Southwest Harbor's water is pumped from Long Pond. It's so clean that the manager of the water and sewer district thinks some of the treatment it's getting is unnecessary, and may even be making the water quality worse. ISLANDER FILE PHOTO

Can chlorination make water worse?



SOUTHWEST HARBOR — After researching the purification methods being used at the town’s water treatment plant, Water and Sewer District Manager Steve Kenney is convinced much of what happens there is unnecessary.

“I didn’t want to jump to conclusions before getting the plant running as designed,” he said from the plant on Long Pond Road recently.

But, as Kenney had suspected, the filtration system seems to be introducing a problem into the town’s water that doesn’t exist when the raw water is pumped from Long Pond into the plant to be treated.

“Our raw water quality is superior,” said Kenney who was hired by the town in late 2015. “When I got here I didn’t know what this plant was doing. We’re spending a lot of money, using a lot of chemicals and a lot of energy to do nothing.”

If Kenney’s calculations are correct in the unnecessary use of electricity and chemicals, the town could be saving about $2,000 per month. Since the current treatment system was installed and completed in 2010, that adds up to at least $200,000 of possible overspending in the last eight years.

This figure does not include the cost of installing the blower system that was designed specifically for the plant, according to Kenney, and may serve no purpose other than to remove chemicals that don’t need to be added in the first place.

In an update to the Southwest Harbor Water and Sewer District Board of Trustees presented in February, Kenney outlined how the current system introduces a problem, eradicates it by 99 percent and then re-introduces it to the water that goes into the public system.

“After reading the info I had on the background of the Air Blower system it was clear that they worked as designed but didn’t resolve the problem,” Kenney wrote in a report. “They basically create DBPs (disinfection byproducts) by adding hypochlorite and caustic soda to the filtered water. The DBPs are then blasted with a bubble bath, ‘knocking’ the chlorine bond free from the organics and causing them to dissipate into the atmosphere through ventilation ducts and fans.

“Test [sic] show that DBPs are created and removed up to 99 percent,” the report continues. “Unfortunately, the TOC (total organic carbon), level stays the same and all this operation does is clean the carbon free of the chlorine that was added. The carbon then reforms into another batch of DBPs as it is exposed to the hypochlorite injected in the finished water room.”

In addition to eliminating what he considers an unnecessary and expensive first step, Kenney would like to see the town use a chemical other than chlorine as the final treatment step before the water goes out to the public system.

“It makes no sense to treat the water when there is nothing in there to begin with,” said Kenney told the Islander, referring to the current practice of adding hypochlorite, a liquid chlorine, to the water. “When chlorine hits the organics it binds to them to form disinfection bi-compounds.”

The district’s board of trustees is “seriously looking into” Kenney’s recommendation to shift away from chlorine, according to Lee Worcester, chairman of the board. A final decision has not yet been made, he said.

Kenney said he has spoken with the water treatment crews in Bar Harbor and Portland. The public water systems in both those towns are treated with chloramines rather than chlorine. Chloramines react more slowly than chlorine, but stay active in the water they are treating longer. Water treated with chloramines can be used for drinking, bathing or cooking because the body’s digestive system neutralizes it before it reaches the bloodstream.

In the case of the town’s water, DBPs created include Trihalomethane (THM) and Haloacetic Acids (HAA5), which the United States Environmental Protection Agency considers possible carcinogens.

The EPA has established a Maximum Contaminant Level (MCL) for total THMs in public drinking water systems. The MCL for total THMs is 80 parts per billion (ppb).

These types of carcinogens are believed to increase the chances of developing cancer in the body’s filtering organs with enough exposure, according to Kenney.

The standard is based on an average daily intake of two liters (0.53 gallons) of water per day by a 70-kilogram (154-pound) adult for a chronic time period. Therefore, exposure at or below the state drinking water standard for chloroform of 70 ppb is not anticipated to result in either adverse non-cancer health effects or cancer, according to a report written by the New Hampshire Department of Environmental Services.

“Why put them out in the system if you don’t have to?” Kenny asks. “Why create THM if you don’t need to?”

In 2018, once in late summer and again at the end of the year, the town was required to post a public notice in the Islander warning residents the level of THM was higher than allowable standards in the town’s public drinking water.

A reading of 92 ppb was taken last March and one of 91 in June of last year. In December 2018, a reading of 83 was recorded.

Data is based on averages and if the numbers read high more than three times, the average is expected to be too high to stay within the standard.

All of the high readings were taken at the end of the public water line on Seawall Road, where the chlorine added to the water at the treatment plant has had time to bind to the organics in both the water and the pipes along the route to create the higher number.

According to Kenney, the negative affects of chlorine increase over time, depending on how long the chemical has to bind to the organics in the water or pipes.

In order to keep the numbers low, employees of the district flush the lines occasionally to prevent the chlorine from sitting and continuing to bind with organics to create more of the unwanted biproducts.

Sarah Hinckley

Sarah Hinckley

Sarah Hinckley covers the towns of Southwest Harbor, Tremont and neighboring islands. Send story ideas and information to shinckley@mdislander.com.

Leave a Reply

Your email address will not be published. Required fields are marked *