Final Report

Table of Contents

  • 1.0 Introduction
  • 2.0 Evaluating Rain Water System Sustainability
  • 3.0 Purpose and Goals of Rain Water Study
  • 4.0 Parameters of the Rain Water System
  • 5.0 How the Rainwater System Works - Weigle's Model
  • 6.0 Benefits of the Rain Water System In ESE Building
  • 7.0 Costs of Implementing Rain Water System for ESE Building
  • 8.0 Limitations
  • 9.0 Recommendations
  • 10.0 Conclusion
  • References
  • Bibliography
  • Appendices

    1.0 Introduction

    It is impossible to turn back the clocks and live the way our ancestors did thousands of years ago, but changes in our current lifestyles and the way in which we view the natural world can help us to achieve a more sustainable environment. Sustainable development can be both a conceptual framework and a goal for maintaining and achieving sustainability. The Bruntland Commissionhas provided the necessary objective for sustainable development, "to meet the needs of the present without compromising the ability of future generations to meet their needs," but this is only the goal of sustainable development, it is not a solution nor is it a framework from which to build a sustainable environment.

    Fresh water is one of our most important natural resources as it is necessary for survival and lacks a substitute. We depend on water for survival as well as for our convenience; we drink it, cook with it, wash with it, travel on it,and an enormous amount is used for the purposes of agriculture, manufacturing, mining, energy production, and waste disposal (Environment 264). Therefore, with respect to sustainability, maintaining the quality and quantity of water is a top priority.

    Water covers approximately three-fourths of the earth's surface, creating many problems for water management and the implementation of water conservation technologies (Environment 264). However, from a community level many water saving tactics can be implemented to conserve this most precious natural resource.

    In light of the new building, the future Centre for Environmental Science and Engineering (ESE building), scheduled to open in 1998, has provided an opportunity for a WATgreen team to initiate the study of a rain water system for the building. The results of this study could lead to the incorporation of a rain water system into the plumbing of the ESE building.

    The proposed rain water system would involve using rainfall that would otherwise be collected as surface runoff and channeled through the Region of Waterloo's storm water sewer system eventually leading to the Grand River and other small tributaries. With a rain water system, 'free' rainwater would instead be stored in a rain water storage or retention tank and then used for flushing toilets, which does not necessitate the use of clean chemically treated water. The use of a rain water system on the University of Waterloo campus not only promotes water conservation, but it also promotes an aspect of sustainable development of such an irreplaceable resource.

    In turn, it is the task of the WATGreen team to examine the feasibility of a rain water system for the ESE building. Considering a significant component of sustainability is related to economic concerns, both a bio-technical and a socio-economic study will be performed Prior to the performance of any such studies however, it is necessary to first identify the components of the rain water system itself. The WATGreen team has made it their goal to identify components of the rain water system that are only the most "environmentally" efficient. That is, each of the components identified will use as little energy, water as is possible, while minimizing costs and waste generation.

    The physical components of the new building's rain water system will consist of: the retention tank used for rainwater storage, the plumbing system which will channel the water to the toilets and channel contaminated water to sanitary sewers, a connection to the sanitary sewer system to remove the waste or sewage from the system, a storm sewer connection in case of overflow in the retention tank due to excessive precipitation, and 6 litre toilets or the smallest possible flush toilet available on the market to reduce the amount of water expended by flush toilets.

    The inputs into the system will depend on the climate and seasonal conditions in the Waterloo area. Rainfall will be the prime input into the system, however some energy will be required to operate the pump, which will pump the water from the retention tank to the toilets.

    After all of this has been completed, what will it all mean to the University of Waterloo? Simply, the inclusion of a rain water system in new developments on campus will promote development which is sustainable, and if the system is incorporated into the design of the building, the University of Waterloo may be regarded as an environmental pillar of the community. In other words, UW would be setting the standards for future developments, not only on campus, but for the Kitchener-Waterloo community and beyond.
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    2.0 Evaluating Rain Water System Sustainability

    In order to study this system, it becomes necessary for the WATGreen team to determine what approach or perspective will guide them through the system study. It is necessary to adopt a specific approach so as to focus the study and avoid being sidetracked. Similarly, in adopting an approach early on in the study, direction is established within the study and wasted time on unnecessary information is avoided.

    A rain water system is a means of water conservation and involves the implementation of a unique plumbing system thus, the study will be completed from a conservationist/technical perspective. The conservationist's perspective works toward achieving the optimal use out of existing resources, while attempting to minimize the use of additional inputs into the system. The technical aspect of the perspective aims at designing a technically feasible plumbing system that incorporates the conservationist framework outlined above. These approaches set the framework from which sustainability will be evaluated because in order for the development of the new building and the plumbing system in particular to occur, integration of a natural resource (water), and integration of human technologies will have to be implemented in a sustainable manner.

    The sustainability framework will be based on both a financial study and an ecological savings study. The financial study will determine the predicted monetary savings to the University of Waterloo for treated water consumption versus the implementation of a rain water system. The ecological savings study will be determined by the rain water system infrastructure and the amount of rain water used instead of chemically treated water. Also, the amount of contaminated water channeled to the Region of Waterloo's sewage treatment plant will also be assessed.

    As analysts of the possibility for a rain water system within the new building, it becomes necessary for the WATGreen team to know to whom the issue is of concern and who has some stake in the development of such a system. Actor systems are comprised of both the main persons or stakeholders in an issue and the social rules and power structure in which they operate. These are the people who are affected directly or indirectly by a problem and who may have a vested interest in its outcome. Actor systems can include core actors who are at the centre of an issue, supporting actors who are less involved but can exert influence over an issue, and should-be actors who may be affected by a problem or its solutions but are unable to participate in problem resolution or who are unaware of the issue (University of Waterloo).

    Within the realm of this system study, it is vital to consider the roles of the members of the community that will be affected in any decisions or developments. The inclusion of these actors will allow the development of the new building to be accepted by the community. For example, we feel the listed actors below will, or should be involved in the development of the plumbing system of the ESE building. Their stake in the matter is described in detail following their listing below:

    Click here for more info on these groups

    The roles of these actors is critical to the study of the system. For example, the role of the students is to assess the feasibility of a rain water system in the ESE building. The plant operations staff are responsible for the technical aspects and the maintenance of the system, and the New Building Committee will be responsible for the implementation of a rain water system into the cost and design of the building, as are the architects and contractors.

    The supporting actors should influence the core actors to implement a rain water system. Weigle Reality should encourage the University of Waterloo to implement a rain water system into the ESE building because of the success they have in their condominium complex, which has a rain water system incorporated into its design. The Region of Waterloo should encourage the core actors to incorporate any environmental technologies into new developments to sustain the Waterloo community.

    The should-be actors are mainly the financial sponsors of the new ESE building. For example, private donors and the provincial government who are mainly providing the funds for the building should have a say in the design of the building and it's environmental standard. The students and WPIRG should be concerned about what the University of Waterloo is constructing on campus and in light of the attention the natural environment is receiving in the 1990s the students and WPIRG should make sure that the UW only promotes the most environmental technologies available.
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    2.1 Criteria to Evaluate the Feasibility & Benefits of a Rain Water System

    The first criteria used to evaluate the system will be the precipitation levels which occurred in previous years, and recorded at the University of Waterloo. The second criteria will be the flushing demands of toilets in the environmental science and engineering buildings. The last four criteria will be used to formulate a Cost-Benefit Analysis. Theses four criteria will be:
    1. energy requirements to operate the pump
    2. the costs of water necessitated by present flushing demands
    3. the costs for the over all implementation of the rain water system
    4. the cost for maintaining a rain water system over the long-term
    In order to evaluate the feasibility of the system, the precipitation will be measured and the flushing demands will be monitored. The precipitation data will be obtained from the Larry Lamb ecology lab located on the University of Waterloo campus. This precipitation data is an extremely important aspect of the system as it will indicate whether or not enough rainfall is present in one year to meet the flushing demand. Similarly, it will indicate how much treated water will be needed to compensate for the difference in rain water and flushing demand if it is found that not enough rain falls in one year to meet the flushing needs of the new building. The flushing demands at the University of Waterloo will be measured via counting the average number of flushes in an 8hr. day. The information required to complete a CBA will be obtained from the University of Waterloo's Plant Operations department, from Paul Weigle a contractor and supporter of rain water systems, and from the new building committee.
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    3.0 Purpose and Goals of Rain Water Study

    The roles of humans within this issue has been already discussed. It is ironic that this WATGreen team of 1995 are faced with a task of redesigning a system which will replace a plumbing system that was designed by humans and accepted for so many years. Directing rain water to a storm sewer may have seemed like a solution to the causes of excessive overland flow as a result of human developments. Because humans have created many impermeable surfaces into the natural system, humans have also had to create a system to redirect the surface runoff or overland flow. Therefore, in trying to rectify the problem environmental engineers have devised a system to remove rain water from roof tops and other concrete and asphalt surfaces.

    However, in trying to remedy the problem of overland flow, rainwater has needlessly been redirected to rivers and other water bodies. To a certain degree this water is necessary to replenish the hydrological cycle, but some of the rainwater can be redirected for use in buildings that would otherwise require chemically treated water. Therefore, the purpose and goals of this study is to:

    1. Determine the amount of water needed to flush toilets in a building the size of the ESE building.
    2. Determine the amount of rainwater that could be accumulated on an annual basis.
    3. Evaluate possible storage methods for the rainwater (ie. the size of the retention or storage tanks).
    4. Examine a suitable plumbing system with the inclusion of 6 litre toilets or the lowest possible flush toilets available on the market.
    5. Determine the present costs for supplying chemically treated water for flushing toilets.
    6. Determine initial costs of implementing a rain water system in the new buil$

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    4.0 Parameters of the Rain Water System

    While studying the inputs and outputs of the system, it is extremely necessary to focus on the system's boundaries so as to avoid the unnecessary inclusion of irrelevant or inapplicable data. The dimensions of the new ESE building will be approximately 148 000 square feet, which will be approximately the size of the present psychology building located on the Waterloo campus. The size of this new building is relevant in determining the potential amounts of rainwater that could be accumulated from the collection surfaces. The larger the building, the more collection surfaces that could be located. The environment of the system is enclosed within the structure of the building, allowing inputs from the physical environment. The environment includes the collection of rainwater from the roof of the building and all balconies or patios, and the plumbing which will include the most efficient toilets suitable for non-residential use, and the retention tank or cistern. The size of the cistern which will supply the water needed by the flushing of toilets, will be a function of the flushing demand of the new building as well as the amount of rainfall per year.

    The system is dependent on the initial inputs into the system (rainwater). However, in order to have a reliable system it is necessary to have a backup source in order to provide for maximum efficiency in the event that sufficient amounts of rainwater to meet the flushing demands does not fall. Therefore, a connection to treated water supplied from the Region of Waterloo, which will also provide water for any other plumbing component in the building such as sinks, will fuel the system when needed. The main feature of this system is to reduce the stress on water use on the University of Waterloo campus and the system will benefit the environment by producing less stress on the sanitary sewer system and eliminating waste more efficiently.
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    5.0 How the Rain Water System Works - Weigle's Model

    The workings of the rain water system to flush toilets is really much simpler than it may appear. Rain water/snow melt is first of all collected from every available rooftop, patio or balcony. Patio stones cover these surfaces entirely and are spaced approximately 2.5 cm above underlying pads. Separating the patio stones from the pads is a layer of gravel which facilitates the infiltration of the water. Drains are located at the corners of the rooftop/patio/balcony feeding down into a main artery which channels rain water into the awaiting concrete cistern.

    The main artery feeds the concrete cistern from a hole located towards the top of the tank. The cistern is lined with rubber to prevent the adverse corrosion effects of the acid rain. A float valve is located within the cistern to detect low rain water levels. In the event that insufficient amounts of rain water are being fed into the cistern, a backup system which pumps city water into the tank exists. The city water is fed in through a separate pipe by way of a shower head to avoid a bacteria transfer between the rain water and already treated city water.

    Within the cistern there is an aeration system to oxygenate the water to prevent stagnent odours. This system is triggered daily by and automatic timing device. There is also a disturbulation system to circulate any sediment that may collect on the bottom of tank. According to Paul Weigle, in three years of use, this system has never needed to be used. It has been placed there for long-term maintenance of the entire rain water system. Pumps and pressure tanks serve to pump the water from the cistern to toilets and lawn sprinklers. To achieve maximum efficiency, the pumps are located beneath the water level in the cistern. Therefore the pumps only have to function for approximately 30 minutes each day.

    The system proposed for the ESE building is similar to Paul Weigle's system, differing only in it's use and perhaps size. While Weigle's system is used for flushing toilets, lawn irrigation, and washing vehicles; the system proposed for the ESE building will limited to flushing toilets.
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    6.0 Benefits of the Rain Water System In ESE


    6.1 Economic Benefits

    There are two main costs incurred when city water is imported to the university to flush toilets. There is a charge for water consumption which at the time of the study was .68/cubic metre. Also incurred, is a sewage consumption charge of .72/cubic metre (City of Waterloo,March 1,95). Using a rain water system, both of these costs would be eliminated as no water is being imported, it is assumed that no sewage consumption charge can be totalled (Kay,March 28,95). The university would only be charged for the city water pumped in to compensate for low rain water levels during dry times of the year.
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    6.2 Environmental Benefits

    While the economic benefits outline the affordability of a rainwater system to flush toilets, there are environmental benefits that justify implementing such a system. First of all, by re-using rainwater, the demand is ruduced on the regions already scarce water resources (Mitchell Feb. 28, 1995) Secondly, because of the acidic composition of rainwater, the need to chemically treat and deoderize toilet water is eliminated. Acid rain fails to stain toilets and similarly wards of bacteria that previous toilet sanitation products were needed to eliminate (Weigle March 7 1995). Lastly the use of low flush toilets will lesssen the demand at the water treatment plants as there will be less waste water.
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    7.0 Costs of Implementing Rain Water System for ESE Building

    Complete costs cannot be estimated until the following information has been obtained:
    1. The actual size of the collection area(s)
    2. The number of toilets to be installed in the building
    3. Flush demand

    This is the minimum amount of information that is needed to provide an accurate cost estimate. Paul Weigle stated that a "ballpark figure" cannot be obtained until these requirements are met. Contact information for Paul Weigle can be found on the contact sheet.
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    7.1 Maintenance

    Two types of maintenance costs are involved with this rain water system: long term costs and short term costs. Regarding the rain water systems already in place, no short term costs have been incurred. This time span involves a three year period, beginning with the commissioning of the system to flush toilets successfully (Weigle,March 7,95).

    Long term costs are presently difficult to predict as no rain water system fulfilling the purpose of flushing toilets has been in place long enough to make a valid estimate. There is a possibility, like within any system for difficulties to occur with its individual parts after working for extended periods of time. For this system in particular, problems may arise with the pumps (Weigle,March 7,95).
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    8.0 Limitations

    Throughout the course of this study, the WATGreen Team was limited by certain factors.
    3. Insufficient background literature on rain water systems to flush toilets. This inhibited the WATGreen team from looking beyond the sources who had actually implemented such a system to obtain information.

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    9.0 Recommendations

    Based on the limitations that inhibited a more thorough study of the implementation of the rain water system for the new building, several recommendations are suggested by this WATGreen team.
    1. A complete flush demand study, sighting the specific water requirements for flushes within a building the same size as the new ESE building.
    2. Based on flush demand results and a more detailed analysis of precipitation records, an exact calculation of cistern size should be performed.
    3. Scoping should be done for contractors and architects other than Paul Weigle who have the knowledge and expertise to design and construct a rain water collection system for cost comparisons.
    4. A study should be done by the architects of the new building on how to maximize areas for rain water collection within the new building.
    5. It is recommended by the WATGreen team that three years following the implementation of the rain water system within the new building, a follow-up study be performed comparing the costs of running this system compared to other systems of comparable size within the University of Waterloo's boundaries.

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    10.0 Conclusion

    In today's day and age of increased environmental concern over sustainability, changing things in such a way so as to reduce one's ecological footprint is essential. The implementation of a rain water system on campus will not only reduce the university's ecological footprint, but also set the stage for futuresustainable developments. Also key, is the fact that the system would exist within an Environmental Science and Engineering Building - a suitable setting for a state of the art environmental technology.
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    Appendix A: Rain Water Systems Diagram

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    Appendix B: Flush Study Results

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