campus audit: water analysis
by Karen Fochler, Senior Project Environmental Studies, 2006
Water Use and Conservation on St. Mary’s Campus
Introduction
California has a Mediterranean-type climate, with warm, dry summers and cool, wet winters. The beauty of the Bay Area is the result of many sunny days and a pleasant, temperate climate. With the majority of rain falling during the winter and spring months, Californians are dependent upon a system of reservoirs and aqueducts to provide adequate water for the demands of agricultural, industrial and residential needs during the long dry season. (Carle). The purpose of this paper is to review how water is currently used, to evaluate efficiency of water use at St. Mary’s College, discussing alternatives for improved efficiency, and to give recommendations for more effective water conservation methods.
Water Sources
Moraga receives most of its water from the East Bay Municipal Utilities District, specifically from the Molkelumne river. This includes the Pardee Reservoir at 209,950 acre-feet, and the Camanche Dam at 431,000 acre-feet (Nuzum). This water is monitored and purified for cooking, drinking, bathing, washing, cleaning, and irrigation. The other current source of water is the seasonal rain, primarily occurring from November through April. This provides seasonal water for the landscape.
Current Conservation Measures at St. Mary’s
St. Mary’s College of California in Moraga consists of about 3300 students (3,737 full time equivalency in 2005) and 197 full-time faculty. There are about 1486 students and faculty who live on campus in residence halls. The residence halls are used by other programs during the summer. Recent data (Tables 1 & 2) would indicate that each person in the residence halls uses 40 - 80 gallons per day on average At St. Mary’s College, some measures have already been put into place to help conserve water, including:
- low flow showers and toilets,
- waterless urinals, and
- efficient methods of irrigation and gardening. (Kehoe)
The grounds cover 420 acres, 90 of which are under irrigation. (St. Mary’s)
There are a number of other effective methods that could impact the amount of water used at St Mary’s College.
Roughly half of the water consumed at St Mary’s College, as well as in the community at large, is by irrigation, both for gardening and in agriculture. Much of the beauty on St. Mary’s College campus can be attributed to the landscaping that frames the buildings. This landscaping, with 200 different kinds of plants, (Kennedy) requires water to maintain its lush, green appearance. Water use on campus ranges from approximately 93,975 gallons per day in January/February, to 290,690 gallons per day, almost tripled, in July/August. (Analysis of EBMUD usage, Jeanne DeMatteo) The bulk of this variation is due to higher demands for irrigation in the hot, dry summer months.
There are some measures already in place to conserve irrigation on campus. These include:
- Drought-tolerant plants, such as oleander, lavender, and nadina. Roughly 95% of the plants at Saint Mary’s are drought tolerant.
- Allowing the drought-tolerant grass lawns (fescue) to grow slightly taller to provide more shade and slow evaporation. (Kennedy).
- Using wood chips as mulch to slow evaporation
Other water conservation methods are possible. These include:
- Water reclamation
- Evapo-transpiration irrigation control.
- Public conservation awareness campaigns
- Drip irrigation
- XeriscapingTM
- Dual flush toilets
Conservation Methods on other Campuses
Cisterns and Water reclamation
There are a number of college campuses that use cistern systems to utilize rain and other non-potable water for irrigation purposes. These universities include Duke University and Humboldt State University. A cistern system consists of water storage tanks that collect rainfall from a catchment system on a roof(s), and store it either underground or at ground level. (Bucklin) These watertight containers are made from materials that will not react with the water, such as reinforced concrete, galvanized steel or plastic.
A number of variables factor into the effectiveness of a cistern system. These factors include the climate, use of gravity to allow the water to flow, surface area of the catchment system, filtration and channeling of the water, cistern size and style and location of the equipment. (Biddle) The cistern system works well at Humboldt state, in Arcata, California, which is located in an area with a similar weather pattern to Moraga, with a long, dry summer season, and the vast majority of rainfall in the winter. It is a very small system, however, at less than 2,000 gallons of water, and used to provide irrigation around one building. Arcata, although with a similar weather pattern to Moraga, is a significantly cooler and wetter climate. Its irrigation needs are much less than in Moraga. Duke University has a 70,000 gallon hidden cistern that is successfully used to irrigate a two-acre planted area. The rain falls on the roof of the Engineering and Applied Science building. (Dickinson)
The simplest, most economical way to collect the water is to allow gravity to carry the water from the roof downward into the collecting system. Facilitating the use of gravity would be the use of large, slanted roof surfaces to collect the rainfall. (Banks 2) Galvanized steel and aluminum roofs work best as material for collecting runoff. If the roof is too rough, dirt and debris collect and contaminate the water.
Water filtration involves four different aspects. (Biddle) Wire mesh is applied over the gutters and downspouts to keep out large debris such as leaves, twigs, etc. The running water passes through a layer of sand within the cistern to sift out small particles. A third aspect, optional for non-potable water, is chemical purification, which takes place within the cistern. This can consist of a carbon filter, reverse osmosis and/or ultraviolet light, which can remove nearly everything except radioactive particles. (Banks, 2) The final filtration is the maintenance of the systems, including scheduled cleaning of the roof, rain gutters and collection system. To keep algae from growing, the cistern would needed to be kept from sunlight, either underground or covered, and enclosed to keep mosquitoes out.
The different materials available for cisterns have variable prices. Metal runs about 40 to 60 cents per gallon; plastics 35 cents to one dollar per gallon, fiberglass 38 cents to $1.50 per gallon and 35 cents to one dollar per gallon for concrete. So, a 10,000 gallon concrete or plastic cistern would run approximately $10,000, metal would be approximately half or $5,000. (1997 prices, Biddle).
One inch of rain falling on a 1,000 square feet of roof surface will yield approximately 550 gallons of rainwater. (Banks,2) With the average rainfall in Moraga at 26.86 inches per year, a 5,400 square foot roof (roughly the horizontal square footage of Aquinas hall’s roof) would yield 79,700 gallons of rainwater per year, collecting incrementally throughout the rainy season. (calculation; see attachment)
Evapo-transpiration Systems
Evapo-transpiration measures water lost through evaporation from both plants and soil, and is a good indicator of irrigation needs. . An evapo-transpiration irrigation system monitors weather conditions closely, and waters according to the day-to-day need, rather than on a set schedule.
Meaurements of temperature, solar radiation, rainfall, humidity and wind measurements are sent directly from a local weather station to a computer, which calculates the evapo-transpiration rate. This information is then communicated from the computer (a personal computer), back to the individual irrigations controllers out in the field. (Stanford)
Stanford University uses this high-tech method to more efficiently monitor irrigation needs through the use of a weather station linked to a computer. The weather data is monitored daily, and will change the sprinkler and drip irrigation run times based on daily need, based on the evapo-transpiration rate. This has resulted in a 27% reduction in water use on the Oval lawn, a lawn area at the entrance of Stanford Campus. For example, the data collected by the weather station on March 28, 2005 looked like this: Minimum temperature, 48.06 degrees, Maximum temperature 60.53 degrees, Total solar radiation, 391.97, total rainfall 0.77 inches, average humidity 83.44%, and average wind run of 2.62. This data was entered into the PC weather program, resulting in a evapo-transpiration rate of 0.10 inches/day. (Stanford)
Examples of such weather stations are available on the Internet at costs starting around $800. For example, a “Cabled Vantage Pro 2 Plus” proved accurate weather readings, including pre-installed UV and solar radiation sensors, laser-calibrated rain collectors, temperature and humidity sensors, an anemometer to measure wind speed and direction, with alarms that can be set, all connecting via cable to a personal computer. The computer can be programmed to make adjustments to irrigation patterns based on day-to-day changes in these weather indexes, communicating these changes automatically to the field controllers. (WeatherInstruments.com).
Conservation Campaigns
North Carolina has been susceptible to drought over the years. As a consequence, both the University of North Carolina at Chapel Hill and Duke University have established campaigns to educate staff and students on water conservation. UNC has a water conservation campaign called “every drop counts”. Some of the recommended practices include taking a shorter shower, as short as four minutes, not leaving faucets running while shampooing, brushing teeth or shaving, and operating washing machines and dishwashers only when full. (“Water Conservation”) Fliers could be posted in bathrooms, kitchens and laundry areas with reminders to use the above conservation guidelines, as well as a phone number to call to report all leaks. Dorms could compete with each other to use the least amount of water. Prizes could be offered to the “winning” dorm on a monthly basis.
Additional Water Conservation Measures
Drip Irrigation
More extensive use of drip irrigation could be used in planting areas. Drip irrigation can use 50-70% less water than traditional sprinkler systems. Early attempts at “drip” irrigation involved filling clay pots with water, and allowing the water to slowing filter out to the surrounding root systems. In 1959 Simcha Blass from Israel developed the modern form of drip irrigation through the use of plastic pipes and tubing, with emitters located at the root lines of plants. It is a highly efficient system, because the water is slowly dripped at the root line, eliminating the waste of watering leaves, run off, erosion and increased evaporation. There is less fertilizer and nutrient loss, and soil type plays a less important role. It is easier to regulate the water needs for different plant types. Drip irrigation is not effective on lawns because the drip lines need to be very close together in order to water all the roots, and would be damaged by people walking on it. The initial expense for drip irrigation can be more than traditional sprinkler systems. The tubing lasts from one to three years before needing to be replaced. (“Drip Irrigation”)
Saint Mary’s College has attempted to use drip irrigation with mixed results. One of the problems is that the emitters can get clogged with debris, which may not become apparent until the plant begins to die. (Kennedy). Top quality drip irrigation can help prevent this problem, but there does need to be regular maintenance and periodic replacement of parts (“Drip Irrigation”). Vandalism, intentional and unintentional, has been a problem on campus as well. If people walk through planted areas, the drip lines can be easily damaged. Currently, St. Mary’s uses sprinklers for all of its irrigation needs. The sprinkler system is on an established watering schedule in the summer, and manually turned on or off as needed during the rainy season. (Kennedy)
XeriscapingTM
Xeriscaping was coined by combining xeros (Greek for "dry") with landscaping. Plants whose natural requirements are appropriate to the local climate are emphasized, and care is taken to avoid losing water to evaporation and run-off.
A high proportion (95%) of St. Mary’s landscaping already consists of drought tolerant plantings (Kennedy). However, there may be some lawn areas that are not used for recreational purposes that could be transformed into attractive, drought-tolerant ground cover and/or raised beds that would be more water conservative. (“Xeriscaping”)
Grass uses seventy-nine gallons of water per square foot a year in the desert versus. seventeen gallons per square foot for xeriscape. (“H2O”
Dual Flush Toilets
Currently, St. Mary’s College has replaced most of it’s toilets with low-flow toilets, using 1.6 gallons per flush (gpf). (Kehoe) Dual flush toilets, which use 0.8 gpf for liquid waste, and 1.6 gpf for solid waste, can result in a 26% water savings on the typical low flush toilet. This can result, on average, in lowering from 9.1 to 6.9 gallons per day per person would use, on average, in flushing the toilet. On a campus the size of St. Mary’s, this could work out to saving roughly 4,000 gallons per day if all the toilets were converted to dual flush toilets. (Dual Flush Toilets)
Conclusions
Living in continually drought-prone California requires being mindful of how water is used. Because of this, a public conservation awareness campaign should be an ongoing effort. Reminders of how much water is being used in the shower, or in toilet, etc., can help people recognize they have choices in using water that can make a difference. In times of increased water shortage, dorm competitions could be instituted, comparing and publicizing how much water per person was being used. Costs are minimal to implement such a program, but there’s a limit to the amount of potential water savings. From an educational standpoint, there is great benefit to helping people think more about how their personal choices can impact the environment. This could help St. Mary’s students be better citizens in the future. Themes and goals of conservation should change periodically, because people get tired of hearing the same thing, and will start tuning out the message if it’s not changed from time to time. Also, periodic rewards and incentives will help stimulate fresh interest.
An evapo-transpiration system, working in conjunction with drip irrigation, could result in significant water use savings. This system could greatly increase the efficiency of watering. The combination of a weather station communicating with a drip irrigation system can lower water use by at least 50%. There is a significant initial cost involved, which would be determined by how great an area would be converted to drip irrigation. But the long term, the benefits would make it worthwhile. If only a weather station was added, and no drip irrigation, there could still be a significant water savings, up to 27% if St. Mary’s experiences the same reduction Stanford has. A weather station would need to be purchased, and a computer dedicated to the project.
Water reclamation is an intriguing possibility, but the system required to store enough water to make a significant difference would be daunting. A single, 70,000 gallon cistern such as the one Duke uses would run dry in less than a day of irrigation at St. Mary’s. If rainfall were more year-round here, like in North Carolina, were most of the rainfall is in the summer, a cistern system could be used to effectively supplement irrigation during dry times.
Saint Mary’s College uses drought-tolerant plants to a large extent. Many of the plants come from similar Mediterranean climates as California. As plants and trees need to be replaced, water needs should be considered.
It is important for St. Mary’s to stay aware of new developments in water efficiency with regard to appliances and fixtures. As the current toilets need replacing, dual flush toilets would make good sense, and save an impressive amount of water from going down the drain. The same is true for choosing other new equipment as the need arises.
Saint Mary’s College has made good progress toward sustainability with its water-saving measures. However there are more measures that can be considered.
Appendix – Discussion of St. Mary’s College Water Use Data
The tables on the following pages contain the data collected for this paper on water use. Despite repeated efforts to gain access to information, this data was only made available recently. This resulted in the necessity to make several assumptions about factors which could be verified with more time.
The EBMUD Data and Analyses (Tables 1 & 2). Some of the older dorms do not have their own water meters. Therefore, the dorms that have meters were used to estimate the average use per resident – and this average was then applied to all residents to estimate a total residence usage. Because the meters associated with dorms also measure adjacent landscape watering, the winter months were the primary data for estimating use by residents. It was assumed there was little landscape irrigation necessary during the November – March period. Surprisingly, there was great variation from dorm to dorm. This may be due to unspecified additional dorms drawing through some of the meters. The dorms with high averages in the winter season may also indicate they have fewer water conservation measures implemented.
The Sports Field Water Meter Readings (Table 3) were provided by Joe Kehoe. The Intramural and Baseball field meter was basically static – indicating it was likely broken. If the meter was broken, then the total sports field watering usage would be more in the 100,000 gallon range for the June – October season. Mr. Kehoe stated his belief that the sports fields constituted 70% of the total irrigation used at St. Mary’s. With the water main registering 59 million gallons for academic year 2005-2006, more study is needed to understand the major uses of water in St. Mary’s of California. It is hoped that the data and analysis tables in this paper will help focus additional research.
Appendix
Calculation for determining amount of water run off:
550 gallons per 1,000 square-feet roof per one inch rainfall (Banks, 2)
550 gallons/1,000 s-f x 5,400 s-f/Aquinas roof=29,700 gallons/one inch rainfall
29,700 gallons/one inch x 26.86 inches per year= 79,774 gallons/year.
Bibliography
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www.eweatherinstruments.com/weather-stations/cable-stations/products.cfm?action=view&key=dvc012
