Why Are 96,000,000 Black Balls on This Reservoir?

Summary

The video script explores the 96 million shade balls covering the Los Angeles Reservoir, debunking myths about their purpose. The balls, filled with water to prevent wind displacement, primarily block sunlight to inhibit the formation of carcinogenic Bromate from Bromide in the water. Made of food-grade plastic with carbon black for UV stability, they also reduce algae growth and evaporation, offering environmental and economic benefits.

Takeaways

• 🌞 Shade balls are used primarily to block sunlight from the water in the Los Angeles Reservoir, not to reduce evaporation as commonly believed.
• 🏗️ The LA Reservoir has the largest collection of shade balls, with a staggering 96 million balls in use.
• 🧑‍🔧 The balls are partially filled with water to prevent them from being blown away by high winds and to maintain their position in the reservoir.
• 🚤 Navigating through the shade balls is difficult due to their close-packed structure and the buoyancy they provide.
• 🔑 The real purpose of the shade balls is to prevent the formation of Bromate, a carcinogenic substance, by blocking sunlight which reacts with Bromide and disinfectant Chlorine in the water.
• 💧 Bromide, naturally occurring in the water, becomes harmful when disinfected with Ozone, leading to Bromate formation, a process accelerated by sunlight.
• 🔬 The discovery of Bromate formation in the open reservoir led to the implementation of shade balls as a solution to maintain water quality.
• 🟢 The black color of the shade balls is crucial for blocking light and is made from safe, food-grade high-density polyethylene with carbon black for UV stability.
• 🌡️ Contrary to expectations, shade balls have a cooling effect on the water due to their insulating properties, reducing the temperature under the balls.
• 🌿 The balls also help in controlling algae growth by eliminating the need for as much Chlorine, as sunlight is the primary factor for algae proliferation.
• 💰 The cost of the shade balls is offset by savings in chemical use and reduced evaporation, making them a cost-effective solution.
• 🔄 The shade balls are recyclable and have a lifespan of at least 10 years, providing long-term benefits for the reservoir.

Q & A

What are shade balls and what is their primary purpose?

Shade balls are high-density polyethylene spheres used to cover water reservoirs, primarily to block sunlight and prevent the formation of bromate, a harmful chemical, rather than to reduce evaporation as commonly believed.

How many shade balls are there in the LA Reservoir?

There are 96 million shade balls in the LA Reservoir, making it the largest collection of these balls in the world.

Why are the shade balls black?

The shade balls are black to block all light from reaching the water, which is necessary to prevent the formation of bromate. The black pigment also contains carbon black, which makes the plastic durable in sunlight for at least 10 years.

What is the material used to make shade balls and is it safe for drinking water?

Shade balls are made from high-density polyethylene, the same material used in food-grade plastic like milk jugs. The black pigment is safe for contact with drinking water.

How do shade balls help with the issue of Bromide in the water?

Bromide, when exposed to sunlight and disinfected with chlorine, can form carcinogenic bromate. Shade balls block sunlight, preventing this reaction and thus reducing the formation of bromate.

What was the initial reaction to the idea of using shade balls in the reservoir?

The initial reaction was that it seemed a bit 'out there' or absurd, but it was not considered nuts, and it effectively addressed the issue of bromate formation in the water.

How do shade balls affect the water temperature and evaporation?

Shade balls absorb more energy and get hotter on top, but the bottom stays cool, and the air inside the balls acts as a thermal insulator. This results in a cooling effect and reduces evaporation by 80 to 90%.

What are the cost implications of using shade balls in the LA Reservoir?

Shade balls cost around 33 to 34 cents each, but their use results in savings from reduced chemical treatments and evaporation, potentially covering half the cost of the balls over their lifespan.

How do shade balls impact wildlife, particularly birds?

Shade balls deter birds and wildlife from landing on the water surface, which was one of their original uses as 'bird balls' to prevent animals from getting poisoned or interfering with operations like airports.

What alternative shapes have been considered for covering reservoirs, and why were they not chosen?

Hexagonal shapes were considered because they can lock together, but they were not chosen because they could stack up or perch on the reservoir's bank, which is not desirable as water levels fluctuate.

What other benefits have been observed from using shade balls in the LA Reservoir?

In addition to preventing bromate formation, shade balls have helped control algae growth by blocking sunlight, reducing the need for chlorine and improving water quality.