xvEPA
United States
Environmental Protection
Agency
2014 GREEN INFRASTRUCTURE TECHNICAL ASSISTANCE PROGRAM
City of Fall River
Fall River, MA
Green Infrastructure Implementation in Fall River,
Massachusetts
Reducing Stormwater Contributions to Combined Sewers through Tree Filter
Retrofits, Rain Barrels, and Stormwater Credits to Homeowners
APRIL 2016
EPA 832-R-16-002
-------
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, soil and plants absorb and filter the water. 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 (storm sewers) and discharged into nearby water bodies. 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. Green infrastructure can be a cost-effective approach for
improving water quality and helping communities stretch their infrastructure investments further by
providing multiple environmental, economic, and community benefits. This multi-benefit approach
creates sustainable and resilient water infrastructure that supports and revitalizes urban communities.
The U.S. Environmental Protection Agency (EPA) encourages communities to use green infrastructure to
help manage stormwater runoff, reduce sewer overflows, and improve water quality. EPA recognizes
the value of working collaboratively with communities to support broader adoption of green
infrastructure approaches. Technical assistance is a key component to accelerating the implementation
of green infrastructure across the nation and aligns with EPA's commitment to provide community
focused outreach and support in the President's Priority Agenda Enhancing the Climate Resilience of
America's Natural Resources. Creating more resilient systems will become increasingly important in the
face of climate change. As more intense weather events or dwindling water supplies stress the
performance of the nation's water infrastructure, green infrastructure offers an approach to increase
resiliency and adaptability.
For more information, v\s\t http://www.epa.Qov/Qreeninfrastructure.
-------
Acknowledgements
Principal USEPA Team
Jamie Piziali, USEPA
Christopher Kloss, USEPA
Eva Birk, ORISE, USEPA
Community Team
Terry Sullivan, City of Fall River
Paul Ferland, City of Fall River
Bob O'Connor, Massachusetts Division of Conservation Services
Cindy Bauman, CDMSmith
Consultant Team
Jonathan Smith, Tetra Tech
Christy Williams, Tetra Tech
Kelly Meadows, Tetra Tech
Bobby Tucker, Tetra Tech
Adam Orndorff, Tetra Tech
This report was developed under EPA Contract No. EP-C-11-009 as part of the 2014 EPA Green
Infrastructure Technical Assistance Program.
Cover design by Tetra Tech, Inc.
-------
Contents
1 Executive Summary 1
2 Introduction 2
2.1 Water Quality Issues/Goals 2
2.2 Overview and Goals 3
2.3 Benefits 4
2.4 Local Challenges 4
2.5 Site Conditions 4
2.6 Existing Catch Basin Characteristics 7
2.7 Evaluation of Tree Filter Retrofit Locations 10
2.8 Soil Conditions 10
3 Birch Street Tree Filter Pilot Program 10
3.1 Design Development 12
3.2 Tree Selection 15
3.3 Stormwater Calculations 15
3.4 Planning-Level Cost Estimate 16
3.5 Identified Catch Basin Retrofit Opportunities 18
3.6 Tree Filter Assessment Summary 19
4 Rain Barrel Incentive Program Options for Fall River 20
4.1 Proposed Rain Barrel Program Eligibility & Guidelines 20
4.2 Application Process 20
4.3 Rain Barrel Distribution 22
4.4 Code Revisions 22
5 Conclusion 23
6 References 23
Appendix A: Tree Filter Standard Design 1
Appendix B: Tree Filter Retrofit Location Summary 1
Appendix C: Tree Filter Fact Sheet 1
IV
-------
Figures
Figure 2-1. The Birch Street catchment area 5
Figure 2-2. Birch Street outfall 6
Figure 2-3. Typical street exhibiting limited trees along the right-of-way 7
Figure 2-4. Catch basin hood prevents debris from entering combined sewer 8
Figure 2-5. Catch basins with curb style inlet 9
Figure 2-6. Slotted grate inlet catch basin 9
Figure 3-1. Schematic view of typical tree filter 11
Figure 3-2. Tree filter section view 14
Figure 3-3. Recommended tree filter retrofit locations 18
Tables
Table 3-1. Instantaneous storage volumes fortree filter 16
Table 3-2. Tree filter cost estimate 17
Table 3-3. Catch basin retrofit site characteristics 19
Table 4-1. Rain barrel comparison matrix 21
-------
I Executive Summary
The City of Fall River is an historic waterfront community located at the mouth of the Taunton River
along Mount Hope Bay in southeastern Massachusetts. Like many older industrial centers in the
northeastern U.S., the City faces the challenge of degraded surface water quality associated with an
aging combined sewer system. Through the implementation of several large sewer separation and
storage infrastructure projects completed in recent years, the City has achieved significant reductions in
the incidence of combined sewer overflows (CSOs). However, despite the successes of these
conventional solutions, several areas of the City continue to exhibit frequent CSOs. These areas are
generally not suitable for conventional infrastructure approaches due to resource limitations and
significant implementation constraints.
This report documents the development of several green infrastructure elements that could be
incorporated into the City's stormwater management program. First, much of the City relies on aging
drainage infrastructure, primarily curb and street inlets subject to ongoing repair and replacement due
to structural failure. To leverage an ongoing tree planting effort citywide, a low-cost standardized tree
filter design was developed to replace these drainage elements as the City integrates green
infrastructure in constrained street corridors and existing infrastructure. As part of a more focused tree
filter pilot program, the Birch Street catchment area was studied, 12 specific retrofit locations were
identified for future tree filter installation, and schematic designs were developed to guide pilot
program implementation. Additionally, a fact sheet was developed to communicate the benefits of tree
filters to City residents. In combination, the standardized design, the results of the pilot program (that
uses the standard design), and the outreach materials will provide the City with the tools and experience
it needs for widespread implementation of tree filters. Second, this report also explores the
implementation of a citywide rain barrel program, including the adoption of a standard design for a rain
barrel for residential use, the adoption of a citywide stormwater incentive program, and potential code
revisions for administration of the incentives.
The adoption of tree filters in Fall River would serve three critical functions: (1) replacement of failing
infrastructure, (2) reduction of stormwater contribution to combined sewers, and (3) facilitation of the
installation of trees within street rights-of-way to support Fall River's urban tree initiatives. Rain barrels
would capture a portion of runoff, providing small-scale irrigation and other benefits; developing an
appropriate incentive program can increase participation and public awareness. Implementing the green
infrastructure practices described in this report (tree filter retrofits in the pilot program and residential
rain barrel distribution citywide) would demonstrate to residents, city staff, elected officials, and other
stakeholders how green infrastructure functions and can provide multiple benefits to the community.
-------
2 Introduction
The City of Fall River, Massachusetts is located in Bristol County along the eastern coast of Mount Hope
Bay at the mouth of the Taunton River. Water bodies are an integral part of the City's culture, and there
are several rivers, reservoirs, and a bay that border or lie within the City boundaries; Rhode Island
borders Fall River to the south and also has substantial shoreline along Mount Hope Bay. In the
eighteenth and nineteenth centuries, the Quequechan River, with waterfalls that gave the City its name,
provided power for textile mills, allowing the City to be a major industrial center in New England during
that time. Fall River is currently the tenth largest city in the state, with approximately 90,000 residents,
including large populations of low income and non-English speaking residents.
Fall River was recently selected by the state of Massachusetts as one of three cities to implement a new
energy-efficient tree-planting initiative (EETPI). The initiative seeks to plant up to 15,000 trees
throughout these cities in areas where tree densities are generally low in order to reduce energy use in
urban neighborhoods and lower heating and cooling costs for residents and businesses. In addition, a
local nonprofit tree-planting organization, the Fall River Tree Committee, Inc., recently established one
of the state's first urban tree nurseries and is supported by a strong group of volunteers who assist in
planting and maintaining trees throughout the community.
In Fall River, however, the existing street network throughout the City has minimal space for tree
planting due to paving widths and sidewalks on both sides of the streets that typically extend from back
of curb to the right-of-way limit. To leverage ongoing urban tree-planting efforts, this report provides a
framework for a green infrastructure pilot program for implementation of tree filters. The purpose of
the pilot program, which focuses on a drainage area that experiences CSOs, is to evaluate the feasibility
of implementing tree filters in the public right-of-way to provide stormwater control, while
simultaneously creating opportunities to expand the urban tree canopy. This report also explores the
potential installation of residential rain barrels, an economic incentive for City residents, and potential
code revisions needed for administration of the incentives.
2.1 Water Quality Issues/Goals
Massachusetts Department of Environmental Protection (MassDEP) has classified Mount Hope Bay as a
Class SB water1 suitable for shellfish harvesting. Data from multiple sources indicate that the majority of
the Bay consistently fails to meet water quality standards for bacteria. In addition to shellfishing, other
designated uses in the Bay, such as primary and secondary contact recreational use, are affected by
bacteria pollution (MassDEP 2010). Stormwater runoff from the City and other municipalities in both
Rhode Island and Massachusetts also contribute to the observed impairments in the Bay.
In 2010, MassDEP, along with the U.S. Environmental Protection Agency (EPA), developed a total
maximum daily load (TMDL) to address pathogens in Narragansett Bay and Mount Hope Bay. That same
year, the Rhode Island Department of Environmental Management (RIDEM) developed a TMDL to
address bacteria-related impairments in Mount Hope Bay and the Kickemuit River Estuary. Both TMDLs
provide guidance for local governments and stakeholders to implement practices to meet bacteria water
quality standards in the Bay and its tributaries.
CSOs from the City of Fall River are the largest source of fecal bacteria to Mount Hope Bay during wet
weather (RIDEM 2010). The City has been under a Federal Court Order since 1992 to reduce CSO
1 See 314 Code of Massachusetts Regulations at http://www.mass.gov/courts/case-legal-res/law-lib/laws-by-source/cmr/300-
399cmr/314cmr.html.
-------
discharges, and ongoing construction of facilities to store and treat the combined sewage have begun to
mitigate the overflows. More than $178 million in capital improvements have been made to the Fall
River collection system in recent years to address the CSO issue, including the completion of a deep rock
tunnel storage system that began operation in 2005 (MassDEP 2010). These extensive upgrades to the
collection and treatment systems at Fall River are expected to result in significant water quality
improvements.
Fall River continues to experience CSO discharges from combined sewer outfalls along the City's
shoreline during severe storm events, despite investments in gray infrastructure. The City wishes to
expand its toolbox of CSO abatement methods to include green infrastructure to manage stormwater to
improve water quality, while also providing additional benefits to the community (e.g., increasing tree
canopy).
This report describes two parts of the City's green infrastructure initiatives. The first is the development
of a pilot program to use green infrastructure—specifically tree filters—to reduce CSOs and to improve
tree cover and aesthetics in a portion of Fall River. The pilot program would be one element of a multi-
faceted municipal effort focused on integrating the state's EETPI with installation of tree filters to
manage stormwater in a neighborhood setting, the installation of residential rain barrels, and an
economic incentive program for City residents.
The pilot program targets the Birch Street catchment basin, which drains 94 acres and is connected to a
66-inch interceptor located along Mount Hope Bay shoreline. During significant rainfall events, the
capacity of the interceptor is exceeded and combined sewer effluent is discharged directly to Mount
Hope Bay. Based on continuous simulation modelling analysis of the City's combined sewer outfalls, the
Birch Street basin is estimated to experience the greatest reduction in stormwater flows as a result of
green infrastructure implementation (COM 2012). Similarly, the basin is estimated to experience the
greatest cost savings, as compared to conventional CSO reduction measures, when using green
infrastructure practices to address stormwater flow reduction.
The pilot program would demonstrate the integration of green infrastructure with ongoing, citywide
urban tree initiatives. The goals of the pilot program would be to:
• Develop a tree filter standard design that can be implemented in street rights-of-way across the
City to replace failing catch basins.
• Develop concept schematics to retrofit up to 12 existing catch basins within the Birch Street
pilot watershed with tree filters.
Consistent with the City's plan for CSO abatement, the new trees installed with the tree filter standard
design would help the City meet its goals for reducing stormwater (and CSO) flows and would be
demonstrated in 12 priority retrofit locations. Because the Birch Street subwatershed is also an area of
focus for other tree planting efforts ongoing in the City, Fall River would be able to capitalize on a
number of existing resources, including a dedicated non-profit, an urban tree nursery, and grants from
the U.S. Forest Service and the state Department of Energy Resources. The neighborhood association in
the basin has voiced strong support for plans to reduce CSO discharges. The City would also develop
educational materials to distribute to residents to inform them about efforts to improve water quality,
how tree filters work, and other related topics.
Second, the City seeks to develop a residential stormwater incentives program applicable to the entire
city. The goals of the incentives program would be to:
-------
• Identify a rain barrel standard design that can be adopted by the City and used by residents in
order to capture a portion of stormwater flows, thereby reducing the potential for CSO events.
• Develop a process for the incentives program application and rain barrel distribution.
• Identify changes to city code to provide for administration of the incentives program.
The City envisions two primary benefits from implementing these green infrastructure elements. The
first is a reduction in the number of CSO events through improved control of stormwater. City officials
estimate that the entire tree planting program (i.e., not just those installed as part of the pilot program)
might reduce the citywide stormwater flows by 10-20 percent above the stated goal to meet the City's
CSO plan. The second benefit is a beautification of the City by planting additional trees, which will also
provide shade, reduce energy consumption, improve air quality, and engage local organizations.
Fall River faces a long-standing problem with CSO discharges and has already spent a significant amount
on conventional infrastructure. Despite these efforts, CSOs remain a concern and addressing these last
outfalls will likely require large expenditures, a problem in a city with limited resources. Fall River's
significant investments in gray infrastructure have started to reduce CSO discharges, but additional
investment is needed to sufficiently reduce overflows. As such, the City is investigating opportunities to
utilize green infrastructure to optimize performance and inform future stormwater decisions by
considering the wide range of benefits achieved by implementing green infrastructure.
2.5 Site Conditions
The Birch Street catchment area is located in southwest Fall River along the eastern shore of Mount
Hope Bay. Much of the development in this catchment occurred during the early twentieth century in
response to the industrial growth of the City. The catchment drains 94 acres that include residential
neighborhoods, parks, an elementary school, and several commercial businesses. The catchment area is
roughly bounded by Slade Street to the north, South Main Street to the east, Pokross Street to the
south, and Bay Street to the west. (See Figure 2-1.) The majority of the residences are single family
homes, although portions of a large block of apartment buildings are located in the southwest corner of
the catchment area.
-------
Legend
Birch Street Drainage Basin
Birch Street CSO Area
NAD 1983 SlatePlane Massachusetts^Mainland.HPS 200
Map Produced 12-2-1-2014 -A Porteous
Source: Tetra Tech, Inc.
Figure 2-1. The Birch Street catchment area
Prior to 2009, the Birch Street catchment area was somewhat larger, but construction of a 20-foot
diameter CSO storage tunnel in 2009 resulted in the interception of a portion of the combined sewer for
this catchment into the tunnel storage, effectively reducing the catchment area. Despite this reduction
in contributing area, combined sewage flows still exceeds the capacity of the interceptor along the shore
of Mount Hope Bay during larger storm events, resulting in direct discharge from the catchment area
outfall at those times (Figure 2-2). A modeling analysis estimated that direct discharge to Mount Hope
Bay occurs approximately 56 times in a typical year, resulting in 19 million gallons of combined sewage
discharging directly to the Bay (COM 2012).
-------
Photo credit: Tetra Tech, Inc.
Figure 2-2. Birch Street outfall
The streets within the catchment are configured in a grid network with streets in a north-south or east-
west orientation. The combined sewer system is exclusively located within the center of the road right-
of-way with a main trunk along Bay Street connected to secondary feeder lines along the east-west
oriented streets corresponding to the dominant slope direction. Houses are generally located close to
the street with lawn space dedicated at the rear of the house within the center of the blocks. Street
fronts exhibit limited presence of trees (Figure 2-3). Based on observations from a site visit, all
stormwater runoff generated within the private parcels (including rooftop runoff) is surface routed into
the street right-of-way and eventually to the catch basin inlets along the curb.
-------
Photo credit: Tetra Tech, Inc.
Figure 2-3. Typical street exhibiting limited trees along the right-of-way
2.6 Existing Catch Basin Characteristics
During the site visit, a review was conducted on the existing catch basins that collect stormwater runoff
from the curb gutters and route it to the combined sewer. The review included collection of information
on typical catch basin geometry, with a specific emphasis on characteristics important in the
development of a tree filter standard design.
Catch basins within the Birch Street area are generally grouped around street intersections to capture
runoff flowing along curb edges and prevent cross-street flow. Many intersections have multiple catch
basins, while others have one or two, or depending on the slope, none. Catch basins are typically circular
and constructed of brick or masonry block construction, depending on age. Historically brick was used,
but masonry block is common for new construction and repairs. Catch basins are 5 to 6 feet in diameter
with a depth of 5 to 6 feet. The connection to the combined sewer is provided by a cast iron pipe
typically 2.5 to 3.5 feet below the top of the inlet. As a result, the catch basins incorporate a sump of 1.5
to 3.5 feet at the bottom to capture trash, floatables, and other debris. A hood, which serves as a debris
shield, is typically installed on the sewer connection pipe to prevent floatables from entering the sewer
system (Figure 2-4).
-------
-
Photo credit: Tetra Tech, Inc.
Figure 2-4. Catch basin hood prevents debris from entering combined sewer
Catch basin inlets in Fall River generally are one of two configurations: curb and slotted grate inlets.
Both configurations appear to be of consistent construction and dimensions below the ground surface
as detailed above. Curb inlets, colloquially referred to as Bradley Head inlets (see Figure 2-5) consist of a
concrete slab top integrated into the sidewalk incorporating a standard manhole ring frame and cover.
Stormwater runoff is routed into the catch basin by means of a precast slot weir or throat integrated
into the slab top at the curb edge and depressed or modified pavement surface to accommodate inflow.
Curb inlets are sometimes located at the apex of intersections rather than along a straight section of
curb. The curb inlet is the preferred style for new or replacement catch basin inlets.
-------
Photo credit: Tetra Tech, Inc.
Figure 2-5. Catch basins with curb style inlet
Slotted grate catch basin inlets (see Figure 2-6) consist of a slotted cast iron drain (generally a cascade or
bar grate) located within the curb gutter situated above the catch basin structure. These inlets do not
include a dedicated manhole for access but rather rely on the grate for this purpose. Slotted grate catch
basins appear to be somewhat more common within the Birch Street catchment area.
Photo credit: Tetra Tech, Inc.
Figure 2-6. Slotted grate inlet catch basin
-------
2.7 Evaluation of Tree Filter Retrofit Locations
The Birch Street catchment area contains 58 catch basin inlets. Each catch basin inlet location was
visually evaluated for the feasibility of retrofitting with a tree filter system. Feasibility considerations
included a variety of factors related to conflicts with existing infrastructure and physical space
requirements, such as:
• Overhead utility lines (low clearance height)
• Existing trees, utility poles, fire hydrants, or other vertical infrastructure
• Conflicts with adjacent structures on private property
• Presence of a cross-walk
• Sufficient sidewalk width to accommodate a tree and remain compliant with the Americans with
Disabilities Act
Among the catch basins evaluated, 12 locations were identified as feasible for retrofit with a tree filter.
The remaining 46 catch basins locations were excluded from consideration based on one or more of the
issues noted above. The most common issues observed were presence of overhead utilities, and to a
lesser extent, conflicting adjacent infrastructure.
The Birch Street catchment area is classified using the U.S. Department of Agriculture's Web Soil Survey
as Urban-Land, which has unknown parent material due to significant excavation or fill. According to the
Web Soil Survey, the depth to a restrictive layer (water table or bedrock) exceeds 200 centimeters.
Based on comments from City staff, much of Fall River overlays a shallow granite dome that is covered
with a highly permeable glacial till material. Infrequent outcroppings of bedrock were observed during
the site investigations, and City staff indicated that bedrock was sometimes encountered during
installation of shallow infrastructure (such as new catch basins), requiring expensive bedrock removal.
Interestingly, many homes in Fall River have full basements, and basement flooding does not appear to
be a common issue within the community, perhaps indicative of high rates of permeability associated
with the overlying soil material.
The presence of shallow underlying bedrock underscores the need for the standard tree filter design to
emulate the depth and dimensions of the existing catch basins so that additional bedrock removal is
limited. The high permeability rates associated with shallow soils also indicate that open bottom tree
filters might be appropriate to enhance the reduction of runoff contribution to the combined sewer and
allow the trees contained within them to access a larger rooting area.
3 Birch Street Tree Filter Pilot Program
Tree filters are structural elements typically installed along roadway curbs or in other ultra-urban
settings. Sometimes referred to as tree box filters, they consist of a concrete box that contains a filter
media suitable for plant growth in which a small tree is planted (Figure 3-1). Tree filters serve to function
in much the same way that bioretention or bioswales do, but they are much more suitable to highly
urban environments where pedestrian surfaces must be retained. Stormwater runoff is routed into the
tree filter system via a curb opening, where it enters a storage zone directly above the filter media.
Some designs also incorporate a pretreatment chamber upstream of the storage zone to capture debris
and heavy sediment. Captured stormwater runoff slowly infiltrates through the filter media before
10
-------
exiting the tree filter, either through an underdrain connected to the storm or combined sewer system
or directly into underlying soils. The filter media removes a portion of pollutants carried by the runoff
and stores moisture for use by the tree.
Vegetation
centered in
treatment
Impervious surface
Q., Conveyance
protection bypass
Mound 6" berm
around tree filter rim
Cross section of
72" diameter
concrete vault
12" Overflow pipe
1?" Perforated
subdrain
12" Overflow outlet,
discharges to existing
storm drain or the
surface
Source: University of New Hampshire
Figure 3-1. Schematic view of typical tree filter
In support of the City's tree planting initiative, a standard tree filter design was developed to provide a
simple, low-cost option that could be installed by the Community Utilities Department to replace failing
catch basins on an as needed basis at locations throughout the City. The tree filters would serve three
critical functions: (1) replace failing infrastructure, (2) reduce stormwater contribution to combined
sewers, and (3) facilitate implementation of trees within the street right-of-way to support Fall River's
tree programs. Additional design criteria for the tree filter, which are based on the existing geometries
of the combined sewer catch basins and culverts (as described in Section 2.6), include:
II
-------
• Fit within existing 6-foot to 8-foot wide sidewalk corridor (distance from curb to right-of-way
limit)
• 6-foot maximum depth below grade
• Outlet invert 2.5 feet to 3.5 feet below grade
• 24-inch maximum outlet diameter
• Open bottom for infiltration
• Pretreatment option for floatables and solids control
Sections 4.1-4.4 below describe the development of the standard design (Appendix A). Section 4.5
describes the process of identifying specific retrofit sites for the tree filter pilot program in the Birch
Street catchment (Appendix B). Lastly, Appendix C contains a fact sheet to distribute to the public that
further describes tree filters and how they function.
3.1 Design Development
To facilitate a low-cost tree filter design that could be integrated into existing infrastructure while
considering typical constraints inherent in a retrofit application, the design team worked with a local
precast concrete manufacturer to develop a tree filter configuration that could be based on existing
septic tank templates. As the basis for the design, a 2,000-gallon, traffic-rated septic tank was selected
with outside dimensions of 6 feet wide, 10.5 feet long, and 6.25 feet high (including an 8-inch thick slab
top). These dimensions maximize treatment volume while complying with the aforementioned site
constraints and design criteria.
The single baffle wall in the septic tank form was retained for structural integrity and modified to
provide separation between the two internal compartments: the tree filter and the outlet sump (with
floatables control). The unit is designed so that stormwater enters the tree filter through a curb inlet at
the top of the tree filter compartment (similar to the manner in which flow enters the curb inlet catch
basins described previously), and it discharges from the system either through infiltration under the
open-bottom tank or overflows through the culvert outlet. The baffle wall is designed to provide up to
12 inches of ponding depth over the tree filter during storm events. Stormwater inflows that exceed the
infiltration capacity of the tree filter layers and the ponding volume will overflow to the outlet sump
through the 6-inch tall opening between the top of the baffle wall and the slab top.
An underdrain is provided to drain the tree filter compartment into the outlet sump. Note that the tree
filter tank will be constructed with a PVC coupler at the bottom of the baffle wall for quick underdrain
connection in the field. During storm events, most of the initial infiltrated stormwater will bypass the
underdrain and saturate the bedding layer through the bottom opening. Once inflow rates exceed the
native soil infiltration rates, the underdrain layer will saturate and flow will begin discharging through
the underdrain (and filling the sump compartment). The tree filter will then saturate to the depth of the
outlet invert, which is based on the existing sewer depths. Regardless, at least 12-18 inches of the tree
filter will freely drain and provide aerobic conditions immediately following the end of the storm event.
After the storm event, the 18 inches of ponded sump water can slowly drain back through the
underdrain and out the bottom of the tree filter based on the saturated infiltration rate of the native soil
conditions. This underdrain configuration was provided to eliminate the nuisance of permanent standing
water and anaerobic conditions in the sump compartment, although the underdrain component can be
removed as a design alternative. Removal of the underdrain system from the standard design might be
desirable as a means to reduce installation costs. This design alternative could also result in enhanced
12
-------
runoff reduction performance since the potential for discharge of filtered runoff into the combined
sewer would be eliminated.
The surface opening for the tree trunk is located 2 feet 6 inches from the curb edge to allow a minimum
of 3 feet of sidewalk width between the outer edge of the right-of-way and the tree trunk (assumes
maximum trunk diameter of 12 inches and sidewalk corridor of 6 feet. The opening for the tree trunk
uses a two-piece cast iron tree grate that can be replaced with various size openings as the tree grows.
As depicted in the section view below (Figure 3-2), other design components and features include the
following (see Appendix A for a detailed design drawing):
1. Filter Tank Components
a. 8-inch high x 18-inch wide curb inlet opening to tree filter
b. 30-inch square tree grate with adjustable tree opening
c. ASTM A48 manhole frame and cover
d. Concrete baffle wall with overflow weir and underdrain coupler
e. 24-inch maximum outlet opening (sited and cored by precast manufacturer) for site-
specific culvert size and depth)
f. Gross pollutants control device at outlet
2. Bioretention Media Filter
a. Energy dissipation pad (salvaged concrete debris from catch basin demolition)
b. 3-inch layer shredded hardwood mulch
c. 2.5-foot bioretention media layer
d. 2-inch washed sand "choking" layer (to prevent clogging of underdrain layer)
e. 8-inch layer No. 8 drainage stone (with underdrain)
f. 4-inch diameter perforated PVC underdrain (connected through baffle wall)
g. 5-inch layer of No. 8 washed stone in open bottom
h. 6-inch washed No. 57 stone bedding layer
13
-------
D1 ITI =T PIPP
24- (MX 1.0
MARKED AMD BORED BASED ON
EKkVMNG^r-.'iR ELEVATICW.
4' SC-I4I;
PVC
CLEANOUT -..
.
AtJD BORED BASED OH
RTDNE,
EXTEND 12" FROM
-QOTPRINT O'FLTER
BOX
4' PERFORATED
UND31AIN.
USE APPROVED RLBBER
BOOT TO CONNECT
THROUGH BA==L= WALL
W: 4" SLIP JDWT COUPLER
Source: Tetra Tech, Inc.
Figure 3-2. Tree filter section view
-------
3.2 Tree Selection
Conditions for tree establishment and growth within a tree filter are in many ways better than those
experienced by trees elsewhere in urban areas, since the latter are often placed in areas of heavily
compacted soil, constrained by subsurface infrastructure, or virtually covered by impervious surfaces.
These conditions restrict the availability of space, nutrients, and water, all of which are necessary for
tree vitality and growth. Tree filters, on the other hand, contain an engineered or customized media
specifically tailored for plant growth as well as removal of stormwater pollutants. The routing of
stormwater runoff into the tree filter similarly ensures the tree is provided with sufficient water and any
entrained nutrients. As mentioned above, the media is designed to drain quickly so that anaerobic
conditions within the root zone do not develop. Therefore, the primary limiting factors of tree filter
systems are primarily spatial. Tree roots are constrained horizontally by the configuration of the filter
area, approximately 5 feet by 6.5 feet, and might be limited vertically by the potential presence of
underlying bedrock beneath the filter box.
The selection of tree species for incorporation into a tree filter must consider these conditions, as well
as community preferences for urban trees. In addition, the selection of a tree species in a specific
location should consider surrounding infrastructure and obstructions. These include adjacent structures,
distance to signage, other trees, and, as commonly observed within the Birch Street catchment area, the
presence of overhead utilities.
3.3 Stormwater Calculations
Instantaneous storage volumes were calculated for the standard tree filter design. Since the storage
volume is fixed, the proportion of total drainage area water quality volume that is captured and treated
by each tree filter will vary by site (although gross pollutants control will be provided for 100 percent of
the runoff entering the tree filter). A more comprehensive and accurate estimate of runoff volume
reduction will require in-situ soil infiltration data and long-term continuous simulation modeling using
observed rainfall depths, durations, and frequencies. Such analysis could be provided as part of
subsequent CSO mitigation efforts to evaluate the impact of the tree filter system relative to other CSO
reduction methods.
The equation used to estimate the instantaneous storage volumes is based on the various media and
aggregate volumes, assumed void ratios, and volume of surface ponding within the tree filter
compartment. This is expressed by the equation below.
Storage Volume = V (Fr * Vm~) * 7.48
Where storage volume is in gallons and:
Vr = voids ratio for each substrate
Vm = volume of each substrate (cubic feet)
Table 3-1 shows the calculated storage volumes for the standard tree filter design. Each tree filter
system will provide nearly 750 gallons of hydraulic storage in a saturated fully utilized condition. This
equates to almost 100 cubic feet of stormwater runoff for each tree filter system. The volume of storage
is equivalent to the runoff expected from a 1,265-square foot (0.03-acre) impervious area during a 1-
inch storm event, a widely accepted depth associated with water quality sizing.
15
-------
Table 3-1. Instantaneous storage volumes for tree filter
Tree Filter Component
Surface ponding
Bioretention media
Choking layer (ASTM C-33 sand)
Underdrain layer (No. 8 stone)
Open bottom fill (No. 8 stone)
Bedding layer (No. 57 stone)
Total Volume
Depth (in)
12
30
2
8
5
6
Void Ratio
1.0
0.25
0.50
0.40
0.40
0.45
Storage Volume (gal)
278
174
23
74
31
168
748
3.4 Planning-Level Cost Estimate
Cost estimates for the standard tree filter design were assembled from quotes received from the precast
manufacturer and product vendors, local bid summaries, and RSMeans estimates for standard materials
(e.g., washed stone, concrete sand). Although it is anticipated the Community Utilities Department can
perform the majority of tree filter installation, the cost estimate provided includes the labor, overhead,
and material markup costs associated with installation by private contractors. Table 3-2 shows the
itemized tree filter cost estimate, including the unit cost reference, material quantities, and overhead
expenditures.
16
-------
Table 3-2. Tree filter cost estimate
Item _ . ..
.. Description
Reference
Quantity
Unit
Unit Cost
Total
Demolition/Earthwork
1 Saw-cut cement sidewalk
2 Saw-cut asphalt pavement
3 Remove curb and discard
4 Earth excavation
5 Backfill
6 Bedding coarse (washed No. 57 stone)
7 Off-site hauling/disposal
Local bid
summary*
Local bid summary
Local bid summary
Local bid summary
Engineer's opinion
RS Means
Bid summary
12.0
22.5
16.5
36.7
20.4
1.9
18.0
LF
LF
LF
CY
CY
CY
TN
$4.80
$3.20
$9.75
$21 .50
$8.50
$30.34
$83.50
$58
$72
$161
$789
$174
$56
$1 ,503
Precast Tank and Accessories
8 10.5 ft x 6 ft x 5 ft Precast Tree Filter Tank6
9 Custom coring for outlet pipe (12-24 in. dia.)
10 26 in. x 4 in. manhole frame and cover
. . 30" Square Tree Grate set w/ 1 6 in. dia. tree
opening
10 Inner Tree Ring Grate Accessory (12-16 in.
_ dia.)
._ 30 in. Square Steel Tree Frame w/ anchor
_ studs
14 Floatables control devices
Quote from J&R
Quote from J&R
Quote from E.J.
Quote from E.J.
Quote from E.J.
Quote from E.J.
Quote from E.J.
1.0
1.0
1.0
1.0
1.0
1.0
1.0
EA
EA
EA
LS
EA
EA
EA
$2,800.00
$250.00
$331 .46
$444.18
$62.42
$92.40
$177.88
$2,800
$250
$331
$444
$62
$92
$178
Tree Filter
1 1 Bioretention Media
12 No. 8 stone
1 3 Washed ASTM C-33 concrete sand
14 Washed No. 57 stone bedding for tank
15 4 in. SCH 40 perforated PVC
16 4 in. SCH 40 PVC
17 4 in. SCH 40 perforated PVC cleanout
18 12-1 4 ft deciduous tree
19 Triple shredded hardwood mulch
RS Means
RS Means
RS Means
RS Means
RS Means
RS Means
Engineer's opinion
Bid summary
Engineer's opinion
3.4
1.3
0.2
1.9
6.0
4.0
1.0
1.0
0.3
CY
CY
CY
CY
LF
LF
EA
EA
CY
$40.00
$25.22
$68.29
$51 .00
$13.76
$6.00
$100.00
$800.00
$60.00
$138
$33
$16
$94
$83
$24
$100
$800
$21
Curb/Sidewalk/Asphalt Replacement
20 Cement concrete sidewalk
21 Granite curb
22 Furnish and install aggregate base
23 Furnish and install aggregate sub-base
24 Furnish and install HMA 12.5 mm
Construction Subtotal
25 Mobilization (5%)
26 Bonds and Insurance (5%)
27 Construction contingency (15%)
Total Cost
Local bid summary
Local bid summary
Local bid summary
Local bid summary
Local bid summary
4.0
16.5
0.6
1.2
1.2
SY
LF
TN
TN
TN
$45.00
$38.50
$100.00
$120.00
$110.00
$180
$635
$60
$144
$132
$9,429
$471
$471
$1,414
$11,786
A unit costs based on summary of local bids provided by City
B Includes knockouts, underdrain pipe coupler, and delivery
17
-------
3.5 Identified Catch Basin Retrofit Opportunities
As noted in Section 2.7, 12 existing catch basin locations were identified as priority candidates for
replacement with the tree filter standard design. The 12 recommended retrofit locations and their
respective drainage areas are shown in Figure 3-3. A detailed summary of locations is provided in
Appendix B, including catchment and impervious area determination methods, sanitary sewer Node ID,
adjacent street addresses, site map, and drainage area.
• Tree Filter Retrofit Locations
Tree Filter Catchment Areas
Birch Street Drainage Basin
Area Treated by Tree Filter Pilot Sites
Source: Tetra Tech, Inc.
Figure 3-3. Recommended tree filter retrofit locations
The catch basins identified for retrofitting provide direct capture of over 16 acres of the Birch Street
catchment area (i.e., 17 percent of the total 94-acre catchment). The drainage area to each of the 12
sites (Table 3-3) exceeds, in some cases by significant amounts, the drainage area that would result in
complete utilization of the inherent storage volume of the filter during a 1-inch storm without
overtopping or bypass. However, due to the dynamic nature of rainfall events, tree filter retrofits at
these locations would likely provide reductions of flow rate during all storm events due to recharge
through the filter bottom and detention storage inherent to the design. Likewise, during smaller storm
events the tree filter would provide treatment and removal of stormwater contaminants through
filtration of the media. In the event of future sewer separation, these practices would then serve to
reduce pollutant loading from stormwater sources to Mount Hope Bay.
18
-------
Table 3-3. Catch basin retrofit site characteristics
Site#
1
2
3
4
5
6
7
8
9
10
11
12
Total
Drainage Area (ac)
1.71
0.88
2.89
0.65
1.37
0.71
1.03
0.72
2.22
2.06
2.21
0.51
16.96
Impervious Area (ac)
0.67
0.35
1.02
0.25
0.44
0.37
0.72
0.40
1.01
0.86
0.43
0.36
6.88
% Impervious
39.2
39.4
35.2
38.2
32.2
51.3
69.9
55.6
45.5
42.0
19.6
70.1
NA
Additional information on specific catch basin geometries (e.g., outlet diameter and invert, bottom
invert) and presence/location of utility service lines to adjacent residences was not available at the time
of this report. As a result, more detailed conceptual design development was not possible for these
retrofit locations. The standard tree filter design, however, has been developed to be suitable for the
conditions observed at these sites. As additional site-specific information becomes available for these
sites, the Fall River Community Utilities Department might further develop site specific implementation
plans for the tree filters, including necessary utility relocations, infrastructure inverts, combined sewer
tie-in conditions, and incorporation of sidewalk infrastructure.
3.6 Tree Filter Assessment Summary
Through adoption of a proposed tree filter standard design, the City of Fall River will add to its existing
suite of tools for addressing the issue of continued CSOs to Mount Hope Bay. Prioritized implementation
at the 12 identified retrofit locations within the pilot area will further provide the City with an example
of how ongoing repair of existing infrastructure can incorporate green infrastructure principles to both
meet local water quality needs and enhance ongoing tree initiatives. These efforts, when combined with
other programmatic initiatives described below, will serve as a framework to expand green
infrastructure efforts throughout the City.
19
-------
4 Rain Barrel Incentive Program Options for Fall River
The City currently manages a stormwater service fee credit program to incentivize the reduction of
stormwater. The current program only authorizes commercial properties to apply for credits, and credits
cannot exceed 25 percent of the total fee ($140/2,800 square feet per year). The City requested a
framework outlining the program revisions necessary to authorize a simple residential incentive
program that would allow use of rain barrels to generate stormwater utility fee credits. City staff were
only interested in incentivizing rain barrels to generate initial interest from residents. Additional credit
options could be authorized in the future if there is adequate participation in the rain barrel program.
Based on input from City staff, the design team is proposing the following revisions to the City's existing
stormwater credit incentive program. The proposed framework includes residential eligibility criteria, an
application process, maintenance obligations, and code revisions necessary to authorize the rain barrel
incentive program.
4.1 Proposed Rain Barrel Program Eligibility & Guidelines
• Eligibility is limited to residential homes only.
• Applicant must own the home and be in good financial standing with the City of Fall River.
• Rain barrels must be either the manufactured device preferred by the City or a similar model as
approved by the City. See Table 4-1. for rain barrel options/types.
• Rain barrels must be installed prior to applying for the utility credit.
• Fifty percent of the property's roof drainage area must be connected to rain barrels and provide
at least 50 gallons of storage per downspout.
4.2 Application Process
• The City will issue a credit of up to $75 per household. This credit will be applied to the first two
quarters of utility fee after installation of the rain barrel.
• After the initial $75 installation credit, a credit of $2 per quarter will be earned as long as a rain
barrel is on the property and functioning properly.
• Registration in the program will require the submittal of a simple application form and
documentation that the barrel has been purchased and installed. A copy of the receipt for
purchase and photo documentation of installation will be required.
• Completed applications must be submitted to the City of Fall River within 90 days of purchase of
the rain barrel.
• The application form will include several statements to certify that:
o The property owner will maintain the barrel properly.
o The rain barrel will remain on the property for the life of the barrel and that if it fails to
function it will be replaced in order to continue to get the credit.
o The fee credit can be transferred to new property owners should the property be sold.
o The owner must notify the City if the rain barrel is permanently disconnected for
revocation of the credit.
20
-------
Table 4-1. Rain barrel comparison matrix
Type
Price Size
Installation
Use
Aesthetics Shape
Warranty Materials
Big Blue $90 55 gal.; 35 Moderate; does not
in x 22.4 in include gutter
diverter (sold
separately). Must
install spigot and
overflow fittings.
FreeGarden RAIN $80 55 gal.; 33 Easy; must screw
in x 24 in in spigot and screw
Enviro World Rain Barrel on toP witn four
screws.
Barrel with Brass Spigot $95 50 gal. Easy; must screw
in spigot and insert
screen in top.
Removable lid, Only comes in Round 1 year
but not screw top. blue
One overflow or
connector located
halfway up barrel.
Would not need
stand if used
middle valve for
spigot.
Removable lid. Only comes in Square to 1 year
Two overflow white fit against
connectors or house or
either side in corner
located at top of
container. Do not
need stand due
to location of
spigot
Unknown if lid Brown, looks Flat back 1 year
removable. Two like wooden to go
overflow barrel against
connectors at top house
of barrel. Spigot
located at bottom
of barrel so would
likely need a
stand for proper
flow.
Food grade
repurposed;
brass spigot
Plastic, brass
spigot
Polyethylene
21
-------
4.3 Rain Barrel Distribution
Based on input from City staff, the preferred method of rain barrel distribution is requiring residents to
independently purchase a rain barrel preferred by the City. However, if the City should decide in the
future to implement a centralized rain barrel initiative and public education program, there are a
number of organizations that can administer rain barrel sales for local governments (e.g., the Great
American Rain Barrel Company (TGARB) located in Hyde Park, Massachusetts).
The design team reviewed the City's municipal code and recommends several changes be made to
authorize the proposed residential rain barrel program, as well as any similar incentive program which
might be implemented in the future.
The existing regulations do not authorize residential property owners to qualify for a credit, they put a
restriction on the amount of credit a property owner can receive, and they include confusing relevant
definitions. The proposed revisions will allow for residential properties to earn the credit and allow for
the credit to exceed 25 percent of the total charge (which will be the case for the first two quarters of
the credit application). Further, the revisions remove the term facility from the definition of the term
credit, as stormwater facility is defined later in the same section in a way that is not appropriate in
understanding the term credit; the definition of stormwater facility includes combined sewers, catch
basins, storm drains, drainage pipes, and a variety of other structures and stormwater control measures.
The following text provides the proposed underline/strikeout revisions proposed for the City's municipal
code.
Section 74-140 Stormwater Fee
(3) Definitions.
Credit. Credit shall mean a conditional reduction in the amount of the stormwater
service fee to an individual property based on the provision and continuing presence of
an effectively maintained and operational City-approved on-site stormwater
management system or facility or other service or activity that reduces the stormwater
management utility's cost of providing services.
Credits can bo applied as follows at the discretion of the sower commission: Credits shall
not bo eligible below the base ERU, moaning that any property that is subject to this foe
shall bo required to pay at least the cost of one ERU per quarter. As residential
properties (single through eight family) pay the lowest possible cost credits arc not
available.
Credit shall not exceed 25 percent of the total charge.
Credit requests filed after June 30 of any year shall not be applicable to the previous
fiscal year(s).
22
-------
5 Conclusion
Like many New England industrial cities with aging infrastructure and uncertain economies, the City of
Fall River is faced with the challenge of maintaining existing utility services with limited resources. In
addition, the City is under a Federal Court Order to reduce CSOs. Although the City has committed
significant resources to address these issues, problem areas remain. Through the adoption of the green
infrastructure program elements described above, however, the City can leverage existing programs and
initiatives in a manner to mitigate some CSOs in the pilot Birch Street catchment area. Upon completion
of potential future sewer separation projects currently planned for the Birch Street catchment, green
infrastructure elements will then serve to further protect the water quality of Mount Hope Bay by
reduction and treatment of stormwater prior to discharge directly to Mount Hope Bay. Furthermore, the
adoption of tree filters in Fall River would serve three critical functions: (1) replace failing infrastructure,
(2) reduce stormwater contribution to combined sewers, and (3) facilitate implementation of trees with
street right-of-way to support Fall River's urban tree initiatives.
The Birch Street catchment area pilot program presents an opportunity to exhibit how green
infrastructure practices can integrate into existing infrastructure. The pilot area is representative of
typical residential neighborhoods and serves as a template for more widespread adoption in the other
CSO areas throughout Fall River and elsewhere in the region. Implementation of the green infrastructure
practices (tree filter retrofits in the pilot program and residential rain barrel distribution citywide) will
demonstrate to residents, City staff, elected officials, and other interested stakeholders how green
infrastructure functions and can provide multiple benefits to the community.
6 References
COM Smith. 2012. CSO Abatement Program City of Fall River Massachusetts. CSO Control Plan and
Program Update Report. Providence, Rl.
MassDEP (Massachusetts Department of Environmental Protection). 2010. Final Pathogen TMDLfor the
Narragansett/Mt Hope Bay Watershed. CN#351.0, Report #61 -TMDL -2. Massachusetts Department
of Environmental Protection, Division of Watershed Management, Boston, MA. Available online at:
http://www.mass.gov/eea/docs/dep/water/resources/n-thru-y/narrmthb.pdf.
RIDEM (Rhode Island Department of Environmental Management). 2010. Total Maximum Daily Load
Study for Bacteria: Mount Hope Bay and the Kickemuit River Estuary. Rhode Island Department of
Environmental Management, Office of Water Resources, Surface Water Protection Section, Providence,
Rl. Available online at:
http://www.dem.ri.gov/programs/benviron/water/guality/rest/pdfs/mthope.pdf.
University of New Hampshire. 2007. University of New Hampshire Stormwater Center: 2007 Annual
Report. University of New Hampshire, Durham, NH.
23
-------
Appendix A: Tree Filter Standard Design
A-l
-------
RECOMMENDED TREE LIST
Common Name
Crabapple
Dogwood
Hawthorn (thornless variety)
Japanese Tree Lilac
Cherry Plum
Serviceberry (single stem)
Botanical Name
Malus spp.
Cornus spp.
Cratoegus spp.
Syringa reticulate
Prunus cerosifera
Amelanchier spp.
BIORETENTION MEDIA SPECIFICATION
BSM
Composition
Volume
Weight
Sand
65%
Sandy Loam
Sand
Silt
Clay
20%
75-^80%
10% max.
3% max.
Compost
15%
9% max.1
1 compost by weight results in approximately 5% organic matter by weight.
SECTION A-A
4" SCH 40 PVC
CLEANOUT
2'-5"
I I
•UNDISTURBED SOIL
6" LAYER WASHED #57 STONE,
EXTEND 12" FROM FOOTPRINT
OF FILTER BOX
4" PERFORATED UNDERAIN.
USE APPROVED RUBBER BOOT TO
CONNECT THROUGH BAFFLE WALL
4" slip joint coupler
CITY/TOWN
STREET/ROUTE # OR NAME
OUTLET PIPE
24" MAX I.D.
MARKED AND BORED BASED ON
EXISTING SEWER ELEVATION..
GROSS POLLUTANTS CONTROL
DEVICE
OUTLET
CHAMBER
TREiE F L ER
18"X8"CURB
INLET
3" LAYER SHREDDED
HARDWOOD MULCH >"
3" CONCRETE
BAFFLE WALL
BIORETENTION MEDIA
\ \ vs
2" WASHED ASTM C-33
CONCRETE SAND
8" WASHED #8
DRAINAGE STONE
OOOOOOOOOOOOOOOOO
oooooooooooooooooovo
OPEN BOTTOM FOR INFILTRATION
(FILL WITH 5" WASHED #8 DRAINAGE STONE)
STATE
MA
FED.AIDPROJ. NO.
-
SHEET
NO.
4
TOTAL
SHEETS
X
PROJECT FILE NO. XXXXXX
OUTLET PIPE
24" MAX I.D.
MARKED AND BORED BASED ON
EXISTING SEWER ELEVATION..
UTILITY SKETCH PLAN
0.
cq
un
o
_O
0_
Q
>
LJJ
Q
HI
LJJ
LJJ
OL
CURB CUT W/
18"X8" CURB INLET TO TREE FILTER
EXISTING CURB
EDGE
CD
r
23
L
OPTIONAL 18'X8" CURB INLET
i
18"x4" CURB INLET
:r m^'^^^m^'-
30"x30" CAST IRON
TREE GRATE
(2-PIECE) |
I
J
^^'^^^^^^ r =
4" PERFORATED UNDERDRAIN
WITH CLEANOUT AND RUBBER
BOOT CONNECTION THROUGH
BAFFLE WALL
MAX 30" O.D.
OUTLET PIPE TO
EXISTING SEWER
26" X4" MANHOLE
FRAME AND COVER
(MADOT STD DETAIL #)
OPTIONAL 30" OUTLET PIPE OPENING
PLAN VIEW
CAST-IN-PLACE CURB W/
STEEL NOSE PLATE
4"MIN/6"MAX
THROAT OPEN ING
EDGE OF EXISTING
SIDEWALK
MAX SIDEWALK WIDTH
CAST-IN-PLACE
DEPRESSED GUTTER
AT THROAT OPENING
4"X4" TYP. BRICK OR MASONRY
DEBRIS FROM ONSITE DEMOLITION.
PLACE MIN. 2' X 3' TO PROVIDE
ENERGY DISSIPATION
4" PERFORATED
PVC UNDERDRAIN
SECTION B-B
PREPARED BY:
REVISIONS
REV.
COMMENTS
DATE
SCALE: XX FEET TO THE INCH
FILE NAME: TREE_FILTER_DETAIL_V3.DWG
FIELD BOOK. NO: XXXX
DISTRICT (X) UTILITY ENGINEER:
XXXXXX
FIELD CHIEF: XXXXX
PARS. NO: XXXXXXX
STREET/ROUTE # OR NAME
(TOWN/CITY NAME)
BASED OFF % SUBMISSION
PROJECT #
DATE:
MONTH DD, YEAR
SHEET
OF X
-------
Appendix B: Tree Filter Retrofit Location Summary
B-l
-------
Appendix B: Priority Tree Filter Retrofit Locations
I. I Overview
During field investigations of the Birch Street catchment area, a feasibility determination was conducted
on each of the 58 existing catch basins connected to the combined sewer system to assess whether a
tree filter may be appropriate at a given basin. The field determination consisted of a physical site visit
to each catch basin for visual evaluation of potential conflicts with replacement of the existing catch
basin by the proposed tree filter structure. A variety of potential conflicts were observed and ranged
from significant to minor. Significant conflicts included conditions that made a retrofit impossible or
would carry significant costs. An example of a significant conflict is a catch basin immediately adjacent to
a building or critical infrastructure that would likely be damaged during retrofit operations or require
expensive relocation. Minor conflicts included those that would result in relatively small impacts to
adjacent infrastructure or result in low-cost relocation. An example off a minor conflict is the presence
of a street sign within the retrofit footprint. All 58 of the potential sites exhibited some form of potential
conflict; some minor, some significant, or some a combination of the two.
1.2 Priority Tree Filter Retrofit Site Index
The project team conducted a review of the site evaluations and prioritized 12 catch basins in which
conflicts were generally minor. These locations (shown in Figure B-l) are recommended for retrofit with
the tree filter standard design in accordance with implementation schedule to be determined by Fall
River.
B-2
-------
Site Visit Catch Basins
Stormwater Catdi Basins
Sanitary Sewer Catch Basins
Stormwater Pipes
Sewei Pipes
Parcels
Birch Street Drainage Basin
Fall River
Site Visit Map Index
Map Produced UU-11-2U14 -A. Porteous
N
0.075
0
0.125
0.15
^U Miles
0.25
1 Kilometers
TETRA TECH
Source: Tetra Tech, Inc.
Figure B-l. Prioritized tree filter retrofit locations within the Birch Street catchment area
Contributing drainage area for each priority retrofit site was approximated in ArcGIS using 2 foot
contour data and aerial imagery. Summary information on the twelve prioritized tree filter retrofit
locations is provided in Table B-l. The 12 sites are not presented in any specific order. It is understood
that the City of Fall River wishes to retrofit tree filter systems as the existing catch basins require repair
or replacement.
B-3
-------
Table B-1. Summary of prioritized tree filter retrofit locations
Site Visit ID
1
2
3
4
5
6
7
8
9
10
11
12
Sanitary Sewer
Node ID
CB 242
CB 3202
CB 231
CB_34
CB_16
CB_12
CB_3085
CB_3631
CB_18
CB_20
CB_218
CB_241
Drainage Area
(acres)
1.71
0.88
2.89
0.65
1.37
0.71
1.03
0.72
2.22
2.06
2.21
0.51
Adjacent Parcel
ID
B-ll-1
H-15-35
B-12-17
A-l-2
A-l-2
A-2-43
A-3-1
A-3-1
A-l-17
B-7-46
A-l-1
H-14-38
Adjacent Parcel Address
455 Dwelly Street
185 Dwelly Street
433 Slade Street
King Philip Street
King Philip Street
199 King Philip Street
Bay Street
Bay Street
450 Charles Street
508 Bowen Street
335 Birch Street
425 Dwelly Street
B-4
-------
1.2.1 Tree Filter Site
Site Visit Catch Basins
Sanitary Sewer Catch Basins
Sewer Pipes
Contours (2 ft)
Parcels
Site 1 Drainage Area
Birch Street Drainage Basin
NAD
Fall River: Site 1
1983 StatePlane Massachusetts Mainland TIPS 2001
Map Produced
N
A
0
0
80
160
20 40
k TETRATECH
Source: Tetra Tech, Inc.
Figure B-2. Map of retrofit site I drainage area
B-5
-------
Photo credit: Tetra Tech, Inc.
Figure B-3. Site I is located at the intersection of Dwell/ and King Streets
Photo credit: Tetra Tech, Inc.
Figure B-4. Site I does not exhibit significant nearby structures or overhead utilities
B-6
-------
Photo credit: Tetra Tech, Inc.
Figure B-5. The existing inlet type for site I is a Bradley
B-7
-------
1.2.2 Tree Filter Site 2
Site visit Catch Basins
Sanitary Sewer Catch Basins
Sewer Pipes
Contours (2 ft)
Parcels
Site 2 Drainage Area
Birch Street Drainage Basin
Fall River: Site 2
NADJ383_StatePlane_Massachusetts_Mainland_FIP3_2001
Map Produced 09 11 2014 A. Portcous
Source: Terra Tech, Inc.
Figure B-6. Map of retrofit site 2 drainage area
B-8
-------
Photo credit: Tetra Tech, Inc.
Figure B-7. Site 2 is located away from infrastructure and overhead utilities
B-9
-------
1.2.3 Tree Filter Site 3
Legend
• Site Visit Catch Basins
Sanitary Sewer Catch Basins
Sewer Pipes
Contours (2 ft)
Parcels
Site 3 Drainage Area
Birch Street Drainage Basin
Fall River: Site 3
NAD_i983_SiaiePlane_Massactiusetts_Mainlan
-------
Photo credit: Tetra Tech, Inc.
Figure B-9. Site 3 is located at the intersection of Slade and King Street
B-ll
-------
1.2.4 Tree Filter Site 4
Legend
Site Visit Catch Basins
Sanitary Sewer Catch Basins
Sewer Pipes
Contours (2 ft)
Parcels
Site 4 Drainage Area
Birch Street Drainage Basin
110
Feet
30
I Meters
Fall River: Site 4
Source: Tetra Tech, Inc.
Figure B-10. Map of retrofit site 4 drainage area
B-12
-------
Photo credit: Tetra Tech, Inc.
Figure B-1 I. Site 4 is located adjacent to a large park
B-13
-------
1.2.5 Tree Filter Site 5
Site Visit Catch Basins
Sanitary Sewer Catch Basins
Sewer Pipes
Contours (2 ft)
Parcels
Site 5 Drainage Area
Birch Street Drainage Basin
Fall River: Site 5
NAD_1983_StalePlane_Massacnusetts_Mainlana_FIPS_2001
Map Produced 09-11-2014 -A. Porteous
Source: Tetra Tech, Inc.
Figure B-12. Map of retrofit site 5 drainage area
B-14
-------
Photo credit: Tetra Tech, Inc.
Figure B-l 3. Site 5 is also located adjacent to a large park
B-15
-------
1.2.6 Tree Filter Site 6
Legend
• Site Visit Catch Basins
o Sanitary Sewer Catch
Drainage Area
Drainage Basin
Fall River: Site 6
Map Produced 09-11-2014 -A. Porteous
Source: Tetra Tech, Inc.
Figure B-14. Map of retrofit site 6 drainage area
B-16
-------
Photo credit: Google Streetview
Figure B-15. Site 6 is located at the bottom of a slope along King Phillip Street
B-17
-------
1.2.7 Tree Filter Site 7
Legend
• Site Visit Catch Basins
'- Sanitary Sewer Catch Basins
Sewer Pipes
Contours (2 ft)
Parcels
Site 7 Drainage Area
Birch Street Drainage Basin
NAD_i983_StatePlane_Massachusetts_Mainland_FIPS_2CiOi
Map Produced 09-11-2014 -A Porteous
Source: Tetra Tech, Inc.
Figure B-16. Map of retrofit site 7 drainage area
B-18
-------
Photo credit: Tetra Tech, Inc.
Figure B-17. Crumbling sidewalk around site 7
Photo credit: Tetra Tech, Inc.
Figure B-18. Site 7 is located adjacent to multifamily housing
B-19
-------
1.2.8 Tree Filter Site 8
• Site Visit Catch Basins
Sanitary Sewer Catch Basins
Sewer Pipes
Contours (2 ft)
Parcels
Site 8 Drainage Area
Birch Street Drainage Basin
62.5
125
—i Feet
NAD_1983_StatePlane_Massacr)useus_Mainland_FIPS_2001
Map Produced 09-11-2014 -A. Porteous
15
30
in Meters
TETRA TECH
Source: Tetra Tech, Inc.
Figure B-19. Map of retrofit site 8 drainage area
B-20
-------
Photo credit: Tetra Tech, Inc.
Figure B-20. Crumbling sidewalk at site 8
Photo credit: Tetra Tech, Inc.
Figure B-21. No significant or minor conflicts at site 8
B-21
-------
1.2.9 Tree Filter Site 9
Site Visit Catch Basins
Sanitary Sewer Catch Basins
Sewer Pipes
Contours (2 ft)
Parcels
\//'_ Site 9 Drainage Area
Birch Street Drainage Basin
210
_Feet
60
Meters
Fall River: Site 9
NAD_1983_StatePlarte_Massacrmsetts_Matrtland_FIPS_2001
Map Produced 09-11-2014 -A, Porteous
Source: Tetra Tech, Inc.
Figure B-22. Map of retrofit site 9 drainage area
B-22
-------
Photo credit: Tetra Tech, Inc.
Figure B-23. Site 9 is located at the intersection of Bowen and Charles Streets
Photo credit: Tetra Tech, Inc.
Figure B-24. Site 9 exhibits no adjacent structural conflicts
B-23
-------
1.2.10 Tree Filter Site 10
9 Site Visit Catch Basins
'. Sanitary Sewer Catch Basins
Sewer Pipes
Contours (2 ft)
Parcels
Site 10 Drainage Area
Birch Street Drainage Basin
Fall River: Site 10
NAD_1903_SlaleP!ane_Massachusett3_Mainland_riPS_2001
Map Produced 09-11-2014 -A. Porteous
Source: Tetra Tech, Inc.
Figure B-25. Map of retrofit site 10 drainage area
B-24
-------
Photo credit: Tetra Tech, Inc.
Figure B-26. Site 10 is located at the intersection of Penn and Bowen Streets
Photo credit: Tetra Tech, Inc.
Figure B-27. An existing stop sign will need to be relocated
B-25
-------
1.2.1 I Tree Filter Site II
Legend
• Site Visit Catch Basins
c Sanitary Sewer Catch Basins
Sewer Pipes
Contours (2 ft)
Parcels
Site 11 Drainage Area
Birch Street Drainage Basin
Fall River: Site 11
NAU_1983_SlatePlane_Massachusett5_Mainland_HHi;_2Um
Map Produced 09-11-2014 -A- Porteous
Source: Tetra Tech, Inc.
Figure B-28. Map of retrofit site I I drainage area
B-26
-------
Photo credit: Tetra Tech, Inc.
Figure B-29. An aging tree at site I I will need to be removed
B-27
-------
1.2.12 Tree Filter Site 12
Legend
• Site Visit Catch Basins
• Sanitary Sewer Catch Basins
Sewer Pipes
Contours (2 ft)
Parcels
Site 12 Drainage Area
Birch Street Drainage Basin
140
_Fee1
40
I Meters
Fall River: Site 12
NAD 1983 StaiePlane Massachusetts Mainland FIPS 2001
Map Produced 00-11-2014 -A Porteous
Source: Tetra Tech, Inc.
Figure B-30. Map of retrofit site I I drainage area
B-28
-------
Photo credit: Tetra Tech, Inc.
Figure B-31. This crosswalk at site 12 may need to be relocated
B-29
-------
Appendix C: Tree Filter Fact Sheet
c-i
-------
What is a Tree Filter?
Tree filters are stormwater catch basins which incorporate a planting chamber
containing a specially engineered soil which filters stormwater runoff to remove
pollutants. The chamber holding the soil is sized so that it can accommodate a tree
or shrub enhancing the filtering of the soil while also improving street aesthetics and
providing shade. Tree filters are an important tool for the City of Fall River to reduce
the environmental impact of stormwater runoff and protect Mt. Hope Bay while
incorporating trees along the roadways.
How are they installed?
Tree filters are designed to fit within the existing street corridor specifically between
the curb edge and the outer edge of the right of way replacing existing catch basins.
During installation heavy equipment is used to remove the existing catch basin and
portions of the existing sidewalk and street surface. Once a tree filter is installed these
features are replaced retaining roadway and pedestrian functions.
What trees can be planted?
Trees used in tree filters should be capable of thriving in the urban environment along city
streets. They should be size limiting so that their root systems do not exceed the space
available within the filter chamber and they should be hardy to the stormwater flow and
pollutants which flow through the filter. The following is a list of trees which have been
identified as meeting these criteria which are available in Fall River.
Crabapple
Dogwood
Hawthorne
How are they maintained?
Like any landscape feature tree filters require
ongoing maintenance to ensure that the tree is
provided with a healthy growing. This includes checking
the tree for illness or nutrient deficiencies and if needed
pruning to remove dead of diseased limbs. Additionally
since tree filters capture debris and sediment carried by
stormwater runoff these items must be removed
from time to time to ensure that the filters
continue to function. This requires removal
of the metal grate around the tree trunk
and using a vacuum truck to remove
collected debris. Additionally it may be
necessary to replenish the layer of
mulch on top of the engineered soil.
Japanese Tree Lilac
Cherry Plum
Service Berry (single stem)
------- |