Yesterday, November 10, 2011, the Orange County Water District (OCWD) held its annual tour of the Groundwater Replenishment System (GWRS), a state of the art system in Orange County, CA for recycling wastewater into drinking water and maximizing groundwater recharge from naturally occurring run-off in the Santa Ana River watershed. I was lucky enough to get a seat on the tour, which always seems to fill up fast, and along with about 150 other people, participated in the day long adventure.
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| Microfiltration units |
The GWRS is the world’s largest advanced wastewater purification system for indirect potable reuse.(1) The wastewater is purified using microfiltration (MF), reverse osmosis (RO), and advanced oxidation (AO) with hydrogen peroxide and ultra-violet (UV) light. The water that results meets all state and federal safe drinking water regulations for potable water. On the tour, they give you the opportunity to drink some, which I did; it tasted good, and I’ve had no ill effects, I assure you. However, rather than being used as a source of potable water directly, the water is either pumped into the ground near the coast as a barrier against seawater intrusion, or it is pumped to percolation basins so it can recharge the groundwater aquifer that underlies a large part of Orange County. The plant has a capacity of 70 million gallons per day (MGD). A 30 MGD expansion is currently in the planning stages, to be completed by 2014; and another 30 MGD expansion is planned for the future.
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| Reverse osmosis cartridges |
The GWRS is the world’s largest advanced wastewater purification system for indirect potable reuse.(1) The wastewater is purified using microfiltration (MF), reverse osmosis (RO), and advanced oxidation (AO) with hydrogen peroxide and ultra-violet (UV) light. The water that results meets all state and federal safe drinking water regulations for potable water. On the tour, they give you the opportunity to drink some, which I did; it tasted good, and I’ve had no ill effects, I assure you. However, rather than being used as a source of potable water directly, the water is either pumped into the ground near the coast as a barrier against seawater intrusion, or it is pumped to percolation basins so it can recharge the groundwater aquifer that underlies a large part of Orange County. The plant has a capacity of 70 million gallons per day (MGD). A 30 MGD expansion is currently in the planning stages, to be completed by 2014; and another 30 MGD expansion is planned for the future.
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| The far tap is the fully treated wastwater. Yummy! |
The aquifer is also recharged by water draining from the Santa Ana River watershed. This recharge is enhanced by the use of rubber dams to divert the water into off-channel percolation basins, and by in-channel engineering that spreads the water out across the entire channel, maximizing the wetted area of the channel, which in turn maximizes percolation. The tour included a visit to one of the rubber dams and related off-channel features. These recharge efforts also include hundreds of acres of constructed wetlands in the area above Prado Dam, one of two large permanent dams on the river. These wetlands take water that drains from heavily agricultural areas, including large dairy farms, which is very high in nitrate, and allows natural biological attenuation to occur. The water leaving these wetlands, which flows into the recharge areas mentioned previously, has nitrate levels that are frequently non-detectable. This process prevents high nitrate water from percolating into the aquifer and causing widespread contamination. The tour group helped plant trees in the wetland area to help prevent erosion.
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| Inflatable rubber diversion dam on the Santa Ana River |
The combination of the GWRS and the other recharge operations puts 230,000 acre-feet (AF) of water back into the aquifer every year; that’s almost half of the 500,000 AF of water that is used within the Orange County Water District.
It was a great tour, and a very educational day all around. I’d highly recommend it to anyone with an interest in water.
The GWRS aspect of this facility is quite interesting though I am not sure I could knowingly drink from the purified water unless it was in a plastic bottle and sold for $1.50!
ReplyDeleteThanks for sharing. Here is a short read for you though not as informative as yours; I think you will enjoy it.
http://valleycresttakeson.com/watermanagement/trends/how-much-will-you-pay/