sustainable water demonstration final...
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Sustainable Water Demonstration
Final Report
Bryan Dripps
Heather Reinhart
Michael Henderson
2010/11
Project Sponsor: First Alternative Coop and the Corvallis Sustainability Coalition
IE 497/498
Project Number: 11
Course Instructor: Kenneth Funk
Faculty Advisor: Nancy Squires
Sponsor Mentor: David Eckert
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DISCLAIMER
This report was prepared by students as part of a college course requirement. While considerable effort has
been put into the project, it is not the work of a licensed engineer and has not undergone the extensive
verification that is common in the profession. The information, data, conclusions, and content of this report
should not be relied on or utilized without thorough, independent testing and verification. University faculty
members may have been associated with this project as advisors, sponsors, or course instructors, but as such
they are not responsible for the accuracy of results or conclusions.
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EXECUTIVE SUMMARY
The primary focus of this project was to research, design and implement a fully functional, interactive, and
entertaining public display system which collects, stores, and distributes rainwater to a vertical garden in order
to demonstrate to the community the practicality of sustainable water practices. The display drives to educate
on the feasibility of rainwater use and demonstrate the work required to move water.
The project includes a collection system of PVC piping, leaf screen filters, first flush diverters, mosquito
screens, and water safe tanks. The piping moves the water from the roof through the filters and into storage
tanks. Leaf screen filters remove large debris from the water before first flush filters remove polluted water
from a new rain, and mosquito screens keep mosquitoes from infesting the water stored in the tanks.
The pumping system includes a peristaltic, or roller pump, attached to a bicycle powered by the user. The rear
wheel of the bicycle was removed and replaced with a stand and hybrid chain-and-v-belt drive system to power
the roller pump and support the user. Standardized hose fittings attached to the pump allow garden hoses to be
connected to the pump and tanks, which permit a range of applications and portability of the pump to any
demonstration site.
The pump is capable of moving water to any height that this demonstration requires, delivering large volumes
of water even at roof height. It has been tested for reliability, and functions well due to its simplicity. The
pump fits well within the site and is fairly lightweight, allowing for easy storage and transport. It is simple to
use and requires little effort, which permits a large demographic to use the system.
Multiple design changes were required to refine the human-powered pump system, but the end result is a clean,
elegant, and efficient device, capable of pumping water with little effort and no electricity.
The result of this project is a completely functional rainwater collection and irrigation system. The tanks are
filling with clean, non-potable water during every rain event, and the bicycle powered pump is ready and
capable of moving water for irrigation and display purposes.
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TABLE OF CONTENTS
1. PROJECT DESCRIPTION ............................................................................................................................. 1
1.1. Background ............................................................................................................................................. 1 1.2. Requirements .......................................................................................................................................... 1
1.2.1. Project Description.......................................................................................................................... 1 1.2.2. Customer Requirements (CRs) ....................................................................................................... 2
1.2.3. Engineering Requirements (ERs) ................................................................................................... 3 1.2.4. Testing Procedures (TPs) ................................................................................................................ 4 1.2.5. Design Links (DLs)......................................................................................................................... 6 1.2.6. House of Quality (HoQ).................................................................................................................. 8
2. EXISTING DESIGNS, DEVICES, AND METHODS .................................................................................. 9
2.1. System Level ........................................................................................................................................... 9 2.1.1. Kelly Engineering Center ............................................................................................................... 9 2.1.2. Montana Resident’s Home System ................................................................................................. 9
2.1.3. Portland Residential Rainwater Irrigation ...................................................................................... 9 2.2. Component Level .................................................................................................................................. 10
2.2.1. First Flush Management ............................................................................................................... 10 2.2.1.1. Floating Ball.................................................................................................................................. 10
2.2.1.2. Tipping-Gutter System.................................................................................................................. 10 2.2.1.3. Vertical Gravity Filter ................................................................................................................... 10
2.2.2. Filtration ........................................................................................................................................ 11 2.2.2.1. Sand Filter ..................................................................................................................................... 11 2.2.2.2. Screen Filter .................................................................................................................................. 11
2.2.2.3. Carbon Filter ................................................................................................................................. 11 2.2.3. Water Delivery .............................................................................................................................. 12
2.2.3.1. PVC Piping ................................................................................................................................... 12
2.2.3.2. Gutters ........................................................................................................................................... 12
2.2.3.3. Metal Piping .................................................................................................................................. 12 2.2.4. Human Power Interface ................................................................................................................ 12
2.2.4.1. Foot Pedals .................................................................................................................................... 12 2.2.4.2. Merry-Go-Round .......................................................................................................................... 13 2.2.4.3. See-Saw......................................................................................................................................... 13
2.2.5. Pumping Mechanism .................................................................................................................... 13 2.2.5.1. Centrifugal Pump .......................................................................................................................... 14 2.2.5.2. Reciprocating Pump ...................................................................................................................... 14
2.2.5.3. Archimedes Screw ........................................................................................................................ 14 2.2.6. Delivery to Vertical Garden .......................................................................................................... 14 2.2.6.1. Drip Irrigation System .................................................................................................................. 15 2.2.6.2. Misting Irrigation System ............................................................................................................. 15
2.2.6.3. Flooding ........................................................................................................................................ 15 3. DESIGNS CONSIDERED ........................................................................................................................... 16
3.1. Design #1 .............................................................................................................................................. 16
3.2. Design #2 .............................................................................................................................................. 18 3.3. Design #3 .............................................................................................................................................. 19
4. DESIGN SELECTED ................................................................................................................................... 21 4.1. Rationale for Design Selection ............................................................................................................. 21 4.2. Design Description................................................................................................................................ 21
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4.2.1. Collection System ......................................................................................................................... 21
4.2.2. Pump ............................................................................................................................................. 22
4.2.3. Human Interface and Power Generation ....................................................................................... 23
4.2.4. Living Wall Irrigation ................................................................................................................... 24 5. IMPLEMENTATION ................................................................................................................................... 25
5.1. Implementation Plan ............................................................................................................................. 25 5.2. Implementation Overview .................................................................................................................... 26
5.2.1. Centrifugal Pump .......................................................................................................................... 26
5.2.2. Human Interface and Drive System .............................................................................................. 27 5.2.3. Piping Network ............................................................................................................................. 27 5.2.4. Living Wall Irrigation ................................................................................................................... 28 5.2.5. Bike Stand ..................................................................................................................................... 28
6. TESTING ...................................................................................................................................................... 29
6.1. Overflow ............................................................................................................................................... 29 6.2. First Flush Diverters ............................................................................................................................. 29
6.3. Pumping Head ....................................................................................................................................... 29 6.4. Aesthetics .............................................................................................................................................. 30 6.5. Usability ................................................................................................................................................ 30 6.6. Maintenance .......................................................................................................................................... 30
6.7. Weight ................................................................................................................................................... 31 6.8. Draining ................................................................................................................................................ 31
6.9. Sizing .................................................................................................................................................... 31 6.10. Entertaining ........................................................................................................................................... 31 6.11. Delivery................................................................................................................................................. 32
7. BIBLIOGRAPHY ......................................................................................................................................... 33 8. APPENDIX A: ENGINEERING CALCULATIONS .................................................................................. 34
9. APPENDIX B: BILL OF MATERIALS ...................................................................................................... 40
10. APPENDIX C: PART DRAWINGS ........................................................................................................ 42
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ACKNOWLEDGEMENTS
David Eckert
Hazen Parsons
Dr. Nancy Squires
Dr. Kenneth Funk
Dr. John Parmigiani
First Alternative Coop
Robert Culbertson
Joe Richard and JTI Supply, Inc.
Gary Borntrager
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1. PROJECT DESCRIPTION
1.1. Background
This project aimed to build the beginning of a sustainable water demonstration at the First Alternative Coop.
Rainwater was collected, filtered, and delivered to existing storage tanks. A human powered pump was
built to pump rainwater up to a vertical garden. The demonstration aimed to illustrate the usefulness of
rainwater collection and also demonstrate how much work is required to transport it.
Rainwater collection is of increasing importance around the world. After the implementation of this project,
the sponsor possesses a system for collecting clean rainwater to use for a public demonstration and also for
watering plants. The sponsor has also gained a human powered pump that can be used for a variety of
purposes in the demonstration. The demonstration will not only inform people, but will also attract
customers to the First Alternative Coop, possibly increasing sales.
1.2. Requirements
1.2.1. Project Description
The original project description is as follows.
Students will coordinate with the Corvallis Sustainability Coalition and the First
Alternative Natural Foods Co-op to design and install a series of water delivery
systems to collect rainwater and transport it on-site for approved uses and to collect
gray water (once used, relatively non-polluted water) and transport it on-site for
approved uses. The purpose of the project is to reduce municipal tap water use on-
site and to reduce the discharge of wastewater and storm water into the municipal
piping systems. The City of Corvallis and First Alternative Natural Foods Co-op
have allocated some funding. The student will gain hands-on experience with fluid
transport/storage and management on a government/business/non-profit project.
The students will use existing surveys and develop any necessary additional surveys
to design plans for delivering storm water from two buildings to a variety of storage
tanks and for delivering that stored storm water for later use on the site. Some of the
delivery systems will include electrical or human-powered pumps. One area has
been set-aside as a public storm water demo area. This area will include many
techniques for storm water mitigation, interpretive displays and interactive
components. Human powered pumps, such as hand pumps, treadle pumps and bike
pumps, will be incorporated on this area. A concept design has been approved and
the basic landscaping and tank installation has begun.
The project has been modified significantly and the scope more explicitly defined. Students were to
work with the First Alternative Coop and the Corvallis Sustainability Coalition to develop a system for
delivering and filtering rainwater to storage tanks. A human powered pump was to be designed and
implemented in the watering of a vertical garden, as part of a sustainable water demonstration. As this is
part of a demonstration, the systems needed to be engaging and accessible to a wide range of users. The
area for the demonstration is limited, so students needed to consider spatial limitations. A budget of
$1500 had been supplied. Further funds were available if justified.
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1.2.2. Customer Requirements (CRs)
1. System shall allow for draining of excess water to municipal storm water.
The system as a whole can only handle so much water. Any water overflowing the system must be
rerouted to conventional municipal storm water system. If not properly managed, overflow can
accumulate in unwanted places and cause flooding.
2. System shall remove debris from first flush.
First flush refers to the first rain after a dry period. This first rain carries a significant portion of
sediment, organic matter, oil, debris, and bacteria; the system must be able to remove first flush
contaminants prior to the main filter.
3. System shall allow for pumping of water from tank to an adequate height and pressure.
The pump’s performance will be based upon the subsequent engineering requirements derived from this
requirement. It will be based on the height of the living wall, and the required pressure for the delivery
system.
4. Pumping mechanism should be aesthetically pleasing.
The pump is to be used in a public demonstration, so the end product should be attractive and not look
jumbled.
5. Shall be easy to use and accessible to a range of users.
This project is an interactive display, so it must accommodate a wide spectrum of customers.
6. Pump shall be low maintenance.
The pump should be durable and not require undue maintenance scheduling. This pump will be unique,
so less maintenance requirements are ideal.
7. Pump shall be human powered.
The basis of this project is the incorporation of human power to see how much work is actually required
to move water, so this is absolutely necessary.
8. Pump should be movable.
If the project area is being modified, or the pump is moved to another display site, it should be portable.
9. Pump should be able to be drained.
If the region freezes, the pump must be able to be drained in order to reduce chance of freeze-based
damage to the pump.
10. Pump connections should use standard hose fittings.
If the pump is delegated to a new task or hoses are damaged, standardization of components is cheaper,
easier to maintain, and easier to fix
11. Pump should be compact.
Space is limited, thus the pump should take up minimal space.
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12. Pump should be entertaining.
An entertaining pump will boost use among the potential customer base, and thus awareness of
sustainable water techniques.
13. Pump shall contain a steel tab to lock it to the building.
Theft is always a valid concern, especially in outdoor public areas.
14. Each tank shall contain a backflow prevention valve.
This is for sanitation reasons. Any water that has left the tanks should not re-enter without being
filtered first.
15. System shall deliver adequate water to plants.
The primary purpose of the pump is to water a living wall. The plants must receive adequate water or
the pumping and watering systems are useless.
1.2.3. Engineering Requirements (ERs)
1. Overflow piping should be able to export water at a rate of 6 GPM.
Tolerance: -0.5 gallons, no upper limit
Rain typically doesn’t fall at a rate of more than 0.30 inches per hour. This equates to around 6 GPM
for this roof. In order to compensate for a severe storm once the tanks are full, an export rate of 6
GPM adequate to avoid flooding of the area.
2. First flush filter shall remove first 17 gallons from first rain.
Tolerance: -1 gallon, +10 gallons
This ensures that all buildup of debris from the dry season is removed from the water before entering
the tanks. A convention usually followed for first flush systems is that the first 10 gallons per 1000
square feet are removed. The roof is approximately 1650 square feet.
3. Pump should move water to a height of ten feet.
Tolerance: -2 feet, no upper limit
This ensures the water will reach the top of the living wall, watering all levels.
4. Pumping mechanism shall have zero rough edges, visible glue or blemishes.
Tolerance: +2 blemishes
This makes sure the device is safe and professional looking.
5. A range of users shall be able to pump for 10 minutes without tiring.
Tolerance: - 2 minutes, no upper limit
The device must be easy and enjoyable to use for a wide range of age, height, and physical fitness
levels.
6. Pump shall require maintenance no more than once per 10 hours of use.
Tolerance: -2 hours/ no upper limit
10 continuous hours of use would equate to months of use under predicted normal operating
conditions.
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7. Pump shall weigh 40lbs or less.
Tolerance: +5 pounds
40 lbs is a manageable weight for a team of people to move when pump relocation is necessary.
8. Pump shall require no tools for draining.
Tolerance: 0 tools
In order to prevent freeze damage, the pump must be drainable. Requiring no tools makes draining
for storage a much easier task.
9. Pump shall fit inside a 3x4x4 foot box.
Tolerance: +6 inches per dimension, no lower limit
Space is limited at the site, so the pump must be small. There is a picnic bench near the coffee stand
that could be moved for the pump. Also, the pump could be placed between the two larger tanks.
These size constraints would allow for the pump to fit in either of these locations.
10. 80% of users should find the pump entertaining after completing a survey.
Tolerance: -5%, no upper limit
Users should enjoy the device and want to come back or tell others about the project. The project is
aimed at raising awareness and interest, so an adequate number of users should find the system
entertaining.
11. System shall deliver at least 1 inch per hour of water.
Tolerance: ±0.5 inches
Too little water would be insufficient to plant growth. Too much water delivered can damage plants
and erode soil base. As the living wall is not built yet, this requirement is subject to change. We don't
currently know what the soil area of the living wall the sponsor will provide will be, so we are unable
to give a specific volume at this time.
1.2.4. Testing Procedures (TPs)
1. A bucket of 6 gallons or greater will be filled to 6 gallons with a garden hose. The overflow pipe for
each tank will be disconnected and the bucket will be slowly poured down the overflow pipe. A stop
watch will be used to time the pour. The water must go down the overflow in less than 1 minute without
backing up in order for this test to be successful.
2. Team members will pour a five gallon bucket filled with water down each downspout. After each
downspout has received approximately five gallons, each first flush filter will be emptied into the empty
bucket. The volume of water from each downspout will be measured by looking at the marks on the
bucket. The volume of water diverted by the downspouts shall total between 16 and 27 gallons in order
for the system to pass this test.
3. A hose will be attached to the inlet and outlet of the pump. There shall be at least 2 feet of water in
the tank to simulate actual operation. One team member shall stand on a step stool and hold the outlet
end of the hose at ten feet above the pump and lowered until water flows from the hose. Another team
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member shall use a tape measure to measure the height of the outlet. The third team member will
operate the pump. For this test to be successful, water must flow from the end of the hose when held at
a minimum of 8 feet.
4. The sponsor and another individual not involved in the project will thoroughly inspect the human
interface and pump and note any blemishes, visible glue, or any sharp or rough edges. For this test to be
successful, the inspection shall expose no more than two blemishes.
5. Five users of different ages and of different fitness levels shall operate the pump to irrigate the living
wall. The users will be told to operate the pump until they are too tired to continue, up to 10 minutes.
The use of the pump will be timed with a stop watch. All users must use the pump for at least 8 minutes
before tiring in order for the test to be successful. This can be done at the same time as testing
procedure 10.
6. Over the course of a week, each team member shall use the pump to circulate water held in a small
plastic storage container. A garden hose shall be attached to the inlet of the pump. The outlet hose will
go back into the tank. Each team member shall operate the pump for 30 minutes per day for 7 days.
During this week, no maintenance shall be done on the pump or bicycle. For this test to be successful,
the pump must operate for the first eight hours without any maintenance. Maintenance can be done,
however, on the hoses and water containment system. Priming of the pump will not be considered
maintenance for this test.
7. One student will hold the entire pump and stand on a bathroom scale indoors on a flat surface. The
weight will be recorded. The student will put the pump on the ground and stand on the scale without the
pump. Their weight will be recorded. The difference between the two weights must be less than 45
pounds.
8. After testing procedure 6 is complete, the last student to use the pump will remove the hoses attached
to the inlet and outlet and attempt to drain the pump into the plastic container. The other team members
must be present to confirm that no tools were used. If the student can drain the water from the pump
without using any tools, the pump will satisfy the requirement.
9. Students will measure the pump’s maximum height, length, and width with a tape measure. The
smallest dimension must be less than 3 feet, and the others’ must be smaller than 4 in order for this test
to be successful.
10. Students will ask ten individuals to operate the pump and irrigate the living wall. After five minutes
of use, students will ask the user “yes or no, this system for irrigation was both entertaining and
interactive to use”. Seven of the ten users surveyed must answer yes to this question in order for the
system to satisfy this requirement.
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11. Calculate the volume required in gallons by measuring the surface area of the vertical section of the
tank and multiplying that by one inch, then converting to gallons. Then operate the pump with the outlet
hose held at eight feet until the calculated volume, measured by filling five gallon buckets, has been
reached. This must take one hour or less to pass this. This test can be done along with testing procedure
6.
1.2.5. Design Links (DLs)
1. Overflow for all pipes is three inch diameter PVC. This is fairly wide and can handle flow rates much
higher than 6 gallons per minute, usually several hundred.
2. The design utilizes five first flush systems of four inch diameter. Each pipe shall be five and a half
feet in length. This will allow for each first flush pipe to divert 3.6 gallons of water; a total of 18
gallons will be diverted.
3. The speed that the pump operates at is optimized for the pump radius for a pressure head of four
meters, or approximately twelve feet. For a pressure head of four meters, minimal power is required.
Any user will be able to generate the required power.
4. The system is aesthetically pleasing because careful consideration was put into the materials used for
the pump, the human interface, and the non-intrusive layout of the pipes. The system will be
carefully constructed and all machined parts will be deburred to prevent any blemishes or visible
glue. The casing for the pump will be constructed from polycarbonate, and the impeller will be
powder coated to prevent any oxidation. The bicycle utilizes a belt drive system rather than a chain
to minimize rusting.
5. The system meets this requirement by utilizing bicycle power. Most users can generate between 0.5
and 0.7 HP on a bicycle. Pumping water to the required pressure head requires a fraction of this
power. The actual power required depends on the pump efficiency. This pump shall be easy for the
majority of users. It will require much less power than that required for riding a bicycle at a
reasonable pace.
6. The pump is very simple in design. There are very little parts to the actual pump. On the pump
itself, only the bearing and seal will need to be replaced occasionally. The impeller and case will both
be very rust resistant as well. The case will be secured by stainless steel bolts and heli-coils, to
prevent damage to the plastic case. The mechanism for generating power is a bicycle. It will be belt
driven, to minimize rust. The bicycle itself will be painted and sealed; as will the stand that will
support it and hold the pump.
7. The mechanism for generating power will be a bicycle. Without the tires, it will be compact. The
bicycle itself will weight little, and the stand to secure it to the pump is simple and lightweight. The
pump is small and made from lightweight materials as well. Overall, the human-powered pump will
be small and weight little.
8. The pump design is a centrifugal pump. There are no valves to keep water in the pump. To drain it
for storage, it will be as simple as removing the inlet hose and tilting it until the water is drained from
the pump.
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9. By using a bicycle, users will be able to see the living wall as they power the pump. The system will
be interactive. Users will be able to pump competitively, to see how much water they can get to
come from the delivery lines.
10. The pump is relatively large in diameter and depth. It will be able to produce flow rates high enough
to irrigate an inch of water within an hour.
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1.2.6. House of Quality (HoQ)
Dra
in o
ver
flow
of at le
ast 6 G
PM
Shall
rem
ove first 17 g
allo
ns o
f w
ate
r
Shall
pum
p to a
heig
ht of 10 feet
Shall
be fre
e o
f ro
ugh e
dges, glu
e, or
oth
er
ble
mis
hes
Users
shall
be a
ble
to u
se for
at le
ast 10 m
inute
s
Shall
with
sta
nd 1
0 h
ours
with
out m
ain
tenance
Shall
weig
h le
ss than 4
0 lb
s
Shall
dra
in w
ithout to
ols
Pum
p s
hall
fit in
to a
3x3x4 foot box
80%
of users
shall
find p
um
p e
nte
rtain
ing
Syste
m s
hall
be a
ble
deliv
er
at le
ast 1 in
ch in
an h
our
Customer Requirements Wt. X – strong
System shall allow for draining of excess water to municipal storm water. 25 X o – moderate
System must remove debris from first flush. 25 X * - weak
System shall allow for pumping of water from tank to an adequate height. 25 X
Pumping mechanism should be aesthetically pleasing. 15 X
Pump shall be easy to use and accessible to a range of users. 25 * X *
Pump shall be low maintenance 20 o X o
Pump shall be human powered. LTE *
Pump should be movable. 20 * X o
Pump shall be able to be easily drained. 25 o X
Pump connections should use standard hose fittings. LTE
Pump should be compact. 25 o o X
Pump shall be entertaining. 20 * * o X
Pump shall contain a steel tab to lock it to the building. LTE *
Each tank shall contain a backflow prevention valve. LTE
Pump shall deliver adequate water to plants. 25 * X
Target 6 17 10 0 10 10 40 0 4 80 1
Units GPM Gal ft. issue min hours lbs tools ft. % in/hr
Tol -0.5
-
1/+10 -2 +2 -2 -2 +5 +0 +0.5 -10 -0.2
TP 1 2 3 4 5 6 7 8 9 10 11
DL 1 2 3 4 5 6 7 8 7 9 10
Engineering Requirements
Colle
ct
Pum
pin
g
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2. EXISTING DESIGNS, DEVICES, AND METHODS
2.1. System Level
The existing systems chosen for discussion are the system used by Kelley Engineering Center at OSU, a
Montana home system, and a rainwater irrigation system in Portland, Oregon. Kelly Engineering Center
was chosen because it is similar to this project, only of a much larger scale. The Montana system was
chosen because of its similarity to the system this project aims to develop. Finally, the Portland system is
also similar to this project in that it is of similar scale, it is local, and is subjected to nearly identical
2.1.1. Kelly Engineering Center
At Kelly Engineering Center of Oregon State University, a similar rainwater catchment and filtration
system was built, only on a much larger scale. The system collects water from the gutters on the building
and runs it into planters to filter out any particles and debris. Water is then filtered by UV radiation and
stored. There are three 16,500 gallon storage tanks in the basement of the building. This water is used in
non-potable applications throughout the building, mainly in toilets. The system cost $90,000 but saves
approximately 372,000 gallons of water annually (Storm Water Solutions).
This system does not meet many requirements that the Corvallis project will. While it exceeds the
requirements in many areas, such as filtration, the project is on a much larger scale. It is an example of a
large-scale application of rainwater collection and use. It is useful to examine because the system
utilizes cutting edge ideas, such as the planter and UV filtration systems.
2.1.2. Montana Resident’s Home System
The system developed in Montana (Rupp) follows a simple design utilizing readily available materials to
catch, filter, and store water. The system uses traditional gutter downspouts to collect water from the
roof of a house and gravity feeds it into a filter that is essentially a metal mesh screen on top of a pipe of
large diameter (1-2 feet) that includes a conventional vertical first flush filter to divert sediment out of
the pipe. This filter sits atop (or moderately close to, and above) the cistern. The cistern is completely
buried in the ground to avoid freezing without the need for an external electric heater or extensive,
expensive insulation. Water is pumped from the deep cistern by means of an electric pump for ease of
use and incorporation into an otherwise standard house layout.
The Montana system meets some of the requirements for this project on the component level. First, the
system filters out particles with a screen filter. Next, the first flush is diverted using a common first flush
filter. This setup may require more maintenance than having the screen filter after the first flush system,
as the filter is more likely to get clogged. Second, the system takes care to avoid freezing the water, and
finally the water is used for irrigation and in home purposes which may be of interest for future projects.
2.1.3. Portland Residential Rainwater Irrigation
The system in Portland, Oregon (Ersson) utilizes an above ground storage tank fed via traditional roof
gutters with leaf screens to protect the system from initial large contaminants. The gutter downspouts
feed a closed system piping unit that flows into a first flush filter. This first flush filter uses a floating
ball that allows the first few dirty gallons to fill up the filter, which allows the ball to seal a valve,
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whereby allowing all remaining water to pass over the first flush filter and into the collection tank. The
tank, being above ground, requires no pump to irrigate the garden, but uses a small electric pump to
pressurize the water supply feeding the house’s main water input.
Using the Portland system as a precedent is useful because it uses features that could offer solutions to
component choices for this project. The storage tank is located above ground, leaf screens and a first
flush filter are utilized, and the water collected is used to irrigate a garden. Overall, this system comes
closest to fulfilling the requirements for this project.
2.2. Component Level
This project can be broken down into six general sub-functions: first flush management, filtration, water
delivery, human power interface, pumping mechanism, and delivery to the vertical garden.
2.2.1. First Flush Management
The first flush refers to the first rain after a dry spell. During this time, excess debris shocks the system
and will clog the main filter. Also, build up during the dry period can lead to bacterial contamination and
acidic water. A system is required to filter out this excess debris separately. Three main designs for first
flush systems include the floating ball system, tipping gutter system, and vertical gravity filter.
2.2.1.1. Floating Ball
A floating ball system uses a vertical piece of pipe connected to the main horizontal pipe. This
vertical section fills first, collecting all of the debris and contaminants. There is a ball in this section
that floats to the top and plugs the opening when it is full. The bottom of a floating ball system can
be unscrewed, allowing the draining of the first flush water and debris.
Several retail first flush systems are available. An inexpensive floating ball system available through
Rain Harvest Systems would work well for our project. It contains a ball and a screw cap that has a
drip valve for an automatic reset.
2.2.1.2. Tipping-Gutter System
A tipping gutter system uses a gutter initially tilted away from the tank. The water is directed to a
bucket suspended by a rope that goes through a pulley and is attached to the end of the gutter. As
this bucket fills with water, the increasing weight of the bucket tilts the gutter toward the tank. This
ensures that the first bucket load of water and debris does not reach the tank. A small hole is put in
the bucket, allowing it to drain slowly and reset (REUK). This system fulfills the requirements of the
first flush function, although it is a complex solution. Another issue with this system is the
considerable amount of space it requires over some of the other options.
2.2.1.3. Vertical Gravity Filter
The most basic type of first flush filter involves a large diameter (~6 inch) pipe of variable length to
hold a volume based upon roof area of rain collection. The pipe is outfitted as a vertical unit, sealed
off at the bottom with a screw-in plug and a spigot near the bottom that is constantly left slightly
11
open. As the system is exposed to rain, the pipe fills up with the initial flood of water, and all of the
sediment with the first flush settles at the bottom of the pipe. The cleaner water following the initial
surge will flow straight over the filter and into the water catchment cistern. The spigot allows the
filter to drain standing water. After a set amount of use, the filter can be cleaned out by simply
removing the plug at the bottom of the pipe, which would allow the sediment and other accrued
debris to fall out.
One issue with the vertical gravity filters is that there is turbulent area at the top of the filter where
the clean water flows over the water trapped in the filter. This allows oil and other low density
debris to be swept into subsequent component of the system.
2.2.2. Filtration
Filters offer an in-line solution to reducing or eliminating sediment and debris from entering subsequent
components of the delivery system. Ideally, the filter would be placed immediately after the collection
unit (in this case, the roof) in order to eliminate debris from as much of the system as possible.
2.2.2.1. Sand Filter
Sand filters are a natural way to filter relatively fine contaminants from a water supply. They are
used not only in applications of similar scale, but also for large industrial applications. A sand filter
method to clean the water would meet all of the filtering requirements of this project. Sand filters are
also natural and have little or no negative impact on the environment, making them ideal for this
sustainable water demonstration. Required maintenance of sand filters is minimal, and cost is low.
2.2.2.2. Screen Filter
Screen filters present a simple method to filter large sediment out of the system at an early stage of
the collection process. Utilizing a screen filter offers an inexpensive and easy way to filter the water
at a basic level, while also allowing ease of maintenance. If the filter is installed at an angle, then
debris caught in the filter would be sloughed off as water kept flowing over the filter. Screen filters
are also available in a range of filter mesh sizes to cater toward any diameter of particulate matter to
be removed. The downside of these filters is that they still allow some biological matter, leaves and
bugs, into the system.
2.2.2.3. Carbon Filter
Carbon filters consist of a mass of activated carbon powder, positively charged, that can attract most
of the negatively charged tiny particulates and impurities of a water source. Carbon filtering is a
relatively new method of filtration, and can filter particulate matter as small as 0.5 microns. These
filters are usually used for systems in which the water collected must be drinkable before it is
integrated into the primary water main for a house. Carbon filters are widely available, but are also
costlier than the sand filtration and screen methods. A carbon filter design would fulfill many of the
customer requirements, but may be excessive, as sanitation is not a primary concern.
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2.2.3. Water Delivery
The water delivery function transports water from the collection site to the tanks. Three existing
delivery designs discussed here are PVC piping, typical residential gutters, and metal piping.
2.2.3.1. PVC Piping
PVC piping is a cheap existing method for transporting fluids. It is inexpensive, easy to locate, and
there are many existing joints and attachments. The piping also requires little maintenance and lasts
a long time. This method would work well for this project. One drawback is the purpose for the
system is a sustainable water demonstration, and the manufacturing of PVC is more harmful to the
environment than alternatives, so another method may suffice better, as budget is not a very large
issue. Another issue for consideration is freezing. Because any piping is closed, damage can occur
from water freezing inside the pipe.
2.2.3.2. Gutters
Gutters are used mainly on buildings to direct rainwater to downspouts. Residential gutters are
designed to transport rainwater. They would work very well for this function, as they are designed
specifically for this purpose. While slightly more expensive than PVC, they are less prone to damage
from freezing, as they are open. While they are more prone to clogging from debris, they are also
much easier to clean than piping. If gutters are used, multiple filters must be used intermittently to
ensure that the water is cleared of free-falling debris along the length of the delivery system.
2.2.3.3. Metal Piping
Metal piping is frequently used in buildings to transport fluids. Metal piping doesn't typically contain
the harsh chemicals that PVC does and it serves a similar function. There are several drawbacks to
metal pipes in this application though. For one, it is very expensive. It also transfers heat more
easily, accelerating any freezing, can corrode causing unwanted elements in the water and it is
significantly heavier than PVC.
2.2.4. Human Power Interface
One of the most important areas of this project is the pumping mechanism. Because this project is
intended to be used as an interactive demonstration, the human interface must be interesting and easy to
use. The purpose of this function is to generate mechanical power, which will be used by the pump.
Three powering mechanisms discussed here are foot pedals, merry-go-rounds, and see-saws. All three
of these methods have been employed for pumping water in other systems.
2.2.4.1. Foot Pedals
Foot pedaling power is one of the most efficient ways to utilize human power. The efficiency of
foot pedaling, the power it generates, and its ease of use are reasons foot power is used extensively
for human powered transportation. Bicycles and unicycles are also readily available and could
13
easily be fitted to the pump by means of a chain. One disadvantage is that there are several moving
parts that require maintenance, but bicycle maintenance knowledge is fairly easy to find.
Jon Leary, a mechanical engineering student from University of Sheffield, designed and built a
portable human powered pump. It was designed for Guatemalan farmers to help irrigate fields. The
pumping mechanism can be flipped upward and the bicycle can be ridden (Coxworth). This design
would serve the pumping function well. It is not extremely compact, but it would fulfill most of the
customer requirements. This example shows what human power can accomplish with pumping.
Biking is an effective and especially ergonomic way to deliver power to a pump.
2.2.4.2. Merry-Go-Round
A merry-go-round is not only a fun playground toy, but also a useful means of powering a water
pump. The merry-go-round powers an underground pump that moves the water from an aquifer to an
above ground tank. The bottom of the tank stands several meters above ground so when the water is
called upon, gravity does all the work. These fun and hard working pumps have mainly been
installed in Africa to help provide safe clean drinking water. These play-pumps, as they have
become aptly named, are showing up in the U.S. as well (Torrone).
The merry-go-rounds are very effective human powered pumping tools that are also accessible to a
range of users, entertaining, very low maintenance, and can provide adequate power to the water
pump. The size of the merry-go-round may render the option impractical for this project.
2.2.4.3. See-Saw
Another way to harness human power is the see-saw or teeter-totter, a common playground
attraction. A community in Columbia was rebuilding their water pumps when the children noticed
the pumping handle was very similar to half of a see-saw. The community developed a see-saw that
could be attached to their water pump and have since introduced this method to over 600
neighboring villages.
The see-saws are a great way to power a water pump while also being entertaining. They are low
maintenance and accessible to most everyone. The force input on every stroke of the cycle of this
particular design can provide a large torque value and be used as the input for a fairly high-output
pump. This design may be too large for our size requirements.
2.2.5. Pumping Mechanism
Pumping the water will be accomplished with the use of human power, and presents the most difficult
component level design of the system. The pump must be able to force water to an adequate pumping
height without requiring excessive user energy input. The pump must allow for a wide range of physical
fitness levels while still delivering sufficient water. The pump designs discussed here are the centrifugal
pump, reciprocating pump, and the Archimedes's screw.
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2.2.5.1. Centrifugal Pump
A centrifugal pump is commonly used in small-scale and large-scale industrial fluid applications. A
centrifugal pump makes use of an impeller that forces the water outward from a central water intake.
The pump casing directs this outward flow through a single outlet. The water moving outward is
replaced with water that is at the inlet. The main advantage of a centrifugal pump is that it provides
constant, steady pressure and flow. The only disadvantage to this method is that it requires priming,
but this could be resolved if the water intake were to be drawn from the bottom of the tanks near the
pump. A centrifugal pump would provide adequate pumping height and pressure, require relatively
little maintenance with few moving parts, and could be easily drained.
2.2.5.2. Reciprocating Pump
A reciprocating pump often uses a plunger or piston to move the liquid and is generally used for
small-scale operations. The pump operates by effectively expanding a volume via a moving piston,
creating a vacuum that draws fluid into the cylinder via a one-way valve. The fluid is then forced out
of another, opposing one-way valve as the piston descends and decreases the effective cylinder
volume.
Piston pumps are difficult to design and would more than likely require a lot of maintenance. The
pump would not need to be drained and are usually small and portable. Siphoning and back flow
would not be a problem when using this pump and the pump is capable of providing an adequate
amount of water to the vertical garden.
2.2.5.3. Archimedes Screw
The Archimedes's screw is one of the oldest pump designs, dating back thousands of years, when it
was powered by a hand crank, and is still used extensively in industrial applications. It is essentially
a large screw inside of a casing. When turned, it forces the fluid up the casing. This design would
fulfill most of the customer requirements, but it is rather complex design. The Archimedes's screw,
while effective, doesn’t provide much pressure; it simply lifts fluids. One advantage is that it is very
resistant to damage, which would lower maintenance requirements. This design can operate as an
open system, thus increasing visibility of the water being moved around.
2.2.6. Delivery to Vertical Garden
The final sub-function within this system is the delivery of water to the plants in a vertical garden. This
serves as the final outcome of the system and gives a purpose to the public demonstration. The three
existing watering designs discussed herein are drip irrigation systems, misting irrigation systems, and
flooding.
15
2.2.6.1. Drip Irrigation System
A drip irrigation system is a common method for watering gardens. It would require little to no
pressure from the pump, effectively water the vertical garden, and offers a relatively inexpensive
option. A drip system would fulfill almost all of the customer requirements, as it is low impact and
is an effective way to water gardens, but it would not be very visible or exciting. This problem
could be corrected by making the delivery visible by another means.
2.2.6.2. Misting Irrigation System
Misting systems are a commonly employed method for watering small gardens and for keeping
produce fresh. There are retail misting designs available, ranging from full systems to in-line PVC
nozzles. Misting systems are gentle on the plants, deliver a reasonable volume of water, and are
visible. The only disadvantage this method has is that it requires greater pressure than alternatives,
such as a drip system.
2.2.6.3. Flooding
Another existing method for watering plants is simply to flood the area with water. This is
commonly done with potted and hanging plants. The soil is flooded with water until it drips through
the bottom of the pot. This watering method could be employed to water the vertical garden. The
downfall is that the delivery of this system is only minimally visible, and minerals and tiny
particulates would leech out with the water as it seeped through the soil to the next layer in the
vertical garden.
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3. DESIGNS CONSIDERED
This chapter discusses possible system designs for the project as viewed from the individual component
designs. These designs came from research of current designs and devices that are used for water transportation,
storage, and delivery in modern systems. Those designs and devices that are most applicable to this project are
stated in chapter two, and they are considered the most cutting-edge for their particular purpose.
3.1. Design #1
System Outline
First Flush Management: Floating Ball First Flush System
Filtration: Slanted Box Leaf Screen and an Angled Screen Filter
Transportation to Tanks: PVC Piping
Human Interface: Unicycle with Arm Supports
Misc. Water Transport: Garden Hoses
Pumping Mechanism: Centrifugal pump
Delivery Method: Holding Tank with Watering Troughs
System Description
In this system the water runs from the roof into a slanted box leaf filter. This removes large debris and
keeps the first flush system from getting clogged. The water flows out of the slanted box leaf filter and
straight into a floating ball first flush system. There are several kits online that include the ball, the joint,
and the cap with a drip valve. This first flush system replaces the building’s normal drain pipes. The water
then leaves the first flush by means of PVC piping that runs along both sides of the building.
The PVC piping on the south side of the building leads to the east-most 3000 gallon holding tank. The
piping can be supported by the pole between the building and the tank. Water enters a 35 mesh slanted
screen filter, to lower cleaning requirements. The two 3000 gallon tanks are connected by a pipe that will
allow them to fill simultaneously. The tanks have an overflow pipe at a height directly beneath the filter
height. This ensures that the water cannot ever flow back up through the filter, as the water level could
never reach the height at which the water enters. These overflow pipes run down the sides of the tanks into
municipal pipes underground.
On the north side of the building, the collection pipe first enters the 500 gallon tank through the same type
of angled screen filter. The overflow from this tank leads to the 1650 gallon tank, which overflows into the
municipal drainage system. This allows for the 500 gallon tank to remain full most of the time, making the
watering of the vertical garden more dependable.
Each of the tanks are fitted with a standard hose spigot towards the bottom of the tank. This ensures that the
hose is always pressurized, so long as there is water in the tank. This way, the centrifugal pump, when
lower than the water level at the top, is always be primed. A vacuum breaker is fitted to the end of the
17
spigot and prevents back flow into the tank. To prevent free flow of water, the valve on the spigot can
simply be turned off when watering is complete.
The centrifugal pump is powered by means of foot pedaling. A frame is to be made from aluminum tubing
and a bicycle seat and crank is fitted to the system. Arm supports are included so that the user can be
stabilized while pedaling. The system has three gears, so that users of different strengths are able to power
the pump. The centrifugal pump consists of a two part casing sealed with a liquid gasket and bolted
together, a simple impeller, a water proof bearing, and a shaft fitted with a bicycle gear. It is chain driven.
A garden hose is fitted to the outlet of the pump and run up to a Plexiglas tank on top of the vertical garden.
This tank is fitted with a toilet flush valve. This will be opened by a buoy that is chained to the valve.
When released, the water inside the tank runs into troughs containing many small holes above the vertical
garden planters. The water drips out of the trough and water the plants.
System Advantages and Disadvantages
Advantages:
1. Compact and powerful power mechanism.
2. Simultaneous tank filling allows for a greater variety of uses for the water.
3. Steady flow from centrifugal pump.
4. Constant resistance to drive.
5. Two-step filtration with angled screens requires little maintenance.
6. Floating ball contains contaminated water.
7. Holding tank gives control over total volume delivered to plants.
8. Holding tank with troughs gives visible and entertaining water delivery.
Disadvantages:
1. Tilted box leaf filter takes up a lot of vertical space, making it difficult to fully fill the 3000 gallon
tanks.
2. Simultaneous tank filling gives less available pressure for a given volume.
3. Floating ball first flush system is more complex than alternatives.
4. Bicycle components are vulnerable to rust and wear.
5. Bicycle components require more maintenance than alternative human interfaces.
6. Centrifugal pump requires priming. Limits available uses for pump.
7. Water delivery system to the vertical garden is more complex than alternatives.
8. Plexiglas holding tank requires cleaning to look appealing and sanitary.
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3.2. Design #2
System Outline
First Flush Management: Vertical Pipe Filter
Filtration: Cartridge Filter and Box Leaf Screen
Water Delivery: Open Gutters
Human Interface: See-Saw
Pumping Mechanism: Diaphragm Pump
Misc. Water Transport: Garden Hoses
Delivery Method: Garden Drip System
System Description
The second design considered starts with water from the roof flowing into a box leaf screen filter to remove
large leaves and debris. The water enters an open gutter attached to the outside footprint of the building.
From there, the water heads to the vertical pipe first flush filter which filterd the first 17 gallons of the first
rain. Next, the water flows into PVC piping to a cartridge filter in order to remove any small particles left in
the water to prevent debris in the tank.
The pipe layout is be similar to that of design #1, with the south pipe delivering water to the two 3000
gallon tanks and the north pipe supplying the 500 gallon and 1650 gallon tanks. The one difference with the
delivery to the tanks is that the first 3000 gallon tank fills first and the overflow fills the second large tank.
This allows for higher available pressure for a lower volume of collected rainwater. The overflow from the
second tank drains into the municipal storm drain pipe. This overflow pipe is be located at a lower height
than the entrance in the first tank. The 500 gallon tank fills first and overflow into the 1650 gallon tank in
order to keep adequate water in the 500 gallon tank.
The water is drawn from the bottom of the tank and has a spigot and vacuum breaker. This gives the most
pressure to begin with and lowers pumping requirements for the diaphragm pumps. The pumps are powered
by a see-saw. This human interface is both entertaining and effective. Two small diaphragm pumps are
located at each side of the see-saw. When one is on its intake cycle, the other will be exhausting. Water for
both pumps is drawn from the same line for the intake and water is outputted to the same line as well. Each
pump consists of a diaphragm, a casing, and two one way valves, one for intake and one for exhaust. The
diaphragm would not need to move much, so the pumps can be near the fulcrum. This allows for good
leverage from the users.
The vertical garden will be watered with a standard garden drip system. Before entering the drip system,
water will be run through a trough and will turn a pinwheel. This will give a visible delivery and make the
system more entertaining.
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System Advantages and Disadvantages
Advantages:
1. Individual filling of the large tanks gives higher available pressure for a smaller volume of water.
2. Flat box leaf filter takes up less vertical space.
3. Vertical pipe first flush system is a simple design.
4. Cartridge filter removes very small particles.
5. Open gutters are easier to maintain than piping alternatives.
6. Human interface is exciting and allows for competitive pumping.
7. Diaphragm pumps are simple.
8. Drip systems are inexpensive and extensively used.
Disadvantages:
1. Individual tank filling restricts uses for water when there is a small volume.
2. Flat box leaf filters require more maintenance than tilted box filters.
3. Cartridge filters require frequent replacement.
4. PVC pipe is already available on site, making gutters a much more expensive option.
5. See-saw is not compact enough to fit within space restrictions.
6. Diaphragm pumps do not supply consistent flow.
7. Drip systems are not visible.
3.3. Design #3
System Outline
First Flush Management: Floating Ball Filter
Filtration: Screen Filter and Cone Leaf Screen
Water Delivery: Metal Piping
Human Interface: Merry Go Round
Pumping Mechanism: Centrifugal pump
Misc. Water Transport: Garden Hoses
Delivery Method: Mist system
System Description
Water starts by collecting on the collection roof. From the roof, the water enters the metal piping. The
entrance to the metal piping contains a conical, wide mesh screen. This ensures that no large leaves or
debris enter the collection pipes. Following the screen filter, water is then routed into the first flush filter,
where the dirty water with sediment and contaminants are contained within a floating ball filter.
After filling the first flush systems, the water continues through the metal pipes into a screen filter assembly
and into the tanks. The pipes on the south side feed the 3000 gallon tanks and the pipes on the north side fill
the 500 gallon tank and the 1650 gallon tank. The 3000 gallon tanks are filled simultaneously and an
20
overflow pipe is near the top of the west-most tank. The overflow from the 500 gallon tank is used to fill
the 1650 gallon tank, which overflows into the storm drain system.
Water would be drawn from bottom of the tanks with a typical garden spigot and a vacuum breaker. The
water then flows into a centrifugal pump which is powered by a merry-go-round. A merry-go-round is an
effective and entertaining human pumping interface. With enough users, the pump would get an adequate
amount of power. This method is able to power a larger pump than the other methods, as many users are
able to power the pump simultaneously.
The vertical garden is watered by a misting system. Misting systems are widely available and come in
several forms. The type used in this design is in line PVC mister nozzles. These nozzles are inexpensive
and provide adequate water. A centrifugal pump can provide both plentiful and constant pressure, making a
misting system ideal.
System Advantages and Disadvantages
Advantages:
1. Cone leaf filter is compact.
2. Simultaneous filling of tanks allows for more uses for a lower volume of water.
3. Floating ball system seals contaminated water from system water.
4. Metal piping is more durable than PVC piping.
5. Merry-go-round is an interactive and fun human interface.
6. Merry-go-round can allow many users to power pump.
7. Centrifugal pump delivers constant flow of water.
8. Mist system is gentle and visible.
Disadvantages:
1. Cone leaf filter requires more maintenance than alternatives.
2. Simultaneous filling of tanks yields lower available pressure for a small volume of water.
3. Floating ball system is more complex than alternatives.
4. Metal piping is more susceptible to freezing.
5. Merry go round is not very compact. It would be difficult to fit in a 3x4x4 foot box.
6. Misting system requires higher pressure to function properly.
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4. DESIGN SELECTED
4.1. Rationale for Design Selection
The most reasonable design for this system is design number one in section 3.1. This section discusses why
the system and components chosen for this project prevail over other options.
The system is most appealing for many reasons. The first being the first flush system is very low
maintenance and better at keeping the debris out of the system than the alternatives. When the floating ball
system is compared to the vertical pipe system, it has one clear advantage. Both systems can handle the 17
gallon capacity, but the floating ball system keeps any debris that has entered the filter in the filter, where
the vertical pipe system does not get closed off once filled up.
Next the angled screen filter allows any debris to slide off the filter to avoid clogging and is inexpensive to
install and replace. The cartridge filter would filter the smallest debris and is easily replaceable, but the
cartridge filter is expensive and requires more frequent maintenance.
The slanted box leaf screen when compared to the box screen and the cone leaf filter comes out on top
because the angle allows the leaves to slide off of the filter on their own where as the box leaf filter and
cone leaf filter would need to have the leaves removed on occasion to avoid clogging and flooding. While
the slanted box leaf screen filter takes up more vertical space than the other alternatives, its lower
maintenance requirement overshadows the lower water height in the 3000 gallon tanks, which are at nearly
the same height as the building.
PVC piping excels against the metal piping system and the open gutters for water delivery. The PVC piping
is closed to the environment to keep any extra debris from entering the system. The PVC is offered in larger
diameters to prevent clogging and the PVC has a larger resistance to heat transfer, which will protect against
freezing to a certain degree. Another distinct advantage to the PVC is that much PVC piping has already
been purchased by the sponsor, lowering the financial requirement for the water delivery.
The unicycle human interface design is ideal over the see-saw and merry-go-round, the main reason being
its size. Human pedaling is a very space efficient method for generating power. That is, it can generate the
most power per area that it takes up. Since the entire pump must fit into a 3x4x4 foot volume, this design is
much more practical. Bicycle components are also readily available and relatively easy to install. The
centrifugal pump is advantageous in this application because a constant flow and constant resistance are
generated. This makes use of the pedaling system much easier.
The main advantage with the holding tank and trough design is that it is visible. The filling of the holding
tank makes pedaling more interactive and engaging. It also allows for some control over how much total
water is delivered to the vertical garden.
4.2. Design Description
4.2.1. Collection System
The collection system includes the transport, drainage and collection of rainwater. It begins at the
downspouts of the building, including first flush systems and screen filters, and then ends with the tanks.
The system also includes overflow and drainage of the tanks. All drawings for the collection system
22
can be found in appendix C in drawings L1 through L6.
The water collected on the building’s roof passes through the existing screens above the downspouts.
Water first enters the first flush systems, which are at each of the five downspouts. Standard practice
for rainwater collection dictates that approximately 10 gallons per 1000 square feet of roof area are
diverted. Per this calculation, the first flush system must divert 17 gallons. To achieve this, the filters
will divide this load between the five downspouts; each first flush system should divert 3.4 gallons of
water. The first flush systems are floating ball systems, which can be purchased as kits. These include a
screw cap for cleaning, a drip valve for reset, and a floating ball. Each first flush system is 5 feet 6
inches long and is made with 4 inch PVC pipe. The system on the downspout on the outcropping will
be slightly shorter, 4 feet 10 inches, to accommodate the overflow from the 500 gallon tank. Using
simple geometry, the volume of a cylinder that is 66 inches tall and 4 inches in diameter is 829 cubic
inches. This is equivalent to 3.6 gallons. The smaller filter is 58 inches tall, and thus divert 3.15 gallons.
The total volume diverted by the five first flush systems is 17.6 gallons.
After the first flush diverters are full, water begins to bypass the filter and collect in the storage tanks.
The water flows through 3” schedule 40 PVC pipe to fill the tanks. The two downspouts on the north
side of the building, as well as the downspout on the building’s outcropping feed the 500 gallon tank,
which overflows to fill the 1650 gallon tank. The downspout on the outcropping contains a leaf beater
angled screen for demonstration purposes. Filling the 500 gallon tank first ensures the tank, which is
used for irrigating the living wall, is always be full. The water enters the tanks through a large opening
on the top. This opening contains a large 35 mesh screen to keep out mosquitoes and other fine debris.
The delivery to these tanks is illustrated in detail in drawings L2 through L4 in appendix C.
The two downspouts on the southern side of the building feed the two 3000 gallon tanks. The 3” PVC
pipes leave the main building at the southwest corner of the building. Two 45 degree joints direct the
pipes along a power pole, which is used to support the pipes leaving the building. The water enters the
east-most 3000 gallon tank as high as possible (approximately eight feet). It is directed into a pipe
reducer that is open to the air. Inside the reducer is a size 35 mesh screen to filter out small debris and
block mosquitoes and their eggs. This is illustrated in appendix C in drawing L5. The two 3000 gallon
tanks are connected underground to allow them to fill simultaneously. A T-joint is located along this
pipe, where a valve is attached to allow for draining. The tanks’ overflow connects to this pipe, which
feeds into the fountain. The fountain will overflow into a raingarden. The overflow from the 1650
gallon tank will also flow into this raingarden. The fountain and raingarden are out of the scope of this
design, and are being handled by the sponsor. This project simply sets up a drainage and overflow pipe
to be used for the fountain. Detailed drawings of the northern delivery and overflow can be found in
appendix C in drawings L5 and L6.
4.2.2. Pump
The pumping apparatus allows for the sustainable water demonstration to be interactive. The pump
consists of two sub-assemblies: the shaft assembly, and the centrifugal assembly. The shaft housing
consists of a casing, a ball bearing, a bearing cover plate, two thrush washers, a shaft seal, a pulley, and
a shaft. This sub-assembly is attached to the centrifugal assembly by four bolts and the shaft. The
centrifugal assembly consists of a hose inlet and outlet, two case halves, and an impeller.
23
Shaft housing assembly serves to provide support for the drive shaft and to apply pressure to a shaft seal,
to seal the interface between the shaft and the centrifugal casing. The bearing is a ½” x 1 ⅛ inch x 5/16
inch SR8-2RS rubber sealed stainless steel bearing. Although not directly exposed to rain or water
within the pump, this bearing is able to withstand much moisture and any outdoor operation. The shaft
case is an aluminum rod machined on a lathe to hold the bearings and provide pressure on the shaft seal.
It is anodized to protect it from oxidation. The case contains a flange for mounting to the centrifugal
assembly. A drawing can be found in appendix C, drawing P6. The shaft seal is used to prevent any
leakage through the interface between the shaft and the centrifugal case. It is designed to operate at a
height of 0.831 inches. The seal slides onto the shaft and is pressed against the case by the shaft casing.
The ½ inch shaft is constructed from a ⅝ inch stainless steel rod. It is threaded at the end, to allow for
bolting onto the impeller. Set screws are drilled through the impeller and the shaft to secure the
impeller. The pulley is machined from the same aluminum stock as the shaft housing. It is one inch in
diameter, to give the proper gear ratio of 10:1. It is secured with a Woodruff key and an e-clip. The
drawings for all parts in the shaft housing assembly are located in appendix C, drawings P5 through P8.
The centrifugal assembly is the part of the pump that is actually moving the water. The casing for the
pump is made of translucent polycarbonate. One half provides the location to bolt the shaft housing to
the assembly. The holes do not penetrate through, they are tapped and have helicoils inserted, to
improve longevity and prevent damage during maintenance. The second half contains a conical cutout
to fit the impeller. This half contains the inlet. The outlet is on a feature created by both case halves.
The casing is tapped to attach the hose fittings. Four bolts hold the case halves together. The bolt holes
contain a metal insert to prevent wear on the plastic. The case halves contain RVT liquid gasket to
prevent leakage. Drawings for the case halves can be found in appendix C in drawings P1 through P3.
The impeller is CNC machined from an aluminum disc. The part contains 6 curved vanes to channel the
water outward and a left-hand threaded tapped hole in the center allowing for the impeller to be attached
to the shaft. The impeller is anodized to prevent oxidation and for aesthetic appeal. The impeller is 4.5
inches in diameter which is the optimum diameter for the operating conditions (3 feet of water in the
tank, and a pumping height of 12 feet), calculated in appendix A. The part is designed to operate at
1000 - 1200 RPM which allows for adequate flow and delivers a pumping head of approximately 9 feet.
4.2.3. Human Interface and Power Generation
The human power interface includes a bicycle, a belt and pulley system, and a stand. The bicycle is of
medium size to accommodate men, women and age appropriate children. The rear tire of the bicycle is
removed and the wheel’s shaft is salvaged to attach the back of the bicycle to the rear stand. The rear
stand is manufactured from structural steel pipe, available at Home Depot for $8.2 for 10’, bent in the
formation shown in drawing P10, as well as 3/16”x1.5” flat steel bar, also available from Home Depot
for $6.52/4’, welded to the piping in two ways. The first is on the bottom of the stand for structural
support and to attach the pump, and secondly, plating is welded to the top and holes drilled in which to
attach the shaft recovered from the rear wheel. This creates a stable stand for the bicycle and allows for
pump attachment. A floor stand to stabilize the front tire may also be used if needed. This stand is
available from Gearup for $19.95.
24
The usual gear and sprocket system is replaced with a belt and pulley system, a 1” pulley attached to the
pump and a 10” pulley to the bicycle and pedals. This gives the 10:1 gear ratio, low maintenance, and
durability required. The belt size is not yet known, as the bicycle had not been purchased during the
design phase; however a V-belt is available from all local auto stores.
4.2.4. Living Wall Irrigation
Specific plans for the living wall had not been provided during the design phase, so the design for the
vertical garden irrigation system had been designed to be adaptable to the vertical garden’s geometry.
The set up was to be made from ½ inch PEX hose, which is strong and flexible to some degree. The
PEX hose would be fitted with a hose attachment at one end as an inlet, and would contain a plug at the
other end. The hose was to have a 1/16th inch hole every one inch along the pipe. The hose would wrap
around the living wall and water will drip onto the plants as the user pumps water into the hose inlet.
This system was to be retrofitted after the living wall had been constructed by a third party.
25
5. IMPLEMENTATION
5.1. Implementation Plan
Over winter break, the collection system was to be completed. Construction began December 13, 2010.
The collection system was to be completed by the beginning of January. All parts for the collection system
that were not currently in possession would be purchased at home depot, or ordered online between
December 6 and December 10. The sponsor for this project had already purchased much of the necessary
supplies for the collection system. These parts were not to be taken from the budget.
At least one team member would be in Corvallis working on construction with Hazen Parsons over the
break. Over the week of December 6, the city would mark all underground electrical wires. This is required
before pipes can be placed underground for filling the 3000 gallon tanks, and for draining. After all pipes
are placed underground and on the building, an inspector must first examine the system to make sure it is up
to code. After the system passes inspection, the system would be connected to the downspouts, and the first
flush systems put in place.
All parts for the pump would be ordered over winter break. The bearing (PMP003-5), thrust washers
(PMP003-4), shaft seal (PMP003-3), Woodruff key (PMP003-12), and all raw materials for the
manufactured parts are purchased locally. Almost all of the parts and materials are available for order
online or through a local vendor. The turnaround time for the parts and materials would be a maximum of a
few weeks. If ordered over the break, they would be available before the start of winter term.
Edgecam code for the impeller (PMP002-3) and case halves (PMP002-1 and PMP002-2) was to be written
and a jig would be constructed before winter term begins. Writing the NC code and manufacturing the jig
before the beginning of the term would allow for more time to machine parts, and to troubleshoot any
design or manufacturing errors. Dean Codo, a local machine shop owner who volunteered some space and
equipment for this project, would be contacted at the beginning of the break to discuss the use of his shop.
When winter term begins, the impeller, and two case halves NC code should be tested on the Bridgeport
mill using machinable wax. While this does add to the cost of the pump, it decreases the likelihood of
making an expensive mistake on the polycarbonate stock. This was to occur during the first week of winter
term. If the code contained any errors, these had to be fixed before the following week so that the impeller
can be machined. The casing for the pump would be machined from polycarbonate. The top and bottom of
the casing would be machined separately from 6 inch square stock of heights three inches for the bottom and
2 inches for the top case. The shaft housing assembly and shaft would be constructed during week two of
winter term also. The shaft casing (PMP003-2) would be fabricated on a lathe in the MIME shop, or in
Dean Codo’s shop. The bearing plate (PMP003-6) would be machined from a slice from the same stock
used on the shaft casing. The shaft (PMP003-1) would be made from ⅝ inch diameter stainless steel rod. It
would be machined on a lathe to precisely ½ inch. The more precise this diameter, the better the seal will be
at the interface between the shaft seal and the shaft. Once all parts have been machined, each of the pump
sub-assemblies (PMP002 and PMP003) would be assembled and joined to form the finished pump. The
26
pump was to be completed by the end of week 3 of winter term.
After the pump was to be completed, the assembly of the human interface (HPWASSEM) would be done.
The location of the pump on the stand depends on the bicycle (HPW001) that is purchased. The pump must
be constructed first so the drive pulleys can be aligned. The bicycle would be attached to a stand
(HPW0003) that allows the bicycle to remain upright with a stable base for ease of mounting and egress
from the riding position. The bike stand would be bolted directly to the frame.
The living wall is intended to be finished during winter break by a third party. Once the wall is built and
installed, the basic piping layout can be installed with it. This layout includes a vertical PVC pipe of ½”
internal diameter to be laid flush against the wall. It would be filled from the top by the output from the
pump. The bottom of the pipe should be sealed off and one hose fitting would be made horizontally from the
elevation of each of the tiers of the wall. As discussed above, the hose will have pre-drilled holes to allow
for the water to drip out at multiple points along the length of the hose.
The team was given a total budget of $1,500; $960.30 was allocated per the original Bill of Materials
(Appendix B). This included the piping that the sponsor already purchased, so the total cost would be far
under budget. The remaining $540 would be used for finishing of aluminum parts, testing, and a buffer for
troubleshooting any design issues.
5.2. Implementation Overview
5.2.1. Centrifugal Pump
Materials for the proposed team manufactured pump were purchased towards the end of winter break
and the beginning of winter term. Finding the materials was relatively strait forward, as most of the
materials were common. The one exception was the polycarbonate, which was difficult to locate. It was
purchased within the first few weeks of the term.
The initial pump, fabricated by the team, was made of 4 main body parts: top and bottom case halves
(PMP002-1 and PMP002-2), an impeller (PMP002-3) and a shaft (PMP003-1).
The shaft casing (PMP003-2) was the first to be manufactured. This was done on a lathe, and there were
no complications in the fabrication. The shaft (PMP003-1) was then manufactured from stainless steel.
This part was more complex, and after its completion, it was evident that the shaft needed to be longer in
order to properly attach to the pump and stand. The shaft was redesigned an inch longer, to allow for the
shaft collar that resided on a large support bearing. A pulley (PMP003-9) was made on a lathe from
aluminum, and was very easy to manufacture.
The top case half (PMP002-1) was fabricated from polycarbonate plastic to allow for viewing into the
pump, to keep the pump interesting by allowing visibility of how a centrifugal pump functions. The part
was drawn in SolidWorks and exported into Edgecam software to generate CNC machining code. The
code was run on a Bridgeport CNC machine, which is a computer controlled 3-axis milling machine.
27
The bottom case half (PMP002-2) and the impeller (PMP002-3) were machined in a similar fashion, but
were machined on a Fadal CNC, which has coolant capabilities to expedite the machining process and
allowed faster tooling speeds and a more streamlined operation.
After completing the CNC work, the pump had to be assembled. Woodruff slots were cut in the shaft
and key-ways were cut in the impeller and pulley. While assembling the pump, it was discovered that
attaching the impeller would be difficult, as there was little room between the impeller and the casing,
and the impeller had extremely sharp edges making it difficult to handle. This would also make
replacing the bearings and thrust washers a difficult task. The only design change on the pump that
occurred during the implementation process was shaft collars were used instead of e-clips to secure the
pulley and shaft.
5.2.2. Human Interface and Drive System
A standard road style mixte bicycle frame (HPW001) provides the human interface and the power to the
pumping system. A mixte bicycle frame was used as the top bar is lower to accommodate a wider range
of body types and sizes to allow the greatest number of people to use the pump. The frame was powder-
coated as opposed to painted because the finish is far more durable and thus helps to guard against
corrosion from the elements. From the original implementation plan, the team intended to use all v-belt
pulleys to drive the system, but fabrication and clearance difficulties drew the team towards using a
hybrid system that used both a chain drive and a a v-belt system.
The bike’s original chain drive system was used to drive a Shimano Deore disk brake rear hub with a
geared cassette (HPW003-1) on the proper side and a v-belt pulley attached in place of the disk brake on
the provided bolt pattern. The v-belt from the hub drives the pump. Gearing for the bicycle was initially
set at a 52:12 ratio for the chain drive and a 2.3:1 ratio between the v-belt pulleys to attain the intended
10:1 ratio between the rider’s cadence speed and the pump driving speed.
5.2.3. Piping Network
The materials for this portion of the project were purchased at the beginning of the break by Hazen
Parsons, a rainwater specialist who assisted with the implementation of the piping network. This was
done because of the industry connections Hazen held. The team was no longer responsible for this part
of the budget, by decree of the sponsor, and all funds allocated to the team were to be used on the
human-powered pump.
Implementation of the collection, delivery, and overflow piping began the first week of winter break.
The underground pipes that were used to connect the 3000 gallon tanks and provide drainage and
overflow were installed first with minimal difficulty. These were connected to the overflow pipe on the
east 3000 gallon tank. The drainage pipe then went into the fountain on site, which will overflow to a
rain garden. This part of the system is being developed by another party.
28
After the underground piping was installed, the first flush filters were assembled. 4 inch pipe was cut to
size and was used with the Rain Harvest™ first flush kits. The assembled first flush filters were
attached to the building with steel brackets and mason nails. After the first flush filters were installed, a
few weeks were taken off for the holiday season. After taking a break, the overflow from the 1650
gallon tank was completed, and the drainage for the rain garden was installed before the start of the
term.
After winter term began, the remainder of the piping was installed. All above ground pipes were
installed within the first three weeks of the term. The overflow from the 500 gallon tank into the 1650
gallon tank was completed several days before evaluation one.
Very little design changes due to implementation and fabrication were made on this system. One main
change was the filtering of the water. Originally, the team was responsible for meeting a 500 micron
filtering requirement. Because the purchasing of materials was no longer in control of the team, simple
mosquito netting was purchased as a filter for the 3000 gallon tanks, and insert screens were purchased
for the 500 and 1650 gallon tank. These filters did not meet the requirements established in fall term, so
a petition was filled in order to remove the filtering requirement from the project. The mosquito netting
used to filter water for the 3000 gallon tank was placed in line, sandwiched by a PVC couple. This filter
is more difficult to keep clear of debris, but less water height in the tank was lost with this method.
5.2.4. Living Wall Irrigation
As stated previously in the report, the living wall was to be constructed and implemented by another
party, and the team was to provide irrigation to the plants growing on the wall. This part of the system
was removed from the scope of the project because the living wall was not implemented within the time
frame that was expected.
5.2.5. Bike Stand
The initial design called for an aluminum stand (HPW0003) to reduce weight of the entire assembly.
The stand was created, but was scaled wrong from the SolidWorks drawing into the first iteration. The
stand would not support the weight of the bicycle and user. To solve this, a stand of simple geometry
was created from 1 inch square steel tubing of ⅛ inch wall thickness (HPW002). The bicycle attached to
the stand via a clamping system instead of the intended attachment point at the rear axle dropouts
because of a lack of clearance for the rear derailleur. This stand was sufficient for much of the initial
testing, but was very heavy and thus exceeded the weight requirement.
29
6. TESTING
6.1. Overflow
The overflow flow rate was tested with the use of a marked eight gallon bucket and a six gallon bucket. Six
gallons were measured out with the eight gallon bucket and transferred into the six gallon bucket. A
coupling on the overflow was removed, exposing the pipe. A makeshift funnel was inserted into the pipe.
One team member poured the water into the pipe, while another kept time on a stop watch.
Overflow 1 (1650 Gal): 38.40 seconds
Overflow 2 (3000 Gal): 52.80 seconds
The water drained with ease and the test was passed. The biggest obstacle was the test itself. Pouring water
from a bucket into a 3 inch diameter pipe is difficult, as it had a tendency to spill. The pouring was the
biggest limiter rather than the overflow piping.
6.2. First Flush Diverters
Each first flush filter was filled from the roof with the use of a five gallon bucket. One teammate listened at
the tank to hear water free falling to the bottom; once this occurred, it was known that the filter was full. A
marked eight gallon bucket was placed under the downspout and the drip valve on the filter was removed,
rapidly draining the filter into the bucket. The volume from each downspout was recorded and totalled.
The results are outlined below.
NE downspout: 16.5 L
SE downspout: 13.5 L
NW downspout: 17.0 L
SW downspout: 19.0 L
Outcrop downspout: 16.0 L
This totals to 82.0 L, or 21.7 gallons diverted. This is value is acceptable, and this requirement was met.
6.3. Pumping Head
The pump inlet was attached to a hose spout and the outlet hose was held at a height of ten feet. One team
member pedaled the pump, while another held the hose to the required height. Flow from the end of the
hose meant that the pump had met the pumping head requirement.
When first testing the pump, it was immediately apparent that it was not going to perform to our
expectations in its current state. Since centrifugal pumps usually operate more efficiently at higher speeds, it
seemed that the pump needed a higher RPM range in order to be effective, and thus a further gear reduction
was needed. This theory was reinforced when the hose was held lower, and water would flow lightly when
the user pedaled at an extremely high rate. The drive pulley that attached to the hub was redrawn for a target
50% RPM increase to a 15:1 ratio, which necessitated a 3.75 inch diameter drive pulley. The pulley was
30
made and the pump was tested again, but the pump still did not work effectively. Due to time and budget
constraints, as well as a fear that the pump’s inherent design would not work in any RPM configuration, the
team opted to purchase a pump and retrofit it to the project. A pump was generously donated by Joe
Richard, of JTI Supply, Inc.
The commercial pump is a peristaltic, or roller pump. It operates in a wider range of speeds and thus was
ideal for this project in the sense that it operated within the range that the bike was set up to ride in already.
Peristaltic pumps operate via 6 rotating chambers that contact the sides of pump cavity, thus sealing off 6
volumes within the chamber. As the pump runs, the inlet water is pulled into the pump via the low pressure
created by the expanding volume of each chamber. The exit condition operates on nearly the same principle.
As the water exits the pump, its flow creates a low pressure at the exit location and effectively draws the
water out of its respective chamber.
The pump has no chance of back flow from the exit, requires no priming, and drains simply by operating the
pump without the inlet hose attached to the water source or pumping air through the system. In addition, the
wide RPM range allows the drive system to operate without a derailleur to shift gears.
Upon testing the new human-powered pump, it vastly exceeded the pumping head requirement. At a height
of ten feet, water flowed with ease from the outlet.
6.4. Aesthetics
The sponsor, David Eckert, and Michael Viliurdes from the First Alternative Coop inspected the pump
thoroughly for any blemishes, visible glue, our sharp edges. A form was provided to report any issues and
for their signatures. Zero issues were found on the human-powered pump and this test proved successful.
6.5. Usability
Over the span of the maintenance test, five individuals were asked to help operate the device. Their times
were recorded on the time log used for the maintenance test. This gave usage times for five random users.
Of the people that operated the pump, no one operated it for less than 10 minutes. This test was passed.
6.6. Maintenance
The team set up the pump at a team member’s house. A large cooler was filled with water. The inlet and
outlet hoses both went into the cooler of water, to allow for recirculation. A usage log was started and the
team operated the device, recording times. The team also had other individuals operate the pump and log
their usage. This had to total over eight hours, without any maintenance on the pump, the bicycle, or the
stand.
9.05 hours were logged on the pump with out maintenance,and the test went well. The only difficulty lied
in the hoses and the holding tank. The hoses had a tendency to kink, so they had to be flattened
occasionally. The inlet hose would suction to the side of the cooler, stopping flow for a short time. Apart
from these minor hick-ups, there were no issues involved with this test.
31
6.7. Weight
One team member held the pump and stood on a bathroom scale and weight was recorded. The weight of
the team member without the pump was then recorded. The difference in these weights had to be less than
45 lbs to satisfy this requirement.
The first testing of the device gave a weight of 50 lbs. The first human-powered pump did not satisfy the
weight requirement. This was due largely in part to the stand used to hold the rear of the bike up. the stand
was made from ⅛ inch thick steel tubing, which made the bike heavy and cumbersome.
For the final bike stand, the weight was cut in half by using 1/16 inch thick steel tubing. The same design
from the previous stand was used, but with rear dropouts to allow for a mounting point to the bicycle at the
axle. A slotted mounting plate was welded to the base of the stand which allowed the pump to be attached at
different locations. This allowed for the V-belt pulley to be tensioned properly during assembly. The weight
of the device was tested a second time. It weighed 42 lbs and passed the weight requirement.
6.8. Draining
The team attempted to drain the pump without any tools by removing the outlet hose, and disconnecting the
inlet hose from the water source. One team member pedaled the bicycle and the pump was drained in this
manner, and the drainage requirement was met.
6.9. Sizing
The team arranged the human-powered pump into a compact configuration for storage, by turning the tire
sideways. One team member used a tape measure to measure the largest dimensions in height, length, and
width. The results are as follow.
length: 4 feet, 1½ inches
width: 2 feet, 2 inches
height: 3 feet, 1 inch
These dimensions are within the tolerances specified in the house of quality, and the device met the sizing
requirement.
6.10. Entertaining
The team asked for volunteers to ride the bicycle for about five minutes and report the entertainment value.
In the amount of time remaining for the project the team was able to find five volunteers and all five
reported the pumping exercise as entertaining, however with a requirement of seven out of ten reviews to be
positive the team was two volunteers short of success. This test was failed by the team due to lack of
volunteers.
32
6.11. Delivery
Eight feet was measured on the building with a tape measure. One team member stood on the 1650 gallon
tank and held a bucket and the hose outlet at that height. Another team member operated the human-
powered pump, while a third kept time. The time to fill the bucket and the bucket volume were used to
calculate the flow rate in gallons per minute.
The required volumetric flow rate was calculated to be 0.69 GPM based on the tank geometry. Using a four
gallon bucket which was filled in one minute, giving a flow rate of 4 GPM at eight feet, surpassing the
requirement, and the test was passed.
33
7. BIBLIOGRAPHY
Bump, John. (1999, Feb 1). Bicycle efficiency and power -- or, why bikes have gears. [Online].
Available: <http://users.frii.com/katana/biketext.html>
Coxworth, Ben. (2010, June 1) Student invention lets Guatemalans pump water on the go. [Online]
Available: <http://www.gizmag.com/mobile-bicycle-powered-water-pump/15281/>
Ersson, Ole. (2005, Jan) Ersson Rainwater Harvest and Purification. [Online]
Available: <http://www.appropedia.org/Ersson_rainwater_harvest_and_purification_%28original%29>
Igor J. Karassik, Joseph P. Messina, Paul Cooper, Charles C. Heald. Pump Handbook, 4th
ed. McGraw-Hill.
2008.
REUK. (2007, Jan 29). First Flush System Rainwater Harvesting. [Online]
Available: <http://www.reuk.co.uk/First-Flush-System-Rainwater-Harvesting.htm>
Rupp, Gretchen. (1998, Dec) Rainwater Harvesting Systems in Montana. [Online]
Available: <http://www.builditsolar.com/Projects/Water/MSUExtnRainwaterCatchmentmt9707.pdf>
Storm Water Solutions. (Accessed 2010, Oct 17) Case Study: OSU Rainwater Reclamation [Online]
Available: <https://docs.google.com/viewer?url=http://www.oeconline.org/our-work/rivers/rivers-
files/stormwater-case-studies/LID_CaseStudy_OSU_KelleyEC.pdf>
Torrone, Phillip. (2006, July 15). PlayPumps - Kid powered merry-go-round water pumps. [Online]
Available: <http://blog.makezine.com/archive/2006/07/playpumps_kid_powered_mer.html>
34
8. APPENDIX A: ENGINEERING CALCULATIONS
A.1. Pump Sizing Calculations
This procedure is outlined in Karassik. It is used to find the optimum impeller radius based on the pump head,
the desired flow rate, and the rotation rate that the pump will operate at. The procedure will be as follows. The
first step is to determine the desired flow rate, the pumping head, and the impeller RPM. After these are found,
non-dimensional pump parameters are calculated. These are used to find the optimum radius, based on
accepted engineering practice. A MATLAB program was written using this procedure to vary flow rate and
rotation rate of the impeller and see how the required radius changed.
Equations Used
(1) 2 1H H H Pumping Head
(2)2
2
P VH Z
g g
(3) P gh Pressure at the bottom of a water column
(4)30
N Angular speed, where N is the RPM value
(5)3/452.92
s
N Q
H
Specific speed
(6)
1/4
1/2
0.4 for Ω 1
0.4 for Ω 1
s s
s s
Head coefficient
(7)1
impeller
g Hr
Impeller radius based on required pumping head and flow rate
Solution
The first step is to determine the flow rate, pressure head, and impeller angular velocity. The flow rates used
range from 1 to 5 gallons per minute. The RPM values range from 500 to 1200 RPM. The operating conditions
for these pump calculations are 1m of water in the tank, and a required pumping height of 4m.
1 tan kP gh
2 2
2 2 1 12 1 2 1
2 2
P V P VH H H Z Z
g g g g
P2 is atmospheric pressure; V1 is assumed to be zero, as the change in height of the tank level is very small in
comparison to the velocity at the hose outlet; Z1 is also zero, as it is the height of the pump. This simplifies to
the following when the velocity is replaced with the volumetric flow rate and hose diameter.
35
2
122
1 4
2
PQH Z
g D g
After the required pumping head is calculated, the non-dimensional pump parameters must be calculated.
These are done by using equations (5) and (6), and known variables to find the specific speed and the head
coefficient. The head coefficient is then used in conjunction with the angular speed and pumping head in (7) to
find an ideal radius.
This is done for a range of volumetric flow rates and rotational speeds using a MATLAB program. The results
are plotted and pump geometry can be decided from the plot.
Results
From figure A1, a diameter of 4.5 inches was chosen. This allows for a minimal diameter with design target of
a rotational speed of 1000 to 1200, which is reasonable for gearing with a bicycle. Using a gear ratio 10:1, this
speed would be attained for a comfortable cruising speed of 100 to 120 RPM. This speed is near when people
generate their maximum power on a bicycle. As shown in figure A2, maximum power is generated between
100 and 170 RPM. If the cyclist were to pedal faster, this would increase the pressure head and flow rate of the
pump. An impeller diameter of 4.5 inches will ensure that the majority of users will be able to pump water to
the required height at a reasonable flow rate.
Figure A1: Impeller Diameter vs. RPM
36
Limitations
As stated previously, these equations and this procedure came from Karrasik. The optimum radius came from
experimental data for industrial pump design. For this application, the specific speed required was relatively
low. A centrifugal pump is not the most efficient pump type for this application and as such, the specific speed
values were at the lower end of the spectrum on the experimental data. The head coefficient could contain some
degree of inaccuracy by being towards the lower end of the data.
A.2. Pump Power Requirements
The ideal power requirement for the pump is based solely on the pumping head and the mass flow rate. The
power requirement in actual application also depends greatly on the pump efficiency (as the power requirement
is infinite for a pump of 0% efficiency, and drops as the efficiency moves toward 100%). This calculation uses
one simple equation, the definition of pump efficiency.
pump
s
g Hm
P
Pump efficiency (Karassik)
Rearranged for power:
s
pump pump
g Hm g H QP
The MATLAB program used to calculate the pump diameter was also used to plot the required power against
the pump efficiency.
Figure A2: Power Curves for Different Cyclists (Source: Bump)
37
Results
From figure A3 and figure A2, it is clear that bicycle power will be sufficient for most users to irrigate the
living wall, given the pump is of reasonable efficiency. Even at low efficiencies, pumping at low flow rates
requires little power. It can be stated with confidence that bicycle power will be sufficient to pump water to the
living wall.
Figure A3: Power vs Pump Efficiency for flow rates of 1,2,3,4,5 GPM
38
MATLAB Code for Pump Calculations
Main Program
%PUMP ANALYSIS MAIN PROGRAM
clc
clear
close all
%Define Operating Conditions
htank = 1;
h2 = 4;
D = 0.019;
%Define Variables
n=[1:1:5]; %in GPM
Q = (6.309E-5)*n; %Convert to m^3/s
N = [500:50:1200];
Speed = N*pi/30;
eff = [0.2:0.05:1];
%Initial Pump Parameters
P(1) = 998.2*9.8*htank; %Pressure at Pump Inlet
P(2) = 0; %Atmospheric Pressure
V(1) = 0;
Z(1) = 0;
Z(2) = h2;
for i = 1:1:length(Q)
V(2) = 4*Q(i)/(pi*D^2); %Velocity at outlet (based on flowrate)
dH(i) = Head_Calculator(P,V,Z); %Calculate Head
%Calculate Pump Parameters
[S_Speed(i,:), S_Head(i,:),S_Flow(i,:)] = Pump_Params(N,Q(i),dH(i));
r(i,:) = (1./Speed).*(9.8*dH(i)./S_Head(i,:)).^(1/2);
D_imp(i,:) = 2*39.37*r(i,:); %convert from meters to
inches
%Plot the diameter v RPM
figure(1)
hold on
plot(N, D_imp(i,:),'k')
grid on
xlabel('RPM')
ylabel('Impeller Diameter')
title('Impeller Diameter vs. RPM')
%Plot the power requirement
Ps = 9.8*dH(i)*998.2*Q(i)./(eff);
figure(2)
hold on
plot(eff*100, 0.00134*Ps,'k')
title('required power vs. efficiency')
xlabel('efficiency (%)')
ylabel('power (HP)')
grid on
end
39
Head_Calculator.m
%HEAD CALCULATOR
function H = Head_Calculator(P, V, Z)
%P, V, Z are vectors used to calculate the pressure head for WATER ONLY!
%All Units are in Metric and STP is assumed
H = (P(2)/(998.2*9.8) + V(2)^2/(2*9.8) + Z(2)) - (P(1)/(998.2*9.8) + V(1)^2/(2*9.8) +
Z(1));
end
Pump_Params.m
%PUMP PARAMETER CALCULATOR
function [Spec_Speed, Head_Coeff, Flow_Coeff] = Pump_Params(N, Q, dH)
Spec_Speed = N*sqrt(Q)/(dH^(3/4)*52.919);
Flow_Coeff = 0.1715*sqrt(Spec_Speed);
if(Spec_Speed < 1)
Head_Coeff = 0.4*Spec_Speed.^(-1/4);
else
Head_Coeff = 0.4./sqrt(Spec_Speed);
end
end
40
9. APPENDIX B: BILL OF MATERIALS
Bill of Materials for Original Design LVL PART # DESCRIPTION COST QTY TYPE VENDOR DRAW#
A PMPASSEM Human Powered Pump Assembly $557.09 1 Assembly N/A Total Project Cost $960.30
B PMP001 Pumping Mechanism $353.41 1 Assembly N/A P0
C PMP002 Centrifugal Assembly $269.77 1 Assembly N/A
D PMP002-1 Front Casing Half $68.03 1 CNC Professional Plastics P1-P2
D PMP002-2 Rear Casing Half $149.82 1 CNC Professional Plastics P3
D PMP002-3 Impeller $49.04 1 CNC Online Metals P4
D PMP002-4 Plastic Threaded Hose Fitting $1.98 2 Purchased Home Depot
D PMP002-5 1/4"-20 x 2.5" Bolt $0.41 1 Purchased *Readily Available*
D PMP002-6 1/4"-20 x 1.5" Bolt $0.37 3 Purchased *Readily Available*
D PMP002-7 1/4-20 Nut $0.07 4 Purchased *Readily Available*
D PMP002-8 1/4" Washer $0.05 8 Purchased *Readily Available*
C PMP003 Shaft Assembly $83.64 1 Assembly N/A
D PMP003-1 Pump Shaft $5.99 1 Manufactured Online Metals P5
D PMP003-2 Shaft Casing $27.90 1 Manufactured Online Metals P6
D PMP003-3 Shaft Seal $16.08 1 Purchased Drillspot
D PMP003-4 Thrust Washer $1.70 2 Purchased Amazon
D PMP003-5 Shaft Bearing $8.95 1 Purchased Bearings Direct
D PMP003-6 Bearing Plate $4.65 1 Manufactured Online Metals P7
D PMP003-7 1/4"-20 x 0.625" $0.23 4 Purchased *Readily Available*
D PMP003-8 1/8"-44 x 0.375" Machine Screw $0.19 6 Purchased *Readily Available*
D PMP003-9 Drive Pully $13.95 1 Manufactured Online Metals P8
D PMP003-10 1/2" E-Clip $1.68 1 Purchased Fastenal
D PMP003-11 3/8" E-Clip $1.92 1 Purchased Fastenal
D PMP003-12 #204 Woodruff Key $0.40 1 Purchased Robnett's Hardware
B HPWASSEM Human Interface $203.68 1 Assembly N/A
C HPW0001 Refurbished Used Bicycle $101.84 1 Purchased Craigslist
C HPW0002 Front tire stand $19.95 1 Purchased Gear Up
C HPW0003 Rear Bicycle stand $42.89 1 Assembly N/A P10
D HPW0003-1 Allied Tube & Conduit 1/2 In. x 10 Ft. $8.20 1 Purchased Home Depot
D HPW0003-2 1/8" flat steel bar48 in. x 1-3/8 in. x 1/8 in. $6.52 1 Purchased Home Depot
D HPW0003-3 36 in. x 1-1/2 in. x 3/16 in. Steel Flat Bar $28.17 3 Purchased Home Depot
C HPW0004 Belt and pulley system $39.00 1 Assembly N/A
D HPW0004-1 10" pully $19.00 1 Purchased Chicago Die Casting
D HPW0004-2 Drive Pully $13.95 1 Manufactured Online Metals P8
D HPW0004-3 V-Belt $10.00 1 Purchased Auto Store
A PL000 Piping Network $349.31 x Assembly N/A L1-L6
B PL001 3" PVC 90 Joint $38.76 17 Purchased Home Depot
B PL002 3" PVC 45 Joint $10.16 4 Purchased Home Depot
B PL003 3" PVC T-Joint $9.24 3 Purchased Home Depot
B PL004 First Flush System $232.75 5 Assembly N/A P9
C PL004-1 First Flush Kit $149.75 5 Purchased Rainharvest
C PL004-2 3"x4" PVC Reducer $45.50 7 Purchased Home Depot
C PL004-3 4" PVC Pipe $37.50 30 Purchased Home Depot
B PL005 2” 90º Joint $1.17 5 Purchased Home Depot
B PL006 2' T Joint $1.78 1 SPONSOR Home Depot
B PL007 2" x 3" Reducer $13.40 1 SPONSOR Home Depot
B PL008 2" PVC Pipe $1.11 43 SPONSOR Home Depot
B PL009 2" PVC Valve $11.95 1 Purchased Home Depot
B PL010 1/2" x 25' PEX Hose $6.95 1 Purchased Home Depot
B PL010 Spigot Valve $22.04 4 Assembly N/A
C PL010-1 Spigot Valve $12.20 4 Purchased Home Depot
C PL010-2 Threaded Hose Coupler $3.96 4 Purchased Home Depot
C PL010-3 Threaded PVC Stud $1.96 4 Purchased Home Depot
C PL010-4 PVC Bolt $3.92 4 Purchased Home Depot
B PL011 Tank Filter 1 Assembly N/A L7
C PL011-1 Leaf Filter 1 Manufactured L8
C PL011-2 Fine Filter 1 Purchased Utah Biodiesel
C PL011-3 Hose Clamp $1.00 1 Purchased NapaA MISC001 Machinable Wax Block $53.90 2 Purchased Grizzly
Total Project Cost $960.30
41
Final Bill of Materials
LVL PART # DESCRIPTION COST QTY TYPE VENDOR DRAW#
A PMPASSEM Human Powered Pump Assembly $410.12 1 Assembly N/A
B PMP001 Hypro 6500c roller pump $140.00 1 Assembly JTI Supply, Inc
B HPWASSEM Human Interface $270.12 1 Assembly N/A
C HPW001 Powdercoated Used Bicycle $120.00 1 Purchased Craigslist
C HPW002 Rear Bicycle stand $50.28 1 Assembly N/A P10
D HPW002-1 Steel Base Piece $26.63 2 Manufactured N/A
D HPW002-2 Steel Cross Support $13.32 4 Manufactured N/A P11
D HPW002-3 Steel Plate $5.00 1 Machined N/A P12
D HPW002-4 Middle Support $3.33 1 Manufactured N/A
D HPW002-5 Bracket $2.00 2 Manufactured N/A P15
C HPW0003 Belt and pulley system $99.84 1 Assembly N/A
D HPW003-1 Shimano Bicycle Hub and Cassette $69.90 1 Purchased Corvallis Cyclery
D HPW003-2 Drive Pully $13.95 1 Machined N/A P13
D HPW003-3 V-Belt $5.99 1 Purchased NapaD HPW003-4 Pump Pulley $10.00 1 Manufactured N/A P14
A PL000 Piping Network $283.46 x Assembly N/A L1-L6
B PL001 3" PVC 90 Joint $38.76 17 Purchased Home Depot
B PL002 3" PVC 45 Joint $10.16 4 Purchased Home Depot
B PL003 3" PVC T-Joint $9.24 3 Purchased Home Depot
B PL004 First Flush System $187.25 5 Assembly N/A P9
C PL004-1 First Flush Kit $149.75 5 Purchased Rainharvest
C PL004-2 4" PVC Pipe $37.50 30 Purchased Home Depot
B PL005 2” 90º Joint $1.17 5 Purchased Home Depot
B PL006 2' T Joint $1.78 1 SPONSOR Home Depot
B PL008 2" PVC Pipe $1.11 43 SPONSOR Home Depot
B PL009 2" PVC Valve $11.95 1 Purchased Home DepotB PL010 Hose Spigot $22.04 4 Assembly N/A
Total Cost $410.12
Rem
oved
fro
m B
ud
get
42
10. APPENDIX C: PART DRAWINGS
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
PVC
60
61
62
63
64
65
66
David Eckert ____________________________
Nancy Squires ____________________________
Bryan Dripps ____________________________
Mike Henderson ____________________________
Heather Reinhart ____________________________