over soils with low permeability can be hydrologically connected to SCMs
implemented over high permeability soils through the underdrain systems. Hydrologically connecting
the SCMs where infiltration will be limited to locations where infiltration will be higher will maximize the
treatment capacity of the site providing a greater overall infiltration capacity.
-------
Table 6-1. Traditional bioretention/planter box specifications
1. Siting Setbacks
Pavement
Building
Property lines/ROW
No requirement
No requirement with lined bottom; otherwise,
Basement: > 10 feet
No Basement: > 5 feet
> 2 feet / >0 feet
2. Volume
Bottom slope
Side slopes
Freeboard
Flat
Bioretention: 2H:1V or flatter
Planter Box: Vertical|retaining wall
6 to 12 inches
3. Vertical Component
Surface Storage
Growing Layer
Filter Layer
Drainage Layer
Native Material
6 inches
BR: > 48 inches soil media;
PB: > 24 inches soil media;
3 inches of mulch, max
2 to 4 inches of clean medium sand (ASTM c-33) over 2 to 3 inches of #8 or #78
washed stone when drainage layer is used
Recommended 12 to 30 in. of clean coarse aggregate AASHTO #4, #5, or equivalent
Test infiltration; >l/2 in/hr if designing with infiltration
4. Drainage
Inlet Curb inlet; sheet flow through grass filter strip downspout w/ energy dissipation
Underdrain 6-inch (BR) or 4-inch (PB) perforated PVC placed to meet dewatering requirement if
needed; cleanout at terminal ends and every 250-300 feet
Outlet Required to meet release rates
Overflow Downstream inlet or catch basin set 6 to 12 inches above soil surface and connected
to storm drainage network
Infiltration Meet water quality volume requirement
Dewatering Surface: < 24 hours
Sub-surface: < 72 hours
5. Composition
Surface Treatment
Soil Media
Side Slopes
Mulch
Vegetation and mulch
With or without an underdrain, meets dewatering requirement; supports plant
growth
Grass or mulch
Triple-shredded hardwood
6. Pollutant
Pretreatment
Required. May include grass filter strip, stone trench, forebay, sump inlets
7. Maintenance
Access Able to be accessed by a vehicle
Requirements Designed and maintained to improve water quality; Maintenance plan should be in
place
BR = bioretention; PB = planter boxes
19
-------
IMPERVIOUS UNER
WHERE REQUIRED BY
CITY ENGINEER
_ UNCOMPACTED SUBGRADE
SECTION A-A1
(PLANTER WITHOUT ON-STREET PARKING^
2"-3" CHOKER
STONE {§"- J-)
OR RLTER FABRIC
1j" -}" WASHED
STONE DRAINAGE BED
CHOKER STONE
OR FILTER FABRIC
4" PERFORATED
UNDER DRAIN
WHERE NEEDED
Source: City of Atlanta
Figure 6-1. Typical planter box
20
-------
Table 6-2. Permeable pavement
1. Siting Setbacks
Pavement
Building
Property lines/ROW
No requirement
No requirement with lined bottom; otherwise,
Basement: > 10 feet
No Basement: > 5 feet
> 2 feet / >0 feet
2. Volume
Slope
Side slopes
Freeboard
Less than 0.5 percent
Not applicable
Not applicable
3. Vertical Component
Surface Layer
Growing Layer
Bedding
Base Layer
Native Material
Interlocking Concrete Pavers; Concrete Grid Pavers; Plastic Grid Pavers;
Concrete; Asphalt
Not applicable
1) Perm. Interlocking Cone. Pavers: 1.5 to 3 inches of #8 or #78 washed
stone
2) Concrete and Plastic Grid Pavers: 1 to 1.5 inches of bedding sand
3) Permeable Concrete and Asphalt: None
12 to 30 in. of clean aggregate AASHTO #56 or equivalent; thickness
depends on strength/storage needed; install 30 mil geotextile liner
where aggregate meets soil
Compacted as sub-base
4. Drainage
Inlet
Outlet
Overflow
Infiltration
Dewatering
5. Composition
Surface Treatment
Pavement surface
Required to meet release rates
Downstream inlet
Meet water quality volume requirement
< 72 hours
For interlocking or grid-type pavers use fine aggregate, coarse sand, or
top soil & grass in openings
6. Pollutant
Pretreatment
Divert runoff from sediment sources away from pavement
7. Installation and Maintenance
Installation
Load Bearing
Requirements
Per manufacturer's recommendation
Designed for projected traffic loads using AASHTO methods
Designed and maintained to improve water quality; Maintenance plan
should be in place
Notes: A reinforced concrete transition width (12 -18 inches) is required where permeable pavement meets adjacent non-
concrete pavement or soil.
21
-------
- Permeable 1
Concrete Paver (PICP)
-Filler Material
(gravel or sand)
^ Concrete Transition, strip
-B.eddi.kvg Layer
Gqravel orsand)
Stru.ctw.raL Layer
(waskied k
Pervious concrete
Con.ar
(As Rec[u.i.red)
bed "Base soil
, Strip
Beddlw-g Layer
L, washed IA.O 2 stotve)
Struttural Layer
(wcfshed IA.
ijeotextiLe
bed Base soil
Figure 6-2. Permeable interlocking
concrete pavers
Figure 6-3. Pervious concrete
22
-------
7 Operations and Maintenance
Maintenance activities should be focused on the major system components, especially landscaped areas
and permeable pavement. Landscaped components should blend over time through plant and root
growth, organic decomposition, and should develop a natural soil horizon (Table 7-1). The biological and
physical processes over time will lengthen the facility's life span and reduce the need for extensive
maintenance. The primary maintenance requirement for permeable pavement consists of regular
inspection for clogging and sweeping with a vacuum-powered street sweeper (Table 7-2).
Irrigation for the bioretention systems might be needed, especially during plant establishment periods
or in periods of extended drought. Irrigation frequency will depend on the season and type of
vegetation. Native plants will likely require less irrigation than nonnative plants.
The following tables outline the required maintenance tasks, their associated frequency, and notes to
expand upon the requirements of each task.
Table 7-1. Bioretention operations and maintenance considerations
Task
Monitor
infiltration and
drainage
Pruning
Mowing
Mulching
Mulch removal
Frequency
Maintenance notes
Watering
Fertilization
Remove replace
dead plants
Inlet inspection
Outlet inspection
1 time/year
1-2 times/year
2-12 times/year
1-2 times/year
1 time/2-3 years
1 time/2-3 days for first 1-2 months;
sporadically after establishment
1 time initially
1 time/year
Once after first rain of the season, then
monthly during the rainy season
Once after first rain of the season, then
monthly during the rainy season
Inspect drainage time (12-24 hours). Might have to
determine infiltration rate (every 2-3 years).
Turning over or replacing the media (top 2-3
inches) might be necessary to improve infiltration
(at least 0.5 in/hr).
Nutrients in runoff often cause bioretention
vegetation to flourish.
Frequency depends on the location, plant selection
and desired aesthetic appeal.
Recommend maintaining l"-3" uniform mulch
layer.
Mulch accumulation reduces available water
storage volume. Removal of mulch also increases
surface infiltration rate of fill soil.
If drought conditions exist, watering after the initial
year might be required.
One-time spot fertilization for first year vegetation
(optional).
Within the first year, 10% of plants can die. Survival
rates increase with time.
Check for sediment accumulation to ensure that
flow into the retention area is as designed. Remove
any accumulated sediment.
Check for erosion at the outlet and remove any
accumulated mulch or sediment.
23
-------
Task
Frequency
Maintenance notes
Underdrain
inspection
Miscellaneous
upkeep
Once after first rain of the season, then Check for accumulated mulch or sediment. Flush if
yearly during the rainy season water is ponded in the bioretention area for more
than 72 hours.
12 times/year
Tasks include trash collection, plant health, spot
weeding, and removing mulch from the overflow
device.
Table 7-2. Permeable pavement operations and maintenance considerations
Task
Frequency
Maintenance notes
Impervious to Pervious
interface
Vacuum street sweeper
Replace fill materials
(applies to pervious
pavers only)
Miscellaneous upkeep
Once after first rain of the
season, then monthly
during the rainy season
Twice per year as needed
1-2 times per year (and
after any vac truck
sweeping)
4 times per year or as
needed for aesthetics
Check for sediment accumulation to ensure that flow
onto the permeable pavement is not restricted.
Remove any accumulated sediment. Stabilize any
exposed soil.
Portions of pavement should be swept with a
vacuum street sweeper at least twice per year or as
needed to maintain infiltration rates.
Fill materials will need to be replaced after each
sweeping and as needed to keep voids with the
paver surface.
Tasks include trash collection, sweeping, and spot
weeding.
24
-------
8 Capital Cost Estimates
The cost estimates for implementing the green street features along Boone Boulevard are found in
Table 8-1.
Table 8-1. Cost estimate for implementation of Boone Boulevard green infrastructure
Item No
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
Description
Preparation
Traffic Control
Site Preparation
Curb and Gutter Removal
Excavation and Removal
Remove Asphalt Pavement & Base
Driveway Accommodation
Traditional Bioretention/Planter Box
Fine Grading
Soil Media - 2' Depth
Filter Layer (sand and No. 8 stone)
Drainage Layer - 14" Depth
Grouted River Rock
Baffles
Vegetation
Mulch
Curb and Gutter
Slotted 4" PVC Underdrain
Underdrain Cleanouts
Permeable Pavement
Permeable Pavement
Structural Layer (washed no 57)
Subbase Layer (washed no 2)
Concrete Vertical Curb
Slotted 4" PVC Underdrain
Underdrain Cleanouts
Vegetated Medians
Curb and Gutter
Topsoil (1.51 Depth)
Vegetation
Structures
4'x4' Concrete Catch Basin
12" RCP
Construction Subtotal
Planning (20% of subtotal)
Mobilization (10% of subtotal)
Bond (5% of subtotal)
Construction contingency (10% of subtotal)
Construction Total
Design (40% of Construction Total)
Total Cost
Quantity
15
560
2,312
2,568
4
21,583
835
139
489
314
51
10,959
68
608
983
21
10,310
286
286
2,062
2,062
52
1,619
462
8,322
1
145
Unit
day
LF
CY
SY
EA
SF
CY
CY
CY
SF
EA
SF
CY
LF
LF
EA
SF
CY
CY
LF
LF
EA
LF
CY
SF
EA
LF
Unit Cost
$1,000.00
$6.00
$22.00
$10.00
$700.00
$0.72
$40.00
$45.00
$45.00
$15.00
$125.00
$4.00
$55.00
$7.90
$8.00
$12.00
$8.00
$45.00
$45.00
$8.50
$8.00
$12.00
$7.90
$24.00
$4.00
$3,500.00
$31.26
Total
$15,000
$3,359
$50,862
$25,678
$2,800
$15,540
$33,402
$6,263
$21,983
$4,710
$6,375
$43,837
$3,721
$4,802
$7,864
$246
$82,477
$12,887
$12,887
$17,526
$16,495
$619
$12,790
$11,096
$33,288
$3,500
$4,533
$454,543
$90,909
$45,454
$4,545
$90,909
$686,359
$274,544
$960,903
25
-------
Costs are estimated based on the existing site conditions, account for the potential necessity of under-
drains and are sized to capture 1.2 inches of runoff from impervious surfaces. The costs include both
construction of the green infrastructure practices as well as site preparation, mobilization, etc., but do
not implementation of the road diet plan including; roadway re-surfacing, re-striping, signage, and
improvements to existing sidewalk to comply with the American Disabilities Act. Costs assume that no
utility removal/rerouting will be required. In the event that detailed site survey and final design
indicates the need for utility modification or other infrastructure improvements these costs may need
revision.
26
-------
9 References
Anderson, L, and H. Cordell. 1988. Influence of Trees on Property Values in Athens, Georgia (USA): A
Survey on Actual Sales Prices. Landscape and Urban Planning 15(1-2):153-164.
Atlanta Regional Commission, 2001. Georgia Stormwater Management Manual: Volume 2 Technical
Handbook. Available at http://atlantaregional.com/environment/aeorgia-stormwater-manual.
City of Atlanta. 1995. Simpson Redevelopment Plan.
City of Atlanta. 2006 Simpson Road Corridor Redevelopment Plan Update.
Espey, M., and K. Owusu-Edusei. 2001. Neighborhood Parks and Residential Property Values in
Greenville, South Carolina. Journal of Agricultural and Applied Economics 33(3):487-492.
Hastie, C. 2003. The Benefit of Urban Trees. A summary of the benefits of urban trees accompanied by a
selection of research papers and pamphlets. Warwick District Council. Available at
http://www.naturewithin.info/UF/TreeBenefitsUK.pdf. Accessed September 2010.
Hobden, D., G. Laughton, and K. Morgan. 2004. Green Space Bordersa Tangible Benefit? Evidence
Chen, J., and K. Hobbs. 2013. Rooftops to Rivers II: Green strategies for controlling stormwater and
combined sewer overflows. Natural Resource Defense Council. October 2013. Available at
http://www.nrdc.orci/water/pollution/rooftopsii/.
Kou, F., and W. Sullivan. 2001a. Environment and Crime in the Inner City: Does Vegetation Reduce
Crime. Environment and Behavior 33(3):343-367.
Kuo, F., and W. Sullivan. 2001b. Aggression and Violence in the Inner City: Effects of Environment via
Mental Fatigue. Environment and Behavior 33(4):543-571.
Kuo, F. 2003. The Role of Arboriculture in a Healthy Social Ecology. Journal of Arboriculture 29(3).
New Yorkers for Parks and Ernst & Young. 2003. Analysis of Secondary Economic Impacts Resulting from
Park Expenditures. New Yorkers for Parks, New York, NY.
Park Pride. 2011. Proctor Creek North Avenue Watershed Basin: A Green Infrastructure Vision. Available
at http://www.i3arki3ride.orci/ciet-involved/communitv-i3rocirams/i3ark-visionina/content/more-
info/2010 pna overview.pdf. Accessed September 2012.
Pincetl, S., J. Wolch, J. Wilson, and T. Longcore. 2003. Toward a Sustainable Los Angeles: A Nature's
Services Approach. USC Center for Sustainable Cities, Los Angeles, CA.
Shultz, S., and N. Schmitz. 2008. How Water Resources Limit and/or Promote Residential Housing
Developments in Douglas County. University of Nebraska-Omaha Research Center, Omaha, NE.
. Accessed September 1, 2008.
Voicu, I., and V. Been. 2009. The Effect of Community Gardens on Neighboring Property Values. Real
Estate Economics 36:2(241-283).
27
-------
Wachter, S. M., and G.W. Bucchianeri. 2008. What is a Tree Worth? Green-City Strategies and Housing
Prices. Real Estate Economics, Vol. 36, No. 2, 2008. Available at SSRN:
http://ssrn.com/abstract=1084652
Ward, B., E. MacMullan, and S. Reich. 2008. The Effect of Low-impact Development on Property Values.
ECONorthwest, Eugene, Oregon.
Wolf, K.1998. Urban Nature Benefits: Psycho-Social Dimensions of People and Plants. Human Dimension
of the Urban Forest. Fact Sheet #1. Center for Urban Horticulture. University of Washington,
College of Forest Resources.
Wolf, K. 2008. With Plants in Mind: Social Benefits of Civic Nature. Winter 2008. Available at
www.MasterGardenerOnline.com. Accessed December 2012.
28
-------
Appendix A Proctor Creek/North Avenue Needs Assessment
Several studies in the Proctor Creek/North Avenue (PNA) watershed basin have identified social,
economic, and environmental needs along major road corridors. These studies include:
2004 Vine City Redevelopment Plan
2009 Vine City/Washington Park Livable Centers Initiative (LCI)
1998 and 2006 updates of the English Avenue Community Redevelopment Plan
Atlanta Beltline Redevelopment Plan
Northside Drive Corridor Plan
Simpson Road Corridor Redevelopment Plan Update
2012 Proctor Creek Microbial Sampling Study
2011 Proctor Creek - Headwaters to Chattahoochee River - Watershed Improvement
Plan (Atlanta Regional Commission)
A document produced in 2010 by Park Pride, Proctor Creek North Avenue Basin: A Green Infrastructure
Vision (PNA Vision), presents the highlights of most of these studies and presents concept plans for four
demonstration sites and five catalyst sites, all based on green infrastructure. The needs addressed in
these prior studies can help inform the selection of locations to implement green infrastructure projects.
Some of these studies also identify improvement projects that are in the planning stages, which may
help identify opportunities to complement existing plans, where feasible, or direct attention away from
areas where planned projects will sufficiently meet the needs of the area.
Needs include:
1. Flood reduction and management/capacity relief for the combined sewer system
2. Cleaner surface and groundwater
3. Improved streets and sidewalks
4. Economic revitalization
The first two needs can be appropriately evaluated by subwatersheds identified in Figure 1. The last two
needs are discussed in the prior studies in terms of neighborhoods and street corridors, and are more
appropriately characterized and evaluated in these terms. The needs are discussed in detail in the
following sections.
Flood Reduction and Management/Capacity Relief for the Combined Sewer System
Flood reduction and management is the primary need in the project area. Green infrastructure projects
can alleviate flooding by directing runoff to bioswales, rain gardens, and other stormwater control
features in the landscape. Directing flow away from homes and infrastructure will reduce nuisance
flooding. Capturing large flows and releasing the water over an extended period of time will also provide
relief to the combined sewer system.
The Vine City Livable Cities Initiative study notes that a flood following a major rainfall in September of
2002 resulted in the declaration of a state of emergency and the flooding of 169 homes in and around
the study area. Some residents were evacuated by boat. As part of the response to the disaster, the city
purchased land south of Joseph E. Boone Boulevard and demolished the houses in that area.
A-l
-------
The area bounded by Simpson, Walnut, Thurmond, and Sunset Streets was designated as a Flood
Recovery area by the City of Atlanta. This includes parts of subwatersheds 215 and 105. The blocks
boarded by Simpson, Elm, Walnut and Thurmond Streets were identified for open space and residential
development due to this area being prone to flooding. These areas were identified as projects H4 and P6
in the 2004 Vine City Redevelopment Plan, and are part of the Boone Park East demonstration project in
the PNA Vision document. The City of Atlanta Department of Watershed Management owns two parcels
(approximately 12 acres) that are included in this project area. This is a prime site for the green
infrastructure improvements, as it typically floods and is already owned by a City agency (PNA Vision).
Much of the area to the immediate east of the Atlanta BeltLine, in subbasin 135, consists of
underground streams, sewer overflows, and areas of chronic flooding. Many of the area's houses
experience continued stormwater flooding and sewer backup issues (PNA Vision). The PNA Plan for the
area named "Valley of Hawks" calls for a considerable amount of area immediately adjacent to the
Atlanta Beltline to be developed as green space, green infrastructure, and marsh wetlands).
Subwatershed 105, which is known locally as The Gulch is the largest and most impervious sub-
watershed in the PNA watershed. It is the source of is approximately 25% of all the flood runoff from the
total project area (assumes subwatershed 105 corresponds to subwatershed D in PNA Vision). The Gulch
was a major source of water that flooded the Vine City and English Avenue neighborhoods in 2002 (PNA
Vision).
Subwatershed 215, in the northeast corner of the project area has a highly impervious industrial base
along the old rail lines and spurs, and south of Donald Lee Hollowell Drive/Bankhead Highway. This
subwatershed needs storage for approximately 17 million gallons in cisterns or ponds (PNA Vision)
(assumes subwatershed 215 corresponds to subwatershed K in PNA Vision).
Cleaner Surface and Groundwater
The PNA study area needs cleaner surface and groundwater in order to improve the health and safety of
the community (Park Pride, 2011). Water quality impairments in the study area are primarily due to
urban runoff. Pollutants such as pesticides, herbicides, oils, grease, and sediment wash off of the
landscape and into the stream system. A visual survey was conducted in 2009 to identify possible
sources of pollution along Proctor Creek, from its headwaters to the Chattahoochee River (Proctor Creek
Watershed Improvement Plan). The survey revealed potential non-point sources of pollution, including
Urban runoff
Aging or previously repaired sanitary sewer lines that cross the creek
Signs of terrestrial and aquatic wildlife activity that can contribute fecal bacteria
Domestic animals with access to or in close proximity of, the creek, which can be a source of
fecal bacteria
Areas where erosion control could be improved
Excessive amounts of trash and debris that had either washed into the creek or been
deliberately placed there
Escherichia coli (E. coli) and fecal coliform bacteria are pollutants of concern in parts of the Proctor
Creek basin. Proctor Creek is an impaired stream, from its headwaters to the Chattahoochee River. The
segment is listed for not meeting State water quality requirements for fecal coliform. A Proctor Creek
Microbial Sampling Study was conducted by EPA in 2012 to determine if Proctor Creek and its tributaries
A-2
-------
are experiencing seasonal bacterial impairment and whether the source is human or animal. E. coli was
chosen as the parameter of concern rather than the State's fecal coliform standard because studies have
shown E. coli to be a better indicator of potential harmful pathogens in a waterbody. Results of the
study showed very high levels of bacteria originating from human sources at monitoring station #3,
which is outside of the project study area, and immediately downstream of a recently separated
combined sewer overflow (CSO) facility. Further downstream, monitoring station #4 shows slightly
lower concentrations of bacteria originating from human sources, but concentrations that are much
higher than the other sample stations in the study. Station #4 is where Proctor Creek crosses North
Avenue, and is within the PNA study area (Subbasins 135 and 209). It appears that elevated levels at
station #4 are a result of the recently separated CSO facility upstream of station #3.
Green infrastructure measures that divert water into vegetated areas such as bioswales, tree boxes, or
rain gardens allow pollutants to biodegrade or to be filtered to some extent before the water enters
surface and groundwater. These measures can also reduce CSO events downstream by detaining storm
flow volumes and providing relief to the combined sewer system.
Improved Streets and Sidewalks
Based on the lack of any recent redevelopment or revitalization, it is likely that streets and sidewalks are
in need of repair throughout the study area (Park Pride, 2011). A thorough examination of these needs
was made for the Vine City neighborhood. Green infrastructure can be used to improve drainage off of
streets and sidewalks, and it can also improve the aesthetic appeal of a neighborhood and improve
safety. Some of the measures that can be used to improve streets are curb cuts that direct water into
bioswales, rain gardens, or street islands; permeable pavement that allows water to seep into the soil;
and traffic calming devices to make neighborhoods more pedestrian-friendly.
Within the study area of the 2004 Vine City Redevelopment Plan sidewalks were found to be missing in
numerous locations, and a high number of pedestrians were observed in the neighborhood. The lack of
sidewalks presents a challenge to school age children walking to Bethune Elementary and Kennedy
Middle schools. In addition, there are numerous streets in the neighborhood in need of infrastructure
improvements due to pot holes, poor drainage and lack of overall maintenance. The 2004 Plan identifies
specific streets and sidewalks that are missing or in need of repair.
Economic Revitalization
Economic revitalization is needed throughout most of the project study area. An exception may be the
area south of Martin Luther King Drive, which is largely occupied by a concentrated group of colleges
and universities.
Downtown Atlanta is in need of greater connectivity options to the various transit services that exist
today, as well as a hub for future transit. A multi-modal passenger terminal (MMPT) is proposed in the
area known as the "gulch," just west of the Metropolitan Atlanta Rapid Transit Authority's (MARTA) Five
Points station, and south of the downtown Atlanta Central Business District. It will be a hub for existing
and proposed multi-modal transit networks. Green infrastructure in the area around the proposed hub
would be a good way to build on this investment in the community, by encouraging economic growth
and making the area an attractive destination.
The Simpson Road Corridor Redevelopment Plan Update discusses the demise of Simpson Road from its
heyday of the 1950s and 1960s. It was a street that equaled Peachtree Street in Buckhead today with its
A-3
-------
thriving commercial activities, notable residential dwellings, and schools. Like other predominately
African American streets, Simpson Road had many thriving African American businesses ranging from
restaurants, inns and lounges, service stations, barber and beauty shops and tailor shops. Today the
Simpson Road corridor has an abundance of abandoned and underutilized buildings and a perception of
higher than average crime, as well as a high concentration of below-market rate housing and lower
income characteristics. The Redevelopment Plan is a visionary yet achievable blueprint for revitalizing
the corridor with respect to its historic context and physical character.
The Northside Drive Corridor Plan (1995) recognizes a need to accommodate and plan for future growth
by improving the corridor to a six-lane boulevard, improving transit connections to downtown and
Midtown, and supporting walkability through the corridor (referred to in the Simpson Road Corridor
Redevelopment Plan Update).
Redevelopment is needed where the proposed Atlanta Beltline crosses Simpson Road near the existing
MARTA alignment. The Beltline Redevelopment Plan (2005) calls for a redevelopment node at this
location that will include significant medium density mixed-use redevelopment between Herndon
Elementary School and Mayson Turner Road (northern section), a major expansion of Maddox Park, and
the possibility of a new combined MARTA rail and Beltline transit station at the corner of Simpson Road
and Mayson Turner Road (southern section). The Beltline plan also recommends a series of
transportation improvement projects in and around the Simpson area to complement the goals of the
Beltline project, address the physical changes required by the project, and mitigate potential adverse
traffic impacts of the Beltline project.
The PNA Vision notes the largely vacant southeast corner of North Avenue and Northside Drive, vacant
businesses along Boone Street, and vacant land in subwatershed J (subwatershed 215), where a large
area of public housing was recently torn down.
Prioritization Criteria
The project team will conduct a field evaluation of potential sites for green infrastructure projects,
focusing on the demonstration sites and catalyst sites identified in the PNA Vision document. Following
the field evaluation, the sites will be prioritized based on the value they will provide and degree to which
they meet the needs of the Proctor Creek. Criteria that may be used to prioritize sites include:
Construction feasibility
Property ownership (public or private)
Flood reduction potential
Potential to improve surface and groundwater quality
Opportunity to improve streets or sidewalks
Economic revitalization potential
Project value (cost/benefit)
A-4
-------
Subwatersheds
Limited Access
Highway
Major Road
Proctor Creek - Green Infrastructure
General Area Map
Figure A-l. PNA study area
A-5
-------
This page is intentionally blank.
A-6
-------
Appendix B Proctor Creek/ North Avenue Project Prioritization Summary
On October 15 and 16, 2012, the project team conducted a field evaluation of potential sites for green
infrastructure projects within the Proctor Creek/North Avenue (PNA) watershed basin as a part of the
Environmental Protection Agency (EPA) 2012 Green Infrastructure Technical Assistance Program. In
addition, the project team hosted a public meeting with key stakeholders on October 16, 2012 to discuss
the preliminary field evaluation results and to help inform the prioritization criteria for project selection.
This memo summarizes the findings of the field evaluation, development of prioritization criteria, and
subsequent prioritization of identified green infrastructure opportunities within the PNA.
Field Evaluation
The field evaluation primarily was focused on demonstration sites and catalyst sites identified in the
PNA Vision document produced by Park Pride in 2010. However, two additional Green Infrastructure
opportunities, (Joseph E. Lowery Boulevard and Lindsey Street) were identified by the field crew for
consideration and were discussed during the stakeholder meeting. The project team worked with the
City and Park Pride to define a set of field reconnaissance guidelines and field forms to assess each of
the Green Infrastructure opportunities identified in the PNA Vision document. The field crew consisted
of two technical experts (Jonathan Smith and Eric Byrne), Walt Ray with Park Pride, Susan Rutherford
with the City of Atlanta, and many other stakeholder and expert advisors at various times during the
field evaluation. The field crew located and assessed each of the Green Infrastructure opportunities
identified in the PNA Vision document. During the field visit, the team evaluated each Green
Infrastructure opportunity to define general site attributes, constraints, project understanding, and
construction feasibility. For each site, the field crew took notes and collected photographic
documentation.
Some of the sites were removed from consideration in the prioritization matrix upon the field
assessment due to various site constraints, which included potential utility conflicts, insufficient
drainage area, inadequate gradients, etc. Utility conflicts were evaluated based on GIS data layers or the
observation of aboveground utility features such as power poles, catch basins, or manholes. In addition,
some of the sites were removed from consideration because they were deemed to be outside the Green
Infrastructure objectives of the study. Out of the initial 18 sites evaluated in the field, 6 were ultimately
selected for consideration in the prioritization matrix. Two additional sites were added during the field
evaluation, taking the total to 8 sites that were discussed during the stakeholder meeting and included
in the final prioritization matrix. The final 8 sites are listed in Table B-l along with a short project
description.
Table B-l. 8 Projects for Consideration in the Prioritization Matrix
Project ID Project Location Project Description(s)
Boone Street: Green Street Green street retrofit between beltline and Northside
Demonstration Drive.
Boone Park East: Demonstration Project Pond: water storage feature and park with community
garden(s) and open play space for recreation. Project
may incorporate bypass of runoff from large parking lot
to the north into the project area for storage and
treatment.
B-l
-------
Project ID Project Location Project Description(s)
E Vine City Park Extension Expansion of Vine City Park and implementation of a
water storage feature
G Boone Park West: Demonstration Site Pond: water storage feature and park
H Bone Park West Pond: water storage feature between Cairo Street and
Joseph Lowery Boulevard
I English Avenue School: Demonstration Community garden, rainwater harvesting, porous
Site concrete parking, recreation (playground and basketball
court)
New-O Joseph Lowery Boulevard Green street retrofit of portion of Lowery Boulevard
New-P Lindsey St. Park and water storage feature between Lindsay St. and
Oliver St. Project will implement several off-street
bioretention facilities in a planned community park.
Stakeholder Meeting
The project team coordinated a stakeholder meeting on October 16, 2012 at the Fulton County
Neighborhood Union Health Center in the PNA watershed basin. The meeting was well attended and
included city officials, community leaders, and representation from organizations such as Park Pride,
Atlanta Beltline, City of Atlanta Planning and Community Development, and others. The meeting
consisted of a short presentation about each of the project opportunities, followed by a discussion to
promote an exchange of ideas and concepts, and finished with a list of priorities and weighting factors
developed by the meeting participants.
One of the primary goals of the stakeholder meeting was to develop a list of prioritization criteria based
on input from stakeholders and project team members. Meeting attendees initially identified a list of
over twenty criteria. Following several iterations of attributes considered for inclusion, the final list was
narrowed to 12 priority criteria. Each of the prioritization criteria that made the final list are described
below in no particular order.
Drainage Area/Stormwater Evaluates the potential for the proposed project to
Storage Potential reduce runoff volume discharging to the downstream
stormwater system.
Community Evaluates the likelihood that the project will be
Acceptability/Partnerships embraced or accepted by the local community and
utilize existing or potential partnerships with existing
community groups or initiatives.
Operations & Maintenance Evaluates the level of operations and maintenance that
would be required for the project long term.
Greenspace/Recreation Evaluates the green space or recreational opportunities
provided by or incorporated into the project.
B-2
-------
Implementation Timeline
Water Quality Treatment
Potential
Project Value
Existing Infrastructure
Connection/Ongoing Public
Initiatives
Aesthetics
Displacement Minimization
Streets and Sidewalks
National/Regional Showcase/
Destination/Visibility
Evaluates the potential for the project to be
implemented in a short timeframe.
Evaluates the potential of the project to reduce
pollutant loading to Proctor Creek.
Represents the cost-benefit of the project to address
overall project goals. This criteria relies heavily on the
professional judgment of the evaluation team in
estimating the
Represents the potential for the project to be integrated
into current infrastructure or public initiatives.
Evaluates the potential impact of the project to improve
or enhance community aesthetics
Evaluates the potential impact of the project on existing
residents and community activities. An example of
displacement is the removal of a recreational amenity
such as a playground or sports court for the purpose of
constructing a stormwater BMP.
Evaluates how the project integrates into planned street
and sidewalk improvements.
Potential for the project to become a showcase site
Upon selection of the 12 prioritization criteria, meeting attendees identified the six criteria of greatest
importance for the selection of a green infrastructure project to proceed to conceptual design phase
within the PNA. These factors were ranked and are incorporated into the prioritization and ranking
system described below.
Results and Discussion
After the prioritization attributes were selected, a scoring and ranking system was determined based on
input from stakeholders, team members, and the twelve prioritization attributes. Some of these
attributes, like "Streets and Sidewalks Improvements" are qualitative and thus involve only a "yes" and
"no" scoring criteria while attributes like "Drainage Area/Stormwater Storage Potential" are
quantitative. It should be noted however, that for the quantitative attributes, professional judgment
and experience were used in lieu of engineering calculations due to time, budget, and scope constraints.
Scoring the project opportunities for the attributes also required threshold criteria (ranges of values)
developed from all the site attribute values. Thresholds were selected to assign scores to ranges of
attribute values based on a weighted ranking of the attribute values. For each project opportunity, total
scoring was based on a total maximum score of 100 points with each attribute receiving a possible score
B-3
-------
between 0 and 10. Since there are twelve prioritization attributes and some attributes have more
importance for implementation than others, the project team applied weighting factors to each
attribute to ensure that the maximum possible score equals 100. The weightings were based on the
relative importance of the attribute to overall achievement of the goals and objectives. Each
prioritization attribute and its associated scoring criteria are shown in the tables below, and the final
weighted scoring matrix is shown in Table B-2.
It is important to note that the project scoring results are heavily dependent on the prioritization criteria
and weighting developed as a part of the stakeholder meeting. While the Boone Park East
Demonstration project achieved the highest ranking of the 8 green infrastructure projects evaluated
during this process, it is the project team's assessment that the project may not be the best candidate
project to meet the objectives of the EPA Green Infrastructure Partners Program.
B-4
-------
Scoring factors for the twelve
Drainage Area/
Stormwater Storage Potential
None
Interception
Infiltration/Bioretention
Small Storage
Medium Storage
Large Storage
Water Quality Treatment
Potential
Minimal
Moderate
Intensive
Street & Sidewalk
Improvements
No
Yes
Project Value
High
Medium
Low
priority criteria
Score
0
1
2.5
5
7.5
10
Score
0
5
10
Score
0
10
Score
10
7.5
5
Community
Acceptability
No
Yes
No
Yes
Existing Infrastructure
Connection
No
Yes
No
Yes
Greenspace
No
Yes
No
Yes
Aesthetics
Low
Medium
High
Partnerships
No
No
Yes
Yes
Ongoing Public
Initiatives
No
No
Yes
Yes
Recreation
No
No
Yes
Yes
Score
0
5
10
Score
0
5
5
10
Score
0
5
5
10
Score
0
5
5
10
Operations &
Maintenance
Intensive
Score
Moderate
Minimal
10
Nat'l/Reg. Showcase/
Destination/Visibility
Score
Low
Medium
High
10
Implementation Timeline Score
Long
0
Medium
Short
10
Displacement Required Score
Yes
No
0
10
B-5
-------
Table B-2. Weighted rankings
Weighting
9
Ol
'E
Q.
C
D
E
G
H
1
New-O
New-P
£
_o
1
Si,
a.
Boone Street:
Green Street
Demonstration
Boone Park East:
Demonstration
Project
Vine City Park
Extension
Boone Park West:
Demonstration Site
Boone Park West
English Avenue
Priorities
2
01
00
E
^ o
Drainage Area;
Stormwater St
Potential
10
20
10
10
10
1
Community
Acceptability/
Partnerships
10
10
5
5
5
School: 5 10
Demonstration Site
Joseph Lowery
Boulevard
Lindsey St.
5
10
5
10
1.5
Operations &
Maintenance
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
1
Greenspace/
Recreation
0
10
0
5
5
5
0
5
1
£
Implementatio
Timeline
10
10
10
5
5
10
5
10
0.5
4-»
£
Ol
Water Quality
Treatment Pot
2.5
5
2.5
5
5
0
2.5
5
0.5
Project Value
5
5
2.5
2.5
2.5
2.5
3.75
5
1.5
01
3 M
t3 o
EDO in
r- fll
Existing infrast
Connection/Or
Public Initiativ
15
7.5
7.5
0
0
15
7.5
7.5
0.25
Aesthetics
2.5
2.5
1.25
2.5
2.5
1.25
2.5
1.25
0.25
Displacement
Minimization
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
0.25
J3
i
Streets & Sidev
improvements
2.5
0
0
0
0
0
2.5
0
0.25
to :=
1 '«
Nat'l/Reg. Sho
Destination/Vi
1.25
2.5
0
0
0
1.25
1.25
0
o
o
ii
_£
Ol
o
u
i-
68.75
82.5
48.75
45
45
60
45
63.75
B-6
-------
Appendix C Conceptual Design Layouts
c-i
-------
Site Location
MBL
NA
Date of Field Visit 10/15/2012
Field Visit Personnel JS, EB, WR
Major Watershed
Proctor Cr.
Latitude
Longitude
Street Address
Landowner
33° 45' 48" N
84° 24' 28" W
NW Boone Blvd.
City of Atlanta
Watershed Characteristics
Watershed Area, acres 2.56
Proposed Characteristics
Existing Site Description: The proposed project site includes the Boone Blvd.
roadway corridor between Brawley Dr. and Maple St. Boone Blvd is an existing 4-
lane roadway (two lanes each direction) with adjacent sidewalks. The project site
is served by a combined sewer system with feeder lines under the roadway
intersecting main trunk lines at Vine St and Brawley Dr. Boone Blvd is currently
slated to undergo improvements within the next few years. Improvements will
include the reduction from four lanes to two, the addition of 2 five-foot wide one-
way cycle tracks, and new center turn lanes at select intersections.
HydrologicSoil Group
Total Impervious, %
Design Storm Event, in
Proposed SCMs
Urban
91.6
1.2
Total Detention Volume, ft3
Planter Box Area, ft2
Bioretention Area, ft2
Perm. Pavement Area, ft2
10,585
PB, BR, PP Ext. Planting Strip Area, ft2
Proposed Green Infrastructure Description: Proposed SCMs within the right of way
include planter boxes along three blocks and permeable pavement bike paths along five
blocks . Two off-line bioretention systems (located in Mims Park) will treat runoff from 1.5
blocks. All SCMs will contain under-drains that connect to existing or proposed storm
mains. In addition extended planting strips will be incorporated along three blocks.
PB= Planter Box, BR = Bioretention, PP = Permeable Pavement
*Green Infrastructure characteristics are based on field observations and CIS data resources available at the time of
conceptual design analysis. Note that final design characteristics will be dependent on a detailed site survey and could vary
slightly from conceptual design characteristics.
CITY OF ATLANTA LIMITS
Storm Sewers
Sewer Mains
Extended Planting Strip
Planter Box
Permeable One-Way Cycle Track
Impermeable One-Way Cycle Track
m
00
O
O
^
m
DO
co
o
775 Joseph E. Boone Blvd, facing east
Asphalt One-Way Cycle Track
Two-Lane Travel Way^ r-* 5.0'
/ s*
f J^
!H=III=IIH
ermeable One-Way Cycle Track
xisting Sidewalk
Geotextil
4" Perforated Underdrain
jil Media (Min. Depth = 2') Native Soil
V Choking Layer
12" Gravel Drainage Layer
Section A-A'
rainage Aggregate (No. 8 stone)
ubbase (No. 57 stone)
oarse Base (No. 2 stone)
" PVC Underdrain
-------
Legend
Storm Sewers
Sewer Mains
Vegetated Median
Permeable One Way Cycle Track
Impermeable One-Way Cycle Track
Bioretention
Proposed Catch Basin and Culverts
f
Stonei Dissipation"Basin '
Grass Spillway
Stone Spillway
Riser Outlet Structure
and Culvert
ProDos₯d Permeable
m
00
O
O
^
m
DO
o
785 Joseph E. Boone Blvd NW, facing west
Section B-B
6'
4'
2'
0
Raised Vegetated Medianx
H
JT
Native Soil
One Lane Roadway
Concrete
Curb
,Permeable One-Way Cycle Track
xisting Sidewalk
rainage Aggregate (No. 8 stone)
ubbase (No. 57 stone)
Base (No. 2 stone)
4" PVC Underdrain
------- |