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INTRODUCTION
Across the United States there is increasing awareness of the need to address pollution generated by
stormwater runoff. As stormwater moves through the landscape it captures and carries trash, bacteria, heavy
metals, and other pollutants from the urban environment. These pollutants degrade the quality of receiving
waters and threaten public health. Stormwater can also cause erosion and flooding, damaging wildlife
habitat, property, and infrastructure.
Green infrastructure practices offer flexible solutions for managing stormwater runoff and protecting public
health and water quality. Green infrastructure works by incorporating both the natural environment and
engineered systems to protect, restore, or mimic the natural water cycle. A variety of green infrastructure
practices can be used to capture, treat, infiltrate, and evapotranspire stormwater runoff. At the local level,
green infrastructure practices include land conservation, rain gardens, permeable pavements, green roofs,
infiltration planters, trees, rainwater harvesting systems, and more. Applied at scale, green infrastructure
preserves and restores natural landscapes and allows for better management of stormwater runoff in the
urban environment. At any scale, green infrastructure practices can provide a wide array environmental
benefits.
Since 1988, EPA's Clean Water State Revolving Fund (CWSRF) has grown to become one of the largest
sources of public financing for water infrastructure projects in the country. Each of the 51 programs
operating independently across the 50 States and Puerto Rico demonstrate the power of federal and state
partnerships to protect the nation's water resources. States have significant flexibility within the CWSRF to
set competitive interest rates, establish their own funding priorities, assist communities of all sizes, and
leverage financial resources to address a wide range of water quality concerns. The flexibility, affordability,
and eligibilities inherent to the CWSRF make it an ideal vehicle for funding green infrastructure projects.
EPA developed its Green Infrastructure Policy for the CWSRF to capitalize on this compatibility. Released in
December of 2015, the policy promotes CWSRF investment in green infrastructure projects and broadly
encourages investment in sustainable infrastructure. Amongst the variety of sustainable projects that CWSRF
programs finance, green infrastructure offers flexible, innovative solutions for stormwater management.
The CWSRF's Green Project Reserve (GPR) also encourages investment in green infrastructure. Established
under the American Recovery and Reinvestment Act (ARRA) and carried forward with subsequent
appropriations, the GPR directs state programs to provide a variable percentage of their capitalization grants
to a range of sustainable water infrastructure projects, including green infrastructure. CWSRF programs have
been very successful at implementing the GPR, providing an impressive $5.5 billion in assistance to GPR
projects since EPA began tracking loan level data in 2010. As part of the GPR, CWSRFs have provided $1.2
billion to over 900 green infrastructure projects.
Eligible CWSRF recipients can choose from a wide array of green infrastructure projects that are eligible for
funding through the CWSRF. The Water Resources Reform and Development Act (WRRDA) of 2014
specifically amended the CWSRF program eligibilities with respect to stormwater, authorizing each CWSRF
program to provide financial assistance "for measures to manage, reduce, treat, or recapture stormwater or
subsurface drainage water." This language encompasses virtually any green infrastructure project that
mitigates stormwater runoff and opens a wide range of green infrastructure projects to CWSRF eligibility for
both public and private borrowers.
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Post-construction monitoring is not a requirement of CWSRF assistance. Nonetheless, recipients with
adequate technical, financial, and managerial capacity recognize that there is value in documenting and
sharing environmental outcomes: demonstrated success offers a path for other stakeholders to follow. As the
largest public source of water quality financing in the United States, the CWSRF program has the national
reach and resources to help expand the adoption of green infrastructure across the wastewater sector.
This collection of case studies explores the efforts of five CWSRF assistance recipients to monitor or model
the environmental benefits of green infrastructure practices. Their results are quantifiable, and not only
highlight the environmental benefits of green infrastructure, but tell an important story: across a wide variety
of projects and multiple geographic areas, CWSRF programs are making a substantial difference in the
national effort to prevent stormwater pollution.
Lancaster, PA
CWSRF Funding Integrates Green Infrastructure
and Public Works Projects
BACKGROUND
Lancaster City is the county seat of Lancaster County in central Pennsylvania. Like many urban communities
with deep historical roots, a complex system of infrastructure evolved to handle wastewater and stormwater
runoff from areas of dense urban development. Approximately half of Lancaster City is served by a combined
sewer system (CSS) while the other half is served by a municipal separate storm sewer system (MS4). Both
systems discharge to the Conestoga River, a tributary of the Susquehanna River that ultimately discharges to
the Chesapeake Bay. During wet weather events, partially treated or untreated sewage can exceed the local
treatment capacity, resulting in the discharge of combined sewage directly to the Conestoga River. Each year,
hundreds of millions of gallons of combined sewage impact contact recreation during and after wet-weather
events. Combined sewage overflows are only part of the runoff-driven pollution sources to the Conestoga
River, with large expanses of upstream agriculture and MS4 systems also creating impacts to recreation and
aquatic life. Many of the runoff management techniques the City is using are applicable to these sources as
well.
Lancaster City's Department of Public Works is embracing the potential of green infrastructure to address
stormwater runoff at the source before it can enter the CSS, improving water quality from the Conestoga to
the bay, while also creating urban green spaces that strengthen neighborhood communities and look inviting
to new businesses. In 2011, an ambitious Green Infrastructure Plan laid out a long-term path to integrate
green infrastructure as part of the City's normal public works projects in parks, streets, alleys, and as part of
private redevelopment projects. Making this vision a reality requires a clear and transparent business case
demonstrating the value of the green infrastructure project relative to the public funds invested and funding
sources that are cost-effective, flexible, and have the capacity to finance dozens of projects over a multi-year
time horizon: qualities embodied by the CWSRF program. In 2014, the City embarked on a landmark
partnership with funding from Pennvest to pilot green infrastructure across the City with a public-private
partnership which has played a critical role in the transformation of Lancaster City's stormwater
infrastructure.
PROJECT ELEMENTS - REBUILDING LANCASTER TO MANAGE RUNOFF LOCALLY
When Lancaster City issued its Green Infrastructure Plan in 2011, opportunities to increase green
infrastructure implementation were plentiful: impervious surfaces, mainly comprised of roadways, parking
lots, and buildings covered 48 percent of the city's 7.3 square miles. Located across a mosaic of public and
private properties, these impervious areas were not contiguous. Each prospective site presented unique
stormwater management challenges but also promised a variety of environmental, economic, and social
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4
benefits to residents. Municipal officials recognized that achieving these benefits would require flexible
implementation of green infrastructure practices in numerous locations. Lancaster City's Green Infrastructure
Plan laid out a path to accomplish exactly that through the city-wide implementation of green infrastructure
across several priority areas.
Parks
Tree plantings, bioretention, and other green
infrastructure practices located in parks and other
public spaces present opportunities to manage the
stormwater runoff from relatively large land areas.
Depending on the type and scale of the selected green
infrastructure practices, green parks can also help
manage stormwater runoff from adjacent impervious
surfaces such as streets, parking lots, and residential
roofs. In addition to preventing stormwater pollution,
vegetated green infrastructure practices, particularly
those that incorporate native plantings, have the
potential to create and/or restore urban wildlife
habitat, provide environmental education and
recreational opportunities, and help create a more
aesthetically pleasing urban environment.
Green Streets, Alleys, and Sidewalks
City streets and the alleys, sidewalks, and other
pedestrian rights-of-way that accompany them can
be a major source of stormwater runoff.
Incorporating tree trenches, bioretention,
permeable pavers, and other green infrastructure
practices into these locations converts them into
assets that manage stormwater runoff. When
designed and sited carefully, these assets can even
be capable of capturing runoff from adjacent
properties. Because these green infrastructure
practices are cheaper to implement when they are
incorporated during repaving, reconstruction, and
other routine maintenance activities, Lancaster
City's Green Infrastructure Plan identified 468 blocks
of green streets that will be implemented as streets
are reconstructed over the long term. The plan also
identified existing tree canopy in the City and set the
long-term goal of increasing coverage from 28 to 40
percent. Realizing this goal will increase stormwater
infiltration capacity along the City's streets, create
urban wildlife habitat, and lower summer temperatures.
Lancaster City's Brandon Park is home to a basketball court
constructed over permeable macadam, allowing stormwater
to infiltrate into the soil underneath the playing surface.
(Photo courtesy of the Lancaster City Department of Public
Works)
Permeable pavement lines an alley in downtown Lancaster
City. (Photo courtesy of the Lancaster City Department of
Public Works)
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5
A750-gallon cistern and bioretention basin outside of the Lancaster
Brewing Company. (Photo courtesy of the Lancaster City Department of
Public Works)
Private Property
Municipal officials recognized that to achieve
optimum green infrastructure implementation,
public property wouldn't be sufficient: Lancaster
City needed to engage citizens, local business
owners, and other private stakeholders. Local
ordinances require property owners who are
adding new impervious surface areas to manage
the first inch of rainfall on their property and not
allow it to discharge to the City's CSS. Green
infrastructure practices offer an effective means
of doing so, and property owners in Lancaster
City are taking advantage. One such property is
the Lancaster Brewing Company, which allowed
the City to install a 750-gallon cistern to store runoff
from the brewery roof. Other green infrastructure practices on-site include permeable pavers and
bioretention basins. Collectively, these green infrastructure practices not only help manage stormwater
runoff, but serve as public art that engages with and educates brewery patrons and passing pedestrians.
CWSRF ASSISTANCE
Thanks to $7 million in CWSRF funding from Pennvest, Lancaster City has successfully implemented 59 green
infrastructure projects that address their Green Infrastructure Plan's key priorities. 20 of these projects were
financed entirely through the CWSRF with the remainder paid for through a combination of CWSRF dollars
and funding from other sources. With more projects in the funding pipeline, Lancaster City is taking
significant steps to protect public health and water quality and bring the vision outlined in its Green
Infrastructure Plan to life.
ENVIRONMENTAL BENEFITS
Building 59 projects over 7 years is a significant step toward realizing Lancaster City's vision for
institutionalizing green infrastructure, but city officials realized up front that transforming a system of
infrastructure is a complex, long-term process that requires commitment and planning.
The City's current suite of completed green infrastructure projects demonstrate the scalability of these
technologies. When applied to wider area over a long-term time horizon, the potential environmental
benefits are substantial. Before moving forward with the City's Green Infrastructure Plan, city officials
conducted a thorough analysis of the predicted environmental benefits using a green infrastructure benefits
calculator developed by the engineering firm CH2M HILL, now Jacobs Engineering Group. Based on the
characteristics of various green infrastructure practices, the calculator yielded potential benefits of
implementing selected green infrastructure practices over 5 and 25-year periods. Major inputs to the
calculator included:
• Lancaster City's impervious surface area;
• Capture volume of green infrastructure practices;
• The amount of impervious area captured by green infrastructure practices;
• An average annual runoff coefficient of 85 percent based on other comparable cities;
• An average annual rainfall of 42.04 inches;
• The relationship between stormwater reduction and CSO reduction within the CSS;
• Implementation periods of 5 and 25 years; and
• Typical pollutant concentrations for urban stormwater runoff and CSO discharges
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The calculator's analysis yielded the following results:
Parameter
5-Year Implementation
25-Year Implementation
Impervious Area Managed by Green Infrastructure (ac)
221
1,265
Average Annual Runoff Reduction (MG/yr)
182
1,053
Average Annual Total Suspended Solids (TSS)
Reduction (Ib/yr)
252,000
1,457,000
Average Annual Total Phosphorous (TP) Reduction (lb/
yr)
4,800
27,800
Average Annual Total Nitrogen (TN) Reduction (Ib/yr)
10,700
61,600
Long-term implementation of green infrastructure practices in accordance with Lancaster City's Green
Infrastructure Plan will manage nearly 2 square miles of impervious surface, resulting in the capture of over 1
billion gallons of stormwater per year: enough runoff to fill over 1,500 Olympic size swimming pools.
Capturing this runoff will prevent significant amounts of sediment and nutrient pollution from impacting local
water bodies and polluting the Chesapeake Bay watershed,
Lancaster City's Green Infrastructure Plan lays out an ambitious new vision for how the City can manage
stormwater runoff and protect public health and water quality, but like all infrastructure projects,
prospective benefits are accompanied by logistical and financial challenges. Full implementation of the plan
will require 25 years and an estimated $77 million. Affordable funding from the CWSRF program helped the
City's Department of Public Works take crucial first steps toward implementation. With 59 projects on-the-
ground and more in the funding pipeline, Lancaster City is proving it has both the commitment and the
capacity to make its vision for green infrastructure a reality.
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Maplewood Mall, MN
CWSRF GPR Funds Green Infrastructure Project in Maplewood, Minnesota
BACKGROUND
The Maplewood Mall is situated within the Ramsey-Washirigton Metro Watershed
District (District). The District is a 65-square mile urban and suburban watershed on
the east side of the Twin Cities Metropolitan area in Minnesota, 40 percent of which
is comprised of impervious streets, highways, parking lots, and driveways. Within the
District, the Kohlman Lake Total Maximum Daily Load (TMDL) requires the reduction
of phosphorus in addition to the already defined District-wide goal of stormwater
volume reduction. In 2008, the District identified Maplewood Mall and the
associated parking lot as a major contributor of phosphorus loadings into Kohlman
Lake which sits just one mile west. Maplewood Mall is a 70-acre site, approximately
half of which is covered by a parking lot and is 97 percent impervious.
PROJECT ELEMENTS AND CWSRF ASSISTANCE
In collaboration with Simon Property
Group and the City of Maplewood, the
District broke ground on the four-phase,
multi-year project in 2009. The project
involved the installation of 55 rain garden
one mile of tree trenches, 375 trees, 6,73;
square feet of permeable pavers to
intercept runoff from parking lot areas,
and a 375-gallon cistern to catch runoff
from the mall roof. The project design
specified enhancements for certain green
infrastructure features, including iron
aggregate material in rain gardens to
capture dissolved phosphorus present in
stormwater and hydraulically-linked tree
trenches that provide treatment in series.
Construction was completed and all
project elements were in service by May 2013. The project was the recipient of approximately $1,570,000 in
SRF GPR funds, including approximately $392,000 in principal forgiveness, in July 2012. The total project cost
was $6.4 million dollars which, in addition to SRF funds, also included local funds, Minnesota Pollution
Control Authority (MPCA) Clean Water Fund Grants, a MPCA TMDL Implementation Grant, and a MPCA 319
Grant.
s,
3
% .'i
A bioretention installation helps manage stormwater runoff from adjacent streets and
sidewalks. (Photo courtesy of the Ramsey-Washington Metro Watershed District)
DATA COLLECTION AND METHODS
In 2013 monitoring data was collected from the Woodlyn rain garden, located at one of the entrances to the
mall. Rain gardens installed during later construction phases were modeled after the Woodlyn installation
and are likely to yield similar environmental benefits data. Water quality sample data was paired with rainfall
and flow monitoring data to calculate flow-weighted concentrations of total phosphorus, ortho phosphorus,
and total suspended solids entering and leaving the rain garden. The total volume entering and leaving the
rain garden was also measured. Inflow and outflow concentrations (and volumes) were compared to
determine the reduction in concentration and the pounds of removal for each constituent. Fourteen samples
representative of five distinct rainfall events were collected between May 17, 2013 and July 22, 2013.
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RESULTS AND BENEFITS
Data collected showed a 61 percent reduction of total phosphorous, a 51 percent reduction of ortho
phosphorous, and a 94 percent reduction of total suspended solids. These reductions are consistent with the
rain garden's removal rate design. The data also showed a 20 percent average reduction in stormwater
volume at the rain garden outflow point for the entire monitoring period. During a 0.64-inch storm event on
June 10, 2012, the rain garden reduced both peak discharge and outflow volume by 95 percent and 49
percent, respectively.
The District is planning to collect and monitor more data from the tree trenches. Water levels in the tree
trenches will be monitored during a series of storm events via installed water level loggers. In addition, tree
trenches will undergo a synthetic storm analysis in which a controlled volume of water is applied to each tree
trench and the drawdown time is observed.
GITYPE DATA COLLECTED UNITS RESULTS
RAIN GARDEN
Stormwater
(cubic feet, ft3)
Reduced stormwater volume by an
Volume
average of 20%
Peak Flow
{cubic feet per
Reduced peak flow by 85% during June
second, cfs)
10, 2012 event
Total Phosphorus
(mg/L)
Reduced total phosphorus
Load
concentration by 61%
Total Ortho
(mg/L)
Reduced total ortho phosphorous
Phosphorous
concentration by 51%
Total Suspended
(mg/L)
Reduced total suspended solids
Solids Load
concentration by 94%
TREE TRENCH
Drawdown Time
To Be Determined
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Maywood Ave, OH
CWSRF GPR Funds Green Street Project fn Toledo, OH
BACKGROUND
Maywood Ave is a residential street in Toledo, OH, composed mainly of single-
family homes prone to basement flooding. The street was selected by the City
for a pilot project to determine the effectiveness of installing green
infrastructure to reduce combined sewer overflows.
PROJECT ELEMENTS AND CWSRF ASSISTANCE
The pilot project involved the installation of approximately 1,300 linear feet of bioswales along both sides of
the street in the right-of-way and pervious concrete in driveway aprons and sidewalk areas. The street
surfaces were restructured to drain toward the green infrastructure features and curb cuts were engineered
to allow access to the bioswales in the right-of-way. Construction was completed on the project in 2010.
Though the project was intended to be a demonstration project for green infrastructure and a way to
educate and foster participation in the community, it had additional benefits including neighborhood
beautification and reducing neighborhood flooding. The project was the recipient of approximately $864,000
in ARRA SRF GPR funds in February 2010, all of which was principal forgiveness. The project also received
approximately $278,000 from Lucas County funds and U.S. Department of Agriculture's Natural Resource
Conservation Service (NRCS) to support additional green infrastructure.
DATA COLLECTION AND METHODS
To determine if bioswales and pervious concrete were effective in achieving the project's goals, a data
collection and monitoring effort was initiated. Two flow meters were installed in storm drains; one
downstream at the east end of Maywood Avenue and a surrogate monitor on the adjacent Russell Street for
comparison purposes. Pre-construction meter readings were recorded between the months of March and
June 2010 at both locations to provide baseline flow readings.
RESULTS AND BENEFITS
Following construction completion, flow meter readings over a six-month
period showed decreased peak flows in gallons per minute (gpm) and
increased stormwater storage and infiltration compared to pre-construction
monitoring results. In addition to the stormwater reductions achieved, zero
instances of basement flooding were reported through August 18, 2011. The
flow monitoring period was extended through fall and winter months in 2011
to evaluate year-round effectiveness of the green infrastructure projects.
In addition to flow meter monitoring, a Stormwater Management Model
(SWMM) was prepared to simulate the long-term impact of installed green
infrastructure. The model was calibrated using the pre- and post-construction
data collected by the two flow meters and rainfall data collected by tipping
bucket rain gauges. Simulation results showed art annual reduction of 10,560
gallons of runoff volume, approximately a 64 percent reduction, equal to
about three combined sewer exceedances per year. The model also showed a
60-70 percent reduction in peak flows at equivalent rainfall intensities.
A bioretention installation manages
stormwater runoff from adjacent
impervious surfaces. (Photo courtesy
of the City of Toledo)
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Gl Type
Data Collected
Units
Results
Decreased peak flow
compared to pre-
construction results
(see graph I)
Bioswales
Peak Flow
gpm
Storage/Infiltration
Increased storage/
infiltration compared
to pre-construction
results (see graph 2)
mg
Modelled Annual Run-
off Volume
Reduced annual runoff
volume by 10,560 gal-
lons(64%)
gallons
Reduced peak flow by
60-70%
Modelled Peak Flow
gpm
1200
1000
800
Pre-Cerlstruction
LL.
Post-Cor
400
200
~~
0,00 0.10 0,20 0,30 0.40 0.50
Peak Hour Intensity Rain (in/hr)
Figure 1: Graph of pre- and post- construction peak flows.
0.60
0.70
0.30
Post Constructor
0.20
0)
instruction
0.10
l-
0.05
0.00
ooo
0.50
1.00
1.50
Total Rainfall (in)
2.00
2.50
350
Figure 2: Graph of pre- and post- construction storage/infiltration.
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Williamsville, NY
CWSRF GPR Funds Green Infrastructure Project in Williamsville, New York
BACKGROUND
The Village of Williamsville is located in Erie County in western New York. The
nationally historic Williamsville Water Mill is located on Spring Street in the central
business district for the Village. The mill sits atop a bedrock ledge that was being
adversely impacted by stormwater runoff from Spring Street, Rock Street, and
adjacent parking areas. This runoff was significantly eroding the bedrock ledge and
affecting the stability of the mill's foundation. Additionally, the existing drainage
system of drop inlets and collection lines on Spring Street was clogged with sediment and not functioning
properly. This resulted in uncontrolled runoff over the 30-40 foot ledge, eroding the ledge and carrying silt
and sediment into the system of swales, streams, and ponds in Glen Park, which is located below Spring
Street. This stream system discharges directly to Ellicott Creek, which is listed by the New York State
Department of Environmental Conservation (NYSDEC) as a Priority Waterbody that is impaired due to silt and
sedimentation. The known source of contamination to the creek is urban stormwater runoff.
PROJECT ELEMENTS AND CWSRF
ASSISTANCE
To reduce erosion and improve water quality in Ellicott
Creek, the Village of Williamsville, in collaboration
with the Buffalo Niagara Riverkeeper (BNRK),
developed plans to reconstruct Spring Street to install
green infrastructure. The project includes the
installation of bioretention planters, rain gardens, and
porous pavers. These features are designed to
capture, filter, and slowly release runoff that is
currently conveyed directly over the bedrock ledge
into the system of swales and ponds in Glen Park. A
green wall system was installed to reinforce
a portion of the bedrock ledge and reduce erosion
while also treating stormwater runoff. The green
infrastructure work was part of a larger downtown
revitalization project, which includes the
redevelopment of the Spring Street area as a village
green focal point in the downtown area.
The project was funded through a $799,160 grant
from the New York CWSRF's Green Innovation Grant
Program administered by the New York State
Environmental Facilities Corporation. Additional
funding was provided by a $1,902,180 Water Quality
Improvement Project program grant administered by
the New York State Department of Environmental
Conservation, $722,856 in matching funds from the
Village, and $250,000 from Senator Michael
Ranzanhofer (administered through the Dormitory
Authority of the State of New York).
GREEN INNOVATIONS
SOLUTION:
A rain garden installed as part of Williamsville green infrastructure
improvements. (Photo courtesy of the NY State Environmental
Facilities Corp.)
Signage describing green infrastructure installed as part of project.
(Photo courtesy of the NY State Environmental Facilities Corp.)
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DATA COLLECTION AND METHODS
The BNRK conducted post-construction monitoring of stormwater quality and quantity from April through
May 2017. Riverkeeper staff collected samples from the stormwater outfall pipe during four post-
construction rain events. The samples were analyzed for Total Kjeldahl Nitrogen (TKN), Nitrate-Nitrite, Total
Phosphates, Turbidity, and Total Suspended Solids (TSS). Total Nitrogen was calculated from TKN and Nitrate-
Nitrite (N-N). In addition, precipitation was measured using a standard plastic four-inch rain gauge and flow
volume was monitored during the four rain events. The post-construction monitoring data was compared to
pre-construction monitoring results in which similar precipitation levels fell to determine any reduction in
flow volume and pollutants as a result of the project.
RESULTS AND BENEFITS
Monitoring results showed a substantial decrease in volumetric flow rate, turbidity, and TSS. Average
volumetric flow rate decreased by nearly 90 percent after the project was completed. Additionally, during
post-construction sampling there were 11 occasions where the flow of water from the outfall pipe was too
low to measure. The average turbidity decreased by almost 70 percent post-construction. This reduction in
turbidity indicates a reduction of suspended particles flowing off East Spring Street and into Glen Park and
ultimately, Ellicott Creek. The results of the TSS measurement reinforce this finding, with average TSS
decreasing by approximately 64 percent from pre-construction measurements.
Nutrient measurements were taken as an amount per volume of water. It is important to note that with the
90 percent reduction in volumetric flow rate resulting from the project, there is also a corresponding
reduction in overall nutrients from the outfall. Therefore, the nutrient reduction provided by the project is
actually far greater than indicated by the measurements in the table, below. On average, post-construction
samples showed lower nutrient levels than those collected pre-construction. Average TKN was reduced by
approximately 16 percent. Average phosphorus decreased by about 44 percent. Samples collected and
analyzed for Nitrate-Nitrite, which are naturally occurring, inorganic ions present in the environment
remained fairly consistent, with a slight increase of nearly nine percent.
Pre-coristructiori
Post-construction
Average volumetric flow rate
10,199.25 cm3 /sec
1,082.06 cm3 /sec
Average turbidity
1 12.1 1 NTU
34.7 NTU
Average TSS
57.39 rng/L
20.44 mg/L
Average TKN
0.8688 mg/L
0.7315 mg/L
Average phosphorus
0.182 mg/L
0.102 mg/L
Average N-N
0.30464 mg/L
0.33135 mg/L
The information collected during post-construction monitoring is important, as the Village hopes that this
project can serve as a model for other communities in the region and across the state, particularly for areas
with steep slopes. The Village is also looking to effectively use the project technology for other streetscaping
improvements in the area, and for the development of new standards for streetscaping design.
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linois River and Euchaw/Spavinaw Watersheds, OK
CWSRF GPR Funds Streambank Stabilization in the Illinois
River and Euchaw/Spavinaw Watersheds, Oklahoma
BACKGROUND
The Illinois River begins in the Ozark Mountains in the northwest corner of
Arkansas and flows west into Oklahoma, where the Oklahoma Conservation
Commission sees it as one of the highest priority watersheds. Once entering
Oklahoma, it then flows southwest and south through the mountains of
eastern Oklahoma into Tenkiller Ferry Lake, a popular recreational destination for Oklahomans that supports
a sizable tourism industry. The Illinois River and most of its major tributaries are classified as state scenic
rivers. However, the River, Lake Tenkiller, and some of the principal tributaries in the watershed are not
meeting water quality standards for nutrients, bacteria, and other issues, creating a threat to not just the
environment but public health and the economy. One significant contributor to nutrient loads and sediment
is unstable and degrading streambanks.
PROJECT ELEMENTS AND CWSRF ASSISTANCE
In 2009, the Oklahoma Conservation Commission (OCC) identified 35 sites
in the Illinois River Watershed with significant bank erosion where
landowners and land managers were requesting assistance to address
sustained streambank erosion. Of these sites, 12 were selected for
streambank stabilization projects to reduce erosion of sediments and
nutrients.
These 12 streambank stabilization projects restored almost 7,000 linear
feet of stream. They were very successful, weathering many significant
flood events. Approximately three years after project completion, the
watershed experienced its largest flood event ever recorded. Fortunately,
none of the projects lost further ground beyond the originally protected
banks; however most experienced some damage, and a few required
repairs to prevent damage to the originally protected bank. In 2016,
repair work was completed on four of the sites. In addition, one new site
was repaired, in partnership with the Oklahoma Department of
Transportation (ODOT), which restored an additional 2,830 feet. This site
was restored because ODOT had seen the original 12 restorations and
was anxious to implement similar methods near a threatened highway in
the watershed.
The project was funded with a $2,000,000 loan from the Oklahoma
CWSRF program, administered by the Oklahoma Water Resources Board,
for the restoration of 11 sites. The U.S. Fish and Wildlife Service provided
an additional $100,000 to address one site.
DATA COLLECTION AND METHODS
To estimate reductions in nutrients and sediment loading as a result of
the streambank stabilization projects, the OCC collected measurements
of the length of eroding bank at the 12 restoration sites using site and
iand bed surveys. This data was analyzed using GIS to determine
Streambank before project. (Photo courtesy
of the Oklahoma Conservation Commission)
Sis
Streambank after project. (Photo courtesy of
the Oklahoma Conservation Commission)
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14
streambank migration rates over time and provide an estimate of the volume of sediment lost. The OCC also
collected bank sediment analysis data for other OCC projects in the basin to provide an estimate of nutrient
concentrations in streambank soils in the basin, based on generalized stream order. Load reduction results
for the 12 streambank stabilization projects were then modeled, based on relative stream order and length of
bank stabilized.
RESULTS AND BENEFITS
Using the model, it is possible to estimate load reductions, per year, that have resulted from the 12
streambank stabilization projects (and subsequent project efforts).
Project
Linear Feet Restored
Tons Sediment Reduced/
year
Pounds Phosphorus
Reduced per year
Pounds nitrogen
reduced per year
12 streambank stabilization
sites
6,657
3,954
1,669
3,535
Repairs + ODOT
3,146
3,030
1,256
2,546
Total
9,803
6,984
2,925
6,081
Since construction, accounting for the sediment (and related nutrient loss) that occurred during the two
major storm events, load reductions from the 12 streambank stabilization projects and additional linear
repair and ODOT site work are estimated to be:
Project
Tons Sediment Reduced
Pounds Phosphorus
Reduced
Pounds Nitrogen Reduced
12 streambank stabilization
sites
20,760
8,760
18,560
Repairs + ODOT
6,460
2,690
5,500
Total
27,220
1 1,440
24,060
This load reduction is critical since modeling suggests that 80-90 percent load reductions will be required to
meet water quality standards in the watershed. Significant reductions in NFS loading will be required, which
may be impossible without streambank stabilization and protection.
The measured impacts in the watershed are significant, but more importantly, the projects served as the
impetus for new partners to do additional streambank work in the watershed, resulting in more stabilization
and greater load reduction impacts. The projects also resulted in additional interest in the methods across
the state. ODOT is using these methods in other watersheds throughout Oklahoma, and the workshops
associated with the project introduced many people to the concept of natural channel restoration resulting in
many additional projects.
For more information about the CWSRF please contact us at:
United States Environmental Protection Agency
Clean Water State Revolving Fund Branch
Office of Water, Office of Wastewater Management
1200 Pennsylvania Avenue, NW (Mailcode 4204M)
Washington, DC 20460
Document Number; 830B18001
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