Volume 1, Number 4
Recycled Water is Keeping Hacienda Green
By Tina Hansen
Despite the recent heavy rains, meeting water demands in California will continue to be a challenge. Fortunately, with new technology, recycled wastewater has become a resource that will help keep Hacienda green and growing. As the overall demand for water grows and the supply diminishes, recycling wastewater into clean, usable water is not only a necessity to conserve potable water but is also beneficial for the environment.
In urban areas, the demand for water is primarily driven by the need for water for drinking and personal use, and non-potable water, used for irrigation and landscaping. One of the main goals of recycling wastewater is to provide usable, non-potable water to reduce the need to use fresh potable water resources for uses where non-potable water is good enough.
In any location, the wastewater produced and collected by homes, industries, and businesses must be treated before it is released back to the environment. At Hacienda, this wastewater flows into a treatment plant through more than 200 miles of underground pipeline; all part of the Dublin San Ramon Services District (DSRSD). With the completion of several new upgrades to the system, wastewater is now treated so it can be used for irrigation and landscape purposes.
The principal aim of wastewater treatment is to remove as much of the suspended solids as possible before the remaining water, called effluent, is discharged back to the environment. As the solid material in the water decays, it uses up oxygen in the water making it less useful for plants.
The water recycling process is a three-step process of treatment of cleaning in preparation for it to be reused or discharged into the Bay. The first step is to skim out impurities and sediment. This step removes about 60 percent of suspended solids from wastewater and also aerates the wastewater, to replace oxygen. Then, the water goes through a secondary treatment that further cleans it, removing more than 90 percent of suspended solids, cleaning the water to the point considered safe to be discharged into the Bay. The last step is called Advanced Tertiary treatment which puts the wastewater through a microfiltration and UV disinfection. This last step produces water, though not potable, of high enough quality for irrigation purposes that can be used at parks, golf courses, and schoolyards.
"Our investments in water recycling infrastructure continue to pay back huge dividends by reducing imports of drinking water from the State Water Project and exports of treated wastewater to the San Francisco Bay," DSRSD board president Pat Howard said in a statement. "Recycled water is a sustainable water supply for irrigation."
Recycled water use has seen a dramatic rise over the last few years and to keep pace with demand, the DSRSD has begun an expansion of its treatment facility. Construction began in January at the cost of $18.2 million and will increase capacity by 70 percent from 9.7 million gallons a day to 16.2 million. The project is expected to take 18 months, and the contractor has recently met its first milestone on work related to the holding basin dedicated to wastewater.
"With California's extreme drought fresh in our memory, it has never been clearer that recycled water is an essential part of our water supply," said Georgean Vonheeder-Leopold, president of the Dublin San Ramon Services District Recycled Water Authority.
In Pleasanton, the city began its Recycled Water Project last August by installing new pipes as part of its recycled water distribution system that serves many landscapes currently irrigated with potable water. Once completed this project is expected to have an annual savings of approximately 450,000,000 gallons of potable water.
The Recycled Water Project is nearing completion of Phase 1 which involved the installation of 10 miles of pipe in and around Hacienda. The recycled water will be used to irrigate greenspaces and landscaping within various Hacienda projects and Hacienda's street medians. In addition, the new system will allow recycled water to be used at several city parks such as Ken Mercer Sports Park, Tennis and Community Park, Creekside Park and Owens Plaza Park. When all 138 customers are hooked up to the system, this project will save 10 percent of the city’s total potable water use, or 4 million gallons a year.
Non-potable water reuse has become a widely accepted practice that is expected to grow. In a recent survey of 3,000 Californians done by Xylem Inc., a leading global water technology company, California residents are overwhelmingly supportive of using treated wastewater or recycled water in their everyday lives. The survey defined recycled water as former wastewater that has been treated and purified so that it can be reused for drinking purposes. The survey found that 76 percent of respondents believe recycled water should be used as a long-term solution for managing water resources, regardless of whether or not a water shortage exists.
“With overwhelming support from the public, California is well-positioned to lead the U.S. in accelerating the availability and acceptance of recycled water. The state has the opportunity to champion a flexible framework that recognizes the unique needs of local communities as they work to establish water resource strategies that include sustainable solutions, such as recycled water,” said Joseph Vesey, Xylem Senior Vice President.
As the population increases, demand for water that is both potable and non-potable is essential for future development. The population within Zone 7’s service area, of which Pleasanton and Hacienda are a part, increased 47 percent between 1990 and 2015, and is projected to grow by another 19 percent by 2040, from 245,200 in 2015 to 291,000; a majority of the projected growth expected to occur within the next 10 years.
Zone 7 supplies untreated water for agriculture and golf courses and treated drinking water to the City of Pleasanton. As a result of the water conservation measures taken by the city and a successful response to water use reduction plans put in place by Zone 7, potable water demands are lower. In fact, because of continued efforts through a mandate by the State of California in 2015, potable water usage projections are lower than were formerly estimated. These altered projections are in large part due to the recently completed recycled water projects and water conservation programs implemented by the local water supply retailers.
A new study being conducted by Zone 7 has just begun to look at ways to make wastewater eventually available as a potable water supply. “The new study is looking at methods to make our water supply more reliable from water that is right here in the Valley. Perhaps in the future, we will be able to purify this water to a greater level to be used ultimately as a drinking water supply source,” said Judy Zavadil, Engineering Services Manager of DSRSD.
Another initiative under consideration is building or connecting to desalination plants, which make seawater potable. According to Bay Area Integrated Regional Water Management, a study is being conducted to examine the development of an environmentally and socially responsible, and cost-effective regional brackish water desalination project to benefit the entire San Francisco Bay Area.
Gilad Cohen, chief executive of IDE Americas, a technology provider for some existing desalination plants in the area, says, “The technology is ready, and California is working on more desalination, water reuse, and conservation.”
As the state continues its efforts to conserve water and develop new innovative water supplies, for the moment, the worst of the problem has been eased by recent heavy rains. Earlier this month Governor Brown lifted the drought order in all but a few counties, where he said emergency drinking water projects would continue to help communities where wells have gone dry, but he noted the need for continued work on both conservation and the development of new water sources.
These efforts are continuing locally. The City of Pleasanton is offering rebates to residents who replace existing water-thirsty front lawns or sidewalks with water-efficient, drought-tolerant landscaping. In Hacienda, water conservation efforts frequently exceeded even the state-mandated use reduction requirements and will continue to be aided in no small part by the availability of recycled water for irrigation.
With so much dependent on water and with the ingenuity and creativity shown in developing new opportunities around water usage, the City of Pleasanton, Hacienda, and associated water districts will continue to find ways to improve access to a clean water supply and provide a sustainable and green environment.