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Business, STEM

Tech Note: Shade Balls Help Conserve Water

4-inch Black Plastic Shade Balls Source: Accuweather

4-inch Black Plastic Shade Balls Source: Accuweather

At my last count, 14 active wildfires are raging in California. So many that it prompted me to call my uncle in Sacramento to ensure that his property and family members are not in harm’s way.  After confirming that he was in the clear, our conversation turned to a related topic: the California drought.

The fact that California is in a drought does not make the situation with wildfires any better. It does, however, call for prudent water management. If you aren’t already aware, the state produces a significant amount of food for the rest of the U.S.

According to the California Department of Food and Agriculture, California’s agricultural exports in 2013 were about $21.24 billion in value, representing a 15 percent increase over the previous year. In terms of value, California’s top three agricultural exports are almonds, dairy and dairy products, and wine. California’s share of total US Agricultural exports for 2013 was 14.7 percent or slightly more than the 13.1 percent share reported the previous year.

As we continued our phone conversation, my uncle indicated that he has had to invoke some water restrictions around his home to ensure that there is enough water to take care of the physical needs inside of his home. The property is serviced by a groundwater well. This is also the first time in 50+ years that this Californian has had issues with his well in the 45 years that he has been in his home.

In 2014, Governor Jerry Brown asked Californians to cut their water consumption by 20%. Mandatory restrictions were put in place in 2015. Brown directed the state’s Water Resources Control Board to approve rules that force cities to limit watering on public property, encourage homeowners to let their lawns die and impose mandatory water-savings targets for the hundreds of local agencies and cities that supply water to California customers. [Ref 1]

Citing lack of success with voluntary reduction targets, Brown ordered water agencies to cut overall water use by 25 percent.

With agriculture being a large industry within the state, some of the farmers are beginning to switch their crops from those with higher water intensity to those that require less water to grow. Coming from a farming background myself, I definitely agree that some of the agricultural practices that have been in place for centuries certainly require some rethinking…and not just here in the U.S., but worldwide.

Therefore, when I heard about the shade balls that the Los Angeles Department of Water and Power (LADWP) are using to save water and slow the evaporation rates in one of their largest reservoirs, my eyebrows arched up! As it turns out, this utility has been using shade balls since 2008.

Mayor Eric Garcetti supervised the latest onslaught of 4-inch black plastic balls, bringing the total count to 96 million in the 175-acre reservoir. Located in Sylmar, the reservoir holds up to 3.3 billion gallons, enough to supply the city with drinking water for up to three weeks. [ Ref 2] Not only will the shade balls help reduce evaporation from the reservoir, they provide a “floatable cover” that shades and cools the water. This lessens the possibility of bacteria and algae growth. Another plus: less need to treat the water thereby reducing the reactions that can produce harmful substances.

According to LADWP, this project will help the agency comply with EPA’s water quality requirements, particularly the Disinfection By-Product Rule, while saving more than $250 million and 300 million gallons of water each year (enough to serve 2,760 homes) that would otherwise be lost to evaporation. An estimated savings of $28,000 a month in chlorine costs are also expected at this Los Angeles reservoir.

This project also brings together the best of business and STEM in the workplace, and more importantly, for a government agency. Consideration was given to using a single floating protective cover to meet the water quality standards. This alternative was ruled not possible or practical. Next consideration was given to splitting the reservoir into two with a bisecting dam and installing two floating covers. This option would have cost more than $300 million, and an additional $100 million would have been needed for operational adjustments and an additional reservoir to ensure reliable water service.

The selected alternative, shade balls, cost $34.5 million to deploy and achieve the same water quality results. At approximately $0.36 each, shade balls are an innovative money-saving, water-quality tool that requires no construction, parts, labor or maintenance. They also have a 10-year expected lifespan before replacement. [Ref 3]

LADWP biologist, Dr. Brian White, conceptualized this innovative, cost-effective, in-house solution.

I was especially interested in why the agency chose black balls over some bright dayglow color? The agency was contacted to find out the material of construction and if there is a rhyme or reason to the chosen color. Albert Rodriguez of LADWP indicated that the balls are made of high density polyethylene (HDPE) and are approved for contact with drinking water. This is the same material that is used in one-gallon milk cartons.

As far as the color, carbon black promotes an added layer of UV protection from the sunlight. Using other colors would require dies that leach into the water. The ball material is fully recyclable whenever it is removed for replacedment.

References

1.     California Approves Mandatory Water Cutbacks To Combat Drought, last updated 05/07/2015, contributed from the Associated Press, http://www.huffingtonpost.com/2015/05/05/california-water-cutbacks_n_7218696.html

2.     Why Did L.A. Drop 96 Million ‘Shade Balls’ Into Its Water?, by Brian Clark Howard for National Geographic, August 12, 2015, http://news.nationalgeographic.com/2015/08/150812-shade-balls-los-angeles-California-drought-water-environment/

3.     Los Angeles Reservoir Shade Ball Fact Sheet, Los Angeles Department of Water and Power, http://www.ladwpnews.com/external/content/document/1475/2583090/1/LA%20Reservoir_ShadeBallFactSheet.pdf

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About Vi Brown

Vi is principal and CEO of Prophecy Consulting Group, LLC, an Arizona firm that provides business and engineering services to private and public clients. Prior to establishing her consulting practice in 2001, Vi worked with Motorola, Maricopa County Government, Pacific Gas & Electric, CH2M Hill, and Procter & Gamble. As an adjunct faculty member, Vi teaches undergraduate calculus classes and graduate level environmental courses. She is also a professional speaker.

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