As Orange County’s public research university, UCI embraces its leadership role in the wise use of available water resources. As part of the university’s Water Action Plan, the campus committed to reducing potable water consumption by 50% by the year 2025, outperforming the University of California system-wide target of a 36% reduction. All ten University of California campuses have a Sustainable Water Systems section included in their Sustainable Practices Policy. This section outlines goals for water conservation, stormwater management, education, and outreach.
Collaboration between UCI and Irvine Ranch Water District began in 1965 long before the Sustainable Practices Policy was implemented when UCI began converting some of its irrigated landscape from potable water to recycled water produced by the nearby Michelson Water Recycling Plant. As the campus developed, UCI has continually expanded recycled water use to nearly all of its irrigated landscape, displacing 230 million gallons of potable water annually. With landscape irrigation displacement exhausted, UCI realized that other uses of potable water would be the source of further reductions.
In an attempt to meet the goal of 50% potable water reduction, in 2017, UCI and IRWD worked together to design and construct a recycled water line to serve the cooling towers at UCI’s Central Plant and make changes at the plant to accommodate the much different water quality profile of the recycled water. This project was made possible, in part, by the agreement that: IRWD would fund the cost of the pipeline, assist with obtaining grant funding, and UCI would manage the project, including improvements and changes to the central plant cooling tower water systems and controls. These modifications were funded by a loan and paid back through the cost differential between potable and recycled water, and by grants from the Metropolitan Water District. UCI is now about halfway through its repayment plan.
This water conservation effort is the byproduct of a partnership between UCI and IRWD. Established in 1961, IRWD provides high-quality drinking water, sewage collection, sewage treatment, drought-proof recycled water, and natural urban runoff treatment for almost half a million residents in 181 square miles of central Orange County, California. IRWD is an independent, not-for-profit public agency serving all of Irvine and parts of Lake Forest, Newport Beach, Tustin, Costa Mesa, Orange, and unincorporated areas. IRWD is governed by five publicly elected directors, who live in the neighborhoods they represent. The Board of Directors is responsible for policies and decision-making. Day-to-day operations are supervised by the General Manager.
A large and drought-proof portion of IRWD’s water supply is recycled water, which comes from treating and purifying water that goes down customers’ drains. This includes tertiary-treated recycled water produced by IRWD for irrigation and other nondrinking uses, and drinking water from Orange County Water District’s Groundwater Replenishment System. IRWD is a national leader in recycling — with a history of achievements dating to 1963, when it integrated recycled water infrastructure into the design of the community.
The existing cooling system at UCI’s Central Plant recirculates water using pumps and spray nozzles to allow efficient evaporation of part of the circulated water in the cooling towers. Evaporation absorbs heat transferred from the campus cooling and generation equipment; the evaporated water is mixed with huge volumes of ambient air and discharged via large fans at the top of the towers.
Because the existing campus irrigation system water pipes were fully subscribed and recycled water is sold at a different rate when used for this purpose, the project installed a dedicated metering station connected to the existing IRWD recycled water mains located on the campus in an area leased to the Irvine Company, a 3,500-foot section of twelve-inch recycled water pipe, and two connections at the existing campus Central Plant.
To use the recycled water in the cooling water system, cartridge micron filters were added. The filtration reduces suspended solids present in the recycled water and was highly recommended by others using this water source in their systems. In addition, fully-automated instruments and controls replaced the existing controls, which had expanded ad hoc with the plant as it grew by a factor of ten with the campus building space from the 1960’s.
To reduce corrosion and attain long equipment life, UCI has developed over the last 30 years a world-class water treatment regime for its hydronic systems, including the water in the cooling water system at the Central Plant. To accommodate the new water source, UCI modified their water treatment process and reduced cycles of concentration, from 4 cycles to 2.8 cycles. Both potable and recycled water in the area are relatively high in dissolved solids making increasing cycles of concentration much beyond four costly.
A component of UCI’s community outreach process was to tour the source water facility, IRWD’s Michelson Water Recycling Plant, and several different facilities that used recycled water in their cooling tower systems. Among these facilities was the Capital One Group industrial facility. During these tours UCI Campus and Environmental Planning, Facilities Engineering, and Plant Operations staff members met with the facilities staff to get firsthand feedback of their experience using recycled water for non-irrigation purposes. In addition, UCI and IRWD engineering staff members mutually reviewed the construction project documents and provided inspection and technical expertise, including cross-connection control, throughout the construction process leading to a successful installation on the densely-developed campus.
Additional outreach to the members of the university was conducted through publicizing the project on campus through various student organizations and faculty/staff newsletters.
The UCI staff on the project developed and presented an Operational Cost Analysis and Projected Loan Payback Model to campus leadership. They also presented to the UCI Water Resource Work Group and updated their water action plan to reflect their new goals. After the project was implemented, UCI publicized the project through IRWD publications and held a dedication ceremony with public officials and the press.
UCI quantified their success by measuring the following components: recycled water usage, potable water usage, chemical water treatment usage, filtration media usage, equipment performance and wear, and changes in their operational costs.
Recycled water for irrigation purposes is less costly than potable water. The IRWD published rate for year 22-23 for potable water is $2.42 per hundred cubic feet (CCF), the base rate for recycled irrigation water is $2.16. A CCF is 100 cubic feet or approximately 748 gallons. It is a common water billing unit in the arid western US. A million gallons is approximately 1337 CCF.
UCI is paying the loan from IRWD that helped fund the project. It will take about 15 years to pay the cost of the pipeline. UCI Pays the “Commercial and Industrial loan customers” rate for the recycled water (presently $2.42 per CCF) until the loan has been repaid. Then, UCI will move to the “Commercial and Industrial customers” base rate, which is presently $1.23 per CCF. The differential between the two rates is the means of payment.
UCI pays for disposal of the blow down from the towers. The rate is about $0.80 per CCF of recycled water at the meter. However, there are capital cost components that UCI pays in addition to the treatment costs. This is different from other customers of IRWD and is based on a unique agreement dating to the founding of the campus; as a tax-exempt state constitutional corporation, whereby instead of paying property taxes, UCI buys treatment capacity rights in the Michelson Water Recycling Plant. Due to the unique nature of the agreement, sewage rates at UCI are not applicable to other customers.
Due to careful water treatment, continuously monitored by a full-time staff member dedicated to treating the various campus hydronic systems, including the Central Plant cooling system, within the first five years of operation with recycled water, UCI has not observed acceleration of deterioration of existing components within the cooling system.
Recycled water use requires greatly increased chemical treatment. This additional water treatment has significantly increased the campus cost for treating the cooling water compared to potable water. Biocide usage has increased dramatically; to attain the cycles of concentration, acid treatment is now required (previously, UCI had eliminated use of acid treatment in 1989); and the micron filters are an entirely new item. Costs for treating the cooling water when using recycled water have risen to $1.65 per CCF from $0.87 when using potable water.
Implementing recycled water at the Central Plant displaces 61 million gallons of potable water per year by using 88 million gallons of recycled water. The primary objective to reduce potable water use was accomplished, and the university reached its stretch goal of reducing potable water consumption by 50% from a 2005 to 2007 baseline. Although the project has not yet led to financial savings, it did not significantly add to the utility budget. The long-term effects on the overall operations and maintenance budget will be evaluated for true cost savings. UCI's hard work on this project earned them an award for water reuse.
- University of California Irvine, Water Action Plan
- Better Buildings Initiative. Water Savings Network
- Department of Energy, Developing a Comprehensive Water Management Program
- Department of Energy, Alternative Water Sources
- US EPA, Water Budget Tool