The report confirmed less technical observations, but also delivered one surprise. The rate of subsidence var- ies by neighborhood, sometimes by as much as 15-20 percent. Critical Industry As an important economic driver in the region, water from EL47.5 and the Odessa Groundwater project will be critical to the farmers, families and businesses. Maybe farmers could have continued to draw water from the aquifer. Maybe, though, the aquifer might eventually go dry. That’s not a chance the region is willing to take. “It is only speculative what and when would have happened without the project,’’ Scharlau said. “However, trends have shown a consistently de- clining aquifer.”
Sustained groundwater pumping also leads to a multitude of other is- sues. Deterioration of water quality, increased pumping costs, drying up of wells, and reduction of water in streams and lakes are some of the consequences of overreliance on aquifers. So too is land subsidence, which is the gradual settling or sudden sinking of the Earth’s surface due to removal of subsurface materials. Subsidence occurs when large amounts of groundwater have been withdrawn. The layers within an aquifer compact and settle, resulting in lowering the ground surface. A study this year reported that 19 percent of the world’s population will be affected by land subsidence by 2040, accounting for 21 percent of the global GDP. One of the most extreme examples of land subsidence has occurred in California’s San Joaquin Valley , a large farming com- munity. Since the 1920s, excessive pumping of groundwater at thou- sands of wells has caused land to sink as much as 28 feet (8.5 meters). Eastern Virginia has also experienced land subsidence with overuse of the Potomac Aquifer. Like the Odessa project, officials have executed a plan to enhance sustainability of the region’s long-term groundwater supply. The solution, however, is dramatically different as it uses highly treated water that would otherwise be discharged into the Elizabeth, James, or York Rivers and treats it to meet drinking water quality standards. The water is then added to the Potomac Aquifer, which is the primary source of groundwater throughout eastern Virginia. A report in 2020 from Old Dominion University and NASA’s Jet Propulsion Laboratory found that Norfolk and Virginia Beach are subsiding at the rate of approximately 3.5 millimeters every year.
The U.S. Bureau of Reclamation said more than 700 irrigation wells were drilled in the Odessa region. In June 2017, the Washington De- partment of Ecology issued cease and desist orders requiring landown- ers to stop pumping groundwater. In December 2017, the Department fined landowners for illegally pumping more than 500 million gallons of groundwater from the aquifer to water 530 acres of crops that in - cluded potatoes, alfalfa, and timothy hay. Agriculture is an important component in the Washington state economy. The state is the third largest food and agricultural exporter in the United States, generating $10.6 billion in revenue across 39,500 farms and ranches. Water is a critical resource, and the Odessa Groundwater Replace Project will be instrumental in helping farmers maintain their livelihood. While a labor intensive and sophisticated solution, the project illus- trates a creative solution toward solving an infrastructure problem that faces many U.S. communities.
THOMAS RENNER writes on building, construction, engineering, architecture, and other topics for trade industry publications throughout the United States.
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october 2021 csengineermag.com
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