The Importance of Operation and Maintenance for the Long-Term
Success of Green Infrastructure
A Review of Green Infrastructure O&M Practices in ARRA Clean Water State Revolving Fund Projects
AEPA
Clean Water
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Executive Summary
Green infrastructure reduces storm water pollution by infiltrating, evapotranspiring, capturing, and
using rainwater, and can be used to replace or augment traditional or gray storm water infrastructure.
The use of green infrastructure as a storm water management strategy can help communities and other
stakeholders effectively address some of our nation's most pressing water quality concerns.
On February 17, 2009, the American Recovery and Reinvestment Act (ARRA) was signed into law.
ARRA appropriated $4 billion dollars to the Environmental Protection Agency's (EPA) Clean Water
State Revolving Fund (CWSRF). ARRA included several new requirements for the CWSRF, one of
which was to establish a Green Project Reserve (GPR). The GPR specified that 20 percent of ARRA
CWSRF funds be directed to four categories of projects: green infrastructure, water efficiency
improvements, energy efficiency improvements, and environmentally innovative activities. The ARRA
GPR provided the opportunity for eligible CWSRF recipients to implement a variety of green
infrastructure approaches , whether for the first time or as a way to add to their existing green
infrastructure portfolio. Through the CWSRF Green Project Reserve, 259 green infrastructure
projects worth over $209 million were funded. These projects include a variety of green infrastructure
practices such as rain gardens, pervious pavement, constructed wetlands, rain barrels, bioswales, and
green roofs. Similar to traditional or gray infrastructure, the long-term success of green infrastructure
is dependent on adequate maintenance. While maintenance needs for gray infrastructure are well-
established, there is less research and information available on green infrastructure operation and
maintenance (O&M). This report is intended to provide information for communities and funders to
help ensure that ARRA-funded green infrastructure projects are operated and maintained to optimize
long-term performance and effectively assist communities in reducing storm water runoff and
improving water quality. Other communities may also find this report useful.
The report examines the O&M practices of 22 green infrastructure projects funded by the ARRA
CWSRF, and highlights both the opportunities and challenges associated with green infrastructure
O&M. Activities examined
include planning and tracking
of maintenance, training and
education, use of partnerships,
and funding. Although there
was significant variability in
these activities across projects,
there were some trends that
emerged. Fifty-five percent of
the projects were found to
have accountability
mechanisms, such as an O&M
plan or manual in place, and 27
percent have established
a
ri-
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Data downloaded from the EPA Clean Water Benefits Reporting System on January 24, 2011 capturing ARRA GPR data
through the quarter ending 12/31/2010.
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tracking systems, such as manual log forms and electronic database systems to document and track
maintenance activities. Tracking systems can help communities identify gaps in current maintenance
practices and help establish more preventative and effective maintenance controls. Fifty-nine percent of
the projects have also developed training or education programs related to O&M. Many of the green
infrastructure projects profiled in this report depend on involvement from community members and
volunteers, and in addition to providing practical instruction, training can provide valuable information
on the environmental benefits and important water quality impact that green infrastructure can have
when properly maintained. In approximately 36 percent of the projects profiled, public-private
partnerships were developed to provide funding or labor for O&M activities. Fifty-nine percent of the
projects have a dedicated source of funding established. Funding sources range from the use of
municipal or district general funds to stormwater utility fees. The four projects with storm water
utilities in place have varying rate structures, ranging from a flat monthly service charge to fees charged
based on the amount of impervious surface in residential and commercial areas. The report also found
that having some type of authority in place to assure compliance, such as maintenance agreements or
legal agreements with private landowners, residents, or contractors, can provide a strong incentive for
responsible parties to ensure that proper maintenance activities are performed at regular intervals.
While maintenance plans and strategies vary by project and project type, the findings in this report
demonstrate that proper maintenance is essential to maximizing the environmental, social, and
economic benefits of green infrastructure, as well as ensuring that projects perform as they were
designed to. Whether green infrastructure activities are implemented to meet regulatory requirements
or as a voluntary effort to improve water quality, establishing written plans and procedures to assure
long-term maintenance is important in ensuring the success of the project.
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Introduction
Growth in urban and suburban communities across the country has reduced available rainwater
infiltration and natural groundwater recharge areas where land is covered by buildings, parking lots,
roads, sidewalks, and other impervious surfaces. In areas with high levels of impervious surfaces, rain
events result in increased concentrations of pollutants in storm water runoff as well as a higher volume
of runoff. It is estimated that the runoff volume generated by impervious surfaces can be as much as 20
times greater than the volume in undisturbed watersheds, and can lead to flooding and erosion of
streambeds and streambanks.2 Traditional or gray stormwater infrastructure is designed to collect and
convey stormwater into municipal storm sewer systems, where it is often discharged untreated into
area waterways. Although untreated stormwater is cleaner than wastewater, it still carries pollutants
from impervious surfaces. In communities with combined wastewater and stormwater systems, the
water is sent through the sewer system to a treatment plant, which cleans the water and then discharges
it into local waterways. When large storm events send more water into the combined sewer system
than can be conveyed and treated, it causes a combined sewer overflow (CSO) that releases untreated
wastewater directly into area waterways. CSO discharges are often detrimental to the receiving
waterbody and can result in water quality violations. Green infrastructure approaches to stormwater
management can be successful tools for reducing the pollutant loads and volume of stormwater runoff,
as well as the frequency of CSOs.
The U.S. Environmental Protection Agency defines green infrastructure as approaches and technologies
that maintain and restore natural hydrology by infiltrating, evapotranspiring, capturing and using
stormwater.3 Green infrastructure includes a wide array of practices at multiple scales. At its largest
scale, the preservation and restoration of natural landscape features such as forests and wetlands are
integral components of green stormwater infrastructure. By protecting these ecologically sensitive
areas, communities can improve water quality and provide wildlife habitat and opportunities for
outdoor recreation. On a smaller scale, green infrastructure consists of site- and neighborhood-specific
practices such as rain gardens, porous pavement, green roofs, trees and tree boxes, and rainwater
harvesting for non-potable uses such as toilet flushing and landscape irrigation. Green infrastructure has
numerous environmental, social, and economic benefits that include stormwater runoff volume and
pollutant reduction, reduced sewer overflow events, flood prevention, enhanced groundwater
recharge, increased carbon sequestration, increased land values, urban beautification, reduced urban
heat island effects, and reduced energy demands. This report focuses on the smaller scale green
infrastructure efforts to help manage runoff and improve water quality in urbanized areas, as these
efforts are increasingly being implemented by communities.
All stormwater management systems, whether gray or green, require maintenance. Appropriate
operation and maintenance activities ensure that green infrastructure will continue to function properly
and yield expected water quality and environmental benefits, protect public safety, meet legal
standards, and protect communities' financial investment. If properly constructed and maintained,
Lampe et al (2005). Performance and Whole-Life Casts of Best Management Practices and Sustainable Urban Drainage Systems. Water
EnvironmentResearch Foundation.
U.S. EPA. Managing Wet Weatherwith Green Infrastructure. Retrieved October 21, 2011. Available at:
http: / / water. epa.gov/ infrastructure / greeninfrastructure / index, cfm
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studies have shown that green infrastructure is capable of near complete attenuation of storm water flow
volume, with mean flow volume reductions measuring 99 percent for reported storm events. In
addition, these types of projects can also cost less to construct than gray stormwater technologies.
Green infrastructure proponents also claim that green infrastructure practices can potentially reduce
traditional municipal infrastructure and utility maintenance costs. Unlike gray wastewater
infrastructure, there is not a nation-wide standard for the operation and maintenance of green
infrastructure, although there is a rapidly growing body of literature on proper O&M for various green
infrastructure activities. One challenge facing communities is funding green infrastructure
O&M. Many water quality funding programs, such as the Clean Water State Revolving Fund (see text
box on page 5) can fund the construction and limited monitoring of green infrastructure, but cannot
fund ongoing O&M activities. Operation and maintenance of green stormwater infrastructure is an
evolving area that has been steadily gaining importance as the environmental, social, and economic
benefits of these types of projects are recognized by a growing number of communities.
This report provides an overview of O&M practices and highlights both the opportunities and
challenges associated with green infrastructure O&M. It documents lessons learned from the green
infrastructure projects funded by the CWSRF under the American Recovery and Reinvestment Act.
The purpose of this report is to provide information to communities and operators of funding
programs, such as the CWSRF, to help ensure that ARRA-funded green infrastructure projects, once
implemented, are operated and maintained in such a way that they remain successful over the long-
term and effectively assist communities in meeting their water quality goals.
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Horner, R. et al (2002). Hydrologic Monitoring of the Seattle Ultra-Urban Stormwater Management Projects. University of Washington
Department of Civil and Environmental Engineering. Water Resources Series No. 170 available at:
https:// www. Seattle. gov/util/groups/public/@spu/@usm/documents/ webcontent/spu02_020016.pdf
Low Impact Development Center (2002). Municipal Guide to Low Impact Development. Retrieved November 1, 2011. Available at:
http://lowimpactdevelopment.org/lid%20articles/Municipal_LID.pdf
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Financing Green Infrastructure Through the Clean Water State Revolving Fund
The Clean Water State Revolving Fund program was established in 1987 through amendments to
the Clean Water Act. Each year since the inception of the program, the federal government has
appropriated funds to EPA, which are then distributed to states based on a formula set in the
enabling legislation. Today, all fifty states and Puerto Rico have active CWSRF programs that
provide low-cost financing to a variety of water quality projects, including traditional municipal
wastewater treatment projects as well as nonpoint source, watershed protection or restoration, and
estuary management projects. Green infrastructure practices are eligible for CWSRF funding, but
historically the majority of program funding has been directed to the construction, repair,
replacement, and rehabilitation of traditional municipal wastewater and stormwater infrastructure.
In 2007, EPA released a draft white paper, The Clean Water State Revolving Fund Program: Tapping its
Untapped Potential, highlighting the potential uses of CWSRF funding for green stormwater
infrastructure projects to address point and nonpoint source pollution.
The American Recovery and Reinvestment Act was signed into law on February 17, 2009 and
appropriated $4 billion to the CWSRF. Along with the money came several new requirements,
including the requirement to establish a Green Project Reserve. Under the GPR, to the extent that
there were sufficient applications, each state CWSRF program was to allocate at least 20 percent of
its ARRA funds to four categories of projects: green infrastructure, water efficiency improvements,
energy efficiency improvements, or environmentally innovative activities. Of the $4 billion that was
appropriated to the CWSRF, $1.1 billion went to GPR-eligible projects, of which $209 million
went towards 259 green infrastructure projects. Projects include rain gardens, green roofs,
vegetated swales, rainwater harvesting, constructed wetlands, porous pavement in parking lots,
bike lanes and other impervious surfaces, and riparian and shoreline restoration efforts. The ARRA
GPR provided a catalyst for state CWSRF programs to fund an unprecedented number of green
infrastructure projects to manage stormwater and improve water quality. Similar to ARRA, the
EPA appropriation bills for Fiscal Years 2010 and 2011 specify that at least 20 percent of a state's
CWSRF capitalization grant be directed to projects that qualify for the GPR. For FY 2012, the GPR
requirement was reduced to at least 10 percent of each state's CWSRF capitalization grant.
Data downloaded from the EPA Clean Water Benefits Reporting System (CBR) on January 24, 2011 capturing ARRA GPR
data through the quarter ending 12/3172010.
Thirty ARRA CWSRF green infrastructure projects from across the country were contacted to participate in this report. Of the
30, 23 are represented. The other seven project sponsors either did not respond or did not have sufficient information on their
projects' O&M activities to be included.
Research and interviews were conducted with representatives from 22 green infrastructure projects
funded by the ARRA CWSRF to determine what type of plans are in place to inspect and maintain
these projects, and how these activities are funded and implemented. Where available, maintenance
cost estimates for these projects are included. Though the profiled projects exhibit significant variation -SL
in scope, size, and combinations of green infrastructure approaches used, the majority include efforts to ง
establish some form of long-term operation and maintenance structures to protect each respective c
infrastructure investment. c
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Green Infrastructure O&M: Challenges and Opportunities
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The role of green infrastructure as an effective storm water management solution is increasingly the
focus of environmental stakeholders and of federal, state, and local governments. In 2008, EPA
partnered with environmental and trade organizations such as American Rivers, the Natural Resources
Defense Council, the National Association of Clean Water Agencies, the Low Impact Development
Center, and the Association of Clean Water Administrators to develop a national green infrastructure
strategy, Managing Wet Weather with Green Infrastructure: Action Strategy 2008. The strategy recognized
many of the water quality impacts associated with hydrologic modification, increased urbanization of
our nation's watersheds and the problems resulting from stormwater runoff. In April 2011, EPA
launched the Strategic Agenda to Protect Waters and Build More Livable Communities through Green
Infrastructure. The Agenda updates the 2008 strategy and outlines activities that the Agency will
undertake to help communities implement green infrastructure approaches. The Agenda also calls for
the development of green infrastructure O&M best practice guidelines and cost comparison tools. In
the wake of ARRA, the EPA CWSRF Branch has held a number of regional workshops that focus on the
Green Project Reserve, opportunities for implementing green infrastructure, and the importance of
O&M in ensuring long-term viability for green infrastructure projects.
One of the challenges communities face when making
stormwater management decisions is determining when a
green solution is the right solution. The most effective
solutions to improving water quality are often not achieved
through traditional stormwater management or through
green infrastructure alone, but through a blend of both
approaches. Because of this, it is important to consider both
gray and green infrastructure alternatives. The planning and
design phase of stormwater infrastructure projects is the most
opportune time to consider integrating green infrastructure
approaches into proposed projects. Factors to consider
include cost-effectiveness, what the short-and long-term environmental benefits are expected to be,
and the anticipated O&M costs. Comparing these costs for both gray and green alternatives over the
anticipated life of a project can yield useful estimates that can aid in the decision-making process.
However, because green infrastructure approaches have not been used as extensively as gray
infrastructure to manage stormwater, the O&M costs are not as well documented and quantified. In
many of the green infrastructure O&M studies that have been conducted to date, estimates of O&M
costs are not based on actual costs, but on engineering estimates. As green infrastructure projects
continue to be implemented by an increasing number of communities, more data on performance,
installation costs, and maintenance costs will become available to better quantify the costs and benefits
of these types of projects.
U.S. EPA (2008). Managing Wet Weather with Green Infrastructure: Action Strategy 2008. Retrieved November 10, 2011. Available
at: http://water.epa.gov/infrastructure/greeninfrastructure/upload/gi_action_strategy.pdf
U.S. EPA (2011). Strategic Agenda to Protect Waters and Build More Livable Communities through Green Infrastructure. Retrieved
November 13, 2011. Available at:
http: / / water. epa. go v/ infrastructure / greeninfrastructure / upload/ gi_agenda_protectwaters. pdf
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Weighing the Cost-Effectiveness of Gray vs. Green Infrastructure
Recent studies have examined the effectiveness of green infrastructure in managing stormwater, as well
as its cost effectiveness when compared to gray infrastructure. One study found that in general, green
infrastructure is just as effective at removing pollutants from stormwater, reducing peak flows, and
mitigating flooding and sedimentation as gray infrastructure, but on average costs 5-30 percent less to
construct and is approximately 25 percent less costly to maintain over the life cycle of a project.
Depending on the project type and scope, green infrastructure can have more intensive maintenance
demands due to the need for greater frequency and subsequent additional labor hours necessary for
optimal performance. However, it is generally a less costly alternative than gray infrastructure due to
savings in installation, cost of maintenance activities, and greater adaptability of the infrastructure.
The University of New Hampshire Stormwater Center conducted a 4-year pilot study that examined
the performance and required maintenance of various types of pervious pavement. The installation
costs of the pervious pavement were found to be 20 - 25 percent higher than the costs for standard,
impervious applications. However, the study results indicated that this type of green infrastructure
demonstrated improved surface infiltration during the winter months and required 75 percent less road
salt application as a result of minimized standing water and ice. This represents a significant water
quality benefit for communities in cold-weather climates who struggle with rising chloride levels in
local rivers and streams. In addition, pervious pavement installations have demonstrated life spans that
exceed 30 years, as
Project Cost-Effectiveness
Ranking Criteria in the CWSRF
The CWSRF program has emphasized the importance of funding the
most cost-effective alternative project solutions. Some state SRF
programs have already built mechanisms for gauging project cost-
effectiveness into their priority ranking systems in which
construction and O&M costs, as well as cost/benefit indicators, are
assessed.
Maryland's CWSRF program has incorporated scoring criteria that
allocates points based on project cost efficiencies using a ratio of
capital costs to acres of drainage area or linear feet of stream
restoration that will be completed by a project.
Pennsylvania's program has a nonpoint source rating system that
includes a cost-effectiveness rating that also factors in anticipated
O&M costs.
compared to traditional
pavement which typically
lasts f 2 - f 5 years in cold
climates.
If installed correctly,
pervious pavement is an
effective design alternative
that can provide many
water quality and economic
benefits. Pervious
pavement has the capability
to provide effective storage
for an area approximately
three times its surface area,
and can retain as much as
10 inches of direct rainfall.
a
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Jaffe, M. et al (2010). The Illinois Green Infrastructure Study: A Report to the Illinois Environmental Protection Agency on the Criteria in
Section 15 of Public Act 96-0026, The Illinois Green Infrastructure for Clean Water Act of 2009. Retrieved October 2, 2011. Available at:
http://www.epa.state.il.us/green-infrastructure/docs/draft-final-report.pdf
Gunderson, J. (2008). Pervious Pavements: New findings about their functionality and performance in cold climates.
Stormwater. Retrieved October 10, 2011 .Available at: http://stormh2o.com/september-2008/pervious-asphalt-concrete-3.aspx.
PI-
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Municipalities are increasingly seeing reduced stormwater treatment costs as a result of using pervious
pavement to treat and reduce the overall volume of stormwater flows.n The use of pervious pavement
also reduces the need for more costly infrastructure traditionally used to manage flow volumes such as
drainage piping and catch basins. Land development that involves a reduced amount of disturbance can
also generate cost savings. The elimination of these types of gray infrastructure installations can provide
a significant cost savings to communities.
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Though there are case studies and modeling scenarios that illustrate the economic benefits of choosing
green infrastructure alternatives, it is important to note that green infrastructure approaches may not
always be less expensive to construct or maintain than gray stormwater infrastructure. This is highly
dependent on a multitude of variables that may include size and surface area, costs of plant materials
and survival rates, proximity to pollution sources, site and slope preparation required, necessary soil
amendments, and the complexity of underdrain systems. Another consideration is the extent of
maintenance necessary for different types of green infrastructure. Some green infrastructure types
require less maintenance than their gray counterparts, while many will require more. Green and gray
infrastructure approaches can be used in concert to address stormwater pollution and runoff, manage
sewer overflows, and provide necessary adaptations to increases in intense storm events. For more
information on green infrastructure planning and modeling tools, see Appendix D.
University of New Hampshire (2011). Forging the Link: Linking the Economic Benefits of Low Impact Development and
Community Decisions. Retrieved November 8, 2011. Available at:
http://www.unh.edu/unhsc/sites/unh.edu.unhsc/files/docs/FTL_Resource%20Manual_LR.pdf
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Designing with Maintenance in Mind
Ensuring that green infrastructure projects are planned and designed with maintenance in mind can
help maximize environmental benefits and reduce the cost of the project over its lifespan. For green
infrastructure projects to capture and infiltrate stormwater onsite to the maximum extent, there are a
number of important O&M factors to consider prior to project implementation. These include:
Type of maintenance to be performed
Frequency of maintenance and available personnel to perform maintenance
Cost of component replacement, e.g. plants, shrubs, porous pavement
Sufficient funds in place to cover O&M activities, including cost of replacement components.
Developing an O&M plan or manual can also help ensure green infrastructure projects maintain long-
term viability and continue to protect water quality and effectively manage stormwater. O&M plans
may include basic elements such as: identification of the party(ies) responsible for maintenance,
maintenance schedules, inspection requirements, frequency of inspections, easements or covenants for
maintenance, and identification of a funding source(s).12 A description of basic maintenance activities
such as weeding, mulching, trimming of shrubs and trees, replanting, sediment and debris removal, and
inlet/outlet cleaning may also be included.
Decatur Street in Edmonston, MD utilizing both green and gray
infrastructure. Photo courtesy of the Town of Edmonston, MD
Without a plan to ensure necessary maintenance is conducted with sufficient frequency, the project
may fail to achieve desired objectives. Failure to properly maintain green infrastructure can lead to
excessive sedimentation, clogged inlets and outlets, loss of vegetative plantings, soil compaction, and
failure to properly infiltrate stormwater. This can lead to additional overflows and have a harmful effect
on water quality, thus negating the original intent of the project. Because projects such as rain gardens,
pervious pavements, and green roofs constitute a relatively new approach to stormwater management,
in many cases communities have had to advocate for these types of projects with stakeholders and rate
payers in order to garner support for them. Projects in disrepair can erode confidence in the viability of
green infrastructure. The proper design, construction, and maintenance of green infrastructure
projects, as well as targeted public education and outreach, can effectively mitigate these issues.
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Tetra Tech (2010). Operation and Maintenance of Green Infrastructure. Retrieved October 2, 2011. Available at:
http:// www. raingardeninitiative.org/documents/pdfs/ 3pm_Maintenance_Christian.pdf.
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Green Infrastructure Project Types
Green infrastructure encompasses abroad spectrum of project types. Assistance recipients who
implemented ARRA GPR-funded projects through the CWSRF program demonstrated creativity in
their use of green infrastructure, employing multiple project types and incorporating green
components into gray infrastructure projects. The variety of project types that were implemented is
reflected in Table 1. Each represents a different method for infiltrating, evapotranspiring, capturing,
and using storm water. Common green infrastructure practices funded by the ARRA CWSRF include:
Pervious pavement: A paved surface that allows for the infiltration of water into a
subsurface storage layer (generally consisting of rock, gravel, or sand). This can be
accomplished either through gaps between paver blocks with permeable infill or vegetation, or
through pavement that is manufactured to be permeable. Permeable paving materials include
porous aggregate, porous turf, open-jointed block, porous concrete, and porous asphalt.
Rain barrels or cisterns: Vessels used to collect rainwater at a particular site. They are often
connected to a downspout to capture runoff from a roof, and the collected water is typically
reused onsite. This conserves potable water in addition to reducing storm water runoff.
Infiltration basins: A shallow depression constructed over permeable soil that temporarily
retains storm water prior to it infiltrating. Infiltration basins reduce runoff and contribute to
groundwater recharge.
Table 1: ARRA GPR Green Infrastructure Projects by Type*
Green roofs: An
area of a building roof
or deck structure that
is intentionally
vegetated to provide
a range of
environmental
benefits that include
reduced runoff.
Green roofs fall into
two broad categories:
extensive green roofs
are those that are
vegetated only with shallowgrowing plants and grasses, while intensive green roofs make use of
a broader range of plants, including shrubs and flowering plants. Green roofs often also reduce
energy costs by providing better building insulation and reducing the urban heat island effect.
Bioretention: Bioretention areas, or rain gardens, are depressed, landscaped areas with
permeable soil that are designed to retain and filter runoff before it is removed through
infiltration or evapotranspiration. They are often applied at small sites, such as in residential
areas, in parking lots, along highways, in urban settings, and adjacent to industrial or
commercial facilities.
Project Type
Pervious pavement
Rain barrels /cisterns
Infiltration basins
Green roofs
Biorention / Bios wales
Wetlands
Riparian/shoreline restoration
No. of Projects
28
17
18
9
S3
27
70
*Some projects include more than one than one type of green infrastructure
and as a result may be double counted.
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Green roof at the EPA Region 8 office in Denver, CO
Bios-wales: Constructed conveyance channels designed to direct stormwater runoff while
reducing velocity of water flow and increasing overall infiltration rates. Vegetated swales allow
for biofiltration processes that partially treat stormwater during conveyance.
Wetlands: Transitional areas between land and water that can have surface or near-surface
water year-round, although some are fully saturated only periodically. They include bogs,
swamps, floodplains, marshes, tidal wetlands, and man-made wetlands.
Riparian/shoreline restoration: Natural areas at the interface between land and water of
rivers, streams, or other water bodies. These are often used in agricultural areas to reduce the
impact of nutrient pollution from animal waste or fertilizers.
More detailed information on the various types of green infrastructure and relevant design and
maintenance considerations can be found in Appendix A, and a summary table of green infrastructure
O&M practices can be found in Appendix B.
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Findings and Results of the ARRA GPR Green Infrastructure O&M
Study
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Green infrastructure O&M practices and activities
were examined for 22 green infrastructure projects
funded through the ARRA CWSRF Green Project
Reserve. On-site visits were conducted at five of the
22 projects to obtain more detailed information on
O&M practices. Complete case studies for each of
the five on-site project visits can be found in
Appendix C. Table 2 provides an overview of the
green infrastructure projects that were included in
the study, as well as their O&M structures.
Information is based on interviews, site visits, and
research that were undertaken for the purposes of
this study.
Some of the projects profiled are in communities
that have previously implemented green
infrastructure projects. For other communities,
ARRA GPR funding provided the opportunity to
use green infrastructure as a stormwater
management strategy for the first time.
Municipalities such as Toledo, OH, Lenexa, KS, and
Spokane, WA have been implementing various
green infrastructure practices such as vegetated
swales and rain gardens for many years. Spokane has
used grass swales for over 25 years with a great deal
of success.13 Similarly, special districts like the Long
Creek Watershed Management District in Maine and non-governmental organizations like the
Chesapeake Bay Trust have also implemented green infrastructure projects prior to the introduction of
the ARRA GPR. However, non-traditional CWSRF recipients such as the Chemung County Library
District in New York, which used ARRA funds to install a green roof at a local library, had never
funded any type of green infrastructure before.
The ARRA GPR provided the opportunity for eligible CWSRF recipients to implement a variety of
green approaches to stormwater management challenges, whether for the first time or as a way to
expand their existing green infrastructure portfolio through the use of such practices as rain gardens,
tree plantings, pervious pavement, rainwater harvesting programs, and green roofs.
55%
59%
27%
59%
36%
23%
36%
Have an O&M plan, manual, or
similar guidelines in place
Have a dedicated revenue
source to pay for O&M
activities
Have a formalized O&M
tracking system
Provide training and/or
educational materials on how to
maintain green infrastructure
Municipality or government
agency is responsible for O&M
Private organizations, entities,
or homeowners are responsible
for O&M
Responsibilities split between
private and public sectors
'Peacock, William R., P.E., City of Spokane (2011). Personal communication with the author
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Table 2: ARRA GPR Green Infrastructure O&M Study: Overview of Maintenance Structures
State
CA
CA
CA
CA
CA
CA
KS
MD
MD
MD
ME
NY
NY
NY
NY
NY
OH
PA
PA
LIT
WA
WA
Project
Sponsor
American
Rivers, Yuba
Watershed
Friends of the
Santa Clara
River
Truckee River
Watershed
Council
Hermosa Beach
Oakland
Literacy for EJ,
Heron's Head
Lenexa
Chesapeake Bay
Trust Anne
Arundel Co.
Takoma Park
Edmonston
Long Creek
Watershed
Management
District
Amherst
Rome
Tioga CSWCD
Chemung
o
County Library
District
Lindenhurst
Memorial
Library
Toledo
Chester CCD
PA
Environmental
Council
Salt Lake
County
Spokane
Olympia
GI
Subcategories
+ ซ
ซ
+ +
ซ
+ + +
+ ซ +
+ +
+ 4
O&M Plan
in Place
S
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O&M responsibilities were classified as municipal, private, or a combination of both. Of the 22 projects
that were included, eight projects shared responsibilities between municipal Public Works departments
and private entities, and eight undertook O&M through municipal efforts alone. Only five projects have
O&M responsibilities assigned solely to private entities or organizations. A little over half of the
projects had developed an O&M plan, manual or similar guidance, as well as provided various
Table 3: O&M Responsibilities and Frequency of Maintenance Required
State
CA
KS
MD
Project
Sponsor
American
Rivers, Yuba
Watershed
Friends of the
Santa Clara
River
Truckee River
Watershed
Council
Hermosa
Beach
Oakland
Literacy for
Environmental
Justice,
Heron' s Head
Lenexa
Chesapeake
Bay Trust
Anne Arundel
County
Takoma Park
Edmonston
Municipal
Responsibilities
Weeding
o
Trash Removal
Clean drainage
structures
Watering
N/A
Inspections
Pump maintenance
Clean baffle box
Clean divergence
Inspections
N/A
Trash removal
Mowing
Clean streamway
irrigation system
Clean pervious
pavement
N/A
Weeding
Trash Removal
Watering
Trash removal
Weeding
o
Inspections
Clean catch basins
Frequency
Maintenance
Performed
(Municipal)
As needed
As needed
2-3 times /week
N/A
As needed
Annually
Annually
N/A
Monthly
As needed
N/A
Quarterly
Bi-weekly
As needed
Daily
As needed
Documen-
tation
Tracking
System
N/A
N/A
No data
Manual
reporting
No data
Manual
Reporting
Electronic
N/A
N/A
N/A
Private
Responsibilities
N/A
Weeding
Replanting
Invasive Species
N/A
N/A
Rain barrel cleaning
Inspections
Weeding
Plant Pruning
Tank cleaning
N/A
Inspection
Trash Removal
Erosion Control
Invasive Species
N/A
Replanting
Fertilizing
Frequency
Maintenance
Performed
(Private)
N/A
As needed
No data
N/A
Annually
Monthly- Quarterly
(differs by
component)
Monthly
Annually
As needed
N/A
Semi- Annually
N/A
As needed
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Table 3 continued: O&M Responsibilities and Frequency of Maintenance Required
State
ME
NY
OH
PA
LIT
WA
Project
Sponsor
Long Creek
Watershed
Management
District
Amherst
Tioga CSWCD
Chemung
County Library
District
Lindenhurst
Memorial Library
Toledo
Chester CCD
PA
Environmental
Council
Salt Lake County
Spokane
Olympia
Municipal
Responsibilities
N/A
N/A
Inspections
Inspections
Watering
Weeding
Inspections
Weeding
Underdrain system
Inspections
Monitoring
Watering
Trash removal
Weeding
Watering
Weeding
Inspections
Catch basin cleaning
o
Underdrain system
Trash removal
Snow removal
Trash removal
Weeding
Irrigation system
Replanting
Frequency
Maintenance
Performed
(Municipal)
N/A
N/A
Annually
Bi-Monthly
No data
No data
As needed
No data
No data
Annually
As needed
Daily
As needed
Documen-
tation
Tracking
System
Electronic
N/A
In development
N/A
N/A
No data
N/A
N/A
No data
Manual
reporting
Manual
reporting
Private
Responsibilities
Inspections
Clean catch basins
Mulching
Weeding
o
Trash removal
Reseeding
Mowing
N/A
N/A
N/A
Rain barrel cleaning
o
Catch basin cleaning
Inspections
Monitoring
Weeding
o
Rain barrel cleaning
o
N/A
Mowing
o
Weeding
o
Trash removal
Replanting
Replanting
Frequency
Maintenance
Performed
(Private)
Annually
As needed
No data
N/A
N/A
N/A
As needed
As needed
No data
N/A
City performs
bi-annual
inspections;
residents perform
maintenance
As needed
informational and educational materials to staff, stakeholders, and residents on how to properly care for
different types of green infrastructure. The majority of the projects did not report having a formalized
documentation or O&M activity tracking system in place. Those that are undertaking such efforts are
predominantly doing so through the use of manual log forms. Though only two projects (the City of
Spokane and the City of Lenexa) currently employ electronic tracking systems, several communities are
in the process of developing systems to manage their O&M responsibilities.
The reported O&M activities are performed at intervals ranging from daily, monthly, quarterly, and
annually. Approximately, 50 percent of the projects with private entities responsible for O&M (sole or
shared with a municipality) report maintenance is performed on an as-needed basis. Sixty-one percent of
the projects in which responsibility for O&M is assumed solely by municipalities had more defined
frequency intervals. Table 3 illustrates the accountability structures and frequency of various O&M
activities for these green infrastructure projects.
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3
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Observed Green Infrastructure O&M Practices
This study highlights a number of common elements shared among green infrastructure projects. Observed
O&M practices from the 22 ARRA-funded green infrastructure projects, as well as from a comprehensive
literature review, include the following:
Accountability mechanisms such as an O&M plan or manual
O Having a written O&M plan, manual, or similar guidance in place helps ensure that project
sponsors are aware of and can be held accountable for O&M responsibilities, and helps ensure
the long-term viability of a project.
Documentation and tracking systems
O Tracking systems can help improve oversight by assisting project sponsors in keeping track of
O&M activities and costs, and by identifying opportunities for more effective strategies for
preventative maintenance. They can also help ensure that green infrastructure projects are
performing as designed.
Training and education
O Effective O&M training is provided in an easy-to-understand format, occurs at regular
intervals, and is targeted to the activities employees or volunteers are expected to perform.
Education and training can also provide information on the water quality and environmental
benefits that green infrastructure can yield when properly maintained.
Partnerships
O Partnerships can help ensure that the necessary resources, such as adequate personnel,
equipment, and funding are in place to maintain the environmental benefits as well as the
aesthetic amenities provided by green infrastructure projects.
Vehicles for compliance assurance
O When multiple parties such as contractors and private landowners are involved in publicly
funded green infrastructure projects, having some type of authority in place to assure
compliance can help communities ensure that maintenance activities are being performed as
expected. Maintenance agreements and local ordinances may include maintenance schedules,
inspection requirements, and permission to access private property, and repercussions for
failure to perform.
Dedicated funding source(s)
O A dedicated source of funding provides a means to cover maintenance costs, including labor,
equipment, and the repair and replacement of green infrastructure components as necessary.
Funding sources used in the projects profiled here include municipal or district general funds
and storm water utility fees.
14 For information on the literature consulted, see "References" in Appendix A.
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Accountability and O&M Plans
Accountability is essential to the success of a project. Many of the projects profiled in this report,
particularly in the smaller communities, had strong support from prominent city officials, such as the
Mayor or City Council members, and they helped facilitate implementation of the project. The projects
are well maintained as a result of their continuing support, even when no formal O&M plan is in place.
When these individuals leave office however, the support may not be as strong and new officials may
choose to direct funding to other efforts. To hold public officials accountable and help ensure green
infrastructure project maintenance is not at the mercy of changing municipal priorities, communities or
sponsoring organizations can develop an O&M plan that clearly states who is responsible for
maintenance, what the funding source is, and the environmental benefits to the community when the
project is properly maintained.
The EcoCenter at Heron's Head Park in San Francisco, CA developed an O&M Plan that includes a
description of O&M activities and monitoring procedures, as well as work sheets and record-keeping
forms for components of the facility. The O&M Plan will be reviewed and updated once a year or after
significant system changes. The EcoCenter at Heron's Head Park is run by the organization Literacy for
Environmental Justice in San Francisco, CA and serves as a learning center for community youth on
issues such as energy efficiency, water conservation, and green infrastructure. The EcoCenter used
ARRA funds for constructed wetlands that are used to treat its own wastewater, a green roof, rain
Table 4: EcoCenter at Heron's Head Park Maintenance Schedule
Task
Settling Tank Inspection
Advantex Unit Inspection
(Control Panel)
LIV Disinfection System
Inspection and Cleaning
Drip Irrigation
Disposal Field Inspection
Pump Inspections
Constructed Wetland
Weed Control
Constructed Wetland
Native Plant Inspections
Constructed Wetland
Native Plant Pruning
Constructed Wetland
Cutback Native Species
Constructed Wetland
Inspect for anoxic conditions
LIV Disinfection System
Lamp Replacement
Setting Tank Pumping
Advantex Unit Cleaning
o
Testing Remote Emergency
Alarm System
Frequency
Quarterly
Quarterly
Annually
Quarterly
Quarterly
Monthly
Monthly
Annual
Annual
Weekly
Every 2 Years
Every 3-5 Years,
or as needed
Every 3-5 Years,
or as needed
Annual
Year 201 1
Ql
X
X
X
X
M
M
W
Q2
X
X
X
X
M
M
X
X
W
X
Q3
X
X
X
X
M
M
W
Q4
X
X
X
X
X
M
M
W
Year 20 12
Ql
X
X
X
X
M
M
W
Q2
X
X
X
X
M
M
X
X
W
X
Q3
X
X
X
X
M
M
W
Q4
X
X
X
X
X
M
M
W
X
Year 20 13
Ql
X
X
X
X
M
M
W
Q2
X
X
X
X
M
M
X
X
W
X
Q3
X
X
X
X
M
M
W
Q4
X
X
X
X
X
M
M
W
Year 20 14
Ql
X
X
X
X
M
M
W
X
X
Q2
X
X
X
X
M
M
X
X
W
X
Q3
X
X
X
X
M
M
W
Q4
X
X
X
X
X
M
M
W
X
Year 20 IS
Ql
X
X
X
X
M
M
W
Q2
X
X
X
X
M
M
X
X
W
X
Q3
X
X
X
X
M
M
W
Q4
X
X
X
X
X
M
M
W
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water catchments, and native landscaping. The purpose of the O&M Plan is to "ensure that equipment
is properly functioning, to maximize system reliability, and to ensure that equipment meets its
expected service life and does not require unnecessary and excessive repairs." The Plan includes a
detailed maintenance schedule that very clearly outlines specific maintenance tasks and the frequency at
which they should be performed (Table 4). Having a written maintenance schedule in place that details
the type and frequency of maintenance activities helps ensure long-term project viability.
Documentation and Tracking Systems
Another important element that aids in the effective oversight of O&M is the development of a system
to document and track maintenance activities. This is often part of a computerized maintenance
management system or asset management system that allows for the electronic logging of O&M tasks.
The City of Spokane, WA constructed a network of 37 rain gardens between the curbs and sidewalks to
intercept stormwater runoff on either side of a major thoroughfare. The City's Sewer Maintenance
Division currently uses a system that will link to a GIS platform and enable the City to utilize all of the
laptops that have been deployed in the field. This will allow work orders to be opened and date-
stamped directly from the laptop, eliminating duplication and increasing the accuracy of maintenance
tracking. The City will be using this system to log information that will help the City establish better
preventative maintenance controls for green and gray infrastructure projects throughout the City.
Other forms of documentation and tracking that may also be effective include electronic database
systems, use of time logs or timesheets with specific references to the maintenance activities
performed. Six of the 22 communities that were included in the study reported using some form of
documentation or O&M tracking system. For example, the Long Creek Watershed Management
District in Maine currently uses log sheets and is in the process of developing an electronic database to
track O&M tasks, and Lenexa, KS tracks O&M activities
via an electronic asset management database system.
Regardless of the format, a formalized documentation and
tracking system can assist operators of green infrastructure
projects with keeping track of O&M activities, costs, and
staff time, as well as in identifying opportunities for more
5 effective strategies for preventative maintenance. This can
also help ensure that green infrastructure practices are
performing as designed.
Photo courtesy of Literacy for Environmental Justice,
Training and Education EcoCenter at Heron's Head Park, San Francisco, CA
Education and training is an essential part of O&M. Training courses or workshops for municipal
employees and contractors responsible for green infrastructure O&M are a necessary component of a
well-developed maintenance program. Training targeted to the activities employees are expected to
perform provides practical instruction on the proper care and maintenance of green infrastructure
S-H
S-H
Eckman Environmental Corp. (2011). Operations and Maintenance Guidelinesjor On-Site Wastewater Treatment System at Heron's Head
Park, Pier 98, San Francisco, California. Literacy for Environmental Justice.
16 Schug, Mike, City of Spokane (2011). Personal communication with the author.
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projects. Training can also provide information on the environmental benefits and important water
quality impact that green infrastructure can have when properly maintained.
Many green infrastructure projects are often implemented by private landowners, nonprofit
organizations or other nontraditional CWSRF recipients, and may rely on private residents or
volunteers to conduct project maintenance. In these cases, many of the individuals involved may not
have experience performing the maintenance activities required for the project to function optimally.
To prevent this from causing problems, successful projects not only have an O&M plan in place, but
have also conducted public education efforts, outreach campaigns, and training programs. Friends of
the Santa Clara River, a nonprofit organization sponsoring a constructed wetland and riparian
restoration project in California, conducts training workshops at the project site to educate volunteers
on the necessary maintenance required, which includes identification and removal of invasive plant
species. The cities of Toledo, OH, Oakland, CA, and Spokane, WA have implemented green
infrastructure projects on private property or provided rain barrels or cisterns to private
landowners/residents. These municipalities have provided detailed brochures, manuals, and one-on-
one training sessions with residents and private landowners on how to properly care for their green
infrastructure. Taking steps to educate individuals about required maintenance can prevent accidental
damage to the system, such as removal of native species or application of strong pesticides, herbicides,
or other chemicals that are undesirable in the watershed.
The Maywood Avenue project in Toledo uses rain gardens, bioswales, porous pavement, and rain
barrels as a strategy to mitigate CSO events and improve water quality in the Maumee Watershed. The
City of Toledo and Lucas County in Ohio created a website (www.raingardeninitiative.org) dedicated
to green infrastructure stormwater management solutions. It contains educational materials, including
A Homeowner's How-To Guide: Rain Gardens Jor Northwest Ohio, which provides detailed guidance on:
Benefits of rain gardens and how they work
Location considerations
Determining the slope
Proper sizing and identification of the drainage area
Soil testing and selection
Choosing the right native plants K
Required maintenance o
Common mistakes and how to correct them ฃ^
ง
According to Patekka Bannister, Stormwater Specialist with the City of Toledo's Public Utilities g-<
Department, involving the community and empowering the residents by connecting them to their "^
water resources, teaching them to be better stewards, promoting environmental education and ^
awareness, and providing a homeowner maintenance manual and individual trainings are the key to the o
success of this project. ฃ
Toledo-Lucas County Rain Garden Initiative (201 \).A Homeowner's How-To Guide: Rain GardensJor Northwest Ohio. Retrieved
September 29, 2011 .Available at http://www.raingardeninitiative.org/documents/pdfs/NW_Ohio_Manual.pdf.
18 Bannister, Patekka Pope, City of Toledo (2011). Personal communication with the author.
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Partnerships and Contracting
Partnerships are an important component of many green infrastructure O&M strategies. The City of
Olympia, WA's Yauger Park stormwater improvement project was implemented by the City's
Department of Public Works (DPW) and includes the construction of a porous pavement parking lot, a
rain garden, and constructed wetlands in a high-use urban park. Although maintenance activities are
paid for with revenues from DPW's stormwater utility fee, the Olympia Parks Department is
responsible for maintenance activities of the rain gardens and other landscaped areas of Yauger Park.
Unlike gray infrastructure, green infrastructure is highly visible to the public and is often considered an
aesthetic amenity. As a result, the quality and quantity of maintenance that green infrastructure projects
receive is often influenced by public expectations of how green space should look. DPW will perform
bi-monthly inspections to ensure proper maintenance activities are being performed by the City's Parks
Department's expectations of how green space should look. DPW performs bi-monthly inspections to
ensure proper maintenance activities are being performed by the City's Parks Department and that the
rain gardens and other vegetated areas of the park are maintained at a weed-free level.19 The
partnership between DPW and the Parks Department helps ensure that the necessary resources,
including adequate staffing levels, equipment, and funding are in place to maintain the environmental
benefits and the aesthetic amenities provided by this highly visible urban stormwater improvement
project.
Some projects have elected to enlist contractors to perform some of the required maintenance activities
such as inspections, application of fertilizers/fungicide, pumping, tank cleaning, or removal of trash
and debris. The City of Hermosa Beach, CA entered into an agreement with the Los Angeles County
Flood Control District as well as a third-party contractor to establish roles and responsibilities for this
full-scale pilot project to determine the effectiveness of subsurface infiltration in an urban beach
environment in controlling stormwater run-off and pollution. The City maintains the infiltration trench
downstream from the pump station, the private contractor is responsible for the cleaning of the baffle
box, and Los Angeles County maintains the divergent structure, tide gate, and pump.
Compliance Assurance
S-H
-w When multiple parties are involved, including contractors, private landowners and/or homeowners, as
2 well as the various municipal departments that may be responsible for performing O&M activities,
a many municipalities have found it useful to have some form of authority in place to assure compliance.
~jj In the event that a responsible party fails to fulfill its maintenance duties and the project is in danger of
ฃ falling into damage or disrepair, having some kind of legal authority can help bring such issues to a
^ formalized resolution. A number of the communities profiled in this report have secured such authority
through binding, legal agreements with private landowners, residents, and contractors. The Long
^ Creek Watershed Management District in Cumberland County, Maine, entered into individual
^ contracts with each of the private landowners involved in this stormwater improvement and riparian
^ restoration project. These contracts require the landowners to perform minimum good housekeeping
standards that include landscape and winter maintenance such as removal of debris, sediment and
floatables, sweeping, and vacuuming. Other communities profiled for this report that entered into
' Haub, Andy, City of Olympia (2011). Personal communication with the author.
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maintenance agreements with private
landowners and residents include the
Chesapeake Bay Trust and Anne Arundel
County, MD, the City of Toledo, OH, and the
City of Spokane, WA. Maintenance agreements
may include elements such as a clear description
of the maintenance to be performed,
maintenance schedules, inspection
requirements, establishment of permission to
access the green infrastructure project or enter
onto the property where it is located, and
P P .1 p r i Photo courtesy of Lindenhurst Memorial Library, Lindenhurst, NY
repercussions tor failure to perform, rurtnermore,
maintenance agreements be recorded with the city and County Recorder to ensure that the
requirements remain bound to the property in perpetuity. 2ฐ This practice can help to ensure
maintenance activities continue with the transfers of property ownership and also provides clear
documentation of responsibilities that are conveyed with the title.
In the absence of maintenance agreements, communities can also rely upon local ordinances to provide
compliance assurance. The City of Toledo, in addition to its individual contracts with residents for the
maintenance of the Maywood Avenue project, can also turn to the Toledo Municipal Code, which
passed an emergency ordinance (Ord. 253-09) in April 2009 that amends the municipal code to include
requirements for the design, construction, and maintenance of pervious parking/surfaces, bioretention
areas, and rain gardens. Section 1108.0206 of the Municipal Code specifically requires that
"bioretention area(s) shall be maintained by the property owner for its intended function for the
duration of its life." Without some form of legal authority to assure compliance, municipal
storm water managers are left with little or no recourse available to require at least minimal
maintenance activities that will assure the viability of green infrastructure projects. As a result,
investments in these types of capital improvement projects may be jeopardized if measures are not
taken to ensure accountability, identify acceptable design, construction, and maintenance
requirements, and clearly articulate the repercussions for failure to perform such requirements.
These measures are necessary for green infrastructure to continue to gain acceptance as an effective
storm water management solution on par with gray infrastructure.
Funding
The establishment of a dedicated source of funding that will allow for a budget capable of covering the
costs associated with maintenance, staff, equipment, and the repair and replacement of green
infrastructure components as necessary, helps to ensure the continued success of an O&M system for
green infrastructure projects. Table 5 illustrates the average costs of maintaining green infrastructure as
reported by five of the 22 projects profiled in this report. Overall, 59 percent of the respondents
Storm water Center (2011). Maintenance Agreements and Arrangements. Retrieved November 4, 2011. Available at:
http: / / www. storm watercenter .net/ Manual_Builder/ Maintenance_Manual /4Maintenance_Agreements/ Maintenance%2 OAgre
ements%20Introduction.htm
Toledo Municipal Code. Retrieved November 15, 2011. Available at:
http://www.toledo.oh.gov/LinkClick.aspx?fileticket=_rblqNBBQ2I%3D&tabid=310
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reported having a dedicated source of funding that would be used to help fund the O&M activities
necessary to properly care for and protect these green infrastructure projects.
Table 5: Average Annual Cost of Green Infrastructure O&M for Selected ARRA Clean
Water SRF Projects*
State
ME
MD
KS
CA
WA
Project Sponsor
Long Creed Watershed
Management District
Edmonston
Lenexa
American Rivers
Yuba Watershed
Olympia
Type of GI
BMP
++ +
+ +
+ +
Average cost of
O&M
$78,308, annually
(includes all monitoring
and equipment costs)
$15,000- $20,000
annual operating budget
$19, 140 annually
$780- $2, 440 annually
for O&M and necessary
plant replacements
$100, 000 budgeted for
first year, with plans to
reduce in future years
O&M Funding
Sources
Participating landowners
fee assessment by
LCWMD
Facility maintenance
operating budget
Stormwater utility fees
Included in existing
county maintenance
budget
Stormwater utility fees
* Estimated project costs vary due to project scope, size, and location
Bioretention/Bioswales ^ Riparian Restoration ^ Rainwater Harvesting (rain barrels
and cisterns)
Wetlands
Green Roof
Pervious Pavement
Vegetative Plantings
(Including Trees)
Unspecified green Stormwater
Improvement projects/BMPs
While there are a number of potential grant and loan options for implementing green infrastructure
solutions, those funds generally will not pay for the operations and maintenance of this infrastructure.
Consequently, some communities have established user fees for Stormwater infrastructure, similar to
those for traditional wastewater infrastructure to aid in funding O&M activities. Others have used
municipal or district general funds for this purpose.
The findings from this study of 22 ARRA-funded green infrastructure projects indicate that
municipalities with more experience with green infrastructure (Spokane, Olympia, Lenexa, and
Toledo) have a Stormwater utility that collects fees dedicated to the maintenance of these systems.
Typically, the rates assessed to customers are based on the amount of impervious surface area on a
residential or commercial basis. For instance, the City of Lenexa bases its Stormwater fees on
$7.50/Equivalent Dwelling Unit (EDU). The City of Spokane charges commercial properties per
impervious acre while residential properties are assessed a flat rate. The City of Olympia also has a
Stormwater utility that is administered through the Department of Public Works. Olympia residents
and businesses are charged a flat monthly Stormwater service charge. The primary difference between a
Stormwater utility and a conventional municipal Stormwater management program is that a utility has
the authority to charge fees, which enables it to act independently of municipal general taxation
processes. Stormwater utilities can also implement watershed-based planning and regional Stormwater
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management solutions.22These utilities play an
important role in spreading awareness about storm water
pollution. According to Raylene Gennett, the Storm
Water District Supervisor for the City of Spokane, the
creation of a storm water utility with discrete and
separate rates has helped increase public awareness of
storm water issues.
For those projects in communities that do not have a
storm water utility, several different methods of
generating revenues were observed that include the use
of a municipal or special district general fund or a facility
maintenance operating budget, the establishment of
landowner fee assessments, and partnerships. In
Maryland, the City of Takoma Park and the Town of
Edmonston's green infrastructure projects are paid for
out of the respective communities' facility maintenance
operating budget and general operating fund. The Long
Creek Watershed Management District in Cumberland
County, Maine undertook an innovative approach to
addressing the need for a revenue source to maintain this large riparian restoration project that spans
across several municipalities within the Long Creek Watershed. Landowners were given the option of
participating in a group permit at a cost of $3,000/acre of impervious surface annually for ten years, or
securing individual permits at a cost estimated to be approximately double that of the group permit.
Almost all of the landowners entered into an agreement to participate in the group permit, accounting
for over 91 percent of the impervious surface area in the watershed. The assessments are expected to
generate approximately $1.6 million in the first year to pay for O&M, equipment, administration, and
water quality monitoring efforts.23
The City of Rome, NY relies on its continuing partnerships with the National Grid Power Company
and the Division of Urban Forestry to cover the cost of small tree plantings and maintenance for their
urban canopy restoration project. This project includes tree plantings to reduce stormwater runoff and
the replacement of impervious surfaces with pervious rubber pavement. National Grid has helped pay
up to one-half of the costs for tree plantings under overhead conductors and will continue to support
green infrastructure projects, canopy restoration in the downtown area, and other urban
neighborhoods. While O&M is not eligible for funding under the CWSRF, the program is able to fund
project-monitoring activities for the purposes of assessing the effectiveness of green stormwater
management practices for up to three years for green infrastructure projects that are not required by a
Photo courtesy of the Town of Edmonston, MD
Fuss & O'Neill (2010). Technical Memorandum: Evaluating the Role of Stormwater Utility Districts in the Implementation of Low Impact
Development. Retrieved September 28, 2011. Available at:
http:// www.ct.gov/dep/lib/dep/ water/nps/swgp/tm2_role_swu.pdf.
23 Buranen, Margaret (2010).The Restoration of Long Creek. Stormwater. Retrieved October 12, 2011 .Available at:
http: //www. stormh2o.com/november-december-2010/restoration-long-creek.aspx.
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NPDES permit. However, communities will still need to ensure they have funds for operations and
maintenance, and funds for project monitoring, if needed, beyond the three-year period.
Conclusion
The use of green infrastructure as an urban storm water management strategy can help communities and
other stakeholders effectively address some of our nation's most pressing water quality concerns. There
are numerous environmental, social, and economic benefits that may be realized when proper
consideration is given to size, scope, and maintenance needs of green infrastructure projects. The 22
ARRA CWSRF Green Project Reserve projects that were profiled for this study illustrate the variety of
green infrastructure practices and projects that can be used to effectively manage storm water, as well as
the necessary O&M structures to ensure that these projects continue to function as intended over the
long-term. Though the findings in this report demonstrate that one size does not fit all when it comes
to green infrastructure and its proper maintenance, there were common and overarching themes
applicable to the projects that were identified. These include: the establishment of accountability and
maintenance schedules through an O&M plan, the tracking and documentation of maintenance
activities, training and education on green infrastructure maintenance, the presence of mechanisms to
ensure compliance, and the importance of securing a dedicated source of funding to pay for O&M.
Projects that use green infrastructure to address storm water runoff and sewer overflows will continue
to gain traction within the CWSRF program through the Green Project Reserve. These types of
projects are also gaining increasing visibility through EPA initiatives such as the Agency's Strategic
Agenda to Protect Waters and Build More Livable Communities through Green Infrastructure, and
through the work of communities and environmental organizations across the country. As green
infrastructure becomes more integrated into the traditional storm water management framework, there
will be more opportunities for improved research and better quantification of the benefits of these
types of projects. Opportunities will also increase for communities and other stakeholders to share in
lessons learned and to develop and implement maintenance programs specifically targeted toward
green infrastructure.
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Appendix A - Green Infrastructure Design and Maintenance Practices
The maintenance needs of various types of green infrastructure vary considerably by type and design.
As green infrastructure approaches to stormwater management become more common within the
CWSRF program, understanding these maintenance requirements is critical for the success of projects.
Green infrastructure is new to many communities, and many CWSRF assistance recipients are
unfamiliar with the O&M costs and activities for these types of projects. Although the CWSRF program
cannot provide funding for O&M activities, ensuring that assistance recipients have adequate capacity to
maintain projects after construction is complete is vital to achieving water quality objectives. For green
infrastructure, this means not only that the community has financial resources, but also the knowledge
base to maintain projects appropriately.
This appendix is intended to provide more detailed information about green infrastructure and
familiarize CWSRF funders and assistance recipients with common practices for green infrastructure
operation and maintenance. Information was gathered from academic sources, state and local
guidelines, and industry publications. It is intended to present a broad overview of requirements and
highlight the most important considerations for each project type. Because O&M should be evaluated
by a community during the project planning phase, important design elements that can influence long-
term maintenance needs and costs are included as well.
O&M information is presented by project type, and a summary is presented in Appendix B. The
information in these sections is primarily summarized from sources identified in the reference section at
the end of this Appendix, except where otherwise noted. These references can also be used as sources
of more comprehensive technical information on specific project types.
Overview of Green Infrastructure Types
The water treatment benefits provided by green infrastructure are due largely to the effects of filtration
and retention. Various project types make use of natural ecosystem processes to remove pollutants
from stormwater by filtering runoff through a moist, vegetated environment. Retaining stormwater
helps to reduce the overall flow volume, while also providing time and an environment for removal of
the water by infiltration, evapotranspiration, or capture and use. These methods provide an o^
inexpensive way to improve water quality, and projects of this type often bring the aesthetic benefits of ^!
additional green space to communities as well. ~-^
>-(
Water quality improvements can result from several different processes. First, passing water over a ง
vegetated area slows flow rates and moderates the impact of peak flows during high volume events by ^
providing temporary retention for runoff. When water speed is slowed, sediment and other suspended g^
solids settle to the bottom the same way they would in a traditional settling pond. Similarly, capture of Ef
rainwater for later use reduces peak flow and may prevent some pollutants from entering water bodies. o
Direct benefits are also achieved from vegetation itself. Many plants have the capacity to remove ^
pollutants such as excess nutrients, organic compounds, metals, and other contaminants. Allowing
runoff to infiltrate into soil also creates an opportunity for pollutants to filter out as the water flows
through the soil.
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3
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All types of green infrastructure rely on the processes described above to improve water quality to
some extent. The following section reviews general design and maintenance practices for those green
infrastructure systems that are most commonly funded by the CWSRF. Detail on specific concerns for
each project type is presented after the general discussion.
Design and Maintenance
The design of green infrastructure systems can be very significant to long-term maintenance needs and
costs. In addition to selecting the correct type of project for the circumstances, of primary importance
during the planning phase is designing a project appropriate for local climate and rainfall patterns. It is
common for a system designed to absorb storm water to be designed to accommodate the flow volume
typical of a large, periodic storm event in that location, such as a 2-year, 5-year, or 10-year storm
event. Alternatively, they may be designed with a mechanism to control overflow, such as with an
underdrain or diversion to a storm drain system. The permeability of soil for both conveyance and
detention or retention areas in a project should allow sufficient infiltration to prevent undesirable
pooling. In some cases, this may mean that an engineered soil design will be necessary.
Design should also consider the potential for erosion, which can be a problem if substrate is
insufficiently secured, if there are steep slopes, or if the system experiences particularly high flow rates.
Where water flows into a system, slopes should be sufficient to allow for continuous flow without
being damaged by erosion. Erosion will reduce the effectiveness and the life span of the system and can
allow channels to form through the system. Weed mats, hardwood mulch, or similar materials can be
used to secure substrate and reduce erosion. In extreme cases, periodic re-grading of slopes and
replanting of damaged vegetation may be necessary.
In systems that include vegetation, plants should be selected
to thrive in the local climate, with native species being most
desirable. Vegetation should be hardy enough to withstand
extremes of precipitation and temperature, as well as the
expected concentration and type of pollutants. This will
help to increase the rates of plant survival and minimize
maintenance costs for communities.
Ensuring the health of vegetative plantings is also important
to the success of many systems. The first one to three years
or growing seasons is the most critical time for vegetation
and is known as the establishment period. In some cases
contractors involved in construction will consider the establishment phase a part of construction or
cover costs of maintenance during the first year under a warranty or guarantee. For communities
unfamiliar with green infrastructure maintenance, such a provision can greatly assist the success of a
project during the critical establishment phase. Examples of best practices during the establishment
period include:
More frequent inspections: Inspections should occur every few weeks and follow major rain events, to
ensure that growth is going as planned and desirable species are not being crowded out by weeds.
The Benefits of Native Vegetation
in Green Infrastructure
Native species are best adapted to an
area's existing climate and
precipitation patterns. Therefore
they are likely to require minimal, if
any, irrigation or fertilization once
established, will be better equipped
to compete with weeds in the area,
and will contribute to ecological
restoration of the area.
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Plant maintenance: Weed removal, extra watering, and minimal fertilization may be necessary as the
young plants take root. Herbicides are not recommended for weed removal, due to the difficulty of
preventing the herbicide from entering groundwater.
Erosion control: Additional erosion control may be necessary in this period, as roots may not be deep
enough yet to limit erosion, and the soil will have recently been disturbed.
Minimize shock to plants: Where an inflow control mechanism exists, minimize wastewater or
storm water entering the system to reduce shock to the newly planted vegetation. Polluted water can
begin to be introduced as plants establish. A good sign that plants are thriving in their new environment
is when they begin to put out new growth.
Compensate for short growing seasons: In cold climates, the planting of larger, more mature plants
may help to accelerate establishment.
Subsequent to the establishment period, required maintenance is generally not as intensive. Regular
inspections can be reduced to three to five times a year. Additional inspections can be conducted as-
needed following major rain events or during snowmelt, due to high flow rates and the possibility of
damage to plants. Inspection should include both monitoring and routine activities to ensure the success
of the system, including removal of trash and debris.
During inspections, removal of weeds and invasive
species, as well as replacement of desirable plants
that have been damaged or died, can help to maintain
system health. In general, about 85 percent of land
area should have healthy vegetation.24 In some
systems, such as grassed swales or riparian areas,
regular mowing will improve the aesthetic
appearance and help spur growth of plants.
However, this is not appropriate for all project
types, especially those with a landscaped design, such
as rain gardens or green roofs. Similarly, periodic
harvesting is also sometimes used to spur plant
growth, but should be carefully considered before
employed. While there are documented benefits to plant harvesting in some systems, it can damage
habitat and decrease the rate of maturation of the ecosystem. Choices about plant harvesting should be
made on a case-by-case basis, depending on the needs of the system and the intended goals of the
project.25
Photo courtesy of Literacy for Environmental Justice,
EcoCenter at Heron's Head Park, San Francisco, CA
Pennsylvania Department of Environmental Protection (2006).Pennsylvania Stormwater Best Management Practices Manual.
Retrieved December 5, 2011 .Available at: http://www.stormwaterpa.org/assets/media/BMP_manual/07_Chapter_6.pdf
25 US EPA (2008). A Handbook ojConstructed Wetlands. Retrieved December 15, 2011 .Available at
http:// water, epa.gov/type/ wetlands/restore/upload/ 1998_04_02_wetlands_pdf_hand.pdf
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Pest control is one final aspect of general maintenance that applies to most
systems. Insects and animals can cause considerable damage if they are not
controlled, and in suburban or urban locations they can contribute to the
project becoming a blight or nuisance. In some cases, such as with riparian
restoration, systems are designed to provide necessary and beneficial
habitat, and in these cases animal and insect life should be welcomed.
There is only cause for concern when the system fosters pests. In moist,
and slow-moving or stagnant, designs, mosquito proliferation is a common
concern. Mosquitoes typically require about 10 days of stagnant water to
breed. However, they may go through their lifecycle in as little as 4.5
days. A good way to prevent mosquito proliferation is to ensure that
water is not allowed to remain undisturbed or pooled for more than a few days. Providing nearby
habitat for natural predators of mosquitoes, such as bats, purple martins, or swallows can also help to
control their populations. Muskrats and geese are also common problematic species. These animals eat
roots of plants, and will burrow or dig to reach them. Deer will also consume a wide variety of plants.
Installation of fencing and utilizing a ground cover, such as chicken wire, can reduce damage from pest
animals by limiting the amount of digging that is possible and protecting root systems. All of these
measures will protect the project and ensure that it remains a positive improvement for communities
that are investing in green infrastructure.
These general aspects of design and maintenance are important for the successful use of green
infrastructure to address water quality and stormwater concerns. More project-specific information for
each of the more common green infrastructure project types funded by the CWSRF is below.
Bioretention Areas
A bioretention area, or rain garden, is an area of land that has been designed to filter or infiltrate
stormwater before it is discharged to a stormdrain or another body of water. Bioretention areas can be
used in residential areas, parking lots, along highways, in urban settings, and adjacent to industrial or
commercial facilities. When well maintained, they bring both water quality and aesthetic benefits, but
their ability to improve water quality depends on a design that is suitable for the location.
3 Bioretention areas are depressed from the surrounding land area and are underlain by a permeable soil.
ง Stormwater that flows in is retained for up to 72 hours before it is infiltrated or removed through
jj evapotranspiration. Critical design elements include size, shape, soil composition, and plant selection.
J-H These ensure the success of the bioretention area and minimize maintenance concerns. Plant selection
in a bioretention area depends on both the location and the expected pollutant load. Areas along
2 roadways or in traffic medians generally include lower-growing plants that can be easily maintained and
do not impact visibility. When constructed near industrial or commercial facilities, high pollutant loads
g!) are likely and mean that hardier plants should be chosen, and that an underdrain and an impervious
http://www. vdh.virginia.gov/lhd/CentralShenandoah/EH/WNV/mosquito_breeding_habitats. htm
27 Rain Barrel Guide. Retrieved October 11, 2011. Available at: http://wwrw.rainbarrelguide.com/safety-maintenance/
zs
Ibid.
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Is Road Salt Damaging to
Wetlands?
De-icing salt in runoff can be
damaging to wetland plants. If
runoff to the wetland is likely to
have high salt content in the
winter, salt-tolerant plants should
be chosen. A grassy buffer installed
adjacent to the wetland to absorb
some of the chlorides will also help
to maintain nlant health.
liner (at least 30 mm thick) are necessary to prevent
groundwater contamination.29 The size and shape of a
bioretention area should be specifically designed for the
amount of rainfall at a given location, with an inflow
mechanism designed to handle appropriate water volumes
without eroding. Often, a vegetated swale is used in
combination with a bioretention area in places with high
volume storm events. Because bioretention areas are not
intended to have permanently standing water, soil design is
critical to ensure the success of the cell at removing
pollutants and infiltrating water. Including a pretreatment
area, such as a grassed swale, prior to the bioretention area
may prevent sedimentation that can cause clogging or disrupt
the soil design. Within the bioretention area, there should be a base consisting of an engineered
mixture of mulch, organic material, and sand layered to achieve the desired infiltration rate. Hardwood
mulch is recommended for the top layer as this can prevent weed growth. For remaining layers,
resources are available to assist planning the appropriate mixture. A base layer of aggregate or gravel to
provide filtration is recommended beneath soil layers. In areas with natural clay or impervious subsoil,
an underdrain may be necessary to ensure sufficient drainage and prevent pooling during high volume
precipitation events.
Constructed Wetlands
Wetlands are transitional areas between land and water that can have surface or near-surface water
year-round, although some are fully saturated only periodically. Constructed wetlands are a common
method for treating runoff by recreating natural
hydrological processes that improve water quality.
r- What's the Difference? They often include a mechanism for controlling the
\lthough the terms are often used rate of inflow' as wel1 as a drain or other outflow
..!.-, _i-i_. j_~ -"...: ...j__ป structure to enhance control in case there is a need for
ioretention Areas vs. Rain Gar
- What's the Difference?
Although the terms are often used
interchangeably, the term "rain garden"
usually refers to a well-landscaped,
manicured bioretention area with a variety
of plants selected for both aesthetics and
their effectiveness at managing
stormwater. This type of bioretention area
is common in residential and high visibility
urban settings. Generally, they do require
a higher degree of maintenance to
maintain appearance.
repairs or an unusual flow event. Unlike some types of
green infrastructure, constructed wetlands are
typically designed to fit into the existing environment
and often are intended to restore habitat as well as
improve water quality. In order to minimize
maintenance needs, wetlands should be fit into the
existing topography of the site. By designing them this
way, water flows and wetland plants will work more
smoothly with nature, making it possible to capitalize
on beneficial ecosystem services. There have been
Prince George's County, MD Department of Environmental Resources, Environmental Services Division (2009). Bioretention
Manual. Retrieved October 21, 2011. Available at
http:/ /www. princegeorgescountymd.gov/ Government/ Agency Index/ DER/ESG/Bioretention/pdf/Bioretention%20Manual_
2009%20Version.pdf.
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anecdotal cases in which wetlands that were not designed to fit into the natural shape of the site cost up
to 20 times as much as those that took such parameters into consideration during project design.30
Maintaining adequate water levels is critically important to the health of the wetland, particularly
during the establishment period. Certain time periods require that particular attention be paid to water
level. For example:
3
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During establishment: Water levels should initially be kept low to allow sufficient oxygen to
reach the roots of young plants they can be increased when the establishment period has
ended.
During periods of high runoff: Water levels should be controlled to prevent overwatering of
plants and shortened residence times that reduce water quality benefits.
During periods of low runoff or high evapotranspiration: Water should be contributed to the
system as necessary to ensure it does not dry out.
During cold weather: As long as water is flowing, even wetlands with a layer of ice should
continue to provide water quality benefits, but colder temperatures are likely to reduce
biological activity. If possible, residence times should be increased to ensure treatment levels
remain adequate. Excess water can be stored for use in dry periods.
To achieve maximum water quality benefits, flow should be
even throughout the wetland. Pooling water or channels will
reduce the overall area of the wetland being used for
infiltration and may create areas where water stagnates,
creating habitat in which insects can breed. Disrupted flow
can result from the roots of woody species, accumulation of
debris, or trash in the wetland. Raking to redistribute
substrate, limiting growth of larger, woody plants, and
removing debris from the wetland can help to prevent these
problems. Accumulation of sediment can also damage plants,
lead to channelization, and reduce infiltration rates. If
sediment accumulation becomes problematic, it should be
removed, either by flushing or by draining and dredging the
area. Similarly, where inflow and outflow structures are
present, they should be checked regularly for clogging, and
flushed or cleaned when necessary.
What is Channelization?
I Channelization occurs when
channels form in the substrate
from water flow. As channels
become more defined, water will
flow more quickly through them,
creating erosion and reducing
infiltration. Channel formation
reduces the surface area that water
travels through and increases flow
rates, reducing the overall
treatment that water receives.
Hiosvisiles
Bioswales, or swales, are a type of constructed conveyance channel that directs storm water runoff
while reducing flow speeds and increasing overall infiltration rates. A swale is a linear, sloped
structure, with a grade that is typically between 1 -3 percent longitudinally, and should not exceed 5-6
' Curatolo, Jim, Upper Susquehanna River Coalition (2011). Personal communication with the author
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percent.31 Swales should drain an area less than 10 acres to prevent erosion and sediment buildup that
can necessitate significant, frequent maintenance and may cause the swale to fail.32
Swales can be used in addition to or in lieu of a traditional storm water conveyance system and come in
two main types: open channel and bioswales/ vegetated swales. The former is not heavily vegetated and
transports stormwater runoff at a reduced velocity, providing minimal filtration along the sides and
base of the channel. Bioswales or vegetated swales have the additional benefit of biofiltration processes
to partially treat stormwater during conveyance. Swales are frequently constructed adjacent to
impervious surfaces such as parking lots or along highways or road medians and can discharge to an
existing stormwater management system, a bioretention area, or an infiltration basin. Because of this,
routine maintenance considerations for the swale may be linked to the maintenance needs for the rest
of the system. The useful lifespan of swales has been estimated at anywhere from 20 50 years.
Erosion is a primary concern for swales. In addition to carefully designing the width and slope of a
swale, deep rooted plants are critical to minimize erosion and ensure the longevity of the swale.
Erosion controls and repair may be required while soil is loose and vegetation is forming; reseeding or
replanting may be necessary in some situations if vegetation does not take hold.
Swales require inspection to ensure their effectiveness and to determine if maintenance is needed to
repair damage to vegetation or the structure of the channel. For an established swale, inspections
should at minimum be conducted annually and after any single event with more than one inch of
rainfall. During inspections, debris and dead vegetation should be removed; otherwise, they will block
the flow of water and result in overflow and further damage. Both the swale inlet and outlet should be
cleared of any material that may block the flow of water. Ponding time must be checked to make sure it
does not exceed 24 48 hours; otherwise, remedial maintenance such as re-grading, tilling, or
replanting may be necessary. 34 If significant sediment build-up occurs, it may be necessary to flush
inflow and outflow drains, as well as infiltration trenches, where they are present. In areas with a cold
climate, the swale should be inspected immediately after spring snowmelt and any remedial
maintenance should be done at that time.
Riparian or Shoreline Buffers
Riparian or shoreline buffers are a natural area at the interface between land and water, such as a river
or lake. They are typically strip-shaped and, as a result of their shape and location, are very well-suited
to capture and slow sheet flow. They are most effective when they can be designed to be continuous. In
contrast to wetlands, riparian buffers are not intended to be fully saturated the majority of the time.
a
Pennsylvania Department of Environmental Protection (2006).Pennsylvania Stormwater Best Management Practices Manual. hj
Retrieved December 5, 2011 .Available at: O
r-t-
http://www.portal.state.pa.us/portal/server.pt/community/best_management_practices_manual/10631
University of Florida (2008).Florida Field Guide to Low Impact Development: Bioswales/Vegetated Swales. Retrieved ^
September 10, 2011 .Available at http://buildgreen.ufl.edu/Fact_sheet_Bioswales_Vegetated_Swales.pdf
Pennsylvania Department of Environmental Protection (2008). Pennsylvania Stormwater Management Plan. Retrieved October
12,2011. Available at http://www.elibrary.dep.state.pa.us/dsweb/Get/Version-48475/05_Chapter_6.pdf
34 Ibid.
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These systems are commonly used as an agricultural BMP, to reduce the impact of runoff containing
high nutrients from animal waste or fertilizers.
Appropriate width of a riparian buffer typically ranges from 35-100 feet. This should be determined
based on the slope and nature of the river. Steeper slopes require greater width as well as deeper root
systems and/or ground cover to limit erosion. Mowing and flow control in riparian buffers is more
complex than in other systems. Due to the additional goal of restoring natural habitat and reducing
erosion, trees, shrubs, and some accumulation of natural debris are desirable in restored riparian areas.
Therefore, mowing should be controlled so as not to inhibit growth of these plants. Because buffers are
designed to have water infiltrate quickly, pooling of water should be minimal. If roots of woody plants
and accumulation of plant debris cause channel formation or uneven flow patterns, raking of substrate
and replacing damaged or dead plants may help to reduce problems.
Infiltration Basins
3
4i
R
When are Infiltration Basins a Ris
sk?
A stormwater pond is an area that is intended to capture water from a severe storm event and store it
for slow release. An infiltration basin is a shallow depression constructed over permeable, uncompacted
soil which captures runoff and retains it temporarily.
They are typically a minimum of 15 feet across and
have a base which is covered by dense vegetation.
Unlike detention ponds, which were not eligible for
the ARRA GPR, an infiltration basin is specifically
designed so that water can pass through a permeable
layer of soil and recharge groundwater. Because the
aim is to ensure runoff infiltrates to groundwater, no
mechanism or structure is constructed to discharge
stormwater during regular conditions. Outflow
mechanisms constructed for an infiltration basin
should only operate during unusually high volume
events to manage overflow. Infiltration basins should
retain water for between 6 and 72 hours.
When considering whether or not to use an
infiltration basin, location-specific concerns are
critical.
Infiltration basins are effective stormwater
management solutions in areas where vegetation
might be minimal and soil compaction may have
A major concern with this type of green
infrastructure is that poor filtration can
result in groundwater contamination. For
this reason infiltration basins have fewer
applications than other types of green
infrastructure. Although they can be
effective when used in conjunction with
other types of green infrastructure, such as
swales, infiltration basins are not a good
option for locations with a high pollutant
load. They also should not be used near
locations where groundwater is
withdrawn for public or private
consumption. If considering an infiltration
basin, it is important to check local
regulations and guidelines to ensure it is
an appropriate solution for your site.
35 Ibid. 33, p. 33
Lowndes, Mary Anne (2004). Infiltration Basins: Post-Construction Stormwater Management Workshops. Wisconsin Department of
Natural Resources. Retrieved December 9, 2011. Available at: http://dnr.wi.gov/runoff/stormwater/post-
constr/Infiltrationbasin. pdf
Southeast Michigan Council of Governments (2008).Low Impact Development Manual Jor Michigan: A Design Guide Jor Implementers
and Reviewers. Retrieved November 12, 2011. Available at:
http:/ /www. semcog.org/uploadedfiles/Progr ams_and_Projects/ Water/Storm water/LID/lid_manual_intro.pdf
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increased runoff and reduced infiltration rates. However, an infiltration basin should not be constructed
too close to buildings or facilities, as they can increase the risk of basement flooding. It is recommended
that the base of an infiltration basin be at least two feet above the seasonal high water table for
groundwater. The location should ideally have soil that is naturally permeable. Infiltration rates will
be difficult to maintain in any area where soil has high clay content. Areas with karst topography should
avoid construction of infiltration basins because of the increased risk for sinkhole formation.
Maintenance for an infiltration basin involves:
Regular inspections to ensure water is draining within 72 hours: If this is not the case, it may be
necessary to clean and flush inflow and outflow mechanisms and remove any sediment build-
up. This is usually done during a time when the basin is completely dry when materials can be
most easily removed.
Mowing, weeding, and debris removal: This should occur on average once per month for most
locations.
Semi-annual or annual inspections: To check for petrocarbon or contaminant build-up,
vegetation health, and any erosive or structural damage. After a few years, it may be necessary
to remove sediment build-up, replant vegetation, and add compost or top soil.
Many states have published documents that provide guidelines to local regulations and conditions for
those considering an infiltration basin. For example, Wisconsin, New Jersey, Michigan, and several
other states have published manuals or presentations regarding the use of infiltration basins. Because
there are more site-specific concerns with this type of green infrastructure, it is critical that local
guidelines and considerations be taken into account during the planning and design of infiltration basins.
Rain Barrels/Cisterns
A rain barrel or cistern is any vessel that is used to collect rainwater at
a particular site. They are often connected to a downspout at a private
residence to capture rainwater that runs off the roof, but they can also
be used on larger buildings, such as schools and libraries. Rain barrels
are typically small, aboveground units, while cisterns are a larger
alternative that is sometimes placed underground. Rain barrels are
most commonly plastic, but cisterns can be constructed of a variety of
materials, such as concrete, plaster, metal, or impervious stones. The
volume of water generated in the collection area during a typical
storm event should be considered in determining what size unit is
most appropriate. As an example, 600 square feet of roof will
New Jersey Department of Environmental Protection (2004). New Jersey Storm water Best Practices Manual. Retrieved
November 28, 2011. Available at: http://www.nj.gov/dep/stormwater/bmp_manual/NJ_SWBMP_9.5.pdf
Schrenkel, Jim. Karst Topography. Retrieved November 29, 2011. Available at:
http://www.dcnr.state.al.us/watchablewildlife/Watchablearticles/karst.cfm
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generate more than 90 gallons of water during a 0.25-inch storm event.
4-0
3
Because rain barrels do not require much technical expertise or maintenance, they are a good option
for homeowners and relatively small sites, where rainwater can be reused on the property. Collected
rain water can either be released slowly to recharge groundwater, or it can be stored for water gardens
or other nonpotable uses. As it is returned to groundwater, the collected rain water is also filtered
through the soil, improving water quality. Reuse of the water makes it possible for homeowners to save
hundreds of gallons of potable water in addition to reducing stormwater runoff.
Rain barrel maintenance is inexpensive and can usually be handled solely by the property owner.
Choosing the correct type and location of rain collection systems can make the process much easier.
Collected rainwater should be accessible and able to be moved to the desired location without moving
the container, either through a gravity-fed line, with a watering can, or using a pump system.
Water should be released slowly onto well-vegetated, stable, and non-eroding soil.
Rain barrels should be placed on level ground to prevent tipping.
Rain barrels should be appropriately sized for the expected amount of runoff. Water should not be
allowed to sit in the rain barrel for long periods of time. If overflow is expected, an overflow hose or
similar mechanism should direct it away from house foundations.
The most important regular maintenance activity for rain barrels is emptying them. This will ensure
that there is room in the barrel for future rain events and prevent undesired overflow. Regularly
emptying the barrel will also prevent water from becoming stagnant and reduce or eliminate other
issues, such as insect or algae problems. Mosquitoes can reproduce in stagnant water in as little as a few
days, so it is important that water is not left undisturbed for long periods of time. If mosquitoes
become a problem, it is possible to purchase nontoxic water additives to help control it. Mosquito
dunks, which can be added to the water to kill mosquito larvae, are inexpensive and nontoxic to
humans and animals. Annual cleaning with a nontoxic cleaner, such as vinegar, or putting a few
tablespoons of bleach in the water will help to prevent water quality problems and algal growth.
Storing the barrel in a dark and shady location will also help to
control algal growth, as light and warmth contribute to an
optimal environment for algae.
'an Rain Water be Collected
in Cold Weather?
If below-freezing temperatures are
common in the winter, the water
collection system should be
disconnected. Empty rain barrels
should be stored upside down to
prevent water or debris from
accumulating inside.
Rain water collection is not appropriate for all sites. The
surfacing material on a roof may introduce pollutants to the
water that will be damaging for plants. Specific concerns
include treated cedar shake roofs, roofs that have asbestos in
the material, and gutters that have lead in the paint or
solder.42 In these cases, rain water harvesting is not
recommended.
Sands, K. and T. Chapman (2003). Rain Barrels Truth or Consequences. Retrieved December 15, 2011. Available at
http://www.epa.gov/owow/NPS/natlstormwater03/32Sands.pdf
Rain Barrel Guide. Retrieved October 11, 2011. Available at http://www.rainbarrelguide.com
Sands, K. and T. Chapman (2003). Rain Barrels Truth or Consequences. Retrieved December 15, 2011 .Available at
http://www.epa.gov/owow/NPS/natlstormwater03/32Sands.pdf
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Permeable Pavement
Permeable or pervious pavement describes paving options that allow for the infiltration of water.
Permeable pavement reduces runoff by allowing infiltration, but because runoff is not always treated, areas
paved with permeable pavement may include a drainage system as well to help prevent groundwater
contamination. Permeable pavement types can be broadly characterized as follows:
Concrete grid: Concrete pavers that include a gap
that can be filled with soil, gravel, or vegetation to
allow for infiltration.
Porous gravel: An alternative to conventional gravel.
Pervious concrete or asphalt: A type of asphalt made
with an aggregate designed to leave significant voids,
which allows for the penetration of water.
Permeable pavers: Permeable or semi-permeable
paving stones placed on a permeable aggregate,
Photo courtesy of Lindenhurst Memorial sometimes with gaps to allow for further infiltration.
Library, Lindenhurst, NY
If well-maintained, permeable pavement can be effective for more than 30 years and can be less costly
over its lifetime than traditional paving methods.
To ensure adequate infiltration, it is important to prevent
clogging of and damage to the pavement. Measures that can
be taken to prevent this include:
Gardens surrounding the paved area should be
planned to prevent sediment running off onto the
pavement.
Permeable pavement should not be installed in areas
with trees and large shrubs. Large roots can damage
the surface and debris from trees can lead to clogs.
Weed growth should be prevented and contained
with controlled use of herbicides when necessary to
prevent cracking of pavements during removal.
During construction, measures should be taken to
limit loose sediment reaching the pavement and to
prevent vehicle or foot traffic from compacting
sediment into pavement pores.
Sand should not be used for snow control. When
necessary, mechanical snow removal is the most
effective for permeable pavements.
Drainage
Ensuring the area on which the
permeable pavement is to be
located has appropriate drainage is
critical to the long-term success of
the project. This will likely need to
be determined by an engineer. Soil
alteration or installation of an
underdrain system may be
necessary, depending on the nature
of the existing soil, the groundwater
depth, and the anticipated pollutant
level in the absorbed runoff. This is
particularly true for permeable
pavements that do not filter as well
as infiltrate. Cold climates will also
have to take into consideration the
potential for frost action on
saturated soil.
ri-
e
Gunderson, J. (2008). Pervious Pavements: New findings about their functionality and performance in cold climates.
Stormwater. September 2008. Available at http://www.stormh2o.com/SW/Articles/1071 .aspx.
44 Ibid. 33, p. 33
-------
Periodically, usually about one to two times a year, sediment will need to be removed. Frequency can
be determined by monitoring infiltration rates. For permeable pavements, vacuuming with a vacuum
sweeper is recommended. For systems that contain infill, such as permeable pavers or concrete grids,
the first W'-l" can be removed and replaced. Clean aggregate can simply be added using a push broom.
For cracked or otherwise damaged pavement, the method of repair will vary depending on the type of
pavement being used. Porous pavement and concrete can be patched most easily and cost effectively
with normal concrete or asphalt; however, if it is a large area that needs patching, this can impact the
effectiveness of the system and an engineer should be consulted. Individual pavers are advantageous
because the paver can simply be replaced. Porous gravel and similar, less structured pavement systems
should be inspected regularly for wear on the material. Uneven compaction could enable the formation
of channels and pools, which will prevent infiltration and could create habitat for insect breeding.
Regular inspections, particularly shortly after installation and following major rain events, should check
for this. Redistribution or addition of fill material where problems are found will help to limit long-
term problems and increase water treatment benefits.
3
4i
q
Green Roofs
A green roof is an area of a building roof or
deck structure that is intentionally vegetated
to provide a range of environmental benefits.
In addition to reducing storm water runoff
levels, green roofs also provide habitat,
improve air quality, and reduce urban heat
island effect.45 By providing greater insulation
than traditional roof structures, green roofs
have been shown to improve the energy
efficiency of buildings and reduce cost and
energy necessary for heating and cooling.
Some Studies suggest that the service life of a Green roof at the EPA Region 8 office in Denver, CO
green roof may be longer than traditional roofing, as water is removed through evapotranspiration and
places less stress on the waterproof lining of the roof itself.
Green roofs typically fall into two broad categories, extensive and intensive green roofs. Extensive
green roofs have a shallow substrate and low-growing vegetation. They consist of simple vegetation
without deep root structures, such as grasses, and require minimal maintenance. Intensive green roofs
have a deeper substrate where a range of vegetation can be grown, including shrubs and flowering
plants. Sometimes called roof gardens, these intensive green roofs require more regular maintenance
and upkeep than their extensive counterparts. Intermediate types which combine features from the two
are referred to as semi-intensive.
U.S. EPA. Heat Island Effect. Retrieved December 2, 2011. Available at: http://www.epa.gov/heatisland/about/index.htm
46 Low Impact Development Center. Green Roofs. Retrieved November 15, 2011. Available at:
http: / /www. lidstorm water, net/ greenroofs_cost. htm
-------
Many state and local guidelines as well as numerous
international standards exist to provide information and
assistance for green roof construction. Internationally, the
German standard is referenced by many national and local
guides. Canada and the United Kingdom have also issued
codes for green roofs. Within the U.S., several states as
well as EPA have issued guidance on design and
maintenance of green roofs. However, even with the
existence of many broad standards to provide background
information, the design of a green roof must carefully
consider the specific site. Overall, a more intensive green
roof will provide more benefits and may achieve objectives beyond storm water management, such as
providing wildlife habitat in an urban or suburban setting. However, intensive green roofs are more
costly and require significantly more maintenance. Green roofs constructed in arid climates or locations
with severe winter weather will also have additional considerations.
The first 12 15 months after construction is considered the establishment phase for a green roof.
During this time, fertilization, irrigation, and regular weeding should be performed to ensure plant
survival. Some contractors will provide a warranty after construction, during which time they will
return to the roof to care for vegetation and replace any dead or diseased plants. Beyond the
establishment phase, extensive green roofs require significantly less irrigation and in some cases may
only require irrigation during drought conditions. These roofs are not maintenance-free, however; they
require inspection to check for leaks, blocked drains, dead vegetation, or debris. This should be done
semi-annually at a minimum. Intensive green roofs will require more frequent inspections. Because
they may include a variety of plants, shrubs, and trees, irrigation may be needed regularly. Many
guidelines suggest installing a recycled water or rain water collection system on-site to minimize cost
and ensure overall water efficiency of the building.
While other types of green infrastructure have largely been researched and piloted by academic groups,
state and local government, and nonprofit coalitions, green roofs are more industry-driven. Low-
impact green roof design is an emerging market, with businesses arising to assist with planning,
consulting, and construction of green roofs. Many of these companies participate in certification
programs such as the U.S. Green Building Council (USGBC) Leadership in Energy and Environmental
Design (LEED) program, an example of the way in which industry-wide coalitions have begun
establishing standards for the industry as green building design becomes more widespread.50
Green Roof Technology. Retrieved November 3, 2011. Available at: http://www.greenrooftechnology.com/industry-
standards
48
Tolderlund, L. et al (2010). Design Guidelines and Maintenance ManualJor Green Roofs in the Semi-Arid and Arid West. Retrieved
October 20, 2011. Available at http://www.epa.gov/region8/greenroof/pdf/GreenRoofsSemiAridAridWest.pdf
Green Roof Organization (2011). GRO: The Green Roof Code Jor the United Kingdom. Retrieved October 14, 2011. Available at
http://www.nfrc.co.uk/docs/initiatives/grogreenroofcodeuk201 lonline.pdf.
50
U.S. Green Building Council. USGBC: LEED. Retrieved December 11, 2011. Available at:
http: / / www. usgbc. org/ DisplayPage. aspx?CategoryID19.
-------
Reference List
Bartsch, L.D. andJ.S. Raible. Bioswales: A Guide to Low-Impact Development Design and Maintenance. Retrieved
October 17, 201 1 .Available at http://arkansaswater. org/319/pdf/OS-
1100%20Urban%20Low%20Impact%20Bioswale%20Binder%20Intro.pdf
California Storm water Quality Association (2003). New Development and Redevelopment Handbook. Retrieved
December IS, 201 1 .Available at http://www.cabmphandbooks.com/Documents/Developnient/Section_6.pdf
City of Eugene, OR (2008). Stormwater Management Manual. Retrieved December IS, 201 1 .Available at
http://www.eugeneor.gov/portal/server.pt?open=512&objID=689&PageID=1795&cached=true&mode=2&userI
D=2
Connecticut Department of Environmental Protection (2004). 2004 Connecticut Stormwater Quality Manual.
Retrieved December IS, 2011. Available at:
http://www.ct.gov/dep/cwp/view.asp?a=2721&q=32S704&depNav_GID=16S4#chapter
Green Roof Organization (201 1). GRO: The Green Roof Code for the United Kingdom. Retrieved October 14,
2011. Available at http://www.nfrc. co.uk/upload/GRO%20CODE%202011.pdf
Hathaway, H.M. et al (2008). A Field Study of Green RoofHydrologic and Water Quality Performance.
Transactions of the American Society of Agricultural and Biological Engineers, Vol. 51, Issue 1: 37-44.
Jurries, D., Oregon Department of Environmental Quality Northwest Region (2003). Biofiltersfor Storm
Water Discharge Pollutant Removal. Retrieved September 9, 201 1 . Available at
www. deq. state, or. us/ wq/storm water /docs/nwr/biofilters.pdf
Lowndes, Mary Anne (2004). Infiltration Basins: Post-Construction Stormwater Management Workshops.
Wisconsin Department of Natural Resources. Retrieved December 9, 201 1 . Available at:
http://dnr.wi.gov/runoff/stormwater/post-constr/Infiltrationbasin.pdf
Massachusetts Low Impact Development Toolkit. Fact Sheet #7: Bioretention Areas. Retrieved September 9,
20 11. Available at
http://www.lowimpactdevelopment.org/raingarden_design/downloads/BioretentionMassachusetts.pdf
3
S-H
-------
Pennsylvania Department of Environmental Protection (2008). Pennsylvania Stormwater Management Plan.
Retrieved October 12, 2011. Available at http://www.elibrary.dep.state.pa.us/dsweb/Get/Version-
48475 /05_Chapter_6 .pdf
PA Department of Environmental Protection (2006). Pennsylvania Stormwater Best Management Practices
Manual. Retrieved December 5, 2011 .Available at http://www.stormwaterpa.org/43
Prince George's County, MD Department of Environmental Resources, Environmental Services Division
(2009). Bioretention Manual. Retrieved October 21, 2011. Available at:
http: //www. princegeorgescountymd.gov/Government/ Agency Index/DER/ESG/Bioretention/pdf/Bioretention%
20Manual_2009%20Version.pdf
Saiz, S. et al (2006). Comparative Life Cycle Assessment of Standard and Green Roofs. Journal of Environmental
Science and Technology, 40, 4312-4316.
Sands, K. and T. Chapman (2003). Rain Barrels Truth or Consequences. Retrieved December IS,
2011 .Available at http://www.epa.gov/owow/NPS/natlstormwater03/32Sands.pdf
Southeast Michigan Council of Governments (2008). Low Impact Development Manual for Michigan: A Design
Guide for Implementers and Reviewers. Retrieved November 12, 2011. Available at:
http ://www.semcog.org/uploadedfiles/Programs_and_Projects/Water/Stormwater/LID/lid_manual_intro.pdf
Tennessee Valley Authority. Riparian Restoration Fact Sheets. Retrieved October 12, 2011 .Available at
http: / /www. tva. go v/river /landandshor e / stabilization/
Tjaden, B. and G.M. Weber (1998). Riparian Forest Buffer Design, Establishment, and Maintenance. Retrieved
October 14, 2011 .Available at http://www.riparianbuffers.umd.edu/fact/FS72S.html
Tolderlund, L. et al (2010). Design Guidelines and Maintenance Manual for Green Roofs in the Semi-Arid and Arid
West. Retrieved October 20, 2011 .Available at
http://www.epa.gov/region8/greenroof/pdf/GreenRoofsSemiAridAridWest.pdf
University of Florida (2008). Florida Field Guide to Low Impact Development: Bioswales/ Vegetated Swales.
Retrieved September 10, 2011 .Available at O
http ://buildgreen.ufl.edu/Fact_sheet_Bioswales_Vegetated_Swales.pdf (ฃC,
O
Urban Drainage and Flood Control District (2010). Urban Storm Drainage Criteria Manual Volume 3. Retrieved ^
September 9, 2011 .Available athttp://www.udfcd.org/downloads/down_critmanual_volIII.htm cx>
ง
US EPA (2008). A Handbook of Constructed Wetlands. Retrieved December IS, 2011 .Available at 5^
http://water, epa.gov/type/wetlands/restore/upload/1998_04_02_wedands_pdf_hand.pdf Q
R
Vermont Agency of Natural Resources (2002). The Vermont Stormwater Management Manual. Retrieved
December IS, 2011 .Available athttp://www.anr.state.vt.us/dec/waterq/stormwater/docs/sw_manual-
voll.pdf
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Appendix B
Summary of Green Infrastructure O&M Requirements
Bioretention
Cells/ Rain
Gardens
Wetlands
Swales
Riparian &
Shoreline
Restoration
Weeding,
Mowing, &
Watering
Necessary on a
regular basis;
o
more frequent
for manicured
cells, in urban
areas, or near
roads / walkways
Seasonal
mowing of
emergent
o
areas; maintain
adequate water
levels for
habitat; regular
removal of
weeds/ woody
growth
Necessary on
an occasional
basis for
vegetated
swales
Seasonal
mowing; water
o
as necessary
during first 3-5
years and dry
periods; mulch
at tree bases;
weeds kept
under ~12
Trash &
Debris
Removal
Necessary on
a regular
&
basis,
particularly in
urban settings
Regular trash
and debris
removal;
debris
should be
prevented
from creating
areas of
pooled water
Removed as
quickly as
possible to
prevent
channel
blockage
o
Trash should
be removed;
natural debris
can be
allowed to
accumulate
Sediment
Removal,
Draining, &
Flushing
As-needed; if
water is
standing for
o
long periods
of time
Sediment
removal at a
predetermine
d depth of
sediment
accumulated
(6-12");
flushing of
inflow/
outflow
mechanisms
when clogged
Not necessary
unless swale is
damaged
Prevention of
channel
formation, as
necessary
Re-grading
& Erosion
Control
As needed for
prevention of
channel
formation or to
repair erosion
damage
As needed for
prevention of
channel
formation
Regularly
during
establishment;
as needed
subsequently to
prevent
channel
blockage
Prevention of
channel
formation, as
necessary;
replanting if
erosion
destabilizes
stream banks
Seasonal
Considerations
Snow removal if
necessary;
monitor to
prevent channel
formation
during
snowmelt
System will be
less effective in
winter, inflow
should be
slowed; irrigate
during dry
periods
As needed after
high volume
winter storms or
snowmelt
Area should not
be disturbed
during the
spring
Plan&
Component
Replacement
Plant
replacement as
necessary;
regular
&
mulching to
minimize weed
growth
As needed;
Plant
replacement as
necessary to
maintain 85%
vegetation
cover of
emergent land
Plant
replacement as
necessary if the
channel is
damaged by
erosion
Plant
replacement as
necessary to
maintain
vegetation cover
of about 85% of
emergent land
Monitoring
&
Inspection
Regular
monitoring
and inspection
to ensure
adequate
infiltration
rate
Several
inspections/y
r
and following
major rain
events and
snowfalls;
Every 2-3
weeks during
o
establishment
Inspect
regularly to
ensure water
is
not pooling
and channel is
not eroded or
damaged
Several
inspections/y
r
and following
&
major rain
events; every
2-3 weeks
during
o
establishment
a
&<
^K
&
PI-
c
TO
-------
Infiltration
Basins
Rain
Barrels/
Cisterns
Pervious
Pavement
Green
Roofs
Weeding,
Mowing, &
Watering
Mowing and
o
weeding
should
be conducted
on average
&
once per
month
N/A
Controlled
herbicide as
necessary so
as
not to disturb
pavement
Irrigation and
fertilization
regularly
during
establishment;
weeding on a
regular basis
subsequently
Trash &
Debris
Removal
As needed
Mesh screen
can filter out
debris
Necessary on
a regular basis
&
Necessary on
a regular
&
basis. Critical
if debris or
dead
vegetation
creates a fire
hazard
Sediment
Removal,
Draining, &
Flushing
Necessary any
time water is
not
infiltrating
within 72
hours
Water should
be removed
7- 10 days
after a rain
event
Vacuuming at
o
a min. of 1-
2x/yr and,
where
present,
flushing of
drainage
system
Drains should
be inspected
regularly
Re-grading
& Erosion
Control
As needed basis
if damage is
Incurred
during a high
volume event
Water should
drain onto
stable, non-
eroding soil
Sediment
should be
prevented
from eroding
directly onto
pavement
N/A
Seasonal
Considerations
Monitor during
snowmelt to
ensure infiltration
rate is maintained
If freezing is
o
common, rain
barrels should be
disconnected, and
stored upside
down; mosquito
dunk may be
needed during
summer
Mechanical snow
removal
(plowing); sand
not
recommended
As needed during
&
high snowfall
volumes
Plan&
Component
Replacement
May be
necessary after
basin has been
in use for
several years
As necessary
Damaged pavers
replaced with
spares; small
areas can also be
repaired with
traditional
pavement.
Infill , can be
replaced with a
broom
As needed;
frequency will
depend on
vegetation type
and roof design
Monitoring &
Inspection
Monitor to
ensure water
infiltrates within
72 hours.
Inspect 1 -2x yr
for contaminant
build-up
Periodically
ensure water is
not running
o
into house
foundations or
erodible areas
l-2x a year; no
standing water
should be on
surface after a
rain event
Regular
inspections;
ensure
compliance with
local guidelines
and/or building
codes
-------
Appendix C
Project Case Studies
Site visits were conducted at five of the 22 green infrastructure projects funded through the ARRA CWSRF
Green Project Reserve that were examined for this report. The following case studies from each site visit
provide detailed information on the project and its O&M activities. The site visits took place at ARRA GPR
projects in:
Spokane, Washington
Edmonston, Maryland
Lenexa, Kansas
Takoma Park, Maryland
Nevada City, California
Spokane Urban Runoff Greenways Ecosystem (SURGE) Project
Spokane, WA
Background
The City of Spokane is located on the Spokane River in eastern Washington and has a population of
almost 210,000 people. Polluted stormwater is now considered the largest source of pollution in the
Spokane River, a tributary of the Columbia River. The City implemented a demonstration program to
construct street-side rain gardens to capture, treat, and infiltrate stormwater runoff as close to where it
falls as possible. The Spokane Urban Runoff Greenway Ecosystem (SURGE) program retrofits existing
urban landscapes around the City using green infrastructure. The SURGE program was conceived prior
to ARRA as a way to achieve municipal stormwater management goals while reducing runoff to the
Spokane River. To fund SURGE efforts, a stormwater utility was created in 1998 with discrete and
separate rates. However, in 2009 ARRA funding was used to sponsor one project as part of the overall
SURGE effort. Because of the ARRA funding that was provided, City leaders were able to justify the
construction of the West Broadway SURGE project, which received $572,839 in ARRA CWSRF
funding, and get the project completed several years earlier than originally planned.
Project Description
The City constructed a network of 37 rain gardens, along with five drainage structures and over 1,200 o
square yards of pervious sidewalk to intercept stormwater runoff on either side of Broadway Avenue q-
between Elm and Oak Streets. To ensure the success of these rain gardens, native vegetation was ^
chosen for its ability to thrive during the long, dry summers and cold, snowy winters of the inland ^
Northwest. Careful selection of the proper soils to augment the treatment and infiltration process was 73-
another specific planning element in the creation of the greenway ecosystem. Each rain garden is ^
comprised of a layering of structural soil, creating a cascading and dynamic system. When capacity is C
reached, stormwater flows past the gardens and is collected in the combined sanitary sewer system. c
One of the more innovative aspects of the West Broadway SURGE was the use of the "tree zone" ^
concept, which encourages planners to take into consideration multiple site conditions such as building
set-back distances and amounts of available sunlight when selecting the types of trees to be planted.
Planners selected five different tree varieties suitable for the existing site conditions.
>-*ป,
-------
O&M Structure and Activities
The City of Spokane formalized their O&M process through a City Council ordinance. The stormwater
utility's 2007 NPDES permit included the requirement for an ordinance to be in place. An ordinance
was passed in April 2010 specifically addressing erosion and sediment stormwater controls.
The West Broadway SURGE, which is located in a commercially zoned part of town and is 100 percent
in the public right-of-way, is maintained by the City's stormwater maintenance division. The City's
maintenance is divided into four quadrants, with each quadrant assigned a maintenance crew. The
Broadway Avenue rain gardens have been added to the annual inspection and cleaning routine for the
maintenance crew assigned to the corresponding quadrant. One of their primary functions is to inspect
and clean catch basins. There is one catch basin crew that monitors the rain gardens, as well as 30 grates
with sumps which were incorporated as part of the rain storm garden infrastructure design.
The O&M annual inspection and cleaning routine undertaken by the City includes the following:
Grates and catch basins are cleaned and sump areas in
the channel between the curb and storm gardens are
pumped out
Trash and debris are removed at entrance and exit pads
and curb-outs
Inspections are conducted of both vegetative plantings
and physical structures (concrete curbing, grates, drains)
and findings are submitted to the Storm Water District
., . rr,.. re , w. Supervisor
Picture courtesy ol City ol Spokane, WA
Sumps are vacuumed when inspections reveal build-up
of sediment and debris
O&M activities required during the winter months largely depend on the amount of snowfall. Snow
and ice can create conditions that do not allow for infiltration to occur. In response, sewer maintenance
crews break, dislodge, and remove ice and excess snowpack as needed. The City does not use sand or
^ salt to maintain roads during the winter months as part of continuing efforts to curtail pollutant loads to
tj the water-quality impaired Spokane River, but instead utilizes a liquid de-icer mix of magnesium
J3 chloride to deal with icy road surfaces. During precipitation events and snowmelt that result in pooling
g and inundation of the rain gardens, the City deploys vactor trucks to pump out excess water on an as-
J? needed basis.
R
W
Maintenance crews document their O&M activities for the SURGE projects on their timesheets using
^ specific references to the sewer and stormwater system map pages. They also identify areas in need of
^ follow-up activities and provide brief status reports on the status of the infrastructure. Timesheets are
ฐo reviewed by the Storm Water District Supervisor.
City representatives indicated that they have not developed a complete plan for green infrastructure
asset management because the City has not accumulated enough operational experience to establish
parameters for its repair, rehabilitation, or replacement. The City is transitioning to a computerized
-------
maintenance management system for tracking operation and maintenance of all of its wastewater and
stormwater projects. The new SURGE program numbers have been assigned and input into the system
with the hope that this information can be used to establish preventative maintenance controls in the
future. Currently, adjacent property owners have primary responsibility for maintenance of vegetation
(e.g., plants, flowers and trees) and weed removal. The City acknowledged that maintenance crews
may need to perform these functions if property owners fail to do so.
The Greening of Decatur Street
Edmonston, MD
Background
Edmonston is a small town with approximately 1,400 residents. It straddles the Northeast Branch of the
Anacostia River and is located 2.5 miles from Washington, D.C. The Anacostia River is one of the
nation's most polluted rivers, and stormwater is a large source of pollution. In an effort to address
these issues and spur green development, Edmonston partnered with the Chesapeake Bay Trust (CBT)
to retrofit one of its busiest streets using green infrastructure. Construction began in November 2009
and was officially completed in November 2010. The project was funded with a $ 1.1 million CWSRF
ARRA loan. EPA Administrator Lisa Jackson was present at the construction launch for this project in
fall 2009 and called Decatur Street "one of the greenest streets in the country."5
Project Description
The project involved narrowing the two-lane Decatur Street to accommodate eight rain gardens, each
with a variety of native grasses, plants, and shrubs. Rainfall is diverted from storm drains into the rain
gardens via an opening in the curb. Non-native trees were replaced with native tree species such as
oaks, maples, and sycamores. Permeable crosswalks and bike lanes were installed to allow more rainfall
to infiltrate the ground. Two types of permeable pavement were used on Decatur Street: interlocking
concrete pavers in the crosswalks and porous asphalt in the bike lanes. Town officials considered
replacing the sidewalks on Decatur Street with pervious pavement but found it would be cost
prohibitive to do so. Instead, the sidewalks were repaved and are now sloped in places to allow water
to drain into the rain gardens. The pervious pavement and the rain gardens are expected to absorb
approximately 80 percent of the runoff from most rainfall events.
Nearby, communities are in the process of implementing green C
infrastructure projects modeled after Edmonston's with the goal of ^
reducing stormwater runoff and protecting the Anacostia River and o
ultimately the Chesapeake Bay. C"
K*
O&M Structure and Activities ป.
^
This project was designed with maintenance in mind. The design 73-
included a variety of hardy native plants, trees, and grasses. Using ฃ
native vegetation served to reduce the amount of watering necessary C
for it to thrive. A local nursery did the initial plantings and in the spring
Photo courtesy of the Town~ of 2011 the Town retained the nursery to inspect the rain gardens,
Edmonston, MD
|-s
cx>
51 Wheeler, Timothy (2009). " Remaking Main Street," The Baltimore Sun. Retrieved June 22, 2010. Available at:
http:// www. baltimoresun.com/features/green/bal-md.gr.street25nov25,0,2052577. story
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apply fertilizer, and conduct a supplementary planting. In the future Edmonston Public Works
maintenance staff will take care of replanting in order to reduce costs. The Town will try to obtain
grant funding to purchase new trees, shrubs, and other vegetation when needed. Edmonston has not
developed a formal maintenance plan for Decatur Street. However, Public Works Department
employees perform daily inspections. Maintenance activities for the rain gardens include daily weeding
and debris removal, watering plants during dry periods, and repair of eroded areas on an as-needed
basis. Pesticides and herbicides are not used in rain garden maintenance. Each rain garden includes an
observation port which permits maintenance personnel to inspect and clean the underdrains, which are
inspected weekly and cleaned as needed. When necessary, areas of bare soil surrounding vegetation and
trees are mulched and trees are trimmed.
Maintenance activities for the pervious surfaces are limited to daily litter and debris removal. Town
officials indicated that the pervious pavement and rain gardens had performed as designed during the
first 11 months of operation.
Edmonston has two Public Works employees responsible for maintenance of the Decatur Street rain
gardens, trees, and pervious pavement as well as maintenance of 14 other rain gardens in the Town.
They are also responsible for mowing public fields, trash pick-up from town property, and various
other tasks. Their salary is paid out of the Town's general fund; Edmonston does not have a stormwater
utility. The Town is planning to hire a part-time employee whose sole responsibility will be
maintenance of Decatur Street as well as the other rain gardens on public property.
Central Green Streamway
Lenexa, KS
Background
Lenexa is a mid-sized community of approximately 48,000 residents located 12 miles south of Kansas
City, MO. The Central Green Streamway Project is part of Lenexa's new City Center North
development, a mixed-use development that will create a new central meeting place for residents with
retail, commercial and entertainment venues. The Lenexa City Center is expected to offer about 4.5
-------
mission is to reduce flooding, protect
environmental and water quality, and provide
recreational and educational opportunities.
O&M Structure and Activities
The City's Municipal Services Stormwater
Division has primary responsibility for O&M
of the Stormwater conveyance portion of the
project, defined as the main channel that lies
between the adjacent paved paths. They have a
10-person crew that monitors both gray and
green Stormwater infrastructure, with a 4-
person crew dedicated to green infrastructure
maintenance. Routine maintenance activities
include vegetation management and trash
pickup. Seasonal maintenance activities include open water management such as cattail removal.
Cattails can reduce the hydraulic capacity of the channel and negatively impact the aesthetic of the open
water. Standard Operating Procedures (SOPs) have been developed for all green infrastructure
maintenance activities, along with fact sheets available on the City's website.
Additional O&M responsibilities are performed by the City's Parks Division and its Streets Division.
Parks is responsible for mowing, the irrigation/water reuse system, and trash pickup for all areas not
maintained by the Stormwater Division. There are two pump systems for irrigation that will require
regular maintenance by Parks. The Streets Division maintains hard surface pathways, performing snow
removal and the repair and replacement of surfaces. Because the project was recently constructed, the
City has not yet integrated the site into their long-term asset management program. However, they do
have expectations for the lifecycle of various components based on experience with similar facilities.
Long-term asset management is projected to include the replacement of the irrigation pumps, repair of
the Stormwater channel due to flood damage, pathway replacement, and pond sediment removal.
The City has a Stormwater utility and has developed an operations budget. Ongoing O&M is paid for
through Stormwater fees based on the amount of impervious area at $7. SO/Equivalent Dwelling Unit
(EDU). A Capital Development Charge is also assessed on new development projects with property
draining to a public facility. The charge can be waived if the developer includes its own 100-year
detention or retention facility.
Task
Wet basin sediment removal
Wet basin general maintenance
o
Native upland plant weeding and replacement
Native wetland plant weeding and replacement
Irrigation pump /pip ing
Timeframe
Forebay, approximately 5 yrs; Entire basin, approximately
Monthly trash removal, annual plant maintenance, cleaning
outlet structure
20 years
out wetland
Monthly during establishment, seasonal thereafter
Monthly during establishment, seasonal thereafter
As needed based on manufacturers' recommendations
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Maintenance schedule developed by the City ofLenexa and its O&M Plan
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Green Roof at Takoma Park Community Center
Takoma Park, MD
Background
The City of Takoma Park has approximately 17,200 residents and shares a border with Washington,
D.C. The Community Center was completed in 2006 and houses several City offices. The 4,000 square
foot green roof was constructed in 2009 on the roof of the Community Center parking deck, accessible
to City employees and the public from the first floor of the building. This was the first green roof to be
installed at a municipal facility and the City undertook the project to help reduce stormwater runoff
and alleviate leakage from the roof to the parking deck below. The roof has an estimated 20-year
service life.
The total project cost was $76,700 and the project received
$69,500 in ARRA CWSRF grant funds.
Although the cost for the green roof was almost double the
cost of a conventional roof, during site visits City officials
indicated they are glad they made the investment because the
green roof is much more attractive and user-friendly than a
conventional roof. A walking path and sitting areas were
incorporated into the design, so the space is attractive and
accessible to staff and building visitors.
Photo courtesy of Takoma Park, MD
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Project Description
The Takoma Park Community Center's green roof is classified as an extensive green roof. Extensive
green roofs have a shallow soil medium, shallowly rooted plants, and comparatively low weight
loadings. These types of green roofs typically have minimal maintenance requirements as compared to
green roofs with a wider variety of vegetation. The green roof is comprised of a sequence of layers:
vegetation rooted in a soil composite, filter fabric, a drain board, a polyisocyanurate insulation layer, a
water impermeable membrane, and a concrete roof deck. Vegetation has been established on the roof
and has achieved a 50 percent ground cover. It is on track to achieve its target ground cover of 80
percent. Vegetation was established using 3-inch plugs of various Sedum varieties. Sedum was chosen
because it is capable of thriving in poor soils and low moisture conditions. The planting medium was
composed of a compacted soil composite layer that is a mix of expanded slate and compost material.
There are two storm drains on the roof, one is located under the pavers and the other is installed near
the center of the roof to collect and drain precipitation that exceeds the infiltrative capacity of the green
roof. The project was included in the City's Watershed Implementation Plan (WIP), which describes
how it aims to meet the Chesapeake Bay Total Maximum Daily Load (TMDL) allocations. The project
is provided as an example of an urban stormwater best management practice that uses environmental
site design (ESD), a comprehensive design strategy for maintaining predevelopment runoff
characteristics and protecting natural resources by integrating site design, natural hydrology, and
smaller controls to capture and treat runoff.
O&M Structure and Activities
The City discussed required maintenance activities with the project designer while the project was still
in development. Indications were that maintenance would be minimal. Maintenance activities in the
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first year following construction included weeding and fungicide application by licensed contractors.
Watering was not required during the six-week plant establishment period as there were heavy spring
rains at the time of project completion. The City had a 2-year maintenance contract, but since
maintenance activities were minimal it did not renew the contract for the second year. Activities were
taken over by City maintenance staff, who already maintain numerous stormwater infiltration basins
throughout the City. City crews inspect the roof bi-weekly and current maintenance activities include
trash and debris removal, quarterly weeding, and removal of dead or dying plants as-needed.
Replanting will take place in spring 2012, and in the future on an as-needed basis. The sub-soil layer
does not receive any type of preventative maintenance. The roof membrane is covered by a 20-year
warranty from the vendor.
The green roof installation did not include an
integrated irrigation system. If rainfall is inadequate,
supplemental watering would be performed by City
maintenance crews through a sprinkler system.
During construction of the green roof, the paved
walkway leading up to the roof was waterproofed to
ensure that water from adjacent surfaces will not
permeate the roof membrane and drain mat. The
funding for green roof maintenance comes out of
Takoma Park's facility maintenance operating
budget.
Photo courtesy of Takoma Park, MD
Stormwater Management in the Yuba Watershed
Nevada City, CA
Background
American Rivers' ARRA-funded CWSRF project involved the construction of green infrastructure
projects at the Rood Center site in Nevada City, CA. Nevada City is located in a rural area of eastern
California and shares a border with Nevada. The Rood Center is a county facility that encompasses
several government buildings, including the Nevada County Government Center building, the Madelyn
Helling Library, and the Rood Government Center building. This project includes one rain garden and
a bioswale, with curb cuts to direct stormwater flow to these features, and a walking path constructed
of permeable concrete. In the construction phase, a second rain garden was also added behind the
library.
Stormwater runoff at the Rood Center empties into the Oregon Ravine, which flows through Nevada
City to Deer Creek, a tributary of the Yuba River. The Yuba River was named by American Rivers as
one of the top ten most endangered rivers in the United States in 2011 because it is one of the few
remaining habitats in California for the threatened Chinook salmon. Additionally, the South fork of
the Yuba River has been designated as a Wild and Scenic River. Working with American Rivers,
Nevada County decided to undertake this water quality improvement project as a part of a greater
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American Rivers. Hydropower Dams Endangering Local Fish Species. Retrieved November 30, 2011. Available at:
http://www.americanrivers.org/our-work/protecting-rivers/endangered-rivers/endangered-yuba.html
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effort to green the area and to protect and improve water quality. Using $375,000 in ARRA funds,
they were able to implement storm water control techniques to reduce pollution reaching the Yuba
River. Construction took place during the summer of 2010 and was complete by the fall of 2010.
O&M Structure and Activities
An O&M manual for the project was prepared by a contractor, Integrated Environmental Restoration
Services, in August 2010. This manual outlines maintenance needs for the various project components
in terms of irrigation, infiltration rates, seed replacement, and drainage structures. As a joint project
between American Rivers and Nevada County, the maintenance plans were designed collaboratively.
However, long-term maintenance responsibilities will be undertaken by Nevada County.
Nevada County and American Rivers have indicated that these green infrastructure systems have been
designed to require minimal maintenance. To that end, native plants were selected that would thrive
even in California's dry summers. Maintenance needs and responsibilities have been incorporated into
the existing maintenance budget and folded into the responsibilities of ground maintenance crews.
Maintenance for the rain gardens and bios wales is expected to be minimal during the first year or two,
while many plants are still establishing and some are still young enough that it is difficult to differentiate
desirable species from weeds. Up to this point, maintenance has generally included irrigation, trash
removal, and weeding when necessary. In general, about one hour has been dedicated to these O&M
activities per month. The maintenance needs are expected to increase as plants get larger and weeding
must take place more frequently. Additionally, it is expected that after about five years some plants will
begin to die off and will require replacement.
The permeable concrete walkway aspect of the project was also designed to entail minimal
maintenance. Because the path is slightly raised, sediment accumulation and clogging are not expected
to be a problem. At this time, no regular maintenance schedule exists for this component of the
project. However, one section of the pavement has heaved, and a plan to replace this section has been
established.
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In addition to regular O&M of the system, monitoring of infiltration rates and water quality
improvements were undertaken for one year by the South Yuba River Citizens League. Between
October 2010 and March 2011, monitoring
took place during the first measurable
storm event and seven subsequent events.
These studies tested water quality influent
and effluent for pollutant concentrations,
total dissolved solids, and total suspended
solids. Overall sediment was found to be
reduced in runoff, as were concentrations
of several pollutants. The bioswale and rain
garden were found to be particularly
effective at reducing lead concentrations,
which initially were well above regulatory
action levels. Photo courtesy of American Rivers
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Appendix D
Green Infrastructure Planning Tools
There are several planning tools that are available online that can assist water quality managers and their
teams in finding the right opportunities for implementing green infrastructure into the existing built
environment as well as in new developments. The Water Environment Research Foundation (WERF)
is a non-profit organization that funds and manages water quality research through a diverse set of
partnerships with municipal utilities, corporations, academia, industry, and the federal government. In
cooperation with the EPA, WERF has developed a set of modeling tools to help water quality managers
make decisions regarding the integration of green infrastructure practices called the LID Whole Life
Cost Models. These models are a comprehensive set of spreadsheet tools that allow the user to examine
the capital costs and ongoing maintenance costs of various types of green infrastructure to help them
determine the estimated costs over the useful life of a project. There are spreadsheet models for each of
the following green infrastructure types :
Swales
Permeable Pavement
Green Roofs
Cisterns
Residential rain gardens
Curb-contained bioretention cells
In-curb planter vaults
Each of the spreadsheet models require user data inputs for parametric cost estimations, watershed
characteristics, facility storage volume capacity, and design and maintenance options to generate
automatic outputs and calculations for estimated capital and whole-life costs, including maintenance
costs. The tool also generates graphs representing the present value cost over time along with
cumulative discounted costs and discounted costs over time.
The O&M costs that were incorporated into the model were developed through a series of interviews
with stormwater management agencies and extensive literature review. However, because of the high
variability in available data, engineering estimates were used. Furthermore, it was not generally
possible to correlate the influence of project size on O&M costs due to the presence of more significant
factors potentially influencing the level of maintenance required for a particular site, such as its ง
proximity to the nearest pollution source. This was the case for the swale and permeable pavement
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models, which do not account for relationships between size and O&M costs. However, the models for g
green roofs, curb -contained bioretention, and rain gardens scale O&M costs relative to the surface area C^
of the installation. The WERF LID Whole Life Cost Models allow the user to anticipate O&M costs ฃ
associated with routine maintenance activities, corrective and unplanned-for activities at their
respective frequency intervals, and a breakdown of activities according to whether they are considered
high, medium, or low in maintenance demand.
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The entire suite of planning tools and the user's guide to the WERF LID Whole Life Cost Models are
available at:
http: / /www. werf. org/ c/ Knowledge Areas / Storm water / ProductsToolsnonWERF / BMP_and_LID_
Whole_Li. aspx
The EPA Green Infrastructure website features a page that includes a wide selection of available
predictive modeling tools and calculators that may be used to help users simulate watershed hydrology
and rainfall-runoff, make informed decisions on pollutant load reductions, and predict the anticipated
benefits and cost savings associated with the inclusion of green infrastructure BMPs into their projects.
Some of these tools can also allow the user to compare the inspection and maintenance costs of
different stormwater BMP systems. This web page
(http://water.epa.gov/infrastructure/greeninfrastructure/gi_modelingtools.cfm) contains links to the
following planning tools:
Casey Trees "Green Build-Out" Model
System for Urban Stormwater Treatment and Analysis Integration (SUSTAIN) model
The Center for Neighborhood Technology Green Valuesฎ Calculator
Virginia Runoff Reduction Method
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