SPEECH
Waste not, want not. In this era of environmental deterioration and climate change, such words instil a measure of challenge to any engineer, and sometimes add on a degree of inspiration as well. In this spirit, Orange County’s Groundwater Replenishment System is certainly one of those inspired creations. Treating secondary effluent may not sound as glamorous as perhaps other visually aesthetic or physically imposing engineering projects, however what it may lack in glamour, it makes up for in environmental consciousness. Mother Nature couldn’t have asked for a better friend. The GWR system, the largest water purification reuse project of its kind in the world, generates a new supply of pure water to meet the needs of half a million people; water as pure as distilled water.
For a fairly arid region in California, this system is definitely a boon and ensures the county’s groundwater basin doesn’t go dry – to the tune of 70 million gallons per day. Wastewater effluent, normally a resource that is just dumped into the ocean, represents the sort of wastefulness that Orange County simply cannot afford, given the increase in local demands for water added to the diminished supply of water imported from outside.
However, rather than being focused on quantity, the GWR system is more concerned about quality. The water that is recharged into the basin is of such high quality that some impurity is actually added thereafter in the form of minerals. It all begins with a low‐pressure microfiltration process, preparing the water for the reverse‐osmosis step. Not satisfied with this, the system then utilizes ultraviolet light and hydrogen peroxide to treat the already super‐pure water. Oh, and did we mention just how energyconscious the whole system is? With structures that have been designed to accommodate solar power, the GWR system uses variable‐frequency drives for added efficiency; cast‐in‐place drilled concrete piles to reduce vibration and sound; and reduces saltwater intrusion into the basin while lowering the output of wastewater into the ocean.
For its socially and environmentally conscious design, invaluable contribution to the county’s water supply, and the comprehensive nature of its water treatment, the American Society of Civil Engineers is proud to recognize the Orange County Groundwater Replenishment System as OCEA Award of Merit contender.