Office of Environmental Management

Pilot Test Shows Chlorine Effectively Disinfects Hanford Wells

December 4, 2018

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Before-and-after photos of screens on wells used to inject treated water back into the ground on the Hanford Site show how small amounts of chlorine can reduce biological growth, improving flow and groundwater treatment capacity.
Before-and-after photos of screens on wells used to inject treated water back into the ground on the Hanford Site show how small amounts of chlorine can reduce biological growth, improving flow and groundwater treatment capacity.

RICHLAND, Wash. – Whether it’s minerals in your sprinkler pipes or a buildup of grease in your kitchen drain, the concept and concern are the same: the need to improve flow by removing that material.

   Multiply that notion by hundreds of wells across the Hanford Site used to return treated groundwater to the aquifer, and you begin to see a dilemma for operators. When you take injection wells out of service for cleaning, you decrease the amount of groundwater the system can treat during downtime.

   Another option that shows promise is adding safe amounts of a material to outgoing water at treatment facilities to reduce buildup.

   “This buildup reduces the efficiency of our groundwater treatment operation,” said Mike Cline, director of EM’s Richland Operations Office (RL) soil and groundwater division. “The contractor and its workforce constantly seek to maximize the amount of contaminated groundwater we treat, and reducing buildup in pipes without taking wells out of service is a concept with great potential.”

   RL contractor CH2M HILL Plateau Remediation Company (CHPRC) began researching causes of buildup and possible solutions. Early tests have shown injecting small amounts of chlorine reduces the biological material obstructing the flow.

   “Our focus this year is on increasing efficiencies and the safe optimization of our extensive groundwater treatment network,” said Bill Barrett, CHPRC’s deputy vice president for the soil and groundwater remediation project. “This is an important way we can safely and efficiently treat more groundwater.”

   Injecting trace amounts of chlorine, similar to the amount you might find treating your home tap water, means workers may need to clean the wells out less frequently. Crews began the chlorine injections in October and will continue to monitor their effectiveness for the next several months.

 

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