Groundwater Replenishment System Initial Expansion
- Project Location:
18700 Ward Street, Fountain Valley, CA 92708
- Project Description:
The Groundwater Replenishment System (GWRS) is the world’s largest water purification system for indirect potable reuse and helps increase Orange County, California’s water independence by providing a locally controlled, drought-proof supply of high-quality water. The GWRS came online in 2008 and produced a record-breaking 70 million gallons of potable water per day. In 2015, the GWRS Initial Expansion increased the capacity of the GWRS by 30 million gallons per day (MGD), bringing its total capacity to 100 MGD, and generating enough near-distilled quality water to meet the annual needs of 850,000 people.
The GWRS is a joint project between the Orange County Water District (OCWD; the District) and Orange County Sanitation District (OCSD) located in Fountain Valley. After wastewater is treated to secondary levels at OCSD Fountain Valley Plant No. 1, it is not discharged to the ocean, but rather, it flows to the GWRS where it undergoes a state-of-the-art purification process consisting of microfiltration, reverse osmosis and ultraviolet light (UV) with hydrogen peroxide. The result is ultra-pure water that meets or exceeds state and federal drinking water standards.
Process: three-step advanced purification process
The first step in the purification process is microfiltration. Microfiltration is a separation process that uses polypropylene hollow fibers with tiny holes in the sides that are 0.2 micron in diameter. By drawing water through the holes into the center of the fibers, suspended solids, protozoa, bacteria and some viruses are filtered out of the water. 6,840 additional microfiltration membranes were installed during the GWRS Initial Expansion bringing the system’s total to 24,624. The goal is to treat the water so it is clean enough to go to the heart of the purification process, reverse osmosis.
During the reverse osmosis (RO) process, water is forced through the molecular structure of semi-permeable polyamide polymer membranes under high pressure, removing dissolved chemicals, viruses and pharmaceuticals in the water. 6,300 RO membranes were installed during the GWRS Initial Expansion, bringing the system’s total to 22,050 RO membranes.
Water is exposed to high-intensity ultraviolet (UV) light with hydrogen peroxide (H2O2) to disinfect and to destroy any trace organic compounds that may have passed through the reverse osmosis membranes. Examples of these trace organic compounds are N-Nitrosodimethylamine (NDMA) and 1-4 Dioxane, which have to be removed to the parts-per-trillion level. UV with H2O2 is an effective disinfection/advanced oxidation process that keeps these compounds from reaching drinking water supplies. It takes only 10 seconds for the water to pass through three reactors and become completely sanitized. 1,728 UV lamps were installed during the GWRS Initial Expansion, bringing the system’s total to 5,616 UV lamps.
Process: post purification
GWRS post purification facilities stabilize the water using decarbonation and lime to eliminate the potential for scale formation and screen plugging at groundwater injection wells. Carbon dioxide is removed from the water to decarbonate it and increase its pH. Lime further increases the pH and adds calcium and alkalinity by converting the remaining carbon dioxide to bicarbonate. Improvements to the post-treatment were made during the GWRS Initial Expansion and included lowering the pH and increasing the alkalinity to increase buffering capacity and decrease variability.
The complete process purifies the water in approximately 45 minutes.
Timeframe of completion:
Design complete August 2010
Construction start October 2011
Construction complete June 2015
- Project Justification:
The GWRS Initial Expansion made the world’s largest water purification system for indirect potable reuse even bigger, increasing the system’s reliability in times of drought. To date, the GWRS has produced 172.5 billion gallons of new water.
By recycling water, the GWRS indefinitely postpones the need for OCSD to construct a new ocean outfall by diverting treated wastewater flows that would otherwise be discharged to the Pacific Ocean. 1.3 billion gallons of wastewater is lost to the ocean every day in Southern California and the GWRS is tapping into this valuable resource. The GWRS is helping preserve Orange County’s vital coast and helping OCSD become closer to its goal of 100 percent recycling. In addition, the region relies less on imported water, reducing strain on the Sacramento-San Joaquin River Delta and Colorado River.
Increased water quality and basin health
The GWRS Initial Expansion improves groundwater quality by reducing the amount of dissolved solids in the Orange County groundwater basin. Approximately 35 million gallons (132,500 cubic meters) per day of GWRS water are pumped into injection wells to create a seawater intrusion barrier. Another 65 million gallons (246,000 cubic meters) are pumped daily to OCWD’s percolation basins in Anaheim where the GWRS water naturally filters through sand and gravel to the deep aquifers of the groundwater basin to increase the local drinking water supply. Since the expansion came online in May 2015, 26,270 acre-feet of GWRS water has been sent to OCWD’s percolation basins; enough water for 210,000 people. This ultra-pure water is increasing the water quality and health of the basin.
Local reliability and cost
Nineteen water agencies located in north and central Orange County pump water from the groundwater basin for the 2.4 million people they serve. The GWRS Initial Expansion allowed OCWD to maintain a high groundwater basin pumping percentage (BPP) - currently 76 percent - and decreased the need for water agencies to purchase a greater amount of costly imported water. GWRS water is produced at a unit cost of $525 an acre-foot with subsidies and $850 an acre-foot without subsidies - each less than the cost of imported water, which is approximately $1,000 an acre-foot.
Without the GWRS, the District would have had to lower the BPP. The GWRS increases local water reliability and helped OCWD maintain groundwater pumping through consecutive droughts.
Producing GWRS water is energy efficient. The system uses less than half the energy required to transport water from Northern to Southern California and one-third the energy required to desalinate seawater.
To further decrease energy usage, energy recovery devices (ERDs) were installed within the RO system during the initial expansion to capture energy normally lost when water is released from a high-pressure system. The ERDs use turbines that resemble the configurations on an automotive turbo charger. It is anticipated that the high‐tech energy recovery system will save 14 million kilowatt hours and $ 1.3 million annually for the life of the system. Another benefit of this device is its corresponding reduction in CO2 greenhouse gas emissions, estimated at 14 million pounds per year.
Enhanced post-treatment stabilization
The previous lime feed system was replaced with a Tekkem system to provide post treatment stabilization. OCWD experienced operational difficulties maintaining treated water pH with its lime slurry make up system. The expansion addressed this by modifying the water quality goals to allow operation at a more stabilized point.
Two 7.5 million gallon storage tanks were built to allow OCWD to store excess treated wastewater during the day and feed the equalized flow to the plant at night during low-flow periods. This allows the GWRS to operate at a steady rate and simplifies operation. It enables the GWRS to maximize the amount of water it purifies.
As California faced the fourth year of a historic drought, the GWRS Initial Expansion started up. As other water sources decreased, the GWRS grew.
The GWRS serves as a global model for water reuse projects. Visitors from around the world visit the plant to learn how they may implement similar facilities in their communities. OCWD staff is often called upon as experts to guide the development of similar projects around the world. The GWRS is a blueprint to local water reliability.
The GWRS Initial Expansion created approximately 30 design jobs and 100 construction jobs. In addition, the GWRS was designed to be further expanded to increase production capacity to help meet future water needs.
- Special Circumstances:
Relationships with the public, media and elected officials were further strengthened due to OCWD’s proactive drought-tackling steps, especially in the midst of mandatory water restrictions used by Governor Edmund G. Brown, Jr.
Obstacles overcome: flow equalization and contaminated soil
Through careful planning, OCWD and OCSD were able to mitigate any possible concerns. Meetings and workshops were conducted to identify potential issues and challenges which could arise. 3D design models were used allowing staff to conduct “walk throughs.” For example, OCWD and OCSD maximized flows to the GWRS through the use of equalization tanks, despite decreased flows to OCSD due to conservation. The tanks also provide extra storage should OCSD see increased usage at a rate above what GWRS can safely handle. Unforeseen conditions, such as the discovery of contaminated soil under a flow equalization tank, was promptly addressed and partially remediated by raising the tank, avoiding the cost and schedule impact of removing the soil.
Obstacles overcome: public perception
Similar wastewater reclamation projects were proposed in neighboring Los Angeles and San Diego counties in the 1990s, but never came to fruition because the issue got politicized and wrongly labeled “toilet to tap.” OCWD and OCSD studied these projects carefully before embarking on the ambitious and visionary GWRS project. Both agencies continue to execute an aggressive outreach plan to educate the general public within Orange County and beyond about the real facts of wastewater purification. Approximately 4,000 people tour the GWRS annually. An enhanced tour marketing program set to launch in early 2016 is sure to increase those numbers.
Obstacles overcome: cost
Concern for cost was overcome through OCWD’s sound financial management. OCWD received $1.5 million in grant funding ($1 million from the California Department of Water Resources; $500,000 from Southern California Edison) for the Initial Expansion. The GWRS also received a 12-year, $7.5 million annual subsidy from the Metropolitan Water District of Southern California. OCWD continues to advocate for water reuse projects to receive legislative funds.
The GWRS Initial Expansion has drawn positive public and media attention and has been featured in numerous articles and television programs, including Bloomberg and 60 Minutes. The dedication event welcomed elected officials from Orange County and beyond and drew numerous accolades including support from Governor Edmund G. Brown, Jr., Congressman Dana Rohrabacher, Congresswoman Loretta Sanchez, Senator John Moorlach, and Assemblymen Travis Allen and Matthew Harper.
- Project Attachments:
Videos about expansion project:
Expanding Replenishment of California’s Precious Groundwater, Black & Veatch: https://www.youtube.com/watch?v=_skly5XrTcA
GWRS Initial Expansion Dedication, Orange County Water District: https://www.youtube.com/watch?v=-hLqcIAEdSg
People Drink Sewage Water for the First Time, Buzzfeed: https://www.youtube.com/watch?v=p-f_F3tE9rA
History of the Groundwater Replenishment System
GWRS is the ultimate expression of OCWD and OCSD’s long-term goal of developing a dependable water supply from a resource that formerly was wasted to the ocean. The model public agency partnership began with Water Factory 21 (WF 21). It was a world-renowned, and first-of-its-kind, water recycling facility that helped pave the way for many international projects and ultimately the GWRS. In the mid-1990s OCWD needed to expand WF 21 and address continued problems with seawater intrusion. At the same time, OCSD faced the challenge of having to build a second ocean outfall. The GWRS resolved these issues. Both agencies shared the cost of constructing the first phase of the GWRS ($481 million US dollars). OCWD funded the initial expansion which cost $142 million. OCSD supplied OCWD with stringently controlled, secondary treated wastewater at no charge. OCSD also invested resources to build a pump station to maximize wastewater flows to the GWRS. OCWD in turn agreed to manage and fund the GWRS operations. Through this collaboration, the GWRS emerged as one of the most celebrated civil engineering and water reuse projects in the world. Operational since 2008, the GWRS produced 70 million gallons (265,000 cubic meters) of water per day. OCWD expanded the plant’s capacity to 100 million gallons (379,000 cubic meters; 307 acre-feet) per day in 2015.
The Orange County Water District takes the limited water supply found in nature and supplements it to provide water for 19 cities and water agencies serving 2.4 million residents in north and central Orange County. Since 1933, when the California legislature formed it, OCWD has been entrusted to guard the region’s groundwater basin. In manages and replenishes the basin, ensures water reliability and quality, prevents seawater intrusion, and protects Orange County’s rights to Santa Ana River water.
The Orange County Sanitation District is a public agency that provides wastewater collection, treatment and recycling for approximately 2.5 million people in central and northwest Orange County. OCSD is a special district that is governed by a 25 member Board of Directors comprised of 20 cities, four special districts, and one representative from the Orange County Board of Supervisors. OCSD has two operating facilities (Fountain Valley-Plant No. 1 and Huntington Beach-Plant No. 2) that treat wastewater from residential, commercial and industrial sources.
- Award Citation::
The Groundwater Replenishment System (GWRS) is the world’s largest water purification system for indirect potable reuse and helps increase Orange County, California’s water independence by providing a locally controlled, drought-proof supply of high-quality water. In 2015, the GWRS Initial Expansion increased the capacity of the GWRS by 30 MGD, bringing its total capacity to 100 MGD, and generating enough near-distilled quality water to meet the annual needs of 850,000 people.
- Suggested Award Summary:
The Groundwater Replenishment System (GWRS) is the world’s largest water purification system for indirect potable reuse and helps increase Orange County, California’s water independence by providing a locally controlled, drought-proof supply of high-quality water. The GWRS came online in 2008 and produced a record-breaking 70 million gallons of potable water per day. In 2015, the GWRS Initial Expansion increased the capacity of the GWRS by 30 million gallons per day (MGD), bringing its total capacity to 100 MGD, and generating enough near-distilled quality water to meet the needs of 850,000 people.
In 2008, the Orange County Water District (OCWD) and the Orange County Sanitation District (OCSD) made history with the opening of the GWRS. The GWRS produces high-quality water using a three-step process consisting of microfiltration, reverse osmosis and ultraviolet light with hydrogen peroxide. The purified water helps to protect Orange County’s groundwater basin from the threat of seawater intrusion and increases local drinking water supplies. The GWRS Initial Expansion not only increases output to 100 million gallons per day at a typical average cost of $525 and acre-foot, it decreases dependence on costly imported water from Northern California and the Colorado River, uses half the energy required to deliver imported water to the region, provides reliability in an area plagued by cyclical droughts, and protects the environment by decreasing the amount of treated wastewater in our ocean and reusing a precious resource.
The expansion included the addition of two 7.5 million gallon flow equalization tanks, 6,840 microfiltration membranes, 6,300 reverse osmosis membranes, and 1,728 ultraviolet light lamps. In addition, the expansion included the installation of energy recovery devices (ERDs) within the RO system. Each ERD was integrated with a booster pump to boost feed pressures to later stage membranes, leading to prolonged membrane life. Estimates indicate the ERDs will result in saving 29 kilowatts of energy and $23,000 per year per RO skid. New post treatment stabilization was also implemented and included lowering the pH and increasing the alkalinity to increase buffering capacity and decrease variability. As part of this enhancement, the previous lime feed system was replaced with a Tekkem system.
The GWRS is Orange County’s shining example of forward thinking and environmental stewardship that will help Orange County prepare for those not-so-rainy days. To date, it has produces more than 172.5 billion gallons of fresh, clean water.