EPA RainWorks Challenge
Green Wall and Rain Garden System for the Campus
Joel Brunner • Andrew Cawrse • Margaret Cope • Graham Fazio • Ciara Rahn • Danielle Slotke
Team #S73
The Stormwater Problem: Urbanization has resulted in approximately 25 million acres of
impervious surfaces in the United States (Kloss and Calarusse 2006). As a result, urban areas
have little open space to capture stormwater during precipitation events. In our city, this has
led to an increase in the amount of stormwater entering the combined sewer system. In areas
where stormwater flows to a combined sewer system, impervious surfaces contribute to
combined sewer overflows (CSOs). CSOs occur when sewers become overfull from rainfall and
the sewer discharges the mixture of wastewater and rainwater in order to prevent basement
backups. One solution to help prevent CSOs is to incorporate new green spaces into the urban
areas through green infrastructure. Green infrastructure retains polluted stormwater, which
results in healthier ecosystems, and the captured water is allowed to infiltrate and recharge the
groundwater. This process helps mitigate flooding and CSOs by reducing the amount of
stormwater discharging to the sewer system.
The campus for the proposed project is located in a densely urban environment and is
surrounded by a mix of residential and commercial properties. The city that includes the
campus is located in the Midwest and experiences varying seasonal temperatures that range
from hot and humid summers to below freezing and snowy winters. In addition, the weather
patterns for the area are very sporadic, from intense precipitation events to long periods of
drought. In July of 2010, the area experienced record-setting rainfall over a short period. The
total rainfall over one day ranged from five to nine inches and more than 4,400 homes in the
city reported flooded basements (NOAA, 2010). The intensity of the rain overwhelmed the
sewer system, which resulted in 2.1 billion gallons of combined sewer overflows and separate
sewer overflows (Metropolitan Sewerage District, 2010). The city has taken steps to alleviate
combined sewer overflows including the construction of storage that is designed to store 521
million gallons of water. However, CSOs still occur in the city during times of especially heavy
precipitation.
Project Location: The combined sewer service area encompasses approximately 5% of the city’s
sewer service area and is primarily located in the highly developed urban area of the city.
(Metropolitan Sewerage District, 2012). While the campus is located within the combined
sewer service area, the storm sewers on the campus are separate from the sanitary sewers
until they intersect with the combined sewers running down the bordering streets’ rights-ofway (Wasley, 2006). The campus itself is highly developed with a mixture of buildings, streets,
sidewalks, and parking areas. The campus has approximately 61 acres of impervious surface,
which accounts for 53% of the total campus area (Wasley, 2006). These impervious areas on the
campus increase the amount of stormwater that discharges into the storm sewer and into the
combined sewer. In addition, the campus’s conventional stormwater management approach
has been to remove it from the developed areas as quickly as possible (Wasley, 2006). The
combination of impervious surfaces and a stormwater management approach that promotes
using a system of pipes to drain stormwater quickly means that most of the rainwater that falls
on the campus ends up in the combined sewer, thus elevating the risk of CSOs. To combat this
problem, the campus has begun to advocate a Zero-Discharge Goal, which strives to reduce the
amount of stormwater discharging to the sewer system through green Best Management
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Practices (Wasley, 2006). One way to help the campus obtain its goal is through the
construction of green infrastructure on the campus.
Our site, the English Building (Figure 1), is located in the eastern portion of the campus and has
a roof area of approximately 2,513 square feet. The roof area that drains into our green
infrastructure system consists of
approximately 838 square feet. The
current stormwater management
system for the site building consists of
an externally drained roof. The
stormwater falls on the roof and drains
from stone scuppers directly into the
sewer system. As the stormwater
management system currently stands,
very little, if any, rainfall that lands on
the building is captured before
entering the sewer system. The site is
located near the southeastern corner
of this building. This area includes a
windowless and unadorned southern
wall and a ground surface that consists
of a layer of gravel with no landscaping.
This area is generally unappealing to
look at and does very little to improve
the visual quality of the campus. Green
infrastructure in this area will not only
capture and reduce the amount of
stormwater discharging into the sewer
system, but would also make the area
much more aesthetically appealing.
Green Infrastructure Solution: Green infrastructure can take the form of large-scale projects
such as regional open space networks to smaller, localized projects such as rain gardens. Our
project focuses on combining two types of urban Best Management Practices, a green wall and
a rain garden. A green wall is a vertical vegetated wall that is either freestanding or
incorporated into part of a building. The green wall will be located adjacent to the south wall of
the site building. The green wall will be connected to one of the roof drainage scuppers with a
downspout and will capture a portion of the stormwater discharging from the roof. Runoff that
is not captured by the green wall will flow into a 55-gallon rain barrel situated below the green
wall and will be used for irrigation purposes. The final step in our system consists of a rain
garden located at the base of the green wall. The rain garden will be responsible for capturing
and retaining stormwater that is not contained by the green wall or rain barrel.
The main goal of the project is to reduce the amount of stormwater that is discharging from the
site building directly into the sewer system. This will reduce the amount of water that is leaving
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the campus and entering the combined sewer system, which will help alleviate the chance of
combined sewer overflows during times of heavy precipitation. In addition, the captured
stormwater will slowly infiltrate back into the environment and recharge the groundwater.
Green infrastructure, such as green walls and rain gardens, has ecological benefits as well. The
main ecosystem goals for the project are to reintroduce native species back to this area and
promote biodiversity by providing a more natural habitat for different species of animals. The
system will also capture and retain pollutants that flushed from the roof of the site building.
The following proposal defines the group’s selection of a green infrastructure project for our
campus and describes how the solution will lead to a number of benefits.
Green Wall Benefits: Because green walls are less common than many green infrastructure
options, the benefits of green walls are less understood. A green wall is defined as a wall that
incorporates vegetation in its structure or on its surface that does not require the plants to be
rooted at the base of the wall. Green walls are not an entirely new idea and have proven to be
very useful in many different ways; “The concept of a green wall is an ancient one, with
examples in architectural history dating back to the Babylonians with the famous Hanging
Gardens in Babylon” (Kontoleon and Eumorfopoulou, 2009). This concept is making a
resurgence in cities around the world that want to be a leader in green infrastructure. Green
walls supply countless benefits: improving aesthetics, regulating temperature and reducing
carbon footprint, protecting building exteriors, providing habitat for wildlife, improving air
quality, noise reduction, and, most importantly stormwater runoff mitigation. These benefits
can help meet the challenges of the future. “A major challenge for the 21st century is
integrating human and non-human use of urban areas to support biological conservation
without compromising societal utilization” (Francis and Lorimer, 2011). Integrating green
infrastructure such as green walls will have a variety of benefits to the community.
Water Quality Benefits: Mitigation of storm water is both an environmental and social benefit
that can be gained from green walls. The city in which our campus is located uses a combined
sewer system to collect and treat sanitary and stormwater flow. This creates problems when
there is a large rainfall event that inundates the system, and sometimes forcing the sewerage
district to release a mix of treated and untreated water into Lake Michigan. These occurrences
are well documented in the city, and much research has been devoted to finding the impacts of
the combined sewer overflows.
Scientists have indicated, “2.5 inches of rain in one day would initiate a combined sewer
overflow into Lake Michigan, and the frequency of these events is expected to rise by 50% to
120% by the end of this century” (Patz et al., 2008). A green wall can be a vital tool to prevent
those combined sewer overflows. Green walls absorb between range 45-75% of rainfall while
acting as a natural filter (Francis and Lorimer, 2011). In contrast, without green infrastructure,
this rainfall would become runoff to be treated at the wastewater treatment plant.
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Figure 1: Below is a demonstration of how to determine the amount of rain that could be
infiltrated through the green wall:
Total Rooftop Area = 2,513 sq. ft.
Approximate area draining into the downspout = 840 sq. ft.
Green wall area = 80 sq. ft.
Amount of rooftop water with one inch rain = 500 gallons/1 inch rain
An educated guess on the percentage of the roof a green wall can infiltrate  10%
500 gallons x 10% = 50 gallons infiltrated by the green for every inch of rain
Region averages 35 inches per year.
35 inches x 50 gallons= 1,750 gallons/year
The educated guess was based off what a properly sized rain garden can infiltrate, which is 30%
of the total roof top area. A rain garden is much deeper and water can infiltrate over a longer
time period compared to a green wall that has water moving through it quicker due to gravity.
This is an estimate because there isn’t previous science based research on what an
appropriately sized green wall compared to the roof area can soak up. This is why our
proposed green infrastructure grant is important to get funded to see the limits of a green wall
in action, and test it as a viable way of reducing stormwater runoff from our campus.
Social-Environmental Benefits: Several social and environmental benefits accompany the
construction of green infrastructure. For example, they can aid in noise reduction. Plants and
planting medium act as an insulator for reducing sound reflection; “recently sustainable cities
have found that greenery is a key element in addressing noise pollution, giving rise to vertical
systems” (Wong et al., 2010). Especially in an urban campus setting, the reduction of noise is
beneficial to everyone around. It is beneficial to the campus because it limits the noise in and
around that building, and yet it is also beneficial to the surrounding residential neighborhoods.
Improved exterior air quality is also an associated advantage. Green walls capture airborne
pollutants and atmospheric deposition on leaf surfaces while filtering noxious gases and
particulate matter helps improve the local air quality. “Vegetation is not only limited to particle
adherence; it is also efficient in taking up other air polluting substances in particulate matter
such as CO2, NOx, and SO2” (Ottele et al., 2010). Clean air and clean water are the two most
essential elements in our world, and a green wall is very proficient at filtering both.
They can also reduce the urban heat island effect. Vegetation cools exterior surfaces of
buildings and reduces the amount of reflected heat. Green walls can create microclimates that
help reduce the city temperature as a whole. “Impervious surfaces like facades influence the
microclimate around the city by increasing temperatures around the buildings, which can be
solved by green infrastructure in which the heat energy is consumed by evapo-transpiration”
(Sheweka and Mohamed, 2012). This benefits the surrounding buildings which remain cooler,
thus reducing cooling costs in the summer.
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Green walls are also often an aesthetic improvement to bare exterior walls. Studies have shown
that the presence of plants can improve human health and mental well-being. “Interaction with
plants, both passive and active, can change human attitudes, behaviors, and physiological
responses” (Lohr et al., 1996). Plants also have stress-reducing benefits for people by “passively
viewing them in natural settings”. (Lohr et al., 1996). Plants, like those found in a green wall,
can indirectly influence people in its surroundings, creating a calming and soothing
environment from which all can benefit.
An additional benefit of implementing stormwater management structures such as green walls
will be an education tool for the university to use. Several classes can benefit from learning how
a green wall works and the value it has to the campus and surrounding community.
Structural Benefits: The use of a green wall would help offset the costs of heating and cooling
such a large building in those climates. Green walls have the potential to improve energy
efficiency. Our area experiences cold, harsh winters and grueling, hot summers. By providing a
thick layer of vegetation between the building structure and external temperatures, they
improve capacity for thermal insulation. Empirical data on the thermal performance of green
walls is hard to come by, though studies are emerging. For example, a study in Greece found
that “temperature differences between the exterior and interior surfaces of plant-covered wall
are essentially reduced when compared with conventional bare walls” (Kontoleon and
Eumorfopoulou, 2009). “A metropolitan scale survey in Tokyo suggests temperature reduction
by 5-8° C at facade wall surface” (Cheng et al., 2010). Reducing that temperature in the summer
and insulating the building in the winter will not only decrease the university costs to heat and
cool the building, but will also reduce use of gas or coal to create electricity.
Another benefit of using a green wall is the protection it gives to the exterior of the building.
Green walls decrease the rate at which UV radiation, precipitation, and temperature
fluctuations wear down a building’s exterior material. This will lengthen the lifespan of the
building thus saving the university money in updating the infrastructure of the campus. When
building new structures, it is important to use green infrastructure because sustainable
certification and recognition can be achieved. Green walls contribute toward several LEED
credits when used in combination with other sustainable building practices.
Promoting green infrastructure, such as green walls, is seen throughout the country. The local
sewerage district has a sustainability division that educates and supports green infrastructure.
Our campus also strives for a greener campus, creating a rainwater plan for the university and
implementing green roofs, rain gardens, and more. Elaborate green walls like the one proposed
can show a campus’s concern for the environment, therefore promoting green infrastructure
techniques to others in the area.
Rain Garden Benefits: Indeed, the concept of green infrastructure is becoming more common
throughout the United States. Green walls can improve the urban environment by providing the
social and environmental services described above. However, our plan includes a rain garden to
work in tandem with this green wall would increase these benefits and improve the system’s
efficiency at stormwater runoff reduction overall. Rain gardens have significant potential in
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reduction of runoff and delay of peak flow to the sewer system. They introduce native
vegetation and can be retrofitted for existing impervious sites to mitigate runoff while creating
a visually appealing and ecologically useful space. Furthermore, as the efficiency of the green
wall is observed, the garden will be able to store much of the remaining stormwater runoff
directed through the system.
This garden is proposed as part of a system with a green wall because rain gardens alone are
not effective at removing all flow during heavy rain events; once the soil becomes saturated,
the garden is less efficient in storing water and contributes flow to the combined sewer system
(Shuster et al., 2007). This project will increase the volume of stormwater runoff retained in our
green infrastructure installation by using the green wall to first capture runoff from the roof
and direct the remainder of flow to the rain barrel and rain garden, and by doing so create an
efficient system for management of stormwater even during intense rainfall.
Studies indicate that significant amounts of runoff can be infiltrated and ultimately prevented
from entering the combined sewer system; during an average rainfall with discharge directed to
a well-designed rain garden, over ninety-eight percent of runoff may be infiltrated and exit the
rain garden as subsurface flow, while less than one percent will leave the system as runoff
(Dietz and Clausen, 2005; Abi Aad et al., 2010). It is difficult to predict precisely how much flow
the rain garden will infiltrate, especially as each rainfall is different in terms of intensity,
duration, and volume. However, we have estimated the potential impact during a single heavy
rainfall and for the entire year based on average rainfall for this region of the United States.
A study by the USGS observing rain gardens with similar soil texture and using prairie
vegetation estimated an average infiltration rate of 6.5 inches per hour with a median rate of
4.2 inches per hour. This is considerably higher than the infiltration rate of 2.5 to 3.0 inches per
hour using the same soil, but instead planting the area with turf grass. With data collected over
four years, researchers were able to determine that approximately 90% of all precipitation
entering the rain garden would be stored within it (Selbig and Balster, 2010).
Using this conservative estimate of infiltration potential and the average rainfall for the campus
and surrounding region, we have estimated the potential storage for our rain garden (Figure 2).
The area of the roof to be directed toward the proposed system was visually assessed to be
approximately 840 square feet, and the average rainfall for the area is approximately 35 inches.
As calculated in Figure 1, this is a volume of approximately 17,500 gallons per year. Assuming
average infiltration of the rain garden, 90% of runoff, 15,750 gallons will be stored in this part
of the system alone in a typical year (Selbig and Balster, 2010).
Figure 2: Below is a demonstration of how to determine the amount of rain that could be
infiltrated through the rain garden:
Total Rooftop Area = 2,513 sq. ft.
Approximate area draining into the downspout = 840 sq. ft.
Amount of rooftop water with one inch rain = 500 gallons/1 in. rain
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Region averages 35 inches per year.
35 inches x 500 gallons= 17,500 gallons/year
Similarly designed rain gardens in the region absorb 90% of runoff in a year.
17,500 x 90% = 15,750 gallons infiltrated by the green wall.
This is only a small amount of the stormwater entering the city’s combined sewer system every
year, but the local metropolitan sewerage district created a model to estimate the percent
reduction in combined sewer overflows from major storms by rain gardens. These overflows
occur when the combined sewer cannot contain the influx of sanitary and stormwater, and
implementation of best management practices like rain gardens in residential areas could
reduce the peak flow during these major events by 5 to 36% (Metropolitan Sewerage District,
2005).
Though the rain garden cannot infiltrate all flow during prolonged or intense rain events, it is
predicted that the presence of the rain garden will have an impact on rate of flow exiting the
site. The introduction of a pervious surface will slow the runoff from the leaving the area, and
have a reduction on the peak flow of the storm by 58 to 70% (Davis, 2008); while impervious
surfaces will immediately allow flow to exit to the combined sewer system, this green space will
capture and delay that flux to the sewers, creating a more even and constant flow of water
from the area to the storm drains (Davis, 2008). This is a significant improvement in infiltration,
as the area selected for this project is largely impervious and currently allows little or no
infiltration.
The joint benefits of runoff reduction and pollutant removal make rain gardens an efficient and
viable option for an urban campus. Coupling a green wall and a rain garden in a visible location
will serve not only an environmental purpose in water quality improvement, but economic and
social purposes as a gathering place and educational fixture as well. The combination of a
traditional piece of green infrastructure, the rain garden, with the unexpected and unusual
construction of a green wall, will provide a visually interesting example of the university’s goal
for awareness of water quality issues and the need for sustainable solutions.
Green Wall Design: The green wall consists of a ten-foot high, eight-foot long, and two-foot
wide freestanding structure. Three 14-foot treated posts anchor the two ends and the center of
the green wall structure. The back of the wall consists of an aluminum screen to contain the
growing medium (Coffey, 2009). In addition, a waterproof membrane is located between the
aluminum screen and the building wall to ensure that the building does not encounter water or
moisture issues because of the green wall. The front of the green wall consists of steel panels
with two inch perforated squares that allow the plants to grow through while holding the
growing medium in place (Coffey, 2009). A layer of garden fabric between the steel panels and
the growing medium ensures that the growing medium is contained inside the green wall. The
green wall is then securely anchored to the building.
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The top of the green wall consists of a slightly sloped trough. A downspout is connected to two
of the site building’s drainage scuppers and connected to the highest point of the green wall.
The stormwater flows off the
building roof and into the
downspouts making its way
to the top of the green wall.
As the stormwater flows
down the slightly sloped
trough on the top of the wall,
a portion of the water will
flow into drains at the top of
the wall and into an internal
irrigation system for the
green wall. The irrigation
system consists of evenly
spaced horizontal and vertical
plastic drip tubing. The tubing
will fill with stormwater and
irrigate the plants. In
addition,
the
irrigation
system can be used to distribute fertilizers throughout the growing medium when necessary.
Excess stormwater that does not drain into the green wall will then discharge into a downspout
connected to the lowest point at the top of the wall into a connected 55-gallon rain barrel
situated below the green wall. The rain captured by the barrel will be used for irrigation during
dry periods. In addition, monitoring the water level in the barrel can be used to extrapolate
how much stormwater the green wall captures. When the barrel fills during a heavy rain event,
the excess water will spill into the rain garden situated below the green wall.
The growing medium and vegetation used in the design are crucial to ensure the success of the
green wall. The hollow space between the front and back of the wall is filled with a lightweight
growing medium such as coir
mixed with native soils. The
design of the growing medium
provides a planting base as
well as the nutritional needs
required by the native plants.
The vegetation used in the
green wall will have to be
carefully selected in order to
ensure that the plants will
thrive
in
the
chosen
environment. One of the main
factors taken into account will
be the colder climate in this
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region. The chosen plants will consist entirely of shallow-rooted native species that evolved to
thrive in the cold climate conditions. The plants will have to be able to survive through freezing
temperatures in the winter as well as hot, dry summers. In addition, how the plants react to the
different seasons will have to be considered since the aesthetics of the green wall will change
with each season (GRHC, 2008). Local experience has identified types of native plants that
thrive in green roofs on the campus, which will be used when determining the types of plants
that would most likely be successful in the green wall.
Additional Green Wall Research: Additional experimentation needed to implement this green
wall concept at our university is how well a green wall reacts to the harsh winters in our area.
We have seen green walls successfully implemented in warmer climates, but have not found
research on its use in the Midwest climate. Different plants must be used in a temperate
climate than an arid climate, and some experimentation on what plants work best at absorbing
the water and are still hardy to survive extreme conditions. Our region is prone to both drought
and flood conditions, and further research how the green wall would act in either case is
needed in order to implement a green wall. An additional question that arises with a green wall
is which plants will be able to grow and thrive on the wall sideways. Most plants should survive
and grow in a green wall, but we cannot say with certainty that they will.
Further experimentation required is how much water a green wall can absorb in a dry and wet
condition. Francis and Lorimer suggest that green walls can retain 45-75% of rainfall in a green
wall (Francis and Lorimer, 2011). A review of scientific literature uncovered little definitive
information on the amount of water a green wall can take up, so further research is needed to
decide the size of the green wall, and its hydrologic relationship with the rain garden. Another
factor that must be addressed is finding the best way to attach the green wall to the building.
Consulting with a construction company and proposing our project will likely be a good way to
determine how to secure it.
Rain Garden Design: A major factor in the effectiveness of a rain garden is the type of soil in
the area. Much of our region is comprised of heavy of clay soils. To increase the amount of
water that can be captured, we will excavate two feet of the clay soil and replace it with a
mixture of 50-60% sand, 20-30% topsoil, and 20-30% compost (WMEAC, 2012). Another feature
of the rain garden design is a "ponding" area. The purpose of this area is to ensure that
stormwater entering the system spreads out over the entire surface area of the garden. To
ensure this, the planting surface will be six inches deeper than the surrounding area. This will
allow for water to pool in the garden as it infiltrates into the ground. To accommodate this, an
additional 6 inches of existing clay soil will be removed and not replaced. This combination will
allow for much more efficient stormwater drainage and absorption in the garden.
The next issue considered was the location of the rain garden. Given that our garden will be
constructed alongside a green wall, we want to maximize the amount of stormwater entering
our system. In order get the greatest benefit from our garden, we picked a site that would allow
us to reroute water from a minimum of two down spouts. Other key factors that lead us to
select our site were the availability of a flat wall to mount our apparatus to and the fact that the
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ground has no measurable slope. Before construction, precautions must be taken to ensure
that there are no utility lines beneath the site.
When using sandy soils, the recommended size for a rain garden is anywhere from 20-30% of
the drainage area (WMEAC, 2012). This is dramatically smaller than the 60% drainage area
recommended for the clay soils currently in place. This means that for a 1,000-ft2 rooftop, a
200-300 ft2 rain garden would capture the same amount of stormwater as a 600 ft2 area
comprised of clay soil. As we are unsure how much water our green wall will hold, we designed
our garden to be able to handle the entire volume from 838 ft2 of roof. This ensures that none
of the stormwater from these downspouts will make its way into the combined sewer system
even if the green wall doesn’t absorb any water.
The rooftop of our building is 2513 ft2 and drains through six separate downspouts. We will
redirect water from one of these draining locations into our system to direct rainwater from a
roof area of 838 ft2 to drain into our green infrastructure. Although only 251 ft2 (30% of the
drainage area) is recommended for sandy soils, we will only be replacing to a depth of two feet
the existing clay soil. Because we want to prevent stormwater from entering the combined
sewer system in heavy storm events, we designed our garden to be larger than recommended.
Considering these factors and the dimensions of our site, we decided upon a garden of 530 ft2.
The vegetation in the rain garden will consist entirely of native plants since native plants
evolved to thrive in the local climate and ecosystem and have a high likelihood of survival
(WMEAC, 2012). Native prairie vegetation has also been shown to increase storage and
infiltration rates. The USGS conducted a five year study observing the retention capacity and
drainage rates of gardens consisting of native prairie vegetation compared to those with turf
grass and found dramatic differences. Native prairie vegetation was able to store an average of
0.21 inches of rainfall more above ground and 0.74 inches more below (Selbig and Balster,
2010). They also showed that the use of native plants in rain gardens resulted in an average
infiltration rate 0.6 inches/hour faster than those with turf grass (Selbig and Balster, 2010).
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Figure 3: List of plants recommended for the garden with key for planting location.
(CityofMadison.com/engineering/stormwater/raingardens.cfm)
The plants we selected for our garden were also chosen to be ideal for partial shade. Our
garden is shaded throughout parts of the day by large trees and a small portion is blocked
intermittently by a pedestrian ramp. Our list of plants and their respective location can be seen
in Figure 3.
Value and Costs of Proposed System to Campus: Urban stormwater runoff from impervious
surfaces is the number one threat to water quality in Lake Michigan (Wasley, 2006). Our
campus’s goal is to continue leading higher education institutions in the art and science of
designing green infrastructure. The campus's proximity to a Great Lake and the need to address
stormwater runoff into the Great Lakes make the campus a prime location for designing,
implementing, and monitoring the benefits of stormwater management in an urban location.
Our campus has a stormwater master plan that addresses stormwater management on
campus’s highly impervious campus. Three main water-related goals are identified in the
campus master plan: conserve/reduce campus water usage through operations and human
behavior changes, engineer and landscape for zero-stormwater discharge from campus, and
address frequently flooded buildings on campus (Wasley, 2006). This will allow for the
university to become a visual model and teaching tool for stormwater management. The
campus has implemented green roofs and rain gardens. Our project would add diversity to the
stormwater management tools and conforms to the campus master plan.
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The diamond on campus map (Figure 4 on the following page) marks the site of our green wall
and rain garden system. The site is an excellent choice for this project due to visibility from the
street and walkway. Current characteristics of the location include gravel, stormwater drains, a
roof runoff system and impervious surfaces. Numerous bus routes pass this building, which
increases the number of students viewing the system. Many students will be able to enjoy the
site and learn about the green wall and garden. Potential users would be able to hold outdoor
meetings and learn about stormwater management. Environmental student groups will be able
to teach others about the benefits from stormwater management. Our project is innovative
because no green walls have been implemented on our campus. This would add diversity to the
types of green infrastructure and stormwater management on campus and add to knowledge.
Figure 4: Campus map. The blue diamond indicates location of proposed green infrastructure.
A wide variety of users will benefit from this project ranging from classes to student groups.
Planning, environmental engineering, environmental science and public policy or administration
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classes could visit the site and have hands-on learning for conservation and environmental
policy and planning. Hands-on experience with a topic increases student learning.
The main stakeholder is the campus environmental sustainability coordinator. Our group has
been in contact with her, and the stated her support for the project. Other stakeholders would
include facilities, maintenance and possibly environmental student groups. Student
stakeholders would include environmental conservation groups such as Ecotone and Emerging
Green Builders. The student groups can get involved by volunteering to plant and maintain the
green wall and rain garden.
Budget
Capital Costs
Green Wall
14' wooden posts
80 sq ft aluminum screen
80 sq ft waterproof membrane
(plastic)
80 sq ft perforated steel panels
80 sq ft garden fabric
10' metal sheet
10' PVC
native plants
coir and soil ~160 cubic ft
disconnect downspout
10' metal downspout
wall labor
Rain Garden
plants
sand
soil (2' depth )
perimeter edging
garden labor with gravel evacuation
rain barrel
Maintenance for 10 years
labor
vandalism damage repair/ event
TOTAL
Quantity
Cost
3
1
$2.50
$1,600.00
1
1
1
1
7
20
1
1
1
2
$12.00
$105.00
$13.00
$230.00
$35.00
$140.00
$640.00
$500.00
$125.00
$300.00
143
140
140
1
10
1
$1,001.00
$280.00
$560.00
$840.00
$1,000.00
$75.00
20
5
$2,000.00
$1,500.00
$10,958.50
As mention in the designs, the green wall is 10ft by 8ft by 2ft. Most of the labor will come from
volunteers, but we have budgeted for professional help with disconnecting the downspout,
attaching a new downspout and mounting the green wall to the building securely. Capital costs
for the rain garden are listed in the table. The garden is 7 feet by 20 feet. Costs were priced
based on local hardware stores.
Operations and maintenance would be minimal for this green infrastructure system.
Maintenance would include weeding, pruning and cleanup of potential vandalism to the
system. Pruning and weeding could be a student group activity, class or other volunteers. Other
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costs would include making sure leaves do not block the top of the holes for the green wall and
periodic inspection to make sure the green wall is properly attached to the wall and structurally
sound. The costs would come to labor costs for structural support maintenance, weeding if no
student group does this and potential vandalism clean up. The system should last for 10 years if
maintained properly.
Compared to the current system, our system would produce water savings and cost savings.
Furthermore, reducing storm water runoff or harvesting rainfall reduces the energy
consumption of water utilities for conveyance and treatment. Using green infrastructure
reduces in flood risk, treatment costs, and the need for grey infrastructure. Infiltration projects
can reduce energy required for pumping by raising groundwater levels. Green infrastructure
can help improve air quality. An EPA study estimates health benefits including fewer premature
deaths and cases of chronic bronchitis, of reduced NO2 emissions at $1680 to $6380 per Mg in
2006 (Clark et al., 2008). This would also increase property value. A review of the literature
suggests a 20% guideline for increased property value for those properties fronting or abutting
a park (Crompton, 2005). Industrial buildings with large blank walls could benefit from installing
a green wall – rain garden system.
Potential funding for this project could come from a variety of sources, as they can range from
large government entities to local trusts. The WDNR has a grant program and the local
Metropolitan Sewage District has incentives for green infrastructure. A local watershed
organization has a mini-grant program for projects up to $5,000. Additional local funding
sources include local foundations that support water quality work. The university’s
sustainability director may provide matching funds as well.
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References
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