Watering Solutions for The University of Toledo
Outdoor Classroom Garden
Submitted By
Ryan McChesney, Pavan Penumalla, Bhavya Paruchuri, and S. Amir Mohaghegh Motlagh
Submitted To
Professor Defne Apul
For
CIVE6900
Sustainability in Engineering and Science
Fall 2009
Fall Semester 2009
November 20, 2009
Abstract
With the depletion of natural resources, sustainability has been the major concept that has been
revolving around the world. In this context, The University of Toledo has started a new outdoor garden
classroom as part of its progress towards sustainability. Our task, as a class, was to find a way to get
water to this garden in a sustainable manner.
Our intent was to use natural ways to water the garden. We have evaluated five different design
solutions for watering based on the cost, feasibility and usage of unsustainable products. We have taken
into consideration the life cycle analysis and compared different methods based on the emission of
greenhouse gases and energy. For the life cycle assessment, we considered the manufacturing and the
operational stages of the designed system.
We have come up with a design to use rain water and eliminate the usage of potable water. We will
collect rainwater from the University of Toledo Law Center and use a purely gravity fed system of
piping to collect water in a tank located near the garden. From the tank we will use a battery powered
automated valve to control the water flow to the flexible tubing drip irrigation system.
We have come up with a solution to reduce the utilization of manufactured products and minimized the
use of energy in our system. We have looked at all the options that we could think of to fix the water
problem for the garden and will recommend, upon approval from the University, the construction of this
watering system.
From our calculations, using a life cycle assessment tool, we have arrived at a conclusion that the global
warming potential emissions and energy consumption of the rainwater harvesting system remained the
same throughout its lifespan because of negligible operation phase emissions. In comparison, for the
current system, the global warming potential emissions and energy consumption increase at a linear rate
throughout its lifespan.
We estimate that the rainwater harvesting system will cost approximately $15,000. This is a costly
system but we feel it is worth the investment since it will serve as an educational display for all ages. It
also will over time be more cost effective and more environmentally friendly. We feel our proposed
rainwater based system is the best option for solving the water problem for The University of Toledo
Outdoor Garden Classroom.
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Table of Contents
1. Introduction ............................................................................................................................................. 5
2. Problem Statement .................................................................................................................................. 6
3. Objective and Overview ......................................................................................................................... 7
4. Site Description ....................................................................................................................................... 7
4.1. Soil Type and Characteristics ........................................................................................................... 7
4.2. Topography of the Site ..................................................................................................................... 8
4.3. Water Demand.................................................................................................................................. 9
4.4. Current Watering System ................................................................................................................. 9
4.4.1.
Cost for Water ..................................................................................................................... 11
4.4.2.
Cost for Gas ........................................................................................................................ 11
5. Alternative Designs Considered for Watering the Garden ................................................................... 11
5.1.
Excavate a Well .......................................................................................................................... 12
5.1.1.
Approach ............................................................................................................................. 12
5.1.2.
Discussion ........................................................................................................................... 12
5.2.
Draw Water from Ottawa River ................................................................................................. 13
5.3.
Make Use of the Existing Fire Hydrants .................................................................................... 14
5.4.
Erect a Storage Tank Above the Ground ................................................................................... 15
5.5.
Rainwater Harvesting System .................................................................................................... 16
5.6.
Summary of Selected Method .................................................................................................... 19
6. Design of Selected Method ................................................................................................................... 20
6.1.
Description of Rainwater System ............................................................................................... 20
6.2.
Tank Sizing ................................................................................................................................ 21
6.3.
Irrigation ..................................................................................................................................... 22
7. Life Cycle Assessment of Base Scenario and Rainwater Harvesting Systems .................................... 23
7.1.
EIOLCA for Base Case Scenario ............................................................................................... 23
7.2.
EIOLCA for Rainwater Harvesting System ............................................................................... 24
7.3.
Inventory for Base Case and Rainwater Harvesting Scenarios .................................................. 25
8. Comparison of Current System to Rainwater Design Scenario ............................................................ 25
8.1. Cost Comparison ............................................................................................................................ 25
8.2. CO2 Comparison ............................................................................................................................ 25
8.3. Energy Comparison ........................................................................................................................ 26
9. Conclusions ........................................................................................................................................... 27
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9.1. Future Work ................................................................................................................................... 27
9.2. Other Photos of the Project ............................................................................................................ 29
10. Acknowledgements ............................................................................................................................. 31
11. References ........................................................................................................................................... 32
12. Appendices .......................................................................................................................................... 33
12.1. Handwritten Rainwater Calculations ........................................................................................... 33
12.2. EIOLCA Detailed Spreadsheets ................................................................................................... 35
12.3. Additional Information for Client ................................................................................................ 36
12.4. Irrigation System Product Cutsheets ............................................................................................ 38
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1. Introduction
“Sustainable development is the development that meets the needs of the present without compromising
the ability of future generations to meet their own needs,” stated by Gro Harlem Brundtland in the
Brundtland Commission formally the World Commission on Environment and Development (WCED).
The University of Toledo has adopted sustainability in almost every aspect including energy, buildings,
food, and transportation. According to “The College Sustainability Report Card 2010”, UT has achieved
a C+ Sustainability rating. UT is helping to improve the human condition, as stated in their purpose
statement. On Earth Day, UT’s departments of Women’s and Gender Studies, Environmental Sciences,
Public Health and Human Service and the Honors Program as well as campus organizations such as the
Urban Affairs Center and community organizations, including Toledo Grows collaboratively broke the
ground for the Outdoor Garden Classroom.
UT Outdoor Classroom Garden is located on West Towerview Blvd.; adjacent to the Law Center (Figure
1). The size of the garden is 117' X 56'. The professors and students have come together to set up the
garden to foster lively discussions about sustainable agriculture and its impact on environmental health
and human wellness (Independent Collegian, 20 April, 2009). This educational venue is designed so that
the environmental sciences as well as the humanities can use the space to teach sustainable agricultural
practices; the arts will be able to use the area to derive inspiration as grounds to showcase their work
while those in pharmacy can grow plants with medicinal applications (Independent Collegian, 12
February, 2009).
Figure 1: Location of the garden in The University of Toledo Main Campus Map
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Source: Virtual Tours and Directions; University of Toledo (www.utoledo.edu)
Many departments have incorporated the garden into their classes. In fall 2009, the following courses on
UT campus used the garden as part of the learning experience: Plants and Society, Environmental
Problems Laboratory, Biodiversity Lab, Agroecology, Sustainability Science and Engineering, Plant
Physiological Ecology, Women and the Environment, and Advanced Topics, Ecofeminism.
The garden has the following plants in it: Agastache, Angelica, Basil, Borage, Hyssop, Cosmos,
Ipomopsis, Marigolds, Nasturtium, Salvia, and Sun Flower. The garden also produces vegetables
including tomatoes, purple cabbage, corn, broccoli, squash, hale, beans. Figure 2 shows the layout of the
different plants in the garden. This “locally-grown” produce would lessen Aramark’s (food services of
UT) dependence on shipping its food from distant farms and thus cut down on the amount of carbon
dioxide being released into the atmosphere from the use of fossil fuels. Thus the garden serves as an
application to decrease UT's carbon footprint. Volunteers, TAs and a few professors were involved in
watering the plants of the garden in summer 2009. Due to the winter months in Ohio, the garden needs
to be watered for approximately 7 months in a year; cover/catch crops are grown in the remaining 5
months to build the garden soil (Winter Cover Crops Build Garden Soils, July 28 2009, Ohio State
University Extension).
Figure 2: Design of the garden
Source: UT Outdoor Garden Classroom ( http://www.utoledo.edu/as/garden/design.html )
2. Problem Statement
The UT Outdoor Garden Classroom is a representation of University of Toledo's contribution to
sustainability. Initially, the garden was watered through a hosepipe using water from the fire hydrant
nearby. About a month later a sprinkler system was installed. After a few months, the fire hydrant was
broken and it will cost the University approximately $6,500 to fix the hydrant. After the hydrant was
broken, the grounds department at UT supported the watering of the garden by providing the
coordinating team with a trailer of water (approximately 500 gallons of water) twice a week. It is placed
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adjacent to the garden and thus ruins the aesthetic appearance of the garden. The system uses a Honda
GX140 pump to supply water to the sprinkler system. The pump consumes about half gallon of gas to
supply every 500 gallons of water to the sprinkler system. Later, the volunteers had a problem
coordinating with the arrival timings of the trailer. Sometimes, the trailer would never turn up leaving
the garden without water for a few days. In addition to the trailer problem, the current sprinkler system
over-sprays the plants and therefore results in an inefficient use of water. This shows that the water was
not obtained and used systematically; hence this demands a better solution to the problem.
3. Objective and Overview
Our goal was to explore various designs and provide the university with the most sustainable and
efficient option to irrigate the garden. Towards this objective, we developed 5 different alternatives to
water the garden. A lifecycle assessment guided us in adopting an alternative with minimum CO2
emissions and minimum energy consumption. Depending upon cost, feasibility, sustainability criteria we
have decided to opt for a rainwater harvesting system as the most efficient alternative. Our study showed
that the best option was to supply water to the garden by installing a rainwater harvesting system by
collecting rainwater from the roof of the law center building and storing them in a 5000 gallons tank
adjacent to the garden. The water from the storage tank will reach the irrigation system under gravity.
Our system will involve no pump in water distribution. The irrigation system to be used is a drip
irrigation system that is 90% more energy and water efficient compared to any other irrigation system.
Hence, the system that we suggest has no fuel combustion involved once it is in place, therefore it is
energy efficient; it uses rainwater and drip irrigation system for irrigating the garden, therefore it is
water efficient as well.
4. Site Description
4.1. Soil Type and Characteristics
The soil on the garden site is a mix of two different soil types. The following information was
taken out of the Lucas County Soil Survey book from the United States Department of
Agriculture (USDA, 1979). The two soil types are symbols Ee and StB. Symbol Ee stands for
Eel loam, occasionally flooded. Symbol StB stands for Spinks fine sand, 2 to 6 percent slopes.
The main soil type at the garden is Ee, the StB is sandier soil that is mostly located north of the
garden as you go up the slope towards the houses.
The soil horizon breakdown for the two different soil types is as follows. Ee is loam from 0 to 9
feet; silt loam, loam from 9 to 33 feet; and stratified sandy loam to silty clay loam from 33 to 60
feet. StB is fine sand, loamy fine sand from 0 to 6 feet and stratified fine sand to loamy fine sand
from 6 to 84 feet.
Given this information, the main soil on the site is mostly loam. Because of this the soil makes it
hard for the water to move throughout the soil. This means that the permeability of the soil is low
on the site.
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4.2. Topography of the Site
Figure 3 is a CAD drawing with spot elevations of the garden that was developed with the help
of Bryan Ellis, PE, PS. This was done using GPS equipment that the Civil Engineering
department has recently purchased. The GPS equipment used was manufactured by Trimble.
Two major components of the system are the base station and the rover. The rover was used to
collect the data as we walked around the site shooting our points. The rover receiver was a
Trimble 5800. This was the unit on top of the range pole we walked around with. This has a
receiver built into it that would receive GPS radio signals to establish a position. A Trimble
TSC2 data collector with windows CE software as an operating system was the handheld device
used to control the equipment. The base station used a zephyr antenna set at the base control
point. This also has a receiver built into it that would receive GPS radio signals to establish a
position of just the base control point. The base station also used the Trimble 5700 receiver radio
and a Trimble HPB450 transmitter to broadcast information from the base station to the rover
radio.
From our GPS information we found that the garden is at a higher elevation than the road and the
base of the law center. Figure 3 shows that the northwest corner of the garden is the highest point
of the garden. This is the best spot to place the storage tank because we are using a gravity fed
system and need the elevation difference to push the water through the irrigation system. We are
using a drip irrigation system so the natural flow of the water on the surface will go from the
northwest corner to the southeast corner, covering the entire garden. The elevation difference
between the northwest corner of the garden and the southeast corner of the garden is 4.47’.
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Figure 3: Auto CADD drawing with elevations of the garden.
4.3. Water Demand
Water demand is an estimate of the amount of water expected to be used by the consumers of the
system. From the current scenario the water demand was noted to be 4000 gal/month (since a
500 gallon trailer comes twice every week to water the garden). Calculations done with the help
of Dr. Scott Heckathorn gave us a water demand of 4502.12 gal/month (personal conversation,
October 1st, 2009). Using the standard guide for non-residential water demand, the water demand
was estimated to be 4000 gal/month (Texas water development board, 2005). Comparing both
the water demands to the standard guide for non-residential water demand, the average demand
for the garden was taken to be 4500 gal/month accordingly the rainwater tank was designed.
4.4. Current Watering System
The watering system that is currently working consists of a water trailer, a water pump and five
sprinkler heads to distribute the water for the plants. The trailer holds 500 gallons of water and it
should be refilled twice every week. The pump currently in use is a Honda GX140 with 5 HP
powers, a 4-stroke engine that consumes 3.7 kWh (Figure 4 and 5). It uses about half of the
engine oil capacity (0.6 quarts = 0.15 gallon) to water 500 gallons of water. The pump on the
trailer does not have sufficient power to run for the whole watering system and it can just run for
the half of the sprinklers at a time; so it takes about an hour to water the whole garden. The
current sprinkler system (Figure 6) over-sprays the plants and therefore results in an inefficient
use of water.
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Figure 4: Pump used by the trailer at the garden
Figure 5: Pump Specifications
Source: (ebay.com)
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Figure 6: Sprinkler Head of the irrigation system
4.4.1. Cost for Water
On an average, in the United States, tap water costs are slightly more than $1.4 per
1000 gallons. In the city of Toledo, rate of water per 1,000 Cubic Feet is $ 10.74
($1.436 per 1,000 Gallon) (http://ci.toledo.oh.us, 2009). The grounds department said
that it would cost $25 for every trip taken with water to the garden (Mike Rippel,
personal communication, September 30th, 2009).
4.4.2. Cost for Gas
We assume $2.6 per gallon of gas for the pump consumption. The pump uses about
0.15 gallon per week (0.6 gallon per month), so the cost for gas will be about $1.56
per month. Therefore, if we assume that we need water and gas for 7 months in a
year, for the current system the total cost for water and gas in a year will be:
(7*4*1.436) + (7*25*2*4) + (7*0.6*2.6) = $ 1,452
5. Alternative Designs Considered for Watering the Garden
Five different design alternatives were considered for solving the water problem at the garden. The
solutions considered were:
1. Excavate a well
2. Draw water from Ottawa River
3. Make use of the Fire Hydrant
4. Erect a storage tank above the ground
5. Rainwater harvesting system
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5.1. Excavate a Well
5.1.1. Approach
One of the options we considered for watering the outdoor classroom garden was to
dig a well near the garden, pump up the groundwater and use it for watering. This
would be a simple, small diameter well with a submersible pump to push the water to
the surface. From here the water would be stored in the above ground tank until the
water is needed. It would then be dispersed through the irrigation system to the
garden.
5.1.2. Discussion
We encountered many problems with the idea of using a well to water the garden.
First of all we found that the University of Toledo’s campus is over a valley of
bedrock; so to dig a well it would have to go down about 100' to bedrock and then go
about 10-20' additional to get to where we can get enough water. The reason we
would have to drill down to bedrock, as this is not always necessary when extracting
groundwater, is that the soil on campus is clayey soil with low permeability. This is
not an ideal soil to catch pockets of ground water because the water cannot flow
freely through the soil. There is a small chance to hit a permeable pocket of sand
when drilling but it would take weeks to fill with water because of the small size. For
this reason, if we did a well we would need to go into bedrock where the water is
contained.
Another issue we would have with the well option would be contaminants in the
water. Because of anoxic conditions, there could possibly be high concentrations of
hydrogen sulfide in the water. This would not be good to put on the vegetables and
other plants in the garden. This is how the university currently waters the lawns
around campus. They have a well that they pump the water from. Because of the
hydrogen sulfide in the water, it makes the water smell bad and this would be a
distraction to visitors to the garden and also wildlife. This gas can also corrode the
piping and turn the water to a black color.
The price for drilling a well and for the pump, tank, and irrigation system was an
initial concern for this option. Since this was a major factor, we made sure we got a
quote of how much it would cost. We called Kimball Well Drilling out of Genoa,
Ohio to get our quote (personal communication, October 22, 2009). The cost to drill
is $21 per foot plus $400 for a pressure seal, and around $1,800 for 12 gallons a
minute pump. So if we were to go 130 ft. and hit water on the first drill, the cost of
the well and pump would be $4,930, if not the price could increase. Additional costs
to complete the system are the tank, $1,595, and irrigation system, $2,200 for
materials and $2,000 for labor. Since the water contains hydrogen sulfide, we would
need a filtration system to purify the water for the garden. According to Crystal Quest
(Crystal Quest, 1997), this system would cost approximately $1,095 plus installation;
including pipe and labor it would cost approximately $1,300. With all of these costs,
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the lowest possible cost of this alternative would be $12,025. The high cost along
with the quality of the water makes this system very expensive and not feasible. With
this option, there would also be operating costs involved. Filters for the filtrations
system, maintenance to the pump would all have to be taken into account.
5.2. Draw Water from Ottawa River
The other option for watering the garden is by using the nearby river. The river is located on the
south bound of the garden approx 1150 ft from the garden (Figure 7). By using a pump the water
can be pumped up and transported to the destination. In this case we need a high efficiency pump
as we need to transport the water for 1150 ft. Also, for water to travel 1150ft before reaching its
final destination would involve lot of frictional losses. Moreover, the river is located at a lower
elevation compared to the elevation of the garden.
This is going to involve high performance components that produce more emissions. Thinking in
a sustainable manner 1150 ft PVC pipe (construction phase) and a high performance pump
(construction phase & operation phase) are going to involve very high percentage of global
warming emissions.
In summer the water level can be really low and also considering the drought phase the water
may need to be pumped well ahead; hence a tank to store this water would be mandatory. The
tank would involve some construction phase emissions. Moreover 1150 ft is an estimate of direct
path. Hence, the option has been eliminated.
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Figure 7: Aerial view of the path of water supply from Ottawa River to the Garden
Source: (Google Earth)
5.3. Make Use of the Existing Fire Hydrants
One of the alternatives that we have is using fire hydrant as a watering system. There are two fire
hydrants around the garden. A few months ago, they watered the garden with hoses from one of
the fire hydrants but it took about an hour or more each time for watering. About one month later
they got a sprinkler system installed. Later, one of the volunteers broke the fire hydrant (Figure
8), water spilled underground and we estimated that it will cost several thousands to fix it.
To fix the broken hydrant a Class-A (1000-1400 gpm) fire hydrant is needed. A good quality
hydrant costs less than $1,000. But we have to budget a complete installation (tee, street valve,
lateral, bury, extension and hydrant body, properly bedded trench, contractor's labor) at $3,500
during construction when there is no existing pavement to remove and replace and trenching
equipment is already in place. It will cost $6,500 when streets, sidewalks, etc. have to be opened
up and then replaced (firehydrant.org, 2009).
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Figure 8: Broken fire hydrant at the garden
Besides the cost issue that we have, there are regulations for using the fire hydrant. Fire hydrants
are usually associated with the fire department because fighting fires is the major purpose of a
hydrant. The need to keep them well maintained for quick and reliable service when needed is
paramount. A hydrant that does not operate when needed can result in serious loss of life and
property.
Frequent uses for fire hydrants include: flushing and cleaning water mains, flushing sewers,
filling tank truck for street washing, tree spraying, winter watering and providing
a temporary water sources for construction jobs, such as for mixing mortar and settling dust. Any
use of hydrants by non-utility employees is restricted and it requires a permit from the water
department and the water leaving the hydrant must be metered and paid for (greeleygov.com,
2009).
In summary, making use of the fire hydrant for watering the garden has 2 problems that should
be considered:
-
Fixing cost of the hydrant
Restricted use by non-utility employees
5.4. Erect a Storage Tank Above the Ground
One other alternative we have considered for watering the garden is by placing a storage tank
adjacent to the garden. In this method, the water will be supplied by the grounds department as it
did in the current system but this water would be transferred to the storage tank.
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The water is stored in the tank and then used for irrigation purpose. Tanks are of different types:
fiber glass, metal, water wall, little metal tank and polyethylene. In this scenario we have
adopted a polyethylene tank as it is cost effective, durable and easily transportable.
The issues with this method are once the tank has been placed at site; the grounds department has
to supply water once it gets close to empty. It is not sustainable because it would require a lot of
potable water. It is also not very feasible for the grounds department to supply water to the
garden indefinitely. The water is supplied to the garden with the help of a trailer, therefore
involves transportation emissions. Also, for the production of the tank it involves certain amount
of global warming emissions. Considering the above issues, this option has been eliminated.
5.5. Rainwater Harvesting System
To complete the rainwater harvesting option, there are many details that need to be examined
carefully. This option is a simple, yet a complicated demonstration of head pressure and the use
of gravity.
A typical rainwater collection system consists of the following:
- A collection area (usually the roof)
- A method of conveying the water (gutters, downspouts, and piping)
- A filtering device
- A storage tank or cistern
- A system to distribute the water as needed
If we could put a little effort in collecting the run-off rain waters from the roof instead of letting
them run straight into the sewer, we could save a lot of water to water our houseplants, gardens
and lawns for free. Storage of rainwater is required to regulate the non-uniformly distributed
characteristics of water (Su et al., 2009). The efficiency of the rainwater harvesting system is
affected by two factors; distribution patterns of rainfall and that of water demands (Zhang & Cai,
2003; Wei et al., 2005).
The suggested option will collect rainwater from the north side of the University of Toledo Law
Center. According to our measurements from our CAD drawing, the roof area is approximately
2,400 square feet and has an exterior gutter system and drains into three downspouts. We would
join the three downspouts together at the base of the building below the frost line and then start
running 4” PVC pipe north towards the garden. Sidewalks will need to be torn up to get the pipe
below and then concrete will be poured to replace the sidewalk.
When the pipe gets to the road, there is a larger problem. To get the pipe under the road would be
an enormous cost that would not be feasible for this project. The other option is to go over the
road with the pipe. We would elbow up and over the road laying the pipe on the road surface.
Because of the stresses that would be put on the pipe by the motor vehicles passing over the road
we would have to make it a metal pipe and cover it with a speed bump application to keep the
vehicles from bottoming out. To get this accomplished we would have to run it by the university
to make sure it is acceptable to do that.
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Once the pipe gets over the road it would elbow back down to below the frost line and then
continue towards the garden. After one more elbow it would go behind the garden and head to
the 5,000 gallon tank. The total length of the pipe is going to be approximately 500 feet.
In figure 9 is a drawing of the site with the red lines being the 4” PVC pipe and the red circle
being out 5,000 gallon storage tank.
Figure 9: Path of water supply from the roof of the Law Center to the tank at the Garden
The tank is the most important component of the system; it is the most expensive and the most
permanent component of the system as well. Tanks can be made of different materials. Different
types of rain water harvesting tanks are: fiberglass tanks, polyethylene tanks, in-ground
polyethylene tanks, wooden tanks, metal tanks, concrete tanks, stone and mason tanks, and
plastered tire cistern. Tanks that store water for potable use should have a USDA – approved
food-grade resin lining and the tank should be opaque to inhibit algae growth.
Polyethylene tanks are the most common tanks available in market today. They are available in
different sizes, shapes, and colors. They are inexpensive, lightweight and long-lasting as well
when compared to other types of tanks. Tanks can be placed above and below the ground
depending upon soil, outside temperature ranges, cost and aesthetics. In-ground, polyethylene
tanks are used if the tank is buried more than 2 ft. deep. This is an expensive option considering
the cost of excavation and cost of a more heavily reinforced tank. Table 1 summarizes the
advantages and disadvantages of tanks of different materials. After skimming through the table,
we observed that the advantages of a polyethylene tank supersede its disadvantages. Hence, we
have decided to opt for a polyethylene tank for storage of rainwater. Figure 10 shows the image
of high-capacity polyethylene tanks. For an aesthetic appeal, wooden tank made of redwood
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(contains no resins and has high levels of tannin, a natural preservative resistant to insects and
decay, a good insulator, keeping the water cooler in the summer and protects it from freezing the
winter) would be a desirable option ( Doug Pushard, Rainwater Harvesting: Comparing Storage
Solutions , November 2009). Figure 11 shows the image of a wooden tank.
Figure 10: High-capacity polyethylene tanks
Figure 11: Wooden tanks
Source: Rainwater Harvesting: Comparing Storage Solutions
Table 1: Summary showing the feasibility of tanks of different materials
Fiberglass
polyethylene
Below Ground
polyethylene
Cement
Ferrocement
Plastered Tires
Stone
Wood
--Low/No
++
+++
Expected
Maintenance
---
Build Your
Own
-----
++
+++
--
---
+
+
-
--------++
++
++
++
+
+
+
++
++
+
-
Expected Life
Availability
Transportability
++
++
++
+++
+++
++
++
+++
+++
+
+ High/Yes
Figure 12 is a basic sketch of the system and how it will be set up. This gives a section view of
the system, illustrating the elevation difference, the elbow up and over the road, and how the
water will sit in the system. The rainwater system is purely based on gravity. The elevation
difference between the top of the gutter and the top of the tank is 14.59 feet. As shown by the
calculations attached in the appendix, given a maximum velocity of 2.8 fps going into the gutter,
the output of water into the tank velocity is 4.57 fps. This is taking into account the loss of
velocity in the pipe due to friction, bends and material type.
Once the pipes are full from the gutters to the tank, the water will slowly begin to push the water
into the tank as the water in the downspouts increase. There will always be water standing in the
downspouts due to the elevation difference between the tank and the downspouts. This will
require making sure that the downspouts will not leak. It is important that the whole system is
leak proof. If the system were to leak, we would lose all of our water in the storage tank. To
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prevent this from happening in case of a leak, a standpipe would be placed vertically in the
middle of the tank. This would keep the water from draining in the tank.
Another concern was what would happen in the winter with the system. Because of the cold
weather conditions in Toledo, we would have to completely drain the tank and the pipes in the
winter months. The pipes that are going over the road would have to be disconnected and drained
completely. To do this a hose could be run from the tank to the storm sewer grate. The 4” PVC
lines should be drained using a compressed air system or by building in a valve that would drain
the pipes to a catch basin around the garden.
Overflow really is not much of a concern but must be taken into consideration. Since we did our
calculations to a 5 year storm, there aren’t going to be many rains that will produce much more
rain than what we designed for. The calculations show that the water will drain into the tank
faster than it can come into the gutters. But if the tank does fill up and it is still raining hard, an
overflow downspout could be placed on the gutter.
Figure 12: Basic sketch of the piping system.
5.6. Summary of Selected Method
Table 2 shows the different methods evaluated along with the advantages and disadvantages
which were discussed earlier in this paper. As you can see there are positives and negatives for
each option however we have selected rainwater harvesting system as the most appropriate
option.
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Table 2: Summary of evaluated watering methods
Design Solution
Advantages
Current system
Cheapest
Excavate a well
Short distance to garden
Draw water from river
Water availability throughout
the year
Storage tank about ground
Water stored in tank
Fire hydrant
No need to pump
Rain water Harvesting
Educational demonstration,
no energy use, not labor
intensive, most sustainable
option
Disadvantages
Potable water, Manual
watering, depend on grounds
crew
Usage of pump, hydrogen
sulfide, cost
Usage of high efficient pump,
PVC pipes, long distance,
cost
Usage of potable water,
hauling water to tank, labor
intensive
Restriction use by non-utility
employees
Cost, getting pipe over road
Conclusion
Eliminated
Eliminated
Eliminated
Eliminated
Eliminated
Chosen
6. Design of Selected Method
6.1. Description of Rainwater System
As discussed previously, we have selected the rainwater harvesting from the University of Toledo Law
Center as the preferred method to water the garden. This system (Figure 13) will cover quite some
distance and will have many details that need to be carefully examined. The system starts with the
collection of rainwater from the north side of Law Center into three downspouts. The rainwater will then
travel down the watertight downspouts and all tie together at the base of the building. After they tie
together, the 4” PVC pipe will tee out and head towards the garden at an elevation approximately three
feet below the surface, depending on other utility locations underground. The pipe will travel across
sidewalks necessitating tearing up and replacing sidewalks to place the pipe underneath of them.
When the pipe gets to the road, it will have to elbow up and over the road and then back down. To get
over the road we will need to switch to metal pipe and place a speed bump application over top of the
pipe. This will prevent the pipe from crushing and still allow the water to flow to the garden. This is the
cheapest alternative we could find to get across the road.
After the piping gets across the road, it will go along side of the garden and then elbow over heading
towards the tank. Once it arrives at the tank it will have an inlet pipe which will go into the middle of the
tank and then elbow up until the pipe nearly reaches the top of the tank. This acts to prevent backflow.
The system relies on the force of gravity to feed the water all the way through the pipes. Once the water
is in the tank, the irrigation system, which is described in the following sections, will distribute the water
to the plants in the garden.
Page | 20
Figure 13: View of the site with the roof area, piping, garden, and tank location shown
Source: (maps.msn.com)
6.2. Tank Sizing
We used the information shown in Table 3 and Table 4 to size our tank for our rainwater system.
This information came from an excel spreadsheet taken from the Texas Rainwater Guide (Texas
water development board, 2005). This spreadsheet allowed us to input our roof area, water
demand, average rainfall for Toledo, and a guess on our tank size and it would populate the rest
of the fields in Table 3. This allowed us to see how much water would be in the tank at the end
of each month.
Since these tables were developed for use in Texas, we needed to take into consideration the
climate differences. Since we do not want our system to freeze up in the winter months, our
system will be drained and we will not be collecting rainwater. Also we will only be watering for
at the most eight months out of the year so water will not be used during the other months. Given
the below information, a tank of 5,000 gallons has been chosen.
Page | 21
Table 3: System Sizing Calculator
Raw Data
Catchment Area (sq. ft.)
Monthly Indoor Demand (gal)
Outdoor Demand (gal)
Water in Storage to Begin (gal)
Tank Size (gal)
2,400
0
4,000
1,000
5,000
Table 4: Tank sizing Chart
January
February
March
April
May
June
July
August
September
October
November
December
Indoor
demand
Irrigation
(gal)
Total
demand
(gal)
Average
rainfall
(in/mon)
Collection
surface size
(Sqft)
Gallons/ft2
collection
coefficient
Efficiency
factor
Rainfall
collected
(85%
efficiency)
End of
month
storage
(gal)
0
0
0
0
0
0
0
0
0
0
0
0
0.0
0.0
0.0
4000.0
4000.0
4000.0
4000.0
4000.0
4000.0
4000.0
0.0
0.0
0
0
0
4,000
4,000
4,000
4,000
4,000
4,000
4,000
0
0
0.00
0.00
0.00
3.24
3.14
3.80
2.80
3.19
2.84
2.35
0.00
0.00
2,400
2,400
2,400
2,400
2,400
2,400
2,400
2,400
2,400
2,400
2,400
2,400
0.62
0.62
0.62
0.62
0.62
0.62
0.62
0.62
0.62
0.62
0.62
0.62
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0
0
0
4,098
3,971
4,806
3,541
4,035
3,592
2,972
0
0
0
0
1,000
1,098
1,069
1,876
1,417
1,452
1,044
16
0
0
6.3. Irrigation
We have opted to use a Drip irrigation system for water distribution to the garden. We did this so
we could efficiently use the water we have stored in out tank. Our proposed system consists of
two products from Netafim. The first is an AuquPro smart valve watering controller. It is battery
operated and has three different programmable options. Option 1 is having one watering session
at the same time every day, option 2 is watering once a day on selected days, and option 3 is
having up to three sessions per day on selected days. So this control valve will give us flexibility
on when we want to water the garden. It also allows the convenience of not having to be present
when the watering is being done.
The second part of the system is a TechNet 120 pressure compensating, continuously selfcleaning dripping system. This is flexible tubing that can adapt to any planting area and the
installation is fast and inexpensive. This lets a precise and equal amounts of water be delivered
Page | 22
over a broad pressure range at different flow rates. There are a broad range of flow rates
available, 1.0 liter/hr, 1.6 liters/hr, and 2.0 liters/hr. This tubing is compatible with the control
valve we chose and is the best option for our application.
a. Advantages of Drip Irrigation
Drip irrigation is one of the most efficient methods of irrigation as it minimizes
evaporation and impedes weed growth. The flexibility of the system is also a major
advantage which allows for easy and fast installation.
UV water purification is superior means to purify water for rainwater harvesting systems
by destroying all types of bacteria and disinfects without use of heat or chemically
additives. But for our requirement, UV purifiers are not necessary (John Mone,
Everything You Need to Know about Ultraviolet Water Purification, November 2009).
7. Life Cycle Assessment of Base Scenario and Rainwater Harvesting Systems
The Economic Input-Output Life Cycle Assessment (EIO-LCA) method estimates the materials and
energy resources required for, and the environmental emissions resulting from, activities in our
economy. Results of LCAs can be useful for identifying areas with high environmental impact, and for
evaluating and improving product designs (Economic Input-Output Life cycle Assessment, 17
November 2009). We have used the US 1997 Industry Benchmark Model – producer price method
contributed by Green Design Institute. The model used the monetary dollar unit value of the year 1997.
The 2009 cost of all products have been converted to 1997 costs to comply with the 1997 Benchmark
Model. It had 491 sectors and was last updated on 4 July 2007. Following are the steps involved in
running the model:
- We first choose a desired model; in our case we chose US 1997 Industry Benchmark Model –
producer price
- Then we select the industry and sector
- We then provide the amount of economic activity for the respective sector in dollars
- The category of impact is chosen before running the model.
- From the output, we took a note of the Global Warming Potential measured in MTCO2E (Metric
Tons Carbon Dioxide Equivalent) and Total energy consumption measured in TJ (Terajoule)
values in the ‘total for all sectors’ row.
7.1. EIOLCA for Base Case Scenario
We separated the EIOLCA for each alternative into two parts; construction phase and operation
phase. The total cost of each component used in the construction and operation phases is entered
into the method and run to find the GWP emissions and energy consumption. The resulting
values are entered into the Table 5. The detail version of the output is in the appendix.
Page | 23
Table 5: Emissions and energy consumption values of base case scenario
Phase
Sector
#
336212
33291
Pump and pumping
equipment manufacturing
Plastics pipe, fittings, and
profile shapes
Truck trailer manufacturing
Metal valve manufacturing
484000
Truck transportation
221200
Natural gas distribution
Water, sewage and other
systems
333911
Construction
Operation
Sector Name
326120
221300
Emissions
Materials
required
MTCO2E
TJ
Pump
0.281
0.003
Pipe
2.4
0.032
Trailer
Sprinkler
Transporting
potable water
Gas
1.01
0.01984
0.011
0.0002625
2.22
0.018
0.018
0
Water
0.235
0
6.18384
0.064263
Total
7.2. EIOLCA for Rainwater Harvesting System
The cost of each component was entered into the system to get the emission and energy
consumption values. The output of the calculations was compiled in table 6. The detail version of
the output is in the appendix.
Table 6: Emissions and energy consumption values of rainwater harvesting system
Phase
Sector Name
326120
Plastics pipe, fittings, and
profile shapes
325212
Total
Materials required
MTCO2E
TJ
4" PVC pipe including
trenching and installation
7.77
0.103
Synthetic rubber
manufacturing
5000 Ga Polyethylene Storage
Tank including delivery
2.97
0.045
333111
Farm machinery and
equipment manufacturing
Drip Irrigation System
2.61
331210
Iron, steel pipe and tube
from purchased steel
# 3 Downspouts
1.35
0.015
0.00
0.000
14.7
0.193
Construction
Operation
Emissions
Sector
#
Negligible compared to the other approaches
0.030
Page | 24
7.3. Inventory for Base Case and Rainwater Harvesting Scenarios
The base case scenario i.e., the current system has pump, pipes, sprinkler heads, potable water,
gas in its inventory for which the model - EIOLCA was run (Table 5). Similarly, the rainwater
harvesting system has PVC pipe, 5000 gallons polyethylene tank, drip irrigation system,
downspouts in its inventory (Table 6).
8. Comparison of Current System to Rainwater Design Scenario
8.1. Cost Comparison
Table 7 shows the total cost of each component used in all the five alternatives broken down by
the different components. We could see that even though the initial cost of the rainwater
harvesting system is high, it will pay itself off as there are negligible operational costs involved.
It will be a system that will last a long time and will be worth the investment.
Table 7: Cost Comparison of the five alternatives chosen
Construction
Tank
Pump
Pipes
Potable water
Pressure seal
Drilling and
casing
Filtration
Hydrant
Hydrant
installation
PVC
Downspout
Getting across
the road
Irrigation
Miscellaneous
Total
Fire hydrant
Tank above the
ground
$1,595
$575
River
Well
$1,595
$1,800
$3,150
$1,595
$1,800
Rainwater Harvesting
System
$1,595
$2,400
$400
$2,730
$1,300
$1,000
$6,500
$7000
$1,000
$700
$4,200
$11,700
$4,200
$1500
$10,270
$4,200
$4000
$15,445
$700
$4,200
$12,025
$4,200
$200
$14,695
8.2. CO2 Comparison
Comparing Global Warming Potential (GWP) of CO2 emission shows that at first sight the total
CO2 emission of the baseline method is significantly lower than the rainwater alternative but if
the system runs for a long time, the CO2 emission in the graph below shows that the total CO2
emission of the baseline method is continuously increasing and in less than 5 years, it will be
higher than the rainwater method (Figure 14).
Page | 25
Figure 14: CO2 emission comparison
8.3. Energy Comparison
We have a similar story in total energy consumption. First look at the total energy usage
demonstrates that less energy is used in the baseline system but in a long term period (about 8
years); the rainwater method has lower total energy consumption (Figure 15).
Figure 15: Total energy use comparison
Page | 26
9. Conclusions
The goal of this study was to propose a sustainable method to water the University of Toledo Outdoor
Classroom Garden. We evaluated five options: excavate a well, draw water from Ottawa River, make
use of existing fire hydrants, erect a storage tank above ground, and a rainwater harvesting system. Of
these, we eliminated the first four options and concluded that the best solution for watering the garden is
the rainwater system that eliminates the usage of potable water. We will collect rainwater from the
University of Toledo Law Center and use a purely gravity fed system of piping to collect water in a tank
located near the garden. From the tank we will use a battery powered automated valve to control the
water flow to the flexible tubing drip irrigation system.
From our life cycle assessment study, we estimate that the initial CO2 emissions from using the
proposed rainwater system and the current system are 14.7 MTCO2E and 3.71 MTCO2E respectively.
While the initial CO2 emissions are higher for the proposed system, its life cycle emissions will be
lower. The current system releases 2.47 MTCO2E every year. After less than five years the proposed
system will emit less CO2 than the current system. Similarly, the initial energy requirement of the
proposed system is 0.19TJ while of the current system is 0.046TJ. The annual operation energy
requirements for proposed and current systems are negligible and 0.018TJ respectively. The energy
consumption for the operation phase of the proposed system is considered negligible because we have
assumed there will be very little energy needed to run the system. The proposed system will have
consumed less energy than the current system starting in approximately eight years.
We feel our proposed rainwater based system is the best option for solving the current water problem.
Given the university’s goal of becoming carbon neutral, the proposed rainwater harvesting system can
help obtain this goal.
This project has been a great learning experience and we hope that our work will help the committee
choose a solution for the watering problem at the University of Toledo Outdoor Classroom Garden.
9.1. Future Work
For this rainwater harvesting system to be completed there are still things that will need to be
looked at and followed up on.
A detailed application needs to be specified for the pipe going across the road. We think that this
may be able to be accomplished but have not found a specific solution. The pipe may have to be
reduced when crossing the road surface due to how high it would make the speed bump. The
University may also have a problem with this laying over top of the road.
As previously stated, the downspouts on the Law Center must be retrofitted to become
completely watertight. Water will always be sitting in the downspouts when the system is in use
because of the elevation differences in the outlet and the gutter of the Law Center. To seal them,
there may be a way to put a coating on the inside of the current downspout or new gutters may
need to be purchased. Longstanding water in the pipes may initiate and sustain biofilm growth.
More research is necessary to address this potential problem.
Page | 27
Filters will also need to be put onto the downspouts to filter out all of the large debris from
getting into our tank. We did not account for this in our system.
At the base of the Law Center the current downspouts are tied together. We are not sure exactly
how they are tied together or how many are tied together but this may be helpful in using what is
in existence to tie the three downspouts from our section of the roof together. The exact method
of tying these together will have to be determined before proceeding with construction.
As discussed in the paper, there will need to be some sort of gutter overflow application placed
on the Law Center. There is a small chance that the water will back up to that height but it is
possible. This could be done with a new downspout added that is on one end and is at a higher
elevation in the gutter itself so the water has to get up to a certain height before water entered the
overflow downspout. Alternatively, there could be an overflow hole or valve on the top of the
tank so that water just spills out by the tank before it can back up in the gutter.
The system will also need to be drained in some manner during the winter months. We have not
specified a specific way to do this but it will need to be looked at further. The entire pipe lying
on the road could be disconnected and removed for ease of use.
We are not certain that the water quality coming off the Law Center roof is acceptable for use on
the garden plants. We think that the roof shingles are slate and therefore are not toxic like asphalt
and should be acceptable.
Before any digging or trenching occurs, Ohio Utilities Protection Service (OUPS) must be called
to mark all important utilities in the area. The university also has CAD drawings that have these
locations on them that may be used for reference.
The City of Toledo may have certain laws and regulations concerning rainwater harvesting that
should be checked before starting construction on this system.
All of our work is dependent on the university’s approval. The University of Toledo would have
to go through the process of approving such work to be conducted on university property and
buildings.
All of these items must be addressed before this system is ready for construction.
Page | 28
9.2. Other Photos of the Project
Figure 16: Garden from the viewpoint of the tank
Figure 17: UT Law Center
Page | 29
Figure 18: Downspout at Law Center
Figure 19: Group members with Bryan Ellis performing GPS measurements
Page | 30
10. Acknowledgements
Scott A. Heckathorn - Associate Professor of Ecology, Department of Environmental Sciences,
The University of Toledo - We thank Scott Heckathorn who helped us out in calculating the water
demand for the garden.
Dave - T.A, UT outdoor classroom garden. Dave met with us to introduce us to the garden. He has been
extremely active in the maintenance and upkeep of the garden and his help and information was
extremely valuable.
Mike Rippel - UT Grounds Department, Toledo, Ohio: We thank the client for giving us an approximate
estimate of the cost charged for supplying water to The University of Toledo.
Marc Jobe - Landmarc Inc. Ida, Michigan. Marc was kind enough to come out to our garden site and
discuss the possible options we had at the beginning of the project. Marc then proceeded to provide us
with specific products to use for our irrigation system. He also gave us an estimate of the cost of that
system.
Dr. Nicholas Kissoff - UT Professor Department of Engineering Technology. Dr. Kissoff helped in the
conceptual evaluation of whether our system would work or not. He also assisted in performing the
calculations to show the system would work.
James Martin-Hayden - UT Professor Department of Environmental Services. Professor Martin-Hayden
was helpful in that he is a groundwater expert. He was very useful in providing information about the
soil type and determining if a well could be drilled or not on campus.
Bryan Ellis - Glass City Engineering and Services. Bryan was our resource for finding our elevations.
He took time out of his professional schedule to meet with us twice to capture all of our points of
elevations via GPS. He also then took all of the points and imported them into an Auto CADD drawing
for us to use.
Kimball Well Drilling - Genoa, Ohio. We would like to thank Kimball Well Drilling for providing us
with quote of a well. They were very friendly and helpful.
Chirjiv Anand - Graduate Student, Department of Civil Engineering, The University of Toledo. Chirjiv
helped us in using the excel spreadsheet taken from the Texas Rainwater Guide that we applied to size
the storage tank.
Stacy Philpott - Assistant Professor of Ecology, Department of Environmental Sciences, The University
of Toledo. She got us introduced to the garden. She is particularly active in maintaining the garden and
in taking good care of the garden.
Defne Apul - UT Professor Department of Civil Engineering. Our professor of this course played a
major role in the vision and guidance of this paper and project. We could not have done it without her.
Page | 31
11. References
“Ask FireHydrant.org” (2009). <http://www.firehydrant.org/info/faqs_ask3.html> (Last accessed Oct.
28, 2009).
Crystal Quest. (1997). “Iron and Hydrogen Sulfide Water Filter.”<http://www.crystalquest.com/Iron
%20and%20Hydrogen%20Sulfide%20Water%20Filter.htm> (Last accessed Nov. 12, 2009).
Doug Pushard, Rainwater Harvesting: Comparing Storage Solutions, November 2009
“A Primer on LCA, Economic Input-Output Life cycle Assessment” (2009). <http://www.eiolca.net/cgibin/dft/use.pl> (Last accessed Nov. 2, 2009).
HAMweather. (2007). “Climate for Toledo, Ohio.” <http://www.rssweather.com/climate/Ohio/Toledo/>
(Last accessed Oct. 27, 2009).
Lucas County, Ohio Soil Survey. 1979. USDA-SCS.
Murphy, J. D. (2009). “Means Construction Cost Index.” R.s. means Company, 67th edition.
“Saving water Outdoors, Southwest Florida, Water Management District.” (2009). <http://www.
swfwmd.state.fl.us/conservation/files/SavingWaterOut.pdf> (Last accessed Oct. 20, 2009).
Texas Rainwater Guide, Texas water development board, Chris Brown, Jan Gerston, Stephen Colley and
Dr. Hari j. Krishna; 2005.
“Water Distribution” <http://www.greeleygov.com/water/waterdistribution.aspx> (Last accessed Oct.
30, 2009).
“Water Rates” (2009). <http://www.ci.toledo.oh.us/Departments/PublicUtilities/
UtilitiesAdministration/Rates/tabid/351/Default.aspx> (Last accessed Nov. 5, 2009).
Water System Design Manual, August 2001; 5-15.
“Water Tanks” (2009). <http://www.watertanks.com/tnt-water-tanks> (Last accessed Oct. 23, 2009).
“Winter Cover Crops Build Garden Soils.” Ohio State University Extension. July 28 2009
< http://www.extension.org/pages/Winter_Cover_Crops_Build_Garden_Soils> (Last accessed Oct. 30,
2009).
Page | 32
12. Appendices
12.1. Handwritten Rainwater Calculations
Page | 33
Page | 34
Current System and Rainwater Harvesting Sytem EIOLCA Complete Output
12.2. EIOLCA Detailed Spreadsheets
Page | 35
12.3. Additional Information for Client
After our presentation to the client, an additional request was brought up regarding the amount of
catchment area needed to water the garden. The thought is that a structure might be built next to
the garden to store tools and supplies for the garden. This structure possibly could be large
enough to provide enough roof area to supply the water to the garden. What we did was
investigate a few different scenarios with different numbers to give the client some options.
There are five scenarios listed below.
Option
Catchment Area (sf)
Water Demand (gal/mon)
Tank Size (gallons)
Water to begin in tank
(gal)
Least amount of water in
tank during the year (gal)
1
2,000
3,000
5,000
2
1,800
3,000
5,000
3
1,500
2,500
4,000
4
1,200
2,500
5,000
5
1,030
2,500
5,000
0
1000
1,000
3,000
5,000
415
262
385
8
94
The above scenarios have different input values: catchment area, water demand, tank size, and
water to begin in the tank. These input values then calculate the amount of water left in the tank
each month based on average monthly rainfall for Toledo. The last row is the lowest value of the
amount of water left in the tank at the end of the month.
The water demand of the garden plays the most significant role in determining the size of the
tank and the catchment area needed. In our report, we used the value of 4,000 gallons per month
as water demand. We knew this number was a high number as the plants probably would be
healthy without this amount of water. You need to take into account the actual amount of rainfall
that the garden will receive directly. If it rains a lot during one week, your water demand will
decrease dramatically for that month since you will not need to water from the tank due to the
high rainfall. The spreadsheet does not take such things into account and therefore, realistically a
lower water demand is not out of the question.
From the table, a small building should be able to provide enough water to the garden. There are
a few things to think about when placing the building. With the tree line close to the back of the
garden, the building would have to be far enough away from the trees to get the required amount
of rainfall on the roof.
Our designed rainwater collection system is for taking water from the Law Center and not a
structure close to the garden. The elevation differences from having a structure built next to the
garden need to be taken into consideration. See the below figure for how the system could be
configured.
Page | 36
Source: http://deercreek_63080.tripod.com/theprimitivecabinwebsite/id8.html
This figure shows the rainwater being directly diverted into the storage tank. This would
eliminate the need to put a pipe underground, drastically eliminating the cost from our proposed
system. From the tank, the irrigation system could be directly connected to the bottom of the tank
just as our proposed system would be.
Having a structure right next the garden, would be a good solution to the current watering
problem at the garden.
Page | 37
12.4. Irrigation System Product Cutsheets
Page | 38