United States
    Environmental Protection
    Agency
                                    EPA/600/R-15/219
                                    October 2015
                                    www2.epa.gov/water-research
Green Infrastructure for Stormwater
Control: Gauging Its Effectiveness with
Community Partners


    Office of Research and Development
    Water Supply and Water Resources Division
                                                   \

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                                                    EPA/600/R-15/219
                                                    October 2015
   Green Infrastructure for Stormwater Control:
Gauging its Effectiveness with Community Partners

                   Summary of EPA GI Reports
                          Prepared by
                     Matthew Hopton, Ph.D.
                   Michelle Simon, Ph.D., P.E.
                         Michael Borst
                  Ahjond Garmestani, Ph.D., J.D.
                          Scott Jacobs
                       Dennis Lye, Ph.D.
                     Thomas O'Connor, P.E.
                     William Shuster, Ph.D.

               U.S. Environmental Protection Agency
                Office of Research and Development
           National Risk Management Research Laboratory
             Water Supply and Water Resources Division
                          Edison, NJ
                        Cincinnati, Ohio
                      Taylor Jarnagin, Ph.D.

              U.S. Environmental Protection Agency
                Office of Research and Development
              National Exposure Research Laboratory
                 Environmental Sciences Division
                     Research Triangle Park
                         Raleigh, NC

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                                     ABSTRACT








This document is a summary of the green infrastructure reports, journal articles, and conference




proceedings published to date.  It is our intention to update this summary as we have more




information to share and when relevant publications are completed. The Environmental




Protection Agency's Office of Research and Development has an ambitious research agenda to




continue quantifying the performance of green infrastructure during the next five years. This




report contains the synopses of the significant findings, lessons learned, and guidance to




communities based on a number of research efforts that included one roof downspout




disconnection, three green plus one conventional roof, two rain garden and  bioretention, and two




permeable pavement research efforts across eight EPA regions.  Some of the research addressed




water quality changes, such as bacteria, chlorides, solids, nutrients, and metals through




individual storm control measures.  Others  studied the aggregate hydrologic response from a




collection of green infrastructure  storm water control measures over areal spaces of one to 100




acres over a period of one to seven years. One study focused on the impact of development due




to the conversion of farm to suburbs for ten years.  In addition to the green  infrastructure




performance studies, twelve sites were systematically characterized for disturbed urban soil




infiltration rates. While this is the most comprehensive summary of the Office of Research and




Development's research efforts to date, the findings of the research for the next five years will




greatly increase our ability to apply green infrastructure.
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                                     DISCLAIMER









The U.S. Environmental Protection Agency, through its Office of Research and Development, funded and




managed, or partially funded and collaborated in, the research described herein.  It has been subjected to




the Agency's administrative review and has been approved for external publication. Any opinions




expressed in this document are those of the author(s) and do not necessarily reflect the views of the




Agency, therefore, no official endorsement should be inferred. Any mention of trade names or




commercial products does not constitute endorsement or recommendation for use.
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                              ACKNOWLEDGEMENTS








The authors of this report appreciate the assistance of Dr. Roberta Campbell and Ms. Josephine Gardiner




provided in generating this document and to Dr. Ariamalar Selvakumar and Mr. Jason Berner for their




thorough and speedy reviews. This research would not have been possible without the cooperation and




support of the communities and various entities and staff within the communities.
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                          TABLE OF CONTENTS


ABSTRACT	2

DISCLAIMER	3

ACKNOWLEDGEMENTS	4

TABLE OF CONTENTS	5

LIST OF ABBREVIATIONS	7

LIST OF ABBREVIATIONS, CONTINUED	8

LIST OF TABLES	9

LIST OF FIGURES	9

EXECUTIVE SUMMARY	10

  Introduction	10
    Infiltration	15
    Hydrology	16
    Water Quality	17
    Place-based	17
    Guidance for stakeholders and decision makers	18
    Future needs (i.e., new questions, where our knowledge is lacking, etc.)	19
    Community Access/General Interest	19
  Summaries of Specific Research Efforts and References	22
    Region 2 - Edison, NJ	22
    Region 2 - New York, NY	26
    Regions - Clarksburg, MD	29
    Regions - State College, PA	31
    Region 4 - Louisville, KY	35

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Region 5 - Cincinnati, OH	38
Region 5 - Cleveland, OH	41
Regions - Detroit, MI	43
Region 6 - Austin, TX	45
Region 7 - Kansas City, MO	47
Region 7 - Omaha, NE	51
Regions -Denver, CO	52
Region 9 - Phoenix, AZ	55
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                            LIST OF ABBREVIATIONS
ASCE         American Society of Civil Engineers
BACI         Before-After-Control-Impact
BMP          Best Management Practices
GATE         Cities and the Environment
CN           Curve Number
CRADA       Cooperative Research and Development Agreement
CSO          Combined Sewer Overflow
CSPA         Clarksburg Special Protection Area
DEP          Department of Environmental Protection
DOI          Digital Object Identifier
EEC          Edison Environmental Center
EISA          Energy Independence and Security Act
EO           Executive Order
EPA          Environmental Protection Agency
ET           EvapoTranspiration
GI            Green Infrastructure
HSPF         Hydrological Simulation Program Fortran
JAWRA       Journal of the American Water Resources Association
KCMO        Kansas City Missouri University
KCWSD       Kansas City Water Services Department
LID          Low Impact Development
LiDAR        Light Detection and Ranging
mm           millimeter
MSD          Metropolitan Sewer District
NPDES        National Pollutant Discharge Elimination System
NYC          New York City
ORD          Office of Research and Development
PA           Porous Asphalt
PC           Pervious Concrete
PICP          Permeable Interlocking Concrete Pavement
RARE         Regional Applied Research Effort
RWH         Rain Water Harvesting
SCM          Storm Control Measures
SSC          Suspended Solids Concentration
SSURGO      Soil Survey Geographical
SUDS         Sustainable Urban Drainage Systems
SUSTAIN      System for Urban Stormwater Treatment and Analysis Integration
SWMM       StormWater Management Model
TC           Total coliform
TDR          Time Domain Reflectometers
TSS          Total Suspended Solids
U.S.          United States
USGS         United States Geological Survey
UV           Ultraviolet
VELMA       Visualizing Ecosystems for Land Management Assessment
VMC          Volumetric Moisture Content
WQ          Water Quality

                                       Page 7 of 57

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                LIST OF ABBREVIATIONS, CONTINUED
WSUD      Water Sensitive Urban Design
WWF       Wet Weather Flow
XPSWMM   XP' s StormWater Management Model
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                                 LIST OF TABLES








Table 1	13




Table 2	14









                                LIST OF FIGURES







Figure 1. Map of EPA ORD green infrastructure research sites (2015)	15




Figure 2. Twelve cities located in each of the major soil orders were sampled to characterize altered




urban soils	16
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                              EXECUTIVE SUMMARY

Introduction

       ORD has worked with numerous U.S. communities to study how green infrastructure

(GI) can be utilized to improve the performance of currently failing wastewater systems, and to

understand better the co-benefits of this approach to water management and related social,

economic, and environmental ramifications. The American Society of Civil Engineers (ASCE)

evaluated the water infrastructure and gave the U.S. a grade of D - because most of our water

infrastructure is nearing the end of its useful life.: Further, EPA has issued 849 combined sewer

overflow (CSO) permits2 that have aggressive deadlines to reduce CSO events that will be very

expensive ($187.9B in the next 20 years) to achieve.3 As communities develop land and alter

land use, difficulties associated with managing stormwater can be expected to increase.

"Gray" stormwater infrastructure is designed largely to move stormwater away from the built

environment, whereas GI reduces the quantity and treats stormwater on site while delivering

many other environmental, social, and economic benefits.4 EPA recommends that communities

use GI whenever  or wherever it can be effective and  economically advantageous  for aging water

infrastructure upgrades.5 This document is a brief summary  of EPA's Gl-related research efforts

and the results to  date from these studies. More detail can be found in the references listed at the

end of each summary. The research efforts are grouped by EPA Region and community.  Each
1 American Society of Civil Engineers http://www.infrastructurereportcard.org/drinking-water/ accessed 7/20/2015
2 EPA's Report to Congress on Implementation and Enforcement of the CSO Control Policy
http://water.epa.gov/polwaste/npdes/cso/upload/csortcappsd s.pdf accessed 7/2/2015
3 Water Environment Federation http://www.wef.org/WaterProtectionReinvestmentAct Summary 080112 accessed
7/21/2015
4 http://water.epa.gov/infrastructure/greeninfrastructure/gi why.cfm accessed 7/21/2015
5 EPA
http://YOsemite.epa.gov/opa/admpress.nsf/3881d73f4d4aaaOb85257359003f5348/5390e840bfOa54d785257881004f9
6dl IQpenDocument accessed 7/20/2015


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summary introduces the collection of papers, a brief description of the research performed, the

research questions asked, and insight from the results of the research.

       To manage stormwater in densely-populated and developed areas, civil engineers have

focused on gray infrastructure to manage stormwater and efficiently move it offsite.  They have

sized and designed gray infrastructure (e.g., pipes, tanks, pumps, etc.) for centuries and have

become very comfortable with such technologies.  However, the U.S. has far less engineering

experience with GI technologies as compared to traditional "gray" infrastructure and there has

been a push to utilize "green" technologies because they can be less impactful to the

environment and may be economically advantageous to communities (i.e., lower installation and

maintenance costs).  Moreover, GI may be less disruptive to the hydrologic cycle because the

intent often is to infiltrate the stormwater rather than move it offsite. Individual GI stormwater

control measures (SCMs)6 (e.g., disconnection of roof down spouts, rain gardens, green roofs,

detention ponds, permeable pavement, etc.) have only been analytically studied for the last

twenty years and studies measuring the aggregated response of many SCMs over large areas and

for multiple years are extremely rare. The overarching goal of EPA's GI research is to quantify

the reduction in stormwater runoff and resulting changes in water quality and other

environmental, economic, and social benefits, and to obtain engineering cost and  design data.

       EPA is examining the costs of design, installation, operation, maintenance, and

replacement for GI with the intent to develop objective data that communities can use when
6 Storm Control Measures (SCMs). Many EPA documents use the term "Best Management Practice (BMPs)" for GI
and Low Impact Development (LID). There has been some reluctance from the regulated community, academics,
and even regulators to continue to use the term owing to the fact that the specific term "Best" implies a high level of
expected performance. Some have referred simply to stormwater management practices. The National Research
Council proposed the term stormwater control measures (SCM). However, as the Clean Water Act (CWA (1977)
specifically refers to "Best Management Practices," BMPs will be the legal name until the CWA is either amended
or superseded. EPA web pages still refer to BMPs.


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considering implementation of GI. To help communities make this decision, EPA is developing

models, such as SWMM, VELMA, and HSPF, and Decision Support Tools, such as the National

Stormwater Calculator, to predict the performance of GI. Communities rely on these models and

tools to help them make what can be multibillion dollar decisions. For example, Kansas City,

MO designed its $10 million 100-acre Middle Blue River pilot on SWMM predictions and,

based on the performance of this 100-acre pilot, it will design its $2 billion, 20-year consent

decree sewer upgrade.7  EPA's stormwater modeling tools are very sophisticated, but EPA will

continue to develop and improve some of these models through validation using field data at

large spatial scales in an effort to assist communities in making sound decisions.

       Presented in Table 1 are ORD GI projects with completed publications (i.e., reports and

journal articles).  ORD intends to update this document as more information becomes available

when additional results are published.  Some of ORD research sites such as Cincinnati,

Cleveland, Detroit, Louisville, Edison, and Camden, are  still active.

       GI can be applied to new or retrofit instillations.  The U.S. is a demographically and

geographically diverse country, and as the map (Fig. 1) and the tables (Table 1 and 2)

demonstrate, EPA has just started to examine the performance and effectiveness of GI under all

the different demographic and geographic conditions throughout the U.S. Eventually, EPA

hopes to provide information useful to communities of all sizes (i.e., population and area) and in

all climatic regimes.
7 Kansas City Water Services Department (KCWSD). 2013. Final Report Kansas City Overflow Control Program
Middle Blue River Green Solutions http://www.burnsmcd.com/Resource_/PageResource/Overflow-Control-
Program-Assistance/Final-Report-Kansas-City-Overflow-Control-Program-Middle-Blue-River-Basin-Green-
Solutions-Pilot-Project-2013-ll.pdf
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Table 1. EPA has a number of community-based research efforts, each utilizing different GI
SCMs, and of various sizes, in an attempt to quantify changes to stormwater runoff due to GI.
Number of Individual SCMs Evaluated Per Location
Location
Edison, NJ
New York, NY
State College, PA
Clarksburg, MD9
Louisville, KY
Cincinnati, OH
Cleveland, OH10
Detroit, MI
Austin, TX
Kansas City, KS
Denver, CO
Dis-
connection





166


1


Rain
Gardens
2




82
12


78

Green
Roofs
I8
1
6







1
Bio-
Retention









51

Permeable
Pavement
3



14
2



2

Tree +
Infiltration
Planters




32






8 The Edison Roof was not a green roof but a conventional roof.  ORD characterized the water quality of the roof
runoff of a conventional roof for comparison to a possible future green roof.
9 Role of Urbanization
10 Demolished Building
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Table 2.  EPA has a number of community-based research efforts, each utilizing different GI
SCMs, and of various sizes, in attempt to quantify changes to water quality in stormwater runoff.
Water Quality Parameters Studied
Location
Edison, NJ8
New York, NY
State College, PA
Clarksburg, MD11
Louisville, KY
Cincinnati, OH
Cleveland, OH12
Detroit, MI
Austin, TX
Kansas City, KS
Denver, CO
Dis-
connection








Bacteria


Rain
Gardens
Nutrients




Nutrients
Metals,
PAHs,
Total
Suspended
Solids, E.
coli



Nutrients,
Metals,
Total
Suspended
Solids

Green
Roofs
Nutrients,
Metal
Nutrients
Nutrients







Nutrients
Bio-
retention









Nutrients,
Metals,
Total
Suspended
Solids

Permeable
Pavement
Chlorides,
Nutrients,
Metals,
Total
Suspended
Solids



Nutrients






Tree
Planters




Nutrients






11 Role of Urbanization
12 Vacant lots
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                                                                            w York, NY

                                                                           idison, NJ

                                                                         Clarksburgh, MD
                500      1000
                                       2000
                                      ^m Kilometers
       Figure 1. Map of EPA ORD green infrastructure research sites as of 2015.



Infiltration


       A major site-specific property of GI often is the ability to infiltrate water.  EPA's

National Stormwater Calculator uses the USDA's SSURGO Soil database13 to look up the

infiltration rates of soils but this database contains undisturbed soils. However, many urban soils

have been disturbed, altered, or relocated and most urban soils have been compacted which

reduces their ability to infiltrate water.  To understand how soil in urban systems perform when

used in GI implementation, each of the major soil orders in the continental U.S. and Puerto Rico

have been characterized. To date, EPA has systematically measured the infiltration rates and
13 http://www.ncgc.nrcs.usda.gov/products/
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characterized the soils in 12 cites (Portland, ME; Camden, NJ; Atlanta, GA; New Orleans, LA;

Detroit, MI; Cleveland, OH; Cincinnati, OH; Omaha, NE; Junction City, KS; Phoenix, AZ;

Tacoma, WA, and San Juan, PR). In addition to these cities, EPA has measured the urban soil

infiltration rates at many of their research sites, including Edison, Cincinnati, Louisville, and

Kansas City. ORD has studied GI sites located in densely urban, suburban, and more natural

sites.
                                    Soil Assessment Status
                                                                    ..
                     500
                                          Mumrto-a
       Figure 2. Twelve cities, representing each of the major soil orders, were sampled
       to characterize altered urban soils.
Hydrology

       Most of the GI research efforts studied the hydrology of specific types of low impact

development (LID) SCMs, such as green roofs or permeable pavement. Much of the data
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collected to date can be used to determine the maximum amount of rain specific SCMs can




completely infiltrate, and, conversely, what it cannot. Furthermore, these data can be used to




calibrate and validate the SWMM LID modules to help figure out when and where the models




work best and caveats to consider when using the models. The Cincinnati, Louisville, and




Kansas City GI research efforts have investigated the performance and effectiveness at a




watershed scale by examining the response of numerous LIDs rather than focusing on the




performance of one individual type of SCM.







Water Quality




       The Edison, Cincinnati, Louisville, and Kansas City research efforts investigated nutrient




effects but also metal and total suspended solids reductions through permeable pavement, rain




gardens, and bioretention SCMs.  Most of the GI water quality (WQ) data collected at




municipalities have significant variance in the inlet, outlet and percent removal event mean




concentrations. Statistical analyses of these data are often hampered by the fact that only a few




samples could be collected or where experimental  replication is not feasible or within budget.




The Edison data set has higher numbers of samples with statistically comparable values for




chloride, metals, and nutrient data.







Place-based




       Place-based field research requires a time commitment as collaborations are established,




baseline measurements are recorded, GI is installed,  and storm events are monitored. Given




adequate time, these studies can be used to quantify the performance and effectiveness  of GI and




used to improve models and help communities make decisions.  Working with municipalities




offers many opportunities for synergistic monitoring and advancement of GI implementation for







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EPA. However, there can be coordination challenges when construction schedules are delayed




and Federal contracts end.







       The field-based research efforts performed to date have been very insightful, but are just




beginning to examine all of the variation and diversity of stormwater management conditions in




the U.S. EPA is gaining a better understanding of the intricacies of stormwater management and




that there is not a one-size-fits-all  solution.







Guidance for stakeholders and decision makers





       GI research is a long-term, complicated, and expensive undertaking and EPA is working




intensely to understand better how the different types of GI perform under different




environmental settings and to provide a better estimate of expected results from its  use.




Stakeholders and decision makers need to understand that there are different levels of




performance and effectiveness that can be achieved from GI and that there are solutions that can




be implemented at multiple spatial scales and in multiple configurations. Ideally, EPA will




provide case studies as examples for communities of similar social, economic, demographic, and




geographic characteristics to help  them identify options for dealing with stormwater




management. Communities need  to recognize that GI provides a number of ecosystem services




that are not restricted solely to stormwater management and they should consider these as well




when deciding which GI SCMs to use.  Although many of the challenges and resulting solutions




are generalizable, each community deals with issues that may be unique to them and they must




use the best available information to address and resolve these issues.
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Future needs (i.e., new questions, where our knowledge is lacking, etc.)




       Although EPA is gaining a better understanding and appreciation of GI for stormwater




management, quite a few knowledge gaps need to be filled to provide information that is more




useful for communities. Because the U.S. is so diverse and the number of GI SCMs are great,




EPA needs to determine how repeatable the performance and effectiveness of certain practices




are in different climatic regimes. Specifically, much of the EPA GI research has been in the




eastern U.S., in wet (i.e., mesic) climates. EPA ORD has not examined arid or semi-arid regions




nor does EPA have an understanding of the benefits and drawbacks of infiltrating more




stormwater.  There could be water quality and water quantity effects and  these need better




understanding.  Ideally, EPA will provide models that have been fully validated and that clearly




express the strengths and weaknesses of different GI types, and where they work best so




communities can use the information to make sound decisions and better manage their systems.




This will require additional research in areas of the country that have largely been ignored. The




issue is further complicated by a changing climate and resulting nonstationarity (i.e., past climate




conditions are not  a predictor of future climate conditions) and EPA research  needs to help




communities prepare for an uncertain future.







Community Access/General Interest




       One of the  more problematic issues any new concept or practice faces is the evolution of




the terminology associated with it.  As the topic of watershed drainage and its connection to




stormwater management is increasingly discussed by  researchers and decision-makers alike,




new, multi-worded terms can muddle communication and slow development. Another area with




room for improvement lies in the lack of integration between urban design  and the developing




field of urban ecology. Traditionally, environmental consultants, who generally do not conduct





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scientific research, are providing outdated and non-site-specific information to city planners,




designers, and engineers. This leaves out important ecological-specific research an urban




ecologist could provide. Thirdly, there are many socio-economic and political barriers and




benefits to GI as an alternative to gray infrastructure-based stormwater management. These




papers address the complexities and opportunities regarding the increased interest and




implementation of GI systems as sustainable solutions to stormwater management.




       The scope of the papers listed in this section is conceptual and broad, meant to




encompass the challenges and potential opportunities of implementing any kind of GI into any




type of urban environment.  Case studies in Cleveland and Milwaukee are provided as examples




to help explain how stakeholders can overcome barriers to GI application. Questions of how to




translate new and often localized terminology for use in larger scale applications, and ways to




integrate urban ecological research directly into the planning process were also asked.




       As the topic of watershed drainage develops and evolves and GI becomes a more




standardized practice, it is important for end-users of this information to understand the




terminology and exactly what is being discussed.  The ecological implications of urban




development are also an important product of both urban and GI design and should involve




direct urban ecological research.  It is also essential to note that it is still possible for stakeholders




to see the value of GI, and to implement GI as a method of stormwater management, even in the




face of a combination of financial, administrative, political, and technical challenges.




       Due to a conscious effort to use GI as a tool for the mitigation of stormwater overflows,




communication, stakeholder involvement, and accuracy of ecological impact assessments are




integral to laying a promising foundation for the future of GI methods.
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Background Literature

Felson, A, M Pavao-Zuckerman, T Carter, F Montalto, W Shuster, N Springer, E Stander, and O
    Starry.  2013.  Mapping the design process for urban ecology researchers. Bioscience
    63(ll):854-864.
Fletcher, TD, WD Shuster, WF Hunt, R Ashley, D Butler, S Arthur, S Trowsdale, S Barraud, A
    Semadeni-Davies, J-L Bertrand-Krajewski, PS Mikkelsen, G Rivard, M Uhl, D Dagenais,
    and M Viklander. 2014. SUDS, LID, BMPs, WSUD and more - The evolution and
    application of terminology surrounding urban drainage.  Urban Water Journal: 1-18.
    http://dx.doi.org/10.1080/1573062X.2014.916314
Keeley, M, A Koburger, D Dolowitz, D Medearis, D Nickel, and WD Shuster. 2013.
    Perspectives on the use of green infrastructure for stormwater management in Cleveland and
    Milwaukee. Environmental Management 51:1093 -1108.
                                      Page 21 of 57

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Summaries of Specific Research Efforts and References


Region 2 - Edison, NJ

       The Edison Environmental Center (EEC) is a U.S. EPA facility in Edison, New Jersey.14

This site acts as a test bed for equipment and techniques before implementing them in field

settings where EPA has less control over the location. With ownership of the facility, EPA can

construct experimental GI SCMs to test different design features and include replication to

increase statistical power. There are four GI systems at EEC from which research results have

recently been published: permeable pavement systems, bioinfiltration areas, rain gardens, and

cisterns.

       In a retrofitted one-acre parking lot, EPA installed three common permeable pavement

types [permeable interlocking concrete pavement (PICP), pervious concrete (PC), and porous

asphalt (PA)] in  140-ft long head-to-head parking rows designed to receive run-on from the

upgradient impervious hot-mix asphalt driving lane.  A primary goal of this research was to

evaluate the effect that permeable pavement type had on the infiltrate water quality composition

and hydrologic response when all three were exposed to the same conditions and rainfall events.

       Eight journal articles and one EPA report have been produced on GI research conducted

at the Edison Environmental Center (EEC) with most publications describing results associated

with the permeable pavement systems. Hydrologic performance outputs have evaluated surface

infiltration capacity, surface clogging dynamics, and evaporation. Surface infiltration capacity

was statistically different by pavement type (PC - 4,800 cm/h; PICP - 2,100 cm/h; and PA - 150
14 This facility provides an added level of safety and control for research activities. There is no concern for
vandalism or theft, and areas can be blocked to conduct tests on pavement surfaces.


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cm/h), but each could sufficiently infiltrate runoff from the most extreme rainfall intensity if the




surface was not clogged.  Based on visual observations, surface clogging occurred as sediment




from the drainage area was transported with run-on onto the permeable pavement surface and




blocked the pore space.




       Embedded soil moisture sensors [time domain reflectometers (TDRs)] in the open-graded




aggregate below the permeable pavement surface documented this observation through remote




monitoring techniques.  A water balance of captured infiltrate from lined permeable pavement




sections was calculated, and it showed that evaporation from permeable pavement systems was




measurable, albeit small (about 5% on an annual basis), and that the PC surface had more




evaporation than the other two surfaces.




       Published water quality performance reports are limited to chloride, but results associated




with other sampled stressors are in press (nutrients and  pH) or under production (metals and




semi-volatile organic compounds). Chloride concentrations in  the infiltrate approached 10,000




mg/L for the rain event that immediately followed a snow event where de-icing salt was applied.




Chloride persisted in the infiltrate year round, and it remained above the chronic toxicity




threshold for freshwater aquatic life (230 mg/L) into April. A power regression with cumulative




rainfall since the previous storm event best described the chloride flush through the permeable




pavement system.




       A portion of impervious asphalt from this parking lot and the roof from an adjacent




building drain into six bioinfiltration areas that were constructed side-by-side with three different




ratios of drainage area to bioinfiltration surface area to test the  effect of size on hydrologic




performance. Embedded soil moisture sensors in the six bioinfiltration areas with three different




sizes demonstrated that infiltration was concentrated near the inlet.  These results, in









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combination with meteorological observations and plant size measurements, demonstrated that




shrubs closest to the inlet correlated with larger growth patterns than the shrubs farther from the




inlet primarily because the closer shrubs received substantially more runoff. Runoff provides a




source of water and nutrients and both are essential for plant growth.




       A set of eight mesocosm15 rain gardens were constructed with a partial factorial design to




test whether any of the four design treatments (size, presence of a carbon source layer, vegetation




type, and drainage configuration) influenced nitrogen fate in underdrain effluent.  Collected




stormwater runoff from a parking lot at the neighboring community college was used to simulate




two event sizes.  Lastly, a cistern was installed to provide water for cooling water tower usage




and other non-potable uses. The rain water capture and use research was not designed with




replication but was a research opportunity to monitor use from a system specifically installed to




address Section 438 of the Energy Independence and Security Act of 2007 (EISA) and the




presidential Executive Order (EO) (no. 13148, "Greening the Government through Leadership in




Environmental Management" issued 4/21/2000) to improve environmental performance.




       The eight mesocosm rain gardens illustrated that the presence of an internal water storage




zone significantly reduced combined nitrate and nitrite mass, but it significantly increased




ammonia quantity. Overall, there was no significant difference in total nitrogen quantity for the




presence or absence of an internal water storage zone, and the additional carbon source layer did




not have a significant effect on nitrogen removal.




       The use of collected roof runoff and condensate recovery led to a substantial reduction of




potable water used for cooling tower makeup water during the warmer months. There was an




average annual 8.3% decrease in potable water usage, in addition to measures to decrease potable
15 Four were 4255 L in volume and the other four were 2785 L.





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water usage previously instituted.  The primary source of contamination in roof runoff appears to




be atmospheric, as rainwater concentrations were correlated with most observed constituents in




the roof runoff. There were some building material components (i.e. copper gutters and




galvanized sheet metal), which contributed to the significantly larger observed copper and zinc




runoff concentrations, respectively.




       As guidance for stakeholders and decision makers, site-specific conditions will govern




maintenance frequency for permeable pavement systems.  The permeable pavement site at the




EEC, with a limited sediment supply, has been in operation for more than 5.5 years without




needing maintenance to alleviate surface clogging.  Surface clogging begins at the upgradient




edge (impervious surface/permeable pavement interface) and progresses downslope, so this




mechanism should be considered when selecting locations to manually test surface infiltration




rates for considering when maintenance is needed.  The surface of the PC has demonstrated




significant unraveling, however, this observation has not been included in a publication or report.




When bioinfiltration areas are oversized, it increases the likelihood that vegetation planted




farthest from the runoff source will experience water-deficit  stress, which could limit growth,




cause mortality, or necessitate additional maintenance (i.e., irrigation and fertilization), so




bioinfiltration design should consider plant placement and species selection relative to the




proximity of the runoff source.




       Future needs associated with this research include: (1) exploring the fate of stressors as




water percolates to groundwater, (2) evaluating fate of microorganisms in permeable pavement




systems, (3) determining an efficient method to identify where manual surface infiltration tests




should be conducted in order to evaluate maintenance needs, (4) finding more suitable uses for
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harvested rainwater, and (5) evaluating long-term water quality data from the permeable

pavement research site to determine if there are seasonal effects of changes with age.



References

Borst, M and RA Brown. 2014. Chloride released from three permeable pavement surfaces after
   winter salt application. Journal of the American Water Resources Association 50(1):29-41.
   http://onlinelibrary.wiley.com/doi/10.1111/jawr. 12132/full
Borst, M, AA Rowe, EK Stander, and TP O'Connor. 2010.  Surface Infiltration Rates of
   Permeable Surfaces: Six Month Update (November 2009 through April 2010). U.S.
   Environmental Protection Agency, Office of Research and Development, Cincinnati, Ohio,
   Report No. EPA/600/R-10/083.
   http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P1008CH4.txt
Brown, RA and M Borst. 2013. Assessment of clogging dynamics in permeable pavement
   systems with time domain reflectometers.  Journal of Environmental Engineering
   139(10): 1255-1265. http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EE. 1943-
   7870.0000734
Brown, RA and M Borst. 2014. Evaluation of surface infiltration testing procedures in
   permeable pavement systems.  Journal of Environmental Engineering 140(3):04014001.
   http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EE.1943-7870.0000808
Brown, RA and M Borst. 2015. Quantifying evaporation in a permeable pavement system.
   Hydrological Processes, (available online ahead of print).
   http://onlinelibrary.wiley.com/doi/10.1002/hyp.10359/full
Gilchrist, S, M Borst, and EK Stander. 2014.  Factorial study of rain garden design for nitrogen
   removal. Journal of Irrigation and Drainage Engineering 140(3):04013016.
   http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29IR.1943-4774.0000678
O'Connor, TP and M Amin.  2015. Rainwater collection and management from roofs at the
   Edison Environmental Center.  Journal of Sustainable Water in the Built Environment
   1(1):04014001. http://ascelibrary.org/doi/abs/10.1061/JSWBAY.0000792
Stander, EK, AA Rowe, M Borst, and TP O'Connor. 2013. Novel use of time domain
   reflectometry in infiltration-based low impact development practices. Journal of Irrigation
   and Drainage Engineering 139(8):625-634.
   http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29IR.1943-4774.0000595


Region 2 - New York, NY

       This Region 2 Regional Applied Research Effort culminated in an ORD final report on

the topic of green roofs (EPA 2014). This report documents the quantity and quality of runoff

from a suite of urban green roofs located in New York City (NYC). An overall research goal
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was to assess green roof performance on actual urban rooftops, which have lower and more




typical runoff dimensions to drains and are subject to more realistic urban environmental




conditions (i.e., light, wind and rain shadows), as opposed to test plots at academic research




campuses or laboratories. The urban green roofs were located throughout NYC representing




three of the five boroughs (The Bronx, Manhattan, and Queens). All of the areas monitored




drained to combined sewers, so reductions in roof runoff theoretically should help reduce CSO's.




      This report presents analysis of water benefits from an array of observed green and




control (non-vegetated) roofs throughout NYC.  Water quantity and water quality were measured




in the runoff of green and control roofs.  The sites were located  on a variety of buildings and




represent a diverse set of available extensive green roof installation types, including vegetated




mat, built up, and modular tray systems. Plant types on individual roofs were also different.




      This work confirms that deploying green roofs on existing buildings can reduce the




negative impacts of urban wet-weather flow (WWF), including water quality and water quality




impacts in an urban environment. Findings for water quantity performance demonstrate that the




modular tray system captured the lowest percentage of precipitation among all green roof




systems for storms 0-20 mm in depth but was the highest for storms above 30 mm. Multi-year




predictions indicated that on an annual basis, the built up system will retain the most rainfall,




then followed by the modular tray system, and then the vegetated mat systems. The Natural




Resources Conservation Service curve number (CN) method could not capture observed relative




differences between the retention performances of the built up, modular tray and mat systems in




different storm categories.  Individually, the vegetated mat systems had 62%  and 42% overall




rainfall retention respectively, whereas the built up system had 56% and tray  system 59%.  The
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estimated long term rainfall capture of the system was between 37-60% for vegetative mats, 49-




66% for built up, and 47-61% for trays.




       Water quality monitoring indicated that the green roofs neutralized the acid rain as the pH




of runoff from green roofs was consistently higher than that from the control roofs and




precipitation with observed average pH's equal to 7.28, 6.27, and 4.82 for the green roofs,




control roofs and precipitation, respectively.  In general, observed nitrate and ammonium




concentrations were lower in green runoff than in control roof runoff, with the exception of




runoff from the built up system, which had higher nitrate concentrations than the control roof




runoff. Overall, total P concentrations were higher in green roof runoff than control roof runoff.




Micronutrients and heavy metals were detected either at very low concentrations or not at all.




       While there appears to be more chemical constituents present in green roof runoff than




control roof runoff, there is an overall reduction in the volume of runoff from green roofs.  Thus,




the total mass of nutrient runoff from green roofs is less than that from  non-vegetated roofs.  As




a result, the water quality benefits of green roofs are favorable in urban environments. The




projected annual mass loading per unit rooftop area of nitrate, ammonium, and total phosphorous




discharging from all five green roofs was considerably less than that from their respective control




(non-green) roofs, due to the ability of green roofs to retain precipitation. Thus, green roof




implementation could improve urban stormwater and subsequently urban receiving water quality




if achieved at large areal scales. The green roofs of this study were all built on existing




structures, so results of this study could be used for further retrofitting of existing structures with




green roofs.




       The continued monitoring of the urban green roofs that were part of this effort (funded as




a Region 2 RARE award) will provide additional data needed to understand the evolving









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performance of urban green roofs with age, as well as the role of seasonality in green roof

hydrology.  Other recommendations for further study include undertaking relative cost-benefit

analysis of green roofs versus other stormwater management technologies, more research

experiments considering driving factors for water control such as substrate depth and water

holding capacity, and continued studies that will optimize design with respect to maintenance

and performance.



References

EPA. 2014. Culligan, P, T Carson, S Gaffin, R Gibson, R Hakimdavar, D Hsueh, N Hunter, D
   Marasco, W McGillis, and TP O'Connor.  2014. Evaluation of Green Roof Water Quantity
   and Quality Performance in an Urban Climate. U.S. Environmental Protection Agency,
   Office of Research and Development, Cincinnati, Ohio, Report No. EPA/600/R-14/180.


Region 3  - Clarksburg, MD

       This work is from the Clarksburg Monitoring Partnership, a collaborative research effort

in the Clarksburg Special Protection Area (CSPA) in Montgomery County, Maryland. This

effort is a partnership among the U.S. EPA; the U.S. Geological Survey, Eastern Geographic

Science Center (EGSC); and the Montgomery County Department of Environmental Protection

(DEP) along with other research partners.  This ongoing research is focused on the use of high-

resolution mapping of urban development using repeat acquisitions of digital orthoimagery and

Light Detection And Ranging (LiDAR) data, high resolution mapping of SCMs and Best

Management Practices (BMPs), streamflow and precipitation monitoring, and in-stream and in-

pipe biological and water quality assessments.16
16  EPA http://www.epa.gov/esd/land-sci/clarksburg01-05.htm.

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       This research is meant to evaluate the effectiveness of the County's Phase II BMPs

implemented as a part of the Chesapeake Bay Watershed Implementation Plan for the National

Pollutant Discharge Elimination System (NPDES) stormwater rules for municipalities with less

than 100,000 people.17 This research uses a Before-After-Control-Impact (BACI) study design

to evaluate BMP performance over time during the construction (sediment control) and post-

construction (stormwater control) phases of urban development.

       The CSPA is one of four Special Protection Areas in Montgomery County.  Clarksburg is

a rapidly developing area where the County is undergoing urbanization in a "town center"

pattern; concentrating development in a relatively small area of high density residences,

businesses, services, infrastructure, and amenities while maintaining intact riparian buffers,

agriculture, and forest patches to the greatest extent possible. The County uses adaptive

management; where lessons learned from one development are applied to later development

plans.

       The Phase II BMPs investigated in the research are a mixture of gray infrastructure18 and

Green BMP Treatment Trains and are found in areas of higher development density whereas GI

is more prevalent in areas of lower density development. Distributed BMPs are used to retain

and infiltrate stormwater runoff rather than centralized retention basins.

       In spite of the best efforts of the County, monitoring results in the first watershed

developed in the CSPA show a major impact from the development during the construction

phase.  Lessons learned to date include the need for greater sediment control and more rapid
http://www.mde.state.md.us/programs/Water/StormwaterManagementProgram/Pages/ProgramsAVaterPrograms/sed
imentandstormwater/storm_gen_permit.aspx.
18 http://water.epa. gov/infrastructure/greeninfrastructure/gi_what.cfm


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conversion of BMPs from construction phase to post-construction phase during the development

process. Future development plans also call for both reducing the intensity of development and

limiting development in headwater stream areas to try to protect water quality and stream biota

(see Annual Reports listed below). Future monitoring will reveal the extent to which water

quality and stream biota recover towards pre-construction levels in areas already built-out and

whether the adaptive management implementation of previous lessons learned will help to

mitigate the impacts of future development.  Our plans are to maintain the monitoring work long

enough to see changes that occur during long time scales.



References

Hogan, DM, ST Jarnagin, JV Loperfido,  and K Van Ness.  2014. Mitigating the Effects of
   Landscape Development on Streams in Urbanizing Watersheds. Journal of the American
   Water Resources Association (JAWRA) 50(1): 163-178. DOT:  10.1111/jawr. 12123 <
   http://onlinelibrary.wiley.com/doi/10.1111/jawr. 12123/full >
Jones, DK, ME Baker, AJ Miller, ST Jarnagin, and DM Hogan. 2014.  Tracking geomorphic
   signatures of watershed suburbanization with multitemporal LiDAR.  Geomorphology
   219:42-52. DOT:  10.1016/j.geomorph.2014.04.038.
Loperfido, JV, GB Noe, ST Jarnagin, and DM Hogan. 2014. Effects of distributed and
   centralized stormwater best management practices and land cover on urban stream hydrology
   at the catchment scale. Journal of Hydrology 519(C):2584-2595.  DOT:
   http://dx.doi.org/10.1016/jjhydrol.2014.07.007.
Montgomery County Special Protection Area Annual Reports:
   http://www.montgomerycountymd.gov/dep/water/special-protecti on-areas.html#reports.


Region 3 - State College, PA

       This Region 3 RARE research culminated in an ORD final report on the topic of green

roofs (Berghage et al. 2009).  The work for this research was carried out by the Penn State Green

Roof Center of The Pennsylvania State University at University Park, PA. Specifically, this

research investigated the design specifications and materials of green roofs used as stormwater

control devices.  This research was meant to gather field performance data from side-by-side


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structures to provide performance data for stormwater control by green roofs for both water




quantity and quality. Six small-scale buildings were tested in agricultural fields which allowed




for unobstructed wet weather data collection. Additionally this research explored




evapotranspiration (ET), drought limitations, and long term maintenance needs due to exposure




to acid rain. For these additional studies, controlled test bed systems were located in the Penn




State Horticultural Science greenhouses while additional testing of media acidification was




conducted in the laboratory.




       The experimental design used small-scale buildings exposed to the local weather in an




attempt to gather data of variance for effects of different roof type and to determine whether




statistically significant differences could be described for any given rain event. Key parameters




monitored included real time flow and grab sample pollution assessment.  The grab samples




were analyzed for conductivity, turbidity, pH, nutrients, and trace metals.  In a controlled




environment (i.e., greenhouse test bed systems),  weighing lysimeter studies were conducted to




obtain background information and to demonstrate the differences in water storage, and retention




and detention characteristics of the media, with and without the presence of plants, and drought




studies. The laboratory study used accelerated aging to determine the effects of acid rain on the




length of life for the roofs.




       Collected field data indicated that a 3.5 - 4 inch deep green roof can retain 50%  or more




of the annual precipitation in the Northeast.  Replicated data from this study provided estimates




of expected differences in performance from identical green roofs. Green roof runoff reduction




was consistent during the warm summer months (almost no runoff) but was variable during




winter months when runoff from  the buildings varied in some storm events from 80% for one
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building to 100% for others.  Flow rates were reduced in runoff from green roofs until the




systems were saturated at which point runoff flow roughly equaled the rate of precipitation input.




       Establishment of plants on Green roofs (first year only) in Region 3 may require




supplemental irrigation.  Plants increase the transport of moisture through the soil medium when




compared to unplanted medium.  This finding will need to be incorporated into green roof




modeling. Pennman-Monteith ET prediction equations can describe water loss from planted




green roofs.




       Field water quality data (e.g., pH, conductivity, color, and nitrate) from green versus non-




green roofs were measured and compared statistically. Results demonstrated that green roofs




may reduce certain pollutants (e.g., acid precipitation and nitrate), but that it may increase




loadings directly related to these planted systems (e.g., phosphorous, potassium, calcium, and




magnesium).  The laboratory test of the pH buffering capacity of the planting media suggest that




the green roof media can buffer acid precipitation for approximately 10 to  15 years, after which




it may be necessary to amend the media with lime to maintain the pH buffering capacity.




       Green roofs can be incorporated with other GI SCMs and should be included in a




municipal stormwater plan. For suburban or agricultural areas, additional green roof runoff




treatment may be as simple as directing the downspouts to grass-covered areas (vegetated filter




strips or swales) or collecting green roof runoff in rain barrels to be used for irrigation, but this




may not be practical for urban areas where there is limited room for stormwater controls. For




urban areas that have combined sewers, green roofs  should be viewed as a benefit due to the




volume reduction to the combined system and the delay in time to peak.




       Directly discharging green roof runoff to a receiving water is not recommended due to




the increased levels of phosphorous, potassium, calcium, and magnesium.  Due to variability in









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results, a conclusion from this study was that continued sample collection and analysis is

warranted.  Further testing of materials used for green roof construction and planting should be

conducted to determine loadings coming from roofs as well as other constituents from

atmospheric deposition and building materials for standard roofing. Modeling loadings for green

roofs for watershed management requires additional monitoring with full-scale roofs or multiple

roofs in an urban setting.  The drought studies indicated some potential limitations without the

use of irrigation.

       Green roofs need to be tested in other climates so that further design specifications on

plant mixtures, media depth and amendments, and potential irrigation requirements can be

determined. Other climatic conditions should also include year-to-year or long-term studies, as it

seems very likely that in dry years the green roof runoff would be far less than in wet years.

Additional weighing lysimeter studies should be conducted to identify more plant species

suitable for green roofs, especially varieties that are drought resistant and require minimal

nutrient supplements.  The effects of green roof runoff discharge on receiving waters or the

potential for additional treatment of green roof discharge were not addressed, and these should

be addressed in future studies.



References

Berghage, RD, D Beattie, AR Jarrett, C Thuring, F Razaei, and TP O'Connor. 2009. Green
    Roofs for Stormwater Runoff Control. U.S. Environmental Protection Agency, Office of
    Research and Development, Cincinnati, Ohio, Report No. EPA/600/R-09/026, February
    2009.  http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P1003704.txt
                                      Page 34 of 57

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Region 4 - Louisville, KY




       The Louisville and Jefferson County Metropolitan Sewer District (MSD) entered into a




consent decree with U.S. EPA, U.S. Department of Justice, and Kentucky Department for




Environmental Protection to limit CSOs. In one of the combined sewer systems, CSO Basin




#130, a GI approach was determined to be more cost-effective than the gray alternative to meet




the CSO targets outlined in MSD's long term control plan. EPA-ORD entered into a




Cooperative Research and Development Agreement (CRADA) with URS Corporation and MSD




to monitor and evaluate the individual performance and collective effectiveness of GI practices




installed in this basin. The basin is 17 acres of mixed residential and commercial areas in the




Butchertown section of Louisville, Kentucky, and the design included: 14 permeable pavement




systems, 28 tree boxes, and 4 infiltration planters installed along the public right-of-way.




       During the design and planning stages, the municipality (MSD) hoped the monitoring and




research program could address: (1) how often maintenance is needed for the permeable




pavement  surfaces, (2) the lifetime of the system before complete replacement is needed, (3) if




implemented at other locations across the city, should the GI design or placement strategy




change to improve performance, and (4) if the design meets the CSO frequency and volume




reduction targets. These concerns are shared by many communities, so our research attempted to




address these knowledge gaps.




       To address the first three concerns, a series of embedded sensors  (soil moisture, water




level, temperature) within the SCMs to study the infiltration and exfiltration dynamics of the




system and evaluate how they changed with age. Most of the GI practices were not installed




until 2013, so the fourth concern is  still under investigation.
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       Based on monitoring results from the first two permeable pavement strips that were




installed in December 2011, three journal articles have been published to date.  One article




highlights how installing soil moisture sensors [time domain reflectometers (TDR)] in the open-




graded aggregate below the pavers can be used to monitor remotely the progression of surface




clogging.  This installation proved to be a useful monitoring technique to address the question




about maintenance frequency. The second article highlighted the results from multiple pressure




transducers installed in wells along the length of the system. Analyzing the rates at which water




accumulated and drained provided insight on how infiltration and exfiltration processes changed




with time. With respect to the exfiltration rate, there was a significant reduction after the first




few events and through the first thirteen months.  The decrease was attributed to fine sediment




on the double-washed aggregate.




       Attempts to model the hydrologic performance of this system in EPA SWMM using the




measured water levels to calibrate the model were made, but this task demonstrated that the




treatment of exfiltration by this model did not accurately represent  exfiltration processes for a




long, narrow, and deep geometry. Exfiltration was treated as a constant flux on the bottom area




only, which is a similar method as in other common hydraulic models.  In this system, the water




drawdown rate decreased considerably with less water because the  hydraulic head and exposed




sidewall area were smaller. Alternate ways to model the lateral exfiltration processes were




pursued, and a unit process model was developed and reported in the third paper to include and




quantify lateral exfiltration. The unit process model also included a function to represent




changes in surface infiltration through clogging based on the results from the embedded sensors




that measured the progression of surface clogging.
                                      Page 36 of 57

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       As a result of this research, guidance for stakeholders and decision makers can be




provided for permeable pavement placement, remote monitoring strategies to predict




maintenance needs, construction materials that have a negative effect on performance, and the




benefits of a specific system geometry.  Surface clogging is accelerated when sediment and




organic material are present in the drainage area, so in an effort to limit the maintenance




frequency, permeable pavement systems should not be sited in areas with unstable drainage areas




and surrounding deciduous vegetation.  Soil moisture sensors (TDRs) installed in the open-




graded aggregate of storage gallery proved to be an effective remote monitoring technique to




determine maintenance needs.  The fine particle size  material (a.k.a., fines) present in double-




washed aggregate (about 2% by mass) resulted  in significant reductions in exfiltration rate




during the first 13 months of monitoring. While this is clean by industry standards, the demand




for these applications is not large enough to reduce the fines percentage, so a reduction in




vertical exfiltration capacity should be considered in  systems with deep aggregate layers. Even




though the subsoil at the first two monitored sites was clayey and the average infiltration rates




were 0.08 and 0.38 cm/h, the storage gallery and trench nearly drained completely during the




time between typical events because of the specific geometry of the system - long, narrow and




deep.  In this type of geometry, most of the exfiltration was determined to be lateral through the




exposed sidewalls.




       Future needs associated with this research topic are to: (1) explore lateral exfiltration in




more depth, (2) evaluate the collective effects of GI on sewer flow rates on a larger scale, (3)




evaluate whether the decrease in exfiltration rate continues with time and whether it is




hydrologically meaningful, and (4) investigate the interaction of the exfiltrating water with




existing groundwater.









                                      Page  37 of 57

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References

Brown, RA and M Borst. 2013.  Assessment of clogging dynamics in permeable pavement
   systems with time domain reflectometers. Journal of Environmental Engineering,
   139(10): 1255-1265. http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EE.1943-
   7870.0000734
Brown, RA and M Borst. 2015.  Evaluation of surface and subsurface processes in permeable
   pavement infiltration trenches. Journal ofHydrologic Engineering 20(2):04014041.
   http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29HE.1943-5584.0001016
Lee, JG, M Borst, RA Brown, L Rossman, and MA Simon. 2015. Modeling the hydrologic
   processes of a permeable pavement system. Journal ofHydrologic Engineering, (Just
   Released), 04014070. http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29HE. 1943-
   5584.0001088
Region 5 - Cincinnati, OH

       Consent decree settlements for violations of the Clean Water Act increasingly include

provisions for redress of combined sewer overflow activity through hybrid approaches that

incorporate the best of both gray (e.g., high-rate treatment plants, storage tunnels) and green

techniques (e.g., plant-soil systems like rain gardens, green roofs, pervious pavement systems).

Research was undertaken to help determine the most cost-effective, least-invasive method for

introducing GI into local communities where stormwater management is an issue. One six-year

study assessed the potential impact of distributed GI placed on a number of residential lots

within the same watershed. Various water quality and stream biota measurements were taken

three years before and three years after the GI technologies were applied, and the results were

compared to see if stormwater management at the parcel level can provide effective mitigation of

combined sewer overflows. The resulting papers focus on the economic, social, and

environmental factors surrounding the implementation of GI at the residential parcel level as a

tool for stormwater management.

       Many of these studies were conducted within the Shepherd Creek Watershed of

Cincinnati, Ohio.  The central motivating question was whether stormwater management at the


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parcel level is an effective strategy in mitigating sewer overflows and promoting stream health.




Researchers gauged the willingness of the community to participate in a GI installation program-




namely a reverse auction for the planting of rain gardens and the introduction of rain barrels on




residents' properties. The Shepherd Creek study found that the GI implemented in this




watershed did contribute to ecosystem services such as flood protection, water supply, and




increased water infiltration.  It also provided benefits to the local residents, and reduced the need




for larger, more expensive centralized retrofits.




       If this strategy is found to be a viable way to manage stormwater runoff and a similar




program attempted elsewhere, it may be beneficial to note a few key factors.  First, while there




was indication that education alone may be enough to motivate residents to install  GI, research




determined an auction promoted more participation than education alone, and at a  cheaper per




unit control cost than a flat stormwater control payment plan.  Second, a relatively small




monetary incentive can successfully entice homeowners to accept stormwater management




technologies on their property. Third, as participants share their experiences, neighbors may




become more willing to trust parcel-level stormwater management programs such  as the one




conducted in Shepherd Creek.




       The majority of GI research in Cincinnati evaluated infiltration-based stormwater




management strategies, but researchers  also studied the distribution of urban trees  and associated




impacts on stormwater runoff. Trees complement infiltrating GI by intercepting incoming




rainfall and preventing it from contributing to stormwater runoff. Researchers found that public




trees in the Cincinnati area provide substantial stormwater benefits, but these benefits vary




significantly according to community forestry practices at the municipal level. Proactive
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management of public trees can override other drivers of unequal tree distribution within cities

such as race or income.

       In general, management of environmental systems is complicated by uncertainty in the

constituent factors and processes that comprise an ecosystem. Regardless of the scale of

investment in environmental management, uncertainty remains. Uncertainties in the efficacy of

GI for CSO control arise from non-linearity in fluxes among the different parts of the hydrologic

cycle and spatial and temporal thresholds in potential ecological response. These studies point to

the need for further research to identify the minimum effect thresholds and restoration

trajectories for retrofitting catchments to improve the health of stream ecosystems.



References

Berland, A and ME Hopton. 2014.  Comparing street tree assemblages and associated
   stormwater benefits among communities in metropolitan Cincinnati, Ohio, USA.  Urban
   Forestry & Urban Greening 13:734-741. doi: http://dx.doi.Org/10.1016/j.ufug.2014.06.004.
Berland, A, K Schwarz, DL Herrmann, and ME Hopton.  2015. How environmental justice
   patterns are shaped by place: Terrain and tree canopy in Cincinnati, Ohio, USA. Cities and
   the Environment (GATE) 8(1): Article 1.
Kertesz, R, O Odom Green, and WD Shuster.  2014. Modeling the hydrologic and economic
   efficacy of stormwater utility credit programs for U.S. single family residences.  Water
   Science & Technology 70.11:1746-1754. doi:10.2166/wst.2014.255.
Mayer, AL, WD Shuster, JJ Beaulieu, ME Hopton, LK Rhea, AH Roy, and HW Thurston. 2012.
   Building green infrastructure via citizen participation - a six-year study in the  Shepherd
   Creek (Ohio, USA).  Environmental Practice 14:57-67.
Odom Green, O, WD Shuster, LK Rhea, AS Garmestani, and HW Thurston. 2012.
   Identification and induction of human, social, and cultural capitals through an experimental
   approach to stormwater management. Sustainability 4(8): 1669-1682.
   DOI:10.3390/su4081669.
Roy, A, L Rhea,  A Mayer,  W Shuster, J Beaulieu, M Hopton, M Morrison, and  A St. Amand.
   2014. How much is  enough? Minimal responses of water quality and  stream biota to partial
   retrofit  stormwater management in a suburban neighborhood. PLoS One 9(l):e85011.
Roy AH and WD Shuster.  2009.  Assessing impervious surface connectivity and  applications for
   watershed management. Journal of the American Water Resources Association 45(1): 198-
   209.
Shuster, WD, R Gehring, and J Gerken.  2007.  Prospects for enhanced groundwater recharge via
   infiltration of urban stormwater runoff- a case study. Soil Water Conservation 62:129-137.


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Shuster, WD, D Lye, A De La Cruz, LK Rhea, K O'Connell, and A Kelty. 2013. Assessment of
   residential rain barrel water quality and use in Cincinnati, OH. Journal of the American
   Water Resources Association 49:753-765. DOT: 10.1111/jawr. 12036.
Shuster, WD and L Rhea. 2013. Catchment-scale hydrologic implications of parcel-level
   stormwater management (Ohio USA). Journal of Hydrology 485:177-187.
   http://dx.doi.org/10.1016/jjhydrol.2012.10.043
Thurston, HW, MA Taylor, WD Shuster, AH Roy, and M Morrison. 2010. Using a Reverse
   Auction to Promote Household Level Stormwater Control.  Environmental Science Policy
   13:405-414.
Region 5 - Cleveland, OH

       Each of these papers address one or several dimensions of the role of GI in sustainable

urban stormwater management. Current consent decree settlements for violations of the Clean

Water Act increasingly include provisions for redress of combined sewer overflow activity

through hybrid approaches that incorporate both gray (high-rate treatment plants, storage tunnels,

etc.) and green techniques (plant-soil systems like rain gardens, green roofs, pervious pavement

systems, etc.).  The overall questions that addressed are: 1) can GI be integrated into an urban

setting, 2) how to design, monitor, and maintain the GI, and 3) can GI performance for

stormwater management, and ecosystem services provided be assessed?

       Through 2017, the GI retrofit of a neighborhood in Cleveland, Ohio (Slavic Village

Community Development Corporation area) will be studied.  Ongoing hydrological and

ecological monitoring provides feedback on the impact of GI implementation.  This work centers

on managing the urban landscape for water conservation and storage, developing a role for

community engagement and renewal, and moving forward a comprehensive management

strategy for the stabilization and restoration of urban ecosystems. One important aspect of this

work is that it is conducted in an environmental justice community. Attempts to account for

these unique social and economic factors into the GI implementation process to achieve overall



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integration with environmental management will be made. To this end, the research is dependent

upon collaboration with the Cleveland Botanical Garden, Slavic Village Development

Corporation, Northeast Ohio Regional Sewer District, the City of Cleveland, Region 5, and Ohio

State University.

       It is possible to develop effective integrated green approaches at the site scale to improve

the integrity of local hydrologic cycles, reduce runoff that reaches the sewer system, and reduce

risk of combined or septic sewer overflows.  The specific management approach includes rain

gardens and using specific landscape hydrologic measurements (made in 2010, 2011 by ORD) to

determine the utility of vacant lots to act as passive GI.  These data can be used to prescribe

management for these lots at a level which will make them both cost effective and provide

detention for stormwater abatement.

       In general, management of environmental systems is complicated by uncertainty in the

constituent factors and processes that  comprise an ecosystem.  Regardless of the scale of

investment in environmental management, uncertainty remains. Uncertainties in the efficacy of

GI for CSO control arise from non-linearity in fluxes among the different parts of the hydrologic

cycle and spatial and temporal thresholds in potential ecological response.  Further, rapidly-

changing social dynamics of a diverse, post-industrial urban setting under financial austerity

contribute political and social uncertainty. Adaptive management provides a framework that

explicitly accounts for these sources of uncertainty, and a recent paper (Shuster and Garmestani

2015) details our collaborative efforts to date in Cleveland, Ohio.



References

Jacobs, S, B Dyson, W Shuster, and T Stockton.  2013.  A structured decision approach for
   integrating and analyzing community perspectives in re-use planning of vacant properties in


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   Cleveland, Ohio.  Cities and the Environment 6( 1): 11.
   http://digitalcommons.lmu.edu/cate/vol6/issl/ll
Rhea, LK, WD Shuster, R Losco, and J Shaffer.  2014. Data proxies for assessment of urban soil
   suitability to support green infrastructure. Journal of Soil and Water Conservation,
   69(3):254-265. doi:  10.2489/jswc.69.3.254
Shuster, WD, A Barkasi, P Clark, S Dadio, P Drohan, B Furio, T Gerber, T Houser, A Kelty, R
   Losco, K Reinbold,  J Shaffer, J Wander, and M Wigington. 2011.  Moving beyond the
   udorthent - a proposed protocol for surveying urban soils to service data needs for
   contemporary urban ecosystem management. Soil Survey Horizons 52:1-8.
Shuster, WD, C Burkman, J Grosshans, S Dadio, and RJ Losco. 2014.  Green residential
   demolitions: Case study of vacant land reuse in storm water management in Cleveland.
   Journal of Construction Engineering and Management 141(3):06014011.
   10.1061/(ASCE)CO. 1943-7862.0000890
Shuster, WD, S Dadio, P Drohan, R Losco, and J Shaffer.  2014. Residential demolition and its
   impact on vacant lot hydrology: Implications for the management of stormwater and sewer
   system overflows. Landscape and Urban Planning. 25:48-56. DOI:
   10.1016/j.landurbplan.2014.02.003
Shuster, WD and AS Garmestani.  2014. Adaptive exchange of capitals in urban water resources
   management - an approach to sustainability? Clean Technologies and Environmental Policy
   DOI 10.1007/sl0098-014-0886-5.
Shuster, WD, MA Morrison, and R Webb.  2008. Front-loading urban stormwater management
   for success - a perspective incorporating studies of retrofit low-impact development. Cities
   and the Environment 1 (2): 8.
Shuster, WD, B Newport, B Furio,  N Cantello and S. Ellis. 2011.  APPENDIX 3, To Consent
   Decree, United States and State of Ohio v. Northeast Ohio Regional Sewer District (N.D.
   Ohio), Green Infrastructure Requirements.
Shuster, WD, B Newport, B Furio,  M Klingenstein, N Cantello, and S Ellis.  2011. APPENDIX
   4, To Consent Decree, United States and State of Ohio v. Northeast Ohio Regional Sewer
   District (N.D. Ohio), Requirements Applicable to Proposals for Green for Gray Substitutions.
Shuster, W.D. and A.S.  Garmestani. 2015. Adaptive exchange of capitals in urban water
   resources management - an approach to sustainability? Clean Technologies and
   Environmental Policy  17: 1393-1400.
USEPA.  2013.  On the  Road to Reuse: Residential Demolition Bid Specification Development
   Tool. EPA 560K13002, September. 81pp. http://www2.epa.gov/large-scale-residential-
   demolition/road-reuse-residential-demolition-bid-specification-development
Region 5 - Detroit, MI

       Although the importance of urban soil interpretation has been recognized for many years,

anthropogenic soils have been delineated as simply urban- or made-land on most soil survey

maps.  There is a significant lack of information regarding the composition of these soils and



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how they have been altered over time. It is important to gain better understanding of these soils

so that currently unused spaces like vacant lots can be revitalized and used as natural resources

for urban agriculture, GI, etc.  The paper referenced in this section argues that anthropogenic

soils found on vacant urban land can be mapped, even at the scale of a single lot.

       The soil survey took place on a <0.1 ha vacant lot in Detroit, Michigan.  The lot was

formed circa 1998 by the demolition of a wood-frame home from the 1920s in an urban

residential setting.  The research set out to conclude whether or not there is a mappable pattern of

anthropogenic polypedons19 against the alternative that the distribution is random, as well as

provide an answer to the possibility of piecing together the history of urban soils and reclaiming

them to suit current stormwater management needs.  The type of GI used would be determined

once the composition and content of the soil was known.

       The results suggest that anthropogenic soils on vacant urban land are mappable, even at

the scale of a single vacant lot. The soils approximated an anthrosequence, a related group of

profiles whose characteristics differ mainly because of anthropogenic activity.  This

anthrosequence can be used to characterize the map unit composition of native soil-urban land

complexes found on vacant property produced by building demolition.  However,  a more

complete picture of urban soils via Order 1 surveys would help define the characteristics of

anthrosequences in other urban settings and inform decisions regarding the implementation of
19 polypedon - Two or more contiguous pedons, which are all within the defined limits of a single soil series.
pedon - A three-dimensional sampling unit of soil, with depth to the parent material and lateral dimensions great
enough to allow the study of all horizon shapes and intergrades below the surface.
soil series - The basic unit of soil mapping and classification, comprising soils all of which have similar profile
characteristics and developed from the same parent material.
All above definitions from Micahel Allaby. A Dictionary of Ecology. 2004. Encyclopedia.com.
http://www.encyclopedia.com.
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GI, or other revitalization projects, allowing a city and its community members to reclaim

unused vacant lots and give them a purpose.



References

Howard J and Shuster WD. 2015. Experimental Order 1 Soil Survey of Vacant Urban Land,
    Detroit, Michigan. Catena 126:220-230. http://dx.doi.Org/10.1016/j.catena.2014.ll.019



Region 6 - Austin, TX

       Water scarcity is being felt in parts of Region 6 due to the historic drought conditions and

an increasing population. Alternative water sources, such as harvested rainwater, are becoming

more important and Region 6 has seen an increase in the number of potable rainwater harvesters.

There is also growing interest in the U.S. regarding rainwater harvesting systems (RWH) that

incorporate minimal treatment. Treatment can be expensive, and both residential and

commercial rainwater harvesters might be interested in minimal-treatment systems because of

the associated savings.  Many rainwater harvesters also wish to avoid the use of chemicals, such

as chlorine, that add off-flavors or odors to the water. EPA will require data about (1) risks

associated with using untreated or minimally treated rainwater produced commercially or

residentially,  and (2) risks will depend upon exposures occurring during the ultimate use of the

rainwater such as irrigation, drinking, or other indoor household usage (e.g., laundry, bathing).

       It is commonly thought that microbiological quality of harvested rainwater poses a

greater potential human health hazard as compared to the physical/chemical quality.  The

objectives of this study were to:  1) identify the composition of the microbial community in

untreated or minimally treated harvested rainwater and 2) quantify the impact of typical

residential treatment (e.g., filtration and disinfection) on  the microbial community.



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       Six residential RWH systems, located in close proximity to one another (within a 1-km




radius) in the central Texas area, were selected for this study. Site 1 performed batch-




chlorination in the cistern, sites 2-5 used ultraviolet (UV) light,  and site 6 had no disinfection.




Sites 1-5 used their treated rainwater for potable (e.g., drinking) and non-potable uses (e.g.,




laundry), and site 6 used the water only for non-potable purposes. All the UV sites (sites 2-5)




had either roof-wash filters (which are placed between the gutters and the first cistern such that




collected water is filtered before entering the cistern) or recirculating filters (which are  sand




filters through which the cistern water is occasionally passed).  In particular, site 5 operated its




recirculating filter once per day. Four sites had first-flush diverters, which divert a fraction of




the initial rainfall to a separate system (e.g., pipe or bath) because the first-flush tends to have




higher contaminant concentrations as compared to subsequent volumes of harvested rainwater.




Each of the tested systems had two filters between the cistern and tap, but the nominal pore size




varied.




       RWH systems that are located geographically  close to one another will not necessarily




have similar water qualities in their cisterns. Neither will those systems necessarily yield similar




treated water quality, even if they have similar treatment processes in place.




       Although Escherichia coli and Eenterococci generally are preferable to total coliform




(TC) as indicator bacteria in environmental applications, none of these appears to be a proper




indicator for the microbiological quality of harvested rainwater. TC, E. coli, and Enterococci




were often absent from the treated rainwater, even though substantial concentrations of the




potential human pathogens Legionellapneumophila, Myobacterium avium, M. intmcellulare,




Aspergillusflavus, A.fumigatus, or A. niger were present.
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       The observed log-removals of HPC, L. pneumophila, M. avium, M. intracellulare, A.

flavus, A.fiimigatus, and A. niger by filtration and UV disinfection were less than expected based

on previous laboratory studies. A careful study of the performance of commercially available

UV lamps for residential-scale disinfection is needed. Operators of individual, residential RWH

systems might require additional operation and maintenance training to achieve reliable

treatment of rainwater, such that the quality is similar to that of community water systems.

       Federal water quality regulations do not exist for potable RWH systems at individual

residences in the U.S. Consumers  of harvested rainwater might incur health risks by indoor

domestic use of harvested rainwaters, if those waters are not suitably treated.  For individual

residences, disinfection with ultraviolet (UV) light is the most common disinfection strategy

(70%), while chlorination is used in a smaller number of systems (8%). With respect to

filtration,  most of the potable RWH systems surveyed used cartridge filters (48%) or activated

carbon filters (39%). However, the treatment efficacy of individual RWH systems is not well

documented, especially for the removal of potential human pathogens, such asL.pneumophila.,

Mycobacteria spp., and Aspergillus spp., and more research is needed in these areas.



References

Lye, D. (submitted). Harvested rainwater quality before and after treatment in six full-scale
   residential systems.  PLoS One.



Region 7 - Kansas City, MO

       In 2010, Kansas  City, MO (KCMO) signed a consent decree with EPA on CSO. The

City decided to use adaptive management in order to extensively utilize GI in lieu of, and in

addition to, gray structural controls. KCMO installed 130 GI SCMs—primarily bioretention


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units—in a hundred acre-pilot; one of the largest retrofitted areas in the U.S. in 2012.  EPA's




Office of Research and Development (ORD) partnered with KCMO to conduct extensive




monitoring to quantify the performance of the pilot area.  The study focused on the long-term




monitoring efforts to quantify GI performance at two scales: site scale (individual SCMs) and




pilot (100 acre) scale.




       Site-scale elements of the GI research included stormwater monitoring systems at eight




individual SCMs (rain gardens, bioretention cells, and smart drains) in the pilot area. Parameters




measured by deployed monitoring systems included inflow, infiltrated volume, bypassed flow,




and drawdown times. In addition, a subset of SCMs is being monitored for water quality




(loading reduction) parameters including particle size, bacteria, nutrients, and metals.  EPA also




collected sewershed flow data before and after GI installation,  and performed evaluations of land




use, soil infiltration, drainage areas, and individual bioretention unit performance.  The titles of




the comprehensive reports written on this study are listed in the references.




       This work was performed in the Marlborough neighborhood along the Middle Blue River




in Kansas City, MO. This historically African-American community was established in 1945.




The neighborhood requested that the streets be lined with curbs and gutters to prevent standing




water that had traditionally been present after heavy rains. KCWSD installed the curbs and




gutters as well as relined the aging sewer system.  Both of these actions resulted in higher sewer




flow than before the research started. KCWSD installed 67 rain gardens, 5 bioretention cells, 2




cascades, 1 bioswale, 11 curb extensions with rain gardens, 24 curb extensions with below grade




storage, 19 bioretention with below grade storage,  1 gravel  parking space, 4300 linear feet of




porous concrete, 1100 linear feet of pervious paver sidewalk, and 90 pervious




sidewalk/infiltration galleries.  In addition to the GI installed, KCWSD  installed larger









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underground pipes with an additional storage volume of 288,000 gallons which is directly




connected to the sewer system.




       However, in spite of system upgrades which resulted in higher sewerflow, ORD




measured a 32% decrease in sewerflow before versus after GI installation which is consistent




with the SWMM model results presented by KCWSD.  KCWSD predicted that the peak flow




would reduce by 76%. ORD is interested in seeing the resultant drop in CSO.  While these data




are extremely variable, water quality analyses showed around a 50% reduction in all measureable




parameters TSS, SSC, turbidity, nitrate, and phosphate.




       This was a challenging effort. There were numerous entities involved in the research:




EPA ORD, EPA Region 7, Kansas City Water Services Division, EPA Contractors Tetra Tech,




University of Missouri-Kansas City, University of Alabama-Tuscaloosa, KCWSD Contractor




Burns and McDonald, KCWSD Contractor URS, Corporation, KCWSD's GI Designer. The




research started in 2008 and ORD finished collecting data in 2013.  The design portion of the




research effort was two years longer than anticipated and there was a drought in 2012, right after




the GI was installed resulting in another year for measurement. Many of the original EPA ORD,




EPA Region 7, KCWSD, and contractors who started the research retired before its conclusion.




This was a field scale effort which experienced many problems typical for a practical




application:




1.  Originally, it was intended to compare the 100-acre GI pilot to an 87-acre control area under




the same rain fall conditions. There were many problems with the measurement of sewerflow in




the control area and it was not possible to get useable results.  The analyses presented in this




report were based on before  and after results for the pilot area.
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2.  Before GI was installed, KCWSD relined the sewers in the pilot areas which resulted in an

increase sewerflow, which was not expected.

3.  The pilot area Marlborough neighborhood requested that KCWSD install curbs and gutters to

prevent standing water from remaining on homeowner's lawns. The installed curbs and gutters

directed more stormwater into the sewers than before the GI was installed.

4.  Once all GI was installed in 2012, Kansas City suffered a drought. ORD extended the

research period for another year beyond its original intention.

5.  The water quality sampling equipment from one of the five individual BMPs selected for

analysis was accidently destroyed by the solid waste collection system.

       The soil infiltration was much higher than expected and the BMPs worked extremely

well.  The fact that BMPs had little overflow resulted in a smaller than anticipated dataset to

analyze water quality.  However, in spite of system upgrades which resulted in higher sewerflow,

ORD measured a 32% decrease in sewerflow before versus after GI installation which is

consistent with the SWMM model results presented by KCWSD.  KCWSD predicted that the

peak flow would reduce by 76%.  ORD is interested in seeing the resultant drop in CSOs.



References

EPA. 2011. Report on Enhanced Framework (SUSTAIN) and Field Applications for Placement
   of BMPs in Urban Watersheds. U.S. Environmental Protection Agency, Washington, DC,
   EPA 600/R-l 1/144, November.  http://nepis.epa.gov/Adobe/PDF/P100DEWI.pdf.
EPA. 2015.  Kansas City Middle Blue River Green Infrastructure Pilot Proj ect Summary Report. In EPA
       Review.
Kansas City Water Services Department (KCWSD). 2013. Final Report Kansas City Overflow
   Control Program Middle Blue River Green Solutions
   http://www.burnsmcd.com/Resource_/PageResource/Overflow-Control-Program-
   Assistance/Final-Report-Kansas-City-Overflow-Control-Program-Middle-Blue-River-Basin-
   Green-Solutions-Pilot-Project-2013-ll.pdf
Pitt, R.; Talebi L. 2014. Modeling of Green Infrastructure Components and Large Scale Test
   and Control Watersheds. 218 pages. Appendices 193 pages.


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Tertra Tech. 2011. National Demonstration of the Integration of Green and Gray Infrastructure
   in Kansa City, Missouri.  A Pre-performance Summary Report.  9/30/2011.  98 pages.
Tetra Tech. 2013. Advanced Drainage Concepts for Using Green Solutions for CSO Control.
   2012 Summary Progress Report. 63 pages.
Region 7 - Omaha, NE

       Many cities with CSO controls often experience pollution of streams, lakes, and other

natural bodies of water when, in a rain event, the system is overwhelmed and is forced to

discharge untreated wastewater through CSOs.  This research looks at the combined potential of

the best of both green and gray infrastructure methods in retaining and/or slowing the movement

of stormwater before it adds to the CSS. A hybrid approach with green and gray infrastructures

playing to their respective strengths may also allow for downsizing or elimination of some

ageing gray infrastructure CSO controls. This paper details a field deployment to Omaha, NE in

order to characterize soil taxonomic and hydraulic properties of vacant lots, park land and other

transitional and mostly abandoned areas in order to assess their potential for the installation of

GI.

       Parcels, mostly vacant lots and parks, were selected for assessment by City of Omaha

wastewater officials in areas where the local sewershed may benefit from additional detention

capacity. This research sought to determine the soil taxonomic and  hydraulic properties of urban

soils in the greater Omaha area, as well as their potential to be used  as an effective stormwater

management tool. Types of GI that would be considered here  include any infiltration-based GI

such as rain gardens, in combination with gray infrastructure such as cisterns.

       In conducting this and related research it has been found that obtaining site specific soil

data is an important first step before any decisions are made as to what can be done to the green

space.  The site specific soil characteristics are often very different from what is described on


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generalized, regional tables and interpolated datasets. This is especially true in highly disturbed

urban areas where soils were either not mapped or only minimally so.

       The beginning of more research to come, this study supports the idea that a hybridized

system utilizing both green and gray infrastructure methods with the goal of reducing sewer

overflows is the most efficient and cost-effective alternative to managing stormwater runoff both

in the short and long term.  Incorporating GI techniques, such as rain gardens, into a stormwater

management plan not only lessens the stress on the current, ageing infrastructure, but is overall a

more sustainable and aesthetically pleasing option.

       Looking ahead, the issue of maintaining these GI SCMs once they are installed, needs to

be addressed. While municipal budgets are often stretched and there is little time for inspection,

post-construction monitoring to determine if the GI works effectively and appropriate operation

and maintenance should be conducted to ensure design effectiveness and otherwise guide

corrections.  This field protocol will be a model for other deployments and soil assessment

studies in looking for suitability for the implementation of future GI research.



References

Shuster, WD and S Dadio.  2014. Soils Investigation for Infiltration-based Green Infrastructure
   for Sewershed Management (Omaha NE). U.S. Environmental Protection Agency,
   Washington,  DC, EPA/600/2014/063.
   http://nepis.epa.gov/Exe/ZyPDF.cgi/P100KHY2.PDF?Dockey=P100KHY2.PDF



Region 8 - Denver,  CO

       This Region 8 RARE research culminated in  an ORD final report on green  roofs (EPA

2012). This green roof research was performed in an applied urban field condition of the rooftop

of EPA Region 8 Headquarters in downtown Denver, CO with supplemental plant and drought


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studies performed at Colorado State University in Fort Collins, CO. Due to the porous and well-




drained nature of the typical growing medium used in extensive green roof systems, the success




or failure of an extensive green roof is primarily dependent on a plant species'  ability to grow in




the media.  These challenges are intensified for extensive green roofs on buildings in areas




characterized by high elevation and semi-arid climate as typified by the environment of the Front




Range of Colorado. Success of an extensive green roof is primarily dependent on plant species'




ability to survive the low moisture content of the growing medium.  Plants adaptable to dry,




porous soils are primarily used in  extensive green roof applications. Although Sedum species,




which are succulents, have dominated the plant palette for extensive green roofs, there is




growing interest in expanding the  plant list for extensive green roof systems, especially using




native species.




       Prior to this study, green roof plants had not been scientifically tested for long term




survivability and adaptability in the Front Range of Colorado.  The low annual precipitation,




short periods of snow cover, low average relative humidity, high solar radiation (due to




elevation), high wind velocities, and predominantly sunny days all add up to challenging




growing conditions for many species of plants. Plant studies of individual plants, mixed




plantings and drought studies were performed. Amendments (i.e., zeolite), to traditional green




roof media was tested to see if this benefited the green roof plants. Additionally, overwinter




damage to the initially installed drip irrigation system allowed for comparative performance to




overhead drip irrigation system.




       The plant studies revealed, plant cover increased for all six species during the first




growing season.  Subsequently, one species was removed from analysis in the second season due
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to the low overwintering rate (12.5%).  Four of the five remaining species also exhibited




decreased plant cover due to winter dieback, but survived through the second season.




       In terms of plant cover, five of the six species evaluated in this study appear to be




appropriate for use in extensive green roof applications.  In the mixed study of eight species, at




the end of the study, the two native species that had higher plant cover than the others. Similar




to the individual plant studies, there were overwintering declines though competition may have




also determined success and reduction of species plant cover.




       Four growing media amendments were evaluated based on plant taxa growth




performance. The greatest increase in plant cover from the addition of zeolite was seen in




mixtures with 33% and 66% zeolite.




       In the drought study, fifteen plant taxa were evaluated for response to gradual and long-




term drying of the porous extensive green roof growing medium; despite  differences in dry




down, the succulent species maintained viable foliage for over five times longer than the




herbaceous species.  Additionally, the revival rates of the succulent species were nearly double




those of the herbaceous species.




       Volumetric moisture content (VMC) data were collected throughout the study and the




overhead rotary irrigation system delivered a more consistent amount of water throughout the




green roof as measured by instantaneous VMC. Less irrigation was applied in the second year




with the spray irrigation than in the first year with the drip irrigation system. Year to year, for




the months July through September, there was 10% more rainfall in the second year (i.e., 97 mm




compared to 88.1  mm), but there was 32% less irrigation required (i.e., 200 mm compared to 270




mm). Overall, the overhead rotary irrigation  increased biomass and plant  cover.
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       Due to the success of some native species in these experiments, the use of native plants

for green roofs should be pursued though finding adequate supplies may be an issue.  In the arid

west, green roofs will most likely require supplemental irrigation.  Due to the quick draining

nature of the green roof media and shallow rooted nature of most green roof plants  (especially

during establishment), drip irrigation should not be used for green  roofs.

       Based on the diverse effects observed in this study due to changes in irrigation regime

and interaction effects with zeolite amendments, future studies should look at root growth in

addition to top growth of plants. The low overwintering success or eventual die-off of several

species in the study and overall winter dieback of most of the observed species may be an

indication of desiccation of roots due to limited snow cover.  An additional limited irrigation

regime during winter months may improve plant survival in green  roofs in arid regions.

Additional studies should be performed with other zeolite mixture  ratios, additional native plant

species and mixture of species should be tested. Due to the need to irrigate in the arid west,

determining the cost effective benefits of green roofs beyond stormwater management needs to

be qualified for this GI practice to be more accepted in this area  of the country.



References

EPA.  2012. Klett, JE, JM Bousselot, RD Koski, and TP O'Connor. 2012. Evaluation of Green
   Roof Plants and Materials for Semi-Arid Climates. U.S. Environmental Protection Agency,
   Office of Research and Development, Cincinnati, Ohio, Report No. EPA/600/R-12/592.
   http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P100FS5E.txt



Region 9 - Phoenix, AZ

       Many cities with CSO often experience pollution of streams, lakes, and other natural

bodies of water when, in a rain event, the system is overwhelmed and is forced to discharge


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untreated wastewater through CSOs. By studying the soil morphology and correspondent




hydrologic data in the Phoenix area, this research was aimed at assessing the potential for




residential parcels and desert parks to be used as a tool in managing stormwater flows and




mitigate untreated runoff. This paper details a field deployment to Phoenix, AZ the purpose of




which was to characterize soil taxonomic  and hydraulic properties of Aridisol pedons found in




desert parks and residential parcels, as well as a few dual-purpose park-stormwater retention




basins in order to assess their stormwater  retention potential.




       This research effort looked at two  sites located in the outlying native Sonoran Desert that




have not been subject to direct anthropogenic disturbance, four residential lots representing a




range of neighborhoods and landscapes, and three stormwater retention basins that also serve as




recreational fields and feature turfgrass that is maintained and utilized throughout the year. This




study sought to determine whether the Aridisol soils found in the greater Phoenix area are




effective for retaining stormwater, especially those whose soil structure has been affected by




anthropogenic change. Specifically, the focus was on the use of retention basins and other




infiltration-based GI.




       The resulting hydropedological data indicate that the infiltration performance of retention




basins is low, probably due to the development of finer surface soils and compaction. Taken as




an aggregate, these findings also suggest that residential yards may have sufficient infiltration




capacity to detain the runoff volume that they produce.  Proper maintenance and clearing of




accumulated, fine-textured  sediments within any retention basin used for the purpose of




stormwater management may result in an  increase in infiltration and overall a more efficient and




impactful system.
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       Our limited number of hydropedological assessments indicate a potential for stormwater

management via infiltration into urban Aridisols, although further study is needed to develop

finer scale mapping of soil hydrology in this arid conurbation.



References

Shuster, WD, S Dadio, C Burkman, S Earl, and S Hall. 2015.  Hydropedological assessments of
   parcel-level infiltration in an arid urban ecosystem. Soil Science Society of America Journal
   79:389-406. doi:10.2136/sssaj2014.05.0200.
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